Showing papers on "Wireless mesh network published in 2021"

Deep Reinforcement Learning for Communication Flow Control in Wireless Mesh Networks

Abstract: Wireless mesh network (WMN) is one of the most promising technologies for Internet of Things (IoT) applications because of its self-adaptive and self-organization nature To meet different performance requirements on communications in WMNs, traditional approaches always have to program flow control strategies in an explicit way In this case, the performance of WMNs will be significantly affected by the dynamic properties of underlying networks in real applications With providing a more flexible solution in mind, in this article, for the first time, we present how we can apply emerging Deep Reinforcement Learning (DRL) on communication flow control in WMNs Moreover, different from a general DRL based networking solution, in which the network properties are pre-defined, we leverage the adaptive nature of WMNs and propose a self-adaptive DRL approach Specifically, our method can reconstruct a WMN during the training of a DRL model In this way, the trained DRL model can capture more properties of WMNs and achieve better performance As a proof of concept, we have implemented our method with a self-adap-tive Deep Q-learning Network (DQN) model The evaluation results show that the presented solution can significantly improve the communication performance of data flows in WMNs, compared to a static benchmark solution

Efficient and Secured Swarm Pattern Multi-UAV Communication

Abstract: Unmanned Aerial Vehicle (UAV) or drone, is an evolving technology in today's market with an enormous number of applications. Mini UAVs are developed in order to compensate the performance constraints imposed by larger UAVs during emergency situations. Multiple mini autonomous UAVs require communication and coordination for ubiquitous coverage and relaying during deployment. Multi-UAV coordination or swarm optimization is required for reliable connectivity among UAVs, due to its high mobility and dynamic topology. In this paper, a Secured UAV (S-UAV) model is proposed which takes the location of the UAVs as inputs to form a Wireless Mesh Network (WMN) among multiple drones with the help of a centralized controller. After WMN formation, efficient communication takes place using A* search, an intelligent algorithm that finds the shortest communication path among UAVs. Further, the S-UAV model utilizes cryptographic techniques such as Advanced Encryption Standard (AES) and Blowfish to overcome the security attacks efficiently. Simulation results show that the S-UAV model offers higher throughput, reduced power consumption and guaranteed message transmission with reduced encryption and decryption time.

The Performance Analysis of Spectrum Sharing Between UAV Enabled Wireless Mesh Networks and Ground Networks

Abstract: Unmanned aerial vehicle (UAV) has the advantages of large coverage and flexibility, which could be applied in disaster management to provide wireless services to the rescuers and victims. When UAVs forms an aerial mesh network, line-of-sight (LoS) air-to-air (A2A) communications have long transmission distance, which extends the coverage of multiple UAVs. However, the capacity of UAV is constrained due to the multiple hop transmissions in aerial mesh networks. In this paper, spectrum sharing between UAV enabled wireless mesh networks and ground networks is studied to improve the capacity of UAV networks. Considering two-dimensional (2D) and three-dimensional (3D) homogeneous Poisson point process (PPP) modeling for the distribution of UAVs within a vertical range $\Delta \textit h$ , stochastic geometry is applied to analyze the impact of the height of UAVs, the transmit power of UAVs, the density of UAVs and the vertical range, etc., on the coverage probability of ground network user and UAV network user. Besides, performance improvement of spectrum sharing with directional antenna is verified. With the object function of maximizing the transmission capacity, the optimal altitude of UAVs is obtained. This paper provides a theoretical guideline for the spectrum sharing of UAV enabled wireless mesh networks, which may contribute significant value to the study of spectrum sharing mechanisms for UAV enabled wireless mesh networks.

Privacy reinforcement learning for faults detection in the smart grid

Abstract: Recent anticipated advancements in ad hoc Wireless Mesh Networks (WMN) have made them strong natural candidates for Smart Grid’s Neighborhood Area Network (NAN) and the ongoing work on Advanced Metering Infrastructure (AMI). Fault detection in these types of energy systems has recently shown lots of interest in the data science community, where anomalous behavior from energy platforms is identified. This paper develops a new framework based on privacy reinforcement learning to accurately identify anomalous patterns in a distributed and heterogeneous energy environment. The local outlier factor is first performed to derive the local simple anomalous patterns in each site of the distributed energy platform. A reinforcement privacy learning is then established using blockchain technology to merge the local anomalous patterns into global complex anomalous patterns. Besides, different optimization strategies are suggested to improve the whole outlier detection process. To demonstrate the applicability of the proposed framework, intensive experiments have been carried out on well-known CASAS (Center of Advanced Studies in Adaptive Systems) platform. Our results show that our proposed framework outperforms the baseline fault detection solutions.

