International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 1, Issue 2, October 2012
ISSN 2319 - 4847
A NEW APPROACH FOR CONGESTION
CONTROL IN WIRELESS NETWORK
AND ANALIZE IT FOR TCP
Manjeet Kaur Bedi1, Kendar Pratap2 and Raj Kumari3
1
Assistant Professor, Govt. National P.G.College, Sirsa, Haryana (INDIA)
2,3
Lecturer, Govt. National P.G.College, Sirsa, Haryana (INDIA)
ABSTRACT
This paper proposes a congestion control mechanism of various versions of TCP in Wireless Network and techniques for
provides performance improvement in terms of throughput and window size variations. When multiple synchronized servers
send data to a same receiver in parallel, for many important Data center applications and Research. So in this way many-toone traffic pattern is common. In this paper, we study TCP in-cast congestion may severely degrade their performances by
increasing response time also we study among TCP throughput, round trip time (RTT) and receive window. Our idea is to
design an ICTCP (In cast congestion Control for TCP) scheme at the receiver side. In particular, our method adjusts TCP
receive window proactively before packet drops occur. The implementation and techniques demonstrate that we achieve al-most
zero timeout and high good put for TCP incast. In this paper, we discuss a cross layer congestion control technique of TCP and
MAC in wireless networks also avoidance system control congestion.
Keywords: TCP, Adaptive, per- flow, Congestion, Reno, Data center
synchronized, flow control.
networks, incast congestion, PHY layer,
1. INTRODUCTION
Wireless networks are inherently limited by battery power and bandwidth constraints. They are characterized by
Mobility, random changes in connectivity, fluctuations in channel and interference due to neighboring nodes etc. In this
way packet loss of a wireless network is much more than that of a wired network, in which packet loss occurs mainly
due to congestion in the network. In this paper both TCP layer and PHY layer jointly control congestion. The PHY
layer changes transmission power as per the channel condition, interference received and congestion in the network,
whereas the TCP layer controls congestion using Reno-2 window based flow control. Congestion in a network is
characterized by delay and packet loss in the network. So Transport Control Protocol (TCP) is used as a reliable
transport layer protocol in the traditional.
2. THE CONGESTION CONTROL MECHANISM
The congestion control mechanism of various versions of TCP provides better throughput in a wired network. Best
effort find in wired network and deals with congestion effectively, where the packet loss is mainly due to congestion at
various nodes and routers.
2.1 Congestion avoidance system control
Congestion Control and Congestion Avoidance are two known solutions which address the problem given below.
Congestion results occurred when the aggregate demand for resources as bandwidth exceeds the capacity of the link.
Congestion is characterized by delay and loss of packets in delivery. In TCP, congestion is said to have occurred when
the sender receives three duplicate acknowledgments (dupacks) or when a timeout (packet loss) occurs, resulting in
wastage of resources. In congestion control, system controls the network parameters after realizing congestion
(reactive) whereas, in congestion avoidance, system controls the network parameters before congestion (proactive).
2.2 Congestion Control in Wireless Network
TCP was designed for use in wired networks. It becomes imperative to ask whether the same mechanism will also work
in the case of wireless networks. In TCP, the window size Wireless is reduced whenever packets are lost – assuming
that the loss is due to traffic congestion along the path of the flow under consideration. This assumption is not valid in
wireless networks since the channel may have been in a poor state thereby causing the packet to be lost at the physical
Volume 1, Issue 2, October 2012
Page 63
International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 1, Issue 2, October 2012
ISSN 2319 - 4847
layer (OSI Model) itself. The statistics of this type of loss may be very different from a packet dropping at a router
queue due to traffic congestion.
2.3 The adaptive window based congestion control
This type of adaptive window based congestion control used by TCP for wired network may not be appropriate for
wireless network. This is due to the time varying nature of a wireless channel and interference due to other nodes
causing packet loss, which is different from packet loss due to congestion. But, TCP’s congestion control mechanism
does not discriminate packet loss due to congestion and that due to bad channel or interference, rather apply the same
congestion control mechanism for both.
2.4 Adaptive Window Management traffic control
Most of the traffic in the Internet are TCP traffic. TCP’s congestion control in wired network is based on Adaptive
Window Management technique. In this technique, congestion window (cwnd) increases or decreases based on packet
drops and dupacks.
