Free Space Optical Backhaul for 5G Networks

Space for 5G

Status

Ongoing
Status date

2024-06-04
Activity Code

3A.192

Objectives

Objectives:

Identify necessary system interfaces, requirements and performance criteria.
Complete simulated bi-directional lasercom satellite backhaul link with realistic optical turbulence effects and gross link loss.
Demonstrate feasibility of lasercom satellite backhaul in the presence of adverse weather with realistic channel effects.
Enable high bandwidth optical links for 5G satellite backhaul to Low Earth Orbit (LEO) satellite constellations.

Challenges

Two key challenges are:

Ensuring the necessary interfaces to 5G network equipment on the ground are defined.
Resilience of the link to atmospheric attenuation and turbulence effects.

These are directly addressed in the project:

The interface risk is directly addressed by creating a demonstration system which is integrated into the simulated 5G network at the 5G Hub.
The project addresses the atmospheric effects by creating a representative channel simulator capable of repeatably simulating gross loss and time dependent (turbulence induced) loss using high speed variable attenuators.

Benefits

The product of this project is a technology demonstrator (start TRL 2; end TRL 3) to prove the feasibility of utilising free space optical communication technology, such as our TERRA-M optical ground station, as an alternative to existing radio spectrum 5G constellation backhaul options. Optical communication provides 100x the data throughput compared to conventional radio technology, without the bandwidth constraints. The project output is an important UK sovereign technology and capability providing high volume data links between terrestrial and non-terrestrial networks..

The next step beyond this demonstration is the development of a system that can be implemented into 5G backhaul architectures, providing further redundancy for the uplink and downlink of data in the event that terrestrial communication methods experience downtime e.g. accidental or deliberate cutting of undersea cables.

Features

This work focuses on utilising COTS (Commercial Off The Shelf) telecom equipment for the optical ground terminal and satellite terminal simulators and then testing the performance of these in representative, simulated, channel conditions.

System Architecture

There are three key aspects:

Satellite terminal simulator
1. Reception of data from Optical Ground Terminal
  1. Reception of optical signal
  2. Conversion of optical signal to electrical signal
  3. Decoding of user data
  4. Relay of user data via ethernet interface
2. Transmission of data to Optical Ground Terminal
  1. Reception of user data via ethernet interface
  2. Encoding of user data
  3. Conversion of electrical signal to optical signal
  4. Transmission of optical signal to Optical Ground Terminal
Channel simulator
1. Uplink signal channel simulation
  1. Attenuation of signal for gross channel loss
  2. Temporal attenuation of signal to simulate optical turbulence effects
2. Downlink signal channel simulation
  1. Attenuation of signal for channel loss
  2. Temporal attenuation of signal to simulate optical turbulence effects
Optical ground terminal simulator
1. Reception of data from Satellite Terminal
  1. Reception of optical signal
  2. Conversion of optical signal to electrical signal
  3. Decoding of data
  4. Relay of data via ethernet interface
2. Transmission of data to Satellite Terminal
  1. Reception of data via ethernet interface
  2. Encoding of data
  3. Conversion of electrical signal to optical signal
  4. Transmission of optical signal to satellite terminal

Plan

There are 4 main development and demonstration activities, alongside project management and systems engineering activities that run throughout all phases:

There are three key milestones: Kick-Off, Mid-Term Review (during the AIT phase), and a Final Review following the conclusion of the demonstration, intended to take place in summer 2024.

Simulator design
Assembly, integration and testing phase
- Channel simulator
- Terminal simulator
Representative channel testing
Demonstration of optical backhaul technology at ESA’s 5G Hub

Current status

The project is currently in the AIT phase and has passed mid-term review. Both simulators have concluded design and development work is ongoing on the turbulence model (for the channel simulator) and assembling servers to represent the ground and space terminals. Testing is anticipated for July 2024.