RSSI represents the total received wide-band power measured over entire bandwidth by UE. RSSI is not reported to eNodeB. It is computed to be used for the calculation of RSRQ in LTE system. RSSI is also a power and its measurement unit is dBm same as RSRP.

LTE系統(tǒng)中RSSI是UE在全帶寬上測量到的功率；RSSI不直接上報，而是換算成RSRQ上報eNodeB；

與RSRP相同，RSSI也是功率測量指標，計量單位為dBm; 

RSSI=Serving Cell Power + Neighbour Co-Channel Cells Power + Thermal Noise (1)

RSSI=服務小區(qū)功率+同頻鄰小區(qū)功率+熱噪聲功率

Under full Load condition the  RSRP (dBm)= RSSI – 10*log (12*N)  (2)

全加載場景下:RSRP(dBm)=RSSI-10*log (12*N)

                            圖表1.帶寬與噪聲系數(shù)

Using Above equation one can say that if RSRP is -70 dBm and the cell is fully loaded (20MHz) and there is not interference from other cell then RSSI measured by UE should be -70 dBm +30.72 = -39.28 dBm. Let’s say the UE is experiencing 10dBm power from a Neighbour cell operating at same frequency then the RSSI should be -39.28 dBm +10 dBm = -29 dBm

根據(jù)公式(2)當RSRP=-70dBm時，20MHz帶寬的小區(qū)無干擾時;

UE測量到的RSSI=-70dBm+30.72=-39.28 dBm;

而當UE接收到同頻鄰區(qū)的功率為10dBm時，

根據(jù)公式（1） RSSI=-39.28 dBm +10 dBm = -29.28 dBm

So from the above calculation it can be concluded that if UE is seeing only one cell then there is relation between RSRP and can be directly scaled by the factor for particular bandwidth given in the table, but UE start seeing more signal on the same frequency from other cell then RSSI value become even better.

通過公式，當網(wǎng)絡中僅有一個小區(qū)時UE可以直接獲得全帶寬的RSRP；

而UE接收到多個同頻小區(qū)信號時RSSI將會更高。