Towards Secure Wireless Mesh Networks for UAV Swarm Connectivity: Current Threats, Research, and Opportunities

Abstract: UAVs are increasingly appearing in swarms or formations to leverage cooperative behavior, forming flying ad hoc networks. These UAV-enabled networks can meet several complex mission requirements and are seen as a potential enabler for many of the emerging use-cases in future communication networks. Such networks, however, are characterized by a highly dynamic and mobile environment with no guarantee of a central network infrastructure which can cause both connectivity and security issues. While wireless mesh networks are envisioned as a solution for such scenarios, these networks come with their own challenges and security vulnerabilities. In this paper, we analyze the key security and resilience issues resulting from the application of wireless mesh networks within UAV swarms. Specifically, we highlight the main challenges of applying current mesh technologies within the domain of UAV swarms and expose existing vulnerabilities across the communication stack. Based on this analysis, we present a security-focused architecture for UAV mesh communications. Finally, from the identification of these vulnerabilities, we discuss research opportunities posed by the unique challenges of UAV swarm connectivity.

An Accelerated End-to-End Probing Protocol for Narrowband IoT Medical Devices

Abstract: In this study, a narrowband internet of things (NB-IoT) medical device (MD) was presented. We consider a wireless communication system where the multi-hop sources shared the downlink and uplink resources to probe and control hospital patients’ MDs.A multicast data packet was distributed over the multi-hop MD networks, and a random linear network coding approach was applied in the source instead of the intermediate nodes. We evaluated the MD probe cycle between a master station and remote terminal units, which were connected with several critical devices in a medical room. Furthermore, an accelerated end-to-end (E2E) probing protocol was established in the wireless mesh network to minimize the probing cycle of the health devices. In particular, a faster protocol was developed to address the probe and control subproblem.The proposed approach could assist in realizing the accelerated E2E probing for NB-IoT MDs, reducing the number of retransmissions, recovering lost packets, and providing a prompt overview of the medical network performance,based on several basic parameters such as modulation types, Quadrature amplitude modulation (QAM) and Frequency-shift keying (FSK), acknowledgment (ACK), average message sizes AMS, subcarrier spacing (SCS). Furthermore, in a comparative study of the contemporary probing cycle techniques, the proposed protocol notably outperformed several widely used protocols,with the reduction of the number of transmissions as well as the improvement of round trip time (RTT), and E2E probing cycle exceeding 89%, 71%, and 60%, respectively.

Accelerated PSO algorithm applied to clients coverage and routers connectivity in wireless mesh networks

Abstract: The deployment of wireless mesh routers is a crucial task for improving network performance. Therefore, it should be taken seriously to ensure the network accessibility in terms of coverage and connectivity. This placement problem of mesh routers in wireless mesh networks represents an instance of multi-objective optimization problems with huge searching space to explore. In the literature, various optimization algorithms have been applied to find a trade-off between client coverage and network connectivity. To find an optimal mesh router placement, in this paper, we consider Accelerated particle swarm optimizer (APSO) due to its rapid convergence and low computational complexity compared to other population-based algorithms. We have experimentally evaluated it using different generated benchmarks of multiple configurations. The experimental results show that APSO algorithm provides very promising results compared to linearly decreasing weight particle swarm optimizer (LDWPSO).

A Coverage Construction and Hill Climbing Approach for Mesh Router Placement Optimization: Simulation Results for Different Number of Mesh Routers and Instances Considering Normal Distribution of Mesh Clients

Abstract: The Wireless Mesh Networks (WMNs) enables routers to communicate with each other wirelessly in order to create a stable network over a wide area at a low cost and it has attracted much attention in recent years. There are different methods for optimizing the placement of mesh routers. In our previous work, we proposed a Coverage Construction Method (CCM) and CCM-based Hill Climbing (HC) system for mesh router placement problem considering normal and uniform distributions of mesh clients. In this paper, we evaluate performance of CCM-based HC system for different number of mesh routers and instances. For the simulation results, we found that the CCM-based HC system was able to cover more mesh clients for different instances compared with CCM.

