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Two-way Radio Breakthrough To Double Wi-Fi Speeds
An anonymous reader writes "Scientists at Stanford University have built a radio that can transmit and receive at the same time on the same frequency. The breakthrough could lead to a twofold increase in performance for home wireless networks and end that annoying habit of pilots finishing every sentence with 'over.'" But you can still do it if you like. I'm not judging.
Doing this On the same frequency is remarkable. but the gains they are claiming can be had right now by using TWO frequencies. Transmit on channel 1 receive on channel 12.. t
This might be problem if you want mesh network with many (n>2) nodes. They (mostly) want to hear each other.
Anyhow, with 100 dB (10 000 000 000) times stronger transmit signal I somehow doubt if geometry of antennas can be accurate
enough to keep it working with changing temperature, humidity etc. over MHz of bandwith.
Maybe with heavy DSP processing and continuos monitoring?
Compensating for scattering of own signal, and all reflections from surounding objects?
On top of it, we normally use MIMO: so you have to do it on 4 receiving antennas ;-).
Even with MIMO 2by2 we might double channel capacity in perfect (MIMO perfect) radio conditions.
Yes, it is possible in the lab. But mass products?
Ah, back to good old Shannon: just double the bandwith.
73
Iztok
Phones are "full duplex" because there are 2 wires involved. One wire coming in to the receiver and going up to the earpiece, and one wire going out from the mouthpiece. (Yes, telco engineers, I know it's not quite that simple, but for purposes of this conversation, it is)
To put it another way, you don't fill the bathtub by reversing the flow of the drain.
To translate that to wireless, you'd need two frequencies for full duplex. Full duplex over one frequency would be like full duplex over one wire instead of two.
BTW re: modems being faster if you turned off the upload channel and used it for download - - that wouldn't work because of the checksum - - the data packets have a checksum which the modem sends back up the upload channel to verify that it's receiving the information correctly. (this wouldn't have been a problem with certain protocols like Ymodem-G, which eliminates the cyclic redundancy checking and therefore does not need the upload channel, but you're then relying on a completely error-free connection which is iffy at best over a standard phone line, hence the fact that such protocols were almost never used in the wild).
What they used to do in the modem days to make them faster was to use a protocol called Shotgun, which linked 2 modems working on 2 separate phone lines together to increase the throughput.
"I disagree with you" does not equal "flamebait."
> Phones are "full duplex" because there are 2 wires involved. One wire coming in to the receiver and going up to the earpiece, and one wire going out from the mouthpiece. (Yes, telco engineers, I know it's not quite that simple, but for purposes of this conversation, it is)
Utter screaming gibberish.
The phone IS actually full duplex. The Receive and Transmit signals travel on the same wires at the same time (in opposite directions), thanks to a gadget called a Hybrid.
And believe it or not, the same thing can be done on wireless. Single Frequency Duplex radios were demonstrated decades ago.