WoPANets embodies the methodology, illustrated in the following Fig.
The main steps of this implemented methodology are :
- System Specifications
This first step consists in collecting the maximum of available information concerning the application profiles and the network architecture.
- The application profiles can be defined based on events traces or more commonly on traffic contracts, which define the main characteristics of the exchanged traffic flows, e.g., packet lengths, period or inter-arrival time, deadline, traffic class, jitter, burst size, source, set of destinations, path(s) (...).
- The network architecture is described (if known), e.g., switched networks, wired/wireless links or gateways (if any), and more information on the node behavior and technological characteristics, e.g. service policy, transmission capacity or memory constraints, can be integrated ;
- System Modeling
This second step is of utmost importance since it conditions the tightness of the guaranteed quality-of-service metrics. The main idea of this step is :
- First, to model the specified application profiles, and more precisely the maximum exchanged traffic data between applications, based on the concept of maximum arrival curve in Network Calculus framework.
- Then, the system behavior is modeled and particularly the minimum availability of the system guaranteed to the input traffic, i.e., the minimum service curve in NC framework.
- Performance Analysis After building the traffic and system models, the performance analysis of the communication system can be conducted to compute various quality-of-service metrics, such as maximum bounds on end-to-end delay, buffer utilization within crossed nodes, network utilization at the bottleneck or the jitter.
- Performance Optimization
Once the performance analysis of the first specified solution is conducted, there are two offered possibilities for the designer, depending on the performance analysis results :
- If the specified solution does not fulfill the system constraints, one may look for an admissible solution guaranteeing these requirements, by defining some variable system’s parameters to allow the exploration of alternative solutions ;
- If the specified solution is feasible, one may look for a better solution to enhance the guaranteed system performance, e.g., minimizing the delay or maximizing the network utilization.
- Specification Refinement this last step consists in defining the most accurate specification of the communication network under design, which improves the system’s performance while guaranteeing its constraints. This choice depends on the performance optimization step results, and the designer experience to select the most adequate solution among the proposed ones.