QoS Provisioning in Wireless Mesh Networks: A Survey

Abstract: With the recent developments in Wireless Mesh Networks (WMN), provisioning of Quality of Service (QoS) for real time applications is considered as an important but challenging area of research. QoS support for various real time applications are implemented in different layers of the protocol stack. The diversity of such research efforts has contributed to many protocols/schemes. This paper presents a comprehensive survey on various QoS enhancement schemes reported in the literature covering various angles of research domains. Diversified QoS challenges in WMNs and their reported solutions proposed in the literature are discussed using a layered approach. While presenting the state of the art research findings in MAC and routing, a classification framework for each of the layers is proposed first. The classification frameworks provide unified approaches for categorizing different protocols based on their distinctive features and sketch their correlations. However, the proposals for leveraging TCP performance in WMN have been discussed straightaway. Further, this paper provides an insight into the pros and cons of the surveyed protocols and points out the open research challenges for the future generation networking.

Deterministic cooperative hybrid ring-mesh network coding for big data transmission over lossy channels in 5G networks

Abstract: Wired and wireless communication data is getting bigger and bigger at such a high pace. Accordingly, the big data (BD) communication networks should be developed as quickly as the quick increase in the exchanging data size is. Based on this regard, this paper proposes a wired and wireless protocol that applies cooperation Network coding (CoNC) in a wired ring topology (WRT) to improve exchanging the BD significantly in wireless mesh network (WMN). The paper presents a solution for distributed nodes to deal with big data over 5G by proposing Hybrid Ring-Mesh Protocols (HRMP) that exploit the CoNC technique at distributed nodes. The proposed protocol (X-ORING) deterministically combines the data that is received at a base station (BS), where the BS wirelessly retransmits the combined data to the WMN members, instead of just forwarding them to the WMN members. Moreover, all members of the WMN are connected by wired optical fibre channels in a WRT and directly to the BS. The results show that applying CoNC in the proposed protocols exploits the advantages of the WRP between the WMN members, and consequently, the WMN packet error rate is significantly improved. Moreover, using optical fibre wires between the mesh network members and the BS increases the WMN coverage region considerably, and allows the BS to receive all members' packets correctly. Finally, the results show that applying CoNC on the WRT improves the entire network maintenance and reliability greatly, simply because the proposed HRMP can continue broadcasting even if one of the direct optical fibre goes out of serves, i.e. the fibre link between one of the N member and the BS lost the connectivity.

An optimized distributed secure routing protocol using dynamic rate aware classified key for improving network security in wireless sensor network

Abstract: To transmit information over the industrial network today, you need data in a secure way to make it a high security root. Routing security issues in the wireless web network have been well studied. The problem of security in routing in wireless mesh networks (WMN) has been well studied. There exist numerous techniques to resolve this issue but differ and suffer to achieve higher security performance in WMN. To resolve this issue, a dynamic rate aware classified key distributional secure routing (DRCKDS) is proposed. In this approach, the sensor nodes maintain various factors related to the neighbor like energy, transmission involvement, rate of success and so on. According to this, available routes are identified to reach the destination from the source. For each route identified, the method computes the secure route measure (SRM). According to the SRM value, an optimal route is selected for the transmission. Similarly, the method generates different secret keys and distributes them through the transmission route selected. The same key has been used to encrypt the data and forward the packet through the route selected. The method improves the security performance and improves the quality of service of WMN.

