The example in Section 12.5.2 analyzes a MEAS_RES message in more detail.
The reader is asked to duplicate the following values by means of that example.
Table 12.1 provides an overview of the power control and most important parameters, which can be separated into two groups:
• The measurement results of the MS, which can be separated into the results related to the active BTS and those related to the neighbor cells;
• The measurement results of the BTS.
GSMNetworks:Protocols,Terminology,andImplementation
A-interface C-interface 1 C-interface 2 Explanation
UDT/BEGIN sendRoutingInfo
This figure does not show the ISDN exchange, due to space limitations.
When the Gateway-MSC receives an IAM (ISUP) for a mobile subscriber, then, first, the HLR of that subscriber is queried for location information.
To decide which HLR to query, can be retrieved from the MSISDN.
The G-MSC sends a sendRoutingInfo message (MAP) over the C-interface to the HLR. The HLR has the information, which VLR currently serves the subscriber (from Location Update ) and sends a provideRoamingNumber message (MAP), to determine routing information (MSRN).
UDT/BEGIN provideRoamingNumber
UDT/END
provideRoamingNumber UDT/END
sendRoutingInfo
E-interface
ISUP/IAM Initial Address Message
This allows the Gateway-MSC to initiate routing of the call request towards the active MSC/VLR, by means of the MSRN. For this purpose, an IAM message (ISUP) is used. After receiving the IAM, the MS is searched in the whole Location Area, by means of PAGING messages.
UDT/BSSM PAGING [TMSI/IMSI, CIs]
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DT1/BSSM CIPHER_MODE_CMP [-/-]
DT1/DTAP SETUP [connect. details]
When the connection is established to the MS, the SETUP message is used to provide all details (Bearer Capabilities) to the MS. This information is directly extracted from the IAM. The MS on its part confirms with CALL_CONF, that the SETUP message was received and accepted.
Otherwise, the MS reacts with a REL_COM message.
DT1/DTAP CALL_CONF [OK]
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BSC MSC HLR
VLR G-MSC
The MSC/VLR assigns a (temporary) MSRN for this process and responds with a provideRoamingNumber back to the HLR. The HLR for its part sends the MSRN in the sendRoutingInfo response, back to the Gateway-MSC.
Figure 12.9 Mobile terminating call in the NSS.
Scenarios253 Explanation
DT1/DTAP ALERT
The MSC sends an ACM to the Gateway-MSC, when it receives the ALERT message from the MS. The Gateway-MSCforwards the ACM to the ISDN.
The ALERT message signals that the mobile station is ringing.
ISUP/ACM Address Complete Message DT1/DTAP
CON ISUP/ANM
ANswer Message
As soon as the mobile subscriber accepts the call (e.g., presses the SEND button), the MS sends a CON message to the MSC. The MSC passes this information in an ANM (ISUP) via the Gateway-MSC to the ISDN. The MSC confirms receipt of the CON message towards the MS by sending a CON_ACK message.
DT1/DTAP CON_ACK
Active phase of the call ISUP/REL RELease [reason]
When the ISDN subscriber ends the call, the Gateway-MSC or the active MSC, respectively, receives a REL message (ISUP) from the ISDN.
The MSC passes this information, transparently in a DISC (BSSAP), via the BSS, on to the MS. The MS confirms release of the Call Control connection by sending a REL message (BSSAP) to the MSC. The MSC acknowledges that it received the REL message, and hence that the call has ended, to both, the MS, as well as towards the ISDN, by sending a REL_COM or a RLC message (BSSAP+ISUP).
DT1/DTAP DISC [reason]
DT1/DTAP
REL [reason] ISUP/RLC
ReLease Complete DT1/DTAP
REL_COM [reason]
C-interface 2 C-interface 1
A-interface
Figure 12.9 (continued)
The values for the receiving level (= RXLEV) and the receiving quality (=RXQUAL) are provided for both cases. Obviously, in the case of neighbor cell measurements, only the receiving level measurements are available, since the MS does not have an active connection.
Table 12.1
Input Parameters for Power Control and Handover Decision Measured Value
Object to be
Measured Explanation RXLEV-FULL-SERVING-
CELL (6 bit 0≡63dec)
BTS With what level does the MS receive the active BTS? This value is always provided but only relevant if no DTX is ac- tive in the downlink direction.
RXLEV-SUB-SERVING- CELL (6 bit 0≡63dec)
BTS With what level does the MS receive the active BTS? This value is always provided but only relevant if DTX is active in the downlink direction.
RXQUAL-FULL- SERVING-CELL (3 bit 0≡7dec)
BTS How well (BER) does the MS receive the active BTS? The BER is determined by means of the Training Sequence Code. This value is always present but only relevant if no DTX is active in the downlink direction.
RXQUAL-SUB- SERVING-CELL (3 bit 0≡7dec)
BTS How well (BER) does the MS receive the active BTS? The BER is determined by means of the Training Sequence Code. This value is always present but only relevant if DTX is active in the downlink direction
RXLEV-NCELL 1 - N (6 bit 0≡63dec)
BTS With what level does the MS receive the neighbor cells (as indicated in SYS_INFO 2)?
RXLEV-FULL-up (6 bit 0≡63dec)
MS With what level does the BTS receive the MS? This value is always provided but only relevant if no DTX is active in the uplink direction.
RXLEV-SUB-up (6 bit 0≡63dec)
MS With what level does the BTS receive the MS?
This value is always provided but only relevant if DTX is active in the uplink direction.
RXQUAL-FULL-up (3 bit 0≡7dec)
MS How well (BER) does the BTS receive the MS? The BER is determined by means of the Training Sequence Code. This value is always present but only relevant if no DTX is ac- tive in the uplink direction.
RXQUAL-SUB-up (3 bit 0≡7dec)
MS How well (BER) does the BTS receive the MS? The BER is determined by means of the Training Sequence Code. This value is always present but only relevant if DTX is active in the uplink direction.
Timing Advance (6 bit 0≡63dec)
MS How far is the MS away from the BTS?