Radio resource allocation and control schemes in wireless communication systems

Abstract

Radio resource management schemes in wireless systems such as orthogonal frequency division multiple access (OFDMA), 1x evolution data only (1xEV-DO), and code division multiple access (CDMA) systems are addressed. The allocation schemes for those systems and some control algorithms such as call admission and load sharing using load measures are provided in this work. In OFDMA systems, subcarriers and power allocation schemes in OFDMA systems are investigated. The problems in downlink and uplink are provided to maximize rate-sum capacity by differentiating the power constraints. Two necessary conditions for the optimality can be drawn from Karush-Kuhn-Tucker (KKT) condition. Using the conditions, some practical algorithms are proposed: the greedy subcarrier allocation based on the marginal rate function and the iterative power allocation based on the water-filling algorithm. In downlink, the algorithm gives the optimal solution. However, in uplink, it is not optimal but achieves almost near optimal solution for small-sized problems. The water-filling and the equal power allocation display similar performance when they are combined with the proposed subcarrier allocation algorithm. In 1xEV-DO systems, time slot allocation algorithms in downlink are suggested. The defect in the conventional proportionally fair algorithm is that it can not provide the required quality of service (QoS) and priority for the diverse needs of each user. Enhanced scheduling algorithms are proposed to resolve this problem. The algorithms adopt some parameters related to the required QoS. In setting the parameters, two cases are considered. One is an exponentially varying parameter as in the conventional power control scheme, and the other is a constant parameter determined by the QoS. There is a trade-off between achieving higher system throughput and meeting required QoS. In CDMA systems, power allocation schemes in CDMA systems are covered when there are different requirement...