Symptoms
http://www.intel.com/content/dam/www/public/us/en/documents/pdf/next-gen-80211ac-wifi-for-dummies.pdf
The above link and table are from an Intel article on 802.11ac. Intel is the vendor of the common Intel 7260 802.11ac wireless adapter. These are the maximum possible connection speeds of various devices on a wireless network,
not the actual TCP throughput. The Signal to Noise ratio (SNR) and distance from the AP, as well as other factors will lower the TCP throughput of a client from the maximum possible connection speed.
The generally accepted industry standard for determining the TCP throughput of a client is the connected speed of a client divided by 2, and then divided by the number of clients sharing the bandwidth of the AP. This is because wireless networks have overhead that Ethernet networks don't need, such as control and management traffic, and because the medium is not dedicated to individual clients but rather shared between all of them, similar to a hub. All stations must listen to each other’s management and control traffic to determine when it is their turn to send or receive. In addition, wireless is half-duplex, meaning the device cannot send and receive simultaneously.
Taking the table above and dividing the connected speeds by 2, we then get this TCP throughput for each type of client. This would be a
rough estimate of the
maximum possible TCP throughput of a single client on a pristine wireless network.
Cause
This rough estimate of the maximum possible TCP throughput of various clients when in a pristine environment does not take into account other factors found in real world scenarios, factors such as environmental conditions, RF interference, building materials, weather, or the number of clients on the network, as well as many others. The above TCP throughput rates will go down as environmental factors and other clients are added to the equation.
Resolution
Summary: In the real world, depending on a wide number of factors, actual TCP throughput will be much less than the connected data rate, and will vary widely, from client to client, AP to AP, building to building, and even from moment to moment.
Affected Products
Wireless Networking