Space–time code: Difference between revisions

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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|monthdate=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|monthdate=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=1456&ndash;1467|volume=45|issue=5|monthdate=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 also provide [[diversity reception|diversity gain]] but doesn't provide coding gain.

STC may be further subdivided according to whether the receiver knows the [[channel (communications)|channel]] impairments. In [[coherent space-time code|coherent STC]], the receiver knows the channel impairments through training or some other form of estimation. These codes have been studied more widely, and [[division algebras]]<ref name="divalg">{{cite journal|author=B.A. Sethuraman, B. Sundar Rajan, and V. Shashidhar|title=Full-diversity, high-rate space-time block codes from division algebras|journal=IEEE Transactions on Information Theory|pages=2596&ndash;2616|volume=49|issue=10|monthdate=October | year=2003}}</ref> over number fields have now become the standard tool for constructing such codes.

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|monthdate=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|monthdate=July | year=2000|volume=18|issue=7|doi=10.1109/49.857917|pages=1169&ndash;1174}}</ref>

== See also ==