The use of short range wireless standards has increased today. But the wireless standards used in the environment are not very efficient in the areas of power consumption, survivability, dynamic information technology capabilities and energy efficiency. ZigBee, WLAN and Bluetooth play a very important role in wireless communication. But on the other hand the throughput of these three technologies decreases due to the fact that they co-exist in the frequency band of 2.4GHz. This paper will show the comparative study of ZigBee, WLAN and Bluetooth and also the method to improve the throughput using power control technique using NS-2.