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Modelling and Analysis of TCP Performance in Wireless Multihop Networks  [PDF]
Hannan Xiao, Ying Zhang, James Malcolm, Bruce Christianson, Kee Chaing Chua
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.201027061
Abstract: Researchers have used extensive simulation and experimental studies to understand TCP performance in wireless multihop networks. In contrast, the objective of this paper is to theoretically analyze TCP performance in this environment. By examining the case of running one TCP session over a string topology, a system model for analyzing TCP performance in multihop wireless networks is proposed, which considers packet buffering, contention of nodes for access to the wireless channel, and spatial reuse of the wireless channel. Markov chain modelling is applied to analyze this system model. Analytical results show that when the number of hops that the TCP session crosses is ?xed, the TCP throughput is independent of the TCP congestion window size. When the number of hops increases from one, the TCP throughput decreases ?rst, and then stabilizes when the number of hops becomes large. The analysis is validated by comparing the numerical and simulation results.
Performance improvement of TCP over wireless network  [PDF]
Raja singh,Brajesh patel
International Journal of Engineering Science and Technology , 2011,
Abstract: TCP’s congestion control suffers from a coarse granularity when applied to the multihop ad hoc environment.To overcome this problem, we propose a rate based wireless congestion control protocol (WCCP). There are two components in WCCP. One is at the transport layer. It replaces the window adjusting algorithm of TCP with a rate control algorithm to regulate the sending rate. The other is between the networking layer and the MAC layer. It monitors and possibly modifies the feedback field in TCP data packets when it passes the outgoingpackets from the networking layer to the MAC layer and the incoming packets in the reverse direction.
TO IMPROVE THE TCP PERFORMANCE USING CROSS LAYER IN WIRED CUM WIRELESS NETWORK.  [PDF]
VIMALA.D,KANNADASAN. R
International Journal of Engineering Science and Technology , 2012,
Abstract: Recent development mostly based on the high speed internet access of large amount of data at any time over wireless network. Packets loss can also occur due to link failure in wired cum wireless environment. To reduce the loss rate, packet delay, retransmission time, Wi-Max is proposed with cross layer design. In this paper, to improve the performance TCP in the WI-MAX flow its estimating bandwidth of the each packet, reduce the RTT in retransmission which gives more data transfer rate and also reduce the packet drop ratio. Some layers are merging their functions and provide traffic flow with ARQ in Wi-Max. Each node provides information through Access Point which can uplink and downlink feedback about packet as an ACK or NACK. Retransmission mechanism is used for NACK to resend the lost frame through the access point.
Study of Proposed Methods for Improving TCP Performance Over Wireless Links  [PDF]
Anshuman Sinha
Computer Science , 2009,
Abstract: TCP is designed for networks with assumption that major losses occur only due to congestion of network traffic. On a wireless network TCP misinterprets the transmission losses due to bit errors and handoffs as losses caused by congestion, and triggers congestion control mechanisms. Because of its end to end delivery model, congestion handling and avoidance mechanisms, TCP has been widely accepted as Transport layer protocol for internetworks. Extension of Internetworks over wireless links is inevitable with the spread of ubiquitous computing and mobile communications. This paper presents study of different mechanisms proposed to extend Transport Control Protocol and other alternate solutions to enhance end to end performance over lossy wireless links. The paper studies details of different design choices proposed and their technical advantages and disadvantages. Finally, an analysis and proposal for best choice of proposed schemes are made for wireless networks.
Enhancement of TCP Performance with the Help of Snoop Protocol in Wired CUM Wireless Network
Maninder Kaur,Parminder Singh
International Journal of Distributed and Parallel Systems , 2012,
Abstract: The TCP networks have been the only communication for wired media that followed IEEE 802.3networks. This paper attempts to provide a comprehensive overview of this Link Layer approach i.e.Snoop protocol that improving throughput of TCP in wireless networks. It first explains the role of Snoopprotocol that overcomes the limitations of TCP protocols in wireless media. We investigated theapplication of this protocol in wireless networks and observed that a single hop in the wireless networkexperienced large variations in round trip time in a very short period. Without changes to the Snoopprotocol to accommodate these dramatic RTT variations, Snoop was performing badly compared withregular TCP even when there were no packet losses or errors. The main cause for this is prematureretransmissions performed by Snoop. We have modified the Snoop protocol to avoid these unnecessaryretransmissions by having a higher local retransmission timeout. The results showed us that Snoopbenefits from this approach which has made a significant performance improvement over regular TCP inmultihop wired cum wireless networks
Improving TCP Performance Over Wireless Network With Frequent Disconnections  [PDF]
Purvang Dalal,Nikhil Kothari,K. S. Dasgupta
International Journal of Computer Networks & Communications , 2011,
Abstract: Presented in this paper is the solution to the problem that arises when the TCP/IP protocol suite is usedto provide Internet connectivity through mobile terminals over emerging 802.11 wireless links. Takinginto consideration the strong drive towards wireless Internet access through mobile terminals, theproblem of frequent disconnections causing serial timeouts is examined and analyzed, with the help ofextensive simulations. After a detailed review of wireless link loss recovery mechanism and identificationof related problems, a new scheme with modifications at link layer and transport layer is proposed. Theproposed modifications which depend on interaction between two layers (i) reduce the idle time beforetransmission at TCP by preventing timeout occurrences and (ii) decouple the congestion control fromrecovery of the losses due to link failure. Results of simulation based experiments demonstrateconsiderable performance improvement with the proposed modifications over the conventional TCP,when a wireless sender is experiencing frequent link failures.
