WIRELESS HOME NETWORK CONTORL MECHANISM

FOR STANDBY POWER REDUCTION

Joon Heo, Choong Seon Hong

Dep. of Computer Eng., Kyung Hee Uni., 1 Seocheon, Giheung, Yongin, Gyeonggi, 449-701 South Korea

Seok Bong Kang

Kangnam Internet Business Center #508, Giheung, Yongin, Gyeonggi, 449-702 South Korea

Sang Soo Jeon

233-13, 1Dong, Sungsu-2Ga, Sungdong-Gu, Seoul, 133-826 South Korea

Keywords: Standby Power Reduction, Home Network, Low Power Wireless Communication.

Abstract: Standby power is electric power that a device consumes when not in present use, but plugged in to a source

of power and ready to be used. Present estimates indicate that standby power consumption reaches 10 to 15

percent of total residential electrical use. In this paper, we propose a Host-Agent based standby power

control mechanism in home network environment. It uses the IEEE 802.15.4 based ZigBee communication

protocol between Host and Agent for transmission and secure network. The Agent can acquire the local

context information from various embedded sensor and sends the sensing information to the Host. The Host

compares this context information from Agent with database and sends the standby power control message

to the Agent. To prove the necessity and the efficiency of the proposed control mechanism, we have

developed prototype devices and carried out simulation according to control scenario.

1 INTRODUCTION

Standby electricity is the energy consumed by

appliances when they are not performing their main

functions or when they are switched off. As more

and more appliances are being used in households

and offices, their energy consumption during

standby periods represent a significant share of the

total energy used. Household appliances and office

equipments such as televisions (TVs), video

recorders, audio players, telephone answering and

facsimile machines, computers, printers and copiers

contribute to this standby loss which is relatively

low, with typical loss per appliance ranging from

less than 1 W to as much as 25W. According to the

IEA, on an average, 10% of a total household

(OECD) power consumption is being wasted in the

form of standby power (Standby Korea 2010).

Moreover due to the special characteristics of home

network devices such as set top box, xDSL modem,

home gateway, PC and TV can all be connected to

the external communication system in standby

mode; an increase of standby power consumption is

expected. It is apparent that the future market will be

dominated by electric/electronic devices with

network functions, rather than those devices without

network functions. The number of products with

standby power consumption is growing rapidly in

both quantity and diversity (Standby Korea 2010).

ZigBee is a new low rate wireless network

standard designed for automation and control

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. Expected applications for the ZigBee

are building automation, security systems, remote

control, remote meter reading and computer

peripherals. The ZigBee standard utilizes IEEE

802.15.4 standard as radio layer.

In this paper, we propose a standby power

control mechanism in home network environment.

Proposed mechanism uses the IEEE 802.15.4 based

ZigBee communication protocol between Host and

Heo J., Seon Hong C., Bong Kang S. and Soo Jeon S. (2007).

WIRELESS HOME NETWORK CONTORL MECHANISM FOR STANDBY POWER REDUCTION.

In Proceedings of the Second International Conference on Wireless Information Networks and Systems, pages 70-75

DOI: 10.5220/0002147500700075

 SciTePress

Agent for context information and control message

transmission. Agent acquires the local context

information from various embedded sensor and

sends to the Host. Host compares this context

information from Agent with database and sends the

standby power control message to Agent.

This paper is organized as follows. Section 2

explains about related works such as standby power

consumption of home network, context-aware

concept and low power wireless protocol. Section 3

describes the proposed low power communication

and security modules. This section also explains

Host-Agent based control system architecture.

Implementation results and prototype device of

proposed mechanism are presented in section 4.

Finally, we have given some concluding remarks

and future works.

2 RELATED WORKS

2.1 Standby Power Consumption and

Context-aware of Home Network

A new form of standby power called ‘Active

Standby’ is becoming a reality that we have to face.

The emergence of active standby power started with

the introduction of set top boxes. It is a power mode

where the consumer switches off the power (the

consumer thinks the power is switched off

completely) but the internal circuit still consumes

standby power to wait for external cord/cordless

signals. 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 attributed to the home network system. In

1999, IEA has proposed to reduce the standby power

of all electronic products below 1W, the so called 1-

watt Plan. Several countries such as US government

(2001), Australian government (2002) and Korea

government (2004) already announced a national

strategy to achieve the 1W standby power target

(Standby Korea 2010).

Proposed mechanism integrated with various

sensors, actuators, wireless networks and context-

aware technology will control standby power. In

order for adaptation to take place, application must

become aware of their surrounding environment,

otherwise known as context. 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

context, we refer to the circumstances or situations

in which a computing task takes place. Context of an

entity A is any measurable and relevant information

that can affect the behaviour of A. Context can be

considered and exploited as different levels of

abstraction (S. Mayer and A. Rakotonirainy).

