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.

Multi-User Preemptive Scheduling For Critical Low Latency Communications in 5G Networks

Abstract: 5G new radio is envisioned to support three major service classes: enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine type communications. Emerging URLLC services require up to one millisecond of communication latency with 99.999% success probability. Though, there is a fundamental trade-off between system spectral efficiency (SE) and achievable latency. This calls for novel scheduling protocols which cross-optimize system performance on user-centric; instead of network-centric basis. In this paper, we develop a joint multi-user preemptive scheduling strategy to simultaneously cross-optimize system SE and URLLC latency. At each scheduling opportunity, available URLLC traffic is always given higher priority. When sporadic URLLC traffic appears during a transmission time interval (TTI), proposed scheduler seeks for fitting the URLLC-eMBB traffic in a multi-user transmission. If the available spatial degrees of freedom are limited within a TTI, the URLLC traffic instantly overwrites part of the ongoing eMBB transmissions to satisfy the URLLC latency requirements, at the expense of minimal eMBB throughput loss. Extensive dynamic system level simulations show that proposed scheduler provides significant performance gain in terms of eMBB SE and URLLC latency.

Age-Delay Tradeoffs in Single Server Systems

Abstract: Information freshness and low latency communication is important to many emerging applications. While Age of Information (AoI) serves as a metric of information freshness, packet delay is a traditional metric of communication latency. We prove that there is a natural tradeoff between the AoI and packet delay. We consider a single server system, in which at most one update packet can be serviced at a time. The system designer controls the order in which the packets get serviced and the service time distribution, with a given service rate. We analyze two tradeoff problems that minimize packet delay and the variance in packet delay, respectively, subject to an average age constraint. We prove a strong age-delay and age-delay variance tradeoff, wherein, as the average age approaches its minimum, the delay and its variance approach infinity. We show that the service time distribution that minimizes average age, must necessarily have an unbounded-second moment.

Ending the Anomaly: Achieving Low Latency and Airtime Fairness in WiFi

Abstract: With more devices connected, delays and jitter at the WiFi hop become more prevalent, and correct functioning during network congestion becomes more important. However, two important performance issues prevent modern WiFi from reaching its potential: Increased latency under load caused by excessive queueing (i.e. bufferbloat) and the 802.11 performance anomaly. To remedy these issues, we present a novel two-part solution: We design a new queueing scheme that eliminates bufferbloat in the wireless setting. Leveraging this queueing scheme, we then design an airtime fairness scheduler that operates at the access point and doesn't require any changes to clients. We evaluate our solution using both a theoretical model and experiments in a testbed environment, formulating a suitable analytical model in the process. We show that our solution achieves an order of magnitude reduction in latency under load, large improvements in multi-station throughput, and nearly perfect airtime fairness for both TCP and downstream UDP traffic. Further experiments with application traffic confirm that the solution provides significant performance gains for real-world traffic.We develop a production quality implementation of our solution in the Linux kernel, the platform powering most access points outside of the managed enterprise setting. The implementation has been accepted into the mainline kernel distribution, making it available for deployment on billions of devices running Linux today.

Differentiated services code point mirroring for wireless communications

Abstract: The DSCP Mirroring System enables the automatic reuse of the Differentiated Services Code Point header by the user devices that are served by a network to enable delivery of wireless services to the individually identified user wireless devices and manage the various data traffic and classes of data to optimize or guarantee performance, low latency, and/or bandwidth without the overhead of the management of the Differentiated Services Code Point header.