long: copy also long preamble for channel estimation
This commit is contained in:
Bastian Bloessl
+56
-53
@@ -27,29 +27,29 @@ using namespace gr::ieee802_11;
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using namespace std;
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bool compare_abs(const std::pair<gr_complex, int>& first, const std::pair<gr_complex, int>& second) {
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return abs(get<0>(first)) > abs(get<0>(second));
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}
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class ofdm_sync_long_impl : public ofdm_sync_long {
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public:
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ofdm_sync_long_impl(unsigned int sync_length, bool log, bool debug) : block("ofdm_sync_long",
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gr::io_signature::make2(2, 2, sizeof(gr_complex), sizeof(gr_complex)),
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gr::io_signature::make(1, 1, sizeof(gr_complex))),
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d_fir(gr::filter::kernel::fir_filter_ccc(1, LONG)),
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d_log(log),
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d_debug(debug),
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d_offset(0),
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d_freq_est(0),
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d_state(SYNC),
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SYNC_LENGTH(sync_length) {
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set_tag_propagation_policy(block::TPP_DONT);
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d_fir = new gr::filter::kernel::fir_filter_ccc(1, LONG);
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d_correlation = gr::fft::malloc_complex(8192);
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d_freq_est_buf = static_cast<gr_complex*>(std::malloc(sync_length * sizeof(gr_complex)));
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}
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~ofdm_sync_long_impl(){
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delete d_fir;
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gr::fft::free(d_correlation);
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free(d_freq_est_buf);
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}
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int general_work (int noutput, gr_vector_int& ninput_items,
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@@ -64,19 +64,21 @@ int general_work (int noutput, gr_vector_int& ninput_items,
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ninput_items[1] << " noutput " << noutput <<
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" state " << d_state << std::endl;
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int ninput = std::min(ninput_items[0], ninput_items[1]);
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int ninput = std::min(std::min(ninput_items[0], ninput_items[1]), 8192);
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const unsigned int nread = nitems_read(0);
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get_tags_in_range(d_tags, 0, nread, nread + ninput);
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if (d_tags.size()) {
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std::sort(d_tags.begin(), d_tags.end(), gr::tag_t::offset_compare);
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const gr::tag_t &tag = d_tags.front();
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const uint64_t offset = tag.offset;
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const uint64_t offset = d_tags.front().offset;
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if(offset > nread) {
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ninput = offset - nread;
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} else {
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if(d_offset && (d_state == SYNC)) {
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throw std::runtime_error("wtf");
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}
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if(d_state == COPY) {
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d_state = RESET;
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}
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@@ -90,26 +92,20 @@ int general_work (int noutput, gr_vector_int& ninput_items,
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switch(d_state) {
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case SYNC:
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d_fir->filterN(d_correlation, in, std::min(SYNC_LENGTH, std::max(ninput - 63, 0)));
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d_fir.filterN(d_correlation, in, std::min(SYNC_LENGTH, std::max(ninput - 63, 0)));
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while(i + 63 < ninput) {
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d_freq_est += in[i] * conj(in[i + 16]);
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d_freq_est_buf[d_offset] = d_freq_est;
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d_cor.push_back(pair<double, int>(abs(d_correlation[i]), d_offset));
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d_cor.push_back(pair<gr_complex, int>(d_correlation[i], d_offset));
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i++;
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d_offset++;
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if(d_offset == SYNC_LENGTH) {
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search_frame_start();
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d_freq_est = d_freq_est_buf[std::max<int>(0, d_frame_start - 160 - 17)];
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d_offset = 0;
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d_state = COPY;
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mylog(boost::format("frame at %1% - freq_est (20M): %2%") % d_frame_start
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% ((arg(d_freq_est) / 16) * 20e6 / (2 * M_PI)));
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break;
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}
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}
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@@ -117,59 +113,53 @@ int general_work (int noutput, gr_vector_int& ninput_items,
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break;
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case COPY:
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while(i < ninput) {
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while(i < ninput && o < noutput) {
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int rel = d_offset - d_frame_start;
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if( (rel >= 0) && (rel % 80 > 15)) {
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if(o >= noutput) {
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break;
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}
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if(!rel) {
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add_item_tag(0, nitems_written(0),
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pmt::string_to_symbol("ofdm_start"),
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pmt::PMT_T,
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pmt::string_to_symbol(name()));
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}
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if(rel == 16) {
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assert(o == 0);
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add_item_tag(0, nitems_written(0) + o,
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pmt::string_to_symbol("ofdm_start"),
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pmt::PMT_T,
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pmt::string_to_symbol(name()));
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}
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out[o] = in_delayed[i] * exp(gr_complex(0, d_offset * arg(d_freq_est) / 16));
