Slot Duration Research Articles

Improving access to outpatient computed tomography

Demand for diagnostic imaging services in the United States continues to rise, posing challenges for health systems to maintain efficient scheduling processes. This study documents a quality improvement initiative undertaken at our institution in response to a surge in demand for outpatient imaging during 2022, which led to a notable scheduling backlog. By October 2022, the average scheduling interval, defined as the time from order placement to scheduled examination date, had increased from 2 weeks to 6 weeks. The objective of this initiative was to reduce the scheduling interval from 6 weeks to 10 days by January 2023. Utilizing feedback from schedulers, technologists, and radiologists, several interventions were implemented. The impact of each intervention was monitored with a control chart with weekly appointment delays tracked as a balancing measure. Initially, examination slots were double-booked for a period of 4 weeks to address the backlog, resulting in a reduction of the scheduling interval to 12 days (72 % decrease). Subsequently, examination slot duration was shorted from 20 to 15 min and contrast protocols were standardized across all sites. These adjustments further decreased the interval to 7 days (41 % reduction) over the following 9 weeks. While staffing shift adjustments had no impact on the scheduling interval, the introduction of an extra CT scanner reduced the interval to 3 days (57 % decrease). These interventions resulted in a notable increase in examination volume, from a weekly average of 722 to 860 examinations (19 % increase), approximately an additional $1,612,000 in annual revenue. Importantly, there was no change in the average appointment delay, which remained at 15 min over the study period. These improvements were sustained across the subsequent months and received favorable subjective feedback from staff. While the initiative successfully addressed scheduling inefficiencies across our health system, the rise in examination volumes has led to an increased turnaround time for completed reports. Future directions for enhancing the outpatient scheduling process include expanding online scheduling platforms, implementing systems to assess imaging appropriateness, and developing urgency stratification to prioritize time-sensitive examinations.

Speed analysis of ALOHA-based random-access algorithm with various slot duration

Speed analysis of ALOHA-based random-access algorithm with various slot duration

Service Continuity Based Data Delivery Optimization in Satellite-Terrestrial Networks

The satellite-terrestrial networks (STNs) enable global data delivery with low latency and high transmission rate utilizing the Low-Earth-Orbit (LEO) satellite constellation, especially for users in remote regions. However, the dynamic nature of STN presents two challenges to the quality of experience (QoE): 1) the dynamic topology in different time slots; 2) the dynamic path planning for each user. These raise unique problems for the optimization of data delivery paths in STN with service continuity guarantee. In this paper, we first model the STN by a time-varying graph to describe the data delivery in a certain service duration. An indicator called user satisfaction is constructed to measure delivery performance. Aiming at maximizing total user satisfaction, we reformulate the STN path planning problem by utilizing the spatial-temporal decomposition. Considering the path planning in each time slot, we modify the heuristic algorithm to optimize the allocation of transmission resources for different users. In the temporal dimension, we show that the path allocation results in previous time slots directly affect subsequent path calculation then propose an active time slot division algorithm to improve the STN service continuity. Excellent STN transmission performance is matched to the best fit time slot duration to obtain efficient and continuous data delivery. Experimental results show that the proposed STN data delivery optimization scheme achieves superior transmission performance with better service continuity.

Optimal radio resource management in 5G NR featuring network slicing

3GPP 5G New Radio (NR) has introduced several new features that the network slicing concept can leverage to guarantee the heterogeneous requirements in terms of throughput and delays of expected 5G network services. Mainly, these features are (i) Mixed-numerology to control the time slot duration, hence guaranteeing low latency requirements; (ii) Bandwidth Parts (BWP) to control the number of radio resources allocated to users, hence satisfying different throughput requirements. However, efficient radio resource management is already complex, and adding these new dimensions will further increase this complexity. In this paper, we first propose modeling radio resource management in 5G NR featuring network slicing through a Mixed Integer Linear Program (MILP). For our best knowledge, this is the first MILP modeling of the radio resource management featuring network slicing taking into account (i) Mixed-numerology, (ii) both latency and throughput requirements (iii) multiple slice attach per UE (iv) Inter-Numerology Interference (INI). After showing that solving the problem takes an exponential time, we considered a new approach to solve it in a polynomial time, which is highly required when scheduling radio resources. The new approach consists of formalizing this problem using a Deep Reinforcement Learning (DRL)-based solver. We evaluate the use of RL to solve the problem for different network configurations and compared its performance with the optimal solution obtained by solving the MILP problem.

