Stability of queueing-inventory systems with different priorities

We study a production-inventory system with two customer classes with different priorities which are admitted to the system following a flexible admission control scheme. The inventory management is according to a base stock policy and arriving demand which finds the inventory depleted is lost (lost sales). We analyse the global balance equations of the associated Markov process and derive structural properties of the steady state distribution which provide insights into the equilibrium behaviour of the system. We derive a sufficient condition for ergodicity using the Foster-Lyapunov stability criterion. For a special case we show that the condition is necessary as well

Performance analysis of queueing system model under priority scheduling algorithms within 5G networks slicing framework

A new era is opening for the world of information and communication technologies with the 5G networks’ release. Indeed 5G networks appear in modern wireless systems as solutions to “traditional” networks’ inflexibility and lack of radio resources problems. Using these networks the operators can expand their services’ range at will and, therefore, manage daily operations by monitoring ‘key performance indicators’ (KPIs) - helping meet the quality of service (QoS) requirements much easily. To meet the QoS requirements 5G networks can be implemented alongside priority scheduling algorithms. This paper considers the operation of a wireless network slicing model under two scheduling algorithms. A comparative analysis of main performance measures is provided.Переход к беспроводным сетям пятого поколения 5G ознаменовал новый этап развития информационных и коммуникационных технологий. Сети пятого поколения должны решить такие проблемы, как негибкость «традиционных» сетей и нехватка частотных радиоресурсов для качественного предоставления услуг. Предполагается, что, используя эти сети, мобильные операторы смогут значительно расширить спектр услуг и обеспечить требуемое качество их предоставления. Для удовлетворения требований к качеству обслуживания ( англ. Quality of Service - QoS) операторам необходимо выполнение «ключевых показателей эффективности» ( англ. Key Performance Indicators - KPI), описанных в стандартах связи. Для этой цели могут быть использованы алгоритмы приоритетного облуживания. В статье рассмотрена модель беспроводной сети 5G, поддерживающая технологию нарезки сети и реализующая управление доступом к сетевым радиоресурсам при помощи введения приоритетов. Изучена работа модели в рамках двух алгоритмов. Проведён сравнительный анализ основных показателей эффективности модели

Functional limit theorems, branching processes and stochastic networks

This manuscript describes some of the work I have been doing since 2010 and the end of my PhD. As the title suggests, it contains three main parts. 1. Functional limit theorems: Chapter 2 presents two theoretical results on the weak convergence of stochastic processes: one is a sufficient condition for the tightness of a sequence of stochastic processes and the other provides a sufficient condition for the weak convergence of a sequence of regenerative processes; 2. Branching processes: in Chapter 3, scaling limits of three particular types of branching processes are discussed: 1) Galton-Watson processes in varying environments, 2) binary and homogeneous Crump-Mode-Jagers processes and 3) Crump-Mode-Jagers processes with short edges;3. Stochastic networks: Chapter 4 presents three results on stochastic networks: 1) scaling limits of the M/G/1 Processor-Sharing queue length process, 2) study of a model of stochastic network with mobile customers and 3) heavy traffic delay performance of queue-based scheduling algorithms

Fuelling the zero-emissions road freight of the future: routing of mobile fuellers

The future of zero-emissions road freight is closely tied to the sufficient availability of new and clean fuel options such as electricity and Hydrogen. In goods distribution using Electric Commercial Vehicles (ECVs) and Hydrogen Fuel Cell Vehicles (HFCVs) a major challenge in the transition period would pertain to their limited autonomy and scarce and unevenly distributed refuelling stations. One viable solution to facilitate and speed up the adoption of ECVs/HFCVs by logistics, however, is to get the fuel to the point where it is needed (instead of diverting the route of delivery vehicles to refuelling stations) using "Mobile Fuellers (MFs)". These are mobile battery swapping/recharging vans or mobile Hydrogen fuellers that can travel to a running ECV/HFCV to provide the fuel they require to complete their delivery routes at a rendezvous time and space. In this presentation, new vehicle routing models will be presented for a third party company that provides MF services. In the proposed problem variant, the MF provider company receives routing plans of multiple customer companies and has to design routes for a fleet of capacitated MFs that have to synchronise their routes with the running vehicles to deliver the required amount of fuel on-the-fly. This presentation will discuss and compare several mathematical models based on different business models and collaborative logistics scenarios