Publication Date


Degree Type

Master's Project

Degree Name

Master of Science (MS)


Computer Science


HARQ (Hybrid Automatic Repeat Request) combines ARQ (Automatic Repeat Request) with FEC (Forward Error Correction) to provide a reliable way to ensure that data are received correctly and in sequence. A multiple-copy HARQ scheme is proposed for WiMAX (Worldwide Interoperability for Microwave Access) to reduce the waiting time of erroneously received data in the receivers’ buffer. In this project, the performances of WiMAX multi-channel stop-and-wait HARQ scheme are compared with that of the proposed multiple-copy HARQ scheme. The multiple-copy HARQ can send the same copy of a data burst on contiguous channels during noisy channel conditions so that the required time for an unsuccessfully received data burst to recover is shortened. It is beneficial for time sensitive data to have a shorter waiting time in a SS’s (Subscriber Station) buffer. The simulation results show that the multiple-copy HARQ scheme requires only 56% of the time that the original WiMAX HARQ needs to successfully deliver erroneous data bursts in the SS’s buffer. The throughput of the multiple-copy HARQ scheme can still reach more than 73% of the original WiMAX HARQ scheme’s throughput.