Enhancement of Throughput for Multi Hop WPAN’s Using UWB - OFDM Physical layer

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Enhancement of Throughput for Multi Hop WPAN’s Using UWB - OFDM Physical layer Powered By Docstoc
					                                                         (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                             Vol. 9, No. 5, May 2011

    Enhancement of Throughput for Multi 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
e-mail: subbunvl@yahoo.com                   e-mail: kesavary@hotmail.com                      Email: syedabdulsattar1965@gmail.com


Abstract— One of the most significant determinants                    extensive usage of cutting edge WPAN networks (up to 480
for the UWB (Ultra Wide Band) based substitutive                      Mbps) grounding on a UWB physical layer application. The
physical layer for WPANS (Wireless Personal Area                      special interest group (SIG) from IEEE have structured for this
Networks) is MB – OFDM (Multiband Orthogonal                          high- rate WPANS, which is popularly known as IEEE
Frequency Division Multiplexing). This paper deals in the             802.15.3.
manipulation outcomes for Multi-Hop WPAN depending
upon the UWB - OFDM physical layer are exhibited.                     We begin with the thought of Multi Hop Wireless Personal
However, the spectrum radius of         MB-OFDM UWB                   Area Network (WPAN) in this paper, then the confrontations
machines is quite minimal, and single-hop transmissions               of the Multi Hop WPANS, and later the reflections of Multi
may not be sufficient for WPANs functionalizing at huge-              Hop WPANS for the performance assessments like End- to-
data-rates. Therefore, a multi-hop provisional WPAN                   End delay, Packet Failure rate calculations for both the data
machine is appropriated at this juncture so as to maximize            rates of 200 Mbps and 480 Mbps.
the coverage of UWB radio. Performance of the entire
machine is achieved to determine if the Quality-of-Service
conditions can, now even, be sustained when an IEEE
802.15.3 TDMA MAC stratum is used in multi-hop                                           II.   MULTI HOP WPAN’S
correspondence situations. Simulation outputs for Multi
Hop WPAN standing on the UWB - OFDM physical layer                    Mobile multi-hop Adhoc networks (MANETs) are assortments
are reproduced in this paper. In this mode of functioning,            of mobile nodes of bridges linked together over a wireless
the transmitting machines for the data rates of 200 Mbps,             viaduct. These nodes can freely and actively self-monitor into
480 Mbps are used because these two are the directives for            approximate and temporary expedient network analysis sites.
the highest compulsion rate and the greatest optional rate            In this way, instruments can seamlessly inter-network in areas
respectively. We used both 9mX 9m and 20mX20m                         where pre-existing communication infrastructure (e.g., disaster
geographical areas for the networks fields for the Multi              recovery sites and battlefield environments) is zero. The
Hop scenarios in this simulation model. The critical                  discreet connectivity concept is not a budding one , but has
functionalities of the Multi Hop WPANS like average End               been in existence for the last 30 years in different modes such
– to – End Delay and Packet Failure Rate(PFR) and for all             as packet radio network (1972), sustainable adaptive radio
the source – Destination pairs are manipulated and                    network (1980), Global Mobile information system (early
restricted by employing the Qualnet network simulator.                1990s). Due to their quick and economically less demanding
                                                                      deployment of Ad hoc wireless networks we observe
Keywords- Multi hop, OFDM, Throughput, UWB, WPAN’s                    applications for the same in many areas. Defense applications,
                                                                      associated and spearheaded computing, emergency operations,
                     I.    INTRODUCTION                               wireless mesh networks, wireless sensor networks, and hybrid
                                                                      wireless network architectures are some of the areas its
At this juncture, there is a huge requirement for wireless            applications. Conventionally, logical networks have been the
communication systems that could be monitored at high                 only correspondence networking practice that accepted the ad
amount of data rates over a very less distance communications         hoc paradigm. The thumb-rule behind provisional networking
so as to attain the modern advances in electronic gadgets             is that of multi-hop relaying.
(Camcorders, DVD Players, etc). The usage of high - rate
Wireless Personal Area Networks (WPANs) for short                     In cellular networks, the routing decisions are acceded in a
distances provisional connectivity among electronic gadgets           centralized format under the surveillance of base stations. But
and communication devices have paved their way since 2000.            in an ad hoc cordless network, both accessing and resource
having been approved from Federal Communications                      management are operated in a scattered form in which all
Commission (FCC) for the use of Ultra- Wide- Band (UWB)               nodes would associate to capacitate communication among the
on the unlicensed band in 3.1 – 10.6 GHz range maximizes the          nodes themselves. This calls for each bridge to be more



