summaryrefslogtreecommitdiff
path: root/cesar/ce/rx/bitloading/src/ber.c
blob: 2397aa1d6862b8da2f0c2b3a9b4b854433ee3f9b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
/* Cesar project {{{
 *
 * Copyright (C) 2009 Spidcom
 *
 * <<<Licence>>>
 *
 * }}} */
/**
 * \file    ce/rx/bitloading/src/ber.c
 * \brief   Functions to compute BER.
 * \ingroup ce_rx
 *
 * This module contains some sets of functions to compute the BER from a given
 * NSR and modulation.
 */
#include "common/std.h"

#include "ce/rx/bitloading/inc/ber.h"
#include "ce/rx/bitloading/inc/poly.h"
#include "ce/rx/ce_rx_param.h"

/**
 * The configuration of the BER module.
 */
ce_rx_bl_ber_conf_t ce_rx_bl_ber_conf;

/**
 * Default value of margin to apply to BER target.
 * This value is apparently quantified on 53 bits.
 *
 * By default, we do not want any BER margin.
 */
s64 ce_rx_bl_ber_margin_[] = {
    CE_RX_BL_BER_MARGIN_1_2_DEFAULT, CE_RX_BL_BER_MARGIN_16_21_DEFAULT
};

/* Imported from 2 files:
 * http://stestephe/svn/spidcom_digital_svn/projects/DSP_350/DSP_chain/SW/Bit_Loading/BER_vs_NSR/Polynomes_BERinq_vs_NSRq_normalises.m
 * http://stestephe/svn/spidcom_digital_svn/projects/DSP_350/DSP_chain/SW/Bit_Loading/BitAllocationNSRLines.m
 * Revision: 19108.
 */
ce_rx_bl_ber_poly_coef_t ce_rx_bl_ber_poly_coef[CE_MOD_COUNT - 1] =
{
    CE_RX_BL_BER_POLY_COEF
};

static const s64
ce_rx_bl_ber_consign_coefs_av[PHY_FEC_RATE_NB][CE_RX_BL_BER_POLY_MAX_DEGREE] =
{
    CE_RX_BL_BER_CONSIGN_COEFS_AV
};
static const u8 ce_rx_bl_ber_consign_degrees_av[PHY_FEC_RATE_NB] =
{
    CE_RX_BL_BER_CONSIGN_DEGREES_AV
};

static const s64
ce_rx_bl_ber_consign_coefs_eoc[PHY_FEC_RATE_NB][CE_RX_BL_BER_POLY_MAX_DEGREE] =
{
    CE_RX_BL_BER_CONSIGN_COEFS_EOC
};
static const u8 ce_rx_bl_ber_consign_degrees_eoc[PHY_FEC_RATE_NB] =
{
    CE_RX_BL_BER_CONSIGN_DEGREES_EOC
};

const u64 ce_rx_bl_initial_bpt[PHY_FEC_RATE_NB] = {
    10 * CE_RX_BL_BPT_QUANT_FACTOR,
    10 * CE_RX_BL_BPT_QUANT_FACTOR
};

u64
ce_rx_bl_ber_for_mod (ce_rx_bl_ber_poly_coef_t poly[CE_MOD_COUNT - 1],
                      u32 nsr, u8 mod_index)
{
    /* Check parameters. */
    dbg_assert (poly);
    dbg_assert (mod_index <= CE_MOD_COUNT);

    /* If modulation is 0 or NSR under first range. */
    if (!mod_index || nsr < poly[mod_index - 1].range[0])
        return CE_RX_BL_BER_DEFAULT_UNDER;
    /* Go through each range. */
    uint i;
    for (i = 0; i < poly[mod_index - 1].poly_count; i++)
    {
        /* If under range, compute polynomial. */
        if (nsr <= poly[mod_index - 1].range[i + 1])
            return ce_rx_bl_poly (poly[mod_index - 1].degree[i],
                                  poly[mod_index - 1].coef[i],
                                  nsr);
    }
    return CE_RX_BL_BER_DEFAULT_OVER;
}

void
ce_rx_bl_ber_vs_nsr (ce_rx_bl_ber_poly_coef_t poly[CE_MOD_COUNT - 1], u32 nsr,
                     u64 ber_pt, u8 *mod_lower, u64 *ber_lower,
                     u64 *ber_upper)
{
    /* Check parameters. */
    dbg_assert (poly);
    dbg_assert (ber_pt < CE_RX_BL_BER_DEFAULT_OVER);
    dbg_assert (mod_lower);
    dbg_assert (ber_lower);
    dbg_assert (ber_upper);

    /* Let's do a dichotomy search. */
    uint lm = 1, um = 8, m;
    u64 ber_index[CE_MOD_COUNT] = { 0, -1, -1, -1, -1, -1, -1, -1 };

