Ep 5. Millimeter Wave Communication [Wireless Future Podcast] 

fantasy? uhhhh

I think you are summarizing the physical behaviors quite well. Strictly speaking, mmWave bands are from 30 to 300 GHz, where the wavelength is from 10 to 1 mm. This is the end of the radio spectrum. We will cover THz communications in the future if we have enough new things to say.

PAPR is discussed in Episode 6. I can add the following to that: 5G is so far entirely based on multi-carrier modulation. The following paper considers PAPR in Massive MIMO and shows that OFDM and single-carrier transmission result in roughly the same PAPR: arxiv.org/pdf/1510.01397.pdf

There are two references in the description of the video. In particular, the following paper is elaborating on this point: "Antenna Count for Massive MIMO: 1.9 GHz versus 60 GHz"

You lose 21 dB since you are comparing receive antennas with equal gain, which means that the area becomes (60/5.8)^2 times smaller at 60 GHz compared to 5.8 GHz. This effect is not caused by a larger pathloss over the air but just the different antenna sizes. If you would compare the pathloss with equal-sized receivers, the difference disappears. You read more about it here: ma-mimo.ellintech.se/2019/10/29/is-the-pathloss-larger-at-mmwave-frequencies/

@@WirelessFuture I appreciate the reply! I read the link, thanks! Isn't removing the antenna (using 0 dB gain for example) the whole point of figuring out path loss? If I consider antenna gain, then I can use the higher gain antenna of mmWave to offset these losses but this just means I'm improving the link budget and making ways to offset the weaker signal from the higher path loss. Example, If I decide to use a 5/8wave omni directional antenna with 3dBi gain (I know, not typical for mmWave) but hear me out... the path loss is still 20dB more than 5.8GHz. I have to make up with all this additional loss by using phased arrays to get the dB gain up for this additional path loss. If you use the same size dish for both frequencies, then the smaller wavelength means its focused more, and dissipating less area, while the lower frequency with much less gain has the same RSSI, but is how spread out much more, which means there is effectively more "of it". It would great to have a conversation on the subject. Cheers!

@@Z28videogates If you want to truly remove the impact of the receive antenna, you need to consider the power flux (W/m^2) of the impinging signal. It will be the same irrespective of the frequency of the transmitter is isotropic. When computing the received power, you are essentially multiplying the power flux with the (effective) area of the receive antenna. If one assumes that the antenna area shrinks with the wavelength, then the received power shrinks proportionally. This is what happens when comparing isotropic receive antennas at two different frequencies. If one instead considers equal-area receive antennas when modifying the frequency, then the received power is unchanged. You are totally right that the antenna gain pattern will then change as we modify the frequency. We get a more and more directive antenna. This is alright for fixed wireless links, while mobile links use arrays of low gain antennas instead to make directivity steerable by beamforming.

The antennas will for sure be directed away from the head, since the radio waves would otherwise be absorbed by the skin and thus not useful. It remains to determine what data rate is needed for AR applications. Connecting AR glasses to a phone via Bluetooth would be a good solution if the data rate is sufficient (Bluetooth supports a few Mbps), but some other solution might be needed if real-time video should be delivered to the phone or the cloud.

If the received power is the same, then it is probably better to use the 10 GHz band since you typically have more spectrum available in that band. If the spectral bandwidth is the same, both bands are equally good. If the transmit power is the same, the benefit might be lost since propagation losses can be bigger in the 10 GHz band. This is why only typical say that higher frequencies have shorter range.

@@WirelessFuture "spectral bandwidth" meaning the width of the modulation, in absolute Hz?

​@@johnaweiss Yes. I wrote “spectral bandwidth” since the term “bandwidth” is used by computer scientists to mean data rate (bit/s), which is a misnomer in my opinion.

@@WirelessFuture I know, i should have said "data rate" in my question. There's a positive correlation between spectral bandwidth and data-rate, correct?

Can you please explain your question in more detail?

@@WirelessFuture will call waiting,blocked calls scenarios decreases thus in turn traffic handling capacity improved by using mm waves?

Blocked calls are typically caused by lack of coverage rather than lack of capacity, since the data rate needed for calls is fairly low. Generally speaking, the more frequency bands used by the network, the better the coverage and capacity will be. But I think that Massive MIMO in low and mid bands will be more important to prevent blocked calls.

@@WirelessFuture ok.thanks a lot sir