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, JAPANBackground 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 Our Group Navigation System Server 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 Server Ad-hoc Communication Navigation Server ManagementTool Leader Member Personal Navigation System Group GPS 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 ・ Comment ・ Start ・ End Path ・ Longitude ・ Latitude ・ Name ・ File ・ Comment Point ・ ImagePicture ・ Vector maps Map Search Engine ○Route search ○Create Contents ○Create URL of Picture Trim of map Sending Picture Navigation Server SQL Server Management Tool Personal Navigation Facility Mobile Terminals Start Turning Point End Warning message Navigation Navigation Server provides Text, Map and Picture data to each member Send warning message if some members come off from the navigation route Wireless LAN 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 Emulate the mobility of users Users with mobile terminals seems to be moving on the general map Rehearse whether to transmit information correctly Click Synchronizes with the place on the map Management Tool Variable configuration files Rehearsal Mode of Management Tool Map Mobile Terminal Emulator Coordinates ⇒ longitude & latitude User who has the mobile terminal seems to move on the map Mobile Terminal Emulator shows the navigation of the point

Simulation Experiments Examination of GPS distribution intervals Short: Easy to observe member's position Long: Member’s 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 (  A realistic network simulator for MANET  It can simulate mobility of mobile node under realistic environment 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 parent’s member-node list Distribution interval of GPS information packet is the trade-off of the power consumption and the group maintenance 1. Generate GPS packet 3. Add node A to the neighbor-list 4. Broadcast all member-node list A P C 2. Receive the packet of members And refresh nodes list Server Leader Leader Group Warning Message If members left from it’s leader’s 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 Warning Packet Leader Node A Node B GPS Distribution Interval Time after member goes out of leader’s 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 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 Leader ’ s wireless range Receiving warning packet