OsmocomBB MS-side GSM Protocol stack (L1, L2, L3) including firmware https://osmocom.org/projects/baseband
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osmocom-bb/src/host/trxcon/src/sched_lchan_tchh.c

494 lines
13 KiB

/*
* OsmocomBB <-> SDR connection bridge
* TDMA scheduler: handlers for DL / UL bursts on logical channels
*
* (C) 2018-2022 by Vadim Yanitskiy <axilirator@gmail.com>
* (C) 2018 by Harald Welte <laforge@gnumonks.org>
* Contributions by sysmocom - s.f.m.c. GmbH
*
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <errno.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#include <osmocom/core/logging.h>
#include <osmocom/core/utils.h>
#include <osmocom/core/bits.h>
#include <osmocom/gsm/protocol/gsm_04_08.h>
#include <osmocom/gsm/gsm_utils.h>
#include <osmocom/coding/gsm0503_coding.h>
#include <osmocom/codec/codec.h>
#include <osmocom/bb/l1sched/l1sched.h>
#include <osmocom/bb/l1sched/logging.h>
static const uint8_t tch_h0_traffic_block_map[3][4] = {
/* B0(0,2,4,6), B1(4,6,8,10), B2(8,10,0,2) */
{ 0, 2, 4, 6 },
{ 4, 6, 8, 10 },
{ 8, 10, 0, 2 },
};
static const uint8_t tch_h1_traffic_block_map[3][4] = {
/* B0(1,3,5,7), B1(5,7,9,11), B2(9,11,1,3) */
{ 1, 3, 5, 7 },
{ 5, 7, 9, 11 },
{ 9, 11, 1, 3 },
};
static const uint8_t tch_h0_dl_facch_block_map[3][6] = {
/* B0(4,6,8,10,13,15), B1(13,15,17,19,21,23), B2(21,23,0,2,4,6) */
{ 4, 6, 8, 10, 13, 15 },
{ 13, 15, 17, 19, 21, 23 },
{ 21, 23, 0, 2, 4, 6 },
};
static const uint8_t tch_h0_ul_facch_block_map[3][6] = {
/* B0(0,2,4,6,8,10), B1(8,10,13,15,17,19), B2(17,19,21,23,0,2) */
{ 0, 2, 4, 6, 8, 10 },
{ 8, 10, 13, 15, 17, 19 },
{ 17, 19, 21, 23, 0, 2 },
};
static const uint8_t tch_h1_dl_facch_block_map[3][6] = {
/* B0(5,7,9,11,14,16), B1(14,16,18,20,22,24), B2(22,24,1,3,5,7) */
{ 5, 7, 9, 11, 14, 16 },
{ 14, 16, 18, 20, 22, 24 },
{ 22, 24, 1, 3, 5, 7 },
};
const uint8_t tch_h1_ul_facch_block_map[3][6] = {
/* B0(1,3,5,7,9,11), B1(9,11,14,16,18,20), B2(18,20,22,24,1,3) */
{ 1, 3, 5, 7, 9, 11 },
{ 9, 11, 14, 16, 18, 20 },
{ 18, 20, 22, 24, 1, 3 },
};
/**
* Can a TCH/H block transmission be initiated / finished
* on a given frame number and a given channel type?
*
* See GSM 05.02, clause 7, table 1
*
* @param chan channel type (L1SCHED_TCHH_0 or L1SCHED_TCHH_1)
* @param fn the current frame number
* @param ul Uplink or Downlink?
* @param facch FACCH/H or traffic?
* @param start init or end of transmission?
* @return true (yes) or false (no)
*/
bool l1sched_tchh_block_map_fn(enum l1sched_lchan_type chan,
uint32_t fn, bool ul, bool facch, bool start)
{
uint8_t fn_mf;
int i = 0;
/* Just to be sure */
OSMO_ASSERT(chan == L1SCHED_TCHH_0 || chan == L1SCHED_TCHH_1);
/* Calculate a modulo */
fn_mf = facch ? (fn % 26) : (fn % 13);
#define MAP_GET_POS(map) \
(start ? 0 : ARRAY_SIZE(map[i]) - 1)
#define BLOCK_MAP_FN(map) \
do { \
if (map[i][MAP_GET_POS(map)] == fn_mf) \
return true; \
} while (++i < ARRAY_SIZE(map))
/* Choose a proper block map */
if (facch) {
if (ul) {
if (chan == L1SCHED_TCHH_0)
BLOCK_MAP_FN(tch_h0_ul_facch_block_map);
else
BLOCK_MAP_FN(tch_h1_ul_facch_block_map);
} else {
if (chan == L1SCHED_TCHH_0)
BLOCK_MAP_FN(tch_h0_dl_facch_block_map);
else
BLOCK_MAP_FN(tch_h1_dl_facch_block_map);
}
} else {
if (chan == L1SCHED_TCHH_0)
BLOCK_MAP_FN(tch_h0_traffic_block_map);
else
BLOCK_MAP_FN(tch_h1_traffic_block_map);
}
return false;
}
/**
* Calculates a frame number of the first burst
* using given frame number of the last burst.
