 Electrical and Electronic Engineering  Research Publications
Electrical and Electronic Engineering  Research Publications
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ItemNo Preview AvailableOTFS Based Joint Radar and Communication: Signal Analysis Using the Ambiguity FunctionDayarathna, S ; Smith, P ; Senanayake, R ; Evans, J (IEEEINST ELECTRICAL ELECTRONICS ENGINEERS INC, 2024)

ItemFrequency Permutation Subsets for Joint Radar and CommunicationDayarathna, S ; Senanayake, R ; Smith, P ; Evans, J (IEEEINST ELECTRICAL ELECTRONICS ENGINEERS INC, 202402)This paper focuses on waveform design for joint radar and communication systems and presents a new subset selection process to improve the communication error rate performance and global accuracy of radar sensing of the permutation based random stepped frequency radar waveform. An optimal communication receiver based on integer programming is proposed to handle any subset of permutations followed by a more efficient suboptimal receiver based on the Hungarian algorithm. Considering optimal maximum likelihood detection, the block error rate is analyzed under both additive white Gaussian noise and correlated Rician fading. We propose two methods to select a permutation subset with an improved block error rate and an efficient encoding scheme to map the information symbols to selected permutations under these subsets. From the radar perspective, the ambiguity function is analyzed with regards to the local and the global accuracy of target detection. Furthermore, a subset selection method to reduce peaktosidelobe ratio (PSLR) is proposed by extending the properties of Costas arrays. Finally, the process of remapping the frequency tones to the symbol set used to generate permutations is introduced as a method to improve both the communication and radar performances of the selected permutation subset.

ItemHigh Reliability Radar and Communications Based on Random Stepped Frequency WaveformsDayarathna, S ; Senanayake, R ; Evans, J ; Smith, P (IEEE, 2023)This paper is on the waveform design of joint radar and communication systems. Focusing on permutation code based random stepped frequency waveforms, we present a new joint radar and communication system that has improved communication error rate performance when compared to existing approaches. More specifically, we propose a subset selection process to improve the Hamming distance between communication waveforms. An efficient encoding scheme is proposed to map the information symbols to selected permutations. Further, an optimal communication receiver based on integer programming followed by a more efficient suboptimal receiver based on the Hungarian algorithm is also proposed. Considering the optimum maximum likelihood detection, the block error probability is analyzed under both additive white Gaussian noise channels and Rician fading channels. Finally, we discuss the radar performance under the new system and highlight that it has negligible effect on the radar local and global accuracy.

ItemBit Modulated Frequency Permutation Waveforms for Joint Communications and RadarDayarathna, S ; Senanayake, R ; Evans, J ; Smith, P (IEEEINST ELECTRICAL ELECTRONICS ENGINEERS INC, 202312)In this paper, we propose the selection of a subset of waveforms based on the random stepped frequency permutation waveform to support joint radar and communication. More specifically, we solve two critical implementation problems arising from the subset selection which is motivated by the fundamental bit level operation requirements of communication systems. Noting that the practicality of any selected subset depends on the feasibility of efficient implementation, we focus on finding a specific subset for which we can design an efficient mapping process and a receiver implementation. More specifically, we propose an efficient process to map information bits to waveforms based on the factorial number system. An efficient optimal communication receiver that utilizes the Hungarian algorithm is also designed. For additive white Gaussian noise and correlated Rician fading channels, the bit error rate is analyzed in accordance with the optimum maximum likelihood detection.

ItemNo Preview AvailableJoint Relay Selection and Power Control to Maximize SumRate in MultiHop NetworksDayarathna, S ; Senanayake, R ; Evans, J (IEEE, 20230101)

ItemMaximizing SumRate via Relay Selection and Power Control in DualHop NetworksDayarathna, S ; Senanayake, R ; Evans, J (IEEE, 2022)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.

ItemOptimal Routing for MultiUser MultiHop Relay Networks Via Dynamic ProgrammingDayarathna, S ; Senanayake, R ; Evans, J (IEEEINST ELECTRICAL ELECTRONICS ENGINEERS INC, 20220523)In this letter, we study the relay selection problem in multiuser, multihop relay networks with the objective of minimizing the network outage probability. When only one user is present, it is well known that the optimal relay selection problem can be solved efficiently via dynamic programming. This solution breaks down in the multiuser scenario due to dependence between users. We resolve this challenge using a novel relay aggregation approach. On the expanded trellis, dynamic programming can be used to solve the optimal relay selection problem with computational complexity linear in the number of hops. Numerical examples illustrate the efficient use of this algorithm for relay networks.

ItemSumRate Optimization in Flexible HalfDuplex Networks With Transmitter/Receiver SchedulingDayarathna, S ; Senanayake, R ; Evans, J (IEEEINST ELECTRICAL ELECTRONICS ENGINEERS INC, 202207)In this paper, we focus on the problem of transmitter and receiver scheduling to maximize the achievable sumrate of a flexible halfduplex network where nodes have the flexibility to either transmit, receive or be silent in a given time slot. We consider a network with multiple transmitters and receivers where each transmitter has specific information it needs to send to a set of receiving nodes. First, we conduct some structural analysis and show that the achievable sumrate is maximized when each transmitter only transmits to a single receiver at a given time. Next, we consider one instance of the flexible network and by reducing the symmetric multiple receiver network to a single receiver network, we also show that the achievable sumrate is maximized when either one transmitter or all the transmitters transmit. In fact, there exists a unique received signaltonoise ratio at which the optimality changes from alltoone. Finally, we design a novel lowcost algorithm that gives a suboptimal solution to the achievable sumrate maximization problem in a flexible halfduplex network. We also provide a comprehensive comparison of the proposed algorithm with respect to existing resource allocation techniques, and observe that our proposed algorithm provides significant sumrate gains.

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.