Frequency domain feed-forward filter combined DFE structure in single carrier systems over time-varying channels

Most of the researches about frequency domain equalization assume that the single carrier wireless communication system works over static channels. However, with more and more requests for mobile wireless reception, we have to consider the case of time-varying channels. In this paper, we propose a frequency domain feed-forward filter combined decision feedback equalizer over time-varying channels (FD-DFE-TV) for single carrier systems. Moreover, some complexity reducing techniques are provided to lower the additional computational burden brought by the disposal in time-varying channels. Simulations show that the proposed method can effectively lower the system error floor thus has superior performance than existing FD-DFE structure in time-varying environment, especially in high speed mobile reception.

I. Introduction

Wireless broadband communication systems face the effects of very dispersive channels which may lead to severe intersymbol interference (ISI). To deal with this phenomenon, there are two modulation techniques adopted in modern wireless communication systems: single carrier (SC) modulation with equalization and orthogonal frequency division multiplexing (OFDM). The examples of SC systems include the Advanced Television Systems Committee (ATSC) [1] and the Chinese Digital Television Terrestrial Broadcasting (DTTB) [2] [3] with carrier number equals one mode. On the other hand, OFDM has been adopted in digital video broadcasting terrestrial (DVB-T) [4], and IEEE 802.11a/g wireless local area network (LAN) [5], etc. Sometimes, both of the above two techniques are recommended for a wireless communication system, such as the 802.16a WLAN.