Dynamic rate and channel use allocation for cooperative wireless networks

In this paper, we investigate the performance of link adaptation (LA) algorithms for cooperative multiple access multiple relay networks. In the first transmission phase, the sources transmit in turn in consecutive time slots. In the second cooperative retransmission phase, the destination schedules one relaying node to send redundancies. LA is a fundamental mechanism allowing the source nodes to adapt to the radio channel conditions. In this paper, we investigate the problem of rate allocation using a centralized method, where the destination is the central node that determines the source rates. Furthermore, and in sharp contrast with existing cooperative transmission schemes, we consider the packet size to be time-varying. In other words, we propose adapting the slot duration of each of the sources during the transmission phase as a new degree of freedom. Accordingly, the LA process determines the rate and the time slot duration of each source. We consider a practical performance metric namely, the network spectral efficiency. This metric being difficult to be optimized (given the complex multi-variable optimization problem), we propose best-response dynamic (BRD) algorithms to solve the rate and time duration allocation. Then, we conduct a thorough performance analysis using Monte-Carlo simulations. Our numerical results validate the effectiveness of the proposed BRD algorithms as they yield performance close to the corresponding exhaustive search approach. Furthermore, the results ensure the gain of exploiting the new degree of freedom of the variable slot duration.

The Evaluation of IEEE 802.11ah Performance Based on the Effect of Mobility, Node’s Number, and Traffic Using the Markov Chain Model

The Internet of Things (IoT) is currently growing rapidly and one of the technologies supporting it is wireless fidelity (Wi-Fi) standard IEEE 802.11ah. This technology supports mobility and has a large number of nodes or devices with small energy consumption; hence it is capable of functioning for a long time. In this study, three work scenarios were proposed, namely 1) the mobility, which involves changing the distance between the access point (AP) and the nodes, 2) changing the node’s number, and 3) testing the variations in traffic by changing the collision possibilities and the RAW (Restricted Access Window) (the full title). slot duration in order to analyze the IEEE 802.11ah network performance parameters. The results showed that there was a decrease in throughput, an increase in energy consumption, and a delay due to changes in the nodes’ number and movement/mobility. Also, the variation in traffic by changing the collision probability causes a change in throughput, hence when the collision probability is large, the throughput decreases, while the delay value increases, and vice versa. In conclusion, this study proved that changes in the nodes’ number, movement/mobility, and traffic collision probability affected the IEEE 802.11ah network's performance in throughput, delay, and energy consumption parameters.

Molecular Communication Transmitter Design in Limited-Capacity Storage Regime.

The limited storage capacity at the transmitters of a molecular communication (MC) system can affect the system's performance. One of the reasons for this limitation is the size restriction of the transmitter, which the storage must be replenished so that the transmitter has enough molecules for future transmission. This paper proposes a biologically inspired transmitter model based on neurons for MC whose storage charging and discharging follow differential equations. The proposed transmitter opens its outlet for a specific time in each time frame to exponentially release a portion of stored molecules to code bit-1 and remains silent to code bit-0. We analyze our model based on different transmission parameters. These parameters are the symbol duration, the release time duration, the storage capacity, and the release and replenishment rate of the storage. We find that the storage outlet must be open for a certain period within the time slot duration in order to improve the performance of the proposed system. Additionally, we demonstrate that determining the effect of storage capacity size can be important for practical MC due to the significant differences between the ideal transmitter and the proposed one, which have a limited size. We show that increases in the transmitter storage size can improve the system performance. As a result, taking a closer look at these practical transmitters is essential to solving the problems and challenges of molecular communication systems.

