Multiple Gateways Research Articles

Edge-Based Hybrid System Implementation for Long-Range Safety and Healthcare IoT Applications

In many conventional Internet-of-Things (IoT) applications, data are transferred directly from the sensor network to the cloud via a gateway for further data processing. However, this typical usage of a gateway is not suitable for every application. For short-range IoT wireless protocols [e.g., Bluetooth low energy (BLE)], multiple gateways are required to achieve broader coverage, which is inconvenient. In this article, an edge-based hybrid network system architecture is presented. The proposed system consists of hybrid routers and an IoT gateway. The router supports two wireless protocols, BLE and long range (LoRa), and is equipped with a solar energy harvester to extend the router's lifetime. It can extend the coverage of short-range BLE network by utilizing LoRa wireless technology, and support fundamental edge computing tasks such as preliminary data processing. The IoT gateway can support multiple IoT protocols, including LoRa, BLE, and XBee. It can perform more advanced edge computing tasks, such as data filtering, storage, processing, user interface, and cloud connection. Three case studies incorporating a wearable safety monitoring sensor network, a healthcare monitoring application, and a smart hospital application are studied with the proposed edge network system to demonstrate its promising capabilities to support IoT applications. Experimental evaluations indicate that by processing data at the edge, the minimal delay is only 11.5 ms. Furthermore, with the hybrid LoRa network implementation, the BLE network can be extended to 2.4 km.

Adaptive Mechanism for Discovering Internet Gateways in Wireless Networks Using Swarm Intelligence

One of the most critical and challenging processes is the provision of internet connectivity for nodes in Wireless Mesh Networks (WMN) or mobile ad hoc networks (MANET). A wide variety of “business and non-commercial” applications are implemented in MANET, most of them gaining Internet resources. Gateway (GW) or Mesh GWs are the key components of MANET's Internet connectivity, and multiple GWs are implemented to improve MANET's capabilities. Many of the current routing protocols are implemented and improved to work with MANET, either using traditional routing approaches or tree-based network approaches. But since MANET is a complex and transient network, it is very necessary to explore new or tack the GWs failure that adds more overhead on the network. Thus, in this paper a hybrid protocol inspired by the swarm intelligence technique that follows the non-root GWs discovery approach using Ant Colony Optimization (ACO) is suggested. The experimental results validate the processes of exploring new GWs, testing and maintaining existing paths to GWs, exploring different paths to existing GWs and detecting any connection failure in any route, and attempting to fix that failure.

NOMA Application to Satellite Communication Networks for 5G: A Comprehensive Survey of Existing Studies

The 4th generation of communication networks (4G) seems limited and unable to satisfy the growing networks’ performances demands of new intended communication services such as the internet-of-things (IoTs). The 5th generation of communication networks (5G) has therefore been envisaged to fill the gap. The non-orthogonal multiple access (NOMA) technology and the satellite communication have been identified as key enabling technologies for the achievement of 5G networks. There are many ongoing NOMA related works for 5G; however, the few existing reviews mostly discuss works that apply NOMA to terrestrial networks. This paper therefore, gives a comprehensive and up-to-date review of existing works applying NOMA to satellite communication networks. More precisely, it presents studies that have either designed or do performance analysis of NOMA-based multibeam satellitesystems (MBSSs) or integrated satellite-terrestrial networks (ISTNs). The surveys presented showed that the application of NOMA to satellite communications for 5G is starting to gain considerable interest. Most of the current PD-NOMA design works attempt to maximize the system capacity (sum-rate), and most of the current PD-NOMA performance analysis works demonstrate the superiority of NOMA over OMA through Ergodic Capacity and Outage probability estimations. The surveys also showed that this field is still quite opened for research, with issues such as user-fairness maximization, satellite capacity improvement, ground-surface moving beams (for LEOs and MEOs satellites) and multiple gateways combination … etc. remaining prospective research areas to be explored.

