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					                  Department of Communication Engineering

Title:Adaptive Channel Control for Wireless ATM Networks
Principal Investigator:Chung-Ju Chang
Sponsor:National Science Council
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Keywords Wireless ATM, PRMA, Multimedia Handoff, Neural Fuzzy Wireless CAC,
            Hierarchical Packet Switch

      The project will design and implement adaptive channel control mechanisms for
a wireless ATM network supporting multimedia messaging services. Because of the
system complexity of the wireless multimedia ATM network, adaptive channel control
mechanisms considered in this project contain the design of a random contention
protocol for multimedia messaging services, the design of a multimedia handoff
strategy, the design and implementation of a wireless call admission control, and the
design of the channel access control for a packet-switch based hierarchical cellular
radio system. As shown in Fig. 1, a variant packet reservation multiple access (PRMA)
protocol involved with the concept of fuzzy logic control will be the major work of
the design of a random contention protocol for multimedia messaging services; a
multimedia handoff controlled with capability of fuzzy logic control will be the major
effect of the design of a multimedia handoff strategy; a neural fuzzy wireless call
admission con-troller will be the major achievement for the design of the wireless call
admission control; and a channel access control for a hierarchical cellular radio
system will be proposed to support more adaptive channel access service for wireless
ATM customer and improve quality of service..
NSC87-2218-E009-047

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Title:Design and Implementation of VBR Traffic Controllers for ATM Networks
Principal Investigator:Chung-Ju Chang
Sponsor:National Science Council
Keywords:ATM, Traffic Control, Signaling, Admission Control, Flow Control


       The ATM Forum classifies service categories into constant bit rate (CBR),
real-time variable bit rate (rt-VBR), non-real-time variable bit rate (nrt-VBR),
available bit rate (ABR), and unspecified bit rate (UBR) services. The CBR capability
is intended to support real-time applications requiring tightly constrained delay
variation such as voice, video, and circuit emulation; and the ABR capability can be
used to support applications which do not require stringent bound on delay variation
such as file transfer and e-mails. The mechanisms to guarantee quality of service
(QoS) for CBR applications and flow control for ABR connections are currently the
main research areas for ATM technologies.
       In this project, we shall study and design (1) traffic scheduling algorithms to
guarantee QoS of CBR (also valid for rt-VBR) applications, and (2) flow control
algorithms for ABR connections. The tasks include

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First Year:
1. Improve and generalize the Delay Monotonic with Bandwidth Reservation
(DM/BR) algorithm, which we had obtained some results, to multiple node case.
2. Analyze the latency, fairness, grouping method, and weight assignment scheme for
the hierarchical self-clocked fair queueing (H-SCFQ) algorithm.
3. Simulate the EPRCA flow control algorithm (suggested by ATM Forum as a
relative rate marking flow control algorithm for ABR traffic) and modify the
computation of fair share to improve the performance.
Second Year:
1. Further research of the DM/BR algorithm (possibly to make it applicable to all
service categories) and circuit design.
2. Further research of the H-SCFQ algorithm (possibly to reduce latency and
improve fairness) and circuit design.
3. Design high performance explicit rate marking ABR flow control algorithm.
4. Design other service scheduling algorithms.
Third Year:
1. Chip design for the DM/BR algorithm.
2. Chip design for the H-SCFQ algorithm.
3. Development of other scheduling algorithm.
Chip design for relative rate marking or explicit rate marking algorithm.
NSC87-2213-E009-116

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Title:Traffic Management and Signaling System for ATM Networks
Principal Investigator:Chung-Ju Chang
Sponsor:National Science Council
Keywords:ATM, Traffic Control, Signaling, Admission Control, Flow Control

      There are many research topics in high-speed networks providing multimedia
information services. In ATM networks, traffic control and management and signaling
system are two issues not being solved and still being studied and developed. This
project takes three years to analyze and design the traffic control and management
schemes for all kinds of CBR, VBR, and ABR services; and the schemes will finally
be implemented into VLSI chips to satisfy the real-time requirement and fulfill the
realization purpose. In the mean time, the study on signaling system, necessary for
carrying these traffic control and management messages between customer premise
equipments and node (or UNI), is also included. Thus, the first subproject will design
and analyze the traffic control for VBR services, using neural-net and/or fuzzy logic
techniques from time-domain or frequency-domain points of view. The second
subproject will study and design the signaling system using object-oriented design,
where the features of the signaling system include point-to-point cases,
point-to-multipoint cases, and virtural path services, etc. The study and developement
of signaling system will develope Service Specific Connection Oriented Protocol
(SSCOP), Q.2931, and Q.2971 based on AAL5 SAAL (Signaling ATM Adaptation
Layer). The third subproject is to design a service scheduling scheme for CBR

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services, which can satisfy the constrains of mean delay and delay variation; it also
designs a flow control mechanism for ABR services. The analytical approach is to
improve the delay monotonic with bandwidth reservation (DM/BR) algorithm and
apply the algorithm to the multiple node case; it will also analyze the hierachical
self-clocked fair queueing (H-SCFQ) algorithm for service scheduling mechanism.
NSC87-2213-E009-116

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Title: Market Survey Analysis and Forecast on Non-Voice Telecommunication
       Services
Principal Investigator:Chung-Ju Chang
Sponsor:Chunghwa Telecom Co., Ltd.
Keywords:Non-Voice Telecommunication Services, Market Survey Analysis, Market
            Forecast

      The project is to do the market survey analysis and forecast on non-voice
telecommunication services in Taiwan, as the telecommunication liberalization have
began. Based on some market surveys and the analytical methods, we hope to
understand the potential market that which non-voice telecommunication services
may exist. And we perform the feasibility study that the telecommunication operator
provides CATV services; the non-voice telecommunication services provision in
CATV networks are also included. In summary, the project contains:
1.Study non-voice telecommunication services contents and approaches in Taiwan.
2.Study the market capacity, grow rate,and growth factors of telecommunication
services, after telecommunication liberalization.
3.Via market survey analysis and forecast, find out the niche applications and/or
possible potential customers of the non-voice telecommunication services which may
be supported for network programming, customer service operator, and marketing as
references.
4.Establish and provide some analytical method and/or tool for non-voice
telecommunication services.
5.Feasibility study of telecommunication operator providing CATV services.
C87068

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Title:New MM-Wave Uniplanar RF Receiver and Sources
Principal Investigator:Chi-Yang Chang
Sponsor:National Science Council
Keywords:MM-Wave Receiver, MM-Wave Oscillator, Uniplanar Circuit

     This project will be finished in 3 years.
     Recently, the frequency of microwave and millimeter wave circuit goes higher
and higher. Therefore, the uniplanar circuit becomes more and more important. The
advantages of uniplanar circuit such as no via hole or wrap around processes, low

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parasitics, easy to make transition from one kind of transmission line to other kind of
planar transmission line. For example, the transitions between coplanar waveguide
(CPW) and coplanar strips(CPS), CPW and slot line, CPW and microstrip line, are
easy to built.
      First year, a Ka band millimeter wave receiver will be made which includes RF
section and IF section.. The RF section comprises a uniplanar low noise amplifier, a
uniplanar mixer. IF section comprises an IF amplifier, and IF filter.
      This receiver will be connected to a feeding structure of a leaky wave antenna
which is developed by subprogram 1 and 3. Since the structure of the antenna feed,
the uniplanar circuit is most suitable to make interconnection with it.
      In the second year of this program, a mm-wave uniplanar VCO will be designed
and fabricated. This VCO will be used as local oscillator of the mm-wave receiver,
and as the source of the transmitting antenna. This VCO will use either frequency
doubler approach or direct oscillating in the mm-wave frequency.
      In the third year, whole system will be integrated. In accordance with the
antenna developed for the system, the circuit developed in the former two years such
as receiver, local oscillator, transmitting source, etc, will be integrated together to
verify the system performance.
NSC87-2213-E009-107

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Title : Design of MM-Wave Uniplannar Subharmonic Mixer
Principal Investigator : Chi-Yang Chang
Sponsor : Chung San Institute of Science and Technology
Keywords : Uniplanar Mixer, MM-Wave Mixer, Subharmonic Mixer

       In this thesis we develop two basic types of uniplanar Ka hand subharmonic
mixers. The first type uses one anti-parallel diode pair to design the so-called single
ended subharmonic mixer. In this type of mixer, we design a diplexer and use a RF
grounded anti-parallel diode pair to meet the goal. The other type is called single
subharmonic balanced mixer. In this thesis, two kinds of single balanced subharmonic
mixers are developed. The first kind uses a wide band balun, two antiparalleldiode
pairs, and a bandpass filter at RF port. The second type uses the same balun as the
first kind, but replaces two anti-parallel diodes with two single diodes. All the circuits
can cover full Ka band.
NSC 87-2623-D-009-006

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Title:ATM-Based Multicode CDMA Transport Architecture for Wireless Multimedia
      Transmission Real-Time Optimal Adaptive Prediction of MPEG Video Via
      ATM Networks Using Pipelined Recurrent Neural Networks
Principal Investigator:Po-Rong Chang
Sponsor:National Science Council
Keywords:Wireless ATM Network, Multicode CDMA, Dynamic Spreading Code

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               Allocation

      This project investigates the development of ATM-based multicode CDMA
architecture for next-generation multiservices multimedia wireless personal
communication networks(PCN). ATM is the step in the evolution of switching
systems, with the promise of carrying multimedia service on a single wireless network.
It can offer constant bit-rate (CBR), variable bit-rate (VBR), and packet transported
services designed to support a rage of voice, data, video, and multimedia applications.
In this project, we are especially interested in the ATM in combination with CDMA
which can support the VBR multimedia services. Each individual connection (channel)
across the radio interface can be distinguished by the CDMA code allocated to that
connection. High data rates are achieved by allocating more than one code to a single
user in order to provide more than one channel for transmitting user‟s information
data. In other word, the service bit rate can be varied by varying the number of
CDMA codes transmitted in parallel, each with a fixed spreading factor, which carry
the data between them. This scheme is termed as a multi-code CDMA system.
Furthermore, in order to avoid the self-interference that a multimedia user employing
multiple codes may incur, the multiple codes to/from one user should be made
orthogonal. This particular spread coding scheme is called the concatenated
orthogonal/PN spreading code which is capable of subdividing a high rate stream
belonging a multimedia user into several lower basic bit-rate streams in order to meet
the channel transmission rate requirement. Meanwhile, the maximum available
number of codes in the multi-code CDMA system is still limited. Hence, a
cost-effective dynamic code allocation scheme has then been proposed to dynamically
assign appropriate number of codes to each user for achieving the maximum resource
utilization for multi-user multimedia services via the mobile radio channel. In addition,
a design of buffer requirement at a base station has been developed to compensate the
nondeterministic jitter delay resulted from wireline ATM network and the constant
propagation delay via wireless ATM network. Finally, the overall system will be
evaluated and examined by the real MacMind Director generated multimedia titles.
NSC87-2218-E009-046

