Interference robust transmission for the downlink of an OFDM-based mobile communications system

Abstract

Radio networks for future mobile communications systems, for example, 3GPP Long-Term Evolution (LTE), arelikely to use an orthogonal frequency division multiplexing- (OFDM-) based air interface in the downlink witha frequency reuse factor of one to avoid frequency planning. Therefore, system capacity is limited by interference,which is particularly crucial for mobile terminals with a single receive antenna. Nevertheless, next generationmobile communications systems aim at increasing downlink throughput. In this paper, a single antenna interferencecancellation (SAIC) algorithm is introduced for amplitude-shift keying (ASK) modulation schemes in combinationwith bit-interleaved coded OFDM. By using such a transmission strategy, high gains in comparison to a conventionalOFDM transmission with quadrature amplitude modulation (QAM) can be achieved. The superior performance ofthe novel scheme is confirmed by an analytical bit-error probability (BEP) analysis of the SAIC receiver for a singleinterferer, Rayleigh fading, and uncoded transmission. For the practically more relevant multiple interferer case wepresent an adaptive least-mean-square (LMS) and an adaptive recursive least-squares (RLS) SAIC algorithm. We show that in particular the RLS approach enables a good tradeoff between performance and complexity and is robust even to multiple interferers.