Performance analysis and modeling of errors and losses over 802.11b LANs for high-bit-rate real-time multimedia

摘要

Inherent error-resilient nature of multimedia content renders two high-level options for wireless multimedia application design. One option is to employ (semi-) reliable wireless Medium Access Control (MAC) functions in conjunction with the traditional User Datagram Protocol (UDP). The other option is to employ a less-reliable MAC and transport layer protocol stack that passes corrupted packets to the application layer, which consequently achieves a “higher throughput”. This “higher throughput” traffic, however, could contain many “useless” corrupted packets. In this paper, we address key questions regarding the viability of the above two options for the support of high-bit-rate wireless multimedia applications over 802.11b LANs. First, we study the level of throughput improvements realized by the less-reliable protocol stack at 2, 5.5 and 11 Mbps data rates using actual measurements that mimic realistic home or business settings. Second, we analyze and model the error patterns within the “higher throughput” corrupted packets to evaluate their potential impact on multimedia applications. Third, we compare the amount of overhead that is needed at the application layer to achieve different levels of lost- and corrupted-packet recovery for the two (reliable and less-reliable) protocol stack scenarios. Major conclusions of our study include: (1) Either protocol-stack is viable at 2 Mbps while neither of them is viable at 11 Mbps under realistic settings; and (2) Some benefits of the “higher throughput” corrupted packets can be realized at 5.5 Mbps when combined with a joint erasure-error protection algorithm at the application layer.