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Bluetooth: Controller: df: Fix IQ sample data saturation info drop

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Nordic Semiconductor Radio peripheral provides IQ samples as
12 bits signed integer with sign extended to 16 bits.
Where out of range IQ samples (saturated) have value -32768.

Due to conversion of IQ samples to 8 bit signed integer, required by
BT 5.3 Core Vol 4, Part E sections 7.7.65.21 and 7.7.65.22 the
saturation information was lost.

The PR fixes that issue by use of value -128 to mark saturated
IQ samples. Note that BT 5.3 Core does not give any particular
value of IQ sample a special meaning.

This is a vendor specific solution and does not affect other
implementations of lower link layer.

Signed-off-by: Piotr Pryga <piotr.pryga@nordicsemi.no>
This commit is contained in:
Piotr Pryga 2022-02-04 15:11:36 +01:00 • committed by Carles Cufí
commit d04456f4d9
2 changed files with 19 additions and 5 deletions
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8
subsys/bluetooth/controller/hci/hci.c
View file

@ -2846,8 +2846,8 @@ static void le_df_connectionless_iq_report(struct pdu_data *pdu_rx,
sep->sample_count = 0U;
} else {
for (uint8_t idx = 0U; idx < samples_cnt; ++idx) {
sep->sample[idx].i = IQ_SHIFT_12_TO_8_BIT(iq_report->sample[idx].i);
sep->sample[idx].q = IQ_SHIFT_12_TO_8_BIT(iq_report->sample[idx].q);
sep->sample[idx].i = IQ_CONVERT_12_TO_8_BIT(iq_report->sample[idx].i);
sep->sample[idx].q = IQ_CONVERT_12_TO_8_BIT(iq_report->sample[idx].q);
}
sep->sample_count = samples_cnt;
@ -2969,8 +2969,8 @@ static void le_df_connection_iq_report(struct node_rx_pdu *node_rx, struct net_b
sep->sample_count = 0U;
} else {
for (uint8_t idx = 0U; idx < samples_cnt; ++idx) {
sep->sample[idx].i = IQ_SHIFT_12_TO_8_BIT(iq_report->sample[idx].i);
sep->sample[idx].q = IQ_SHIFT_12_TO_8_BIT(iq_report->sample[idx].q);
sep->sample[idx].i = IQ_CONVERT_12_TO_8_BIT(iq_report->sample[idx].i);
sep->sample[idx].q = IQ_CONVERT_12_TO_8_BIT(iq_report->sample[idx].q);
}
sep->sample_count = samples_cnt;
}

16
subsys/bluetooth/controller/ll_sw/nordic/lll/lll_df_types.h
View file

@ -66,8 +66,22 @@ struct lll_df_adv_cfg {
#define IQ_SAMPLE_CNT (PDU_DC_LL_HEADER_SIZE + LL_LENGTH_OCTETS_RX_MAX)
#define RSSI_DBM_TO_DECI_DBM(x) (-(x) * 10)
#define IQ_SHIFT_12_TO_8_BIT(x) ((int8_t)((x) >> 4))
/* Macro that represents out of range IQ sample (saturated). Value provided by Radio specifications.
* It is not defined by Bluetooth Core specification. This is the vendor specific value.
*
* Nordic Semiconductor Radio peripheral provides 16 bit wide IQ samples.
* BT 5.3 Core specification Vol 4, Part E sectons 7.7.65.21 and 7.7.65.22 limit size of
* IQ samples to 8 bits.
* To mitigate the limited accuratcy and losing information about saturated IQ samples a 0x80 value
* is selected to serve the purpose.
*/
#define IQ_SAMPLE_STATURATED_16_BIT 0x8000
#define IQ_SAMPLE_STATURATED_8_BIT 0x80
#define IQ_SHIFT_12_TO_8_BIT(x) ((int8_t)((x) >> 4))
#define IQ_CONVERT_12_TO_8_BIT(x) \
(((x) == IQ_SAMPLE_STATURATED_16_BIT) ? IQ_SAMPLE_STATURATED_8_BIT : \
IQ_SHIFT_12_TO_8_BIT((x)))
/* Structure to store an single IQ sample */
struct iq_sample {
int16_t i;