Space–time block code: Difference between revisions

Revision as of 00:48, 29 June 2005

Revision as of 06:20, 11 July 2005

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==Introduction==

Until [[1995]], most work on [[wireless|wireless communications]] focused on having an [[antenna array]] at only one end of the wireless link &mdash; usually at the receiver. In 1995, [[Emre Telatar]] published a seminal paper^{[[#References|1]]} which, in 1998, inspired [[Gerard Foschini]] to demonstrate^{[[#References|2]]} the substantial [[channel capacity]] improvements available by correctly using antenna arrays at ''both'' ends of the link. Shortly afterwards, [[Siavash Alamouti]] ^{[[#References|3]]} and [[ Vahid Tarokh]] et., al[[Hamid Jafarkhani]] and demonstrated<sup>[[#References|3Rob Calderbank]], ^{[[#References|4]]} demonstrated how to use these [[multiple-input multiple-output]] systems to achieve significant [[bit error rate|error rate]] improvement &mdash; the scheme they invented is called '''space&ndash;time coding'''. In fact, Tarokh et. al invented two types of space&ndash;time code: [[space-time trellis code|space&ndash;time trellis code]]s (STTCs) and space&ndash;time block codes (STBCs); the latter are the topic of this article.

STC relies on the transmission of multiple redundant copies of data in the hope that some of them may arrive at the receiver in a state that means they can be usefully relied upon for correct decoding. In the case of STBC, the data-stream to be transmitted is encoded in 'blocks', as in ([[block code|block coding]]) which are distributed across space (meaning antennas) and time &mdash; hence the name. Note that while it is necessary to have multiple transmit antennas, it is not necessary to have multiple receive antennas although to do so improves performance. This process of receiving diverse copies of the data is known as [[diversity reception]] and is what was largely studied until Foschini's 1998 paper.