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Z-Stack Settings for multi-hop(25 hops) network

adarsh.pll
Intellectual 580 points
Other Parts Discussed in Thread: Z-STACK, CC2530, CC2520

Dear TI Employee

Recently I went through the TI’s Application Report (SWRA427B–November 2013) by Suyash Jain titled “Breaking the 400-Node ZigBee® Network Barrier With TI’s ZigBee SoC and Z-Stack™ Software.”

Section 4 of this document throws light on the Z-Stack Settings( like NWK_MAX_DEVICE_LIST ,LINK_DOWN_TRIGGER, NWK_ROUTE_AGE_LIMIT, BCAST_DELIVERY_TIME, ROUTE_DISCOVERY_TIME,  NWK_LINK_ STATUS_PERIOD etc.) for the large network but limited to 4 hops. I would request Suyash (or any other TI employee who can support) about the settings that need modification(along with the optimum value) when the network is as follows:

1)     25 nodes

2)     placed on ground

3)     In a straight line at 25 mtr distance one after other(transmitting at 5dbm).

4)     4 nodes(of the 25 nodes) sending data every 120ms( 85 bytes as payload) and all 25 sending 10 bytes as payload every 5 seconds.

5)     So probably having 25 hops in a worst case.

 Please consider this as really important.


  • 0
    Intellectual 580 points

    Hi

    Can you help with the above queries.

    Adarsh

  • 0 in reply to adarsh.pll
    Intellectual 580 points

    Hi Suyash

    In addition to above queries can you also throw some light on below given points:

    1) How to program large number of devices without physically connecting each device to the PC? Also we need to assign separate IDs to each device.

    2) What is significance of ED_RF_POWER_MAX_DBM and ED_RF_POWER_MIN_DBM in formation of a link. Why the value set as -88 and 6. Can we modify?

    3) Why a device don't stop sending route request packets even though it received a route reply from its neighbour?

    Adarsh

  • 0 in reply to adarsh.pll
    TI__Genius 10650 points

    Hi Adarsh,

    Do you see an issue when you use the application note to setup your network. If yes can you please describe the network behavior/issues that you have when setting up the network. 

    For your second post:

    1. You can use OTA in order to download the code wirelessly, Please see the document Z-Stack OTA Upgrade User's Guide.pdf included with the Z-Stack install in the Documents Folder. 

    2. The equation used to convert the RSSI to LQI used in the Stack is:

    LQI = (MAC_SPEC_ED_MAX * (rssiDbm - ED_RF_POWER_MIN_DBM)) / (ED_RF_POWER_MAX_DBM - ED_RF_POWER_MIN_DBM);

    Where

    rssiDbm =  Read RSSI value by the stack

    MAC_SPEC_ED_MAX = 255

    ED_RF_POWER_MIN_DBM = -97 + 10 (10 is added to the minimum sensitivity (-97dBm for CC2530) of the Radio as per IEEE 802.15.4 spec as a threshold)

    ED_RF_POWER_MAX_DBM = Signal at which the receiver saturates =10dBm for CC2530

    3. Do you have a log for this. But, this can happen if the link between the neighbors is not good. If after setting up the route, the route is broken then the device will re-send the Route requests in order to dynamically correct the route to the destination device. 

    Hope this helps.

  • 0 in reply to Suyash Jain
    TI__Genius 10650 points

    Hi Adarsh,

    Additionally: please refer to the document to understand the parameters and there effect on network performance especially those that limit the radius or number of hops that the messages will take for example: DEF_NWK_RADIUS, DEFAULT_ROUTE_REQUEST_RADIUS, You will have to adapt the parameters for your network configuration. 

    Also, refer to the section 5.4 and 5.5 of Z-Stack developers guide to understand important parameters ex- CONCENTRATOR_RADIUS for the Many to One Source Routing implementation.

    Hope this helps

  • 0 in reply to Suyash Jain
    Intellectual 580 points

    Hi Suyash

    After using the application note suggestions it helped. The problem of lots of route request in the network reduced.

    But still there are route request infrequently.
    It will be difficult to adapt the application when we are having so many parameters. Modifying, testing and analysis may take lot of time.

    Related to second post:

    1) I haven't tested it yet. Still would like to ask if OTA download depends on size of application code?

    2) Can we modify LQI /RSSI parameters so that it helps to reduce route requests? That is link once made should not be broken till device is in the region of influence.say by increasing the ED_RF_POWER_MIN_DBM to -80dbm. Will it help?Also we are working on msp430+cc2520 hardware.

    3)Devices are placed very close. So logically they should not exchange route request packets. Why the packets are present? Will send you log soon.

    I have kept the values of DEF_NWK_RADIUS, DEFAULT_ROUTE_REQUEST_RADIUS as default i.e 30 as we may be probably looking at a 25 log network.

    Is it necesary to use MANY TO ONE source routing to achieve our objectives.

    Regards,

    Adarsh