Buffer-driven adaptive video streaming with TCP-friendliness

Abstract

Existing streaming mechanisms have no consideration for the characteristics of streaming applications because they only consider network stability. In this paper, in order to overcome limitations of the previous work on video streaming, we propose a new adaptive video streaming mechanism. The proposed mechanism includes more sophisticated features that consider both network and user requirements. From the network viewpoint, the proposed mechanism can estimate the TCP-friendly rate suitable for current network conditions. Therefore, it is able to adjust the sending rate of video stream in a TCP-friendly manner and improves the network stability by reducing the packet losses. From the user viewpoint, our mechanism provides the smooth playback by preventing the receiver buffer underflow or overflow. Moreover, it is designed to take into consideration the streaming video content. Through the simulation, we prove that our mechanism efficiently uses the buffer resources and provides improved network stability with TCP-friendliness and smooth playback.

Introduction

The Internet has recently been experiencing an explosive growth in the use of audio and video streaming applications. Such applications are delay-sensitive, semi-reliable, and rate-based. Loss-tolerant video streaming applications, such as video conferencing, prefer UDP (User Datagram Protocol) as a transport protocol that has no congestion control algorithm. The emergence of non-congestion-controlled streaming applications threatens unfairness to competing TCP (transmission control protocol) traffic and possible congestion collapse. UDP is considered selfish and ill-behaving because TCP throttles its transmission rate against the network congestion, whereas UDP does not have such a congestion control algorithm. As a result, the available bandwidth to TCP connections is oppressed and their performance sharply deteriorates because the current Internet does not attempt to guarantee an upper limit on end-to-end delay and a lower limit on available bandwidth [1].

Studies on the congestion-controlled streaming mechanism has been increasingly done since the 1990s [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16]. These works attempt to guarantee the network stability and fairness with competing TCP connections. In [1], non-TCP connections are defined as TCP-friendly when “their long-term throughput does not exceed the throughput of a conformant TCP connection under the same network conditions”. TCP-friendly rate control mechanisms regulate its data sending rate according to the network condition, typically expressed in terms of the RTT (round trip time) and the packet loss probability. Therefore, they improve the network stability and fairness with competing TCP connections. However, by considering only the network stability, these works ignore the quality of video stream which is delivered to the user. Moreover, most of existing streaming mechanisms have no consideration for the characteristics of video stream which affects significantly the quality of streaming services.

In this paper, we propose a new adaptive video streaming mechanism. The proposed mechanism adjusts the sending rate of video stream-based on the current network state and controls the quality of video stream-based on the receiver buffer occupancy. It also considers the characteristics of video stream which is requested from the user. Therefore, our mechanism maintains the network stability accomplished by previous works and achieves the smooth playback by preventing the buffer underflow or overflow.

The rest of this paper is organized as follows. In Section 2, we review and discuss some of the previous works and in Section 3, we present the concept and algorithms introduced in our mechanism. Detailed description of our simulation results are presented in Section 4. Finally, Section 5 concludes the paper and discusses some of our future work.