Dynamic Resource Allocation for Relay-based OFDMA Systems With Fairness Considerations

• Main Authors: Lu, Yen-Shuo, 盧彥碩
• Other Authors: Su, Yu-T.
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/05710535874738957179

碩士 === 國立交通大學 === 電信工程系所 === 97 === Capacity and coverage of an Orthogonal Frequency Division Multiple Access (OFDMA) network can be greatly enhanced by dynamically and opportunistically allocate the radio transmission resources. We restrict our investigation to a single-cell system with multiple cooperative relay stations and mobile stations (MSs). A TDD scenario is assumed and only the uplink transmission with the base station (BS) handling the resource allocation is considered. The transmission resources include subcarriers, power and relays with the later being dedicated relay stations or cooperative MS's with unused signal dimensions. We first consider the scenario that the total transmit energy is to be minimized under rates, QoS and maximum per-subcarrier loaded bits constraints where QoS refers to the bit error rate (BER) requirement. As there is a deterministic relation between the number of bits carried by a subcarrier and the power (energy) needed to achieve a desired BER performance, once the QoS requirement is given, bit-loading (rate-assignment) is equivalent to energy appropriation. The second scenario is concerned about the problem of sum rate maximization with a fairness consideration plus power, QoS and minimum rates constraints. For both scenarios we present two linear-complexity suboptimal solutions. Numerical results are given to show that the proposed solutions do offer attractive performance advantages of either energy-saving or near-optimal sum-rate while maintaining much improved and robust fairness performance.