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Makes me wonder now ... in terms of software, RTOS supported or commercially available drivers for this / these protocol(s) e.g. akin to an IP Stack

Good presentation, nicely done, relieved a lot of concerns of the unknown.  Actually very reminiscent of most network topology and protocol studies, concepts not unfamiliar to me, now particularized for this particular application ...

 

Thanks for the great lecture

I have not used a non becon enabled network

I am planning on implementing a zigbee network

looking forward to another great lecture

Thanks Paul Excellent Lecture

 

Iron

@Ann - may look into mesh/tree in the near future

Iron

@Ann - star (and point to poing) topology

Iron

Great to have access to the recorded sessions

Iron

Missed the live lecture

Iron

Thanks Paul; excellent presentation

Iron

What can be the max radius where Zigbee can provide end to end communication ?

Iron

better late than never. hello from sunny miami.

802.15.4 PPDU overhead can be adjusted depending on the MAC options utilized from the new IEEE 802.15.4e Standard addendum.

Iron

Good session for me, it gives me some directions to explore more about protocols and topologies.

Thank you Paul,

 

@pauln: slide 15 is good as it stands to show the protocol layers, but to convey the increasing number of "onion layers" as one moves down the chart, it might work even better with the arrows starting close together and getting further apart as you move down the slide, and maybe even color coding to show the portion of the layer above that is wrapped with additional protocol in the next layer below.

Iron

Sign-ing off for today.  Bye, see you tomorrow!

 

@mr.E  The contention period is still a defined length.

802.15.4 recommends this order - I have not considered

precisely why.

 

Blogger

Hi LevitonDave, we can keep the hops less than 4 times. Is it ok for a low delay application?

Iron

Good talk - see you all tomorrow.

@pauln: Any comments as to why the contention-free period follows the contention (CSFM-CA) period when using a beacon? I would think the period immediately following the beacon would provide the greatest confidence about where the contention-free time slots lie.

Iron

@TonyD - 100 ms over a multi-hop network is getting tight. How many hops might be involved?

@bbauer

There are a number of reference texts on these protocols

too.  I will say that such radios are new enough that indiviual

work on protocols is quite a busy field.  We have a forthcoming

patent on a protocol of our own creation. 

So - go ahead, blaze the trail for us all.

Blogger

Thanks Paul, I will check out 6LoWPAN. Good talk, I hope to hear you tomorrow.

Bill

Iron

@bbauer

End-to-end protocol using broadcast packets.?.

The end-to-end idea can be accomplished using IP.

IP over 802.15.4 is call 6LoWPAN - check it out.

Blogger

Actually it's a bit of a mesh, with repeaters as required. We need E2E comm but have little say as to where the radios are positioned, as they have other purposes, although roughly in a line. Don't want to tie you up Paul.

Iron

If I were to build a large (many nodes and large distances) I would consider using IP before I invented my own protocol.  Designing network protocols (such as IP) is a very complicated business, in the sense that there are a lot of things that go wrong.  And, as you learn more about networking technologies, you would probably end up adding more features that are already provided by IP.  Or, perhaps not adding them, even though they are needed to meet your requirements.

And, if you have more than a trivial topology, you probably want some sort of automatic routing.  There are numerous routing protocols available for use in IP networks.  And, desiging a routing protocol is very complicated, in that many problems can be very subtle.

Iron

yes levitondave has a good point about

store and forward!

Blogger

@bbauer

If radio count and link distance are

not a factor, then next in line comes data

reception likelihood of success.  Is the data important

and must it get through 100% of the time, or can you

suffer losses.  If you can suffer losses, the job get easier.

 

Blogger

@bbauer - you may be looking at trying to use the intermediate radios as "repeaters" (store and forward) unless you wish to have real-time or connectivity part way along the line. (like at substations)

I'm designing protocol for end-to-end using broadcast packets. I want to know if I'm re-inventing the wheel.

Iron

@bbauer

I'm ex-BBNCC too - 1986-ish.

I don't know if you'd need to write your own protocol,

I think the real first question is - How many radio's will

you need and what is the maximum distance apart that they

can operate?  Going 100KM with little radios whos link distances

are aroung 100M will be painful!

