A Study of Bandwidth Allocation Strategies for Interactive Image Applications

Abstract

Image applications are expected to consume a significant portion of the bandwidth of future integrated service networks. In this paper, we examine the effectiveness of various bandwidth allocation mechanisms for this class of applications. First, we describe how a rate based hop by hop (HBH) congestion control scheme, proposed previously by us for controlling data traffic, may be modified to control the flow of image traffic. The performance of the modified HBH scheme as measured by the average image transfer times is shown to be within 15-30% of an unachievable lower bound. We also compare the effectiveness of the HBH scheme with a hierarchical round robin (HRR) scheme that reserves bandwidth before commencing each image transfer. Our results indicate that the likelihood of exceeding a desired transfer time requirement with the HBH scheme is lower than the blocking probability with the HRR scheme. Moreover, the average transfer times achieved with the HBH scheme are much lower. However, the variation of the transfer time is very small with the HRR scheme. We also show that the HBH scheme may be used to effectively trade transfer time vs image quality.