氏学位名張 品昌

名博士（システム情報科学）

学 位 記 番 号

第４５号

学位授与年月日

令和２年３月２３日

学位論文題目

Physical Layer Authentication for Wireless Communications

論文審査委員

主査 姜 暁鴻副査 稲村 浩副査 藤野 雄一
副査 和田 雅昭論

文 要 旨Authentication serves as a critical property of secure communication to verify theidentity of the entity involved in the communication. With the rapid development of
wireless technologies, the flexible and cost-effective authentication is becoming an
increasingly urgent demand for future wireless networks. This is because on one hand,the open and broadcast natures of wireless communications make wireless networks
more vulnerable to spoofing attacks, where an unauthorized transmitter may
impersonate as a legitimate one. On the other hand, with the wide deployment ofInternet of things (IoT) and continuous evolvement of wireless technologies toward thefifth generation (5G) and beyond networks, it is foreseeable that future wirelessnetworks will be consisted of a large number of heterogeneous devices, making
cryptographic authentication techniques in wireless networks a challenging issue.
Recently, physical layer authentication techniques, which exploit intrinsic and uniquefeatures of physical layer for authentication, has drawn a considerable attention toenhance and complement conventional cryptography-based authentication solutions.
This thesis focuses on the study of physical layer authentication for wirelesscommunications.
We first explore the channel-based authentication solution taking hardware
impairments into account and thus propose a new channel-based authentication scheme
for massive multiple input-multiple-output (MIMO) systems with non-ideal hardware.

In particular, based on signal processing theory, we formulate channel estimation under
hardware impairments and determine error covariance matrix to assess the quantity
caused by hardware impairments on authentication performance. With the help ofhypothesis testing and matrix transformation theories, we are able to derive exact
expressions for the probabilities of false alarm and detection under different channel
covariance matrix models. Extensive simulations are carried out to validate theoreticalresults and illustrate the efficiency of the proposed scheme. Impacts of systemparameters on performance are revealed as well.
Wethen propose

a novel authentication

solution

which notonly exploitslocation-specific wireless channels but also utilizes transmitter-specific hardware
impairments for authentication, and thus propose an improved channel-based scheme
jointly utilizing channel gain and phase noise in heterogeneous MIMO systems. Three
properties of the proposed scheme: covertness, robustness, and security, are analyzed indetail. By using a maximum-likelihood estimator (MLE) and extended Kalman filter(EKF), we estimate channel gains and phase noise, and formulate variances ofestimation errors. We also quantize the temporal variations of channel gains and phasenoise through the developed quantizers. Based on theories of hypothesis testing andstochastic process, we then derive the closed-form expressions for false alarm andmissed detection probabilities with the consideration of quantization errors.
Simulations are carried out to validate theoretical results of the two probabilities.
Based on theoretical models, we further demonstrate that the proposed scheme makes
it possible for us to flexibly control performance by adjusting parameters (such as
channel gain threshold, phase noise threshold, and decision threshold) to achieve a
required authentication performance in specific MIMO applications.
Finally, we focus on the study of physical layer authentication in a dual-hop wirelessnetwork with an untrusted relay and propose an end-to-end (E2E) channel-based
authentication scheme. This scheme fully utilizes wireless channel feature (i.e., channel
impulse response in the dimensions of amplitude and path delay), and adopts artificial
jamming technique, so that it is not only resistant to impersonate attack from anunauthorized transmitter but also resilient to replay attack from the untrusted relay.
Theoretical analysis is conducted to derive expressions for false alarm and missed
detection probabilities. Finally, numerical and simulation results are provided toillustrate both the efficiency of these theoretical results and the E2E performance ofdual-hop wireless networks.

審査結果の要旨
This thesis focuses on the study of physical layer authentication for wireless communications.
More specifically, this thesis conducts the studies on: 1) the channel-based authentication solution
taking hardware impairments into account, 2) the authentication solution which not only exploits
location-specific wireless channels but also utilizes transmitter-specific hardware impairments forauthentication, and 3) an end-to-end (E2E) channel-based authentication scheme for a dual-hop
wireless network with an untrusted relay. In the first study, this thesis proposes a new channel-based
authentication scheme for massive multiple input-multiple-output (MIMO) systems with non-ideal
hardware. In the second study, this thesis presents an improved channel-based scheme jointly
utilizing channel gain and phase noise in heterogeneous MIMO systems. In the last study, this thesis
designs an end-to-end (E2E) channel-based authentication scheme fully utilizing wireless channel
feature (i.e., channel impulse response in the dimensions of amplitude and path delay).
・論文の構成Chapter 1 Introduction
Chapter 2 Related Works
Chapter 3 End-to-End Physical Layer Authentication for Dual-Hop Wireless Networks
Chapter 4 Physical Layer Authentication for Massive MIMO Systems with Hardware
Impairments
Chapter 5 Physical Layer Authentication Jointly Utilizing Channel and Phase Noise forMIMO Systems
Chapter 6 Conclusion
Appendices
・研究目的の妥当性，従来の手法との比較においての有意性，および理論・実験手法の新規性
This thesis studies physical layer authentication for wireless communications.
More specifically, this thesis conducts the studies on: 1) the channel-based
authentication solution taking hardware impairments into account, 2) theauthentication solution jointly exploiting location-specific wireless channel gain andphase noise, and 3) the end-to-end (E2E) channel-based authentication solution in adual-hop wireless network with an untrusted relay.
In the first work, we propose a new channel-based authentication scheme formassive multiple input-multiple-output (MIMO) systems with non-ideal hardware.

Based on signal processing theory, channel estimation under hardware impairments
and error covariance matrix are derived. Exact expressions for the probabilities of false
alarm and detection under different channel covariance matrix models are modeled
analytically as well. Extensive numerical results are provided to validate theoreticalresults and illustrate the efficiency of this proposed scheme.
In the second work, we propose an improved channel-based authentication scheme
jointly utilizing channel gain and phase noise in heterogeneous MIMO systems. Three
properties of the proposed scheme: covertness, robustness, and security, are analyzed indetail. By using a maximum-likelihood estimator (MLE) and extended Kalman filter(EKF), we estimate channel gains and phase noise, and formulate variances ofestimation errors. Based on theories of hypothesis testing and stochastic process, wethen derive the closed-form expressions for false alarm and missed detection
probabilities with the consideration of quantization errors.
In the last work, we focus on end-to-end (E2E) channel-based authentication
solution, and propose a scheme which adopts artificial jamming technique and utilizes
wireless channel feature (i.e., channel impulse response in the dimensions of amplitude
and path delay), so it is not only resistant to impersonate attack from an unauthorizedtransmitter but also resilient to replay attack from the untrusted relay. Theoreticalanalysis is conducted to derive expressions for false alarm and missed detection
probabilities. Finally, numerical and simulation results are provided to illustrate theefficiency of these theoretical results and the new authentication scheme.
・得られた知見のシステム情報科学の分野における意義
The results of this thesis provide the following insights.
1. The studies conducted in this thesis will be helpful for the design of physical layer
authentication solutions. Our results show that flexible authentication performance
control can achieved by adjusting system parameters, and these proposed schemes havethe capability of satisfying different performance requirements for future emerging
wireless networks.
2. The results in this thesis help us to understand the potential effects ofmulti-dimensional physical layer features (e.g., channel impulse response, channel
frequency response, I/Q imbalance, carrier frequency offset, and phase noise) onauthentication performance.
3. The results imply that these proposed authentication schemes and related theoreticalmodels will be useful for providing a guideline to devise the coping
schemes against various attacks, as well as for understanding the fundamental
authentication performance of multi-hop wireless networks.