Human-centric quality management of immersive multimedia applications

Augmented Reality (AR) and Virtual Reality (VR) multimodal systems are the latest trend within the field of multimedia. As they emulate the senses by means of omni-directional visuals, 360 degrees sound, motion tracking and touch simulation, they are able to create a strong feeling of presence and interaction with the virtual environment. These experiences can be applied for virtual training (Industry 4.0), tele-surgery (healthcare) or remote learning (education). However, given the strong time and task sensitiveness of these applications, it is of great importance to sustain the end-user quality, i.e. the Quality-of-Experience (QoE), at all times. Lack of synchronization and quality degradation need to be reduced to a minimum to avoid feelings of cybersickness or loss of immersiveness and concentration. This means that there is a need to shift the quality management from system-centered performance metrics towards a more human, QoE-centered approach. However, this requires for novel techniques in the three areas of the QoE-management loop (monitoring, modelling and control). This position paper identifies open areas of research to fully enable human-centric driven management of immersive multimedia. To this extent, four main dimensions are put forward: (1) Task and well-being driven subjective assessment; (2) Real-time QoE modelling; (3) Accurate viewport prediction; (4) Machine Learning (ML)-based quality optimization and content recreation. This paper discusses the state-of-the-art, and provides with possible solutions to tackle the open challenges

A New Frequency Planning for Improved Capacity and Coverage in Sectorized OFDMA Cellular Networks

One of the main challenges in cellular systems is how to reduce Other Cells Interference (OCI) while keeping high spectral efficiency and high coverage probability. Since the beginning of cellular technologies, frequency planning with sectoring has been used to mitigate such OCI. However, in modern wireless Orthogonal Frequency Division Multiple Access (OFDMA) technologies much attention is being paid to more complex strategies like Coordintation Multi-Point transmission/reception (CoMP) techniques due to its higher performance. This paper presents a new frequency planning for sectorized cell networks. Simulation results show that this scheme considerably outperforms classical sectoring (CS) in terms of both capacity and coverage probability. In particular, for the case of hexagonal grid, the capacity improvement is around 6 b/s/Hz compared to CS while keeping a coverage probability higher than 0.9 for a 0 dB Signal to Interference plus Noise Ratio (SINR) threshold.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A New Tractable Model to Estimate the Uplink Inter-Cell Interference in LTE

This paper presents a tractable model to estimate the uplink Inter-Cell Interference (ICI) in fully loaded LTE networks. Interfering users are considered to be uniformly distributed in an annulus so that evaluation of the interference power is obtained asymptotically for a high number of users. Model validity is proved through Monte Carlo simulations, showing that analytical results are close to simulation results even for a low number of users per cell.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Contextual bandit learning-based viewport prediction for 360 video

Accurately predicting where the user of a Virtual Reality (VR) application will be looking at in the near future improves the perceive quality of services, such as adaptive tile-based streaming or personalized online training. However, because of the unpredictability and dissimilarity of user behavior it is still a big challenge. In this work, we propose to use reinforcement learning, in particular contextual bandits, to solve this problem. The proposed solution tackles the prediction in two stages: (1) detection of movement; (2) prediction of direction. In order to prove its potential for VR services, the method was deployed on an adaptive tile-based VR streaming testbed, for benchmarking against a 3D trajectory extrapolation approach. Our results showed a significant improvement in terms of prediction error compared to the benchmark. This reduced prediction error also resulted in an enhancement on the perceived video quality

Coordinated Multicast/Unicast Transmission on 5G: A Novel Approach for Linear Broadcasting

Linear broadcasting services, with a scheduled programming, constitute a paramount tel-ecommunication service for today’s society. Although the existing technology is mature, current linear broadcast systems have serious limitations when providing service to moving users or users placed in areas with complex orography and poor signal quality. To over-come these limitations, 3GPP 5G standard has included a work item to support 5G mul-ticast/broadcast services for future Release 17. This paper investigates the integration of point-to-point (unicast) communication with cellular multicast/broadcast on 5G technology to extend the current support of linear broadcasting services. This integration relies on the use mobile edge computing (MEC) at the 5G base station (gNB) to host a dynamic adap-tive streaming over HTTP (DASH) server that is coordinated with the multicast transmis-sion to complement the broadcast service. This approach join the reliability of point-to-point communications, with dedicated resources for each user, with the spectrum efficiency of multi-cast communications, where a set of users share common resources. The coopera-tion between those unicast and multicast schemes allows those users whose coverage is not good enough, to complete the linear broadcast flow through the point-to-point transmission via MEC. The benefits of such approach have been assessed with simulations in a realistic scenario that considers a vehicle moving across a sparsely populated region in southern Spain. Results reveals that throughput and bitrate playback (reproduction rate) are greatly improved when unicast/multicast integration is enabled since the number of stalling events is reduced significantly.This work has been partially supported by Radio Televisión Española through Impulsa Visión RTVE grant and by the Universidad de Málaga. We are grateful to Pere Vila, Esteban Mayoral Campos, Adolfo Muñoz Berrón and Miguel Ángel Bona San Vicente for their support and collaboration during the development of the project. Funding for open access charge: Universidad de Málaga / CBU

Doppler Spectrum Analysis in Three-Dimensional 5G Millimeter-Wave Channel Models

This article is contextualized in the mobile communications systems where there are multiple factors to consider: mobility, frequency, obstacles, reflectors, etc. In this paper, is presented an evaluation of the Doppler spectrum in a Three-Dimensional (3D) channel model for different frequencies, User Terminal (UT) directions and UT speeds. To commence, it introduces the channel model that is used for the simulations, then the Classical Doppler Spectrum frequently used in Two-Dimensional (2D) channel models is entered. Finally, it tries the Doppler Spectrum for the some typical 5G frequencies, speeds up to 500 km/h and for the motion direction in the 3D space.Spanish Government (Ministerio de Economia y Competitividad) and FEDER under grant TEC2016-80090-C2-1-R and by the Universidad de Málaga, Campus de Excelencia Internacional Andalucía Tech