Wireless communication: a power efficiency perspective

Summary form only given. The limited battery resource at a mobile terminal coupled with the hostile multipath fading channel makes the problem of providing reliable high data rate services challenging. In this paper we develop a new framework for the design of power efficient transmission mechanisms that support multimedia traffic having different delay constraints. First, we present optimal design techniques that substantially reduce the transmission power for small increases in average communication delays for a single user scenario thereby providing another avenue for mobile devices to save on battery power. We also construct a variable rate modulation scheme to show the benefits of the proposed formulation in a practical system. Power optimal schedulers with absolute packet delay constraints are also studied. Next, we design power efficient schedulers that satisfy average delay bounds for multiple users in a broadcast channel. Optimal schedulers that jointly allocate rate and power to the different users based on the different buffer and channel conditions are presented in a code-division multiple access (CDMA) system. We show that joint scheduling gains over non-cooperative single user schedulers are largest when the users belong to different delay classes. The power minimizing schedulers are derived using well known results from dynamic programming. We also introduce a class of suboptimal schedulers.