© 2012 duplo - full-duplex radios for local access. all rights reserved. kari rikkinen, university...

© 2012 DUPLO - full-DUPlex radios for LOcal access. All rights reserved.

Kari Rikkinen, University of Oulu

Pre-FIA Workshop

17 March 2014, Athens

A new full-duplex radio transmission paradigm


Contents

• Introduction

• FD transceiver

• FD system

• Summary

• References

2


Why Full-Duplex ?

Full-duplex (FD) radio transmission paradigm = the same carrier frequency is simultaneously used both for transmission and reception at the wireless transceiver.

•FD transmission can provide significant improvements to wireless communications systems operation• increased link capacity

• flexibility in spectrum usage

• improved security in transmission

• efficient solutions for channel access (e.g., for cognitive radio)

•Lot of activity and progress in full-duplex research during past two-three years to develop transceiver solutions and applications for FD

•FD is a potential technology component for 5G networks, but could even be applied earlier into the evolution path of 4G and WLAN systems• FD has already been proposed to IEEE 802.11 standardization

3


DUPLO project

• DUPLO: Full-Duplex Radios for Local Access• EU FP7 ICT project (STREP)

• Duration: November 2012 – April 2015

• Partners: University of Oulu (coordinator), IMEC, TTI, Thales, University of Surrey, University of Twente

•Main objectives• Full-duplex technology development for wireless communications transceivers

• RF, antenna and digital baseband solutions enabling efficient self-interference cancellation in wireless transceiver

• System solutions for full-duplex transmission

• focus in small area radio communication solutions• potential use cases, performance analysis, network level solutions

• Proof-of-concept verification

4


FD transceiver implementation challenge – self-interference

•Self-interference in the FD transceiver

•The self-interference is caused by multiple mechanisms• direct crosstalk between TX and RX paths in the transceiver • limited antenna isolation• transmit signal reflections from the objects close to the FD transceiver

•How much self-interference suppression is needed ? • In general, self-interference level in the receiver should be reduced to noise floor to get full benefit out from full-duplex transmission.

• The amount of self-interference cancellation (SIC) in total (isolation + cancellation) depends on system operation assumptions, example budget:

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o PTX: +10 dBmo 10 MHz bandwidth and 15 dB NF RX noise floor at -89 dBm/10 MHz 99 dB of self-interference cancellation in total (isolation + cancellation) needed


• Measurement set-up• wideband channel measurement

(measurement bw 7 GHz)

• test transceiver with separate TX and Rx antennas (antenna separation 30 cm)

• different measurement locations • anechoic chamber, lab environment

(with/without strong reflectors close to the transceiver), office environment

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Self-interference channel characteristics

a)

Antenna orientations

b)

c)

d)

• Measurement results

SI channel is a multipath channel

[1]

[1] [1]

[1] A.Sethi, V.Tapio, M.Juntti,”Self-interference Channel for Full Duplex Transceivers”, To appear in IEEE WCNC2014, Istanbul, Turkey.


FD transceiver structure

•Three main means to reduce self-interference at the FD transceiver• Antenna(s)

• isolation of the transmit signal from the receiver chain at the antenna level

• e.g., use of separate TX and RX antennas, use of different polarizations for TX and RX, use of MIMO techniques

• Analog RF (or baseband) cancellation• subtraction of self-interference at RX analog path

• Digital baseband cancellation• removal of remaining self-interference at digital baseband

• transceiver chain impairments (e.g., PA nonlinearity and phase noise in oscillators) should be included in the SI channel model for the optimum performance

• Combination of these techniques is needed to achieve good self-interference cancellation capability.

7

Block diagram of full-duplex transceiver


FD transceiver solutions

Reference

Solution SIC performance

Stanford [3](2011)

Separate TX and RX antennas (20cm distance)RF cancellation with balun circuit Digital BB interference cancellation

RF (balun) cancellation 43 dBDigital BB cancellation 30 dB(digital + balun) 73 dB + additional 40 dB from antenna separation (estimate) (measurement bandwidth: 10 MHz, in 2.4 GHz band)

Rice [5](2012)

Separate TX and RX antennas (20cm distance)RF cancellation with additional RF chain Digital BB interference cancellation

Antenna separation (AS) 41 dBAS + RF + Digital BB 78 dB (measurement bandwidth: 625 kHz, in 2.4 GHz band)

Rice [6](2012)

Separate TX and RX antennas (50 cm distance, with 90o beamwidth and different tilting), optional use of cross-polarized antennasActive RF and BB cancellation

Antenna only w/o cross-pol. 60 dBAntenna only with cross-pol. 70 dBAntenna (w/o cross-pol.)+ RF + BB 86 dBAntenna (with cross-pol.)+ RF + BB 95 dB(measurement bandwidth: 20 MHz, in 2.4 GHz band)

NYU [7](2012)

Circularly polarized patch antenna + balanced feed network (single antenna solution)Active RF interference cancellationNo digital BB (in the analysis)

Antenna & balanced feed network 40-45 dBAntenna/feed network + RF canceller 59 dB (measurement bandwidth: 8 MHz, in 914 MHz band)

Stanford [4](2013)

Single antenna + circulatorAdaptive analog RF cancellerDigital BB interference cancellation

Circulator + analog cancellation 62 dBDigital BB cancellation 48 dBTotal 110 dB(measurement bandwidth: 80 MHz, in 2.4 GHz band)