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Title:Real-Time Optimal Adaptive Prediction of MPEG Video Via ATM Networks
       Using Pipelined Recurrent Neural Networks
Principal Investigator:Po-Rong Chang
Sponsor:National Science Council
Keywords:ATN Networks, MPEG Video, Pipelined Recurrent Neural Networks

     This project investigates the application of a pipelined recurrent neural network
(PRNN) to the adaptive traffic prediction of MPEG video signal via dynamic ATM
networks. The traffic signal of each picture type (I, P, and B) of MPEG video is
characterized by a general nonlinear autoregressive moving average (NARMA)
process. Moreover, a minimum mean squared error predictor based on the NARMA
model is developed to provide the best prediction for the video traffic signal. However,

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the explicit functional expression of the best mean squared error predictor is actually
unknown. To tackle this difficulty, a PRNN that consists of a number of simpler
small-scale recurrent neural network (RNN) modules with less computational
complexity is conducted to introduce best nonlinear approximation capability into the
minimum mean squared error predictor model in order to accurately predict the future
behavior of MPEG video traffic in a relatively short time period based on adaptive
learning for each module from previous measurement data, in order to provide faster
and more accurate control action to avoid the effects of excessive load situation. Since
those modules of PRNN can be performed simultaneously in a pipelined parallelism
fashion, this would lead to a significant improvement in the total computational
efficiency of PRNN. In order to further improve the convergence performance of the
adaptive algorithm for PRNN, a learning-rate annealing schedule is proposed to
accelerate the adaptive learning process. Another advantage of the PRNN-based
predictor is its generalization from learning that is useful for learning a dynamic
environment for MPEG video traffic prediction in ATM networks where observations
may be incomplete, delayed or partially available. The PRNN-based predictor
presented in this project will be shown to be promising and practically feasible in
obtaining the best adaptive prediction of real-time MPEG video traffic.
NSC87-2213-E009-149

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Title:High-Speed Two-Way Data Communications Over Multi-Channel Networks :
       Theory and Practice
Principal Investigator:Po-Ning Chen
Sponsor:National Science Council
Keywords:Multi-Channel Broadcast Networks, Two-Way Interactive Multi-Channel
            Networks, Network Frequency Allocation, Network Topology, Queuing

       Multi-channel broadcast network (MBN) is one of the existing popular
infrastructures that have been widely used in providing communication services.
Two typical examples are the networks that deliver CATV (Community Antenna
Television) and that provide applications on Trunking radio. In recent years, driven by
a growing demand of multimedia services and a fast expansion of Internet, the
traditional communications systems with poor bandwidth efficiency can no longer
fulfill users‟ requirements. As a result of lacking of bandwidth, research on high-speed
broadband network, such as ATM(Asynchronous Transfer Mode) network, is
precipitately finding its footing. Yet, it needs time and requires high cost to deploy
such a high-speed infrastructure, which has not been practical at current stage.
Therefore, it appears viable to re-engineer the existing multi-channel networks to
provide high-speed data communications. This leads to a new research topic focusing
in migrating MBN into the so-called Two-way Interactive Multi-channel Network
(TIMN), such as Internet Service on CATV networks.
NSC87-2213-E009-139

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Title:Traffic Control and Time-Bounded Service Technologies on Wireless Network
Principal Investigator:Po-Ning Chen
Sponsor:ITRI/CCL
          :
Keywords Wireless Local Area Network, Time-Bounded Service, Quality of Service,
            Distributed Coordination Function, Point Coordination Function

      With the advances in digital communications, the spread of portable computers,
and the need to users' mobility, wireless local area networks (LANs) have become an
emerging technology for today's computer and communication industries. Wireless
LANs have been used in environments, such as manufacturing floors, conventions
and historic buildings, where cable installation is expensive or impractical. In addition,
mobility also becomes possible with wireless LANs. Accordingly, the scope of the
IEEE 802.11 draft standard is the physical layer (PHY) and medium access control
(MAC) sublayer implementation. The IEEE 802.11 draft standard describes
mandatory support for asynchronous data transfer with optional support for
distributed time-bounded services, which is supported by distributed coordination
function (DCF) and point coordination function (PCF), respectively. At present, most
work on the implementation and performance analysis to-date has concentrated on the
DCF, i.e., asynchronous data service. In this proposal, we consider PCF for wireless
LANs to support packetized voice and video with minimal delay for an acceptable
quality of service (QoS), specifically to support time-bounded services. We shall
design and analyze communication protocols at MAC sublayer. We shall identify
various architecture and performance issues such as the maximum number of
time-bounded service stations allowed and quality of service for different applications
and propose our methods for analysis. The work from this proposal, as we expect,
should prove useful in the success delivering the time-bounded services in the
wireless LANs.
C87097

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Title:Channel Assignment in HCS
Principal Investigator:Po-Ning Chen
Sponsor:FarEasTone Telcommunications Co.,Ltd
Keywords:Hierarchical Cellular Structure, Channel Assignment, Microcell

      In this project, we consider a hierarchical cellular system (HCS) with two tiers
where macrocells in the high tier provide broad radio coverage, microcells in the low
tier support system capacity and both jointly serve users of different mobility. One
important issue in the system is how best a channel assignment scheme can be
designed to reduce the probability of new call blocking as well as hand-off call forced
termination. Th project is focused on the issue, in particular on development of
measurement-based dynamic channel assignment (DCA) schemes to overcome the
inter-tier interference in system. Specifically, we investigate in a system model
consisting of HCS, TDMA or FDMA , and DCA in both tiers the performance on

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system capacity, new call blocking probability, forced termination probability, etc.
C87219

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Title:Development of Mandarin Speech Recognition Systems
Principal Investigator:Sin-Horng Chen
Sponsor:National Science Council
Keywords:Mandarin Speech Recognition, Robust Speech Recognition, Robust
            Training Telephone Speech Recognition, Noise Compensation, Channel
            Bias Removal, Speaker Adaptation, Speech Signal Pre-Segmenation

       This project is to develop two continuous Mandarin speech recognition systems
for telephone and microphone inputs, respectively. All key issues related to the
developments of these two systems will be studied intensively. Research topics are
stated as follows. (1) For telephone speech recognition system: (a) In the first year, an
HMM-based, 1300-syllable, continuous-speech recognition baseline system will be
implemented. The method to combine base-syllable recognition and tone recognition
will be studied. Besides, an RNN-based speech segmentation method for noise
statistics estimation will also be studied. Finally, a medium-size word recognition
system will be developed. (b) In the second year, an embedded training to
simultaneously consider speaker, channel, and noise compensations will be studied.
Fast recognition using pre-segmentation and beam search techniques will also be
studied. (c)In the third year, system integration and test will be done. (2) For
microphone speech recognition system: (a) In the first year, a 200-speaker speech
database will be first recorded. An MRNN-based syllable recognition baseline system
will be implemented. Fast search using multi-level pruning technique will be studied.
(b) In the second year, speaker and microphone normalization methods will be studied
first. Then, a statistical language model will be incorporated to extend the system to a
continuous-word recognition system. A new recognition approach to specially
emphasize the transition part of speech signal will be studied.(c) In the third year, the
development of the speaker-independent continuous speech recognition system will
be finished.
NSC87-2213-E009-056

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Title:Speech Input and Output Interface of Computer for Blind User
Principal Investigator:Sin-Horng Chen
Sponsor:National Science Council
Keywords:Blind Persons, Isolated-Word Recognition System, Command Words,
            Network Access, Information Retrieval, TTS System, Dialog Input,
            Robust, Mail-Writing

     This project is to develop a speech input and output interface of computer for
blind users to access information through computer network. In the first year, a

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small-vocabulary, isolated-word baseline recognition system will be developed. The
vocabulary contains 200 command words required for network access and
information retrieval. It is a neural network-based system. Besides, the TTS system
developed in the previous project will be integrated into the system as a speech output
device. In the second year, we will improve the system in several aspects: increase the
vocabulary size to 100000 words, develop a dialog input mode, and make it robust to
speakers and microphones. In the third year, a mail-writing application by speech
input for blind persons will be developed.
NSC87-2213-E009-027

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Title:Analysis of Scanning Active Microstrip Antenna Array
Principal Investigator:Shyh-Jong Chung
Sponsor:National Science Council
Keywords : Scanning Active Array, Dual Slot-Coupled Microstrip Antenna,
             Injection-Locking Circuit, Beam-Switchable Active Array

       A novel scanning active microstrip antenna array is proposed and to be designed
in three years. In the first year, a dual slot-coupled microstrip active antenna was
proposed and analyzed by the method of lines. The antenna and the oscillator were
separately placed on two common grounded substrates, and were coupled through two
suitably designed slots. The microstrip path was used as not only a radiator, but also a
feedback network of the oscillator. Based on this antenna design, a beam-switchable
antenna array was implemented in the second year. The main beam of the array was
first designed in the broadside direction by suitably controlling the antenna couplings.
An injection-locking circuit, which was made of microstrip lines, was then placed on
the circuit substrate to lock the frequency and phase of each antenna . The locking
signal was tapped from the first antenna and enlarged by an FET amplifier. The
length of the microstrip line determined the phase difference between the adjacent
antennas, and thus determines the main-beam angle. By switching the on/off of the
FET amplifier, the array can operate in these two radiation modes. In the third year, a
frequency-scanned beam steering method will be proposed for the scanning active
array. A highly dispersive transmission structure is designed on the antenna as an
external injection-locking circuit. The main beam of the array is scanned by changing
the frequency of the injection-locking signal.
NSC87-2215-E009-064

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Title : Retrodirective Planar Antenna Reflectors for Applications in Intelligent
        Transportation Systems(ITS)
Principal Investigator:Shyh-Jong Chung
Sponsor:National Science Council
Keywords : Intelligent Transportation Systems(ITS), Retrodirective Reflector,
              Microstrip Antennas, Slot Antennas

