Space–time trellis code
Encyclopedia
Space–time trellis codes (STTCs) are a type of space–time code
used in multiple-antenna wireless communications
. This scheme transmits multiple, redundant
copies of a trellis (or convolutional) code
distributed over time and a number of antennas
('space'). These multiple, 'diverse' copies of the data are used by the receiver to attempt to reconstruct the actual transmitted data. For an 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
s (STBCs), they are able to provide both coding gain and diversity gain and have a better bit-error rate performance. However, being based on trellis codes
, they are more complex than STBCs to encode and decode; they rely on a Viterbi decoder
at the receiver where STBCs need only linear
processing.
STTCs were discovered by Vahid Tarokh
et al. in 1998.
Space–time code
A space–time code is a method employed to improve the reliability of data transmission in wireless communication systems using multiple transmit antennas...
used in multiple-antenna wireless communications
Wireless
Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications...
. This scheme transmits multiple, redundant
Redundancy (information theory)
Redundancy in information theory is the number of bits used to transmit a message minus the number of bits of actual information in the message. Informally, it is the amount of wasted "space" used to transmit certain data...
copies of a trellis (or convolutional) code
Convolutional code
In telecommunication, a convolutional code is a type of error-correcting code in which* each m-bit information symbol to be encoded is transformed into an n-bit symbol, where m/n is the code rate and...
distributed over time and a number of antennas
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
('space'). These multiple, 'diverse' copies of the data are used by the receiver to attempt to reconstruct the actual transmitted data. For an 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 code
Space–time block coding is a technique used in wireless communications to transmit multiple copies of a data stream across a number of antennas and to exploit the various received versions of the data to improve the reliability of data-transfer...
s (STBCs), they are able to provide both coding gain and diversity gain and have a better bit-error rate performance. However, being based on trellis codes
Convolutional code
In telecommunication, a convolutional code is a type of error-correcting code in which* each m-bit information symbol to be encoded is transformed into an n-bit symbol, where m/n is the code rate and...
, they are more complex than STBCs to encode and decode; they rely on a Viterbi decoder
Viterbi algorithm
The Viterbi algorithm is a dynamic programming algorithm for finding the most likely sequence of hidden states – called the Viterbi path – that results in a sequence of observed events, especially in the context of Markov information sources, and more generally, hidden Markov models...
at the receiver where STBCs need only linear
Linear
In mathematics, a linear map or function f is a function which satisfies the following two properties:* Additivity : f = f + f...
processing.
STTCs were discovered by Vahid Tarokh
Vahid Tarokh
Vahid Tarokh is an electrical engineer with contributions to telecommunication, specifically to signal processing for wireless communications.-Life:...
et al. in 1998.