diff options
Diffstat (limited to 'src/osmo-bts-trx/loops.c')
| -rw-r--r-- | src/osmo-bts-trx/loops.c | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/src/osmo-bts-trx/loops.c b/src/osmo-bts-trx/loops.c index 926b4c6f..fc10c408 100644 --- a/src/osmo-bts-trx/loops.c +++ b/src/osmo-bts-trx/loops.c @@ -37,6 +37,11 @@ * MS Power loop */ +/*! compute the new MS POWER LEVEL communicated to the MS and store it in lchan. + * \param lchan logical channel for which to compute (and in which to store) new power value. + * \param[in] chan_nr RSL channel number of the channel, only used for logging purpose. + * \param[in] diff input delta value (in dB) + * \returns 0 in all cases */ static int ms_power_diff(struct gsm_lchan *lchan, uint8_t chan_nr, int8_t diff) { struct gsm_bts_trx *trx = lchan->ts->trx; @@ -44,14 +49,17 @@ static int ms_power_diff(struct gsm_lchan *lchan, uint8_t chan_nr, int8_t diff) uint16_t arfcn = trx->arfcn; int8_t new_power; + /* compute new target MS output power level based on current value subtracted by 'diff/2' */ new_power = lchan->ms_power_ctrl.current - (diff >> 1); if (diff == 0) return 0; + /* ms transmit power level cannot become negative */ if (new_power < 0) new_power = 0; + /* saturate at the maximum possible power level for the given band */ // FIXME: to go above 1W, we need to know classmark of MS if (arfcn >= 512 && arfcn <= 885) { if (new_power > 15) @@ -61,6 +69,8 @@ static int ms_power_diff(struct gsm_lchan *lchan, uint8_t chan_nr, int8_t diff) new_power = 19; } + /* don't ever change more than MS_{LOWER,RAISE}_MAX during one loop iteration, i.e. + * reduce the speed at which the MS transmit power can change */ /* a higher value means a lower level (and vice versa) */ if (new_power > lchan->ms_power_ctrl.current + MS_LOWER_MAX) new_power = lchan->ms_power_ctrl.current + MS_LOWER_MAX; @@ -83,11 +93,16 @@ static int ms_power_diff(struct gsm_lchan *lchan, uint8_t chan_nr, int8_t diff) ms_pwr_dbm(band, lchan->ms_power_ctrl.current), new_power, ms_pwr_dbm(band, new_power)); + /* store the resulting new MS power level in the lchan */ lchan->ms_power_ctrl.current = new_power; return 0; } +/*! Input a new RSSI value into the MS power control loop for the given logical channel. + * \param chan_state L1 channel state of the logical channel. + * \param rssi Received Signal Strength Indication (in dBm) + * \return 0 in all cases */ static int ms_power_val(struct l1sched_chan_state *chan_state, int8_t rssi) { /* ignore inserted dummy frames, treat as lost frames */ @@ -110,6 +125,10 @@ static int ms_power_val(struct l1sched_chan_state *chan_state, int8_t rssi) return 0; } +/*! Process a single clock tick of the MS power control loop. + * \param lchan Logical channel to which the clock tick applies + * \param[in] chan_nr RSL channel number (for logging purpose) + * \returns 0 in all cases */ static int ms_power_clock(struct gsm_lchan *lchan, uint8_t chan_nr, struct l1sched_chan_state *chan_state) { @@ -213,6 +232,14 @@ int ta_val(struct gsm_lchan *lchan, uint8_t chan_nr, return 0; } +/*! Process a SACCH event as input to the MS power control and TA loop. Function + * is called once every uplink SACCH block is received. + * \param l1t L1 TRX instance on which we operate + * \param chan_nr RSL channel number on which we operate + * \param chan_state L1 scheduler channel state of the channel on which we operate + * \param[in] rssi Receive Signal Strength Indication + * \param[in] toa256 Time of Arrival in 1/256 symbol periods + * \returns 0 in all cases */ int trx_loop_sacch_input(struct l1sched_trx *l1t, uint8_t chan_nr, struct l1sched_chan_state *chan_state, int8_t rssi, int16_t toa256) { @@ -220,15 +247,18 @@ int trx_loop_sacch_input(struct l1sched_trx *l1t, uint8_t chan_nr, .lchan[l1sap_chan2ss(chan_nr)]; struct phy_instance *pinst = trx_phy_instance(l1t->trx); + /* if MS power control loop is enabled, handle it */ if (pinst->phy_link->u.osmotrx.trx_ms_power_loop) ms_power_val(chan_state, rssi); + /* if TA loop is enabled, handle it */ if (pinst->phy_link->u.osmotrx.trx_ta_loop) ta_val(lchan, chan_nr, chan_state, toa256); return 0; } +/*! Called once every downlink SACCH block needs to be sent. */ int trx_loop_sacch_clock(struct l1sched_trx *l1t, uint8_t chan_nr, struct l1sched_chan_state *chan_state) { |