| Currently, in order to improve the reliability of the air interface in wirelesscommunication system, people usually use the diversity technique against the fadingchannel. Traditional diversity technique send multiple copies of the same signal andcombined to increase the SNR of the received signal at the signal receptor of these copies.Nowadays, multi-user diversity is a multiple user network, since each user’s channelfading is relatively independent, the more users on the system, the better quality of thechannel, then befits of multi-user diversity is greater. Opportunity communication takesadvantage of the opportunity beamforming techniques to artificially produce a large rangeof random fluctuations in the channel to improve the multi-user diversity gain, therebyincreasing the overall throughput of the system.The main purpose of this paper is to improve throughput under Rayleigh fadingchannel multi-user MIMO systems by the opportunity communicate algorithm. This paperintroduces the multi-user MIMO downlink of the channel model and channel capacity, andstudy the opportunity for single beamforming and multi-beamforming impacting onsystem performance, as well as multi-beamforming makes great feedback in the system.For deciding the number of base station of beamforming and dealing with feedbacks ofsystem problems, this paper proposes an adaptive beamforming algorithm opportunitytruncated by setting the decision threshold, truncating match with poor channel transmitbeam to reach the preferred beam, with reducing interference between the beams, and thenachieve the purpose of reducing the amount of feedback. The optimal cutoff threshold ofvarious channel environments obtains through MATLAB simulation technique, provingthat the adaptive optimal threshold cutoff opportunity beam system can effectively reducethe amount of feedback, and in general it will not affect the basic properties of the beamopportunity of improving system throughput and spectrum efficiency. |
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