The development of computation-intensive and delay-sensitive smart applications has put forward great challenge to the current cellular networks. To cope with this challenge, unmanned aerial vehicles (UAVs) providing additional on-demand communication and computing services has become a promising technology. This letter proposes a novel task offloading framework in UAV-aided mobile edge computing (MEC) networks. Specifically, the MEC queuing delay is considered in the formulated problem, where the average task delay is minimized via jointly optimizing user association and UAV deployment. The optimal transport theory is introduced to analyze the user association sub-problem, and the UAV deployment is optimized by the classical particle swarm optimization algorithm. Simulation results show that the delay performance is significantly improved by the proposed algorithm.

In this paper, we propose a novel deep unsupervised learning-based approach that jointly optimizes antenna selection and hybrid beamforming to improve the hardware and spectral efficiencies of massive multiple-input-multiple-output (MIMO) downlink systems. By employing ResNet to extract features from the channel matrices, two neural networks, i.e., the antenna selection network (ASNet) and the hybrid beamforming network (BFNet), are respectively proposed for dynamic antenna selection and hybrid beamformer design. Furthermore, a deep probabilistic subsampling trick and a specially designed quantization function are respectively developed for ASNet and BFNet to preserve the differentiability while embedding discrete constraints into the network structures. With the aid of a flexibly designed loss function, ASNet and BFNet are jointly trained in a phased unsupervised way, which avoids the prohibitive computational cost of acquiring training labels in supervised learning. Simulation results demonstrate the advantage of the proposed approach over conventional optimization-based algorithms in terms of both the achieved rate and the computational complexity.

A critical bottleneck of massive multiple-input multiple-output (MIMO) system is the huge training overhead caused by downlink transmission, like channel estimation, downlink beamforming and covariance observation. In this paper, we propose to use the channel state information (CSI) of a small number of antennas to extrapolate the CSI of the other antennas and reduce the training overhead. Specifically, we design a deep neural network that we call an antenna domain extrapolation network (ADEN) that can exploit the correlation function among antennas. We then propose a deep learning (DL) based antenna selection network (ASN) that can select a limited antennas for optimizing the extrapolation, which is conventionally a type of combinatorial optimization and is difficult to solve. We trickly designed a constrained degradation algorithm to generate a differentiable approximation of the discrete antenna selection vector such that the back-propagation of the neural network can be guaranteed. Numerical results show that the proposed ADEN outperforms the traditional fully connected one, and the antenna selection scheme learned by ASN is much better than the trivially used uniform selection.

In order to reduce the downlink training overhead of mmWave communications, we propose a novel downlink beamforming strategy using the uplink sub-6GHz channel and downlink mmWave pilots that are sent from a few active antennas. Specifically, we design a novel dual-input neural network architecture, called FusionNet, to merge the sub-6GHz channel and the channel of a few active mmWave antennas. The proposed fusion model could intelligently adjust the attention paid (by the neural network) for sub-6GHz channel and mmWave channel by an attention mechanism. The output of the FusionNet represents the probability for each beam being the optimal one. We also propose an antenna selection model that can choose better active antennas to send the downlink pilots, in which the gradient of antenna selection vector is approximated by that of an antenna probability vector. Simulation results demonstrate the superior performance of the proposed strategy compared to the existing one that purely relies on the sub-6GHz information or compared to the shallow model that directly adds uniform pilots.

With the rapid increase of the demand for the Internet of Things (IoT), spectrum resources have incremental challenges. Nonorthogonal multiple access (NOMA) and spectrum sensing (SS) are considered key candidate technologies for next-generation wireless communications to improve spectrum utilization. Nevertheless, using both technologies at the same time makes the system more complex and brings new challenges to user differentiation. In order to make better use of these advantages, we creatively propose a feature detection-based SS method for NOMA systems. To better distinguish the relationship between the presence or absence of signals from different NOMA users, we employ feature detection to obtain the feature values of each user. We propose workflows and transceiver architectures combining the two technologies. Based on the relationship among users’ priorities, power, and transmission in common scenarios, we design a downlink mode and two uplink modes and deduce the threshold settings of the corresponding modes. Meanwhile, we also customarily propose enhanced algorithms, to have a marked increase in the performance for the proposed method in various modes. Experimental results illustrate that the proposed technique is feasible and has prominent detection performance and satisfying throughput performance.

Brain-computer interfaces (BCIs) aim to directly bridge the human brain and the outside world through acquiring and processing the brain signals in real time. In recent two decades, tremendous progress has been made in terms of BCI paradigms and decoding algorithms. The information transfer rate of the BCI systems has been significantly enhanced, and the communication community are considering including the BCI technologies into the 6G networks and beyond. However, some critical problems and challenges remain. To some extent, the BCI systems resemble the wireless communication systems, as brain signals are generated and transmitted by the neurons and received by the sensors, propagating through multiple brain tissues which cause inevitable attenuation and mixing effects. Therefore, by following this idea, a systematic review of the BCI technologies is provided through comparing it with wireless communications. The main challenges of BCI lie in brain channel modelling, modulation, signal processing and detection. The latest and some classic researches are covered. In addition, typical applications of BCIs such as the Quality-of-Experience (QoE) metric and Internet-of-Brains (IoB) are predicted. Then, we present a prospect of BCIs being integrated with future wireless communication systems. Also, the technical challenges regarding communication and computation to fulfill the prospect are discussed, as well as privacy, security and ethical concerns. Therefore, this review aims to comprehensively overview BCI-inspired communication on two levels, the BCI itself being a communication system and future integration of BCI and communication as a whole system.