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      A new type of retrodirective reflectors will be designed and developed, using
microstrip antennas and slot antennas. Each reflector contain several suitable
positioned and connected planar antennas. When a microwave/millimeter-wave is
incident upon this reflector, the returning fields from all the antennas are added
coherently over a wide range of incidence angles ( about 90~ 120 ) , thus resulting in
high microwave/millimeter-wave echo to the source point. In the future intelligent
tranportation systems, each vehicle will be equipped with a forward-looking and a
backward-looking microwave/millimeter-wave radars. Based on the radar echoes, the
computer in the vehicle can read the status of the environment ( including the
positions, the distances, and the speeds of the nearby vehicles, and the potential
hazards in the path ) , and then adopt suitable steps. Due to the low cost and
comformability of the structure, the proposed reflector can be mass-producted, and
can be affixed on the vehicles and on the man-made or topographic structures to
increase their radar echoes over a wide angle range, thus increasing the validity of the
judgments of the vehicle computers.
NSC87-2213-E009-115

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Title:Internet-Based Video Conference System
Principal Investigator:Wen-Thong Chang
Sponsor:National Science Council
Keywords:Video Conference, TCP-IP

NSC87-2213-E009-121

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Title:Motion Parameter Estimation with Wiener Filter in Three-Parameter Motion
       Model
Principal Investigator:Wen-Thong Chang
Sponsor:National Science Council
Keywords:Motion Estimation, Three-Parameter Motion Model, Wiener Filter

      Two-parameter motion model has been widely used in image compression
technology. However, the two-parameter motion model is still not sufficient to
describe the motion phenomenon of objects in real images. The two-parameter motion
model can only be used to describe the two-dimensional translatory motion. The
three-parameter motion model is more practical and can achieve better compression
efficiency. It can be of use for low bit rate image compression in the future. Based on
the three-parameter motion model, the Taylor series expansion is used to construct a
signal representation model to describe the relationship between the image signal and
the motion parameters from two successive pictures. This model describes the
relationship among the displace frame difference (DFD), the image gradient (G) and
the desired motion parameters. However, the image representation model is a

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nonlinear function. For practical implementation, this function must be linearized.
The purpose of linearization is to derive a modified DFD such that it is proportional to
the motion parameter estimation error. For this, methods are proposed to process the
original DFD such that it can be used in the linearized signal representation model. To
linearize, the high order expansion terms in the Taylor series are treated as expansion
error. Then, the Wiener filter is used to remove the expansion error to derive the DFD
suitable for linearized model. After Wiener filtering, the processed DFD will be
proportional to the motion parameter error. Then the direct inverse method can be
used to estimate the desired motion parameters.
NSC87-2213-E009-096

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Title:Scalable Coding With Multi-State Prediction and Progressive Quantization
Principal Investigator:Wen-Thong Chang
Sponsor:National Science Council
Keywords:Multi-State Prediction, Progressive Quantization, Scalable Coding

      This project investigates the application of scalable coding scheme in the
encoding structure with prediction. Scalable coding can make the operation of the
decoder very flexible and decoupled from the encoder to reconstruct the image with
various SNR depending on the amount of bit received. For the encoder, with the
Rate-Distortion relationship, depending on the transmission environment, rate control
can be more effectively applied. Therefore, for low bit rate environment, bit rate
adaptation coding can be more efficiently implemented. Multi-layer coding is one of
the earlier approaches for scalable coding. With multi-layer coding, the prediction
error in MPEG coding is transmitted in a hierarchical manner. The quantized DCT
coefficients are the basic layer. The quantization errors are divided into several
layers for transmission. However, during encoding, only the basic layer quantized
DCT coefficient is used for prediction. Therefore, it is still not a very efficient
scalable structure. Moreover, most of the bits are allocated to the basic layer.
The problem with scalable coding is that it is difficult to be implemented in the
predictive coding environment. Because, in predictive coding, the encoder must
maintain a state of the decoder for prediction. However, in scalable coding, the
decoder is allowed to have the freedom to reconstruct an image with various SNR and
resolution. Therefore, we will investigate a multi-state prediction scheme for the
encoder to track the state of the decoder such that scalable coding can be applicable in
the predictive coding mode. Due to the multi-state prediction, there will be multiple
prediction errors for transmission. For this, we will also need a set of progressive
quantizers to quantize these prediction errors such that the total bit rates can be made
as low as possible.
NSC87-2213-E009-090

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Title : Motion Estimation Based on Pyramid Data Structure

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Principal Investigator : Wen-Thong Chang
Sponsor : ITRI/CCL
Keywords : Full Search, Minkowski Inequality, Pyramid Data Structure

      The accuracy of the motion estimation has fundamental effect on the coding
efficiency of the motion compensated predictive coding . For the best accuracy , full
search is still widely used in the video coding application . Due to the high amount of
the required computation , for some real time application , several sub-optimal
algorithms are used . Therefore , designing efficient data processing sequence and
defining efficient measure for block comparison in order to reduce the computation
cost of the full search is an important research topic in video coding . This is
especially demanding for the real time and narrow bandwidth application such as
H.263 . For this , an efficient algorithm based on the pyramid data representation and
the hierarchical application of the Minkowski inequality is proposed . The pyramid
structure provides hierarchical layers for intermediate data storage . Based on the
intermediate data and the Minkowski inequality , an efficient hierarchical comparison
tree can be defined . Based on the tree comparison , decision can be made to judge
whether a block is to be processed or not such that the overall full search computation
can be reduced .
C87095

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Title:Dialect Identification Based on Broad Phonetic Classification
Principal Investigator:Wen-Whei Chang
Sponsor:National Science Council
Keywords:Dialect Identification, Broad Phonetic Classification, Hidden Markov
            Model

      a part of multilingual spoken language system, techniques are needed to identify
most standard dialects in order to route the user to the appropriate human or
information access system. For our study it is aimed to develop automatic
identification of three Chinese dialects: Mandarin, Hokkien, and Hakka. Irrespective
of dialect, an isolated Chinese character is pronounced as a syllable which can be
phonetically decomposed into a optional initial and a final sub-syllable. To distinguish
one dialect from another, we should investigate their differences in the inventory of
phonological units, the frequency of occurrences of these units, and the order in which
they occur in words. Prosodic patterns also differ significantly among dialects.
Recognizing this, we attempt to develop a dialect identifier which uses hidden
Markov models (HMMs) to take into account both the stochastic models of language
acoustics and the language modeling. As an initial step, we perform broad phonetic
class partitioning of speech using a continuous mixture HMM recognizer in
conjunction with a mel-scaled cepstral feature extraction process. Once incoming
speech frames have been identified as one of five broad phonetic classes, procedures
for modeling and identifying dialects can be formulated based on an ergodic discrete
HMM which describes the sequential statistics of broad phonetic classes in each of

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the dialects.
NSC87-2213-E009-039

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Title: Secure Speech Communication over Broadband Networks
Principal Investigator: Wen-Whei Chang
Sponsor: Military Industrial Development Foundation
Keywords: Defense information, Asynchronous Transfer mode, Traffic Management
             Sub-Project: Traffic Management Algorithms for Broadband Networks

       To transfer the rapidly increasing volume of defense information in real time
relies on deployment of broadband networks. Among several competing technologies,
many people expect broadband networks based on the asynchronous transfer mode
(ATM) technology to be widely deployed in the near future.
In addition to large volume, defense information has special quality of service
requirements such as security, real time delivery, and zero information loss. Secure
speech communication studied in this sub-project is an example. Speech compression
and security issues are investigated elsewhere. Here, we focus on the issues of real
time delivery and zero information loss.
       To achieve real time delivery and zero information loss, admission control is
indispensible. However, admission control is strongly affected by the traffic
management algorithm used. We shall develop and design and implement static
priority based and hybird frame and priority based traffic management algorithms in
this sub-project. The tasks are described below.
1. Static priority based algorithm: Since rate monotonic scheduling algorithm had
been shown to be the optimum static priority assignment scheme, we shall focus our
attention on this algorithm. We shall derive a necessary and sufficient condition of a
set of connections to be rate monotonic schedulable. Besides, we shall design
admission control algorithm and potential hardware implementation. We shall also
extend the results to an environment where packets are of variable length.
2. Hybrid frame and priority based algorithm: Virtual clock can guarantee the
throughput by allocating a minimum bandwidth to each connection. However, it has
problems in fairness and delay. On the other hand, stop-and-go and hierarchical round
robin, which are both based on framing technique, can achieve fairness and guarantee
delay bound but are less flexible because the frame length determines bit rate and
delay. In this sub-project, we shall try to combine the advantages of virtual clock and
framing technique to design a good service scheduling algorithm.
A87081

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Title:The National Science & Technology Program for Telecommunications
Principal Investigator:Chi-Fu Den
Sponsor:National Science Council
Keywords : Telecommunications, Wireless Communication, Broadband Internet,

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               Experimental Network

      Based on the decree of establishing “National Science & Technology Program”
in the final report of the Fifth National Science and Technology Congress, the
National Science Council (NSC) proposed “The National Science & Technology
Program for Telecommunications”(NTP).Two major topics have been identified in
NTP: Broadband Internet and Wireless Communication. The planning effort on
broadband Internet has been heavily coordinated with National Center for
High-Performance Computing of R.O.C., and a National Broadband Experimental
Network will be built to accommodate the future broadband Internet research
activities. The possible research activities will be focused on Broadband Infrastructure,
QoS Oriented Networking, and Broadband Applications. The wireless communication
planning effort will follow International Mobile Telecommunications 2000
(IMT-2000). Research activities will be focused on WB-CDMA WLL , 3G Mobile
Radio Systems and Wireless Internet and High Speed WLAN. Based on the above
research topics, NTP will coordinate research organizations so that the national
research resources are effectively utilized to improve the productivity of the
telecommunication industry.
NSC88-2219-E009-001

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Title:3D Sound Reproduction Via Two Loudspeakers
Principal Investigator:Shih-Fu Hsieh
Sponsor:National Science Council
Keywords:Virtual Reality, 3D Sound, Crosstalk Cancellation, Virtual Loudspeaker

      During these years, multi-media computers have became popular in
entertainment industry, such as VCD and computer games. Along this trend, virtual
reality, whether audio or video, will play an important role in the multi-media domain
in the future. In this proposal, we discuss how to reproduce the 3D stereo sound via
two loudspeakers in order to make audio virtual reality possible. In Dolby AC3, the
five channels audio system can also adopt our model to produce other three
loudspeakers virtually over the conventional two loudspeakers system.
      In the procedure of reproduction, the head related transfer function (HRTF)
determines the localization of the virtual sound source, so we can change the location
of virtual sound source by using different (HRTFs), as shown in Figure 1. This
approach provides the reproduction system a method to produce virtual sound source
at any position in 3D space, and creates an audio virtual reality space. During the
reproduction, the crosstalk between the loudspeakers and the listener‟s ears would
degrade the perception quality of the virtual sound source. To overcome this problem,
we offer a method called „crosstalk cancellation‟ which can reduce the crosstalk
between the two loudspeakers and the two ears and equalize the sound to produce
exact virtual sound source.
      We will consider some different structures of crosstalk canceller and
investigate their performance, in the aspects of stability and implementation, which

