As with many recent posts, this was originally a reply to a member of Quora. I am a frequent columnist at this popular Q&A forum.
Is there a theoretical speed limit to
WiFi devices over the next 10 years?
Because of four recent practices,* it is difficult to predict an upper limit for future overall throughput:
- Channel bonding
- Beam steering (MIMO shaping and directing the antenna pattern)
- Mesh Networking (i.e. subdividing a service area into micro-cells). Residential examples: Google WiFi, Netgear Orbi or TP-Link Deco
- Ultra wideband or Ultra-high frequency: In 2017, both Netgear and Asus introduced routers with (‘WiFi AD’). Although it still not widely adopted, it adds a 60 GHz radio to the existing 2.4 and 5 GHz radios, supporting 7 Gbps network speed).
Note that none of these techniques demands a high output power per channel. They all use ‘tricks’ to achieve higher speeds. But the tricks are scaleable. There really is no upper limit to any of these techniques.
Mesh networks don’t increase overall bandwidth, but by reducing the signal power and service area (and having many more access points), there is more bandwidth available for each device.
The 60 GHz used by WiFi AD is so high, that it cannot pass through walls in a typical home—just within a room. On the other hand ultra-wideband transmission has been demonstrated and recently blessed by the FCC, but it is not yet a WiFi standard. With this method, it will be possible to send insanely high-speed, low power signals through walls to cover small areas.
How fast are ultra-wideband radios? How about terabytes per second, depending on distance? It’s difficult to imagine future applications that may need that speed. It dwarfs the real world data input capacity of our senses. Perhaps, someday, you will need to transfer the entire literature of all known civilizations into your brain under under 2 milliseconds. I suppose that it would be good for that purpose.
* I called these technologies “recent developments”. But actually, three of four practices have a long history in military, commercial and industrial applications.
a) Beam steering
Focusing an antenna pattern has been around for more than 75 years. Yagi TV antennas (popular in 1960s and 70s) are highly directional. Some TV broadcast towers are situated near the edge of a service area. They split their broadcast signal, through a phase delay and deliver the waveforms to an array of antenna. This allows them to steer the signal without any mechanical movement. Directional lasers or infrared beams are often used for communications.
b) Channel bonding (or reverse multiplexing)
I had an exceptional router in the 1990s that could combine backhaul services (not just switch from one to the other in case of a drop out). It boosted speed by distributing internet packets over three separate networks):2 separate cable services and an early cell phone modem.
c) Mesh/Cellular coverage
The ‘full-blown’ implementation was developed by Motorola in the 1980s to accommodate growth in the mobile telephone market. I am not aware of an earlier implementations that included graceful, real-time hand-off of a device in motion. Of course, hotels and large convention centers have used mesh networking for more than a decade.