Big barrier to 5G cracked by full-duplex chippery

Take a look at mobile standards like LTE and you'll notice that duplexing is difficult: it's either accomplished by separating uplink and downlink in time or frequency. Why? Because it's really hard to use closely-spaced frequencies for uplink and downlink in the small space of a smartphone: the two signals will inevitably …

[Anonymous Coward]

Some Way to Go

This is quite neat (it's a difficult thing to do afterall), though I'm not convinced that this is a real problem that needs to be solved. At least not for a public mobile telephony standard.

There's nothing particularly difficult in having adequate frequency and / or time separation, which is how existing mobile standards implement a full duplex channel. It's simply a case of careful spectrum / frequency planning, something the human race has been doing for a long time now.

I'm not sure it does much to improve sprectral efficiency, it just means that you can put tx/rx bands closer together. That's just moving them around, it doesn't let them magically overlap. It might allow guard bands to be narrower, which does help a bit but not that much. You have to be pretty lazy (like the GPS manufacturers) before guard bands start having to be wastefully wide.

The picture shows what looks like just the Rx amplifier, and it's quite large. I guess it's an early prototype. However I'm not sure the silicon and the power consumption is worth it. It might prove to be something that the network operators would want (if they can somehow achieve more spectral efficiency, which I'm not convinced of), but it would likely come at the expense of reduced battery life for their customers' handsets.

[bminish]

Difficult to do at power

This will be difficult to do at the higher powers needed an a real world environment since a proportion of the transmit signal will be reflected back from the nearby environment. In the Real world this means things like walls, the ground etc.

Nonetheless this is an impressive achievement that may help us edge yet closer to the Shannon Theorem Limits