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                                                                                                 ISSN 1947-5500
                                                               (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                   Vol. 9, No. 5, May 2011
intelligible so that it can act both as a data signaling host for           network, due to the huge amount of variables taken part, the
transmitting and receiving data, and as a network lane for                  amplitude of the machine develops significantly, thus
routing packets from other ends. Hence, the mobile paths in                 materializing logical modeling a considerably arduous task.
possible wireless networks are more confusing and entangled                 On the side of the machine, simulation methods capacitate the
than that of their correspondents in cellular networks. The                 exploration of more problematic and realistic phenomena. In
truancy of any central administrator, or control station, makes             composite machinery such as multi-hop networks, attentive
the routing process a more complicated one compared to that                 preference of the system attributes can drive to considerable
found in cellular networks. Multi-network ―hops‖ may be                     development in function, specifically for time-sensitive
required for one station to interchange information with                    applications. Focusing on time-sensitive applications, the
another node located elsewhere in the network due to the                    objective is to examine the performance strategies of multi-
restricted transmission range of a wireless network. In such a              hop WPAN systems standing on an OFDM physical layer.
network, each mobile node operates not only as a host but also              Compatible system functioning precautions involving end-to-
as a router, forwarding packets for other mobile nodes in the               end delay, productivity and packet failure rate realized in
network that may not be within direct wireless transmission                 various conditions with different choices of system
range of each other. Each node involves in an accessing                     parameters.
protocol that permits it to search for ―Multi-hop‖ paths
through the network to any other node.
                                                                            A. Capacity Analysis of a Multi-Hop Network
WPAN is said to be a single-hop network as per the present
IEEE 802.15.3 Strategy. That is, an info packet can be                      The network productivity or approximate capacity for a multi-
forwarded only from a source address to a destination address,              hop network is described in this section. When frequency
and there is no arbitrating node to work as a ―router‖. Using an            reuse is not considered, the capacity of multi-hop networks is
UWB - OFDM physical layer practicability for a WPAN, the                    greatly affected by the average hop count h. Theoretically, if
amount that can be attained is acutely minute, usually less than            the network capacity based on peer-to-peer communications is
10 meters. For an assured transmission with minimal packet                  C , the capacity of multi-hop networks will be C = C/h ,
error progression, a certain concentration of within 4 meters is            assuming that the network bandwidth used for routing
usually needed. The benefit with a multi-hop network is                     messages is multi negligible, and that a high-efficiency
obvious as it can maximise network coverage without                         scheduling scheme is implemented. If the aggregate packet
increasing either the accessibility strength, or sensitivity of the         production rate is r Mbps, the highest number of source-
receiver. The other advantage is that of improved reliability               destination pairs that can be supported is L = C /r. When the
through redundancy of route. The ambit of IEEE 802.15.3                     number of source-targeted pairs L is max multi over L,
MAC code to provide multi-hop networks calls for attentive                  packets will be launched due to the existence of a network due
and comprehensive observation.                                              point condition at max.

