BITS Faculty Publications

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Subject: search.filters.subject.Cellular networks

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    Economic and reliability analysis of discrete-time G-queue with multi-optional services and Bernoulli feedback
    (Springer, 2025-07) Kulshrestha, Rakhee
    Cellular networks play a crucial role in modern telecommunications, supporting growing numbers of mobile users and various call types ranging from voice calls to multimedia data sessions. Efficient call handling is essential to ensure reliable and timely connections, optimal resource utilization, and a satisfactory Quality of Service (QoS). This study analyzes various call types in cellular networks using a discrete-time queueing model. Specifically, we investigate a discrete-time Geo/Geo/1 G-queue characterized by an unreliable server, k-optional services, and Bernoulli feedback mechanisms. Furthermore, within the framework of this queuing model, various call types are treated as positive customers, while virus attacks are considered negative customers. The arrival of a negative customer interrupts an ongoing service, leading to a server failure. Additionally, we assume that all arriving customers (positive) must undergo the First Essential Service (FES). After completing the FES, the server offers further services, allowing customers to either select one of the k-optional services, rejoin the queue for another FES, or leave the system if they do not wish to utilize additional services. Then, the entire system is modeled as a two-dimensional discrete-time Markov chain, and the matrix-geometric method is utilized to compute the steady-state probability vector, which is then employed to evaluate the numerical results of various performance metrics that depend on the queueing and reliability analysis. Finally, a cost model is established, and the Quasi-Newton method and Particle swarm optimization (PSO) technique are employed to achieve optimal operating conditions with minimal expected cost.
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    Analysis of Multiple Queue Model in Cellular Networks with Sub Rating of Channels
    (King Abdulaziz University Journal, 2012) Kulshrestha, Rakhee
    In cellular Networks we generally consider a single queue for each cell, some authors proposed a model with a dedicated queue for each transceiver in the cell. We have extended the idea of dedicated queue for each transceiver in the cell with sub-rating channels to improve the Quality of Service (QOS) of the system. In this paper we have compared three models, in model-I we used guard channels to give priority to handoff attempts and a buffer for finite size is provided to give priority to handoff data attempts, further in model-II we have taken sub-rating channel scheme (SCS). In subrating scheme a full rate channel is temporarily divided into two half rate channels in the blocked cell; one half rate channel serve the originating call and another serves handoff call. We proposed a dedicated queue for each transceiver in the cell with sub-rating in model-III. The Fixed Channel Assignment Scheme is considered for all models. The probabilities of handoff failure, blocking probability of new calls, forced termination of handoff calls, probability of noncompleted calls for all models are calculated for varying assumed of values arrival rate of new data calls, arrival rate of new voice calls, buffer size of channels and service rates. We compared and analyzed the numerical results to validate the proposed models.
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    Performance Analysis of Fractional Guard Channel Scheme with Buffer for Cellular Mobile Networks
    (Springer, 2019-07) Kulshrestha, Rakhee
    In this paper, we have developed an efficient channel assignment scheme using fractional guard channel for utilizing the limited radio recourses efficiently and seamlessly by providing buffer for good-quality signal calls to improve the quality of service. Two models are proposed to prioritize good-quality handoff calls over poor-quality calls. The expressions for blocking probability, call dropped probability of handoff calls, utilization of channels and buffer are obtained for a cellular radio network. Numerical simulation results for both the models illustrate the impact of different parameters on the key performance measures.
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    A Game Theoretic Analysis for Power Management and Cost Optimization of Green Base Stations in 5G and Beyond Communication Networks
    (IEEE, 2022-09) Chamola, Vinay; Joshi, Sandeep
    Due to the exponential increase in the number of users, the next-generation cellular networks are resource-constrained in power and bandwidth. Power consumption is one of the critical consideration for the next-generation wireless networks, therefore, management of available resources is essential to achieve power efficiency. With the growing incentive to ‘go green’ and to reduce the carbon footprint, the fifth generation (5G) and beyond wireless networks will derive power from renewable sources to solve the energy efficiency problems. This work focuses on integrated regulation of the traditional, i.e., the grid-based and the renewable, i.e., the solar-based power supplies for the 5G and beyond 5G green base stations (BSs) in a smart city scenario. We propose a pricing model for suppliers to charge the BSs for electricity consumption when the renewable power supply cannot meet their total energy requirements. We propose a game-theoretic analysis for cost optimization by proposing two games, i.e., the power control game and the best supplier game. Each BS acts as a game player and has some actions like power reduction and supplier selection to reduce the total energy costs. We also provide the game transition profiles for the BSs. Furthermore, the Nash Equilibrium’s existence is verified for each of these games and an optimal cost solution is proposed for the green BSs.
