Modeling TCP performance over wireless channels using fixed-point approximation

Wireless channels are prone to transmission errors. Loss of IP packets due to imperfect local error concealment strategy implemented at the data-link layer is the major reason for TCP performance degradation in wireless networks. These losses are misinterpreted by TCP senders as congestion indications and subsequently lead to decrease of the sending rate. In addition to wireless losses IP packets can also be lost due to buffer overflow at the IP layer. To study performance experienced by a number of concurrent TCP sessions sharing the same wireless bottleneck we adopt the fixed-point approach. We demonstrate that throughput provided to TCP flows is complex cross-layer function depending on wireless channel statistics and configuration of the protocol stack at the wireless interface.