Creating a wireless mesh from scratch

On 03/12/14 22:36, tim..... wrote:
> Last week, I had a (telephone) interview with a company who said that (they
> thought) their problem required a wireless mess solution but that the
> environment that they worked in was too noisy for the 2.4 GHz band that
> available solutions (such as Zigbee) operate in, and they wanted someone to
> design (eventually, code and test) such a solution using a different wireless band.

Did the indicate which band? If so and it isn't an ISM band, have they budgeted 
the time/money to get the appropriate licences?

Maybe I'm being too cynical, but have they sold a concept and are now having to 
develop it? Or maybe they are just looking for free consultancy?


> Not having any experience at all of working on a mesh, I declined on the grounds
> of insufficient match for the job.

Good choice!


> My gut feel for this task is that creating (the software for) a mesh network
> from scratch would be 5-10 (man) year's of effort and not the 9-12 months that
> the company would like it to be, and I would be on a hiding to nothing trying.

Depends on where you start. IIRC Linear Technology are claiming inroads into 
this kind of area for "IoT" devices.


> Does anybody have any experience of creating a, software, mesh solution from
> scratch who can confirm or refute my estimate of how long it might take - should
> the opportunity arise again :-)

Not without a /requirements/ specification!

On 12/4/2014 3:08 AM, Paul E Bennett wrote:
> A Mesh network requires having enough residual bandwidth for each node that
> it can repeat frames intended for another node between two nodes not able to
> link directly.

A mesh (wireless or not) can also be used to provide some measure of
comms redundancy and/or recovery.  Implemented incorrectly (or, applied
to an improperly constrained set of nodes), they can lead to a very brittle
infrastructure (e.g., potentially having large portions of the network
reliant on a *single* node for connectivity to the balance of the network)

Wireless meshes have advantage in *mobile* and/or reconfigurable networks
where one or more nodes may enter or leave the mesh AT A PARTICULAR "SPOT"
over time.  But, *expecting* the entire network to remain "connected"
without other constraints in place is just wishful thinking.

The OP's client hasn't (from the OP's reporting) even ensured a mesh
(of any technology) is feasible for the (unnamed) application!

> Node 1 message meant for node 3 is received by node 2 then gets repeated to
> node 3 by node 2.
>

On Wed, 3 Dec 2014 22:36:52 -0000, "tim....."
<tims_new_home@yahoo.co.uk> wrote:

>Last week, I had a (telephone) interview with a company who said that (they 
>thought) their problem required a wireless mess solution but that the 
>environment that they worked in was too noisy for the 2.4 GHz band that 
>available solutions (such as Zigbee) operate in, and they wanted someone to 
>design (eventually, code and test) such a solution using a different 
>wireless band.
>
>Not having any experience at all of working on a mesh, I declined on the 
>grounds of insufficient match for the job.

You might study the history of AX.25 packet radio systems used by
radio amateurs since the 1980's and find out what kind of problems
were encountered.

"Modern" mesh systems try to solve some of these problems e.g. by
spread spectrum., but even with SS a large number nodes too close will
degrade the SNR and hence bit rates.

On 12/4/2014 11:30 PM, upsidedown@downunder.com wrote:
> On Wed, 3 Dec 2014 22:36:52 -0000, "tim....."
> <tims_new_home@yahoo.co.uk> wrote:
>
>> Last week, I had a (telephone) interview with a company who said that (they
>> thought) their problem required a wireless mess solution but that the
>> environment that they worked in was too noisy for the 2.4 GHz band that
>> available solutions (such as Zigbee) operate in, and they wanted someone to
>> design (eventually, code and test) such a solution using a different
>> wireless band.
>>
>> Not having any experience at all of working on a mesh, I declined on the
>> grounds of insufficient match for the job.
>
> You might study the history of AX.25 packet radio systems used by
> radio amateurs since the 1980's and find out what kind of problems
> were encountered.
>
> "Modern" mesh systems try to solve some of these problems e.g. by
> spread spectrum., but even with SS a large number nodes too close will
> degrade the SNR and hence bit rates.
>
Might find that more nodes in the mesh is far cheaper than a custom
solution.

