Читать книгу Industry 4.0 Vision for the Supply of Energy and Materials - Группа авторов - Страница 61

Industrial environments have some special properties such as equipment noise, electromagnetic interference, and complex coordination among devices that pose unique challenges for wireless connectivity. IIoT systems often require support of seamless communication and diverse objectives of functions for a wide range of applications. Therefore, wireless communication protocol design that meets these performance criteria is essential to fulfill service QoS and ensure prolonged lifetime.

MAC layer is a key sublayer of the data link layer that exploits use of specific protocols to administer nodes privilege to access shared wireless medium according to application requirements. MAC protocol controls the radio and channel sensing scheme and defines nodes duty cycle, communication mode between devices, data rates, transmission power, and range. Given that radio is the foremost source of power consumption in networks, MAC protocols could significantly impact nodes’ overall power consumption and their lifetime [188]. In addition to the aforementioned key features, the MAC layer also controls other wireless settings such as frames synchronization, source–destination address management, error detection for physical layer transmission, collision reduction, and mitigation of idle listening.

With the goal of meeting the requirements of IIoT applications, the existing protocols could be adapted, evolved, or developed for different performance characteristics. MAC protocol schemes can be categorized into two broad classes: scheduled based and contention based [189]. Hybrid schemes are also proposed as a combination of these schemes.