POWER OPTIMIZATION OF BANDWIDTH EFFICIENT P2P WCDMA TRANSCEIVER IN TACTICAL NETWORKS

Abstract

Power Optimization of Bandwidth Efficient WCDMA Transceiver High data rates combined with high mobility represent a challenge when designing tactical networks. Advanced algorithms are required, resulting in higher complexity, more chip area, and increased power consumption. However, this contrasts to the limited power supply of mobile devices using spread spectrum techniques. The selected thesis topic is about the application of Point to Point WCDMA transceiver deployed in the Tactical Networks, optimized regarding its power consumption, with the focus on the dynamic precision scaling. This device is also made bandwidth efficient, as it uses adaptive modulation scheme and chooses the appropriate modulation scheme, sending more data using the same power as per channel conditions. So a tradeoff has been studied between modulation schemes, word lengths and number of users in a WCDMA system in tactical environment. This thesis was dealt with in three parts. Firstly, it deals with the simplified physical layer of the WCDMA. This involves the exclusion of a few components and control section to emphasize more on the baseband portion, and to make it convenient for MATLAB® implementation. Necessary parts involving spreading, scrambling, digital modulation, and Gaussian channelization are being incorporated in this section. Secondly, the behavior of P2P WCDMA based physical layer is evaluated in the tactical environment. This is intended to be done by analyzing the underline system in multipath fading channels of tactical terrains. SUI channels were studied and implemented for the system evaluation in this phase, considering SUI channels as an approximation of tactical environment. To accommodate the needs of multipath fading effects, Rake receiver has been studied and added in the WCDMA transceiver module and effects of higher order modulation and delay spread of a channel have been studied in it. To improve the performance of classical rake in high delay spread; some amendments had been studied and incorporated apart from complex multiuser detection techniques (MUD). By utilizing the idea that reduced wordlength means reduced area which leads to reduced power consumption; in the last phase the system has been mapped from floating point to fixed point using MATLAB® Fixed point Toolbox. Optimum wordlength was found using Gradient Search method using Fixed point toolbox and Transformation toolbox by Han [1]. Simulation results were compared for floating and fixed points WCDMA systems.