Enhancement of Throughput for Single Hop WPAN’s using UWB- OFDM Physical layer

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					                                                       (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                           Vol. 9, No. 5, May 2011

   Enhancement of Throughput for Single Hop WPAN’s
          using UWB- OFDM Physical Layer
Ch. Subrahmanyam                           K. Chennakesava Reddy                              Syed Abdul Sattar
Department of ECE                          Department of ECE                                  Department of ECE
Scient Institute of Technology             TKR College of Engg. & Tech.                       Royal Institute of Tech. & Science
Hyderabad, India                           Hyderabad, India                                   Hyderabad, India
Email: subbunvl@yahoo.com                  Email: kesavary@hotmail.com                        Email: syedabdulsattar1965@gmail.com

Abstract— One of the significant and secure agents for              UWB radio communications and later the presentation on
the UWB (Ultra Wide Band) based alternative physical                concept of single Hop WPAN’s in brief. Finally in the
layer    for    WPAN’s       (Wireless   Personal     Area          simulations, major limitations of single Hop adhoc WPAN’s
Networks) is MB – OFDM (Multiband Orthogonal                        can be discussed.
Frequency Division Multiplexing). In this presentation, the
simulation ejaculates for single Hop WPAN depending                 A. Overview of WPAN’s
upon the OFDM UWB physical layer are expounded. In
this effect, the transmittal systems for the data
                                                                    Wireless Personal Area Networks (WPANs) capacitate the
progressions of 55 Mbps, 200 Mbps, and 480 Mbps are
                                                                    lower distant expedient connectivity among compact
applied because these three are correspondents for lowest
                                                                    consumer electronics and communication devices. The range
progression, the highest the compulsion rate and the
                                                                    of a WPAN is generally restricted to a radius of 10 meters.
greatest optional rate resultantly. We applied both 4mX
                                                                    The Bluetooth radio system has materialized as the first
4m and 10mX10m insular fields for the network regions
                                                                    electronic component representing WPAN applications with
for the single Hop sketches in the simulation designs. The
                                                                    its prominent elements of low power consumption, small in
prevalent functions of the single Hop WPANS like average
                                                                    size, and low in cost. Data weight for Bluetooth devices is
End – to – End Delay and Packet Failure Rate(PFR) and
                                                                    restricted to 1 Mbps for version 1.2, and 3 Mbps for version
Throughputs for the entire source – target oriented pairs
                                                                    2.0 with enhanced data rate (EDR), respectively. These data
are replicated by imparting the Qualnet network
                                                                    tariffs are adequate for streaming stereo’s audio, transmitting
                                                                    data or carrying voice communications, but they are not
Keywords- OFDM, Single Hop, Throughput, UWB, WPAN’s                 sufficient to back up for multimedia traffic. The IEEE
                                                                    802.15.1 Standard was extracted from the Bluetooth version
                                                                    1.1 Foundation Specifications, and was published in June
                     I.    INTRODUCTION                             2002.
Nowadays, we have the requirement for wireless
communication systems which could be manipulated at a huge          The next generation of consumer oriented compact electronics
amount of data progressions over short distance                     and communications devices will support multimedia data
communications so as to meet the sophisticated product              traffic that requires high data rates. These applications contain
outcomes in consumer electronics i.e. Camcorders, DVD               high-quality video and audio distribution, multi-megabyte file
Players, etc. The utmost utilization of high-end Wireless           transmissions for music and image files [1]. For example,
Personal Area Networks (WPANS) for short distances with             devices that will use high-rate WPANs include digital
improvised connectivity among consumable electronics and            camcorders, digital televisions, digital cameras, MP3 players,
interactive devices have got established more prominently           printers, projectors, and laptops, etc [1]. The requirement for
since 2000. Having been approved by the Federal                     communications between these multimedia-capable devices
Communications Commission (FCC) for the application of              leads to associated judicious type connections that warrant
Ultra- Wide- Band (UWB) on the unlicensed band in 3.1 –             data rates well in 3 excess of 20 Mbps and Quality of Service
10.6 GHz range, this enhances the extensive usage of high           (QoS) provisions with respect to guaranteed bandwidth [1]. To
speed WPAN systems (up to 480 Mbps) standing on a UWB               assimilate the required physical layer and MAC layer QoS
physical layer execution. The renowned IEEE 802.15.3. has           requirements, the IEEE 802.15 WPAN Working Group
been structured with the same high- rate WPANS by the               initiated a new group i.e. the 802.15.3 High-Rate WPAN Task
special interest group (SIG).                                       Group. The IEEE 802.15.3 Standard was framed to capacitate
                                                                    wireless connectivity of high-speed, low-power, low-cost,
In this methodological script, at first we begin with a             multimedia-capable consumer electronic devices [10]. The
comprehensive conception of a Wireless Personal Area                idea of adding high-rate strength to the IEEE 802.15 family of
Network (WPAN), next introduction of fundamentals for               standards was first incorporated in November 1999. The

