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osmo-bts/include/osmo-bts/ta_control.h

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ta_control: move timing advance code from osmo-bts-trx to common The timing advance controller that is implemented in loops.c of osmo-bts-trx only works for osmo-bts-trx and not for any of the phy based bts. Lets move the timing advance controller into the common part and make it available for every bts. Also lets add a unit-test. Change-Id: If7ddf74db3abc9b9872abe620a0aeebe3327e70a Related: SYS#4567
2020-01-15 10:01:24 +00:00
#pragma once
#include <osmo-bts/gsm_data.h>
TA loop: Take into account UL SACCH 'Actual Timing advance' field First step improving and reworking TA loop: Move trigger of the loop to similar place done by BS/MS Power Control Loop, that is, upon receivial of UL SACCH block, which contains information about the TA used to transmit the block encode in L1SACCH Header. Hence, from computed received TOA and TA used when transmitting from the MS, we can infer the desired TA to be used by the MS, which will send back to it later during DL SACCH block. The values taken are actually the ones calculated for the previous SACCH block and stored in lchan->meas.ms_toa256. That's because L1SACCH contains the TA used for the previous reporting period, similarly to what's specified for MS Power Control loop (TS 45.008 sec 4.2): """ The MS shall confirm the power control level that it is currently employing in the SACCH L1 header on each uplink channel. The indicated value shall be the power control level actually used by the mobile for the last burst of the previous SACCH period. """ (The reader may observe that currently this is not properly done for MS Power Control loop when calling lchan_ms_pwr_ctrl(): this is a bug.) This new method also permits changing TA quicker, since we have more confidence that the TA we request is aligned with the one used to transmit, and we don't simply increment/decrement based on the value we request to transmit. Related: SYS#5371 Change-Id: I2d0f128c8dcac93ee382283a1c91fca76623b8fc
2021-09-06 17:00:34 +00:00
void lchan_ms_ta_ctrl(struct gsm_lchan *lchan, uint8_t ms_tx_ta, int16_t toa256);