NOMA-Based 802.11n for Industrial Automation

Abstract

Industry 4.0 and Industrial Internet refer to the expected revolution in production, utility management and, in general, fully automated, interconnected and digitally managed industrial ecosystems. One of the key enablers for Industry 4.0 lies on reliable and timely exchange of information and large scale deployment of wireless communications in industry facilities. Wireless will bring solutions to overcome the main drawbacks of the current wired systems: lack of mobility, deployment costs, cable damage dependency and scalability. However, the strict requirements in reliability and latency of use cases such as Factory Automation (FA) and Process Automation (PA) are still a major challenge and a barrier for massive deployment of currently available wireless standards. This paper proposes a PHY/MAC wireless communication solution for FA and PA based on Non-Orthogonal Multiple Access (NOMA) in combination with the 802.11n standard. The communication system proposed aims at delivering two different sets of services. The first service class is composed of Critical Services (CS) with strict restrictions in reliability and latency. The same communication system should convey also a second group of services, referred as Best Effort (BE) with more relaxed boundary conditions. The proposal theoretical background, a detailed transmission-reception architecture, the physical layer performance and the MAC level system reliability are presented in this paper. The solution provides significantly better reliability and higher flexibility than TDMA systems, jointly with a predictable control-cycle latency.

Analysis of NOMA-Based Retransmission Schemes for Factory Automation Applications

“…In [19], the first approach of a NOMA-based 802.11n system was proposed for FA environments. In this work, the communication architecture (PHY/MAC) of the 802.11n standard to include NOMA features was redesigned.…”

“…Therefore, CS is configured with the lowest Modulation and Coding Scheme (MCS) (i.e., BPSK 1/2) and BE is configured with higher MCS that provide higher data rates (i.e., QPSK 1/2 -16QAM 1/2). Regarding the size of the packets, as in [19], the size of the CS information packet has been set at 18 bytes, while for the BE the size is flexible.…”

“…Concerning the implementation part, in a first step, a transmitter-receiver 802.11n standard chain has been implemented in Matlab [48]. Based on this implementation, several modifications have been carried out in the PHY level to introduce NOMA as a multiplexing option [19]. In addition, the transmitter-receiver chain also implements channel phenomena simulations, including fast-fading, free space loss, etc.…”

“…The development of this section is based on [19], and therefore, the transmitter-receiver chain, as well as the NOMA signal generation and cancellation have not been modified. However, this subsection extends the previous work by focusing on the effect of the IL and the MCS of the Lower Layer (LL).…”

“…In [19], the use of Non-Orthogonal Multiple Access (NOMA) in combination with the IEEE 802.11n standard to meet the strict industrial requirements is considered. These results show that NOMA has the potential for enabling highly robust communications for industrial environments.…”