[HN Gopher] Low-Power Wi-Fi Extends Signals Up to 3 Kilometers
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       Low-Power Wi-Fi Extends Signals Up to 3 Kilometers
        
       Author : pseudolus
       Score  : 44 points
       Date   : 2024-02-03 17:50 UTC (5 hours ago)
        
 (HTM) web link (spectrum.ieee.org)
 (TXT) w3m dump (spectrum.ieee.org)
        
       | leroman wrote:
       | 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 wrote:
         | 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)
        
       | westurner wrote:
       | Could this [1] be possible with "Wi-Fi HaLow, based on the IEEE
       | 802.11ah standard", too?:
       | 
       | [1] "Sensor-Free Soil Moisture Sensing Using LoRa Signals" (2022)
       | https://news.ycombinator.com/item?id=38768950
        
         | westurner wrote:
         | - "43 km line of sight with USB WiFi stick (2005)"
         | https://news.ycombinator.com/item?id=30541576
         | 
         | - Kreosan English's modded lunar rover WiFi antenna videos:
         | "100s of km" https://youtu.be/Nk-nj_BwoBE?si=0iwpQBFs9ZqFP0p8
         | ... 10x: https://youtu.be/GWq6L94ImX8?si=V2R8hpa3vAosbhvi
        
       | zokier wrote:
       | 1Mbps over 3km doesn't sound exactly impressive by itself. People
       | have been doing multikilometer wifi links for ages now. Random
       | paper reviewing some of them:
       | https://www.researchgate.net/publication/281644239_Outdoor_L...
       | 
       | Select example:
       | 
       | > Next, Paul et al. [62] reported on their observation of the
       | WLAN link performance in open outdoor networks. The deault packet
       | size was 1470 B for all reported measurement campaigns. They
       | achieved a maximum range of 1800 m LOS at 148 Mbps with IEEE
       | 802.11n links in outdoor locations for back-haul connection among
       | WLAN APs.
       | 
       | I'm sure there are things here making the actual tech impressive,
       | presumably biggest thing being power consumption and size. But
       | just saying that the demo is not doing much when they don't
       | provide any details of the setup.
        
         | lxgr wrote:
         | With what antenna type? IoT-like use cases often don't lend
         | themselves towards the usage of highly-directional, large
         | antennas and high-power transmitters.
        
           | zokier wrote:
           | That's exactly the problem, this demo doesn't tell anything
           | about antennas or power levels, so it's completely impossible
           | to say if their thing is worth anything.
        
       | jokoon wrote:
       | well at some point, long distance wifi is just a 4G/5G antenna
       | 
       | of course the protocol is not the same, but it's not very
       | different either
       | 
       | 4g/5g might also have techniques to improve connectivity in a 3km
       | radius when you have buildings and so many other problematic
       | things, while wifi was designed for building interiors.
       | 
       | I don't know how expensive is a cheap 5G antenna, but seems like
       | it's a tech designed for longer distance, so why use wifi?
        
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       (page generated 2024-02-03 23:00 UTC)