Secondary User System Research Articles

Deep learning and chaotic system based image encryption algorithm for secondary user system

Deep learning and chaotic system based image encryption algorithm for secondary user system

Optimal energy-efficient transmission for hybrid spectrum sharing in cooperative cognitive radio networks

In order to improve the energy efficiency (EE) in cognitive radio (CR), this paper investigates the joint design of cooperative spectrum sensing time and the power control optimization problem for the secondary user systems to achieve the maximum energy efficiency in a cognitive network based on hybrid spectrum sharing, meanwhile considering the maximum transmit power, user quality of service (QoS) requirements, interference limitations, and primary user protection. The optimization of energy efficient sensing time and power allocation is formulated as a non-convex optimization problem. The Dinkelbach's method is adopted to solve this problem and to transform the non-convex optimization problem in fractional form into an equivalent optimization problem in the form of subtraction. Then, an iterative power allocation algorithm is proposed to solve the optimization problem. The simulation results show the effectiveness of the proposed algorithms for energy-efficient resource allocation in the cognitive network.

Queueing Analysis of Performance Measures Under a New Configurable Channel Allocation in Cognitive Radio

To help achieve optimal channel allocation for a cognitive radio network with multiple channels and multiple users, the authors propose a queueing analytical framework for implementing a configurable channel allocation method. Various allocation scenarios can be captured by the allocation method under different parameters. The influence of the parameters under different environmental parameters and system settings on the performance measures is investigated by the proposed framework. System settings such as imperfect spectrum sensing, adaptive modulation and coding scheme, automatic repeat and request, various primary user activity patterns, and finite secondary user buffer size are considered to make the proposed model practical. The procedures to derive performance measures, such as average queue length, packet loss rate, throughput, and average packet delay, are presented. Numerical results that reveal the relationship between various performance measures and the channel allocation method parameters under different channel conditions and secondary user system settings are shown. The allocation method and the analytical framework would be useful to help achieve optimal performance and evaluate different allocation methods.

Spectrum access strategy for cognitive wireless networks sensing part of channels

To effectively balance contradiction between sensing time of access channel and total throughput of channel in secondary user system of cognitive wireless network, a kind of spectrum access strategy sensing part of channels is proposed. The Thesis, based on algorithm proposed through single secondary user carrying out transmission on multiple channels of master user at the same time, takes total throughout of channel as objective function; on one hand, it is related to transmission rate, on the other hand, it is related to selection of sensing time and sensing channel. The algorithm assumes secondary user detects channel through perception in order and chooses certain suitable channel by using optimum stopping theory to perceive. It avoids sensing all channels, meanwhile, the throughput is greater. Through comparison with simulation analysis of HC-MAC (Hardware-constrained Cognitive MAC) algorithm, the algorithm avoids sensing all channels and lowers expenditure, meanwhile, the throughput is greater, which make it obtain obvious advantage on performance.

UWB Sensing Antenna, Reconfigurable Transceiver and Reconfigurable Antenna Based Cognitive Radio Test Bed

For the effective use of available frequency bandwidth, cognitive radio technology is evolving in the last few years. In this, spectrum is shared between primary and secondary users. Secondary users also called as unlicensed users, makes use of part of spectrum which is not used by primary or licensed users. Hence secondary user systems must be capable of sensing the spectrum and should be able to reconfigure to transmit at different frequencies. For this it must consists of spectrum sensing circuit and a reconfigurable transceiver consisting of reconfigurable antenna. This paper discuss the single module of reconfigurable transceiver which dynamically allocates two different frequencies 2.4 and 3.1 GHz for transmission. Ultra-wideband patch antenna, spectrum sensing algorithm and reconfigurable patch antenna are also discussed. The module can be modified to transmit at more frequencies in the range 2.4–9 GHz by having reconfigurable devices such as LNAs, power amplifiers, local oscillators, mixers, etc.

干扰温度约束下的一种新的中继选择策略

协作通信中的一个关键问题是如何分配和管理中继节点，尤其在次用户系统受到干扰温度约束条件下，协作方案的设计不仅要最大限度的提高系统性能，而且需要控制次用户系统对主用户系统的干扰。针对这种情况在次用户系统中提出一种基于协作波束形成中继选择策略，该方法以最小化次用户系统中断概率为目标，推导出一个中继选择门限，保证了有限的传输功率只分配给高效的中继链路，从而提高系统传输性能。仿真结果显示，该建议方法优于单中继转发方案和全中继转发方案，能有效降低次用户系统中断概率。One of the key problems in cooperative communication is how to allocate and manage the relay nodes, especially in the secondary user system under the interference temperature constraint. The design of the collaborative scheme should not only maximize the performance of the system, but also need to control the secondary user system’s interference in the primary user system. For this situation, a relay selection strategy is proposed based on the collaborative beamforming in the secondary user system. To minimize the outage probability of the secondary user system, a threshold is determined which only allocates the transmission power to the efficient relay links to improve the transfer performance of the system. The simulation results demonstrate that the proposed strategy can effectively reduce the outage probability of the secondary user system, and more over, it is better than the Single Relay Amplify-and-Forward (SAF) scheme and the All Relays Amplify-and-Forward (AAF) scheme.

Robust L_p-Norm Decoding for BICM-Based Secondary User Systems

The frequency bands used by secondary user systems such as cognitive radio and ultra-wideband (UWB) systems are subject to various forms of non-Gaussian noise and interference including co-channel and narrowband interference caused by the primary user and other secondary users as well as man-made impulsive noise. For secondary user systems employing popular bit-interleaved coded modulation (BICM) we propose a robust Lp-norm metric for Viterbi decoding to overcome the harmful effects of non-Gaussian noise and interference. For the resulting system, we derive an approximate upper bound on the bit error rate (BER) and a general analytical expression for the asymptotic BER valid for all practically relevant types of fading, including Rayleigh, Ricean, Nakagami-m, Nakagami-q, and Weibull fading, and all types of noise and interference with finite moments. Simulation and analytical results show that, in non-Gaussian noise and interference, the proposed Lp-norm metric yields large performance gains over the conventional L2-norm metric and outperforms erasure decoding.