TCH Viterbi decode Parameter

Chengcheng Gou gouchengcheng at gmail.com
Tue Jun 5 08:13:23 UTC 2012


Hi:

I am studying the tch code, and want to decode the Convolutional code
of TCH using
xcch.c; and how to set the parameters;

1. conv_xcch_next_output
2. conv_xcch_next_state
3. N = 2,
4. K = 5,

static const uint8_t conv_xcch_next_output[][2] = {
	{ 0, 3 }, { 1, 2 }, { 0, 3 }, { 1, 2 },
	{ 3, 0 }, { 2, 1 }, { 3, 0 }, { 2, 1 },
	{ 3, 0 }, { 2, 1 }, { 3, 0 }, { 2, 1 },
	{ 0, 3 }, { 1, 2 }, { 0, 3 }, { 1, 2 },
};

static const uint8_t conv_xcch_next_state[][2] = {
	{  0,  1 }, {  2,  3 }, {  4,  5 }, {  6,  7 },
	{  8,  9 }, { 10, 11 }, { 12, 13 }, { 14, 15 },
	{  0,  1 }, {  2,  3 }, {  4,  5 }, {  6,  7 },
	{  8,  9 }, { 10, 11 }, { 12, 13 }, { 14, 15 },
};

const struct osmo_conv_code conv_xcch = {
	.N = 2,
	.K = 5,
	.len = 224,
	.next_output = conv_xcch_next_output,
	.next_state  = conv_xcch_next_state,
};

Thanks!




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