LTE RSRP vs RSRQ | Difference between RSRP and RSRQ in LTE
This page LTE RSRP vs RSRQ describes difference between RSRP and RSRQ used in LTE.It explains basics of RSRP and RSRQ and mentions useful difference between terms.
RSRP is the short form of Reference Signal Received Power and it is equivalent to UMTS CPICH Received Signal Code Power (RSCP). RSRQ is the short form of Reference Signal Received Quality and it is equivalent to UMTS CPICH Ec/Io. Both LTE RSRP and LTE RSRQ parameters are used for cell selection, cell re-selection and handover. RSRP is also used to estimate the path loss for power control calculations.
It is the average power received from a single reference signal resource element. LTE RSRP is calculated for useful part of OFDMA symbol and will not consider cyclic prefix. The average is taken in linear units. Antenna connector of UE is considered as reference point. Either one or both antennas can be used for transmission of reference signal. This is considered for RSRP measurement.
SIB3 informs the UE of the maximum measurement BW used during intra frequency cell re-selection. It also informs UE whether second antenna need to be used for RSRP measurement or not. SIB-5 also provides the similar information to the LTE UE.
RSRP measurements are mapped to the integer numbers value range from 0 to 97 before they are included in the RRC messages. The same mapping is mentioned in the table below.
|Reported RSRP integer value||Actual RSRP in dBm|
Absolute Measurement Accuracy (intra-frequency RSRP measurement) = Between +/-6 and +/-8 dB.
Relative accuracy (between two intra frequency points) = between +/-2 and +/-3dB
Absolute Measurement Accuracy (inter-frequency RSRP measurement) = Between +/-6 and +/-8 dB.
Relative accuracy (between one intra frequency and another inter frequency points) = +/-6dB
The equation for LTE RSRQ is defined below:
RSRQ = RSRP/ (RSSI/N)
Where N is number of resource blocks over which RSSI is measured. RSSI is calculated as a linear average of the total power measured across OFDMA symbols which contain reference symbols transmitted from first antenna port, e.g. symbols 0 and 4 when MIMO is not used.
RSRQ also takes antenna connector of UE as reference point. RSRQ mapping from dBm to integer number is carried out first before including them within RRC messages. LTE RSRQ mapping into integer number value from 0 to 34 is mentioned in the table below.
|Reported RSRQ integer value||Actual RSRQ in dBm|
The max.RSRQ is based on assumption that Reference signal
resource elements are occupied (i.e. no traffic).
There are 2 RS REs per OFDMA symbol.
Hence RSRQ = RSRP/(RSSI/N) = RSRP/(2xRSRPxN/N) = 0.5 = -3dB
Absolute accuracy for intra-frequency RSRQ = between +/-2.5 and +/-3.5dB
A relative accuracy is not specified for intra-frequency case.
Absolute accuracy for inter-frequency RSRQ = between +/-2.5 and +/-3.5dB
A relative accuracy(between intra and inter frequency) = +/-3dB and +/-4dB .
LTE RSRP Calculator | LTE RSRQ Calculator
Refer LTE RSRP and RSRQ Calculator>> for complete detail including formula/equations and example of the calculator.
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