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Introduction
In this article, I’ll show you how to map telco coverage & cell towers using CellMapper (CM) app. Note that this guide is more intended towards Malaysians as it has some Malaysia-specific terms.
What is CellMapper?
CellMapper exists primarily because most telcos around the world didn’t provide any public data of their tower locations!
From CellMapper’s website, CellMapper is a useful app for locating 2G/3G/4G base stations. The application measures the signal strength and other network data collected by end users and uses the data collected to locate network base stations and their coverage.
Data inside CellMapper map is crowdsourced, so your location may or may not have sufficient data for the particular telco.
CellMapper is supported by ads in their website and apps. Premium membership is available as I explain below.
Download the app
There is also version for Windows 10 Mobile, but I didn’t cover it here.
If you are in 5G area & have 5G phone & 5G-enabled plan, you are encouraged to join CellMapper beta in Play Store as it has numerous fixes for better 5G NSA detection & mapping.
How to set up the app for first time?
When you open the app for the first time (or wiped data for the app) on your phone, allow all the requested permission. If you’re on Android 11 and newer, location permission must be set to “Allow all the time” & (Android 12++) enable precise location.
Steps below should be similar across many Android skins.
Then exit the app by opening the side menu (≡) then press exit. Open the app again and it should prompt you to disable battery optimizations for CellMapper. This varies by OEM and Android software/skin used.
The websites above publishes detailed instructions on how to disable battery optimisations. Use it for CellMapper app.
Battery optimisation needs to be disabled so that CellMapper can collect data properly without the Android system throttling the app.
Enable “Force full GNSS measurement” (optional)
“Force full GNSS measurement” can be found in Developer Options which is hidden by default. You can search on how to enable Developer options menu as it varies between OEM & software used.
This option helps in increasing GPS accuracy which in turn helps for better data collection in CellMapper app.
Note that some apps might won’t play nice with developer options enabled.
Reduce amount of bad/useless data from being uploaded to CellMapper servers
For phones with Mediatek & Exynos chipsets you need to disable 2G & 3G recording in CellMapper’s settings as the phone spits out wrong signal reading to 3rd party apps. Samsung’s ServiceMode menu shows correct info.
I also strongly encourage you to disable 3G mapping in CellMapper settings (doesn’t matter what SoC your phone has) as 3G services in Malaysia isn’t guaranteed after 31 December 2021. As of writing this article there are still some places throughout the country that still have 3G services which will eventually being turned off.
To do so, open side menu (≡) then tap on Settings. Under Advanced Settings, untick Record 2G data and/or Record 3G data.
How do I create an account (optional)?
Creating an account can be done either through the app or the website (cellmapper.net). Benefits of having an account:
- Ability to modify towers (move/delete) upon reaching 50000 points
- Keep tally of contributed data
- Create/modify/delete wiki related to the tower
You also can subscribe to premium membership for 3 CAD/month (~RM10/month) via PayPal. Benefits are:
- Star next to your username (in tower BTS/NB/eNB/gNB details)
- Dedicated server for premium users (faster data processing)
- Search tower by Cell ID (hidden for non-premium users)
- Ad-free app & website
- Supporting CellMapper devs
If you don’t want to get premium subscription, it is highly encouraged to whitelist CellMapper from any ad blocking software that you have.
How do I map?
Before you start mapping, please ensure that:
- Have a cell signal (d’oh!), there should be any data in CellMapper cells menu.
- Disabled aeroplane mode
- (Recommended) Have an active SIM. You can map with dead SIM or sometimes no SIM at all, but the phone will randomly latch to any telco signal that it can.
- Working & stable GPS, indicated by green Location/GPS icon in CellMapper cells menu.
- Disable any kind of battery saver feature
- (Highly recommended) Enable Keep Screen On and set brightness to DIM in CellMapper settings.
- Make sure Record icon is green in CM cells menu
Places that are discouraged/not recommended to map (please exit CM app or turn off record in CM dashboard), but you can:
- At any classified facilities/places (you actually can get into trouble!)