An example is used to demonstrate why a Multi - hop WPAN                    The conversion and transformation system being monitored at
is required to provide backup for immense progression                       200 Mbps is utilized here to exemplify how the Multi- hop
practical traffic flows. A video conference or home theatre                 network ability is related to the associated network
system is a trivial practice for use of WPAN based on the                   strategy and the average hop count. It is known that the
OFDM UWB physical layer. That is, to transmit the                           attainable productivity for 200 Mbps peer-to-peer transmission
multimedia traffic instead of using cables, the unwired links               is about 120 Mbps. If the average hop count is set to h = 3, the
will be used. The frequency range requirements for each                     capacity of a multi-hop network will be C = 120/3= 40 Mbps,
traffic outflow is about 6 Mbps, the average downtime should                theoretically. the maximum number of source-destination =
be less than 90 ms, and the packet Failure rate, less than 8% so            40/6 = 6, if the average packet multi generation rate per link is
as to arrive at the required QoS level. The circuitry region for            r = 6 Mbps,. If the packet Generation rate doubles, that can be
a video conference or home theatre system generally ranges                  supported is L = C /r max multi per link r = 3 Mbps, then the
from 9 m x 9 m to 20 m x 20 m. The indemnity radius for an                  maximum number of source-destination pairs that can be =
UWB - OFDM regulation is relatively only 3 meters for a data                40/3 = 13. If the average hop count is fixed to backed up is
procession of 200 Mbps and only 7 meters for a info                         L = C /r h = 4, the max multi capacity of a multi-hop network
progression of 480 Mbps to guarantee a PER of 8%. A single-                 will be C = 120/4 = 30 Mbps, theoretically. If the multi
hop network structure is inadequate to cover the expected                   average packet generation rate per link is r = 6 Mbps, then the
network area for these huge amounts of data rates have                      maximum number of source-destination pairs that can be
retained obvious. If a Multi - hop WPAN frame works well,                   supported is L = C /r = 30/6 = 5. The maximum number of
then the network coverage area can be perfectly enlarged                    source-destination pairs that can be backed up is L = C /r =
through the application of arbitrary nodes while monitoring                 30/3 = 10. If the max multi average packet generation rate
transmission at the required data rates. The suitability of the             per link is r = 3 Mbps. When the max multi number of source-
IEEE 802.15.3 TDMA MAC layer for use with multi-hop                         estimation pairs L is greater than L, packets will get a break
WPAN systems necessitates to be recognized. In Multi - hop                  down affected due to the saturation of max network.




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                                                                                                       ISSN 1947-5500
                                                             (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                 Vol. 9, No. 5, May 2011
Resultantly, the packet failure rate and the aggregate                    Table 1. abridges the limitations of system used in the simulations for the
downtime should increase productively.                                    Multi -hop situations recognized in this analysis.