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then aids us to design a virtual loudspeaker system and a moving sound system.
NSC87-2213-E009-119

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Title:Acoustic Echo Cancellation with Double Talk Detection
Principal Investigator:Shih-Fu Hsieh
Sponsor:National Science Council
Keywords:Double Talk Detection, Adaptive Echo Cancellation

      For teleconference systems, an adaptive acoustic echo cancellation(AEC) can be
used to eliminate echo signals. However, a double talk can degrade its performance
significantly. Therefore, we need to provide double talk detection and some
appropriate approaches to diminish this problem.
      A simple and precise method using power-level detection can be used to detect
the double talk. Analytical results on Echo Return Loss(ERL) and Echo Path
Loss(EPL) are derived. We also use the power-weighted approach to enhance the
detection effect.
      We propose step-size adjustment and filter coefficient-restore methods to assure
echo cancellation quality when double-talk is detected. A rigorous analysis on EPL is
performed to distinguish room impulse response variations from double talk. Finally,
computer simulations are provided to verify our statistical analysis.
      Because the cost of the floating-point algorithm is higher than that of the
fixed-point algorithm, we will also analyze and simulate the fixed-point NLMS
algorithms as needed in the consumer market.
NSC87-2213-E009-067

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Title:Millimeter Wave Quasi-Optical Solid State Array Source
Principal Investigator:Christina Jou
Sponsor:National Science Council
Keywords:Active Antenna Array, Grid Oscillator, Monolithic, Hybrid

      Current research interest in milli-meterwave system is motivated by the
advantage such as smaller antennas, wider bandwidths, and better resolution for
imaging and radar system. However, this natural progression from the micro-wave to
millimeterwave spectrum has been hindered in many cases by the lake compact,
reliable, high power solid-state source at these wavelengths. The advances in device
technology make wafer-scale integrated power combining sources very attractive. In
addition, free-space power combining is more efficient at high frequencies than power
combining in guided wave structure, and transmi-tting and receiving system based on
monolithic implementation have the potential to be smaller, lighter.
      Quasi-optical techniques spurred the development of active integrated power
combiner in 1980‟s 1990‟s. As the operating frequency increases, the available power
from solid state devices decrease. Therefore, power combining of solid-state devices

                                                                                                     15
using quasi-optical techniques in the millimeterwave region became an important
issue. There are two different approaches for quasi-optical power combining. One is
the active antenna approach and the other is the grid approach.
      The advantage of active antenna is:(1) increasing the effective length of short
antenna (2) increasing the band-width (3) decreasing the mutul coupling between
array elements (4) improving the noise factor. In the 1995 project, we had
successfully demonstrated a 2×1 active antenna array. These circuits were fabricated
on Duroid substrates with a dielectric constant of 2.2 and a thickness of 20 mils.
From the forgoing advantages, we can see active devices and passive patch antenna
fabricated on the same substrate can improve antenna performance, The technology of
monolithic micriwave integrated circuit is mature, and makes the approach promising.
In the 1994 project, we had successfully demonstrated the “16 MESFET planar
oscillator grid array at GHz”[6]. In that project we had learned from design,
frabrication and how to test the whole circuit, and how to use the nonlinear CAD tool
to simulate the learned that the oscillation frequency was limied mainly due to the ft
of the MESFET and the device packaged figuration. We will design, fabrication and
test a monolithic quasi-optical resonante tunnneling diode(RTD) grid oscillator array.
This approach has the advantage of (1) in millimeter wave , quasi-optical combining
is more efficient than waveguide approach(2) Although, the output power of the RTD
device is small,(limited to microwatt), but, as well know, RTD has very high cutoff
frequency, therefore, we can monolithically integrated hundred and thousand of these
diode to increase its total output power. We will work with subproposal (1) to develop
the single discrete RTD device and after we optimize the device design then, we will
integrate monolithically many of these RTD device to form the RTD oscillator grid
array. So far, no one has ever published any monolithic RTD grid oscillator array
measured data. This RTD oscillator grid array experiment will be the first attempted.
Prof. N.C. Luhmann of U.C.Davis has fabricated successfully diode array in IEEE
MTT[7]. So we will cooperate with N.C. Luhmann for monolithic RTD grid array in
the third year of this proposal, and with help of Prof. C.P. Lee of NCTU. The
monolithic RTD oscillator grid array is possible.
      In order to improve the frequency and power performance, we will also in the
second year of this project, work with subproposal(1) to develop a higher frequency
transistor device such as HEMT or HBT, which have higher ft and higher power, in
order to elevate the oscillation frequency, and we will also use the chip from device,
so that we can have flexibility of redesign the grid configuration.
NSC87-2215-E009-063

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Title:FET & HBT Integrated Ku-Band Transmitter Chain for Commercial Mobile
       Satellite Communication
Principal Investigator:Christina Jou
Sponsor:National Science Council
Keywords:Satellite Transmitter, HBT, Ku-Band, Local Oscillator (LO), Mixer,
             Power Amplifier (PA), Phase-Locked Loop (PLL), Synthesizer


                                                                                                     16
      The technique of interesting FET and HBT devices on the save substrate gives
circuits designers the flexibility to take advantage of both the performance
characteristics of FET and bipolar device[1]. To be specific, HEMT‟s feature low
noise figures ,and HTB‟s feature low 1/f noise, high linearity, and output drive
capability. Thus, the integration of FET‟s and HBT‟s allows the realization of optimal
system performance.
      Ku-band transmitters are important components for mobile satellite
communication system. Low cost, high weight, small size and high reliability in such
system can be achieves through higher levels of circuit integration when the device
process becomes mature.
      This project processes an “FET and HBT integrated Ku-band transmitter-chain
for commercial mobile satellite communication”. This system consists of three
module(Fig.1): LO module, up-converter module and power amplifier module. This
project has two parts: (1)HBT device modelling (2)transmitter circuit design,
fabrication and testing.
      To setup the HBT device modeling, we will work with Prof. C. P.Lee of
National Chiao-Tung university Electronic department. Prof. Lee‟s lab. has been
developing high-performance HBT device for years We will work with the to develop
HBT microwave small-signal and large-signal equivalent circuit model. DC and the
scattering parameter measurement will be used to develop the model. Moreover, the
layout geometry and doping effect on the device cutoff frequency and breakdown
voltage will be studied. In this year‟s project, after the HBT equivalent circuit model
is developed, we will use them to develop the voltage-control-oscillator(VCO). In the
last year, we will integrate FET and HBT device circuit on a same transmitter-chain.
      As to the transmitter system circuit module: for the LO module, we will design a
13.2 GHz direct phase locked oscillator. Its advantage: Direct locking without using
frequency multiplier, and using phase locking results in the frequency error less than
0.0001%. About the up-converter module: a good RF output amplifer requires a mixer
with high 1-dB compression point, high 3rd-order interception point, low conversion
loss and loss and low noise figure. The main requirement for the PA module in this
communication system is: high linearity, high power, high efficiency. Class B and C
PA‟s are frequently used in this kind of application, and several methods to linearize
them have been investigated. One of the most-promising designs is the linear
amplifier using output circuit to cancel its harmonics.
      Finally, based on the foregoing discussion on the consideration of device and
circuit component, we will begin our second year, designing, fabricating and testing a
hybrid HBT PLL-VCO, a balanced resistive up-converter, and an X-band distributive
FET PA. The circuits will be similar to the design of MMIC circuit. Besides, with all
the FET modules completed, we will try to integrated them on one circuit. In the last
year, we will base on the first two year‟s experience and study to develop a new
integrated HBT and FET Ku-band transmitter.
NSC87-2213-E009-113

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Title:High-Q Millimeter-Wave Point Source Communications

                                                                                                     17
Principal Investigator:Jen-Tsai Kuo
Sponsor:National Science Council
Keywords:Microstrip, Leaky Wave, Resonator Cavity

      This three-year‟s proposal aims at developing a portable high-Q cavity
providing semi-point source for millimeter-wave wireless communication purpose.
The antenna or point source is made of a very high Q resonant cavity with a
microstrip on a dielectric substrate. The microstrip structure is excited, by proper
feeding circuits, to operate with leaky wave modes, called space wave mode. For a
leaky wave mode the EM energy is located in the region above the substrate, unlike
the dominant or bound modes in which the energy gathers in the substrate beneath the
metalic strip. When the space wave mode is excited,it radiates upwardly from horizon
with certain angle. Note that the four inner side-walls in addition to the air-dielectric
interface become reflection planes. The leaky waves are then guided to an output
aperture by a tapered waveguide. Let us name it as a leaky wave cavity. The main
differences between the leaky wave resonant cavity and the homogeneous box cavity
mentioned in the college text books are (1)oscillator and microstrip circuits are
fabricated on a dielectric substrate inside the cavity, (2)the resonant frequencies can
be properly predicted to be located in a band that the leaky waves exist and the
resonant frequency spectrum is then “purified”, unlike the multi-resonant frequency
peaks in a homogeneous cavity, and (3) an optimal length of the waveguide is
adjustable so that the wave can be guided, by tunning screws and a tapered waveguide
section, to the radiation aperture at the end of the waveguide. This millimeter wave
source can have a very high Q value.
      To accomplish the target, one should be capable of understanding and analyzing
the followings : (1) the mode spectrum of a closed (with top cover) microstrip in
millimeter-wave band; (2) the mode spectrum of a semi-opened (without top cover)
microstrip structure, i.e., dominant modes, higher order modes, and leaky wave modes;
(3) to locate frequency band or to choose certain structure dimensions that support the
leaky wave modes for specified frequency band; (4)the way to excite the leaky wave
modes; (5) the analysis and design of circuits including oscillators and transition or
feeding circuits for the excitation of leaky wave modes; (6) the propagation behavior
or path of the leaky wave modes in the cavity; (7) to locate the tunning screws that
can affect the EM energy distribution inside the cavity efficiently, in conjunction with
the adjust of the cavity size, to properly guide the waves to the output aperture. This
will make the whole system a high-Q semi-point source for use in millimeter-wave
imaging system.
NSC87-2213-E009-109

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Title:Miniaturized Resonator Filters with Improved Response Symmetry for Mobile
       Communications
Principal Investigator:Jen-Tsai Kuo
Sponsor:National Science Council
Keywords:Mobile Communication, Hairpin Resonator Filter, Miniaturization Design

