Orphan notification in cc2530

how can you tell that orphan notification from Zigbee End device?

coordinator realignment field in the above diagram shows that coordinator address is 0x7DFC but there is no coordinator in the network because i powered of the coordinator once the net work formed.There is only router and end device in the network.End device is connected to router.

orphan notification is always from ZED and it contains IEEE address of ZED.

IF U CONFIGURE THAT DEVICE AS ROUTER THEN ALSO SAME IEEE ADDRESS.AS I KNOW BASED ON IEEE ADDRESS WE CAN NOT TELL THAT IS AN END DEVICE

what does tells the coordinator realignment field in the above packet?

Coordinator realignment is used by coordinator to reply to an orphan notification command or when PAN attributes change with the logical channel information.

Dear Darkside

in which type of scenarios the realignment frame generates?
what is the use of that realignment frame?
is the coordinator/router received the orphan notification or not?

I had replied to this: Coordinator realignment is used by coordinator to reply to an orphan notification command or when PAN attributes change with the logical channel information. Coordinator realignment is issued by coordinator. It is not received by coordinator or router.

Dear Yk Chen
You told that the orphan notification is not received any coordinator or router when the end device generates it.then how knows to coordinator/router when the end device losts it's parent.

The process is like the followings:
When ZED lost connection with its parent node, ZED would broadcast orphan notification. If coordinator receives orphan notification broadcast, ZC would unicast coordinator realignment to ZED.

if the coordinator receives the orphan notifications then why the link between coordinator and end device lost?

That's what I see from your sniffer snapshot. ZED only sends orphan notification when it loses connection with its parent node. This is for sure. Then you see there are 4 coordinator realignments with the same sequence number 40, which is weird for me. It seems that there are strong interferences in your test environment.

is cc2530 beacon enabled or non beacon enabled?

i place the router and end device with an apart of 60cm distance.
once again i remember you i switched off the coordinator after network formed.There is only router and end device exist in the network.end device is connected to router.

is there no csma/ca technique in cc2530?

Yes, there is collision avoidance on CC2530.

as i know csma/ca technique is used in the non beacon enabled network.

Please refer to en.wikipedia.org/.../ZigBee

Dear YK Chen
please go through this link www.telecomabc.com/.../zigbee.html

The current ZigBee protocols support beacon and non-beacon enabled networks. In non-beacon-enabled networks, an unslotted CSMA/CA channel access mechanism is used. In this type of network, ZigBee Routers typically have their receivers continuously active, requiring a more robust power supply. However, this allows for heterogeneous networks in which some devices receive continuously, while others only transmit when an external stimulus is detected. The typical example of a heterogeneous network is a wireless light switch: The ZigBee node at the lamp may receive constantly, since it is connected to the mains supply, while a battery-powered light switch would remain asleep until the switch is thrown. The switch then wakes up, sends a command to the lamp, receives an acknowledgment, and returns to sleep. In such a network the lamp node will be at least a ZigBee Router, if not the ZigBee Coordinator; the switch node is typically a ZigBee End Device.

In beacon-enabled networks, the special network nodes called ZigBee Routers transmit periodic beacons to confirm their presence to other network nodes. Nodes may sleep between beacons, thus lowering their duty cycle and extending their battery life. Beacon intervals depend on data rate; they may range from 15.36 milliseconds to 251.65824 seconds at 250 kbit/s, from 24 milliseconds to 393.216 seconds at 40 kbit/s and from 48 milliseconds to 786.432 seconds at 20 kbit/s. However, low duty cycle operation with long beacon intervals requires precise timing, which can conflict with the need for low product cost.

In general, the ZigBee protocols minimize the time the radio is on, so as to reduce power use. In beaconing networks, nodes only need to be active while a beacon is being transmitted. In non-beacon-enabled networks, power consumption is decidedly asymmetrical: Some devices are always active, while others spend most of their time sleeping.

Except for the Smart Energy Profile 2.0, ZigBee devices are required to conform to the IEEE 802.15.4-2003 Low-Rate Wireless Personal Area Network (LR-WPAN) standard. The standard specifies the lower protocol layers—the physical layer (PHY), and the Media Access Control portion of the data link layer (DLL). The basic channel access mode is "carrier sense, multiple access/collision avoidance" (CSMA/CA). That is, the nodes talk in the same way that humans converse; they briefly check to see that no one is talking before they start, with three notable exceptions. Beacons are sent on a fixed timing schedule and do not use CSMA. Message acknowledgments also do not use CSMA. Finally, devices in beacon-enabled networks that have low latency real-time requirements may also use Guaranteed Time Slots (GTS), which by definition do not use CSMA.


Note: From the above explanation we conclude that csma /ca technique is not used in the beacon enabled network.

Sorry I misunderstand your question about beacon or non-beacon. Actually, ZigBee networks are non-beacon. Non beacon means asynchronous, not that is it is not using the 'Beacon' type of frames.

I see there were lots of questions that were asked as follow up.
I'll try to clarify.
- When end device loses connection with his parent, or when it restarts after power cycle, it sends an orphan notification looking for his parent back again
- When the parent recognizes his child sending an orphan notification, it responds with a coordinator re-alignment frame. Coordinator realignment is a MAC frame which requires MAC acknowledgement from the receiver (ie end device), and I don't see that in your log
-ZigBee uses 802.15.4 MAC in a non-beacon type of configuration. Frames are emitted asynchronously and 'on demand' by end device, which wakes up when he needs to send it. Periodically end device wake up to poll for data buffered by their parent. But not to receive beacon frames
- ZigBee uses CSMA-CA feature of 802.15.4 MAC. Channel is assessed to be cleared before any transmission happens. Number of max backoff, clear channel assessment period, as well as min and max backoff exponent are 802.15.4 MAC parameters chosen by the ZigBee protocol as MAC settings.

I hope this clarifies everything.
Thanks,
TheDarkSide

Dear Darkside

Thank  you for your valuable information regarding the end device orphan notification.

from your  reply i thought that zigbee end devices send polling frame periodically to their parent after checking the channel is free or not.so in that context CSMA-CA is used.

is that right or wrong?

Yes, you are right about this.

thank you sir.

i observed the GTS fields in the one of the field as shown above.

1.what is the beacon request frame,which device generates it  and use of it .

2.in the second frame 0x7DFC is the router short address.second frame is comes after every beacon request frame.which information tells the second frame?

The frame format of the Beacon frame as standardized in IEEE 802.15.4 spec includes GTS field, but in the context of ZigBee all the fields are 0 which in fact means that the coordinator does not permit GTS requests and that there's no GTS descriptor allocation.
1. When a device search for a Zigbee network to join, it would send Beacon request. ZC/ZR in the radio coverage would responses with Beacon Frame.
2. You can refer to the slide at www.cse.yorku.ca/.../Zigbee-Standard-Talk.pdf

is that second frame is response frame of beacon request frame?

Yes, it is.

in that response frame showing only source address and source PAN .where is the destination address?

There is no destination address in beacon frame.

Then Which device receives that beacon response frame.

As I know, it's like broadcast. Every device with RX on at this moment would receive it. Device would check the information in Beacon Frame.