matt9j · HackerTrans

il y a 4 ansdiscuss

This is actually not entirely true depending on how your structure your spending. In particular in the United States (the context for Coinbase's employees), the basis used to compute capital gains resets when the items are inherited when you die. So if you have enough wealth to take out loans on it until you die without ever needing to liquidate the wealth, your estate and heirs (again through some sophisticated accounting) reset the capital gains basis, and then can pay off the loans with the appreciated assets and completely avoid capital gains. ProPublica did a very detailed investigation on this in mid-2021 (https://www.propublica.org/article/the-secret-irs-files-trov...)

matt9j

il y a 5 ansdiscuss

I have some experience building rural cellular networks (4G and starting to work on 5G), and can say that the core network part of the network is usually not the biggest challenge. There are open source cores available that actually work quite well for basic Internet access (magma has been mentioned elsewhere in the thread), and open5gs is another one. They can be deployed on lightweight edge infrastructure or in the cloud, since the computational overhead for the core is not huge for a small network (10s-100s of devices). SIM cards can be purchased pretty easily online from a variety of sources. There are even already existing turnkey solutions with a core network hosted in the cloud providing a management portal that integrates directly with like-branded radios (see Baicells).

Getting outdoor radios for rural access installed though is a bit more challenging, and I would be surprised if AWS was offering an outdoor solution here in the short term. Directional antennas and radio planning become a lot more important. There are a couple different players who will sell outdoor CBRS radios in small volume who all have pluses and minuses. CBRS is great for rural areas since there are often GAA channels available, but depending on the terrain may or may not provide huge area coverage. CBRS limits the height above average terrain and power you can deploy at. There are limits to the types of equipment and locations you can deploy without getting a professional installer certification. Getting the certification slightly raises those limits, but they are still something you need to take into account for wide-area access. You can actually get the CPI certification pretty easily via online classes offered by the different SAS (spectrum access service) providers. If you’re seriously considering founding a cellular wisp, there are some Facebook (unfortunately haha) groups out there that are pretty active and where you can get shoptalk questions answered about specific radios and technologies!

IMO the main value add from the AWS solution here is the access control, monitoring/auditing, and QoS management they are offering, which would be essential in an industrial setting, especially if running sensitive services over the network.

matt9j

il y a 5 ansdiscuss

An important piece of modern (4G/5G) cell network design is that cells can have overlapping coverage to provide extra capacity in an area. The top level statistic that 52% of sites were down does not necessarily mean that 52% of the area was out of coverage at that time. It would be very expensive to heavily reinforce every small cell in every neighborhood for a large scale disaster, but would make sense to reinforce enough macro sites with wide area coverage to maintain low bandwidth emergency communications (voice+text) across the entire region.

matt9j

il y a 6 ansdiscuss

I'm surprised Olin college hasn't come up in this discussion yet (http://www.olin.edu/). They're small, but essentially went with this model, at least for a while. They're more undergraduate-focused though, so I don't know if they'll ever garner the "reputation" of MIT and Stanford's impactful research programs.

matt9j

il y a 6 ansdiscuss

Magma at its initiation extended a hard fork of OAI. The projects have since diverged quite a bit, but some of the core bits are still shared. NextEPC was renamed to open5gs a while back, and a lot of the open source telecom work seems to be happening there https://github.com/open5gs/open5gs . The project was recently reorganized by its founder though, and currently requires a CLA to contribute upstream.

matt9j

il y a 6 ansdiscuss

In addition to just the total amount of spectrum, coordinated scheduling between towers in the cellular standards helps with cooperative management of interference. Some of this is just now happening in 802.11ax, but without the high-speed non-microwave connections that celltowers in dense areas enjoy to coordinate over. 5G-NR also allows coordinated multipoint transmission, which you can think of kind of like MIMO but from multiple towers instead of just multiple antennas on the same tower. I don't know if this would ever be feasible in consumer WiFi equipment due to the challenges of synchronizing clocks across the different APs.

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