Relay channel

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In information theory, a relay channel is a probability model on the communication between a sender and a receiver aided by one or more intermediate relay nodes. It is a combination of the broadcast channel (from sender to relays and receiver) and multiple access channel (from sender and relays to receiver).

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[edit] General discrete-time memoryless relay channel

A discrete memoryless single-relay channel can be modelled as four finite sets, X1,X2,Y1, and Y, and a conditional probability distribution p(y,y1 | x1,x2) on these sets. The probability distribution of the choice of symbols selected by the encoder and the relay encoder is represented by p(x1,x2).

               o------------------o
               |   Relay Encoder  |
               o------------------o
                 A              |
                 | y1        x2 |
                 |              V
o---------o x1 o------------------o y  o---------o
| Encoder |--->|   p(y,y1|x1,x2)  |--->| Decoder |
o---------o    o------------------o    o---------o

[edit] Degraded relay channel

Such a relay channel is said to be degraded if y depends on x1 only through y1 and x2, i.e., p(y | x1,x2,y1) = p(y | x2,y1).

[edit] Reversely degraded relay channel

[edit] Feedback relay channel

[edit] Relay without delay channel

[edit] References

[edit] External links

  • Many resources on the Relay Channel and Cooperative Communications are available at "[1]," - from Ramy Medhat Tannious webpage - UT Dallas.
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