Performance Analysis of TCP Downstream Between Heterogeneous Terminals in an Infrastructure Network

This work provides a performance characterization of three types of transmissions: upstream, downstream and wireless-to-wireless in an infrastructure network based on IEEE 802.11 a/b/g wireless LAN. Measures were carried out on a test-bed which reproduces on a small scale, a real prototype of such a network. When a PDA is mainly used for downloading data from its stationary server, i.e., a desktop PC, a PC and a PDA acts as a fast sender and a slow receiver, respectively, due to substantial differences in their computational capabilities. Thus, we propose two distinct methods for improving the performance during downstream. First, by increasing the size of a receive buffer for a PDA the congestion window size of TCP becomes more stable. Second, a pre-determined delay between packets to be transmitted at the sender should be given. From the performance point of view a method of buffer sizing is preferred rather than adjusting the inter-packet delay. However, such a delay reduces the number of erroneous packets remarkably.