High Rate Links Research Articles

QUIC on the Fast Lane: Extending Performance Evaluations on High-rate Links

QUIC is a new protocol standardized in 2021 designed to improve on the widely used TCP/TLS stack. The main goal is to speed up web traffic via HTTP, but it is also used in other areas like tunneling. Based on UDP, it offers features like reliable in-order delivery, flow and congestion control, stream-based multiplexing, and always-on encryption using TLS 1.3.Unlike TCP, QUIC integrates these capabilities in user space, relying on kernel interaction solely for UDP. Operating in user space allows more flexibility but sacrifices some kernel-level efficiency and optimization that TCP benefits from. Various QUIC implementations exist, each distinct in programming language, architecture, and design.QUIC is already widely deployed on the Internet and has been evaluated, focussing on low latency, interoperability, and standard compliance. However, benchmarks on high-speed network links are still scarce.This paper presents an extension to the QUIC Interop Runner, a framework for testing the interoperability of QUIC implementations. Our contribution enables reproducible QUIC benchmarks on dedicated hardware and high-speed links. We provide results on 10G links, including multiple implementations, evaluate how OS features like buffer sizes and NIC offloading impact QUIC performance, and show which data rates can be achieved with QUIC compared to TCP. Moreover, we analyze different CPUs and CPU architectures influence reproducible and comparable performance measurements. Furthermore, our framework can be applied to evaluate the effects of future improvements to the protocol or the OS.Our results show that QUIC performance varies widely between client and server implementations from around 50Mbit/s to over 6000Mbit/s. We show that the OS generally sets the default buffer size too small. Based on our findings, the buffer size should be increased by at least an order of magnitude. Our profiling analysis identifies Packet I/O as the most expensive task for QUIC implementations. Furthermore, QUIC benefits less from AES NI hardware acceleration while both features improve the goodput of TCP to around 8000Mbit/s. The lack of support for NIC offloading from QUIC implementations results in missed opportunities for performance improvement.The assessment of CPUs from different vendors and generations revealed significant performance variations. We employed core pinning to examine if the performance of QUIC implementations is affected by the allocation to specific CPU cores. The results indicated an increased goodput of up to 20% when running on a specifically chosen core compared to a randomly assigned core. This outcome highlights the impact of CPU core selection on the performance of QUIC implementations but also for reproducible measurements.

Maximum Throughput First Access Point Selection Scheme for Multi-Rate Software-Defined Wireless Network

As the number of devices increases, many businesses deploy multiple access points (APs) in neighboring areas to provide Internet service. In such networks, a mobile station (MS) often has multiple APs within its coverage area, and deciding which AP to associate with becomes a significant issue that can influence network performance. Software Defined Network (SDN) has recently become a popular technology for making intelligent mobile station assignment decisions for APs. In a multi-rate Wi-Fi network, the actual bandwidth of high-rate links can be reduced to that of low-rate links. In this paper, we propose a Maximum Throughput First (MTF)AP selection scheme, which is a refinement of existing Mininet Wi-Fi mechanisms. MTF considers the parameters of actual throughput achieved by the access point and the number of associated stations as selection metrics when making the association decision. The simulation results show that MTF provides better performance, especially in multi-rate environments.

Optimal design of artificial bee colony based UAV routing (ABCUR) algorithm for healthcare applications

PurposeTo avoid this situation, the authors proposed an optimal artificial bee colony algorithm-based Unmanned Aerial Vehicle (UAV) routing algorithm for efficient data communication between doctors and patients. This proposed method worked in three stages.Design/methodology/approachIn recent decades, wireless body area networks have played an important role in health care applications. It facilitates the transmission of the patients' health data analysis report to the appropriate doctors.FindingsIn the first phase, biological sensors are connected to the human body via a controller node and collected data is transmitted via Bluetooth to the Personal Device Assistant (PDA). In the second phase, collected data will be transmitted via the Internet of things using an artificial bee colony algorithm. The second aids in determining the best route. In the third phase, unmanned aerial vehicles will use the best path to send collected data to doctors, caregivers, ambulances and cloud storage servers.Originality/valueThe simulation results show that the network's performance is superior when compared to existing approaches. The proposed algorithm achieves a high throughput, a lower delay, a higher link rate and a higher delivery rate.

