User's Manual

2 Introduction
ID No: 159967 Page 11
2. INTRODUCTION
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 BTS. The configuration of a master unit
depends on the number of the remote units and the frequency range.
The optical transmission uses WDM-systems with a wavelength of 1550 nm in the
uplink and 1310 nm in the downlink.
2.2. THE MMR8/19
The fibre optic distribution system is designed for AMPS/PCS or iDEN/PCS services.
Up to two bands can be transmitted. In future applications each fibre will be 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.
An auto-levelling function for compensating different fibre losses and a
comprehensive supervision concept are implemented.
The remote unit MMR8/19 is connected to a central master unit through 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.