How to Measure Mobile Signal
It is always good to determine the signal you receive before you deploy your solution and compare it to the end result after implementation.
Measuring mobile signal is done in two ways, using the signal bars on your mobile device or obtaining exact readings.
The signal bars on your mobile device will offer a very basic interpretation of the mobile signal and also the signal quality. Each phone manufacturer calculates how many bars to display differently, resulting in different readings between phones in the same location.
It is important to stress that signal bars do not always mean you can make a call. Users will sometimes have signal bars, but cannot place a call due to network congestion.
The bars on your phone are a representation of both signal strength and the quality of the signal. As we have progressed from GSM, 3G and now 4G, the quality of the signal has become just an important as the signal strength level in determining your quality of service.
Users with five bars may have a low signal strength reading, but have excellent signal quality. iPhone – iOS 7 takes into account the signal strength, signal quality and also the number of people using the base station to determine how many bars are displayed.
This helps to prevent a user thinking they can place a call when they have several bars.
Other Phones – only takes into account the signal strength in dBm and the signal quality in determining how many bars to display.
The other way to measure signal is using exact readings from your phone. To access these readings you need either to put your phone into service mode or download a signal App. There are several measurements that determine the quality of your mobile signal:
Signal Strength – GSM & 3G/HSPA (RSSI) Applicable to GSM and 3G networks. The exact signal strength, often called Received Signal Strength Indication (RSSI), is measured in dBm. The dBm scale is roughly between -50 and -120dBm, with -50 being perfect signal and -120 being when you fall off the network. RSSI measures both the usable signal and the noise in a single figure.
- -50 to -75 dBm – High Signal
- -76 to -90 dBm – Medium Signal
- -91 to -100 dBm – Low Signal
- -101db to -120 dBm – Poor Signal
4G/LTE (RSRP) LTE signal strength is measured on a different scale than 3G/HSPA, it is measured in Reference Signal Received Power (RSRP). This often ends up being around -20dBm lower than RSSI, so - 100dBm (RSSI) would equate to around -120dbm (RSRP).
RSCP = RSSI + Ec/Io RSRP does a much more accurate job of measuring signal strength than RSSI, as it excludes noise and interference on the network, measuring just the usable portion of the signal.
Just because RSRP signals appear lower, it will not mean your signal is worse.
- -75dBm and -88dBm is a strong signal
- -89dBm and -96dBm is a very good signal
- -97dBm and -105dBm is good
- -106dBm and -112dBm is fair
- -113dBm and -125dBm is poor
SNR - The “Signal to Noise Ratio” is a measurement that compares the signal strength to the level of background noise. The higher the SNR the better your signal quality will be.
The SNR reading will be automatically calculated by the base station in dB. On the SNR scale 4 is poor and 25 is great.
ASU - "Arbitrary Strength Unit" is a value that is proportional to your RSRP. The higher the number the better your signal quality.
ASU = RSRP + 140, so if you have a RSRP of -100dBm, then the ASU will be 40.
Ec/Io - Very similar to SNR above, this measurement is the ratio of signal to interference. With the best being around -10 and the worst quality being around -40.
RSRQ - Reference Signal Received Quality is the ratio of usable signal to noise and interference measured in
Field Test, Service and Engineering Modes
To access the exact readings you need to go into your phones field test mode or into the phones settings to get the current network status.
Field test mode is entered by typing a code into the phones keypad, with each phone model having it’s own unique code.
iPhone - dial *3001#12345#* into the keypad and press call.
Android - You can view the db reading by going into Settings > About Phone. For service mode enter *#0011# into the keypad.
ZTE/Telstra Phones For service mode enter *983*3641# into the keypad. To exit service mode enter *983*3640#