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New Member

2.4 GHz 4 channel (1, 5, 9, 13) plan on 5508 WLC

Hi,

Has anyone successfully deployed a 4 channel (1, 5, 9, 13) none-overlapping plan in the UK?

Cheers,

Jason

6 REPLIES
Hall of Fame Super Gold

2.4 GHz 4 channel (1, 5, 9, 13) plan on 5508 WLC

No because it won't work.  You're breaking the "rules" in radio engineering.

New Member

2.4 GHz 4 channel (1, 5, 9, 13) plan on 5508 WLC

Hi Leolaohoo,

Thanks for the reply, I've been doing a bit of digging could you comment on the below please an exert from :

http://www.ja.net/documents/publications/factsheets/063-overlapping-channel-problem.pdf

In the UK, the area of the wireless spectrum set aside for the use of 802.11b/g wireless networking

devices is the ISM (Industrial, Scientific and Medical) band between 2.400 GHz and 2.497 GHz. In

the UK this is subdivided into 13 channels of 25 MHz. In the US, only the first 11 of these channels

are available – a fact with implications for UK deployments (see ‘WAG’s Advice’ below).

However, this description can give a misleading picture. Radio signals are not tightly confined to

a single point in the spectrum but are distributed symmetrically around a ‘mid’ frequency. This will

be familiar from the experience of tuning a radio, where the signal gradually gets stronger as you

turn the dial before hitting the peak frequency and then slowly dies away again. In fact, the width of

spectrum across which the signal is distributed is related to the bandwidth (in the networking sense)

of the data being transmitted and the symbol rate used to encode it (this relationship is discussed

in Nyquist/Shannon sampling theory). 802.11b, with a bandwidth of 11Mbit/s and a binary symbol

system, requires 22MHz per channel (802.11g achieves its greater data rate in the same channel

width by increasing the bits carried per symbol). So, a better picture of the channels in the 2.4

GHz spectrum is given by the following (the four differently shaded, solid curves indicate signals

associated with the four non-overlapping channels: 1, 5, 9 and 13):

Also why would Cisco publish :

Wireless LAN Design Guide for High Density Client Environments in Higher Education

Jim Florwick

Jim Whiteaker

Alan Cuellar Amrod

Jake Woodhams

Design Guide

November, 2011

Note:

Before considering a four-channel plan in 2.4 GHz, see

Channel Deployment Issues for 2.4-GHz 802.11WLANs

If the WLAN is located in a regulatory domain where the bandwidth to deploy four channels is

available (e.g., availability of channel 13 and 14) unless the WLAN is sufficiently isolated from every other network

it is likely that someone will deploy using the standard 1, 6, 11 model and drastically increase the interference to

the WLAN.

Hall of Fame Super Gold

2.4 GHz 4 channel (1, 5, 9, 13) plan on 5508 WLC

Maybe my response was a bit hasty but I have NOT yet seen someone implement this sort.  It's mostly 1, 6 and 11.  

Silver

2.4 GHz 4 channel (1, 5, 9, 13) plan on 5508 WLC

Jason while this can be done in the UK seen as you have the ability to use the additional channels you want to be careful when doing so. If you deploy a 4 channel plan and someone introduces a 3 channel plan there will be a lot of interference. One would have to do a proper RF survey to validate that there are no 3 channel plans in use presently.

Silver

2.4 GHz 4 channel (1, 5, 9, 13) plan on 5508 WLC

I know of a university that last I checked was running 1,4,8,11 plan

Hall of Fame Super Silver

Re: 2.4 GHz 4 channel (1, 5, 9, 13) plan on 5508 WLC

Well I would think it would be okay if, like what others mentioned, there are no other wireless around the area and if you have only one floor. With multiple floor I would think that would make it difficult because of signal bleed from adjacent floors. I still would go with the majority and stick with using 1, 6, and 11. But that's me:)

Sent from Cisco Technical Support iPhone App

-Scott
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