Interesting findings about WCDMA Cell ID

Posted by Alex Zaah filed under Others

I have lately received quite a few feedbacks about my GSM tracker. In case you have not used it before, here is the link. I myself rarely use it these days since it does not have much to do with my job, but I used to learn about everything related in the days when Symbian phones were very popular all over the world and here are two interesting findings I discovered a few years back.

As you may know, 4G network is already very popular in developed nations like US and Western Europe. We here is also switching to LTE networks although 3G is not universally deployed. But 2G is the absolute mainstream when Nokia phone is dominating the market, and I still recall the  network apps I used, fieldtest, CellTrack91 etc.

When I first used a 3G card in my Samsung I550W phone, I found that the Cell ID I got from fieldtest 10.09 (118960471) is quite different from the drive test (12631). In fact Nokia introduced certificate system into Symbian S60V3 and many software for S60V2 stopped working and I had to make a few changes to make it work again. So first I think maybe there’s something wrong with the app.

However I changed my mind later when I discussed it with some people I met on the forum. According to him, in 2G mode the value I got is Cell ID, but in UMTS mode the value is actually another parameter and you need to perform a mod transfer to get the real Cell ID.

Since the Cell ID value ranges from 0 to 65536, you can use below formula

Cell ID = mod(118960471,65536)

Open up excel and use above formula you will get 12631. By the way, RNC id=int
(118960471/65536).

Another difference between 2G and 3G, to the best of my knowledge, at least here is that we use 4-digit Cell ID in 2G cell sites, and 7-digit Cell ID in 3G base stations. So sometimes you could not find the GPS coordinates of certain Cell IDs obtained from some app. In my case it’s CellTrack91.

For example, I once used CellTrack91 to test one cell towers and got the Cell ID 10796, but I just could not find the latitude and longitude. Then I tried another app and got 190130732. As you may know apps always turn hex into decimal, so we need to reverse engineer it, haha.

10796        ->2A2C
190130732 ->B552A2C

It became quite obvious to me that the first 3 digits were omitted for whatever reason. If you try 190130732, my GSM tracker works perfect. If you are experiencing the same issue, these two findings might help.

The mobile industry and technology is advancing quickly, we all need to learn to keep up with the new developments, so are the apps. What about you? Let me know your thoughts or opinions on Facebook or Google Plus. I just do not have the time to go through the numerous spam comments to find the really useful and inspiring points left by visitors like you, sorry.

Posted by Alex Zaah | Category: Others | Tags:

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