Leveraging fairness in LoRaWAN: A novel scheduling scheme for collision avoidance

The employment of Low-Power Wide Area Networks (LPWANs) has proven quite beneficial to the advancement of the Internet of Things (IoT) paradigm. The utilization of low power but long range communication links of the LoRaWAN technology promises low energy consumption, while ensuring sufficient throughput. However, due to LoRa’s original scheduling process there is a high chance of packet collisions, compromising the technology’s reliability. In this paper, we propose a new Medium Access Control (MAC) protocol, entitled the FCA-LoRa leveraging fairness and improving collision avoidance in LoRa wide-area networks. The novel scheduling process that is introduced is based on the broadcasting of beacon frames by the network’s gateway in order to synchronize communication with end devices. Our results demonstrate the benefits of FCA-LoRa over an enhanced version of the legacy LoRaWAN employing the ALOHA protocol and an advanced adaptive rate mechanism, in terms of throughput and collision avoidance. Indicatively, in a single gateway scenario with 600 nodes, FCA-LoRa can increase throughput by nearly 50%while in a multiple gateway scenario, throughput reaches an increase of 49% for 500 nodes.

When Should We Perform Endoscopic Drainage and Necrosectomy for Walled-Off Necrosis?

Endoscopic drainage and necrosectomy are now accepted treatment approaches for patients with symptomatic walled-off pancreatic necrosis (WON). The current recommendations advocate step-up approaches for the treatment of symptomatic WON. Previous recommendations stipulated that endoscopic intervention should be delayed until more than four weeks after the onset. Recent data on early drainage have been increasing and this option might be considered in well-encapsulated cases, but the percutaneous route is preferred if the drainage is performed within two weeks after onset or in nonencapsulated cases. Recently, additional drainage methods, such as the multiple gateway technique and multiple stent placement, have been developed to open up multiple dead spaces in the WON cavity. Endoscopic necrosectomy could be performed via the transluminal route or percutaneous route after failed initial and additional drainage procedures. The use of novel lumen-apposing stents is a promising treatment option that could reduce the number of steps, the procedure time, and the overall number of necrosectomies.

Improving transaction success rate in cryptocurrency payment channel networks

Blockchain-based cryptocurrencies has received a substantial interest in the last decade as Blockchain can ensure trust among users without relying on third parties. However, cryptocurrency adoption for micro-payments has been limited due to slow confirmation of transactions and unforeseeable high fees, especially in the case of Bitcoin. To this end, creating off-chain payment channels between users is proposed which enables instant and nearly free transactions without writing to blockchain. Off-chain channel idea is then extended to establish payment channel networks to scale the idea to allow payment routing among many users. However, due to the way these channels are designed, both sides of a channel have a fixed one-way capacity for making transactions. Consequently, if one side consumes the whole one-way capacity, the channel becomes non-transitive in that particular direction, which causes failures of payments that would like to pass through. Eventually, the network becomes partitioned with unevenly distributed funds. In this paper, we propose the adoption of three specific techniques that aim to increase the overall success rate of payments and address channel imbalance problem to keep the payment channel network sustainable in the long run. First, we show the effectiveness of balance-aware routing that better utilizes available funds in the channels. Second, we propose an efficient method for selection of the gateway (i.e., connection point) for a user by considering the gateway’s inbound and outbound capacity. It exploits the fact that end-users can connect the network through multiple gateways any of which can be used to initiate the payment. Finally, we propose proportional payment splitting method to further increase success rate especially for large transactions. We implemented the three approaches for assessing their effectiveness. Compared to existing approaches such as maximum flow or greedy, the proposed approaches can achieve much higher success rates with channels balanced better.

