Performance Evaluation of Multirate Loss Systems Supporting Cooperative Users with a Probabilistic Behavior

Ioannis MOSCHOLIOS  Michael LOGOTHETIS  Shigeo SHIODA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E100-B   No.10   pp.1778-1788
Publication Date: 2017/10/01
Online ISSN: 1745-1345
Type of Manuscript: PAPER
Category: Fundamental Theories for Communications
Keyword: 
poisson,  quasi-random,  cooperative,  retry,  recursive,  

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Summary: 
We consider a multirate loss system that accommodates several service-classes with cooperative and non-cooperative users, which generate random or quasi-random arriving calls (depending on the users population). The term “ cooperative” refers to users that can retry (with a certain probability, when the total occupied bandwidth of the system is below a predefined threshold) to be connected in the system with a reduced bandwidth, if they are blocked with their initial peak-bandwidth requirement. This behavior increases the quality of service (QoS) perceived by other users. Due to the retries, the system model does not have a product form solution for the steady state distribution. However, we propose an efficient calculation of system's occupancy distribution, congestion probabilities and system's utilization, while avoiding complex state space enumeration and processing. As it is shown through simulation, the proposed recursive formulas are consistent and quite accurate. For evaluation, we use the conventional trunk/bandwidth reservation control to equalize the congestion probabilities and compare them with the results of the proposed models. Besides, we generalize the proposed models by considering the coexistence of random and quasi-random arrivals. Furthermore, we propose (a) a heuristic method for the determination of desired retry probabilities according to a fairness index and (b) an optimization procedure whereby we assess the retry threshold so that the QoS of the least speed non-cooperative calls is guaranteed for certain retry probabilities of cooperative calls.