Power allocation algorithm in OFDM-based cognitive radio systems

In orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) systems, the optimized algorithms for sub-carrier power allocation face the problems of complex iterative calculation and difficult realization. In this paper, we propose an exponential power distribution function and derive a sub-optimal power allocation algorithm. This algorithm aims to allocate power of in-band subcarriers of cognitive users according to the numerical characteristics of the power distribution function by using a convex optimization numerical method under linear constraints. This algorithm has the advantages of fast calculation speed and easy realization, and reduces the interference to the authorized users, which is caused by the power leakage of the in-band subcarriers of cognitive users to the out-of-band subcarriers. Simulation results show that the proposed algorithm maximizes the inband channel capacity of the cognitive users under certain interference thresholds of the authorized users, thus increasing their transmission rate

Catch-Up Distillation: You Only Need to Train Once for Accelerating Sampling

Diffusion Probability Models (DPMs) have made impressive advancements in various machine learning domains. However, achieving high-quality synthetic samples typically involves performing a large number of sampling steps, which impedes the possibility of real-time sample synthesis. Traditional accelerated sampling algorithms via knowledge distillation rely on pre-trained model weights and discrete time step scenarios, necessitating additional training sessions to achieve their goals. To address these issues, we propose the Catch-Up Distillation (CUD), which encourages the current moment output of the velocity estimation model ``catch up'' with its previous moment output. Specifically, CUD adjusts the original Ordinary Differential Equation (ODE) training objective to align the current moment output with both the ground truth label and the previous moment output, utilizing Runge-Kutta-based multi-step alignment distillation for precise ODE estimation while preventing asynchronous updates. Furthermore, we investigate the design space for CUDs under continuous time-step scenarios and analyze how to determine the suitable strategies. To demonstrate CUD's effectiveness, we conduct thorough ablation and comparison experiments on CIFAR-10, MNIST, and ImageNet-64. On CIFAR-10, we obtain a FID of 2.80 by sampling in 15 steps under one-session training and the new state-of-the-art FID of 3.37 by sampling in one step with additional training. This latter result necessitated only 620k iterations with a batch size of 128, in contrast to Consistency Distillation, which demanded 2100k iterations with a larger batch size of 256. Our code is released at https://anonymous.4open.science/r/Catch-Up-Distillation-E31F

WindMill: A Parameterized and Pluggable CGRA Implemented by DIAG Design Flow

With the cross-fertilization of applications and the ever-increasing scale of models, the efficiency and productivity of hardware computing architectures have become inadequate. This inadequacy further exacerbates issues in design flexibility, design complexity, development cycle, and development costs (4-d problems) in divergent scenarios. To address these challenges, this paper proposed a flexible design flow called DIAG based on plugin techniques. The proposed flow guides hardware development through four layers: definition(D), implementation(I), application(A), and generation(G). Furthermore, a versatile CGRA generator called WindMill is implemented, allowing for agile generation of customized hardware accelerators based on specific application demands. Applications and algorithm tasks from three aspects is experimented. In the case of reinforcement learning algorithm, a significant performance improvement of $2.3\times$ compared to GPU is achieved.Comment: 7 pages, 10 figure

Donut-Shaped mmWave Printed Antenna Array for 5G Technology

This article presents compact and novel shape ring-slotted antenna array operating at mmwave band on central frequency of 28 GHz. The proposed structure designed at 0.256 mm thin Roggers 5880 is composed of a ring shape patch with a square slot etched at the top mid-section of partial ground plane. Through optimizing the ring and square slot parameters, a high bandwidth of 8 GHz is achieved, ranging from 26 to 32 GHz, with a simulated gain of 3.95 dBi and total efficiency of 96% for a single element. The proposed structure is further transformed in a 4-element linear array manner. With compact dimensions of 20 mm 22 mm for array, the proposed antenna delivers a high simulated gain of 10.7 dBi and is designed in such a way that it exhibits dual beam response over the entire band of interest and simulated results agree with fabricated prototype measurements

Secrecy performance by power splitting in cooperative dual-hop relay wireless energy harvesting

In wireless communication systems, for secure communication between a transmitter and receiver over the communication channel, the physical layer security is widely utilized. The paper presents a dual-hop wireless full-duplex relay (FDR) network with a source relay and destination relay between two nodes and listening devices. The relay and source use energy harvesting to gain energy from power beacon. Two cooperative techniques are utilized to investigate the amplify-forward (AF) and decode-forward (DF) secrecy capacity in the energy harvesting power splitting system. It is shown that the secrecy performance of an AF relay is better than the secrecy performance of a DF relay in the given form. At 40-meter distance between the relay and the eavesdropper in an energy harvesting system, the AF relay outperforms the DF relay. The simulation is performed using the Monte-Carlo method in MATLAB

Decision aided joint compensation of clipping noise and nonlinearity for MIMO-OFDM systems

In this paper, we propose a new iterative approach to compensate the nonlinearity and clipping noise in multi-input multi-output orthogonal frequency division multiplexing (MlMO-OFDM) system with nonlinear channel. The proposed approach consists of two stages. Firstly a decision aided method is proposed to eliminate the nonlinearity introduced by high power transmit amplifier (HPA). Then this improved decision observations are employed to achieve the clipping noise compensation. The effectiveness of the proposed approach has been verified by computer simulations