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authorHarald Welte <laforge@gnumonks.org>2017-12-02 23:01:29 +0100
committerHarald Welte <laforge@gnumonks.org>2019-01-21 15:29:58 +0100
commit4d2c96089b1db1c8f21b1a1d300a8e8d8d74f410 (patch)
tree0beaf648d55b4ccd5ddb2313110bbd9493bf1f60
parent7a1dd94726447504b53bb66f40996800de836df3 (diff)
prbs-tool: Add error simulation capabilitieslaforge/prbs-tool
The tool can now simulate: * lost bursts on the TRX->BTS interface * zeroed/overwritten bursts on the TRX->BTS interface * errors in the TCH codec frames before passing them to the encoder Change-Id: I0b52c2af6d973669ac233bf9868400e497496460 TODO: Ability to introduce errors in certain classes of the bits only.
-rw-r--r--utils/prbs-tool.c91
1 files changed, 79 insertions, 12 deletions
diff --git a/utils/prbs-tool.c b/utils/prbs-tool.c
index f765531..26d4aa2 100644
--- a/utils/prbs-tool.c
+++ b/utils/prbs-tool.c
@@ -55,7 +55,7 @@ struct trx_ul_msg {
uint32_t fn;
uint8_t rssi;
uint16_t t_offs;
- sbit_t bits[148];
+ uint8_t bits[148]; /* 0..255, *NOT* sbit_t */
} __attribute__((packed));
struct trx_dl_msg {
@@ -134,6 +134,26 @@ struct pchan_data {
unsigned int burst_nr;
/* training sequence code */
unsigned int tsc;
+
+ /* loose 'count' bursts every 'nth_mframe' on TRX-BTS interface */
+ struct {
+ unsigned int count;
+ unsigned int nth_mframe;
+ } sim_lost_bursts;
+
+ /* zero 'count' bursts every 'nth_mframe' on TRX-BTS interface */
+ struct {
+ unsigned int count;
+ unsigned int nth_mframe;
+ } sim_zero_bursts;
+
+ /* flip every 'nth_bit' of the PRNG oudput before encoding */
+ struct {
+ unsigned int nth_bit;
+ unsigned int i;
+ } sim_flip_codec_bits;
+
+ unsigned int i;
};
struct ts_data {
@@ -164,6 +184,18 @@ static void trx_data_init(struct trx_data *trx)
}
}
+/* apply any intentional errors to the output of the PRBS sequence */
+static void apply_errors_prbs(struct pchan_data *pchan)
+{
+ for (int i = 0; i < sizeof(pchan->prbs_u)-4; i++) {
+ pchan->sim_flip_codec_bits.i++;
+ if (pchan->sim_flip_codec_bits.i == pchan->sim_flip_codec_bits.nth_bit) {
+ pchan->sim_flip_codec_bits.i = 0;
+ pchan->prbs_u[4+i] ^= 0x01;
+ }
+ }
+}
+
/*! obtain the next to-be-transmitted burst for the given pchan
* \param pchan physical channel on which we operate
* \param[in] fn frame number
@@ -188,6 +220,9 @@ static int pchan_get_next_burst(struct pchan_data *pchan, uint32_t fn, ubit_t *b
osmo_pbit2ubit(pchan->prbs_u, prefix, 4);
rc = osmo_prbs_get_ubits(pchan->prbs_u+4, sizeof(pchan->prbs_u)-4, &pchan->st);
OSMO_ASSERT(rc == sizeof(pchan->prbs_u)-4);
+
+ apply_errors_prbs(pchan);
+
/* pack to PBIT format */
rc = osmo_ubit2pbit(pchan->tch_data, pchan->prbs_u, sizeof(pchan->prbs_u));
//memset(pchan->tch_data, 0xff, sizeof(pchan->tch_data));
@@ -201,16 +236,17 @@ static int pchan_get_next_burst(struct pchan_data *pchan, uint32_t fn, ubit_t *b
/* encode block (codec frame) into four bursts */
rc = gsm0503_tch_fr_encode(pchan->bursts, pchan->tch_data, GSM_FR_BYTES, 1);
OSMO_ASSERT(rc == 0);
-
+#if 0
for (int i = 0; i < sizeof(pchan->bursts); i += GSM_BURST_BITS)
printf("\t%s\n", osmo_ubit_dump(pchan->bursts + i, GSM_BURST_BITS));