    /* Dichotomy search. */
    while (lm != um)
    {
        m = (lm + um) / 2;
        ber_index[m] = ce_rx_bl_ber_for_mod (poly, nsr, m);
        /* Index to high? */
        if (ber_index[m] > ber_pt)
        {
            um = m;
        }
        else
        {
            lm = m + 1;
        }
    }
    m = lm;

    dbg_assert (m);
    *mod_lower = m - 1;
    *ber_lower = ber_index[m - 1];
    /* Lower BER must respect consign. */
    dbg_assert (*ber_lower < ber_pt);
    *ber_upper = ber_index[m];
}

u64
ce_rx_bl_ber_pt_bpt (phy_fecrate_t fec_rate, uint carrier_nb, u64 bpt)
{
    /* Check parameters. */
    dbg_assert (fec_rate < PHY_FEC_RATE_NB);
    dbg_assert (carrier_nb);
    dbg_assert (bpt >= (CE_BIT_PER_MOD[1] * CE_RX_BL_BPT_QUANT_FACTOR)
                && bpt <= (CE_BIT_PER_MOD[CE_MOD_COUNT - 1]
                           * CE_RX_BL_BPT_QUANT_FACTOR));

    /* Local configuration for multiple polynomials carriers enabled
     * dependant. */
    struct ce_rx_bl_ber_pt_bpt_conf_t {
        uint carrier_max;
        const u8 (*degrees)[PHY_FEC_RATE_NB];
        const s64 (*polys)[PHY_FEC_RATE_NB][CE_RX_BL_BER_POLY_MAX_DEGREE];
    };

    /* Configuration for polynomials to use based. */
    struct ce_rx_bl_ber_pt_bpt_conf_t conf[] = {
        /* For AV. */
        {
            917,
            &ce_rx_bl_ber_consign_degrees_av,
            &ce_rx_bl_ber_consign_coefs_av,
        },
        /* For EoC. */
        {
            1366,
            &ce_rx_bl_ber_consign_degrees_eoc,
            &ce_rx_bl_ber_consign_coefs_eoc,
        },
    };

    /* Find the polynomials to use. */
    /* A note here: apparently using a polynomials defined for X carriers
     * enabled with a tone mask with less carrier enabled is ok and just give
     * lower result. It should have no bad side effect (according to a
     * discussion with the TNS team). */
    uint i;
    for (i = 0; i < COUNT (conf); i++)
    {
        if (carrier_nb <= conf[i].carrier_max)
        {
            return ce_rx_bl_poly ((*conf[i].degrees)[fec_rate],
                                  (*conf[i].polys)[fec_rate], bpt);
        }
    }
    /* Unsupported tone mask. */
    dbg_assert_default ();
}

void
ce_rx_bl_ber_margin_set (s64 margin_q[PHY_FEC_RATE_NB])
{
    /* Check parameter. */
    dbg_assert (margin_q);

    /* Store margin values. */
    phy_fecrate_t i;
    for (i = PHY_FEC_RATE_1_2; i < PHY_FEC_RATE_NB; i++)
        ce_rx_bl_ber_margin_[i] = margin_q[i];
}

void
ce_rx_bl_ber_sliding_mean_update (ce_rx_bitloading_t *bl, u64 ber)
{
    /* Check parameter. */
    dbg_assert (bl);

    uint i;

    /* First value? */
    if (bl->ber_sliding_mean[CE_RX_BL_BER_SLIDING_MEAN_FAST] == -1)
    {
        /* Initialize sliding means. */
        for (i = 0; i < CE_RX_BL_BER_SLIDING_MEAN_NB; i++)
        {
            bl->ber_sliding_mean[i] = ber;
        }
    }
    else
    {
       /* Update fast sliding mean. */
       bl->ber_sliding_mean[CE_RX_BL_BER_SLIDING_MEAN_FAST]
            = ((u64) ce_rx_bl_ber_conf.sliding_mean_fast_factor
                    * bl->ber_sliding_mean[CE_RX_BL_BER_SLIDING_MEAN_FAST]
                   + (CE_RX_BL_BER_SLIDING_MEAN_FACTOR_DIV
                      - ce_rx_bl_ber_conf.sliding_mean_fast_factor) * ber)
                     / CE_RX_BL_BER_SLIDING_MEAN_FACTOR_DIV;

       /* Update slow sliding mean. */
       bl->ber_sliding_mean[CE_RX_BL_BER_SLIDING_MEAN_SLOW]
            = ((u64) ce_rx_bl_ber_conf.sliding_mean_slow_factor
                    * bl->ber_sliding_mean[CE_RX_BL_BER_SLIDING_MEAN_SLOW]
                   + (CE_RX_BL_BER_SLIDING_MEAN_FACTOR_DIV
                      - ce_rx_bl_ber_conf.sliding_mean_slow_factor) * ber)
                     / CE_RX_BL_BER_SLIDING_MEAN_FACTOR_DIV;

    }
}

u64
ce_rx_bl_ber_quantify (ce_rx_measure_mbox_t *measure, u64 ber_reached,
                       u16 pb_size)
{
    u64 num1 = CE_RX_BL_BER_QUANT_FACTOR;
    u64 div1 = measure->total_pb_count * pb_size;
    u64 num2 = measure->false_pb_count * ber_reached;
    u64 div2 = measure->total_pb_count;
    u64 res1 = measure->ber_sum * (ROUND_DIV (num1, div1));
    u64 res2 = 2 * (ROUND_DIV (num2, div2));
    return (res1 + res2 );
}

u64
ce_rx_bl_ber_pt_robo (uint carrier_nb)
{
    /* It corresponds to the BER target for 2 bits per tone for FEC rate
       1/2. */
    return ce_rx_bl_ber_pt_bpt (PHY_FEC_RATE_1_2, carrier_nb,
                                2 * CE_RX_BL_BPT_QUANT_FACTOR);
}