i need to investigate some solutions for a true mobile wireless networks and im looking for anyones input.

the situation is as follows, i need to design a network that will supporting IP traffic on a public bus transport system. wireless terminals on each bus will communicate through a router onboard each bus (ie each bus is a mobile wireless lan) at the bus depot there is a gateway for internet and telephony. the range of each lan on each bus is limited to no more than 3km and there is no more than 10 busses within the network.

what are some considerations for the planning, design and architecture of such a network?