There is considerable pressure to define the key requirements of 5G, develop 5G standards, and perform technology trials as quickly as possible. Normally, these activities are best done in series but there is a desire to complete these tasks in parallel so that commercial deployments of 5G can begin by 2020. 5G will not be an incremental improvement over its predecessors; it aims to be a revolutionary leap forward in terms of data rates, latency, massive connectivity, network reliability, and energy efficiency. These capabilities are targeted at realizing high-speed connectivity, the Internet of Things, augmented virtual reality, the tactile internet, and so on. The requirements of 5G are expected to be met by new spectrum in the microwave bands (3.3-4.2 GHz), and utilizing large bandwidths available in mm-wave bands, increasing spatial degrees of freedom via large antenna arrays and 3-D MIMO, network densification, and new waveforms that provide scalability and flexibility to meet the varying demands of 5G services. Unlike the one size fits all 4G core networks, the 5G core network must be flexible and adaptable and is expected to simultaneously provide optimized support for the diverse 5G use case categories. In this paper, we provide an overview of 5G research, standardization trials, and deployment challenges. Due to the enormous scope of 5G systems, it is necessary to provide some direction in a tutorial article, and in this overview, the focus is largely user centric, rather than device centric. In addition to surveying the state of play in the area, we identify leading technologies, evaluating their strengths and weaknesses, and outline the key challenges ahead, with research test beds delivering promising performance but pre-commercial trials lagging behind the desired 5G targets.

5G : A tutorial overview of standards, trials, challenges, deployment, and practice

Future generation cellular networks are expected to provide ubiquitous broadband access to a continuously growing number of mobile users. In this context, LTE systems represent an important milestone towards the so called 4G cellular networks. A key feature of LTE is the adoption of advanced Radio Resource Management procedures in order to increase the system performance up to the Shannon limit. Packet scheduling mechanisms, in particular, play a fundamental role, because they are responsible for choosing, with fine time and frequency resolutions, how to distribute radio resources among different stations, taking into account channel condition and QoS requirements. This goal should be accomplished by providing, at the same time, an optimal trade-off between spectral efficiency and fairness. In this context, this paper provides an overview on the key issues that arise in the design of a resource allocation algorithm for LTE networks. It is intended for a wide range of readers as it covers the topic from basics to advanced aspects. The downlink channel under frequency division duplex configuration is considered as object of our study, but most of the considerations are valid for other configurations as well. Moreover, a survey on the most recent techniques is reported, including a classification of the different approaches presented in literature. Performance comparisons of the most well-known schemes, with particular focus on QoS provisioning capabilities, are also provided for complementing the described concepts. Thus, this survey would be useful for readers interested in learning the basic concepts before going into the details of a particular scheduling strategy, as well as for researchers aiming at deepening more specific aspects.

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Downlink Packet Scheduling in LTE Cellular Networks: Key Design Issues and a Survey

The fifth-generation mobile initiative, 5G, is a tremendous and collective effort to specify, standardize, design, manufacture, and deploy the next cellular network generation. 5G networks will support demanding services such as enhanced Mobile Broadband, Ultra-Reliable and Low Latency Communications and massive Machine-Type Communications, which will require data rates of tens of Gbps, latencies of few milliseconds and connection densities of millions of devices per square kilometer. This survey presents the most significant use cases expected for 5G including their corresponding scenarios and traffic models. First, the paper analyzes the characteristics and requirements for 5G communications, considering aspects such as traffic volume, network deployments, and main performance targets. Secondly, emphasizing the definition of performance evaluation criteria for 5G technologies, the paper reviews related proposals from principal standards development organizations and industry alliances. Finally, well-defined and significant 5G use cases are provided. As a result, these guidelines will help and ease the performance evaluation of current and future 5G innovations, as well as the dimensioning of 5G future deployments.

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A Survey on 5G Usage Scenarios and Traffic Models

The fifth generation of cellular communication systems is foreseen to enable a multitude of new applications and use cases with very different requirements. A new 5G multi-service air interface needs to enhance broadband performance as well as provide new levels of reliability, latency, and supported number of users. In this paper, we focus on the massive Machine Type Communications (mMTC) service within a multi-service air interface. Specifically, we present an overview of different physical and medium access techniques to address the problem of a massive number of access attempts in mMTC and discuss the protocol performance of these solutions in a common evaluation framework.

Towards Massive Connectivity Support for Scalable mMTC Communications in 5G Networks

We present a comprehensive model for variable-bit-rate MPEG video streams. This model captures the bit-rate variations at multiple time scales. Long-term variations are captured by incorporating scene changes, which are most noticeable in the fluctuations of I frames. The size of an I frame is modeled by the sum of two random components: a scene-related component and an AR(2) component that accounts for the fluctuations within a scene. Two random processes of i.i.d. rvs are used to model the sizes of P and B frames, respectively. The complete model is then obtained by intermixing the three sub-models according to a given GOP pattern. It is shown that the composite model exhibits long-range dependence (LRD) in the sense that its autocorrelation function is non-summable. The LRD behavior is caused by the repetitive GOP pattern which induces periodic cross-correlations between different types of frames. Using standard statistical methods, we successfully fit our model to several empirical video traces. We then study the queueing performance for video traffic at a statistical multiplexer. The results show that the model is sufficiently accurate in predicting the queueing performance for real video streams.

