Mesh BSS: IEEE 802.11 wireless mesh network

4.3.15 Mesh BSS: IEEE 802.11 wireless mesh network

4.3.15.1 General
The IEEE 802.11 mesh facility provides MAC enhancements to support wireless LAN mesh topologies. The
mesh facilities are available to mesh STAs that belong to a mesh BSS (MBSS). For a mesh STA that has not
become a member of an MBSS, only the mesh discovery service is available. The enhancements that
distinguish mesh STAs from nonmesh STAs are collectively termed the “mesh facility.” The mesh-specific
mechanisms vary among implementations.
4.3.15.2 Overview of the mesh BSS
A mesh BSS is an IEEE 802.11 LAN consisting of autonomous STAs. Inside the mesh BSS, all STAs
establish wireless links with neighbor STAs to mutually exchange messages. Further, using the multi-hop
capability, messages can be transferred between STAs that are not in direct communication with each other
over a single instance of the wireless medium. From the data delivery point of view, it appears as if all STAs
in a mesh BSS are directly connected at the MAC layer even if the STAs are not within range of each other.
The multi-hop capability enhances the range of the STAs and benefits wireless LAN deployments.

STAs in a mesh BSS might be sources, sinks, or propagators of traffic; some mesh STAs might only
propagate traffic for other STAs. As described in 4.3.15.4, a mesh BSS might have interfaces to external
networks and can be a DSM for infrastructure BSSs.
Within a mesh BSS, STAs utilize the mesh coordination function (MCF) to access the channel. MCF is
based on the core QoS facilities specified in 4.3.7, and a mesh BSS is categorized as one type of QoS BSS.
MCF is described in 9.20.
4.3.15.3 Mesh STA
A STA that belongs to a mesh BSS is termed a “mesh station” (mesh STA). Mesh STAs are QoS STAs that
support mesh services, i.e., they participate in formation and operation of a mesh basic service set (MBSS).
A mesh STA implements a subset of the QoS functionality:
— Use of QoS frame format
— EDCA (as a part of MCF)
— Block acknowledgement (optional)
— No acknowledgement (optional)
A mesh BSS does not incorporate the full hybrid coordinator (HC) and BSS QoS functionality. MBSSs do
not incorporate the following:
— HCCA
— Traffic specifications (TSPECs)
— Traffic stream (TS) management
— Admission control
— Automatic power save delivery (APSD)
— Direct-link setup (DLS)
— Tunneled direct-link setup (TDLS)