1. Introduction

This section preserves the RFC text for RAW technologies, including Wi-Fi 6/7, IEEE 802.11, TSCH, 6TiSCH, 5G NR, TSN/TSC integration, UE, gNB, RAN, UPF, PDU sessions, LDACS, PHY/MAC terms, figures, tables, and security considerations.

Original RFC Text

1.  Introduction

   Deterministic Networking (DetNet) [RFC8557] provides a capability to
   carry specified unicast or multicast data flows for real-time
   applications with extremely low data loss rates and bounded latency
   within a network domain.  Techniques that might be used include (1)
   reserving data plane resources for individual (or aggregated) DetNet
   flows in some or all of the intermediate nodes along the path of the
   flow, (2) providing explicit routes for DetNet flows that do not
   immediately change with the network topology, and (3) distributing
   data from DetNet flow packets over time and/or space (e.g., different
   frequencies or non-shared risk links) to ensure delivery of each
   packet in spite of the unavailability of a path.

   DetNet operates at the IP layer and typically delivers service over
   wired lower-layer technologies such as Time-Sensitive Networking
   (TSN) as defined by IEEE 802.1 and IEEE 802.3.

   The Reliable and Available Wireless (RAW) architecture [RFC9912]
   extends the DetNet architecture [RFC8655] to adapt to the specific
   challenges of the wireless medium, in particular, intermittently
   lossy connectivity, by optimizing the use of diversity and
   multipathing.  [RFC9912] defines the concepts of reliability and
   availability that are used in this document.  In turn, this document
   presents wireless technologies with capabilities, such as time
   synchronization and scheduling of transmission, that would make RAW
   operations possible over such media.  The technologies studied in
   this document were identified in the charter during the RAW Working
   Group (WG) formation and inherited by DetNet (when the WG picked up
   the work on RAW).

   Making wireless reliable and available is even more challenging than
   it is with wires, due to the numerous causes of radio transmission
   losses that add up to the congestion losses and the delays caused by
   overbooked shared resources.

   RAW, like DetNet, needs and leverages lower-layer capabilities such
   as time synchronization and traffic shapers.  To balance the adverse
   effects of the radio transmission losses, RAW leverages additional
   lower-layer capabilities, some of which may be specific or at least
   more typically applied to wireless.  Such lower-layer techniques
   include:

   *  per-hop retransmissions (also known as Automatic Repeat Request
      (ARQ)),

   *  variation of the Modulation and Coding Scheme (MCS),

   *  short-range broadcast,

   *  Multi-User - Multiple Input Multiple Output (MU-MIMO),

   *  constructive interference, and

   *  overhearing whereby multiple receivers are scheduled to receive
      the same transmission, which saves both energy on the sender and
      spectrum.

   These capabilities may be offered by the lower layer and may be
   controlled by RAW, separately or in combination.

   RAW defines a network-layer control loop that optimizes the use of
   links with constrained spectrum and energy while maintaining the
   expected connectivity properties, typically reliability and latency.
   The control loop involves communication monitoring through
   Operations, Administration, and Maintenance (OAM); path control
   through a Path Computation Element (PCE) and a runtime distributed
   Path Selection Engine (PSE); and extended Packet Replication,
   Elimination, and Ordering Functions (PREOF).

   This document surveys the short- and middle-range radio technologies
   over which providing a RAW service is suitable, presents the
   characteristics that RAW may leverage, and explores the applicability
   of the technologies to carry deterministic flows.  The studied
   technologies are Wi-Fi 6/7, Time-Slotted Channel Hopping (TSCH), 3GPP
   5G, and L-band Digital Aeronautical Communications System (LDACS).
   The purpose of this document is to support and enable work on the
   these (and possibly other similar compatible technologies) at the
   IETF, specifically in the DetNet Working Group working on RAW.

   This document surveys existing networking technology; it does not
   define protocol behaviors or operational practices.  The IETF
   specifications referenced herein each provide their own security
   considerations, and lower-layer technologies provide their own
   security at Layer 2; a security study of the technologies is
   explicitly not in scope.