Background

A leading Scandinavian telecommunications company was experiencing problems with leased lines taking traffic to a GSM base station, resulting in their customers being unable to make mobile calls.

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 as the Telco was unable to prove to the provider of the core transmission that there was actually a problem. They were repeatedly told that since no alarms were evident, there was therefore no problem.

Solution

Telco trialled Chronos’ SyncWatch, both with and without GPS, at the edge of their 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 during the early hours of the morning, a major synchronisation problem was detected and successfully captured by SyncWatch. This is unlikely to have been detected by manual/human methods.

This particular alarm had not been noticed by the management system for the NodeB 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.

Benefits

The evidence captured by SyncWatch was easily shared with all concerned, including the backhaul Partner, giving the Telco tangible proof that sync issues within the network were impacting upon the performance of a base station that was in turn affecting service quality. Traditional synchronisation testing with expensive standalone test equipment and the constant presence of a trained sync test engineer would not cost-effectively deliver this important capability.

The Telco was able to justify investment in a number of SyncWatch probes based on the evidence seen with one unit. The deployment of the probes across the networks will allow the Telco to ’see’ sync events that may ripple out from a root cause that lies higher in the network hierarchy.

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