                                                                                                     18
               Parallel Coupled Microstrip Filter, Microwave Integrated Circuit
               (MIC‟s)

      Miniaturization design of MIC„s has gained its attraction since the last few years.
This proposal aims at developing the design technique of reduced size coupled
resonator filters in 900 MHz band for mobile communication with improved
frequency response symmetry. It includes two subjects, namely, (1)microstrip-slot
coupled resonator filters; and (2)miniaturized hairpin resonator filters.
      The circuit structures of the two topics are developed based on the synthesis
procedure for parallel coupled strip resonator filters. Field theoretical analysis will be
invoked when necessary. The first goal is to improve the response symmetry. Simple
modal analysis of coupled microstrips should be done to determine a structure with
identical even-and odd mode phase velocities. The second is to properly layout the
circuit such that the total area occupied by the circuit can be minimized.
NSC87-2213-E009-111

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Title:Implementation of ISM Band Wireless Transceiver for Video Conference
       Signal
Principal Investigator:Yao-Huang Kao
Sponsor:National Science Council
Keywords:Video Conference, ISM Band, QPSK, Transceiver

       The purpose of this project is to construct and evaluate a high speed
digital wireless transceiver for video conference within three yaers. In the
first yaer, an ISM band transceiver is implemented. The power level is set
to be similar to that of DECT system of 250 mW . In order to match the
high speed request of n*1280Kbits,where n is the number of user group, the
10 MHz bandwidth of the transceiver with QPSK modulation is designed.
       The transceiver is divided into three parts. The first one includes the
power amplifier, antenna switch, filter, and low noise amplifier. The second
includes the synthesizer, VCD, and mixer. And the third part consists of
QPSK or QAM modulator. All the units are going to be built from
commercially available integrated circuits. This transceiver will act as a basic
tool in examining the performance of the video conference system in the next
two years.
       In the second year, 5.8GHz transceiver with QAM modulator is con-
structed. And in the third year, the system performances, including the
bit error rate and sensitivity is detailed examined.
NSC87-2213-E009-091

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Title:Fabrication of 20GHz Phase Locked Oscillator Using Dielectric Resonators(II)
Principal Investigator:Yao-Huang Kao

                                                                                                     19
Sponsor:National Science Council
Keywords:Dielectric Resonator, Varactor Tuning Dielectric Resonator Oscillator
         (VTDRO), Phase Locked Loop (PLL), Step Recovery Diode (SRD)

      In this project, a 20Ghz phase locked dielectric resonator(DRO) is fabricated
within two years. This oscillator is intented not only for the development of high
quality DRO in Taiwan industry, but for the precision local oscillator in the
downconverter of ROCSAT-1,which has serious Doppler effect in the downlink with
frequency centered at 18.45 Ghz. A 5 Ghz voltage tuned dielectric oscillator has been
finished in the first year. The circuits are packaged into several modules for easy
fabrication and testing.
      In this second year, the works include a prescaler(/4), Class-C amplifier for
multiplication, synthesizer, 5Ghz phase locked DRO and the integration and testing of
modules at 20Ghz. The phase noise is emphasized. The work is believed to have
crucial contributions to the electronic warfare, satellite communication, and consumer
industry in the country.
NSC87-2213-E009-114

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Title:Design of Switching Router with Quality of Service Guarantee
Principal Investigator:Tsern-Huei Lee
Sponsor:National Science Council
Keywords:Internet, Quality of Service, Switching Router

      Continuous rapid growth of the Internet and increase of multimedia applications
demand higher bandwidth within the Internet Service Providers to maintain the
quality of service (especially for real-time applications). One possible approach to
increase the bandwidth is to use the ATM network. However, ATM technology is not
mature at this moment to accomodate the traffic of (and replace gradually) current
Internet infrastructure. Instead, increasing the processing speed of current Internet
routers seems to be a reasonable migration path. Thus, combining switching and
routing technologies is currently under development of leading networking companies.
Some IETF drafts concerning switching routers include IP Switching by Ipsilon, Tag
Switching by Cisco, and Aggregate Route-based IP Switching (ARIS) by IBM.
      The purpose of this project is to design switching routers with quality of service
guarantee. The tasks include
First Year (Design of Switching Routers)
   1. Compare IP Switching, Tag Switching, and ARIS.
   2. Choose and improve the design philosophy of switching routers.
   3. Design and evaluate the performance of switching component (including
      architecture and buffer management schemes).
   4. Partition system software into modules (including protocol and system control
      software).
   5. Study RSVP protocol
Second Year (Quality of Service Guarantee)

                                                                                                     20
   1. Study and try to improve RSVP protocol
   2. Design service scheduling algorithms
   3. Circuit design of service scheduling algorithms
   4. Develop software modules (if possible)
Third Year (Chip Implementation)
   1. Improve service scheduling algorithms developed in the second year
   2. FPGA chip implementation of service scheduling algorithms
   3. Develop software modules (if possible)
       The goal of this project is to understand and develop the key techonoligies of
switching routers such as switch architecture, resource reservation, and service
scheduling algorithms. We expect to publish good quality papers in journals and
international conferences during execution of this project.
NSC87-2213-E009-123

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Title : Design of CBR Traffic Scheduling Algorithm and ABR Flow Control
       Algorithm in ATM Networks
Principal Investigator:Tsern-Huei Lee
Sponsor:National Science Council
Keywords:Asynchronous Transfer Mode, Constant Bit Rate, Available Bit Rate,
            Service Scheduling, Flow Control

       The ATM Forum classifies service categories into constant bit rate (CBR),
real-time variable bit rate (rt-VBR), non-real-time variable bit rate (nrt-VBR),
available bit rate (ABR), and unspecified bit rate (UBR) services. The CBR
capability is intended to support real-time applications requiring tightly constrained
delay variation such as voice, video, and circuit emulation; and the ABR capability
can be used to support applications which do not require stringent bound on delay
variation such as file transfer and e-mails. The mechanisms to guarantee quality of
service (QoS) for CBR applications and flow control for ABR connections are
currently the main research areas for ATM technologies.
       In this project, we shall study and design (1) traffic scheduling algorithms
to guarantee QoS of CBR (also valid for rt-VBR) applications, and (2) flow
control algorithms for ABR connections. The tasks include
First Year:
      1. Improve and generalize the Delay Monotonic with Bandwidth Reservation
         (DM/BR) algorithm, which we had obtained some results, to multiple node
         case.
      2. Analyze the latency, fairness, grouping method, and weight assignment
         scheme for the hierarchical self-clocked fair queueing (H-SCFQ) algorithm.
      3. Simulate the EPRCA flow control algorithm (suggested by ATM Forum as a
         relative rate marking flow control algorithm for ABR traffic) and modify the
         computation of fair share to improve the performance.
Second Year:
      1. Further research of the DM/BR algorithm (possibly to make it applicable to all

                                                                                                     21
        service categories) and circuit design.
     2. Further research of the H-SCFQ algorithm (possibly to reduce latency and
        improve fairness) and circuit design.
     3. Design high performance explicit rate marking ABR flow control algorithm.
     4. Design other service scheduling algorithms.
Third Year:
     1. Chip design for the DM/BR algorithm.
     2. Chip design for the H-SCFQ algorithm.
     3. Development of other scheduling algorithm.
    4.Chip design for relative rate marking or explicit rate marking algorithm.
NSC87-2213-E009-118

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Title: Secure Speech Communication over Broadband Networks
Principal Investigator: Tsern-Huei Lee
Sponsor: Military Industrial Development Foundation
Keywords: Defense Information, Asynchronous Transfer Mode, Traffic Management
            Sub-Project: Traffic Management Algorithms for Broadband Networks

       To transfer the rapidly increasing volume of defense information in real time
relies on deployment of broadband networks. Among several competing technologies,
many people expect broadband networks based on the asynchronous transfer mode
(ATM) technology to be widely deployed in the near future.
       In addition to large volume, defense information has special quality of service
requirements such as security, real time delivery, and zero information loss. Secure
speech communication studied in this sub-project is an example. Speech compression
and security issues are investigated elsewhere. Here, we focus on the issues of real
time delivery and zero information loss.
       To achieve real time delivery and zero information loss, admission control is
indispensible. However, admission control is strongly affected by the traffic
management algorithm used. We shall develop and design and implement static
priority based and hybird frame and priority based traffic management algorithms in
this sub-project. The tasks are described below.
1. Static priority based algorithm: Since rate monotonic scheduling algorithm had
been shown to be the optimum static priority assignment scheme, we shall focus our
attention on this algorithm. We shall derive a necessary and sufficient condition of a
set of connections to be rate monotonic schedulable. Besides, we shall design
admission control algorithm and potential hardware implementation. We shall also
extend the results to an environment where packets are of variable length.
2. Hybrid frame and priority based algorithm: Virtual clock can guarantee the
throughput by allocating a minimum bandwidth to each connection. However, it has
problems in fairness and delay. On the other hand, stop-and-go and hierarchical round
robin, which are both based on framing technique, can achieve fairness and guarantee
delay bound but are less flexible because the frame length determines bit rate and
delay. In this sub-project, we shall try to combine the advantages of virtual clock and

                                                                                                     22
framing technique to design a good service scheduling algorithm.
A87018

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Title: Scheduling Algorithms and Chip Design for Constant Bit Rate Traffic
Principal Investigator: Tsern-Huei Lee
Sponsor: Computer & Communications Research Labs of Industrial Technology
           Research Institute.
Keywords: Constant Bit Rate, Quality of Service, Priority Assignment, Admission
             Control, Scheduling

      In this project, we intend to develop traffic scheduling algorithms with chip
design for constant bit rate (CBR) services. CBR applications have to specify quality
of service (QoS) in terms of maximum cell transfer delay and peak-to-peak cell delay
variation. Since the QoS requirements requested by a CBR application is expected to
be satisfied deterministically, a rate-based scheduling algorithm seems indispensible
to handle aggregate CBR traffic.
      In this sproject, we adopt priority assignment schemes. We shall develop fast
admission control algorithms and schedulers for both static and dynamic priority
assignments. The working items are described below.
     1) Static Priority Assignment: We shall develop fast admission control for the
Deadline Monotonic (DM) Algorithm. In the DM algorithm, connection i is assigned
a higher priority than connection j if the deadline of connection i is smaller than that
of connection j. We haved proved that the DM algorithm is the optimum static priority
assignment scheme for an environment where messages can be of variable lengths but
are segmented into multiple equal-length packets. All we need to do here is to
appropriately simplify the results to be used in an ATM switch and design admission
controller and scheduler chips.
     2) Dynamic Priority Assignment: Similarly, fast admission control will be
developed for the earliest deadline first (EDF) algorithm which has the best
performance among all scheduling algorithms. The admission control criterion
currently known is too complicated to be executed in real time. In this project, we
shall simplify the criterion and design chips for both admission controller and
scheduler.
      To guarantee end-to-end delay bound, it is very helpful to maintain the C
BR property inside the network. Therefore, we shall include traffic regulation i
n our scheduler design. Besides, we shall also investigate other feasible schedul
ing algorithms in this project.

