Adaptive Resource Allocation for Multiuser OFDM Systems in the Presence of ICI

• Main Authors: Tain-Sao Chang, 張添壽
• Other Authors: Jenn-Kaie Lain
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/80117335543595182133

博士 === 國立中正大學 === 電機工程所 === 98 === The research in this dissertation addresses the dynamic resource allocation for multiuser orthogonal frequency division multiplexing (OFDM) systems with inter-carrier interference (ICI). Dynamic resource allocation has been identified as one of the most promising techniques to enhance spectrum efficiency. Firstly, we provide an overview of existing optimization techniques in multiuser OFDM systems. The techniques can be broadly categorized into two: rate adaptive (RA) and margin adaptive (MA). The goal of RA is to maximize the system throughput subject to quality of service (QoS) and total available transmission power. The objective of MA is to minimize the transmission power under data rate and QoS constraints. Consequently, two different optimization problems for multiuser OFDM systems with ICI are studied. The optimization problems for both RA and MA are formulated. To solve above two optimization problems efficiently, we propose two suboptimal resource allocation algorithms, respectively. According to channel state information (CSI) and QoS requirements of each user, the proposed algorithms properly allocate subcarriers, power, and modulation scheme to improve system throughput under QoS guarantee. Simulation results show that the proposed algorithms can effectively reduce the effect of ICI to improve system performance while the QoS for each user is guaranteed. Besides, an adaptive resource allocation algorithm, based on the RA optimization criterion, is proposed for multicast OFDM systems with ICI. The proposed algorithm according to both the channel state information and the ICI among users dynamically allocate resource to multicast groups. Finally, fairness issue among multicast groups is studied. In this dissertation, we formulate an optimization problem which is always a tradeoff between satisfaction of the proportional fairness constraints and improvement of the throughput objective. To solve this problem efficiently, we proposed a suboptimal resource allocation algorithm. The algorithm fairly allocates resource to multicast groups based on the specific ratio (allocated group data rate over required group data rate) for each iteration. The simulation results show that the proposed algorithm can effectively improve the system performance while proportional fairness among multicast groups is maintained. Hence, the proposed algorithm is more suitable when the multicast OFDM system suffers from the ICI interference.