# Time-Sensitive Networking in IEEE 802.11 be: On the Way to Low-Latency WiFi 7
## 4 Supporting TSN in WiFi 7  
TSN consists of a set of sub-standards defined by the IEEE 802.1 TSN Task Group [33] to support deterministic messaging on standard Ethernet. Therefore, a single network with TSN capabilities can be shared by time-sensitive and best-effort applications. Essentially, TSN technology relies on a central management solution that uses time scheduling to ensure reliable packet delivery with bounded latency and low packet delay variation (_jitter_) in deterministic real-time applications.  
In principle, TSN capabilities can be mapped seamlessly from Ethernet to WiFi, without architectural changes nor protocol translation gateways. However, the proper operation of TSN in WiFi and, in consequence, the meeting of time-sensitive requirements, is mainly hindered by (1) the variability of wireless channel conditions (even without device mobility), (2) the interference proneness in unlicensed spectrum bands, and (3) the inherent randomness of medium access in WiFi.  
A careful design of WiFi 7 technologies taking into account the TSN principles and the wireless specificity could certainly contribute to reduce WiFi latency issues, yet at the present time that potential integration is neither straightforward nor exempted from uncertainties and incompatibilities. Therefore, the approach followed by the TGbe to prove the feasibility of TSN over wireless could encompass already available IEEE 802.11 mechanisms, native versions or adaptations from TSN sub-standards, and proposals of new solutions in several areas, as compiled in Table 1.  
This section elaborates on some key components of TSN, analyzes the most suitable IEEE 802.11 be enhancements to support them, points out the main challenges involved in the integration process, and sheds some light on possible solutions and open research directions.  
\begin{table}
\begin{tabular}{l c c c} \hline \hline \multirow{2}{*}{**Component**} & \multicolumn{2}{c}{**TSN**} & \multirow{2}{*}{**Status**} & \multirow{2}{*}{**Targeted Features**} \\  & **Sub-Standard** & & \\ \hline
**Network configuration** & & & \\ IEEE 802.1 Qcc & ✓ & S & M \\ \hline
**Time synchronization** & & & \\ IEEE 802.1 AS over IEEE 802.11 & ✓ & A & J, L \\ IEEE 802.11 mc FTM & & A & J, L \\ \hline
**Traffic filtering and policing** & & & \\ IEEE 802.1 Qci & ✓ & - & L, R \\ IEEE 802.11e/aa admission control & & A & L, R \\ Multi-band admission control & & S & L, R \\ \hline
**Traffic classification** & & & \\ IEEE 802.1Q-based VLAN tag traffic stream & & A & C \\ differentiation (TSPEC, TCLAS) & & S & L \\ EDCA operation enhancements & & S & L \\ \hline
**Scheduled operation** & & & \\ IEEE 802.1 Qbv-based time-aware scheduler & ✓ & S & J, L, R \\ IEEE 802.11 ax trigger-based access & & A & J, L, R \\ IEEE 802.11 ax TWT mechanism & & A & J, L, R \\ Multi-AP coordination & & R2/S & J, L, M, R \\ RTWT & & R1/S & J, L, R \\ \hline
**Traffic shaping** & & & \\ IEEE 802.1 Qav credit-based shaper & ✓ & S & J, L \\ IEEE 802.1 Qch cyclic queuing and forwarding & ✓ & - & J, L \\ IEEE 802.1 Qcr asynchronous traffic shaping & ✓ & - & L \\ \hline
**Transmission selection** & & & \\ IEEE.21 Qbu-based frame preemption & ✓ & S & J, L \\ \hline
**Ultra reliability** & & & \\ IEEE 802.1 CB over IEEE 802.11 ak & ✓ & A & R \\ Multi-link operation & & R1 & L, R \\ HARQ & & S & L, R \\ \hline \hline \end{tabular} Status: (A) already available in IEEE 802.11, (R1) in the roadmap of IEEE 802.11 be Release 1, (S) under study by TGbe, (-) not considered by TGbe. Targeted features: (C) traffic classification, (J) jitter, (L) latency, (M) resource management, (R) reliability.  
\end{table}
Table 1: Potential enhancements to support TSN requirements in WiFi 7.