Setup Delay Research Articles

Further mobility enhancements for 5G-advanced and beyond

The study on mobility is an inherent part of any generation of cellular technology. It is aimed at ensuring robust, reliable, and interruption-free handover of the mobile user connection. Such continuous improvement is necessary as the service requirements become more stringent which urge the mobility to meet the highest performance expectations. In this paper, it is described how such requirements are to be achieved by the 3GPP Release 18 components. It begins with the introduction to the world of mobility, covering the solutions that have been designed since the first generation of New Radio (NR). Then improvements pursued in consecutive 3GPP releases are outlined. Selected areas for Release 18 mobility enhancements have been evaluated using 5G-compliant system-level simulations and results thereof are presented below. These include wrong Primary Secondary Cell (PSCell) preparation in Conditional Handover (CHO) and the impacts of secondary cell setup delay in Dual Connectivity (DC). It is shown that preparing multiple PSCells in CHO ensures the user accesses the right cell in up to 96% of cases.

Scalable narrow linewidth high power laser for barium ion optical qubits

The linewidth of a laser plays a pivotal role in ensuring the high fidelity of ion trap quantum processors and optical clocks. As quantum computing endeavors scale up in qubit number, the demand for higher laser power with ultra-narrow linewidth becomes imperative, and leveraging fiber amplifiers emerges as a promising approach to meet these requirements. This study explores the effectiveness of thulium-doped fiber amplifiers (TDFAs) as a viable solution for addressing optical qubit transitions in trapped barium ion qubits. We demonstrate that by performing high-fidelity gates on the qubit while introducing minimal intensity noise, TDFAs do not significantly broaden the linewidth of the seed lasers. We employed a Voigt fitting scheme in conjunction with a delayed self-heterodyne method to accurately measure the linewidth independently, corroborating our findings through quadrupole spectroscopy with trapped barium ions. Our results show linewidth values of 160 ± 15 Hz and 156 ± 16 Hz, respectively, using these two methods, underscoring the reliability of our measurement techniques. The slight variation within the error-bars of the two methods can be attributed to factors such as amplified spontaneous emission in the TDFA or the influence of 1/f noise within the heterodyne setup delay line. These contribute to advancing our understanding of laser linewidth control in the context of ion trap quantum computing as well as stretching the availability of narrow linewidth, high-power tunable lasers beyond the C-band.

PaCHNOC: Packet and Circuit Hybrid Switching NoC for Real-Time Parallel Stream Signal Processing.

Real-time heterogeneous parallel embedded digital signal processor (DSP) systems process multiple data streams in parallel in a stringent time interval. This type of system on chip (SoC) requires the network on chip (NoC) to establish multiple symbiotic parallel data transmission paths with ultra-low transmission latency in real time. Our early NoC research PCCNOC meets this need. The PCCNOC uses packet routing to establish and lock a transmission circuit, so that PCCNOC is perfectly suitable for ultra-low latency and high-bandwidth transmission of long data packets. However, a parallel multi-data stream DSP system also needs to transmit roughly the same number of short data packets for job configuration and job execution status reports. While transferring short data packets, the link establishment routing delay of short data packets becomes relatively obvious. Our further research, thus, introduced PaCHNOC, a hybrid NoC in which long data packets are transmitted through a circuit established and locked by routing, and short data packets are attached to the routing packet and the transmission is completed during the routing process, thus avoiding the PCCNOC setup delay. Simulation shows that PaCHNOC performs well in supporting real-time heterogeneous parallel embedded DSP systems and achieves overall latency reduction 65% compared with related works. Finally, we used PaCHNOC in the baseband subsystem of a real 5G base station, which proved that our research is the best NoC for baseband subsystem of 5G base stations, which reduce 31% comprehensive latency in comparison to related works.

