Energy-Efficient Smart Packet Access in WCDMA Networks: Performance with TCP/IP based Applications

This paper presents a performance analysis of adaptive packet access (PA) in WCDMA networks with TCP/IP based applications. The focus is on optimal tradeoffs between energy efficiency and TCP throughput over burst-error correlated fading channels. The channel model is adopted for low mobility PA applications. Both high-speed PA (HSPA) and low-speed PA (LSPA) with radio-link retransmission-and-error-control protocols are studied. By theoretical analysis and simulation, we show that in HSPA adapting the radio-packet retransmission period to the channel conditions significantly reduces the number of retransmissions while maintaining adequate TCP performance. This method is referred to as smart packet dispatching (SPD). In LSPA, adapting the length of radio packets to the channel conditions significantly increases the effective TCP throughput. This method is referred to as smart packet length (SPL). The SPD and SPL, commonly called smart packet access (SPA), are capable of avoiding burst-error states of correlated fading channels and therefore enhance the robustness of radio transmissions and allow the system to operate with much lower fade margin or transmit-power. Furthermore, the SPA schemes improve energy efficiency and system performance without need of excessive signal processing.