Why Wireless Internet is Slower than Wired?

There’s nothing like the untethered freedom of wireless internet. Having the flexibility to get online from a variety of locations is a beautiful thing. But why is it that you seem to always be sacrificing speed for the sake of mobility? What is it about wireless internet that slows you down? The following are 10 reasons why wireless internet is slower that wired:

1. Firstly, wireless signals are subject to interference from physical obstructions like walls, metal objects, etc. This will decrease signal strength and, therefore, overall performance.
2. Electrical noise when transmitting through the air will also adversely affect wireless performance.
3. Because wireless is usually being transmitted via an omnidirectional antenna, much of the signal is lost to the wireless device, which is receiving only a fraction of the available signal.
4. Routers typically run at 54Mbps. Broadband wired internet speed on ethernet can be 100Mbps. So the capacity of the wired connection may exceed that of your wireless router, even if it’s connected to the same broadband source.
5. This can also be a function of the wireless standard that you’re using. 802.11n, for instance, is capable of 300 Mbps speed, while 802.11g speeds are in the aforementioned 54 Mbps range.
6. Proximity to the router will affect speed. The further you are from the source, the slower your speeds.
7. Your wireless device is sharing the available bandwidth with all other devices on that wireless network. Think of it on terms of water pressure,and trying to run a bath while the kitchen sink and the clothes washer are both running.
8. Positioning of the antenna can affect the wireless signal.
9. Speed differences between wireless and wired are going to be most significant when transferring files between devices on the same network.
10. Wireless encryption, a security necessity when transmitting through the air, also slows down the signal.

Although any wireless router is rated for speeds in excess of most broadband speed, the nature of wireless transmission makes it susceptible to conditions that can adversely affect performance.

source here