Why Suggestion for LTE RSRP is -105dBm

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Why suggestion for LTE RSRP is -105dBm? LTE coverage standard is measured by RS pilot channel power RSRP (Reference Signal Received Power), we can get the indoor edge field strength of RS based on the RX sensitivity: RX sensitivity: RSRP  RSRP

＝

-174 + 10×lg(15000) + NF + SINR + IoT + SM, (NF :

 Noise figure; SINR: Signal to interference plus noise ratio; IOT: IOT: Interference over thermal; SM: slow fading margin ) According to the requirements of edge rate, SINR is based on the 10RB occupied by one user, IoT is supposed to be 7dB, NF is equal to 7dB, the slow fading margin SM value is depende on coverage probability and standard variance of SM. Based on the current research: in case of 95% indoor coverage area, the SM standard error criterion values of different scenarios as follows:

shadow fading standard

shadow fading

variance

margin(dB)

Recreation Ground

7

8.6

Office Building

6

7

Hotel

7

8.6

Supermarket

6

7

Airport/ exhibition hall

6

7

Parking

6

4

scenario

In this paper, the slow fading margin is defined as 7dB, then the requriements of the RSRP are as follows: No.

Edge rate

Edge SINR

Edge RSRP

1

2 Mbps

6 dB

-105 dBm

2

1 Mbps

4 dB

-110 dBm

3

0.5 Mbps

0 dB

-115 dBm

For indoor coverage, the -105dBm edge strength can satisfy the severice requirement.

In LTE, the RS is defined as pilot signal, the RSRP is a sub-carrier power, for 20MHz 2014-12-20

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carrier band , there are 1200 sub-carrier , if the edge RSRP is -85dBm, the coverage radius is 15m,

the edge total power=-85dBm+10log(1200)=-54.2dBm, then we can calculate the output

 power of antenna is about 30dBm by ITU-R P.1238 propagation,

when the indoor antenna

output power is more than 15dBm, it will affect public security according to the ICNIRP (International Commission on Non-ionizing Radiation Protection) standard.

ITU-R P.1238 indoor propagation model .

 L

20 log  f     N  log d    L f  n   28 dB  X  

＝

 N  ：Distance

loss coefficient

 f  ：Frequency (unit: MHz)

d  ：Distance between a mobile station and a transmitter (unit: m) ， d   1m

 L f  n 

 X  

：Floor penetration loss coefficient

：Slow fading margin: Its value is related to the coverage

 probability requirement and the indoor slow fading standard variance. It has been considered in edge coverage criterion.

For example, N=20, f=2600MHz, Lf(n)=20dB, X σ= 7dB, the total output power of antenna is 10dBm, the output RSRP of antenna=10-10log1200=-20.8dBm, If the the edge RSRP is -85dBm, then it can calculate the coverage raduis d=2.21m, so the distance between two antennas is 2*d=4.41m, if the edge RSRP is -85dBm, the cost of deployment and implementation of the

2014-12-20

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 project can not be realized. Comparing GSM900, UMTS2100 and LTE 2600, if LTE RSPR is -85dBm, the GSM900 BCCH coverage level must be up to -40.7dBm, and UMTS2100 CPICH level must be up to -52dBm. It is difficult for GSM900 and UMTS2100 to achieve this coverage requirement

System Frequency(MHz) RRU output pilot

GSM 900 46

UMTS

LTE

2100

2600

33

15.2

 power(dBm)

Cost of deployment and implementation of the project can not be realized

According to the HUAWEI commerical and trial network experience, RS power of single RE is difficult to meet the -85dBm requirement. So Huawei suggest the edge RSRP is -105dBm.

2014-12-20

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