Title :
Analysis of synchronization algorithms with time-out control over networks with exponentially symmetric delays
Author :
Abdel-Ghaffar, Hisham S.
Author_Institution :
Network Wireless Syst. Group, Lucent Technol., Whippany, NJ, USA
fDate :
10/1/2002 12:00:00 AM
Abstract :
We study the performance of a class of time-offset estimation algorithms for synchronization of master-slave nodes based on asynchronous transfer of timing cells when GPS is not used. We implement a synchronization control mechanism based on cell acknowledgment time-out (TO) with wait or no wait options. We analyze the mechanism reliability and performance parameters over symmetric links using an exponential cell delay variation model. We show that the maximum-likelihood offset estimator does not exist for the exponential likelihood function. We analytically provide RMS error result comparisons for five ad hoc offset estimation algorithms: the median round delay, the minimum round delay, the minimum link delay (MnLD), the median phase, and the average phase. We show that the MnLD algorithm achieves the best accuracy over symmetric links without having to impose a strict TO control, which substantially speeds up the algorithm. We also discuss an open-loop estimation updating mechanism based on standard clock models.
Keywords :
delays; maximum likelihood estimation; phase estimation; synchronisation; telecommunication control; telecommunication networks; RMS error; asynchronous transfer; average phase; cell acknowledgment time-out; downlink delays; exponential cell delay variation model; exponential likelihood function; exponentially symmetric delays; master-slave nodes; maximum-likelihood offset estimator; median phase; median round delay; minimum link delay; network synchronization; open-loop estimation updating mechanism; performance parameters; phase estimation algorithms; reliability; standard clock models; symmetric links; synchronization algorithms; synchronization control; time-offset estimation algorithms; time-out control; timing cells; uplink delays; Algorithm design and analysis; Delay estimation; Error analysis; Global Positioning System; Master-slave; Maximum likelihood estimation; Performance analysis; Phase estimation; Synchronization; Timing;
Journal_Title :
Communications, IEEE Transactions on
DOI :
10.1109/TCOMM.2002.803979