2 Functional Description
Page 11
2. FUNCTIONAL DESCRIPTION
2.1. PURPOSE
Cellular telephone systems transmit signals in two directions between base
transceiver station (BTS) and mobile stations (MS) within the signal coverage area.
If weak signal transmissions occur within the coverage area because of indoor
applications, topological conditions or distance from the transmitter, extension of the
transmission range can be achieved by means of an optical distribution system.
Such a system contains an optical Master Unit and several Remote Units. The
number of the Remote Units depends on the hardware and software configuration.
The Remote Units are connected to the Master Unit with optical links. The optical
loss must be less than 10 dB inclusive optical couplers or splitters.
The Master Unit is the connection to the base transceiver stations. The configuration
of a Master Unit depends on the number of the Remote Units and the frequency
range.
WDM (Wave Division Multiplex) filters are integrated in the optical modules. For the
UL, a wavelength within 1540 nm - 1562 nm is used. For the DL, a wavelength of
1310 ±20 nm is used. The maximum output power for the UL and DL is 5.7 mW.
2.2. THE ION-M80/90/19P
The fibre-optic distribution system is designed for LMR and PCS services. Up to
three bands (LMR800, LMR900 and PCS1900) can be transmitted. Each fibre is able
to serve up to four Remote Units and to operate up to four providers. One Master
Unit can operate up to 124 Remote Units point-to-point plus 32 x 4 Remote Units in a
cascaded way.
An auto-levelling function for compensating different fibre losses and a
comprehensive supervision concept are implemented. Auto-levelling in DL works with
optical power measurement, in UL a 10.7 MHz signal is used for measuring the
optical loss. Thus a (“cascaded”) backbone structure can be used in the optical
network, i.e. up to four Remote Units can be connected to the Master Unit via only
one fibre and optical couplers.
The unit also provides a transparent link in the frequency range from 2496 MHz to
2690 MHz, which can be used e.g. for WiMAX applications in this frequency range.
The Remote Unit ION-M80/90/19P (Intelligent Optical Network; MMR) is connected
to a central Master Unit via optical-fibre lines. Specific customer designs for lamp
pole or wall mounting are available. Thus, the system provides many advantages in
view of easy site acquisition.
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