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Investigation of White Rabbit based Frequency Synchronisation for Distributed MIMO Testbed

von Bergen, Jonathan LU and Lindholm, Hugo (2026) EITM01 20261
Department of Electrical and Information Technology
Abstract
The demand for better networks and faster speeds within telecommunications
has been an ever-growing ambition for the last decade. A promising candidate
for dealing with this demand is distributed multiple-input multiple-output (D-
MIMO) systems that combine large-scale antenna arrays and decentralized node
architectures. However, evaluating the possibilities and limitations of such system
requires real-time testbeds.
This thesis investigates White Rabbit as a potential alternative for synchro-
nization in the Lund University Large Intelligent Surface (LuLIS) testbed. The
testbed is a scalable field programmable gate array (FPGA) based testbed with
16 distributed AMD Zynq UltraScale+ ZCU216 nodes that can operate up to 256
... (More)
The demand for better networks and faster speeds within telecommunications
has been an ever-growing ambition for the last decade. A promising candidate
for dealing with this demand is distributed multiple-input multiple-output (D-
MIMO) systems that combine large-scale antenna arrays and decentralized node
architectures. However, evaluating the possibilities and limitations of such system
requires real-time testbeds.
This thesis investigates White Rabbit as a potential alternative for synchro-
nization in the Lund University Large Intelligent Surface (LuLIS) testbed. The
testbed is a scalable field programmable gate array (FPGA) based testbed with
16 distributed AMD Zynq UltraScale+ ZCU216 nodes that can operate up to 256
antennas. The testbed currently achieves frequency synchronization by distribut-
ing an external reference clock over coaxial cables. Although effective over short
distances, this becomes increasingly difficult as the node separation grows. An
alternative is White Rabbit, which is an open-source synchronization technology
that achieves sub-nanosecond time synchronization via fiber-optic communication
over large distances.
A White Rabbit node was developed and integrated on the AMD Zynq Ultra-
Scale+ ZCU216 evaluation board. The implemented design is evaluated in terms
of synchronization accuracy and frequency stability. The results shows that White
Rabbits presents a highly stable frequency stability, while remaining within the
cyclic prefix. Therefore, posing as a scalable and viable solution for replacing
traditional coaxial cables in a distributed wireless communication system. (Less)
Popular Abstract
Imagine an orchestra, where the musicians are scattered across an entire city. For
the orchestra to sound good, each musician has to start at the same beat and have
the correct tempo. Even a small delay would impair the performance.
This challenge is similarly faced by future wireless networks. Researchers are
developing a system where many antennas corporate to send and receive radio
signals. Instead of gathering all antennas at a stationary point, they can be dis-
tributed across buildings, streets and public spaces while still functioning as one
coordinated system. This technology, called distributed multiple-input multiple-
output (DMIMO), could increase network capacity and improve coverage.
The difficulty is keeping all... (More)
Imagine an orchestra, where the musicians are scattered across an entire city. For
the orchestra to sound good, each musician has to start at the same beat and have
the correct tempo. Even a small delay would impair the performance.
This challenge is similarly faced by future wireless networks. Researchers are
developing a system where many antennas corporate to send and receive radio
signals. Instead of gathering all antennas at a stationary point, they can be dis-
tributed across buildings, streets and public spaces while still functioning as one
coordinated system. This technology, called distributed multiple-input multiple-
output (DMIMO), could increase network capacity and improve coverage.
The difficulty is keeping all antennas operating at the same pace and agree on
exactly when to transmit and receive signals, much like the musicians following
the same tempo and starting on the same beat. However, the precision required
for these systems is so high that a measured difference in billions of a second would
impact the performance.
Today, many researchers solve this problem by distributing a reference signal
through a dedicated cable. While this is proven effective in small area it can be
increasingly difficult as the system grows larger and antennas are being placed
further apart.
This thesis investigates whether a technology developed by CERN called White
Rabbit could provide a better solution. White Rabbit was originally developed
for the Large Hadron Collider where scientific instruments must be synchronized
with high precision over large distances.
The results show that White Rabbit can provide the necessary synchronization
accuracy while offering greater flexibility and scalability than traditional cable-
based solutions. (Less)
Please use this url to cite or link to this publication:
author
von Bergen, Jonathan LU and Lindholm, Hugo
supervisor
organization
alternative title
Undersökning av White Rabbit för frekvenssynkronisering i en distribuerad MIMO-testbädd
course
EITM01 20261
year
type
H2 - Master's Degree (Two Years)
subject
keywords
D-MIMO, MIMO, 6G, Synchronization, Frequency synchronization, White Rabbit, DMTD, Dual Mixer Time Difference, PTP, Precision Time Protocol
report number
LU/LTH-EIT 2026-1179
language
English
id
9242972
date added to LUP
2026-06-29 13:06:52
date last changed
2026-06-29 13:06:52
@misc{9242972,
  abstract     = {{The demand for better networks and faster speeds within telecommunications
has been an ever-growing ambition for the last decade. A promising candidate
for dealing with this demand is distributed multiple-input multiple-output (D-
MIMO) systems that combine large-scale antenna arrays and decentralized node
architectures. However, evaluating the possibilities and limitations of such system
requires real-time testbeds.
This thesis investigates White Rabbit as a potential alternative for synchro-
nization in the Lund University Large Intelligent Surface (LuLIS) testbed. The
testbed is a scalable field programmable gate array (FPGA) based testbed with
16 distributed AMD Zynq UltraScale+ ZCU216 nodes that can operate up to 256
antennas. The testbed currently achieves frequency synchronization by distribut-
ing an external reference clock over coaxial cables. Although effective over short
distances, this becomes increasingly difficult as the node separation grows. An
alternative is White Rabbit, which is an open-source synchronization technology
that achieves sub-nanosecond time synchronization via fiber-optic communication
over large distances.
A White Rabbit node was developed and integrated on the AMD Zynq Ultra-
Scale+ ZCU216 evaluation board. The implemented design is evaluated in terms
of synchronization accuracy and frequency stability. The results shows that White
Rabbits presents a highly stable frequency stability, while remaining within the
cyclic prefix. Therefore, posing as a scalable and viable solution for replacing
traditional coaxial cables in a distributed wireless communication system.}},
  author       = {{von Bergen, Jonathan and Lindholm, Hugo}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Investigation of White Rabbit based Frequency Synchronisation for Distributed MIMO Testbed}},
  year         = {{2026}},
}