Method for Detecting Transmission Link Failure in Industrial Wireless Networks

Industrial Wireless Networks have been increasingly employed in industry. In manyindustrial environments device failures can occur. The detection of failures is essential for theproper network operation. This work aims to accomplish link failure detection in an IndustrialWireless Network. A link failure can occur if the radio Power Amplifier presents problems. Ifthe power amplifier does not work properly, asymmetry may occur in communications sincethe Power Amplifier is responsible only for the transmission. It is proposed an algorithm whichperiodically analyses the Receive Signal Level of transmissions and infer whether happening aPower Amplifier fault in some device. The proposed method contributes to the correct diagnosisof network problems since link asymmetry can induce the Network Manager and also the userto understand that healthy devices are not working correctly.

Minimizing the Adverse Effects of Asymmetric Links: A Novel Cooperative Asynchronous MAC Protocol for Wireless Sensor Networks

As Wireless Sensor Networks (WSNs) grow in popularity, researchers are now focusing more on some challenging issues that significantly degrade overall performance, such as energy hole mitigation, link asymmetry minimization, etc. Link asymmetry is a problem that arises when the coverage distance between two adjacent nodes varies. It creates an obstacle to overcome when designing an efficient Medium Access Control (MAC) protocol for WSNs with low duty-cycling. This phenomenon poses an especially difficult challenge for receiver-initiated asynchronous MAC protocols, which are popular due to their relatively higher energy efficiency. Exploiting the benefits of cooperative communication has emerged as one of the viable solutions to overcome this limitation. Cooperative communication in WSNs has received a lot of attention in recent years. Many researchers have worked to create a MAC layer supporting cooperative communication. However, the association of cooperative communication with an asymmetric link is not studied in the literature. In this research work, COASYM-MAC, a cooperative asynchronous MAC protocol for WSNs, is proposed based on a receiver-initiated MAC protocol that uses the fact that nodes have alternate paths between them to reduce link asymmetry. A key feature of the proposed protocol is that the optimal helper node is selected automatically in case of link asymmetry. Simulations exhibited that COASYM-MAC performs significantly better than a state-of-the-art MAC protocol for WSNs that handles asymmetric links, ASYM-MAC.

An Extended Cross Layer Approach Handling Asymmetry with Quality of Service, Congestion Avoidance and Congestion Aware Routing

Nodes in wireless multi-hop networks establish links with their neighbors that are used for data transmission. In Wireless Mesh Networks (WMNs) working in an ad hoc model, a transmission region of mesh routers and mesh clients is heterogeneous which cause link asymmetry. The cross-layer framework was developed to handle link asymmetry problems such as unidirectional link issue, heterogeneous exposed problem and heterogeneous hidden problem. Additionally, congestion control and quality of service (QoS) requirements are required to enhance the performance of network. Hence, in this paper, the Cross Layer approach Handling Link Asymmetry (CHLA) is extended as quality-of-service aware routing (CHLA-QSAR) and quality-of-service with congestion control aware routing (CHLA-QSCCAR). QoS requirements are achieved by Signal strength estimation, network capacity estimation, MAC scheduling, Link Scheduling and Slot assignment. Congestion is controlled by a proposed bandwidth management mechanism by congestion window management dependent on the dynamic incidents of traffic conditions. Moreover, congestion avoidance mechanism is also proposed with Quality of Service with Congestion aware routing (QSCACAR). The simulation is conducted for CHLA, CHLA-QSAR, and CHLA-QSCCAR and CHLA-QSCACAR methods in terms of bit error rate, end to end delay, latency, routing overheads and throughput. The simulation results proved that each proposed work is consecutively improving the performance than CHLA.