WiFi: “beamforming” only begins to describe it (2014)

Re:WiFi: “beamforming” only begins to describe it (2014) by hinkley on Sunday April 05, 2020 @02:18PM (#22787292)

I think it helps to think about the problem from a multiparty standpoint. On wired ethernet the simplest case is one wire going between two machines. In coax everyone shares one channel and so RX and TX have to interlace instead of overlap. You go to twisted pair and it’s unambiguous that full duplex is available and desirable.

But, now you cant just wire three machines together, because everyone’s TX has to connect to your RX and vice versa and how would that work? How about with fifty machines. You’d need some sort of star arrangement, or a little box in the middle to juggle every outbound to every inbound.

With wireless there is no box in the middle (except, very loosely, in two-tier mesh networks where infrastructure nodes talk on two channels and leaf nodes on one), so it’s really like wireless coax with the occasional router. If you want more bandwidth you could run several channels everywhere, or segment fewer machines into separate channels and connect them with more routers.

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Re:WiFi: “beamforming” only begins to describe it (2014) by madengr on Sunday April 05, 2020 @03:15PM (#22787759)

You actually can overlap RX and TX bandwidth on coax, though you need magic-tees and very good impedance matching in either end, and of course constant impedance cable. That limits it to about 100 Mbps, but you can buy the (magnetic) magic tees to do it. These are specifically for replacing analog video cameras with IP over the existing coax.

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