An Energy Efficient Cell Selection Framework for Femtocell Networks With Limited Backhaul Link Capacity
TL;DR: This paper provides a framework for femtocell deployment in the urban scenario where interference, energy consumption, and backhaul capacity are major concerns, and proposes a novel QoS-aware cell selection scheme that assigns mobile users to femtocells considering the capacity improvement obtained per unit increase in energy consumption.
Abstract: Dense deployment of femtocells improves the network capacity without significantly burdening the operator with huge capital and operational expenditure. However, extremely dense deployment of femtocells comes with the cost of increased cochannel interference and higher energy consumption. Additionally, femtocells burden the existing ADSL/broadband lines by using them as backhaul to connect to the cellular core network. A cell selection scheme defines the criteria on which mobile users associate themselves with base stations. This criteria may include received signal quality, available bandwidth, and energy consumption. Hence, cell selection plays a crucial role in system capacity, load balancing, and energy consumption. In this paper, we provide a framework for femtocell deployment in the urban scenario where interference, energy consumption, and backhaul capacity are major concerns. We first model the energy consumption of base stations, user equipment, and wired backhaul links. Then, we propose an efficient spectrum and power allocation technique to mitigate interference and improve bandwidth utilization in the uplink and downlink, respectively. Finally, we suggest a novel QoS-aware cell selection scheme that assigns mobile users to femtocells considering the capacity improvement obtained per unit increase in energy consumption. The proposed cell selection scheme incorporates the energy consumption of the wired backhaul links and their limited capacity constraint into the cell selection criteria. Our proposed spectrum and power allocation technique, when combined with the proposed cell selection, leads to a significant reduction in energy consumption without any deterioration in the system capacity. Simulation results confirm that our proposed framework has the potential to significantly improve the energy efficiency of the network.
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TL;DR: In this paper , the authors present the main considerations for green communications and survey the related research on AI-based green communications, focusing on how AI techniques are adopted to manage the network and improve energy harvesting toward the green era.
Abstract: Green communications have always been a target for the information industry to alleviate energy overhead and reduce fossil fuel usage. In current 5G and future 6G era, there is no doubt that the volume of network infrastructure and the number of connected terminals will keep exponentially increasing, which results in the surging energy cost. It becomes growing important and urgent to drive the development of green communications. However, 6G will inevitably have increasingly stringent and diversified requirements for Quality of Service (QoS), security, flexibility, and even intelligence, all of which challenge the improvement of energy efficiency. Moreover, the dynamic energy harvesting process, which will be adopted widely in 6G, further complicates the power control and network management. To address these challenges and reduce human intervene, Artificial Intelligence (AI) has been widely recognized and acknowledged as the only solution. Academia and industry have conducted extensive research to alleviate energy demand, improve energy efficiency, and manage energy harvesting in various communication scenarios. In this paper, we present the main considerations for green communications and survey the related research on AI-based green communications. We focus on how AI techniques are adopted to manage the network and improve energy harvesting toward the green era. We analyze how state-of-the-art Machine Learning (ML) and Deep Learning (DL) techniques can cooperate with conventional AI methods and mathematical models to reduce the algorithm complexity and optimize the accuracy rate to accelerate the applications in 6G. Finally, we discuss the existing problems and envision the challenges for these emerging techniques in 6G.
55 citations
TL;DR: In this article , the authors proposed a dynamic optimization model to minimize the overall energy consumption of 5G heterogeneous networks and provide the essential coverage and capacity by optimizing carrier allocation and power utilization, the proposed model determines when to turn off small cells to meet the quality of service constraints of users with the highest level of energy efficiency.
Abstract: The dense deployment of small-cell networks is a key feature of the next-generation mobile networks employed to provide the necessary capacity increase. The small cells are installed in the areas covered by macro base stations (eNBs) to supply the required local capacity based on the known concept of the hierarchical HetNets. Moreover, small-cell networks use high-capacity backhaul links on millimeter-wave bands to develop multihop topologies to mitigate the costs of data transmission. Nonetheless, green networking gains great importance for the uncontrolled installation of too many small cells may escalate operational costs and emit more carbon dioxide. This article proposes a dynamic optimization model to minimize the overall energy consumption of fifth-generation (5G) heterogeneous networks and provide the essential coverage and capacity. Optimizing carrier allocation and power utilization, the proposed model determines when to turn on or off small cells to meet the quality of service constraints of users with the highest level of energy efficiency. We also proposed a multihop backhauling strategy to effectively use the existing infrastructure of small-cell networks for simultaneous dual-hop transmissions. The numerical results indicated considerable rates of power saving in different traffic models while guaranteeing the throughput requirements for uniform and hotspot user equipment distribution patterns. Also, according to the simulation results, energy efficiency and system data rates can significantly be improved.