*
* See GSM 05.02, clause 7, table 1
*
* @param chan channel type (L1SCHED_TCHH_0 or L1SCHED_TCHH_1)
* @param last_fn frame number of the last burst
* @param facch FACCH/H or traffic?
* @return either frame number of the first burst,
* or fn=last_fn if calculation failed
*/
static uint32_t tchh_block_dl_first_fn(const struct l1sched_lchan_state *lchan,
uint32_t last_fn, bool facch)
{
enum l1sched_lchan_type chan = lchan->type;
uint8_t fn_mf, fn_diff;
int i = 0;
/* Just to be sure */
OSMO_ASSERT(chan == L1SCHED_TCHH_0 || chan == L1SCHED_TCHH_1);
/* Calculate a modulo */
fn_mf = facch ? (last_fn % 26) : (last_fn % 13);
#define BLOCK_FIRST_FN(map) \
do { \
if (map[i][ARRAY_SIZE(map[i]) - 1] == fn_mf) { \
fn_diff = GSM_TDMA_FN_DIFF(fn_mf, map[i][0]); \
return GSM_TDMA_FN_SUB(last_fn, fn_diff); \
} \
} while (++i < ARRAY_SIZE(map))
/* Choose a proper block map */
if (facch) {
if (chan == L1SCHED_TCHH_0)
BLOCK_FIRST_FN(tch_h0_dl_facch_block_map);
else
BLOCK_FIRST_FN(tch_h1_dl_facch_block_map);
} else {
if (chan == L1SCHED_TCHH_0)
BLOCK_FIRST_FN(tch_h0_traffic_block_map);
else
BLOCK_FIRST_FN(tch_h1_traffic_block_map);
}
LOGP_LCHAND(lchan, LOGL_ERROR,
"Failed to calculate TDMA frame number of the first burst of %s block, "
"using the current fn=%u\n", facch ? "FACCH/H" : "TCH/H", last_fn);
/* Couldn't calculate the first fn, return the last */
return last_fn;
}
int rx_tchh_fn(struct l1sched_lchan_state *lchan,
uint32_t fn, uint8_t bid, const sbit_t *bits,
const struct l1sched_meas_set *meas)
{
int n_errors = -1, n_bits_total = 0, rc;
sbit_t *buffer, *offset;
uint8_t l2[128], *mask;
size_t l2_len;
/* Set up pointers */
mask = &lchan->rx_burst_mask;
buffer = lchan->rx_bursts;
LOGP_LCHAND(lchan, LOGL_DEBUG, "Traffic received: fn=%u bid=%u\n", fn, bid);
if (*mask == 0x00) {
/* Align to the first burst */
if (bid > 0)
return 0;
/* Align reception of the first FACCH/H frame */
if (lchan->tch_mode == GSM48_CMODE_SIGN) {
if (!l1sched_tchh_facch_start(lchan->type, fn, 0))
return 0;
} else { /* or TCH/H traffic frame */
if (!l1sched_tchh_traffic_start(lchan->type, fn, 0))
return 0;
}
}
/* Update mask */
*mask |= (1 << bid);
/* Store the measurements */
l1sched_lchan_meas_push(lchan, meas);
/* Copy burst to the end of buffer of 6 bursts */
offset = buffer + bid * 116 + 464;
memcpy(offset, bits + 3, 58);
memcpy(offset + 58, bits + 87, 58);
/* Wait until the second burst */
if (bid != 1)
return 0;
/* Wait for complete set of bursts */
if (lchan->tch_mode == GSM48_CMODE_SIGN) {
/* FACCH/H is interleaved over 6 bursts */
if ((*mask & 0x3f) != 0x3f)
goto bfi_shift;
} else {
/* Traffic is interleaved over 4 bursts */
if ((*mask & 0x0f) != 0x0f)
goto bfi_shift;
}
/* Skip decoding attempt in case of FACCH/H */
if (lchan->dl_ongoing_facch) {
lchan->dl_ongoing_facch = false;
goto bfi_shift; /* 2/2 BFI */
}
switch (lchan->tch_mode) {
case GSM48_CMODE_SIGN:
case GSM48_CMODE_SPEECH_V1: /* HR */
rc = gsm0503_tch_hr_decode(l2, buffer,
!l1sched_tchh_facch_end(lchan->type, fn, 0),
&n_errors, &n_bits_total);
break;
case GSM48_CMODE_SPEECH_AMR: /* AMR */
/**
* TODO: AMR requires a dedicated loop,
* which will be implemented later...
