TCP over micro mobility protocols: a systematic ripple effect analysis

With the increasing popularity of powerful handheld/mobile computing devices and ubiquitous availability of wireless connectivity, protocols that support mobility are becoming increasingly important. It is critically important to explore and understand the design space, so that appropriate mechanisms are incorporated into the design to provide the required performance under the varied environments and services provided by the lower layers. The mechanisms incorporated into the design may interact in subtle ways with the mechanisms of the higher layer to produce unintended effects. We study how the different mechanisms of the lower layers (IP and MAC) that support mobility affect the performance of Transmission Control Protocol (TCP). We use the building block framework to capture and study the wide variety in the IP layer handover optimization mechanisms. We use detailed 802.11 models to study the effect of MAC layer mobility support on TCP. We show by simulation how different mechanisms affect TCP differently in different scenarios. We also show results that are very counter intuitive, like buffering packets does not always improve TCP throughput and TCP-Tahoe performs better than its more sophisticated counterparts.