Vinh Van Phan

MAC layer packet-length adaptive CLSP/DS-CDMA radio networks: performance in flat Rayleigh fading channel

We analyse throughput-delay performance of an unslotted DS-CDMA packet radio network (PRN) using the channel load sensing protocol (CLSP) and packet-length adaptation. This paper shows that while error-correcting channel coding has not yet been effective in heavily correlated flat fading environments, adapting the length of radio packets to time-varying channel conditions is a simple adaptive technique for maintaining and improving the system performance and the energy efficiency of mobile terminals. In our modeling we study the correlation between fade duration statistics and packet length in a flat Rayleigh fading channel under the effects of imperfect power control and user mobility. The results are used to derive practical and robust adaptation mechanisms and performance characteristics. A number of numerical results is presented. This paper lays the groundwork for exploiting adaptive radio possibilities on media access control (MAC) layer in unslotted DS-CDMA PRN.

Unslotted DS/CDMA packet radio network using CLSP and packet-length adaptation in Rayleigh fading channel

We to high uncertainty of radio channel and imperfect power control, throughput-delay performance of packet radio networks (PRN) may suffer from disgraceful degradations. This paper shows that, while error-correcting channel coding has not yet been effective in heavily-correlated flat fading environments, adapting the length of radio packets to time-varying channel conditions is a simple adaptive technique for maintaining and improving the system performance and the energy-efficiency of mobile terminals. Based on a comprehensive study of correlation between fade duration statistics and packet length over a flat Rayleigh fading channel, robust adaptation mechanisms and performance characteristics are derived for an unslotted CLSP/DS-CDMA PRN system.

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.