4 ms·

This is really cool! one use case I can think of is car to car communication to allow them to share some dangers up ahead for example

Mjr_Mojo 3y ago
Vehicle to vehicle WiFi communication is standardised under the 802.11p and 802.11bd ammendments. They main difference between 11p and standard WiFi is they have halved the bit rate to increase the range and provide a way for vehicles to broadcast info outside a pre-established network context. 11bd builds on 11p adding more functionality. I don't remember the specifics of 11bd as at the time I was working with the technology 11bd hadn't finished standardisation yet. 11p and 11bd are more generally V2X comms of which there are a cellular variants (C-V2X and NR-V2X)
kwhitefoot 3y ago
Unless you are far from civilization you can just use the cellular network and not need yet another radio. My Tesla gets real time updates for traffic congestion already, it's not much of a stretch to think that it could upload it's location to a server and receive relevant information concerning the surrounding vehicles through the existing channels. Such a centralised system could also do some sanity checks. But in a peer to peer system how would one guard against malicious actors shouting false information?
- Mjr_Mojo 3y ago
  Direct vehicle-to-vehicle communication can be used to provide a lot more detailed localised info (e.g. heading, speed, current position) on a lot shorter timescales (+ end to end data delivery timelines guarantees) for collision avoidance and warning systems. The current intended standard is to broadcast these basic safety messages at 10Hz but that could be higher with 802.11bd and NR-V2X. Additionally there is dedicated spectrum set aside for vehicular communications on an international level, which helps ensure there is less congestion for these safety critical applications. Using localised peer to peer comms also eliminates some of the privacy concerns with directly sharing this info with a centralised authority as well as removing the need for any global persistent identification for this info. They also eliminate any reliance on the cellular network/internet which cannot be guaranteed to function normally for safety critical communications. There are also alternate cellular standards for vehicle to vehicle comms called C-V2X and NR-V2X so it's entirely feasible one cellular radio could do general data comms and the P2P safety standards.
  - iisan7 3y ago
    That's great but I'm still left wondering about the malicious actors problem. I thought consensus from multiple vehicles but easily spoofed. Validation against third party data but then what's the point. I can't see an easy way to improve trust, and without it I don't see the feasibility of this approach.
    - refulgentis 3y ago
      Right, but no one's trying to build systems that rely on precise velocity & its deritatives & related measures from nearby emitters - its implausible physically as well, your velocity can change very rapidly for reasons beyond your control. But they are being used to build systems that are advisory or are closed systems.
      - iisan7 3y ago
        good points. driver advisory ("possible slowdown/disabled vehicle ahead") or closed systems (cargo road trains) make a lot of sense.

Mjr_Mojo 3y ago

Vehicle to vehicle WiFi communication is standardised under the 802.11p and 802.11bd ammendments. They main difference between 11p and standard WiFi is they have halved the bit rate to increase the range and provide a way for vehicles to broadcast info outside a pre-established network context. 11bd builds on 11p adding more functionality. I don't remember the specifics of 11bd as at the time I was working with the technology 11bd hadn't finished standardisation yet. 11p and 11bd are more generally V2X comms of which there are a cellular variants (C-V2X and NR-V2X)

kwhitefoot 3y ago

Unless you are far from civilization you can just use the cellular network and not need yet another radio. My Tesla gets real time updates for traffic congestion already, it's not much of a stretch to think that it could upload it's location to a server and receive relevant information concerning the surrounding vehicles through the existing channels. Such a centralised system could also do some sanity checks. But in a peer to peer system how would one guard against malicious actors shouting false information?

Mjr_Mojo 3y ago
Direct vehicle-to-vehicle communication can be used to provide a lot more detailed localised info (e.g. heading, speed, current position) on a lot shorter timescales (+ end to end data delivery timelines guarantees) for collision avoidance and warning systems. The current intended standard is to broadcast these basic safety messages at 10Hz but that could be higher with 802.11bd and NR-V2X. Additionally there is dedicated spectrum set aside for vehicular communications on an international level, which helps ensure there is less congestion for these safety critical applications. Using localised peer to peer comms also eliminates some of the privacy concerns with directly sharing this info with a centralised authority as well as removing the need for any global persistent identification for this info. They also eliminate any reliance on the cellular network/internet which cannot be guaranteed to function normally for safety critical communications. There are also alternate cellular standards for vehicle to vehicle comms called C-V2X and NR-V2X so it's entirely feasible one cellular radio could do general data comms and the P2P safety standards.
- iisan7 3y ago
  That's great but I'm still left wondering about the malicious actors problem. I thought consensus from multiple vehicles but easily spoofed. Validation against third party data but then what's the point. I can't see an easy way to improve trust, and without it I don't see the feasibility of this approach.
  - refulgentis 3y ago
    Right, but no one's trying to build systems that rely on precise velocity & its deritatives & related measures from nearby emitters - its implausible physically as well, your velocity can change very rapidly for reasons beyond your control. But they are being used to build systems that are advisory or are closed systems.
    - iisan7 3y ago
      good points. driver advisory ("possible slowdown/disabled vehicle ahead") or closed systems (cargo road trains) make a lot of sense.