                                                              114                              http://sites.google.com/site/ijcsis/
                                                                                               ISSN 1947-5500
                                                             (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                 Vol. 9, No. 5, May 2011
802.15.3 Task Group started their official work in March                  mentioned in the previous section,. The goals for this standard
2000, and 802.15.3 was finally accepted as an IEEE Standard               are to attain and obtain data rates of up to 110 Mbps at a 10 m
in June 2003. This Standard is not expected to be a plain                 distance, 200 Mbps at a 4 m distance, and higher data r at
enlargement of the IEEE 802.15.1 Standard because the MAC                 shorter distances [7]. Depending upon these criteria, various
needs is very variant.                                                    proposals were acceded in response to 802.15.3a. Most
                                                                          proposals favor the Ultra-Wide-Band (UWB) physical layer.
Conventionally, an IEEE 802.15.3 compliant WPAN engages                   UWB systems have shown their ability to satisfy such needs
in an unlicensed 2.4 GHz frequency range with an RF                       by providing data rates of up to several hundred Mbps. UWB
bandwidth of 15 MHz. The symbol progression is 11 Mbps                    was first used to directly modulate an impulse-like waveform
and applies to all specified modulation formats, including                with very short duration occupying several gigahertz of
QPSK, DQPSK, and 16/32/64 QAM [1]. Through the use of                     bandwidth. Two examples of such systems are Time-Hopping
multi-bit symbol modulation and channel coding, the                       Pulse Position Modulation (TH-PPM) and Direct-Sequence
attainable data rates can be in the amplitude from 11 Mbps to             UWB (DS- UWB). Imparting these conventional UWB
55 Mbps. a much higher data rate is required than that                    methods over the entire allocated frequency, band has many
specified in the IEEE 805.15.3 Standard, for applications that            disadvantages, including need for high complexity RAKE
involve imaging and multimedia, such as H.323/T.120 video                 receivers to capture multipath energy, high-speed analog-to-
conferences, home theatre, interactive applications, and file             digital converters (ADC) and high power consumption. These
downloading. To enumerate a project to facilitate a higher                considerations motivated a shift in the UWB system design
speed PHY enhancement correction to 802.15.3 for these                    method from initial ―Single-Band‖ radio that occupied the
applications, the IEEE 802.15 High Rate Alternative PHY                   entire allocated spectrum in favor of a ―Multi-Band‖ design
Task Group (TG3a) for WPANs was constituted. This                         strategy [2]. According to the FCC ―Multi-Band‖ schemes
alternative physical layer (alt-PHY) is intended as a                     divide the available UWB spectrum into several sub-bands,
supplement to the IEEE 802.15.3 range. To be supported by                 each one occupying approximately 500 MHz (which is the
the physical layer, a bit rate of at least 110 Mb/s at a distance         minimum bandwidth for a UWB system definition). As if it
of 10 meters is required. The transmission strength is ensured            were following the total of its bandwidth by interleaving
static by supervisory emission limits. An accumulating higher             symbols across different sub- bands, a UWB system can still
bit rate of at least 200 Mb/s at a distance of 4 meters is                organize the same transmit power. A narrower sub-band
required. Even at the expense of reduced operating distances,             bandwidth also calms down the necessity on the sampling rate
scalability to rates in excess of 480 Mb/s is expected. The Data          for ADCs consequently enhancing digital processing
rates in the actual proposals may be higher, data rates                   capability [2]. Multiband-OFDM (MB-OFDM) is one of the
mentioned above are minimums and most proposals favor the                 promising candidates for the alternative PHY layer
Ultra Wide Band physical layer implementation approach to                 implementation to facilitate WPANs. It combines Orthogonal
realize the desired system specifications.                                Frequency Division Multiplexing (OFDM) with the above
                                                                          described multi-band method activating UWB transmission in
To dispatch information over comparably lowest destinations               order to inherit all the strengths of an OFDM technique which
among a few participants [10], Wireless personal area                     has already proven its unique role in wireless communications
networks (WPANs) are utilized. A WPAN is distinguished                    systems (ADSL, DVB, 802.11a, 802.16.a, etc) [2].
from other types of data grids. In that, communications are
normally decentralized to a minute area that literally covers                                II.   SINGLE HOP WPAN’S
about 10 meters in radius and totally covers connected
equipment whether static or in motion. High-Rate WPAN                     In this section, based on the OFDM UWB physical layer are
activates multimedia relation among compact instruments                   presented, the simulation yields for single-hop WPAN. The
within a Personal Operating Space (POS). A set of devices                 objective in using a single-hop scenario is to evaluate the
within a POS, which control under the control of a Pico net               Physical and MAC developed in this analysis. Transmission
controller (PNC) in order to share a wireless resource, is called         systems for rates of 55 Mbps, 200 Mbps, and 480 Mbps are
a Pico net. The basic timing for the WPAN is to offer the                 interpolated in this observation as they are representative of
function of the PNC. Additionally, the PNC manages the                    the lowest rate, the highest mandatory rate and the highest
Quality-of-Service (QoS) requirements for the WPAN as a                   optional rate, respectively. Both the 4m x 4m and the 10m x
whole.                                                                    10m circuitry areas for the network regions are used for
                                                                          simulation studies of the single-hop scenarios. Since the
                                                                          transmission radii of MBOA OFDM UWB systems that
B. UWB radio Communications-Its Fundamentals
                                                                          achieve a PER of 8% are 12.0 m, 7.4 m, and 3.2 m for systems
                                                                          organizing at 55 Mbps, 200 Mbps and 480 Mbps, respectively,
The IEEE 802.15.3 High Rate Alternative PHY Task Group                    the progressive functioning of the single-hop WPAN is easily
(TG3a) for WPANs is functioning is to ascertain a project to              apprehended within these network areas. In addition to the
facilitate a higher speed PHY enhancement amendment to                    average end-to-end delay and packet failure rate, the total
802.15.3in order to support very high data rate applications as           throughputs for all source- destination pairs are also gained.

