A fast industrial WLAN protocol and its MAC implementation for factory communication systems

Abstract

In this work, an industrial Wireless Local Area Network (iWLAN) system used to control industrial robots (iRBs) in factory automation (FA) environments is addressed. For fast and deterministic communication, we propose a synchronous multi-user round-robin transmission protocol. To reduce the overhead caused by the conventional multiple downlink access, we also propose a low overhead Packet Division Multiple Access (PDMA) technique. The analysis and simulation results show that our proposals provide 100% and 300% better throughput than the conventional industrial Point Coordination Function (iPCF) and Space Division Multiple Access (SDMA) protocol schemes, respectively. In particular, with the control duration per iRB of being better than 100 µsec, the proposal completely satisfies the demand for fast control of FA systems. Furthermore, the hardware architecture of MAC layer of iWLAN system is also proposed and designed to successfully implement the proposed protocol.

RT-WiFi on Software-Defined Radio: Design and Implementation

“…IEEE 802.11e introduces the hybrid coordination function (HCF) controlled channel access (HCCA) which enables the polling method and the enhanced distributed channel access (EDCA) which enables priorities in the transmissions and uses the highest priority for the real-time transmissions to guarantee their access to the channel. [11], [15]- [17], [39] study the real-time performance based on the polling method using HCCA. [16] proposes a frequency domain polling method and evaluates the real-time performance through simulations.…”

“…Although those solutions can achieve deterministic communication performance and have ultra-low energy footprint, they cannot support high-speed communications, constrained by the underlying IEEE 802.15.4/802.15.4e [8] physical layer (PHY) and data link layer (DLL). The works in the second category [9]- [14] achieve the real-time performance based on IEEE 802.11e standard, including the hybrid coordination function (HCF) controlled channel access (HCCA) which enables the polling method [15]- [17] and the enhanced distributed channel access (EDCA) which enables priorities in the transmissions and uses the highest priority for the realtime transmissions to guarantee their access to the channel. However, when EDCA is applied, the downlinks may compete for the highest priority queue on the access point (AP) side which may cause unnecessary delay and the ensuing timing violations.…”

Implementation and Trial Evaluation of a Wireless Manufacturing Execution System for Industry 4.0

“…Common for all these existing wireless solutions is that they operate in unlicensed spectrum and are, therefore, prone to interference and subject to Listen-Before-Talk (LBT) mechanisms and constraints. This means that they do not scale well in environments with interference from other sources or a large number of devices [6]. While solutions have been proposed to mitigate the scalability issue of unlicensed spectrum-based technologies, they are not commercially available yet.…”

“…While solutions have been proposed to mitigate the scalability issue of unlicensed spectrum-based technologies, they are not commercially available yet. These solutions may include for example RT-Wi-Fi [7] and [6], which proposes a modified MAC layer to better accommodate the more demanding real-time exchange of information, or MulteFire [8], which aims at providing LTE-like functionality in the unlicensed spectrum. As they are not subject to the same constraints, e.g.…”

Det-WiFi: A Multihop TDMA MAC Implementation for Industrial Deterministic Applications Based on Commodity 802.11 Hardware

“…The proposed schemes can be classified into two groups. The first group aims to optimize the conventional 802.11 MAC layer [12][13][14][15]. Some default parameters in 802.11 MAC, such as contention window and backoff mechanism, are optimized to meet the industrial application demand.…”