Tips to improve the Wireless Range.
How Can the Range of a WiFi Network Be Boosted? The wireless signal strength depends on many variables. Like the position of the Router / Access Point, interfering devices, thickness of the walls, the adapter/receiver on the computers. We will discuss some factors that will help boost the wireless range and performance.
The router should not be placed in an isolated part of the house. The router should not be placed near a Television set or any other electronic devise. Avoid placing the router in a cupboard or behind any thing. If the wireless router is against an outside wall of the house , the signal will be weak on the other side of your home. Common sources of interference in residences include brick or plaster walls, microwave ovens, and cordless phones. But there are many other ways to boost the signal of the wireless network. Try keeping the Access Point / Router elevated from the floor and away from any electronic device. Open the Setup page of the Router [the default IP Address is 192.168.1.1] and change the Wireless Channel. Try different combinations to best optimse the 
coverage. For N-Series devices, keep the Radio Band to 40 MHz Channel, Wide Channel to 9 and Standard Channel to 11-2.462 GHz. If you are using a N-Series Access point / Router, also use a N-Series adaptgers to enjoy the N-Series Connectivity. If you place the router is a central position of the house, the wireless range will be covered in the entire house [ofcourse depends on the size of the house] all the devices will be able to connect wireless without any hassel. The N-Series provides a maximum speed of 270MBPS. You can also replace the wireless antennas on the router to boost the range. Like high gain antennas. Or adjust the position of the antenna on the router or the computers to get better reception. Try using a Range Expander to extend the wireless signal. Keep the firmware on the router and the drivers on the adapter updated.
