Convolutive Superposition for Multicarrier Cognitive Radio Systems

Abstract

Recently, we proposed a spectrum-sharing paradigm for single-carrier cognitive radio (CR) networks, where a secondary user (SU) is able to maintain or even improve the performance of a primary user (PU) transmission, while also obtaining a low-data rate channel for its own communication. According to such a scheme, a simple multiplication is used to superimpose one SU symbol on a block of multiple PU symbols. The scope of this paper is to extend such a paradigm to a multicarrier CR network, where the PU employs an orthogonal frequency-division multiplexing (OFDM) modulation scheme. To improve its achievable data rate, besides transmitting over the subcarriers unused by the PU, the SU is also allowed to transmit multiple block-precoded symbols in parallel over the OFDM subcarriers used by the primary system. Specifically, the SU convolves its block-precoded symbols with the received PU data in the timedomain, which gives rise to the term convolutive superposition. An information-theoretic analysis of the proposed scheme is developed, which considers different amounts of network state information at the secondary transmitter, as well as different precoding strategies for the SU. Extensive simulations illustrate the merits of our analysis and designs, in comparison with conventional CR schemes, by considering as performance indicators the ergodic capacity of the considered systems.

Joint Resource Optimization for Orthogonal Frequency Division Multiplexing Based Cognitive Amplify and Forward Relaying Networks

“…In our paper, both relaying link and direct link are included and the selection criteria are provided according to the strength of both links. Secondly, different goals: although some work involves both links, their goal is to calculate accurate performance formulas rather than resource optimization [12,18,19]. However, what we are concerned about is the joint optimization of power allocation and subcarrier pairing.…”

“…However, what we are concerned about is the joint optimization of power allocation and subcarrier pairing. Thirdly, different system models: different from most works [18][19][20][21][22], where a primary user selected a secondary user acting as a relay to help the primary user forward the message. However, in our model, the secondary user doesn't participate in the communication process of the primary user as long as the secondary user meets the interference management condition.…”

SenPUI: Solutions for Sensing and Primary User Interference in Cognitive Radio Implementation of a Wireless Sensor Network

“…Most recently, NOMA has been proposed in numerous systems of cognitive radio implementation, that is, amplifyand-forward scheme for spectrum sharing in cognitive radio channels [2], convolutive superposition for multicarrier cognitive radio systems [3], power allocation for interference alignment [4], Cooperative Non-Orthogonal Multiple Access in Cognitive Radio [5], and Advances and Future Challenges in Non-Orthogonal Multiple Access [6].…”

Adaptive Energy Efficiency Maximization for Cognitive Underwater Acoustic Network under Spectrum Sensing Errors and CSI Uncertainties

“…Generally, there exist three access strategies in CUAN: underlay, interweave, and overlay [3]. In underlay strategy, secondary user (SU) can always share the same channel with primary user (PU) conditioned that the SU interference to PU is below the threshold, and the condition has recently been relaxed by convolutive superposition method [4]. In the interweave approach, SU opportunistically transmits the data with two power levels according to the channel state (e.g., busy or idle).…”