Rohde & Schwarz CMU-K20, Operating Manual

Page: 266 / 646

GPRS Signalling and EGPRS
CMU-K20/K21/K22/K23/K24
1115.6088.12 4.188 E-12
Setup of a Connection
(Popup Menu Connection Control – Connection)
The menu group Connection Control controls signalling (setup and release of a connection, services,
signalling parameters) and configures the inputs and outputs with the external attenuation values and
the reference frequency.
The term signalling denotes all procedures that are necessary for setting up and releasing a connection and for
controlling the connection in the mobile radio network. In the case of a GSM mobile phone supporting GPRS, both
a circuit switched GSM call connection and an (E)GPRS connection for data transfer can be set up. In addition a
special GPRS test mode has been defined for production tests of GPRS mobile phones. The five GSM signalling
states
Signal Off, Signal On, Synchronized, Alerting, Call Established of the CMU are therefore complemented by
the following GPRS signalling states:
Signal Off CMU transmits no signal.
Idle CMU transmits a GSM control channel signal. A GPRS mobile station can detect this signal,
synchronize to its timing and frequency and then read the system information. In particular,
the MS learns whether the CMU (representing the current cell in a real network) supports
GPRS services and can initiate a GPRS attach.
Attach in Progress Transitory state: GPRS attach is being performed. This step is always initiated by the mobile
station under test. The MS identifies itself with its GSM identity (IMSI, Temporary Link Level
Identity, TLLI) and indicates its presence to the CMU for the purpose of using GPRS Point to
Point (PTP) services. This can be done any time while the CMU is in the
Idle state.
Detach in Progress Transitory state: GPRS detach is being performed. Like GPRS attach, the GPRS detach
procedure is always initiated by the mobile station under test.
Attached The mobile station is GPRS-attached. From this state, it is possible to initiate a TBF
connection.
Connecting TBF Transitory state: The CMU attempts to access the TBF Established state. Unlike the GPRS
attach, the TBF connection must be initiated by the CMU.
TBF Established The mobile station is in the multislot test mode A or B for GPRS specified in GSM 04.14 (see
section
4.190
on p.
4.190
). In this mode, it continuously transmits RLC data blocks until the
TBF connection is released.
Note: The TBF Established state was specified especially in order to facilitate production tests.
Reaching this state is the goal of the CMU's GPRS signalling scheme. The CMU signalling
states
Idle, Attached and TBF Established must not be confused with the mobility
management states Idle, Standby and Ready defined in GSM 03.60.
A number of actions or control commands which can be initiated either by the CMU (e.g. Signal On, Signal Off) or
by the mobile station (e.g. MS Attach/Detach) switch between the different signalling states. In
Fig. 4-83
on p.
4.189
, dashed lines represent processes initiated by the mobile station.
Activating
(E)GPRS
The CMU mimics a real GSM base station which may or may not support
(E)GPRS. The instrument provides the two
Network Support modes GSM, GSM +
GPRS or GSM + EGPRS that can be selected in the Network or in the Connection
tab of the Connection Control menu while the CMU is in the GSM Signal Off or
Idle state (see Network Support softkey on p. 4.92 ff.).
Operating
sequence
To establish an (E)GPRS connection proceed as follows:
1. In the Menu Select menu, select one of the menus in GSM Signalling mode.
The Connection tab of the Connection Control menu is opened. The CMU should
be in the signalling state Signal On . The Main Service softkey is inactive.
2. Press the Network Support softkey to select GSM + (E)GPRS .
3. Press the Main Service softkey (which is now active) to select Packet Data
and switch over from the circuit switched GSM to the GPRS/EGPRS signalling
scheme.
The CMU is now in the GPRS Idle state. It reaches the Attached state after the
深圳德标仪器
135-1095-0799