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Algorithms and Tools
Published in Hamidreza Ahmadian, Roman Obermaisser, Jon Perez, Distributed Real-Time Architecture for Mixed-Criticality Systems, 2018
where [va,vb].mT $ [v_a, v_b].mT $ is the macrotick in nanoseconds and [va,vb].δt $ [v_a, v_b].\delta _{t} $ is the transmission delay on the wire for one bit. The macrotick is the time-line granularity of the physical link, resulting from e.g.,hardware properties or design constraints. Typically, the TTEthernet time granularity is around 60ns [168] but larger values are commonly used. The transmission delay refers to the propagation of a bit on the medium, and depends on the link length and the link medium, i.e., copper or fiber.
Communications Systems
Published in Stuart Borlase, Smart Grids, 2018
Mehrdad Mesbah, Sharon S. Allan, Donivon D. Hettich, Harry Forbes, James P. Hanley, Régis Hourdouillie, Marco C. Janssen, Henry Jones, Art Maria, Mehrdad Mesbah, Rita Mix, Jean-Charles Tournier, Eric Woychik, Alex Zheng
IEEE C37.118 PMU communication standard defines the exchange of synchronized phasor measurements used in power system applications. It was first published in 1995 (revised in 2006). A synchronized phasor measurement, or synchrophasor, is produced by a PMU (Phasor Measurement Unit), and represents the magnitude and phase angle of a measured voltage or current waveform. PMUs distributed across the electric grid produce synchronized measurements that are time stamped. As of today, IEEE C37.118 is primarily used for WAMPAC applications. The IEEE C37.118 standard defines the communication rules for a single PMU, or a PMU data aggregator, called PDC (Phasor Data Concentrator). Synchronization of measurement time stamps of PMUs and transmission delays are two important challenges in the protocol. The synchronization aspect is currently handled through the integration of a GPS receiver directly into the PMU at each measurement site. In the future, IEEE 1588 should be able to provide the required synchronization needs through the communications network and, therefore, remove the need for a GPS receiver in PMU devices. The transmission delay challenge depends highly on the network communication topology, number of communications switches in cascade, length, and type of communication links, etc.
Smart Grid Technologies
Published in Stuart Borlase, Smart Grids, 2017
The IEEE C37.118 standard defines the communication rules for a single PMU, or a PMU data aggregator, called PDC (Phasor Data Concentrator). Due to the distributed nature of the measurement points across the network, IEEE C37.118 has to be implemented on top of a routable protocol such as TCP/IP or UDP/IP. To ensure the success of applications based on IEEE C37.118, two main challenges have to be addressed: (1) synchronization of the measurement points or PMUs and (2) transmission delays. The synchronization aspect is currently handled through the integration of a GPS receiver directly into the PMU. In the future, IEEE 1588 should be able to provide the required synchronization needs through the communications network and therefore remove the need for a GPS receiver in PMU devices. The transmission delay challenge depends highly on the network communication topology, that is, number of switches, length and type of links, etc. However, a common practice is to sacrifice the reliability characteristic of TCP by implementing IEEE C37.118 over UDP.
Performance analysis of LT code-based HARQ error control in underwater acoustic sensor networks
Published in Journal of Marine Engineering & Technology, 2022
P. Kaythry, R. Kishore, V. Nancy Priyanka
Figure 6 depicts the delay experienced by proposed scheme in comparison with RBLC and RLTC codes for different number of nodes in the network. As the number of nodes increases, recovery of data packets becomes a critical issue, as all the encoded packets are required in the intermediate nodes in the case of RBLC and RLTC. In RBLC, successful data packet recovery at the receiver side totally depends on the encoded packets with redundant bits. If retransmissions are more in RLTC, then the delay incurred will also be high. RLTCH makes use of ARQ, which is helpful in error-prone channel with a reduced number of retransmissions for recovery in lesser time. Distance between the nodes is also a deciding factor of transmission delay, as the hop distances vary, bandwidth available will decreases at the cost of an increase in the delay value.
Adaptive relay co-ordination scheme for radial microgrid
Published in International Journal of Ambient Energy, 2022
Belwin J. Brearley, R. Raja Prabu, K. Regin Bose, V. Sankaranarayanan
The speed of data transmission depends on communication channel bandwidth and transmission medium (copper wire, fibre optic). The delay caused because of communication channel bandwidth is known as transmission delay. The delay caused because of transmission medium is known as propagation delay. Transmission delay is calculated as the ratio data packet size to link bandwidth.
Minimum and maximum packets’ delays determination for communication flows’ delays jitters computation
Published in Australian Journal of Electrical and Electronics Engineering, 2023
Each packet transmitted by a source host is routed to the destination host through a series of intervening nodes; therefore, the end-to-end delay of the path traversed by the packets is the sum of the delays experienced at each hop on the path (Bolot 1993). Each of these delays consists of two components (Bolot 1993; Ming-Yang, Rong, and Huimin 2004; Mesbahi and Dahmouni 2016): a fixed component, consisting of the transmission delay at a node plus the propagation delay on the link to the succeeding node, and a variable component, consisting of the processing delay at a node plus the queuing delay at the same node. The transmission delay is the time needed to transmit a packet; in other words, it is the time interval between when the first bit of a packet is emitted by a node and when the last bit of the same packet is emitted by the same node. The propagation delay of a packet is the time interval between when the last bit of the packet is emitted at a link’s head node and the time when it is received at the link’s tail node. A packet’s processing delay at a nodal device is the time required for the nodal device to process and switch the packet (Mesbahi and Dahmouni 2016; Alassane et al. 2016; Comer 2004). Included in the processing delay are the time required by the device to perform error detection and the recognition of address and the time needed to transfer the packet to the output queue (Sodhro et al. 2019). The queuing delay of a packet is the time between when the packet is placed in a queue for transmission and when it starts being emitted from the node. During the time when a packet incurs queuing delay, it waits for other packets that were queued before it to be transmitted (Comer 2004). However, propagation delay is in general small when compared to transmission and queuing delays (Edward, Christopher, and Keith 2018) and, it can be neglected in computing delays for even wide area networks (Forouzan 2008; Sodhro et al. 2019). Therefore, in this paper, we concern ourselves with the processing, queuing and transmission delays at nodes and neglect inter-nodal links’ propagation delays. Being able to compute nodal devices’ (switches or routers) PDUs’ or Protocol Data Units’ (for example, packets, in packet-switched networks, cells in ATM, that is, Asynchronous Transfer Modes networks) maximum and minimum delays, together with knowing the number of nodes from the origin of a traffic stream to its destination, will make the computation of the maximum and minimum end-to-end delays of the packets in the stream possible; therefore, jitter computation for mitigation purposes, as explained in Figure 2, becomes a possibility.