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To meet rapidly growing customer-traffic demands, passive optical networks (PONs) have been widely applied in optical access networks. However, one common imperfection of the commercially deployed PON is that the maximum rate is limited by the optical power budget of the worst-case optical network unit (ONU). If the current infrastructure is to continue into the future 100 Gb/s PON, the optical power budget of the worst-case ONU probably cannot meet the requirement for the 100 Gb/s data transmission. In this paper, we propose a new 100 Gb/s fine-granularity flexible-rate (FGFR) PON based on discrete multi-tone (DMT) with peak-to-average power ratio (PAPR) optimization. The FGFR DMT-PON frame integrates the DMT subframe with time-division multiple access to achieve higher overall throughput. Each ONU is able to achieve the maximum data rate depending on its optical power budget. A high PAPR is a big obstacle to the practical applications of the DMT in the PON. We use the joint clipping operation and clipping-noise-cancellation algorithm to mitigate the high PAPR for the DMT signal. The experimental results show that the FGFR DMT-PON can achieve a wide-range data-rate adjustment from 25 to 100 Gb/s with a potential granularity of 50 Mb/s under the optical power budget from 36 to 26 dB. [ABSTRACT FROM AUTHOR]

Universal Adversarial Perturbations (UAPs), which is type of image-agnostic adversarial attack, has been deeply investigated for Convolutional Neural Networks due to its high efficiency. On the other hand, as an architecture based on self-attention mechanism, Vision Transformers (ViTs) have boomed and been widely applied to solve various computer vision problems since most recent years. In this letter, we delve into the robustness of ViTs against universal adversarial attack and propose an inheritance attention matrix-based UAPs (IAM-UAP). Specifically, we introduce the inheritance attention weight matrix (IAM), which represents the integration of global information of the input patch sequence. Further, we propose a perturbation optimization objective based on IAM to confuse the global information integration of ViTs. The empirical results confirm the attacking capability of IAM-UAP on ViTs with a moderate attacking rate. In addition, we also disclose that the patch size of ViTs is a latent factor influencing the robustness against the universal attack. [ABSTRACT FROM AUTHOR]

Wireless network virtualization, which decouples the physical supply process and the service provisioning process, can abstract, isolate, and share the physical infrastructure network equipment. This paper studies the resource virtualization in virtual multiple-input multiple-output single-carrier frequency-division-multiple-access uplink systems, where resources are abstracted to hide the complex details of the fading channel and the link rates are virtualized using the statistical method. Furthermore, the virtual link rates are scheduled and instantiated to different slices with customized delay-bounded quality of service (QoS) provisioning. In this scheme, a physical mobile network operator (PMNO) is in charge of the network resource at the physical layer, while virtual mobile network operators (VMNOs) are responsible for the traffic admission and the slice management at the MAC layer. Furthermore, we build up the resource virtualization problem as a cross-layer Stackelberg game, which has the interactive dual processes based on the QoS exponent: top-to-down sub-game of leaders at the MAC layer and down-to-top sub-game of follower at the physical layer. Using the newly designed functions for PMNO and VMNOs, we develop an effective dynamic algorithm with an iterative dual update to meet the optimization targets of PMNO and VMNOs. Simulation results verify the superiority and stability of delay-bounded QoS guaranteed wireless resource virtualization algorithm developed in this paper in terms of convergence, access rate, and delay-outage probability. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the joint clustering of users and resources based on minimum mean square error-ordered successive interference cancellation (MMSE-OSIC) equalization for multi-cell single carrier-frequency division multiple access (SC-FDMA) uplink systems. To exploit the properties of the MMSE-OSIC equalization, we formulate the dynamic user grouping and resource allocation as a clustering problem, where resources are divided into several clusters and users are assigned into different clusters. Furthermore, we develop a new efficient K-means type algorithm named iterative K-groups clustering algorithm (IKG_OSIC) to solve the optimization problem. By making use of the MMSE-OSIC results, IKG_OSIC algorithm largely reduces the computation complexity of the joint resource allocation problem. The simulation results show that the proposed algorithm achieves good tradeoff between the performance and complexity and has better system throughput than the existing algorithms for virtual multiple-input multiple-output single carrier-frequency division multiple access (VMIMO-SC-FDMA) uplink systems. [ABSTRACT FROM AUTHOR]

In field measurements at millimeter-wave (mmWave) frequencies, the spatial propagation characteristics are usually obtained by using steerable high-gain horn antennas to compensate the large path loss. However, it is a challenging issue to deembed antenna patterns from the observed channel responses. This paper has two contributions. First, according to the steering-antenna sounding process, a spatial channel response model is designed, where the multipath propagation profile, antenna pattern, and channel response are spatially sampled and combined in a discrete convolutional form. Then, a low-complexity antenna deembedding algorithm, including two steps of deconvolutions, is proposed. Second, a field measurement campaign on the frequency-space mmWave channels in an office is presented to validate the method. The channels were sounded at 72.5 to 73.5 GHz using three horn antennas with different beam widths and gains. The omnidirectional angular channel responses (ACRs) were measured by rotating the receiver antenna. The observed and reconstructed ACRs are consistent, and the estimated antenna-free angular propagation profiles by using different horn antennas are also highly correlated, which validate the proposed antenna deembedding approach. Furthermore, the omnidirectional transfer functions in the mmWave band obtained using different horn antennas are compared, and the channel coherence bandwidth is analyzed based on the autocorrelation of the transfer functions. [ABSTRACT FROM PUBLISHER]