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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, we propose a cognitive Go-Back-N Hybrid Automatic Repeat reQuest (CGBN-HARQ) scheme for a cognitive radio (CR) system to opportunistically transmit data over a primary radio (PR) channel. We model the activity of PR users (PRUs) occupying the PR channel as a Markov chain with two states: `ON' and `OFF'. In order to use the PR channel, the CR system first senses the availability/unavailability...
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, we study the performance of hybrid cognitive radio systems that combine the benefits of interweave and underlay systems by employing a spectrum sensing and a power control mechanism at the Secondary Transmitter (ST). Existing baseline models considered for performance analysis assume perfect knowledge of the involved channels at the ST, however, such situations hardly exist in practical...
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...
This work considers a system with two energy harvesting (EH) nodes transmitting to a common destination over a random access channel. The amount of harvested energy is assumed to be random and independent over time, but correlated among the nodes possibly with respect to their relative position. A threshold-based transmission policy is developed for the maximization of the expected aggregate network...
We study the probability of error optimization problem in collaborative spectrum sensing (CSS) with limited time and energy resources in energy harvesting cognitive radio (CR) networks. The frame structures for sensing and data transmission, if the spectrum is identified as vacant, are both supposed to be fixed. This implies that the time resource dedicated for CSS is limited and shared between spectrum...
The fifth-generation (5G) mobile network is facing severe challenges of the traffic demand surge and spectrum scarcity. To improve the network capacity and data rate, the deployment of Long Term Evolution (LTE) cellular system on unlicensed band is considered as one of the promising solutions. But the interference problem among LTE and WiFi system on the same unlicensed band hinders the deployment...
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...
Internet of Things (IoT) is considered to be the next revolution in the field of wireless communications. This concept involves mapping of physical world to virtual (cyber) world. It is achieved by interconnecting devices having sensing capabilities using unique addressing scheme and passing their collective information to the IoT cloud. However at present, these devices belonging to different technologies...
We study a collaborative spectrum sensing (CSS) problem with limited time and energy resources in cognitive radio (CR) network. Time duration of sensing and data transmission, if the spectrum is identified as vacant, are both supposed to be fixed. This implies that the time resource dedicated for CSS is limited and shared between results reporting time (which depends on the number of sensing users)...
Many spectrum sensing techniques have been proposed to allow a secondary user (SU) to utilize a primary user's (PU) spectrum through opportunistic access. However, few of them have considered the tradeoff between accuracy and energy consumption by taking into account the selfishness of the (SUs) in a distributed network. In this work, we consider spectrum sensing as a game where the payoff is the...
Recently underwater acoustic sensor networks with autonomous underwater vehicles (AUVs) have been applied in various areas, such as ocean data collection, marine environment monitoring and military surveillance, which static networks can hardly accomplish. In order to achieve the missions, effective communication is crucial and needs the guarantee of medium access control (MAC) protocol, which schedules...
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 the best solution for spectrum scarcity and spectrum underutilization over wireless communication challenges. It empowers secondary users to use primary user's spectrum without any interference. In this paper, a new approach of artificial neural network based spectrum sensing is proposed which senses the availability of a vacant channel in the primary user's spectrum and allocates...
An Underwater Sensor Network (UWSN) has many unique features that makes it different from terrestrial network. This includes lower bandwidth, longer propagation delay, dynamic topology, high error rate, and energy constraint. To overcome the limitations of such an environment, opportunistic routing has recently attracted much attention due to its ability to improve the performance of UWSNs in terms...
Wireless communications are currently undergoing very rapid development, and as a result, the demand for wireless spectrum has been growing dramatically. In this regard, future wireless solutions have to meet multiple needs in terms of spectrum efficiency (SE). Both 5G, the next generation of mobile networks, and Cognitive Radio (CR) came as promising new technologies dealing with those requirements...
Wi-Fi wireless communication has become a basic service in public areas. But the quality is not stable due to the factors that are influenced by 1) a limited number of channels results in access interference, 2) various transmission ranges, carrier sensing and hidden terminal starvation problems, and 3) the barriers reduce the quality of transmissions. This work aims to explore and analyze the factors...
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