Joint Link Rate Selection and Adaptive Forward Error Correction for High-Rate Wireless Multicast

Multicast communication over wireless networks has many potential applications, such as real-time audiovisual content distribution or digital signage systems with multiple remote terminals. However, today’s common 802.11 networks cannot fully support such applications at the link layer due to the technical challenges in achieving both high transmission rate and high reliability for multicast data transfers. Those challenges primarily emerge from the inapplicability of immediate acknowledgment mechanisms of unicast transmissions to the multicast case and the need for finding a common transmission rate for all receivers with diverse channel conditions. The research literature in this domain mainly addresses the problem at the higher layers of the protocol stack. In this article, we present a novel approach that combines wireless link rate selection with an adaptive packet-level Forward Error Correction (FEC) mechanism in order to achieve high-rate and highly reliable multicast in 802.11 wireless networks. The integration of FEC into the 802.11 MAC layer allows direct interaction between the transmission rate and the coding scheme. As a result, potential packet losses caused by higher link rates can be compensated by the adjustable redundancy provided by FEC. In combination with an aggregated receiver feedback mechanism, this yields improved transmission efficiency and reliability for wireless multicast. We investigate this approach in a simulation environment under a realistic wireless channel model in various application scenarios with up to 50 receivers. The results represent significant performance improvements, in terms of throughput, channel utilization, and packet loss, over the state-of-the-art methods for reliable wireless multicast.

Using address histories to improve the link rates of surveys in the Integrated Data Infrastructure (IDI)

Stats NZ’s Integrated Data Infrastructure (IDI) is a linked longitudinal database combining administrative and survey data. Initially, the IDI contained a small number of administrative datasets from key government agencies, which generally contained good quality identifying information such as nam es and date of birth. As a result, the methodologies developed to link these datasets together relied heavily on these variables, and yielded high link rates while maintaining good quality links. When survey datasets were later added, the link rates achieved were lower than that of administrative datasets, due to poor quality names and the underutilisation of geographic information. This indicated there were improvements to be made to the linking methodology used to link survey data in the IDI. Stats NZ underwent extensive consultation with the research community on their requirements for the expansion of the IDI (IDI2). A key finding from the consultation was that researchers wanted improved survey linkage. This paper outlines how the address history of individuals were used to increase the link rate of surveys in the IDI.

O-42 Dynamic functional connectivity of the EEG in postanoxic coma

Background Predicting neurological recovery of patients with postanoxic coma remains a challenge. We investigate predictive properties of dynamic interactions between neuronal assemblies. Methods We performed a retrospective study of 709 comatose patients after cardiac arrest. We extracted 5 min EEG epochs every 2 h after resuscitation, up to 72 h, and applied automated artefact rejection. Per frequency band (Theta (4–8 Hz), Alpha (8–13 Hz)), instantaneous frequencies were obtained using the ridge algorithm. A link between two EEG locations was assumed if they shared the same instantaneous frequency. Link Rate (LR) was the mean number of links per second, Link Duration (LD) the mean duration per interaction. Differences between patients with good (CPC 1–2) and poor (CPC 3–5) outcome were compared. Results 47 patients were lost to follow-up. Patients with good outcome (n = 300) showed a higher LR 10–40 h after cardiac arrest in the theta band (good: 1.94 ± 0.21 Hz, poor: 1.86 ± 0.40 Hz (median ± IQR) at 24 h) and between 12–24 h in the alpha band (good: 1.72 ± 0.15 Hz, poor: 1.66 ± 0.33 Hz at 24 h). LR stabilized after 44 h in the theta band and decreased in the alpha band. LD with a good outcome was always lower than with a poor outcome in the theta band (good: 85 ± 6 ms, poor: 88 ± 2 ms at 24 h), and for the first 42 h in the alpha band (good: 91 ± 5 ms, poor: 96 ± 2.5 ms at 24 h). Conclusions During the first 40 h after cardiac arrest, lower LR and higher LD are associated with poor outcome. Analysis of predictive values for individual patients are ongoing and will be presented.

Relay-Assisted and QoS Aware Scheduling to Overcome Blockage in mmWave Backhaul Networks

In the scenario where small cells are densely deployed, the millimeter wave (mmWave) wireless backhaul network has been widely used. However, mmWave is easily blocked by obstacles, and how to forward the data of the blocked flows is still a significant challenge. To ensure backhauling capacity, the quality of service (QoS) requirements of flows should be satisfied. In this paper, we investigate the problem of optimal scheduling to maximize the number of flows satisfying their QoS requirements with relays exploited to overcome blockage. To achieve a practical solution, we propose a relay-assisted and QoS aware scheduling scheme for the backhaul networks, called RAQS. It consists of a relay selection algorithm and a transmission scheduling algorithm. The relay selection algorithm selects non-repeating relays with high link rates for the blocked flows, which helps to achieve the QoS requirements of flows as soon as possible. Then, according to the results of relay selection, the transmission scheduling algorithm exploits concurrent transmissions to satisfy the QoS requirements of flows as much as possible. Extensive simulations show RAQS can effectively overcome the blockage problem, and increase the number of completed flows and network throughput compared with other schemes. In particular, the impact of relay selection parameter is also investigated to further guide the relay selection.

