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
70
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
Copyright
c
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
71
- 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.
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Then sensing information is transmitted to
the Agent (Router) which can mediate.
(c) Agent (Router) mediates the sensing
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
DB
Sensor
Driver
ZigBee
Network
IEEE 802.15.4
MAC
IEEE 802.15.4
PHY
Sensing
DB
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
73
1. Host
2. Agent 1 ~ 3
3. Agent 4
4. Packet Sniffer
5. Host Monitoring
6. Packet Monitoring
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.
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74
- 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.
(c) Agent supplies the power to PC according
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.
(c) Agent blocks the standby power according
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
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