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Cooperative transmission (CT) enables balanced energy consumption among sensor nodes and mitigates the energy hole problem in wireless sensor networks (WSNs). In typical CT enabled medium access control (MAC) protocols, a source node decides to trigger CT or not based on a residual energy comparison between itself and its relay node. In this paper, we propose a receiver initiated CT MAC protocol,...
Overhearing and idle listening are two primary sources for unnecessary energy consumption in wireless sensor networks. Although introducing duty cycling in medium access control (MAC) reduces idle listening, it cannot avoid overhearing in a network with multiple contending nodes. In this paper, we propose an event-triggered sleeping (ETS) mechanism for synchronous duty-cycled (DC) MAC protocols in...
Synchronized duty cycling (DC) aligns sensor nodes to wake up at the same time in order to reduce idle listening for medium access control (MAC) in wireless sensor networks (WSNs). Demand wakeup MAC (DW-MAC) is a popular synchronous DC MAC protocol which allows nodes to compete and transmit multiple packets in one operational cycle. This multiple packet transmission (MPT) feature makes DW-MAC more...
A dynamic error-feedback controller is presented for the synchronized output regulation of heterogenous linear networked systems, where only the leader node has the information of the regulated errors while the remaining follower nodes have the information of the relative output errors with respect to their in-neighboring nodes. By using the small-gain theorem, the sufficient criterion is developed...
Clock synchronization is becoming an increasingly important characteristic of modern wide area monitoring and control systems such as the power grid. It provides an opportunity to coordinate control actions and measurement instants across hundreds of miles and numerous network topologies. Devices and networks have advanced to a point where synchronization across a wide area can be achieved within...
The paper presents different test methods for PMU (Phasor Measurement Unit) during transients in detail and shows practical results from tests of PMU from various vendors. The authors emphasize transients, because the measurement of stationary signals and their accuracy is already defined in IEEE C37.118. However, with the exception of step functions no dynamic signals are considered. The results...
Practical implementations in distributed model based control face a fundamental trade-off between model complexity and the number of modeled nodes. For linear systems, higher order models better capture the behavior of the system at higher frequencies, but the effective operating frequency range is limited during implementation due to sensor/actuator bandwidth limits, control algorithm limits and,...
Wide-area monitoring (WAM) applications for power distribution rely on accurate global time synchronization. Furthermore, there is interest in replacing current time synchronization methods such as Inter Range Instrumentation Group (IRIG), with distributed time synchronization protocols that utilize the data communication lines eliminating the need for dedicated timing signals within the substation...
With the increasing use of Ethernet for real-time control of distributed dynamic systems, and inexpensive processing power at the sensor and actuator nodes, there is a growing interest in the process control community to move towards “model based” distributed control. Prior work shows that the lack of precise time synchronization is a critical hindrance to reliable model generation or estimation in...
Single photons at 1.04 μm were converted to the visible region by sum-frequency generation with a synchronized pumping beam at 1.55 μm and the maximum detection efficiency was reached 27.6%.
Shrinking process tolerances due to decreasing device sizes and increasing chip complexity in semiconductor manufacturing are motivating efforts to improve methods of equipment data acquisition (EDA). Prior work shows that the lack of precise time-stamping and clock synchronization is a critical hindrance to reliable data acquisition and real-time process control systems. The ultimate goal in the...
This paper presents two MAC strategies for multi-hop cognitive radio networks in single radio multi-channel cases. Both strategies use one of the idle multiple channels for communication among secondary users, and the network will leave the current channel and jump to another channel as a group if any primary user appears. The first strategy is based on a pre-defined pattern that will always tune...
This paper addresses preamble-based low complexity synchronization, channel estimation and equalization for Zero-padded (ZP) MB-OFDM based UWB systems. The proposed synchronization method consists of sync detection, coarse timing estimation, fine timing estimation, and oscillator frequency offset estimation. The distinctive features of MBOFDM systems and the interplay between the timing and carrier...
Orthogonal frequency division multiplexing (OFDM) is an effective modulation technique for high-rate transmission over frequency selective fading channels. However, just because of its orthogonality, OFDM systems are also extremely sensitive and vulnerable to synchronization errors. In this paper, we investigate a scheme especially for symbol synchronization utilizing the special training structure,...
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