2.2 Low-Power Wireless Protocol

The IEEE 802.15.4 wireless standard was developed

specifically for remote monitoring and control. The

standard defines transmission and reception on the

physical radio channel (PHY), and the channel

access, PAN (personal area network) maintenance,

and reliable data transport (MAC) (Wireless 2003).

ZigBee defines the topology management, MAC

management, routing, discovery protocol, security

management and includes the 802.15.4 portions.

ZigBee is designed for applications that need to

transmit small amounts of data while being battery

powered so the architecture of the protocols and the

hardware is optimized for low power consumption

of the end device. The coordinator and routing

devices should not be battery powered, as these

should be able to receive and transmit all the time.

Also the network functionality depends on this. The

data transfer mechanism depends on the topology.

Security and data integrity are key benefits of the

ZigBee technology. The ZigBee architecture

recognizes two types of devices RFD (Reduced

Function Device) and FFD (Full Function Devices).

Only the FFD defines the full ZigBee functionality

and can become a network coordinator. The RFD

has limited resources and does not allow some

advanced functions (e.g. routing) as it is a low cost

end device solution. Each ZigBee network has a

designed FFD that is a network coordinator. The

coordinator acts as the administrator and takes care

of organization of the network. Typical coordinator

has a neighbour table of devices found in the

neighbourhood. This leads to extended demands on

the coordinator device, as it needs more memory and

processing power (J. Gutierrez and et all,

2003)(ZigBee).

3 STANDBY POWER

REDUCTION MECHANISM

The goals of proposed standby power control

mechanism are like below:

- Standby power consumption ≤ 200mW

- Sensor embedded Agent and operation

WIRELESS HOME NETWORK CONTROL MECHANISM FOR STANDBY POWER REDUCTION

- Low power actuator

- Device compatibility

- High authenticity of Host

- Context-aware algorithm application

3.1 Low Power and Secure Network

Proposed mechanism uses the IEEE 802.15.4 based

ZigBee communication protocol between Host and

Agent for context information and control message

transmission. Also, security function of specification

is applied for data transmission. Communication and

security module should consider whether hardware

platform and defined operation algorithm are

available. In home network environment, the defined

functions of communication and security are shown

in Table 1. Defined functions are focus on network

management and high level security.

Table 1: Function definition for proposed system.

Section Function Definition

Network

Device

Management

- Role separation of Host and Agent

- Channel scan and selection

- Allowing Agent to join

- Neighbour table management of Agent

- Allocation of unique network address

- Disassociation

Routing

- Routing table management

- Routing cost calculation

- Route discovery and recovery

Broadcast - Efficient broadcasting algorithm

Authentication

- Security level

- Message authentication code

Secure Key

Establishment

- Secure key distribution from Host

- Key transport mechanism

Encryption

/Decryption

- Enc./Dec. according to the security level

- Secure key agreement

First of all, security problem should be solved.

The attacker can eavesdrop and modify easily

because Host and Agent use wireless

communication for message transmission. This

weakness can be threatened not only standby power

control but also entire home network. Therefore, the

security technologies of IEEE 802.15.4 and ZigBee

specification should be implemented at Host and

Agent for secure control network. Figure 1 shows

the concept of implemented security service. Used

security module of this paper can support all security

functions of ZigBee security specification (ZigBee).

AES

CCM*

SSP

SSP : Security Service Provider

CCM* : CTR and CBC-MAC mode *

AES : Advanced Encryption Standard

ZigBee

IEEE 802.15.4

Figure 1: Security concept of IEEE 802.15.4 and ZigBee.

3.2 Host-Agent based Control

Mechanism

Host and Agent are the two main component of our

proposed standby power reduction mechanism.

Where Agent acquires the local context information

using the various embedded sensor and sends this

information to the Host. The Host compares this

context information from Agent with database and

sends standby power control message to Agents. In

home network environment, the operation procedure

and standby power control method are shown in

Figure 2. The Agents can be embedded in electronic

devices and wall sockets; Agent can control standby

power itself using the context information or drive

actuator after receiving control message from Host.

Host

Agent (Router)

Agent (End Device)

Sensing Area

Step 1

Step 2

Step 3

Figure 2: Standby power control mechanism.

The operations and different functions of Host and

Agent are described below.

[Step 1]

(a) Agent (End Device) sense the specific

context information using the embedded

sensors such as light, temperature, infrared

ray, remote control and humidity.

(b) Agent (End Device) control standby power

mode itself using the sensing information

according to embedded control algorithm.

WINSYS 2007 - International Conference on Wireless Information Networks and Systems

Then sensing information is transmitted to

the Agent (Router) which can mediate.

information to Host.

