[LibreQoS] [Rpm] [Starlink] On FiWi

Robert McMahon rjmcmahon at rjmcmahon.com
Tue Mar 14 12:54:01 EDT 2023

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 US,
>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 work.
>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 from
>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 (or
>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 the
>$200 endpoints (ODUs) over wireless point-to-multipoint up to 10km
>away. Each ODU then has a reverse converter, which gives us EPON again.
>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 a
>$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 slightly
>> longer distances we deprive ourselves of the opportunity to serve the
>> 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 signal.
>> o) And, never forget, any transmission capacity not used is wasted
>> forever, like water over the dam. Not using such techniques represent
>> 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 in
>> data center.
>> This approach basically drives out WiFi latency by eliminating shared
>> 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 an
>> 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 remains
>> 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
>> _______________________________________________
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>> Starlink at lists.bufferbloat.net
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