Digital twin (DT) technology has a high potential to satisfy different requirements of the ever-expanding new applications. Nonetheless, the DT placement in wireless digital twin networks (WDTNs) poses a significant c...
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Digital twin (DT) technology has a high potential to satisfy different requirements of the ever-expanding new applications. Nonetheless, the DT placement in wireless digital twin networks (WDTNs) poses a significant challenge due to the conflict between unpredictable workloads and the limited capacity of edge servers. In other words, each edge server has a risk of overload when handling an excessive number of tasks or services. Overload risks can have detrimental effects on a network's sustainability, yet this aspect is often overlooked in the literature. In this paper, we aim to study the sustainability-aware DT placement problem for WDTNs from a cost minimization perspective. To this end, we formulate the DT placement-driven cost optimization problem as a chance-constrained integer programming problem. For tractability, we transform the original non-deterministic problem into a deterministic integer linear programming (ILP) problem using the sample average approximation (SAA) approach. We prove that the transformed problem remains NP-hard and thus finding a global optimal solution is very difficult. To strike a balance between time efficiency and performance guarantee, we propose an improved local search algorithm for this ILP by identifying high-quality starting states from historical search data and enhancing the search process. Numerical results show a lower cost and higher efficiency of our proposed method compared with the previous schemes.
A time efficient algorithm based on Bloom filters is proposed to solve the problem of longest prefix matching in IP lookups. It is distinguished from the existing algorithms by three features. Firstly, a first-byte in...
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A time efficient algorithm based on Bloom filters is proposed to solve the problem of longest prefix matching in IP lookups. It is distinguished from the existing algorithms by three features. Firstly, a first-byte indexing table is established before querying the Bloom filters, so that the impact of positive false inherent to Bloom filters on IP lookups is reduced. Secondly, only twelve Bloom filters are required for prefix query, as is based on the uniform distribution of various prefix lengths. Thirdly, update of routing tables is supported by associating a counter with each bit in the bit vectors of the Bloom filters. Performance analysis and experimental results show the efficacy of the proposed algorithm in decreasing the time complexity of IP lookups.
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