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Title:Adaptive Beamformer for Signal Acquisition in a Slowly Varying Multipath
       Environment
Principal Investigator:Ta-Sung Lee
Sponsor:National Science Council

                                                                                                     23
Keywords:Adaptive Array, Multipath Coherent Interference, Beamforming

      The linearly constrained minimum variance (LCMV) beamformer is an effective
signal extraction technique in spatial domain. In principle, the algorithm drives an
array receiver to form a main beam for extracting the desired signal, and nulls for
suppressing the interfering signals by minimizing the beamformer output power based
on the direction-of-arrival (DOA) estimate associated with the desired signal. The
LCMV beamforming algorithm has several types of implementation, all of which
cannot effectively handle coherent interference with an arbitrary array geometry.
      In this project, we will try to develop a new implementation of the LCMV
beamformer in a slowly varying multipath environment to achieve two goals. One is
to alleviate the performance degradation due to coherent interference, and the other is
to enhance the quality of signal acquisition. The enhancement of signal acquisition
means that the beamformer will simultaneously receive and constructively combine
the desired signal and corresponding coherent interference for increasing the effective
signal power, while suppressing the noncoherent interfering signals. In addition, we
will also try to develop a auxiliary beamforming structure capable of improving the
robustness of the beamformer against the errors of DOA estimates. We will ascertain
the efficacy of the adaptive array processor with computer simulation in a mobile
communication scenario. Theoretical performance analysis will also be presented.
NSC87-2213-E009-038

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Title:Enhancement of Sound Signal Quality in Teleconference with the Aid of
       Microphone Arrays
Principal Investigator:Ta-Sung Lee
Sponsor:National Science Council
Keywords : Distance Education, Teleconferencing, Microphone Array, Echo
              Cancellation

      With the advent of telecommunication networks, multi-point-to-multi-point
interactive communication schemes such as distance education and teleconferencing
have become popular. In such systems, the need of simultaneous transmission and
reception of audio and video signals increases the implementation difficulties.
      The major problem of distance education and teleconferencing is twofold. For
video signals, the channel bandwidth limits real-time transmission; for audio signals,
we have the time delay and echo problems - time delays cause overlapping of audio
signals from the distant terminal; echoes cause mutual interference of audio signals
between the distant and local terminals. In this project, we will try to exploit the
technique of microphone arrays to lessen the aforementioned problems of audio
transmission. Our viewpoint is based on the fact that a microphone array has the
distinctive features of directivity and adaptivity, with which we can suppress or isolate
the voice signal from the distant terminal to prevent it from leaking back to the
transmission system of the local terminal. This should greatly alleviate the tap length
requirement of the conventional adaptive echo canceller. On the other hand, a

                                                                                                     24
microphone array can enhance audio signal acquisition for the local terminal, and this
should help to boost up the SNR in audio transmission.
      This project follows the sequence of computer simulations, hardware
implementation and real field testing. Firstly, we will conduct computer simulations
on acoustic field of conference rooms and microphone arrays. Secondly, we will
implement a high quality real-time microphone array using high speed DSP cards.
Finally, we will perform field test to confirm the performance of the joint operation of
the microphone array and echo canceller.
NSC87-2213-E009-124

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Title:Millimeter Wave Imaging Array Design
Principal Investigator:Yu-De Lin
Sponsor:National Science Council
Keywords : Millimeter-Wave Imaging Array, Leaky-Wave Antenna, Planar
              Transmission Lines

      The purpose of this project is to design the millimeter-wave imaging antenna
arrays for the quasi-optical millimeter-wave vision system proposed in the main
project, which include the illumination antenna array and the imaging array. To be
compatible with the active circuits and the feeding circuits designed in other projects,
the antenna arrays will be based on the planar structures. The illumination antenna
array will be a leaky-mode antenna array based on planar transmission lines due to its
high efficiency and easy fabrication. The imaging array will be either a
frequency/mechanical-scanning antenna array or a two dimensional planar array,
depending on the active circuit design. This antenna array also needs to be compatible
with the focusing dielectric lens in another project. This project will expand three
years. In the first year, we will focus on the optimization of linear arrays and
investigation of novel approaches for the array. These works include: design of the
feeding structure, pattern analysis, and efficiency analysis of single antenna elements;
design of the feeding network for the array; antenna fabrication and measurement. In
the second year, we will integrate the antenna arrays with the lens system. In the third
year, the complete two-dimensional antenna arrays will be simulated and tested in the
quasi-optical vision system.
NSC87-2213-E009-108

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Title:Comparative Study of S-Band Antennas
Principal Investigator:Yu-De Lin
Sponsor:Tran System, INC.
Keywords:S-band Antennas, Microwave Communication S ystem

     There are many S -band antennas well -documented in the literature.
Yet, to meet the specific requireme nts of the microwave communication

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s ystem under consideration, some antennas are more suitable than
others. The purpose of this project is to investigate the S -band
antennas that are suitable for the microwave systems designed by the
TranS ystem Inc. After theoretical anal ysis of the antenna structures,
experimental measurements are performed to provide confirmation and
adjustment of the design formulas. The antennas will be fined -tuned to
meet the system specifications in the end.
C87031

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Title:Measurement Study of S and Ka Band Antennas
Principal Investigator:Yu-De Lin
Sponsor:Gem Tek Technology Co., Ltd.
Keywords: ISM band, Antennas, Microwave Communicat ion System

     ISM bands are prepared for the development of industry, science
and medicine. There are many antennas well -documented in the
literature. Yet, to meet the specific requirements of the microwave
communication system under consideration, some ante nnas are more
suitable than others. The purpose of this project is to investigate the
2.4GHz ISM-band antennas that are suitable for the microwave systems
designed by the Gemtek Technology Co., Ltd. After theoretical anal ysis
of the antenna structures, exp erimental measurements are performed to
provide confirmation and adjustment of the design formulas. The
antennas will be fined -tuned to meet the system specifications in the
end.
C87152

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Title:Performance Evaluation of Electromagnetic Shielding by Metal Screen
Principal Investigator:Song-Tsuen Peng
Sponsor:National Science Council
Keywords:Wire Meshes, Bigratings

      Electromagnetic shielding using metallic plate is a technique that reduces or
prevents coupling of undesired electromagnetic radiation into equipment, causing
undesired interferences. To reduce weight and cost, solid metallic materials are
replaced by wire meshes in practice. The shielding effectiveness of a wire mesh
depends on various parameters, such as, the frequency and polarization of an incident
wave, mesh size, and conductivity of metal wires, etc. In this proposal, the wire
mesh will be modeled as a metallic bigrating that is composed of two single metallic
gratings.The two single gratings may have different periods and different orientations,
and they are separated by a uniform dielectric layer. In the limiting case where the
uniform dielectric layer is absent, we have a structure belonging to the class of wire

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meshes; however, the uniform layer is included here for the sake of generality of the
structure and its presence will also be investigated with an aim at improving the
shielding effectiveness.
      The research work will be divided into two main parts: the scattering of plane
wave by a single metal gratings as a module and the treatment of a stack of the
modules for the bigrating structure as a whole. Mathematically, we have here a
three-dimensional boundary-value problem which requires the coupling of TE and
TM polarized waves. The principal investigators of this proposal had resolved the
inherent difficulties associated with such a class of problems and a rigorous theory of
plane wave scattering by a bigrating had been well developed by the principal
investigators.
      Specifically, we shall extend our previously results to the case of metallic
bigratings. We believe that our previous experiences with bigrating structures and the
concrete results obtained before will offer this research program a great benefit of
having a head start, so that the shielding effectiveness of metal meshes can be
rigorously and systematically investigated, as proposed here.
NSC87-2213-E009-125

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Title : Research on Electromagnetic Interferences and Their Prevention for
       High-Speed Rail (3)
Principal Investigator:Song-Tsuen Peng
Sponsor:Ministry of Transportation and Communications
Keywords : Electromagnetic Interference, High-Speed Rail, Electromagnetic
              Radiation, Harmonic Current, Ground Return Current System

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Title:On the Design of an Anti-Multipath/Anti-Interference Direct Sequence Spread
       Spectrum Receiver
Principal Investigator:Yu-Teh Su
Sponsor:National Science Council
Keywords : Spread Spectrum, Multipath Fading, Narrow-Band Cochannel
              Interference, Anti-Interference Receiver Structure

      Initially used mostly in military environments, spread spectrum (SS) techniques
is finding new civil applications in areas such as HF, mobile VHF/UHF
communications, and local-area wireless networks. Signal transmission in these
communication environments, however, are likely to experiences multipath fading
and narrow-band cochannel interference(NBCI). Although SS techniques are
inherently insensitive to these impairments, there are, nevertheless, times when the
processing gain may not provide the system with sufficient interference immunity.
This would be the case if the interference is too strong or if the bandwidth of the
interference is too large. The result is degradation of the bit-error-rate (BER)
performance and perhaps more seriously, the loss of the system's ability to acquire

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and maintain code lock. Multipath or cochannel interference immunity of a SS system
can be improved significantly by applying appropriate signal processing techniques
before the despreading process takes place.
      Coventional approach for mitigating these impairments is to insert a subsystem
which is solely responsible for interference suppression. We propose a new `total
solution' that integrates the interference suppression mechanism with the detection
and synchronization subsystems. The resulting new `smart' anti-interference receiver
structure is suitable for use in a wireless synchronous direct sequence CDMA system
that has to coexist with a narrowband wireless system such as AMPS. We shall
present the receiver architecture, analyze its performance, outline the operation
sequences in various operation modes.
NSC87-2213-E009-112

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Title:On the Code and Signal Designs of OFDM/CDMA Systems (II)
Principal Investigator:Yu-Teh Su
Sponsor:National Science Council
Keywords:Multipath Fading, CDMA, OFDM, Spread Spectrum, Error-Correcting
            Codes

