2.4GHz WiFi channel selection when all the non-overlapping channels are crowded

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For 2.4GHz wifi, if the non-overlapping 1-6-11 channels all fully crowded by neighbors, should I select from the other overlapping channels (2,3,4,7.. etc.) or even so select the least crowded from 1-6-11?

Note: I have no option for upgrading to 5GHz for now.

Best Answer

It is suggested to select form the least crowded of the 1-6-11 Source (Here)
If you go with anything else, you can seriously reduce overall bandwidth.

Does your Wireless Router not have that the option of auto channel select?

(Summary of the Link Provided)

Test Results

Cisco performed tests to see the interference in a four-channel environment. The tests were conducted with four Cisco Aironet 1200 access points and four Cisco Aironet 350 clients, all running 802.11b at 11 Mbps. To help simulate the physical separation between devices, the access points and clients were set at 5-mW transmit power and spaced about 10 feet apart.

The throughput was measured by the average of all four clients simultaneously passing a 50-MB file five times. In all combined tests there was one client to each of the four access points. In the stand-alone test for benchmark comparisons, all four access points and all four clients were on. However, only one client was in the process of sending a 50-MB file using FTP.

Testing included two different scenarios:

  1. Four North American access points, two using channel 1, the third using channel 6, and the fourth using channel 11

Note In this model, the first two access points had to share the RF because they were on the same channel.

  1. Four North American access points using channels 1, 4, 8, and 11

Table 1 displays the results of the two tests. Note that even when two access points shared channel 1, the overall performance was greater than in the four-channel scenario. This is because the CSMA protocol created a holdoff when the clients on the same channel decoded that the interference was another 802.11 signal. In the four-channel scenario, the client could not decode the interfering signal, reacted as if it was low-level noise rather than a holdoff, and sent the packet. This resulted in a collision and a retransmission on both clients.

Table 1 Result Summary Showing Average Throughput per Client

Channels / Throughput (KB)
1, 1, 6, and 11 / 601.1
1, 4, 8, and 11 / 348.9

Conclusion

Many have long recommended a three-channel approach to provide nonoverlapping channels. We still recommend such installations for 2.4-GHz WLANs, for both 802.11b and 802.11g technologies. A four-channel scheme can cause severe issues when the system is brought online and the number of users starts to increase.

In a four-channel design, the signal of one device is noise to another device. Even in a design where a channel 1 cell would never overlap a channel 4 cell, for example, you must still account for clients transmitting that are not in the same location as the access point. By looking at only the access points, you are ignoring the majority of radios in your network. Virtually all new radio deployments support 802.11g and/or 802.11a and thus OFDM, which has much more sideband energy than 802.11b.

If you design a system with four channels, the risk of interference between cells greatly increases, resulting in poor performance and lower throughput. As the volume of users and bandwidth needs increase, problems will slowly arise, making it necessary to resolve the issue at a later date. Start by using three nonoverlapping, noninterfering channels.