Capture Aware Sequential Waterfilling for LoRaWAN Adaptive Data Rate

LoRaWAN (Long 1 Range Wide Area Network) is an attractive network infrastructure and protocol suite for ultra low power Internet of Things devices. Even if the technology itself is quite mature and specified, the currently deployed wireless resource allocation strategies are still coarse and based on rough heuristics. This paper proposes an innovative “sequential waterfilling” strategy for assigning spreading factors to End Devices. Our design relies on three complementary approaches: i) equalize the Time-on-Air of packets transmitted by the system’s End Devices in each spreading factor’s group; ii) balance the spreading factors across multiple gateways and iii) keep into account the channel capture, which our experimental results show to be very substantial in LoRa. While retaining an extremely simple and scalable implementation, this strategy yields a significant improvement (up to 38%) in the network capacity over the Adaptive Data Rate used by many network operators on the basis of the design suggested by Semtech, and appears to be extremely robust to different operating/load conditions and network topology configurations.

RSS-Based Localization and Mobility Evaluation Using a Single NB-IoT Cell.

Low Power Wide Area Networks (LPWAN) have the ability to localize a mobile transmitter using signals of opportunity, as a low power and low cost alternative to satellite-based solutions. In this paper, we evaluate the accuracy of three localization approaches based on the Received Signal Strength (RSS). More specifically, the performance of a proximity, range-based and optimized fingerprint-based algorithm is evaluated in a large-scale urban environment using a public Narrowband Internet of Things (NB-IoT) network. The results show a mean location estimation error of 340, 320 and 204 m, respectively. During the measurement campaign, we discovered a mobility issue in NB-IoT. In contrast to other LPWAN and cellular technologies which use multiple gateways or cells to locate a device, only a single cell antenna can be used for RSS-based localization in NB-IoT. Therefore, we address this limitation in the current NB-IoT hardware and software by studying the mobility of the cellular-based 3GPP standard in a localization context. Experimental results show that the lack of handover support leads to increased cell reselection time and poor cell sector reliability, which in turn results in reduced localization performance.

Adaptive algorithm for spreading factor selection in LoRaWAN networks with multiple gateways

Recently, LoRaWAN has been considered a promising technology for large-scale IoT applications owing to its ability to achieve low power and long range communications. However, LoRaWAN is limited using Aloha random access scheme. When in dense scenarios, such scheme leads to a high number of collisions, thus severely impacts the reliability and scalability of LoRaWAN. In this paper, we investigate the impact of scalability and densification of nodes and gateways on the system reliability taking into account the capture effect. We propose an optimization problem to derive the node distribution at different spreading factors (SF) in LoRaWAN networks with multiple gateways. We then introduce an adaptive algorithm that enables to easily implement SF optimization by adjusting the signal-to-noise ratio thresholds. Moreover, the performance of the proposed algorithm is compared with the performance of legacy LoRaWAN and relevant algorithms from the state-of-the-art. Simulation results show that the proposed algorithm significantly outperforms the state-of-the-art algorithms, and improves the throughput and packet delivery ratio of the network.

Single-step endoscopic ultrasound-guided multiple gateway drainage of complex walled-off necrosis with lumen apposing metal stents

In this study we analyzed the feasibility and safety of single-step multiple transluminal gateway drainage (MTGD) for complex walled-off necrosis (WON) using lumen-apposing metal stents (LAMSs). Six patients underwent endoscopic ultrasound (EUS)-guided MTGD using two LAMSs. Technical success was 100%. The mean procedure time was 29 min. The mean number of direct endoscopic necrosectomy sessions per patient was 2. Two of six patients developed adverse events, which was bleeding in both cases and treated endoscopically and surgically, respectively. The mean hospital stay was 52.5 days. No patients had residual necrosis or WON recurrence. Although the limited number of patients, the single-step MTGD using electrocautery-LAMSs can be considered a feasible and well-tolerated treatment option for patients with complex WON. Nevertheless, larger randomized controlled studies are needed in order to confirm our data and better define the advantages of this technique.

