Full Duplex for 5G Handsets
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Full Duplex poster as presented at the 5G Brooklyn Summit
![Aim: To bring Full-Duplex transceiver technology from the drawing board to the handset.
A low cost, small form factor duplexing solution based on electrical balance isolation.
Simulated and Measured Performance
Division Free Duplex for 5G Handsets
Leo Laughlin, Chunqing Zhang, Mark Beach,
Kevin Morris, and John Haine
email: M.A.Beach@Bristol.ac.uk
This work is supported by the UK EPSRC under Grant EP/I028153/1, and by u-blox AG, 8800 Thalwil, Switzerland.
Communication Systems
and Networks Group
@BristolCSN
bristol.ac.uk/engineering/research/csn
Bristol Full Duplex Transceiver Architecture
• High isolation achieved when ΓBAL= ΓANT.
• Balancing impedance must be dynamically adapted to track antenna impedance in the
time domain. 2dB Tx insertion loss, 5dB Rx noise figure.
• Suitable for small form factor multiband mobile devices: requires just one antenna, can be
implemented on chip, and can be tuned over wide frequency ranges.
• Isolation bandwidth limited by Frequency domain variation in antenna and balancing
impedances.
Electrical Balance Duplexer
Hybrid can be
implemented
on-chip
+
Active Analogue Cancellation
ΓANT (ω) ΓBAL(ω)
Band limited isolation due to diverging values of antenna
and balancing impedances.
• Residual self-Interference at EB duplexer
receive port
• Residual self Interference reduced by actively
injecting cancellation signal.
• Frequency selective self-interference channel can be
replicated using baseband DSP.
• Cancellation performance limited by EVM of radio
chain.
• Implements LTE like OFDM physical layer.
• Active cancellation subsystem estimates amplitude and phase of residual self-
interference for each subcarrier. (SC spacing = 15kHz).
• Cancellation signal is then generated using Frequency Domain Equalisation
(FDE) on a copy of the transmit signal.
• Results demonstrate wide tuneability. Performance is the same at 900MHz and
1900MHz.
[5]
Self Interference
Cancellation
PA LNATx Rx
0ᵒ0ᵒ
0ᵒ 180ᵒ
Antenna
Balancing impedance
Antenna reflection
coefficient, ΓANT
Balancing reflection
coefficient, ΓBAL
Hybrid Junction
Transmitted signal
Residual interference
after EB duplexer
Residual interference
after EB duplexer and
active cancellation
Antenna
Impedance tuner
Hybrid
PXIe Chassis (VSTs)
Directional
coupler
Measured Isolation performance [4]
Tx-Rx Isolation
P(Isolation>Mantissa)
Ideal
10 ms
20 ms
Non-adaptive
Simulated performance with measured
antenna dynamics [2]
• Antenna impedance variation due to dynamic environment (e.g.
user interaction).
• Balancing impedance must track changes in antenna impedance.
• Measured dynamic
antenna with simulated
adaptive duplexer
• Duplexer is rebalanced
(i.e. balancing
impedance is retuned)
at fixed intervals.
• Isolation is variable and
depends on adaptation
behaviour.
Communication Systems & Networks Research Group
Merchant Venturers Building, Woodland Road, Bristol. BS8 1TR
• Published in high impact journals
• Two patents pending, protecting the
circuit design and the control algorithms.
• Prototype has been demonstrated at
international conferences
• Breakthrough design has received media
coverage in the technical press
• UK EPSRC ICT Pioneers 2016 Technology
Everywhere Prize
Acheivements [1] L. Laughlin, C. Zhang, M. A. Beach, K. A. Morris and J. L.
Haine, “Passive and active electrical balance duplexers”, IEEE
Transactions on Circuits and Systems II: Express Briefs., vol. 63,
no. 1, pp. 94–98, 2016.
[2] L. Laughlin, M. A. Beach, K. A. Morris and J. L. Haine,
“Electrical balance duplexing for small form factor realization of in-
band full duplex”, IEEE Communications Magazine, vol. 53, no. 5,
pp. 102–110, May 2015.
[3] L. Laughlin, M. A. Beach, K. A. Morris and J. L. Haine,
“Optimum single antenna full duplex using hybrid junctions”, IEEE
Journal on Selected Areas in Communications, vol. 32, no. 9, pp.
1653–1661, Sep. 2014.
[4] L. Laughlin, C. Zhang, M. A. Beach, K. A. Morris and J. Haine,
“A widely tunable full duplex transceiver combining electrical
balance isolation and active analog cancellation”, in Proceedings
of the 81st IEEE Vehicular Technology Conference (VTC),
Glasgow, May 2015, pp. 1–5.
[5] S. H. Abdelhalem, P. S. Gudem and L. E. Larson, “Hybrid
transformer-based tunable differential duplexer in a 90-nm cmos
process”, Microw. Theory Tech. IEEE Trans., vol. 61, no. 3, pp.
