 Electrical and Electronic Engineering  Research Publications
Electrical and Electronic Engineering  Research Publications
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ItemMaximizing SumRate via Relay Selection and Power Control in DualHop NetworksDayarathna, S ; Senanayake, R ; Evans, J (IEEE, 20220101)In this paper, we focus on the sumrate optimization problem in a general dualhop relay network by considering the joint relay selection and power control in the presence of interference. First, we propose a new relay selection algorithm which has better sumrate performance than the existing relay selection techniques. Then we combine relay selection and power control to propose a novel iterative algorithm based on the tight lower bound approximation which maximizes the achievable sumrate. We also prove that for the special case of twouser networks, binary power allocation is optimum for at least two transmitting nodes. Extensive numerical examples are used to compare the performance of the proposed algorithm and to illustrate the accuracy of the analysis.

ItemChemical Reactionsbased Detection Mechanism for Molecular CommunicationsCao, TN ; Jamali, V ; Wicke, W ; Yeoh, PL ; Zlatanov, N ; Evans, J ; Schober, R (IEEE, 202005)In molecular communications, the direct detection of signaling molecules may be challenging due to the lack of suitable sensors and interference from coexisting substances in the environment. Motivated by examples in nature, we investigate an indirect detection mechanism using chemical reactions between the signaling molecules and a molecular probe to produce an easytomeasure product at the receiver. The underlying reactiondiffusion equations that describe the concentrations of the reactant and product molecules in the system are nonlinear and coupled, and cannot be solved in closedform. To analyze these molecule concentrations, we develop an efficient iterative algorithm by discretizing the time variable and solving for the space variables in each time step. We also derive insightful closedform solutions for a special case. The accuracy of the proposed algorithm is verified by particlebased simulations. Our results show that the concentration of the product molecules has a similar characteristic over time as the concentration of the signaling molecules. We analyze the bit error rate (BER) for a threshold detector and highlight that significant improvements in the BER can be achieved by carefully choosing the molecular probe and optimizing the detection threshold.

ItemCentralized Scheduling with SumRate optimization in Flexible HalfDuplex NetworksDayarathna, S ; Razlighi, M ; Senanayake, R ; Zlatanov, N ; Evans, J (IEEE, 202005)In this paper, we focus on maximization of the instantaneous sumrate in flexible halfduplex networks, where nodes have the flexibility to choose to either transmit, receive or be silent in a given time slot. Since the corresponding optimization problem is NPhard, we design lowcost algorithms that give suboptimal solutions with good performance. We first consider two existing approximation techniques to simplify the sumrate optimization problem: arithmeticgeometric means inequality and another utilising the tight lower bound approximation. We then propose a novel pattern search algorithm that performs close to exhaustive search but with significantly lower complexity. Comparing the performance of the proposed algorithm with respect to existing resource allocation techniques, we observe that our proposed algorithm provides significant sumrate gains.

ItemBinary Power Optimality for Two Link FullDuplex NetworkDayarathna, S ; Senanayake, R ; Evans, J (IEEE, 202005)In this paper, we analyse the optimality of binary power allocation in a network that includes fullduplex communication links. Considering a network with four communicating nodes, two of them operating in halfduplex mode and the other two in fullduplex mode, we prove that binary power allocation is optimum for the fullduplex nodes when maximizing the sum rate. We also prove that, for halfduplex nodes binary power allocation is not optimum in general. However, for the two special cases, 1) the low signaltonoiseplusinterference (SINR) regime and, 2) the approximation by the arithmetic meangeometric mean inequality, binary power allocation is optimum for the approximated sum rate even for the halfduplex nodes. We further analyse a third special case using a symmetric network for which the optimum power allocation is binary, under a sufficient condition. Numerical examples are included to illustrate the accuracy of the results.

ItemTwoWay Communications via Reconfigurable Intelligent SurfaceAtapattu, S ; Fan, R ; Dharmawansa, P ; Wang, G ; Evans, J (IEEE, 20200619)The novel reconfigurable intelligent surface (RIS) is an emerging technology which facilitates high spectrum and energy efficiencies in Beyond 5G and 6G wireless communication applications. Against this backdrop, this paper investigates twoway communications via reconfigurable intelligent surfaces (RISs) where two users communicate through a common RIS. We assume that uplink and downlink communication channels between two users and the RIS can be reciprocal. We first obtain the optimal phase adjustment at the RIS. We then derive the exact outage probability and the average throughput in closedforms for singleelement RIS. To evaluate multipleelement RIS, we first introduce a gamma approximation to model a product of Rayleigh random variables, and then derive approximations for the outage probability and the average throughput. For large average signaltointerferenceplusnoise ratio (SINR) \rho, asymptotic analXsis also shows that the outage decreases at the rate (\log(\rho)/\rho) where L is the number of elements, whereas the throughput increases with the rate \log(\rho).

ItemResource allocation in dynamic DF relay for swipt network with circuit power consumptionPilanawithana, B ; Atapattu, S ; Evans, J (IEEE, 20200227)This paper considers simultaneous wireless information and power transfer (SWIPT) over a dualhop dynamic decodeandforward (DF) relay network with the powersplitting (PS) energy harvesting protocol at the relay. The circuit power consumption (CPC), which includes power requirements for both decoding and encoding circuits, is considered at the relay. For a rate dependent linear CPC model, we formulate an optimization problem to decide the optimal throughput, PS ratio, relay transmit power and time ratio for the source to relay transmission. Although the resultant optimization problem is nonconvex, we derive an efficient optimization algorithm, requiring significantly less floating point operations than an interior point method. Finally, we present numerical results which lead to some interesting insights for system design.

ItemLimitedfeedback distributed relay selection for random spatial wireless networksInaltekin, H ; Atapattu, S ; Evans, J (IEEE, 20200227)This paper considers a locationbased optimal relay selection scheme for a relayassisted wireless network where available decodeand forward relays are distributed as a homogeneous Poisson point process. To solve an optimum relay selection problem, a central entity or the source requires information pertaining to all relay locations. Since the task of feeding this information back is impractical, we investigate a thresholdbased limited feedback distributed relay selection policy. We show that the total number of relays feeding back is a Poisson distributed random variable. For a given thresholdbased limited feedback distributed relay selection policy, we obtain analytical expressions for the average rate and the outage probability over the fading and nofading communication scenarios. The derived analytical expressions are verified and the performance achieved by the proposed relay selection policy is illustrated through extensive simulations. It is observed that the limited feedback distributed relay selection policy can achieve almost the same performance with the optimum relay selection policy by only utilizing location information from a few number of relays.

ItemDistributed downlink beamforming in cellular networksNG, BENJAMIN ; EVANS, J. ; HANLY, S. (IEEE  Institute of Electrical and Electronic Engineers, 2007)

ItemMaximal lifetime rate and power allocation for sensor networks with data distortion constraintsLi, JCF ; Dey, S ; Evans, J (IEEE, 20070101)

ItemOn Optimal Power Allocation for a Class of Interference NetworksBadruddin, N ; Evans, J ; Hanly, S (IEEE, 20100101)