Optimal Power Allocation for Relay Assisted Cognitive Radio Networks.
ABSTRACT In this paper, we study the optimal power allocation of wireless relay nodes which are used in the secondary user (SU) communication of a cognitive radio (CR) network. We consider the behavior of transmitting powers of SUs where those powers are limited to the tolerable interference as seen by the primary user (PU) communication. To improve the performance of the secondary communication based on minimizing the outage probability, we re-formulate the power allocation problem with a new set of constraints. These are obtained by considering the co-channel interference generated by the SU communication to the PU communication. The power allocation problem is solved for both regenerative and non regenerative relay models under Rayleigh fading conditions. SU communication with N number of relays is discussed and compared. The outage probability of SU communication is limited by the interference power threshold (IPT) constraints of PUs and is affected significantly by the IPT levels of PUs.
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ABSTRACT: This paper proposes linear precoder-decoder schemes for a multiple-input multiple-output (MIMO) underlay device-to-device (D2D) communication system by considering two D2D modes; two-way relaying based D2D and direct D2D. The D2D communication takes place in the same spectrum as the cellular communication. In the two-way relaying based D2D mode, the relay uses physical layer network coding (PNC). The precoder-decoder design is based on minimizing mean square errors (MSE), which is useful to mitigate interference, and to improve the performance of both D2D and cellular communications. Distributed and centralized algorithms are proposed considering bi-directional communication in both D2D and cellular communications. In the direct D2D mode, a similar MSE procedure is adopted, and exact solutions are derived for precoder-decoder matrices. In the numerical results, the optimality and convergence properties of the proposed algorithms are analyzed. Additionally, the system performances are investigated with interference thresholds, and maximum available power at the nodes. Two transmit mode selection schemes are considered as dynamic and static selection schemes. Finally, these selection schemes are investigated over an XY grid by varying the position of a given device. The results reveal that the PNC two-way relaying based D2D mode extends the coverage area of D2D communication.IEEE Transactions on Communications 10/2014; · 1.75 Impact Factor
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ABSTRACT: This paper proposes an optimal strategy for power allocation algorithm for source and relay nodes in multihop cognitive radio network that minimizes the outage probability of data transmission while meeting the constraints of interference to primary user and total transmit power of cognitive radio users. Overall objective is to enhance the network lifetime along with an increase in sum (total) transmission capacity. Extensive simulations are done for both energy aware (EA) and non-energy aware (NEA) power allocation schemes. Simulation results show that EA based power allocation not only enhances network lifetime but also reduces interference to primary user at the cost of slight decrease in sum transmission capacity compared to NEA based scheme.Wireless Communication Systems (ISWCS), 2012 International Symposium on; 01/2012
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ABSTRACT: This paper considers optimal resource allocation in integrated framework of cognitive radio and ad hoc network. The design problem looks for an optimal solution in power and channel allocation in multihop cognitive radio network (CRN) with linear topology. The overall goal is to minimize outage probability and enhancement in network lifetime, while meeting the limits of total transmit power and interference threshold to primary user (PU) simultaneously. The problem has been solved using standard technique of solving convex optimization problem and weighted bipartite matching. Simulation results show that the proposed scheme not only minimizes outage probability better compared to existing (only) power allocation strategies but also reduces interference to PU and saves sum transmission power of secondary users (SUs). Furthermore, in view of the energy constraints of the nodes in cognitive radio ad hoc networks, the solution is extended to address the issue of the network lifetime improvement. Simulation results confirm that our extended solution offers better network lifetime, although it shows slightly inferior performance in terms of minimizing outage probability compared to our initial solution.Communication Systems and Networks (COMSNETS), 2013 Fifth International Conference on; 01/2013