1316–1326, 2013.](https://image.slidesharecdn.com/fullduplexmarkbeachetal5gsummit2016v2-160422192657/85/Full-Duplex-for-5G-Handsets-1-320.jpg)
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Full Duplex for 5G Handsets
- 1. Aim: To bring Full-Duplex transceiver technology from the drawing board to the handset. A low cost, small form factor duplexing solution based on electrical balance isolation. Simulated and Measured Performance Division Free Duplex for 5G Handsets Leo Laughlin, Chunqing Zhang, Mark Beach, Kevin Morris, and John Haine email: M.A.Beach@Bristol.ac.uk This work is supported by the UK EPSRC under Grant EP/I028153/1, and by u-blox AG, 8800 Thalwil, Switzerland. Communication Systems and Networks Group @BristolCSN bristol.ac.uk/engineering/research/csn Bristol Full Duplex Transceiver Architecture • High isolation achieved when ΓBAL= ΓANT. • Balancing impedance must be dynamically adapted to track antenna impedance in the time domain. 2dB Tx insertion loss, 5dB Rx noise figure. • Suitable for small form factor multiband mobile devices: requires just one antenna, can be implemented on chip, and can be tuned over wide frequency ranges. • Isolation bandwidth limited by Frequency domain variation in antenna and balancing impedances. Electrical Balance Duplexer Hybrid can be implemented on-chip + Active Analogue Cancellation ΓANT (ω) ΓBAL(ω) Band limited isolation due to diverging values of antenna and balancing impedances. • Residual self-Interference at EB duplexer receive port • Residual self Interference reduced by actively injecting cancellation signal. • Frequency selective self-interference channel can be replicated using baseband DSP. • Cancellation performance limited by EVM of radio chain. • Implements LTE like OFDM physical layer. • Active cancellation subsystem estimates amplitude and phase of residual self- interference for each subcarrier. (SC spacing = 15kHz). • Cancellation signal is then generated using Frequency Domain Equalisation (FDE) on a copy of the transmit signal. • Results demonstrate wide tuneability. Performance is the same at 900MHz and 1900MHz. [5] Self Interference Cancellation PA LNATx Rx 0ᵒ0ᵒ 0ᵒ 180ᵒ Antenna Balancing impedance Antenna reflection coefficient, ΓANT Balancing reflection coefficient, ΓBAL Hybrid Junction Transmitted signal Residual interference after EB duplexer Residual interference after EB duplexer and active cancellation Antenna Impedance tuner Hybrid PXIe Chassis (VSTs) Directional coupler Measured Isolation performance [4] Tx-Rx Isolation P(Isolation>Mantissa) Ideal 10 ms 20 ms Non-adaptive Simulated performance with measured antenna dynamics [2] • Antenna impedance variation due to dynamic environment (e.g. user interaction). • Balancing impedance must track changes in antenna impedance. • Measured dynamic antenna with simulated adaptive duplexer • Duplexer is rebalanced (i.e. balancing impedance is retuned) at fixed intervals. • Isolation is variable and depends on adaptation behaviour. Communication Systems & Networks Research Group Merchant Venturers Building, Woodland Road, Bristol. BS8 1TR • Published in high impact journals • Two patents pending, protecting the circuit design and the control algorithms. • Prototype has been demonstrated at international conferences • Breakthrough design has received media coverage in the technical press • UK EPSRC ICT Pioneers 2016 Technology Everywhere Prize Acheivements [1] L. Laughlin, C. Zhang, M. A. Beach, K. A. Morris and J. L. Haine, “Passive and active electrical balance duplexers”, IEEE Transactions on Circuits and Systems II: Express Briefs., vol. 63, no. 1, pp. 94–98, 2016. [2] L. Laughlin, M. A. Beach, K. A. Morris and J. L. Haine, “Electrical balance duplexing for small form factor realization of in- band full duplex”, IEEE Communications Magazine, vol. 53, no. 5, pp. 102–110, May 2015. [3] L. Laughlin, M. A. Beach, K. A. Morris and J. L. Haine, “Optimum single antenna full duplex using hybrid junctions”, IEEE Journal on Selected Areas in Communications, vol. 32, no. 9, pp. 1653–1661, Sep. 2014. [4] L. Laughlin, C. Zhang, M. A. Beach, K. A. Morris and J. Haine, “A widely tunable full duplex transceiver combining electrical balance isolation and active analog cancellation”, in Proceedings of the 81st IEEE Vehicular Technology Conference (VTC), Glasgow, May 2015, pp. 1–5. [5] S. H. Abdelhalem, P. S. Gudem and L. E. Larson, “Hybrid transformer-based tunable differential duplexer in a 90-nm cmos process”, Microw. Theory Tech. IEEE Trans., vol. 61, no. 3, pp. 1316–1326, 2013.