Space time codes and MIMO transmission

Alister Burr*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter


This chapter focuses on the techniques available for achieving in practice the significant capacity increases that are in principle available on the MIMO wireless channel. It reviews the main performance benefits of MIMO, namely multiplexing gain and diversity gain, which provide, respectively, increased throughput and increased robustness, and shows how these are in fact properties of the underlying channel, but require care in the design of transmission schemes if they are to be realized in MIMO systems. It shows the extent to which they can be traded-off against one another, though noting that the idealized diversity-multiplexing trade-off may not be available under more realistic conditions. The theory of space-time coding provides a useful basis for understanding how the diversity and multiplexing benefits can be achieved. It leads to criteria for the transmitted signal, especially for achieving maximum diversity gain. The most important criterion is that the rank of the transmitted signal matrix should be maximized. This has allowed us to consider the design of MIMO schemes for achieving maximum diversity, leading to what are commonly called space-time codes, and maximum multiplexing gain, leading to spatial multiplexing. However, the theory of space-time codes can, in fact, also be applied to spatial multiplexing in order to optimize diversity here also. This chapter also describes a third transmission technique, precoding, which is widely used in current and developing wireless standards, and shows that the other transmission schemes can in fact conveniently be described in terms of precoding. In conclusion, it reviews the application of MIMO techniques in these emerging standards, especially 3GPP LTE/LTE-Advanced, and WiMAX (IEEE 802.16). In both, the formalism of precoding is widely used, especially for closedloop MIMO systems, where channel state information is exploited at the transmitter to adapt the transmitted signal to the MIMO channel.

Original languageEnglish
Title of host publicationMIMO
PublisherElsevier Inc.
Number of pages41
ISBN (Print)9780123821942
Publication statusPublished - 2011

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