8

90-110 dB total SIC cancellation capability is achievable

Different FD transceiver solutions and their reported performance


•To enable wide application areas for the full-duplex technology in the evolved 4G/WLAN and 5G systems, the FD transceiver solutions need to be implementable for small form factor radio devices, e.g., • femto-cell nodes, tablets, smart phones, or sensor nodes (’extremely’ small form factor)

•Two different analog/RF solution approaches selected for the DUPLO compact FD transceiver design,i.e.,

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Potential analog/RF solutions for compact FD transceivers

Upper Patch

Lower Patch & Feeding Network

PORT 1

PORT 2

Electrical Balance SIC

TX RX

1. Dual-polarized antenna with active RF canceller

• use of different polarizations for TX and RX signals• pacth antenna structure (prototype dimensions 60 x

60 x 8 mm)• isolation > 50 dB (simulated, in 10 MHz bw)• low antenna loss • additional 10 dB cancellation with active RF canceller• potential solution for femto-cell nodes, laptops etc

2. Electrical balance duplexer • use of electrical balance circuit to isolate TX and RX• enables very small size implementation into CMOS (≈

1 mm2)• can be combined with miniature antenna• isolation ≈ 50 dB (simulated, in 6 MHz bw)• duplexer insertion loss (3 dB) • potential solution for smartphones, sensor nodes etc

[9] B.Debaillie, D.J. van den Broek, C.Lavin, B. van Liempd, E.A.M. Klumperink, C. Palacios, J. Craninckx, B. Nauta, A. Pärssinen ”Analog/RF Solutions Enabling Compact Full-Duplex Radios”, accepted to IEEE JSAC Special Issue on Full-duplex Wireless Communications and Networks, 2014.


Use of FD transmission paradigm in wireless systems

•Potential applications of full-duplex transmission technology in wireless systems include M2M communications, D2D connections, relays, backhaul connections, terminal to access point connections, mesh network solutions, etc.

•Most straightforward application for FD transmission is a single (isolated) point-to-point link

•Applying FD transmission to legacy systems may require modifications to scheduling and radio resource management solutions due to additional interference paths FD introduces to system operation• inter-user interference

• inter-cell interference (in multicell scenario)

10

Example of a small cell with a full-duplex BS and half-duplex UEs(Blue and red arrows denote different radio resources)

Example of two neighboring small cells with full-duplex BS and UEs

A point-to-point full-duplex link


Summary

•The main challenges with full-duplex transmission are related to transceiver design and system solutions.

•State-of-the-art results indicate that it is possible to achieve 90-110 dB total self-interference cancellation capability (at least with experimental demonstrator, by now).

•To enable wide application areas for the full-duplex technology in the evolved 4G/WLAN and 5G systems, the FD transceiver solutions need to be implementable for small form factor radio devices.

• System level studies are needed to clarify what is the total impact of full-duplex transmission to wireless system performance and how to manage with additional interferences (inter-node, inter-cell interference).

•DUPLO project is working with FD transceiver design and system level simulations and analysis aiming for solutions applicable to evolved 4G/WLAN and 5G systems.

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© 2012 DUPLO - full-DUPlex radios for LOcal access. All rights reserved. 12

DUPLO Workshop on Full-Duplex Radios and Systems

June 4, 2014 Oulu, Finland

http://duploworkshop.crowncom.org/2014/show/home

(Attached to CrownCom 2014 conference, June 2–4, 2014 Oulu, Finland)




References

[1] A.Sethi, V.Tapio, M.Juntti,”Self-interference Channel for Full Duplex Transceivers”, To appear in IEEE WCNC2014, Istanbul, Turkey.

[2] W.Li, J.Lilleberg,”On Full-Duplex Link Performance Under Consideration of Error Vector Magnitude”, To appear in IEEE WCNC2014, Istanbul, Turkey.

[3] J. Choi, T. Kim, D. Bharadia, S. Seth, K. Srinivasan, P. Levis, S. Katti, P. Sinha, "Practical, Real-time, Full Duplex Wireless," International Conference on Mobile Computing and Networking, Sept. 2011.

[4] D.Bharadia, E.McMilin, S.Katti, ”Full Duplex Radios”, SIGCOMM’13, Aug 12-16, 2013, Hong Kong, China.

[5] M.Duarte, C.Dick, A.Sabharwal,”Experiment-Driven Characterization of Full-Duplex Wireless Systems’, IEEE Tr. On Wireless Communications, Vol.11, NO.12, Dec 2012,pp.4296-4307.

[6] E.Everett, A. Sahai, A. Sabharwal,”Passive Self-Interference Suppression for Full-Duplex Infrastructure Nodes”, IEEE Transactions on Wireless Communication, October 2013.

[7] M. E. Knox, “Single antenna full duplex communications using a common carrier,” in Proc. 13th Annual Wireless and Microwave Technology Conference (WAMICON), 2012, pp. 1 –6.

[8] R.Taori, W-C. Kuo, J. Kaushik, H-R Shao, H. Kang, S. Chang, ”Considerations for In-Band Simultaneous Transmit and Receive (STR) feature in HEW”, IEEE 11-13/1122r1.

[9] B.Debaillie, D.J. van den Broek, C.Lavin, B. van Liempd, E.A.M. Klumperink, C. Palacios, J. Craninckx, B. Nauta, A. Pärssinen ”Analog/RF Solutions Enabling Compact Full-Duplex Radios”, accepted to IEEE JSAC Special Issue on Full-duplex Wireless Communications and Networks, 2014.

14

© 2012 duplo - full-duplex radios for local access. all rights reserved. kari rikkinen, university...

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