This article applies for all 2G, 3G and LTE devices.
The article resumes how to interpret the values without complete explanations about each parameter.
A more detailled explanation of every parameters will be found in separate related articles.
In This Task
- Summary of issue
- Related Articles
dB, dBm, dBi and dBd:
All devices (smartfones, 4G routers, ..., display some parameters to help optimizing 2G/3G/4G connexions.
This article explains how to basically interpret these ones.
Signal values are defined by a few different measurements which vary even more for different service modes. These measurements are as follows:
- EC/IO - Downlink carrier-to-interference ratio (signal quality) (dB) (2G, 3G & LTE)
- SINR - Signal-to-Interference-plus-Noise Ratio (signal quality) (dB) (LTE only)
- RSSI - Received Signal Strength Indication (signal power) (dBm) (2G, 3G and LTE)
- RSCP - Received Signal Code Power (signal power) (dBm) (3G only)
- RSRP - Reference Signal Received Power (signal power) (dBm) (LTE only)
- RSRQ - Reference Signal Received Quality (signal quality) (dB) (LTE only)
There are many different factors that influence signal strength and quality, including but not limited to:
- Tower load
- Proximity to the cellular tower
- Signal going through a cellular repeater
- Competing signals
- Physical barriers (mountains, buildings, trains, etc.)
- Both Signal Strength and Signal Quality must be considered for successful cellular data connection
- Measured or reported values vary by modem, carrier, and network environment
- There is no black/white answer to what constitutes a successful connection
- Although signal strength may appear to be adequate, throughput speeds may vary due to dependencies on cellular tower loads
Note that Power parametrs are expressed in dBm, Quality parameters in dB
Ec/Io values - Downlink carrier-to-interference ratio (signal quality) (dB) (2G, 3G & LTE)
Ec /Io is a negative dB value.
Values closer to 0 are better signals.
This is a ratio of 'good' energy over 'bad' energy, or 'cleaness' of signal.
In a perfect world, where there is no true interference, the interference level is equal to the noise level resulting in an
Ec/Io = 0 dB. Once the Ec/Io is above ~ -7 dB, your connection is going to suffer.
Some articles refers to following levels:
In a perfect world, where there is no true interference, the interference level is equal to the noise level resulting in an EC/IO = 0 dB. Once the EC/IO is above ~ -7.0 dB, your connection is going to suffer.
SINR values - Signal-to-Noise Ratio (signal quality) (dB) (LTE only)
SINR is commonly used in wireless communication as a way to measure the quality of wireless connections.
SINR is not actually a ratio but the difference in decibels between the received signal and the background noise level (noise floor). For example, if a radio (client device) receives a signal of -75 dBm and the noise floor is measured at -90 dBm, the SINR is 15 dB. Data corruption and therefore re-transmissions will occur if the received signal is too close to the noise floor. In 802.11 networks, re-transmissions adversely affect throughput and latency.
Use the table below as an indication.
RSSI (Received Signal Strength Indication (signal power) (dBm) (2G, 3G and LTE)
RSSI measures both the usable signal and the noise in a single figure.
RSSI represents the entire received power including the wanted power from the serving cell as well as all cochannel power and other sources of noise.
The RSSI of the modem is indicated by a negative dBm value.
The closer to 0 dBm, the stronger the signal
RSSI values in 2G - Received Signal Strength Indication (signal power) (dBm) (2G, 3G and LTE)
2G (GSM) Signal strength is defined by only one value: RSSI - Received Signal Strength Indicator;
RSSI is a negative value, and the closer to 0, the stronger the signal.
RSSI values in 3G - Received Signal Strength Indication (signal power) (dBm) (2G, 3G and LTE)
The RSSI standard values for 3G are basically the same as for 2G.
RSSI in LTE - Received Signal Strength Indication (signal power) (dBm) (2G, 3G and LTE)
RSSI for LTE is a calculated from several other signal related measurements.
RSSI = wideband power = noise + serving cell power + interference power.
RSCP values (3G only) - Received Signal Code Power (signal power) (dBm) (3G only)
RSCP - indicates the Received Signal Code Power
RSCP term is used for 3G coverage and becomes RSRP in 4G
It denotes the power measured by a receiver on a particular physical communication channel.
while RSCP can be measured in principle on the downlink as well as on the uplink, it is only defined for the downlink and thus presumed to be measured by the UE (User Equipment) and reported to the Node.
Note : RSCP parameter in 3G becomes RSRP in LTE
RSRP values - Reference Signal Received Power (signal power) (dBm) (LTE only)
Knowledge of absolute RSRP provides the UE with essential information about the strength of cells from which path loss can be calculated and used in the algorithms for determining the optimum power settings for operating the network. Reference signal receive power is used both in idle and connected states.
RSRP is usualy showd as bars even if this is very approximative and giving false sence of good connection
RSRP does a better job of measuring signal power from a specific sector while potentially excluding noise and interference from other sectors.
RSRQ values - Reference Signal Received Quality (signal quality) (dB) (LTE only)
RSRQ is the Reference Signal Received Quality is a C/I type of quality measurement and it indicates the quality of the received reference signal (similar to EC/IO in 3G)
RSRQ is a calculated value from RSRP and RSSI . As RSRQ is a ratio of two signal powers with same same unit ( i.e. dBm) it uses dB as a measurement unit. Similar to RSRP , UE reported an integer value to eNodeB and its range is from 0 to 34
Measuring RSRQ becomes particularly important near the cell edge when decisions need to be made, regardless of absolute RSRP, to perform a handover to the next cell. Reference signal receive quality is used only during connected states
Range :- -3 to -19.5 dB
Combination of values
There are some good practice tables.
There is following relationship between SINR and RSRQ (LTE only):
There is also a relationship between SINR and RSSI (2G, 3G and LTE):
IF RSRP is is good but RSRQ is bad, you have noise !
If SINR is, say 13 dB but RSRP is below -80 or RSRQ is below -10 it indicates a problem and then easiest to use SINR only.
A minimum of -20 dB SINR is needed to detect RSRP/RSRQ.
For formula lovers, relationships between RSSI and other measurements:
RSCP become RSRP and RSSI is not that relevant but can be calculated.
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