...If the router won't send the signal to the third floor, can one purchase some kind of booster to place on the second floor to help boost the signal if that is necessary?
Hi. It is possible to increase coverage using a device called a 'wireless repeater', or by using additional wireless routers configured as wireless repeaters (provided these additional routers support this feature).
With regards to software, no additional software is required to set up a home network.
As pointed out by koinonas, wireless may not be the best option here, considering that the modem is in the basement, and that there are several floors to cover. If you choose to go the wireless route, be sure to purchase and use good wireless routers / repeaters with powerful external antennas, to ensure the best coverage. Also, I'd suggest using ones where the external antenna(s) can be detached, in case you need to purchase and use a larger omni-directional / directional antenna for a better signal.
Still, an option providing better performance and coverage might be to use a wired solution. You could use a wired router in your basement, and run Ethernet to the other floors with additional switches. You could also establish a powerline Ethernet network where data is transmitted through your home's power sockets. It may however be more costly than a wireless solution, as powerline solutions are rather relatively expensive, and running Ethernet cabling properly through the home incurs further cost.
Of course, you don't have to use an all wireless or all wired solution. For example, you could connect a wired router to your modem in your basement, then place a wireless access point on the ground floor (which is wired using Ethernet to the wired router in the basement), then use additional wireless repeaters on further floor where necessary.
Here's an example of a possible solution:
Provided that a wireless signal can penetrate the basement ceiling, the wired router in the basement could be replaced with a wireless router, and wireless repeaters (or wireless access points configured as wireless repeaters) could be placed on additional floors to expand coverage, where necessary – thus providing you with an all wireless home network. Note however that network latency (delay) can increase for each computer connected to every additional wireless repeater added (as the signal is relayed between each repeater, from source to destination). This isn't a problem for most applications, but if low latency is key, then consider a wired network instead.
