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This paper proposes a distributed routing mechanism for the multi-hop Cognitive Radio Networks (CRNs) over multiple primary channels. The Secondary Users (SUs) attempts to utilize the channels and minimize their delay along the route while avoiding causing interference to the Primary Users (PUs). In order to address the problem of time-varying channel condition due to the PU dynamics, the route-selection...
In most communication systems, being able to adapt the error protection strength of the physical layer is essential to ensure the functionality of the system in potentially strongly varying conditions. Traditional forward error correction code design focuses on the optimization of codes with a fixed code rate for a worst-case channel condition. So-called rate-compatible codes, on the other hand, are...
We propose the use of constant weight codes to jointly solve the problems of brightness control, data transmission and error correction coding for flicker free Visible Light Communication (VLC) link consisting of white LEDs. This work is unique in that a coding scheme is proposed to address the three problems collectively in single block coding scheme. In addition, recursive as well as iterative algorithms...
This paper concerns developing a low complexity detector for spectrally-efficient Frequency-Division-Multiple-Access (FDMA) multiuser systems based on Continuous-Phase-Modulation (CPM). A class of tree-trellis-search based algorithms is proposed for joint/iterative detection and the complexity is further reduced employing a state-reduction technique based on mismatched filters. The proposed detector...
Starting from Neyman-Pearson criterion, this paper derives an optimal spectrum sensing scheme which exploits spatial diversity among multiple cognitive sensors and temporal diversity among consecutive time slots jointly. In the proposed scheme, the impact of the imperfect reporting channel on the design of the spectrum sensing scheme is effectively integrated. Simulation results show that compared...
The physical layer network coding (PNC) technique exploits the broadcast nature of wireless channels to obtain additional transmission efficiency gains. In this paper, the authors first find and prove that: if we rotate the modulation constellations of multiple sources by proper angles, the points of the equivalent superpositioned constellation at the receiver would cluster into clouds, with each...
We propose a three-message superposition coding scheme in a cognitive radio relay network exploiting active cooperation between primary and secondary networks. The time resource is split into three transmission phases. The first two phases are dedicated to primary communication, while the third phase is for the secondary's transmission. We formulate a throughput maximization problem for the secondary...
Amplify-and-forward (AF) based two-way relaying (TWR) has shown its sum rate advantage over AF based one-way relaying (OWR) in the literature. However, this advantage can not be achieved in some cases. In this paper, we evaluate the sum rates of AF based OWR/TWR and provide the relationship with respect to the relative channel gains and the relative transmit power of the three nodes, i.e., the relay...
In this paper, spectral efficiency (SE) is investigated for cooperative ultra-wideband (UWB) based on-body area networks (OBANs). To optimize SE for single-relay cooperation, an equivalent generic cooperative model in UWB based OBANs is established first. With the proposed model, joint optimal relay location and power allocation for cooperation is then derived to solve the SE maximization problem...
In this paper, a joint resource optimization scheme is designed for orthogonal frequency division multiple access (OFDMA) cellular wireless networks with multi-user cooperation. Joint relay selection, subcarrier allocation and pairing and power allocation algorithms are developed with the objective of maximizing the total capacity of the system considering the quality of service (QoS) requirements...
In this paper, we investigate the problem of joint coordinated resource allocation and power control for LTE-A heterogeneous networks (HetNets) with low-power remote radio heads (RRHs). The scenario we consider is the configuration when RRHs share the same cell ID with the macro BS such that coordinated multi-point (CoMP) operations among transmission points can be performed in a finer granularity...
In current wireless cellular networks, interference has become the major obstacle to high spectral efficiency because of universal frequency reuse. Base station cooperation, also referred to as coordinated multi-point processing or transmission(CoMP), has emerged to mitigate it by estimating and avoiding interference from adjacent base stations(BSs). Through analyzing the scenario of CoMP, we formulate...
In this paper, we consider joint user pairing and frequency allocation with beamforming (BF) assuming per user Quality of Service (QoS) requirements. A single-carrier frequency-division multiple-access (SC-FDMA) transmission employing a zero-forcing (ZF) detector at the receiver is assumed. The BF filter coefficients are jointly optimized with the user pairing and frequency allocation of the users...
This paper studies distributed interference management for femtocells that share the same frequency band with macrocells. We propose a multi-agent learning technique based on distributed Q-learning, called subcarrier-based distributed resource allocation using Q-learning (SBDRA-Q). SBDRA-Q operates under three different learning paradigms: Independent (IL), Cooperative (CL) and Weighted Cooperative...
In this paper, we study joint link scheduling and power control with successive interference cancellation (SIC), aiming at maximizing the α-utility. The joint link scheduling and power control with SIC (PCSIC) problem is formulated to be a mixed-integer non-linear programming (MINLP), which is NP-hard. In order to solve the problem, we first decompose the MINLP into three sub-problem and then propose...
Small-cell networks (SCNs) have emerged as a potential solution to the rapidly increasing demand for high data rates. The base stations (also referred to as access nodes) of the small cells provide service to a group of users through the access link and they are connected to the core/global network via a backhaul link. In this paper, we develop a queuing analytical model that considers the channel...
Aiming at reducing the outage probability of primary users (PU) and obtaining spectrum resources for secondary users (SU), in this paper, we proposed a joint subcarrier and power allocation scheme (JSPA) for reciprocally-benefited spectrum sharing with SUs cooperating with PUs. In JSPA scheme, SUs adopt the decode-and-forward (DF) relaying protocol to help PUs in a two-stage way. Meanwhile, a fraction...
In the literature, the Gaussian input is assumed in power optimization algorithms. However, this assumption is unrealistic, whereas practical systems use Finite Symbol Alphabet (FSA) input, (e.g., M-QAM). In this paper, we consider the optimal power for joint interweave and underlay CR systems given FSA inputs. We formulated our problem as convex optimization and solved it through general convex optimization...
Increasing the cell edge user throughput in the Long Term Evolution (LTE) systems is a relatively new arising research area. The requirement for higher data rates especially at cell edges is becoming ever more pressing as the advantages could help satisfy better Quality of Service (QoS) on an enduser level and mean higher profitability on the operator side. Therefore developing algorithms and techniques...
In this paper, a novel resource allocation with QoS guarantee and fairness (RAQF) scheme is considered for orthogonal frequency division multiple access (OFDMA) two-way relay networks. Multiple source nodes exchange information with the assistance of an amplify-and-forward (AF) relay node (RN) in the presence of an eavesdropper. A joint power allocation, subchannel allocation and subchannel pairing...
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