Improved response model of a superconducting nanowire array for high photon count rate communication

In high-speed photon-counting communication where the slot duration is close to the scale of detector reset time, the detection efficiency recovery characteristics of superconducting nanowire single photon detector (SNSPD) become the key factors affecting counting and communication performance. We introduced the nonlinear detection efficiency recovery model derived from the kinetic inductance model combined with the nonlinear efficiency-current relationship into the pulse position modulation (PPM) optical communication system based on the SNSPD array, and studied the impact of the recovery characteristics on the counting and communication performance of the system. On this basis, we introduce the efficiency recovery model into the correction of the channel logarithmic likelihood ratio (LLR) to estimate the SNR of each slot more accurately. Relevant results show that compared with the existing Poisson channel model, fixed deadtime model and detection efficiency exponential recovery model, this modification combined with FEC can provide the best decoding performance, especially in scenarios with high PPM order, small array pixel number and strong noise level. Besides, the nonlinear detection efficiency recovery model also reflects the best consistency with the experimental measurements of the SNSPD array in terms of response count rates near saturation.

QoS-Aware Resource Management in 5G and 6G Cloud-Based Architectures with Priorities

Fifth-generation and more importantly the forthcoming sixth-generation networks have been given special care for latency and are designed to support low latency applications including a high flexibility New Radio (NR) interface that can be configured to utilize different subcarrier spacings (SCS), slot durations, special scheduling optional features (mini-slot scheduling), cloud- and virtual-based transport network infrastructures including slicing, and finally intelligent radio and transport packet retransmissions mechanisms. QoS analysis with emphasis on the determination of the transmitted packets’ average waiting time is therefore crucial for both network performance and user applications. Most preferred implementations to optimize transmission network rely on the cloud architectures with star network topology. In this paper, as part of our original and innovative contribution, a two-stage queue model is proposed and analytically investigated. Firstly, a two-dimension queue is proposed in order to estimate the expected delay on priority scheduling decisions over the IP/Ethernet MAC layer of IP packet transmissions between gNB and the core network. Furthermore, a one-dimension queue is proposed to estimate the average packet waiting time on the RLC radio buffer before being scheduled mainly due to excessive traffic load and designed transmission bandwidth availability.

Numerology-Aware MCOT Selection for Improving Fairness in 5G NR-U Networks

NR-U enables 5G to access the unlicensed bands. However, a 5G NR-U transmitter has to follow the Listen Before Talk (LBT) procedure, where the transmitter has to sense the channel for a while prior to its transmission. Since NR-U is a scheduled technology, the transmission begins only at slot boundaries. But the LBT procedure may end before reaching the slot boundary, and then the transmitter has to wait for a gap period to align with the slot boundary. 5G has different numerologies, and the slot duration of each numerology is different. When nodes with different numerologies are contending for channel access, the node with a lower slot duration has a high probability of winning the channel since, after the LBT procedure, its next slot mostly comes sooner, which leads to fairness issues. In this letter, we propose an algorithm to improve the fairness in multinumerology contention by adaptively changing the Maximum Channel Occupation Time (MCOT) of each numerology according to the slot duration and the number of nodes in each numerology.

An Analytical Latency Model and Evaluation of the Capacity of 5G NR to Support V2X Services Using V2N2V Communications

