Change in osmo-bts[master]: osmo-bts-trx: remove outdated TRXD protocol documentation

fixeria gerrit-no-reply at lists.osmocom.org
Tue Apr 20 23:05:17 UTC 2021


fixeria has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-bts/+/23823 )


Change subject: osmo-bts-trx: remove outdated TRXD protocol documentation
......................................................................

osmo-bts-trx: remove outdated TRXD protocol documentation

We do have TRXC/TRXD documentation in osmo-gsm-manuals repository.
This big comment is out of sync with what we have in the manuals,
so let's better remove it to avoid maintaining docs in several places.

Change-Id: Ibfcefcbb5f30fe9b6c691578a93e6fedd5644b30
Related: SYS#4895, OS#4941, OS#4006
---
M src/osmo-bts-trx/trx_if.c
1 file changed, 1 insertion(+), 118 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/23/23823/1

diff --git a/src/osmo-bts-trx/trx_if.c b/src/osmo-bts-trx/trx_if.c
index bec6a5a..495de92 100644
--- a/src/osmo-bts-trx/trx_if.c
+++ b/src/osmo-bts-trx/trx_if.c
@@ -916,124 +916,7 @@
 	return buf;
 }
 
-/* Parse TRXD message from transceiver, compose an UL burst indication.
- *
- * This message contains a demodulated Uplink burst with fixed-size
- * header preceding the burst bits. The header consists of the common
- * and message specific part.
- *
- *   +---------------+-----------------+------------+
- *   | common header | specific header | burst bits |
- *   +---------------+-----------------+------------+
- *
- * Common header is the same as for Downlink message:
- *
- *   +-----------------+----------------+-------------------+
- *   | VER (1/2 octet) | TN (1/2 octet) | FN (4 octets, BE) |
- *   +-----------------+----------------+-------------------+
- *
- * and among with TDMA parameters, contains the version indicator:
- *
- *   +-----------------+------------------------+
- *   | 7 6 5 4 3 2 1 0 | bit numbers            |
- *   +-----------------+------------------------+
- *   | X X X X . . . . | PDU version (0..15)    |
- *   +-----------------+------------------------+
- *   | . . . . . X X X | TDMA TN (0..7)         |
- *   +-----------------+------------------------+
- *   | . . . . X . . . | RESERVED (0)           |
- *   +-----------------+------------------------+
- *
- * which is encoded in 4 MSB bits of the first octet, which used to be
- * zero-initialized due to the value range of TDMA TN. Therefore, the
- * old header format has implicit version 0x00.
- *
- * The message specific header has the following structure:
- *
- * == Version 0x00
- *
- *   +------+-----+--------------------+
- *   | RSSI | ToA | soft-bits (254..0) |
- *   +------+-----+--------------------+
- *
- * == Version 0x01
- *
- *   +------+-----+-----+-----+--------------------+
- *   | RSSI | ToA | MTS | C/I | soft-bits (254..0) |
- *   +------+-----+-----+-----+--------------------+
- *
- * where:
- *
- *   - RSSI (1 octet) - Received Signal Strength Indication
- *     encoded without the negative sign.
- *   - ToA (2 octets) - Timing of Arrival in units of 1/256
- *     of symbol (big endian).
- *   - MTS (1 octet)  - Modulation and Training Sequence info.
- *   - C/I (2 octets) - Carrier-to-Interference ratio (big endian).
- *
- * == Coding of MTS: Modulation and Training Sequence info
- *
- * 3GPP TS 45.002 version 15.1.0 defines several modulation types,
- * and a few sets of training sequences for each type. The most
- * common are GMSK and 8-PSK (which is used in EDGE).
- *
- *   +-----------------+---------------------------------------+
- *   | 7 6 5 4 3 2 1 0 | bit numbers (value range)             |
- *   +-----------------+---------------------------------------+
- *   | . . . . . X X X | Training Sequence Code (0..7)         |
- *   +-----------------+---------------------------------------+
- *   | . X X X X . . . | Modulation, TS set number (see below) |
- *   +-----------------+---------------------------------------+
- *   | X . . . . . . . | IDLE / nope frame indication (0 or 1) |
- *   +-----------------+---------------------------------------+
- *
- * The bit number 7 (MSB) is set to high when either nothing has been
- * detected, or during IDLE frames, so we can deliver noise levels,
- * and avoid clock gaps on the L1 side. Other bits are ignored,
- * and should be set to low (0) in this case. L16 shall be set to 0x00.
- *
- * == Coding of modulation and TS set number
- *
- * GMSK has 4 sets of training sequences (see tables 5.2.3a-d),
- * while 8-PSK (see tables 5.2.3f-g) and the others have 2 sets.
- * Access and Synchronization bursts also have several synch.
- * sequences.
- *
- *   +-----------------+---------------------------------------+
- *   | 7 6 5 4 3 2 1 0 | bit numbers (value range)             |
- *   +-----------------+---------------------------------------+
- *   | . 0 0 X X . . . | GMSK, 4 TS sets (0..3)                |
- *   +-----------------+---------------------------------------+
- *   | . 0 1 0 X . . . | 8-PSK, 2 TS sets (0..1)               |
- *   +-----------------+---------------------------------------+
- *   | . 0 1 1 X . . . | AQPSK, 2 TS sets (0..1)               |
- *   +-----------------+---------------------------------------+
- *   | . 1 0 0 X . . . | 16QAM, 2 TS sets (0..1)               |
- *   +-----------------+---------------------------------------+
- *   | . 1 0 1 X . . . | 32QAM, 2 TS sets (0..1)               |
- *   +-----------------+---------------------------------------+
- *   | . 1 1 1 X . . . | RESERVED (0)                          |
- *   +-----------------+---------------------------------------+
- *
- * NOTE: we only support GMSK and 8-PSK.
- *
- * == C/I: Carrier-to-Interference ratio
- *
- * The C/I value can be computed from the training sequence of each
- * burst, where we can compare the "ideal" training sequence with
- * the actual training sequence and then express that in centiBels.
- *
- * == Coding of the burst bits
- *
- * Unlike to be transmitted bursts, the received bursts are designated
- * using the soft-bits notation, so the receiver can indicate its
- * assurance from 0 to -127 that a given bit is 1, and from 0 to +127
- * that a given bit is 0.
- *
- * Each soft-bit (-127..127) of the burst is encoded as an unsigned
- * value in range (254..0) respectively using the constant shift.
- *
- */
+/* Parse TRXD message from transceiver, compose an UL burst indication. */
 static int trx_data_read_cb(struct osmo_fd *ofd, unsigned int what)
 {
 	struct trx_l1h *l1h = ofd->data;

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Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Change-Id: Ibfcefcbb5f30fe9b6c691578a93e6fedd5644b30
Gerrit-Change-Number: 23823
Gerrit-PatchSet: 1
Gerrit-Owner: fixeria <vyanitskiy at sysmocom.de>
Gerrit-MessageType: newchange
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