Load balancing routing under constraints of quality of transmission in mesh wireless network based on software defined networking

Abstract: Load balancing routing and quality of transmission (QoT) aware routing have been increasingly studied in mesh wireless networks (WMN) to improve their performance. For the load balancing routing, the traffic bottleneck in the network can be resolved. However, it can decrease QoT because the routes may passthrough multiple hops. On the other hand, the QoT aware routing often improves the QoT of the routes, but it can increase thetraffic bottleneck due to the unbalanced traffic load in the network. Therefore, the investigation of load balancing routing taking into account QoT is very essential, especially in the case of a wideand ultra-high speed WMN. In this paper, we propose a load balancing routing algorithm under the constraints of QoT for WMN. Our method uses the principle of the software defined networking (SDN) to choose the load balancing routes satisfying the constraints of QoT. Our performance evaluations using OMNeT+ have shownthe effectiveness of the proposed algorithm in improving QoT of thedata transmission routes, increasing the packet delivery ratio andthe network throughput, decreasing the end-to-end delay.

Sensor array for wireless remote monitoring of carbon dioxide and methane near carbon sequestration and oil recovery sites

Abstract: Carbon sequestration and enhanced oil recovery are two important geochemical applications currently deployed using carbon dioxide (CO2), a prevalent greenhouse gas Despite the push to find ways to use and store excess CO2, the development of a large-area monitoring system is lacking For these applications, there is little literature reporting the development and testing of sensor systems capable of operating in remote areas without maintenance and having significantly low cost to allow their deployment across a large land area This paper presents the design and validation of a low-cost solar-power distributed sensing architecture using a wireless mesh network integrated, at selective nodes, into a cellular network This combination allows an “internet of things” approach in remote locations and the integration of a large number of sensor units to monitor CO2 and methane (CH4) This system will allow efficient large area monitoring of both rare catastrophic leaks along with the common micro-seepage of greenhouse gas near carbon sequestration and oil recovery sites The deployment and testing of the sensor system was performed in an open field at Oklahoma State University The two-tear network functionality and robustness were determined from a multi-year field study The reliability of the system was benchmarked by correlating the measured temperature, pressure, and humidity measurement by the network of devices to existing weather data The CO2 and CH4 gas concentration tracked their expected daily and seasonal cycles This multi-year field study established that this system can operate in remote areas with minimal human interactions

A Comparison Study of Linearly Decreasing Inertia Weight Method and Rational Decrement of Vmax Method for WMNs Using WMN-PSOHC Intelligent System Considering Normal Distribution of Mesh Clients

Abstract: Wireless Mesh Networks (WMNs) are becoming an important networking infrastructure. However, they have some problems such as node placement, security, transmission power and so on. To solve node placement problem in WMNs, we have implemented a hybrid simulation system based on PSO and HC called WMN-PSOHC. In this paper, we present the performance evaluation of WMNs by using WMN-PSOHC intelligent system considering Linearly Decreasing Inertia Weight Method (LDIWM) and Rational Decrement of Vmax Method (RDVM). The simulation results show that a better performance is achieved for LDIWM compared with the RDVM.

Simulation Results of CCM Based HC for Mesh Router Placement Optimization Considering Two Islands Model of Mesh Clients Distributions

Abstract: Wireless mesh networks (WMNs) are one of the wireless network technologies that enables routers to communicate with each other wirelessly to create a stable network over a wide area at a low cost, and it has attracted much attention in recent years. In order to provide a lower cost and more stable network, various methods for optimizing the placement of mesh routers are being studied. In a previous work, we proposed a Coverage Construction Method (CCM) and CCM based Hill Climbing (HC) for mesh router placement problem considering normal and uniform distribution of mesh clients. In this paper, we evaluate the performance of CCM based HC for mesh router placement optimization considering two islands model of mesh clients distributions.

Performance Improvement on Reception Confirmation Messages in Bluetooth Mesh Networks

Abstract: Bluetooth mesh is a recent technology built on the Bluetooth Low Energy protocol stack architecture, focusing on the Internet of Things. It represents an excellent solution for commercial and industrial lighting applications, though it is still evolving. One of the biggest challenges of the Bluetooth mesh network is the improvement of confirmation messages reception. In a Bluetooth mesh network, determining the Status of the received messages is a critical aspect that can generate unexpected issues when multiple devices respond simultaneously, as it may occur in some lighting applications. This behavior can reduce the probability of message delivery due to collisions, especially when the number of devices in the network increases. This paper aims to improve the reliability in receiving confirmation messages in a Bluetooth mesh network by proposing a new technique of spreading Status overtime. To evaluate the proposed technique's performance, we compare our technique with a Bluetooth mesh network with standard configuration using real nodes experimental setup. We evaluated our results in terms of packet-loss rate, obtaining 98.84% of the Status received for the network with our optimized configuration and 96.98% for those with the standard configuration. Finally, an in-depth performance evaluation method for the analysis of the lost Status was also conducted.