      The spread spectrum multiple access (SS/MA) techniques have attracted a great
deal of interest recently, because they can offer larger capacities than those achieved
by other more conventional MA techniques. In addition to its MA capability, a SS
system also has inherent anti-multipath, anti-jam and anti-eavesdrop. Nevertheless, in
a multipath fading environment that is characterized by frequency-selective and/or
time-selective fading, to fully take advantage of the inherent anti-multipath capability
of the SS signal, complicated signal processing must be performed by the receiver.
Multi-carrier (MAC) transmission, which is more often referred to as Orthogonal
Frequency Division Multiplexing (OFDM), is known to be an effective measure
against selective fading. By increasing the symbol duration and simultaneously
transmitting multiple narrowband waveforms, MC signals do make the
communication link less sensitive to large delay spread or frequency selective fading
and narrowband interference. Therefore, the combination of MC and SS techniques
can provide enhanced anti-multipath and anti-fading capabilities of a multiple access
system.
      In evaluating an OFDM/CDMA system, many system design issues have to be
carefully examined and studied. For example, good baseband signal can results in less
stringent synchronization requirements and provides better performance; proper usage
of forward error-control codes will lead to superior coding gain and larger capacity.
Powerful codes with decoders of simple or modest complexity are available for
applications in wireless communications. Moreover, unequal error protection codes
can now be easily implemented to enhance the signal quality and serve the need of
multi-media transmissions. From the receiver‟s view point, synchronization and
equalization are always of great concern, especially the environment in which
wireless communications take place. To ease the burden of the receiving unit‟s

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synchronization and equalization subsystems, appropriate signal design in the
transmitting end is needed. On the other hand, our knowledge of the communication
channel will dictate the system design. Delay spread and Doppler spread are two
important channel parameters that affecting the choice of data rate, equalization and
synchronization method in particular. We also need good channel model and reliable
channel statistics in aiding our receiver design and assessing the system
performance.The purpose of the proposed effort is to investigate these design issues,
analyze related impacts, perform system design optimizations, present tradeoff,
recommend a feasible system architecture and provide our predictions of its
performance behavior. We will focus on the topics of signal, code design and
channel model establishment. Our analysis and simulation results are the essential part
of the system engineering in realizing an OFDM/CDMA system.
NSC87-2218-E009-049

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Title:ADSL Transceiver Signal Processing and Codes Technology
Principal Investigator:Yu-Teh Su
Sponsor:ITRI/CCL
Keywords:ASDL, Turbo Codes, DMT, Trellis Codes

      Asymmetric digital subscriber line (ADSL) is a modem technology that converts
existing twisted-pair telephone lines into access paths for multimedia and high speed
data communications. ADSL can expand the existing access capacity by a factor of 50
or more without new cabling. ADSL can properly transform the existing public
information network from one limited to voice, text and low resolution graphics to a
powerful, ubiquitous system capable of bringing multimedia, to everyone's home.
      The purpose of the proposed effort is to examine and evaluate various code
alternatives for use in ADSL transmission systems. We shall analyze their
effectiveness, their impact on system performance and related implementation issues.
      The modulation technology used in ADSL environment can be classified into
two categories. A single tone modulation scheme such as quadrature amplitude
modulation (QAM) is restricted to concentrating transmitted power in one frequency
band. On the other hand, a multitone modulation scheme such as DMT has the
flexibility of optimizing the power spectrum over more than one (disjoint) frequency
band. The latter is the preferred choice for many service providers. Sophisticated
combined modulation and equalization techniques that result in an end-to-end
channel having a predetermined spectral shape can also be achieved by multitone
modulation.
      Many applications envisioned for ADSL involve digitally-compressed video. As
a real time signal, digital video cannot use link or network level error control
procedures commonly found in data communication systems. Therefore, ADSL
incorporates forward error correction can dramatically reduce errors caused by
impulse noise, white noise and crosstalks. Powerful codes with decoders of simple or
modest complexity are available for applications in ADSL.
C87094

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Title:Anti-Jam Analysis of a Satellite CDMA System
Principal Investigator:Yu-Teh Su
Sponsor:Chung Shan Institute Science and Technology
Keywords:Nonlinear Equalization, Multiuser Detection, Satellite Communications

       There are several commercial satellite CDMA systems that are either in the
planing stage or being deployed. Rejection of wideband interference caused by other
co-channel users has been a subject of intensive research recently. However, no
investigation of anti-jam method for satellite CDMA systems can be found in the
literature. The nonlinear nature of the satellite channel makes coherent direct
sequence spread spectrum (DS/SS) signals very susceptible to jamming as a jammer
can easily inject PM and AM noise into the desired signal. The fact that the satellite
transponder does not possess the on-board processing capability makes the design of
an anti-jam (AJ) receiver even more difficult.
       We will suggest algorithms for suppressing jamming signal and design a
pre-distortion device (linearizer) to compensate the nonlinear distortion caused by
high power amplifier. Three types of jammers are considered, namely, partial time
pulsed jammer, continuous wave interference and narrow-band interference. The
purpose of the proposed effort is to provide system level design of a programmable
AJ software terminal for satellite DS/CDMA system. This terminal has an AJ mode
and a regular mode, each mode also can be divided into single access and multiple
access submodes. The design of a satellite AJ transceiver requires information about
the satellite coordinate, its antenna pattern, coverage area, transponder‟s gain control
method and high power amplifier characteristic in addition to the network traffic
statistic, system frequency plan, ground antenna gain and network structure. The
initial phase of the proposed effort will include the following tasks: i) link analysis, ii)
modeling of nonlinear satellite channel and analysis of pre-distortion method, iii)
receiver structure and AJ capability (maximum tolerable J/S and minimum required
S/J) analysis
C87100

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Title:Wireless Antenna and Filter Employing Multilayered Ceramic Technology
Principal Investigator:Ching-Kuang Tzuang
Sponsor:National Science Council
Keywords:Anti-Jamming, Beam-Forming, Interference, Wireless, Leakage

      Increasing demand for wireless data communication generates great number of
user per site, meaning a noisy or interfering enviroment is inevitable unless good
anti-jamming method(s) can be developed economically. This proposal presents a
novel technique that supresses the potentially hazardous interference of neighboring
wireless data terminals almost entirely.

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      The heart of the new anti-jamming technique is a new beam-forming array,
intergrated on a system of stratified ceramic (dielectric) substrate. The advance of the
multi-layered ceramic technology makes tjis proposal a viable approach. By proper
choice of the permitivity values and antenna layout, a pencile beam will emit from tje
antenna array and vice versa. Such highly directive beam is manifestation of laser at
desired microwave frequencies. Thereby a cluster of data terminals can benefit from
the nearly interference-free beams radiated from the crowed data terminals and
properly anchored in room, provided the signal leakages are in good control.
      This program will work in conjuction with ceramic hybrid technology in two
aspects. One is the definition of the multi-layered struvtures. Another is the design
tolerance with tje metalization, thin filmor thick film. The indoor antenna system is
divided into three phases of development, 1) the baseline antenna system design, 2)
fabrication and evaluation, 3)on site testing for anti-jamming capability and
performance assessment.
NSC87-2213-E009-131

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Title:Baseline MM-Wave RF Front-End Technology for MMV
Principal Investigator:Ching-Kuang Tzuang
Sponsor:National Science Council
Keywords : Active-Integrated Leaky-Mode Antenna, Microstrip, Uniplanar
              Technology, Transmission-Type Injection-Locked, Quasi-Optical
              Power Combining, Harmonic-Balance (HB) Analysis

      This proposal describes the basic research carried out to develop a baseline
leaky-modes active-integrated antenna (AIA) technology which originates from an
extensive research of a X-band microwave source module employing the leaky-modes
concept.
      The novel active antenna source module utilizes a microstrip as the radiating
element while adopting uniplanar technology for the active circuit design. The
microstrip is operated in the higher order odd modes, which are leaky modes and can
be efficiently excited by a proximity-coupled center-fed slotline on the same surface
of the uniplanar microwave-integrated circuit. The measured performance of an
X-band transmission-type injection-locked active integrated antenna source module
demonstrated that such approach was suitable for a linear array integration for
quasi-optical power combining. The harmonic-balance (HB) analyses of the proposed
active-integrated antenna agree with the measurements in both free-running frequency
and power level. The measured radiation patterns of the active-integrated antenna also
agree well with the theoretical predictions.
      The high antenna efficiency of greater than 75 % has been experimentally
verified for frequencies up to 26 GHz, revealing great success of the leaky-modes AIA
concept. By proper choice of structural parameters, material constants and novel AIA
configuration, the leaky-modes AIA is expected to work well at millimeter-waves as a
baseline technology, fulfilling the urgent needs of the RF front-ends of the MMV
(millimeter-waves vision) system.

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NSC87-2213-E009-106

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Title:Quasi-Optical Millimeter-Wave Vision
Principal Investigator:Ching-Kuang Tzuang
Sponsor:National Science Council
Keywords:Millimeter-Wave Vision (MWV), Leaky-Modes, Antenna Arrays, Power
            Combiner, Dielectric Lens, Display Apparatus

       An advanced millimeter0wave vision (MMV) technology employing active
leaky-modes antenna arrays is proposed. The millimeter-wave vision (MMV) is a lens
system, consisting of quasi-optical beam-forming power combiner, dielectric lens,
active scanning array receiver, mechanical scanner, signal processing unit and display
apparatus.
       The core technology resides in the following researches headed and conducted
by various professors:
(1) Baseline mm-wave RF front-end technology for MMV (Ching-Kuang C. Tzuang,
    NCTU)
(2) New MM uniplanar RF receiver and source (Chi-Yang Chang, NCTU)
(3) MM-waves imaging array design (Yu-De Lin, NCTU)
(4) Dielectric lens (Kuan-Kin Chan, NCTU)
(5) Advanced MM wide-band CPW-slotline transition (Chih-Wen Kuo, NSYSU)
(6) High-Q MM point-source (Jen-Tsai Kuo, NCTU)
(7) fabrication of micromachined active integrated antenna array (Jin-Shown Shie,
    NCTU)
(8) Laser scanning techniques and applications (C. L. Pan, NCTU)
       This proposal aims to deliver a Ka-band MMV system, capable of displaying
real-time image at the rate of 5 frames/sec and with resolution of approximately 100
by 60 pixels/frame. The MMV grouped efforts require three years to complete. The
impact of MMV on the technology development of so-called wireless communication
is enormous in at least three major areas of interests, namely, (1)active integrated
antenna array design and manufacturate, (2) applied microwave field theory and (3)
IF signal processing. The use of MM-waves band allows very wide spectrum
prohibited in microwave regime; hence a variety of modulation schemes and
anti-jamming techniques can be experimented in the advanced MMV system. We
present a proposal that encompasses a dual-use technology leading this nation to the
next century competing worldwide for advanced wireless communication technology
development.
NSC87-2213-E009-105

