extending/repeating a wireless signal.

See attachment picture for a visual reference.

I have a Base Station or router (Point A in picture). Then i have computers B and C which I want to be connected to the router (and hence the network). But as you can see from the picture computer C is out of range of the router. However computer B is in range of the router and in range of computer C. So I'm curious if its possible to set up a computer as a repeater, but not just a repeater.

Ideally i would want the computer to be able to receive information intended for that machine and then repeat or "pass on" the information that isn't meant for that computer.

The "computers" will be custom built by my friend, (they'll be more like small embedded systems running Linux), so i guess another question is, what would it require (hardware and software wise?)?. Two WiFi controllers (eg: apmcomm–Wireless, GPS, Bluetooth, WiFi, WLan, IPD, SiP, Combo, modules, Wimax, RF, TMC, RDS-TMC) ? From what I've read it would need certain/modified firmware...

Any comments, good readings?

Thanks

no body?

You mean things like
linux connection sharing - Google Search

linux port forwarding - Google Search

It depends on your constraints: are any of the nodes at fixed locations? If so, you might consider using higher gain (directional) antennas. You can pick up such things at electronics stores or even make one yourself from basic materials (the physics involved are pretty simple). That can reduce or eliminate the need for hopping, with the trade-off that you can't walk around as much with portable devices.

However, assuming you really need to a multihop network, the basic need is for the middle node to be a router (doing port forwarding). If the end nodes are on the same network (eg in the same 802.11 channel established by the middle guy) there is a greater trade-off of throughput.

You can also look at various dynamic self-healing networks, particularly if all of the nodes are mobile.

Ok, lets see if I understood.
- Port forwarding: I can set up a system to forward all information incoming on a certain port to a certain machine on the network.
- Internet connection sharing: (from wikipedia) takes IP addresses of computers on the LAN and maps them to unused ports for access to the internet...

Im not sure if these will work... The computers on the LAN will not be connected to the internet. The base station will be connected to a router, and it will send data to the different terminals/nodes/computers on the LAN But the majority wont be in range of the router, and the nodes will be constantly changing locations, going in and out of range of the router... So potentially a packet would need to go from node a to b to c to d to e, but 10 minutes later to go from a to e it would need to go from a to c to d to b to e, and then 10 minutes later it might just need to go from a to e... Would ICS or port forwarding work for this situation?

You should lookup 802.11 wireless roaming.

Jim

while i was reading about wireless roaming one of the articles i read showed how you could use a router as an access point, turning off DHCP and connecting the main router to one of the lan ports on the back of the AP using an ethernet cable. Can this be done without the ethernet cable?

EDIT: I did some more reading and a "mobile ad hoc network" might be exactly what i need :)
http://en.wikipedia.org/wiki/Mobile_ad_hoc_network