Rate, Sub-Carrier, and Power Allocations for Multi-Carrier CDMA with LMMSE Multiuser Detections
Conference: PIMRC 2005 - 16th Annual IEEE International Symposium on Personal Indoor and Mobile Radio Communications
09/11/2005 - 09/14/2005 at Berlin, Germany
Proceedings: PIMRC 2005
Pages: 5Language: englishTyp: PDF
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Authors:
Fu, Po-Wei; Chen, Kwang-Cheng (Graduate Institute of Communication Engineering, College of EECS, National Taiwan University, Taipei, Taiwan, ROC)
Abstract:
Allocations of physical transmission rate, sub-carrier, and power in MC-CDMA systems are proposed to minimize total uplink power consumptions for users of different data rate and bit-error-rate (BER) requirements with the receiver using linear minimum-mean-square-error (LMMSE) MUD. Based on Multi-Code (MC) and Variable-Spreading-Length (VSL) strategies for multi-rate transmissions, we derive the discrete-rate transmission capacity of MC-CDMA and propose a simple admission control criterion for users of individual quality-of-service (QoS) demands. This criterion linearly relates the code length with the transmission rate and BER requrets of all users. An iterative power allocation algorithm is proposed after deciding all supportable transmission rates to allocate the sub-carrier power of each user and jointly solve the sub-carrier allocation problem. The results show that in either MC MC-CDMA or VSL MC-CDMA, the most power-efficient allocation is to distribute the power of each user over several sub-carriers of better quality and even concentrate on the best one, if it is exclusive.