                                                                                Simulation parameter                   Value
  III.   PREVAILING CHALLENGES IN MULTI-HOP NETWORKS                               Simulation Time                       5s
                                                                                   Number of nodes                       20
                                                                                   Number of links                   2,4,6,8,10
In a multi-hop provisional network, connections correspond                          Network Area                20mX20m for 200 Mbs
with each other using multi-hop wireless links, and there are                                                    9mX9m for 480 Mbps
no static infrastructure instruments similar to a ground station.
Each connection in the network also plays a role as a router,                 Node’s coverage radius to            6.9m for 200 Mbps
                                                                                achieve a PER of 5%               2.95m for 480 Mbps
enrooting data packets for other nodes. One of the prominent                    Number of Channels           1(Center Frequency = 3.432
hurdles is the structure of active routing protocols that can                                                              GHz
efficiently search for routes between two corresponding nodes.                   Transmission Power                     -10.3 dBm
Routing is apparently the first methodology to be reconsidered                   Receiver sensitivity          -77.2 dBm for 200 Mbps
                                                                                                                -72.6 dBm for 480 dBm
in altering from single-hop to multi-hop implementations [6].                 Channel model considered        Free space,Shadowing,and
A mobile ad hoc networking (MANET) functioning set has                                                               Rayleigh fading
been established within the Internet Engineering Task Force                     Packet size(application      982 bytes(will be 1024 bytes
(IEFT) to develop a routing framework for IP-based protocols                             layer)                     after MAC layer)
                                                                               Max Network Buffer size               1,00,000 Bytes
in ad hoc networks. Dozens of routing protocols for MANETs
                                                                                  CTA slot Duration         Transmission duration of 1024-
have been introduced, some examples including DSDV                                                                     Byte Packet
(Destination Sequenced Distance Vector), DSR (Dynamic                         Number of slots per Frame
Source Routing), and AODV (Ad-hoc On-demand Distance                          for Equal- Weighed Node-                    20
                                                                                   Based Scheduling
Vector).      However, most simulations and performance
                                                                              Number of slots per Frame           20,40 for 200 Mbps
affinities of mobile Adhoc network piloting protocols are                      for On – Demand Link-              30,60 for 480 Mbps
based on a condensed and visionary physical layer model, as                        Based Scheduling
well as easy performance metrics.
                                                                               Guard time between slots                  1 µs
                                                                                  Intra Frame time                      1.875 s
Most of the presently prevailing codes were framed out under
the hypothesis of an UDG (Unit Disk Graph) communication
model, in which signal strength variations due to a realistic
                                                                          A. SIMULATION RESULTS FOR EQUAL-WEIGHTED
channel are not considered. Without modification, such
                                                                             NODE-BASED SCHEDULING
routing schemes cannot work well with physical layer
characteristics that are correspondent of more factual
communication channel environments.                                       The equal-weighted node-based scheduling scheme is first
                                                                          implemented. The packet generation rates are taken to be 128
  IV. SIMULATION RESULTS FOR MULTI-HOP WPAN                               kbps, 3 Mbps and 6 Mbps. Figures 1 and 2 exemplify the
                   SYSTEMS                                                average delay and the PFR with PGR taken as a parameter
                                                                          using the equal- weighted scheduling scheme for systems
The simulation results for multi-hop communication system                 operating at 200 Mbps. Figures 3 and 4 illustrate the average
structuralizing are exhibited, and the assistive performance              delay and the PFR with PGR considered a parameter using the
analyses are given in this paper. The transmission systems                equal- weighted scheduling scheme for systems being
operating at 200 Mbps and 480 Mbps are simulated in this                  operated at 480 Mbps.
analysis as they are representatives of the immense mandatory
rate and the immense optional rate, respectively. First, the              Each node has the same share of the bandwidth irrespective of
simulation results and function analysis for the equal-weighted           whether it has a packet to transmit or not and independent of
node-based scheduling scheme are shown. Then, the                         how many packets it needs to transmit for equal-weighted
simulation outputs and performance analysis for the on-                   node-based scheduling. For the total number of network nodes
demand link-based scheduling scheme are given.                            set to 20, each node can have 120/20 = 6 Mbps of frequency of
                                                                          the network available for systems being operated at 200 Mbps,
In an unorthodox simulation scheme we applied for Multi –                 and 180/20 = 9 Mbps of network bandwidth available for
Hop networks are basically depended on the Link formation                 systems operating at 480 Mbps. If the PGR per link is 6 Mbps,
algorithm because of the existence of direct relationship                 only 1, or possibly 1.5 traffic currents can be backed up by one
between the Throughput and the scheduling competence. In                  node in either case. So, there will be collisions, and some of
this imaging task we used the two Link organizing algorithms;             the packets will be dropped, if a node is a transmitting node
the first is Equal-Weighted Node-Based Scheduling and the                 for one traffic progression and a forwarding node for another
second, On-Demand Link-Based Scheduling.                                  traffic stream. This situation occurs rarely, and sometimes
                                                                          there are number of traffic currents which need to be




