7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 1/16

 An Efficient Multi-channel Management

Protocol for Wireless Body Area Networks

Wangjong Lee*, Seung Hyong Rhee*, Youjin Kim** and Hyungsoo Lee**

*

Kwangwoon University, Korea,** Electronics and Telecommunications Research Institute, Korea

International Conference on Information Networking (ICOIN), 2009

Computer Systems Lab Group MeetingPresented by: Zakhia Abichar 

 April 15, 2010

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 2/16

2

Receiving device options

 Application: Nike+  

• 2 nodes: sensor & receiving device• Sensor inserted into shoes

• Sensor measures distance

• Transmits in wireless to on-bodydevice; upload to computer 

• Track progress; train on a program

Wireless-enabled iPodCost: $19 (sensor-only)

Wireless-enabled iPodCost: $29 (sensor +wireless receiver)

Nike SportbandCost: $78 (sensor +Sportband)

Sensor  Sensor insertion

Track progress

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 3/16

3

 Application: Adidas miCoach

• System: miCoach pacer (cost: $139)

• 3-nodes system: – Sensor measure the speed

 – HRM measure the heart rate

 – Pacer gathers the information viawireless

• Pacer gives audio feedback: speed up, slow down  – Based on HRM & training goal

• Wireless standard used ANT+

•  Also available: miCoach ZONE – HRM + sport-like device (Cost: $69)

 – Monitor hear-rate while exercising

Sensor 

HRM: HeartRate Monitor 

Pacer 

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 4/16

4

Wireless Body Area Networks

• They are also called WBAN

• Can be considered a successor of WPAN(Wireless Personal Area Network)

• WBAN have a range of 3 meters (9.8 ft)

• Medical or non-medical according to use

• In 2.4 GHz ISM band and 400 MHz band of 

MICS – ISM: Industrial Scientific Medical, used for Wi-Fi

 – MICS: Medical Implanted Communication Service

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 5/16

5

Technical Topic

• We need a protocol to reduce the interference in theMICS band – Interference between MICS systems

 – or between MICS and primary systems

• There is a an LBT (Listen-Before-Talk) protocol defined• LBT isn’t good for non-collision and emergency traffic

• This paper proposes an efficient way of multi-channelmanagement

 – The channel is reserved – Channel aggregation makes a single wide channel and satisfiesvarious traffic types

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 6/16

6

Outline

• Preliminary material

• Proposed scheme

• Simulation results

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 7/16

7

Preliminaries

• IEEE working to make WBAN standards through TaskGroup 802.15.6

• ITU-R issued Recommendation SA.1346 for MICS devices

401 402 403 404 405 406 MHz

METAIDS

MICS

METAIDS:Meteorological Aids

ITU-R: InternationalTelecom. Union -Radiocommunication

SA.1346:

• MICS devices should limit to -16 dBm in a bandwidth of 300 kHz toprevent interference with METAIDS

• Channel spacing of 25 kHz with channel aggregation up to 300 kHz

•  Also, there is LBT specs

• MICS use low power, concluded there’s no interference with METAIDS 

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 8/16

8

Distributed and Beacon-Enabled MAC Protocol

• This is the proposed scheme

• MICS band consists of 10 channels with 300 kHz bandwidth

• 1 channel is the control channel. The other 9 are data

• The control and data channels are not fixed

• Outbody device allocates the channels to inbody devices through thecontrol channel

• Outbody device continuously sends a beacon frame on the controlchannel

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 9/16

9

Channel Assignment

• Outbody device initiates communication with inbody devices

• It also senses the channels to set up a control channel

• MICS devices are secondary users; transmit/received when METAIDSdevices are silent

• They should coexist with other MICS; using LBT protocol• Outbody device selects one channel as the control channel after sensing

• It also assigns a channel number to each channel except the controlchannel

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 10/16

10

Channel Assignment

• On control channel, a beacon superframe consists of 9 beacon slots• Each beacon slot maps to a data channel

•  A beacon in the 1st slot means the 1st channel is reserved

• No beacon in the nth means the nth channel is not reserved

• Inbody devices listen to control channel to know what channel to use• Inbody devices then send a data packet to the outbody device on the

reserved channel

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 11/16

11

Supporting Sleep State

• Inbody devices have 2 modes: wake mode & sleep mode

• There is a duty cycle: wake/sleep•  At wake up, inbody device listens to control channel

 – If there is a channel allocated for it, it talks to outbody device

 – During this time, a beacon is sent on the control to indicate the datachannel is busy

 –  At end of communication, inbody device sleeps. Outbody device stops thebeacon for the sleeping device

 – If there was no data channel for it at wake up, inbody device sleeps

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 12/16

12

Channel Aggregation

• MICS frequency band has narrow channels

• This limits traffic types that need high bandwidth

• Outbody device can allocate aggregated data channels

 – by transmitting the same beacon in adjacent beacon slots

 – the channels are combined in a single wideband channel

• This scheme prevents a waste of resource by using channel guards• It also reduces transmission failure caused by narrow channel

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 13/16

13

Single MAC for 2 PHYs

• Two PHYs for WBAN: ISM (2.4 GHz) and MICS (400 MHz)• Use ISM for outbody communication and MICS for inbody 

communication

• Like MICS, ISM band is divided into non-overlapping channels

 – the same proposed scheme can be used

• WBAN device has two PHY layers and one MAC layer 

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 14/16

14

Simulation Results

• Simulation with ns-2, CMU wireless extension and MACmodules developed by Intel (refs.)

• Topology: 2 inbody devices communicating with 1outbody device

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 15/16

15

Throughput of Proposed Scheme and LBT

• In proposed scheme, control channel is overhead

• In LBT, sensing before transmission is overhead – sensing time is varied in simulation

Listening Time = 0.05 ms

Listening Time = 0.1 ms

7/30/2019 2010-04-15-BodyAreaNetwork

http://slidepdf.com/reader/full/2010-04-15-bodyareanetwork 16/16

16

Throughput with Channel Aggregation

• First case is one aggregate channel of 900 kHz

• Second case is 3 separate channels of 300 kHz each

•  Aggregation increases the throughput

Channel: 1 x 900 kHz

Channel: 3 x 300 kHz