Beyond 3G mobile networks will be data service centric. User equipment (UE) stays in the Connected State relatively long while supporting data services, so efficient power-saving mechanisms for the Connected State are becoming more significant in order to prolong battery life of a handset. Discontinuous reception (DRX) has been a dominant approach for power saving in the Idle State and Connected State. In this study, a novel counter-driven adaptive DRX (CDA-DRX) scheme is proposed and analysed. The CDA-DRX scheme is intended to present a generic and easy-to-implement algorithm to adaptively and autonomously adjust DRX cycle to keep up with changing user activity level. The scheme distinguishes itself from all other researches by minimising signalling overhead and easily balancing packet delivery latency and power consumption. Numerical analysis and system simulation showed that this scheme produces a better tuned DRX operation than the ones proposed in literature or suggested in the standards.

Adaptive and autonomous power-saving scheme for beyond 3G user equipment

A generalized and autonomous discontinuous reception (DRX) scheme, which is applicable to both Third-Generation Partnership Project (3GPP) and IEEE 802.16e standards, is analyzed by two-level Markov chain modeling, along with the European Telecommunications Standards Institute (ETSI) packet traffic model. Numerical analysis showed that this scheme is capable of autonomously adjusting the DRX cycle to keep up with changing user equipment activity level with no signaling overhead increase, thus producing a better tuned DRX operation. Quantitative comparison with the power-saving schemes of 3GPP and 802.16e standards demonstrated that the autonomous DRX scheme is advantageous over these power-saving schemes.

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Performance Analysis of a Generalized and Autonomous DRX Scheme

Data services, especially multimedia services drain battery quickly. Hence, it becomes more and more important to reduce power consumption in order to prolong active time of a mobile station. Three types of sleep mode schemes were defined in 802.16e for power saving. Sleep window size is either fixed or exponentially increased in these schemes. Past researches showed that power saving performance can be improved by carefully adjusting the sleep window size. Past researches also tried to balance the power saving performance and packet delivery latency, which contradict with each other. In this paper, a novel counter-driven adaptive sleep mode scheme is proposed and analyzed. It intends to present a generic and easy-to-implement adaptive sleep window scheme that keeps up with the change of user activity level. This autonomous and adaptive power saving scheme distinguishes itself from all other researches surveyed so far in the literature by minimizing signaling overhead and easily balancing between packet delivery latency and power saving performance according to QoS requirement of established data services.

A Counter-Driven Adaptive Sleep Mode Scheme for 802.16e Networks

In order to reduce the power consumption of a mobile station, IEEE802.16e introduced the sleep mode to extend the standby time of battery-powered mobile stations. However, existing mainstream simulation platforms do not yet support the sleep mode. Since simulation tools play increasingly important role in the design, research of network protocols, products and applications, it is of high importance to also have sleep mode support in the popular simulation platforms. This paper describes the design and implementation of a simulation module for sleep mode of IEEE 802.16e mobile WiMAX based on OPNET WiMAX module. Simulations on downlink web business of sleep mode under wireless communications scenario are performed. Simulation results show that the sleep mode can greatly reduce energy consumption of a mobile station while maintaining its quality of service.

http://www.aicit.org/IJACT/ppl/052_VOL3.NUM11.pdf

Modeling and Simulation of Power Saving Mechanism for IEEE 802.16e Mobile WiMAX

To extend battery life, modern wireless systems implement Power Saving Mechanisms (PSMs). This work presents a performance evaluation of HTTP Web Browsing and Always-On traffic whithin joint IEEE 802.16e Sleep Mode and Idle Mode operation, on an accurate 802.16e PSM NS-2 simulation implementation. We first determine the most influencial PSM parameters in terms of power savings and performance degradation, for then determining optimal transition points between Sleep Mode and Idle Mode. Results show that although power savings can be achieved, performance degradation can be substantial for a wide range of PSM parameters, if (a) Sleep Mode Inactivity Timer are such that PSM is activated within TCP RTT, or (b) timers for PSM modes are such that there is a ``competition'' between which PSM mechanism should be activated. Also, under established conditions, we observe a significant power saving gains followed by a surprising system performance enhancement.

Performance of Power Saving Modes in IEEE 802.16e System

In order to reduce the power consumption to extend the lifetime of battery-powered Mobile Stations (MSs), IEEE 802.16e has introduced a sleep mode to decrease the usage of air interface resources of serving Base Stations (BSs). In the sleep mode, MS enters into a sleep cycle after negotiating with serving BS and stops its traffic service temporarily. In order to reduce the energy consumption as well as decrease the packet delay especially in low traffic scenario, this paper proposes a novel power saving algorithm for sleep mode in which the sleep interval is increased in power function each time until a maximum sleep interval threshold is reached. Theoretical analysis and simulation experiments demonstrate that the proposed algorithm can achieve significantly less mean energy consumption and mean response time compared with exponential and linear increase algorithms. Furthermore, this paper analyzes the performance impact of each parameter in the algorithm and presents how to configure the sleep mode parameters.

Yue-Juan Kuang

Papers

An efficient power saving mechanism for sleep mode in IEEE 802.16e networks