Thursday, 12 November 2015

the difference between RSRP ( LTE) and RSCP ( UMTS)

There are two reference signals analysed for LTE:-
1. RSRP - Reference Signal Received Power over the Reference Signal subcarriers
It is defined as the linear average over the power contributions (in[W]) of the resource elements that carry cell-specific reference signals within the considered measurement frequency bandwith.
2. W-RSRP - Wideband RSRP Power over all Reference Signal subcarriers
It is the received power on one code measured on the primary CPICH. The reference point for the RSCP shall be the antenna connector of the UE. If Tx Diversity is applied on the primary CPICH the RSCP from each antenna shall be separately measured and summed summed together in [W] to a total RSCP on the primary CPICH. If the received diversity is in use bye the UE, the reported value shall not be lower than the corresponding CPICH RSCP of any of the individual received antenna branches.

There is only one reference signal in UMTS:-
RSCP - Reference (Received) Signal Code Power
RSRP is estimated over 15 kHz LTE subcarriers while UMTS RSCP is measured over 5 MHz bandwidth so no direct comparison between these two metrics 

How much difference for RSRP and RSCP in db scale?
for example with 20W 5Mhz bandwidth:
1、Let's first assume that the LTE has RS in all symbol (continous RS in time). our same coverage permise is : We should have same RS power in LTE as UMTS,which is RSCP.
2、Because in LTE, the power are concentrated in RS sub-carrier, and in the 5M system, there are 25*2 RS REs. So the power if RS = RSRP_continous*25*2=RSCP
3、If we take out the assumption -"continous in time", then, to get the same averaged power, we have to increase the power of the RSRP to compensate. So we have RSRP= RSRP_continous*7/2
From above, we have RSRP= RSCP/50*7/2=RSCP*7/100. In db scale: RSRP=RSCP - 11.5db
for 10M bandwidth, the different is 14.5dB
for 20M bandwidth, the different is 17.5dB

Budi Prasetyo

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27 September 2016 at 06:28 delete

Let's assume:
LTE system configured as 10MHz and RS power 15dBm
WCDMA system configured as 5MHz and CPICH 30dBm

At point X away from the base station UE measures RSRP on 4G as -70dBm. What will be the equivalent CPICH RSCP at the same location (assume same carrier band is used)?