Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Hybrid automatic repeat request (Hybrid ARQ or HARQ) is a combination of forward error-correcting coding and error detection using the ARQ error-control method. In standard ARQ, redundant bits are added to data to be transmitted using an error-detecting code such as cyclic redundan ...Full description
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Hybrid automatic repeat request (Hybrid ARQ or HARQ) is a combination of forward error-correcting coding and error detection using the ARQ error-control method. In standard ARQ, redundant bits are added to data to be transmitted using an error-detecting code such as cyclic redundancy check (CRC). In Hybrid ARQ, forward error correction (FEC) bits are added to the existing Error Detection (ED) bits (such as Reed-Solomon code, Convolutional code or Turbo code) to correct a subset of all errors while relying on ARQ to detect uncorrectable errors. As a result Hybrid ARQ performs better than ordinary ARQ in poor signal conditions, but in its simplest form this comes at the expense of significantly lower throughput in good signal conditions. There is typically a signal quality cross-over point below which simple Hybrid ARQ is better, and above which basic ARQ is better.