A high-reliability relay algorithm based on network coding in multi-hop wireless networks

In multi-hop wireless networks, minimizing the transmission time is very important. In this paper, a high-reliability relay algorithm (HRRA) is proposed to decrease the transmission time based on the network coding in multi-rate environment. The HRRA includes the relay selection algorithm (RSA) and the block transmission algorithm (BTA). Based on the relay reliability of node, RSA chooses the neighbor with the higher link rate as the common relay node and creates more network coding opportunities at the common relay node. Thus, the network coding opportunities and the high-rate links associated with common node could both be exploited in the transmissions of BTA. Moreover, a comprehensive theoretical analysis of the transmission time of HRRA in a block is presented. Lastly, the simulation results show that HRRA can significantly reduce the transmission time compared with the shortest path algorithm and heuristic relay node selection algorithm and COPE.

Costly circuits, submodular schedules and approximate Carathéodory Theorems

Hybrid switching—in which a high bandwidth circuit switch (optical or wireless) is used in conjunction with a low bandwidth packet switch—is a promising alternative to interconnect servers in today’s large-scale data centers. Circuit switches offer a very high link rate, but incur a non-trivial reconfiguration delay which makes their scheduling challenging. In this paper, we demonstrate a lightweight, simple and nearly optimal scheduling algorithm that trades off reconfiguration costs with the benefits of reconfiguration that match the traffic demands. Seen alternatively, the algorithm provides a fast and approximate solution toward a constructive version of Carathéodory’s Theorem for the Birkhoff polytope. The algorithm also has strong connections to submodular optimization, achieves a performance at least half that of the optimal schedule and strictly outperforms the state of the art in a variety of traffic demand settings. These ideas naturally generalize: we see that indirect routing leads to exponential connectivity; this is another phenomenon of the power of multi-hop routing, distinct from the well-known load balancing effects.

Exploiting channel and interface heterogeneity for rate separating channel assignment in IEEE 802.11 wireless multimedia sensor networks

In wireless multimedia sensor networks (WMSNs), disaster control and public safety are crucial issues that focus on emergency management, rescue, and emergency medical services. For high data rate requirement of WMSNs, the IEEE 802.11 specification can be used for the radio interface of sensor nodes, and the nodes can be equipped with multiple 802.11 radios to utilize multiple channels and link data rates. In practical IEEE 802.11 WMSNs, a link shows different link qualities depending on the operating channels and interfaces between two nodes, called channel and interface heterogeneity. In multirate WMSNs, low-rate links severely degrade the capacity of high-rate links, known as rate anomaly. In this article, we propose a novel channel assignment protocol, heterogeneity-aware mesh (HMesh), to address both rate anomaly mitigation and the channel and interface heterogeneity in real IEEE 802.11 WMSNs. HMesh constructs a tree-based WMSN using the proposed channel assignment and routing metric and the heuristic channel assignment algorithm. With the metric and heuristic algorithm, HMesh separates different data rate links by considering the channel and interface heterogeneity. Through extensive simulations and experiments on our IEEE 802.11 WMSN test bed, we demonstrate that HMesh significantly outperforms existing channel assignment protocols in IEEE 802.11 WMSNs.

Costly Circuits, Submodular Schedules and Approximate Carathéodory Theorems

Hybrid switching -- in which a high bandwidth circuit switch (optical or wireless) is used in conjunction with a low bandwidth packet switch -- is a promising alternative to interconnect servers in today's large scale data centers. Circuit switches offer a very high link rate, but incur a non-trivial reconfiguration delay which makes their scheduling challenging. In this paper, we demonstrate a lightweight, simple and nearly-optimal scheduling algorithm that trades-off reconfiguration costs with the benefits of reconfiguration that match the traffic demands. Seen alternatively, the algorithm provides a fast and approximate solution towards a constructive version of Caratheodory's Theorem for the Birkhoff polytope. The algorithm also has strong connections to submodular optimization, achieves a performance at least half that of the optimal schedule and strictly outperforms state of the art in a variety of traffic demand settings. These ideas naturally generalize: we see that indirect routing leads to exponential connectivity; this is another phenomenon of the power of multi-hop routing, distinct from the well-known load balancing effects.