5G has been designed to support applications such as connected and automated driving. To this aim, 5G includes a highly flexible New Radio (NR) interface that can be configured to utilize different subcarrier spacings (SCS), slot durations, scheduling, and retransmissions mechanisms. This flexibility can be exploited to support advanced V2X services with strict latency and reliability requirements using V2N2V (Vehicle-to-Network-to-Vehicles) communications instead of direct or sidelink V2V (Vehicle-to-Vehicle). To analyze this possibility, this paper presents a novel analytical model that estimates the latency of 5G at the radio network level. The model accounts for the use of different numerologies (SCS, slot durations and Cyclic Prefixes), modulation and coding schemes, full-slots or mini-slots, semi-static and dynamic scheduling, different retransmission mechanisms, and broadcast/multicast or unicast transmissions. The model has been used to first analyze the impact of different 5G NR radio configurations on the latency. We then identify which radio configurations and scenarios can 5G NR satisfy the latency and reliability requirements of V2X services using V2N2V communications. This paper considers cooperative lane changes as a case study. The results show that 5G can support advanced V2X services at the radio network level using V2N2V communications under certain conditions that depend on the radio configuration, bandwidth, service requirements and cell traffic load.

Connectivity Improvement of Hybrid Millimeter Wave and Microwave Vehicular Networks

The network connectivity while traveling in a vehicle is an important issue, which needs to be addressed by mobile vehicular networks. This paper proposes a novel scheme to improve the connectivity of mobile vehicular networks. In particular, the paper proposes a medium access control (MAC) layer hybrid mmWave and microwave scheme for vehicular networks, and leverage their capabilities to improve the vehicle’s connectivity. The novel computational model is derived to evaluate the connectivity for the proposed scheme. The model is used for performance analysis of vehicles moving on a multi-lane highway road and getting connectivity with road-side-units (RSUs) deployed along the roads. Our analysis considers that reference VN has perfect channel state information. It is assumed that the RSU radiates ubiquitously on the road surface using microwave radio access technology (RAT), while it radiates directionally towards reference VN using mmWave RAT. For mathematical analysis, the directionality in mmWave RAT is well approximated by a sectored antenna model. The analysis for the proposed scheme is compared with the existing mmWave network and packet data convergence protocol (PDCP) layer hybrid scheme. The analysis claims that the proposed hybrid scheme significantly improves the connectivity performance in mobile vehicular networks over the existing schemes. The computation results are validated with the simulation results. Also, the paper offers parametric analysis for connectivity probability with vehicle speed and slot duration to enable its practical implementation in 5G/6G technologies.

A cross layer based cooperative broadcast protocol for multichannel VANET

In multichannel environment of Vehicular Ad Hoc Network (VANET), the control channel (CCH) is exclusively dedicated for broadcast communication. Generally, immoderate transmission of packets has heightened the level of contention and collision at CCH, so a controlled flow is needed. The proposed Cross-Layer based Cooperative Broadcast Protocol (CLCBP) is designed to manage safety traffic at CCH, where a receiver-oriented MAC layer based prioritization scheme is used. A modified 2-D Markov chain model is achieved to theoretically investigate vehicle's queue's backoff procedure, where a density dependent dynamic contention window is shown as a convenient way to control collision. So, the collision density information from network layer is used to adjust the contention window at MAC layer. Additionally, a fuzzy logic technique is used to evaluate rebroadcast probability of receiver on the basis of its efficiency, collision density and packet's priority. In order to meet the delay constraint, the backoff slot duration for vehicles gets lowered with increasing value of rebroadcast probability. The simulation results show that the proposed scheme maintains a good balance between coverage delay, reachability, and saved rebroadcast in comparison with the other broadcast schemes.

Analysis of IEEE 802.15.4-Based Delay and Slot Duration Adjustment Combination Methods on Wireless Sensor Networks

