Almost all devices transmit at the maximum legal power so you cannot increase the signal level. Some walls completely block wireless, my brother has a wall designed to block sound and it also blocks all wireless signals.
You could try a directional antenna to concentrate your legal signal level and try to blast it though the wall but in some cases it will make little difference.
You can completely ignore any wireless "boosters" since they are either illegal or just amplify the interference along with the signal. Wireless repeaters if you can place them correctly can work, in your case can you actually place this device so it can see both your router and your pc with no wall in between. These tend to be hard to setup because you now have 2 wireless signals to deal with so you now have twice the chance to get interference.
The best way to do this is to find a way to get a cable of some kind between the rooms. Ethernet is of course the best but there are systems that will run over the power lines or over the coax used for cable tv.
What is the easiest way to boost the the signal from a wireless router(1 year old), weak signal going into a different room. Yes has to go around a wall into another room.
What is the easiest way to boost it!