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This paper proposes a reserved channel based spectrum handover mechanism for cognitive heterogeneous networks (HetNet). To properly handover secondary users from Macro to Femto base stations and maintaining an acceptable protection on the primary users, we propose a priority-based scheme in which several channels are reserved only for handover of secondary users while the rest of channels can be shared...
In this paper, we study the impact of eigenvalue-based spectrum sensing techniques in the achievable throughput of the secondary cognitive radio network. For this analysis, the channel between the primary and secondary users is modeled as a complex Nakagami-m distribution, in order to investigate the effects of not only the channel envelope, but also the novel non-uniform phase distribution in the...
This paper investigates the performance of a Cognitive Radio Network, emphasizing the secondary users performance. Users are modeled by a priority M/G/1 queue, in which primary users have a higher priority than secondary users. The performance of the system is evaluated by a performance metric called Power Metric. We considered that transmissions occur over a Nakagami-m channel model. Different modulation...
This paper studies a decentralized power allocation for uplink random access of secondary users in cognitive network with successive interference cancellation. First, for the additive white Gaussian noise channel, we propose a novel algorithm, which enables to obtain discrete power levels and optimize the corresponding probabilities, iterating per-level from the lowest power level to the highest one...
In this paper, we study secure transmission designs for underlay cognitive radio networks in the present of randomly distributed eavesdroppers. We consider the scenario where a secondary transmitter sends confidential messages to a secondary receiver subject to an interference constraint set by the primary user. We design two transmission protocols under different channel knowledge assumptions at...
In this paper, we consider the problem of optimal opportunistic spectrum access using full-duplex (FD) radios in presence of uncertain primary user (PU) channel statistics and propose a Sensing-and-Selectively-Transmit protocol (SaST). To optimize its throughput, the SU sensing period has to be carefully tuned. However, in absence of the exact knowledge of PU activity statistics, under SaST, the PU's...
In this paper, a cooperative spectrum sharing protocol is proposed for cognitive radio networks (CRNs) which operates in underlay mode with an automatic repeat-request (ARQ)- based primary user (PU) including primary transmitter (PT) and primary receiver (PR) nodes and a bidirectionally communicating secondary user (SU) which consists of the nodes S1 and S2. In ARQ-based PU, ACKnowledgement/Negative-ACKnowledgement...
In a cognitive radio system the failure of secondary user (SU) transceivers to promptly vacate the channel can introduce significant access-latency for primary or high-priority users (PU). In conventional cognitive radio systems, the backoff latency is exacerbated by frame structures that only allow sensing at periodic intervals. Concurrent transmission and sensing using self-interference suppression...
In this paper, we propose a multi-channel full-duplex Medium Access Control (MAC) protocol for cognitive radio networks (MFDC-MAC). Our design exploits the fact that full-duplex (FD) secondary users (SUs) can perform spectrum sensing and access simultaneously, and we employ the randomized dynamic channel selection for load balancing among channels and the standard backoff mechanism for contention...
In this paper, decentralized heuristic access policies are designed for two secondary users (SUs) in an underlay cognitive radio network in which the PU employs Type-I Hybrid ARQ. Exploiting the redundancy in PU retransmissions, each SU receiver applies interference cancellation (IC) to remove a successfully decoded PU message in the subsequent PU retransmissions. There is no central control unit...
It is envisaged that there will be heterogeneous deployment of ultra-dense femtocells overlaying the existing macrocells in an ad-hoc manner to provide enhanced coverage and capacity for the indoor users in the fifth generation (5G) wireless networks. However, this will lead to serious interference between macrocells and femtocells (cross-tier interference) and interference between neighbouring femtocells...
Cognitive radio is emerging as a promising technique to improve the utilization of the radio frequency spectrum in wireless networks. In this paper, we propose a hybrid CR (cognitive radio) system where underlay and overlay CR approaches are combined under SINR (Signal to Interference plus Noise Ratio) constraints. This new access type allows to optimize the spectrum sensing time with throughput improvement...
We study the problem of optimizing the performance of cognitive radio users with opportunistic real-time applications subject to primary users quality-of-service (QoS) constraints. Two constrained optimization problems are formulated; the first problem is maximizing the secondary user throughput while the second problem is minimizing the secondary user average delay, subject to a common constraint...
The two major concerns of the wireless communication system are throughput of the network and underutilization of wireless channels. Opportunistic routing (OR) aims at improving the former and coping with the latter. Due to the unreliable characteristics of such channels, traditional routing achieves poor throughput. Since traditional routing arbitrarily selects high lossy links among diverse paths...
This paper assesses the communication between smart-meters and aggregators as secondary users that transmit their data over the primary uplink channel. We assume: directional antennas are employed in the meter-aggregator link, secondary users transmit with limited power, meters' transmissions are randomized to avoid packet collisions, and an outage constraint for the secondary links' to guarantee...
One important issue associated with spectrum management in heterogeneous cognitive radio network is: how to appropriately allocate the spectrum to the secondary senderdestination (S-D) pair for sensing and utilization. In this work, the authors investigate the spectrum allocation problem under a more practical scenario, taking the heterogeneous characteristics of both secondary S-D and PU channels...
Recently in cooperative spectrum sensing, there are many researches on designing strategies for the optimization of the length of the sensing time (as a part of the total frame length) while fulfilling the objective of achieving certain level of protection of primary users. The performance of cooperative spectrum sensing scheme is greatly affected by the length of the sensing time selected or calculated...
In this paper, a cooperative cognitive radio network (CRN) with energy harvesting capabilities of its secondary users is considered. Specifically, cooperative spectrum sensing and multi-antenna beamforming are employed to improve the sensing performance and the energy transfer efficiency, respectively. In our approach, a homogeneous CRN scenario is studied where the optimal sensing probability of...
Cognitive Radio is a promising solution for the problem of spectrum under utilization. Cognitive Radio Network consists of licensed(Primary) and unlicensed (Secondary) users. Secondary users can occupy the licensed bands till the arrival of a primary user. Due to the features of cognitive radio network the TCP performance is greatly affected. In this project, intra-flow network coding and Dynamic...
In order to handle the cross-tier and co-tier interference effectively for LTE-A two-tier heterogeneous network, we propose a CSGC algorithm based partial spectrum sharing scheme using cognitive radio (CR) technique. In this paper, Radio resources are divided into three parts: macro-dedicated part, shared part and femto-dedicated part. Simulation result shows that the proposed scheme not only solves...
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