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CC1310: 15.4-Stack, Can sensor device using Active Scan to select the right network in Beacon mode

Intellectual 2990 points

Replies: 3

Views: 810

Part Number: CC1310

Hi Team,

My customer will deploy several 15.4-Stack based sub-1ghz network in real scenario, customer will using Beacon mode from 15.4-Stack.

They want the sensor device to select better Gateway to join, such as better RSSI.

The default operation in the beacon mode, sensor device will use passive scan in every channel to wait for the Beacon send from Gateway.

But this process may consume a lot of power if the BO is big and all the channel mask are enabled. 

So can we use the active scan to choose the right Beacon/Gateway, then switch to the specific channel to do the passive scan to sync with selected gateway.

Thanks.

Victor Xu

  • Hey Victor,

    That behavior violates the spec. According to IEEE 802.15.4-2015 section 6.3.1.2 (Active and passive channel scan):

    "If a coordinator of a beacon-enabled PAN receives the Beacon Request command, it shall ignore the
    command and continue transmitting its periodic beacons as usual. If a coordinator of a nonbeacon-enabled
    PAN receives this command, it shall transmit a single Beacon frame using unslotted CSMA-CA."

    This means a beacon-request packet receive by the collector in beacon-mode will be ignored.

    A possible solution would be to dynamically change the beacon order at runtime. For example when you enable permit join on the collector also set the beacon order to be quick, when you disable it you can put it back to what your application needs.

    ~Brocklobsta

  • In reply to Brocklobsta:

    Hi Brock,
    If the Gateway change the BO in order to let new device join the network faster and low power consumption, but for the device already joined network maybe not suitable since they will wake up with short periodic to receive Beacon. I'm not sure if this is a good idea.
    Can we realize to let PAN Coord response the Beacon after receiving Beacon request even in Beacon mode. It maybe beyond the spec, but seems better for some application requirement.
    Thanks.
    Victor
  • In reply to Victor Xu:

    Victor,

    The stack does not support responding to beacon requests with beacons in beacon mode.One reason for this is to not de-synchronize nodes in the network. If a node loses synch while a device is trying to join, it will listen for a series of beacon to lock in the timing. If the collector is responding to beacon requests asychronously, then the node will have a hard time resynching and wasting much more current (rx always on while listening for beacons).

    You are correct that by reducing the BO the overall power consumption of every node in the network increases, but this increase in only temperary. Once all desired devices have join the network the BO can be increased to reduce power consumption. I imagine the BO will only be reduced for a minute or so. This solution can be fine tuned by selecting the optimal BO for joining. I also recommend BO=SO for the joining process.

    ~Brocklobsta

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