多径信道下OFDM系统中的两种线性载波间干扰抑制技术
Two linear intercarrier interference cancellation techniques in ofdm systems over multipath channels
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摘要: 载波间干扰(ICI)是影响正交频分复用(OFDM)系统性能的重要因素。该文研究了不同延迟线长度L下的频域RAKE(F-RAKE)和频域均衡(F-FIR)两种线性ICI抑制技术。假设接收端已知信道信息,F-FIR采用最小均方误差(MMSE)准则。结果表明L=3时,F-RAKE比标准接收机的载干比(CIR)高2～5dB,而F-FIR则高出2～7dB;随着L的增加,两种接收机所能获得的CIR增益逐渐降低。从计算复杂度来看,F-FIR的计算量是F-PAKE的L倍,工程中可以通过选取不同延迟线长度和接收机结构来达到计算复杂度和性能的折衷。Abstract: InterCarrier Interference (ICI) is an important, factor degrading the performance of Orthogonal Frequency Division Multiplexing (OFDM) systems. Two linear ICI cancellation techniques, Frequency RAKE (F-RAKE) and frequency equalization (F-FIR), with different length of delay-line, L, are studied in this paper. Assuming that the channel information is known in the receiver and MMSE criterion is adopted for F-FIR, results show that F-RAKE has about 2~5dB Carrier-Interference-Ratio (CIR) achievement than standard receiver in case of L=3. Meanwhile, F-FIR has about 2~7 dB CIR achievement. And the CIR performance gains of the two schemes decrease with increment of L. Also, the computational complexity of F-FIR is L times than that of F-RAKE. Thus, the tradeoff between complexity and performance in the engineering can be reached by selecting the length of delay-line and receiver scheme.
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