Prioritization-based adaptive emergency traffic medium access control protocol for wireless body area networks

Wireless Body Area Networks (WBANs) provide continuous monitoring of a patient by using heterogeneous Bio-Medical Sensor Nodes (BMSNs). WBANs pose unique constraints due to contention-based prioritized channel access, sporadic emergency traffic handling and emergency-based traffic adaptivity. In the existing medium access control protocols, the available contention-based prioritized channel access is incomplete due to the repetitions in backoff period ranges. The emergency traffic is considered based on traffic generation rate as well as sporadic emergency traffic that is not handled at multiple BMSNs during contention. In an emergency situation, non-emergency traffic is ignored, traffic is not adjusted dynamically with balanced throughput and energy consumption, and the energy of non-emergency traffic BMSNs is not preserved. In this research, prioritization-based adaptive emergency traffic Medium Access Control (MAC) protocol was designed to consider contention-based prioritized channel access for heterogenous BMSNs along with sporadic emergency traffic handling and dynamic adjustment of traffic in sporadic emergency situation. Firstly, a Traffic Class Prioritization based slotted-CSMA/CA (TCP-CSMA/CA) scheme was developed to provide contention-based prioritized channel access by removing repetitions in backoff period ranges. Secondly, an emergency Traffic Class Provisioning based slotted-CSMA/CA (ETCP-CSMA/CA) scheme was presented to deliver the sporadic emergency traffic instantaneously that occurs either at a single BMSN or multiple BMSNs, with minimum delay and packet loss without ignoring non-emergency traffic. Finally, an emergency-based Traffic Adaptive slotted-CSMA/CA (ETA-CSMA/CA) scheme provided dynamic adjustment of traffic to accommodate the variations in heterogeneous traffic rates along with energy preservation of non-emergency traffic BMSNs, creating a balance between throughput and energy in the sporadic emergency situation. Performance comparison was conducted by simulation using NS-2 and the results revealed that the proposed schemes were better than ATLAS, PLA-MAC, eMC-MAC and PG-MAC protocols. The least improved performances were in terms of packet delivery delay 10%, throughput 14%, packet delivery ratio 21%, packet loss ratio 28% and energy consumption 37%. In conclusion, the prioritization-based adaptive emergency traffic MAC protocol outperformed the existing protocols

Link failure detection, network recovery, and network reliability in multi-hop wireless networks

In this thesis, we study Wireless Mesh Network (WMN) and Mobile Ad hoc NETwork (MANET), which are two kinds of wireless multi-hop communication networks. WMNs and MANETs are promising technologies that have the ability to provide effective solutions to many applications in the technological, social, military, disaster recovery, and economic fields. Some of these applications are the extension of the cellular network's coverage, broadband internet access, and community and neighborhood networks. The big challenge in these kinds of networks is the frequent link failures, which make them less reliable compared to other kinds of networks. Implementing a fast mechanism to detect link failures, effective and reliable routing protocols and metrics, and a powerful reconfiguration scheme to recover from the link failures greatly enhance the WMNs and MANETs performance, and increase their reliability and availability. Our research has three directions. In the first direction, we study link failure detection approaches and link failure recovery techniques. In this direction, we mathematically analyze Hello based link failure detection approach implemented in routing protocols that use two routes, one as a primary route, and the other one as a backup route that is immediately used upon link failures. The objectives behind the above analysis are to mathematically calculate the packet delivery ratio, and to find how much gain we could achieve by using two routes instead of one. Our results show that the packet delivery is increased by 1.5 times by using two routes instead of one. It also shows that applying two routes is essential to cover high link failure rate values, and the need using two routes instead of one is more urgent in WMNs and MANETs with higher link failure rate values, i.e. less reliable networks. In addition to that, we propose a novel framework that dynamically assigns the values of Hello based link failure detection scheme parameters based on the communication types and the QoS requirements. Besides that, we propose a novel protocol to enhance the Hello based link failure detection scheme performance. In the second direction, we study the reliable routing protocols and metrics. This thesis proposes a novel adaptive routing protocol to increase the network connectivity and reliability, while minimizing the hop count, reducing the network nodes' spatial distribution and memory, and simplifying the routing process. The network reliability and connectivity are investigated in the last direction. Based in our study, the only ways to provide reliable and stable communications, virtually decrease the packet loss to zero, and to support multimedia communications in MANETs and WMNs are by using multi-route instead of one, and letting the routing protocols select the most stable routes among the available routes. The network node density specifies the probability that a route exists between any randomly chosen source and destination pair. Thus, to ensure the existence of two routes between any source and destination pairs, the node density must be above a certain threshold. In this thesis, we propose a mathematical model to find the above threshold. Our results show that the probability to have two routes exponentially increases with the number of nodes until it reaches the saturation region where the increase of the number of nodes has negligible improvements in terms of network availability. In addition to that, we study the effects of nodes mobility on the network connectivity. Our work is evaluated by MATLAB