Efficient performance evaluations for forward-link cellular DS-CDMA over fading channels

This research is emphasized on the performance evaluations for forward-link (FL) cellular direct sequence code-division multiple-access (DS-CDMA) systems using some efficient approaches. A generic cellular CDMA which takes into account the effects of path loss, fading, user's spatial distribution and multiple-access interference (MAI) (which also includes inter-cell interference (ICI)) is considered. Three popularly adopted fading statistics, namely Rayleigh, Nakagami and Ricean distributions, are investigated. The performance measure is focused on the average bit-error rate (BER).Doctor of Philosophy (EEE

Subcarrier Sensing for Distributed OFDMA in Powerline Communication

Abstract—Powerline communication (PLC) is a preferred choice for smart home network. In this paper, a new system structure is proposed for PLC, which is based on distributed orthogonal frequency division multiple access (DOFDMA). Sub-carrier sensing, i.e., sensing every OFDM subcarrier to see if it is occupied or not, is proposed to replace the conventional carrier sensing multiple access (CSMA) for multi-user contention of a channel. This structure, borrowed from cognitive radio, allows multiple users to opportunistically share the same channel on different subcarriers and therefore increases the channel capacity. Two subcarrier sensing methods are proposed: one is based on information theory and the other is based on successive energy comparison. Simulations are provided to verify the methods. I