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Wireless Mesh Networks 2010 Part 11

Tham khảo tài liệu 'wireless mesh networks 2010 part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Pursuing Credibility in Performance Evaluation of VoIP Over Wireless Mesh Networks 189 Even though credibility of stochastic simulation has been questioned when applied to practical problems mainly due to the application of not robust methodology for simulation projects which should comprise at least the following - The correct definition of the problem. - An accurate design of the conceptual model. - The formulation of inputs assumptions and processes definition. - Build of a valid and verified model. - Design of experiments. - Proper analysis of the simulation output data. 3. Model credibility 3.1 Problem definition To formulate a problem is so important as to solve it. There is a claim credited to Einstein that states The formulation of a problem is often more essential than its solution which may be merely a matter of mathematical or experimental skill . The comprehension of how the system works and what are the main specific questions the experimenter wants to investigate will drive the decisions of which performance measures are of real interest. Experts are of the opinion that the experimenter should write a list of the specific questions the model will address otherwise it will be difficult to determine the appropriate level of details the simulation model will have. As simulation s detail increases development time and simulation execution time also increase. Omitting details on the other hand can lead to erroneous results. Balci Nance 1985 formally stated that the verification of the problem definition is an explicit requirement of model credibility and proposed high-level procedure for problem formulation and a questionnaire with 38 indicators for evaluating a formulated problem. 3.2 Sources of randomness The state of a WMN can be described by a stochastic or random process that is nothing but a collection of random variables observed along a time window. So input variables of a WMN simulation model such as the transmission range of each WMC the size of