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if(rel >= 0 && (rel < 128 || ((rel - 128) % 80) > 15)) {
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out[o] = in_delayed[i] * exp(gr_complex(0, d_offset * d_freq_offset));
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o++;
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}
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i++;
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d_offset++;
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if(d_offset == 1) {
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dout << "produced " << d_count << " " << d_count / 64.0 << std::endl;
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d_count = 0;
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}
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}
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break;
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case RESET:
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case RESET: {
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int h = 0;
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while(o < noutput) {
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int rel = (d_offset - d_frame_start) % 80;
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if(!rel) {
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if(((d_count + h) % 64) == 0) {
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d_offset = 0;
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d_freq_est = gr_complex(0, 0);
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d_state = SYNC;
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break;
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} else if(rel > 15) {
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} else {
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out[o] = 0;
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o++;
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}
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d_offset++;
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h++;
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}
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break;
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default:
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std::runtime_error("bad state");
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break;
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}
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}
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dout << "produced : " << o << " consumed: " << i << std::endl;
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d_count += o;
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consume(0, i);
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consume(1, i);
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return o;
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@@ -193,11 +183,10 @@ void search_frame_start() {
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// sort list (highest correlation first)
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assert(d_cor.size() == SYNC_LENGTH);
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d_cor.sort();
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d_cor.reverse();
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d_cor.sort(compare_abs);
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// copy list in vector for nicer access
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vector<pair<double, int> > vec(d_cor.begin(), d_cor.end());
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vector<pair<gr_complex, int> > vec(d_cor.begin(), d_cor.end());
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d_cor.clear();
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// in case we don't find anything use SYNC_LENGTH
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@@ -205,17 +194,30 @@ void search_frame_start() {
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for(int i = 0; i < 3; i++) {
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for(int k = i + 1; k < 4; k++) {
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int diff = abs(get<1>(vec[i]) - get<1>(vec[k]));
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gr_complex first;
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gr_complex second;
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if(get<1>(vec[i]) > get<1>(vec[k])) {
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first = get<0>(vec[k]);
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second = get<0>(vec[i]);
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} else {
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first = get<0>(vec[i]);
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second = get<0>(vec[k]);
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}
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int diff = abs(get<1>(vec[i]) - get<1>(vec[k]));
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if(diff == 64) {
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d_frame_start = max(get<1>(vec[i]), get<1>(vec[k])) + 64;
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d_frame_start = max(get<1>(vec[i]), get<1>(vec[k])) + 64 - 128 - 1;
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d_freq_offset = arg(first * conj(second)) / 64;
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//std::cout << "frequency offset " << d_freq_offset << std::endl;
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// nice match found, return immediately
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return;
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// TODO: check if these offsets make sense
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} else if(diff == 63) {
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d_frame_start = max(get<1>(vec[i]), get<1>(vec[k])) + 63;
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d_frame_start = max(get<1>(vec[i]), get<1>(vec[k])) + 63 - 128 - 1;
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d_freq_offset = arg(first * conj(second)) / 64;
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} else if(diff == 65) {
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d_frame_start = max(get<1>(vec[i]), get<1>(vec[k])) + 64;
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d_frame_start = max(get<1>(vec[i]), get<1>(vec[k])) + 64 - 128 - 1;
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d_freq_offset = arg(first * conj(second)) / 64;
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}
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}
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}
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@@ -223,14 +225,15 @@ void search_frame_start() {
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private:
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enum {SYNC, COPY, RESET} d_state;
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int d_count;
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int d_offset;
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int d_frame_start;
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gr_complex d_freq_est;
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float d_freq_offset;
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gr_complex *d_correlation;
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gr_complex *d_freq_est_buf;
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list<pair<double, int> > d_cor;
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list<pair<gr_complex, int> > d_cor;
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std::vector<gr::tag_t> d_tags;
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gr::filter::kernel::fir_filter_ccc *d_fir;
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gr::filter::kernel::fir_filter_ccc d_fir;
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const bool d_log;
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const bool d_debug;
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