Multiple network coded TCP sessions in disruptive wireless scenarios

Abstract

TCP over wireless networks is challenging due to random losses and DATA-ACK interference. Random linear coding schemes have been proposed to improve TCP robustness against extreme random losses, but a critical issue still remains of DATA-ACK interference. To address this problem, we use inter-flow coding between DATA and ACK at potential intersecting nodes to mitigate self-interference. In addition, a pipelined random linear coding scheme with adaptive redundancy is introduced to overcome high loss rates over unreliable links. The resulting coding scheme, ComboCoding, combines inter-flow and intra-flow coding to provide robust, fair TCP communication in multi-flow disruptive wireless networks. Simulation results show that TCP with ComboCoding delivers higher throughput than other coding options in high loss scenarios. Moreover, we study the behavior of multiple TCP flows intersecting and interfering with each other in the same ad hoc network. The results show that ComboCoding consistently provides better fairness among multiple co-existing TCP sessions when compared with TCP without coding. The main contributions of this paper are: the practical design of random linear coded packets and XOR coded packets on bi-directional streams (DATA and ACK), the adaptive redundancy control scheme, and the multiple coded TCP sessions fairness evaluation.

Impact of network coding on TCP performance in wireless mesh networks

“…Their simulations were performed using a chain topology, and show a throughput gain of up to 100%. Chen et al [11] combine a similar idea of coding TCP data and ACK packets with an intra-flow 1 coding scheme to reduce the effect of high loss rates. In [12], Hassayoun et al studied the impact of random losses and packet loss synchronization on TCP performance in WMN.…”

CodeMP: Network coded multipath to support TCP in disruptive MANETs

“…As a consequence, re-optimization must be triggered whenever a parameter changes value. Similar to the approach presented in [15], C.-C. Chen et al propose a practical network coding design, ComboCoding, which uses both intra-and inter-flow coding and adapts the redundancy to the estimated loss rates [16]. ComboCoding further eliminates all explicit control messages and relies completely on overhearing.…”

“…The intra-flow coding scheme is based on our previously published Pipeline Coding [16,21] and can be described as follows. Consider a sequence of equal-sized packets p 1 , p 2 , p 3 , …, that are generated by application and let k denote the number of packets in a coding generation.…”

“…Besides, relay nodes also have a forwarding redundancy to determine the number of re-encoded packets to generate when an innovative packet arrives. Readers are referred to our previous publications for Pipeline Coding details [16,21,23].…”

“…Although performance is improved, the semantic of TCP ACKs is redefined by requiring TCP modifications or an additional adaptation layer at both TCP sender and TCP receiver. Following [14], several approaches have been proposed to address both self-interference and random errors issues, such as I2NC [15] and ComboCoding [16]. Nevertheless, all the above schemes assume a pre-determined single-path route given to the coding module, which is impractical in disruptive MANET scenarios.…”