Performance Analysis of a Novel TCP Protocol Algorithm Adapted to Wireless Networks

Gonzalo Olmedo,Diego Martínez,Celso De Almeida,Román Lara-Cueva

doi:10.3390/fi12060101

Abstract

As telecommunication systems evolve towards new-generation architectures, likewise, new protocols are created in order to improve efficiency. One of these protocols is Transmission Control Protocol (TCP), which controls the transmission bit rate in function of network congestion. Nevertheless, in wireless communications, there appear problems such as noise and interference, for which TCP was not designed. Based on these problems, there exist some methods trying to mitigate congestion, such as explicit loss notifications and the use of end-to-end codification. The aim of this work was to propose a wireless TCP protocol improvement, considering a negative acknowledgment (NACK), which allows to differentiate between losses due to congestion and losses due to wireless channel issues. NACK employs a small protocol packet and produces improvement in the quality of service metrics. The experiments were carried out in in-door and out-door environments, over an online video game scenario, and over a long-distance wireless link between two islands. The average results show a 25-percent delay improvement and a 5-percent jitter improvement when compared to the original TCP Reno protocol, while for throughput a 90-percent improvement was achieved for distances between 100 and 414 m.

Highlights

The Transmission Control Protocol (TCP) was originally designed for wired networks, by interpreting packet loss (PL) as congestion consequence; in wireless networks, PL is caused by issues in the communication channel, such as interference, multi-path fading, mobility, and reflections, which may produce a PL misinterpreting [1]
Congestion Window (CWND) control algorithms achieve their goal in wired networks, in wireless networks, unnecessary executions of the four algorithms occur frequently, which, in turn, causes low transmission bit rates, as seen in the results presented in [4]
We evaluated the proposed TCP-negative acknowledgment (NACK) protocol under different configuration environments and distances by using laptops with the modified TCP-NACK protocol under the Ubuntu kernel, and applying the necessary communication standards for each experiment

Summary

Introduction

The Transmission Control Protocol (TCP) was originally designed for wired networks, by interpreting packet loss (PL) as congestion consequence; in wireless networks, PL is caused by issues in the communication channel, such as interference, multi-path fading, mobility, and reflections, which may produce a PL misinterpreting [1]. TCP can use four algorithms for Congestion Window (CWND) control: Slow Start, Congestion Avoidance, Fast Retransmit and Fast Recovery. Slow Start increases exponentially the transmission bit rate until a packet loss is detected. From this point, the Congestion Avoidance algorithm increases the transmission bit rate linearly, and when three duplicate ACKs are detected, TCP reduces the transmission bit rate by half. CWND control algorithms achieve their goal in wired networks, in wireless networks, unnecessary executions of the four algorithms occur frequently, which, in turn, causes low transmission bit rates, as seen in the results presented in [4]

Objectives

Results

Conclusion