22 citations
TL;DR: In this article , the authors proposed a dynamic optimization model to minimize the overall energy consumption of 5G heterogeneous networks and provide the essential coverage and capacity, which determines when to turn on or off small cells to meet the quality of service constraints of users with the highest level of energy efficiency.
Abstract: The dense deployment of small-cell networks is a key feature of the next-generation mobile networks employed to provide the necessary capacity increase. The small cells are installed in the areas covered by macro base stations (eNBs) to supply the required local capacity based on the known concept of the hierarchical HetNets. Moreover, small-cell networks use high-capacity backhaul links on millimeter-wave bands to develop multihop topologies to mitigate the costs of data transmission. Nonetheless, green networking gains great importance for the uncontrolled installation of too many small cells may escalate operational costs and emit more carbon dioxide. This article proposes a dynamic optimization model to minimize the overall energy consumption of fifth-generation (5G) heterogeneous networks and provide the essential coverage and capacity. Optimizing carrier allocation and power utilization, the proposed model determines when to turn on or off small cells to meet the quality of service constraints of users with the highest level of energy efficiency. We also proposed a multihop backhauling strategy to effectively use the existing infrastructure of small-cell networks for simultaneous dual-hop transmissions. The numerical results indicated considerable rates of power saving in different traffic models while guaranteeing the throughput requirements for uniform and hotspot user equipment distribution patterns. Also, according to the simulation results, energy efficiency and system data rates can significantly be improved.
18 citations
TL;DR: An efficient scheduling scheme is proposed, for scheduling wireless backhaul links, which works jointly with the proposed mode selection and relay probing scheme to further improve the system throughput and alleviate the losses incurred due to blockages.
Abstract: Exploiting the enormous chunks of mmWave spectrum between 30 GHz and 300 GHz have the potential to facilitate gigabit rate services to the future 5G cellular networks, and help in alleviating the current spectrum crisis. Conventional backhaul links such as Digital Subscriber Line (DSL) and Asymmetric Digital Subscriber Line (ADSL) have been proved to be a major bottleneck in satisfying these high data rate demands of indoor user equipments associated with traditional Femto Base Stations (FBS). One possible solution is to deploy higher capacity optical fiber cable to satisfy such demands. However, it is a costly and non-flexible solution. Thus, mmWave wireless backhaul links can be utilized at the FBSs. But due to their high-frequency, mmWave carrier signals are highly susceptible to obstacles and thus suffer a high attenuation in signal strength when passed through the obstacles. In order to alleviate the losses incurred due to blockages and to improve the signal reachability, in this paper, we propose an efficient distributed mode selection and dynamic relay probing scheme. We also propose an efficient scheduling scheme, for scheduling wireless backhaul links, which works jointly with the proposed mode selection and relay probing scheme to further improve the system throughput. Our proposed scheduling scheme permits non-interfering links to schedule and transmit concurrently. An expression for calculating the expected number of concurrent transmissions for our proposed scheduling scheme is derived and validated. Through extensive simulations under various system parameters, we have demonstrated the superiority of our proposed mode selection and relay probing scheme over the fixed relay probing scheme.
9 citations
TL;DR: The simulation results show that the proposed SMDP-based adaptive sleep strategy of the FBS can effectively reduce the network energy consumption.
Abstract: A dense heterogeneous cellular network can effectively increase the system capacity and enhance the network coverage. It is a key technology for the new generation of the mobile communication system. The dense deployment of small base stations not only improves the quality of network service, but also brings about a significant increase in network energy consumption. This paper mainly studies the energy efficiency optimization of the Macro-Femto heterogeneous cellular network. Considering the dynamic random changes of the access users in the network, the sleep process of the Femto Base Stations (FBSs) is modeled as a Semi-Markov Decision Process (SMDP) model in order to save the network energy consumption. And further, this paper gives the dynamic sleep algorithm of the FBS based on the value iteration. The simulation results show that the proposed SMDP-based adaptive sleep strategy of the FBS can effectively reduce the network energy consumption.
5 citations
References
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TL;DR: A brief survey of methods to improve the power efficiency of cellular networks, explore some research issues and challenges and suggest some techniques to enable an energy efficient or "green" cellular network.
Abstract: Energy efficiency in cellular networks is a growing concern for cellular operators to not only maintain profitability, but also to reduce the overall environment effects. This emerging trend of achieving energy efficiency in cellular networks is motivating the standardization authorities and network operators to continuously explore future technologies in order to bring improvements in the entire network infrastructure. In this article, we present a brief survey of methods to improve the power efficiency of cellular networks, explore some research issues and challenges and suggest some techniques to enable an energy efficient or "green" cellular network. Since base stations consume a maximum portion of the total energy used in a cellular system, we will first provide a comprehensive survey on techniques to obtain energy savings in base stations. Next, we discuss how heterogenous network deployment based on micro, pico and femtocells can be used to achieve this goal. Since cognitive radio and cooperative relaying are undisputed future technologies in this regard, we propose a research vision to make these technologies more energy efficient. Lastly, we explore some broader perspectives in realizing a "green" cellular network technology.
