This document summarizes the EU H2020 5G-PPP Project 5G-Xhaul, which aims to develop a converged optical and wireless network to support 5G networks. The project uses a software-defined network architecture with a cognitive control plane to dynamically configure the transport network. The testbed will deploy a dense layer of small cells in Bristol connected by both wireless and optical fronthaul/backhaul networks. It will validate the end-to-end performance of the 5G-Xhaul solution in a realistic 5G network environment.

1. Funding/
Acknowledgment/ Partners/
EU H2020 5G-PPP Project 5G-Xhaul: Dynamically
Reconfigurable Optical-Wireless Backhaul/Fronthaul
with Cognitive Control Plane for Small Cells and Cloud-RANs
Points of Contact: Prof. Dr.-Ing. Eckhard Grass (Project Coordinator), grass@ihp-microelectronics.com
Prof. Mark Beach (Bristol-CSN Lead), M.A.Beach@bristol.ac.uk
Key Technologies
Final Test-bed Integration
Introduction
 Research Aim: A converged optical and wireless network solution, relying
on flexible infrastructure able to support Backhaul (BH) and Fronthaul
(FH) networks to cope with future challenges imposed by 5G Random
Access Networks (RANs) [1]
Key concepts:
 Programmable optical/wireless network elements, enabling tight control
of transport network.
 Software Defined Network (SDN) architecture where control plane
decoupled from individual transport network elements & logically
centralised to achieve a holistic view of network.
 Cognitive control plane, able to measure/forecast spatio-temporal
demand variations and configure transport network elements.
Optical Technologies
 Time-Shared Optical Network (TSON)
 Wavelength Division Multiplexing-Passive Optical Networks (WDM-PON)
Introduction and Motivation
Bristol is Open (BIO)
 Four active nodes in the network core
 TSON nodes as interfaces between standard L2 & time/spectrum
sliceable optical network
 SDN control over network setup & operations
TheBrooklyn5GSummitApril20-22,2016
Figure 1 – 5G-XHaul Network Deployment
Wireless Technologies
 Point-to-Multipoint (P2MP) mmWave (60 GHz)
 Sub-6 GHz connectivity for users, backhaul and fronthaul
Deployment Overview
Data Plane
 Dense layer of small cells located 50-200m apart (complemented by a
layer of macro cells located 500m apart)
a. wirelessly backhauled to macro cell sites (mm-Wave + sub 6 GHz) or
b. directly connected to central office node through WDM-PON
 Remote Radio Heads (RRHs) connected to BaseBand Unit (BBU) pools via
high bandwidth transport links (FH)
- stringent delay & synchronisation requirements
Control Plane
 Network slicing to support heterogeneous access (2G/3G/4G/5G, Wi-Fi,
FH/BH).
 SDN based control plane across multiple domains (i.e. optical, wireless,
ethernet transport), by a logically centralised controller.
 Network Function Virtualisation (NFV) to execute network functions on
commodity hardware.
 TSON with advanced BH capabilities (dynamic connectivity with fine
bandwidth granularity)
- supports sub-wavelegth switching, flexible frame lengths (64ns-25.6µs),
variable bit rates (30 Mbps-6Gbps)
Millimeter Wave BH (Bristol)
Challenges
 Sufficient operating link margin
 Sensitivity to blockage
 Interference management/spatial reuse
 Appropriate hardware
Signal Processing
 Analog beamforming (based on IEEE 802.11ad)
 Hybrid beamforming based on
- phase shifters
- switches
 Low resolution/1-bit Analog-to-Digital Conversion (ADC)
- low cost/complexity/power consumption
 Channel Estimation
- Compressed Sensing
- Echoing (ping-pong algorithm)
References:
[1] A. Tzanakaki et al., ”5G Infrastructures Supporting End-User and Operational Services: The 5G-
XHaul Architectural Perspective”, Accepted to IEEE ICC 2016, Workshop on 5G Architecture, Kuala
Lumpur, Malaysia, May 2016.
[2] http://www.bristolisopen.com
Performance Evaluation (Bristol)
Anite F8 emulators
 Use of spatial temporal channel data from measurements/ray tracing for
- array design & evaluation
- hardware in the loop performance evaluation (8x160 MHz channels can be
stacked in frequency domain – 1.28 GHz bandwidth)
Keysight technologies based instrumentation
 Waveform generation/analysis
 Up/Down-conversion
 Mm-Wave measurements at 60 GHz (70 & 80 GHz availability)
National Instruments based Massive MIMO test-bed
 64 USRPs (128 radios), 15 dBm tx output power per radio
 LTE frame structure, Time Division Duplex (TDD)
 Sub-6 GHz at 3.51 GHz
 200 KHz pilot spacing, every user at 20MHz
Final Objective
 Deploy an open & programmable 5G communication service platform in
the centre of Bristol.
 Validate the performance (e2e) of the 5G-XHaul solution in a realistic 5G
network environment
Figure 2 – BIO city connectivity [2]