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                                                                                                          ISSN 1947-5500
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transmitted by one node at the same time. Hence, the system
may work well with high probability only when the number of
source- destination pairs is very small. When there are not
more than 2 active links when the PGR equals 6 Mbps for
systems operating at either 200 Mbps, or 480 Mbps only, the
simulation results show that the performance measures are
acceptable. When the number of source-destination pairs L is
greater than 2, both the PFR and the average delay increase
logically. Similarly, if the PGR per link is 3 Mbps, only 2 or 3
traffic streams can be transmitted from one node at the same
time in either case. The situation is better than that for a PGR
equal to 6 Mbps, but the capacity available for each node is
still not enough. It can be observed that a maximum of 4
                                                                            Figure 2.: PFR vs. Number of Source-Destination Pairs With Equal-Weighted
active links can be supported. When L > 4, both the PFR and                 Scheduling for Transmission Systems Operating at 200 Mbps.
the delay maximizes dramatically. The maximum numbers of
source-destination pairs that can be supported are less than the
theoretically predicted capacities that were presented in
Section II.A for machines being operated at either 200 Mbps,
or 480 Mbps. The efficiency of allotment is less, and the
system bandwidth is wasted. For a PGR equal to 128 kbps,
there are over 50 traffic currents that can be backed by any one
node at the same time for systems operating at either 200
Mbps, or 480 Mbps. when the PGR is 128 kbps, it can be
recorded that the PFR (<8%) and the delay (about 5ms) both
meet the QoS requirements for real-time applications even for
10 active links. The Equal - weighted scheduling scheme only
works well when either the packet generation rate is low, or
there is only a very small number of active links. However, a
UWB-based WPAN system is structured for high-data rate
inter media progression, and hence, QoS requirements have to                Figure 3.: Average Delay vs. Number of Source-Destination Pairs With Equal-
                                                                            Weighted Scheduling for Transmission Systems Operating at 480 Mbps
be met. The simple equal- weighted node-based scheduling
cannot execute well in this kind of condition. For huge amount
of info speeds, the on-demand scheduling scheme has to be
considered.




                                                                            Figure 4.: PFR vs. Number of Source-Destination Pairs With Equal-Weighted
                                                                            Scheduling for Transmission Systems Operating at 480 Mbps

                                                                            B. SIMULATION RESULTS FOR ON-DEMAND LINK-
                                                                               BASED SCHEDULING
Figure 1.: Average Delay vs. Number of Source-Destination Pairs
With Equal- Weighted Scheduling for Transmission Systems                    For the on-demand link-based scheduling scheme, the packet
Operating at 200 Mbps                                                       generation rates are absorbed to be 3 Mbps and 6 Mbps. A
                                                                            value for PGR of 128 Kbps is not accepted here for the on-
                                                                            demand link- based scheduling scheme, provided that the
                                                                            equal-weighted scheduling can function perfectly for low data
                                                                            rates.




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                                                                                                            ISSN 1947-5500
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As the criteria of using the on-demand link-based scheduling
scheme for systems operating at 200 Mbps, Figures 5 and 6
explain the aggregate delay and the PFR with PGR,
respectively. It can be marked that saturation of the network is
reached when there are more than 6 dynamic connections for a
PGR similar to 6 Mbps. Both the PFR (<7%) and the delay (<
40 ms) are appropriated for real-time applications before
network due-point happens. Another analysis is that both the
PFR (< 7%) and the delay (< 40 ms) are feasible even for the
case of 10 dynamic links when the PGR is 3 Mbps per link.

These simulation yields for systems operating at 200 Mbps
match the theoretically assumed capacities that were shown in            Figure 5.: Average Delay vs. Number of Source-Destination Pairs With
Section II.A. That is, a total of 6 links can be reinforced when         On-Demand Scheduling for Transmission Systems Operating at 200 Mbps
the PGR is equal to 6 Mbps and 12 links can be supported
when the PGR is equal to 3 Mbps. Figures 7 and 8 exemplify
the average delay and the PFR, respectively, using the needed
scheduling scheme for systems being functioned at 480 Mbps.
It can be considered that saturation of the network is attuned
when there are more than 8 active links for a PGR equal to 6
Mbps. Both the PFR (< 7%) and the delay (< 10 ms) remain
reasonable before network saturation occurs.

