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SYNCWATCH A Case Study in Fault Detection on Network Timing
By Charles Curry, Managing Director - Chronos Technology Ltd
A leading Scandinavian Telecommunications Company was experiencing problems with leased lines taking traffic to a GSM base station. This was resulting in customers being unable to make calls from their mobile phones through that base station.
The Telco had tried to isolate the problem for several months using traditional test equipment and techniques. As with many synchronisation problems, the events were unpredictable and as such very difficult to capture. This was proving very costly and a waste of valuable resource. The Telco was also unable to prove to the third party operator providing the core transmission that there was actually a problem. They were repeatedly told that since no alarms were evident, there must be no problem.
Chronos' SyncWatch Probes in both ‘standard' and ‘reference' configurations were deployed. The ‘reference' Probe was deployed at the edge of the network to indicate performance to both 2G and 3G (BTS/NodeB) sites by comparing the leased line timing with a local GPS based reference. The network was monitored for three weeks with no major anomalies then, out of the blue early one morning a major synchronisation problem was detected and successfully captured by SyncWatch. This is unlikely to have ever been detected by manual/human testing methods.
This particular alarm had not been noticed by the management system for the Node B network because the relevant alarm had been configured for a different alarm queue and it was only through the use of SyncWatch that the problem was flagged and ultimately fixed.
The hard evidence produced by SyncWatch was easily shared with everyone who needed to see it including the backhaul partner. This gave the operator the tangible proof he required that sync issues within the network were impacting the performance of a base station that was in turn affecting service quality.
The operator was able to justify the investment in a number of SyncWatch Probes based on the evidence seen with one unit. The deployment of the probes across the network will allow the operator for the first time to ‘see' sync events that may ripple out from a root cause that lies deeper in the network hierarchy.
Traditional synchronisation testing with expensive stand alone test equipment and the constant presence of a trained sync test engineer would probably not have captured this non-systematic event, and certainly not cost effectively.
For more information: Chronos Technology Tel: 01594 862227
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