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请教LTE终端接收信号功率计算的问题 (进入论坛模式)
提问者：atpcat
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提问时间：2012-6-20 15:07
如题，比如调度给终端一个RB，那么请问计算终端接收信号功率时，是应该用基站总功率(43dBm)-路损(dB)，还是应该用一个RB上的功率（比如20M小区，每个RB功率（43-20）=23dBm)-路损？ 期待大家答复，谢谢。
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最佳答案jeffyko 的答案
( 采纳时间：2014-3-31 18:11 )
firstly, PDSCH EPRE(power per RE per antenna port) can be set based on CRS EPRE, and according to 36.213, the difference between PDSCH EPRE and CRS EPRE is decided by a RRC configurable parameter: P_A.
Generally, CRS EPRE is fixed and broadcasted by SIB2. and P_A is UE specific, and the value range is [-6, -4.77, -3, -1.77, 0, 1, 2, 3], so at maximum PDSCH EPRE = CRS EPRE + 3dB. The value range of CRS EPRE is -60~50dBm.
In the extreme, we can set CRS EPRE and P_A to proper value to allow a single user to use as much power as possible.
But normal practices is that it is a multi-user network, and CRS EPRE is generally set to the average power (that's 20W(per antenna port) - 10*log10(1200)=12dBm, and by the way, the 23dBm power from you calculation is wrong!), and P_A may be to 0dB. In this case, PDSCH power is 12+0+3(two branchs tranmission) = 15dBm
Generally, CRS EPRE is fixed and broadcasted by SIB2. and P_A is UE specific, and the value range is [-6, -4.77, -3, -1.77, 0, 1, 2, 3], so at maximum PDSCH EPRE = CRS EPRE + 3dB. The value range of CRS EPRE is -60~50dBm.
In the extreme, we can set CRS EPRE and P_A to proper value to allow a single user to use as much power as possible.
But normal practices is that it is a multi-user network, and CRS EPRE is generally set to the average power (that's 20W(per antenna port) - 10*log10(1200)=12dBm, and by the way, the 23dBm power from you calculation is wrong!), and P_A may be to 0dB. In this case, PDSCH power is 12+0+3(two branchs tranmission) = 15dBm
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回答时间：2012-6-25 09:45其他答案 ( 6 条 )
you should use
received level = 23 + antenna gain - any feeder loss - shadow fading - penetration loss - path loss
received level = 23 + antenna gain - any feeder loss - shadow fading - penetration loss - path loss
为什么要把总功率平均到每个PRB上？又没有使用MU-MIMO，不能使用最大的功率吗？
我也没搞明白。。。等明白人解答
谢谢你的讲解！有一点还想问一下，20W(per antenna port) - 10*log10(1200)=12dBm里，10*log10(1200）一项是什么含义？
还有PDSCH power per PRB 在计算的时候，有3dB的“two branchs tranmission”这有是什么啊？
请不吝赐教，多谢多谢！
还有PDSCH power per PRB 在计算的时候，有3dB的“two branchs tranmission”这有是什么啊？
请不吝赐教，多谢多谢！
20W(per antenna port) - 10*log10(1200)=12dBm是对数域的计算公式
实际等效于总功率/1200，也就是每个RE上的平均功率
12+10*log10(12)就是每个PRB上的平均功率
实际等效于总功率/1200，也就是每个RE上的平均功率
12+10*log10(12)就是每个PRB上的平均功率
3dB是因为eNB有2个发射通道
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