Another observation is that both the PFR (< 7%) and the delay
(< 10 ms) are acceptable even for the case of 10 active links
when the PGR is 3 Mbps per link. The simulation results
attained for networks functionalizing at 480 Mbps match the
theoretically and impractically assumed capacities that were
                                                                         Figure 6.: PFR vs. Number of Source-Destination Pairs With
produced in Section II.A. That is, 8 links can be upheld when
                                                                         On-Demand Scheduling for Transmission Systems Operating at 200 Mbps
the PGR is equal to 6 Mbps and 16 links can be supported
when the PGR is equal to 3 Mbps.

When the PGR is 3 Mbps per link, this will also be examined
that both the PFR and the delay reach the QoS requirements
for real-time applications even for 10 active links. With the
same network buffer size, the PFR is almost the same when
the PGR is equal to 6 Mbps and when the PGR is equal to 3
Mbps. The delay when the PGR is same as to 3 Mbps which
is slightly smaller than that when the PGR is equal to 6 Mbps.
This is feasible since there will be more adjoining deferment
associated with the higher data rate.

The simulation outputs described above for machines being
monitored at both 200 Mbps and 480 Mbps match the capacity
analysis for a multi-hop network exhibited in Section II.A.
Hence, it can be examined that the efficiency in allotment is            Figure 7.: Average Delay vs. Number of Source-Destination Pairs With On-
                                                                         Demand Scheduling for Transmission Systems Operating at 480 Mbps
comparatively greater for the required scheduling scheme, and
the network bandwidth can be utilized more efficiently than in
the case of the equal-weighted scheduling scheme. It can be                                        III CONCLUSIONS
summarized that this UWB-based multi-hop WPAN system
performs well when the on-demand link- based scheduling is               Based on the simulation results attained and performance
used along with the proper routing protocol.                             analyses described in the previous section, conclusions can be
                                                                         drawn. The equal-weighted node-based allotting scheme does
                                                                         not function well for high-data rate applications. That is, the




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

                      Prof. Ch. Subrahmanyam presently working as a                                             Dr. Syed Abdul Sattar, presently working as a Dean of
                      Professor & Head, Department of ECE at Scient                                             Academics & Professor of ECE department, RITS,
                      Institute of technology, Hyderabad. He has completed                                      Chevella, Hyderabad. He has completed his B.E. in
                      his B.E. in 1995 from Andhra University, A. P. India,                                     ECE in 1990 from Marathwada university Aurangabad,
                      and M. Tech. from JNTU Hyderabad, in 2002, and                                            M.S. India, M. Tech. In DSCE from JNTU Hyderabad,
                      Pursuing his Ph.D. from JNTU Hyderabad, A. P. India                                       in 2002, and Pursued his first Ph.D. from Golden state
                      with ECE in Wireless communications. He has about 15                                      University USA, with Computer Science in 2004, and
years of experience in teaching and industry together, he is having                                             second Ph.D. from JNTU Hyderabad, A. P. India with
publications in International Journals and Conferences. He has guided many                                      ECE in 2007. His area of specialization is wireless
M. Tech and B. Tech. Projects. He is a life member of ISTE, India.                      communications and image Processing. He has about 21years of experience in
                                                                                        teaching and industry together and recipient of national award as an
                                                                                        Engineering Scientist of the year 2006 by NESA New Delhi, India. He has
                     Dr. K. Chennakeshava Reddy, Presently working as                   about 73 publications in International and National Journals and conferences.
                     Principal & Professor of ECE at TKR College of                     Presently he is guiding more than 15 research scholars in ECE and Computer
                     Engineering. He has completed his B.E. in 1973 and M.              Science from different Universities. He is a member of Board of studies for a
                     Tech. in1976 from REC Warangal, A.P. India, and                    central university and reviewer/editorial member/chief editor for national and
                     Ph.D. in 2001 from JNTU Hyderabad. He has worked                   International journals.
                     in various positions starting from lecturer to Director of
                     Evaluation in JNT University, Hyderabad, A. P. India.
He has about 70 publications in international and National journals and
Conferences and he has successfully guided 4 Ph.Ds and many are under
progress. He is a member of various technical Associations.




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