Space–time trellis code: Difference between revisions

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'''Space–time trellis codes (STTCs)''' are a type of [[space-time code]] used in [[multiple-input multiple-output|multiple-antenna]] [[wireless|wireless communications]]. This scheme transmits multiple, [[redundancy (information theory)|redundant]] copies of a [[convolutional code|trellis (or convolutional) code]] distributed over time and a number of [[antenna (radio)|antennas]] ('space'). These multiple, 'diverse' copies of the data are used by the receiver to attempt to reconstruct the actual transmitted data. For a STC to be used, there must necessarily be multiple ''transmit'' antennas, but only a single ''receive'' antennas is required; nevertheless multiple receive antennas are often used since the performance of the system is improved by so doing.

In contrast to [[space-time block code|space–time block codes]] (STBCs), they are able to provide both coding gain and diversity gain and have a better [[bit error rate|bit-error rate]] performance. However, being based on [[convolutional code|trellis codes]], they are more complex than STBCs to encode and decode; they rely on a [[Viterbi algorithm|Viterbi decoder]] at the receiver where STBCs need only [[linear]] processing.

== History ==

STTCs were discovered by [[Vahid Tarokh]] et. al in [[1998]]^{[[#References|1]],[[#References|2]]}.

== How it works ==

These multiple, 'diverse' copies of the data are used by the receiver to attempt to reconstruct the actual transmitted data. For a STC to be used, there must necessarily be multiple ''transmit'' antennas, but only a single ''receive'' antennas is required; nevertheless multiple receive antennas are often used since the performance of the system is improved by so doing.

== Comparasons with Space-Time Block Codes ==

In contrast to [[space-time block code|space–time block codes]] (STBCs), they are able to provide both coding gain and diversity gain and have a better [[bit error rate|bit-error rate]] performance.

* However, current STBCs are based on [[trellis codes]]. This makes these codes more complex than STBCs to encode and decode; they rely on a [[Viterbi algorithm|Viterbi decoder]] at the receiver where STBCs need only [[linear]] processing.

==References==

#'''Vahid Tarokh, Nambi Seshadri, and A. R. Calderbank''', [http://www.stanford.edu/~leipoo/ee359/Tarokh9.pdf "Space–time codes for high data rate wireless communication: Performance analysis and code construction"], ''[[Institute of Electrical and Electronics Engineers|IEEE]] [[IEEE Transactions on Information Theory|Trans. Inform. Theory]]'', vol. 44, pp. 744–765, Mar. 1998.

#'''Vahid Tarokh, Ayman Naguib, Nambi Seshadri and A. Robert Calderbank''', "Space–time codes for high data rate wireless communication: performance criteria in the presence of channel estimation errors, mobility, and multiple paths", ''IEEE Trans. Commun.'', vol. 47, no. 2, pp. 199–206, Feb. 1999.

[[Category:Wireless communications]]