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Cities are constantly evolving complex systems. Detection methods of land use distribution have to keep pace with their rapidly changing landscapes. While traditional analysis relies on surveys and census data typically refreshed at most yearly, the widespread use of mobile devices allows cell phone activity measurements to be used as sensors for the functional clustering of urban districts. These activity-based proprietary measurements are recently complemented by publicly available geosocial network records that even enable content-aware analysis. As a bridge between separate methods, in this work we analyze the relation of conversation content and functional spatial clusters of cities using a double dataset approach. We look at the differentiating power of the content of local conversations in activity-driven land use detection based on mobile phone records. In addition to intra-city analysis of three metropolises, we present a comparative study of London, New York City, and Los Angeles sharing the common language of English, but having very different cultural backgrounds. We show that the share of words with a similar temporal pattern to that of local mobile activities is different across cities, as well as between functional clusters. We find that the conversational content can effectively differentiate both functional clusters of a single city, and similar locations of the same function across many cities, like business areas that otherwise have a common temporal heartbeat. Moreover, we identify words related to activity types as the most important features emerging from the content-based, data-driven classification.

A flexible Discontinuous Reception (DRX) scheme is proposed to resolve the drawbacks of State-of-the-Art (SOTA) DRX scheme by eliminating the need of major timers and allowing Intra-Subframe Micro (ISM) sleep periods. The proposed new Timer Eliminating DRX (TE-DRX) scheme was tested and analyzed with traffic logs from live mobile network. This scheme can drastically reduce the active time of mobile devices by more than 75% and can thereby save at least 40% of energy to be used and improve battery life compared to practical technology limit of (SOTA) solution. It is shown that scheduling can be made relaxed. That is, the system is not forced to schedule data for (DRX) users in the first subframes of radio frames, and good performance does not require scheduling user data in consecutive subframes (like in case of short On-duration timers). Thereby it is possible to save energy even in heavily loaded systems and make very efficient (DRX) reality in legacy networks comparable to 5th Generation (5G) sleep mode proposals. Moreover, the proposed method can be considered as a possible extension of upcoming (5G) networks, as well.

Thanks to their widespread usage,mobile devices have become one of the main sensors of human behaviour and digital traces left behind can be used as a proxy to study urban environments. Exploring the nature of the spatio-temporal patterns of mobile phone activity could thus be a crucial step towards understanding the full spectrum of human activities. Using 10 months of mobile phone records from Greater London resolved in both space and time, we investigate the regularity of human telecommunication activity on urban scales. We evaluate several options for decomposing activity timelines into typical and residual patterns, accounting for the strong periodic and seasonal components. We carry out our analysis on various spatial scales, showing that regularity increases as we look at aggregated activity in larger spatial units with more activity in them. We examine the statistical properties of the residuals and show that it can be explained by noise and specific outliers. Also, we look at sources of deviations from the general trends, which we find to be explainable based on knowledge of the city structure and places of attractions. We show examples how some of the outliers can be related to external factors such as specific social events. © 2017 The Authors.

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.

Interference elimination is a key aspect of planning and operating wireless networks. Using frequency duplex links is a common practice, where the communication is done via two channels separated in frequency. An optimization problem is how to allocate the channels in the frequency duplex in order to reduce or completely eliminate the interference might occur between links. In a previous paper we revealed the unexpected difference between this problem and polarization setting if the sharpness of the applied beam widths is relaxed in such microwave networks. In this paper we extend the graph theory based approach of this problem and generalize the special cases of the previous study.

With the explosion of wireless communications in number of users and data rates, the reduction of network power consumption becomes more and more critical. This is especially true for base stations which represent a dominant share of the total power in cellular networks. In order to study power reduction techniques, a convenient power model is required, providing estimates of the power consumption in different scenarios. This paper proposes such a model, accurate but simple to use. It evaluates the base station power consumption for different types of cells supporting the 3GPP LTE standard. It is flexible enough to enable comparisons between state-of-the-art and advanced configurations, and an easy adaptation to various scenarios. The model is based on a combination of base station components and sub-components as well as power scaling rules as functions of the main system parameters. © 2012 IEEE.

This paper discusses how energy consumption can be significantly reduced in mobile networks by introducing discontinuous transmission (DTX) on the base station side. By introducing DTX on the downlink, or cell DTX, we show that it is possible to achieve significant energy reductions in an LTE network. Cell DTX is most efficient when the traffic load is low in a cell but even when realistic traffic statistics are considered the gains are impressive. The technology potential for a metropolitan area is shown to be 90% reduced energy consumption compared to no use of cell DTX. The paper also discusses different drives for the increased focus on energy efficient network operation and also provides insights on the impact of cell DTX from a life cycle assessment perspective.

In order to quantify the energy savings in wireless networks, the power consumption of the entire system needs to be captured and an appropriate energy efficiency evaluation framework must be defined. In this paper, the necessary enhancements over existing performance evaluation frameworks are discussed, such that the energy efficiency of the entire network comprising component, node and network level contributions can be quantified. The most important addendums over existing frameworks include a sophisticated power model for various base station (BS) types, which maps the RF output power radiated at the antenna elements to the total supply power of a BS site. We also consider an approach to quantify the energy efficiency of large geographical areas by using the existing small scale deployment models along with long term traffic models. Finally, the proposed evaluation framework is applied to quantify the energy efficiency of the downlink of a 3GPP LTE radio access network.

In order to quantify the energy efficiency of a wireless network, the power consumption of the entire system needs to be captured. In this article, the necessary extensions with respect to existing performance evaluation frameworks are discussed. The most important addenda of the proposed energy efficiency evaluation framework (E3F) are a sophisticated power model for various base station types, as well as large-scale long-term traffic models. The BS power model maps the RF output power radiated at the antenna elements to the total supply power of a BS site. The proposed traffic model emulates the spatial distribution of the traffic demands over large geographical regions, including urban and rural areas, as well as temporal variations between peak and off-peak hours. Finally, the E3F is applied to quantify the energy efficiency of the downlink of a 3GPP LTE radio access network.

This paper analyses how much the capacity layer of HetNets are utilized as the function of momentary traffic demand and user distribution. It is shown that the capacity layer is inevitably underutilized and it is worth to apply power saving techniques to reduce the energy used by the capacity layer of the HetNet.

Mobile communications are increasingly contributing to global energy consumption. The EARTH (Energy Aware Radio and neTworking tecHnologies) project tackles the important issue of reducing CO emissions by enhancing the energy efficiency of cellular mobile networks. EARTH is a holistic approach to develop a new generation of energy efficient products, components, deployment strategies and energy-aware network management solutions. In this paper the holistic EARTH approach to energy efficient mobile communication systems is introduced. Performance metrics are studied to assess the theoretical bounds of energy efficiency as well as the practical achievable limits. A vast potential for energy savings lies in the operation of radio base stations. In particular, base stations consume a considerable amount of the available power budget even when operating at low load. Energy efficient radio resource management (RRM) strategies need to take into account slowly changing daily load patterns, as well as highly dynamic traffic fluctuations. Moreover, various deployment strategies are examined focusing on their potential to reduce energy consumption, whilst providing uncompromised coverage and user experience. This includes heterogeneous networks with a sophisticated mix of different cell sizes, which may be further enhanced by energy efficient relaying and base station cooperation technologies. Finally, scenarios leveraging the capability of advanced terminals to operate on multiple radio access technologies (RAT) are discussed with respect to their energy savings potential. ©2010 IEEE.