Antenna Combiners And Receiving Paths; Methods Of Combining - Siemens BS-240 Technical Description

Information
Base Station System

4 Antenna Combiners and Receiving Paths

4.1
A30808-X3247-L14-2-7618

Methods of Combining

In order to serve cells with different carrier numbers, certain combinations of combining
modules are required. These configurations provide the necessary performance in a
cost effective way.
For the UL (Up Link) path, antenna diversity is always considered. The required splitting
factor only depends on the maximum carrier number per cell without yielding a
reson-able technical penality.
With respect to the DL (Down Link), a trade off exists between the number of antennas
and the insertion loss for a given carrier number. Increasing the antenna number
decreases the DL insertion loss introduced by hybrid combining of carriers to one
antenna port. For high carrier numbers per cell (≥5) filter combining becomes advanta-
geous with respect to insertion loss but suffering from higher cost and incompatibility to
synthesizer frequency hopping.
Nevertheless, for urban sites where the cell sites are usually small a configuration with
a DUAMCO 8:2 supports synthesizer frequency hopping and there is no need for addi-
tional antennas. Fig. 4.1
between labels and components is shown in
Duplex Combining
2:2 4:2
2x 4x
Filter Combining
2:1 2:1
8x
TX
Fig. 4.1 Overview of Combining Options
DUAMCO (Duplexer Amplifier Multi Coupler)
The DUAMCO x:y modules contain duplex filters in order to combine the transmit and
receive path to one antenna connector. The receive and transmit part of the duplex filter,
respectively, provide the substantial part of the receive and transmit band filtering
required by GSM 05.05, 11.21 and JTC J-STD-007.
the different combining options are shown. The relationship
8:2
8x
2x8
8x
RX
Technical Description (TED:BSS)
Fig. 2.2.
Tower Mounted
Amplifier
High Power Duplexer
and BIAS-T
HPDU
BS-240/241
TMA
DUBIAS
45