220 research outputs found
Learning-Initialized Trajectory Planning in Unknown Environments
Autonomous flight in unknown environments requires precise planning for both
the spatial and temporal profiles of trajectories, which generally involves
nonconvex optimization, leading to high time costs and susceptibility to local
optima. To address these limitations, we introduce the Learning-Initialized
Trajectory Planner (LIT-Planner), a novel approach that guides optimization
using a Neural Network (NN) Planner to provide initial values. We first
leverage the spatial-temporal optimization with batch sampling to generate
training cases, aiming to capture multimodality in trajectories. Based on these
data, the NN-Planner maps visual and inertial observations to trajectory
parameters for handling unknown environments. The network outputs are then
optimized to enhance both reliability and explainability, ensuring robust
performance. Furthermore, we propose a framework that supports robust online
replanning with tolerance to planning latency. Comprehensive simulations
validate the LIT-Planner's time efficiency without compromising trajectory
quality compared to optimization-based methods. Real-world experiments further
demonstrate its practical suitability for autonomous drone navigation
Estimation of MIMO transmit-antenna number using higher-order moments based hypothesis testing
This letter proposes a higher-order-moment based
hypothesis testing algorithm to estimate the transmit-antenna
number for multiple-input multiple-output (MIMO) systems.
Exploiting the asymptotic normal distribution of the moments
composed by noise eigenvalues, the proposed algorithm improves
the estimation performance for low signal-to-noise ratios (SNRs).
Moreover, since the empirical distribution of the moments converges
quickly to the normal distribution when the number of
samples increases, our algorithm can make a reliable estimation
in a sample starved condition. Computer simulations are provided
to demonstrate that the proposed algorithm outperforms the
conventional algorithms
Joint Power Allocation and Beamforming for Active IRS-aided Directional Modulation Network
To boost the secrecy rate (SR) of the conventional directional modulation
(DM) network and overcome the double fading effect of the cascaded channels of
passive intelligent reflecting surface (IRS), a novel active IRS-assisted DM
system with a power adjusting strategy between transmitter and active IRS is
proposed in this paper. Then, a joint optimization of maximizing the SR is cast
by alternately optimizing the power allocation (PA) factors, transmit
beamforming at the BS, and reflect beamforming at the active IRS, subject to
the power constraint at IRS. To tackle the formulated non-convex optimization
problem, a high-performance scheme of maximizing SR based on fractional
programming (FP) and successive convex approximation (SCA) (Max-SR-FS) is
proposed, where the FP and SCA methods are employed to optimize the PA factor
of confidential message and the PA factor of power allocated to the BS, and the
SCA algorithm is also utilized to design the transmit beamforming and phase
shift matrix of the IRS. To reduce the high complexity, a low-complexity
scheme, named maximizing SR based on derivative operation (DO) and general
power iterative (GPI) (Max-SR-DG), is developed, where the DO and methods of
the equal amplitude reflecting (EAR) and GPI are adopted to derive the PA
factors and IRS phase shift matrix, respectively. Simulation results show that
with the same power constraint, both the proposed schemes harvest about 12
percent and 70 percent rate gains over the equal PA and passive IRS schemes,
respectively
Outage Performance Enhancement for NOMA Based Cooperative Relay Sharing Networks
This letter considers a non-orthogonal multiple access (NOMA) based cooperative relay sharing (CRS) network, where two sources communicate with their corresponding users over the same time and frequency via a shared decode-and-forward relay. A novel transmission scheme using max-min criterion based dynamic decoding order strategy is proposed to minimize the outage probability of the network at the cost of lower complexity and overhead. The closed-form expression of the overall outage probability for the proposed scheme is derived. Both analytical and simulation results show that the proposed scheme can achieve non-zero diversity order and almost the same outage performance as the dynamic power allocation based transmission scheme for NOMA based CRS networks
Sum-Rate Maximization Based Relay Selection for Cooperative NOMA over Nakagami-m Fading
This paper proposes a new sum-rate maximization based relay selection (RS) scheme for cooperative non-orthogonal multiple access (NOMA) networks over Nakagami- fading, where one base station communicates with two mobile users by means of multiple relays. The outage probability of the proposed scheme is derived in a closed-form expression, and the diversity order is also obtained. Simulation results are shown to compare the outage performance of the proposed scheme with that of the existing RS schemes
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