Thursday, 5 November 2015

Reference Signal Received Quality (RSRQ) Introduction and Calculation


Abstract
    Nowadays, in our FDD LTE Bidding projects, RSRQ is an important KPI which is mentioned in RFP to measure the performance of coverage. This paper will describe the concept of RSRO and introduce the calculation method of RSRQ in detail.


RSRQ Calculation:      
       The eNodeB use two transmit, the signal distribution is presented as follow:
 

 We can see in one RB which consists of 12 sub-carrier, 2 REs transmit reference signal, 8 Res transmit data signal,    and 2 REs are empty.
We will introduce RSRQ calculation under assumption as follow
Bandwidth5MHz
RB usage ratio of Serving cell1Range is from 0~1
RB usage ratio of Neighboring cell: 0 (Range is from 0~1)
Server Cell RSRP: -90dBm
Neighbor Cell1 RSRP: -110dBm
Neighbor Cell2 RSRP: -110dBm
PA=0, then the power of each RE is the same.
The detail calculation is described as follow:
(1)    Server Cell RB Power12 sub-carrier of one symbol):= RB usage ratio of Serving cell *10^((10*LOG10(8)+ Server Cell RSRP)/10)+10^((10*LOG10(2)+ Server Cell RSRP)/10)
= 1.00E-08mw
(2)    Neighbor Cell1 RB Power12 sub-carrier of one symbol):= RB usage ratio of Neighboring cell *10^((10*LOG10(8)+ Neighbor Cell1 RSRP)/10)+10^((10*LOG10(2)+ Neighbor Cell1 RSRP)/10)= 2E-11mw
Neighbor Cell2 RB Power12 sub-carrier of one symbol=2E-11mw
(3)    Noise power=10^((10*LOG10(带宽*1000000)-174)/10)= 1.99054E-11mw
(4)    RSSI==10*LOG10(Server Cell RB Power + Neighbor Cell1 RB Power + Neighbor Cell2
RB Power + Noise Power)=-79.97dBm
(5)    RSRQ= Server Cell RSRP- RSSI=-10.03dBm.


RSRQ Introduction
        RSRQ: Reference Signal Received Quality (RSRQ) is defined as the ratio N×RSRP/(E-UTRA carrier RSSI), where N is the number of RB’s of the E-UTRA carrier RSSI measurement bandwidth. The measurements in the numerator and denominator shall be made over the same set of resource blocks.
        RSSI: E-UTRA Carrier Received Signal Strength Indicator (RSSI), comprises the linear average of the total received power (in [W]) observed only in OFDM symbols containing reference symbols for antenna port 0, in the measurement bandwidth, over N number of resource blocks by the UE from all sources, including co-channel serving and non-serving cells, adjacent channel interference, thermal noise etc. If higher-layer signalling indicates certain subframes for performing RSRQ measurements, then RSSI is measured over all OFDM symbols in the indicated subframes.

RSRQ Calculation:      
       The eNodeB use two transmit, the signal distribution is presented as follow:
      
 
 We can see in one RB which consists of 12 sub-carrier, 2 REs transmit reference signal, 8 Res transmit data signal,    and 2 REs are empty.
We will introduce RSRQ calculation under assumption as follow
Bandwidth5MHz
RB usage ratio of Serving cell1Range is from 0~1
RB usage ratio of Neighboring cell: 0 (Range is from 0~1)
Server Cell RSRP: -90dBm
Neighbor Cell1 RSRP: -110dBm
Neighbor Cell2 RSRP: -110dBm
PA=0, then the power of each RE is the same.
The detail calculation is described as follow:
(1)    Server Cell RB Power12 sub-carrier of one symbol):= RB usage ratio of Serving cell *10^((10*LOG10(8)+ Server Cell RSRP)/10)+10^((10*LOG10(2)+ Server Cell RSRP)/10)
= 1.00E-08mw
(2)    Neighbor Cell1 RB Power12 sub-carrier of one symbol):= RB usage ratio of Neighboring cell *10^((10*LOG10(8)+ Neighbor Cell1 RSRP)/10)+10^((10*LOG10(2)+ Neighbor Cell1 RSRP)/10)= 2E-11mw
Neighbor Cell2 RB Power12 sub-carrier of one symbol=2E-11mw
(3)    Noise power=10^((10*LOG10(带宽*1000000)-174)/10)= 1.99054E-11mw
(4)    RSSI==10*LOG10(Server Cell RB Power + Neighbor Cell1 RB Power + Neighbor Cell2
RB Power + Noise Power)=-79.97dBm
(5)    RSRQ= Server Cell RSRP- RSSI=-10.03dB.

 


Budi Prasetyo

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