Architecture landscape

The network architecture evolution journey will carry on in the years ahead, driving a large scale adoption of 5th Generation (5G) and 5G-Advanced use cases with significantly decreased deployment and operational costs, and enabling new and innovative use-case-driven solutions towards 6th Generation (6G) with higher economic and societal values. The goal of this chapter, thus, is to present the envisioned societal impact, use cases and the End-to-End (E2E) 6G architecture. The E2E 6G architecture includes summarization of the various technical enablers as well as the system and functional views of the architecture

Application of Quality of Experience in Networked Services: Review, Trend & Perspectives

Full text embargoed until 17.10.2019 (publisher's embargo period, 12 months

QoE estimation model for a secure real-time voice communication system in the cloud

As moving towards cloud-based real-time services, we are witnessing the shift from a technology-driven services to service provisioning paradigms, that is, from Quality of Service (QoS) to Quality of Experience (QoE). User experience and satisfaction are placed at the epicenter of the system design. QoE is a measurement of user experience on the provided service by a system. Often QoE is measured by subjective mechanisms, such as user experience surveys and mean opinion scores (MOS) methods, which can be a costly and time-consuming process. Using an adequate QoE model to measure user experience of perceived quality is cost-effective, compared to using time-consuming subjective surveys. Applying an adequate QoE model to assess user experience is advantageous for cloud-based real-time services such as voice and video. This study uses a formula-based QoE estimation model to estimate and predict QoE prior to the deployment or during the planning stage of the system service. This study investigates a real-world scenario of a company that recently moved to its premises-based real-time trading communication system (TCS) to a public cloud. A simulation system using OPNET is also implemented to illustrate the usefulness of the model. Our result shows that the effect of delay on the users experience of the service provided by the cloudbased TCS is minimum comparing to packet loss rate (PLR) and Jitter. However, it has been observed that the overhead of the different security settings of the TCS system had no major negative impact to the user experience. The proposed model can be used as a QoE control mechanism and network optimization for cloudbased TCS services

Increasing spatial spectrum utilization through opportunistic user-to-user communications

The requirements for ubiquitous and highly reliable wireless services, combined with the low utilization of licensed spectrum, call for flexible and efficient spectrum management schemes. To this end, a lot of attention is paid in the literature on allowing secondary-external users to opportunistically access the licensed spectrum. In parallel to these efforts, the question is whether the licensed users could further improve their own spectrum utilization. In this paper, we focus on increasing the spatial spectrum utilization of an infrastructure-based wireless system by adding autonomous functionality to the primary (system) users. An opportunistic operation mode for the uplink (UL) period, totally transparent to the base station (BS) of the system, is introduced. Users operating in this mode identify spatial spectrum UL opportunities by interpreting BS broadcast messages, and exploit these opportunities by establishing direct connections. It is shown that multiple direct connections can take place in parallel with a single standard UL transmission. Moreover, significant additional throughput is achieved, and in most of the cases, the energy consumption for the direct connections is lower than that of the conventional ones (using the standard mode). © 2012 Springer Science+Business Media, LLC

Spatial spectrum reuse for opportunistic spectrum access in infrastructure-based systems

Opportunistic spectrum access (OSA) receives a constantly growing interest due to its potential to mitigate spectrum scarcity and meet the increasing communication needs of mobile users. OSA refers to identifying and exploiting spatiotemporal unused portions of licensed spectrum to allow communication among unlicensed-secondary users (SUs) without adverse impact to the licensees (primary users - PUs). Key parameters in OSA are the spectrum opportunities detection method used by the SUs, and the interference level perceived by the PUs. A spatial spectrum reuse framework is proposed, where broadcast messages of an infrastructure-based primary system are exploited and combined with location-aware methods to detect spectrum opportunities and establish interference-free secondary links. The study of secondary link establishment probabilities revealed a spectrum reuse of up to 25% for omni-directional and up to 90% for directional antennas. Moreover, increased throughput is achieved in both cases, with directional antennas attaining significantly better performance. © 2012 Springer Science+Business Media, LLC

Enabling device discovery transmissions in LTE networks with fractional frequency reuse

The major challenge in device-to-device (D2D) communications is the device discovery problem, i.e., the problem of meeting the communication peers in time, frequency and space. This requires frequent transmission of discovery signals, consuming expensive and scarce radio resources. To mitigate this consumption, we propose a coordination scheme that reuses uplink (UL) spectrum opportunities under a “blind” spatial spectrum reuse approach. Based on the low transmission demands of the discovery transmissions (low range and power, limited quality requirements, etc.), the scheme enables a number of discovery transmissions without continuously gathering and processing the actual interferences in the network. The focus is on a long term evolution (LTE) network that adopts the fractional frequency reuse (FFR) inter-cell interference coordination technique. In this case, the “blind” spatial spectrum reuse approach is endorsed by the spatial constraints provided by the FFR technique to the UL cellular transmissions (each cell is divided into the cell-center and cell-edge areas, while different spectrum portion is allocated to each area). The proposed scheme introduces a D2D coordinator that exploits spatial distribution analysis and approximations for the wireless environment to adjust the number of the underlay discovery transmissions, and hence, control the introduced interferences. Evaluation results show that the proposed scheme can enable an adequate number of discovery transmissions, with limited and controlled impact on the cellular UL transmissions. © 2015 Elsevier B.V

Alleviating control channel interference in femto-overlaid LTE-advanced networks

Long Term Evolution - Advanced (LTEAdvanced) is a prominent cellular network technology designed to meet the International Mobile Telecommunications - Advanced (IMTAdvanced) requirements for enhanced wireless communications, offering high data rates under an all-Internet Protocol (IP) packet network. The dominant supporter of this effort is the significant improvement in spatial spectrum utilization and indoor coverage expected to be achieved through the penetration of femtocells inside the conventional macrocell areas. However, taking into account that femtocells will spatially reuse the spectrum assigned to macrocells in an unplanned deployment manner, the mitigation of the generated interferences becomes a major challenge. The problem is more severe in the case of closed subscriber group (CSG) femtocells, which serve only a limited set of subscribed users, and interfere with both data and control channels of non-subscribed users. Since deteriorated control channels can lead victim users to radio link or access failure, this article studies the problem of control channel interference in LTE-Advanced networks overlaid by CSG femtocells. Focusing on the downlink interference perceived by macrocell users, a categorization and a performance comparison of the fundamental and emerging control channel interference management schemes are provided. © 2013 IEEE