[Bloat] [Rpm] [Starlink] On FiWi

Robert McMahon rjmcmahon at rjmcmahon.com
Tue Mar 14 13:06:29 EDT 2023

The ISP could charge per radio head and manage the system from a FiWi head end which they own. Virtualize the APs. Get rid of SoC complexity and costly O&M via simplicity. Eliminate all the incremental engineering that has gone astray, e.g. bloat and over powered APs. 


On Mar 14, 2023, 9:49 AM, at 9:49 AM, Robert McMahon <rjmcmahon at rjmcmahon.com> wrote:
>Hi Mike,
>I'm thinking more of fiber to the room. The last few meters are wifi
>everything else is fiber.. Those radios would be a max of 20' from the
>associated STA. Then at phy rates of 2.8Gb/s per spatial stream. The
>common MIMO is 2x2 so each radio head or wifi transceiver supports
>5.6G, no queueing delay. Wholesale is $5 and retail $19.95 per
>pluggable transceiver. Sold at Home Depot next to the irrigation aisle.
>10 per house is $199 and each room gets a dedicated 5.8G phy rate. Need
>more devices in a space? Pick an RRH with more cmos radios. Also, the
>antennas would be patch antenna and fill the room properly. Then plug
>in an optional sensor for fire alerting.
>A digression. A lot of signal processing engineers have been working on
>TX beam forming. The best beam is fiber. Just do that. It even can turn
>corners and goes exactly to where it's needed at very low energies.
>This is similar to pvc pipes in irrigation systems. They're designed to
>take water to spray heads.
>The cost is the cable plant. That's labor more than materials. Similar
>for irrigation, pvc is inexpensive and lasts decades. A return labor
>means use future proof materials, e.g. fiber.
>On Mar 14, 2023, 4:10 AM, at 4:10 AM, Mike Puchol via Rpm
><rpm at lists.bufferbloat.net> wrote:
>>Hi Bob,
>>You hit on a set of very valid points, which I'll complement with my
>>views on where the industry (the bit of it that affects WISPs) is
>>heading, and what I saw at the MWC in Barcelona. Love the FiWi term
>>I have seen the vendors that supply WISPs, such as Ubiquiti, Cambium,
>>and Mimosa, but also newer entrants such as Tarana, increase the
>>performance and on-paper specs of their equipment. My examples below
>>are centered on the African market, if you operate in Europe or the
>>where you can charge customers a higher install fee, or even charge
>>them a break-up fee if they don't return equipment, the economics
>>Where currently a ~$500 sector radio could serve ~60 endpoints, at a
>>cost of ~$50 per endpoint (I use this term in place of ODU/CPE, the
>>antenna that you mount on the roof), and supply ~2.5 Mbps CIR per
>>endpoint, the evolution is now a ~$2,000+ sector radio, a $200
>>endpoint, capability for ~150 endpoints per sector, and ~25 Mbps CIR
>>per endpoint.
>>If every customer a WISP installs represents, say, $100 CAPEX at
>>install time ($50 for the antenna + cabling, router, etc), and you
>>charge a $30 install fee, you have $70 to recover, and you recover
>>the monthly contribution the customer makes. If the contribution after
>>OPEX is, say, $10, it takes you 7 months to recover the full install
>>cost. Not bad, doable even in low-income markets.
>>Fast-forward to the next-generation version. Now, the CAPEX at install
>>is $250, you need to recover $220, and it will take you 22 months,
>>which is above the usual 18 months that investors look for.
>>The focus, thereby, has to be the lever that has the largest effect on
>>the unit economics - which is the per-customer cost. I have drawn what
>>my ideal FiWi network would look like:
>>Taking you through this - we start with a 1-port, low-cost EPON OLT
>>you could go for 2, 4, 8 ports as you add capacity). This OLT has
>>capacity for 64 ONUs on its single port. Instead of connecting the
>>typical fiber infrastructure with kilometers of cables which break,
>>require maintenance, etc. we insert an EPON to Ethernet converter (I
>>added "magic" because these don't exist AFAIK).
>>This converter allows us to connect our $2k sector radio, and serve
>>$200 endpoints (ODUs) over wireless point-to-multipoint up to 10km
>>away. Each ODU then has a reverse converter, which gives us EPON
>>Once we are back on EPON, we can insert splitters, for example,
>>pre-connectorized outdoor 1:16 boxes. Every customer install now
>>involves a 100 meter roll of pre-connectorized 2-core drop cable, and
>>$20 EPON ONU.
>>Using this deployment method, we could connect up to 16 customers to a
>>single $200 endpoint, so the enpoint CAPEX per customer is now $12.5.
>>Add the ONU, cable, etc. and we have a per-install CAPEX of $82.5
