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convcode.h
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1 
29 #ifndef CONVCODE_H
30 #define CONVCODE_H
31 
32 #include <itpp/base/vec.h>
33 #include <itpp/base/mat.h>
34 #include <itpp/base/array.h>
35 #include <itpp/base/binary.h>
36 #include <itpp/comm/channel_code.h>
37 #include <itpp/itexports.h>
38 #include <itpp/base/base_exports.h>
39 
40 namespace itpp
41 {
42 
47 enum CONVOLUTIONAL_CODE_TYPE {MFD, ODS};
48 
53 enum CONVOLUTIONAL_CODE_METHOD {Trunc, Tail, Tailbite};
54 
55 
104 class ITPP_EXPORT Convolutional_Code : public Channel_Code
105 {
106 public:
108  Convolutional_Code(void): K(0), start_state(0), cc_method(Tail) {
109  set_code(MFD, 2, 7);
110  init_encoder();
111  }
112 
114  virtual ~Convolutional_Code(void) {}
115 
118  cc_method = method;
119  }
120 
128  void set_code(const CONVOLUTIONAL_CODE_TYPE type_of_code, int inverse_rate,
129  int constraint_length);
130 
132  void set_generator_polynomials(const ivec &gen, int constraint_length);
134  ivec get_generator_polynomials(void) const { return gen_pol; }
135 
137  void reset();
138 
139 
141 
142  virtual void encode(const bvec &input, bvec &output);
143  virtual bvec encode(const bvec &input) {
144  bvec output;
145  encode(input, output);
146  return output;
147  }
149 
151 
157  void encode_trunc(const bvec &input, bvec &output);
158  bvec encode_trunc(const bvec &input) {
159  bvec output;
160  encode_trunc(input, output);
161  return output;
162  }
164 
166 
176  void encode_tail(const bvec &input, bvec &output);
177  bvec encode_tail(const bvec &input) {
178  bvec output;
179  encode_tail(input, output);
180  return output;
181  }
183 
185 
199  void encode_tailbite(const bvec &input, bvec &output);
200  bvec encode_tailbite(const bvec &input) {
201  bvec output;
202  encode_tailbite(input, output);
203  return output;
204  }
206 
208 
213  void encode_bit(const bin &input, bvec &output);
214  bvec encode_bit(const bin &input) {
215  bvec output;
216  encode_bit(input, output);
217  return output;
218  }
220 
221  // ------------ Hard-decision decoding is not implemented ----------------
222  virtual void decode(const bvec &coded_bits, bvec &decoded_bits);
223  virtual bvec decode(const bvec &coded_bits);
224 
226 
227  virtual void decode(const vec &received_signal, bvec &output);
228  virtual bvec decode(const vec &received_signal) {
229  bvec output;
230  decode(received_signal, output);
231  return output;
232  }
234 
236 
242  virtual void decode_tail(const vec &received_signal, bvec &output);
243  virtual bvec decode_tail(const vec &received_signal) {
244  bvec output;
245  decode_tail(received_signal, output);
246  return output;
247  }
249 
251 
259  virtual void decode_tailbite(const vec &received_signal, bvec &output);
260  virtual bvec decode_tailbite(const vec &received_signal) {
261  bvec output;
262  decode_tailbite(received_signal, output);
263  return output;
264  }
266 
268 
269  virtual void decode_trunc(const vec &received_signal, bvec &output);
270  virtual bvec decode_trunc(const vec &received_signal) {
271  bvec output;
272  decode_trunc(received_signal, output);
273  return output;
274  }
276 
277 
279  virtual double get_rate(void) const { return rate; }
280 
281 
283  void set_start_state(int state) {
284  it_error_if((state < 0) || ((state >= (1 << m)) && m != 0),
285  "Convolutional_Code::set_start_state(): Invalid start state");
286  start_state = state;
287  }
288 
293  void init_encoder() { encoder_state = start_state; }
294 
296  int get_encoder_state(void) const { return encoder_state; }
297 
298 
300  void set_truncation_length(const int length) {
301  it_error_if(length < K, "Convolutional_Code::set_truncation_length(): "
302  "Truncation length shorter than K");
303  trunc_length = length;
304  }
305 
307  int get_truncation_length(void) const { return trunc_length; }
308 
309 
311  bool catastrophic(void);
312 
313 
322  bool inverse_tail(const bvec coded_sequence, bvec &input);
323 
324 
327  void distance_profile(ivec &dist_prof, int dmax = 100000,
328  bool reverse = false);
329 
345  void calculate_spectrum(Array<ivec> &spectrum, int dmax, int no_terms);
346 
369  int fast(Array<ivec> &spectrum, const int dfree, const int no_terms,
370  const int Cdfree = 1000000, const bool test_catastrophic = false);
371 
372 protected:
374  int next_state(const int instate, const int input) {
375  return ((instate >> 1) | (input << (m - 1)));
376  }
378  int previous_state(const int state, const int input) {
379  return (((state << 1) | input) & ((1 << m) - 1));
380  }
382  void previous_state(const int state, int &S0, int &S1) {
383  S0 = (state << 1) & (no_states - 1);
384  S1 = S0 | 1;
385  }
387  int weight(const int state, const int input);
389  void weight(const int state, int &w0, int &w1);
392  int weight_reverse(const int state, const int input);
395  void weight_reverse(const int state, int &w0, int &w1);
397  bvec output_reverse(const int state, const int input);
399  void output_reverse(const int state, bvec &zero_output, bvec &one_output);
401  void output_reverse(const int state, int &zero_output, int &one_output);
403  void calc_metric_reverse(const int state, const vec &rx_codeword,
404  double &zero_metric, double &one_metric);
406  void calc_metric(const vec &rx_codeword, vec &delta_metrics);
408  int get_input(const int state) { return (state >> (m - 1)); }
409 
411  int n;
413  int K;
415  int m;
419  ivec gen_pol;
429  double rate;
446 };
447 
448 // --------------- Some other functions that maybe should be moved -----------
453 ITPP_EXPORT int reverse_int(int length, int in);
454 
459 ITPP_EXPORT int weight_int(int length, int in);
460 
465 ITPP_EXPORT int compare_spectra(ivec v1, ivec v2);
466 
473 ITPP_EXPORT int compare_spectra(ivec v1, ivec v2, vec weight_profile);
474 
475 } // namespace itpp
476 
477 #endif // #ifndef CONVCODE_H
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