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A low complexity resource allocation scheme is proposed for an underlay scheme over OFDM-based multi-user cognitive radio system. The resource allocation problem in an OFDM-based CR system includes subcarrier, power and bit allocation that is a combinational optimization problem. In the proposed scheme, subcarrier and power allocation is accomplished in two separate stages. The power allocation problem...
This paper investigates joint relay selection (RS) and power allocation (PA) in cognitive radio (CR) systems, in which relay nodes operate in amplify-and-forward (AF) mode. In contrast to the conventional schemes, we take into account the performance of the secondary user (SU) which acts as the relay. A two-step optimization scheme is proposed to maximize system throughput with minimum rate guarantees...
In this paper, we address the issue of power allocation in a relay-based cognitive radio network. The power allocation approach analyzed here maximizes the system throughput while maintaining interference to a tolerable limit. We modify the approach to achieve a higher convergence rate. Later we further propose a near optimal power allocation approach that significantly lowers the computational complexity...
The rationale of this work is that the incumbent primary user (PU) of a cognitive radio (CR) system relays its traffic through the secondary user (SU) network for an enhanced throughput. In return, it rewards the SUs with an incentive time during which they can use the complete licensed bandwidth to transmit their own data, without the need for spectrum sensing. With the objective of maximizing the...
We propose a variable-rate variable-power M-level quadrature amplitude modulation (MQAM) scheme employed under delay quality-of-service (QoS) constraints over spectrum-sharing channels. An underlay cognitive radio system, with one primary user and a secondary user, with constraints on interference leakage imposed by the primary receiver is considered. The transmission parameters of the secondary user...
As the development of telecommunication technology, the cognitive radio is considered to be an effective way, and become the research focus in the past years. At the same time, the Auction Channel Allocation Mechanism for cognitive radio system which is validated is an effective and convenient way to solve the problem in cognitive radio. In this paper we discuss the problems encountered in the Auction...
Cognitive radio is an emerging research topic aiming to improve spectrum usage. This paper deals with resource allocation problem in OFDMA cognitive radio systems. Previous research that has dealt with this problem assume perfect knowledge of the channel state information (CSI) and few works consider the quality of the spectrum sensing in the resource allocation issue. The proposed approach combines...
In this paper, we present a low-complexity power allocation scheme for non-regenerative (amplify and forward) relaying in cognitive radio systems. The main objective of the power allocation is to maximize the signal to noise ratio (SNR) at the destination under the constraint of acceptable interference to the primary users (PU). In this paper, we propose an iterative power allocation using SNR upper...
Secondary users, which base on the spectrum pricing function given by primary users, can compete the spectrum resource with each other through game theory in cognitive radio system. It can be divided into cooperative game and noncooperative game according to whether the secondary users cooperate or not in the spectrum sharing. In this paper, based on the Nash bargaining in cooperative game, an improved...
In this paper, we propose a fast genetic algorithm (FGA) for bits allocation in OFDM based cognitive radio systems. The bits allocation in OFDM subchannels is modeled as a binary sequences search problem, which is NP-Hard. First, the bits with the least cost in each subchannel are formulated as a possible solution with a predefined probability. Then a genetic-like algorithm is used to search the current...
In this paper, we consider a cognitive radio system with one primary (licensed) user and multiple secondary (unlicensed) users. Considering the interference temperature constraints, the secondary users compete for the available spectrum so as to satisfy their need for communication. Borrowing the concept of price from market theory, we develop a decentralized Stackelberg game formulation for power...
In this paper an adaptive resource allocation algorithm in OFDMA based cognitive radio (CR) system is proposed that not only meets the quality of service (QoS) of real-time (RT) services but also increases the dynamic capacity of the system. In contrast to existing algorithms for multi-user OFDM systems which are unable to guarantee maximum sum data rate when applied to CR system in real-time, the...
In cognitive radio systems, in order for the secondary users to opportunistically share the spectrum without interfering the primary users, an accurate spectrum measurement and a precise estimation of the interference at the primary users are necessary but are challenging tasks. Since it is impractical in cognitive radio systems to assume that the channel state information of the interference link...
This paper addresses power allocation between channels in a cognitive radio system, and uses insights from information theory to compare the total capacity available using a fully distributed power allocation scheme with an optimum scheme based on perfect knowledge of all links. First the equations for optimum allocation are obtained, leading to an extension of the water-filling power allocation,...
In this paper, we proposed a resource scheduling scheme for OFDM based Cognitive Radio (CR) systems. The available spectrum resources detected by certain sensing method are separate into "white space" and "grey space". Different from other researches which aim at only allocating white space spectrums to cognitive users, our discussion present a proper solution to make use of grey...
In the cognitive networks, one of the major concerns is the fact that cognitive users may cause harmful interference to licensed users. And the fairness of resource allocation is another important problem in this network. This paper focuses on a joint channel and power allocation algorithm that can both protect licensed users and guarantee the fairness of spectrum sharing among cognitive users. This...
Cognitive radio technology has arisen as a hot topic in wireless communication in recent years. Special spectrum allocation algorithms are essential to adapt to the time-space varying characteristics of wireless spectrum in cognitive networks. In this paper, we study and simulate the guard channel policy proposed by Huang Zhen, etc. We find that the blocking probability of secondary users is relatively...
Cognitive radio is a great candidate for creating a new fundamental network architecture improving the efficiency of frequency resource usage. In a heterogeneous network, a cognitive radio system composed with a multi-transmission link is required to select the optimized wireless access network to the terminal. To make the proper selection of a wireless access network to the terminal, the relative...
Cognitive Radio provides a paradigm to enable an efficient and performing use of spectrum resources. Several challenging issues are still to be solved in order to fully exploit the CR potentials. One of these is the development of efficient distributed power allocation methods to be performed by the independent decisional entities of the network. Game Theory, and in particular S-Modular Games, are...
This paper addresses power allocation between channels in a cognitive radio system, and uses insights from information theory to compare the total capacity available using a fully distributed power allocation scheme with an optimum scheme based on perfect knowledge of all links. First the equations for optimum allocation are obtained, leading to an extension of the water-filling power allocation,...
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