Each mobile network architecture able to meet the traffic requirements of future 5G services comes with its own set of benefits vs. requirements for the radio and the transport segments. This paper focuses on the energy performance of four mobile network architectures, each one with different splitting options for the baseband processing functions. The radio segment under exam is based on a new radio access technology referred to as 5G-NX, while the transport segment is based on wavelength division multiplexing (WDM). The energy consumption of each mobile network architecture is weighted against (i) the benefits for the radio segment as a function of the level of centralization of the baseband processing resources and (ii) the required transport capacity and consequently the power consumption levels needed to accommodate the backhaul, midhaul, and/or fronthaul traffic generated at each base station. Our results show that a fully centralized radio access network (C-RAN) with centralization of all the baseband functions is not a practical approach for 5G mobile networks, while a partially centralized C-RAN architecture in which the physical layer baseband processing is performed at the base station site represents a promising solution.

Energy efficiency is of profound importance for prospective 5G wireless networks, especially in sparsely populated rural areas where broadband mobile services should be provided at a reasonable cost. In this paper the impact of beamforming (BF) and cell discontinuous transmission (cell DTX) technologies on the average area power consumption is studied. The required density of base stations for a 5G cellular system in a rural environment is also investigated. For this purpose, we propose a simple rural area model that captures a non-uniform distribution of users and employ the generalized Lloyd algorithm to determine the deployment of base stations. We assume a 5G system operating in mmWave band centered at 28 GHz with the bandwidth of 100 MHz, compared with existing LTE networks at 0.8 GHz with a 20 MHz bandwidth. Simulation results show that for the 5G network the density of base stations needed to provide 50 Mbps for 95% of users at the busy hour will be reduced by 8-9 times with the implementation of BF. It is also observed that BF has a greater effect on the energy saving of 5G networks in rural areas in comparison to the cell DTX.

In this paper, we revisit the radio network energy performance evaluation methodology, commonly known as E3F, that was developed in the European EARTH project during 2010-2011. We propose updates to the large-scale deployment and long-term traffic models in order to reflect the situation in a 5G time frame, and also an improvement in the sense that the baseline network is dimensioned to exactly meet the traffic and performance requirements. As an example, we apply the methodology in order to dimension and evaluate the energy performance of a state-of-the-art country-wide LTE network. The inter site distances of the resulting network range from 380 m in super dense urban (serving 20,000 citizens/km2) to 4850 m in rural areas (serving 100 citizens/km2). The resulting average power per area unit is 0.14 kW/km2, which is significantly lower than what was found in the EARTH project. This can be explained by two factors: i) The present study assumes more efficient base stations, and ii) the baseline network of the original E3F was over-dimensioned. Nevertheless, the conclusion from the EARTH project, that the absolute majority of energy consumed in a radio network is spent on providing coverage, still remains.

In this paper, we evaluate the technology potential of a new 5G radio access technology (RAT), here denoted 5G-NX, in terms of energy performance at the country level, in order to show what can be expected in the future when networks are being modernized and new technology is rolled out. To this end, per deployment area we calculate the daily energy consumption via system level simulations considering a typical European country categorized by six deployment areas, and extend the results to country scale according to a large-scale deployment model. The results show that 55% energy saving is achievable at the country level with 5G-NX networks while providing up to 15 times more capacity and 9 times higher peak rate compared to a baseline LTE network using the same site grid.

Mobile networks are the largest contributor to the carbon footprint of the telecom sector and their contribution is expected to rapidly increase in the future due to the foreseen traffic growth. Therefore, there is an increasing urgency in the definition of green mobile network deployment strategies. This paper proposes a four-step design and power assessment methodology for mobile networks, taking into consideration both radio and transport segments. A number of mobile network deployment architectures for urban residential areas based on different radio (i.e., macro base station, distributed indoor radio, femto cell) and transport (i.e., microwave, copper, optical fiber) technologies are proposed and evaluated to identify the most energy efficient solution. The results show that with low traffic the conventional macro base station deployment with microwave based backhaul is the best option. However, with higher traffic values heterogeneous networks with macro base stations and indoor small cells are more energy efficient. The best small cell solution highly depends on the transport network architecture. In particular, our results show that a femto cell based deployment with optical fiber backhaul is the most energy efficient, even if a distributed indoor radio architecture (DRA) deployment with fiber fronthaul is also a competitive approach.

This paper presents the energy performance of a new radio access technology (RAT) component in 5G, here denoted as 5G-NX. The 5G-NX RAT encompasses massive beamforming and an ultra-lean design as two of its key technology components. The user throughput, resource utilization of the cells and daily average area power consumption are evaluated by means of system level simulations in an Asian city scenario, and the results are compared with a traditional LTE deployment using the same network layout. The simulation results indicate that the new 5G-NX system provides much better energy performance compared to LTE and this is primarily due to the ultra-lean design and the high beamforming gain that provides both longer and more efficient component sleep in the network. At expected traffic levels beyond 2020, 5G-NX is shown to decrease the network energy consumption by more than 50% while providing around 10 times more capacity.

