Subject: [its] Geo-networking and WiFi positioning

From: Alison Chaiken <[email-masked]>
Date: Sat, 29 Jun 2013 12:55:43 -0700

Regarding loss of GPS signal in tunnels and cities, why not use WiFi
Positioning?  Couldn't a vehicle know its position by triangulating among
different RSUs?  Couldn't the last 32 or 64 positions be cached?  What
problem is temporary loss of GPS connectivity going to cause that we are
trying to solve, anyway?

Consider my car parked inside my garage overnight.   Assuredly I should be
able to communicate with a router in my house securely.   Does
geo-networking  apply here?   Should I have a second radio in the car that
talks in the 2.4 GHz band with a different 802.11 protocol for this purpose?

The other fascinating topic is over-the-air updates of vehicle software.
These have security concerns more akin to emergency vehicles than to (gag)
infotainment.   I assume current vendors (Red bend) and OEMs (Tesla) are
using 3G right now for this purpose.

On Thursday night I attended a panel discussion with Mercedes, QNX (leading
car software vendor), Pandora music service, and Gartner.   They talked
about LTE and satellite communications, not 802.11p.   XM and Sirius are
planning to expand their business models to include non-broadcast data
streams, apparently.   GM has announced that it plans to offer LTE across
its whole fleet.   Does 802.11p stand a chance?  Are we certain it will
extend beyond simTD and SafetyPilot trials?

Happy weekend,
Alison

---

From: Rex Buddenberg <[email-masked]>
Date: Sat, 29 Jun 2013 14:59:35 -0700

On Sat, 2013-06-29 at 12:55 -0700, Alison Chaiken wrote:
> Positioning? 

See GNSS Today a couple years ago for an article. 

http://www.insidegnss.com/node/1916

(Google will reveal several other articles/citations)

The problem has to do with the asynchronous (bursty) transmission of
WiFi emissions.   In a tunnel, you're likely to have the same problems
with WiFi shading as with GPS shading.

>  Couldn't a vehicle know its position by triangulating among different
> RSUs?  Couldn't the last 32 or 64 positions be cached?  What problem
> is temporary loss of GPS connectivity going to cause that we are
> trying to solve, anyway?

Ah, better question to ask.  Commercial aircraft are fitted with
inertial systems that provide a 'flywheel' for radionav system gaps.
And inertial systems found initial use on submarines that we didn't want
to require to surface to get a nav fix.  For years, the inertial systems
on submarines are good enough that they need not reset for an entire
patrol.

Loran C was initially deployed for the SSBN  submarine fleet.  One of
the advantages was that the 100kHz signal could be received while
submerged (trailing wire antenna).  Indeed, while I was on the Loran
desk in CGHQ, got mail from some cavecrawlers in Indiana who used Loran
to map caves. ... dragging a receiver and antenna into the cave with
them.

Loran, as a complement to GPS is not at all far-fetched.  The North
Koreans jammed GPS earlier this year; prompting the South Koreans to
announce a rebuild of their Loran system:

http://www.insidegnss.com/node/3532

GPS suffers from several availability shortcomings, shading being an
obvious one.  Loran also suffers availability shortcomings, but there
are no common-cause failures between the two systems.  

> 
> Consider my car parked inside my garage overnight.   Assuredly I
> should be able to communicate with a router in my house securely.

Well if it's an electric car, you'd be plugging it in wouldn't you?
Hook up the ethernet cord at the same time...

>    Does geo-networking  apply here?   Should I have a second radio in
> the car that talks in the 2.4 GHz band with a different 802.11
> protocol for this purpose?

One of the things I've learned over the years is to not do with radio
what you can do with wired internet.  That experience, IMHO, applies
here.

> 
> The other fascinating topic is over-the-air updates of vehicle
> software.  These have security concerns more akin to emergency
> vehicles than to (gag) infotainment.   I assume current vendors (Red
> bend) and OEMs (Tesla) are using 3G right now for this purpose.

Downloads are a classical case where at least the Linux community has
got it right: the authenticity is associated with the data and entirely
independent of the infrastructure.  Even my cellphone provider has that
part right!

> 
> On Thursday night I attended a panel discussion with Mercedes, QNX
> (leading car software vendor), Pandora music service, and Gartner.
> They talked about LTE and satellite communications, not 802.11p.   XM
> and Sirius are planning to expand their business models to include
> non-broadcast data streams, apparently.   GM has announced that it
> plans to offer LTE across its whole fleet.   Does 802.11p stand a
> chance?  Are we certain it will extend beyond simTD and SafetyPilot
> trials?

If you live (or drive) in Wyoming, neither LTE nor 802.11 of any flavor
are likely to be ubiquitous.  It's territory that we describe as miles
and miles of nothing but miles and miles.  

Did these companies talk about what happens after the radio?  If they're
not talking about a router (which can have multiple WAN ports, after
all) and an in-platform LAN on the backside of the router, then they
haven't gotten the modularization model and systems thinking on board
yet.

Whether '802.11p stand a chance' depends on an entirely different
business model, which is not mutually exclusive to the LTE one.  After
all, my cellphone has interfaces for both.  WiFi has tended to be an
unofficial infrastructure at the fringe of the internet.  If you stroll
around the neighborhood and pick up access points, they're all owned by
my neighbors, not any phone company or highway company.  By contrast,
all the 3G and 4G base stations around here are corporately owned.  

> 
> Happy weekend, 
> Alison
> 
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