4 ms·

> 5G operates on higher frequency and requires a larger density of base stations No that’s not required, 5G uses the same old frequencies as 2/3/4G for the bul

by opless 6y ago

> 5G operates on higher frequency and requires a larger density of base stations No that’s not required, 5G uses the same old frequencies as 2/3/4G for the bulk of the traffic, it only uses the >1Ghz frequencies for microcells in malls and other dense areas where appropriate.

mattmanser 6y ago
I assume in order to be able to decide to serve those 1Ghz frequencies, all the phones are going to ping the local towers regardless, so it doesn't matter.
- opless 6y ago
  That'll no doubt be down to the configuration of the terminal device. It'll likely only TX on the available bands allowed in the devices home region for licensing/compliance issues. Back on the tracking side of things... AFAIKR 3G and above do not leak their IMEI/IMSI unencrypted. Of course nearly zero phones show or warn if encryption is used or not (though I think that's a setting in the SIM card).
totalZero 6y ago
> 5G uses the same old frequencies as 2/3/4G for the bulk of the traffic, it only uses the >1Ghz frequencies for microcells in malls and other dense areas where appropriate. That's simply not true. 5G cannot achieve its advanced speeds without higher frequencies, which cannot be deployed without greater density of base stations. Higher frequencies beget faster signal falloff and greater susceptibility to obstruction. "5G needs spectrum across low, mid and high spectrum ranges to deliver widespread coverage and support all use cases. All three have important roles to play." [1] Microcells use high-band, not mid-band, spectrum. High-band may not be useful outside of dense areas because of its reduced range, but it is essential to 5G and the FCC is releasing about 5GHz of spectrum for this purpose. Mid-band (1GHz-6GHz) is the bread and butter of 5G, and the FCC has pushed to open this part of the spectrum as much as possible for 5G to work as intended. This part of the spectrum is the most versatile, but it is in short supply [2]. Part of the challenge of 5G involves more frequent handoffs between base stations versus past generations of mobile phone radio. Similarly, 5G devices use various mitigation techniques to deal with interference from nearby base stations. For both of these reasons, there is a substantial amount of interaction between a single handset and nearby base stations that may not be presently serving it. [1] https://www.gsma.com/spectrum/wp-content/uploads/2020/03/5G-Spectrum-Positions.pdf https://www.gsma.com/spectrum/wp-content/uploads/2020/03/5G-... [2] https://docs.fcc.gov/public/attachments/DOC-363622A1.pdf https://docs.fcc.gov/public/attachments/DOC-363622A1.pdf
- opless 6y ago
  I said ‘where appropriate’. It’s unlikely to be rolled out fully throughout the entirety of the providers network. So you’ll see it in high density areas where people are mostly outside. As I said, malls etc. Also higher speeds at the regular sub-ghz frequencies are achievable through beam-forming.
  - totalZero 6y ago
    To send more data per second, you either need a carrier wave of higher frequency (which 5G is doing), or an increased number of simultaneous data streams at the present frequency (which 5G is also doing). Beamforming can't overstep the physical limitations of a carrier wave, it just adapts the radiation pattern of the antenna array to improve range and reduce interference. This is useful to extend the range of high-band signals, because they operate in object-dense space with a high density of clients. It is also useful at the lower frequencies, because it allows an improvement in spectrum efficiency in an otherwise crowded part of the spectrum. You are basically saying that beamforming allows more single-user MIMO to improve the data speed of an individual user's connection at the lower frequencies. I agree with that. However, you still need more base stations because (A) you won't see the massive advertised 5G speeds without sub-6GHz and mm-wave, and (B) you need more antennas as you improve MIMO to serve more simultaneous data streams to each individual user at sub-GHz. I am not familiar with the authors of this paper (https://arxiv.org/pdf/1902.07678.pdf https://arxiv.org/pdf/1902.07678.pdf), but it offers a good explanation with some images: The spectral efficiency of Massive MIMO grows monotonically with the number of antennas [28]. Thus, we can expect a future where hundreds or thousands of antennas are used to serve a set of users. There are, however, practical limits to how many antennas can be deployed at conventional towers and rooftop locations, for example, determined by the array dimensions allowed by the site owner, the weight, and the wind load. [...] Nevertheless, the spatial multiplexing capability of these two dimensional planar arrays in our three-dimensional world is far from what has been demonstrated in the academic literature, where large one-dimensional arrays are often considered in a two-dimensional world. In many practical deployment scenarios, the user channels are mainly separable in the horizontal domain [35] since the variations in elevation angle between different users and scattering objects are relatively small. [...] However, to deploy more than a few hundred antennas per site and to obtain a truly massive spatial resolution in the horizontal domain, we need new antenna deployment strategies. Instead of gathering all the antennas in a single box, which will be visible and heavy, the antennas can be distributed over a substantially larger area and made invisible by integrating them into existing construction elements. Also, you're going to see mid-band (sub-6GHz) rolled out in a lot of places where mm-wave wouldn't be appropriate.