3. CONGESTION CONTROL TECHNIQUE
3.1 Cross layer
Our simulations show that the cross layer Congestion control technique provides performance improvement In terms of
throughput and window size variations. Instead of usual congestion control technique, we propose a cross layer
technique involving TCP and MAC (Medium Access Control) layer. TCP layer performs the Windowing flow control
and MAC layer varies transmission Power of wireless nodes depending on the channel condition and interference.
3.2 Per-flow for controlling the Window
Our per- flow congestion control is performed independently in slotted time of RTT (Round Trip Time) on each
connection, which is also the control latency in its feedback loop .well controlling the receive window is challenging:
The receive window should be small enough to avoid incast congestion, when we use per-flow and also large enough
for good performance
3.3 The new technical approaches are as follows:
The receive window of each Connection at the receiver side state to fine-grained tune. It is defined as
 To perform congestion control at receiver side, we use the available bandwidth on the network interface as a quota
to coordinate the Receive window increase of all incoming connections.
 Our receive window adjustment is based on the ratio of difference of measured and expected
 Through put over expected one. This is to estimate the throughput requirement from sender side and adapt receiver
window correspondingly.
 Formulation of TCP congestion control mechanism in terms of control system equations.
 Use of transmission power of wireless nodes as a function of cost in an optimization equation.
 Use of optimization techniques to determine the maximum aggregate utility of all the sources, subject to capacity
constraints and maximum transmission power of wireless nodes.
4. DRAWBACKS OF CONGESTION IN WIRELESS NETWORK
a. This mechanism may not be suitable in a wireless network, where packet loss due to time-varying nature of
channel and interference of other nodes are considerably high.
b. Receiver side is a natural choice since it knows the throughput of all TCP connections and the available
bandwidth.
c. The receiver side can adjust the receive window size of each TCP connection so the aggregate burstiness of all the
synchronized senders are under control.
5. SOLUTION TO PROBLEM
There must be some mechanism to tackle the problem of packet losses due to bad channel condition and interference,
such that we can extend the congestion control mechanism of wired network to wireless network for solve the problem.
6. TCP USES DIFFERENT METHOD
Different versions of TCP use different method to increase/decrease cwnd during congestion are
 TCP Tahoe: Avoidance Congestion and Slow Start
 TCP Reno-: Fast Recovery and Fast Retransmit
Volume 1, Issue 2, October 2012
Page 64
International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 1, Issue 2, October 2012
ISSN 2319 - 4847
 TCP Vegas.
6.1 TCP Tahoe
Buffer over-flows in the network resulting congestion in this way TCP Tahoe assumes losses due to packet corruption
are much less probable than losses in buffer flow. It uses triple timeouts to detect congestion or packet loss in the
network. It decreases Congestion Window size to one (from the current Congestion Window size) after detecting a
congestion and then increases cwnd size from one to ssthresh which acts as limit point for exponential increase and is
set to half of the cwnd size before experiencing.
6.2 TCP Reno:
When TCP enters fast recovery it records the highest outstanding unacknowledged packet sequence number. When this
sequence number is acknowledged, TCP returns to the congestion avoidance state.
6.3 TCP Vegas:
This is one of the new approaches for congestion control in wireless network scenario have considered a simple
topology for our simulation with its more accurate yet more conservative mechanisms, is able to capture most of the
bandwidth.
7. CONCLUSION
This paper demonstrates Congestion avoidance system control and Congestion Control in Wireless. Network streams
may be delivered the throughput of all TCP connections and the available bandwidth wireless networks. It presents a
brief overview of the need for congestion controlled window and in particular describes the use of the TCP. Ideal
platform for convenient experimental research in wireless multi- networks Quick response to network dynamics
reduced channel congestion in wireless multi- networks significant fairness improvement for TCP. Most of the traffic in
the Internet is TCP traffic. Cross layer Congestion control technique provides performance improvement In terms of
throughput and window size variations TCP’s congestion control in wired network is based on Adaptive Window
Management technique. In this TCP’s congestion control mechanism does not discriminate packet loss due to
congestion and that due to bad channel or interference, rather apply the same congestion control mechanism for both.
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