Blogger

On a 100 km network, you need to think about what you are doing end-to-end.  You probably need separate hop-by-hop and end-to-end protocols.  For example, do you ack hop-by-hop, end-to-end or both.

Iron

We want to use 802.15.4 radios at each node, maybe with Zigbee.

Iron

Regarding use of Zigbee in a 100 km network:

Zigbee is a suite of protocols.  Some protocols may have more problems with the propagation delay of such a network, while other protocols might work OK.

I suspect that the CSMA-CA protocol (if you are really using that on each hop) seems likely to perform poorly.  This is analogous to the maximum size of an Ethernet network, which is limited by propagation delay.

The ack mechanism probably works poorly, because of the long delay between a packet transmission and the reception of the ack.

The limitation of having only one outstanding (unacknowledged) frame at a time is a problem with a network this large.

Iron

Paul, do you think Zigbee is suitable for real-time applications?

My current project needs a rapid response to an input. We originally tried to apply sub-1G with simple peer-to-peer network. But latter, we have to deal with expanding the wireless coverage. Mesh network such as Zigbee is perfect for our purpose, but I am not sure whether it can provide good real-time performance, say less than 100ms average delay for about 30 nodes. For example, the frequency we are choosing is 2.4GHz and average payload is 40 bytes long.

Iron

@bbauer - Sounds like you want to use radios as a back haul with Zigbee on either end of the back haul. Or are you trying to use zigbee for the entire link?

A 100 km long network might be a little exagerated, but we expect to have at least 100 radios per line. I'm just wondering if anyone has a protocol for this, or if we need to write our own.

Bill (bbauer@ieee.org) (ex-BBNCC)

 

Iron

@levitondave

Yes, real radios do indeed glow in the dark!!

Blogger

@bbauer

You need to explain more, 100KM long

network of Zigbee radios sounds really really

large!!  You'd need a lot of them!  And could

have trouble running such a huge network.  I

would think over such a distance network sync

issues alone would corrupt things.  There must

be a better way.

 

Blogger

@pauln - started ham career with tube based radios (N7IQQ). Also designed test gear for the RF/Cellular industry.

Real radios glow in the dark and heat the ham shack. :)

PSDU is not always a fixed size.

It can be really short - a minimum size

has SHR-PHR-MHR-MFR.  Thats a few bytes

in length.  But - there is a maximum size,

and that is 128 bytes total.

Blogger

I have an application that involves a linear network of radios, say spread out over 100 km of power transmission lines. Would Zigbee provide end-to-end communication using radios as relays?

Iron

@levitondave

I used to have some cool old ham geer,

but its gone now... Nothing that transmits.

Paul

Blogger

did you say the PSDU is always a fixed size?

 

Iron

The sync problem is also present on Cell phones. The difference being that cell phones can tolerate a few bytes being lost without having voice communications suffer. Our ears are amazing at filtering through issues.

Paul - you have lots of vintage radios - any that transmit?

What data rates in bytes per second do you require in your application

10kBps~30kBps

Iron

If 00 00 00 00 A7 is part of the

data and we've already synch'd, its not

a problem.  We don't re-sych, the receiver

is already running.  The issue is if the receiver

never heard SYNC in the first place - cause the

signal is weak, and then happens to see that

sequence...  Then the receiver may try to sync

in the wrong spot.  Ultimately CRC clears that out

that is, if the Net ID and Address filters haven't

already done so.

 

Blogger

excellent session, thank you Paul.

Iron

Thanks Paul - useful understanding of the overhead needed for a wireless network.

Thanks Paul and Ann, an interesting session. See all tomorrow.

Iron

Thanks Paul and Ann, Excellent!

Iron

Paul thank you for another great lecture!

Iron

lots of vacuum tube :)

Iron

So what if 00 00 00 00 00A7 is part of the data?  How does it recover?

Gold

Depends on my application.  Sensor data(accel,gyro) in real time would be around 9600 to 38.4k.

Iron

Lowest required = 57600 bps

Highest desired = 2 Mbps

Iron

we are typically at 1024 bytes/sec

Iron

Today's next audience question is

What data rates in bytes per second do you require in your application?

 

Blogger

Slides 18 and 19 are very helpful

Gold

A combination non-beacon and beacon network is being designed. 

Iron

For those of you just joining us, today's questions so far are: 1) What network topologies have you implemented, or are going to implement, in your network? 2) Has anyone implemented a non-beacon, low-power network? 

