Personal Area Networks: Nearfield intrabody communication

1
Personal Area Networks Near-field intrabody
communication

• By T.G Zimmerman

2
Introduction

• Use the human body as the communication medium
• Many I/O devices are duplicated
• Watch,PDA,Cell-phone, all have displays
• Network devices that are close to the body using
  capacity coupling though the body
• Such communication can be achieved in a power
  efficient manner

3
Advantages

• Makes use of near field effects
• Low frequencies, below 1MHz, typically 0.1-1
  MHz, Low power (few mW)
• Very short range
• Higher density
• More difficult to intercept
• Less Interference
• Well below FCC limits so no strict licensing
  limits
• Avoids duplication of personal devices

4
Challenges

• Privacy/Security
• Beacon signals can be used to keep track of
  people
• Personal information such as credit card numbers,
  telephone numbers and computer passwords can be
  stolen
• Communication becomes difficult or stops when
  touching good conductors

5
A Closer Look

• Information transmitted on a modulating picoamp
  displacement current
• Electrical Model

6
Electrical Model of PAN System
7
The PAN Prototype

• Using the Hartley Shannon Law
• Capacity B log (1S/N)
• B -bandwidth, S -signal, N Noise
• -3dB BW is around 400KHz
• max channel capacity 417kbps
• assuming SNR 10
• Actual transceiver prototype 2400bps
• Dimensions 8 x 5 x 1 cm

8
PAN Prototype (cont.)

• Modulation schemes
• on-off keying ( on 1, off 0 )
• DSSS

9
Electronic Handshakes

• Transmitter placed inside shoe insets
• can be charged during walking
• When 2 people are in close proximity they can
  exchange business card information.
• Business card information is continuously
  transmitted as a set of ASCII characters.
• When people shake hands the information can be
  downloaded to each others PDAs.

10
Conclusions

• Design based on 7 layer ISO model
• Only physical and data link layers developed
  here, rest of the layers need to be developed.
• Many traditional digital communication principles
  can apply to this domain
• Higher data rates seem feasible
• Concept of power sneakers seems promising