| The Study of Direction Finding Algorithms for Coherent Multiple Signals in Uniform Circular Array |
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Cheol-Sun Park, Ho-Joo Lee, Won Jang |
| 등각원형배열을 고려한 코히어런트 다중신호 방향탐지 기법 연구 |
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박철순, 이호주, 장원 |
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국방과학연구소 |
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| Abstract |
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In this paper, the performance of AP(Alternating Projection) and EM(Expectation Maximization) algorithms is investigated in terms of detection of multiple signals, resolvability of coherent signals and the efficiency of sensor array processing. The basic idea of these algorithms is utilization of relaxation technique of successive 1D maximization to solve a direction finding problem by maximizing the multidimensional likelihood function. It means that the function is maximized over only for a single parameter while the other parameters are fixed at each step of the iteration. According to simulation results, the algorithms showed good performance for both incoherent and coherent multiple signals. Moreover, some advantages are identified for direction finding with very small samples and fast convergence. The performance of AP algorithm is compared with that of EM using multiple criteria such as the number of sensor, SNR, the number of samples, and convergence speed over uniform circular array. It is resulted AP algorithm is superior to EM overally except for one criterion, convergence speed. Especially, for EM algorithm there is no performance difference between incoherent and coherent case. In conclusion, AP and EM are viable and practical alternatives, which can be applied to a direction under due to the resolvability of multi-path signals, reliable performance and no troublesome eigen-decomposition of the sample-covariance matrix. |
| Key Words:
Direction Finding, Uniform Circular Array, Alternating Projection(AP), Expectation Maximization(EM) |
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