[Step 2]

(a) Host receives the context information from

Agent then refer the attribute DB of Agents

(Router, End device).

(b) Host transmits actuator On/Off control

message to Agents.

[Step3]

(a) Agent (Router) can mediate control

message to Agent (End device) which can

not receive the message itself.

(b) Agent (End device) drives actuator after

receiving On/Off control message from

Host.

3.3 Sensing Information Acquisition

Proposed control mechanism applies simple context-

aware algorithm for power actuator control. Figure 3

shows the embedded sensors of Agent for sensing

and Figure 4 shows the structure of Host and Agent

module for sensing data transmission.

MCU

GIO

Port

MCU

ADC

Port

Temperature

sensor

Light

sensor

Infrared ray

sensor

Etc.

sensor

Remote

control

sensor

Humidity

sensor

Figure 3: Embedded Sensors in Agent.

Host

Algorithm

Sensor

Driver

Agent

Algorithm

Sensing

Sensor

Driver

ZigBee

Network

IEEE 802.15.4

MAC

IEEE 802.15.4

PHY

Sensing

ZigBee

Network

IEEE 802.15.4

MAC

IEEE 802.15.4

PHY

Figure 4: Sensing data transmission.

Table 2: Definition of sensors.

Context

-aware

Type of

Sensor

Control

Application

Sensing

Information

Power

status

Current

Interception

Condition

Current value

from CT

Light Light Supply Condition

Illumination

value

User

sensing

PIR Supply Condition

Movement of

user

Using

pattern

Current Supply Condition

ON/OFF of

devices

Purposes of embedded sensors shown in Figure 3 are

like below:

- Light sensor / Infrared ray sensor: to sense the

motion of a user.

- Temperature sensor / Humidity sensor: to sense

the information of circumference environment.

- Remote control sensor: to sense control

message when remote controller is used.

As shown in Table 2, we have defined type of sensor,

standby control application and sensing information

according to context-aware information.

4 IMPLEMENTATION

In this section, we define the required items for

proposed mechanism implementation for real home

network. Also, we analyze standby power reduction

effect using the developed prototype devices.

4.1 Network and Security Module

As we explain before, the proposed mechanism of

this paper uses IEEE 802.15.4 based ZigBee

communication protocol for context information and

control message transmission between Host and

Agent. Therefore, we have implemented network

and security functions according to ZigBee

specification (ZigBee). Figure 5 shows the scope of

implemented functions at network module and

security module.

MAC

PHY

AES

CCM*

SSP

(Security

Service

Provider)

APL

NWK data service

Network formation

Allowing devices to join

Joining a network

Resetting a device

Receiver synchronization

Information maintenance

NWK

Figure 5: Implemented ZigBee functions.

The proposed control mechanism has been

organized based on tree topology. Requirement

functions such as routing, address allocation,

encryption/decryption and message authentication

have been tested as shown in Figure 6.

WIRELESS HOME NETWORK CONTROL MECHANISM FOR STANDBY POWER REDUCTION

1. Host

2. Agent 1 ~ 3

3. Agent 4

4. Packet Sniffer

5. Host Monitoring

6. Packet Monitoring

①

②

③

④

⑥

⑤

Host

Agent1

Agent2

Agent3

Agent4

Host

Agent (Router)

Agent (End Device)

Figure 6: Tree-based test topology.

Specially, security service is very important in this

mechanism because Host and Agent use wireless

communication protocol. Implemented security

functions are like below:

- CCM* for encryption and authentication

- MAC, NWK layer security

- Key establishment

- Lightweight security code

- Encryption/decryption of message

- Message integrity for authentication code

- Symmetric key based system

- Security level

4.2 Prototype Device Development

To develop prototype devices, required items of

Host and Agent should be defined. We have

considered such as power module, context-aware

sensor module and MCU module of Host and Agent.

Also, these requirements have implemented in a

prototype devices. Table 3 explains required items

and implementation result of Host; also, Table 4

explains required items and implementation result of

Agent.

Table 3: Requirements and Implementation of Host.

Module Requirement Implementation

MCU

Module

- minimize power

consumption

- role of Coordinator

- power consumption

management

- using the low power

consumption MCU

- Coordinator function

implementation

- power management

algorithm

Context-

aware

sensor

Module

movement sensing

- environment

condition sensing

- authenticity of

sensing

- using the infrared ray

and IR sensor

- temperature, humidity

and light sensor

- sensitivity motion

database

Table 4: Requirements and Implementation of Agent.

