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Zinwave 3000 DAS support for MIMO servicesWhitepaper
The next generation of high data-rate services such as WiMAX and
LTE provide various MIMO options.
Where base-stations (BTS) are deployed to provide in-building
coverage these options can be used to increase
the overall capacity or coverage of the system.
Typically BTS signals are distributed inside buildings via a
Distributed Antenna System (DAS) which has multiple
antenna locations to provide multiple copies of each signal. In
the case of MIMO each antenna location will
require 2 or more independent signals from the same BTS. The
figure below shows a comparison between the
3000 DAS architecture required to support a traditional single
signal (SISO) BTS and a dual-transceiver
(MIMO) BTS:
www.zinwave.com
Secondary Hub
ZANT Antenna
Remote Unit
R X
SISO BTS
T X
Primary Hub
Secondary Hub (1)
ZANT Antenna
ZANT Antenna
Remote Unit (1)
Remote Unit (2)
Secondary Hub (2)
R X 1
R X 2
T X 1
T X 2
MIMO BTS
Primary Hub
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The following considerations should be taken into account when
implementing a MIMO architecture with the
3000 DAS:
The separation between the dual-port antennas at the same
location needs to be sufficient to
provide both MIMO diversity (using guidelines provided by the
BTS manufacturer) and TX-RXisolation. Each ZANT antenna provides at
least 40dB of isolation between the TX and RX ports of
the same remote unit and the separation must provide the same or
better isolation between TX and
RX ports of remote units 1 and 2.
The difference between the two path distances between the BTS
and the two ZANT antennas at
any given location must be within the guidelines provided by the
BTS manufacturer. This can be
typically ensured by connecting the primary hub(s) to the
secondary hubs and the secondary hubs
to the remote units by multi-core fibres with the same length
patch cords. Ideally the ZANT antennas
should also be connected directly to the remote units using
their integrated flying leads.
In the diagram only a single antenna location is shown but the
architecture can be extended to multiple
secondary hubs (up to 8 per primary hub) and multiple remote
units (up to 8 per secondary hub). The MIMO
architecture shown can support up to 32 antenna locations per
primary hub and up to 4 independent MIMO
signals (although only 2 signals are shown). If more MIMO
signals are required or more than 32 antenna
locations per primary hub are required then an alternative
architecture can be deployed as shown in the
figure below:
Secondary Hub (1)
ZANT Antenna
ZANT Antenna
Remote Unit (1)
Remote Unit (2)
Secondary Hub (2)
R X 1
R X 2
T X 1
T X 2
MIMO BTS
Primary Hub (1)
Primary Hub (2)