Load-Balancing Algorithm for Multiple Gateways in Fog-Based Internet of Things

This article investigates the performance of multicriteria-based load-balancing scheme among gateways in fog-assisted Internet of Things (IoT). We employ a queueing model of the IoT system to calculate the latency of data streams from the IoT devices to the applications. However, a gateway node may easily become congested since all the traffic to IP networks are directed toward the gateway. A congested point can affect system performance and may cause reliability problems in the system. Thus, we employ multiple gateways to alleviate the performance degradation of the network, along with a multicriteria decision-making (MCDM)-based load-balancing policy among the gateways to achieve a global load fairness. The proposed model is evaluated in single-hop IPv6 over low-power wireless personal area networks (6LoWPANs). The evaluation results show the effectiveness of the proposed load-balancing model in providing fast and reliable responses to user queries.

Multiple gateway placement in large‐scale constellation networks with inter‐satellite links

SummaryMultiple gateways are required in large satellite constellation networks (LSCNs) with inter‐satellite links (ISLs), and their placement may greatly affect the system performance. Gateway placement can be optimized to achieve better network performance under the non‐uniform ground demand distribution. This paper formulates a gateway placement optimization model for LSCN with ISLs, aiming at achieving an optimal overall performance including delay, traffic peak, and load balance. The constraints of potential gateway location, gateway‐satellite connectivity, and max hop‐count are considered. A genetic algorithm (GA)‐based method is proposed to solve the integer optimization problem with the help of quasi‐evenly distributed reference layout. A Starlink‐like constellation with ISLs is adopted in the simulation. The simulation results show that the optimized layout has better performance than the reference layout. Additionally, the locations with high user demand or at the middle of ocean are preferred by gateways. The network performance is jointly influenced by gateway placement, demand distribution, constellation configuration, node, and link capacities. The abnormally high ISL hop‐count is found in the south Indian Ocean, which is caused by constellation and ISL configuration.

Reconstruction of Holocene oceanographic conditions in eastern Baffin Bay

Abstract. Baffin Bay is a semi-enclosed basin connecting the Arctic Ocean and the western North Atlantic, thus making out a significant pathway for heat exchange. Here we reconstruct the alternating advection of relatively warmer and saline Atlantic waters versus the incursion of colder Arctic water masses entering Baffin Bay through the multiple gateways in the Canadian Arctic Archipelago and the Nares Strait during the Holocene. We carried out benthic foraminiferal assemblage analyses, X-ray fluorescence scanning, and radiocarbon dating of a 738 cm long marine sediment core retrieved from eastern Baffin Bay near Upernavik, Greenland (Core AMD14-204C; 987 m water depth). Results reveal that eastern Baffin Bay was subjected to several oceanographic changes during the last 9.2 kyr. Waning deglacial conditions with enhanced meltwater influxes and an extensive sea-ice cover prevailed in eastern Baffin Bay from 9.2 to 7.9 ka. A transition towards bottom water amelioration is recorded at 7.9 ka by increased advection of Atlantic water masses, encompassing the Holocene Thermal Maximum. A cold period with growing sea-ice cover at 6.7 ka interrupts the overall warm subsurface water conditions, promoted by a weaker northward flow of Atlantic waters. The onset of the neoglaciation at ca. 2.9 ka is marked by an abrupt transition towards a benthic fauna dominated by agglutinated species, likely in part explained by a reduction of the influx of Atlantic Water, allowing an increased influx of the cold, corrosive Baffin Bay Deep Water originating from the Arctic Ocean to enter Baffin Bay through the Nares Strait. These cold subsurface water conditions persisted throughout the Late Holocene, only interrupted by short-lived warmings superimposed on this cooling trend.