-// dec(pchan->bursts);
+ dec(pchan->bursts);
+#endif
}
/* for all bursts: format 148 symbols from 116 input bits */
ubit_t *burst = pchan->bursts + pchan->burst_nr * GSM_BURST_BITS;
- printf("TX(%u): %s\n", pchan->burst_nr, osmo_ubit_dump(burst, GSM_BURST_BITS));
+// printf("TX(%u): %s\n", pchan->burst_nr, osmo_ubit_dump(burst, GSM_BURST_BITS));
memset(burst_out, 0, 3); /* guard bits */
memcpy(burst_out+3, burst, 58); /* firrst half */
memcpy(burst_out+61, _sched_tsc[pchan->tsc], 26); /* midamble */
@@ -219,10 +255,6 @@ static int pchan_get_next_burst(struct pchan_data *pchan, uint32_t fn, ubit_t *b
/* increment burst number for next call */
pchan->burst_nr += 1;
-#if 0
- if (pchan->burst_nr == 4)
- pchan->burst_nr = 0;
-#endif
return GSM_BURST_LEN;
}
@@ -252,6 +284,7 @@ static int read_and_process(int fd)
struct trx_ul_msg *ul_msg = (struct trx_ul_msg *) tx_ul_buf;
/* other variables */
struct pchan_data *pchan;
+ uint32_t fn;
uint8_t rc;
/* do a blocking read on the socket and receive DL from BTS */
@@ -259,7 +292,7 @@ static int read_and_process(int fd)
if (rc < sizeof(*dl_msg))
return rc;
- dl_msg->fn = ntohl(dl_msg->fn);
+ fn = ntohl(dl_msg->fn);
if (dl_msg->ts >= ARRAY_SIZE(g_trx_data.ts))
return -ENODEV;
@@ -267,18 +300,48 @@ static int read_and_process(int fd)
if (dl_msg->ts != 2)
return 0;
- printf("FN=%s TS=%u\n", gsm_fn_as_gsmtime_str(dl_msg->fn), dl_msg->ts);
+ printf("FN=%s TS=%u\n", gsm_fn_as_gsmtime_str(fn), dl_msg->ts);
/* FIXME: second pchan for TCH/H */
pchan = &g_trx_data.ts[dl_msg->ts].pchan[0];
- rc = pchan_process_ts_fn(pchan, dl_msg->fn, ul_msg->bits);
+ rc = pchan_process_ts_fn(pchan, fn, ul_msg->bits);
OSMO_ASSERT(rc == sizeof(ul_msg->bits));
/* copy over timeslot and frame number */
- ul_msg->fn = htonl(dl_msg->fn);
+ ul_msg->fn = htonl(fn);
ul_msg->ts = dl_msg->ts;
+ /* simulate lost frames on TRX <-> BTS interface */
+ if (pchan->sim_lost_bursts.count) {
+ /* count number of 26-multiframes */
+ static int count = 0;
+ if (fn % 26 == 0)
+ count++;
+
+ /* every 10th multiframe, drop two entire block of 8 bursts */
+ if (count % pchan->sim_lost_bursts.nth_mframe == 0 &&
+ (fn % 26) <= pchan->sim_lost_bursts.count) {
+ printf("===> SKIPPING BURST\n");
+ return 0;
+ }
+ }
+
+ /* simulate zero-ed frames on TRX <-> BTS interface */
+ if (pchan->sim_zero_bursts.count) {
+ /* count number of 26-multiframes */
+ static int count = 0;
+ if (fn % 26 == 0)
+ count++;
+
+ /* every 10th multiframe, drop two entire block of 8 bursts */
+ if (count % pchan->sim_zero_bursts.nth_mframe == 0 &&
+ (fn % 26) <= pchan->sim_zero_bursts.count) {
+ memset(ul_msg->bits, 0, sizeof(ul_msg->bits));
+ printf("===> ZEROING BURST\n");
+ }
+ }
+
/* write uplink message towards BTS */
rc = write(fd, tx_ul_buf, sizeof(*ul_msg));
if (rc < sizeof(*ul_msg))
@@ -304,6 +367,10 @@ int main(int argc, char **argv)
trx_data_init(&g_trx_data);
+ //g_trx_data.ts[2].pchan[0].sim_zero_bursts.count = 8;
+ //g_trx_data.ts[2].pchan[0].sim_zero_bursts.nth_mframe = 10;
+ g_trx_data.ts[2].pchan[0].sim_flip_codec_bits.nth_bit = 260*4;
+
fd = open_trx_data_sock(0, "127.0.0.1");
if (fd < 0)
exit(1);