Precision Time Protocol

About: Precision Time Protocol is a research topic. Over the lifetime, 604 publications have been published within this topic receiving 6006 citations. The topic is also known as: PTP & IEEE 1588.

Realization of an Ethernet-based synchronous audio playback system

Abstract: A Dante network card and development template developed by Audinate were used as a platform for realizing an Ethernet synchronous audio playback system. A personal computer (PC) was connected to each Dante device through a switch hub and Ethernet cable PC to transmit sound before TAS3204EVM was applied in digital signal processing and EQ adjustment for application in a live music concert. The expensive wire and cable currently used in live music concerts can be replaced with an Ethernet cable, substantially reducing costs. To ensure that the Dante devices deliver sound simultaneously, an artificial delay was introduced to enable devices closer to the sound source to delay the playback time while devices farther from the sound source play back sound with the other devices. This study examined how the IEEE 1588 Precision Time Protocol can be used for clock correction to synchronize the sound of all devices. Zero Configuration Networking (ZCN) was used to enable the devices to obtain an Internet Protocol address, and the Multicast Domain Name System was employed to obtain the device names, thus ensuring that User Datagram Protocol control instructions can be correctly delivered to control interdevice channel connections.

New algorithm for IEEE 1588 time synchronization under the presence of significant delay variation

Abstract: Time synchronization is one of the basic services in a distributed network as it enables a lot of services, for example synchronized measurements or timeslot-based access to shared communication media. The IEEE 1588 defines the precision time protocol (PTP) that aims to synchronize multiple slave clocks to a master clock by means of synchronization event messages. Unfortunately, the accuracy of time synchronization strongly depends on delay variations produced by the underlying telecom network. Such behavior represents a strong issue, particularly considering the network consisting of devices that are not IEEE 1588 capable. A conventional clock servo will not provide enough accurate level of synchronization in the case of considerable delay variation. We develop a novel time synchronization algorithm that is based on a generic statistical approach and explicitly takes into account the stochastic properties of delay of PTP messages. Numerical simulations show that this algorithm is effective for estimation of the time offset between master and slave reliably, even under significant delay variations.

Scheduling in an Ethernet fronthaul network

Abstract: This paper investigates and compares the performance of different scheduling techniques in an Ethernet fronthaul network in the presence of both time-sensitive/high priority and background traffic streams. A switched Ethernet architecture is used as the fronthaul section of a cloud radio access network (C-RAN) and a comparison of two scheduling schemes, strict priority scheduling and time-aware shaping, is carried out. The different streams are logically separated using virtual local area network identifiers and contend for the use of trunk links formed between aggregator/switch nodes. The scheduling schemes are applied in the access and trunk ports in the fronthaul, and need to handle the queue management and prioritization of the different streams. In such cases, contention-induced latency variation has to be characterized, especially when the fronthaul transports precision time protocol traffic, as it directly leads to errors in timestamping. OPNET models for strict priority and time-aware schedulers have been built and employed, and simulation results are used to compare the performance of the two scheduling schemes.

Impact of PMU sychronization on wide area state estimation

Abstract: This paper investigates the impact of the PTP (Precision Time Protocol) synchronization method, used to synchronize different Phasor Measurement Units (PMUs), on a state estimation application. As a case of study, the output data of the PMUs, synchronized by means of a software-only implementation of the PTP, have been used to estimate the state of an IEEE 57-bus power system.

The Effect of Time Synchronization Error in LAN-Based Digital Substation.

Abstract: In this paper, the effect of time synchronization error on protection algorithms are studied for the usage of the LAN-based collaborative protection. In order to derive the effect of time synchronization, this paper proposes a substation model which is constructed with IEEE 1588 Precision Time Protocol (PTP) supported intelligent electronic devices. The proposed model is used as an example of a target platform to study the effect of time synchronization error with two typical substation protection algorithms, i.e., current differential-based substation protection and distance protection algorithms. From the analyzed and the simulated results, it was well observed that time synchronization error is a significant error-causing factor for both protection algorithms, resulting in erroneous detection of faults and erroneous estimation of fault distances, respectively. The results of research performed in this paper are expected to provide a good guide for constructing the future LAN-based digital power substation with precise time synchronization.