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Master Thesis: L4S in 5G networks

Job Description

Date: Nov 8, 2019

Ericsson Research

Ericsson Research develops new communication solutions and standards. The organization has the responsibility to provide Ericsson with world-class system concepts, technology innovations, and methodologies. The rapidly increasing demands for mobile broadband access in combination with needs for new technology and solutions for the digitalization of industries and societies creates challenging and exciting opportunities for our organization. Building on our experience from real network operations, profound knowledge about existing standards, and forward-looking research, we invent and master advanced concepts and solutions that shape today and tomorrow´s mobile radio communication.


L4S (Low Latency Low Loss Scalable throughput) is a technology to achieve low end-to-end delay for internet applications and leverages on ECN (Explicit Congestion Notification), implemented in network nodes such as internet routers and radio base stations.
In short, L4S integrates fine granularity congestion indication both in congested nodes along a transmission path between a sender and receiver and congestion control in the endpoints. Network nodes indicates congestion by setting the ECN bits in the IP headers. The receiver detects these marked packets and instructs the sender to reduce the sending rate to avoid more congestion. The congestion control makes it possible to achieve low end-to-end delay for applications with high demands on both peak bitrate and delay, examples are gaming applications, XR and remote control of drones and cars.
The problem is that internet infrastructure today is rather complex, and that internet traffic carried between a sender and receiver is often carried over various tunnels, in which case the ECN bits in the IP header for the end-to-end traffic is obscured by tunneling protocols. Examples are; GTP tunnels that are implemented between packet gateways and radio base stations, a.k.a. gNB, split architecture tunneling that can be applied in the 3GPP radio protocol stack and integrated access backhaul (IAB). The challenge is to ensure that the end-to-end flows are L4S capable and that possible congestion, experienced in various parts of the network, is seen by the end-to-end flow.

Thesis Description

The goal of the master thesis is to take a holistic view over the 5G protocol stack and the transmission between the packet gateways (PGW, ePG) and the mobile terminal (UE), identify how L4S marking is done in various network nodes and how these markings are carried over from the tunnel interfaces to the end-to-end IP flow. The initial work will be theoretical nature and literature study of the different interfaces in a 5G protocol stack. The work also comprises implementation and evaluation of end-to-end L4S capabilities for defined scenarios using an existing 5G network system simulator.
The thesis will be concluded with a result presentation for the Ericsson Research team.


  • The successful applicant will be a self-motivated, IP oriented MSc student or equivalent with an interest in algorithm development and testing
  • The work is research oriented, so ability to learn quickly, work independently and identify problems and solutions is necessary
  • You should be an MSc student, preferably in engineering physics, electrical engineering, computer science or similar
  • Courses in wireless communication theory and signal processing as well as experiences of communication systems and internet protocols are considered valuable merits
  • Existing Java and Matlab based system simulator will be modified and used for tests and evaluations, which means that the thesis work requires good Java and Matlab programming skills.

Extent: 1 student, 30hp
Work location: Luleå
Preferred Starting Date: Q1 2020, please enclose a transcript in your application and state when you can start.
Last Day to Apply: 24th of November
Contact: Mats Nordberg, +46703008001, or Agnes Westerberg,



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Primary country and city: Sweden (SE) || || Luleå || Stud&YP

Req ID: 304491