Performance Analysis of Cooperative Low-Power Wide-Area Network for Energy-Efficient B5G Systems

Low-power wide-area networks (LPWANs) have received extensive attention from both academia and industry, since they can efficiently provide massive connectivity to internet of things (IoT) devices in wide geographical areas with low cost and low power consumption. Recently, it was shown that macro-diversity among multiple gateways significantly improves the performance of uplink LPWANs by coherently combining multiple received signals at gateways. We call such networks cooperative LPWANs. In this paper, the error performance of an uplink cooperative LPWAN is mathematically analyzed in terms of outage probability, bit error rate (BER), and diversity order. It is assumed that there exist multiple (two or more) gateways that have multiple antennas and are located at arbitrary positions in the LPWAN area. Each gateway exploits the optimal maximum-ratio combining (MRC) technique to decode the received signal, and then the signals after MRC are delivered to the cloud fusion center for coherent combining in the cooperative LPWAN. The main results, the closed-form expressions of outage probability and BER, were derived by utilizing the hyper-Erlang distribution. Furthermore, the macro-diversity order was mathematically derived. The mathematical analysis was validated through extensive computer simulations. It worth noting that the mathematical analysis of the error performance of cooperative LPWANs is the first theoretical result in the literature to the best of our knowledge.

A Comprehensive Review on Device-to-Device Communication Paradigm: Trends, Challenges and Applications

Sensors and smartphones are used in industry and healthcare technology for data gathering. The sensed data can be acquired by devices and processed through multiple gateways to the Internet of things (IoT) enabled cloud framework. Device-to-device (D2D) communication paradigm is a central part of the third generation partnership project standards to facilitate peer-to-peer connectivity that will be an important part of IoT. There is no centralized control in D2D which strengthens the wireless networks more energy-efficient and spectrum. The D2D enhances the data transmission process with advance security schemes and also improves the quality of service. This paper surveyed recent works on D2D, which is mainly focused on resource allocation, power consumption, security, and also highlights the major challenges. The role of D2D communication systems in healthcare has been discussed here.

RIoT: A Routing Protocol for the Internet of Things†

AbstractThe routing protocol for low-power and lossy networks (RPL) is a standard routing framework for Internet of Things (IoT). It supports multipoint-to-point (MP-to-P), point-to-point (P-to-P) and point-to-multipoint (P-to-MP) communications. It is known that RPL’s control overhead can result in the protocol’s poor performance in P-to-P and P-to-MP communications especially in its non-storing mode of operation. Here, we present a routing protocol for the Internet of Things (RIoT) that supports MP-to-P, P-to-P and P-to-MP communications. The protocol can construct P-to-P and P-to-MP routes with relatively lower control overhead. Another salient feature of RIoT is that it supports multiple gateways in the same network with an aim to reduce memory requirement for storing a forwarding table. Furthermore, RIoT is also capable of handling mobility-based IoT use cases. To facilitate communication among nodes connected to different gateways in the same network, here we also present an inter-gateway communication mechanism. We implemented RIoT in the Contiki operating system, and it is extensively evaluated using emulation and real testbed-based experiments. We analyzed the impact of the number of gateways, radio duty cycling (RDC) and mobility on the routing protocols’ performance. Our results demonstrate that either with or without RDC RIoT demonstrates statistically significantly better packet delivery ratio, per-packet end-to-end delay and control overhead compared to the RPL-based protocol. RIoT’s multi-gateway communication architecture substantially reduces the memory requirement to store a forwarding table. Our results also demonstrate that multiple gateways in a network reduce the network partitioning problem in mobile scenarios. Hence, RIoT also demonstrates better performance in mobile scenarios compared to the RPL-based protocol.

Opportunistic LoRa-based gateways for delay-tolerant sensor data collection in urban settings

