power_control: check-in new parameters and default values

For the sake of simplicity, the old structures that are still used
by MS/BS power control loops are kept in place.  Migration to the
new structures requires additional changes to the existing power
control logic, so it will be done in the follow-up changes.

The new parameters are integrated as follows:

  + struct gsm_bts - a BTS instance:
  |   Hard-coded default (fall-back) parameters for all transceivers.
  |
  +-+-> struct gsm_bts_trx - a TRX instance (transceiver):
    |     Default parameters for all logical channels inherited from
    |     'struct gsm_bts' at start-up.  May be overwritten by the
    |     BSC using ip.access specific 'Measurement Pre-processing
    |     Defaults' message on the A-bis/RSL interface.
    |
    +---> struct gsm_lchan - a logical channel (e.g. TCH or SDCCH):
            Connection specific parameters inherited from 'struct
            gsm_bts_trx'.  May be overwritten by parameters sent
            by the BSC in CHANnel ACTIVation and other messages.

Change-Id: I6d41eb238aa6d4f5b77596c5477c2ecbe86de2a8
Related: SYS#4918

include/osmo-bts/bts.h

@@ -321,10 +321,14 @@ struct gsm_bts {
 		bool vty_override;	/* OML value overridden by VTY */
 	} radio_link_timeout;
 
-	/* Uplink/Downlink power control */
+	/* Uplink/Downlink power control (legacy parameters) */
 	struct bts_power_ctrl_params ul_power_ctrl;
 	struct bts_power_ctrl_params dl_power_ctrl;
 
+	/* Default (fall-back) Dynamic Power Control parameters for all transceivers */
+	struct gsm_power_ctrl_params bs_dpc_params; /* BS Dynamic Power Control */
+	struct gsm_power_ctrl_params ms_dpc_params; /* MS Dynamic Power Control */
+
 	/* used by the sysmoBTS to adjust band */
 	uint8_t auto_band;
 

include/osmo-bts/bts_trx.h

@@ -32,6 +32,8 @@ struct gsm_bts_trx {
 
 
 	struct trx_power_params power_params;
+	struct gsm_power_ctrl_params *bs_dpc_params; /* BS Dynamic Power Control */
+	struct gsm_power_ctrl_params *ms_dpc_params; /* MS Dynamic Power Control */
 	bool ms_pwr_ctl_soft; /* is power control loop done by osmocom software? */
 
 	struct {

include/osmo-bts/gsm_data.h

@@ -161,10 +161,65 @@ struct gsm_rep_facch {
 	uint32_t fn;
 };
 
-/* Depending on the context (MS or BS power control), fields 'current' and 'max'
- * reflect either the MS power level (magic numbers), or BS Power reduction level
- * (attenuation, in dB).  Field 'avg100_rxlev_dbm' is always in dBm. */
+/* MS/BS Power related measurement averaging algo */
+enum gsm_power_ctrl_meas_avg_algo {
+	GSM_PWR_CTRL_MEAS_AVG_ALGO_NONE			= 0x00,
+	GSM_PWR_CTRL_MEAS_AVG_ALGO_UNWEIGHTED		= 0x01,
+	GSM_PWR_CTRL_MEAS_AVG_ALGO_WEIGHTED		= 0x02,
+	GSM_PWR_CTRL_MEAS_AVG_ALGO_MOD_MEDIAN		= 0x03,
+	/* EWMA is an Osmocom specific algo */
+	GSM_PWR_CTRL_MEAS_AVG_ALGO_OSMO_EWMA		= 0x04,
+};
+
+/* MS/BS Power related measurement parameters */
+struct gsm_power_ctrl_meas_params {
+	/* Thresholds (see 3GPP TS 45.008, section A.3.2.1) */
+	uint8_t lower_thresh; /* lower (decreasing) direction */
+	uint8_t upper_thresh; /* upper (increasing) direction */
+
+	/* Threshold Comparators for lower (decreasing) direction */
+	uint8_t lower_cmp_p; /* P1 for RxLev, P3 for RxQual */
+	uint8_t lower_cmp_n; /* N1 for RxLev, N3 for RxQual */
+	/* Threshold Comparators for upper (increasing) direction */
+	uint8_t upper_cmp_p; /* P2 for RxLev, P4 for RxQual */
+	uint8_t upper_cmp_n; /* N2 for RxLev, N4 for RxQual */
+
+	/* Hreqave and Hreqt (see 3GPP TS 45.008, Annex A) */
+	uint8_t h_reqave;
+	uint8_t h_reqt;
+
+	/* AVG algorithm and its specific parameters */
+	enum gsm_power_ctrl_meas_avg_algo algo;
+	union {
+		/* Exponentially Weighted Moving Average */
+		struct {
+			/* Smoothing factor: higher the value - less smoothing */
+			uint8_t alpha; /* 1 .. 99 (in %) */
+		} ewma;
+	};
+};
+
+/* MS/BS Power Control parameters */
+struct gsm_power_ctrl_params {
+	/* Power change step size (maximum) */
+	uint8_t inc_step_size_db; /* increasing direction */
+	uint8_t red_step_size_db; /* reducing direction */
+
+	/* Measurement averaging parameters for RxLev & RxQual */
+	struct gsm_power_ctrl_meas_params rxqual_meas;
+	struct gsm_power_ctrl_meas_params rxlev_meas;
+};
+
+/* Default MS/BS Power Control parameters */
+extern const struct gsm_power_ctrl_params power_ctrl_params_def;
+
 struct lchan_power_ctrl_state {
+	/* Dynamic Power Control parameters (NULL in static mode) */
+	const struct gsm_power_ctrl_params *dpc_params;
+
+	/* Depending on the context (MS or BS power control), fields 'current' and 'max'
+	 * reflect either the MS power level (magic numbers), or BS Power reduction level
+	 * (attenuation, in dB). */
 	uint8_t current;
 	uint8_t max;
 	bool fixed;
@@ -319,10 +374,14 @@ struct gsm_lchan {
 	/* RTP header Marker bit to indicate beginning of speech after pause  */
 	bool rtp_tx_marker;
 
