IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 8, NO. 11, NOVEMBER 2009
A Comprehensive Analysis of Low-Power Operation for Beacon-Enabled IEEE 802.15.4 Wireless Networks Yu-Kai Huang, Student Member, IEEE, Ai-Chun Pang, Senior Member, IEEE, and Hui-Nien Hung
Abstract—ZigBee, a unique communication standard designed for low-rate wireless personal area networks, has extremely low complexity, cost, and power consumption for wireless connectivity of inexpensive, portable, and moving devices. ZigBee uses the IEEE 802.15.4 standard as its communication protocol for medium access control (MAC) layer and physical (PHY) layer. The IEEE 802.15.4 MAC layer achieves duty-cycle operations by setting two system parameters, ���������������������������� (����) and ������������������ ������������������ (����), to achieve low power consumption for ZigBee devices. This study comprehensively analyzes IEEE 802.15.4 duty-cycle operation. Speciﬁcally, a novel analytical model that accommodates a general trafﬁc distribution is developed. An NS-2 based simulation model, which is validated by the developed analytical model is also proposed. Through the experiments conducted by the analytical and simulation models, some important performance-evaluation insights are gained that can be used as guidelines for future low-power ZigBee network deployment. Index Terms—IEEE 802.15.4, ZigBee, low-power operation, performance analysis.
monitoring, and health care . In ZigBee, IEEE 802.15.4 is utilized as the communication protocol for the medium access control (MAC) layer and physical (PHY) layer , and supports low data-rate (i.e., 20kbps, 40kbps, and 250kbps). Such low transmission rate and low-cost characteristics make ZigBee suitable for wireless systems comprising unsupervised groups of devices in houses, factories and ofﬁces. To facilitate ZigBee network deployment, most devices are unplugged, and rather operated by batteries. Additionally, the target environments in which devices operate can be so complex that changing device batteries becomes difﬁcult or even impossible. Thus, how to achieve efﬁcient energy consumption for devices with small power supplies is critical to ZigBee applications. IEEE 802.15.4 MAC layer provides a duty-cycle operation by setting two system parameters, ���������������������������� (����) and ������������������ ������������������ (����), such that low power consumption is achieved for ZigBee networks . In addition to determining the duty cycle, the ���� and ���� parameters collaboratively provide various low-power attributes under a single duty cycle for diverse environments . Simultaneously increasing ���� and ���� increases the transmission latency and decreases system throughput due to intensive channel contention, whereas simultaneously decreasing ���� and ���� reduces available bandwidth and increases the energy consumption during beacon reception. Each low-power attribute via setting the ���� and ���� values has its own impact on transmission and energy efﬁciency of IEEE 802.15.4 MAC layer. With a very limited bandwidth and power capacity for IEEE 802.15.4 devices, any unnecessary transmission overhead or excessive power consumption resulting from improper ���� and ���� settings could markedly degrade device performance. Additionally, inappropriate ���� and ���� settings for a low duty-cycle system may lead to more power consumption than that of a high duty-cycle system with optimal ���� and ���� values. Unfortunately, IEEE 802.15.4 does not explicitly suggest ���� and ���� values. To our best knowledge, the settings for ���� and ���� are based on manual tuning methodologies, which is a time-consuming deployment process. Thus, a comprehensive investigation of low-power operation in IEEE 802.15.4 is necessary. In the past years, some notable research results have been presented for the analyzing of power saving mode (PSM) in IEEE 802.11 , , . However, the IEEE 802.11 PSM is...
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