*/
LOGP_LCHAND(lchan, LOGL_ERROR, "AMR isn't supported yet\n");
return -ENOTSUP;
default:
LOGP_LCHAND(lchan, LOGL_ERROR, "Invalid TCH mode: %u\n", lchan->tch_mode);
return -EINVAL;
}
/* Shift buffer by 4 bursts for interleaving */
memcpy(buffer, buffer + 232, 232);
memcpy(buffer + 232, buffer + 464, 232);
/* Shift burst mask */
*mask = *mask << 2;
/* Check decoding result */
if (rc < 4) {
/* Calculate AVG of the measurements (assuming 4 bursts) */
l1sched_lchan_meas_avg(lchan, 4);
LOGP_LCHAND(lchan, LOGL_ERROR,
"Received bad frame (rc=%d, ber=%d/%d) at fn=%u\n",
rc, n_errors, n_bits_total, lchan->meas_avg.fn);
/* Send BFI */
goto bfi;
} else if (rc == GSM_MACBLOCK_LEN) {
/* Skip decoding of the next 2 stolen bursts */
lchan->dl_ongoing_facch = true;
/* Calculate AVG of the measurements (FACCH/H takes 6 bursts) */
l1sched_lchan_meas_avg(lchan, 6);
/* FACCH/H received, forward to the higher layers */
l1sched_handle_data_ind(lchan, l2, GSM_MACBLOCK_LEN,
n_errors, n_bits_total,
L1SCHED_DT_SIGNALING);
/* Send BFI substituting 1/2 stolen TCH frames */
n_errors = -1; /* ensure fake measurements */
goto bfi;
} else {
/* A good TCH frame received */
l2_len = rc;
/* Calculate AVG of the measurements (traffic takes 4 bursts) */
l1sched_lchan_meas_avg(lchan, 4);
}
/* Send a traffic frame to the higher layers */
return l1sched_handle_data_ind(lchan, l2, l2_len,
n_errors, n_bits_total,
L1SCHED_DT_TRAFFIC);
bfi_shift:
/* Shift buffer */
memcpy(buffer, buffer + 232, 232);
memcpy(buffer + 232, buffer + 464, 232);
/* Shift burst mask */
*mask = *mask << 2;
bfi:
/* Didn't try to decode, fake measurements */
if (n_errors < 0) {
lchan->meas_avg = (struct l1sched_meas_set) {
.fn = tchh_block_dl_first_fn(lchan, fn, false),
.toa256 = 0,
.rssi = -110,
};
/* No bursts => no errors */
n_errors = 0;
}
/* BFI is not applicable in signalling mode */
if (lchan->tch_mode == GSM48_CMODE_SIGN) {
return l1sched_handle_data_ind(lchan, NULL, 0,
n_errors, n_bits_total,
L1SCHED_DT_SIGNALING);
}
/* Bad frame indication */
l2_len = l1sched_bad_frame_ind(l2, lchan);
/* Send a BFI frame to the higher layers */
return l1sched_handle_data_ind(lchan, l2, l2_len,
n_errors, n_bits_total,
L1SCHED_DT_TRAFFIC);
}
int tx_tchh_fn(struct l1sched_lchan_state *lchan,
struct l1sched_burst_req *br)
{
ubit_t *buffer, *offset;
const uint8_t *tsc;
uint8_t *mask;
size_t l2_len;
int rc;
/* Set up pointers */
mask = &lchan->tx_burst_mask;
buffer = lchan->tx_bursts;
if (br->bid > 0) {
/* Align to the first burst */
if (*mask == 0x00)
return 0;
goto send_burst;
}
if (*mask == 0x00) {
/* Align transmission of the first FACCH/H frame */
if (lchan->tch_mode == GSM48_CMODE_SIGN)
if (!l1sched_tchh_facch_start(lchan->type, br->fn, 1))
return 0;
}
/* Shift buffer by 2 bursts back for interleaving */
memcpy(buffer, buffer + 232, 232);
/* Also shift TX burst mask */
*mask = *mask << 2;
/* If FACCH/H blocks are still pending */
if (lchan->ul_facch_blocks > 2) {
memcpy(buffer + 232, buffer + 464, 232);
goto send_burst;
}
/* Check the current TCH mode */
switch (lchan->tch_mode) {
case GSM48_CMODE_SIGN:
case GSM48_CMODE_SPEECH_V1: /* HR */
l2_len = GSM_HR_BYTES + 1;
break;
case GSM48_CMODE_SPEECH_AMR: /* AMR */
/**
* TODO: AMR requires a dedicated loop,
* which will be implemented later...
