<p>laforge <strong>submitted</strong> this change.</p><p><a href="https://gerrit.osmocom.org/c/osmo-bts/+/15971">View Change</a></p><div style="white-space:pre-wrap">Approvals:
Jenkins Builder: Verified
laforge: Looks good to me, approved
</div><pre style="font-family: monospace,monospace; white-space: pre-wrap;">bts-trx: Implement MS Power control loop calculations using dBm instead of ctl levels<br><br>Some bands, such as DCS1800, contain power levels such as 29, 30 and 31 not following same<br>unified sequence other power levels follow regarding conversion to dBm<br>values.<br>This makes extremly complex and prone to error comparing different power<br>levels. Let's instead use dBm values to calculate and crop desired new<br>value, and then convert it back to TS 05.05 ms power control level<br>value.<br><br>With this commit the control loop should be able to manage correctly the MS power<br>levels explained above.<br><br>Related: OS#4244<br>Change-Id: I0160637c5ffa606ee3081ad30be8e6f2a42b725b<br>---<br>M src/osmo-bts-trx/loops.c<br>M src/osmo-bts-trx/loops.h<br>2 files changed, 58 insertions(+), 31 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/src/osmo-bts-trx/loops.c b/src/osmo-bts-trx/loops.c</span><br><span>index 4e77bca..b2b163a 100644</span><br><span>--- a/src/osmo-bts-trx/loops.c</span><br><span>+++ b/src/osmo-bts-trx/loops.c</span><br><span>@@ -23,11 +23,13 @@</span><br><span> #include <unistd.h></span><br><span> #include <stdlib.h></span><br><span> #include <errno.h></span><br><span style="color: hsl(120, 100%, 40%);">+#include <inttypes.h></span><br><span> </span><br><span> #include <osmo-bts/gsm_data.h></span><br><span> #include <osmo-bts/logging.h></span><br><span> #include <osmo-bts/l1sap.h></span><br><span> #include <osmocom/core/bits.h></span><br><span style="color: hsl(120, 100%, 40%);">+#include <osmocom/gsm/gsm_utils.h></span><br><span> </span><br><span> #include "trx_if.h"</span><br><span> #include "l1_if.h"</span><br><span>@@ -39,45 +41,70 @@</span><br><span> </span><br><span> /*! compute the new MS POWER LEVEL communicated to the MS and store it in lchan.</span><br><span> * \param lchan logical channel for which to compute (and in which to store) new power value.</span><br><span style="color: hsl(0, 100%, 40%);">- * \param[in] diff input delta value (in dB) */</span><br><span style="color: hsl(120, 100%, 40%);">+ * \param[in] diff input delta value (in dB). How many dBs measured power</span><br><span style="color: hsl(120, 100%, 40%);">+ * should be increased (+) or decreased (-) to reach expected power.</span><br><span style="color: hsl(120, 100%, 40%);">+ */</span><br><span> static void ms_power_diff(struct gsm_lchan *lchan, int8_t diff)</span><br><span> {</span><br><span> struct gsm_bts_trx *trx = lchan->ts->trx;</span><br><span> enum gsm_band band = trx->bts->band;</span><br><span style="color: hsl(0, 100%, 40%);">- uint16_t arfcn = trx->arfcn;</span><br><span> int8_t new_power; /* TS 05.05 power level */</span><br><span style="color: hsl(120, 100%, 40%);">+ int8_t new_dbm, current_dbm, bsc_max_dbm, pwclass_max_dbm;</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- /* compute new target MS output power level based on current value subtracted by 'diff/2' */</span><br><span style="color: hsl(0, 100%, 40%);">- new_power = lchan->ms_power_ctrl.current - (diff >> 1);</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span style="color: hsl(0, 100%, 40%);">- if (diff == 0)</span><br><span style="color: hsl(120, 100%, 40%);">+ /* power levels change in steps of 2 dB, so a smaller diff will end up in no change */</span><br><span style="color: hsl(120, 100%, 40%);">+ if (diff < 2 && diff > -2)</span><br><span> return;</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- /* ms transmit power level cannot become negative */</span><br><span style="color: hsl(0, 100%, 40%);">- if (new_power < 0)</span><br><span style="color: hsl(0, 100%, 40%);">- new_power = 0;</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span style="color: hsl(0, 100%, 40%);">- /* Don't ask for smaller ms power level than the one set by BSC upon RSL CHAN ACT */</span><br><span style="color: hsl(0, 100%, 40%);">- if (new_power < lchan->ms_power)</span><br><span style="color: hsl(0, 100%, 40%);">- new_power = lchan->ms_power;</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span style="color: hsl(0, 100%, 40%);">- /* saturate at the maximum possible power level for the given band */</span><br><span style="color: hsl(0, 100%, 40%);">- // FIXME: to go above 1W, we need to know classmark of MS</span><br><span style="color: hsl(0, 100%, 40%);">- if (arfcn >= 512 && arfcn <= 885) {</span><br><span style="color: hsl(0, 100%, 40%);">- if (new_power > 15)</span><br><span style="color: hsl(0, 100%, 40%);">- new_power = 15;</span><br><span style="color: hsl(0, 100%, 40%);">- } else {</span><br><span style="color: hsl(0, 100%, 40%);">- if (new_power > 19)</span><br><span style="color: hsl(0, 100%, 40%);">- new_power = 19;</span><br><span style="color: hsl(120, 100%, 40%);">+ current_dbm = ms_pwr_dbm(band, lchan->ms_power_ctrl.current);</span><br><span style="color: hsl(120, 100%, 40%);">+ if (current_dbm < 0) {</span><br><span style="color: hsl(120, 100%, 40%);">+ LOGPLCHAN(lchan, DLOOP, LOGL_NOTICE,</span><br><span style="color: hsl(120, 100%, 40%);">+ "Failed to calculate dBm for power ctl level %" PRIu8 " on band %s\n",</span><br><span style="color: hsl(120, 100%, 40%);">+ lchan->ms_power_ctrl.current, gsm_band_name(band));</span><br><span style="color: hsl(120, 100%, 40%);">+ return;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+ bsc_max_dbm = ms_pwr_dbm(band, lchan->ms_power);</span><br><span style="color: hsl(120, 100%, 40%);">+ if (bsc_max_dbm < 0) {</span><br><span style="color: hsl(120, 100%, 40%);">+ LOGPLCHAN(lchan, DLOOP, LOGL_NOTICE,</span><br><span style="color: hsl(120, 100%, 40%);">+ "Failed to calculate dBm for power ctl level %" PRIu8 " on band %s\n",</span><br><span style="color: hsl(120, 100%, 40%);">+ lchan->ms_power, gsm_band_name(band));</span><br><span style="color: hsl(120, 100%, 40%);">+ return;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- /* don't ever change more than MS_{LOWER,RAISE}_MAX during one loop iteration, i.e.</span><br><span style="color: hsl(120, 100%, 40%);">+ /* don't ever change more than MS_{LOWER,RAISE}_MAX_DBM during one loop iteration, i.e.</span><br><span> * reduce the speed at which the MS transmit power can change */</span><br><span> /* a higher value means a lower level (and vice versa) */</span><br><span style="color: hsl(0, 100%, 40%);">- if (new_power > lchan->ms_power_ctrl.current + MS_LOWER_MAX)</span><br><span style="color: hsl(0, 100%, 40%);">- new_power = lchan->ms_power_ctrl.current + MS_LOWER_MAX;</span><br><span style="color: hsl(0, 100%, 40%);">- else if (new_power < lchan->ms_power_ctrl.current - MS_RAISE_MAX)</span><br><span style="color: hsl(0, 100%, 40%);">- new_power = lchan->ms_power_ctrl.current - MS_RAISE_MAX;</span><br><span style="color: hsl(120, 100%, 40%);">+ if (diff > MS_RAISE_MAX_DB)</span><br><span style="color: hsl(120, 100%, 40%);">+ diff = MS_RAISE_MAX_DB;</span><br><span style="color: hsl(120, 100%, 40%);">+ else if (diff < -MS_LOWER_MAX_DB)</span><br><span style="color: hsl(120, 100%, 40%);">+ diff = -MS_LOWER_MAX_DB;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ new_dbm = current_dbm + diff;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Make sure new_dbm is never negative. ms_pwr_ctl_lvl() can later on</span><br><span style="color: hsl(120, 100%, 40%);">+ cope with any unsigned dbm value, regardless of band minimal value. */</span><br><span style="color: hsl(120, 100%, 40%);">+ if (new_dbm < 0)</span><br><span style="color: hsl(120, 100%, 40%);">+ new_dbm = 0;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Don't ask for smaller ms power level than the one set by BSC upon RSL CHAN ACT */</span><br><span style="color: hsl(120, 100%, 40%);">+ if (new_dbm > bsc_max_dbm)</span><br><span style="color: hsl(120, 100%, 40%);">+ new_dbm = bsc_max_dbm;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Make sure in no case the dBm value is higher than the one of ms</span><br><span style="color: hsl(120, 100%, 40%);">+ power class 1 (the one with more output power) for the given band.