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In this paper, minimum MSE based interference alignment (IA) algorithm is developed for the interfering broadcast channel (IBC), which models the multi-cell downlink system, underlying cognitive radio, device-to-device and other scenarios. The IA precoders and decoders are computed to minimize the MSE. Cascade design is used for IA precoder design, where the first component precoder is obtained by...
In this paper, we propose a new full-duplex relay-assisted cognitive radio system model with an adaptive decoding algorithm at the secondary user, in order to maximize both primary and secondary achievable rates. We consider the uplink transmission and we compare the system's achievable rates obtained with both amplify-and-forward and decode-and-forward relaying in the single-carrier case. Then, we...
In this paper, an underlay based cognitive radio network (CRN) consisting of a secondary base station (SBS), a secondary receiver (SR), an energy harvesting node (EHN), and a primary transmitter-receiver (PT-PR) pair, is considered. The EHN is assumed to have a power splitter (PS) at the receiver to decode information and harvest energy simultaneously from the SBS transmission, thus reducing the secrecy...
In this paper, a new cooperative spectrum sharing protocol that employs space-time block coded spatial modulation (STBC-SM) at the secondary user (SU), is proposed for overlay cognitive radio (CR) networks. STBC-SM is applied at the secondary transmitter (ST) which transmits its data by both modulated symbols and antenna combinations while conveying PU's data only by modulated symbols. This protocol...
In this paper, we consider a cognitive two-way relay system with multiple relay nodes and multiple primary receivers over Nakagami-m fading channels. Relay nodes process signal following selective decode-and-forward (DF) relay technique. The opportunistic relay selection is used to choose the best relay. We derive the exact closed-form expression of the overall outage probability over Nakagami-m fading...
In this paper we implement a turbo based Overlay Cognitive radio Z-channel with Trellis shaping, where the primary and cognitive users transmits and receives concurrently, utilizing the same spectrum. We ensure that bit error rate (BER) performance of the Primary does not degrade even in the presence of cognitive user. We derive bit error rate BER curves for both users, and show significant improvement...
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...
In this paper we study secure communications with weak secrecy constraint in a cognitive radio channel, where the secondary receiver is treated as a potential eavesdropper with respect to the primary transmission. The primary's secrecy rate and the transmission scheme should be kept unchanged whether the secondary users transmit or not. We derive the achievable rate of the discrete memoryless multi-phase...
This article considers a model of cooperative spectrum sharing between primary and secondary systems in which transmission occurs in two phases. In this scheme, we introduce that a single secondary transmitter, ST, employs a quadrature-phase-based signal to present the secondary message, while the primary message is presented by an in-phase-based signal. This allows simultaneous spectrum sharing without...
In this paper, we propose a dirty paper coding (DPC) scheme that uses trellis shaping for the overlay cognitive radio channel, where a cognitive user and a primary user transmit concurrently in the same spectrum. Interference of the primary user is assumed to be known at the cognitive transmitter non-causally. Based on this knowledge, the shaping code selection, as a key feature of the proposal, is...
In this paper, we propose a dirty paper coding (DPC) scheme for the cognitive radio channel where multiple cognitive users coexist with a primary user. The cognitive transmitter is assumed to know the primary signals non-causally and is equipped with two antennas, of which each transmits to a single-antenna receiver. In our proposal, zero-forcing DPC is employed to cancel the interference not only...
In this paper, we investigate the maximum throughput of a saturated rechargeable secondary user (SU) sharing the spectrum with a primary user (PU). The SU harvests energy packets (tokens) from the environment with a certain harvesting rate. All transmitters are assumed to have data buffers. In addition to its own traffic buffer, the SU has a buffer for storing the admitted primary packets for relaying;...
The task of detecting and mitigating Cognitive Radios (CRs) operating as constant jammers in a Cognitive Radio network (CRN) can be very daunting. The CR constant jammers prey on the adaptable functionalities of CRN so as to cause serious denial of service to the users of the network. In addition, these jammers are capable of introducing value faults in pathological cases as a result of being able...
As a promising solution to the spectrum scarcity problem, cognitive radio (CR) has received much attention recently, The key component of CR is the spectrum sensing technique that can detect the idling spectrum of the authorized user. Currently, the accuracy of spectrum sensing remains a significant constraint that limits the practical application of CR. In this paper, we propose an enhanced spectrum...
In this paper we address the problem of allowing secondary access to the spectrum assigned to a broadcast operator. We assume that the secondary transmitter knows of the primary message but is not able to apply interference cancellation techniques due to the lack of channel state information. Thus, interference cancellation can only be performed at the secondary receivers, provided they are able to...
In this paper, we consider the Gaussian cognitive broadcast channel in which the primary user communicate to the primary receivers and the cognitive user has noncausal knowledge of the primary radio's codeword and wishes to communicate to two receivers. We characterize the largest rate region at which the cognitive user could reliably communicate under the constraints that no rate degradation is created...
Recently, substantial attention has been paid to improve the spectral efficiency of communication setups using different spectrum sharing techniques. This paper studies the ergodic achievable rate of spectrum sharing channels in the case where the primary licensed user is equipped with a sequential decoder, while there is no connection between the transmitters. Assuming Rayleigh block-fading channels,...
In this paper, we propose, analyse and compare three different methods for opportunistic spectrum sharing access when the primary users implements an Incremental Redundancy (IR) type Hybrid Automatic ReQuest (H-ARQ) protocol. The first method consists in allowing the secondary user to communicate only during the first primary transmission round of the IR H-ARQ protocol. In this scenario, if the the...
The capacity region of the Gaussian cognitive interference network consisting of a primary multiple access channel and a secondary point-to-point system is considered. Its capacity region with weak interference is known. In this paper, the capacity region of a sub-regime of the strong interference regime is studied. An outer bound on the capacity region of this setup with strong interference is derived...
Cognitive radio (CR) technology provides great flexibility in spectrum utilization with orthogonal frequency-division multiplexing (OFDM) as its candidate transmission technique. In this paper, we propose a simple spectrum shaping scheme for OFDM-based CRs to enhance spectral compactness and ensure bandwidth efficiency. By mapping antipodal symbol pairs onto adjacent subcarriers at the edges of the...
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