Module Requirement Implementation

Power

module

- systematic voltage

supply (12V,3.3V)

- wall socket size

- power consumption

less than 0.06Watt

- noise

- electronic element

voltage supply

- Transformer-less type

- low power

consumption regulator

- RC Filter and TNR

Current

Sensing

Module

- small size

- maintenance of

linear type

- strength till

authentic range

- current transformer

- maintenance at 0~2A

input(CT)

- maintenance of CT at

15A input

Actuator

Module

- strength till

authentic range

chattering

countermeasure

- input strength

maintenance

- Noise countermeasure

Context-

aware

sensor

Module

movement sensing

- environment

condition sensing

- authenticity of

sensing

- using the infrared ray

and IR sensor

- temperature, humidity

and light sensor

- sensitivity, motion

database

MCU

Module

- low power

consumption

- Interface with

ZigBee module

- sufficient memory

- measurement and

control ports

using the low power

MCU

- UART communication

interface with CC420

- ROM /RAM > 1Mbyte

- 12bit ADC Port

Real features of developed prototype device and

characteristics are shown in Figure 7 (Host) and

Figure 8 (Agent). Host prototype has the light sensor

and PIR sensor; it can be located in ceiling. First of

all, we have developed wall socket type Agent.

Movement type Agent and switch type Agent will be

developed. Each type can be used according to

control scenarios.

- Context-aware algorithm application

- Availability 80 %

- Communication rate: 90kbps

- Communication distance: 30m

- Response speed: 0.5 second

- 32bit ARM Core embedded in TCC760 Microprocessor

- CC2420 based ZigBee communication IC

- Standby power control algorithm

Host Prototype Development

Figure 7: Host prototype and characteristics.

WINSYS 2007 - International Conference on Wireless Information Networks and Systems

- Standby power consumption: 200mW

- Low power consumption current sensor module

- Leakage current detection sensor module

- Actuator module using the 2P Triac

- ZigBee communication module

- Context-aware sensor application

- Passive leakage interception switch application

- General wall socket size

Agent Prototype Development

Figure 8: Agent prototype and characteristics.

4.3 Preliminary Results

[Standby power supply scenario]

(a) Hide the lighting sensor of Host (user

existence)

(b) Host can sense the user existence using the

sensor. Then Host transmits the power

supply message to Agent.

to control message from Host.

[Standby power block scenario]

(a) While user uses PC, an electric current

increases up to maximum critical condition

value. This status will be recognized as

working status by Host.

(b) After a user put off the PC, electric current

decreases slowly. Agent sends this

information to Host; if the electric current

less than critical condition, Host sends

standby power block message to Agent.

to control message from Host.

Table 5: Estimated results.

section

Using

Voltage

Working

Current

Sleep

Current

RF 3.0 V 30 mA  0 mA

MPU 3.0 V 63 mA  0 mA

Current sensor 3.0 V  0 mA  0 mA

Light sensor 3.0 V  0 mA  0 mA

Actuator 3.0 V  0 mA  0 mA

Power Supply 3.0 V 110 mW 80 mW

Total Power

consumption

3.0 V

93 mW

+110 mW

0 mW

+80 mW

0.84 sec

0.16 sec

0.080Watt

0.203 Watt

0.203 Watt x 0.16Sec + 0.080Watt x 0.84Sec = 0.09968Watt

[Working Mode]

Watt

[Sleep Mode]

[Average]

Figure 9: Result analysis.

The estimated standby power value according to the

scenario is shown in Table 5 and Figure 9. As shown

in these results, electric current of Agent is 0.203W

when working state; the other side, electric current

of Agent is 0.080W when in sleep state.

5 CONCLUSION

We propose a standby power control mechanism in

home network environment. Our proposed

mechanism uses the IEEE 802.15.4 based ZigBee

communication protocol between Host and Agent

for context information and control message

transmission. To prove the necessity and efficiency

of the proposed mechanism, we have developed

prototype devices. Our future work will analyze the

mechanism according to various scenarios in home

network. Also, authenticity of context-aware

algorithm should be enhanced.

REFERENCES

Ministry of Commerce, Industry and Energy, “Standby

Korea 2010”, from http://www.mocie.go.kr

“Wireless Medium Access Control and Physical Layer

Specification for Low-Rate Wireless Personal Area

Networks”, IEEE Standard, 802.15.4-2003, May 2003.

Jose A. Gutierrez, Edgar H. Callaway Jr and Raymond L.

Barrett Jr, “Low-Rate Wireless Personal Area

Networks,” IEEE Press 2003.

ZigBee Document 053474r13, "ZigBee Specification",

from http://www.zigbee.org

Sven Meyer, Andry Rakotonirainy, “A Survey of

Research on Context-Aware Homes,” Conference in

Research and Practice in Information Technology

Series, Proceeding of the Australasian information

security workshop conference on ACSW frontiers

2003, vol.21, pp.159-168, 2003.

WIRELESS HOME NETWORK CONTROL MECHANISM FOR STANDBY POWER REDUCTION