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