AG Kommunikationstheorie

Thema:

Robust Signal Processing for Cooperative Multi-Cell Transmission

Abstract:

Inter-cell interference is one of the main limiting factors in todays cellular communication systems. To overcome this limitation, multi-antennas concepts can be applied for shaping interference beneficially and transmitting multiple data streams in parallel using the same radio resource. For cooperative multi-cell transmission, collaborating base stations build a virtual antenna array and transmit precoded data to multiple users. However, precoding requires channel state information (CSI) at the base station site, which is made available via feedback in frequency division duplex systems. While theory provides significant gains for cooperative multi-cell transmission, the performance of practical systems suffers from impaired CSI due to, e.g., noisy pilot reception, quantization, and delays in feedback transmission and backhaul exchange. Although, backhaul latency can be reduced by replacing the infrastructure, large investments are required. In this talk an alternative approach is presented, which bears infrastructural imperfections by reducing the impact of impaired channel knowledge with robust signal processing. In this regard, first the quality of CSI is increased and second, advanced precoding techniques which exploit statistical side information of the channel uncertainty are introduced. A major aspect of this talk pertains to techniques and requirements for distributed precoding, which has the potential to provide significant gains compared to centralized precoding.

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