-	/* MS/BS power control */
+	/* MS/BS power control state */
 	struct lchan_power_ctrl_state ms_power_ctrl;
 	struct lchan_power_ctrl_state bs_power_ctrl;
 
+	/* MS/BS Dynamic Power Control parameters */
+	struct gsm_power_ctrl_params ms_dpc_params;
+	struct gsm_power_ctrl_params bs_dpc_params;
+
 	struct msgb *pending_rel_ind_msg;
 
 	/* ECU (Error Concealment Unit) state */

src/common/bts.c

@@ -330,7 +330,7 @@ int bts_init(struct gsm_bts *bts)
 	bts->rtp_port_range_next = bts->rtp_port_range_start;
 	bts->rtp_ip_dscp = -1;
 
-	/* Default UL/DL power control parameters */
+	/* Default UL/DL power control parameters (legacy) */
 	bts->ul_power_ctrl = bts->dl_power_ctrl = \
 	(struct bts_power_ctrl_params) {
 		.target_dbm = -75,
@@ -346,6 +346,10 @@ int bts_init(struct gsm_bts *bts)
 		}
 	};
 
+	/* Default (fall-back) MS/BS Power control parameters */
+	bts->bs_dpc_params = power_ctrl_params_def;
+	bts->ms_dpc_params = power_ctrl_params_def;
+
 	/* configurable via OML */
 	bts->load.ccch.load_ind_period = 112;
 	load_timer_start(bts);

src/common/bts_trx.c

@@ -113,6 +113,10 @@ struct gsm_bts_trx *gsm_bts_trx_alloc(struct gsm_bts *bts)
 	if (trx->nr != 0)
 		trx->nominal_power = bts->c0->nominal_power;
 
+	/* Default (fall-back) Dynamic Power Control parameters */
+	trx->bs_dpc_params = &bts->bs_dpc_params;
+	trx->ms_dpc_params = &bts->ms_dpc_params;
+
 	llist_add_tail(&trx->list, &bts->trx_list);
 
 	return trx;

src/common/gsm_data.c

@@ -420,3 +420,31 @@ int lchan2ecu_codec(const struct gsm_lchan *lchan)
 		return -1;
 	}
 }
+
+/* Default MS/BS Power Control parameters (see 3GPP TS 45.008, table A.1) */
+const struct gsm_power_ctrl_params power_ctrl_params_def = {
+	/* Power increasing/reducing step size */
+	.inc_step_size_db = 4, /* FIXME: PWR_RAISE_MAX_DB */
+	.red_step_size_db = 8, /* FIXME: PWR_LOWER_MAX_DB */
+
+	/* RxLev measurement parameters */
+	.rxlev_meas = {
+		/* Thresholds for RxLev (see 3GPP TS 45.008, A.3.2.1) */
+		.lower_thresh = 32, /* L_RXLEV_XX_P (-78 dBm) */
+		.upper_thresh = 38, /* U_RXLEV_XX_P (-72 dBm) */
+
+		/* NOTE: only Osmocom specific EWMA is supported */
+		.algo = GSM_PWR_CTRL_MEAS_AVG_ALGO_OSMO_EWMA,
+		.ewma.alpha = 50, /* Smoothing factor 50% */
+	},
+
+	/* RxQual measurement parameters */
+	.rxqual_meas = {
+		/* Thresholds for RxQual (see 3GPP TS 45.008, A.3.2.1) */
+		.lower_thresh = 3, /* U_RXQUAL_XX_P (0.8% <= BER < 1.6%) */
+		.upper_thresh = 0, /* L_RXQUAL_XX_P (BER < 0.2%) */
+
+		/* FIXME: RxQual averaging is not yet implemented */
+		.algo = GSM_PWR_CTRL_MEAS_AVG_ALGO_NONE,
+	},
+};