Analysis of DelAck based TCP-NewReno with varying window size over Mobile Ad Hoc Networks

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					                                                                (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                Vol. 10, No. 1, January 2012

Analysis of DelAck based TCP-NewReno with varying
     window size over Mobile Ad Hoc Networks
      Parul Puri1 Gaurav Kumar2 Bhavna Tripathi3                                                  Dr Gurjit Kaur4

Department of Electronics & Communication Engineering                                        Assistant Professor,
      Jaypee Institute of Information Technology,                          Department of Electronics & Communication Engineering
                      Noida, India.                                                             School of ICT,
                parulpuri9@gmail.com1                                                    Gautam Buddha University,
                er.gauravchachra@gmail.com2                                                 Greator Noida, India.
                my.bhavna@gmail.com3                                                   gurjeet_kaur@rediffmail.com4

                                                                               Two key requirements of any network are reliable data
                                                                           transfer and congestion control. The transmission control
 Abstract—In this paper, we study TCP performance over multi-              protocol (TCP) was designed to provide reliable end-to-end
 hop wireless networks that use IEEE 802.11 protocol for access.           delivery of data packet in the wired networks. However,
 For such networks NewReno is the most deployed TCP variant                unlike wired networks wireless networks suffer from many
 that handles multiple packet losses efficiently. It is shown that         problems, such as packet losses due to congestion, node
 the delayed ACK scheme substantially increases the TCP                    mobility, high bit errors, medium access contention due to
 throughput. We propose an approach to improve the                         hidden terminals, and so on. Hence, in order to apply TCP in a
 performance of half-duplex and asymmetric multi hop networks
                                                                           wireless environment, TCP needs some modifications.
 widely employed for mobile communication. Our approach is
 based on optimizing the timer duration of the delayed ACK
                                                                           Further, keeping in mind the basic characteristic of a TCP
 scheme and varying the window size. Simulations have been                 scheme the acknowledgement (ACK) packets need to be
 carried on NS2 for TCP-NewReno variant using DSDV and                     transmitted from TCP sink to TCP source, against the flow of
 AODV routing protocols.                                                   TCP data packets. This results in simultaneous arrival of TCP
                                                                           data and ACK packets which can cause collisions and even
 Keywords: Multi-hop wireless networks, TCP, Newreno, DelAck,              packet losses [2, 3]. As a result, there is a huge degradation in
 DSDV, AODV.                                                               throughput in multi-hop networks [4].
                        I. INTRODUCTION                                        At the MAC level, each data packet transmission is a part
     In the last few years, many research works have focused               of four-way handshake protocol, which is intended to reduce
 on multi-hop wireless networks, in which relaying nodes are               the collision probability. The handshake reduces the
 in general mobile, and communication needs are primarily                  probability of hidden-terminal collisions, but it does not
 between nodes within the same network. In such networks, a                eliminate them. This limits the number of packets that can be
 number of intermediate nodes whose function is to relay                   transmitted simultaneously in a wireless network without
 information from one point to another point carry out                     collisions. The main factor affecting the TCP performance in
 communication between the two end nodes. The application                  multi-hop wireless networks is the contention and collision
 can be useful in various fields, especially because it uses               between ACK and data packets caused by taking the same
 wireless means of communication, hence saving the hassle of               path. Thus, in order to improve the TCP throughput, we shall
 laying down wires in already crowded or remote terrains.                  try to decrease the ACK flows by using the delayed ACK
 People working in collaboration and places in remote                      scheme, where an ACK is transmitted for every d packets,
 locations can connect through it. Activities which require                defined by the DelAck number, that reach the destination [5].
 working at locations having no ground infrastructure, like                However, to avoid a deadlock, and if d packets do not arrive,
 patrolling, disaster hit areas and rural areas, can be carried out        an acknowledgement is generated after some time interval
 using this technology. Some important applications are also               without further waiting.
 being developed on the basis of this technology which can be                 The throughput of a network is limited by two windows:
 used by armed forces in rescue and war time scenarios [1].                the congestion window and the receive window. The TCP
                                                                           sender uses a congestion window (cwnd) in regulating its