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                                                                                                    ISSN 1947-5500
                                                                       (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                           Vol. 9, No. 5, May 2011
Table 1. analyses the system limitations used in the simulations for             PFR is close to zero before the occurrence of throughput
the single-hop scenarios considered in this study.                               saturation. After saturation throughput (about 44 Mbps) has
                                                                                 been reached, the average delay is rated to over 60 ms, and the
     Simulation parameter                          Value
        Simulation Time                              1s                          PFR is increased to over 8%. It can be summarized that for
        Number of nodes                              20                          single-hop scenarios within a 4m × 4m area, the performance
        Number of links                          2,4,6,8,10                      measures for average delay and PFR are both feasible and
         Network Area                      4mX4m, 10mX10m                        meet QoS needs before the congestion of throughput is arrived
      Number of Channels              1(Center Frequency = 3.432
                                                                                 for transmission systems operating at 55 Mbps supporting
      Transmission Power                        -10.3 dBm                        real-time applications. it can be observed that the network
      Receiver sensitivity              -77.2 dBm for 200 Mbps                   saturations are not reached even when 10 source-destination
                                         -72.6 dBm for 480 dBm                   pairs are present for transmission systems operating at both
   Channel model considered            Free space,Shadowing,an
                                             Rayleigh fading
                                                                                 200 Mbps and 480 Mbps,. These results are appropriate since
  Packet size(application layer)      982 bytes(will be 1024 bytes               the network throughputs presented in [8] are about 120 Mbps
                                            after MAC layer)                     and 180 Mbps for transmission systems operating at 200 Mbps
  Max Network Buffer size                      5,000 Bytes                       and 480 Mbps. Both the average delay (<5ms) and PFR (<
 Number of source Destination                    2,4,6,8,10
                                                                                 5%) are small in this case. The PFR is slender enhanced (from
  Guard time between slots                        1 µs                           0.072% to 1.38%) collated to that for the 200 Mbps
     Intra Frame time                           1.875 µs                         transmission for machines manipulating at 480 Mbps,
                                                                                 however, it is bounded in the feasible range (< 5%). It has
The packet loss because of collisions will be negligible since                   been observed that the simulation yields for 4m x 4m single-
the number of slots per model is set to be the number of                         hop situations equate those produced in the MBOA OFDM
source-destination pairs, and each active source node is                         UWB proposal, and the physical layer and MAC layer
assigned one time slot within one frame,. The efficiency for                     improvised in this study work well for 4m x 4m single-hop
scheduling should be close to 100%, theoretically. Generally,                    correspondence system architecture.
when the network saturation is reached, the packet failure rate
                                                                                 B. Simulation Results for 4m X4m Single Hop System
will be increased dramatically due to the buffer overflow, and
the average delay will also be enhanced due to extensive

