Service Access Point Research Articles

IEEE 802.11ay enabled integrated mmWave radar detection and wireless communications

Integrated sensing and communication (ISAC) under the same frequency band and hardware has emerged as a key technology in future wireless networks. Meanwhile, the harmonious coexistence between detection and communication modules has also attracted tremendous research interest in both academia and industry, currently. In this work, we propose a novel Integrated detection and communication (IDAC) scheme in the promising IEEE 802.11ay enabled millimeter wave (mmWave) networks. Particularly, we first introduce a mixing personal basic service set control point or access point (PCP/AP) architecture to support the IDAC function. Thereafter, we embed the radar detection into the IEEE 802.11ay beamforming training (BFT) period by utilizing its directional scanning feature. Furthermore, a BFT and energy allocation strategy is derived to balance the performance between detection and communication. Numerical results demonstrate the effectiveness of the proposed scheme.

Pilot Allocation and Data Power Optimization Based on Access Point Selection in Cell-Free Massive MIMO

Focusing on the pilot contamination problem of cell-free massive multi-input multi-output (MIMO), a pilot allocation algorithm based on access point (AP) selection is proposed. To improve the system performance further, data power optimization is carried out. First, the AP that serves each user is selected through the user-centered idea and the large-scale fading matrix. Use the same service AP numbers between users to measure the pilot contamination intensity and then assign orthogonal pilots to strong potential pilot contamination users. A spectrum efficiency (SE) scheme to maximize the minimum user is proposed for the fairness problem in data power optimization. It is proved that the objective function of data power optimization accords with linear programming, and a dichotomy is given to solve the problem. Simulation results show that the pilot allocation algorithm based on AP selection can significantly improve the total SE of the system and reduce the computational complexity of the system. At the same time, the data power optimization algorithm improves minimum SE for users in the system.

Performance Analysis of Resource Sharing During Downlink Multi-User Transmissions in CSMA/ECA Full Duplex WLANs

Abstract Full Duplex (FD) wireless communications is considered to be the next big step for future Wireless Local Area Networks (WLANs). Old (IEEE 802.11ac) and new (IEEE 802.11ax) WLAN features are expected to co-exist with FD operation. Some of these features include Downlink Multi-User (DL MU) transmissions at the physical layer while at the Medium Access Control (MAC) layer techniques such as the Transmission Opportunity (TXOP) sharing mechanism facilitates these multiuser transmissions. The traditional Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol is inadequate to support full duplex communications efficiently. A very promising adaptation of CSMA/CA and a powerful candidate as the basic channel access method for future WLANs is the Carrier Sense Multiple Access with Enhanced Collision Avoidance (CSMA/ECA). In this paper, we provide an analytical model to assess the performance of resource sharing techniques in full duplex WLANs operating with the CSMA/ECA protocol. Our analysis is based on Markov chains to obtain an estimate of the achievable throughput of the Quality of Service Access Point (QAP) during DL MU transmissions.

Temporal Trends and Future Predictions of Regional EMS System Utilization Using Statistical Modeling.

