User's Manual

Exalt Installation and Management Guide
ExtendAir
®
(TDD) Series Direct Mount
000000-001 11
2011-08-26
• User password = password
• VLAN disabled
Radio Synchronization
The radio synchronization feature improves the performance of Exalt radios operating in the same
frequency band and that are collocated (such as in repeater and hub configurations). Radio
synchronization ties radio systems together to operate off of a common clock system, ensuring that all
radios simultaneously transmit and receive, and thus eliminating near-field interference issues and
related radio system coupling.
Synchronization Modes
Synchronization can be implemented using either one or multiple GPS sources, or using the radios
'Internal' clocking signal. The following general configurations can be accommodated:
• GPS sync, using one GPS source (sold separately) per link. Ideal for links where the radios are not
collocated on the same rooftop or tower.
• GPS sync, using one GPS source (sold separately) to drive timing to multiple collocated links,
using one or more sync distribution accessories (sold separately). The ideal solution for networks
that have multiple links at one location, but also have more nearby radio links that are not
collocated, including repeaters and multi-link backbones.
• Internal sync, using one radio to synchronize another collocated link. This can be accomplished
with a simple cable and proper radio configuration, and ideal when only 2 radios are collocated.
• Internal sync, using one radio to synchronize to multiple collocated links. This can be
accomplished with one or more sync distribution accessories (sold separately). The ideal solution
for networks that have multiple links at one location and do not have other nearby links or
repeaters and multi-link backbones.
Virtually any combination of hubs and repeater sites, star configurations, and/or backbones can be
implemented with synchronization. It is typically necessary or ideal in each configuration to match the
following parameters on every radio in the network:
• Link Distance – Match to the longest distance link in the network.
• Frame Length – Match to the lowest frame length to optimize total system latency (for example,
for TDM networks) or match to a highest frame length to optimize user throughput. Choose an
intermediate value to compromise between latency and throughput.
• Mode – It is desirable, but not always necessary, to match the mode for all collocated links.
• Bandwidth – It is desirable, but not always necessary, to match the bandwidth for all collocated
links.
For complex networks, an Exalt engineer should review multi-link networks before deployment as
several factors can optimize the network for desired performance.
Figure 3illustrates two separate radios benefiting from synchronized GPS sources.
Note: When GPS Sync is enabled, link initiation typically takes 1 to 3 minutes to allow for
the radio to properly synchronize to the available GPS satellites.