Security Enhancement of SIP Protocol in VoIP Communication

In Voice over IP (VoIP) systems, calls are started, maintained, and ended using the Session Initiation Protocol (SIP). One of the SIP flaws is the lack of enough data to validate users, and its contents can be changed to fake the Caller Identification (CID). Fake CID can be used by hackers to trick receivers and obtain valuable materials. Existing solutions have a number of faults, including the use of more network resources, the use of insufficient data to identify fake CID, and high call setup delay for caller and callee during the validation process. This work presents an algorithm to enhance SIP protocol security to mitigate the flaws of the previous solutions that are used to address CID spoofing. By using the Media Access Control (MAC) address, the algorithm can validate the CID and warn the callee for the fake CID. The algorithm was developed and tested by using Mininet, Python based open source OpenFlow (POX) controller, SIPp simulator, Linphone softphone, and freePBX. All faked CID were detected and receivers were alerted on the linphone screen. Session setup delay obtained are within the 15.1 ms to 27.3 ms, which are within the acceptable Quality of Service (QoS) ranges.

Controller placement with critical switch aware in software-defined network (CPCSA).

Software-defined networking (SDN) is a networking architecture with improved efficiency achieved by moving networking decisions from the data plane to provide them critically at the control plane. In a traditional SDN, typically, a single controller is used. However, the complexity of modern networks due to their size and high traffic volume with varied quality of service requirements have introduced high control message communications overhead on the controller. Similarly, the solution found using multiple distributed controllers brings forth the 'controller placement problem' (CPP). Incorporating switch roles in the CPP modelling during network partitioning for controller placement has not been adequately considered by any existing CPP techniques. This article proposes the controller placement algorithm with network partition based on critical switch awareness (CPCSA). CPCSA identifies critical switch in the software defined wide area network (SDWAN) and then partition the network based on the criticality. Subsequently, a controller is assigned to each partition to improve control messages communication overhead, loss, throughput, and flow setup delay. The CPSCSA experimented with real network topologies obtained from the Internet Topology Zoo. Results show that CPCSA has achieved an aggregate reduction in the controller's overhead by 73%, loss by 51%, and latency by 16% while improving throughput by 16% compared to the benchmark algorithms.

Multi-Provider IMS Infrastructure With Controlled Redundancy: A Performability Evaluation

In modern telecommunication networks, services are provided through Service Function Chains (SFC), where network resources are implemented by leveraging virtualization and containerization technologies. In particular, the possibility of easily adding or removing network resources has prompted service providers to redefine some concepts including performance and availability. In line with this new trend, we propose a performability study of a multi-provider containerized IP Multimedia Subsystem (cIMS), an SFC-like infrastructure used in the core part of 4G/5G networks to handle multimedia sessions. On the one hand, performance issues are tackled by modeling each cIMS node in terms of a G/G/m queueing system to derive the Call Setup Delay (CSD), a performance metric related to the user-end experience in multimedia communications. On the other hand, availability issues are addressed through the Multi-State System (MSS) formalism, to take into account different performance rates of the system. Then, we devise an algorithm called PE-MUGF (Performability Evaluation through Multidimensional Universal Generating Function) to identify the minimum-redundancy cIMS configuration which meets given performance and availability targets at the same time. Finally, an extensive experimental analysis based on Clearwater, a containerized IMS testbed, allows us to estimate most of system parameters whose robustness is evaluated through a sensitivity analysis.

Using FlowVisor and evolutionary algorithms to improve the switch migration in SDN

The switch migration (SM) issue has been widely addressed in distributed Software Defined Networks (SDN). Most of researches have focused on achieving SM with balanced loads among controllers but little efforts are devoted to equilibrate the service offered to switches when limited resources in control plane are experienced. This paper deals with the problem of dynamic switch migration in multi-controller SDN. Basically, it aims to achieve a trade-off between the whole flow setup delay, the load balancing among controllers and the service fairness among switches by efficiently splitting requests of a switch between multiple controllers. The trade-off is solved using a combination of the Unbalanced Transportation Problem optimization (UTP) and Genetic algorithms (GA). Henceforth, a new genetic algorithm denoted Reference-based Non-Dominated Sorting Algorithm (R-NSGA-II) is proposed to achieve this trade-off. The proposed approach uses the FlowVisor framework as a virtualization layer between switches and controllers. FlowVisor will relay requests coming from switches toward controllers based on current network status with the aim of achieving the above trade-off. The proposed approach is associated with no switch migration cost since assignment is done logically by FlowVisor. Simulation results show that the proposed approach outperforms several existing approaches in terms of the whole flow-setup time, the load balancing among controllers and the request service fairness among switches.

