To overcome the physical random access channel (PRACH) capacity shortfall, we propose a class of generalized symmetric Zadoff-Chu (SZC) sequences, which could be used to meet the stringent needs about the random access (RA) procedure of mobile satellite communications. Compared with the SZC sequences given by Cui et al. (IEEE Communications Letters, Doi: 10.1109/LCOMM.2015.2411610), the proposed new sequences have a large set size and the same good performance of anti-frequency offset.
Quasi-complementary sequence sets (QCSSs) can be seen as a generalized version of complete complementary codes (CCCs), which enables multicarrier communication systems to support more users. In this paper, we revisit the connection between $(n,k)$ sequences and Florentine rectangles, and design optimal QCSS, based on those Florentine rectangles.
This paper proposes a convolution neural network (CNN) architecture for automatic recognition of signals on the basis of their modulations for Cognitive software defined radio (SDR) applications. It is developed starting from two CNNs specifically designed for this problem and is characterized by having a low number of convolution and fully connected layers sharing also a very low number of filters/units. Moreover, Batch normalization is used to increase learning rate and reduce training time. The reduced complexity together with its low operating time make it compliant with real-time SDR applications. The proposed architecture is validated on the RadioML2016.10a dataset showing interesting results in discriminating both analog and digital modulations under different signal to noise ratio (SNR) regimes.
In EUROCRYPT 2018, Cid et al. introduced a new concept on the cryptographic property of S-boxes to evaluate the subtleties of boomerang-style attacks. This concept was named as boomerang connectivity table (BCT for short). For a power function, the value distribution of BCT can be directly deter-mined by its boomerang spectrum. In this paper, we investigate the boomerang spectrum of a class of power functions over even characteristic finite fields via its differential spectrum, where the exponent is a Niho exponent.
In this paper, we introduce a new kind of hybrid character sums and their applications in the constructions of Mutually unbiased bases (MUBs) and codebooks. It is well-known that MUBs have significant applications in quantum information processing and other fields. However, only a few constructions of MUBs are known in the literature. In this note, we provide a recursive constructions of approximately mutually unbiased bases. Meanwhile, we present some constructions of asymptotically optimal codebooks by using the hybrid character sums.
A multilevel periodic complementary pair (PCP) over integers is a pair of integer sequences with the optimal sum of periodic autocorrelation functions that can be used to augment the known Golay complementary pairs (GCPs). Multilevel PCPs have the advantage of being arbitrary in length when compared to GCPs. As a result, this study proposes two construction options. The first is to construct multilevel PCPs of any length with an uncertain degree using perfect Gaussian integer sequences, and the second is to construct multilevel PCPs of odd prime length with a specified degree based on cyclotomic classes; addionally, the length of PCPs can be extended by interleaving with perfect sequences. A huge number of multilevel PCPs can be obtained using computer search.
Costas array is a class of radar signal array with perfect correlation property. An open problem about the limiting performance of the costas array (i.e. the Golomb-Taylor’s fifth conjecture) is solved in this paper.
Quantum synchronizable codes can correct the ef-fects of quantum noise on qubits as well as misalignment in block synchronization. In this paper, dual-containing cyclic codes of length $2pq$ and $p^{2}$ are constructed by generalized cyclotomy, where some of the cyclic codes of length $p^{2}$ are optimal or almost optimal. Based on these cyclic codes and their augmented codes, we obtain two new classes of quantum synchronizable codes whose synchronization capabilities are the best.
In this paper, we propose two constructions of binary and quadriphase even-length Z-complementary pairs (ZCPs) with a fixed zero corelation zone (ZCZ) ratio by properly cascading Golay complementary pairs (GCPs). The proposed constructions can generate ZCPs from a ZCP of shorter length with a large ZCZ ratio. The ZCPs with large ZCZ ratios extend to more flexible lengths through concatenation. The equivalent relation between the Kronecker product expression and several cascade sequences is revealed, and the direct construction formula of ZCPs with fixed ZCZ ratio is derived.
