What is RSSI, SINR, RSRP, RSRQ? How does this affect signal quality?

Various values ​​such as RSSI, SINR, RSRP, and RSRQ are used to determine the strength and quality of a cellular signal. It is important to know what these abbreviations mean in order to properly adjust the outdoor antenna of a modem, 4G router or repeater and get a stable and fast cellular connection.

Unfortunately, not all cellular devices are able to show all the listed values. It often happens that your modem model displays only a part of the values ​​or one specific value in the web interface. In the worst case, a mobile device may not be able to display numerical values for signal strength and quality at all. In this case, it is impossible to find out the numerical indicators, since the scale is formed based on internal algorithms and calculations of the device software.

When evaluating link quality using RSSI, SINR, RSRP and RSRQ values, you should consider the following factors:

• These metrics help you determine the best location for your outdoor antenna and provide an overall assessment of your RF environment. However, they are not absolute, as cellular communications quality is also affected by other external factors – base station utilisation, operator equipment bandwidth, etc. The tables of estimated parameters below are provided for informational purposes and are based on the experience of our engineers and customers;
• Due to significant differences between 2G, 3G and 4G standards, not all indicators are applicable to all mobile networks. For example, the signal of GSM networks is usually measured with a single RSSI indicator, while 4G networks actively use all four parameters listed above. Parameter estimation also differs depending on the generation of cellular communications. An acceptable RSSI value for GSM communication may be too low for 4G networks.

So, let’s go to the web interface of a mobile device and find the values ​​​​of RSSI, SINR, RSRP and RSRQ. What do all these letters mean? Let’s figure it out!

Received Signal Strength Indicator (RSSI)

RSSI is the value of the signal strength received at the antennas of the device. RSSI is measured in decibels milliwatts (dBm) and indicates the strength of the signal received by your device. In modern networks, this indicator does not allow you to say anything about the quality of the signal, because it takes into account not only the useful signal of your cell, but also all the secondary signal in the measured frequency range. For example, the RSSI value includes the signal of neighboring base stations, internal and external interference and noise.

Since the RSSI parameter is measured in logarithmic decibel-milliwatt units, it can also take on negative values. The higher the RSSI value, the stronger the signal sent to the device. For example, the signal level at RSSI = -55 dBm is much higher than at RSSI = -75 dBm.

RSSI is the simplest, but also the least useful indicator, allowing only a rough estimate of the quality of the connection. In case of strong interference, the RSSI value can be very high, while the mobile Internet works very slowly.

Today, it is recommended to use the RSSI indicator only to assess the strength of the GSM and 3G signal and not to use it when working with 4G devices.

3G signal quality

Received Signal Code Power (RSCP)

In 3G networks, in addition to the RSSI indicator, the RSCP (Received Signal Code Power) parameter is used. This indicator indicates the strength of the signal code received by your device when connected to the operator’s base station. It is important to understand that this figure does not take into account ambient noise. A high RSCP value does not necessarily mean a high quality connection, since the level of ambient noise can be critical for the operation of a 3G connection.

EC/IO (Energy per chip to Interference power ratio)

To assess the quality of cellular communication, it is necessary to take into account not only the strength of the received signal, but also the level of radio frequency noise caused by other smartphones and mobile devices, neighboring base stations, and other artificial sources. For this purpose, 3G networks use the indicator EC / IO ( Energy per chip to Interference power ratio ), which allows you to evaluate the quality of communication based on the strength of the incoming signal and the strength of the interference recorded. EC/IO is always negative.

4G LTE Signal quality

RSRP (Reference Signal Received Power)

During the development of the fourth generation of mobile communications, the 3GPP consortium concluded that RSSI, which takes into account the strength of the entire incoming signal, is not the most appropriate tool. Instead of RSSI, LTE specifications often use the RSRP parameter, which estimates power based on the pilot signals coming from the current base station. Since RSRP does not depend on the channel width and does not take into account spurious signals and interference, it always has a lower numerical value than RSSI.

SINR (Signal Interference + Noise Ratio)

In an ideal world, where there is no electromagnetic interference and the signal from the source reaches the receiver without distortion, noise measurement is not necessary. However, in real life, a cellular signal is affected by many factors such as weather conditions, terrain, greenery, nearby buildings, walls, incorrect antenna settings, and various operating equipment.

In 4G networks, the signal-to-noise ratio is expressed by the indicator SINR (Signal to Interference + Noise Ratio). For some device models, this value can also be abbreviated as CINR – these are full synonyms (Carrier to Interference + Noise Ratio).

SINR is calculated as the ratio between the desired signal and interference from outside sources, and is almost always positive. Negative SINR values actually mean that the 4G network is not working at the current location. SINR is often used to measure signal quality, but it is not included in the specifications of the 3GPP consortium, which develops mobile communications standards.

RSRQ (Reference Signal Received Quality)

The 3GPP consortium has proposed its own indicator for assessing the quality of a 4G signal – RSRQ (Reference Signal Received Quality). RSRQ indicates the quality of the received pilot signals from the current base station. The values of RSSI and RSRP are used for the calculation.

The RSRQ and SINR values can be used independently or together to select the optimal position for an outdoor cellular antenna.

How to use RSSI, SINR and RSRP indicators to tune an outdoor antenna?

During the tuning of a street antenna, the above indicators can change both in one direction and in different directions. There are situations when tuning to a distant base station gives a better result than tuning to the nearest BS. For example, if you tune an antenna to a distant base station, the RSSI level may decrease (because the antenna will no longer receive interfering signals from other sources), but the signal-to-noise ratio (SINR) and the base station signal strength (RSRP) will increase.

We recommend considering as many parameters as possible when aligning an antenna. It should be remembered that when transmitting Internet data, the signal-to-noise ratio is one of the most important parameters, often more important than the absolute signal strength (RSSI).

How to see the level of RSSI, SINR, RSRP on iPhone and Android?

Modern phones offer the possibility to view the signal strength in real time in decibels (RSSI) and additional parameters such as SINR, RSRP and RSRQ. However, the list of available options depends on the phone model and the installed software (firmware). To choose the right repeater, you can check the most of these parameters on the iPhone or Samsung Galaxy smartphone.