Receiver-Based ACK Splitting Mechanism for TCP over Wired/Wireless Heterogeneous Networks

Abstract

SUMMARYWith the rapid development of wireless network technologies, heterogeneous networks with wired and wireless links are becoming common. However, the performance of TCP data transmission deteriorates significantly when a TCP connection traverses such networks, mainly because of packet losses caused by the high bit error rate of wireless links. Many solutions for this problem have been proposed in the past literature. However, most of them have various drawbacks, such as difficulties in their deployment by the wireless access network provider and end users, violation of TCP's end-to-end principle by splitting the TCP connection, or inapplicability to IP-level encrypted traffic because the base station needs to access the TCP header. In this paper, we propose a new mechanism without such drawbacks to improve the performance of TCP over wired and wireless heterogeneous networks. Our mechanism employs a receiver-based approach, which does not need modifications to be made to the sender TCP or the base station. It uses the ACK-splitting method for increasing the congestion window size quickly in order to restrain the throughput degradation caused by packet losses due to the high bit error rate of wireless links. We evaluate the performance of our mechanism and show that our mechanism can increase throughput by up to 94% in a UMTS network. The simulation results also show that our mechanism does not significantly deteriorate even when the receiver cannot perfectly distinguish whether packet losses are due to network congestion or bit errors on the wireless links.

Performance Analysis and Enhancement of TCP in Presence of Jitter in Wireless Networks

“…Since TCP adds one packet per RTT, 0 < k ≤ 1. Using the scheme proposed in [2], K/W loss-predictor, distinguish the packet losses as follows. (i) The next packet loss is due to congestion when, (a) the source receives triple-duplicate acknowledgement, (b) the arrival of ACK is longer than one RTT (Next-RTT), and Jitter value is greater than k/w value.…”

“…Given the wireless network parameters C d (down link capacity), C u (up-link capacity), N (number of TCP sessions), R 0 round-trip time, and B RED control parameter, the wireless network system given by (2) to (4) is asymptotically stable in terms of the state variables δw(t) and δq(t) if and only if the control parameters P max and β satisfies ( ) ( )…”

“…To add intelligence to TCP that packet loss is due to transmission and not due to congestion, and mitigate backoff loss, we introduce the term L t (t) in equation (2). The traces in fig.5 represent immediate-recovery of sender window due to jittering.…”

“…Transmission loss occurs very frequently in wireless links which cannot be ignored. Packet loss due to transmission in wired links can be ignored [2], [3]. In addition to this, challenges for applying TCP over wireless link is an end-to-end congestion control.…”

A TCP congestion control method for real-time communication based on channel occupancy of a wireless LAN

“…To improve the performance for an error-prone wireless environment, the congestion window increment method from the receiver side by ACK-splitting has been proposed [4]. Multiple split TCPACKs make it possible to obtain bandwidth of download traffic quickly by increasing cwnd.…”