We study the packing and covering properties of orthogonal arrays (OAs) as we propose new approaches for obtaining estimations on the minimum distance and covering radius of orthogonal arrays (designs) via examination of their distance distributions. First, we use some special representation of a linear system of equations which allows us to analyse extreme solutions (distance distributions). Second, we show how databases with (feasible) distance distributions can be used for obtaining sharp bounds for the minimum distance and covering radius of OAs. Correspondingly, new bounds are presented either in analytic form and as products of an ongoing project for computation and investigation of the possible distance distributions of OAs.
In this paper, we propose a cubic Turbo Product code (TPC) with the Bose-Chaudhuri-Hocquenghem (BCH) code and the single parity-check (SPC) code as components, as well as an improved turbo-oriented adaptive belief propagation decoding based on the partial layered and row-column weight scheduling (PL-RC-TAB). The proposed coding scheme has comparable encoding and decoding complexities with the two dimensional (2D) TPC based on the classical turbo-oriented adaptive belief propagation (TAB) decoding, but can achieve faster decoding convergence rate and improved error correction performance.
This paper presents a novel active anti-jamming (AAJ) scheme for a jammed channel to enhance the communication between a transmitter node (TN) and receiver node (RN), where the TN actively exploits the jamming signal as a carrier to send messages. Specifically, the TN is equipped with a programmable-gain amplifier (PGA), which is capable of re-modulating the jamming signals for jamming modulation (JM). Under this setup, we first introduce an energy detector to extract the desired messages by distinguishing different energy levels of the received signals. Then, We investigate the channel capacity of the jammed channel enabled with the AAJ scheme. We also derive the semi-closed-forms of the channel capacity and the corresponding optimal input distribution for the binary input and continuous output channel. Finally, simulation results show that the proposed AAJ scheme allows the TN to communicate with the RN even under extremely strong and/or broadband jamming. Moreover, the channel capacity of the AAJ scheme outperforms that of the direct transmission (DT) when the jamming-to-noise ratio (JNR) at the RN is relatively high.
Time slot is valuable channel resource in the data link network based on TDMA architecture. As a pseudo-random sequence, the control sequence can be used to help users efficiently allocate the limited time slot resources, so as to achieve maximum resource utilization. In this paper, we propose a class of control sequences set that not only have good randomness and long-period properties, but also enable terminal users to have good self-organization capabilities. Meanwhile, the data link network can realize higher utilization of time slot resources to maximize the network channel capacity based on the control sequences set. Therefore, terminal users can access the network randomly with anti-eavesdropping capability.
In the Industrial Internet of Things (IIoT), the freshness of information plays a vital role to ensure quality and timely delivery of data services. In this paper, we use age of information (AoI) as the metric. To reduce the AoI, we leverage mobile edge computing (MEC) to partially offload information to the edge server. In addition, the feature of short packet communication in IIoT is also considered in this work. We derive the closed-form expression of average AoI under the standard automatic repeat request (ARQ) protocol with zero-wait policy, and then formulate the average AoI minimization problem by jointly optimizing the short packet blocklength and MEC offloading ratio. Due to the nonconvexity nature of the problem, we tackle it by employing block coordinate descent (BCD) and successive convex approximation (SCA) methods to solve it and then prove their convergence. Our numerical results show that the optimal average AoI yielded by our proposed approach is almost identical to the high-complexity exhaustive search method, and has significant improvement over the benchmark methods. Furthermore, from the AoI perspective, the optimal strategy tends to offload all information to edge server when the computing capacity of local device is less than a threshold.
The classical use of a pseudorandom number gen-erator (PRNG) is in the stream cipher encryption where the PRNG is the core for the security of the encryption scheme. The use of PRNGs is also in modern security and privacy techniques such as fully homomorphic encryption (FHE) and differential privacy (DP). When such techniques are employed in many real-world applications such as traditional analytics computing, embedded systems, smart metering and mobile sys-tems, generating a large amount of random numbers and random noises following certain distributions is challenging. In this paper, we propose a construction of a cryptographic pseudorandom noise generator (CPNG) that can also be used for resource-constrained applications. As two use cases, we show how the CPNG can generate Laplace and Gaussian noises for FHE and DP applications. Experimental results on the performance of the proposed generators are presented, along with a comparison.
