The choice of parameters for access control in communication networks with mobile objects
Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
Modern aviation communication system based on the modular principle with the use of open architecture. For this class of networks characteristic is the constant change in the number and composition of concurrent mobile objects, a significant limitation on the time of network access and the use of relatively low-speed data channels. A certain compromise of conflicting requirements to the network is the use of the protocols of random multiple access, in particular, Protocol synchronous Aloha.
In the present work we study the behavior of the network under heavy load. Interest in this problem stems from the fact that due to the limited frequency resource growth in the number of mobile objects leads to a corresponding increase in network traffic. Thus the probability of the transition network in an unstable condition characterized by a significant deterioration in the efficiency of its functioning. With the aim of improving the operational characteristics of the network it is necessary to clearly identify the current state of the network and to predict its transition to an unstable state.
In this paper an attempt is made choice of such control parameters whose values allow to detect the access network from the steady state.
For a detailed analysis of the characteristics of the network developed a simulation model that allows to investigate the behavior of the network under rather General assumptions.
The simulation results show that the transition in unstable condition leads to a qualitative change in the distribution of the transmission time of a packet. A small number of nodes and traffic characteristic of the steady state, the density distribution has the form of a normal distribution. A large number of nodes or high traffic, typical of the transition network in an unstable condition, leads to expansion of the density distribution, the graph of the function becomes flatter. Thus, the type of density distribution allows us to estimate the number of nodes and network traffic, as well as the degree of closeness of the network to transition to an unstable state.
Qualitative changes in the distribution of the transmission time impact on the behavior of the moments of the distribution. It is shown that the coefficient of variation of time the packet has a critical value of the order of unity. The critical value indicates the transition network in an unstable state.
The obtained results allow to choose the parameters of the network management for the timely prevention of the transition it into an unstable state.
Keywords:telecommunication technology aircraft systems, aviation systems and data communications, intelligent network management, random multiple access
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