Space–time code: Difference between revisions

Revision as of 16:13, 23 May 2008

Revision as of 12:12, 11 September 2008

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Space time codes may be split into two main types:

*[[Space–time trellis code]]s (STTCs)<ref name="construction">{{cite journal|author=Vahid Tarokh, Nambi Seshadri, and A. R. Calderbank|title=Space&ndash;time codes for high data rate wireless communication: Performance analysis and code construction|journal=IEEE Transactions on Information Theory|pages=744&ndash;765|volume=44|issue=2|datemonth=March | year=1998|doi=10.1109/18.661517}}</ref> distribute a [[convolutional code|trellis code]] over multiple antennas and multiple time-slots and provide both coding gain and [[diversity reception|diversity gain]].

*[[Space–time block code]]s (STBCs)<ref name="alamouti">{{cite journal|author=S.M. Alamouti|title=A simple transmit diversity technique for wireless communications|journal=IEEE Journal on Selected Areas in Communications|pages=1451&ndash;1458|volume=16|issue=8|datemonth=October | year=1998|doi=10.1109/49.730453}}</ref><ref name="orthog">{{cite journal|author=Vahid Tarokh, Hamid Jafarkhani, and A. R. Calderbank|title=Space&ndash;time block codes from orthogonal designs|journal=[[IEEE Transactions on Information Theory]]|pages=744&ndash;765|volume=45|issue=5|datemonth=July | year=1999|url=http://www.mast.queensu.ca/~math800/W03/papers/TrkhJafarkCldb_IT99.pdf|doi=10.1109/18.771146}}</ref> act on a block of data at once (similarly to [[block code]]s) and provide only diversity gain, but are much less complex in implementation terms than STTCs.

STC may be further subdivided according to whether the receiver knows the [[channel (communications)|channel]] impairments. In coherent STC, the receiver knows the channel impairments through training or some other form of estimation. These codes have been studied more widely because they are less complex than their non-coherent counterparts. In noncoherent STC the receiver does not know the channel impairments but knows the statistics of the channel.<ref name="hm">{{cite journal|author=Marzetta, T.L. and Hochwald, B.M.|title=Capacity of a mobile multiple-antenna communication link in Rayleigh flat fading|journal=IEEE Transactions of Information Theory|datemonth=January | year=1999|volume=45|issue=1|pages=139–157|doi=10.1109/18.746779}}</ref> In [[differential space–time code]]s neither the channel nor the statistics of the channel are available.<ref name="jsac">{{cite journal|author=V. Tarokh and [[Hamid Jafarkhani|H. Jafarkhani]]|title=A Differential Detection Scheme for Transmit Diversity|journal=IEEE Journal on Selected Areas in Communications|datemonth=July | year=2000|volume=18|issue=7|doi=10.1109/49.857917|pages=1169&ndash;1174}}</ref>

== See also ==

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[[Category:Wireless]]

[[categoryCategory: radioRadio resource management]]