                                                                                                        ISSN 1947-5500
                                                         (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                         Vol. 10, No. 1, January 2012
transmission rate based on the feedback it gets from the               RFC 5681 mandates that an acknowledgement be sent for at
network [6]. Whereas, the receive window size sets a limit on          least every other full-size segment, and that no more than
the amount of data that can be sent unacknowledged. Earlier            500ms expire before any segment is acknowledged.
researches on TCP performance over multi-hop wireless
                                                                          Basically, the delayed acknowledgement procedure defines
networks [3] have shown that for static chain topology it is
beneficial to limit the maximum receive window size of TCP             two terms: DelAck number and Time interval. The DelAck
                                                                       number d defines the number of packets for which the receiver
sink to around n/4, where n is the number of nodes; and any
further increase in the maximum window size causes more                waits before sending an acknowledgement. By using delayed
                                                                       acknowledgement          mechanism        the     numbers      of
collisions and deterioration in the throughput. However, the
issue of limit on an optimum window size for mobile topology           acknowledgments required are reduced. As acknowledgments
                                                                       are also parts of traffic, the load over channel decreases. Thus,
is left unaddressed.
                                                                       using this concept the throughput is increased. But this is not
    It is also seen, for a fixed small size of maximum window          always the case; there are some situations where delayed
size, the delayed ACK does not outperform the standard TCP             acknowledgment leads to reduction in bandwidth. Studies
version since most of the time, the window size limits the             have shown d = 2 gives an optimum performance.
number of packets that can be transmitted by the sender to less
                                                                          Second parameter of the delayed acknowledgement
than d. So, the delayed ACK scheme has to wait for the timer
to expire before generating an ACK; and the sender cannot              procedure is the Time Interval (Fig. 1). A timer is set by the
                                                                       TCP, depending on which DelAck procedure is modified.
transmit packets during that time. Hence, the time interval
plays a critical part of TCP system with DelAck scheme.                Now the acknowledgement is sent when the two packets are
                                                                       received or if the timer goes off, whichever occurs first.
    Tahiliani et al in [4] has studied the performance of TCP
variants such as Tahoe, Reno, NewReno, Sack, and Vegas                    We aim to study the effect of the delayed acknowledgement
                                                                       procedure on TCP throughput over multihop wireless links.
over various routing protocol. They have analyzed that TCP
NewReno and Sack perform better in comparison to the other                Jiwei Chen et al [8] has studied that increasing the value of
schemes. In this paper, the NewReno variant of TCP is tested           DelAck number does not always show a positive increase in
as it is the most deployed one. We propose an approach to              the throughput. In some situations it has proved to be
improve the TCP performance by simulating the delayed ACK              deteriorating also. This is so because if a large DelAck
scheme with an optimum time interval and by varying the                number is chosen it will cause a large burst of packets to pass
receive window size for the same size of congestion window             thereby increasing interference. Keeping in view this adverse
(cwnd) for mobile topology. We choose one proactive routing            affect we have kept our DelAck number to be 2 and focus our
protocols: Destination Sequenced Distance Vector (DSDV) as             study on the Time interval aspect.
well as one reactive routing protocols: Ad hoc On demand
Distance Vector (AODV) for our study since they are
accepted as the standard routing protocols for multi-hop
wireless networks [7].

                       II. Related Work
    In Reference [2], G. Holland et al uses a new metric called
expected throughput to compare the performance by
measuring the differences in throughput with varying number                  Figure 1. Role of DelAck and Time Interval in TCP communicattion
of hops. Further the authors have studied the effects of
mobility on TCP Reno‟s performance in mobile ad hoc                                           IV. Window Size
networks. This metric will be used in our paper and will be
discussed in detail in Section V.                                         In order to limit the impact of congestion, TCP uses a
                                                                       special kind of buffer called Sliding (Receive) Window.
    Ammar Mohammed AI-Jubari [5] has shown that the                    Receive window size indicates the buffer size of the receiver.
delayed acknowledgment strategy can improve TCP                        In other words, window size is the maximum number of
throughput up to 233% compared to the regular TCP over                 packets (bytes) a source can transmit before receiving an
multi-hop wireless networks.                                           acknowledgement from the receiver. By controlling the
    Jiwei Chen [8] has tried to explain the effect of receive          window size, a receiver can control the rate at which other
window size on the TCP throughput, but have restricted the             hosts send data to it. For the small window size, the number of
research to static topology only.                                      packets transmitted to the receiver is less. But the number of
                                                                       acknowledgements transmitted in this case will be
                                                                       comparatively larger and will cause collision with data
               III. Delayed ACK Scheme                                 packets, thus reducing the throughput. On the other hand, if
   RFC 831 first suggested a delayed acknowledgement                   the window size is too large, number of acknowledgements
(DelACK) strategy, where a receiver doesn't always                     decrease. However, as the receiver buffer size is more, number
immediately acknowledge segments as it receives them. This             of packets transmitted by the sender host increases thereby
recommendation was carried forth and specified in more detail          causing bursty traffic. This causes interference and packet
in RFC 1122 and RFC 5681 (formerly known as RFC 2581).                 losses depending upon the path length. Thus, there exists an

