Rohde & Schwarz CMU-K20, Руководство по эксплуатации

Страница: 265 / 646

CMU-K20/K21/K22/K23/K24
GPRS Signalling and EGPRS
1115.6088.12 4.187 E-12
Options and Extensions
The features described in this section require the installation of additional software options; for a
complete list of deliverable options refer to the data sheet.
GPRS Signalling and EGPRS
(Options CMU-K42/K43)
General Packet Radio Service (GPRS) is one of the extensions of GSM Phase 2+ that are aimed to
increase the obtainable data transfer rate. To reach this objective, GPRS relies upon the following key
features:
1. Data transfer is packet oriented. In addition, transmission takes place only when there are actually data
packets to be transmitted (Temporary Block Flow, TBF): The radio resources for each subscriber are
dynamically allocated. Compared to circuit switched data transfer where a fixed physical radio channel is
continuously occupied by one call, the radio resources can be used more efficiently.
2. GPRS is a multislot solution: Up to 8 timeslots per TDMA frame can be allocated to a single subscriber.
3. Redundant data transmission required for error protection can be minimized by using different channel coding
schemes CS1 to CS4.
4. GPRS can be combined with 8PSK-modulated traffic channels to form Extended GPRS (EGPRS). In EGPRS
nine different modulation and coding schemes MCS1 to MCS9 are specified.
5. As a GSM extension, GPRS always works in combination with the existing circuit switched network and does
not change or replace any of the existing GSM features. GPRS and GSM services can be used alternately.
The characteristics of the GPRS technology outlined above determine the test requirements for GPRS
mobile phones and the GPRS-specific test functionality of the CMU:
1. A GPRS-specific test mode for transmitter tests and a loopback test mode for BER tests has been
defined, see
Service Selection
softkey on p. 4.192 . The CMU is capable of performing
Receiver
Quality
measurements on packet switched data traffic channels (PDTCHs) and evaluates the Block
Error Ratio (BLER) and the Data Block Error Rate (DBLER). For background information refer to
section
BER Tests of PDTCHs
on p. 4.120 .
2. The CMU is able to measure a mobile station that operates in multislot mode (see
Slot Mode
softkey on p. 4.155 ). In particular, the tester measures and displays the power versus time and
performs a limit check in up to 4 consecutive timeslots (see section
P/t Multislot
on p. 4.107 ff.). In
contrast to circuit switched operation, no single-slot packet data mode is available.
3. The channel coding schemes CS1 to CS4 that a GPRS mobile station under test will use and the
modulation and coding scheme MCS1 to MCS9 for an EGPRS mobile station can be set in the
Network
tab of the
Connection Contol
menu
(Coding Scheme;
see section
Network Parameters
(Connection Control – Network)
on p. 4.198 ).
4. The GPRS signalling states and the procedures for setting up a data connection are analogous to
the corresponding circuit switched functionality. GPRS is an additional mode of the mobile phone
so that the circuit switched GSM and the GPRS signalling schemes are largely independent from
each other. Any time before a call or a TBF connection is established, the CMU is able to switch
over between circuit switched GSM and GPRS mode (see
Fig. 4-83
on p. 4.189 ).
深圳德标仪器
135-1095-0799