Skip to main content

LUP Student Papers

LUND UNIVERSITY LIBRARIES

True-Time Delay Cancellers for Full-Duplex

Snygg, Vilgot LU and Nilsson, Vejde LU (2024) EITM01 20232
Department of Electrical and Information Technology
Abstract
The concept of simultaneously receiving and transmitting at the same frequency
is known as Full-Duplex (FD). Such a wireless system is a novel technique which
could effectively half the required channel Bandwidth (BW) for the same data
rate. In FD systems, the leakage of the Transmitter (Tx), called Self-Interference
(SI) signal, leaks into the Receiver (Rx) which is a major hardware-related obstacle
for reliable FD operation. Multiple leakage paths exists for the SI signal, such as
direct path (DP) antenna-to-antenna feed through or environment-based multisurface reflection paths (RP). By taking the output of the Tx, introducing delay
and amplitude compensation, then subtracting this signal from the SI signal in the
Rx front end,... (More)
The concept of simultaneously receiving and transmitting at the same frequency
is known as Full-Duplex (FD). Such a wireless system is a novel technique which
could effectively half the required channel Bandwidth (BW) for the same data
rate. In FD systems, the leakage of the Transmitter (Tx), called Self-Interference
(SI) signal, leaks into the Receiver (Rx) which is a major hardware-related obstacle
for reliable FD operation. Multiple leakage paths exists for the SI signal, such as
direct path (DP) antenna-to-antenna feed through or environment-based multisurface reflection paths (RP). By taking the output of the Tx, introducing delay
and amplitude compensation, then subtracting this signal from the SI signal in the
Rx front end, the SI can effectively be canceled in the analog Radio Frequency (RF)
domain. This thesis is investigating how such a SIC circuit, targeting cancellation
in the RF analog domain, could be designed. Large focus is given to True-Time
Delay (TTD) generation, which is a major part of the SIC system. The proposed
RF SIC is a hybrid solution with passive pre-LNA (Low-Noise Amplifier) SIC and
an active post-LNA SIC aimed at an operating frequency of 10 GHz with 100 MHz
of carrier bandwidth. The passive TTD is implemented as a binary weighted
delay chain with cascaded lumped LC transmission line filters for course tuning
and an LR-RL lattice all-pass filter with tunable coupled inductors for fine tuning.
For the active TTD, a Time Interleaved (TI) N-path circuit was used. The passive
TTD achieves a delay range of 62-1661 ps with an estimated rms (Root Mean
Square) cancellation of 18.64 dB over the BW. For the active TI N-path TDD, a
delay range of 22-1772 ps is showcased with an estimated rms cancellation of
19.53 dB over the BW. The TI N-path TTD can be scaled up to achieve longer
delays and branched to generate multiple outputs for cancellation of multipath
reflections with reduced chip-area (Less)
Please use this url to cite or link to this publication:
author
Snygg, Vilgot LU and Nilsson, Vejde LU
supervisor
organization
course
EITM01 20232
year
type
H2 - Master's Degree (Two Years)
subject
report number
LU/LTH-EIT 2024-966
language
English
id
9150005
date added to LUP
2024-04-02 16:35:31
date last changed
2024-04-02 16:35:31
@misc{9150005,
  abstract     = {{The concept of simultaneously receiving and transmitting at the same frequency
is known as Full-Duplex (FD). Such a wireless system is a novel technique which
could effectively half the required channel Bandwidth (BW) for the same data
rate. In FD systems, the leakage of the Transmitter (Tx), called Self-Interference
(SI) signal, leaks into the Receiver (Rx) which is a major hardware-related obstacle
for reliable FD operation. Multiple leakage paths exists for the SI signal, such as
direct path (DP) antenna-to-antenna feed through or environment-based multisurface reflection paths (RP). By taking the output of the Tx, introducing delay
and amplitude compensation, then subtracting this signal from the SI signal in the
Rx front end, the SI can effectively be canceled in the analog Radio Frequency (RF)
domain. This thesis is investigating how such a SIC circuit, targeting cancellation
in the RF analog domain, could be designed. Large focus is given to True-Time
Delay (TTD) generation, which is a major part of the SIC system. The proposed
RF SIC is a hybrid solution with passive pre-LNA (Low-Noise Amplifier) SIC and
an active post-LNA SIC aimed at an operating frequency of 10 GHz with 100 MHz
of carrier bandwidth. The passive TTD is implemented as a binary weighted
delay chain with cascaded lumped LC transmission line filters for course tuning
and an LR-RL lattice all-pass filter with tunable coupled inductors for fine tuning.
For the active TTD, a Time Interleaved (TI) N-path circuit was used. The passive
TTD achieves a delay range of 62-1661 ps with an estimated rms (Root Mean
Square) cancellation of 18.64 dB over the BW. For the active TI N-path TDD, a
delay range of 22-1772 ps is showcased with an estimated rms cancellation of
19.53 dB over the BW. The TI N-path TTD can be scaled up to achieve longer
delays and branched to generate multiple outputs for cancellation of multipath
reflections with reduced chip-area}},
  author       = {{Snygg, Vilgot and Nilsson, Vejde}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{True-Time Delay Cancellers for Full-Duplex}},
  year         = {{2024}},
}