Modified EDF algorithm and WiMAX architecture to ensure end-to-end delay in multi-hop networks

Multi-hop relay based WiMAX architecture is one of the proposed solutions to connectivity in difficult terrains and an economical solution for developing/under-developed countries. This paper analyzes a hybrid multi-hop architecture consists of mesh and PMP both types of connections. Architecture for relay station (RS) has been proposed to provide such hybrid connectivity. Moreover, to provide end-to-end delay guarantee in such multi-hop networks a novel-scheduling algorithm, modified earliest deadline first (MEDF) has been proposed. MEDF provides fairness along with per hop delay guarantees among flows with different delay requirements. Extensive simulation and analysis of MEDF has been done. Results are compared with earliest deadline first (EDF) scheduling under similar scenario, which shows that MEDF is able to provide better end-to-end delay performance. MEDF also ensures the difference between average end-to-end delay of voice and video packets of video-conferencing session is within prescribed delay limit (i.e. within 30 msec) of quality of perception (QoP).