Real-time communication

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Real-time communication(RTC) is a category of software protocols and communication hardware media that gives real-time guarantees, which is necessary to support real-time guarantees of real-time computing. [1] Real-time communication protocols are dependent not only on the validity and integrity of data transferred but also the timeliness of the transfer. Real-time communication systems are generally understood as one of two types: Hard Real-Time (HRT) and Soft Real-Time (SRT). [2] The difference between a hard and soft real-time communication system is the consequences of incorrect operation. Safety-critical systems capable of causing catastrophic consequences upon a fault, such as aircraft fly-by-wire systems, are designated as hard real-time, whereas non-critical but ideally real-time systems, such as hotel reservation systems, are designated as soft real-time. [3] The designation of a real-time communication system as hard or soft has significant influence on its design.

Contents

Hard real-time systems

Hard real-time communication systems are frequently electromechanically linked to a physical mechanism, often one that interfaces directly with people or property, which often contributes to or defines the potential danger of a fault. Due to their safety-critical nature, the communication protocols defined in a hard real-time system generally must be deterministic. [4] Hard real-time communication systems are particularly common in the transportation, industrial, and medical sectors. Common applications include control systems, automotive controllers, medical devices, and critical safety systems such as airbag firing computers.

Examples

Soft real-time systems

Unlike hard real-time communication systems, soft real-time communication systems generally do not have the capacity to cause catastrophic harm upon a fault, which allows for non-deterministic, less rigorous network infrastructure. [6] This allows soft real-time communication systems to operate over consumer networks such as residential internet connections and cellular networks. A large amount of soft real-time systems are telecommunications products such as VoIP systems and certain video calling platforms such as Discord [7] and Google Meet. [8] Data transmitted over a soft real-time communication system is not stored in a centralized server, and peers are connected directly to one another rather than through a server, although intermediary connecting nodes between peers are allowed when a direct link cannot be established. [9]

Examples

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<span class="mw-page-title-main">CAN bus</span> Standard for serial communication between devices without host computer

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WebRTC is a free and open-source project providing web browsers and mobile applications with real-time communication (RTC) via application programming interfaces (APIs). It allows audio and video communication and streaming to work inside web pages by allowing direct peer-to-peer communication, eliminating the need to install plugins or download native apps.

SafetyNET p is a standard for Ethernet-based fieldbus communication in automation technology. SafetyNET p is suitable as a drive bus due to its real-time behaviour, with cycle times of up to 62.5 μs. In accordance with the standard requirements from EN 61508 and EN 61511, it can be used in safety circuits up to and including Category 3, SIL 3.

Time-Sensitive Networking (TSN) is a set of standards under development by the Time-Sensitive Networking task group of the IEEE 802.1 working group. The TSN task group was formed in November 2012 by renaming the existing Audio Video Bridging Task Group and continuing its work. The name changed as a result of the extension of the working area of the standardization group. The standards define mechanisms for the time-sensitive transmission of data over deterministic Ethernet networks.

<span class="mw-page-title-main">Cyphal</span>

Cyphal is a lightweight protocol designed for reliable intra-vehicle communications using various communications transports, originally destined for CAN bus, but targeting various network types in subsequent revisions. OpenCyphal is an open-source project that aims to provide MIT-licensed implementations of the Cyphal protocol. The project was known as UAVCAN prior to rebranding in March 2022.

References

  1. ↑ Sundaresan, Sharad; Bettati, Riccardo (11 July 1997). Distributed Connection Management for Real-Time Communication over Wormhole-Routed Networks. people.engr.tamu.edu (Technical report). Archived from the original on 17 December 2023. Retrieved 17 December 2023– via Texas A&M University.
  2. ↑ Doyle, Paula (May–June 2004). "Introduction to Real-Time Ethernet I" (PDF). The Extension: A Technical Supplement to Control Network. 5. Contemporary Control Systems, Inc: 1–4. Archived from the original (PDF) on 16 March 2023.
  3. ↑ "IE304: Real Time Ethernet, Part 1". www.industrialethernetu.com. Retrieved 2022-03-26.
  4. ↑ Livani, M.A (1998). "Scheduling Hard and Soft Real-Time Communication in the Controller Area Network". IFAC Proceedings Volumes. 31: 13. doi:10.1016/S1474-6670(17)44865-8.
  5. ↑ Dr Barry M Cook; Paul Walker. "Ethernet over SpaceWire - software issues". 2007.
  6. ↑ Saravanan, R.; Ramaraj, N. (2009-01-31). "Providing Reliability in Replicated Middleware Applications". Journal of Computer Science. 5 (1): 11–22. doi: 10.3844/jcssp.2009.11.22 . ISSN   1552-6607.
  7. ↑ "How Discord Handles Two and Half Million Concurrent Voice Users using WebRTC". discord.com. Retrieved 2022-03-26.
  8. ↑ "How does Hangouts use WebRTC? webrtc-internals analysis". webrtcHacks. 2014-07-29. Retrieved 2022-03-26.
  9. ↑ "What is Real-Time Communications (RTC)?". www.realtimecommunicationsworld.com. Retrieved 2022-03-26.
  10. ↑ Bubley, Dean (June 2018). "Emerging RTC use-cases" (PDF). Disruptive Analysis.
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