                                                                                                       ISSN 1947-5500
                                                             (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                             Vol. 10, No. 1, January 2012
optimum window size for which the channel gives maximum                    scene file. So, we calculate the expected throughput using (1)
throughput. We aim to find the size of this optimum size of                as follows:
the Sliding window.                                                                                   

                                                                                                     t       i     Ti
          V.     Simulation Setup and Methodology                          E xp ected throughput    i 1

   Simulations have been done on ns-2 [9], a discrete event                                               ti 1

simulator. The simulations were carried for multihop wireless              Practical Throughput is obtained from the simulations. Both
static and mobile topologies.                                              expected and practical throughputs are then compared in terms
A. Multihop Wireless Static Topologies                                     of the percentage achieved of the expected throughput
                                                                           calculated as follows:
    A linear string topology of 8 nodes was designed, similar
                                                                                                   Practical Throughput          (2)
to the one used in [10]. A single TCP connection with variable             Percentage Achieved =                        %
number of hops (1-7) was studied. The nodes were configured                                          Expected Throughput
to use 802.11 MAC protocol with the following parameters.                                  VI.   RESULTS AND ANALYSIS
Distance between two nodes was 250 metres. This distance is
same as the maximum transmission range. Radio propagation                  A. Multihop Wireless Static Topologies
model used was Two-ray ground reflection model. The                            Tables I and II show the throughput (in Kbps) obtained for
channel data rate was 2 Mbps, TCP packet size was 1460                     each variant of TCP with DSDV and AODV routing protocols
bytes and the maximum window size was 32. With the above                   respectively. These results will be used for calculating the
mentioned parameters fixed and varying the TCP protocol,                   expected throughput values as explained in Section V.
routing protocol and TCP sink results were taken. The results
have been discussed in Section VI.                                             Our studies show that NewReno variant of TCP gives the
                                                                           most optimum performance as compared to other variants for
B. Multihop Wireless Mobile Topologies                                     both the routing protocols. This is because of the fact that
    Our network model constitutes of 25 nodes in a 1500 x                  NewReno is more capable in handling multiple packet losses
400 m2 flat, rectangular area. Movement of nodes was                       from a single window of data as compared to other TCP
according to the mobility patterns generated by the mobility               variants. Hence, for mobile topologies we carry out our
pattern generator offered by ns-2; which is based on random                analysis for the NewReno TCP scheme.
waypoint mobility model. In this model, each node picks a
random destination. Once it arrives to the destination it pauses               As is known, the performance of TCP depends on the
for some time and then picks another destination. This                     routing protocols as every routing protocol has a different
procedure is followed throughout. The mean speed of the                    technique to handle link failures and to form routes. From our
nodes was taken 10m/s and the pause time was 0 sec. The                    results, it can be seen in static topologies performance of
simulation results are based on an average throughput of 25                proactive routing protocol (DSDV) is better in terms of
mobility patterns. The parameters were same as those taken                 throughput as compared to reactive routing protocol (AODV).
for static topologies. Here, the TCP-NewReno variant was                   The reason is that proactive protocols maintain a routing table.
studied with variations in TCP sink, routing protocol and                  However, in reactive protocols route calculation is on-demand
window size. Simulation results are discussed in the Section               basis which causes some delay in sending data. Also, DSDV
VI.                                                                        has lesser number of control packets which decreases the
C. Performance Metric                                                      number of collisions.
    Throughput has been used as the performance metric.                       Further, an improvement in throughput is observed when
Throughput was measured for fixed sender and receiver nodes                DelAck is used for all TCP variants over DSDV and AODV
over the entire period of the connection. TCP cannot                       routing protocols.
determine the cause of packet loss, and considers congestion
the reason behind the losses. Thus, the throughput so obtained             B. Multihop Wireless Mobile Topologies
is always less than the optimal value. In order to compare the                 Tables III and IV show the throughput (in Kbps) obtained
difference, we use another metric called the expected                      for the NewReno variant of TCP with DSDV and AODV
throughput. Expected throughput gives an upper bound on the                routing protocols respectively. Throughput values have been
TCP throughput. Expected throughput is calculated using the                obtained by varying the characteristics of TCP sink such as
throughput values obtained in the static topologies. If t i = time,        window size and delay interval.
Ti = throughput, where i = hops (ranges from 1 to 7). Hence t1
means "amount of time source and destination were 1 hop far                    Based on the simulation results Fig. 2 to Fig. 7 have been
from each other". Similar explanation comes for throughput.                plotted and will be further analyzed.
T2 means "throughput when source and destination were 2
hops far from each other". The values of Ti are those obtained
from simulating static topologies and ti is obtained from the

