基于導(dǎo)頻的發(fā)射分集OFDM系統(tǒng)的子空間跟蹤信道估計(jì)
Subspace-Tracking Channel Estimation for Pilot-Symbol-Aided OFDM Systems with Transmitter Diversity
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摘要: 由于發(fā)射分集技術(shù)可以大大提高系統(tǒng)的抗衰落性能，因此得到了廣泛的研究和應(yīng)用。該文提出了3種基于導(dǎo)頻的發(fā)射分集正交頻分復(fù)用(OFDM)系統(tǒng)的子空間幅度跟蹤信道估計(jì)方法，并分析比較了其估計(jì)性能。利用信道傳播時(shí)延慢變和衰落幅度快變的特點(diǎn)，通過(guò)對(duì)多徑信道的時(shí)延子空間和衰落幅度的跟蹤，可以部分消除信道估計(jì)過(guò)程中噪聲的影響，大大提高信道估計(jì)精度。在信道階數(shù)已知或使用相同秩估計(jì)方法的情況下，第3種方法的運(yùn)算復(fù)雜度最低, 性能最好；第1種方法次之，性能最差；第2種方法由于需要進(jìn)行DFT和IDFT，運(yùn)算復(fù)雜度最高。仿真結(jié)果表明，3種子空間幅度跟蹤信道估計(jì)方法在410-3 誤碼率時(shí)可以提高系統(tǒng)誤碼率性能1～2 dB左右。
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關(guān)鍵詞:
- 正交頻分復(fù)用;發(fā)射分集;信道估計(jì);子空間跟蹤
Abstract: Transmitter diversity has been studied extensively as a technique for combating channel fading in mobile wireless communications, especially when receiver diversity is expensive or impractical. In this paper, three subspace-tracking channel estimation algorithms for OFDM systems with transmitter diversity are proposed, and their performances are compared. Because the fading channel has slow-varying delays and fast-varying amplitudes, the noise effect in the channel estimation can be partially eliminated by tracking delay subspace and amplitudes of the channel. In three approaches, the last one has the lowest computation complexity and the best performance, the first one has a little high complexity and the worst performance, and the second one has the highest complexity for its DFT and IDFT operations. Simulation results show that one to two decibels benefits can be obtained by subspace and amplitudes tracking. -
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