We often encounter situations where mobile phone signals are weak.
Generally speaking, we will judge the current signal strength through the signal logo in the upper right corner of the mobile phone.
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But in fact, this judgment method is too crude. Not only is the accuracy not high, it is not necessarily accurate.
As a veteran in communications, today Xiao Zaojun will introduce to you some more professional methods for judging mobile phone signals. At the same time, I also give you some basic knowledge about mobile phone signals.
First, let me tell you some of the signal checking methods that come with your mobile phone. You can check the signal strength without using a third-party app.
█ How to view on Apple phone
Open iPhone On the dialing interface, enter in the dialing keys *3001#12345#* and then click the dial button to view the signal-related data of the mobile phone.
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Notice! For different versions of mobile phones, the menu content here will be different. And, wait, it will take some time for the system to query the data. After a while, more menus will appear.
Click[NR Rach Attempt]under[5G]to view the value of 5G signal strength (cell_rsrp, the picture below is -98):
Click[Rach Attempt]under[4G]to view the 4G signal strength value (rsrp, -87 in the picture below):
The units of these values are dBm. dBm is calculated using a logarithm, so it is generally a negative value. (For a detailed introduction to dBm, see here: dB, dBm, dBw, dBi… What is the difference?)
Note that the smaller the absolute value of dBm, the better the signal quality.
The comparison reference is as follows:
In[Serving Cell Info]of[RAT]you can also see the following information:
Xiaozaojun will briefly explain to you some of the more important parameters.
PLMN: The operator’s public land mobile network code. Every carrier is different. PLMN consists of MCC (Mobile Country Code, 3 digits) and MNC (Mobile Network Code, 2-3 digits). 46011 is China Telecom’s 4G/5G.
KCTCellMonitorBWPSupport: Type of support for carrier bandwidth adaptation.
Band Info: Frequency band number, 78 in the picture refers to n78.
Bandwidth: Frequency bandwidth, the picture is 20MHz.
CellID: cell number.
Radio Access: Wireless access type. NR is 5G and LTE is 4G.
NRARFCN: 5G frequency number. A total of 3279165 grids are delineated in the frequency band range 0-100GHz. The rasters are numbered starting from 0 and going up to 3279165. Each number represents an absolute frequency domain position, and these numbers are called NR-ARFCN. This frequency number has its own calculation formula, which can be checked online.
PCI: Physical Cell Identifier, physical cell identifier. Used to distinguish wireless signals from different cells.
TAC: Tracking Area Code, tracking area code. It is allocated by the operator and mainly serves as a unique identifier for mobile user positioning.
█ How to view on Android phone
Look againAndroid.
Different brands of Android phones have different ways of checking signal strength.
Let’s take Xiaomi (MIUI 14) as an example. Open the phone’s[Settings]-[My Device]-[All Parameters and Information]-[Status Information]-[SIM Card Status (SIM Card Slot 1)](or Slot 2), you can view real-time signal strength. As shown below:
Signal strength is -93dBm. asu is Arbitrary Strength Unit, subjective strength unit, which can be regarded as the relative value of signal strength.
asu can be obtained from dBm, and the calculation formula is as follows:
LTE and 5G: asu=dBm+140
WCDMA and GSM: asu=(dBm+113)/2
The network type is 5G_SA, which means 5G independent networking (Standalone). Regarding SA and NSA, you can read here: What do NSA and SA in 5G mean?
█ How to view third-party apps
Okay, the above is the viewing method that comes with the mobile phone. As you can see, the information viewed is relatively simple.
What should I do if I want to see more detailed information? Then you have to use third-party App software.
There are many such software, and the one I use more often is Cellular-Z. You should be able to download it from the app store that comes with your phone. It is not recommended that you go online to find the installation package, as it is easy to get poisoned.
After Cellular-Z is installed, start it and enter the main interface:
As you can see, it has relatively complete functions – in addition to the signal status of the two card slots of the mobile phone, it can also view Wi-Fi and GNSS (satellite positioning), as well as complete information about the mobile phone itself.
Xiao Zaojun has just explained the various parameters of the card slot information, so I will not introduce them again here. There is NR-FREQ, which is the current specific 5G frequency of the mobile phone.
Signal strength, numerical values are displayed, and dynamic graphs are also displayed. As mentioned before, the lower the absolute value of the value, the better the signal.
The signal has several parameters, let’s talk about them separately. (It’s more professional, you can skip it if you don’t want to read it)
RSRP: Reference Signal Receiving Power, reference signal receiving power.
What we mainly look at is this parameter. It is the average of the signal power received on all REs (resource elements) carrying the reference signal within a certain Symbol (symbol). The range is between -44 and -140, higher is better.
RSRQ: Reference Signal Receiving Quality, reference signal receiving quality.
It is the ratio of RSRP and RSSI, ranging from -3 to -19.5, the bigger the better. It mainly sorts different LTE candidate cells based on signal quality. This measurement is used as input for handover and cell reselection decisions.
RSSI: Received Signal Strength Indication, received signal strength indication.
It attenuates with distance and is usually a negative value. The closer the value is to zero, the higher the signal strength. If the RSSI continues to be too low, it means that the uplink signal received by the base station is too weak, which may cause demodulation failure. If the RSSI continues to be too high, it means that the received uplink signal is too strong and interferes with each other too much, which also affects signal demodulation.
SINR: Signal to Interference plus Noise Ratio, signal to interference plus noise ratio.
It represents the ratio of the strength of the desired signal received to the strength of the interfering signal (noise and interference) received.
█ About Wi-Fi
Wi-Fi by the way.
Wi-Fi is divided into 2.4GHz frequency band and 5GHz frequency band (there is also a 6GHz frequency band, which is not currently open in China). Channels in both frequency bands include the following:
2.4GHz frequency band
Please note that the 2.4GHz band is very crowded. Mobile phones should try not to use the 2.4G frequency band and should use the 5GHz frequency band. Smart home products at home generally only support the 2.4G frequency band, which can be used for makeshift use.
Through this tool, you can check which channel in your home is relatively idle.
Then, on your own Wi-Fi router, you can set it to use this free channel (for example, channel 48 in the picture above, which belongs to the 5GHz band). The Wi-Fi signal experience will be much, much better.
█ About speed test
Let’s talk about speed testing.
Sometimes, high signal strength does not necessarily mean fast network speed. When there are too many users accessing the network, or the transmission resources of the base station are congested, there may also be a situation where the signal is full but the network speed is very slow.
When measuring speed, you usually use a third-party app, such as Speedtest.
Turn on location authorization to select a nearby speed measurement point and start speed measurement.
Normally, the 5G speed test will not exceed 1000Mbps. A rate of several hundred bps is already excellent. With dozens of Mbps, watching videos and chatting is no problem. If it’s only a few Mbps, the network experience is a bit choked.
█ About complaints
If poor network signal quality often occurs, you can call the operator’s customer service number to make a complaint. If the operator is still unable to solve the problem, you can also call the Ministry of Industry and Information Technology (12321) to lodge a complaint.
Cell phone signal problems often occur near some mysterious units, or near the R&D buildings of equipment manufacturers such as ZTE and Huawei, possibly due to interference. You can also complain about this.
Let me remind you again that if the base station signal is poor, there is nothing an individual, property or company can do and can only let the operator solve the problem. Except for operators, no person or unit is allowed to build their own public network communication base stations.
Okay, that’s today’s popular science. Does everyone understand?