Ham radio guys have a thing called HSMM-mesh...although I think they
recently renamed it.
It's custom firmware on commercial routers.
There are all kinds of regulatory issues if you tried to use
it for commercial applications.
But there may be some lessons to be learned from it.

Don Y wrote:

[%X]

> The OP's client hasn't (from the OP's reporting) even ensured a mesh
> (of any technology) is feasible for the (unnamed) application!
> 
>> Node 1 message meant for node 3 is received by node 2 then gets repeated
>> to node 3 by node 2.

Which is why I suggested the RF survey be conducted. Doing studies like that 
gives you a good look around the plant while taking some real measurements 
and can lead to ideas forming about how to solve his problem. Ogf course, 
just doing the survey and making a report is chargeable work and whether or 
not he got the subsequent job he would have been paid to explore the 
opportunity a bit more.

-- 
********************************************************************
Paul E. Bennett IEng MIET.....<email://Paul_E.Bennett@topmail.co.uk>
Forth based HIDECS Consultancy.............<http://www.hidecs.co.uk>
Mob: +44 (0)7811-639972
Tel: +44 (0)1235-510979
Going Forth Safely ..... EBA. www.electric-boat-association.org.uk..
********************************************************************

On 12/5/2014 7:28 AM, Paul E Bennett wrote:
> Don Y wrote:
>
> [%X]
>
>> The OP's client hasn't (from the OP's reporting) even ensured a mesh
>> (of any technology) is feasible for the (unnamed) application!
>>
>>> Node 1 message meant for node 3 is received by node 2 then gets repeated
>>> to node 3 by node 2.
>
> Which is why I suggested the RF survey be conducted. Doing studies like that
> gives you a good look around the plant while taking some real measurements
> and can lead to ideas forming about how to solve his problem. Ogf course,
> just doing the survey and making a report is chargeable work and whether or
> not he got the subsequent job he would have been paid to explore the
> opportunity a bit more.

Realistically, we both understand that *many* clients balk at this sort
of thing.  They've already got an idea (or a deadline) in their head and
just want someone to say, "Sure, I'll do it!".  That shifts the responsibility
off their shoulders (for the "uninformed" decision) and onto the contractor.

In the OP's situation, I'd have (casually) grilled the client as to why
he/they had come to that "conclusion".  And, if there didn't seem to be
some genuine science involved, take that as a sign that this relationship
would turn ugly, at some point (in the near future!).  I don't try to
"force" a (better!) solution on a client -- but, don't accept jobs where
the solution I'm being asked to pursue "feels wrong".

I pitched a wireless mesh solution to a local firm some years back (as a
favor -- I wasn't interested in the business, just giving them an idea).
It was the *ideal* solution to their problem (they were currently shipping
MILES of cable around the globe for each job).  But, they were afraid of
the "new technology" (outright said so) and comfortable shlepping all
that wire around.  Someday, their customers won't be willing to pay those
costs (or, a competitor will pop up with lower bids) and they'll be
forced to rethink their decision.  But, by then, they will *see* it
as "old, proven technology".

Or, find another line of work!  :>

"David LaRue" <huey.dll@gte.net> wrote in message 
news:XnsA3F8C395B6BF4507d764ee9285@178.63.61.145...
> Hello Tim,
>
> "tim....." <tims_new_home@yahoo.co.uk> wrote in
> news:ce9hk4F1abpU1@mid.individual.net:
>
>> Last week, I had a (telephone) interview with a company who said that
>> (they thought) their problem required a wireless mess solution but
>> that the environment that they worked in was too noisy for the 2.4 GHz
>> band that available solutions (such as Zigbee) operate in, and they
>> wanted someone to design (eventually, code and test) such a solution
>> using a different wireless band.
>
> It sounds like they don't have the requirements nailed down yet.  Any
> single candidate won't be able to solve their issue in the time they
> want.
>
> You could have inquired about the requirements for the project, what
> issues they were having, and how you might go about solving their
> problem ("get a solid communications network for their product").
>
>> Not having any experience at all of working on a mesh, I declined on
>> the grounds of insufficient match for the job.
>
> That was a wise decision.  However if you have a good grounding in
> communications applications you might be able to get up to speed on what
> is needed.
>
> I've been in that situation too, and the time frame is what worried me
> most about your call.  They were looking for a savior as well as someone
> to solve a vague set of requirements.