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Title: Evaluation and Measurement of Space Diversity Performance in Office
       Building Environment
Principal Investigator:Jenn-Hwan Tarng

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Sponsor:National Science Council
Keywords : Space Diversity Technique, Indoor Radio Propagation, Field
           Measurement

      Space diversity reception is an effective countermeasure to mitigate the effects
of fading without increasing transmitted power. In this research, a two- or three
dimensional radio propagation model is used to evaluate space diversity performance
in indoor environment. Meanwhile, the mechanism governing the indoor propagation
effects on the performances of horizontal and vertical diversity is explored.
Measurement is conducted to verify the prediction accuracy.
NSC87-2213-E009-148

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Title:Modeling of UHF Radio Wave Propagation in Urban Environment
Principal Investigator:Jenn-Hwan Tarng
Sponsor:Z-com, INC
Keywords:Radio Propagation, Field Strength Measurement, Urban Environment

      In this project, our aim is to model UHF radio propagation loss in urban
environment. Both the ray-transmission-matrix method and Walfish-Ikegami model
are employed to construct the proposed method. Furthermore, the proposed model
will be cooperated with digital maps to predict radio coverage.
C86008

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Title:Lloyd‟s Mirror Effect on Underwater Deteceion
Principal Investigator:Jenn-Hwan Tarng
Sponsor:National Science Council
Keywords : Space Diversity Technique, Indoor Radio Propagation, Field
              Measurement

      In this project, Lloyd‟s mirror effect is applied to analyze the effect of
underwater sound reflection on underwater sound propagation. First, analytical
models of surface reflections or diffusions are constructed to investigate underwater
sound propagation mechanisms in a shallow water environment. The image method
and Kirchhoff‟s approximation are employed to handle the boundary effects. We are
furthermore to analyze the recorded underwater sound signatures of different ships.
NSC87-2623-D009-001

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Title:R&D of an Intracavitary Microwave Hyperthermia Antenna
Principal Investigator:Lin-Kun Wu
Sponsor:National Science Council

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Keywords : Intracavitary Microwave Hyperthermia Antenna, Benign Prostatic
          Hyperplasia, Arterioscelerosis, Single-Catheter, Double-Catheter

      Design and analysis of a new intracavitary microwave hyperthermia antenna is
proposed. It is intended primarily for the treatment of benign prostatic
hyperplasia(BPH);it may also find application in the microwave balloon angioplasty
treatment of arterioscelerosis. Frequencies of operation considered include both 915
and 433 MHz ISM bands. In addition to the conventional single-catheter mode of
operation,characteristics of the antenna operating in a double-catheter configuration
will also be investigated. For the latter case,effects of the use of forced air or water for
surface cooling will be investigated.
NSC87-2213-E009-127

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Title:Dispersion Effects and Dispersion Compensation Techniques in Optically
       Linear Long-Distance Subcarrier-Multiplexed Video Transmission Systems
Principal Investigator:Winston I. Way
Sponsor:National Science Council
Keywords:Dispersion Compensation, Subcarrier-Multiplexed Systems

      This sub-project is responsible for analyzing and experimenting an optically
linear long-distance subcarrier-multiplexed video lightwave system (the nonlinear
optical effects will be covered by another subproject in our team). We will use
closed-form analysis and numerical simulations by (1) solving nonlinear
wave-envelope equation, and (2) using conventional communication theory approach.
We will first predict the fundamental distance limitation for SCM systems carrying
various modulation formats (AM-VSB, QAM, etc.). We will then design the
optimum parameters in dispersion-compensation fibers and chirped-grating fibers in
order to compensate the optical fiber dispersion effects. We will also carry out
experiments to verify the theoretical and numerical predictions. Our final goal is to
set a world record in the transmission distance for mixed AM-VSB and 64/256-QAM
video signals.
NSC87-2215-E009-003

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Title:Multiple Access in the Presence of Optical-Beat and Co-Channel Interference
       Using Walsh-Code-Based Synchronized CDMA Technique
Principal Investigator:Winston I. Way
Sponsor:National Science Council
Keywords:CDMA, Walsh-Code, Optical Beat Interference, Multiple Access, PON

     We shall analytically and experimentally demonstrate the feasibility of using
Walsh-code-based synchronized code-division-multiple access (S-CDMA) technique
to achieve multiple access in the presence of optical-beat interference (OBI). By

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taking advantage of the excellent orthogonality among Walsh codes, we shall
demonstrate that S-CDMA technique can be successfully used in lightwave networks
where strong OBI and co-channel interference are present. We shall also show that,
if each laser is modulated by a large CDMA signal, multiple access and significant
OBI suppression can be simultaneously achieved . Since no out-of-band clipping
tones were used to suppress OBI, not only additional nonlinear distortions can be
avoided, but also significant modulating power can be saved to maximize the system
power budget. This multiple access technique is expected be applied to WDMA
networks [1] using subcarrier-based common wavelength signaling, or PONs which
generally do not have wavelength control on uplink laser diodes [2-5].
NSC87-2215-E009-019

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Title:Design and Implementation of External Modulator-Based High Power CATV
       Lightwave Transmitter
Principal Investigator:Winston I. Way
Sponsor:National Science Council
Keywords:External Modulator, LiNbO3, CATV High Poser

      This two-year project is to develop an external-modulation-based high-power
(>100mW) optical fiber CATV transmitter. The transmitter is composed of three parts:
(1) a CW multi-quantum-well laser with output power >20mW, (2) a LiNbO3-based
external modulator which contains both a phase- and a Mach-Zehnder (MZ)
intensity-modulator, and (3) an erbium-doped fiber amplifier (EDFA) with a high
output power of >100mW. In addition to assemble and test the three parts, we will
design a novel RF pre-distorter to cancel the nonlinear distortions generated in the
MZ intensity-modulator, an optical dispersion compensation device which may be an
integrated part of an EDFA, and a wideband EDFA for dense
wavelength-division-multiplexing applications.
NSC87-2622-E009-005

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Title : Design of a Long-Distance (>200km) Subcarrier-Multiplexed Lightwave
       System Transporting Multi- Channel (>100ch) Video Signals
Principal Investigator:Winston I. Way
Sponsor:National Science Council
Keywords:Subcarrier-Multiplexed System, Video Distribution and Transmission

      The goal of this project is to transport a large number of subcarrier-multiplexed
(SCM) analog (AM-VSB) and digital (M-QAM) video signals over a > 200 km long
distance conventional single-mode fiber. We plan to use a high-power 1550 nm
transmitter (output power > 20 dBm) based on external modulator and a high-power
erbium-doped fiber amplifier (EDFA), together with two in-line EDFAs whose output
power can be adjusted between 15-20 dBm. We will focus on the following three

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theoretical and experimental studies: (1)in optically linear systems, study the effect of
optical fiber dispersion on long-distance SCM systems; (2)in optically nonlinear
systems (nonlinear mainly due to the high power EDFAs), study the effect of
self-phase modulation, Kerr, and four-wave mixing; and (3)in the above two types of
systems, study the usefulness of dispersion-compensation optical fibers and chirped
fiber grating. Our approaches include experimental and theoretical studies, and
building computer simulation models.
NSC87-2215-E009-002

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Title:Design and Implementation of External Modulator-Based High Power CATV
       Lightwave Transmitter
Principal Investigator:Winston I. Way
Sponsor:New Elite Technologies, Inc.
Keywords:External Modulator, LiNbO3, CATV High Poser

      This two-year project is to develop an external-modulation-based high-power
(>100mW) optical fiber CATV transmitter. The transmitter is composed of three parts:
(1) a CW multi-quantum-well laser with output power >20mW, (2) a LiNbO3-based
external modulator which contains both a phase- and a Mach-Zehnder (MZ)
intensity-modulator, and (3) an erbium-doped fiber amplifier (EDFA) with a high
output power of >100mW. In addition to assemble and test the three parts, we will
design a novel RF pre-distorter to cancel the nonlinear distortions generated in the
MZ intensity-modulator, an optical dispersion compensation device which may be an
integrated part of an EDFA, and a wideband EDFA for dense
wavelength-division-multiplexing applications.
C87150

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Title:Study of Echo Cancellation for Teleconference
Principal Investigator:Wen-Rong Wu
Sponsor:National Science Council
Keywords:Teleconference, Echo Canceller, Microphone Array

       In teleconferencing, the far-end sound will be fed back to the far-end through the
near-end microphone. This is the so called “echo”. This effect may seriously degrade
the sound quality. Thus, echo canceling has been an active research topic in
teleconferencing. The conventional approach to this problem is using an adaptive
filter to cancel the echo in the near-end. Since the echo is an acoustic response, the
required filter length is usually very long. This preclude the practical implementation
of an echo canceller. This project is aimed to develop high efficient echo cancellation
structures and their related adaptive algorithms. The main feature of our approach is
that we use a microphone array performing beam forming. This will effectively
reduce the length of the acoustic channel response. Then, we will develop fast

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adaptive algorithms that can accelerate convergence rate as well as reduce the
computational complexity. Finally, we will implement the echo canceller using the
ASIC design.
NSC87-2213-E009-122

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Title:Subband Kalman Filtering for Speech Enhancement
Principal Investigator:Wen-Rong Wu
Sponsor:National Science Council
Keywords:Subband, Kalman Filter, Speech Enhancement, AR Model, LMS

      Kalman filtering is an effective technique for speech enhancement, in which
speech signals are usually modeled as autoregressive (AR) processes and represented
in the state-space domain. Because parameter(including coefficient and driving-noise
variance) identification for AR processes and Kalman filtering require intensive
computations, practical implementation of this approach is difficult. This project
proposes a simple and practical scheme to overcome these obstacles. Speech signals
are first decomposed into subbands. Subband speech signals are then modeled as
low-order AR processes such that low-order Kalman filters can be applied. Finally,
enhanced subband speech signals are combined to form enhanced full-band speech
signals. To identify AR coefficients, prediction-error filters adapted by the LMS
algorithm are applied. Due to noisy inputs, the LMS algorithm converge to biased
solutions. The performance of the Kalman filter with biased parameters is analyzed.
It is shown that precise estimates of AR coefficients are not required when the
driving-noise variance is properly estimated. New methods for such estimates are
proposed. Thus, we can tolerate the biased AR coefficients and take advantage of the
LMS algorithm‟s simple structure. Finally we will calculate the computational
complexity and discuss the hardware implement of our method.
NSC87-2213-E009-120

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