To meet future demands on user experience and traffic volumes, mobile networks need to evolve towards providing higher capacities and data rates. In this paper we investigate the feasibility of incorporating higher frequency bands (15 GHz) and beamforming to support this evolution. We see that using user-specific beamforming, the challenging propagation conditions at higher frequencies are mitigated and outdoor-in coverage is often possible. In places where 15 GHz coverage is not satisfactory, swift fallback to a lower frequency band is essential. This is seamlessly provided by carrier aggregation with a 2.6 GHz band. Together these components provide a ten-fold increase in capacity over a reference system operating only at 2.6 GHz.

Mobile operators are facing an exponential traffic growth due to the proliferation of portable devices that require a high-capacity connectivity. This, in turn, leads to a tremendous increase of the energy consumption of wireless access networks. A promising solution to this problem is the concept of heterogeneous networks, which is based on the dense deployment of low-cost and low-power base stations, in addition to the traditional macro cells. However, in such a scenario the energy consumed by the backhaul, which aggregates the traffic from each base station towards the metro/core segment, becomes significant and may limit the advantages of heterogeneous network deployments. This paper aims at assessing the impact of backhaul on the energy consumption of wireless access networks, taking into consideration different data traffic requirements (i.e., from todays to 2020 traffic levels). Three backhaul architectures combining different technologies (i.e., copper, fiber, and microwave) are considered. Results show that backhaul can amount to up to 50% of the power consumption of a wireless access network. On the other hand, hybrid backhaul architectures that combines fiber and microwave performs relatively well in scenarios where the wireless network is characterized by a high small-base-stations penetration rate.

Energy efficiency in mobile radio networks has recently gained great interest due to escalating energy cost and environmental concerns. Rapidly growing demand for capacity will require denser and denser networks which further increase the energy consumption. In this regard, the deployment of small cells under macro-cellular umbrella coverage appears a promising solution to cope with the explosive demand in an energy efficient manner. In this paper, we investigate the impact of joint macro-and femtocell deployment on energy efficiency of wireless access networks, based on varying area throughput requirements. We take into account the the co-channel interference, fraction of indoor users, femto base station density and backhaul power consumption. It is shown that utilizing indoor base stations provide significant energy savings compared to traditional macro only network in urban areas with medium and high user demand where the gain increases up to 75 percent as more data traffic is offloaded to femtocells.

In 2020, mobile access networks will experience significant challenges as compared to the situation of today. Traffic volumes are expected to increase 1000 times, and the number of connected devices will be 10-100 times higher than today in a networked society with unconstrained access to information and sharing of data available anywhere and anytime to anyone and anything. One of the big challenges is to provide this 1000-fold capacity increase to billions of devices in an affordable and sustainable way. Low energy consumption is the key to achieve this. This paper takes as starting point the situation of today, and tries to pinpoint important focus areas and potential solutions when designing an energy efficient 5G mobile network architecture. These include system architecture, where a logical separation of data and control planes is seen as a promising solution; network deployment, where (heterogeneous) ultra dense layouts will have a positive effect; radio transmission, where the introduction of massive antenna configurations is identified as an important enabler; and, finally, backhauling solutions that need to be more energy efficient than today.

Energy efficiency in cellular mobile radio networks has recently gained great interest in the research community. The development of more energy efficient hardware and software components aside, effect of different deployment strategies on energy efficiency are also studied in the literature. The latter mainly consist of optimizing the number and the location of different types of base stations in order to minimize the total power consumption. Usually, in the literature, the total network power consumption is restricted to the sum of the power consumption of all base stations. However, the choice of a specific deployment also affects the exact implementation of the backhaul network, and consequently its power consumption, which should therefore be taken into account when devising energy efficient deployment. In this paper, we propose a new power consumption model for a mobile radio network considering backhaul. We then handle a case study and perform a comparison of the power consumption of three different heterogeneous network deployments, and show how backhaul has a non-negligible impact on total power consumption, which differs for different deployments. An energy efficiency analysis is also carried out for different area throughput targets.

Cognitive radio is an enabling technology for efficient utilization of radio spectrum. In this paper, an orthogonal frequency division multiple access (OFDMA) based cognitive (opportunistic) network is considered, which co-exists with a macrocell network through utilizing its unused subcarriers. We particularly consider the uplink opportunity detection problem by the opportunistic network, where accurate synchronization to the macrocell network is crucial for minimizing the interference received from the macrocell users. After demonstrating the impact of synchronization on the inter-carrier-interference (ICI) observed at the opportunistic network, an improved blind first-user synchronization technique is proposed, and its statistics are analyzed. Through computer simulations it is shown that the proposed technique yields less interference and better opportunities for the opportunistic network.