Jointly optimized resource allocation for SDN control and forwarding planes in edge-cloud SDN-based networks

Today’s resource allocation strategies for edge-cloud network based on Software-Defined Network (SDN) and Network Function Virtualization (NFV) architectures often make a decision of placing resource based on network locations, i.e. edge or core cloud. Unfortunately, these strategies are not optimally tailored for a growing class of Internet-of-Things (IoT) services whose traffic is designated to go through a Virtual Network Functions (VNF) service chain. Without considering the communication between SDN control plane and forwarding plane, inappropriate SDN controllers could be selected for switches, which may result in a significant setup delay of the whole service chain. In addition, the fluctuate demand of IoT services requires the entire system, that is composed of controllers, forwarding elements, i.e. switches, and physical machines, being stable during service provisioning. In this paper, we jointly address two issues, i.e. SDN controller-switch assignment and VNF placement, both are high-complexity problems. We formulate the joint optimization problem of dynamically provisioning resource for SDN controllers and VNFs in a long run. We then apply the Lyapunov optimization framework to transform a long-term optimization problem into a series of real-time problems and employ exponentiated gradient ascent (EGA) method to find a near-optimal solution. Extensive simulation and experiments show that our approach helps to optimize the system cost up to 11 ∼ 40% depending on service demand and network size.

Performance Evaluation of a Multidomain IMS/NGN Network Including Service and Transport Stratum

The Next Generation Network (NGN) architecture was proposed for delivering various multimedia services with guaranteed quality. For this reason, the elements of the IP Multimedia Subsystem (IMS) concept (an important part of 4G/5G/6G mobile networks) are used in its service stratum. This paper presents comprehensive research on how the parameters of an IMS/NGN network and traffic sources influence mean Call Set-up Delay (E(CSD)) and mean Call Disengagement Delay (E(CDD)), a subset of standardized call processing performance (CPP) parameters, which are significant for both network users and operators. The investigations were performed using our analytical traffic model of a multidomain IMS/NGN network with Multiprotocol Label Switching (MPLS) technology applied in its transport stratum, which provides transport resources for the services requested by users. The performed experiments allow grouping network and traffic source parameters into three categories based on the strength of their effect on E(CSD) and E(CDD). These categories reflect the significance of particular parameters for the network operator and designer (most important, less important and insignificant).

Practical Performance Analyses of 5G Sharing Voice Solution

Sharing network infrastructure is carried out by a few network operators in the world and is regarded as an effective means to accelerate the commercial 5G with seamless coverage and user experience guarantees but significantly reduced investment. Voice via IMS has been defined as the voice-bearing solution from 3rd-Generation Partnership Project (3GPP) Release 5. Release 15 pointed out that 5G still adopts the IMS-based voice service architecture. In such a background, and in the process of global 5G network evolution from non-stand-alone (NSA) to stand-alone (SA), how to bear 5G voice services in the sharing network infrastructure has quite a few technical options. This paper investigates the 5G access network sharing technical solutions and presents the voice bearer technology under different new radio (NR) evolution stages. Analysis was performed for the different stages of voice handover. Performance results from field tests are provided to verify the feasibility of the solution, and performance analysis such as end-to-end call setup delay was also carried out. From the theoretical and practical analysis, the voice over long-term evolution (VoLTE) non-back-to-home solution has a relatively short access delay in the NSA sharing stage; EPS fallback based on either handover or redirection introduces a large time delay, so EPS fallback can only be used as a transition solution in the early stage of SA sharing deployment; voice over new radio (VoNR) has the lowest access time delay and the simplest implementation solution, so it is the final voice solution for 5G SA sharing network. The comparison of different voice-bearing solutions in different network development stages provides a reference for countries around the world.

