Example
Suppose you have a WiFi-capable game console. This device needs to send one packet to a WAN host, and get one packet in reply.
Network 1: A wireless base station acting as a simple (non-WDS) wireless router. The packet leaves the game console, goes over the air to the router, which then transmits it across the WAN. One packet comes back, through the router, which transmits it wirelessly to the game console. Total packets sent over the air: 2.
Network 2: Two wireless base stations employing WDS: WAN connects to the master base station, that connects over the air to the remote base station, which talks over the air to the game console. The game console sends one packet over the air to the remote, which forwards it over the air to the master, which sends it to the WAN. Reply comes from the WAN to the master base station, over the air to the remote, and then over the air again to the game console. Total packets sent over the air: 4.
Network 3: Two wireless base stations employing WDS, but this time the game console connects by Ethernet cable to the remote base station. One packet goes from the game console over cable to the remote, from there by air to the master, and on to the WAN. Reply comes from WAN to master, over air to remote, over cable to game console. Total packets sent over the air: 2.
Notice that network 1 (non-WDS) and network 3 (WDS) send the same number of packets over the air. The only slowdown is the potential halving due to the half-duplex nature of wifi.
But network 2 gets an additional halving because the remote base station uses double the air time because it's retransmitting over air packets that it just received over the air. That's the halving that's usually attributed to WDS, but that halving only happens when the route through a base station uses-over-the air links on both sides of it. That does not always happen in a WDS, and can happen in non-WDS.
Important Note: This "double hop" (one wireless hop from the main station to the remote station, and a second hop from the remote station to the wireless client ) is not necessarily twice as slow. End to end latency introduced here is in the "store and forward" delay associated with the remote station forwarding packets. In order to accurately identify the true latency contribution of relaying through a wireless remote station vs. simply increasing the broadcast power of the main station, more comprehensive tests specific to the environment would be required.
Read more about this topic: Wireless Distribution System
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