Holdover in synchronization applications: Difference between revisions

Revision as of 20:51, 12 September 2011

Revision as of 20:54, 12 September 2011

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A key application for GPS in [[Synchronization in telecommunications]] is to provide synchronization in wireless basestations. Base stations depend on timing to operate correctly, particularly for the handoff that occurs when a user moves from one cell to another.<ref>http://www.gmat.unsw.edu.au/snap/publications/khan&dempster2007b.pdf</ref> In these applications holdover is used in base stations to ensure continued operation while GPS is unavailable and to reduce the costs associated with emergency repairs, since holdover allows the site to continue to function correctly until maintenance can be performed at a convenient time.<ref>http://www.eetimes.com/design/communications-design/4213947/Understanding-the-concepts-of-synchronization-and-holdover</ref>

Some of the most stringent requirements come from the newer generation of wireless base stations, where phase accuracy targets as low as 1&musmu;s need to be maintained for correct operation.<ref>http://www.telecom-sync.com/pdf/2008/Day1/WCDMA_and_LTE_Synchronisation_Aspects_(Stefano_Rufini,_Ericsson).pdf</ref> However the need for accurate timing has been an integral part of the history of wireless communication systems, and it has been suggested that the search for reliable and cost effective timing soluctions was spurred on by the need for CDMA to compete with lower cost solutions.<ref>http://www.4timing.com/SyncGPS.pdf</ref>

Within the base station, besides standard functions, accurate timing and the means to maintain it through holdover is vitally important for services such as [[E911]]<ref>http://www.eetimes.com/design/communications-design/4213947/Understanding-the-concepts-of-synchronization-and-holdover</ref>