Research On Adaptive Resouce Allocation Algorithma In OFDM

With the development of mobile communication, the required service is expanded from traditional voice to data, and now to multimedia. With the higher and higher expectation and requirement to the mobile communication speed and quality, the radio spectrum resources are being strained. So OFDM (Orthogonal Frequency Division Multiplexing) is become more and more popular nowadays for its high frequency efficiency and strong ability to anti-disturb. It is also regarded as the main technology of next global mobile communication system.OFDM is a widely used multi-carrier modulation scheme which divides the multipath fading channel into a number of flat fading channels. A big advantage is that power and information bits can be allocated depending on the channel characteristics to get a high resource using ratio. In this paper, the emphasis is laid on one of the key techniques in OFDM systems,the adaptive resource allocation techniques for OFDM systems.Now, there are many ways to solve how to allocate the resources. Generally, they can be divided into two classes:fixed resource allocation and dynamic resource allocation. Fixed resource allocation schemes, such as time division access (TDMA) and frequency division multiple access (FDMA),assign an independent dimension, e.g.time slot or sub channel, to each user. A fixed resource allocation scheme is rigid regardless of the current channel condition. This paper mostly analyzes dynamic allocation algorithm, and studies the single-user and multi-user resource allocation algorithm respectively. Firstly, several typical adaptive resource allocation algorithms are introduced, and an improved algorithm is proposed based on these algorithms.These existing algorithms and improved algorithms are compared by simulation. Then, the adaptive sub-carrier power and bit allocation algorithms in multi-user OFDM system are studied, and some algorithms are also analyzed by simulation.