Dynamic Resource Allocation In The Multi-user Mimo - Ofdm System And Limited Feedback Technology Research

In MIMO-OFDM system dynamic resource allocationtechnology,which provides fair guarantee, higher ulitization rate ofwireless channel and support of multiuser QoS level in a way, improvesystem spectrum efficiency and throughput effectively.Therefore it is theone key technology of4G（The Fourth Generation）.In the process ofresource allocation, the transmitter needs to get the downlink channelstate information (CSI), so how to reduce the consume of feedbackand make full use of the feedback overhead, is also a technologythat’s so important.Firstly we analyse the two system which is multiuser wirelessresource allocation, one is max throughput system on the requirementof total power and users’BER. Another is proportional fairness sysytemguaranteeing the proportional fairness among users. For the firstsysytem, We propose a new scheme which adaptively allocates theresource in the downlink scenario of MIMO-OFDM networks on therequirement of users’BER in order to ensure user’s BER. Based on thestatus of channel, this allocation scheme mainly contains thesubcarrier、bit and power allocation via making use of all eigenvaluesubchannels. Compared with max eigenvalue algorithm and spacialsubchannel average algorithm via simulation, results show thateffectively enhance the system throughput and satisfy the requrementof user’ BER. For the second system, Subject to constraints on totalpower bit error rate the algorithm can maximize overall datathroughput while guaranteeing the proportional fairness among usersand the criteria of subcarrier allocation was derived based on eachuser rate proportionality constraints. The simulation results show that thealgorithm can satisfy differently required data rate and offer balanceand tradeoff between maximizing capacity and fairness among users with the less computation.It will occupy enormous sysytem bandwidth if eNodeB get theperfect CSI. In order to reduce the feedback overhead in the uplinkchannel, We propose a new strategy that is Channel qualityinformation(CQI) feedback and quantization algorithm in multiuserMIMO-OFDM system, the optimal quantization thresholds are providedin order to maximize the average transmission rate of the system basedon the predefined averag e bit errors ratio. Simulation results show thatthe proposed dynamic limited feedback and quantization algorithmcan not only save the feedback cost,but also improve the spectrumefficiency, and the complication of real time operation is well situated.