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Energy efficient cognitive radio networks can simultaneously improve spectrum efficiency (SE) and energy efficiency (EE) of wireless communication networks. This paper studies energy efficient spectrum sensing interval, spectrum sensing energy and transmit power allocation scheme of the secondary user (SU) in CR networks. The EE maximization problem subject to the transmit power constraint and average...
We consider a two-way cognitive radio relay network where two secondary users (SUs) can simultaneously transfer energy and information to a relay. Then, a joint optimization algorithm for power allocation and energy cooperation is proposed. The algorithm proves that the formulated throughput maximization problem is a convex optimization problem. Next, we decompose the formulated problem into a power...
Cognitive radio (CR) is a promising method suitable for solving inefficiency spectrum policy by opportunistically identifying the vacant portions of the spectrum that are used by primary users (PUs). In cognitive radio ad hoc networks (CRAHNs), secondary users (SUs) can opportunistically utilize the spectrum that is available from PUs. In this paper, we propose a neighbor-aware distance estimated...
Cognitive radio (CR) is an effective way to improve the utilization of spectrum resource. This paper focuses on the resource allocation in cooperative relay cognitive radio networks and proposes an optimized resource allocation algorithm. In the algorithm, when the channel between the primary source and destination is good, the primary user (PU) selects a best sub-channel to transmit its data directly,...
The paper presents a method of monitoring the basic parameters of cognitive mobile ad hoc network (MANET) with opportunistic access to the spectrum. The collected parameters are based on metrics from different communications layers, combined into single utility function, being a global indicator of the network health. The proposed method was tested and validated using a real time cognitive radio network...
Queuing Theory was ultimately applied to improve the radio resource sharing in cooperative cognitive radio networks. It indeed gives a better model of storing and transmitting packets of both Primary User (PU) and Secondary User (SU). It especially helps emulate the cooperative radio resource sharing between these two users. With such cooperation protocols, the PU allows the SU to share his spectrum;...
In this work, we use a new technique called tagged user approach (TUA) to analyze the performance of S-Aloha MAC protocol for CR users widely used in wireless communication. This new technique assumes that the channel is symmetric so that statistical equilibrium exists for all users. By adding two more realistic assumptions, we analyze the stability of the random chosen user and after extrapolate...
In this paper, cognitive machine to machine (CM2M) gateway in e-healthcare systems are presented by accessing several channels via periodic sensing and spectrum handoff. An optimal energy efficient spectrum management mechanism with multiple thresholds is proposed. The developed mechanism aims to reduce energy consumption in the system by optimizing the spectrum sensing and channel switching, while...
This paper proposes a new spectrum access algorithm based on the Partially Observable Markov Decision Process (POMDP) for Cognitive Radio Networks (CRNs). The proposed algorithm uses the Maximum Likelihood to estimate the licensed channel state transition probabilities based on historical statistics information of the channels. Then, the number of channels sensed by the secondary users in each time...
In cognitive radio (CR), changing the primary user's status diminishes the achievable throughput for secondary user. Traffic of primary user is inversely proportional to throughput of secondary user. Increasing sensing time increases the primary user protection, but has a negative effect on the throughput of secondary user. Solving the dilemma of sensing-throughput tradeoff is to find the optimal...
In this paper we present a novel dynamic spectrum sensing and access model in cognitive radio networks. This model allows secondary user (SU) to sequentially sense two times if necessary due to the false alarm, and choose different accessing manner according to the sensing result. In practice, sensing results often affect the data transmission in cognitive radio systems. Therefore, a hybrid interweave/underlay...
In this paper, energy efficient transmit antenna selection in underlay cognitive radio (CR) multiple-input multiple-output (MIMO) systems from a cross layer perspective, is investigated. Conventional energy efficient antenna selection optimizes an energy efficiency (EE) metric defined in terms of the system capacity and energy consumption, making it a physical layer criterion. In this work, we propose...
The cognitive radio network is intelligent in adapting to the dynamic network environment, and it also provides a new way to solve the application limitation of nowadays MAC protocols. In this paper, an adaptive MAC protocol selection scheme based on machine learning is proposed for cognitive radio networks. This scheme can combine the respective advantages of the competitive protocols and non-competitive...
Standardization activities have already begun on 5G to support very high system requirements. A common consensus toward achieving these targets is to permit transmission over a wide spectrum range. The departure from a dedicated licensed-only spectrum regime to a shared spectrum model poses new challenges for next generation mobile communication systems. Cognitive Radio Technologies is an enabler...
In this paper, we improve throughput performance of a cognitive radio network through a proposed dual-level sensing strategy. Throughput performance of secondary users cannot be enhanced while providing higher priority to protect primary users from secondary user interference. Therefore, we propose a novel multiple access scheme based on dual-level sensing strategy by which both the interference protection...
In this paper, we investigate fundamental throughput and delay tradeoffs in cognitive radio networks (CRN) with a primary user (PU) and a cooperative secondary user (SU). Considering the user fairness, we propose a novel cooperation scheme, where the PU transmits packets with a probability of α instead of always occupying the spectrum, in exchange for the SU's cooperation. The unauthorized SU can...
In this paper, we propose an opportunistic scheduling algorithm for secondary users (SUs) in a dynamic spectrum access network. Scheduling is performed at the beginning of each super-frame where appropriate channel(s) are assigned to the SUs based on the expected throughput that each channel provides. We compute the expected throughput for each channel on specific time slots in a super-frame based...
In this paper, we study spectrum overlay access to share spectrum between primary users (PUs) and secondary users (SUs). Our goal is to maximize the average throughput by optimal power allocation within finite time duration. To do this, we formulate this optimization problem as a Markov Decision Process with continuous state. An approximate value method with pre-allocation mechanism is proposed, which...
In the non-time-slotted cognitive radio networks (CRNs), the synchronization between PUs and secondary users (SUs) cannot be guaranteed, resulting in two challenging problems: the reactivation-failure of PUs and the frequently unexpected hand-offs among SUs. The reactivation-failure of PUs is the incident that the SUs cannot detect the PUs' reactivation when the SUs are occupying the channels to transmit...
We consider a cognitive radio network, where primary users have priority over the spectrum resources, and secondary users can exploit the unused resources through channel sensing. Due to sensing inaccuracy, the secondary traffic may obstruct the primary traffic. A penalty for collision has been used to protect the primary traffic, which is often designed to provide a fixed per-collision compensation...
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