{'fraction_non_alphanumeric': 0.01926605504587156, 'fraction_numerical': 0.001834862385321101, 'mean_word_length': 5.380116959064328, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Optimizing Sensor Nodes Placement for Fault-Tolerant Trilateration-Based Localization

As computing systems become increasingly pervasive, the number of applications that can benefit from or require localization capabilities continuously increases. In indoor environments, wireless sensor networks are a common means to perform localization, trilateration being one of the most commonly used techniques. The placement of anchor nodes influences greatly the system performance and cost. This paper addresses the placement problem for fault-tolerant trilateration based localization. The goal is to minimize the number of anchor nodes needed to localize a target anywhere in an area of arbitrary shape with obstacles, even after one anchor node fails. We propose an exact algorithm based on integer linear programming, as well as an efficient heuristic to solve this problem. The heuristic consists of greedy placement and pruning stages, and achieves the results, in terms of the number of anchors placed, within less than 0.5% of optimum on average. We validate our solutions by simulation.