High-Capacity Data Collection Platform for Smart Cities Using IEEE 802.11ad-Based Millimeter-Wave V2X Communication

The collection and utilization of huge sensor data from vehicles for visualizing the city is expected to realize various enhanced services for smart cities. A next-generation gigabit vehicle-to-everything (V2X) data collection platform based on 60 GHz millimeter-wave (mmWave) small cell radio access has been proposed in the previous work for enabling efficient and high-capacity data upload from vehicles to the cloud. This paper presents further analysis of the initial link setup delay to evaluate the effectiveness of the fast initial V2X link setup method proposed, which is suitable for 60 GHz communication based on IEEE 802.11ad. This paper also presents the application programming interface (API) design based on the hypertext transport protocol (HTTP) to enable the efficient upload of hundreds of files. Combined with the buffering technique at a multiaccess edge computing (MEC) server, the proposed system successfully utilizes very high bandwidth between a vehicle and a MEC server. The proposed methods achieve a 30 times improvement in delay for establishing the initial link and an 11 times higher average throughput. A prototype system installed in Marysville, Ohio, achieved a peak throughput of 2.8 Gbps and successfully demonstrates the effectiveness of city visualization based on high-capacity data collection and analytics.

Roadside units plane optimization scheme in software‐defined vehicular networks

AbstractAs a new research field, software‐defined vehicular networks (SDVN) provide a novel idea for the network management of the internet of vehicles. Due to the time‐sensitivity of vehicle edge networks, time delay optimization for flow rule management is of great significance to improve system performance. Some existing SDVN architectures select part of the underlying roadside units (RSUs) as underlying controllers to assist the upper control plane. There is no mention of how to optimize the state switching between the RSU controller and the common RSU, which may increase the delay and communication overhead. This paper proposes an RSU plane optimization scheme to reduce the state fluctuation between RSUs with control functions. Firstly, we propose a state fluctuation optimization model of the RSU plane. Secondly, the division method and dynamic adjustment strategy of the RSU plane are designed. Finally, a position prediction method is utilized to realize the pre‐installation of flow rules. We use two common methods (greedy and dynamic schemes) to compare with the minimum state fluctuation approach. The simulation analyzes the performance using four parameters. Under the same conditions, the proposed scheme can reduce the flow setup delay and end‐to‐end delay, while reducing the number of controllers and overhead.

The Application of Human Factors Engineering to Reduce Operating Room Turnover in Robotic Surgery.

Challenges associated with turnover time are magnified in robotic surgery. The introduction of advanced technology increases the complexity of an already intricate perioperative environment. We applied a human factors approach to develop systematic, data-driven interventions to reduce robotic surgery turnover time. Researchers observed 40 robotic surgery turnovers at a tertiary hospital [20 pre-intervention (Jan 2018 to Apr 2018), 20 post-intervention (Jan 2019 to Jun 2019)]. Components of turnover time, including cleaning, instrument and room set-up, robot preparation, flow disruptions, and major delays, were documented and analyzed. Surveys and focus groups were used to investigate staff perceptions of robotic surgery turnover time. A multidisciplinary team of human factors experts and physicians developed targeted interventions. Pre- and post-intervention turnovers were compared. Median turnover time was 67min (mean: 72, SD: 24) and 22 major delays were noted (1.1/case). The largest contributors were instrument setup (25.5min) and cleaning (25min). Interventions included an electronic dashboard for turnover time reporting, clear designation of roles and simultaneous completion of tasks, process standardization of operating room cleaning, and data transparency through monthly reporting. Post-intervention turnovers were significantly shorter (U = 57.5, p = .000) and ten major delays were noted. Human factors analysis generated interventions to improve turnover time. Significant improvements were seen post-intervention with a reduction in turnover time by a 26min and decrease in major delays by over 50%. Future opportunities to intervene and further improve turnover time include targeting pre- and post-operative care phases.

Agile neighbor discovery in MEMS-based free space optical networks: a computer vision approach

Highly directional laser-based wireless optical radios are able to spatially reuse several THz of spectrum but suffer from link setup delays. In delay averse and high-throughput self-configuring networks, agile neighbor discovery is of critical importance. Given an optical wireless network with microelectromechanical systems based receivers, we explore the use of adaptive combinatorial group testing and contour tracing to achieve very low neighbor discovery latency. We propose a pattern-based algorithm that leverages group testing and contour tracing techniques to significantly reduce latency. Evaluating our algorithms, we compare hierarchical group testing algorithms to state-of-the-art raster and Lissajous pattern-based scanning and report 99.92% and 87% reduction in latency, respectively, for an array of one million micromirrors. The proposed pattern-based algorithm, when compared to hierarchical group testing and the Moore-neighbor contour tracing algorithms, achieves 63.4% and 4.91% reduction in latency, respectively.

