4G Signal Statistics Explained

One of the advantages of deploying a NetVault service with one of our Managed Cisco attached to the service is you get access to a lot of sensor data via our Netmon Monitoring platform. In the case of a service that has Managed Cisco with integrated 4G LTE, you will also be able to see signal statistics from the 4G LTE modem. The only thing is if you don’t know what any of the data shown means, it is hard to tell if the 4G signal is good or bad were you have placed the Cisco router. Well, worry no more as we will breakdown the different signal statistics and how to work out how good your 4G signal is.

Reference Signal Received Power (RSRP)

RSRP is a measurement of the signal strength received by the 4G LTE modem. This is displayed as a negative number in a unit format of dBm (decibels per milliwatt), the closer the measurement is to zero the better or stronger the RSRP is.

Below is a table showing the generalised levels for RSRP values.

Reference Signal Received Quality (RSRQ)

RSRQ is a measurement of the signal quality being received by the 4G LTE modem. This is displayed as a negative number in a unit format of dB (decibels), like RSRP the closer the measurement is to zero the better quality the signal is.

Below is a table showing the generalised levels for RSRQ values.

Signal to Interference plus Noise Ratio (SINR)

SINR is a measurement of the interfering noise against the actual signal being received by the 4G LTE modem. In the case of the SINR, it should be a positive number and the larger the number is from zero the better your SINR is. SINR can also reach into the negative values, this represents that there is a larger amount of interfering noise then available signal to be used. The 4G LTE service can still work with a negative value but it is not advised.

Below is a table showing the generalised levels for SINR values.

Received Signal Strength Indicator (RSSI)

RSSI is an overall measurement of the 4G LTE signal calculated using the values of the RSRP, RSRQ and SINR. This value is not displayed as part of the 4G Signal Statistics sensor, but it is an easy calculation to make and give you a general understanding of how your overall 4G performance should be. The RSSI value is a negative number and the closer to zero the better your 4G experience should be, to work out the RSSI all you need to do is the following formula:

RSSI = RSRP + RSPQ + SINR

So for example, if we had a service with an RSRP of -82dBm, RSRQ of -21dB and an SINR of 30dB; the RSSI formula would be -82 + -18 + 30 which equals -70dBm for the RSSI. As you can see that makes the RSSI to sit in the good range on the table below, even though the RSRQ is poor the RSRP and SINR are good enough to make up for that.

Below is a table showing the generalised levels for RSSI values.

Example of Bad Signal Statistics

The image below is an example of bad signal strength from Netmon, the SINR is -3.2dB which is very poor and the RSRP is also very poor sitting at -107 dBm. The RSSI for this service is -125.2dBm (-107dbm + -15dB + -3.2dB) which is very poor. It’s at the point that if the service had to failover to it 4G LTE service after the primary connection fails, the End User would find the service to either be running at only at a few Mbps or even unusable.

Example of Good Signal Statistics

The image below is an example of good signal strength from Netmon, the SINR is 25dB which is excellent and the RSRQ is also excellent sitting at -8 dB. The RSSI for this service is -74dBm (-91dbm + -8dB + 25dB) which is good. If the service had to failover to it 4G LTE service after the primary connection fails, most End Users would not realise that the primary connection had failed.

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