PERSONALLY CUSTOMIZABLE GROUP NAVIGATION SYSTEM USING CELLULAR PHONES AND WIRELESS AD-HOC COMMUNICATION Yoshitaka Nakamura, Guiquan Ren, Masatoshi Nakamura, Takaaki Umedu and Teruo Higashino Osaka University, JAPAN

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PERSONALLY CUSTOMIZABLE GROUP NAVIGATION
SYSTEMUSING CELLULAR PHONES AND WIRELESS AD-HOC
COMMUNICATIONYoshitaka Nakamura, Guiquan Ren,
Masatoshi Nakamura, Takaaki Umedu and Teruo
HigashinoOsaka University, JAPAN

• Background
• Portable computing devices have been developed
• With GPS and Wireless Communication
• ?
• Some Navigation Services are provided
• Personal Navigation
• Location Searching for others
• Map Search
• Few navigation service for Group has been
  proposed so far
• Example Navigation for Group Tour

• Problems of Group Navigation
• This system needs route navigation and group
  management facilities
• Using unicast communication between the server
  and the terminal
• Separate download of same information is
  inefficient
• Bandwidth congestion problem occurs when many
  terminal concentrates in a single base station

• Solution
• Only a few terminals communicate with the server
• Distribute information by wireless ad-hoc
  communication
• ?Traffic on the wireless Internet network can be
  decreased by sharing the information between
  terminals

Ad-hoc Communication
Server
Server
Our Group Navigation System

• Navigation
• Navigation Server provides Text, Map and Picture
  data to each member
• Send warning message if some members come off
  from the navigation route

• Rehearsal Mode
• Emulate the mobility of users
• Users with mobile terminals seems to be moving on
  the general map
• Rehearse whether to transmit information correctly

• Outline of Group Navigation
• Servers and client softwere are implemented by
  JAVA
• Personal Navigation Facility
• Navigation Server Provides service on the Web
• Management Tool Customizes navigation data
• Group Management Facility
• Leader Connect to the Web by PHS or Mobile Phone
• Member Receive data via Leader by Wireless LAN

GPS
Warning message
Map
Rehearsal Mode of Management Tool
End
Synchronizes with the place on the map
Personal Navigation System
Group
Coordinates ? longitude latitude
Start
Turning Point
Navigation Server
Management Tool
Leader
Member

• Construction of Navigation Scenario
• Management Tool
• Construction of Scenario Mode
• Users can add
• Point data(Picture, Text message and Map)
• Path data(Text message and Map)
• Route data(Constructed by some paths)
• Rehearsal Mode

Wireless LAN
Click
Personal Navigation Facility

Mobile Terminal Emulator
Mobile Terminals
Variable configuration files

• User who has the mobile terminal seems to move
  on the map
• Mobile Terminal Emulator shows the navigation of
  the point

Search Engine ?Route search ?Create
Contents ?Create URL of Picture
Trim of map
Sending Picture
Navigation Server
SQL Server
Comment Start End
Path
Longitude Latitude Name File Comment
Point
Management Tool
Management Tool
2

• Group Management Facility
• Not to make member get lost from group
• Each member periodically scatters the packet
  including GPS information
• Members make the leader which receive this packet
  as a parent
• Leader observes the member-node position and
  maintain the group
• Several leaders cover the entire group
• Member makes one of leaders as parent
• Leaders exchange the member-node list with each
  other, and know the position of all members
• When members can communicate with two or more
  leaders, they can select one parent who receive
  service by itself

• Group Construction
• Participation in the group (child?parent)
• Each member periodically scatters the packet
  including GPS information
• Leader adds received GPS information of the
  member to the member-node list
• Leader delivers its member-node list to the
  member
• Member confirms the addition to the group by
  received parents member-node list
• Distribution interval of GPS information packet
  is the trade-off of the power consumption and the
  group maintenance

• Warning Message
• If members left from its leaders wireless range
• Cannot receive the navigation data and announce
  from the leader
• The leader discovers member (e.g. node A) with
  the problem from GPS information then the
  communication situation, and sends the warning
  packet
• If the leader cannot send warning packet to the
  member directly, leader send it via another
  member (e.g. node B) near the member

Leader
1. Generate GPS packet
A
Warning Packet
C
Node B
Server
3. Add node A to the neighbor-list
Node A
Leader
Leader
2. Receive the packet of members And refresh
nodes list
4. Broadcast all member-node list
Group

• Simulation Experiments
• Examination of GPS distribution intervals
• Short Easy to observe member's position
• Long Members power consumption is decreased
• Simulation of the group mobility
• Leader can catch its members continuously
• Warning to member away does not become too late
• Using Network Simulator MobiREAL
  (http//www.mobireal.net)
• A realistic network simulator for MANET
• It can simulate mobility of mobile node under
  realistic environment

P

• Simulation of the Group Mobility
• Scenario
• Sightseeing of Kyoto city
• of leaders 3, of members 200
• The distance limit of wireless communication is
  70m
• From the simulation results, we could confirm,
• Member who starts coming off from the group can
  receive the warning packet
• And the member can return to the group

Leaving out of wireless range

• GPS Distribution Interval
• Time after member goes out of leaders
  communication range, until is caught by a leader
• More than 10s, it takes much time until the
  warning packet reach the member
• It cannot catch up with a speed away of the
  member when it takes 30s or more for catching

Leaders wireless range
Receiving warning packet