3 research outputs found
Jamming-Resistant Receivers for the Massive MIMO Uplink
We design a jamming-resistant receiver scheme to enhance the robustness of a
massive MIMO uplink system against jamming. We assume that a jammer attacks the
system both in the pilot and data transmission phases. The key feature of the
proposed scheme is that, in the pilot phase, we estimate not only the
legitimate channel, but also the jamming channel by exploiting a purposely
unused pilot sequence. The jamming channel estimate is used to constructed
linear receive filters that reject the impact of the jamming signal. The
performance of the proposed scheme is analytically evaluated using asymptotic
properties of massive MIMO. The optimal regularized zero-forcing receiver and
the optimal power allocation are also studied. Numerical results are provided
to verify our analysis and show that the proposed scheme greatly improves the
achievable rates, as compared to conventional receivers. Interestingly, the
proposed scheme works particularly well under strong jamming attacks, since the
improved estimate of the jamming channel outweighs the extra jamming power.Comment: submitted to IEEE Trans. Inf. Forensics and Securit
A Practical Spectrum Sharing Scheme for Cognitive Radio Networks: Design and Experiments
Spectrum shortage is a fundamental problem in wireless networks and this
problem becomes increasingly acute with the rapid proliferation of wireless
devices. To address this problem, spectrum sharing in the context of cognitive
radio networks (CRNs) has been considered a promising solution. In this paper,
we propose a practical spectrum sharing scheme for a small CRN that comprises a
pair of primary users and a pair of secondary users by leveraging the
multiple-input and multiple-output (MIMO) technology. In our scheme, we assume
that the secondary users take full responsibility for cross-network
interference cancellation (IC). We also assume that the secondary users have no
knowledge about the primary network, including its signal waveform, frame
structure, and network protocol. The key components of our proposed scheme are
two MIMO-based interference management techniques: blind beamforming (BBF) and
blind interference cancellation (BIC). We have built a prototype of our scheme
on a wireless testbed and demonstrated that the prototyped secondary network
can coexist with commercial Wi-Fi devices (primary users). Experimental results
further show that, for a secondary device with two or three antennas, BBF and
BIC achieve an average of 25dB and 33dB IC capability in an office environment,
respectively
Independence-Checking Coding for OFDM Channel Training Authentication: Protocol Design, Security, Stability, and Tradeoff Analysis
In wireless OFDM communications systems, pilot tones, due to their publicly
known and deterministic characteristic, suffer significant
jamming/nulling/spoofing risks. Thus, the convectional channel training
protocol using pilot tones could be attacked and paralyzed, which raises the
issue of anti-attack channel training authentication (CTA), i.e., verifying the
claims of identities of pilot tones and channel estimation samples. In this
paper, we consider one-ring scattering scenarios with large-scale uniform
linear arrays (ULA) and develop an independence-checking coding (ICC) theory to
build a secure and stable CTA protocol, namely, ICC-based CTA (ICC-CTA)
protocol. In this protocol, the pilot tones are not only merely randomized and
inserted into subcarriers but also encoded as diversified subcarrier activation
patterns (SAPs) simultaneously. Those encoded SAPs, though camouflaged by
malicious signals, can be identified and decoded into original pilots for
high-accuracy channel impulse response (CIR) estimation. The CTA security is
first characterized by the error probability of identifying legitimate CIR
estimation samples. The CTA instability is formulated as the function of
probability of stably estimating CIR against all available diversified SAPs. A
realistic tradeoff between the CTA security and instability under the
discretely distributed AoA is identified and an optimally stable tradeoff
problem is formulated, with the objective of optimizing the code rate to
maximize security while maintaining maximum stability for ever. Solving this,
we derive the closed-form expression of optimal code rate. Numerical results
finally validate the resilience of proposed ICC-CTA protocol.Comment: arXiv admin note: text overlap with arXiv:1803.0208