A CCM-Based HC System for Mesh Router Placement Optimization: A Comparison Study for Different Instances Considering Normal and Uniform Distributions of Mesh Clients

Abstract: The Wireless Mesh Networks (WMNs) enables routers to communicate with each other wirelessly in order to create a stable network over a wide area at a low cost and it has attracted much attention in recent years. There are different methods for optimizing the placement of mesh routers. In our previous work, we proposed a Coverage Construction Method (CCM) and CCM-based Hill Climbing (HC) system for mesh router placement problem considering normal and uniform distributions of mesh clients. In this paper, we propose a CCM-based HC reduction method and evaluate performance of CCM-based HC system for different instances considering normal and uniform distributions. For the simulation results, we found that the CCM-based HC system was able to cover more mesh clients for different instances compared with CCM and processing time has been reduced compared to the previous system.

Evaluation of Theoretical Interference Estimation Metrics for Dense Wi-Fi Networks

Abstract: To meet the rising data offloading demands, IEEE 802.11-based WiFi networks have undergone gradual and consistent densification through Overlapping Basic Service Set (OBSS) deployments. With the upcoming 802.11ax standard, dense and ultra-dense deployments (DNs/UDNs) will become the norm, and the detrimental impact of endemic interference on network capacity will further exacerbate. In traditional Wireless Mesh Networks (WMNs), Theoretical Interference Estimation Metrics (TIEMs) are widely used as an indirect measure of interference. TIEMs are instrumental to channel allocation (CA) and performance prediction, routing, and scheduling algorithms. However, the exact nature of the relationship between TIEMs and performance parameters such as network capacity has not been investigated. TIEMs will likely serve similar roles in sixth-generation 802.11ax WiFi networks, and a TIEM-Capacity analysis will improve their application. In this work, we study the TIEM-capacity relationship through nonparametric regression. This study investigates the impact of WMN topology on their relationship by considering four carefully designed Wireless Mesh Network (WMN) topologies in the experiments. We consider four popular Theoretical TIEMs and a broad set of 100 channel assignment (CA) schemes. The investigations are carried out on IEEE 802.1lg/n WMNs simulated in ns-3. We then analyze the TIEM-capacity feature relationship parameters to classify the TIEMs in terms of their reliability and the ability to model interference. Finally, we validate the outcome of our study on a dense 802.11ac experimental testbed. The TIEM identified as the most suitable for dense scenarios by the proposed analytical framework demonstrates over 95% accuracy and a correlation of 0.98 with dense network capacity.

WiMesh: leveraging mesh networking for disaster communication in resource-constrained settings

Abstract: This paper discusses the design, implementation and field trials of WiMesh, a resilient wireless mesh network-based disaster communication system purpose-built for underdeveloped and rural parts of the world. Mesh networking is a mature area, and the focus of this paper is not on proposing novel models, protocols or other mesh solutions. Instead, the paper focuses on the identification of important design considerations and justifications for several design trade offs in the context of mesh networking for disaster communication in developing countries with very limited resources. These trade-offs are discussed in the context of key desirable traits including security, low cost, low power, size, availability, customization, portability, ease of installation and deployment, and coverage area among others. We discuss at length the design, implementation, and field trial results of the WiMesh system which enables users spread over large geographical regions, to communicate with each other despite the lack of cellular coverage, power, and other communication infrastructure by leveraging multi-hop mesh networking and Wi-Fi equipped handheld devices. Lessons learned along with real-world results are shared for WiMesh deployment in a remote rural mountainous village of Pakistan, and the source code is shared with the research community.

A Simulation System for Mesh Router Placement in WMNs Considering Coverage Construction Method and Simulated Annealing.

