NOMA | ESA CSC

Ground Segment

Status

Ongoing
Status date

2024-03-22
Activity Code

3C.024

Objectives

The objective of the activity is to work on non-orthogonal multiple access (NOMA) techniques for 2 different use cases:

HEO use case
- Bent-pipe satellite
- IoT SS-CDMA system sharing transponder frequency band with VSATs
LEO use case
- IoT SS-CDMA system using WRC-27 new IoT candidate frequencies within the 1.4-2.1 GHz range
- On-board processing or IoT gateway on the ground
- Using Successive Interference Cancellation to improve throughput and availability, especially for IoT terminals at the edge of the coverage

The main target for the HEO use case is to remove the need to allocate dedicated return link bandwidth for the IoT SS-CDMA system and be able to coexists with regular VSAT traffic in a common frequency band. The main target for the LEO use case is to increase the throughput and probability for successful transmission for IoT terminals using Successive Interference Cancellation techniques. The work in this activity is based on using the IoT SS-CDMA air interface and the testbed that was developed in the ALISA ARTES AT activity as a starting point.

Challenges

The main challenges in the project are:

High Doppler variations from satellites in non-geostationary orbits are difficult to track by the demodulator in the presence of phase for low symbol rates at very low signal-to-noise ratios.
Estimation of channel state parameters.
Processing constraints in the satellites.
Pre-compensation of Doppler from satellites in non-geostationary orbits cannot be done for systems where messages are received by multiple satellites.
Complexity of NOMA algorithms.
Battery/power constraints of IoT terminal.

Benefits

IoT communication over satellite at extremely low signal-to-noise ratios using an uncoordinated, frequency agnostic air interface with the possibility to share bandwidth with VSAT systems and improve throughput at band edges using Successive Interference Cancellation.

Features

Frequency agnostic scalable air interface which can support a wide range of use cases.
Low-complexity and near-capacity approaching error-correcting codes tailored for this air interface.
Support for uncoordinated transmissions from the IoT terminals.
Gateway receiver capable of receiving IoT bursts from multiple terminals in parallel, where the received bursts may overlap in time and frequency.
Gateway receiver design supporting Successive Interference Cancellation (SIC) and cancellation of VSAT traffic.
Novel, scalable, high-performance receiver design running on a powerful software defined radio (SDR) platform able to support very large number of users.
Support for IoT communication over satellite links with extremely low link margins (down to Ec/No below -40 dB).
Support for frequency sharing with VSAT point-to-point systems

System Architecture

The architecture of the verification platform used for development and verification in this project is shown in the block diagram below

diagram

Plan

The duration of the project is 28 months. The following review meetings are planned in the project:

Output 0 Review (O0R) in January 2024
Output 1 Review (O1R) in April 2024
Output 2 Review (O2R) in August 2024
Output 3+4 Review (O3+4R) in January 2025
Final Review (FR) in March 2026

Current status

Kick-off date for the project was October 18, 2023. Ongoing work is defining the system scenario, analysing the system benefits, and defining draft system requirements. In addition, the test plans and procedures are being drafted. The next milestone is the Output 1 Review (O1R), which is also the first milestone, the PDR.