Latency (engineering)

About: Latency (engineering) is a research topic. Over the lifetime, 3729 publications have been published within this topic receiving 39210 citations. The topic is also known as: lag.

Corrigendum to “The IX Operating System: Combining Low Latency, High Throughput and Efficiency in a Protected Dataplane”

Abstract: On page 21 of “The IX Operating System: Combining Low Latency, High Throughput and Efficiency in a Protected Dataplane” we describe our use of the tool mutilate to evaluate the latency and throughput of memcached. We discovered an error in our setup: we did not load the initial key-value state into memcached before the start of the experiment. Instead, memcached started in an empty state, causing some GET requests to require less computation than intended. Table 1 shows the performance differences between our original and corrected memcached results.

Reliable Energy Aware Multi-token Based MAC Protocol for WSN

Abstract: Wireless sensor networks (WSNs) have accelerated tremendous research efforts with an aim to maximize the lifetime of battery-powered sensor nodes and, by extension, the overall network lifetime. With an objective to prolong the lifetime of WSN, reducing energy consumption turns out to be the most crucial factors for almost all WSN protocols, particularly for the MAC protocol that directly ensures the state of the main energy consumption component, i.e., the radio module. In order to minimize energy consumption, RMAC and HEMAC protocols allow a node to transmit data packets for multi-hop WSN in a single duty-cycle. At the same time, each node remains in low power sleep mode and wakes up periodically to sense for channel activities, i.e., data transmission. But, in token based MAC protocol, depending on the token availability, there is always an end-to-end communication between source and sink one at a time, still it would have high latency time. Hence, different MAC protocols for WSN always have greater challenges towards energy conservation, maintaining low latency time, and fault-tolerant to node failure. To overcome these problems, we present an energy efficient multi-token based MAC protocol that not only extend the network lifetime and maintain the network connectivity but also achieve congestion less, fault-tolerant and reliable data transmission. Simulation studies of the proposed MAC protocol have been carried out using Castalia simulator, and its performance has been compared with that of SMAC, RMAC, and token based MAC protocol. Simulation results also show that the proposed approach has lower energy consumption and higher delivery ratio.

On Reliable Dissemination in Wireless Ad Hoc Networks

Abstract: Reliable broadcast is a basic service for many collaborative applications as it provides reliable dissemination of the same information to many recipients. This paper studies three common approaches for achieving scalable reliable broadcast in ad hoc networks, namely probabilistic flooding, counter-based broadcast, and lazy gossip. The strength and weaknesses of each scheme are analyzed, and a new protocol that combines these three techniques, called RAPID, is developed. Specifically, the analysis in this paper focuses on the trade-offs between reliability (percentage of nodes that receive each message), latency, and the message overhead of the protocol. Each of these methods excel in some of these parameters, but no single method wins in all of them. This motivates the need for a combined protocol that benefits from all of these methods and allows to trade between them smoothly. Interestingly, since the RAPID protocol only relies on local computations and probability, it is highly resilient to mobility and failures and even selfish behavior. By adding authentication, it can even be made malicious tolerant. Additionally, the paper includes a detailed performance evaluation by simulation. The simulations confirm that RAPID obtains higher reliability with low latency and good communication overhead compared with each of the individual methods.

NUM-Based Fair Rate-Delay Balancing for Layered Video Multicasting over Adaptive Satellite Networks

Abstract: Trading delay and rate in upcoming satellite networks are of paramount interest. In this paper, we present a solution to optimally distribute resources across MAC, IP and APP layers to deal with the problem of efficiently and reliably delivering low latency and high rate inelastic services over such networks. In order to do so, we formulate the problem of rate/delay balancing according to a Network Utility Maximization (NUM) paradigm assuming Scalable Video Coding (SVC) feeding a cross-layer DiffServ architecture, and an adaptive physical layer. We solve not only the bit loading balancing across the IP queues but also the video layers distribution to be sent among the adaptive physical layers, all constrained by delay requirements. The solution, which provides a fair rate-delay trade-off, happens to be on a water filling load across the queuing architecture, and it is suitable for multicasting scenarios. Finally, we propose a full protocol design, implementation, and performance evaluation based on truly available standardized tools, hence, it is ready-to-use. Our solution significantly outperforms non cross-layer approaches in terms of delay and video quality, and it dynamically adapts to channel and traffic variations.

Performance evaluation of layer 3 low latency handoff mechanisms

Abstract: This paper investigates the performance of two Layer 3 low latency handoff mechanisms proposed by the IETF, namely Pre- and Post-Registration. These protocols use Layer 2 triggers to reduce the built-in delay components of Mobile IP. We propose a simple analytical model that allows assessing the packet loss and the delay characteristics of these mechanisms. We describe several handoff implementations over a wireless access based on the IEEE 802.11 standard and analyze several implementation issues. Finally we study the scalability of the protocols using an OPNET simulation.