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Coordinated control and spectrum management for 5G heterogeneous radio access networks

Periodic Reporting for period 2 - COHERENT (Coordinated control and spectrum management for 5G heterogeneous radio access networks)

Reporting period: 2016-07-01 to 2018-03-31

The COHERENT project is one of H2020 5G PPP projects funded by European Commission. It aims to research and develop a unified control and coordination framework for 5G heterogeneous radio access networks. The project focuses on three innovations in control and coordination of 5G networks: i) Software defined networking for radio access networks, to enable a scalable and flexible control and coordination framework for complex resource coordination and spectrum management in 5G networks; ii) Efficient radio resource modelling and management in programmable radio access networks, with well-defined control interfaces, protocols and application programming interfaces (API) to greatly simplify the management of heterogeneous mobile networks, to be verified by various 5G use cases; iii) Flexible spectrum management, based on the awareness of spectrum usage through the COHERENT control framework, to support different spectrum access schemes, including but not limited to, Licensed Shared Access, License Assisted Access, and flexible duplex in 5G radio access networks. COHERENT works closely with other 5G PPP projects to meet the European 5G ambition defined by 5G PPP technical, societal and business related key performance indicators (KPI). The applicability and benefits of the COHERENT approach will be demonstrated by a true proof-of-concept prototype.
During the entire project duration, the project has made the significant achievements toward the project objectives. Based on the architecture developed in Deliverable D2.2 the project worked on the foundation of software-defined networking (SDN) for radio access networks (RAN), refined the network abstractions and network graphs, and developed 16 applications using the network abstractions and network graphs built in Deliverable D3.1. The results of the applications are included in Deliverable D3.2. It cover the important topics in 5G RAN, including massive multi-input multi-output (MIMO), load balancing, multi-connectivity, multicast, relay, and the use of 5G with Private Mobile Radio (PMR).

Based on the outcomes on network abstractions, and the specific LTE and WiFi testbed platforms utilized in the project, the project has developed the COHERENT software development kit (SDK) (Deliverable D2.4) for both LTE and WiFi systems. The COHERENT SDK explores the separation of the control plane and data plane in 5G RAN and provides the northbound interface and APIs for both RAT-dependent and RAT-agnostic control applications. The SDK and COHERENT testbed platform are public available through the open source code repositories.

The project spent significant efforts on the flexible spectrum management. Based on the current development on 5G spectrum, the project developed a spectrum management framework, which extended low-layer abstraction developed in Deliverable D3.1 into the spectrum management and proposed the annotated policy graph for spectrum sharing. The project studied 8 research topics regarding spectrum sharing, which cover inter-tier resource sharing, spectrum sharing for multi-tenant RAN, coexistence of Long Term Evolution (LTE) and WiFi in shared bands, location-based spectrum sharing, and flexible duplexing. The project has conducted two spectrum trials in two cities, which showed the potential of spectrum sharing for 5G. The results of the flexible duplexing study was presented in ECC PT1 meeting. Based on the project results, the project contributed to 5G PPP Spectrum Working Group (WG) on spectrum sharing topics.

The project developed algorithms for programmable RANs. The algorithms cover the network resilience for control plane protection, radio resource allocation, RAN slicing, traffic steering, and flexible functional splits. The outcomes are included in Deliverable D5.2. These algorithms are based on the COHERENT architecture concept. Several algorithms have been implemented in the testbed and their performances were evaluated.

The project has built 6 proof of concept (PoC) based on 3 testbed platforms and the COHERENT SDK. These PoC demonstrated the unified control and coordination concept, the programmability in RAN control, the flexible spectrum management, and the support for distributed antenna systems. The project demos have been shown in EuCNC, Global 5G Event, Flex5GWare event, and CROWNCOM demo event. The outcomes of the demo work are included in Deliverable D6.2.

During the whole project period, COHERENT has submitted 86 standardization contributions to 3GPP, ETSI BRAN and ECC PT1, published 21 journal papers, 58 conference and workshop papers, organized 7 workshops, delivered 4 technical tutorials, 9 demos in different events, 16 presentations in industry forums and company events, and participated in 3 5G panel. The project partners has submitted 6 patent applications and 2 PCT applications. It is worth highlighting that ETSI BRAN TR 301 494 is initiated by COHERENT partners and the content is mainly based on the COHERENT results.

The project has has been actively participating in 5 5G PPP WG: Pre-Std, Spectrum, 5G Architecture, Software Network, Network Management. The project has provided significant contributions to the 5G PPP Architecture white papers.
COHERENT addresses the 5G PPP KPI on 1000 times higher wireless area capacity and more varied service capabilities compared to 2010 and investigates new RAN architecture, spectrum management, network slicing and softwarization at RAN for flexible, scalable, cost efficient control and coordination solutions for 5G mobile networks.

The flexible RAN architecture proposed by COHERENT introduces new logical centralized control and coordination network entity, RAN virtualization, flexible function split, and SDN based control principles into LTE/LTE-A, WiFi and emerging 5G networks. The concept of the network graph, which reflects the low layer reality of RAN by abstracted network views, is introduced to support radio resource virtualization and enable scalable fine-grain coordination among RAN entities for higher wireless area capacity.

New radio resource management methods based on the new architecture are developed to support fine-grain radio resource allocation and node cooperation cross the cellular cells’ boundary. The improved coordination methods are capable of improving the performance of coordinated multi-point transmission and reception (CoMP), multi-connectivity and other new cooperative functions in RAN.

COHERENT has proposed a flexible spectrum management framework for heterogeneous RAN therefore not only conventional spectrum management methods but also new spectrum access schemes, for instance, license shared access (LSA), could be integrated to provide more spectrum opportunities to end users.

The COHERENT partners have been actively cooperating with other 5G PPP projects through 5G PPP working groups and adopting diverse technical inputs into the project work. Led by the partner 4GCelleX, the partners of COHERENT have actively participating in standardization and regulation work in 3GPP. The COHERENT partners have submitted 86 standardization contributions to 3GPP, ETSI BRAN and ECC PT1.
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