Performance of DS-CDMA protocols in wireless LANs

The performance of direct-sequence code-division multiple access (DS-CDMA) systems in indoor wireless channels is presented. TCP traffic, channel noise and signal characteristics are measured using commercial products that implement the IEEE 802.11b DS-CDMA standard. The measured throughputs for a low density mobile network are typically around 4.2 Mbps when one of the two end-systems is on the wired segment. Multipath interference is shown to contribute to significant degradation in TCP performance. Packet loss rates ranging from 0.02 to 0.2 percent are observed in line-of-sight conditions. The BER performance of DS-CDMA is estimated using an image source based channel model of the rectangular room to compute the spatial variation of the channel impulse response. These impulse responses provide a quantitative measure of the system performance and provide estimates of signal power levels required for supporting high data rates in channels influenced by multipath interference.