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J-Series Data Radio – User Manual
SmartPath™ PTMP using LinkXtend™ Bridges
SmartPath™ allows the user to create multiple redundant connection paths in complex PTMP systems using LinkXtend™ bridges. Consider the
PTMP with LinkXtend™ network shown below. The system designer requires that each unit synchronises to the network as quickly as possible,
even if the topology is not initially the preferred one. Over time the network needs to resolve itself to match the preferred topology.
Similar to the previous example, each Bridge or Remote in the network is configured to associate with multiple Access Points. Due to the split
personality of the Bridge (Half-Access Point/Half-Remote) each Bridge site in the network is capable of providing an alternative path to the Access
Point for any other radio in the network.
The system designer can configure a preferred Access Point, but may also specify up to three alternatives should the preferred Access Point fail.
The alternative Access Points for a specific site would be any other Access Point or Bridge radios that have adequate signal strength. All sites
that need to provide alternative paths should be configured as Bridges. The Bridges can be single or dual antenna bridges depending on RF
requirements.
The use of SmartPath™ preferred/alternative mode ensures that during normal operation, the network remains in the optimum or preferred
topology. This assists the network designer in balancing connectivity vs latency. Only during a failure of a site in the preferred topology will other
sites that are dependent on that failed site need to reacquire alternative paths. When operating via alternative paths, the user may observe an
increase in response time (ie: increase latency due to the larger number of hops via bridges). In SCADA and Telemetry applications this is a much
preferred outcome as opposed to total loss of remote site connectivity.
Access Point Re-Acquisition Time
SmartPath™ is optimized to provide remote synchronisation (ie: connectivity) as quickly as possible. This is important for SCADA systems where
minimization of outage time is critical. In order to provide synchronisation as quickly as possible, a Remote configured for SmartPath™ will
synchronise to the first available Access Point (or Bridge) it can find, regardless of whether or not that Access Point (or Bridge) is the preferred
unit. The time taken to find an available Access Point (or Bridge) will depend on the hopping interval. Smaller hopping intervals will result in faster
synchronisation times. A more detailed discussion on hopping intervals can be found in Part D of this User Manual.
On startup, if a Remote synchronises to its preferred Access Point (or bridge) first, then it will remain synchronised unless a loss of signal from the
Access Point (or Bridge) occurs.
However, if the Remote synchronises to an alternative Access Point (or Bridge) first, it will remain synchronised to the alternative Access Point (or
Bridge) for a limited length of time. This time is specified in the “Access Point Reacquisition Time” configuration parameter. This time is normally
10 to 30 minutes but can be configured from 1 to 255 minutes. When the time expires, the Remote will automatically de-synchronise and look for
another Access Point.
The Remote is not guaranteed to find the preferred Access Point on first attempt, but statistical variation will ensure that eventually the Remote
will find it’s preferred Access Point if it’s signal can be received. Once found, the Remote will no longer search for any other Access Point. This
mechanism provides the best balance between connectivity and orientation of the network topology in preferred way. Over time, the network
resolves itself to match the user defined preferred topology.
Содержание JR240
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