ARIB Regulation Type

When using the ARIB regulation type, certain TI 15.4-Stack features are different. This section covers these features.

For information on how to choose regulation type, see Data Rate and PHY.

Minimum Tx Off Time

The minimum TX off-time, also known as the pause duration, specifies the minimum amount of time during which the transmitter shall remain off following any transmission. According to the regulation, a minimum Tx off time of 2 ms is implemented. Packets that are scheduled with less than the min tx-off time interval will be delayed until the minimum Tx off time has passed.

Configuring Min-Tx-Off

Min-Tx-Off is always enabled when using ARIB mode. If you set Minimum TX Off-Time (ms) to 0, it’s equivalent to disabling this feature. If you want to use 0 or a custom value for minimum Tx off time, follow the steps below.

  1. Open SysConfig -> RF STACKS -> TI 15.4-Stack -> Network -> MAC -> Advanced

  2. To enable the feature, check the box next to Custom Minimum TX Off-Time

  3. You can choose a time in ms.

../_images/min-tx-time-sysconfig.png

Figure 77. Configure minimum Tx off time in SysConfig.

Duty-Cycling

The purpose of Duty Cycling is to limit the amount of data a device can send in a given time frame and is governed by regulations. Duty cycling is measured in air time. Air time includes all tx, including both the first transmission and retransmission of data packets. ACK frames can be ignored as their packet sizes are negligible.

When duty-cycling is active, the TI 15.4-Stack keeps track of and restricts the time spent in Tx by the device. The TI 15.4-Stack keeps track of all packets sent during the last 5 minutes. When a packet is scheduled, whether from the application or from the stack, the duty-cycle is checked before transmitting it.

If the maximum permitted “Tx on time” has already been spent, the packet will be denied. In this case a Channel Access Error is thrown.

You can use a PIB retrieval API to check your current duty-cycle status. Please see Duty Cycle PIB Access and Diagnostics.

Configuring Duty-Cycling

To enable or disable duty-cycling, open SysConfig:

  1. Open SysConfig -> RF STACKS -> TI 15.4-Stack -> Network -> MAC -> Advanced

  2. Check or uncheck the box next to Enable Duty Cycle to enable or disable duty-cycling.

  3. You can also set the duty cycle threshold. When you set a new threshold value, SysConfig will calculate and display your duty cycle period.

../_images/duty-cycle-sysconfig.png

Figure 78. Configure Duty-Cycling in SysConfig.

Duty Cycle PIB Access and Diagnostics

The following global variables can be used to check the duty cycle status. They are defined and documented in api_mac.h.

Attribute name

Data Type

Get

Set

ApiMac_attribute_dutyCycleEnabled

Bool

ApiMac_mlmeGetReqBool

ApiMac_mlmeSetReqBool

ApiMac_attribute_dutyCycleStatus

uint8_t

ApiMac_mlmeGetReqUint8

ApiMac_mlmeSetReqUint8 (only for debug purposes)

ApiMac_attribute_dutyCycleRegulated

uint32_t

ApiMac_mlmeGetReqUint32

ApiMac_mlmeSetReqUint32

ApiMac_attribute_dutyCycleUsed

uint32_t

ApiMac_mlmeGetReqUint32

ApiMac_mlmeSetReqUint32 (only for debug purposes)

ApiMac_attribute_dutyCyclePtr

uint32_t

ApiMac_mlmeGetReqUint32

ApiMac_mlmeSetReqUint32 (only for debug purposes)

ApiMac_attribute_dutyCycleBucket

Array of length: sizeof(DC_NODE_ENTRY_s) * DUTY_CYCLE_BUCKETS

ApiMac_mlmeGetReqArray

ApiMac_mlmeSetReqArray (only for debug purposes)

  • You will also find ApiMac_attribute_dutyCycleLimited and ApiMac_attribute_dutyCycleCritical defined, however these are not used by TI 15.4-Stack.

Beacon Mode

When using beacon mode, the TI 15.4-Stack will make sure there is always duty cycle budget for beacon frames. This is done by pre-allocating beacon frames. Scheduled packets will thus be compared to:

  • What frames have already been sent

  • Which beacon frames will be sent

Note

When using ARIB duty-cycling, it is not possible to go below beacon order 4. This is because the beacon frames alone would exceed the permitted duty-cycling.

Clear Channel Assessment (CCA)

Clear channel assessment (CCA) is performed for all packets longer than 5 ms. This means ACK packets do not need CCA.

Packet Sniffer

For instructions on how to configure and use the SmartRF Protocol Packet sniffer with ARIB mode, please see SmartRF Protocol Packet Sniffer.

Coprocessor Example

When using the coprocessor example, it should be noted that ARIB specific features that are enabled (duty-cycling, min-tx off) will be used by all PHYs. This means, even if FCC is selected over the NWP interface, these restrictions will still be enforced.