GSM rxlev计算方法

在GSM系统中，我们常看到RXLEV参数，但这个参数都是正的，如何换算成负数？

Range of parameter

The measured signal level shall be mapped to an RXLEV valuebetween 0 and 63, as follows:

     RXLEV   0      =      lessthan                     ‑110 dBm + SCALE.
RXLEV   1      =      ‑110 dBm +SCALE         to     ‑109 dBm + SCALE.
RXLEV   2      =      ‑109 dBm +SCALE         to     ‑108 dBm + SCALE.
                                    :
                                    :
RXLEV   62    =      ‑49 dBm +SCALE            to     ‑48 dBm + SCALE.
RXLEV   63    =      greaterthan               ‑48 dBm + SCALE.

where SCALE is an offset that is used only in the ENHANCEDMEASUREMENT REPORT message, otherwise it is set to 0.

The MS shall use the SCALE value as indicated by the parameterSCALE_ORD in the MEASUREMENT INFORMATION message (see 3GPPTS 44.018 and 3GPP TS 44.060). If automaticscaling mode is indicated by SCALE_ORD, the MS shall choose thelowest SCALE value that is sufficient for reporting the strongestsignal level within each ENHANCED MEASUREMENT REPORT message.

The MS shall indicate the used SCALE value in each individualENHANCED MEASUREMENT REPORT message (see 3GPPTS 44.018).

 

也就是：实际电平值=报告值-111 dBm

 

例如GSM中RXLEV-ACCESS-MIN=14（SIB3中），那么最小接入电平值就是C=14-111=-97dBm

 

参考文档：3GPP 45.008 8.1.4