WPR.2 - Feedback and Resolution of the Channel State

Objectives

This workpackage aims to explore the role of feedback in wireless communication networks and its relation to the resolution of the time-varying channel state. A key feature of most modern radio systems is the fact that they allow for two-way communication. This allows for a sharing of the medium in both directions for both communication and low-layer signalling of channel quality indicators and decoding capacity indicators. The main issues considered in this study is the effect of imperfect channel knowledge at the receiving end due to the time-varying nature of the wireless channel and methods to encode it for the return channel as a function of the allocated bandwidth for feedback. Proper exploitation of incomplete feedback for both point-to-point two-way channels and multiuser/broadcast channels are considered. Broadband systems exploiting multiple-antennas at both the transmission and receiving ends are assumed.

Description of work

TR2.1: Imperfect Channel Estimation (Responsible D. Slock - CNRS)

This task treats feedback-less transceiver design and effects of imperfect CSI in receivers. This could be used as performance benchmarks for systems exploiting feedback as well as for systems which do not have feedback channels.

TR2.2: Point-to-point and Point-to-Multipoint Two-Way Channels (Responsible R. Knopp - CNRS)

This sub-task aims to find bounds on information rates in single and multiuser two-way channels with or without perfect CSI at the receivers. Coding/quantization techniques for feedback information will play a key role here. The role of feedback in reducing complexity of transceivers will also be addressed.

TR2.3: Precoding for MIMO and MIMO Broadcast Channels (Responsible S. Shamai - Technion)

This task strives for an understanding of the impact of non-ideal CSI in precoding techniques for downlink transmission. The role of channel mismatch both at the transmitting and receiving ends will be considered.