无线网络中自适应阵列处理算法的性能比较

信道间干扰是无线局域网在标准制定和实用中较重要的问题,如使用OFDM技术的高速率无线局域网标准802.11a,工作在国家信息基础设施频段5GHz(许多国家无需频段许可),因此,可能出现多个用户使用相同子载波连接接入点。该类系统中,选用最大似然法进行参数估计是最优的,但计算复杂度大;选用次优但低复杂度的期望极大法作参数估计更具实用价值。在多用户使用同一载波接入时,实际仿真证实了期望极大算法可有效地抵抗信道间干扰。

Cancellation of Co-channel Interference in OFDM System Based on Expectation Maximization

Co-channel Interference(CCI) is an important issue in the design and deployment of WLANs because 802.11a uses Orthogonal Frequency Division Multiplexing(OFDM) and the spectrum allocated in the 5 GHz band is unlicensed.Therefore two or more adjacent users,connecting to different access points,could be using the same subcarriers.Though the estimation of unknown parameters using the maximum-likelihood(ML) is optimal,it is highly complex and could be analytically intractable.The expectation-maximization(EM) algorithm is a sub-optimal technique estimates the parameters in an iterative manner.This work investigates the application of EM to estimate desired user's signal in an OFDM system with CCI.