User manual

AP User Manual January 2004
Software Release 4.1
3.3 SYNCHRONIZATION
The CMM is a critical element in the operation of the Canopy system. At one AP cluster site or
throughout an entire wireless system, the CMM provides a GPS timing pulse to each module,
synchronizing the network transmission cycles.
3.3.1 Unsynchronized Modules
Without this pulse, an AP is unsynchronized, and a BH timing master cannot synchronize a BH
timing slave. An unsynchronized module may transmit during a receive cycle of other modules.
This can cause one or more modules to receive an undesired signal that is strong enough to make
the module insensitive to the desired signal (become desensed).
3.3.2 Passing Sync
In releases earlier than Release 4.0, network sync can be delivered in only one over the air link in
any of the following network designs:
• Design 1
1. A CMM provides sync in Ethernet protocol to a collocated AP.
2. This AP sends the sync in multipoint protocol over the air to SMs.
• Design 2
1. A CMM provides sync in Ethernet protocol to a collocated BH timing master.
2. This BH timing master sends the sync in point-to-point protocol over the air to a BH
timing slave.
In Release 4.0 and later releases, network sync can be either delivered as described above or
extended by one additional link in any of the following network designs.
NOTE: In each of these following designs, Link 2 is not on the same frequency band as
Link 4. (For example, Link 2 may be a 5.2-GHz link while Link 4 is a 5.7- or 2.4-GHz link.)
• Design 3
1. A CMM provides sync in Ethernet protocol to a collocated AP.
2. This AP sends the sync in multipoint protocol over the air to an SM.
3. This SM delivers the sync in Ethernet protocol to a collocated AP.
4. This AP passes the sync in multipoint protocol in the additional link over the air to
SMs.
This design is illustrated in Figure 1.
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