I am trying to calculate how much power an eNodeB would radiate if the maximum values of referenceSignalPower (50 dBm according to 6.3.2 in TS 36.331) and p_a (3 dB) were used. However, I am running into weird results and I would appreciate your advice. These are my assumptions:
1) One antenna port
2) Normal cyclic prefix
Let us also configure the PDSCH-ConfigCommon information element as follows:
referenceSignalPower = 50
Finally, let us assume that the cell under consideration only has one UE and let us configure the following PDSCH-ConfigDedicated for this UE:
Next, I calculate the EPRE_PDSCH. Since p-b=0 and only one antenna port is used, then from Table 5.2-1 in TS 36.213, it results that rho_B=rho_A. Then, also from section 5.2 in TS 36.213:
rho_A=delta_power_offset + p-a
Since delta_power_offset=0, then:
rho_A=0+3= 3 dB
Finally, the EPRE_PDSCH is simply:
EPRE_PDSCH = EPRE_cell_specificRS + rho_A = referenceSignalPower + rho_A = 50 + 3 = 53 dBm
Let us also assume that the cell has a system bandwidth of 20 MHz (N_RB=100 resource blocks). Then, in the first OFDM symbol of the second slot of a subframe in which the PBCH is not transmitted (e.g. the second subframe), there are a total of:
N_RS= N_RB*2 = 200 reference symbols (because each RB carries only 2 RS REs in this symbol)
N_PDSCH_REs = 100*(12-2)=1000 REs carrying the PDSCH
Hence, if each PDSCH RE has a transmit power of EPRE_PDSCH=53 dBm and each RS RE has a transmit power of EPRE_cell_specific_RS=50 dBm, the total power PT radiated by the eNodeB in this symbol is:
PT=N_RS*10^(50/10) + N_PDSCH_REs*10^(53/10) --> 83.4 dBm.
There are two things that strike me here:
-The EPRE of the reference symbols is lower than the EPRE of the PDSC REs due to p-a=dB3. I always thought that the RSs were the most powerful REs! Is this possible?
-A radiated power of 83.4 dBm sounds like a lot to me. Is this indeed foreseen in LTE deployments?
The maximum power transmitted over the whole bandwidth is typically 43dBm.
Then, the RS EPRE depends on the configuration but is usually around 15dBm. Thus, I think your first assumption might be wrong.
Thank you for your response Marko.
Yes, I agree in that RS_EPRE=15 dBm is a more "typical" value. However, I was concerned with the fact that the standard supports up until 50 dBm (see PDSCH-config section in 6.3.2 of TS 36.331). I wonder such a high value is supported? Would it make sense to deploy an eNodeB with an RS_EPRE=50 dBm?
Even though the standard allows the RS power to go up to 50 dBm, I doubt we'd ever see that in real life. Total cell power requirements aside, a UE could detect that cell and camp on it a hundred kilometers away, and yet be unable to receive any services because it would be uplink limited (a typical UE tops out at around 24 dBM).