Expanding cellular coverage via cell-edge deployment in heterogeneous networks: spectral efficiency and backhaul power consumption perspectives (original) (raw)
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Spectral and energy efficiency analysis of uplink heterogeneous networks with small-cells on edge
Physical Communication, 2014
Heterogeneous networks (HetNets) Cell-on-edge (COE) Cell-edge mobile users Spectral and energy efficiency Fast power control Generalized fading channels and interference reduction a b s t r a c t This paper presents a tractable mathematical framework to analyze the spectral and energy efficiency of an operator initiated deployment of the small-cells (e.g., femtocells) where the small-cell base stations are deliberately positioned around the edge of the macrocell. The considered deployment facilitates the cell-edge mobile users in terms of their coverage, spectral, and energy efficiency and is referred to as cell-on-edge (COE) configuration. The reduction in energy consumption is achieved by considering fast power control where the mobile users transmit with adaptive power to compensate the path loss, shadowing and fading. In particular, we develop a moment generating function (MGF) based approach to derive analytical bounds on the area spectral efficiency and exact expressions for the energy efficiency of the mobile users in the considered COE configuration over generalized-K fading channels. Besides the COE configuration, the derived bounds are also shown to be useful in evaluating the performance of random small-cell deployments, e.g., uniformly distributed small-cells. Simulation results are presented to demonstrate the improvements in spectral and energy efficiency of the COE configuration with respect to macro-only networks and other unplanned deployment strategies. (K.A. Qaraqe), serpedin@ece.tamu.edu (E. Serpedin), slim.alouini@kaust.edu.sa (M.-S. Alouini). energy efficient techniques that complement 5G wireless networks. The driving force to further develop LTE toward LTE-Advanced, is the required higher data rates and lower latency in a cost efficient manner. In LTE-Advanced, the focus is on increased peak data rates, higher spectral and energy efficiency, increased number of simultaneously active mobile users and last but not the least, improved performance at the cell-edges. The spectral efficiency of the cell-edge mobile users is often very poor due to the higher path-loss that affects the cell-edge users and thereby degrades the overall network coverage and capacity significantly . To address these stringent requirements, various technologies have been explored in the 3rd generation partnership project (3GPP)-study on http://dx.
Area green efficiency (AGE) of two tier heterogeneous cellular networks
2012 IEEE Globecom Workshops, 2012
Small cell networks are becoming standard part of the future heterogeneous networks. In this paper, we consider a two tier heterogeneous network which promises energy savings by integrating the femto and macro cellular networks and thereby reducing CO2 emissions, operational and capital expenditures (OPEX and CAPEX) whilst enhancing the area spectral efficiency (ASE) of the network. In this context, we define a performance metric which characterize the aggregate energy savings per unit macrocell area and is referred to as area green efficiency (AGE) of the two tier heterogeneous network where the femto base stations are arranged around the edge of the reference macrocell such that the configuration is referred to as femto-on-edge (FOE). The mobile users in macro and femto cellular networks are transmitting with the adaptive power while maintaining the desired link quality such that the energy aware FOE configuration mandates to (i) save energy, and (ii) reduce the co-channel interference. We present a mathematical analysis to incorporate the uplink power control mechanism adopted by the mobile users and calibrate the uplink ASE and AGE of the energy aware FOE configuration. Next, we derive analytical expressions to compute the bounds on the uplink ASE of energy aware FOE configuration and demonstrate that the derived bounds are useful in evaluating the ASE under worst and best case interference scenarios. Simulation results are produced to demonstrate the ASE and AGE improvements in comparison to macro-only and macro-femto configuration with uniformly distributed femtocells.
Energy Efficient Communications with Device-to-Device Links in Cellular Networks
ICWMC 2016 : The Twelfth International Conference on Wireless and Mobile Communications (includes QoSE WMC 2016)
Device-to-Device (D2D) communications in cellular networks allow devices to communicate directly without going through the base station. The D2D underlaying cellular networks method is aimed to increase network energy efficiency, as specified for Long-Term Evolution Advanced (LTE-A) and 5G systems. In this paper, we examine the performance of both cooperative and non-cooperative communications modes based on the energy models we establish, within a mobile network where both user equipment (UE) to base station and D2D transmission links co-exist. We show that the source-destination distance is an important factor to decide whether to use the cooperative or non-cooperative transmission scheme in order to achieve better energy efficiency. We have also investigated the effects of choosing different numbers of relaying branches and relays in each branch on the performance of the network. This investigation leads to identifying optimal transmission schemes for maximizing energy efficiency under varying environmental conditions.
Energy Efficient Heterogeneous Cellular Networks
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.