- Inside underground tunnels (LRT, MRT, Komuter, underground road tunnel, etc.)
- Inside any airborne vehicle (helicopter, aeroplane, seaplane, etc.)
- In building (home, shopping malls, etc.)
- Near any installation of femtocells/signal boosters
- The place is already well mapped like below, unless there is changes (decommissioned tower, added bands, new towers)
After that you can map almost anywhere you want as long as there is a cell signal.
At CM cells menu (dashboard), there are 4 icons above:
GPS/Location = Red: no lock; Green = there is GPS/location lock. Tapping on the icon shows GPS/location info on the bottom screen.
Upload = Red: disabled, upload manually in upload menu; Green = recorded data is uploaded automatically at certain time intervals if there is internet connection, enable it in CM settings
Account = Red: not logged into CM account or no internet access if you logged in before; Green: Logged into CM account
Record = Red: not enabled; Green: enabled. Can be toggled on and off as you wish.
At the bottom of the 4 icons, there should be info about currently serving (topmost with BTS/NB/eNB/gNB number, not in italics) cells and neighbouring cells (“UNKNOWN” or BTS/NB/eNB/gNB numbers in italics). You can search on the web for more info about each parameters, but you can refer to table below to understand how RSRP/RSRQ/SINR works.
Note that you can map without internet connection as long as GPS/location & Record icon is green. You can upload the points later via Upload menu.
General etiquette for mapping:
- Try to map new places, especially those less frequently visited as they’re often still not covered.
- From time to time make a round again to collect new cell towers that could appear in your area.
- Use SIM cards from different telcos to better cover your area.
5G NR mapping
You need to insert ONLY ONE SIM on your phone to map 5G NR data for the time being. However, if both SIMs are from the same telco (same PLMN), you can map 5G NR with dual SIM inserted.
Any kind of 5G saver mode needs to be disabled (such as 5G battery saver in Xiaomi’s MIUI, Smart 5G in realme UI/Oppo’s ColorOS) so that 5G NR can be mapped properly.
If NR NSA data shows up with frequency band/number (certain devices running Android 12 and above), enable “Record cells with frequency data” in CM settings.
Note that Digital Nasional Berhad (DNB) currently runs its network in NSA (non-standalone) mode, so CellMapper is only able to record signal trails which also means no cell towers will be shown in CellMapper map under the NR layer until DNB launches SA mode.
You can try to enable “Use Android 7.0+ Cell ID API” in CM settings if MCC & MNC doesn’t show up in NR NSA cells info.
Note that DNB sets Yes PLMN (502 152) as primary PLMN, so you may see Yes PLMN instead even with non-Yes SIM in the CM app. This is because some Android phones have problems with reporting MOCN towers properly to apps like CellMapper.
Upload recorded/mapped data
After you are done with mapping, make sure to upload the points via sidebar menu (≡)> Upload then tap on the Upload button. After all points have been uploaded, open the sidebar menu and tap Exit.
If there is any error while uploading (site maintenance, etc), you may try again later.
Closing notes
“Why should I use the CellMapper app?” To put it simply, data contributed can benefit everyone that uses CellMapper map 🙂
Some of the use cases:
- To know what telco performs best at particular area in terms of signal
- Adjust external antennas (LPDA, parabolic, outdoor CPEs, etc.) to point to correct direction or to another nearby tower if the nearest one are congested
- Utilise CellMapper data so that you can report network issues properly to telcos & regulators (MCMC, KKD/KKM, CFM etc.)
- Utilise CellMapper data for your research project (make sure you credit CellMapper in your papers)
- Prepare your trip properly, for example: download offline map data & and videos for use at patchy coverage areas.
What CellMapper doesn’t do:
- To know what telco performs best at particular area in terms of performance/speed/congestion.
- Use CellMapper data for commercial purpose. CellMapper makes it clear on the website with “COMMERCIAL USE STRICTLY PROHIBITED” sentence.
- Use its data to avoid yourself or others from ionizing radiation/virus spreading cell towers/whatever bullshit it is. Scary, right? /s
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