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The object of this work is to improve secrecy capacity of primary user (PU) as well as spectrum utilization. To this end, we present a cognitive relaying enabled efficiency and physical-layer security preserving (CREEP) framework, in which secondary users (SUs) are allowed to perform secondary transmissions. By enabling dual-polarized antenna and leveraging polarization processing at SUs, signals...
In this work, we present a polarized-MIMO enabled cooperation framework between multiple secondary users (SUs) and a single primary user (PU). To achieve a two-phase cooperative communication paradigm, some state-of-the-art polarization signal processing techniques, e.g., polarization zero-forcing and oblique projection polarization filtering, are introduced to address the co-channel interference...
This paper investigates the effects of spectrum sensing errors on the performance of cognitive radio based dynamic spectrum access system (CR-DSA). We first analyze the DSA process with imperfect sensing information by a continuous-time Markov chain (CTMC) model, and then derive the performance metrics with respect to the sensing errors. To alleviate effect of errors in the spectrum sensing process...
Joint transmission (JT) is a promising coordinated multipoint (CoMP) transmission scheme for achieving high downlink capacities in wireless cellular networks of next generation. In this paper, an adaptive scheme, named as partial JT CoMP is presented. This scheme improves the network throughput by dynamically adjusting points involving in jointly transmitting according to the instantaneous channel...
In Long Term Evolution (LTE) networks, Energy-Efficient (EE) and Mobility Load Balancing (MLB) are two important functions to optimize the network performance. In order to deal with the energy consumption in downlink LTE system for unbalanced low load scenarios, we built an effective EE resource allocation optimization model and employed a low complexity method to achieve the goal of the optimization...
A quadrature signaling based two-phase cooperation framework for cooperative cognitive radio networking is proposed. By leveraging the degrees of freedom provided by orthogonal modulation, secondary users are able to relay the traffic of primary users and transmit their own in the same time slot without interference. To evaluate the cooperation performance of the proposed framework, a weighted sum...
Relay node (RN) plays a key role in cooperative communications and RN selection may substantially affects the performance gain. In this paper we address the issue of RN selection while taking into account Medium Access Control (MAC) overhead, which is incurred by not only handshake signaling but also frame retransmissions due to transmission error. We use a theoretical model to analyze the cooperation...
Cognitive radio has been suggested as an efficient method for secondary users to promote the efficient utilization of spectrum. Meanwhile, Cooperative relay allows different users or nodes to share resources and to create collaboration through distributed transmission in a wireless networks. The combination of Cognitive radio with cooperative communication could significantly improve the system performance...
Cooperative communication can obtain spatial diversity without using multiple antennas, and thus achieve more reliable transmission or consume less power. Accordingly, a new cooperative MAC mechanism in wireless networks, the DCMAC, is proposed in this paper. The DCMAC makes full use of the broadcasting characteristics of wireless channel to obtain channel information, chooses the most suitable cooperative...
Based on the oblique projection operators, a novel method for interference suppressing named oblique projection polarization filter (OPPF) in the polarization domain is proposed, which is valid for nonorthogonal polarization filtering or projecting. After discussing the fundamental principle of the proposed OPPF in detail, simulation results are given to illustrate the suggested scheme is suitable...
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