Electrical and Electronic Engineering - Research Publications

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    Frequency Permutation Subsets for Joint Radar and Communication
    Dayarathna, S ; Senanayake, R ; Smith, P ; Evans, J (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2024-02)
    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 sub-optimal 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 peak-to-sidelobe 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.
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    High Reliability Radar and Communications Based on Random Stepped Frequency Waveforms
    Dayarathna, 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 sub-optimal 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.
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    Bit Modulated Frequency Permutation Waveforms for Joint Communications and Radar
    Dayarathna, S ; Senanayake, R ; Evans, J ; Smith, P (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2023-12)
    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.
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    Maximizing Sum-Rate via Relay Selection and Power Control in Dual-Hop Networks
    Dayarathna, S ; Senanayake, R ; Evans, J (IEEE, 2022)
    In this paper, we focus on the sum-rate optimization problem in a general dual-hop 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 sum-rate 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 sum-rate. We also prove that for the special case of two-user 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.
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    Optimal Routing for Multi-User Multi-Hop Relay Networks Via Dynamic Programming
    Dayarathna, S ; Senanayake, R ; Evans, J (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2022-05-23)
    In this letter, we study the relay selection problem in multi-user, multi-hop 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 multi-user 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.
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    Sum-Rate Optimization in Flexible Half-Duplex Networks With Transmitter/Receiver Scheduling
    Dayarathna, S ; Senanayake, R ; Evans, J (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2022-07)
    In this paper, we focus on the problem of transmitter and receiver scheduling to maximize the achievable sum-rate of a flexible half-duplex 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 sum-rate 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 sum-rate is maximized when either one transmitter or all the transmitters transmit. In fact, there exists a unique received signal-to-noise ratio at which the optimality changes from all-to-one. Finally, we design a novel low-cost algorithm that gives a sub-optimal solution to the achievable sum-rate maximization problem in a flexible half-duplex 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 sum-rate gains.