Multi-level Power Allocation for Secondary Users in Cognitive Radio Networks with Partial Channel State Information

• Main Authors: Wei-Zhe Lee, 李維哲
• Other Authors: Wan-Jen Huang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/30715909621861466381

碩士 === 國立中山大學 === 通訊工程研究所 === 102 === This thesis investigates power allocation strategy in underlay cognitive radio networks. Different from the conventional strategies that assign the secondary transmitter with single or binary power levels, we adopt multi-level power allocation strategy at secondary transmitter according to the sensing results of the primary spectrum. The secondary transmitter takes two slots to accomplish the transmission: sensing and data transmission slot. The secondary transmitter first evaluates energy of signal received over the primary spectrum during sensing slot, and quantizes the sensing results. During the data transmission slot, the secondary transmitter will send message with a power level which depends on the quantization of sensing results. We assume that secondary transmitter has perfect CSI of those links connected to the secondary transmitter, and statistical CSI of other links. The proposed transmission strategy aims to boost secondary receiver’s SNR (signal-to-noise radio) subject to satisfying the outage constraint of the primary user. We adopt gradient search and distortion measure to find the local optimum of power levels and quantization regions recursively. Simulation results show that the optimal quantization region will eventually converge to the result of two intervals. It implies that if we can obtain reliable sensing result during the first slot, the multi-level power allocation strategy can be simplified to a binary power allocation results with comparable performance of the secondary’s transmission.