Techno-Economic Feasibility Analysis of a Fully-Mobile Radiation Oncology System Using Monte Carlo Simulation

<h3>Purpose/Objective(s)</h3> Disparities in radiation oncology (RO) care exist, in part, due to geographic barriers in access to care. A first step to mitigate these barriers is the development of a semi-mobile RO system for single-facility, temporary care (∼months), which has been successfully implemented in several locations across the United States. To further address geographic disparities, we investigate the feasibility and financial viability of a fully mobile RO system, capable of delivering RO treatments in multiple geographic locations in a single day through Monte Carlo simulation. <h3>Materials/Methods</h3> A ring-gantry linear accelerator (LINAC) was mounted on a mobile coach that can be transported from one location to another via a tractor trailer. In our model, the mobile coach visits two separate geographic locations within a given day, and a total of three locations in a given two-week period. At each location, the mobile coach is parked within a concrete bay to provide shielding. Timing of setup and quality assurance (QA) testing were evaluated to investigate speed and clinical safety. Monte Carlo simulations were performed in Python to model patient throughput and outside factors, such as traffic, that could affect patient treatments. In this simulation, five-fraction treatment regimens were considered for lung, breast, rectum, and prostate. Cancer census data were collected for Southeastern Missouri to represent the geographic supply of patients. The mobile system was also compared to three separate brick and mortar facilities that would treat the same total number of patients, but equally divided amongst three hypothetical facilities. Statistical and sensitivity analyses were conducted for the simulations to evaluate factors impacting financial viability and feasibility. <h3>Results</h3> Machine setup and comprehensive QA that performs all necessary tests according to national standards, could be performed in < 2.5 hours in most situations, leaving > 5 hours for treatment time and driving. On average, the mobile RO system would see 50.0 breast, 39.6 lung, 14, rectum, and 0 prostate patients within a given year. No overtime was needed to treat any patient under treatment, given simulated traffic or setup delays. Assuming a Medicare patient rate of 50%, a five-year life cycle profit would be 355% ± 125% percentage increase for the mobile system compared to the three separate brick and mortar facilities. The number of patients treated has the highest correlation with profit, r(9998) = 0.44, <i>P</i> = < 0.01, followed by concrete bay construction costs, r(9998) = -.05, <i>P</i> = < 0.01. Sensitivity analysis showed that if there is a 10% decrease in patient population, the profit would decrease by -15%. If the Medicare patient rate decreased to 30%, the patients treated vs. profit correlation would become r(9998) = 0.53, <i>P</i> = < .01. <h3>Conclusion</h3> A fully mobile RO-system is a viable and affordable option for RO delivery in areas that lack RO resources.

Modelling and Analysis of 5G Networks Based on MEC-NFV for URLLC Services

Ultra-Reliable and Low Latency Communications (URLLC) is a Fifth Generation (5G) or Beyond(B) 5G of Mobile Networks service that presents strict reliability and latency requirements. Multi-Access Edge Computing (MEC) and Network Function Virtualization (NFV) emerge as essential solutions since they allow network applications/functions to be virtualized and hosted closer to the end-user, improving reliability and latency. However, they may incur delay overheads (e.g., resource setup delay, failure events) to the dynamic resource provisioning that may impair the URLLC, which must be considered in the MECNFV node setting. This work addresses the resource provisioning for URLLC services in MEC-NFV-based networks, considering the Virtualized Network Function (VNF) setup time, failure occurrence and resource pre-initialization. A queue-based model is proposed to analyze the MEC-NFV node configuration in terms of average response time, blocking probability, and average number of active resources, under different service arrival and resource setup rates, maximum system capacity, number of resources and pre-initialized ones are carried out. The results show that the resource pre-initialization may mitigate the negative effect of the lower VNF setup rate.

