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In this paper, we presented a fairness-aware scheduling scheme in OFDM-based cognitive radio networks. Our objective is to maximize the systems energy efficiency while maintain the fairness among secondary users. In addition, many factors will be considered such as the channel quality, the interferences taken to the primary system and the total transmission power of the cognitive radio system. The...
One of the major challenges in Dynamic Spectrum Access (DSA) systems is to guarantee a required level of Quality of Service (QoS) to secondary users of the spectrum. In this paper, we propose efficient algorithms for deriving optimal policies for the sensing / transmitting trade-off in hardware-constrained DSA systems. Unlike previous approaches which seek to maximize mean data rate for the secondary...
According to the peak hours of the day, the number of sensed primary users (PUs) and also requesting secondary users (RSUs) will be dramatically increased. Since the radio spectrum is a limited resource, efficient spectrum management techniques on cognitive radio is necessary to manage all PUs, active secondary users (ASUs) and RSUs where all three types of the users have unknown activity ratios....
Allowing Secondary Users (SUs) to access the licensed spectrum without causing harmful interference to the Primary Users (PUs) is crucial in enabling the Cognitive Radio (CR) technology. In order to increase the utilization of the spectrum bands, we propose a Dynamic Spectrum Allocation (DSA) algorithm that integrates both interweave and underlay spectrum access schemes. The proposed algorithm will...
In this paper we compare three novel schemes for dynamic frequency allocation and transmission power assignment for cognitive radio networks. These spectrum allocation schemes are based on reinforcement learning and power optimization procedures. We propose the so-called RL+Power and RL+Power Coupled schemes and compare them with an existing constant power scheme. Simulation results show that the...
Secondary Users (SUs) in a Cognitive Radio Network (CRN) face unpredictable interruptions in transmission due to the random arrival of Primary Users (PUs), leading to spectrum handoff or dropping instances. An efficient spectrum handoff algorithm, thus, becomes one of the indispensable components in CRN, especially for real-time communication like Voice over IP (VoIP). In this regard, this paper investigates...
A joint channel assignment and power allocation algorithm is presented for cognitive wireless networks, where primary and secondary users operate over the same frequency band at the same time. In this study, we take into consideration a constraint on the interference from secondary users towards primary users, as well as a constraint on the QoS of secondary users. The problem is formulated as a constrained...
In this paper, focusing on the all-layer involved performance analysis of cognitive radio network for overlay fashion, we propose a joint QoS-aware flow control, routing selection, channel and power allocation with an energy efficiency heuristic algorithm (EeHA). It is a NP-hard problem involving the interactions and restrictions between and across layers; therefore, we put forward a suboptimal solution...
In recent years, Dynamic spectrum leasing (DSL) strategies are studied as a new paradigm for dynamic spectrum sharing (DSS) in cognitive radio networks (CRN's). In traditional spectrum leasing model, the cooperative Secondary Users (SUs) use higher power to transmit their own packets but a lower power to relay the packets of primary user. On the other hand, many existing research work can be characterized...
As a kind of effective way to improve the utilization ratio of the spectrum, more and more attention have been paid to the cognitive radio. This paper proposes an improved cognitive radio spectrum sharing model. In this model, the primary users provide idle spectrum to the secondary users. Secondary users have to pay when they share available spectrum with primary users while using the spectrum. The...
To address the impact of the network dynamics on video streaming, the playout buffer is typically deployed at the receiver. With different buffer storage, users thus have different tolerance to the network dynamics. In this paper, we exploit this feature for channel allocation in cognitive radio (CR) networks. We first model the channel availability as an on-off process which is stochastically known...
As the scarce spectrum resource is becoming overcrowded, cognitive wireless mesh networks express great flexibility to improve the spectrum utilization by opportunistically accessing the authorized frequency bands. One of the critical challenges for realizing such networks is how to adaptively match transmit powers and allocate frequency resources among secondary users (SUs) of the licensed frequency...
In this paper, we apply distributed optimization dynamics of the mutually connected neural networks to RAN selection in heterogeneous type cognitive wireless networks. We evaluate the performance of the proposed approach by implementing it on an experimental heterogeneous wireless network system called Cognitive Wireless Cloud, which supports vertical handover between different radio access networks...
The growing problem of spectrum scarcity and the inefficient spectrum utilization in the licensed bands, are addressed by the emerging Cognitive Radio (CR) paradigm. It is seen that the choice of the spectrum bands, called as spectrum decision, must be organized carefully by considering the challenges in the spectrum availability over time, the short term fluctuations in the availability, and the...
The power control problem is considered with the CR user QoS requirement and the interference to primary user under the threshold which the primary user can tolerate. We model the power control as a optimize problem which each CR user SINR must not less than minimum SINR requirement and the total interference must less than predefined threshold. Firstly we consider the network can satisfy the CR user...
In this paper, we study the dynamic uplink power allocation problem in a multi-cell multi-user CDMA-based cellular cognitive radio (CR) system, in which the concept of hierarchical interference bound is introduced to describe the coexistence of the multi-user interference. We propose a novel differential game-based dynamic power allocation model via two formulated cost functions. Furthermore, we present...
Cognitive radio network (CRN) is designed to improve the low resource utilization problem caused by the fixed spectrum allocation policy used today. In CRNs, secondary users (SUs) sense spectrum holes and adaptively use the frequency band. In this paper, we tackle the Quality of Service (QoS) routing problem in wireless ad hoc CRNs. We consider such factors as available time, frequency bands, transmission...
We propose a novel algorithm to model the dynamic channel allocation problem in cognitive radio networks. In the proposed work, we define a unique model to assign priorities to the secondary users based on the required Quality of Service and on the interference delay to minimize the switching of secondary users. The proposed scheme also mitigates the delay of the licensed primary users due to minimized...
Cognitive radio (CR) introduces a dynamic spectrum access technology. One problem is how to achieve load balancing in time domain. Our objective is to balance the occupied time of slots for a fixed channel dynamically to obtain a user-optimal solution. Spectrum load balancing method with QoS support is proposed based on dynamic feed back theory and hash table (SLBDH). The performance of SLBDH are...
In this paper we consider cognitive radios (CR) that employ orthogonal frequency division multiplexing (OFDM) modulation at the physical layer and present an algorithm for transmitter adaptation subject to specified quality of service (QoS) constraints. The proposed algorithm explicitly considers multipath channels between the CR transmitter and its intended receiver, and performs joint spectral shaping...
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