TCP Performance In Wireless Networks Research Articles

A fuzzy-based mechanism for delay window adjustment to improve TCP performance in wireless multi-hop networks

TCP protocol was initially designed for wired networks to guarantee reliable data transfer. In wired networks, TCP assumes congestion if data packets are dropped. However, this assumption does not hold when the end-to-end path includes wireless links, where, high bit error rate (BER), shared medium and dynamic nature of the wireless channel may cause packet loss. This results in a severe degrade in performance of standard TCP in wireless networks. On the other hand, TCP cannot be changed fundamentally due to the large base of installation in the wired network. Delayed-ACK generation at the TCP receiver has been proposed to mitigate collision rate within wireless network. However, choosing appropriate delayed window size is an important issue. In this article, we propose a new delayed-ACK approach based on a fuzzy controller to improve TCP performance in wireless networks. The major advantage of our mechanism is reducing the overhead and the collision rate in multi-hop wireless networks. We also compare our proposal with some of well-known studies. Simulations results confirm good performance of our mechanism.

Cross-Layer Explicit Link Status Notification to Improve TCP Performance in Wireless Networks

To alleviate the performance degradation of conventional TCP in wireless networks, many schemes have been proposed so far. One category of such schemes is the Explicit Loss Notification (ELN) scheme in which TCP senders are notified of wireless losses so as to avoid congestion control against those losses. Thus the key design factor of the ELN scheme is how to detect wireless losses accurately and rapidly. This paper proposes a new ELN scheme, in which wireless losses are detected by monitoring the operation of the wireless link layer. By exploiting such cross-layer design, the proposed scheme can detect wireless losses without additional transmission over the wireless link and thus achieves accurate detection with minimum delay. The proposed scheme additionally sends new information, that is, Explicit Retransmission Start Notification, in order to prevent spurious timeouts of the TCP senders. Furthermore, in order to handle packet reordering and avoid successive shrinking of a congestion window due to multiple packet drops, a new TCP modification is proposed. Through intensive simulations, it is demonstrated that the proposed scheme outperforms the other ELN schemes, and yields the throughput performance of more than 400% of TCP-Reno and 150% of Snoop in the considered environments.

Considering Spurious Timeout in Proxy for Improving TCP Performance in Wireless Networks

In this letter, we introduce a new proxy that effectively prevents unnecessary retransmissions from flowing over a wireless link on a path with sudden delay. The proposed Spurious Timeout (STD) algorithm detects spurious timeout based on the data and acknowledge sequence number. It responses to spurious timeout by filtering duplicate acknowledgements that can cause spurious fast retransmission. Simulation results show that the proposed STD algorithm performs better than, or as well as, other end-to-end mechanisms.

Considering spurious timeout in proxy for improving TCP performance in wireless networks

In this paper, we introduce a new proxy that effectively prevents unnecessary retransmissions of Transmission Control Protocol data segments from flowing over a wireless link on a path with sudden delay. The proposed Spurious Timeout Detection (STD) algorithm detects spurious timeout based on the data and acknowledge sequence number. It responses to spurious timeout by filtering unnecessary data transmissions that can cause spurious fast retransmission. Simulation result shows that proposed STD algorithm performs better than, or as well as, other end-to-end mechanisms in a certain range of data rate.