A Distributed Surveillance System With Full Coverage Guarantee Using Positive Orthogonal Codes

Abstract

Surveillance systems provide continual coverage of target area(s) using several cameras through different angles. Conventionally, a central unit controls the system by adjusting the coverage rate of the cameras. However, in large-scale environments, such a centralized system is costly and energy inefficient, as the central unit should exchange a lot of control messages with the cameras. Centralized systems also are not resilient because they fail when the central unit is faulty. In this paper, we propose a distributed surveillance system in which each camera independently decides its activation sequence without exchanging control messages while providing guaranteed coverage of the target areas and ensuring a fault-tolerant system. Our goal is to provide full coverage of all target areas with reduced number of activations of each camera to reduce energy consumption and increase the system lifetime in case of wireless camera sensor network (WCSN) where cameras are battery-powered. To achieve that goal, each camera is activated according to positive orthogonal codes (POCs). POCs have been used for medium access control (MAC) in vehicular sensor networks as a distributed solution for medium access to reduce packet collisions. To the best of our knowledge, this is the first work that uses POCs to create a distributed surveillance system. This work proposes the system design, modeling, and simulation study of a POC-based distributed surveillance system. Moreover, we present a performance evaluation for the coverage percentage and coverage cost metrics using simulations and theoretical analysis. The results indicate that the use of POCs can achieve full coverage of the target areas with a significantly reduced number of cameras compared to a benchmark scheme that uses synchronous fixed repetition (SFR) codes.