The ALICE high-level trigger read-out upgrade for LHC Run 2

The ALICE experiment uses an optical read-out protocol called Detector Data Link (DDL) to connect the detectors with the computing clusters of Data Acquisition (DAQ) and High-Level Trigger (HLT). The interfaces of the clusters to these optical links are realized with FPGA-based PCI-Express boards. The High-Level Trigger is a computing cluster dedicated to the online reconstruction and compression of experimental data. It uses a combination of CPU, GPU and FPGA processing. For Run 2, the HLT has replaced all of its previous interface boards with the Common Read-Out Receiver Card (C-RORC) to enable read-out of detectors at high link rates and to extend the pre-processing capabilities of the cluster. The new hardware also comes with an increased link density that reduces the number of boards required. A modular firmware approach allows different processing and transport tasks to be built from the same source tree. A hardware pre-processing core includes cluster finding already in the C-RORC firmware. State of the art interfaces and memory allocation schemes enable a transparent integration of the C-RORC into the existing HLT software infrastructure. Common cluster management and monitoring frameworks are used to also handle C-RORC metrics. The C-RORC is in use in the clusters of ALICE DAQ and HLT since the start of LHC Run 2.

Distance-based resource allocation scheme for device-to-device communications underlaying cellular networks

Recently, there has been growing interest in device-to-device (D2D) communications in a cellular network such as LTE-advanced. However, enabling D2D links in a cellular network presents a challenge in radio resource management due to the interference between cellular and D2D links. Some studies have considered cellular users as the primary and proposed methods to protect them from the additional interference from D2D links. However, considering that the D2D function is suitable for short-range and high-rate links, and local multimedia services, it is also important to guarantee these D2D links reliable. Thus, in this paper, we propose a method to properly choose a cellular user that shares radio resource with D2D users in the uplink to mitigate the interference from the cellular user to the D2D receivers. Numerical results show that by applying our method the reliability of D2D communication improves significantly without degrading the performance of the cellular connection. In addition, we derive a closed-form expression for the conditional outage probabilities of D2D links in the case when more than one D2D pair share the same resource with one cellular user, and discuss how the base station can choose a cellular user to optimize the performance of the D2D links.

Common read-out receiver card for ALICE Run2

ALICE at CERN LHC uses custom FPGA-based computer plug-in cards as interface between the optical detector read-out link and the PC clusters of Data Acquisition (DAQ) and High-Level Trigger (HLT). The cards used at DAQ and HLT during Run1 have been developed as independent projects and are now facing similar problems with obsolete major interfaces and limited link speeds and processing capabilities. A new common card has been developed to enable the upgrade of the read-out chain towards higher link rates while providing backward compatibility with the current architecture. First prototypes could be tested successfully and raised interest from other collaborations.

A Predict Deterministic Finite Automaton for Practical Deep Packet Inspection

Deep packet inspection has become extremely important due to network security. In deep packet inspection, the packet payload is compared against a set of patterns specified as regular expressions. Regular expressions are often implemented as deterministic finite automaton (DFA) for matching in linear time at high network link rates. We proposed a predict DFA which can accelerate the processing speed of DFA. A predict DFA uses additional information to predict several next transitions. We tested our proposal on Layer7 rule-set and validated it on real traffic traces, experiments show that our approach offers a significant performance improvement by accelerate rate factors from 1.6 to 2.8 over original DFA.

IEEE 802.11 다중 라디오 다중 전송률 무선 네트워크를 위한 채널 이질성 인지 채널 할당

IEEE 802.11 devices are widely used, and terminals can be equipped with multiple IEEE 802.11 interfaces as low-cost IEEE 802.11 devices are deployed. The off-the-shelf IEEE 802.11 devices provide multiple channels and multiple data rates. In practical multi-channel networks, since there is channel heterogeneity which indicates that channels have different signal characteristics for the same node, channels should be efficiently assigned to improve network capacity. In addition, in multi-rate networks, low-rate links severely degrade the performance of high-rate links on the same channel, which is known as performance anomaly. Therefore, in this paper, we propose a heterogeneity aware channel assignment (HACA) algorithm that improves network performance by reflecting channel heterogeneity and performance anomaly. Through NS-2 simulations, we validate that the HACA algorithm shows improved performance compared with existing channel assignment algorithms that do not reflect channel heterogeneity.

