Multiuser MIMO Transmission with Limited Feedback, Cooperation, and Coordination

Markus Rupp, Ana Pérez-Neira, Robert W Heath, Nihar Jindal, Christoph Mecklenbräuker
2009 EURASIP Journal on Advances in Signal Processing  
Wireless communication systems are already exploiting powerful multiple antenna technologies based on the principles of multiple input multiple output (MIMO) communication. By now, the principles of single user MIMO communication links are well understood. The next generation of systems, though, will use more advanced MIMO communication strategies that support multiuser MIMO. In this way, the spatial degrees of freedom can be better exploited by properly scheduling multiple users. However,
more » ... ple user communication with MIMO is more challenging than single user MIMO because channel state information at the transmitter is crucial to enhance the system capacity and also due to the additional degrees of freedom entailed by suppressing, cancelling, or avoiding interference. For example, limited feedback algorithms that are used to quantize channel state information at the receiver and send this information back to the transmitter(s) or relay(s) become more complex, since they need much higher resolution to achieve similar performance as their single-user counterparts. Consequently, advances in limited feedback communication are still required to make multiuser MIMO viable in next-generation systems. Although using multiuser MIMO within individual cells has considerable potential, even larger performance gains can be achieved by using multiuser MIMO across cooperative base stations. In the ideal case with perfect cooperation across all cells, the set of all base station antennas can be thought of as a single, distributed antenna array. Significant gains can also be achieved by some level of local coordination, for example, neighboring base stations might jointly choose beamforming directions in order to achieve interference alignment. In this general setting, there are fundamental challenges associated with transceiver design, limited channel information, and cooperative mechanisms. For this special issue we received 23 submissions of which we accepted nine. All papers were peer reviewed by multiple reviewers. We summarize the papers accepted for the special issue as follows. The article entitled "Space-frequency block code with matched rotation for MIMO-OFDM system with limited feedback" by M. Zhang et al. presents a novel matched rotation precoding (MRP) scheme to design a rate one spacefrequency block code (SFBC) and a multirate SFBC for MIMO-OFDM systems with limited feedback. The proposed rate one MRP and multirate MRP can always achieve full transmit diversity and optimal system performance for arbitrary number of antennas, subcarrier intervals, and subcarrier groupings, with limited channel knowledge required by the transmit antennas. Simulations show that the proposed SFBC with MRP can overcome the diversity loss for specific propagation scenarios, always improve the system performance, and thus demonstrate flexibility and feasibility making it suitable for a practical MIMO-OFDM system with dynamic parameters. The article entitled "On the asymptotic optimality of opportunistic norm-based user selection with hard SINR
doi:10.1155/2009/480179 fatcat:dsipvqioojcmbkiv3twemtfll4