</span><br><span style="color: hsl(120, 100%, 40%);">+ Ideally we should catch the MS specific power class and apply it</span><br><span style="color: hsl(120, 100%, 40%);">+ here, but for now let's assume the BSC sent us one taking the power</span><br><span style="color: hsl(120, 100%, 40%);">+ class into account. */</span><br><span style="color: hsl(120, 100%, 40%);">+ pwclass_max_dbm = (int)ms_class_gmsk_dbm(band, 1);</span><br><span style="color: hsl(120, 100%, 40%);">+ if (pwclass_max_dbm >= 0 && new_dbm > pwclass_max_dbm)</span><br><span style="color: hsl(120, 100%, 40%);">+ new_dbm = pwclass_max_dbm;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ new_power = ms_pwr_ctl_lvl(band, new_dbm);</span><br><span style="color: hsl(120, 100%, 40%);">+ if (new_power < 0) {</span><br><span style="color: hsl(120, 100%, 40%);">+ LOGPLCHAN(lchan, DLOOP, LOGL_NOTICE,</span><br><span style="color: hsl(120, 100%, 40%);">+ "Failed to retrieve power level for %" PRId8 " dBm on band %d\n",</span><br><span style="color: hsl(120, 100%, 40%);">+ new_dbm, band);</span><br><span style="color: hsl(120, 100%, 40%);">+ return;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span> </span><br><span> if (lchan->ms_power_ctrl.current == new_power) {</span><br><span> LOGPLCHAN(lchan, DLOOP, LOGL_INFO, "Keeping MS new_power at control level %d (%d dBm)\n",</span><br><span>@@ -138,8 +165,8 @@</span><br><span> </span><br><span> /* if no burst was received from MS at clock */</span><br><span> if (chan_state->meas.rssi_count == 0) {</span><br><span style="color: hsl(0, 100%, 40%);">- LOGPLCHAN(lchan, DLOOP, LOGL_NOTICE, "LOST SACCH frame, so we raise MS power\n");</span><br><span style="color: hsl(0, 100%, 40%);">- ms_power_diff(lchan, MS_RAISE_MAX);</span><br><span style="color: hsl(120, 100%, 40%);">+ LOGPLCHAN(lchan, DLOOP, LOGL_NOTICE, "LOST SACCH frame, so we raise MS power output\n");</span><br><span style="color: hsl(120, 100%, 40%);">+ ms_power_diff(lchan, MS_RAISE_MAX_DB);</span><br><span> return;</span><br><span> }</span><br><span> </span><br><span>diff --git a/src/osmo-bts-trx/loops.h b/src/osmo-bts-trx/loops.h</span><br><span>index 0db01d7..7869903 100644</span><br><span>--- a/src/osmo-bts-trx/loops.h</span><br><span>+++ b/src/osmo-bts-trx/loops.h</span><br><span>@@ -8,8 +8,8 @@</span><br><span> */</span><br><span> </span><br><span> /* how much power levels do we raise/lower as maximum (1 level = 2 dB) */</span><br><span style="color: hsl(0, 100%, 40%);">-#define MS_RAISE_MAX 4</span><br><span style="color: hsl(0, 100%, 40%);">-#define MS_LOWER_MAX 2</span><br><span style="color: hsl(120, 100%, 40%);">+#define MS_RAISE_MAX_DB 4</span><br><span style="color: hsl(120, 100%, 40%);">+#define MS_LOWER_MAX_DB 8</span><br><span> </span><br><span> /*</span><br><span> * loops api</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/c/osmo-bts/+/15971">change 15971</a>. 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<div style="display:none"> Gerrit-Project: osmo-bts </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-Change-Id: I0160637c5ffa606ee3081ad30be8e6f2a42b725b </div>
<div style="display:none"> Gerrit-Change-Number: 15971 </div>
<div style="display:none"> Gerrit-PatchSet: 3 </div>
<div style="display:none"> Gerrit-Owner: pespin <pespin@sysmocom.de> </div>
<div style="display:none"> Gerrit-Reviewer: Jenkins Builder </div>
<div style="display:none"> Gerrit-Reviewer: laforge <laforge@osmocom.org> </div>
<div style="display:none"> Gerrit-MessageType: merged </div>