*/
LOGP_LCHAND(lchan, LOGL_ERROR,
"AMR isn't supported yet, dropping frame...\n");
/* Forget this primitive */
l1sched_prim_drop(lchan);
return -ENOTSUP;
default:
LOGP_LCHAND(lchan, LOGL_ERROR,
"Invalid TCH mode: %u, dropping frame...\n",
lchan->tch_mode);
/* Forget this primitive */
l1sched_prim_drop(lchan);
return -EINVAL;
}
/* Determine payload length */
if (L1SCHED_PRIM_IS_FACCH(lchan->prim)) {
l2_len = GSM_MACBLOCK_LEN; /* FACCH */
} else if (lchan->prim->payload_len != l2_len) {
LOGP_LCHAND(lchan, LOGL_ERROR, "Primitive has odd length %zu "
"(expected %zu for TCH or %u for FACCH), so dropping...\n",
lchan->prim->payload_len, l2_len, GSM_MACBLOCK_LEN);
/* Forget this primitive */
l1sched_prim_drop(lchan);
return -EINVAL;
}
/* Encode the payload */
rc = gsm0503_tch_hr_encode(buffer, lchan->prim->payload, l2_len);
if (rc) {
LOGP_LCHAND(lchan, LOGL_ERROR, "Failed to encode L2 payload (len=%zu): %s\n",
lchan->prim->payload_len, osmo_hexdump(lchan->prim->payload,
lchan->prim->payload_len));
/* Forget this primitive */
l1sched_prim_drop(lchan);
return -EINVAL;
}
/* A FACCH/H frame occupies 6 bursts */
if (L1SCHED_PRIM_IS_FACCH(lchan->prim))
lchan->ul_facch_blocks = 6;
send_burst:
/* Determine which burst should be sent */
offset = buffer + br->bid * 116;
/* Update mask */
*mask |= (1 << br->bid);
/* Choose proper TSC */
tsc = l1sched_nb_training_bits[lchan->tsc];
/* Compose a new burst */
memset(br->burst, 0, 3); /* TB */
memcpy(br->burst + 3, offset, 58); /* Payload 1/2 */
memcpy(br->burst + 61, tsc, 26); /* TSC */
memcpy(br->burst + 87, offset + 58, 58); /* Payload 2/2 */
memset(br->burst + 145, 0, 3); /* TB */
br->burst_len = GSM_BURST_LEN;
LOGP_LCHAND(lchan, LOGL_DEBUG, "Scheduled fn=%u burst=%u\n", br->fn, br->bid);
/* In case of a FACCH/H frame, one block less */
if (lchan->ul_facch_blocks)
lchan->ul_facch_blocks--;
if ((*mask & 0x0f) == 0x0f) {
/**
* If no more FACCH/H blocks pending,
* confirm data / traffic sending
*/
if (!lchan->ul_facch_blocks) {
enum l1sched_data_type dt = L1SCHED_PRIM_IS_TCH(lchan->prim) ?
L1SCHED_DT_TRAFFIC : L1SCHED_DT_SIGNALING;
l1sched_handle_data_cnf(lchan, br->fn, dt);
}
/* Forget processed primitive */
l1sched_prim_drop(lchan);
}
return 0;
}