Carrier Aggregation Demonstrator for Satellite Communication Systems

Carrier aggregation (CA) is an integral part of current terrestrial networks. Its ability to enhance the peak data rate, for efficiently utilizing the limited spectrum resources and satisfying the demand for data-hungry applications, have drawn a significant attention. While the application CA in terrestrial scenarios has been widely considered, its application in satellite communications is still a rather unexplored area. Given the benefits of CA in terrestrial wireless environment, SIGCOM group has developed a SW-based tool to investigate the applicability of the CA concept into the satellite domain.

  

Carrier Aggregation Benefits

In the framework of satellite networks, CA has huge potentials in scenarios where a user can meet its demand from multiple carriers, possibly occupying spectrum in different transponders, and hence, offering possibility to exploit the underutilized resources. Furthermore, the ubiquity of satellite systems can provide services for large-scale environments over vast geographical regions, which makes satisfying the heterogeneous spatially distributed demands through different beams a challenging task. Therefore, CA has a promising potential in enabling the flexibility and adaptability to accommodate various types of traffic.

 

System Architecture:

Carrier Aggregation (CA) is implemented by means of three blocks:

  1. At the Gateway side, a Multiuser Aggregation and Access Control (MAAC) block represents the main intelligence of the system that is in charge of designing the carrier allocation strategy for all the user terminals in the system as well as the multiplexing of each carrier.
  2. A load balancing and PDU scheduler module that is responsible for applying the decisions of the MAAC by distributing the incoming PDUs across the available carriers. The load balancing and PDU scheduler block has to be carefully designed such that the PDUs are distributed across the selected carriers based on the link capacities so that the PDU disordering is minimized at the receiver side.
  3. At the receiver side, traffic-merging block that takes the PDU streams of the aggregated carriers as input and converts them into a single stream of received PDUs.

 

CADSAT demonstrator is divided into two different SW tools:  

 

Name in the document

Short description

Goal

CA technique validation

CADSAT SW Tool 1

Single User implementing CA over 2 carriers. Presence of other users will be artificially generated with XFECFRAME zero-padding.

Test the functionality of two of the main critical blocks introduced by CA, namely the “Load balancing and PDU scheduler” block at GW side and the “Traffic merging” procedure at the receiver side.

CA end-to-end system demonstration

CADSAT SW Tool 2

System level simulation consisting of multiple users located in different beams and with different demands

Test the functionality of the MAAC and demonstrate that a CA-enabled system is able to satisfy the UTs demand.

 

Figure (1) Overview of the CA system architecture

 

 

CADSAT SW TOOL 1

The CADSAT SW Tool 1 emulates the load balancing and PDU scheduler functionalities of a single user performing CA over two different carriers.

This simulator entails three operational modes:

  1. Carrier Aggregation (CA)
  2. Channel Bonding (CB)
  3. Single Carrier (No CA/CB)

Three options are available with regard to the PDU scheduling over the aggregated/bonded carriers:

  1. Round Robin
  2. Load Balancing
  3. Adaptive Load Balancing

Please note that when single carrier (No CA/CB) mode is selected this function will be inactive because there is no need for a scheduler when all the PDUs are transmitted through the same carrier.

The CADSAT SW Tool 1 provides as output:

  1. The sequence of received PDUs, indicating which PDU was sent via which carrier.
  2. Missing and Out-of-order PDUs at the receiver side
  3. Peak Data Rate
  4. Processing Time
  5. TCP statistics

Figure (2) CADSAT SW Tool 1.

CADSAT SW TOOL 2

The CADSAT SW Tool 2 emulates a multi-beam GEO system serving multiple user terminals. In particular, the tool provides the user-carrier assignment targeting a fair demand-matching objective at a user level.

Input parameters are:

  1. Number of Beams
  2. Number of Users
  3. Traffic Demand Distribution (relation between high-demand users and non-high demand users)
  4. Spatial User Distribution (number of users per beam)
  5. Max. Number of carriers that can be aggregated
  6. Bandwidth of the carriers 

Outputs are:

  1. Unmet system capacity
  2. Unused system capacity
  3. Total supplied capacity
  4. Number of users doing CA
  5. Statistics of user demand-matching metrics

 

Figure (3) CADSAT SW Tool 2.

 

References:

[1]   M. Kibria, E. Lagunas, N. Maturo, D. Spano, H. Al-Hraishawi, and S. Chatzinotas, “Carrier Aggregation in Multi-beam High Throughput Satellite Systems,” in IEEE Global Commun. Conf., Dec. 2019.

[2]   H. Al-Hraishawi, N. Maturo, E. Lagunas, and S. Chatzinotas, “Perceptive Packet Scheduling for Carrier Aggregation in Satellite Communication Systems,” in Proc. IEEE Int. Conf on Commun. (ICC), Dublin, Ireland, Jun. 2020, pp. 1–6.

[3]   M. G. Kibria, E. Launas, N. Maturo, H. Al-Hraishawi, S. Chatzinotas, “Carrier Aggregation in Satellite Communications: Impact and Performance Study”, under revision IEEE Open Journal of the Communications Society, 2020.

[4]   H. Al-Hraishawi, N. Maturo, E. Lagunas, and S. Chatzinotas, “Scheduling Design and Performance Analysis of Carrier Aggregation in Satellite Communication Systems.” under revision IEEE Trans. Commun., 2020.

 

Acknowledgement:

This work has received funding from the European Space Agency (ESA) funded activity CADSAT: Carrier Aggregation in Satellite Communication Networks. The views of the SIGCOM team do not necessarily reflect the views of ESA. (Web: https://artes.esa.int/projects/cadsat)

 

Research Team

  • Dr Symeon Chatzinotas (SnT) – Project Manager
  • Dr Eva Lagunas (SnT) – Technical Contact Point
  • Dr Hayder Al-Hraishawi (SnT)
  • Dr Nicola Maturo (SnT)
  • Dr Mirza Kibria (SnT)