5GNR Reference Signals Measurement
In 5G new radio (NR) system, reference signal measurement are used to perform cell selection, cell reselection and handover etc. Reference Signal (RS) measurements are further classified into three measurement parameters as given below:
 Reference Signal Received Power (RSRP)
 Received Signal Strength Indicator (RSSI)
 Reference Signal Received Quality (RSRQ)
These measurements (i.e. RSRP, RSRQ, RSSI) are included in the RRC Information Elements (IEs) carries.
Received Signal Strength Indicator (RSSI):
RSSI is defined as the total received wideband power measured over entire bandwidth by UE. RSSI is not reported to eNodeB. The RSSI is used in the calculation of RSRQ in LTE system. RSSI is also a power and its measurement unit is dBm
RSSI = Serving Cell Power + Neighbour CoChannel Cells Power + Thermal Noise
Under full Load condition the RSRP (dBm)= RSSI – 10*log (12*N)
where N represents number of resource block.







Bandwidth 
1.4 mHz 
3 mHz 
5 mHz 
10 mHz 
15 mHz 
20 mHz 
No. of Resource block(N) 
6 
15 
25 
50 
75 
100 
Scaling Factor: 1o log (12N) 
18.57 
22.55 
24.77 
27.78 
29.54 
30.72 
By using above equation RSSI can be calculated as:
If RSRP is 60 dBm and the cell is fully loaded (20MHz) and the UE is experiencing 10dBm power from a Neighbour cell operating at same frequency RSSI measured 60 dBm + 30.72 dBm +10 dBm = 19.98 dBm.
So from the above calculation it can be concluded that if UE is seeing only one cell then there is relation between RSRP and can be directly scaled by the factor for particular bandwidth given in the table1, but UE start seeing more signal on the same frequency from other cell then RSSI value become even better.
Reference Signal Received Power(RSRP):
RSRP is the linear average of reference signal power (in Watts) measured over a specified bandwidth (in number of REs). It is very similar to CPICH RSCP in WCDMA. It is applicable while UE in different RRC states i.e. RRC_IDLE intrafrequency, RRC_IDLE interfrequency, RRC_CONNECTED intrafrequency, RRC_CONNECTED interfrequency.
RP(Integer) 
From RSRP Value (dBm) 
To RSRP Value (dBm) 
00 

140 dBm 
01 
140 dBm 
139 dBm 
02 
139 dBm 
138 dBm 
03 
138 dBm 
137 dBm 
04 
137 dBm 
136 dBm 
05 
135 dBm 
134 dBm 
06 
134 dBm 
133 dBm 
07 
133 dBm 
132 dBm 
08 
132 dBm 
131 dBm 
09 
131 dBm 
130 dBm 
10 
130 dBm 
129 dBm 
11 
129 dBm 
128 dBm 
12 
128 dBm 
127 dBm 
13 
127 dBm 
126 dBm 
14 
126 dBm 
125 dBm 
15 
125 dBm 
124 dBm 
16 
124 dBm 
123 dBm 
17 
123 dBm 
122 dBm 
18 
122 dBm 
121 dBm 
19 
121 dBm 
120 dBm 
20 
120 dBm 
119 dBm 
21 
119 dBm 
118 dBm 
22 
118 dBm 
117 dBm 
23 
117 dBm 
116 dBm 
24 
116 dBm 
115 dBm 
25 
115 dBm 
114 dBm 
26 
114 dBm 
113 dBm 
27 
113 dBm 
112 dBm 
28 
112 dBm 
111 dBm 
29 
111 dBm 
110 dBm 
30 
110 dBm 
109 dBm 
31 
109 dBm 
108 dBm 
32 
108 dBm 
107 dBm 
33 
107 dBm 
106 dBm 
34 
106 dBm 
105 dBm 
35 
105 dBm 
104 dBm 
36 
104 dBm 
103 dBm 
37 
103 dBm 
102 dBm 
38 
102 dBm 
101 dBm 
39 
101 dBm 
100 dBm 
40 
100 dBm 
99 dBm 
41 
99 dBm 
98 dBm 
42 
98 dBm 
97 dBm 
43 
97 dBm 
96 dBm 
44 
96 dBm 
95 dBm 
45 
95 dBm 
94 dBm 
46 
94 dBm 
93 dBm 
47 
93 dBm 
92 dBm 
48 
92 dBm 
91 dBm 
49 
91 dBm 
90 dBm 
50 
90 dBm 
89 dBm 
51 
89 dBm 
88 dBm 
52 
88 dBm 
87 dBm 
53 
87 dBm 
86 dBm 
54 
86 dBm 
85 dBm 
55 
85 dBm 
84 dBm 
56 
84 dBm 
83 dBm 
57 
83 dBm 
82 dBm 
58 
82 dBm 
81 dBm 
59 
81 dBm 
80 dBm 
60 
80 dBm 
79 dBm 
61 
79 dBm 
78 dBm 
62 
78 dBm 
77 dBm 
63 
77 dBm 
76 dBm 
64 
76 dBm 
75 dBm 
65 
75 dBm 
74 dBm 
66 
74 dBm 
73 dBm 
67 
73 dBm 
72 dBm 
68 
72 dBm 
71 dBm 
69 
71 dBm 
70 dBm 
70 
70 dBm 
69 dBm 
71 
69 dBm 
68 dBm 
72 
68 dBm 
67 dBm 
73 
67 dBm 
66 dBm 
74 
66 dBm 
65 dBm 
75 
65 dBm 
64 dBm 
76 
64 dBm 
63 dBm 
77 
63 dBm 
62 dBm 
78 
62 dBm 
61 dBm 
79 
61 dBm 
60 dBm 
80 
60 dBm 
59 dBm 
81 
59 dBm 
58 dBm 
82 
58 dBm 
57 dBm 
83 
57 dBm 
56 dBm 
84 
56 dBm 
55 dBm 
85 
55 dBm 
54 dBm 
86 
54 dBm 
53 dBm 
87 
53 dBm 
52 dBm 
88 
52 dBm 
51 dBm 
89 
51 dBm 
50 dBm 
90 
50 dBm 
49 dBm 
91 
49 dBm 
48 dBm 
92 
48 dBm 
47 dBm 
93 
47 dBm 
46 dBm 
94 
46 dBm 
45dBm 
95 
45dBm 
44 dBm 
96 
44 dBm 

