Redline Communications Inc. SC1000E Manuale Utente
User
BASE
STATION
Manual
Doc #70-00100-01-00-DRAFT
Proprietary Redline Communications © 2009
Page 51 of 60
January 7, 2009
16 QAM 1/2
15.3 / 30.4
6.2 / 12.5
3.1 / 3.0
1.2 / 1.3
QPSK 3/4
7.6 / 15.3
4.7 / 9.4
1.5 / 1.5
0.9 / 0.9
QPSK 1/2
7.6 / 15.3
3.1 / 6.2
1.5 / 1.5
0.6 / 0.6
BPSK 1/2
3.9 / 7.6
1.6 / 3.1
0.8 / 0.8
0.3 / 0.3
7.11 GPS Synchronization
Important: To minimize inter-sector RF interference, synchronization must be
used to coordinate RF transmissions of base stations.
used to coordinate RF transmissions of base stations.
The IEEE 802.16 standard calls for the use of GPS (Global Positioning System)
receivers to provide the precise time reference for synchronization of WiMAX networks.
Operating in TDD mode, the base station and the subscribers transmit at the same
frequency, and require precise synchronization between downlink and uplink
transmissions. Proper coordination of these activities is required to minimize interference
and ensure the best overall system performance.
receivers to provide the precise time reference for synchronization of WiMAX networks.
Operating in TDD mode, the base station and the subscribers transmit at the same
frequency, and require precise synchronization between downlink and uplink
transmissions. Proper coordination of these activities is required to minimize interference
and ensure the best overall system performance.
The base station uses the GPS 1 PPS signal to set the frequency of the TCM onboard
clock. This TCM reference clock is used when broadcasting a radio frame
synchronization signal to all BBM and RRH modules. If the 1 PPS signal becomes
unavailable at any base station, that TCM enters 'holdover mode' to maintain the highest
accuracy until the GPS signal can be restored.
clock. This TCM reference clock is used when broadcasting a radio frame
synchronization signal to all BBM and RRH modules. If the 1 PPS signal becomes
unavailable at any base station, that TCM enters 'holdover mode' to maintain the highest
accuracy until the GPS signal can be restored.
GPS reference clock systems require that a receiver be placed at each base station and
that the GPS antenna have line-of-sight satellite access. Ideally, a GPS antenna should
be mounted on a rooftop with a full 360º view of the sky, but often an antenna mounted
on the side of a building or a tower with a 180º view of the sky is adequate.
that the GPS antenna have line-of-sight satellite access. Ideally, a GPS antenna should
be mounted on a rooftop with a full 360º view of the sky, but often an antenna mounted
on the side of a building or a tower with a 180º view of the sky is adequate.
The base station provides the following synchronization schemes.
Model 1 (Standard) – External GPS Unit
The GPS component is an integrated GPS receiver/antenna module. Signal input is
through an RS-232 cable connected to the Serial 1 port on the TCM front panel.
Recommended for short cable runs (~20m).
through an RS-232 cable connected to the Serial 1 port on the TCM front panel.
Recommended for short cable runs (~20m).
Figure 16: Spec.: External GPS Clock