Flexible line rate is one of the key features for future optical access networks offering optimized throughput to multiple fiber-to-the-X users with different channel conditions and service priority; meanwhile, considerations should focus on technological transition from single-wavelength 50G higher-speed PON (G.hsp) based on optical direct detection systems to future digital coherent technology 100G/λ and beyond. In this paper, we propose a single-carrier modulation scheme that can achieve flexible line rates with arbitrary rational oversampling ratios without altering sampling rate of the transceiver. In the proposed scheme, the waveforms are based on the well-shaped Dirichlet kernel using discrete Fourier transforms (DFT). However, in comparison to conventional single-carrier frequency-division multiplexing (SC-FDM), the Dirichlet waveform of the proposed modulation algorithm is real-valued; in such a way, the proposed algorithm can be readily applied for both pulse amplitude modulation (PAM) for direct detection PON and, with forward compatibility to, future digital coherent PON with e.g., quadrature amplitude modulation (QAM). To validate the feasibility of the proposed system, experiments were carried out and flexible data rates from 62.1 to 174.5 Gbit/s with up to 8-ary PAM was successfully demonstrated for IM/DD-based PON using a fixed sampling rate at 64 GSa/s. The experiments show that the oversampling ratio can be arbitrary rational numbers no less than 1 to adjust the signal Baud rate. As a result, the proposed scheme is promising for offering optimal bandwidth allocation for current IM/DD-based and future coherent PON.
The frequency-hopping sequence(FHS) plays a crucial role in achieving the anti-jamming capability of the FH communication system. Therefore, it is necessary to try to ensure that the wide-gap between two adjacent frequency slots is larger enough and the number of collisions is small enough. In this paper, we present a new class of wide-gap one-coincidence FHS set. Such WG-OC-FHS set is optimal with respect to WG-Peng-Fan Bound. And each sequence of the set is optimal with respect to WG-Lempel-Greenberger Bound. Compared with previous construction, this construction has good randomness and use all frequency slots as much as possible.
Recently, IEEE 802.11ad has received much attention in integrating sensing and communications (ISAC) due to its large bandwidth and high-frequency features. In this paper, a distance measurement algorithm based on auto-correlation is proposed. Such an algorithm exploits the periodic sequences in the preamble of the IEEE 802.11ad frame and does not require any modification to the protocol, which maintains not only low complexity, but also good compatibility with the original IEEE 802.11ad communication system. The simulations show that the centimeter-level measurement accuracy can be achieved when the signal-to-noise ratio (SNR) is above 0 dB; and the improved performance is obtained compared with the existing similar distance measurement algorithms.
This paper presents a novel design of Flag sequences whose ambiguity functions (AFs) are featured by the peak-curtain property. Such a property can be exploited for efficient identification of the AF peak by first searching the curtain, thus leading to low-complexity delay-Doppler estimation. Motivated by the high AF sidelobes of the existing Flag sequences, we propose to minimize the customized weighted integrated sidelobe level (CWISL) with the aid of an Accelerated Partially Majorization-Minimization Algorithm (APMMA). Numerical results demon-strate that our optimized Flag sequences have lower CWISL and peak sidelobe level (PSL) in the delay-Doppler zone of interest.
In this paper, for a prime $p$ and positive integers $n, m, e$, and $t$ such that $n=2me$ and $t=\lfloor\frac{m}{2}\rfloor$, a new large family $\mathcal{S}$ of p-ary sequences of period $p^{n}-1$ with low correlation is constructed. It is shown that $\mathcal{S}$ has maximum correlation magnitude $1+p^{\frac{n}{2}+2te-e}$, family size $p^{nt}$ and maximal linear span $(t+1)n$. Furthermore, based on the theory of quadratic forms over finite fields, all exact correlation values between sequences in $\mathcal{S}$ are determined when $p = 2$.
