Abstract
Wireless networks with directional antennas, like millimeter wave (mmWave) networks, have enhanced security. For a large-scale mmWave ad hoc network in which eavesdroppers are randomly located, however, eavesdroppers can still intercept the confidential messages, since they may reside in the signal beam. This paper explores the potential of physical layer security in mmWave ad hoc networks. Specifically, we characterize the impact of mmWave channel characteristics, random blockages, and antenna gains on the secrecy performance. For the special case of uniform linear array (ULA), a tractable approach is proposed to evaluate the average achievable secrecy rate. We also characterize the impact of artificial noise in such networks. Our results reveal that in the low transmit power regime, the use of low mmWave frequency achieves better secrecy performance, and when increasing transmit power, a transition from low mmWave frequency to high mmWave frequency is demanded for obtaining a higher secrecy rate. More antennas at the transmitting nodes are needed to decrease the antenna gain obtained by the eavesdroppers when using ULA. Eavesdroppers can intercept more information by using a wide beam pattern. Furthermore, the use of artificial noise may be ineffective for enhancing the secrecy rate.
Highlights
W IRELESS ad hoc networks have been widely applied in several areas including tactical networks, deviceto-device, and personal area networking
We consider the directional beamforming and use a sectored model to analyze the beam pattern [4], [28]–[30] (See Fig. 1 in [4]), i.e., the effective antenna gain for an interferer i seen by the typical receiver is expressed as GM, PrMM = PrMm = PrMm = Prmm =
We focus on the carrier frequency at 28 GHz, 38 GHz, 60 GHz, and 73GHz, in which their LoS and NLoS path loss exponents are shown in Table I based on the practical channel measurements [42], [43]
Summary
W IRELESS ad hoc networks have been widely applied in several areas including tactical networks, deviceto-device, and personal area networking. The associate editor coordinating the review of this paper and approving it for publication was J. Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. MmWave with directional transmissions and large bandwidths provides rich opportunities for ad hoc networks. Compared to the lower frequency counterpart, mmWave ad hoc networks experience less interference and achieve greater rate coverage [4]. Security in ad hoc networks is important [5]. Recent developments have shown that by leveraging the randomness inherent in wireless channels, physical layer security can be a low-complexity alternative for safeguarding complex wireless networks [6]. By taking advantage of unique mmWave channel features, this paper establishes the potential of physical layer security in mmWave ad hoc networks
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