Abstract: The Wireless Mesh Networks (WMNs) enables routers to communicate with each other wirelessly in order to create a stable network over a wide area at a low cost and it has attracted much attention in recent years. There are different methods for optimizing the placement of mesh routers. In our previous work, we proposed a Coverage Construction Method (CCM) and CCM-based Hill Climbing (HC) system for mesh router placement problem considering normal and uniform distributions of mesh clients. In this paper, we propose a CCM-based Simulated Annealing (SA) approach for mesh router placement problem. From the simulation results, we found that the proposed method covers more mesh clients for all instances compared with the CCM.

Soft-Mesh: A Robust Routing Architecture for Hybrid SDN and Wireless Mesh Networks

Abstract: Wireless Mesh Networks (WMNs) are considered self-organizing, self-healing, and self-configuring networks. Despite these exciting features, WMNs face several routing challenges including scalability, reliability and link failures, mobility, flexibility, and other network management issues. To address these challenges, WMNs need to make programmable to allow modifications of standard techniques to be configured and implemented through software programs that can be resolved by integrating Software Defined Networking (SDN) architecture. SDN, being a cutting-edge technology promises the facilitation of network management as well as routing issues of wireless mesh networks. However, the evolution of the legacy IP-based network model in its entirety leads to technical, operational, and economic problems that can be mitigated by full interoperability between SDN and existing IP devices. This study introduces a Robust Routing Architecture for Hybrid Software-Defined and Wireless Mesh Networks (Soft-Mesh), by systematic and gradual transitioning of WMNs to SDNs in an efficient manner. The main objective of this paper is to suggest improvements to the architecture of the SDN node that allow the implementation of various network functions such as routing, load balancing, network control, and traffic engineering for the hybrid SDN and IP networks. Mininet-WiFi Simulator is used to perform various experiments to evaluate the performance of proposed architecture by creating a hybrid network topology with a varying number of nodes that is 50, 100, 150, 200, and 250 including SDN hybrid and legacy nodes with varying proportion of SDN hybrid and legacy nodes. Results are taken for the average UDP throughput, end-to-end delay, packet drop ratio, and routing overhead while comparing with traditional routing protocols including Optimized Link State Routing (OLSR) and Better Approach to Mobile Adhoc Networking (BATMAN) and with existing hybrid SDN/IP routing architectures including Hakiri and wmSDN. The analysis of simulation results shows that the proposed architecture Soft-Mesh outperforms in terms of the aforementioned performance metrics than the traditional and exiting hybrid routing protocols. Soft-Mesh gives 50% to 70% improved results concerning the incremental proportion of SDN hybrid nodes.

DDoS attacks impact on data transfer in IOT-MANET-based e-healthcare for tackling COVID-19

Abstract: The Covid-19, a pandemic situation, effects the economy of the whole world severely and is gaining much huge attention in the field of research currently across the globe. The Internet of things (IoT) technology is playing a great role for taking care of the patients by monitoring and controlling the symptoms and is very much essential for the developing countries, where monitoring of health of huge population has its own challenges. So the IoT and its amalgamation with mobile ad hoc network (MANET) acts as base of networks where devices send information among each other wirelessly thus also named as wireless mesh networks (WMN), in which various nodes are either stationary or allied with static position. Sensors and different other devices involved in e-healthcare sector used in WMN converse wirelessly and hence become the main gate to a numerous susceptibilities. The main aim of this research study is to evaluate the performance of reactive, secured and hybrid routing protocols for throughput as one of the important quality of service (QoS) parameters in absence as well as in presence of distributed denial of service (DDoS). The NS-2(network simulator) is used to simulate AODV (ad hoc on-demand vector, SAODV (secured AODV) and hybrid wireless mesh protocol) in scenario of changing nodes. The comparative analysis concludes the HWMP as most suitable protocol among the other two routing protocols with impact on throughput for handling DDoS attacks. This research study aids in providing implications to enhance existing protocols and alleviate the consequence of DDoS instigated by such attacks.