멀티 라디오 애드혹 네트워크에서의 멀티 채널을 이용한 모델 기반 레이트 분할 알고리즘

IEEE 802.11 PHY and MAC layer provide multiple channels and data rates. To improve the performance of IEEE 802.11 multi-radio ad hoc networks, it is required to utilize available channels and data rates efficiently. However, in IEEE 802.11 multi-rate networks, the rate anomaly (RA) problem occurs that the network performance is severely degraded as low-rate links affect high-rate links. Hence, in this paper, we propose a model-based rate separation (MRS) algorithm that uses multiple channels to separate different data rate links so that the RA problem is mitigated. MRS algorithm utilizes an existing throughput model that estimates the throughput of IEEE 802.11 single-hop networks to separate low-rate links and high-rate links. Through simulations, we demonstrate that the MRS algorithm shows improved network performance compared with existing algorithms in multi-radio ad hoc networks.

A Cooperative Channel Assignment protocol for multi-channel multi-rate wireless mesh networks

Wireless mesh networks (WMNs) are considered as one of the outstanding technologies that provide cost-effective broadband Internet accesses to users. The off-the-shelf IEEE 802.11 PHY and MAC specifications support both multi-channel and multi-rate capabilities. However, designing an efficient channel assignment protocol that exploits both available channels and data rates is a critical issue to overcome the network performance degradation. In multi-rate wireless networks, high-rate links may severely suffer from throughput degradation due to the presence of low-rate links. This problem is often referred to as performance anomaly. In this paper, we design a Cooperative Channel Assignment (CoCA) protocol to consider the performance anomaly problem in multi-channel multi-rate WMNs. Based on the proposed family architecture, CoCA exploits the Estimated Delivery Time (EDT) metric and an efficient balancing algorithm. Using the EDT metric, CoCA performs channel assignments to form Multi-channel Multi-hop Paths (MMPs) so that CoCA separates high-rate links from low-rate links over different channels and increases the channel diversity. In addition, CoCA considers the performance anomaly problem and throughput fairness during channel assignments by utilizing the balancing algorithm. We evaluated the performance of CoCA through extensive simulations and found that CoCA outperforms existing well-known channel assignment protocols for WMNs.

A distributed channel assignment protocol for rate separation in wireless mesh networks

Wireless Mesh Networks (WMNs) support the cost-effective broadband access for Internet users. Although today’s IEEE 802.11 PHY and MAC specifications provide multi-channel and multi-rate capabilities, exploiting available channels and data rates is a critical issue to guarantee high network performance. In multi-rate wireless networks, high-rate links heavily suffer from performance degradation due to the presence of low-rate links. This problem is often referred to as performance anomaly. In this paper, we propose a Rate-Based Channel Assignment (RB-CA) protocol to alleviate performance anomaly by using multiple channels in WMNs. RB-CA exploits a new metric, called Prioritized Transmission Time (PTT), in order to form High-rate Multi-channel Paths (HMPs). With HMPs, a large volume of traffics can be simultaneously delivered from or to the Internet via multiple non-overlapping channels as well as high-rate links. Extensive ns-2 simulations and experiments in a real test-bed have been performed to evaluate the performance of RB-CA and then we compared it with a well-known existing WMN architecture. Our simulation and experimental results show that RB-CA achieves improved performance in terms of aggregate throughput, packet delivery ratio, end-to-end delay, and fairness.

Characterization and Modeling of Temporal Variations on an Ultrawideband Radio Link

The development of efficient ultrawideband (UWB) systems for high-rate wireless links requires an accurate knowledge of the radio propagation mechanisms. Anticipated usage scenarios in office or residential environments predict a significant impact of mobile persons on the UWB radio link. However, the issue of temporal variations in the UWB propagation channel has been scarcely investigated so far. This paper presents a study of the time variance of a UWB channel induced by the motion of people, with a specific focus on the main path of a line-of-sight radio link. A real-time measurement campaign involving moving scatterers was performed in the 4-5 GHz band, in a hallway of a typical office building. The analysis of measured data, regarding the shadowing effect and fast signal fluctuations, provides a detailed description of the phenomena involved in a time varying UWB channel. As a result, a model is described for the temporal variations observed on the main propagation path in a fixed UWB link, accounting for both the nonstationary attenuation due to obstructing people and the small-scale signal variations due to scattered propagation paths