本文選題：協(xié)作中繼　切入點：放大轉發(fā)　出處：《西南交通大學》2014年碩士論文　論文類型：學位論文

【摘要】：相對有線信道,無線信道由于其傳播空間的開放性與時變特性,存在衰落效應,信號到達接收端時往往已經(jīng)發(fā)生了嚴重的衰減或畸變,這種變化主要是由于信號的衰落引起的�？臻g分集技術以及MIMO技術通過在不同的空間路徑上傳輸多路信號,有效克服了衰落帶來的影響,提高了信息傳輸?shù)目煽啃砸约跋到y(tǒng)容量。但是空間分集需要在接收端或者發(fā)送端安裝一定距離的多根天線,以保證傳輸?shù)亩嗦沸盘柺遣幌嚓P的。然而由于移動終端要滿足便攜性的要求,尺寸不能太大,這就使得空間分集的實用性收到限制。協(xié)作中繼技術通過不同用戶共享彼此的天線實現(xiàn)虛擬的空間分集效果,提高了信息傳輸?shù)目煽啃砸约跋到y(tǒng)容量,在學術界被廣泛研究。本文首先對幾種常見的分集合并技術進行了討論,對QPSK調(diào)制信號最大比合并、等比合并、選擇合并下不同分集鏈路數(shù)對誤碼率性能的影響進行了仿真,并與無分集時的誤碼率特性做比較。接著,本文分析了三節(jié)點構成的協(xié)作中繼系統(tǒng)中AF、DF、SDF以及IR四種不同的中繼模式,對每種中繼模式的誤碼率性能進行了仿真和分析。然后,針對單向中繼系統(tǒng)頻譜利用率低的問題,研究了基于DF的兩階段雙向協(xié)作中繼系統(tǒng)的兩種主要機制,即基于比特級異或和去噪轉發(fā)機制在等功率分配時的誤符號率性能。并在此基礎上以最小化系統(tǒng)的誤符號率為目標,在總功率一定的前提下,針對等功率分配方案不能適應中繼節(jié)點R兩側信道狀態(tài)差異的缺陷,提出了一種最優(yōu)的功率分配算法。仿真結果表明,該最優(yōu)功率分配算法和等功率分配算法相比,可降低系統(tǒng)的符號錯誤概率,并提高系統(tǒng)的吞吐量性能。
[Abstract]:Compared with wired channel, wireless channel has fading effect because of its open and time-varying characteristics of propagation space. When the signal arrives at the receiving end, it often has serious attenuation or distortion. This change is mainly caused by signal fading. Spatial diversity technology and MIMO technology can effectively overcome the influence of fading by transmitting multi-channel signals on different spatial paths. It improves the reliability of information transmission and system capacity, but spatial diversity requires the installation of multiple antennas at a certain distance at the receiving or sending end. In order to ensure that the transmitted multichannel signal is irrelevant. However, because the mobile terminal needs to meet the requirements of portability, the size should not be too large. This limits the practicability of spatial diversity. Cooperative relay technology realizes virtual spatial diversity through different users sharing each other's antennas, which improves the reliability of information transmission and system capacity. In this paper, several common diversity merging techniques are discussed, and the effects of maximum ratio combination, equal ratio combination, and the number of diversity links on the BER performance of QPSK modulation signal are simulated. Then, four different relay modes, AFDF-SDF and IR, are analyzed, and the BER performance of each relay mode is simulated and analyzed. Aiming at the problem of low spectrum efficiency of one-way relay system, two main mechanisms of two-stage bidirectional cooperative relay system based on DF are studied. That is, the performance of symbol error rate in equal-power allocation is based on the performance of BER and de-noising and forwarding mechanism. On this basis, the target is to minimize the symbol error rate of the system, and under the premise of a certain total power, the symbol error rate of the system is minimized. An optimal power allocation algorithm is proposed to solve the problem that the equal power allocation scheme can not adapt to the channel state difference between the two sides of the relay node R. The simulation results show that the optimal power allocation algorithm is compared with the equal power allocation algorithm. It can reduce the symbol error probability of the system and improve the throughput performance of the system.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN92
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本文編號：1578990