The development of green wireless mesh network: A survey

Abstract: © The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, sharing, adaptation, distribution and reproduction in any medium or format, for any purpose, even commercially, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Achieving Hidden-Terminal-Free Channel Assignment in IEEE802.11-Based Multi-Radio Multi-Channel Wireless Mesh Networks

Abstract: Wireless Mesh Networks (WMNs) are often designed on IEEE 802.11 standards and are being widely studied due to their adaptability in practical network scenarios, where the overall performance has been improved by the use of the Multi-Radio and Multi-Channel (MRMC) configuration. However, because of the limitation on the number of available orthogonal channels and radios on each router, the network still suffers from low throughput due to packet collisions. Many studies have demonstrated that the optimized channel assignment to radio interfaces so as to avoid interference among wireless links is an effective solution. However, no existing channel assignment scheme can achieve hidden-terminal-free transmission and thus avoid communication performance degradation given the limited number of orthogonal channels. In this paper, we propose a new static channel assignment scheme CASCA (CSMA-aware Static Channel Assignment) based on a Partial MAX-SAT formulation of the channel assignment problem that incorporates a CSMA-aware interference model. The evaluation results show that CASCA achieves hidden-terminal-freedom in both grid and random topology networks with 3-4 orthogonal channels with preservation of network connectivity. In addition, the network simulation results show that CASCA presents good communication performance with low MAC-layer collision rate. key words: WMNs, multi-radio multi-channel, channel assignment, hiddenterminal-freedom

Text messages by wireless mesh network vs voice by two-way radio in disaster simulations: A crossover randomized-controlled trial.

Abstract: Background Communication failures secondary to damaged infrastructure have caused difficulties in coordinating disaster responses. Two-way radios commonly serve as backup communication for hospitals. However, text messaging has become widely adopted in daily life and new technologies such as wireless mesh network (WMN) devices allow for text messaging independent of cellular towers, Wi-Fi networks, and electrical grids. Objective To examine the accuracy of communication using text-based messaging transmitted over WMN devices (TEXT-WMN) compared to voice transmitted over two-way radios (VOICE-TWR) in disaster simulations. Secondary outcomes were patient triage accuracy, perceived workload, and device preference. Methods 2 × 2 Latin square crossover design: 2 simulations (each involving 15 min of simulated hospital-wide disaster communication) by 2 modalities (TEXT-WMN and VOICE-TWR). Physicians were randomized to one of two sequences: VOICE-TWR first and TEXT-WMN second; or TEXT-WMN first and VOICE-TWR second. Analyses were conducted using linear mixed effects modeling. Results On average, communication accuracy significantly improved with TEXT-WMN compared to VOICE-TWR. Communication accuracy also significantly improved, on average, during the second simulation compared to the first. There was no significant change in triage accuracy with either TEXT-WMN or VOICE-TWR; however, triage accuracy significantly improved, on average, during the second simulation compared to the first. On average, perceived workload was significantly lower with TEXT-WMN compared to VOICE-TWR, and was also significantly lower during the second simulation compared to the first. Most participants preferred TEXT-WMN to VOICE-TWR. Conclusion TEXT-WMN technology may be more effective and less burdensome than VOICE-TWR in facilitating accurate communication during disasters.

Adaptive Multi-Channel Clustering in IEEE 802.11s Wireless Mesh Networks.

Abstract: WLAN mesh networks are one of the key technologies for upcoming smart city applications and are characterized by a flexible and low-cost deployment. The standard amendment IEEE 802.11s introduces low-level mesh interoperability at the WLAN MAC layer. However, scalability limitations imposed by management traffic overhead, routing delays, medium contention, and interference are common issues in wireless mesh networks and also apply to IEEE 802.11s networks. Possible solutions proposed in the literature recommend a divide-and-conquer scheme that partitions the network into clusters and forms smaller collision and broadcast domains by assigning orthogonal channels. We present CHaChA (Clustering Heuristic and Channel Assignment), a distributed cross-layer approach for cluster formation and channel assignment that directly integrates the default IEEE 802.11s mesh protocol information and operating modes, retaining unrestricted compliance to the WLAN standard. Our concept proposes further mechanisms for dynamic cluster adaptation, including subsequent cluster joining, isolation and fault detection, and node roaming for cluster balancing. The practical performance of CHaChA is demonstrated in a real-world 802.11s testbed. We first investigate clustering reproducibility, duration, and communication overhead in static network scenarios of different sizes. We then validate our concepts for dynamic cluster adaptation, considering topology changes that are likely to occur during long-term network operation and maintenance.