Hi rajngupt,
I recommend you to flash BIOS to the latest and update the wireless driver from the links given below:
BIOS: http://dell.to/16vDv8T
Wireless: http://dell.to/13REFcd
Note: While flashing BIOS connect the Ac adapter and make sure the battery has minimum 15% charge as this needs uninterrupted power supply. Do not use the system till it restarts and comes up to the desktop. In case the system has latest BIOS, you may ignore flashing it. However update the wireless driver. The link provided is for Windows 8 Operating system.
Next, I request you to change the roaming aggressiveness to maximum, wireless channels in the ‘advanced card properties’ to 11 or 6 and Disable Bluetooth Collaboration.
You may also go through this link for reference:
http://intel.ly/GvTz2
Revert for further queries.
