Joint Optimization Of Resource Allocation And PAPR Reduction For OFDMA Systems

With the continuous development of wireless communication, people put forwardhigher requirements to the data transfer rate and spectrum efficiency for mobilecommunication systems. OFDM (Orthogonal Frequency Division Multiplexing)technology is playing an important role in the4th generation mobile communicationsystem for its characters. OFDMA (Orthogonal Frequency Division Multiple Access),which is based on OFDM system, attracts peoples’ attention. OFDMA systems canachieve the flexible configuration of frequency resources by using flexible resourceallocation algorithms. Dynamic resource allocation problem is adaptively to decideresource allocated to each user. In order to make full use of the limited wireless networkresources, which leads to the problem of resource allocation in OFDMA systems,increasing attention has been paid.As a multi-carrier system, OFDMA also makes high PAPR as one of its majorobstacles in implementing. As a result, when a high PAPR signal passes through apower amplifier, the power amplifier may be pushed to a saturation region, causingsignal distortion. It is necessary to find the effectively method to reduce the PAPR.Nowadays, the existing methods usually solve the problem of subcarriers allocation orPAPR reduction independently.Actually, the PAPR of OFDM signal has a tightrelationship with the subcarriers allocation. Through comprehensive analysis andresearch of the two problems, the joint optimization method not only makes full use ofthe spectrum resources to meet the transmission business QoS requirements, but alsoreduces the PAPR in OFDMA system effectively. Besides, this method has a betterpractical value and scientific research significance.This paper firstly describes the system model of OFDM and OFDMA, resourceallocation optimization criterion, three commonly used resource allocation algorithmsand simulation comparison. Then a variety of OFDM system PAPR suppressionalgorithms are researched. After that, we focus on Tone reservation algorithm and itsimproved algorithms. The improved Tone Reservation algorithm has a better overallperformance through simulation analysis. Finally, we propose a joint optimizationmethod for subcarriers allocation and TR PAPR reduction. By comparing thesimulation results, the proposed method, which is to maximize the total throughput, has a better performance in PAPR reduction with total transmitted power and proportionalfairness constraints.