Performance Analysis of Adaptive Equalization Filter to Mitigate Interference in Heterogeneous Networks

Abstract

Heterogeneous networks become a suitable selection to enhance the coverage and capacity in wireless broadband networks. However the growth in the number of femtocells and mobile stations at the enhanced Node Base station (eNB) edge underscores the need for mitigating interference. In this thesis an adaptive equalization filter with extra antenna is used in order to maintain acceptable level of interference; beside, noise reduction. The extra antenna is pointed at the main source of interference which captures the interference signals and then applied to adaptive equalization filter for the purpose of interference reduction. The complex Least Mean Square algorithm (LMS) is employed for setting coefficients of adaptive equalization filter. The system works by instructs its mobile stations to stop transmit for 3% of the Time Division Duplex (TDD) frame length. At this interval, it measures the channel power at main antenna, channel power in extra antenna and error power. The coefficients of adaptive equalization filter are locked and the system allows its mobile stations to continue transmitting. The TDD adaptive equalization filter has achieved a noticeable interference to noise ratio suppression up to 6.5dB on same cases, with 54% improvement compare with adaptive equalization filter noise canceller used as benchmark at same conditions.