IEEE 802.15.4 is one of the standards of the Wireless Sensor Network (WSN) which is at the Medium Access Control (MAC) layer. IEEE 802.15.4 is also technology and protocol within a computer network that can connect all device quickly, has a large capacity and low power consumption. The challenge of Wireless Sensor Network is how to improve the Wireless Sensor Network network performance matrix (goodput, bandwidth utilization, and energy consumption) both in the Contention Access Period (CAP) and in the Contention Free Period (CFP) based on the IEEE 802.15.4 standard. This research is an analysis combination of adjustment delay and slot duration methods to increase goodput, bandwidth utilization and reduce energy consumption in Wireless Sensor Networks in the allocation guaranteed time slots on fixed data simulated using Castalia Simulator software. The problem of this research is whether the combination method can improve the performance matrix of Wireless Sensor Networks on fixed data compared to other methods (SUDAS, ADES, IEEE 802.15.4 Standard). This reserch it aims to determine the performance matrix of combination methods is when compared to other methods (Superframe Duration Adjustment Scheme (SUDAS), Adjustment Delay Scheme (ADES), IEEE 802.15.4 standard) using quantitative approach research methods. Based on the data obtained, the goodput of the combined method increased by 10%, 416%, and 513% respectively compared to the SUDAS method, ADES method, and IEEE 802.15.4 standards. Bandwidth utilization of the combination methods increased by 0.025, 0.223 and 0.232, respectively compared to the SUDAS method, the ADES method, and the IEEE 802.15.4 standard. And the consumption of the combination methods are respectively reduced by 1.02%, 8.72% and 9.08% compared to the SUDAS, ADES and IEEE 802.15.4 standards. With the combination method of delay adjustment and slot duration it is able to optimize the performance of the Wireless Sensor Network compared to other methods.

Probability Models of Distributed Proof Generation for zk-SNARK-Based Blockchains

The paper is devoted to the investigation of the distributed proof generation process, which makes use of recursive zk-SNARKs. Such distributed proof generation, where recursive zk-SNARK-proofs are organized in perfect Mercle trees, was for the first time proposed in Latus consensus protocol for zk-SNARKs-based sidechains. We consider two models of a such proof generation process: the simplified one, where all proofs are independent (like one level of tree), and its natural generation, where proofs are organized in partially ordered set (poset), according to tree structure. Using discrete Markov chains for modeling of corresponding proof generation process, we obtained the recurrent formulas for the expectation and variance of the number of steps needed to generate a certain number of independent proofs by a given number of provers. We asymptotically represent the expectation as a function of the one variable n/m, where n is the number of provers m is the number of proofs (leaves of tree). Using results obtained, we give numerical recommendation about the number of transactions, which should be included in the current block, idepending on the network parameters, such as time slot duration, number of provers, time needed for proof generation, etc.

MM-079: Real-World Treatment Patterns and Outcomes of Triple-Exposed Multiple Myeloma (MM) Patients Treated in Community Oncology Practices in the US

Context Most patients with MM become refractory to proteasome inhibitors (PIs), immunomodulatory drugs, and anti-CD38 monoclonal antibodies; limited evidence indicates these patients have poor outcomes. A US retrospective study showed that 275 patients treated at 14 academic institutions with prior exposure to these 3 agents (triple-exposed) had median overall survival (OS) of 9.2 months. Objective To evaluate real-world treatment patterns and outcomes (duration of therapy and OS) of patients previously treated with a PI, immunomodulatory drug, and anti-CD38 in US community practices. Methods This retrospective observational study used the Integra Connect (IC) database, which includes electronic health data from structured and unstructured fields from 12 community practices on both US coasts. Included were adults with ≥2 ICD-9/ICD-10 codes for MM on ≥2 separate dates who received MM treatment from 2016–2019 with treatment history including triple exposure and who initiated a subsequent line of therapy (s-LOT) after becoming triple-exposed. Outcomes included s-LOT length duration (days from s-LOT start to last-day supply of s-LOT) and OS (time from s-LOT start through death or last office visit date). Results This analysis included 501 patients (median age, 64.9 years; 50% male; 50% with commercial insurance); 82.8% had ECOG 0 or 1 at diagnosis and received a median of 3 prior lines of therapy (LOTs) before initiating s-LOT. Exposures prior to s-LOT included bortezomib (91%), carfilzomib (81%), lenalidomide (94%), pomalidomide (82%), and daratumumab (100%). In s-LOT, 95% received treatment that included the same drug/drug class (bortezomib [30%], carfilzomib [48%], lenalidomide [31%], pomalidomide [47%], and daratumumab [31%]). Median s-LOT duration was 78 days, and median survival was 10.3 months from s-LOT initiation. Conclusions For triple-class-exposed patients, there is lacking consensus on the most efficacious approach to subsequent treatment. This study shows significant retreatment with previously used agents/classes among these patients with short therapy duration and poor survival. New strategies and agents targeting novel aspects of MM are needed for these patients. ©2021 American Society of Clinical Oncology, Inc. Reused with permission. This abstract was accepted and previously presented at the 2020 ASCO Annual Meeting. All rights reserved. Funding GlaxoSmithKline (213286).