Coordinating lot sizing and integrated production and distribution scheduling with batch delivery and holding cost

PurposeThe aim of this paper is to present a method for finding the optimum balance between sequence-dependent setup costs, holding costs, delivery costs and delay penalties in an integrated production–distribution system with lot sizing decisions.Design/methodology/approachTwo mixed integer linear programming models and an optimality property are proposed for the problem. Since the problem is NP-hard, a genetic algorithm reinforced with a heuristic is developed for solving the model in large-scale settings. The algorithm parameters are tuned using the Taguchi method.FindingsThe results obtained on randomly generated instances reveal a performance advantage for the proposed algorithm; it is shown that lot sizing can reduce the average cost of the supply chain up to 11.8%. Furthermore, the effects of different parameters and factors of the proposed model on supply chain costs are examined through a sensitivity analysis.Originality/valueAlthough integrated production and distribution scheduling in make-to-order industries has received a great deal of attention from researchers, most researchers in this area have treated each order as a job processed in an uninterrupted time interval, and no temporary holding costs are assumed. Even among the few studies where temporary holding costs are taken into consideration, none has examined the effect of splitting an order at the production stage (lot sizing) and the possibility of reducing costs through splitting. The present study is the first to take holding costs into consideration while incorporating lot sizing decisions in the operational production and distribution problem.

The Impact of Time Delays for Power Hardware-in-the-Loop Investigations

Power hardware-in-the-loop (PHiL) simulations provide a powerful environment in the critical process of testing new components and controllers. In this work, we aim to explain the impact of time delays in a PHiL setup and recommend how to consider them in different investigations. The general concept of PHiL, with its necessary components, is explained and the benefits compared to pure simulation and implemented field tests are presented. An example for a flexible PHiL environment is shown in form of the Power Hardware-in-the-Loop Simulation Laboratory (PHiLsLab) at TU Hamburg. In the PHiLsLab, different hardware components are used as the simulator to provide a grid interface via an amplifier system, a real-time simulator by OPAL-RT, a programmable logic controller by Bachmann, and an M-DUINO microcontroller. Benefits and limitations of the different simulators are shown using case examples of conducted investigations. Essentially, all platforms prove to be appropriate and sufficiently powerful simulators, if the time constants and complexity of the investigated case fit the simulator performance. The communication interfaces used between simulator and amplifier system differ in communication speed and delay; therefore, they have to be considered to determine the level of dynamic interactions between the simulated rest of system and the hardware under test.

MobiPlace: Mobility-Aware Controller Placement in Software-Defined Vehicular Networks

In this paper, we propose a mobility-aware scheme, named MobiPlace, to address the controller placement problem (CPP) at the Road Side Units (RSUs) in Software-Defined Vehicular Networks (SDVNs). MobiPlace places local controllers at the selected RSUs to reduce the operational delay experienced in traditional SDVN architecture, where controllers are placed at the cloud. Additionally, we consider the effect of dynamic road traffic and propose dynamic adjustment of the placement of the controller with minimal changes. In contrast to the existing literature, we infuse traffic monitoring and traffic prediction strategies to ensure accurate delivery of control messages and data packets. We formulate an Integer Linear Program (ILP) and propose a solution approach consisting of three modules — mobility management , controller placement , and controller selection . The mobility management module uses Markov predictor to predict vehicle movement and reduce controller synchronization overhead when a vehicle moves to a different controller's coverage area. The controller placement module applies a simulated annealing-based algorithm to select potential RSUs that serve as local controllers. The controller selection module determines the preferable controller location for processing the service requests. Simulation results depict that MobiPlace reduces the average flow setup delay by $13.85 \%$ compared to the existing state-of-the-art.

Fast Two-Stage Computation of an Index Policy for Multi-Armed Bandits with Setup Delays

We consider the multi-armed bandit problem with penalties for switching that include setup delays and costs, extending the former results of the author for the special case with no switching delays. A priority index for projects with setup delays that characterizes, in part, optimal policies was introduced by Asawa and Teneketzis in 1996, yet without giving a means of computing it. We present a fast two-stage index computing method, which computes the continuation index (which applies when the project has been set up) in a first stage and certain extra quantities with cubic (arithmetic-operation) complexity in the number of project states and then computes the switching index (which applies when the project is not set up), in a second stage, with quadratic complexity. The approach is based on new methodological advances on restless bandit indexation, which are introduced and deployed herein, being motivated by the limitations of previous results, exploiting the fact that the aforementioned index is the Whittle index of the project in its restless reformulation. A numerical study demonstrates substantial runtime speed-ups of the new two-stage index algorithm versus a general one-stage Whittle index algorithm. The study further gives evidence that, in a multi-project setting, the index policy is consistently nearly optimal.