We propose an agile-beam non-orthogonal multiple access (NOMA) scheme for millimeter wave (mmWave) communication networks. The agile-beam NOMA scheme flexibly switches between the single/multi-beam NOMA depending on the user pairing results. In particular, a novel user pairing strategy employing both distance and angle information is designed to facilitate the agile-beam NOMA transmission. More specifically, the base station first selects one user from the far user group randomly and then pairs it with the user that has the minimum angle difference in the near user group. This pairing strategy efficiently exploits the channel sparsity in user domain while supporting flexible mmWave transmission with agilebeam NOMA. Then an in-depth performance analysis is carried out to reveal the interplay between the key system parameters and the coverage probability of the proposed agile-beam NOMA by using the tool of stochastic geometry. Moreover, numerical results demonstrate the superiority of the proposed agile-beam NOMA over the conventional NOMA and orthogonal multiple access (OMA) in mmWave communication networks. INDEX TERMS Millimeter wave (mmWave) communication, non-orthogonal multiple access (NOMA), user pairing.
We propose an agile-beam non-orthogonal multiple access (NOMA) scheme for millimeter wave (mmWave) communication networks. The agile-beam NOMA scheme can flexibly switch between the single/multi-beam NOMA transmission depending on the angular phase difference. In particular, we derive the asymptotic switching point with equal power and antennas resource allocation in a large number of BS antennas, which enables base station (BS) to make preliminary selection on beam mode. Furthermore, the optimization problem of maximizing the achievable sum rate in the agile-beam NOMA scheme is formulated and then decomposed into two subproblems, i.e., maximizing the sum rate in single-beam case and multi-beam case. And the optimal solution of power and antennas allocation is provided. Moreover, the proposed agile-beam NOMA scheme is extended to more general multi-user case. Simulation results verify the effectiveness of the asymptotic switching point compared with exact switching point. With the sum rate obtained by intelligent optimization algorithm as a benchmark, the optimal solution is validated in simulation. In addition, the sum rate with optimal resource allocation achieves significant gain over equal resource allocation.
INDEX TERMSMillimeter wave (mmWave) communication, non-orthogonal multiple access (NOMA), power and antenna allocation.
Spectrum sensing (SS) has been heatedly discussed due to its capacity to discover the idle registered spectrum bands, which effectively alleviates the shortage of spectrum by spectrum reuse. Energy detector (ED) is widely accepted for SS as its complexity is very low. In this paper, an adaptive sampling scheme is proposed to improve the sensing performance of ED, where the sampling point of the received signal is adaptively adjusted with the environment signal-to-noise ratio (SNR). When SNR decreases, the sensing performance can be maintained and even improved by the rise of the sampling point. When SNR increases, the improved ED is considered for idle spectrum detection. The SNR is evaluated based on the joint of convolutional neural network (CNN) and long short-term memory (LSTM) network. Both theoretical derivations and simulation experiments validate the effectiveness of the proposed scheme.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.