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
