發(fā)布時間：2018-01-09 08:36

  本文關(guān)鍵詞：基于非理想CSI的V-BLAST系統(tǒng)功率分配算法研究　出處：《南京航空航天大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： MIMO V-BLAST OFDM 功率分配 信道相關(guān) 估計誤差 反饋延遲 誤比特率

【摘要】：V-BLAST結(jié)構(gòu)是一種基于MIMO方式的傳輸技術(shù),它能較好的利用多天線系統(tǒng)的信道容量及頻譜效率。在V-BLAST結(jié)構(gòu)中應(yīng)用OFDM技術(shù)可有效抵抗多徑衰落并緩解符號間干擾。自適應(yīng)功率分配算法能根據(jù)信道環(huán)境動態(tài)變化實現(xiàn)各發(fā)射天線功率的自適應(yīng)調(diào)整。本文在信道相關(guān)、信道估計有誤差以及信道反饋有延遲條件下,研究了V-BLAST及V-BLAST OFDM系統(tǒng)的自適應(yīng)功率分配算法,以期所提發(fā)射功率分配方案能更好的提升系統(tǒng)性能,并為實用提供依據(jù)。全文主要工作如下:1.針對傳統(tǒng)V-BLAS系統(tǒng),不考慮傳播誤差,采用ZF及MMSE干擾抵消檢測方式時,推導(dǎo)了系統(tǒng)子流誤比特率(BER)的近似表達(dá)式。同時在完全信道狀態(tài)信息(CSI)條件下研究了基于拉格朗日極值法與基于等信干噪比(SINR)的發(fā)射功率分配方案。通過仿真驗證理論推導(dǎo)及功率分配方案的有效性。2.針對信道相關(guān)及存在估計誤差的V-BLAST系統(tǒng),以最小化平均BER為目標(biāo),分別得到基于ZF及MMSE檢測時V-BLAST系統(tǒng)的發(fā)射功率分配方案。考慮到系統(tǒng)BER性能隨著信道相關(guān)性的增加而下降,根據(jù)信道信息引入去相關(guān)方法以達(dá)到改善系統(tǒng)BER的目的。對所提發(fā)射功率分配方案進(jìn)行仿真同時給出詳細(xì)分析。與傳統(tǒng)等功率分配方案相比,采用所提發(fā)射功率分配方案結(jié)合去相關(guān)方法可顯著改善系統(tǒng)性能。3.針對信道估計有誤差及反饋有時延的V-BLAST系統(tǒng),以最小化平均BER為目標(biāo),提出一種基于MMSE檢測的自適應(yīng)功率分配方案。由信號估計信干噪比(SINR)的概率密度函數(shù)(PDF)推導(dǎo)出系統(tǒng)子流瞬時信干噪比的條件PDF以及系統(tǒng)瞬時BER表達(dá)式。以最小化平均BER為目標(biāo)建立代價函數(shù)得到自適應(yīng)功率分配方案。仿真顯示,所提算法能獲得比等功率分配方案更好的性能,在改善系統(tǒng)BER的同時更具實效性。4.針對信道相關(guān)及估計有誤差的V-BLAST OFDM系統(tǒng),以最小化BER為目標(biāo)提出一種自適應(yīng)功率分配方案�？紤]到信道相關(guān)的影響,應(yīng)用去相關(guān)方法。仿真顯示,將發(fā)射功率分配方案及去相關(guān)方法應(yīng)用到V-BLAST OFDM系統(tǒng)中,在克服頻率選擇性信道中的符號間干擾的同時提升了系統(tǒng)性能。
[Abstract]:V-BLAST structure is a transmission technology based on MIMO. It can make good use of the channel capacity and spectrum efficiency of multi-antenna system. The application of OFDM technology in V-BLAST structure can effectively resist multipath fading and mitigate inter-symbol interference. Adaptive power allocation algorithm can. Adaptive adjustment of transmit antenna power is realized according to the dynamic change of channel environment. The adaptive power allocation algorithms for V-BLAST and V-BLAST OFDM systems are studied under the condition of channel estimation error and channel feedback delay. It is expected that the proposed scheme can improve the system performance better, and provide a basis for practical use. The main work of this paper is as follows: 1. For the traditional V-BLAS system, the propagation error is not considered. When using ZF and MMSE interference cancellation detection method. The approximate expression of sub-stream error bit rate (ber) of the system is derived. At the same time, under the condition of complete channel state information (CSI), the Lagrangian extremum method and the equal-signal-to-noise ratio (SINR) are studied. The efficiency of the scheme is verified by simulation. 2. The V-BLAST system is designed for channel correlation and estimation error. The goal is to minimize the average BER. The transmission power allocation scheme of V-BLAST system based on ZF and MMSE detection is obtained, considering that the BER performance of the system decreases with the increase of channel correlation. According to the channel information, the de-correlation method is introduced to improve the BER of the system. The proposed transmission power allocation scheme is simulated and analyzed in detail. Compared with the traditional equal-power allocation scheme. The proposed transmit power allocation scheme combined with de-correlation method can significantly improve the system performance. 3. For V-BLAST systems with channel estimation errors and feedback delays, the objective is to minimize the average BER. An adaptive power allocation scheme based on MMSE detection is proposed. The probability density function (PDF) of signal-to-noise ratio (SINR) is estimated from the signal. The conditional PDF of the system subflow instantaneous signal-to-noise ratio and the instantaneous BER expression of the system are derived. The adaptive power allocation scheme is obtained by establishing the cost function to minimize the average BER. The proposed algorithm can achieve better performance than the equal-power allocation scheme and improve the efficiency of the system BER at the same time. 4. For the channel correlation and estimation error V-BLAST OFDM system. An adaptive power allocation scheme aiming at minimizing BER is proposed. Considering the influence of channel correlation, the de-correlation method is applied. The transmit power allocation scheme and de-correlation method are applied to V-BLAST OFDM system, which can overcome the intersymbol interference in frequency selective channel and improve the system performance.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN919.3
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本文編號：1400740