Experimental Assessment of Power-Save Behavior of Commercial IEEE 802.16 Network

Abstract

The mobility and portability of next-generation cellular devices must address limited accessibility to power; hence, power-saving techniques of mobile terminals are crucial. In this paper, we provide a comprehensive measurement study of power-save mechanisms implemented in current IEEE 802.16 (WiMAX) deployed networks. Particularly, we examine the power consumption of the various transmission and reception modes and compare them with the power consumption during Idle and Sleep modes. We show, both experimentally and analytically, that although theoretically, power consumption can be dramatically reduced by employing an efficient algorithm that alternates between power-save and active modes, lack of cross-layer coordination prevents efficient power-save implementation. We suggest and implement a simple proactive buffering solution that delays the sporadic traffic generated by the upper layers such as keep-alive messages, when the device is in Idle mode and show that such an enhancement can dramatically reduce the device's power consumption. In this paper, we discuss a strategy, termed Intra Frame Power-Save (IFPS), which, although not standardized by 802.16, is implemented by some leading vendors. IFPS does not require any cross-layer coordination, yet can dramatically reduce power consumption even while the device is in operational mode. We suggest ways for further reducing power consumption while performing the schedule by the base station utilizing the IFPS mechanism.