Wireless/radio Interface/gsm Modem Help

[crushboy18]

i have to make this project called "city bus information system".
on the display in the bus all the info regarding the next stop,last stop,exp in mins information is to displayed,and same can be done on the bus stop.

for this i need to make a radio link between the bus and the stop...wht link should i use...i want to use a radio link...any suitable frequency.

the bus stop will relay the information to the bus...and the display in the bus will display it.
any help regarding the circuit is also appreciated.

secondly i am planning to connect the bus stop to a central server..and i think a gsm/cdma link between the bus stop and the central relay station will be good.so the central server could be updated with all the info from all bus stops.through sms service.

all calculations done here(relay stn) it can send the required info back to the bus stop which relays to the bus.

the proj is still in nascent stage,so any other suggestions would be helpful.

 

[98formulaLS1]

i designed a system exactly like this for my last company.

First, lets discuss the central side.
The central side will include a server that has a connection to the GPRS network. The server will perform the calculations determining the next stops and time until arrival. The server will transmit this info onto the GPRS network, being received by the Vehicle Display and Wayside display (bus stop)

The vehicle display should make a wireless connection to the GPRS network and a wired connection to a GPS receiver. The vehicle should transmit its location data every 10-60 seconds (depending on the system load) to the central side. The central side will process the data, and transmit display information back to the vehicle.

The wayside display should also make a connection to the GPRS network, but no need for a GPS interface, as the wayside will be at a known fixed location. The display need not transmit any information maybe except a status message or error messages. The display will receive information from the central side based on the calculations made from the vehicle info.

Any questions?

 

[98formulaLS1]

timing calculations should include GPRS network relay time, server processing time, and vehicle transmit periods.

Also, you may want to calculate an algorithm that predicts arrival time during periods when the vehicle may be out of network coverage, and in-between vehicle transmitting periods.

 

[crushboy18]

Thankyou So Much...

I Guess The Software At The Central Server Would Be A Lil Complicated +the Algorithm Too...