Blogger

currently testing non beacon low power network

Iron

have done P2P, nothing else

Iron

Yes, low power non-beacon network

Iron

No work on beacon network

no I haven't implemented a non-beacon.

Iron

No non-beacon networks.  All have used beacons.

Iron

Today's next audience question is

Has anyone implemented a non-beacon, low-power network?

Blogger

virtual mesh/tree topology. We do our own meshing with radio in promiscuis mode

Iron

I've used Zigbee peer to peer before and plan to use others in the future.

Iron

looks like another lost post...

 

we use point-to-point communication

Iron

Will be looking at Zigbee by 2Quarter

Iron

No current work with network 

Worked with P2P and tree but implementing full mesh

Iron

Star - one coordinator, mutiple routers

Iron

Peer to peer for now but we are investigaing Zigbee

Iron

Haven't implemented any yet. Here for learning.

Iron

Today's first audience question is

What network topologies have you implemented, or are going to implement, in your network?

Blogger

that's my current challenge - creating multiple PANs in close proximity

 

Iron

If you're having audio issues, please note that some companies block live audio streams. If you don't hear any audio, try refreshing your browser. The show will be archived and available on this page.

Blogger

@bit_slicer   Yes and no.  I'm trying to stuff as much data passing on one channel as I can, bi-directional, but sometimes I grow impatient getting two devices to talk.   :)

if anyone have problems log out and relog in or refresh page

Iron

Joe do you operate XBee's on different networks / channels?

Iron

greetings from Irinve, CA

Iron

"Aye, there be audio!"   (Scotty)

XBee's are awesome!   Every day I try to think of another circuit to monitor with one.  Must be 20+ doing different things around here now.

Good Morning from Hemet, CA

Iron

Yes, but I'm a peaceful troublemaker!   :)

Arduino + FPGA XBee = awesome!

Iron

You don't have a stash?   (All my kids are grown, I'm single, retired, well, I'm spoiled.)   :)

Looking forward to another session full of ISM goodness!

Iron

have not kave -darn fingers don't work today.

Hello from California

 

Iron

Joe: we kave college aged kids - haloween candy is gone within a week. :(

 

hello from Montana

Gold

Making Candy as Christmas gifts and first attempts at peanut butter cups worked well enough to make more.

Joe: You are such a troublemaker! :-)

Iron

Hello from CA, formerly of Cambridge MA

Iron

I have plenty of leftovers from Halloween, mini Snickers bars.   (I usually buy about four times more than I suspect I'll give away, last me until Easter.)   :)

Home made peanut butter cups?   That sounds yummy to me!   I'll have to look into those!

Hello again from Cedar Park Texas

Iron

Hi all.  Mid-30's today in sunny Minneapolis.

Iron

Snickers - I'll go with the home made Peanut butter cups I made last night. Yum.

hello from Edmonton, Alberta

Iron

Hello from Huntsville, Al

Iron

Slides are numbered.    'Sides, today is Snickers Day!!!  :)

Good morning, Portland OR

Hello from Sunny SE Lake Simcoe in Ontario.

Does Joe have his cherry pie and ice cream yet?  -- or are the slides numbered today?

Iron

Please join our Digi-Key Continuing Education Center LinkedIn Group at http://linkd.in/yoNGeY

Blogger

The streaming audio player will appear on this web page when the show starts at 2pm eastern today. Note however that some companies block live audio streams. If when the show starts you don't hear any audio, try refreshing your browser. 

Blogger

Be sure to click 'Today's Slide Deck' under Special Educational Materials above right to download the PowerPoint for today's session.

Blogger

Hi All From Rainy California

Iron

it has stopped raining :)

Iron

Good Morning from Portlandia (there's an evil light in the sky - what did we do? :) )

Good morning from TN

 

Iron

Hello from San Diego

Iron

Good morning from SoCal.

Iron

Hello from Longmont, CO

Iron

Good Morning from Raining San Jose, CA.

It's 60°F now  and a High of 63°F.

Iron

Good morning from Edmonton, AB

Iron

Good morning from Nebraska!

Iron

And North Carolina is next door

 

Iron

Good Morning from Tennessee.  Looking forward to another great lecture.

Iron


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