A. 4m X 4m Single Hop System

The average delay, PFR, and throughput functioning for the
single-hop condition within the 4m × 4m network area are
specified in Figures 1 to 3 as a function of the number of
source-destination pairs. Since the base and targeting nodes
are haphazardly applied, the average distance for the active
links will be less than 3 m. It is elicited from Section II.A that
the propagation ranges to obtain 8% PER for systems
                                                                                 Figure 1.: Average End-to-End Delay vs. Number of Source-
operating at 55 Mbps, 200 Mbps and 480 Mbps are about 12                         Destination Pairs for Single-Hop:4mX4m Area
m, 7.4 m, and 3.2 m, respectively. Therefore, if the physical
layer and MAC layer are developed in this research work
perfectly (that is, the system performance match those
presented on the MBOA proposal, when considering the
overheads of other network layers), the packet failure rate due
to the blunder in channel will be very minute (close to zero)
for transmission systems operating at 55 Mbps and 200 Mbps.
However, there may be transmission errors present for
transmission systems operating at 480 Mbps.

The saturation throughput, that is attainable throughput when
the network saturation occurs for transmission systems
operating at 55 Mbps, is reached when 8 or more source-
destination pairs are present. This is appropriate since the
network throughput produced in [8] is about 48 Mbps at the
physical layer for systems being managed at 55 Mbps. It can                      Figure 2.: PFR vs. Number of Source - Destination pairs for the single Hop
be noticed that the average delay is less than 5 ms, and the                     scenario: 4mX4m Area.

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                                                                                                                  ISSN 1947-5500
                                                                        (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                            Vol. 9, No. 5, May 2011

Figure 3.: Throuput vs.Number of Source – Destination pairs for single- Hop
scenario: 4mx4m Area
                                                                                    Figure 4.: Average End-to-End Delay vs. Number          of Source-
                                                                                    Destination Pairs for single Hop scenario: 10mX10m Area

C. Simulation Results for 10m X 10m Single Hop System

The average delay, PFR, and throughput performance for the
single-hop scenarios within a 10m x 10m area are illustrated in
Figures 4 to 6 as a function of the number of source-
destination pairs. Since the source and destination nodes are
randomly assigned, the average distance for the active links
will be less than 7 m. Theoretically, if the physical layer and
MAC layer developed in this study work well, the packet
failure rate due to the channel error will be very small (close to
zero) for the systems operating at 55 Mbps. However, there
may be channel errors present for the systems operating at 200
Mbps. It was estimated that there would be a huge number of
                                                                                    Figure 5.: PFR vs. Number of Source Destination pairs for the single
channel errors available within those systems functioning at                        Hop scenario: 10mX10m Area
480 Mbps.

It can be analyzed that for systems manipulating at 55 Mbps,
since it is still within the propagation range (about 12 m) in
this case, the execution is approximately similar to the 4m x
4m area. For systems operating at 200 Mbps, the due point
productivity is not reached even when 10 source-destination
pairs are present. The average downtime is very minimal, and
less than 10 ms. The PFR is between 4% and 8%, which is
much greater than the PFR gained in the case of a 4m x 4m
geographical network area. The saturation productivity is not
approached at least for 10 source-destination pairs, for systems
operating at 480 Mbps. The average downtime is very
minimal, and less than 10 ms. However, the PFR is between
40% and 70%, which is too large to be acceptable. It can be                         Figure 6.: Throuput vs.Number of Source – Destination pairs for single Hop
seen that the achievable productivity for machines ordination                       scenario: 10mX10m Area
at 480 Mbps is much less than those for systems operating at
55 Mbps and 200 Mbps. This is because more packets are
                                                                                                               III CONCLUSIONS
dropped due to the presence of higher channel BER. It has
been extracted and understood that the simulation outcomes                          Considering the results for both the 4m x 4m and 10m x 10m
for 10m x 10m single-hop scenarios equate those produced in                         geographical network regions, it can be verified that for single-
MBOA OFDM UWB proposition, and the physical layer and                               hop WPAN systems, within the coverage radius, before the
MAC layer empowered in this study execute well for a 10m x                          saturation throughput is reached, the criteria of performance for
10m single-hop communication system configuration.                                  all data rates or progressions (55, 200 and 480 Mbps), i.e. the
                                                                                    average delay or downtime and PFR, arrive at the QoS
                                                                                    requirements for real-time applications.

