Swansea Metropolitan University
Energy Delay Tradeoff (EDT) is a fundamental tradeoff that can play a crucial role in understanding the energy efficiency of various transmission schemes. For Hybrid Automatic Repeat reQuest (HARQ) protocols, EDT can be well defined. In this paper, in order to understand the EDT for wireless multiuser systems, the authors consider downlink channels where the HARQ with Incremental Redundancy (HARQ-IR) protocol is employed for reliable transmissions to users. For a given total power, the power allocation is studied and its impact on EDT is investigated. It is shown that the Multiuser Diversity (MD)-based power allocation becomes preferable when a long effective delay is allowed.