| The wireless communication system will provide higher data rates than the 3Gsystem in the future. And it can support wireless multimedia communication andhigh speed access to Internet. The phenomenon of fading and multipath are thepractical problem which should be overcome in the high speed wirelesstransmission. Orthogonal The technology of Frequency Division Multiplexing(OFDM) has been giver much attention in the high speed data transmissionsystem for its ability of countering multipath fading. And it has become one of thecore technique in the beyond 3G and even 4G system.Multi-Input and Multi-Out (MIMO) can improve the system capacity andperformance effectively, and it also can enhance the system security. It has sharpeffect in resolving the capacity bottleneck in the future wireless network whichwill develop rapidly. Because of the limited frequency resource, it will be a goodchoice to improve the frequency spectrum efficiency of OFDM system by usingmulti-antenna on both transmitter and receiver. MIMO has been adopted in theproject of high speed downlink packet by 3GPPCode Division Multiple Access (CDMA) has become the key technology inthe third mobile communication system for its good characteristics of counteringmuliaccess interference, the ability of keeping secret, soft capacity, and highfrequency spectrum efficiency. But the capacity of CDMA is restricted by themuliaccess interference and mulipath interference. Fortunately this limitation canbe remedied by OFDM. Therefore, the OFDM-CDMA comes into being. Therewill be anisomerous services in uplink and downlink, different requests for kindsof services, and limitation in power and size of terminal in the future mobilecommunication system. So it is a very important problem to solve the downlinkresource allocation in OFDM-CDMA system.Power control and adaptive data rates allocation are all basic techniques whichcan provide reliable transmission in fading channel. Both of them are main meansof wireless resource allocation. Generally speaking, power control can balance thepower of every subcarrier according to the channel state. Because those channelswith high channel gains will burden high data rates, so the capacity can beimproved greatly. Furthermore, the system with adaptive data rate allocationunder constant power will get more throughput than that of the system withadaptive power control under constant data rate. The main work and content are summed up as follow: The dissertation consists of six chapers. The study meaning of this dissertation in described in chapter 1. It introducethe development of mobile communication, especially the OFDM and SpreadSpectrum Communication. And it also summarizes the research status in quo ofresource allocation in OFDM-CDMA system. In Chapter 2, the basic theory of OFDM is described. The principle of theimplement by using FFT is analyzed. The principle of eliminating ISI by usingcyclic prefix and the effect of it is discussed. the peak-to-average ratio inOFDM system, And two methods of decreasing the peak-to-average ratio areintroduced, which are called amplitude limited method and coding method At theend of this chapter, the advantage and disadvantage of OFDM is given.In Chapter 3, the basic model of MIMO-OFDM and the predecessors'theory oneigen-channels is introduced. Based on them, a novel inplementation scheme formaximizing throughput is discussed using adaptive modulation for MIMO-OFDMsystems is proposed. For a fixed number of antennas, two simple method of datarate allocation to maximize the throughput , which are based on the relationshipbetween the number of transmit and/or receive antennas and the distribution ofeigenvalues was proposed. Simulation results show that the two methods performnearly as well as the ideal rate-allocation without loss in BER performance. Andall the methods can much reduced computation complexity. In Chapter 4, the basic transmitter model and receiver model ofOFDM-CDMA in Rayleigh fading channels in analyzed. Three techniques ofsynthesizing the received signals are summarized, which are called Equal GainCombing, Maximal Radio Combining and Controlled Equalization. For a very...
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