Providing Group Tour Guide by RFIDs and WSNs

Yu-Chee Tseng, CS.NCTU

(a joint work with NTHU)(in IEEE Trans. on Wireless Comm.)(中華民國專利 : "使用無線感測網路提供群組導引服務之方法及系統 ", I319947)

Motivation

Traditional tour guide: personalized guiding by portable audio/mobile devices

They do not consider tourists as a group. Our goals:

a group guiding framework Feasible Low management effort

group guiding protocol with a prototype

System overview & Services

Leader tracking

Help service

Memberrecall

Group guiding services

1. Leader tracking• Sensors cooperate to track the locations of group

leaders.

2. Help service• Help lost members to find their leaders.

3. Member recall• A leader can call his/her members.

4. Push message• A leader can push information to his/her members.

Group guiding protocol (1/2)

How to track a group leader a signal-strength based method by “bidding”

HELLO

no HELLO for Talive sec.

no TRACKED within Talive sec. & continuous

HELLO

no BID with better RSSI is received

& no TRACKED is heared& no HELLO is lost

within Twin sec.

candidate

broadcast BID every Tbid sec.

tracker

broadcast TRACKED every Ttracker sec.

non-tracker

Ttracker, Thello, Tbid

0 1 2 3sec

Talive, Twin

TRACKED or HELLO

BID with better RSSI is received|| TRACKED is heared

|| HELLO is lostwithin Twin sec.

Group guiding protocol (2/2)

Mobility management

Leader Help Center

Member

Direction Board

Help Request Guiding Path

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

PBi

[0, clkA]

[1, clkA]

[2, clkA]

[2, clkA]

[1, clkA]

[2, clkA]

[2, clkA]

[3, clkA]

[3, clkA]

[3, clkA]

[3, clkA][4, clkA]

[3, clkA]

<4, clkA>

[5, clkA]

[4, clkA]

<1, clkB>

<0, clkB>

<1, clkB>

<1, clkB>

<2, clkB>

Move

A potential-based method is adopted for sensors to trace

the locations of leaders.

A local update is proposed to reduce update

messages.

System Architecture (WSN + RFID system)

Leader badge & direction board

XC2C128Control Module

MICAz

commands

Switch Circuit

Control Buttons

Power Supply

LED Matrix

BuzzerLED Matrix

XC2C128

Control Buttons

Buzzer

Help (Information) Center

LaptopMote

Help Center

1xxx 2xxx

Group X Group Y

RFID Tag

SQL Server

Database

WSNcommand

location

1xxx

1xxx

2xxx

2xxx

Network

RFID Reader

Help service & GUI

Prototyping system & Member-recall

Simulation results

Area: 100m*100m Nodes: 10*10, 30*30, and 50*50 Transmission range: 15m Trans. Data rate: 256 kbps Obstacles: 2*4 or 4*2 Pkt. Loss: 0% ~ 20% Each group has one leader and multiple

members.

Performance metrics

Message overhead Tracking leader Support group guiding services

Scalability Length of guiding path

Routing property

Message overhead & Scalability

Message overhead vs. Leader mobility Impact of obstacles on message overhead

Length of guiding path

AEH: Avg. excess hops

Response time vs. Packet loss

Overall message overhead

Conclusions

a feasible GROUP tour guide system based on RFID ease of management

Future work: integrating with real tour information realization in mobile devices, such as iPhone or

gPhone