Bandwidth is the amount of information that can be transmitted along a certain signal or wire during a given time. Wireless bandwidth is affected greatly by the signal strength of the wireless router to you computer. Boosting the wireless signal from your router to where you use your computer will improve bandwidth and transfer speed.
Move your wireless router to a centralized location. If at all possible, try to place your wireless router in the middle of your house or office. If the router is on one side of the building the signal on the other side will be weak, meaning less bandwidth.
Eliminate signal blockers. Keep your wireless router well away from cordless phones, baby monitors, metal file cabinets, walls, and even the floor. Choose a cordless phone or other signal broadcasting equipment that operates on a frequency other than 2.4GHz.
Replace your wireless router's antenna. Some routers do not have an external antenna, but if yours does chances are the antenna is designed to broadcast at 360 degrees. If you use your computer in generally only one direction from the wireless router, install a "hi-gain" antenna that broadcasts the wireless signal in only one direction. The signal from the router will be stronger, increasing bandwidth.
Use a wireless repeater. Wireless repeaters can be purchased at a number of retail and online outlets. Place the wireless repeater in another part of your house where the signal is low to boost the wireless bandwidth for your computer.
Use the same brand wireless router and modem. Hardware manufacturers design their hardware to work best with each other. Even though different brands work together, switching to just one brand can actually increase bandwidth.