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    Power Outage Estimation and Resource Dimensioning for Solar Powered Cellular Base Stations
    (IEEE, 2016-12) Chamola, Vinay
    One of the major issues in the deployment of solar powered base stations (BSs) is to dimension the photovoltaic (PV) panel and battery size resources, while satisfying outage constraints with least cost. The fundamental step in this dimensioning is to evaluate the power outage probability associated with a particular configuration of PV panel and battery size. This paper addresses this issue by first proposing an analytic model to evaluate the power outage probability of a solar powered BS. The proposed model accounts for hourly as well as daily variation in the harvested solar energy as well as the load dependent BS power consumption. The model evaluates the steady state probability of the battery level, which is then used to estimate the BS power outage probability. Next, given a tolerable power outage probability, we address the problem of obtaining the cost-optimal PV panel and battery dimensions for the BS. The proposed model and the framework have been evaluated using empirical solar energy data for geographically diverse locations.
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    Green Energy and Delay Aware Downlink Power Control and User Association for Off-Grid Solar-Powered Base Stations
    (IEEE, 2018-09) Chamola, Vinay
    Cellular base stations (BSs) powered by renewable energy like solar power have emerged as a promising solution to address the issues of reducing the carbon footprint of the telecom industry as well as the operational cost associated with powering the BSs. This paper considers a network of off-grid solar-powered BSs and addresses two key challenges while operating them: first is avoiding energy outages and second is ensuring reliable quality of service (in terms of the network latency). In order to do so, the problem of minimizing the network latency given the constrained energy availability at the BSs is formulated. Unlike existing literature which have addressed this problem using user-association reconfiguration or BS on/off strategies, we address the problem by proposing an intelligent algorithm for allocating the harvested green energy over time, and green energy and delay aware downlink power control and user association. Using a real BS deployment scenario, we show the efficacy of our methodology and demonstrate its superior performance compared to existing benchmarks.
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    Delay Aware Resource Management for Grid Energy Savings in Green Cellular Base Stations With Hybrid Power Supplies
    (IEEE, 2017-03) Chamola, Vinay
    Base stations equipped with resources to harvest renewable energy are not only environment-friendly but can also reduce the grid energy consumed, thus bringing cost savings for the cellular network operators. Intelligent management of the harvested energy can further increase the cost savings. Such management of energy savings has to be carefully coupled with managing the quality of service so as to ensure customer satisfaction. In such a process, there is a trade-off between the energy drawn from grid and the quality of service. Unlike prior studies which mainly focus on network energy minimization, this paper proposes a framework for jointly managing the grid energy savings and the quality of service (in terms of the network latency), which is achieved by downlink power control and user association reconfiguration. We use a real BS deployment scenario from London, U.K., to show the performance of our proposed framework and compare it against existing benchmarks. We show that the proposed framework can lead to around 60% grid energy savings as well as better network latency performance than the traditionally used scheme
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    Downlink power control for latency aware grid energy savings in green cellular networks
    (IEEE, 2016) Narang, Pratik; Chamola, Vinay
    Mobile service providers can achieve cost savings by deploying Base Stations (BSs) which harvest renewable energy as they reduce the energy drawn from the grid and its associated cost. The cost savings can be further enhanced by careful management of the system resources. Furthermore, mobile operators require that such resource management be carefully coupled with managing the quality of service (QoS) to ensure customer satisfaction. This process involves trade-off between energy drawn from the grid and the QoS performance. In contrast to prior research which has addressed the problem of joint management of grid energy savings and the QoS performance using user-association reconfiguration or BS on/off schemes, we present a framework for doing so using BS downlink power control. Our proposed framework is evaluated through simulations using a real BS deployment from London, UK, and we show its superior performance over existing benchmarks. We demonstrate that our framework can lead to around 40% grid energy savings with better network latency performance as compared to the traditionally used scheme.