97 
44 dBm 

Practical Example of RSRP:
Let’s consider a single atnenna system and say the Reference Signal Transmitted power is about 12 dBm. A UE is located somewhere in the cell experiencing a path loss of 100 dB. Then the RSRP measured by UE should be 12100 = 88 dBm , When we compare 88dBm value in then Table 2 it is corresponding to RSRP Integer value 52 so UE can report RSRP=52 in the measurement report.
Normally, when anyone see the UE logs measurement report ,it contained the RSRP integer value, the quick way to find our absolute RSRP value in dBm is simply subtract the integer value from 140 .Let’s take an example Integer RSRP value is 45 then corresponding RSRP dBm = 140 + 45 = 95 dBm.
RSRQ:
RSRQ is th Reference Signal Received Quality and it can be defined using following equation:
RSRQ= (N* RSRP)/RSSI
As per the definition of RSSI, It is wide band power including signal power from serving cell, cochannel neighbour cell, interference from other cell interference and noise, in similar word one can say that RSRQ define the purity of Reference Signal (RS) across the system bandwidth. RSRQ is a calculated value from RSRP and RSSI is measure of signal and interference. As RSRQ is a ration of two signal powers with same same unit i.e. dBm so RSRQ uses dB as a measurement unit.
Similar to RSRP , UE reported an integer value to eNodeB and its range is from 0 to 34 (Table 3). 3GPP has provided a table shown below, by using this table the integer value can be translated to a range of RSRP value in dB.
The best value of RSRP is about 3 dB and worst value can be 19.5dB.
Reported RSRQ(Integer) 
From RSRQ Value(dB) 
To RSRQ Value(dB) 
00 

19.5 dB 
01 
19.5 dB 
19 dB 
02 
19 dB 
18.5 dB 
03 
18.5 dB 
18.0 dB 
04 
18.0 dB 
17.5 dB 
05 
17.5 dB 
17.0 dB 
06 
17.0 dB 
16.5 dB 
07 
16.5 dB 
16.0 dB 
08 
16.0 dB 
15.5 dB 
09 
15.5 dB 
15.0 dB 
10 
15.0 dB 
14.5 dB 
11 
14.5 dB 
14.0 dB 
12 
14.0 dB 
13.5 dB 
13 
13. 5 dB 
13.0 dB 
14 
13.0 dB 
12.5 dB 
15 
12.5 dB 
12.0 dB 
16 
12.0 dB 
11.5 dB 
17 
11.5 dB 
11.0 dB 
18 
11.0 dB 
10.5 dB 
19 
10.5 dB 
10.0 dB 
20 
10.0 dB 
9.5 dB 
21 
9.5 dB 
9.0 dB 
22 
9.0 dB 
8.5 dB 
23 
8.5 dB 
8.0 dB 
24 
8.0 dB 
7.5 dB 
25 
7.5 dB 
7.0 dB 
26 
7.0 dB 
6.5 dB 
27 
6.5 dB 
6.0 dB 
28 
6.0 dB 
5.5 dB 
29 
5.5 dB 
5.0 dB 
30 
5.0 dB 
4.5 dB 
31 
4.5 dB 
4.0 dB 
32 
4.0 dB 
3.5 dB 
33 
3.5 dB 
3.0 dB 
34 
3.0 dB 

So, when there is no traffic, and assuming only the reference symbols are transmitted (there are 2 of them within the same symbol of a resource block) from a single Tx antenna then the RSSI is generated by only the 2 reference symbols so the result becomes:
RSRQ = N / 2N = 3 dB for 1Tx
RSRQ = 6 dB for 2Tx
If all resource elements are active and are transmitted with equal power, then
RSRQ = N / 12N = 10.8 dB for 1Tx
RSRQ = N / 20N = 13 dB for 2Tx
(because RSRP is measured over 1 resource element and RSSI per resource block is measured over 12 resource elements).
Reference: TS 36.133
TS 36.304
 Vivek's blog
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