I took this path earlier in my career, it didn't end well :-(

I'm too old to try it again

tim

 

"Les Cargill" <lcargill99@comcast.com> wrote in message 
news:m5o8pf$qpm$1@dont-email.me...
> tim..... wrote:
>> Last week, I had a (telephone) interview with a company who said that
>> (they thought) their problem required a wireless mess solution
>
>
> They need to think again, then. Are they building to deploy MAN
> networks? My understanding is that that market is oh so very dead.

what market is that?

They are not planning on making a generic network solution to sell on

They have their own specialist data collection (slave) modules which need to 
send that data back to a master wirelessly (and that need is absolute, a 
wired solution is impossible).  They have a (presumably patented) unique 
product that they sell into specialist markets with little competition.

Currently they create a one to many, star network but that has a maximum 
range of about 40 metres.

they want to extend that range (to several 100 metres) by creating a mesh 
from the slaves

Personally, I would have suggested multiple masters connected together on a 
point to point basis, but I guess that they have already thought of this.


>
>> but that
>> the environment that they worked in was too noisy for the 2.4 GHz band
>> that available solutions (such as Zigbee) operate in,
>
> Mesh over Zigbee sounds bloody painful.
>
>> and they wanted
>> someone to design (eventually, code and test) such a solution using a
>> different wireless band.
>>
>
> These are available as COTS for next to nothing on 802.11g and such.
> AliExpress has a node for $45.

I don't think the costs of the radio is significant, but the power 
consumption almost certainly is


 

"Don Y" <this@is.not.me.com> wrote in message 
news:m5of6m$6es$1@speranza.aioe.org...
> On 12/3/2014 3:36 PM, tim..... wrote:
>> Last week, I had a (telephone) interview with a company who said that 
>> (they
>> thought) their problem required a wireless mess solution but that the
>> environment that they worked in was too noisy for the 2.4 GHz band that
>> available solutions (such as Zigbee) operate in, and they wanted someone 
>> to
>> design (eventually, code and test) such a solution using a different 
>> wireless
>> band.
>
> "They thought"... what?  That they needed a wireless mesh network?  That
> the RF environment was too polluted (at least around 2.4G)?
>
> Did they rule out a *wired* network?

that really is impossible, yes really!

tim

 

On 12/5/2014 12:10 PM, tim..... wrote:
>
> "Don Y" <this@is.not.me.com> wrote in message
> news:m5of6m$6es$1@speranza.aioe.org...
>> On 12/3/2014 3:36 PM, tim..... wrote:
>>> Last week, I had a (telephone) interview with a company who said that (they
>>> thought) their problem required a wireless mess solution but that the
>>> environment that they worked in was too noisy for the 2.4 GHz band that
>>> available solutions (such as Zigbee) operate in, and they wanted someone to
>>> design (eventually, code and test) such a solution using a different wireless
>>> band.
>>
>> "They thought"... what?  That they needed a wireless mesh network?  That
>> the RF environment was too polluted (at least around 2.4G)?
>>
>> Did they rule out a *wired* network?
>
> that really is impossible, yes really!

You didn't expound on the requirements in your initial post.  Just said:
    "(they thought) their problem required a wireless mess solution"
That suggests that there may have been other alternatives -- or, that
it would be "wireless or impossible to produce".

Over the years, I've found that folks who "think" they need something
are just looking for an alternative to another option that they have
decided (rightly or not) is "too hard" and are hoping that something they
don't completely understand may, magically, save their asses.

When they discover/decide that they can't have their wireless mesh
solution (in the allotted time), they may "suddenly" decide that
the "too hard" approach bears revisiting.  And, perhaps with this
greater motivation, come up with a viable solution!

[There are some interesting texts/research that suggest the quality
of the solution (to any problem) rises to meet the constraints
placed upon it.  I.e., people only tend to look for "difficult
solutions" when they have been convinced they *must*]