                                                                                                                ISSN 1947-5500
                                                                    (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                    Vol. 10, No. 1, January 2012
                                             TABLE I.        THROUGHPUT (IN KBPS) USING DSDV

                                    Tahoe                      Reno                     New Reno                    Sack
                   No of
                   Hops       Without        With        Without        With        Without      With       Without            With
                              DelAck        DelAck       DelAck        DelAck       DelAck      DelAck      DelAck            DelAck

                     1          752.19       802.40        752.19       802.40        752.19      802.39       752.19          802.39
                     2          376.60       402.15        376.60       402.15        376.60      402.15       376.60          402.15
                     3          251.15       271.74        224.98       271.74        224.98      271.74       165.08          271.74
                     4          173.44       185.36        164.70       180.06        160.00      185.58       179.79          184.50
                     5          152.62       164.44        140.10       159.88        155.98      121.59       154.48          160.52
                     6          141.22       148.07        124.32       143.43        143.05      152.84       144.65          151.25
                     7          133.16       139.06        123.75       131.73        135.36      148.58        74.26           79.77

                                            TABLE II.        THROUGHPUT (IN KBPS) USING AODV

                                    Tahoe                      Reno                     New Reno                       Sack
                   No of
                   Hops       Without        With        Without        With        Without      With        Without           With
                              DelAck        DelAck       DelAck        DelAck       DelAck      DelAck       DelAck           DelAck

                     1          757.76       805.10        757.76       805.10        757.76      805.10       757.76          805.10
                     2          379.15       403.50        379.15       403.50        379.15      403.50       379.15          403.50
                     3          198.02       222.21        199.60       222.21        211.56      222.21       203.98          217.61
                     4          151.24       178.50        127.64       154.55        152.46      177.88       150.65          174.58
                     5          127.37       152.30        113.98       137.77        130.05      152.47       126.17          150.17
                     6          116.77       136.02        105.44       125.04        119.80      135.58       118.47          133.21
                     7           51.81        75.06         53.89         99.08        56.25       71.39        42.29          107.01


                   Without     DelAck-       DelAck-       DelAck-
 Window Size
                   DelAck      100 ms        120 ms        140 ms

       2             496.36       520.60        535.20        523.08
       4             509.72       531.44        535.68        532.44
       6             491.44       524.64        528.64        538.68
       8             525.77       564.11        546.54        559.28
      20             519.84       560.02        544.97        547.22
      32             524.11       560.76        570.00        549.33
 Expected Thpt       592.48       634.31        634.31        634.31


                   Without     DelAck-       DelAck-       DelAck-
 Window Size
                   DelAck      100 ms        120 ms        140 ms

       2             513.96       539.28        525.88        538.76                   Figure 2.Throughput (in Kbps) using DSDV with varying
       4             498.84       549.08        544.08        534.04                                        Window Size
       6             504.60       555.96        540.68        546.08               For window sizes 2, 4, and 6 the throughput is lesser than
       8             501.68       554.44        543.28        542.80           the optimum window size - 8 for different delay intervals.
      20             514.80       559.24        537.44        543.28
                                                                               This decrease in throughput for small window sizes at higher
      32             503.16       554.44        547.52        548.12
                                                                               intervals is evident as for small window sizes the buffer
 Expected Thpt       595.17       632.91        632.91        632.91
                                                                               capacity of receiver is small. Hence, the sender can now send
                                                                               a limited number of packets until it has received
   From Fig.2 it is seen that DSDV gives a maximum                             acknowledgements for all packets in that window. However,
throughput of 570 Kbps for window size of 32 and a delay of                    as the timer interval is more, receiver remains idle for a longer
120 ms. In this case 90% of the expected throughput is                         duration before sending the acknowledgement. This results in
achieved. However, for other delay intervals (0, 100, and 140                  a decrease in throughput. On similar grounds, the adverse
ms) window size-8 outperforms all other window sizes                           effects of elevated idle time are observed for 140 ms delay
including 2, 4, 6, 20, and 32. The percentage achieved is 89%                  interval for all window sizes. This indicates the limitation on
of expected throughput for window size - 8.                                    the value beyond which delay interval should not be increased.

