NETWORK BASED TIMING MECHANISMS TO SUPPORT PRECISE ALIGNMENT OF REAL-TIME STREAMS
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AbstractThe efforts to implement the distribution of real-time information streams via IP packet-based networks in the range environment have largely utilized the recovery of timing information via implicit techniques, such as adaptive clock recovery. These techniques allowed the alignment of streams with disparate delay characteristics to accuracies on the order of 1 millisecond. With the availability of techniques to distribute high accuracy timing information to network nodes, the capability to recover and align real time streams on the order of microseconds is possible. This paper will focus on a methodology to perform precision stream alignment that utilizes timestamping and the IEEE 1588 Precision Time Protocol (PTP) as a clock source. IEEE 1588 is currently utilized in cellular networks to deliver synchronization to remote network elements, providing superior accuracy and stability. The paper will review expectations for performance and discuss considerations in system level design to optimize timing distribution performance and ultimately stream alignment accuracy. System elements and their effect on performance will be identified and characterized. Finally, a TM Gateway implementation example which utilizes PTP coupled with hardwareassisted timestamping techniques to align recovered TM streams to a high degree of accuracy will be described. Real world results for clock accuracy and expectations for stream alignment accuracy will be shared.