Evaluation, Modeling and Optimization of Coverage Enhancement Methods of NB-IoT

Narrowband Internet of Things (NB-IoT) is a new Low Power Wide Area Network (LPWAN) technology released by 3GPP. The primary goals of NB-IoT are improved coverage, massive capacity, low cost, and long battery life. In order to improve coverage, NB-IoT has promising solutions, such as increasing transmission repetitions, decreasing bandwidth, and adapting the Modulation and Coding Scheme (MCS). In this paper, we present an implementation of coverage enhancement features of NB-IoT in NS-3, an end-to-end network simulator. The resource allocation and link adaptation in NS-3 are modified to comply with the new features of NB-IoT. Using the developed simulation framework, the influence of the new features on network reliability and latency is evaluated. Furthermore, an optimal hybrid link adaptation strategy based on all three features is proposed. To achieve this, we formulate an optimization problem that has an objective function based on latency, and constraint based on the Signal to Noise Ratio (SNR). Then, we propose several algorithms to minimize latency and compare them with respect to accuracy and speed. The best hybrid solution is chosen and implemented in the NS-3 simulator by which the latency formulation is verified. The numerical results show that the proposed optimization algorithm for hybrid link adaptation is eight times faster than the exhaustive search approach and yields similar latency

A Distributed Management Scheme for supporting energy-harvested I/O devices

Current wireless technologies for industrial application, such as WirelessHART and ISA100.11a, are not designed to support harvester-powered input/output (I/O) devices, where energy availability varies in a non-deterministic manner. The centralized management approach of these standards makes it difficult and costly for harvester-powered I/O devices (sensor/actuators) to re-join in the network in case of power failure. The communication overhead and delay to cope with the dynamic environment of a large-scale industrial network are also very high for an I/O device. In this paper, we therefore propose a Distributed Management scheme for Hybrid networks to provide Real-time communication (D-MHR) based on the IEEE 802.15.4e and Routing Protocol for Low power and Lossy Networks (RPL) standards, which can address the requirements of energy constrained I/O devices. In D-MHR, the routers can dynamically reserve communication resources and manage the I/O devices in the local star sub-networks. We demonstrate that D-MHR achieves higher network management efficiency compared to IS100.11a standard, without compromising the latency and reliability requirements of industrial wireless networks

D-MSR: A Distributed Network Management Scheme for Real-Time Monitoring and Process Control Applications in Wireless Industrial Automation

Current wireless technologies for industrial applications, such as WirelessHART and ISA100.11a, use a centralized management approach where a central network manager handles the requirements of the static network. However, such a centralized approach has several drawbacks. For example, it cannot cope with dynamicity/disturbance in large-scale networks in a real-time manner and it incurs a high communication overhead and latency for exchanging management traffic. In this paper, we therefore propose a distributed network management scheme, D-MSR. It enables the network devices to join the network, schedule their communications, establish end-to-end connections by reserving the communication resources for addressing real-time requirements, and cope with network dynamicity (e.g., node/edge failures) in a distributed manner. According to our knowledge, this is the first distributed management scheme based on IEEE 802.15.4e standard, which guides the nodes in different phases from joining until publishing their sensor data in the network. We demonstrate via simulation that D-MSR can address real-time and reliable communication as well as the high throughput requirements of industrial automation wireless networks, while also achieving higher efficiency in network management than WirelessHART, in terms of delay and overhead

Implementation of WirelessHART in the NS-2 Simulator and Validation of Its Correctness

One of the first standards in the wireless sensor networks domain,WirelessHART (HART (Highway Addressable Remote Transducer)), was introduced to address industrial process automation and control requirements. This standard can be used as a reference point to evaluate other wireless protocols in the domain of industrial monitoring and control. This makes it worthwhile to set up a reliable WirelessHART simulator in order to achieve that reference point in a relatively easy manner. Moreover, it offers an alternative to expensive testbeds for testing and evaluating the performance of WirelessHART. This paper explains our implementation of WirelessHART in the NS-2 network simulator. According to our knowledge, this is the first implementation that supports the WirelessHART network manager, as well as the whole stack (all OSI (Open Systems Interconnection model) layers) of the WirelessHART standard. It also explains our effort to validate the correctness of our implementation, namely through the validation of the implementation of the WirelessHART stack protocol and of the network manager. We use sniffed traffic from a realWirelessHART testbed installed in the Idrolab plant for these validations. This confirms the validity of our simulator. Empirical analysis shows that the simulated results are nearly comparable to the results obtained from real networks. We also demonstrate the versatility and usability of our implementation by providing some further evaluation results in diverse scenarios. For example, we evaluate the performance of the WirelessHART network by applying incremental interference in a multi-hop network

Decentralized management schemes for real-time and reliable communication in industrial wireless sensor and actuator networks