>>(assuming the same $50 of extras we had before), and an even shorter
>>break-even. In addition, as the endpoints support higher capacity, we
>>can provision at least the same, if not more, capacity per customer.
>>Other advantages: the $200 ODU is no longer customer equipment and
>>CAPEX, but network equipment, and as such, can operate under a longer
>>break-even timeline, and be financed by infrastructure PE funds, for
>>example. As a result, churn has a much lower financial impact on the
>>The main reason why this wouldn't work today is that EPON, as we know,
>>is synchronous, and requires the OLT to orchestrate the amount of time
>>each ONU can transmit, and when. Having wireless hops and media
>>conversions will introduce latencies which can break down the
>>communications (e.g. one ONU may transmit, get delayed on the radio
>>link, and end up overlapping another ONU that transmitted on the next
>>slot). Thus, either the "magic" box needs to account for this, or an
>>new hybrid EPON-wireless protocol developed.
>>My main point here: the industry is moving away from the unconnected.
>>All the claims I heard and saw at MWC about "connecting the
>>unconnected" had zero resonance with the financial drivers that the
>>unconnected really operate under, on top of IT literacy, digital
>>skills, devices, power...
>>On Mar 14, 2023 at 05:27 +0100, rjmcmahon via Starlink
>><starlink at lists.bufferbloat.net>, wrote:
>>> To change the topic - curious to thoughts on FiWi.
>>> Imagine a world with no copper cable called FiWi (Fiber,VCSEL/CMOS
>>> Radios, Antennas) and which is point to point inside a building
>>> connected to virtualized APs fiber hops away. Each remote radio head
>>> (RRH) would consume 5W or less and only when active. No need for
>>> like zigbee, or meshes, or threads as each radio has a fiber
>>> via Corning's actifi or equivalent. Eliminate the AP/Client power
>>> imbalance. Plastics also can house smoke or other sensors.
>>> Some reminders from Paul Baran in 1994 (and from David Reed)
>>> o) Shorter range rf transceivers connected to fiber could produce a
>>> significant improvement - - tremendous improvement, really.
>>> o) a mixture of terrestrial links plus shorter range radio links has
>>> effect of increasing by orders and orders of magnitude the amount of
>>> frequency spectrum that can be made available.
>>> o) By authorizing high power to support a few users to reach
>>> longer distances we deprive ourselves of the opportunity to serve
>>> many.
>>> o) Communications systems can be built with 10dB ratio
>>> o) Digital transmission when properly done allows a small signal to
>>> noise ratio to be used successfully to retrieve an error free
>>> o) And, never forget, any transmission capacity not used is wasted
>>> forever, like water over the dam. Not using such techniques
>>> lost opportunity.
>>> And on waveguides:
>>> o) "Fiber transmission loss is ~0.5dB/km for single mode fiber,
>>> independent of modulation"
>>> o) “Copper cables and PCB traces are very frequency dependent. At
>>> 100Gb/s, the loss is in dB/inch."
>>> o) "Free space: the power density of the radio waves decreases with
>>> square of distance from the transmitting antenna due to spreading of
>>> electromagnetic energy in space according to the inverse square law"
>>> The sunk costs & long-lived parts of FiWi are the fiber and the CPE
>>> plastics & antennas, as CMOS radios+ & fiber/laser, e.g. VCSEL could
>>> pluggable, allowing for field upgrades. Just like swapping out SFP
>>> data center.
>>> This approach basically drives out WiFi latency by eliminating
>>> queues and increases capacity by orders of magnitude by leveraging
>>> in the spatial dimension, all of which is achieved by a physical
>>> Just place enough RRHs as needed (similar to a pop up sprinkler in
>>> irrigation system.)
>>> Start and build this for an MDU and the value of the building
>>> Sadly, there seems no way to capture that value other than over long
>>> term use. It doesn't matter whether the leader of the HOA tries to
>>> capture the value or if a last mile provider tries. The value
>>> sunk or hidden with nothing on the asset side of the balance sheet.
>>> We've got a CAPEX spend that has to be made up via "OPEX returns"
>>> years.
>>> But the asset is there.
>>> How do we do this?
>>> Bob
>>> _______________________________________________
>>> Starlink mailing list
>>> Starlink at lists.bufferbloat.net
>>> https://lists.bufferbloat.net/listinfo/starlink
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