摘要
分析了时变瑞利信道中存在载波频率偏移的正交频分复用(OFDM)系统的性能.首先计算和分析了接收信号不同分量的功率(期望信号、载波间干扰、噪声),然后给出了16-QAM正交频分复用系统的误比特率.理论分析与仿真结果表明:(1)频偏和信道变化极大地降低了OFDM系统的性能;(2)由频偏或信道变化造成的载波间干扰主要集中在循环相邻的几个子载波边界,这一结论对于开发低复杂度载波间干扰消除算法非常有用;(3)频偏对正交频分复用系统性能的影响可等效为信道变化的影响,提出了一个包含载波频偏的时变信道模型.
In this paper, the performance of orthogonal frequency division multiplexing （OFDM） systems with residual carrier frequency offset over time-varying Rayleigh channels is investigated. Due to the presence of noise and implementation loss of synchronization algorithms, residual frequency offset exist in the OFDM receivers, which degraded the performance of OFDM systems. Channels＇ variations also destroy the orthogonality between subcarriers, resulting in intercarrier interference （ICI）, which increases an irreducible error floor in proportion to the normalized Doppler frequency. Therefore, a systematic performance analysis of OFDM systems in these circumstances is required. In this paper, the power of different received signal components （the desired signal, the ICI signals caused by frequency offset and channel variation, and noise signals） are firstly calculated and analyzed, and the SINR （Signal to Interference plus Noise ratio） and BER （Bit Error Rates） calculations for 16-QAM OFDM systems are then investigated. Analytical analysis and computer simulations show the following important results ： （1） residual frequency offset and channels＇ time variations greatly degraded the performance of OFDM systems （2）the intercarrier interference （ICI） energy caused by channel variations and frequency offset is concentrated in cyclically adjacent intercarriers; （3） the influence of residual carrier frequency offset on OFDM system performance can be modeled as the effects of equivalent channels＇ time variations ,and then a time-varying channel model including the residual carrier frequency offset effect is proposed.
出处
《中南民族大学学报（自然科学版）》
CAS
2008年第2期63-67,共5页
Journal of South-Central University for Nationalities：Natural Science Edition
基金
国家自然科学基金资助项目(60772031)
关键词
正交频分复用
载波频率偏移
时变信道
载波间干扰
OFDM
carrier frequency offset
time-varying channel
intercarrier interference
