Gmsk/8Psk Linear Modulation - Siemens BS-240 Technical Description

Information
Base Station System
A30808-X3247-L14-2-7618
Modulating bits
(1,1,1)
(0,1,1)
(0,1,0)
(0,0,0)
(0,0,1)
(1,0,1)
(1,0,0)
(1,1,0)
Tab. 3.2

GMSK/8PSK Linear Modulation

With the 8PSK modulation, the payload/burst is three times more.
The mechanical design of ECU is identical to that of CU versions.
ECU and CU modules may be installed in any kind of mixed configurations concerning
BS-240/241 hardware (Base/Extension Racks). Further, any cell/sector configuration
with a mixture of EDGE CU and "normal CUs" can be implemented.
The EDGE Carrier Unit (ECU) takes care for all carrier oriented tasks of the BTS. In
uplink (UL) direction, two RF signals (diversity) are received and finally converted into
TRAU frames and signalling data. In downlink (DL) direction, TRAU frames and signal-
ling data are received and converted into a GMSK or EDGE modulated RF signal, which
is amplified to the desired power level.
A BTS Rack can be equipped by any combination of ECU and CU.
Smart Adaptive Filtering
The ECU receiver has a smart adaptive filter function. Depending on the level of a
co-channel interference source, the receive signal passes through an adaptive filter with
variable bandwidth.
The filter bandwidth narrows with increasing interference level, allowing for best receiver
performance under a variety of traffic conditions. The quality of service (QoS) in the
uplink greatly benefits from this feature, which can efficiently match with adaptive
filtering in the mobile station receiver.
Functional Structure of the EDGE Carrier Unit
The ECU unit is a new developed and enhanced CU unit which supports the GMSK and
8PSK Modulation in uplink and downlink. It is a HW compatible to the CU unit and fits
into the BTSplus Rack. A functional description of the whole receive and transmit path
including the EDGE Carrier Unit and the antenna combining equipment can be found
below.
The ECU (Fig. 3.8) consists of following functional subunits:
Power Amplifier and Transceiver Unit (EPATRX)
Signal Processing Unit (ESIPRO)
EDGE Power Supply Unit (EPSU)
Technical Description (TED:BSS)
Symbol
0
1
2
3
4
5
6
7
BS-240/241
33