Improving TCP Performance over Wireless Network with Frequent Disconnections  [PDF]
Purvang Dalal,Nikhil Kothari,K. S. Dasgupta
Computer Science , 2011,
Abstract: Presented in this paper is the solution to the problem that arises when the TCP/IP protocol suite is used to provide Internet connectivity through mobile terminals over emerging 802.11 wireless links. Taking into consideration the strong drive towards wireless Internet access through mobile terminals, the problem of frequent disconnections causing serial timeouts is examined and analyzed, with the help of extensive simulations. After a detailed review of wireless link loss recovery mechanism and identification of related problems, a new scheme with modifications at link layer and transport layer is proposed. The proposed modifications which depend on interaction between two layers (i) reduce the idle time before transmission at TCP by preventing timeout occurrences and (ii) decouple the congestion control from recovery of the losses due to link failure. Results of simulation based experiments demonstrate considerable performance improvement with the proposed modifications over the conventional TCP, when a wireless sender is experiencing frequent link failures.
Performance Analysis of AQM Schemes in Wired and Wireless Networks based on TCP flow  [PDF]
Abdullah Al Masud,Hossain Md. Shamim,Amina Akhter
International Journal of Soft Computing & Engineering , 2011,
Abstract: TCP is the main protocol that carried the traffic in a reliable way. IP based network always facing congestion because of increasing traffic. To control congestion and implement QOS in TCP we perform a comparative study between different active queue management techniques. Queue management is an important part to provide for better utilization of buffer. Our objective is to perform a comparative study of RED, DropTail, REM and PI in wired and wireless network based on the number of TCP flows and how they perform in congested link.
Modeling Network Coded TCP Throughput: A Simple Model and its Validation  [PDF]
MinJi Kim,Muriel Medard,Joao Barros
Mathematics , 2010,
Abstract: We analyze the performance of TCP and TCP with network coding (TCP/NC) in lossy wireless networks. We build upon the simple framework introduced by Padhye et al. and characterize the throughput behavior of classical TCP as well as TCP/NC as a function of erasure rate, round-trip time, maximum window size, and duration of the connection. Our analytical results show that network coding masks erasures and losses from TCP, thus preventing TCP's performance degradation in lossy networks, such as wireless networks. It is further seen that TCP/NC has significant throughput gains over TCP. In addition, we simulate TCP and TCP/NC to verify our analysis of the average throughput and the window evolution. Our analysis and simulation results show very close concordance and support that TCP/NC is robust against erasures. TCP/NC is not only able to increase its window size faster but also to maintain a large window size despite losses within the network, whereas TCP experiences window closing essentially because losses are mistakenly attributed to congestion.
An Experimental Improvement Analysis of Loss Tolerant TCP (LT-TCP) For Wireless Network
Md. Abdullah Al Mamun,Momotaz Begum,Sumaya kazary,Md. Rubel
International Journal of Advanced Computer Sciences and Applications , 2011,
Abstract: Now-a-days TCP is a famous protocol used in Internet but the main problem is packet losses due to congestion. In this thesis we proposed a new Loss Tolerant TCP (LT-TCP), an enhancement of TCP which makes it robust and applicable for extreme wireless environment. In the proposed LT-TCP two additional term, data and data header compression are added in existing LT-TCP. We reduce the total volume of data and packet size in our adaptive method which is able to minimize the congestion and increase the reliability of wireless communication. The ECN respond about random data packet loss and disruption process. The overhead of Forward Error Control FEC is imposed just-in-time process and target to maximize the performance even if the path characteristics are uncertain. This proposal show that it will perform better over regular TCP and it is possible to reduce packet losses up to 40-50%.
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