Diversity reception, power control and channel allocation in multi-media multi-rate CDMA networks

In this thesis, diversity reception, power control and channel allocations in multi-media multi-rate CDMA networks are considered. Multipath diversity reception problems in a DS/CDMA system with different spreading bandwidth for multi-media traffic are investigated first. Optimal multipath receivers for multi-rate CDMA systems with M-ary orthogonal modulation system under different system capability assumptions are designed and analyzed. We propose a variable tap-delay Rake receiver without knowledge of path delay and signal strength. Since the tap-delay between two fingers can be changed, the same rake receiver structure can be used in demodulating two types of traffic by tuning the tap-delay. Analysis of combining space diversity and Rake receiver is also presented in this part.;Optimal power control schemes for the DS/CDMA system offering multi-media services with variable transmission rate and different spreading bandwidth are proposed. The transmission power of a mobile station (MS) in the reverse link and the allocated power to a mobile in the forward link are proportional to the power control law which is a function of the distance between the base station and mobile, the transmission rates and interference level. All links are affected by path loss, Rayleigh fading and log-normal shadowing. A two layered power control scheme (cell level and network level) is proposed in the thesis where the transmission power is optimized in cell level and system capacity is maximized in networks level.;Power control problems in a multi-rate multi-media CDMA mobile satellite system with multiple-beam is also considered. The effect of uneven satellite antenna gain on the performance of the CDMA system is investigated. The satellite channel is modeled as a mix of Ricean fading (unshadowed) and Rayleigh fading followed by log-normal (shadowed). Two power control schemes for compensating path loss, uneven antenna attenuation, and reducing the effect of channel fading and shadowing are proposed. One is an equal received bit-energy power control and the other is the optimal power control scheme.;Channel allocations in a multi-media multi-rate CDMA network is considered. The multi-rate CDMA system is designed as a fixed-chip-rate variable- data-rate system. We consider three types of traffic: voice, high-priority data, and low-priority data and two types of transmission rate in the multi-rate CDMA system. A variable-rate admission policy is proposed for voice users and high- priority data users so that the system can accommodate more users. Direct and non-direct allocation schemes are proposed and investigated in the thesis. A distributed queueing model is also presented to evaluate the packet delay and throughput for low-priority data users in both forward and reverse links. Performance of some allocation schemes for low-priority data are proposed and analyzed.