Trends in utilization of Emergency Medical Services (EMS) systems can be used to extrapolate future use of an EMS system, which will be valuable for the budgeting and planning of finances and resources. The best model for incorporation of seasonal and regional fluctuations in utilization to predict future utilization is unknown. Authors aimed to trend patterns of utilization in a regional EMS system to identify the needs of a growing population and to allow for a better understanding of how the EMS system is used on a basis of call volume and frequency of EMS transportation. The authors then used a best-fitting prediction model approach to show how the studied EMS system will be used in future years. Systems data were retrospectively extracted by using the electronic medical records of the studied EMS system and its computer-assisted dispatch (CAD) database from 2010 through 2017. All EMS dispatches entering the system's 9-1-1 public service access point were captured. Annual utilization data were available from 2010 through 2017, while quarterly data were available only from 2013 through 2017. The 9-1-1 utilization per capita, Advanced Life Support (ALS) utilization per capita, and ALS cancel rates were calculated and trended over the study period. The methods of prediction were assessed through a best-fitting model approach, which statistically suggested that Additive Winter's approach (SAS) was the best fit to determine future utilization and ALS cancel rates. Total 9-1-1 call volume per capita increased by 32.46% between 2010 and 2017, with an average quarterly increase of 0.78% between 2013 and 2017. Total ALS call volume per capita increased by 1.93% between 2010 and 2017. Percent ALS cancellations (cancelled en route to scene) increased by eight percent between 2010 and 2017, with an average quarterly increase of 0.42% (2013-2017). Predictions to end of 2019 using Additive Winter's approach demonstrated increasing trends in 9-1-1 call volume per capita (R2=0.47), increasing trends of ALS utilization per capita (R2=0.71), and increasing percent ALS cancellation (R2=0.93). Each prediction showed increasing future trends with a 95% confidence interval. The authors demonstrate paramount per capita increases of 9-1-1 call volume in the studied ALS system. There are concomitant increases of ALS cancellations prior to arrival, which suggests a potential burden on this regional ALS response system.

A Unified Trustworthy Environment Establishment Based on Edge Computing in Industrial IoT

Under the combination of Internet-of-Things (IoT) technology and traditional industry, the Industrial IoT (IIoT) came into being and received wide attention from all walks of life. With the increase of the number of IIOT devices in industrial environments, security threats, and quality of service (QoS) issues increase drastically. Internal attack is one type of important security threat that makes service environment worse and less reliable. However, there is no unified and fine-grained trust evaluation mechanism to deal with the threats of internal attack and improve QoS of IIoT. To this end, a unified trustworthy environment based on edge computing is established and maintained, which can timely detect malicious service providers and service consumers, filter unreal information, and recommend credible service providers. Edge computing is introduced as an effective service access point, since it supports collecting service records to perform trust evaluations. Moreover, a service selection method is designed to choose the corresponding trustworthy and reliable service providers based on the trust evaluation and the recording criterion, which has distinctive advantages in the succinct trust management, convenient searching service, and accurate service matching. Experiments validated the feasibility of the proposed trustworthy environment.

FACTORS OF SPATIAL CONSTRAINTS AND OPPORTUNITIES IN THE CARPATHIAN REGION OF UKRAINE FOR RENEWABLE ENERGY PROJECTS

The article substantiates the use of renewable energy sources in the sustainable tourism development of the region. Sustainable development of tourism in the Carpathian region is considered taking into account the energy and environmental impact of the traditional Ukrainian energy sources. The developed approach combines the economic profits of the tourism industry with the benefits of society since it takes into account the ecological situation and provides measures for its improvement. It is determined that selecting areas that are suitable for renewable energy consuming projects should consist of three stages: selecting potentially suitable areas, considering exclusion criteria, and an in-depth assessing potential sites or territories. The factors determining spatial constraints and providing essential resources for the construction of wind and solar power plants and small hydropower plants are defined, with the parameters of sustainable tourism development of the Carpathian region in view. Factors that are common to different types of power plants are as follows: availability of wind, solar or hydrological resources, local topography and existing obstacles, accessible terrain, available infrastructure, network service access point, soil properties and composition, the proximity of inhabited areas, surface openness and steepness of slope, environmental constraints, land tenure analysis, proximity of protected nature and landscape areas. Based on these studies, the GIS map of the Carpathian region is compiled showing the spatial distribution of the solar potential on a horizontal surface. Solar radiation varies with the height, steepness of the mountain slopes and other meso and micro factors, but over the examined territory the annual insolation is not less than 1000 kW/m2. The work contains recommendations related to the use of solar energy as the innovation of the tourist infrastructure; they aim at the further developing of major tourist centres and isolated settlements in the Carpathian region.