Energy-Aware Radio Resource Management in D2D-Enabled Multi-Tier HetNets
IEEE Access
Hybrid networks consisting of both millimeter wave (mmWave) and microwave (µW) capabilities are strongly contested for next-generation cellular communications. A similar avenue of current research is device-to-device (D2D) communications, where users establish direct links with each other rather than using central base stations. However, a hybrid network, where D2D transmissions coexist, requires special attention in terms of efficient resource allocation. This paper investigates dynamic resource sharing between network entities in a downlink transmission scheme to maximize energy efficiency (EE) of the cellular users (CUs) served by either (µW) macrocells or mmWave small cells while maintaining a minimum quality-of-service (QoS) for the D2D users. To address this problem, first, a self-adaptive power control mechanism for the D2D pairs is formulated, subject to an interference threshold for the CUs while satisfying their minimum QoS level. Subsequently, an EE optimization problem, which is aimed at maximizing the EE for both CUs and D2D pairs, has been solved. Simulation results demonstrate the effectiveness of our proposed algorithm, which studies the inherent tradeoffs between system EE, system sum rate, and outage probability for various QoS levels and varying densities of D2D pairs and CUs. INDEX TERMS Device-to-device (D2D) communication, energy efficiency, fifth generation (5G) network, heterogeneous network, millimeter wave, multi objective optimization and radio resource management.
Small Cells in Cellular Networks: Challenges of Future HetNets
Due to their low cost and easy deployment, small cells provide a viable and costeffective way of improving the cellular coverage and capacity both for homes and enterprises, both in metropolitan and rural areas. Stimulated by their attractive features and advantages, the ongoing development and deployment of small cells by manufacturers and mobile network operators have seen a surge in recent years. Together with macro-cells, they form, what are called Heterogeneous Networks or HetNets. However, the successful rollout and operation of small cells are still facing significan issues. In this paper the need for, challenges and solutions of small cell deployments are analyzed. This analysis is conducted with respect to self-organizing features, interference coordination, energy efficiency and spectrum efficiency. The analysis is complemented with numerical results based on system simulations in Macroonly and HetNet scenarios and also on real measurements performed on an mobile operator network. Results show the clear improvement that a HetNet brings in term of user throughput and also the amunt of spectrum waste that is present in nowadays' operator networks.
Improving capacity and energy efficiency of femtocell based cellular network through cell biasing
Future of cellular networks lies in heterogeneity. Heterogeneous cellular networks are characterized by overlay of low power nodes such as microcells, picocells, and femtocells along with traditional macrocell base stations. These nodes help operators to improve system capacity in cost effective manner while making the environment greener by reducing the carbon footprint. Research has shown that femtocells can be an effective solution to handle the increasing demands for indoor mobile traffic. However, low utilization of femtocell resources limits the gain obtained from their large scale deployment. Also, random placement of femtocells accumulate additional interference to macrocell users. In this paper, we introduce the concept of cell biasing for femtocells to improve user association and resource utilization. Our work analyses the effects of cell biasing on femtocell based cellular network and provides improvement in capacity and energy efficiency of the network through frequency...
Proceedings of the 2nd International Conference on Energy-Efficient Computing and Networking - e-Energy '11, 2011
We study the energy consumptions of two strategies that increase the capacity of an LTE network: (1) the deployment of redundant macro and micro base stations by the operator at locations where the traffic is high, and (2) the deployment of publicly accessible femto base stations by home users. Previous studies show the deployment of publicly accessible residential femto base stations is considerably more energy efficient; however, the results are proposed using an abstracted model of LTE networks, where the coverage constraint was neglected in the study, as well as some other important physical and traffic layer specifications of LTE networks. We study a realistic scenario where coverage is provided by a set of non-redundant macro-micro base stations and additional capacity is provided by redundant macro-micro base stations or by femto base stations. We quantify the energy consumption of macro-micro and femto deployment strategies by using a simulation of a plausible LTE deployment in a mid-size metropolitan area, based on data obtained from an operator and using detailed models of heterogeneous devices, traffic, and physical layers. The metrics of interest are operator-energy-consumption/totalenergy-consumption per unit of network capacity.
2014 IEEE Wireless Communications and Networking Conference (WCNC), 2014
Heterogeneous networks (HetNets) represent a promising solution for the next generation wireless networks (NGWNs), where many low power, low cost small-cells (e.g., femtocells) are planned to support the existing macrocell networks to reduce the over the air signaling and uplink power consumption, and thereby enhance the spectral efficiency compared to the macro-only network. In this context, the massive deployment of many lightly loaded small-cells is anticipated to increase the downlink power consumption of the HetNets. This paper investigates the end-to-end downlink power consumption of the HetNets, which consists of the power consumed by the macrocell and small-cell base stations and the backhaul to carry the traffic from the access to the core network. The downlink power consumption depends probabilistically on the population of the active mobile users in both the macrocell and small-cell networks such that the regulating factor is referred to as active user population factor (AUPF). A mathematical framework is presented to derive AUPF by assuming that the total population of active mobile users is a random variable and has a Binomial probability distribution. The number of active users and smallcells are calculated by the proposed probabilistic traffic model which assures the reduction in downlink power consumption since it now consists of the power consumption due to the base stations and backhaul for only the active population of mobile users. This model helps to evaluate the power consumption of HetNets. The simulations results indicate that AUPF and traffic load have significant impact on the downlink power consumption of HetNets.