GSM test failed due to RxLevF,RXQUAL not within range in CMU200
Both Rxlev and RXQUAL are used in GSM/GPRS system. They are measurement used mainly for power control as well as handover decision. Following information along with tables help analyze this GSM issue such as RxLevF and RXQUAL is not within range due to which test failed using CMU200 equipment.
RXLEV
It is basically the result of received signal level measurement by both MS and BTS individually. It is measured during active connection. Receive level of neighboring cells are indicated in system information message-2. Both RXLEV and RXQUAL are transmitted by Mobile in MEASUREMENT REPORT to the BSC to take decision on power control or handover. It holds unique values for active DTX i.e. SUBSET as well as without DTX i.e. FULL or ALL.
RXLEV field is 5bit long. This binary coded RXLEV value can be mapped to received signal level in dBm.
| RXLEV | Receiving Level (dBm) |
|---|---|
| 0 | <-110 |
| 1 to 62 | -(111 - RXLEV) through -(110 - RXLEV) |
| 63 | > -48 |
RxQUAL
RxQUAL is used for the measurement of Receiver Quality. It is related directly to BER of the system. It relates to bit error rate of the data received over Air interface. It is 3bit field and hence can hold any value from 0 to 7.
Ideally it should be zero for the tests to be passed which also indicates that BER is within limit.
Any nonzero value for RxQUAL will fail the test. Refer GPRS RxQUAL vs BER for all the values listed in the table.
Following parameters are very useful and are used as input parameters for handover and power control decisions.
| MEASUREMENT PARAMETER | DESCRIPTION |
|---|---|
| RXLEV-FULL-SERVING-CELL | 6 bit,BTS is measured here by MS |
| RXLEV-SUB-SERVING-CELL | 6 bit ,BTS is measured here by MS |
| RXQUAL-FULL-SERVING-CELL | 3 bit,BTS is measured here by MS |
| RXQUAL-SUB-SERVING-CELL | 3 bit ,BTS is measured here by MS |
| RXLEV-NCELL 1 - N | 6 bit,BTS is measured here by MS |
| RXLEV-FULL-up | 6 bit,MS is measured here by BTS |
| RXLEV-SUB-up | 6 bit,MS is measured here by BTS |
| RXQUAL-FULL-up | 3 bit,MS is measured here by BTS |
| RXQUAL-SUB-up | 3 bit,MS is measured here by BTS |
| Timing Advance | 6 bit,MS is measured here by BTS |
Test and Measurement Equipments
Test and Measurement Equipments BER Testing equipments Agilent T & M Solutions Anritsu T & M Solutions Rohde & Schwarz T & M solutions wireless channel emulator Vector signal generator Vector signal analyzer Power Analyzer Equipments Protocol Analyzer