Role and mission of health service access points

Part of the health and social care landscape since 1998, health service access points (in French, permanences d'accès aux soins de santé) were set up in response to a health and social care problem. The objective is to help disadvantaged people integrate the healthcare pathway. The ultimate aim is to ensure everyone has access to the appropriate care at a fair price.

Sociological aspects of health service access points

The work of health service access points highlights the process of exclusion through marginalisation, the phenomenon of precarity and anthropological tensions between hospitality and inhospitality or between the desirable and undesirable.

Service access and perceptions for Somali Australian migrants at risk of autism

PurposeThe purpose of this paper is to examine the service accessibility of Somali Australians suffering Autism Spectrum Disorder (ASD) by using both quantitative and qualitative methods.Design/methodology/approachUsing Geographic Information System (GIS) and the 2011 census data a total of 19,178 people reporting Somali ancestry were mapped to SA1 level with most being in the three capital cities of original migration; Sydney, Melbourne and Perth.FindingsAccess to primary services pertinent to ASD was measured using the GIS software, some 15 per cent of these cities Somali children were within 500 m of a General practice and 89 per cent within 2,000 m. A quarter of children were within 2,000 m of a speech pathology service access point and nearly a third (31 per cent) within 2,000 m of a psychologist. Qualitative analysis found a quite negative perspective on mental illness and ASD within the community with 85 per cent of respondents reporting a “Bad” perception of ASD within the community.Research limitations/implicationsClearly, the opportunity these data provide is to develop service models targeting need and changing perspectives of ASD within an at risk community.Originality/valueThis is the first time in Australia that issues of service access (health) for Autism suffers and their families has been analysed in a detailed geographic manner.

C2EM: cloud-assisted complex event monitoring in wireless multimedia sensor networks

Abstract This paper addresses the problem of how to provide a more flexible service for complex event monitoring in wireless multimedia sensor networks (WMSNs). In particular, we propose C2EM, a cloud-assisted complex event monitoring architecture that involves scalar sensors, camera sensors, cloudlets, and clouds to leverage computation offloading reliability, service response time, coverage efficiency, and energy efficiency. On clouds, we design an opportunistic service access point selection scheme that provides quality of service (QoS) supports for scalar sensor computation offloading. Meanwhile, clouds are responsible for optimizing camera sensor utilization of the whole network. On cloudlets, we design a real-time camera actuation scheme with the objective of minimizing the possible coverage overlaps while providing probabilistic guarantee in residual energy. Through computation division, most complex computations and network environment profilers are executed on cloudlets or clouds. Sensors only need to carry out very simple operations. We evaluate the performance of C2EM through simulations under a complex event scenario. The results demonstrate that C2EM can enhance complex event monitoring performance with optimized energy efficiency, desirable event coverage quality, and potential adaptability to the dynamics of complex events.

An executable formal semantics for UML-RT

We propose a formal semantics for UML-RT, a UML profile for real-time and embedded systems. The formal semantics is given by mapping UML-RT models into a language called kiltera, a real-time extension of the $$\pi $$ -calculus. Previous attempts to formalize the semantics of UML-RT have fallen short by considering only a very small subset of the language and providing fundamentally incomplete semantics based on incorrect assumptions, such as a one-to-one correspondence between “capsules” and threads. Our semantics is novel in several ways: (1) it deals with both state machine diagrams and capsule diagrams; (2) it deals with aspects of UML-RT that have not been formalized before, such as thread allocation, service provision points, and service access points; (3) it supports an action language; and (4) the translation has been implemented in the form of a transformation from UML-RT models created with IBM’s RSA-RTE tool, into kiltera code. To our knowledge, this is the most comprehensive formal semantics for UML-RT to date.

