Question about cell tower numbering

[Jay2TheRescue]

I'm going to quote a post I made in the gallery earlier today, but I feel it will get more exposure here so I'll recopy it and elaborate further...

Gallery post - http://gallery.wirelessadvisor.com/s...s&cutoffdate=1

On My Motorola V551 I do this:
Settings> Engineering> Cell Management> Cell Sticker> Target ARFCN: 0635

The Cell Sticker tells the phone to maintian connection with a particular tower until there is no signal left. In my case I use it to prevent my phone from jumping to the Orange network (my home network), which has a weaker signal at work. I got the number from entering Field Test mode, and seeing what tower was strongest in my store. I don't know what ARFCN means, whether it is a channel number, or a cell numer. I just know it works. I would think that the numbers would have to be re-used though as it is only a 4-digit number, and there are more than 9,999 towers on the network nationwide. Even at that the numbers seem to be specific (at least locally) Cingular Orange always seems to be 01xx, Cingular Blue is 06xx, and T-Mobile is 07xx. If anyone else knows more about this please post it.

What exactly is the ARFCN#? Actually, if someone knew what the letters stood for I think it would be self-explanatory.

[bobolito]

ARFCN = Absolute RF Channel Number
That's the control channel number.

[Jay2TheRescue]

Thanks for the quick reply, is that assigned to a particular tower, or can a tower's number change on a regular basis?

[pbw]

Originally Posted by Jay2TheRescue

Thanks for the quick reply, is that assigned to a particular tower, or can a tower's number change on a regular basis?

YEah. This one I can answer. Especially since Bob got the ARFCN thing. Anyway channel numbers are not unique, they will repeater but there is a certain area of seperation. Normally, I have not seen the control channel change unless the carrier moves a site out of its current LAC and into another LAC. If the carrier changes a cell LAC then the control channels and BSIC values also change. Annoying when you collect data from carriers like T-Mobile who seem to change the LAC of all sites every six months.

[hillbilly44]

Originally Posted by pbw

YEah. This one I can answer. Especially since Bob got the ARFCN thing. Anyway channel numbers are not unique, they will repeater but there is a certain area of seperation. Normally, I have not seen the control channel change unless the carrier moves a site out of its current LAC and into another LAC. If the carrier changes a cell LAC then the control channels and BSIC values also change. Annoying when you collect data from carriers like T-Mobile who seem to change the LAC of all sites every six months.

The control channel doesn't always change when the LAC (location area code) changes. It usually stays the same unless they are also doing a retune. A LAC change is due to a cell site being "rehomed" to a new BSC so if a cell is placed on a new LAC that means that the network is growing or caring more traffic.

[pbw]

Originally Posted by hillbilly44

The control channel doesn't always change when the LAC (location area code) changes. It usually stays the same unless they are also doing a retune. A LAC change is due to a cell site being "rehomed" to a new BSC so if a cell is placed on a new LAC that means that the network is growing or caring more traffic.

Word up! I should have prefixed my statements with "not an engineer". All I know is that when VoiceStream went from a lot of small sized LACs to a handful of large LACs they changed all of the control channels and BSICs at each site. I guess this was coincidental? I had seen Triton PCS do the same thing (only their LAC changes are not so frequent). Also why does VoiceStream not reuse LAC numbers but other carriers do?

[hillbilly44]

pbw;

The reason for large LACs is the scalibility of the newer BSC (Base station controllers). They can handle more cell sites than the older models so the LAC boundries are larger. As far as changing BSICs and control channels I don't have a clue why they do that with a rehome. The LAC numbering probably has to do with the BSC configurations.

[ShoresGuy]

What is a SID? Is this the Switch ID?

[Charlyee]

Here is some addiional info:

ARFCN for 850/900 GSM, 1-124.

for 1800 GSM, 512-885

for 1900 GSM, 512-810

[kashkanantambu]

A SID is the acronym for System Idendification It is a five digit number that indicates what area a phone is in.

[club333]

I live in South Jersey. Is there a web site that shows the Cingular cell towers with their numbers ? For example, where is Cingular Cell Tower #000000 located ?

[hillbilly44]

Originally Posted by kashkanantambu

A SID is the acronym for System Idendification It is a five digit number that indicates what area a phone is in.

Actually in a GSM network you use NMC for System Identification. SID is used with TDMA or CDMA networks. Also the LAC (location area code) shows where you are in the network (plus allows you access to it) and is assigned to a BSC (Base Station Controller). The channel you are seeing is for the sector (in idle mode) but in a GSM network you frequency hop so the actual channel will change while you are on a phone call.

[ShoresGuy]

Ok so will this channel change only apply to either GSM 900 or GSM 1800 and GSM 850 or GSM 1900 meaning that the change will occur within one band only if the provider uses GSM 900/1800 or GSM 850/1900. Furthermore, does this also lend creedence (credibility) to the debated topic of whether a handoff occurs between bands or between different network standards (GSM to UMTS handoff and vice-versa)?