Sommersemester 2006

Channel Estimation for Cooperative Relay-Assisted MIMO Channels

Multiple-input multiple-output (MIMO) communication systems are able to substantially increase the data rate (bit/sec) or to improve the transmission quality (bit error rate) in a wireless link [1]. In previous works [2] we have shown that wireless relay networks can be used: Instead of transmitting the data packets directly to the destination, the packets are sent first to amplify-and-forward relays (could be idle mobiles) which then forward the packets to the destination. Relaying the packets introduces an artificial scattering environment which leads to a high-rank equivalent channel matrix. In the general case this equivalent matrix is not diagonal, which means that the receiver has to separate the signals of each receiver. In [3] cooperation between relays is considered with the purpose of obtaining a diagonal equivalent matrix. This can be achieved by adequate relay gains. Determining the relay gains requires channel state information, and its acquisition [4] is the motivation for this semester project. You will implement, simulate and evaluate channel estimation methods derived from MIMO systems and find out the most appropriate one (jointly in terms of training sequence and cost function) for the considered scheme.

[1] A. Paulraj, R. Nabar and D. Gore, Introduction to Space-Time Wireless Communications. Cambridge University Press, 2003.
[2] A. Wittneben and B. Rankov, Impact of Cooperative Relays on the Capacity of Rank Deficient MIMO Channels Proceedings of the 12th IST Summit on Mobile and Wireless Communications, vol. 2, (Aveiro, Portugal), pp. 421-425, June, 2003.
[3] A. Wittneben, Coherent Multiuser Relaying with Partial Relay Cooperation Proc. IEEE Wireless Communications and Networking Conference (WCNC) , April 3-6, 2006.
[4] I. Barhumi, G. Leus, and M. Moonen, Optimal Training Design for MIMO OFDM Systems, Mobile Wireless Channels IEEE Transactions on Signal Processing, vol. 51, pp. 1615-1624, June 2003.

Subject area MIMO communication systems, channel estimation, relaying
Type of work 50% Theory, 50% Software (Matlab)
Students Daniel Hoesli
Supervisor Dr. Etienne Auger
Professor Prof. Dr. Armin Wittneben