Abstract:
The asymmetric nature of bit errors in several practical applications provides
grounds for efficient error control techniques. The Z-channel model and
special classes of codes like asymmetric error detection codes and t-asymmetric
error correcting/d-asymmetric error detecting codes can be successfully used in
ARQ protocols for feedback error control enhancement.
This thesis presents some efficient feedback error control techniques, suitable
for the Z-channel. Precisely, some forms of hybrid ARQ protocols specific to
the Z-channel characteristics are introduced. First a diversity combining scheme
is presented and analyzed. The undetected error probability and the expected
number of retransmissions are calculated for this protocol. Then the Bose-Lin
codes are analyzed and feedback error control specific parameters are derived for
them. Finally, a type I hybrid ARQ one-code scheme is proposed and analyzed.
The proposed techniques improve the throughput efficiency of feedback
error control protocols and decrease their accepted packet error rate. The coding
analysis is also of theoretical value, in the sense that it solves some open problems
in this area.