There are several ways that sensor nodes in a smart city setting can get data to a base station for processing. Sensor nodes that need not report their data to the base station in real time can opt for a delay-tolerant networking or data muling setup. If the data collector itself would send the data to the internet through its own (mobile) backhaul link, we can consider the data collector to be a mobile gateway. The choice of radio technology for the link between the sensor or end device and the mobile gateway is important: it would affect the number of mobile gateways needed, the required mobility pattern for them to provide a certain level of delay guarantees to the data, and the overall efficiency of the scheme. LoRa, with its long range and relatively low power consumption, can potentially decrease the number of gateways needed in the system, while decreasing delays. This study explores opportunistic, mobile LoRa-based gateways using a pull-based transfer of data to implement a low cost system in terms of communication and the hardware used. We present a MAC layer protocol, for use with the LoRa radio/physical layer, with three gateway operation modes: Independent, Pure Pass Through, and Instruction-based.Comparison with a more traditional baseline system with push-based transfer of data reveals that our pull-based system performs better in terms of percentage of data points that are successfully sent by the end devices to the network server. We also evaluate the performance and scalability of the three modes using a small campus-wide deployment and discrete-event simulations. Experiments reveal that of the three modes, the Instruction-based mode is the most balanced in terms of computation power requirement and communication costs. In this mode, the network server handles the computation load, while the gateway handles the generation of the beacons. This shows a better result compared to the other modes wherein the computation load and beacon generation is condensed in the gateway or the network server. This also follows that the communication cost is high in the latter setup since it is dependent on the connection between the gateway and the network server. Our results also show that while utilizing multiple gateways can result in lower delays, they have to be used carefully, since the existence of multiple gateways in the system can easily result to problems with interference, possibly degrading, instead of improving, the performance of the system.

Scalability Performance for Low Power Wide Area Network Technology using Multiple Gateways

Low Power Wide Area Network is one of the leading technologies for the Internet of Things. The capability to scale is one of the advantage criteria for a technology to compare to each other. The technology uses a star network topology for communication between the end-node and gateway. The star network topology enables the network to support a large number of end-nodes and with multiple of gateways deployed in the network, it can increase the number of end nodes even more. This paper aims to investigate the performance of the Low Power Wide Area Network Technology, focusing on the capability of the network to scale using multiple gateways as receivers. We model the network system based on the communication behaviours between the end-node and gateways. We also included the communication limit range for the data signal from the end-node to successfully be received by the gateways. The performance of the scalability for the Low Power Wide Area Network Technology is shown by the successfully received packet data at the gateways. The simulation to study the scalability was done based on several parameters, such as the number of end-nodes, gateways, channels and also application time. The results show that the amount of successfully received data signal at gateway increased as the gateways, application time and channel used increased.

A Hybrid Approach to Enhance Scalability, Reliability and Computational Speed in LoRa Networks

The spreading out of Internet of Things (IoT) facilitates with new wireless communication Technologies. To have reliable communication for long duration, low power wide area can be aimed at sensor nodes. These days, LoRa has become a recognizable preference for IoT based solutions. In this paper LoRa network performance is analyzed. A hybrid technique is proposed to overcome the scalability, reliability and computational speed issues in LoRa network. In the proposed hybrid technique, a lightweight scheduling technique is used to address scalability and reliability issues and then pruning algorithm is also incorporated to enhance the computational speed of LoRa network for IoT applications. Further, LoRa network for IoT applications is analyzed using LoRaWAN NS-3 module and the parameters packet error ratio (PER), network throughput and fairness for improved reliability and scalability are illustrated. Simulation results are obtained for multiple gateways scenarios. The analysis presents that the LoRa network has addressed scalability and reliability issues using lightweight scheduling technique and computational speed is also enhanced using pruning algorithm. Therefore, the hybrid technique illustrated for LoRa network for IoT applications is in good agreement.

A data dissemination scheme for a wireless nanosensor network towards IoNT

Nanotechnology has gained significant importance in many fields, especially biological, industrial, military, and environmental sectors. Rapid advancements in nanotechnology have led to the development of wireless nanosensor networks (WNSNs). Most researchers focus on addressing resource limitations constraints and ignore the dynamic channel state. Therefore, in this paper, we design a fine-grained, lightweight, and energy-efficient end-to-end data dissemination scheme for WNSN that takes into consideration the dynamic channel state problem and energy efficiency. Simulation results showed that the proposed scheme outperforms TEForward in terms of energy consumption and packet delivery ratio. The effect of employing multiple gateways is also investigated.