Throughput is Halved by WDS in Repeater Mode

Wireless Distributed System (WDS) is a system that makes the interconnection of Access Points by supporting wireless cascading. Before the introduction of it, there was no way to connect two Access Points with wireless. As we can see, this new technology limited the size of a WLAN. So we can say this feature helped a lot to migrate offices from using traditional Ethernet cable based LAN to IEEE802.11 networks. WDS is necessary to interconnect two wireless networks (IEEE 802.11 standard) and the working of Wireless Range Expander is based on it. This article tells the advantages and drawbacks of WDS including how throughput is halved by each retransmission.

Advantages of WDS
  1. Preserve client MAC Address in Wireless frames

  2. Wireless Cascading of two routers is possible with WDS

Wireless Distributed System enables cascading of two WiFi devices and makes WLAN easily. If one device does not support WDS, it cannot offer WiFi cascading feature. So this feature is the major player in Interconnecting two IEEE802.11 networks.

WDS works in Two modes:
  1. WiFi Bridging

  2. WiFi Repeater

Drawbacks of Wireless Distributed System
  1. Throughput will be halved

    If we use WDS in repeater mode, by every retransmission, throughput may be halved. This process is explained below.

    • PC-1 connected to Access Point 1 using Ethernet cable send data

    • Access Point 2 received the signal and send data to PC-2 connected by Ethernet cable

    • Here throughput is not halved because there is no retransmission. Here WDS doesn't act as repeater

    Now let us check another scenario where PC-1 is connected to AP1 by Ethernet cable. A WiFi laptop is connected to AP2.

    • PC-1 sends data through AP1

    • AP2 receives the signal and retransmit it to laptop with WiFi adapter

    • Laptop receives the data but throughput is halved

    Here throughput is halved because there is one retransmission. Now let us consider another scenario where both PCs are connected to respective APs via WiFi.

    • PC-1 sends data to AP1 (same throughput)

    • AP-1 retransmit data to AP-2 (half of the actual throughput)

    • AP-2 retransmit data to PC-2 (one by fourth of actual throughput)

  2. Dynamic Encryption may not work

    Another issue with Interconnecting two WiFi networks is the difficulty to implement tight security. Wireless Distribution System doers not support Dynamic Wireless Encryption. WPA and WPA2 (except WPA pre-shared key )are not supported by WDS while bridging two WiFi networks. It supports WEP only and no dynamic key exchange security encryption works with it. It really makes WiFi network by WDS less secure in the eyes of security specialists. To read more about the importance of using Dynamic Encryption over static encryption, click on the link below.
    Choosing Between WEP and WPA

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