5G Numerologies Assessment for URLLC in Industrial Communications.

The fifth-generation (5G) network is presented as one of the main options for Industry 4.0 connectivity. Ultra-Reliable and Low Latency Communications (URLLC) is the 5G service category used by critical mechanisms, with a millisecond end-to-end delay and reduced probability of failure. 5G defines new numerologies, together with mini-slots for a faster scheduling. The main challenge of this is to select the appropriate numerology according to radio conditions. This fact is very important in industrial scenarios, where the fundamental problems are interference and multipath propagation, due to the presence of concrete walls and large metallic machinery and structures. Therefore, this paper is focused on analyzing the impact of the numerology selection on the delay experienced at radio link level for a remote-control service. The study, which has been carried out in a simulated cellular factory environment, has been performed for different packet sizes and channel conditions, focusing on outliers. Evaluation results show that not always a higher numerology, with a shorter slot duration, is appropriate for this type of service, particularly under Non-Line-of-Sight (NLOS) conditions.

6DYN : 6TiSCH with Heterogeneous Slot Durations.

New radio chips implement different physical layers, allowing firmware to change modulation, datarate and frequency dynamically. This technological development is an opportunity for industrial low-power wireless networks to offer even higher determinism, including latency predictability. This article introduces 6DYN, an extension to the IETF 6TiSCH standards-based protocol stack. In a 6DYN network, nodes switch physical layer dynamically on a link-by-link basis, in order to exploit the diversity offered by this new technology agility. To offer low latency and high network capacity, 6DYN uses heterogeneous slot durations: the length of a slot in the 6TiSCH schedule depends on the physical layer used. This article shows how reserved bits in 6TiSCH headers can be used to standardize 6DYN and details its implementation in OpenWSN, a reference implementation of 6TiSCH.

Rate Adaptation and Latency in Heterogeneous IoT Networks

This letter studies the effect of rate adaptation in time slotted Internet of things (IoT) networks. For a given time slot duration and packets size, rate adaptation necessitates packet fragmentation to fit the time slot duration. Accounting for the quality and time resolution of the underlying traffic, this letter characterizes the tradeoff between transmission rate and packet latency in IoT networks. Using tools from stochastic geometry and queueing theory, a novel mathematical framework is developed for static and dynamic rate adaptation schemes. The results show that there is an optimal static rate that minimizes latency, which depends on the network parameters. Furthermore, the dynamic rate is shown to be resilient to different variations in the network parameters without sacrificing packet latency.

Performance of defected ground structure with miniaturized microstrip patch antenna using RMPA substrate material

Abstract A parallel structural antenna with the acts slot configuration is indicated for process of 5G wireless technology. The direct slot configuration defined within the patch antenna drives the 5G mid band and twin band frequency reaction in the frequency location without the conditions. Next, a 2-D Double Periodic Electronic Band (EBG) shape is carried out below the metal ground aircraft to request an extended impedance bandwidth for RMPA Materials. The slot duration and feature changed into designed for an impedance bandwidth of 12.49% and 4.49% at three pass band frequencies of 532 GHz and, 835 GHz respectively. Simulated with measured gain and reflection coefficient of correct settlement for bending bandwidths. The antenna array length is 33.5 mm × 33.5 mm. The antenna modified structure and the experimental effects were compared with all the other existing systems. The proposed antenna, which makes use of the EBG structure, suggests pics and excessive sensitivity steady with a massive impedance bandwidth, meeting the necessities of the IoT software program supplied with the resource of 5G technology.