A Novel Spatial–Temporal Specification-Based Monitoring System for Smart Cities

Abstract

With the development of the Internet of Things, millions of sensors are being deployed in cities to collect realtime data. This leads to a need for checking city states against city requirements at runtime. In this paper, we develop a novel spatial-temporal specification-based monitoring system for smart cities. We first describe a study of over 1,000 smart city requirements, some of which cannot be specified using existing logic such as Signal Temporal Logic (STL) and its variants. To tackle this limitation, we develop SaSTL-a novel Spatial Aggregation Signal Temporal Logic-for the efficient runtime monitoring of safety and performance requirements in smart cities. We develop two new logical operators in SaSTL to augment STL for expressing spatial aggregation and spatial counting characteristics that are commonly found in real city requirements. We define Boolean and quantitative semantics for SaSTL in support of the analysis of city performance across different periods and locations. We also develop efficient monitoring algorithms that can check a SaSTL requirement in parallel over multiple data streams (e.g., generated by multiple sensors distributed spatially in a city). Additionally, we build a SaSTL-based monitoring tool to support decision making of different stakeholders to specify and runtime monitor their requirements in smart cities. We evaluate our SaSTL monitor by applying it to three case studies with large-scale real city sensing data (e.g., up to 10,000 sensors in one study). The results show that SaSTL has a much higher coverage expressiveness than other spatial-temporal logics, and with a significant reduction of computation time for monitoring requirements. We also demonstrate that the SaSTL monitor improves the safety and performance of smart cities via simulated experiments.

CitySpec: An Intelligent Assistant System for Requirement Specification in Smart Cities

“…Existing city requirements are often defined with missing information or ambiguous description. In [2], the authors define essential elements for monitoring a city requirement. Within the 1500 requirements, many requirements have one or more missing elements.…”

“…With the increasing demand for safety guarantees in smart cities, significant research efforts have been spent toward how to ensure that a city's real-time operations satisfy safety and performance requirements [1]. Monitoring systems, such as SaSTL runtime monitoring [2], CityResolver [3], and STL-U predictive monitoring [4], have been developed in smart cities. Figure 1 shows a general framework of monitoring systems in smart cities.…”

An Intelligent Assistant for Converting City Requirements to Formal Specification

“…The demand for safety guarantees in smart cities has been increasing in recent years. Although monitoring systems have been developed and tested to be effective and efficient while dealing with machine-understandable formal specifications [2]- [4], they require two important inputs, i.e., the real-time data streams and formal specified requirements. In other words, the inputs to the monitoring systems need to be machine-understandable formal specification streams.…”

Online Monitoring of Dynamic Systems for Signal Temporal Logic Specifications with Model Information

“…In the past years, numerous algorithms have been developed for monitoring specifications described by, e.g., Linear Temporal Logic (LTL) [9], Metric Temporal Logic (MTL) [7], [23] and Signal Temporal Logic (STL) [6], [8]. Recent applications of specification-based monitoring techniques include, e.g., autonomous vehicles [21] and smart cities [16].…”