tailieunhanh - Micowave and Millimeter Wave Technologies Modern UWB antennas and equipment Part 7

Tham khảo tài liệu 'micowave and millimeter wave technologies modern uwb antennas and equipment part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 172 Microwave and Millimeter Wave Technologies Modern UWB antennas and equipment optimum MRLA R for n x where the redundancy R is quantitatively defined as the number of possible pairs of antennas divided by the maximum spacing L R C n n - 1 7 R L 2L where Cq p q p - q is the number of combinations of p items taken q at a time. It is difficult to find the optimum MRLAs when large numbers of elements are involved because of the exponentially explosive search space and several earlier attempts as well as our work are detailed as follows. a Numerical search algorithms For a small number of elements it is possible to find MRLAs by a simple exhaustive search in solution space but for a large number of elements it is computationally prohibitive to do so. With the help of powerful modern computers some numerical optimization algorithms were proposed to search for MRLAs. Ishiguro 1980 proposed iterative search methods to construct MRLAs to start with the configuration of . 1 . L-1 . the integers in the set denote the spacing and to examine larger spacings preferentially. A site is selected as optimum which if occupied gives as many missing spacings as possible. When more than one site is selected as optimum at some stage they are registered without exception to examine all the combinations of tree structure derived from them. This process is repeated until the condition of full spacing is obtained. Lee Pillai 1988 proposed a greedy constructive algorithm for optimal placement of MRLA like Ishiguro s algorithm in each stage a site is selected as optimum which if occupied gives as many missing spacings as possible. And the results of this stage are stored in a linked list output linked list which in turn becomes an input linked list for the next stage. The algorithm needs large computation time and excessive memory storage. To cope with these problems a modified suboptimal version of this algorithm is also proposed by Lee. With the highly reduced computation time