                                                                                                             ISSN 1947-5500
                                                                (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                Vol. 10, No. 1, January 2012
                                                                           53, 44, 51) Kbps are obtained for window sizes 2, 4, 6, 8, 20,
                                                                           and 32 respectively in comparison to gains (12, 45, 36, 42, 23,
                                                                           and 44) Kbps for 120 ms delay.

       Figure 3. Throughput (in Kbps) using AODV with varying
                             Window Size

    In case of AODV, as seen from Fig. 3, peak in throughput
obtained is 559 Kbps at a window size of 20 with delay 100                         Figure 5. Throughput (in Kbps) using AODV with varying
                                                                                                Window Size and Time Intervals
ms. It has achieved 88% of the expected throughput. In
comparison to the DSDV protocol, AODV has some
variations in terms of the optimum window size and delay                       Fig. 6 gives a comparison of the expected throughput
interval. As seen from Fig. 3, peaks in throughput values are              values and the practical throughput values obtained through
obtained for larger window sizes such as 20 and 32 for                     simulations. The practical throughput values taken for
different time intervals, in comparison to DSDV where the                  comparison are the maximum values obtained for respective
optimum size of window for different time intervals was 8. In              time intervals (100, 120, and 140 ms). It is seen, in order to
terms of the delay interval, Fig. 5 shows that best performance            achieve practical throughput values as close to the expected
for AODV is obtained for DelAck=100ms. Any further                         throughput, it is important to select time interval in
increase in the delay interval degrades its performance.                   conjunction with the window size.
Overall, performance of DSDV is better in comparison to the
AODV protocol.                                                                  Fig. 7 gives the values of the respective time intervals for
                                                                           different window sizes (2, 4, 6, 8, 20, and 32) which give
                                                                           maximum throughput. As can be seen for DSDV, window
                                                                           sizes 8 and 20 give maximum throughput of 564 Kbps and
                                                                           560 Kbps at 100 ms time interval. For AODV all window
                                                                           sizes give maximum throughput at 100 ms time interval.

       Figure 4. Throughput (in Kbps) using DSDV with varying
                   Window Size and Time Intervals

    Further, from Fig. 4 we analyze the gain in the throughput
values obtained with DelAck and without DelAck. As
expected theoretically, a significant amount of gain is obtained
using DelAck. Also, the amount of gain is dependent on the
                                                                            Figure 6. Comparison of Expected and Maximum Practical Throughput (in
two parameters, delay and window size. For smaller window                      Kbps) using DSDV and AODV with varying Window Size and Time
sizes (2 and 4) the gain is more for 120 ms delay. For eg. for                                             Intervals
window size 4, throughput gain is 39 Kbps for 120 ms delay
while for delays 100 and 140 ms the gain is 24 and 27 Kbps
respectively. For larger window sizes (8 and 20) a delay of
100 ms gives the highest throughput. In case of AODV, Fig. 5
shows maximum gain is achieved for 100 ms delays for all
window sizes. For 100 ms delay, gains as high as (25, 50, 51,