On the characterization of VBR MPEG streams

Disclosed herein is a radio resource scheduling method for scheduling radio resources used for communications in a radio communication system which comprises user equipments configured to communicate with transceiver- stations on said radio resources The transceiver stations are configured to exchange coordination messages concerning radio resources affected by intra- system interference The radio resource scheduling method comprises allocating to each user equipment served by a serving transceiver station a corresponding radio resource and a corresponding transmission power level to communicate with said serving transceiver station Allocating is based on coordination messages exchanged by said serving transceiver station

Radio resource scheduling for intra-system interference coordination in wireless communication systems

A method for controlling a heterogeneous wireless network (100) is proposed. The heterogeneous wireless network comprises at least one first base station (115) which manages communication of a plurality of first user equipments (125M) positioned in at least one first cell (105) and at least one second base station (120) which manages communication of a plurality of second user equipments (125p) positioned in at least one second cell (110). Moreover, in the heterogeneous network (100), for each first user equipment (125M) the at least one first base station (115) provides a respective first allocation information set over a respective first allocation time interval. Similarly, the at least one second base station (120) provides for each second user equipment (125p) a respective second allocation information set over a respective second allocation time interval. Furthermore, each first allocation information set and each second allocation information set define transmission resources for communications of each first user equipment (125M) and of each second user equipment (125M), respectively. In the heterogeneous wireless network (100), the at least one second cell (110) is at least partially comprised in the first cell (105). The method comprises the following steps. Said at least one first base station determines (305) a set of probably interfering first user equipments (125 M ) with at least one of the plurality of second user equipments (125 p ). Said step of determining the set of probably interfering first user equipments (125 M ) comprises the following steps. Comparing each second allocation information set with each first allocation information set having the first allocation time interval at least partially overlapped with the respective second allocation time interval, and identifying as a probably interfering first user equipment (125 M ) each first user equipment (125 M ) for which a correspondence is verified in said comparing allocation information sets. The method further comprises the following steps. Said at least one second base station (120) defines a detection time window in order to analyze univocal identifiers transmitted by probably interfering first user equipments (125 M ) in said set. The method comprises identifying (315) a subset of effectively interfering first user equipments (125 M ) with the plurality of second user equipments (125 p ). Said at least one first base station (115) modifies (325) said transmission resources for at least one first user equipment (125 M ) comprised in the subset of effectively interfering first user equipments (125 M ) in order to mitigate interferences.

Uplink interference mitigation in heterogeneous mobile networks

this document analyses the energy efficiency of two relaying schemes that represent a possible way to deploy a relay enhanced network: the two hop scheme and the multicast cooperative scheme. Results exist in literature that provide a model for the theoretical evaluation of the capacity improvement that these solutions can yield, however no analysis is available at present on the energy efficiency of these schemes. This work enhances the existing theoretical models for capacity evaluations, providing a first analysis from an energy efficiency point of view of these two approaches, considering a fully loaded network and the total emitted RF power of the transmitting nodes. Results are provided in terms of the Energy Consumption Index (ECI) of these schemes, a metric proposed in the EARTH project for the assessment of the energy consumption of network solutions. The ECI distribution is obtained and compared with the case of a network deployed without relay nodes, showing that besides the possible improvements in capacity, relays are also candidates as a valuable tool to reduce the energy consumption of a telecommunication network.

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Energy Efficiency in LTE-Advanced Networks with Relay Nodes

Network-controlled device-to-device (D2D) communication allows cellular users to communicate directly, i.e., without passing through the eNodeB, while the latter retains control over resource allocation. This allows the same time---frequency resources to be allocated to spatially separated D2D flows simultaneously, thus increasing the cell throughput. This paper presents a framework for: (1) selecting which communications should use the D2D mode, and when, and (2) allocating resources to D2D and non-D2D users, exploiting reuse for the former. We show that the two problems, although apparently similar, should be kept separate and solved at different timescales in order to avoid problems, such as excessive packet loss. We model both as optimization problems, and propose a heuristic solution to the second, which must be solved at millisecond timescales. Simulation results show that our framework is practically viable, it avoids the problem of packet losses, increases throughput and reduces delays.

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Resource allocation for network-controlled device-to-device communications in LTE-Advanced

In this contribution, the performance of LTE system with various scheduling algorithm taken from the literature are considered. In order to assess the performance of state of the art schedulers a dynamic system level simulator is used that models in details all the features of the downlink of an LTE system in a multi-cell environment. The simulator will be used to analyze the impact of different scheduling policies from an energy efficiency point of view, considering different traffic models. In particular the first step involves analyzing the performances of SOTA algorithms, because up to now these schedulers have been compared from a more traditional point of view (e. g. SE, spectral efficiency) and not for the energy efficiency (EE) evaluation.

Marco Caretti

Papers

Radio resource scheduling for intra-system interference coordination in wireless communication systems

Uplink interference mitigation in heterogeneous mobile networks

Energy Efficiency in LTE-Advanced Networks with Relay Nodes

Resource allocation for network-controlled device-to-device communications in LTE-Advanced

Energy Efficiency Evaluation of State of the Art Packet Scheduling algorithms for LTE