DECT NR+: How to configure the Physical Layer Control Field Type 2 Header

[Luca12]

Hey,

I’m currently evaluating DECT NR+ using two nRF9151 DKs with the nRF Connect SDK v2.9.0.

According to the ETSI specification (ETSI TS 103 636-4 V2.1.1), the Physical Layer Control Field Type 1 is only used for beacon messages. Based on this, I tried modifying the sample to use Type 2 for broadcast or unicast messages. Unfortunately, I haven’t been able to get it working. Could you please provide more information on how to configure the header properly?

Here’s my current configuration: I changed the phy_type in tx_op_params to 1 and added the required fields to the header. However, I’m unsure how to correctly specify the feedback option. The ETSI spec mentions an option for "no feedback," which would be sufficient for my testing, but I couldn’t figure out how to set this using your implementation (referring to Table 6.2.2-1).

uint32_t receiver_id = 0xffff;

struct phy_ctrl_field_type_2 header = {
	.header_format = 0x0,
	.packet_length_type = 0x0,
	.packet_length = 0x01,
	.short_network_id = (CONFIG_NETWORK_ID & 0xff),
	.transmitter_id_hi = (device_id >> 8),
	.transmitter_id_lo = (device_id & 0xff),
	.transmit_power = CONFIG_TX_POWER,
	.df_mcs = CONFIG_MCS,
	.receiver_id_hi = (receiver_id >> 8),
	.receiver_id_lo = (receiver_id & 0xff),
	.df_harq_process_num = 0x0,
	.df_new_data_indication = 0x1,
	.df_redundancy_version = 0x0,
	.num_spatial_streams = 0x0,
	.feedback = {},
};

struct nrf_modem_dect_phy_tx_params tx_op_params = {
	.start_time = 0,
	.handle = handle,
	.network_id = CONFIG_NETWORK_ID,
	.phy_type = 1,
	.lbt_rssi_threshold_max = 0,
	.carrier = CONFIG_CARRIER,
	.lbt_period = NRF_MODEM_DECT_LBT_PERIOD_MAX,
	.phy_header = (union nrf_modem_dect_phy_hdr *)&header,
	.data = data,
	.data_size = data_len,
};

err = nrf_modem_dect_phy_tx(&tx_op_params);

Any help or guidance would be greatly appreciated.

Best regards

Luca

[dejans]

Hi,

Based on this, I tried modifying the sample to use Type 2 for broadcast or unicast messages.

Which specific sample did you try to modify?

Best regards,
Dejan

[Luca12]

Hi,

I am referring to the sample "DECT NR+ PHY Hello" from the SDK. It uses a Type 1 header for broadcast transmission, which does not provide an option to specify a receiver ID. According to the specification, a Type 2 header is required to enable unicast transmission to a specific receiver.

Best regards
Luca

[dejans]

Hi Luca,

You can see how header types are defined in the dect_shell sample. Relevant file is src/dect/common/dect_common.h.

Best regards,
Dejan

[Luca12]

Hi Dejan,

thank you. It is working now. The main issue was that I hadn’t adjusted the receiver ID filter in rx_op_params, which was still set to broadcast mode.

Best regards
Luca