Current wireless technologies for industrial applications, such asWirelessHART and ISA100.11a, use a centralized management approach in which a central network manager handles the requirements of the static network. However, such a centralized approach has several drawbacks. For example, it cannot cope with dynamicity/disturbance in large-scale networks in a real-time manner while it also incurs a high communication overhead and latency for exchanging management traffic. \ud In this thesis, we address the drawbacks of the centralized management approach utilized in WirelessHART and ISA100.11a for real-time industrial monitoring and control applications. More specifically, we propose new decentralized network management schemes to provide an end-to-end reliable and real-time communication for battery-powered and harvested-powered devices in a distributed manner. These schemes enable the network devices to join the network, schedule their communications, establish end-to-end connections by reserving communication resources to address real-time requirements, and cope with network dynamicity (e.g., node/edge failures) in a distributed manner. \ud To evaluate wireless protocols in the domain of industrial monitoring and control, a reference point is needed. To that end, we developed aWirelessHART simulator in NS-2 as a reference point to evaluate other protocols. We validated theWirelessHART simulator with a WirelesHART deployment at an industrial plant. To the best of our knowledge, this is the first implementation that supports the WirelessHART network manager as well as the whole stack of the WirelessHART standard. \ud To address the requirements of battery-powered I/O devices, we propose a distributed management scheme to address real-time and reliable communication requirements. This scheme considers the full mesh topology in which I/O devices are capable of participating in routing and distributed network management tasks, such as communication resources scheduling. \ud We then propose a second distributed management scheme for hybrid networks to be used for real-time industrial wireless automation. This scheme addresses the requirements of energy constrained I/O devices. In this scheme, the I/O devices cannot participate in routing and distributed management tasks. The routers can dynamically reserve communication resources and manage the I/O devices in the local star sub-networks. We demonstrate that the proposed scheme achieves higher network management efficiency compared to the ISA100.11a standard, without compromising the latency and reliability requirements of industrial wireless networks. \ud To better support and address the requirements of energy harvested I/O devices, we extend ISA100.11a. The proposed extension makes management more decentralized by delegating a part of the management responsibility to the routers in the network. It also allows the I/O devices to choose the best routers according to different metrics using local statistics and advertised routers’ ranks

D-MSR: A Distributed Network Management Scheme for Real-Time Monitoring and Process Control Applications in Wireless Industrial Automation

Current wireless technologies for industrial applications, such as WirelessHART and ISA100.11a, use a centralized management approach where a central network manager handles the requirements of the static network. However, such a centralized approach has several drawbacks. For example, it cannot cope with dynamicity/disturbance in large-scale networks in a real-time manner and it incurs a high communication overhead and latency for exchanging management traffic. In this paper, we therefore propose a distributed network management scheme, D-MSR. It enables the network devices to join the network, schedule their communications, establish end-to-end connections by reserving the communication resources for addressing real-time requirements, and cope with network dynamicity (e.g., node/edge failures) in a distributed manner. According to our knowledge, this is the first distributed management scheme based on IEEE 802.15.4e standard, which guides the nodes in different phases from joining until publishing their sensor data in the network. We demonstrate via simulation that D-MSR can address real-time and reliable communication as well as the high throughput requirements of industrial automation wireless networks, while also achieving higher efficiency in network management than WirelessHART, in terms of delay and overhead

Cooperative coexistence of BLE and time slotted channel hopping networks

The Bluetooth Low Energy (BLE) and Time Slotted Channel Hopping (TSCH) mode of the IEEE 802.15.4 are two of the most widely used technology standards for Wireless Sensor Networks (WSNs). In many applications, both technologies need to be used in the same environment to fulfill application requirements. However, since they share the same 2.4 GHz ISM band, such networks may suffer from cross-technology interference, which decreases the reliability of the network. To solve this problem, we propose a cooperative coexistence solution for BLE and TSCH networks in which joint time-slot and channel hopping synchronization are performed. The proposed solution uses a scheduling matrix to model the resource usage of the networks. Following this, the overlaps in this matrix are eliminated by rescheduling the transmissions of the networks. The proposed solution does not require any protocol change. The performance of the proposed cooperative coexistence mechanism is evaluated using experiments with real wireless devices. The results of those show that our proposed solution considerably decreases Packet Error Rate (PER); an improvement of up to 45% PER is observed

Unbearable Lightness:Czech Brutalist Archicture

One of the first standards in the wireless sensor networks domain, WirelessHART, was introduced to address industrial process automation and control requirements. The standard can be used as a reference point to evaluate other wireless protocols in the domain of industrial monitoring and control. This makes it worthwhile to set up a reliable WirelessHART simulator to achieve that reference point in a relatively easy way. This paper explains our implementation of WirelessHART in the NS-2 simulator. According to our knowledge, this is the first implementation that supports the WirelessHART network manager as well as the whole stack of the WirelessHART standard. We evaluated the performance of our implementation in terms of delay and communication load in the network. This implementation offers an alternative to expensive testbeds for testing WirelessHART

Time-domain cooperative coexistence of BLE and IEEE 802.15.4 networks

Wireless sensor networks have entered into our lives, and are expected to be even more widespread in the near future. Bluetooth Low Energy (BLE) and IEEE 802.15.4 are two low-power wireless standards that are widely used in sensor network applications. They share the same unlicensed 2.4 GHz ISM spectrum. To be able to employ both technologies in the same environment in a heterogeneous network, the creation of a proper coexistence mechanism is imperative. In this paper, we propose and develop a cooperative mechanism for the coexistence of co-located IEEE 802.15.4 and BLE networks in the time domain. This mechanism tries to avoid overlap of communications in these networks in order to decrease the chance of Cross-Technology Interference (CTI) and thus packet drops. The proposed mechanism does not impose any protocol change. The performance of the proposed mechanism is evaluated by using real hardware devices. The experimental results show that the overall packet reception ratio improves up to 12%