查看更多>>摘要：In this letter, we use two parallel coprime arrays to localize the jamming source. The classical Two-Dimensional (2D) Direction of Arrival (DOA) estimation primarily relies on unstructured sample covariance matrix. However, estimating the covariance matrix from a finite number of observations frequently fails to perfectly reflect the Toeplitz and Hermitian structural characteristics. Thus, we propose a high-precision localizer of jamming via preprocessing the covariance matrix. First, we introduce 2-Level-Toeplitz (2LT) structure matrix for 2D coarray signal, and derive it in terms of the entries of a Toeplitz matrix. Second, we parameterize the 2LT matrix and borrow the structured covariance estimation technique to obtain the least squares close-form solution. Finally, we reconstruct the noiseless augmented covariance matrix and apply 2D DOA estimation method. Our simulations show that structured covariance matrix enhances the performances of 2D DOA estimation with sparse arrays for jamming signals. Specifically, the Root Mean Squared Error (RMSE) of our estimator consistently approaches the Cramér-Rao Bound (CRB) for different signal-to-noise ratio values and an increasing number of jamming devices.
查看更多>>摘要：Exploration for new dimensions to convey information is a non-trivial task for resource-limited communications. Interleaved Chirp Spreading LoRa (ICS-LoRa) constitutes a new multi-dimensional space from the interleaved versions of LoRa waveforms to convey extra bits. Nevertheless, it destroys the phase continuity of LoRa waveforms and degrades the spectral localization, offsetting the benefit from the increased symbol payload size. This letter fully elaborates the potential of the interleaving dimension and proposes a continuous phase ICS-LoRa scheme, which is proven to be more efficient in data rate improvement than ICS-LoRa. Furthermore, a low-complexity design from the proposed scheme is provided for implementation simplicity.
查看更多>>摘要：Holographic-type communication (HTC) is emerging as an important application scenario for the next-generation communication systems. In particular, to provide immersive user experiences, HTC requires to implement 3D visual reconstruction of a physical object by collecting multi-view images from multiple viewpoints. However, it is a dilemma to balance the efficiency and the visual quality of this distributed HTC scenario. To tackle this problem, a distributed multi-view image semantic communication (DMISC) scheme is proposed in this letter. First, a framework consisting of multiple individual semantic encoders and a joint multi-view semantic decoder is proposed to achieve high-quality image recovery by leveraging the correlations among multi-views. Second, a convolutional neural network-based DMISC model is designed to achieve high communication efficiency and visual quality for 3D reconstruction, by combining joint source-channel coding with joint multi-view decoding. Finally, the simulation results are presented to show that our proposed DMISC scheme can achieve better performance than those existing schemes.
查看更多>>摘要：To support the long-term stable communication demand along with burst traffic demands in 5G/6G smart environments, a new hybrid deployment strategy for fixed base stations (BSs) and unmanned aerial vehicles (UAVs) is proposed. Firstly, a cell integration strategy based on user distribution is proposed, which addresses the issues of high algorithm complexity and poor stability associated with existing hybrid macro/micro BS deployments. Secondly, to tackle the problem of large-scale burst traffic demand that cannot be solely covered by fixed BSs, UAVs are deployed according to user traffic demand, thereby effectively enhancing network coverage and minimizing unnecessary overheads. Simulation results reveal that our approach enhances coverage by 38.45%, reduces algorithm complexity by 31.22%, and decreases UAV deployment costs by 8.9% compared to the traditional method, while ensuring over 98% coverage of burst traffic demand. Furthermore, it confirms that our method fulfills the requirements of mobile user scenarios.
查看更多>>摘要：We enhance coarsely quantized LDPC decoding by reusing computed check node messages from previous iterations. Typically, variable and check nodes update and replace old messages every iteration. We show that, under coarse quantization, discarding old messages entails a significant loss of mutual information. The loss is avoided with additional memory, improving performance by up to 0.23 dB. We optimize quantization with a modified information bottleneck algorithm that considers the statistics of old messages. A simple merge operation reduces memory requirements. Depending on channel conditions and code rate, memory assistance enables up to 32% better area efficiency for 2-bit decoding.
查看更多>>摘要：As a key technology to recover transmitted symbols without any prior information of the incoming signals, pilot-free equalization (PE) has gained widespread attention from researchers. However, conventional PE algorithms often assume a constant or slowly varying channel, limiting their effectiveness in rapidly changing environments. In this letter, we propose a transformer-based deep PE network specifically designed for time-varying channels. To compensate for carrier frequency offsets (CFOs), we incorporate an adaptive parameter correction module. Moreover, the network implements a pre-extractor to capture multi-scale channel features, enabling it to handle time-varying conditions effectively. Simulations demonstrate that the proposed method achieves performance comparable to orthogonal frequency division multiplexing (OFDM) systems while significantly reducing pilot overhead.
查看更多>>摘要：We introduce NeRFCom, a novel communication system designed for end-to-end 3D scene transmission. Compared to traditional systems relying on handcrafted NeRF semantic feature decomposition for compression and well-adaptive channel coding for transmission error correction, our NeRFCom employs a nonlinear transform and learned probabilistic models, enabling flexible variable-rate joint source-channel coding and efficient bandwidth allocation aligned with the NeRF semantic feature’s different contribution to the 3D scene synthesis fidelity. Experimental results demonstrate that NeRFCom achieves free-view 3D scene efficient transmission while maintaining robustness under adverse channel conditions.
查看更多>>摘要：A novel distributed global satellite navigation synchronous spoofer, which is deployed as a pseudo-satellite constellation, sends several synchronous spoofing signals from different directions of arrival (DOAs). In this letter, we propose a synchronous spoofing monitoring method based on a spatial cross-correlation spectrum. The power and corresponding DOA measurements of those correlated sources are extracted by searching for the peak of the proposed cross-correlation spectrum. Experimental results demonstrate that the proposed method enables the simultaneous estimation of three essential features, such as DOAs, received power levels, and cross-correlations among different navigation signals, and effectively detects the synchronous spoofing signal at the moment when the monitoring correlation coefficients reach the maximum of 1.
Jan RadilMartin ŠlapákRudolf VohnoutJaromír Šíma...
908-912页
查看更多>>摘要：In this letter, we present the latest findings in coexistence of two rather different classes of optical signals in one fiber – classical data signals and quantum signals. The most significant and notable difference between the two is the optical power, which is several orders (7 or more) of magnitude distinct from each other. There are several approaches to address this issue – in this letter, at a glance, the realistic and practical approach, which relies on the selection of high-grade optical filters, was chosen. Rigorous, however affordable, optical filtering is required to avoid any possible crosstalk, not only from the classical data signals but also from the spontaneous nonlinear Raman scattering effect. In our experimental verification, it has been demonstrated that the selection of high-grade transmission components is a crucial element in the success of multiplexing strong and weak optical signals in a single fiber. In real-world applications, this approach significantly reduces infrastructure costs by eliminating the need for additional fiber.
NETL
NSTL
IEEE