S. Ata and C.S. Hong (Eds.): APNOMS 2007, LNCS 4773, pp. 515–518, 2007. © Springer-Verlag Berlin Heidelberg 2007

Standby Power Control Architecture in Context-Aware Home Networks

Joon Heo1, Ji Hyuk Heo1, Choong Seon Hong1, Seok Bong Kang2, and Sang Soo Jeon3

1 Department of Computer Engineering, Kyung Hee University, 1 Seocheon, Giheung, Yongin, Gyeonggi, 449-701 South Korea

{heojoon,jihyuk,cshong}@khu.ac.kr 2 I’ware Inc., Ltd., Kangnam Internet Business Center #508 San 6-2 Gukal,

Giheung, Yongin, Gyeonggi, 449-702 South Korea sbyhkang@naver.com

3 VITZRO SYS Co., Ltd., 233-3, 1Dong, Sungsu-2, Sungdong, Seoul, 133-826 South Korea paul@vitzrosys.com

Abstract. Standby power is the energy consumed by appliances when they are not performing their main functions or when they are switched off. In this pa-per, we propose a Host-Agent based standby power control architecture in con-text-aware home network. The proposed architecture uses the IEEE 802.15.4 based ZigBee protocol between Host and Agent for communication and secu-rity. We have made an experiment on according to various context-aware sce-narios using the implemented prototype devices.

1 Introduction

Products that have power switches consume certain amounts of standby power. Par-ticularly, products such as consumer electronics, office equipments and white goods, where the ‘standing by’ time exceeds the operation time, have high standby power consumption. By 2020 standby power consumption is projected to be 1/4 of the total household energy consumption, and the main cause of such an increase can be attrib-uted to the home network system [1]. The IEEE 802.15.4 standard defines transmis-sion and reception on the physical radio channel (PHY), and the channel access, PAN (personal area network) maintenance, and reliable data transport (MAC) [2]. ZigBee defines the topology management, MAC management, routing, discovery protocol, security management and includes the 802.15.4 portions. ZigBee is a new low rate wireless network standard designed for automation and controlling network. The standard is aiming to be a low-cost, low-power solution for systems consisting of unsupervised groups of devices in houses, factories and offices [3]. In this paper, we propose standby power control architecture in context-aware home network. This paper is organized as follows: Section 2 describes the Host-Agent based system archi-tecture, context modeling and context management. Implementation results of proposed mechanism are presented in section 3. Finally, we give some concluding remarks and future works in section 4.

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2 Proposed Standby Power Control Architecture

Proposed standby power reduction architecture is the Host-Agent based. Where Agent acquires the current local context information using the various embedded sensor and sends this information to the Host. The Host compares this context information from Agent with current database and sends standby power control message to Agents. This architecture uses the IEEE 802.15.4 based ZigBee communication protocol be-tween Host and Agent for context information and control message transmission. Also, in order to enable natural and meaningful interactions between the context-aware home and its occupants, the home has to be aware of its occupants’ context, their desires, whereabouts, activities, needs, emotions and situations. Such context will help the home to adapt or customize the interaction with its occupants. By con-text, we refer to the circumstances or situations in which a computing task takes place [4]. Context modeling is about providing a high level abstraction of context informa-tion. The diversity of contextual information and its use in diverse domains lead to different ways for modeling context. We define the use of dynamic sensing informa-tion (user, environment and system). Contextual information is modeled as main-value pairs called sensing information. Figure 1 shows an example of context modeling for standby power reduction.

Fig. 1. Main-value based context modeling

Fig. 2. Context-aware management architecture

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Also, we have designed context management architecture for standby power con-trol. A high-level view of the main components of this architecture is shown in Figure 2. Context gathering sensors of Agents acquire and send the sensed context information to Host. Host also acquires context itself using the embedded sensors. Context should be monitored and updated as schedules.

3 Implementation and Test Results

As we explained before, the proposed architecture of this paper uses IEEE 802.15.4 based ZigBee communication protocol. Therefore, we have implemented network and security functions at prototype devices according to ZigBee specification [3]. The proposed control architecture has been organized based on tree topology. Require-ment functions such as routing, address allocation, encryption/decryption and message authentication have been tested. Implemented security module can support ZigBee security specification such as CCM* algorithm, MAC/NWK layer security, key establishment, message encryption/decryption and message integrity [4].

Fig. 3. Agent Prototype and Characteristics

Fig. 4. Host Prototype and Characteristics

Real features of implemented prototype device and characteristics are shown in Figure 3(Agent) and Figure 4(Host). Agent has implemented 3 types (wall socket type, movement type, switch type). Each type can be used according to control sce-narios. To prove the necessity and the efficiency of the proposed control mechanism, we have made an experiment on control test according to various context-aware sce-narios using the implemented prototype devices. Table 1 explains the test scenarios and Figure 5 shows the testbed. Similar standby power value has been estimated at all

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Table 1. Test Scenarios according to context situation

Scenario Contex-aware Controlled Agent 1 indoor light sensing value of Agents Agent 1 (socket type outlet) 2 PIR sensing value of Host Agent 2 (socket type outlet) 3 light sensing value of desk lamp Agent 3 (movement type outlet) 4 CT value of electronic device Agent 4 (movement type outlet) 5 switch touching of user Agent 5 (button type switch)

Fig. 5. Testbed according to scenarios

of Agents. The estimated electric current of Agent is 203mW when working state; the other side, electric current of Agent is 80mW when sleep state.

4 Conclusion

We propose a standby power control mechanism in home network environment. The Agent acquires the current local context information using the various embedded sensors and sends this information to Host. The Host compares this context informa-tion from Agent with current database and sends the standby power control message to Agent. Our future work will analyze the mechanism according to various scenarios in home network. Also, authenticity of context-aware algorithm should be enhanced.

References

1. Kim, Y.R.: KOREA 1W Policy. In: Standby Power Conference 2006 (November 2006) 2. Wireless Medium Access Control and Physical Layer Specification for Low-Rate Wireless

Personal Area Networks. IEEE Standard, 802.15.4-2003 (May 2003) 3. ZigBee Document 053474r13 ZigBee Specification (December 2006) 4. Heo, J., Hong, C.S., Kang, S.B., Jeon, S.S.: Wireless Home Network Control Mechanism

for Standby Power Reduction. In: Proceedings of the International Conference on Wireless Information Networks and Systems, pp. 70–75 (July 2007)