TCP over asymmetric CDMA radio links

In TCP-supported traffic flows like file downloading and Web browsing, the connection is inherently asymmetric since the size of TCP data packets is different from that of TCP ACK packets. To exploit the asymmetry, different uplink and downlink channel data rates can be allocated in wireless Internet access through third-generation mobile cellular systems. We investigate TCP performance over asymmetric CDMA radio links in cdma2000 system. It is shown that appropriate downlink/uplink data rate ratio should be determined in order to achieve comparable system performance as that of the symmetric radio links, and the required data rate ratio varies with radio channel conditions, especially frame error rates (FERs). This phenomenon is mainly due to the fact that frame error recoveries at the RLP (radio link protocol) for uplink and downlink channels are dependent on each other. To use our results in practical systems, we propose a procedure on channel data rate allocations for TCP-supported data services in order to achieve acceptable system performance and use channel resource efficiently