Relationship Between Throughput and Bit Error Rate for Enhanced Type-II Chase Combining HARQ Mechanism

This MATLAB simulation investigates the relationship between throughput and bit error rate in an enhanced Type-II Chase Combining HARQ mechanism. The implementation employs simplified encoding and decoding processes where error patterns in transmitted codewords are simulated probabilistically based on the specified bit error rate. At the receiver side, the system evaluates whether the number of erroneous bits falls within the correctable error range. For each transmitted codeword, the receiver performs error detection using the bit error count information - error-free codewords are accepted immediately, while corrupted codewords trigger retransmission requests. The algorithm implements an alternating transmission scheme controlled by an "alternate" parameter value, which toggles between sending information codewords and parity codewords. When parity codewords are received, the system forms combined codewords by merging the original and parity data. If the resulting codeword combination demonstrates error correction capability, the transmission is considered successful; otherwise, a retransmission request is generated. This approach provides an efficient method for evaluating HARQ performance under various channel conditions while maintaining computational simplicity through probabilistic error simulation rather than full channel coding implementation.