User's Manual

Table Of Contents
106 Operation
Chapter 4 - Operation and Administration
For 5 MHz bandwidth and AU Minimum Allocation of 5 Symbols, UL-DL Ratio
of 65-35 is not supported for Maximum Cell Radius of 40 KM or higher.
These combination will be rejected by the device, and a suitable trap will be
issued. For all other combinations of Bandwidth and AU Service Type, all DL-UL
Ratios are supported for all values of Maximum Cell Radius.
The default is 50-50 (%).
A change in the configured DL-UL Ratio is applied only after reset.
4.5.2.7 Synchronization
The Synchronization menu includes the following options:
“Clock
“Chain
“GPS Info
4.5.2.7.1 Clock
The Clock parameters define the source for the main clocks in the system. These
parameters are applied after reset. The Clocks menu enables viewing/updating
the following parameters:
4.5.2.7.1.1 External 1PPS Clock
The 1PPS (Pulse Per Second) clock is used to determine the air-frame start time.
Assuming that all systems use the same air-frame size and DL/UL Ratio, then,
when the 1PPS clock is received from a GPS system, this mechanism ensures
inter-site and intra-site synchronization among all sectors, preventing cross
interference and saturation problems. When using the internal 1PPS clock
(derived from the selected 16 MHz clock source), only intra-site synchronization
among sectors can be achieved.
The available options are Enable (use external 1PPS clock source) and Disable
(use internal 1PPS clock source derived from the selected 16 MHz clock).
The default is Enable.
CAUTION
The DL-UL Ratio of all Base Stations in the same coverage area (neighboring cells) must be set to
the same value to ensure optimal performance and avoid uplink saturation.