A 5G mobile network has evolved from a cell centric radio access network to a user centric one. A user-centric no-cell (UCNC) framework has been proposed, which enables physical layer coordination over a large number of transmission and reception points for each mobile user to always experience cell-center-like communications. This paper presents some key technologies in the UCNC framework. The focus is on proof of concept of UL grant-free transmissions in the UCNC architecture. Massive connectivity supporting a huge number of devices is one of the three important scenarios in 5G networks. The challenges to support massive connectivity lie in the cost of signaling overhead and transmission latency. An uplink grant-free transmission based on sparse code multiple access (SCMA) design is proposed. The proposed scheme can provide different levels of overloading to efficiently meet the massive connectivity requirements. Grant-free transmission conducted in RRC connected state can reduce signaling overhead, while in energy conserved operation (ECO) state, it can significantly reduce the user plane transmission latency. Extensive laboratory testing has been conducted in a collaborative project of Huawei and Telefonica to verify the performance matrices. Taking LTE as a baseline for comparison purposes, it is shown that the signaling overhead by using uplink grant-free transmission can be reduced by around 80% and the user plane transmission latency in ECO state can be reduced by around 93%. Moreover, massive connectivity is efficiently supported with the SCMA scheme that yields around 230% gain over OFDMA in terms of supported active users.

This paper focuses on the practical implementation of a Cloud-RAN architecture in the context of future 5G systems, with particular emphasis on different aspects of the functional split between the cloud platform and the radio access points. First, we provide a comprehensive overview of implementation aspects and how different hardware options impact the implementation of RAN functionality. We further discuss a virtualized infrastructure which may have a significant impact on how algorithms are implemented, how they interact with each other, and how they can be scaled within the RAN. We also analyze implementation constraints to be considered to provide backwards compatibility with 3GPP LTE; such constraints on the computing platforms result from the RAN requirements in terms of latency and throughput. Finally, the level of flexibility achievable by the proposed architecture is described from a practical point of view.

The new generations of cellular technologies and the current trend towards small cells or femtocells, will offer an improved spectral efficiency per area, but they also offer an opportunity to improve the energy efficiency, measured as the power consumption needed to provide a certain throughput in a given area. In this paper, two network performance indicators, aggregated throughput and energy efficiency, have been analyzed and compared in two network architectures; a traditional deployment based on outdoor macro base stations, for the provision of outdoor and indoor coverage, and a deployment where some of the indoor traffic is supported by femtocells. Performance simulations and energy calculations have shown that the introduction of a femtocell layer, complementing the macrocell layer is a great leap forward in system performance and energy efficiency, when compared with current indoor coverage based on outdoor macro and micro base stations. Additionally, this paper present a study on how much could be reduced the mobile network energy requirements of macrocell deployments in high density urban deployments, in low traffic conditions, based on the application of two Self Organizing Networks (SON) techniques for energy saving, selective disconnection and power reduction of eNodeBs and HeNBs.

An overview of the main characteristics of the real time emulator (RTE) to be implemented in the context of the Rainbow project is presented. First of all, the RTE functional description is shown in order to justify the rationality of the envisaged approach. Next, a description of the emulation and simulation models used in the RTE for CoDiT is provided. Off-line simulation models are used to estimate the parameters to be employed in the emulation of the different scenarios, while the use of emulation models allows for a reduction of the RTE complexity.