SRA-MSDU: Enhanced A-MSDU frame aggregation with selective retransmission in 802.11n wireless networks

The main goal of the IEEE 802.11n standard is to achieve more than 100Mbps of throughput at the MAC service access point. This high throughput has been achieved via many enhancements in both the physical and MAC layers. One of the MAC enhancements is the frame aggregation in which multiple frames are concatenated into a single large frame before being transmitted. The 802.11n MAC layer defines two types of aggregation, aggregate MAC service data unit (A-MSDU) and aggregate MAC protocol data unit (A-MPDU). The A-MPDU outperforms A-MSDU due to its large aggregation size and the subframes retransmission in erroneous channels. However, in error free channels and under the same aggregation size the A-MSDU performs better than the A-MPDU due to its smaller headers. Thus, adding a selective retransmission capability to the A-MSDU would improve the system performance. In this paper, we have proposed an MSDU frame aggregation scheme that enables selective retransmission at the MSDU level without altering the original MAC header. In this proposed scheme an implicit sequence control mechanism has been introduced in order to keep the frames in sequence and preserve their correct order at the receiver side. The results show that the proposed scheme improves the system performance in terms of throughput and delay even under highly erroneous channels.

A Reliable A-MSDU Frame Aggregation Scheme in 802.11n Wireless Networks

IEEE 802.11n standard is introduced to enhance the throughput to more than 100Mbps at the MAC service access point. This high throughput is achieved through several enhancements at the physical and MAC layers. Frame aggregation is a key enhancement at the MAC later in which multiple frames are concatenated and then sent in one channel access. In error free channels the 802.11n MAC service data unit aggregation (A-MSDU) performs better than the MAC protocol data unit aggregation (A-MPDU)due to its smaller headers. However, the performance of A-MSDU at erroneous channels is poor due to lack of sub-frames integrity check. In this paper, we proposed an A-MSDU frame aggregation with sub-frame integrity check and retransmission at the MSDU level without altering the original MAC frames header structure. The results show that the proposed scheme improves the system performance in terms of throughput and delay even under highly erroneous channels.

Distance-Based Scheme for Vertical Handoff in Heterogeneous Wireless Networks

Seamless vertical handoff between different access networks in the next generation wireless networks remains a challenging problem. A recent vertical handoff scheme that is based on Signal to Interference and Noise Ratio (SINR) may not be the best scheme for selecting the service access point or base station. Although this SINR- based scheme has higher system throughput and lower disconnection probability as compared with other vertical handoff schemes, we presume that the distance is a good criterion for decreasing service disconnection probability and increasing system throughput. The Distance-based Scheme for Vertical Handoff (DSVH) that we propose in this paper for heterogeneous wireless networks is a reactive vertical handoff scheme. We suggest that vertical handoff be based on the Received Signal Strength (RSS) and the distances to access points or base stations, where the main goal of this scheme is to enhance system performance in terms of reducing service disconnection probability and increasing system throughput. The simulation experiments show that our proposed scheme, DSVH, significantly outperforms the SINR-based scheme. It reduces the number of dropped users by 20%. However, the throughput improvrmrnt is insignificant; it is about 1%.

An Enhanced A-MSDU Frame Aggregation Scheme for 802.11n Wireless Networks

The main goal of the IEEE 802.11n standard is to achieve a minimum throughput of 100 Mbps at the MAC service access point. This high throughput has been achieved via many enhancements in both the p...

Cross-layer resource allocation with multipath routing in wireless multihop and multichannel systems

A joint multipath routing algorithm and channel allocation and scheduling for wireless multihop and multichannel systems is discussed. In packet transmission, distribution of packets to multiroutes makes it possible to reduce the transmission cost of the channels. Cross-layer cooperation of routing, channel allocation, and scheduling is an effective method of packet distribution. As a framework for the cooperation, we propose a multiroute distance vector routing (MDVR) scheme. In the MDVR scheme, the routing table is logically placed in between the routing and link layers, and the table plays the role of a service access point between these two layers. To evaluate the performance of MDVR, simulation is performed in a multichannel, multihop environment. The simulation results show that the MDVR framework can be efficiently implemented in the form of a distributed routing algorithm. It is also shown that in MDVR, the system-wise channel efficiency is almost 25% higher than that in a conventional single-route routing approach.