1,163 citations
TL;DR: In this article, the authors address Rayleigh fading, primarily in the UHF band, that affects mobile systems such as cellular and personal communication systems (PCS) and itemizes the fundamental fading mani.
Abstract: The paper addresses Rayleigh fading, primarily in the UHF band, that affects mobile systems such as cellular and personal communication systems (PCS) The paper itemizes the fundamental fading mani
953 citations
TL;DR: A stochastic geometry based model is used to derive the success probability and energy efficiency in homogeneous macrocell and heterogeneous K-tier wireless networks under different sleeping policies and provides an essential understanding on the deployment of future green heterogeneous networks.
Abstract: With the exponential increase in mobile internet traffic driven by a new generation of wireless devices, future cellular networks face a great challenge to meet this overwhelming demand of network capacity. At the same time, the demand for higher data rates and the ever-increasing number of wireless users led to rapid increases in power consumption and operating cost of cellular networks. One potential solution to address these issues is to overlay small cell networks with macrocell networks as a means to provide higher network capacity and better coverage. However, the dense and random deployment of small cells and their uncoordinated operation raise important questions about the energy efficiency implications of such multi-tier networks. Another technique to improve energy efficiency in cellular networks is to introduce active/sleep (on/off) modes in macrocell base stations. In this paper, we investigate the design and the associated tradeoffs of energy efficient cellular networks through the deployment of sleeping strategies and small cells. Using a stochastic geometry based model, we derive the success probability and energy efficiency in homogeneous macrocell (single-tier) and heterogeneous K-tier wireless networks under different sleeping policies. In addition, we formulate the power consumption minimization and energy efficiency maximization problems, and determine the optimal operating regimes for macrocell base stations. Numerical results confirm the effectiveness of switching off base stations in homogeneous macrocell networks. Nevertheless, the gains in terms of energy efficiency depend on the type of sleeping strategy used. In addition, the deployment of small cells generally leads to higher energy efficiency but this gain saturates as the density of small cells increases. In a nutshell, our proposed framework provides an essential understanding on the deployment of future green heterogeneous networks.
579 citations
"An Energy Efficient Cell Selection ..." refers background in this paper
...Recent studies have shown that deploying femtocells or Femto Access Points (FAPs) helps in improving the energy efficiency of the network in a cost effective manner [2], [3]....
[...]
Book•
01 Jan 2018
TL;DR: Key updates for the second edition of LTE for UMTS are focused on the new topics from Release 9 & 10, and include:LTE-Advanced;Self optimized networks (SON);Transport network dimensioning;Measurement results.
Abstract: Written by experts actively involved in the 3GPP standards and product development, LTE for UMTS, Second Edition gives a complete and up-to-date overview of Long term Evolution (LTE) in a systematic and clear manner. Building upon on the success of the first edition, LTE for UMTS, Second Edition has been revised to now contain improved coverage of the Release 8 LTE details, including field performance results, transport network, self optimized networks and also covering the enhancements done in 3GPP Release 9. This new edition also provides an outlook to Release 10, including the overview of Release 10 LTE-Advanced technology components which enable reaching data rates beyond 1 Gbps.Key updates for the second edition of LTE for UMTS are focused on the new topics from Release 9 & 10, and include:LTE-Advanced;Self optimized networks (SON);Transport network dimensioning;Measurement results.
521 citations
"An Energy Efficient Cell Selection ..." refers background in this paper
...The reason behind assigning only one UL RB to UEs comes from the fact that UEs in most practical deployments have comparatively low uplink data rate requirements [31], [32]....
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...Cellular industry estimates show that the ratio of data traffic in the DL to UL is about eight to one [31], [32]....
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TL;DR: It is shown in this article how a large system analysis based on random matrix theory (RMT) can provide tight and tractable approximations of key performance measures of SCNs.
Abstract: The exponentially increasing demand for wireless data services requires a massive network densification that is neither economically nor ecologically viable with the current cellular system architectures. A promising solution to this problem is the concept of small-cell networks (SCNs), which is founded by the idea of a very dense deployment of self-organizing, low-cost, low-power, base stations (BSs). Although SCNs have the potential to significantly increase the capacity of cellular networks while reducing their energy consumption, they pose many new challenges to the optimal system design. We show in this article how a large system analysis based on random matrix theory (RMT) can provide tight and tractable approximations of key performance measures of SCNs.
506 citations
"An Energy Efficient Cell Selection ..." refers background in this paper
...Recent studies have shown that deploying femtocells or Femto Access Points (FAPs) helps in improving the energy efficiency of the network in a cost effective manner [2], [3]....
[...]