1. Waiting-time Displays for Bus Passengers Team A: Huanwen Qu, Laurence Cabenda, Kang Ning

2. Assignment The buses equip with GPS and mobile phones. Call into a central system to report their present location. The bus stands will get LED displays controlled by a microprocessor which can also communicate by phone. The solution of communicating by phone was chosen The central system knows the geography of the routes of all buses, the typical travel speed.

3. Requirements A high-level specification of the sytem Give a briefing to the issue and aspects that may be of importance for this.

4. Illustration

5. Central System Mobilphone network Auto phone call INTERFACE System control Bus speed calc Route map calc Position calc INTERFACE Data process Bus Speed Bus Stand Route Map BUS with GPS BUS stand with LED

6. UML

7. Components Central System Bus Bus Stand

8. Modules of Bus GPS ReceiverBus Position Sender Bus Position Report

9. GPS Receiver Contains GPS control system. Receives bus position from GPS system Exposes an interface which provides current bus position to the Bus Position Report module. – GetPosition : POSITION

10. Bus Position Sender Contains mobile phone communication system. Provides Wireless Data Link to the bus. Exposes an interface to Bus Position Report module. – SendPosition : POSITION Receives position data and sends data to the Central System.

11. Bus Position Report Reports current bus position to Central System periodically. There is a timer in the module. When the timer is triggered, the module requests the current bus position from GPS Receiver module and sends this position to Central System through Position Sender module. Timer --> SendPosition (GetPosition)

12. Modules of Bus Stand Bus Distance Receiver Bus Distance Display LED Display

13. Bus Distance Receiver Contains mobile phone communication system. Provides Wireless Data Link to the bus stand. Receives bus distance from Central System. Calls Bus Distance Display module to show distance data when new data are received. – ShowDistance : DISTANCE

14. Bus Distance Display Shows bus distance data thought LED Display module. – LEDShow (LED) Converts bus distance data to LED display data. – DISTANCE -> LED Exposes an interface to Bus Distance Receiver module. – ShowDistance : DISTANCE Converts DISTANCE to LED and shows it.

15. LED Display Shows the distance of the arriving buses on the LED display. Contains a LED display control system in the module. Exposes an interface which accepts bus distance data with type LED and shows the distance. – LEDShow : LED

16. Modules of Central System Bus Position Trace Route Map Bus Distance Broadcast Bus Distance Forecast Bus Distance Sender Bus Position Receiver

17. Contains Mobile Phone Communication system. Provides Wireless Data Link to the Central System. Receives bus positions for buses. Calls Bus Position Trace module when new position data arrives. – UpdatePosition position

18. Bus Distance Sender Contains Mobile Phone Communication system. Provides Wireless Data Link to the Central System. Sends bus distance data to bus stands. Exposes an interface to Bus Distance Broadcast module. – SendDistance : DISTANCE Accepts DISTANCE data and sends it to bus stands.

19. Bus Position Trace Manages position information of all buses dynamically Two interfaces: – UpdatePosition : POSITION Updates a bus position. – GetPosition : POSITION Get a bus position from the trace.

20. Bus Distance Broadcast Broadcasts bus distance data to all bus stands periodically. Manages a bus stands list. – AllStands : STAND There is timer in the module. When timer is triggered, it calculates all bus distance data and sends them to all bus stands. Timer --> for each stand in AllStands distance = Forecast stand SendDistance distance

21. Bus Distance Forecast Forecasts how much time it takes from a bus to a bus stands according to a typical bus speed and the route. The module can query bus position from Bus Position Trace module and query route map from Route Map module. Interface: – Forecast : STAND -> DISTANCE

22. Route Map Contains all information of bus routes and bus stands. Provides some interfaces for Bus Distance Forecast module to query data of bus routes and bus stands.

23. Discuss Requirements Accuracy Time intervals buses send GPS position Time intervals server update the bus-stands Accuracy versus time overhead.