                                                                              117                                   http://sites.google.com/site/ijcsis/
                                                                                                                    ISSN 1947-5500
                                                       (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                           Vol. 9, No. 5, May 2011
                                                                                               AUTHORS PROFILE
[1] J. Karaoguz, ―High-Rate Wireless Personal Area
Networks,‖ IEEE Communications Magazine, Vol. 39, pp. 96-                                 Prof. Ch. Subrahmanyam presently working as a
102, December 2001.                                                                       Professor & Head, Department of ECE at Scient
[2] S. M. S. Sadough, A. Mahmood, E. Jaffrot and P.                                       Institute of technology, Hyderabad. He has completed
Duhamel, ―Performance Evaluation of IEEE 802.15.3a                                        his B.E. in 1995 from Andhra University, A. P. India,
                                                                                          and M. Tech. from JNTU Hyderabad, in 2002, and
Physical Layer Proposal Based on Multiband- OFDM,‖                                        Pursuing his Ph.D. from JNTU Hyderabad, A. P. India
http://www.lss.superlec.fr/.                                                              with ECE in Wireless communications. He has about 15
[3] R. Bruno, M. Conti and E. Gregori, ―Mesh Networks:             years of experience in teaching and industry together, he is having
Commodity Multihop Ad Hoc Networks,‖ IEEE                          publications in International Journals and Conferences. He has guided many
                                                                   M. Tech and B. Tech. Projects. He is a life member of ISTE, India.
Communications Magazine, pp. 123-131, March 2005.
[4] C. S. Murthy and B. S. Manoj, Ad Hoc Wireless
Networks: Architecture and Protocols, Prentice-Hall, NJ,                                Dr. K. Chennakeshava Reddy, Presently working as
2004.                                                                                   Principal & Professor of ECE at TKR College of
                                                                                        Engineering. He has completed his B.E. in 1973 and M.
[5] A. F. Molisch, J. R. Foerster and M. Pendergrass,                                   Tech. in1976 from REC Warangal, A.P. India, and
―Channel Models for Ultra wideband Personal Area Network,‖                              Ph.D. in 2001 from JNTU Hyderabad. He has worked
IEEE Wireless Communications Magazine, Vol. 10, pp. 14-                                 in various positions starting from lecturer to Director of
21, December 2003.                                                                      Evaluation in JNT University, Hyderabad, A. P. India.
                                                                   He has about 70 publications in international and National journals and
[6] M. D. Benedetto and G. Giancola, Understanding Ultra           Conferences and he has successfully guided 4 Ph.Ds and many are under
Wide Band Radio                                                    progress. He is a member of various technical Associations.
Fundamentals, Prentice-Hall, NJ, 2004.
[7] L. Maret, I. Siaud and Y. Kamiya, ―Ultra Wideband PHY
Layer MBOA                                                                                 Dr. Syed Abdul Sattar, presently working as a Dean of
Performance and Sensitivity to Multipath Channels (IST                                     Academics & Professor of ECE department, RITS,
Magnet Project),‖ http://www.ist-magnet.org/.                                              Chevella, Hyderabad. He has completed his B.E. in
[8] Multiband OFDM Alliance, ―Multi-Band OFDM Physical                                     ECE in 1990 from Marathwada university Aurangabad,
                                                                                           M.S. India, M. Tech. In DSCE from JNTU Hyderabad,
Layer Proposal for IEEE 802.15 Task Group 3a,‖ September                                   in 2002, and Pursued his first Ph.D. from Golden state
14, 2004, http://www.wimedia.org/.                                                         University USA, with Computer Science in 2004, and
[9] H. Xu and A. Ganz, ―A Radio Resource Control Method in                                 second Ph.D. from JNTU Hyderabad, A. P. India with
UWB Protocol Design                                                                        ECE in 2007. His area of specialization is wireless
                                                                   communications and image Processing. He has about 21years of experience in
[10] P. Mohapatra, J. Li and C. Gui, ―QoS in Mobile Ad Hoc         teaching and industry together and recipient of national award as an
Networks,‖ IEEE Wireless Communications Magazine, pp.              Engineering Scientist of the year 2006 by NESA New Delhi, India. He has
44-52, June 2003.                                                  about 73 publications in International and National Journals and conferences.
                                                                   Presently he is guiding more than 15 research scholars in ECE and Computer
                                                                   Science from different Universities. He is a member of Board of studies for a
                                                                   central university and reviewer/editorial member/chief editor for national and
                                                                   International journals.

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