[12] | 1 | // |
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| 2 | // Cognitive radio simulator |
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| 3 | // |
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| 4 | |
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| 5 | #include "cognitive_radio_test.h" |
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| 6 | |
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| 7 | // transmitter thread |
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| 8 | void execute_tx( |
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| 9 | metadata _md, |
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| 10 | char *_msg_in, |
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| 11 | unsigned int _msg_len, |
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| 12 | float * _I, |
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| 13 | float *_Q, |
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| 14 | unsigned int *_sym_len) |
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| 15 | { |
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| 16 | // symbols buffer |
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| 17 | char sym[_msg_len]; |
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| 18 | |
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| 19 | // pack bits into symbols |
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| 20 | repack_bytes( |
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| 21 | _msg_in, // input buffer |
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| 22 | 1, // input symbol size (number bits) |
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| 23 | _msg_len, // input buffer size |
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| 24 | sym, // output buffer |
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| 25 | _md->mod_bps, // output symbol size (number of bits) |
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| 26 | _msg_len, // output buffer size |
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| 27 | _sym_len // number of symbols written to output |
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| 28 | ); |
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| 29 | |
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| 30 | // run modulator |
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| 31 | unsigned int i, s; |
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| 32 | modem * mod = modem_create(_md->mod_scheme, _md->mod_bps); |
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| 33 | for (i=0; i<(*_sym_len); i++) { |
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| 34 | s = (unsigned int)(sym[i]); |
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| 35 | modulate(mod, s, &_I[i], &_Q[i]); |
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| 36 | } |
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| 37 | } |
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| 38 | |
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| 39 | // channel thread |
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| 40 | void execute_channel(metadata _md, float _std, float * _I, float *_Q, unsigned int _len) |
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| 41 | { |
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| 42 | // add noise |
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| 43 | float noise_i, noise_q; |
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| 44 | unsigned int i; |
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| 45 | for (i=0; i<_len; i++) { |
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| 46 | // generate random noise values |
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| 47 | randnf(&noise_i, &noise_q); |
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| 48 | |
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| 49 | // TODO scale by appropriate amount |
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| 50 | _I[i] += noise_i * _std; |
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| 51 | _Q[i] += noise_q * _std; |
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| 52 | } |
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| 53 | } |
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| 54 | |
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| 55 | // receiver thread |
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| 56 | void execute_rx( |
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| 57 | metadata _md, |
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| 58 | float * _I, |
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| 59 | float *_Q, |
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| 60 | unsigned int _sym_len, |
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| 61 | char *_msg_out, |
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| 62 | unsigned int *_msg_len) |
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| 63 | { |
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| 64 | char msg[_sym_len]; |
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| 65 | |
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| 66 | // create demodulator and demodulate |
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| 67 | modem * demod = modem_create(_md->mod_scheme, _md->mod_bps); |
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| 68 | unsigned int i, s; |
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| 69 | for (i=0; i<_sym_len; i++) { |
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| 70 | demodulate(demod, _I[i], _Q[i], &s); |
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| 71 | msg[i] = (char) s; |
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| 72 | } |
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| 73 | |
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| 74 | // unpack bytes |
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| 75 | repack_bytes( |
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| 76 | msg, // input buffer |
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| 77 | _md->mod_bps, // input symbol size (number of bits) |
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| 78 | _sym_len, // num input symbols |
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| 79 | _msg_out, // output buffer |
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| 80 | 1, // output symbol size (number of bits) |
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| 81 | 999999, // output buffer size |
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| 82 | _msg_len // number of output symbols written |
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| 83 | ); |
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| 84 | |
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| 85 | } |
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| 86 | |
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| 87 | unsigned int count_errors(char * _msg_in, char * _msg_out, unsigned int _num_bits) |
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| 88 | { |
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| 89 | unsigned int i, num_errors=0; |
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| 90 | for (i=0; i<_num_bits; i++) |
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| 91 | num_errors += (_msg_in[i]==_msg_out[i]) ? 0 : 1; |
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| 92 | |
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| 93 | return num_errors; |
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| 94 | } |
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