by opless 6y ago

mattmanser 6y ago

I assume in order to be able to decide to serve those 1Ghz frequencies, all the phones are going to ping the local towers regardless, so it doesn't matter.

opless 6y ago
That'll no doubt be down to the configuration of the terminal device. It'll likely only TX on the available bands allowed in the devices home region for licensing/compliance issues. Back on the tracking side of things... AFAIKR 3G and above do not leak their IMEI/IMSI unencrypted. Of course nearly zero phones show or warn if encryption is used or not (though I think that's a setting in the SIM card).

totalZero 6y ago

> 5G uses the same old frequencies as 2/3/4G for the bulk of the traffic, it only uses the >1Ghz frequencies for microcells in malls and other dense areas where appropriate. That's simply not true. 5G cannot achieve its advanced speeds without higher frequencies, which cannot be deployed without greater density of base stations. Higher frequencies beget faster signal falloff and greater susceptibility to obstruction. "5G needs spectrum across low, mid and high spectrum ranges to deliver widespread coverage and support all use cases. All three have important roles to play." [1] Microcells use high-band, not mid-band, spectrum. High-band may not be useful outside of dense areas because of its reduced range, but it is essential to 5G and the FCC is releasing about 5GHz of spectrum for this purpose. Mid-band (1GHz-6GHz) is the bread and butter of 5G, and the FCC has pushed to open this part of the spectrum as much as possible for 5G to work as intended. This part of the spectrum is the most versatile, but it is in short supply [2]. Part of the challenge of 5G involves more frequent handoffs between base stations versus past generations of mobile phone radio. Similarly, 5G devices use various mitigation techniques to deal with interference from nearby base stations. For both of these reasons, there is a substantial amount of interaction between a single handset and nearby base stations that may not be presently serving it. [1] https://www.gsma.com/spectrum/wp-content/uploads/2020/03/5G-Spectrum-Positions.pdf https://www.gsma.com/spectrum/wp-content/uploads/2020/03/5G-... [2] https://docs.fcc.gov/public/attachments/DOC-363622A1.pdf https://docs.fcc.gov/public/attachments/DOC-363622A1.pdf

opless 6y ago
I said ‘where appropriate’. It’s unlikely to be rolled out fully throughout the entirety of the providers network. So you’ll see it in high density areas where people are mostly outside. As I said, malls etc. Also higher speeds at the regular sub-ghz frequencies are achievable through beam-forming.
- totalZero 6y ago
  To send more data per second, you either need a carrier wave of higher frequency (which 5G is doing), or an increased number of simultaneous data streams at the present frequency (which 5G is also doing). Beamforming can't overstep the physical limitations of a carrier wave, it just adapts the radiation pattern of the antenna array to improve range and reduce interference. This is useful to extend the range of high-band signals, because they operate in object-dense space with a high density of clients. It is also useful at the lower frequencies, because it allows an improvement in spectrum efficiency in an otherwise crowded part of the spectrum. You are basically saying that beamforming allows more single-user MIMO to improve the data speed of an individual user's connection at the lower frequencies. I agree with that. However, you still need more base stations because (A) you won't see the massive advertised 5G speeds without sub-6GHz and mm-wave, and (B) you need more antennas as you improve MIMO to serve more simultaneous data streams to each individual user at sub-GHz. I am not familiar with the authors of this paper (https://arxiv.org/pdf/1902.07678.pdf https://arxiv.org/pdf/1902.07678.pdf), but it offers a good explanation with some images: The spectral efficiency of Massive MIMO grows monotonically with the number of antennas [28]. Thus, we can expect a future where hundreds or thousands of antennas are used to serve a set of users. There are, however, practical limits to how many antennas can be deployed at conventional towers and rooftop locations, for example, determined by the array dimensions allowed by the site owner, the weight, and the wind load. [...] Nevertheless, the spatial multiplexing capability of these two dimensional planar arrays in our three-dimensional world is far from what has been demonstrated in the academic literature, where large one-dimensional arrays are often considered in a two-dimensional world. In many practical deployment scenarios, the user channels are mainly separable in the horizontal domain [35] since the variations in elevation angle between different users and scattering objects are relatively small. [...] However, to deploy more than a few hundred antennas per site and to obtain a truly massive spatial resolution in the horizontal domain, we need new antenna deployment strategies. Instead of gathering all the antennas in a single box, which will be visible and heavy, the antennas can be distributed over a substantially larger area and made invisible by integrating them into existing construction elements. Also, you're going to see mid-band (sub-6GHz) rolled out in a lot of places where mm-wave wouldn't be appropriate.