Digitally-enhanced services for the elderly

During the last decades, both the public and private sectors have started adopting ICT not only for back office service management, but also for end-user service access. ICT-supported digitally-enhanced services can provide benefits both for service providers in the form of more efficient service delivery and management and for the customers in the form of better service access and availability. The research presented in this paper explores issues related to bringing digital service access points into the everyday lives of elderly users and examines the effects of digitally-enhanced services. The paper analyses two case studies exploring digitally-enhanced services that aim to help elderly people in their everyday lives. The results indicate that the analysed services can improve the efficiency of the service processes. However, service efficiency does not directly translate into a better service experience for the user. For achieving significant improvements in the lives of the elderly, other value measures and better understanding of service value potential from the viewpoint of elderly users are needed.

Broadband satellite multimedia

The broadband satellite multimedia (BSM) architecture standardised by ETSI defines a satellite independent service access point (SI-SAP) interface layer that separates the satellite independent features of the upper layers from the satellite dependant features of the lower layers, and provides a mechanism to carry IP-based protocols over these satellite dependent lower layers. This enables interoperability at the IP layer between satellite systems of different physical and link layers technologies that fully comply with the SI-SAP concept. This study reviews past and current standardisation activities including the BSM quality of service (QoS) architecture, security architecture, network management that have been carried out by the ETSI Technical Committee-Satellite Earth Stations and Systems (TC-SES)/BSM working group and looking into the future to extend current SI-SAP functions that can enhance existing QoS provision and security management capabilities as well as proposing a mobility management architecture that complies with the IEEE 802.21 media independent handover framework to support BSM mobility and to allow integration of satellite networks with fixed and mobile network infrastructures. A service-based network management architecture is also proposed to allow management flexibility and integration of business and operation support functions, paving the way for satellite integration into the Internet of the future.

Reduction of Restraint and Seclusion Through Collaborative Problem Solving: A Five-Year Prospective Inpatient Study

This study examined usage patterns of restraint and seclusion before and after the implementation of collaborative problem solving (CPS), a manualized therapeutic program for working with aggressive children and adolescents. The clinical setting was a 15-bed psychiatric inpatient unit for school-age children. A total of 755 children were hospitalized for a total of 998 admissions from fiscal years 2003 to 2007 (median age=11 years; 64% boys). Data were collected for three years before and 1.5 years after the six-month implementation of the CPS model of care. There were 559 restraint and 1,671 seclusion events during the study period. After implementation of the CPS model there was a reduction in the use of restraints (from 263 events to seven events per year, representing a 37.6-fold reduction, slope [beta]=-.696) and seclusion (from 432 to 133 events per year, representing a 3.2-fold reduction, beta=-.423). The mean duration of restraints decreased from 41+/-8 to 18+/-20 minutes per episode, yielding cumulative unitwide restraint use that dropped from 16+/-10 to .3+/-.5 hours per month (a 45.5-fold reduction, beta=-.674). The mean duration of seclusion decreased from 27+/-5 to 21+/-5 minutes per episode, yielding cumulative unitwide seclusion use that dropped from 15+/-6 to 7+/-6 hours per month (a 2.2-fold reduction; p for trend .01 or better for all slopes). During the early phases of implementation there was a transient increase in staff injuries through patient assaults. CPS is a promising approach to reduce seclusion and restraint use in a child psychiatric inpatient setting. Future research and replication efforts are warranted to test its effectiveness in other restrictive settings.

Discovering Web Services in Search Engines

Web service access points are no longer a scarce resource, and the process of discovering them is no longer attached to service registries as Web search engines have become a new major source for Web services. Unfortunately, these separate but distinct approaches to service discovery make it unclear whether provisional registry specifications and search-engine technologies will eventually emerge or coexist.