                                                                                                          ISSN 1947-5500
                                                                     (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                     Vol. 10, No. 1, January 2012
                                                                                    case of AODV, 100 ms delay with variable window size gives
                                                                                    optimum throughput.
                                                                                       Currently, we are also analyzing the effect of number of
                                                                                    nodes on the choice of window size and time interval. Testing
                                                                                    our approach in a real test-bed experiment, to show its
                                                                                    efficiency in the real TCP, is a part of our future work.
                                                                                    [1]  M. Gerla and J.T.-C. Tsai, “Multicluster, mobile, multimedia radio
                                                                                         network,” ACM/Baltzer Journal of Wireless Networks, vol. 1, no. 3,
                                                                                         pp. 255-265, 1995.
                                                                                    [2] G. Holland and N. Vaidya, “Analysis of TCP performance over mobile
                                                                                         ad hoc networks,” in Proceedings of ACM/IEEE MOBICOM, Seattle,
                                                                                         Washington, August 1999 .
                                                                                    [3] T. Kuang, F. Xiao, and C. Williamson, “Diagnosing wireless TCP
  Figure 7. Plot of maximum throughputs (in Kbps) obtained for different                 performance problems: a case study," in Proceedings of SCS SPECTS
     window sizes with their delay intervals using DSDV and AODV                         Conference, Montreal, PQ, pp. 176-185, July 2003.
                                                                                    [4] M. Tahiliani, K.C. Shet, and T.G. Basavaraju, “Performance evaluation
              VII. Conclusions and Future Work                                           of TCP variants over routing protocols in multi-hop wireless networks,”
   Through simulation we have studied the effect of delayed                         [5] A.M. Al-Jubari and M. Othman, “A new delayed ACK strategy for
acknowledgment with variations in time interval for various                              TCP in multi-hop wireless networks,” Information Technology
receive window sizes on TCP NewReno in mobile multi-hop                                  (ITSim), pp. 946 – 951, June 2010 .
wireless networks. It is evident from the results that, there                       [6] Pasi Sarolahti, “Linux TCP,” Nokia Research Centre.
exists a tradeoff between the time interval and window size.                        [7] Z. Fu, P. Zerfos, H. Luo, S. Lu, L. Zhang, and M. Gerla, “The impact
We propose that maximum throughput can be achieved by                                    of multi-hop wireless channel on TCP yhroughput and loss," in
                                                                                         Proceedings of IEEE INFOCOM, San Francisco, CA, April 2003.
selecting an optimum time interval for a particular window
                                                                                    [8] E. Jiwei Chen, Yeng Zhong Lee, Mario Gerla, and M.Y. Sanadidi,
size. Further, it is seen choice of window size and time                                 “TCP with delayed ack for wireless networks,” in Broadband
interval varies with the routing protocols also. Results show                            Communications, Networks and Systems, pp. 1-10, October 2006.
for DSDV a time interval of 120 ms and a large window size                          [9] K. Fall, K. Vardhan, “The ns manual,” The VINT Project, January
of 32 gives a peak in throughput. However, a window size of 8                            2009.
gives the most optimum results for various delay intervals. In                      [10] M. Gerla, K. Tang, R. Bagrodia, “TCP performance in wireless
                                                                                         multihop networks,” in Proceedings of IEEE WMCSA, New Orleans,
                                                                                         LA, February 1999.

                          AUTHORS PROFILE

                                                                                                          Bhavna Tripathi received the B.Tech degree in
                      Parul Puri received the B.Tech degree in Electronics
                                                                                                          Electronics & Communication Engineering from
                      & Communication Engineering from National Institute
                                                                                                          Gautam Buddh Technical University, Lucknow , India
                      of Technology, Hamirpur, H.P., India. She is currently
                                                                                                          in 2010 and is currently pursuing the M.Tech degree in
                      pursuing the M.Tech degree in Electronics &
                                                                                                          Electronics & Communication Engineering from
                      Communication Engineering from Jaypee Institute of
                                                                                                          Jaypee Institute of Information Technology, Noida,
                      Information Technology, Noida, India.
                                 She has worked as a Patent Analyst in a
                                                                                                                     Her current research interests include
                      leading legal process outsourcing firm CPA Global,
                                                                                                          digital and wireless communication, digital signal
                      Noida. She has hands on experience in patent analysis,
                                                                                    processing, simulation of telecommunication systems and radio-navigation
patent infringement, and patent portfolio management in various technology
domains including „Speech‟, „IP Multimedia Subsystem architecture‟, and
                                                                                                            Dr Gurjit Kaur has been an Assistant Professor with
            Her current research interests include spread-spectrum
                                                                                                            the Gautam Buddha University, Greater Noida, India.
communication, multi-carrier communication, channel coding, and channel
                                                                                                            She received her ME and Ph.D degrees both from the
                                                                                                            PEC University of Technology, Chandigarh in 2003
                                                                                                            and 2010 respectively. She has been a topper
                     Gaurav Kumar received the B.Tech degree in                                             throughout her academic career and has received the
                     Electronics & Communication Engineering from                                           gold medal from Honorable President of India for
                     Kurukshetra University, Kurukshetra, India in 2008                                     being overall topper at Punjab Technical University,
                     and is currently pursuing the M.Tech degree in                                         Jalandhar.
                     Electronics & Communication Engineering from                               Her professional research areas are Wireless and Optical
                     Jaypee Institute of Information Technology, Noida,             Communication. She has many research papers of national and international
                     India.                                                         repute to her credit. She has served as a reviewer of journals and conferences.
                                His current research interests include
                     digital and wireless communication, resource
allocation for broadband wireless transmissions, simulation of
telecommunication systems and image processing in VHDL.

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