RSRP, RSSI 与 RSCQ

RSRP

3GPP的定义

 

Reference signal received power (RSRP), 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 bandwidth.

For RSRP determination the cell-specific reference signals R₀ according TS 36.211 [3] shall be used. If the UE can reliably detect that R₁ is available it may use R₁ in addition to R₀ to determine RSRP.

 

The reference point for the RSRP shall be the antenna connector of the UE.

 

If receiver diversity is in use by the UE, the reported value shall not be lower than the corresponding RSRP of any of the individual diversity branches

 

Applicable for

 

RRC_IDLE intra-frequency,

RRC_IDLE inter-frequency,

RRC_CONNECTED intra-frequency,

RRC_CONNECTED inter-frequency

 

 

Note1: The number of resource elements within the considered measurement frequency bandwidth and within the measurement period that are used by the UE to determine RSRP is left up to the UE implementation with the limitation that corresponding measurement accuracy requirements have to be fulfilled.

Note 2: The power per resource element is determined from the energy received during the useful part of the symbol, excluding the CP

 

 

是对载有小区参考信号的Resource Element上参考信号的信号功率的线性平均。一般来说，第一个天线端口上的小区参考信号用来做RSRP测量。但如果UE有能力，第二个天线端口上的小区参考信号也可以用来定RSRP.

 

至于有多少个RE被考虑用来做线性平均则是由测量频率带宽决定的

 

注，每个RE上的功率仅是符号中有用部分的接收的能量决定的，不包含CP部分

 

又注，先要进行干扰的消除，只要最后的干净的滤波过后的对应参考信号的功率再做平均。

 

RSSI

3GPP 定义

 

The received wide band power, including thermal noise and noise generated in the receiver, within the bandwidth defined by the receiver pulse shaping filter, for TDD within a specified timeslot. The reference point for the measurement shall be the antenna connector of the UE.

Applicable for

RRC_IDLE inter-RAT,

RRC_CONNECTED inter-RAT

 

与RSRP不同，RSSI的测量和计算包含了噪声和干扰信号

 

 

摘自网上的相关知识

RSSI Received Signal Strength Indicator
Rx Recieived power

 

两者是同一概念，具体指（前向或者反向）接收机接收到信道带宽上的宽带接收功率。实际上中，前向链路接收机（指手机）接收到的通常用Rx表示，反向链路接收机（指基站侧）通常用反向RSSI表示。前向Rx通常用作覆盖的判断依据（当然还需结合Ec/Io），反向RSSI通常作为判断系统干扰的依据。下面以反向RSSI为例解释：

    为了获取反向信号的特征，在RSSI的具体实现中做了如下处理：在104us内进行基带IQ功率积分得到RSSI的瞬时值，即RSSI（瞬时）=sum（I^2+Q^2）；然后在约1秒内对8192个RSSI的瞬时值进行平均得到RSSI的平均值，即RSSI（平均）=sum（RSSI（瞬时））/8192，同时给出1秒内RSSI瞬时值的最大值和RSSI瞬时值大于某一门限的比率（RSSI瞬时值大于某一门限的个数/8192）。由于RSSI是通过在数字域进行功率积分而后反推到天线口得到的，反向通道信号传输特性的不一致会影响RSSI的精度。

    对于干净的无线电磁环境，电磁底噪水平可以通过一下公式进行计算： PN = 10lg(KTW)，对于CDMA系统来说常温情况下的底噪水平是-113dBm/1.2288M，考虑5dB的接收机噪声系数以及2dB的无线环境底噪波动水平，所以正常情况下，RSSI的监测结果应该是-106dBm左右，对于系统负荷的影响，一般最大不超过8dB,也就是-98dBm左右，考虑3dB余量，也就是说在高负荷情况下，如果系统工作正常，RSSI平均水平最大不超过－95dBm，否则就意味着网络有严重的反向干扰。

RSRQ

3GPP 定义

 

Reference Signal Received Quality (RSRQ) is defined as the ratio N×RSRP/(E-UTRA carrier RSSI), where N is the number of RB’s of the E-UTRA carrier RSSI measurement bandwidth. The measurements in the numerator and denominator shall be made over the same set of resource blocks.

 

E-UTRA Carrier Received Signal Strength Indicator (RSSI), comprises the linear average of the total received power (in [W]) observed only in OFDM symbols containing reference symbols for antenna port 0, in the measurement bandwidth, over N number of resource blocks by the UE from all sources, including co-channel serving and non-serving cells, adjacent channel interference, thermal noise etc.  

The reference point for the RSRQ shall be the antenna connector of the UE.

If receiver diversity is in use by the UE, the reported value shall not be lower than the corresponding RSRQ of any of the individual diversity branches.

 

Note

While RSRP is an indicator of the wanted signal strength, RSRQ additionally takes the interference level into account due to the
inclusion of RSSI. RSRQ therefore enables the combined effect of signal strength and interference to be reported in an efficient way

 

RSRP 指示了想要的信号强度，而RSRQ，由于引入了RSSI, 所以还额外考虑了干扰水平