MIMO Transmission over High Delay Spread Channels with Reduced Cyclic Prefix Length

Abstract:
In 3GPP LTE communication systems, the physical layer is based on Orthogonal Frequency-Division Multiple Access and Single Carrier Frequency-Division Multiple Access in the downlink and uplink, respectively. For both schemes two different cyclic prefix (CP) lengths are standardized, a normal CP length and an extended version, the latter being intended for high delay spread channels. We retain the simple one tap equalizer and show that appropriate adaptation of the modulation and coding scheme, rather than extending the CP, yields better throughputs in a typical SNR regime of operation. The proposed adaptation takes the effects of the intersymbol (ISI) and intercarrier (ICI) interference into account, where the ISI/ICI is modelled as coloured noise, which degrades the SNR, and therefore directly affects the feedback parameters.