11,813 research outputs found
Random Linear Network Coding For Time Division Duplexing: When To Stop Talking And Start Listening
A new random linear network coding scheme for reliable communications for
time division duplexing channels is proposed. The setup assumes a packet
erasure channel and that nodes cannot transmit and receive information
simultaneously. The sender transmits coded data packets back-to-back before
stopping to wait for the receiver to acknowledge (ACK) the number of degrees of
freedom, if any, that are required to decode correctly the information. We
provide an analysis of this problem to show that there is an optimal number of
coded data packets, in terms of mean completion time, to be sent before
stopping to listen. This number depends on the latency, probabilities of packet
erasure and ACK erasure, and the number of degrees of freedom that the receiver
requires to decode the data. This scheme is optimal in terms of the mean time
to complete the transmission of a fixed number of data packets. We show that
its performance is very close to that of a full duplex system, while
transmitting a different number of coded packets can cause large degradation in
performance, especially if latency is high. Also, we study the throughput
performance of our scheme and compare it to existing half-duplex Go-back-N and
Selective Repeat ARQ schemes. Numerical results, obtained for different
latencies, show that our scheme has similar performance to the Selective Repeat
in most cases and considerable performance gain when latency and packet error
probability is high.Comment: 9 pages, 9 figures, Submitted to INFOCOM'0
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