nr_pbchsim
发端：
gNB_config->ssb_table.ssb_period.value = 1; //10ms
mu: 0-> SCS15kHz, 1->SCS30kHz，默认30kHz
好像只装填了SSB的数据，共Lmax个可能的SSB，循环：
for (i=0; i<frame_parms->Lmax; i++) {
if((SSB_positions >> i) & 0x01) //有SSB就加入
调用PHY_ofdm_mod：
装填第1个符号：
PHY_ofdm_mod((int *)gNB->common_vars.txdataF[0][aa],
(int*)&txdata[aa][samp],
frame_parms->ofdm_symbol_size,
1,
frame_parms->nb_prefix_samples0,
CYCLIC_PREFIX);
装填后面13个符号：
PHY_ofdm_mod((int *)&gNB->common_vars.txdataF[0][aa][frame_parms->ofdm_symbol_size],
(int*)&txdata[aa][samp + frame_parms->nb_prefix_samples0 + frame_parms->ofdm_symbol_size],
frame_parms->ofdm_symbol_size,
13,
frame_parms->nb_prefix_samples,
CYCLIC_PREFIX);
输入跟gNB->common_vars有关
装填一次，接收就是不同snr的仿真
for (SNR = snr0; SNR < snr1 && !stop; SNR+=.2) {
for (trial = 0; trial < n_trials && !stop; trial++) {
- I: 初始同步
调用：
nr_initial_sync_t nr_initial_sync(UE_nr_rxtx_proc_t *proc,
PHY_VARS_NR_UE *ue,
int n_frames,
int sa,
nr_gscn_info_t gscnInfo[MAX_GSCN_BAND],
int numGscn)
逐个GSCN扫描：
for (int s = 0; s < numGscn; s++) {
nr_ue_ssb_scan_t *ssbInfo = &ssb_info[s];
但因为是仿真，仅有一个GSCN
每次扫描，需要初始化ssbInfo结构，其会被装填上需要搜索的数据：
ssbInfo->rxdata[ant] = malloc16(sizeof(c16_t) * (fp->samples_per_frame * 2 + fp->ofdm_symbol_size));
其中，fp->samples_per_frame为614400=2048*300，fp->ofdm_symbol_size为2048
memcpy(ssbInfo->rxdata[ant], ue->common_vars.rxdata[ant], sizeof(c16_t) * fp->samples_per_frame * 2);
ssbInfo->rxdata的前面数据来自ue->common_vars.rxdata，长度为sizeof(c16_t) * fp->samples_per_frame * 2
memset(ssbInfo->rxdata[ant] + fp->samples_per_frame * 2, 0, fp->ofdm_symbol_size * sizeof(c16_t));
ssbInfo->rxdata后面数据设置为0，长度为fp->ofdm_symbol_size * sizeof(c16_t)
但是应该总共618496
=>单个GSCN的ssb搜索是用函数指针的方式来调用的：
task_t t = {.func = nr_scan_ssb, .args = ssbInfo}
其中：
typedef struct {
void* args;
void (*func)(void* args);
} task_t;
指向的函数是：
void nr_scan_ssb(void *arg)
{
/* Initial synchronisation
*
* 1 radio frame = 10 ms
* <--------------------------------------------------------------------------->
* -----------------------------------------------------------------------------
* | Received UE data buffer |
* ----------------------------------------------------------------------------
* --------------------------
* <-------------->| pss | pbch | sss | pbch |
* --------------------------
* sync_pos SS/PBCH block
*/
=> 调用nr_search_ssb_common
打印出来信息：
SSB extends beyond buffer boundary (sync_pos 614180, ssb_offset 614036, buffer_size 614400)
其中：
const int ssb_offset = sync_pos - fp->nb_prefix_samples;
可看出sync_pos - ssb_offset = 144，差了个CP，sync_pos是没有CP的ssb起点，而ssb_offset是带了CP的ssb起点？
sync_pos是变化的，例如614180
614400-614180=220
为什么找出来的sync_pos都是很大的值？？？612672是我看到的最小值了。。。
ssb_offset + NR_N_SYMBOLS_SSB * (fp->ofdm_symbol_size + fp->nb_prefix_samples) >= params->rxdata_size
NR_N_SYMBOLS_SSB * (fp->ofdm_symbol_size + fp->nb_prefix_samples) >= params->rxdata_size - ssb_offset
感觉是判断rxdata剩下的sample数量是否能包含4个符号的ssb的总的sample数量（8768），包括4个CP
但基本上不够。。。为什么只是1个10毫秒的sample呢？奇怪
来源于：
=> sync_pos的计算是调用pss_synchro_nr
const int sync_pos = pss_synchro_nr((const c16_t **)params->rxdata,
fp,
pssTime,
params->search_frame_id,
params->fo_flag,
params->target_nid_cell,
&nid2,
&freq_offset_pss,
&pss_peak,
&pss_avg);
=> 调用pss_search_time_nr
长度：
if (is == 0)
length = frame_parms->samples_per_frame + (2 * frame_parms->ofdm_symbol_size); //618496
else
length = frame_parms->samples_per_frame; //614400
相关：逐4点平移点乘，Search pss in the received buffer each 4 samples which ensures a memory alignment on 128 bits (32 bits x 4 )
for (n = start; n < start + length; n += 4) { //
……
const c32_t result = dot_product(pssTime[pss_index],
&(rxdata[ar][n + is * frame_parms->samples_per_frame]),
frame_parms->ofdm_symbol_size,
shift);
const c64_t r64 = {.r = result.r, .i = result.i};
pss_corr_ue += squaredMod(r64); //相关值的能量
=> 调用dot_product
但是这个限制会导致“点乘”并没有真正执行：
#if defined(__x86_64__) || defined(__i386__)
if (__builtin_cpu_supports("avx2")) {
一个奇怪的问题，随意的写printf，居然会导致Segmentation fault (core dumped)的错误（程序崩掉），哎，c好脆弱的