ANI功能分析
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1 ANI
ANI（Adapt Noise Immunity）就是基于CCK错包率，和/或CCK错包率，自动调整抗扰等级，从而提高或降低灵敏度，达到提高整体性能的目标。
2 关键常量
firstep_table = { -4, -2, 0, 2, 4, 6, 8, 10, 12}; /*FIR滤波级别表*/
cycpwr_thr1_table = { -6, -4, -2, 0, 2, 4, 6, 8 }; /*功率阈值表*/
ofdm_level_table[] = {
/* SI FS WS */
{ 0, 0, 1 }, /* lvl 0 */
{ 1, 1, 1 }, /* lvl 1 */
{ 2, 2, 1 }, /* lvl 2 */
{ 3, 2, 1 }, /* lvl 3 (default) */
{ 4, 3, 1 }, /* lvl 4 */
{ 5, 4, 1 }, /* lvl 5 */
{ 6, 5, 1 }, /* lvl 6 */
{ 7, 6, 1 }, /* lvl 7 */
{ 7, 7, 1 }, /* lvl 8 */
{ 7, 8, 0 } /* lvl 9 */
};
/*SI Spur-Immunity-level;FS=FIRStep;WS=OFDM weak sigal on */
cck_level_table[] = {
/* FS MRC-CCK */
{ 0, 1 }, /* lvl 0 */
{ 1, 1 }, /* lvl 1 */
{ 2, 1 }, /* lvl 2 (default) */
{ 3, 1 }, /* lvl 3 */
{ 4, 0 }, /* lvl 4 */
{ 5, 0 }, /* lvl 5 */
{ 6, 0 }, /* lvl 6 */
{ 7, 0 }, /* lvl 7 (only for high rssi) */
{ 8, 0 } /* lvl 8 (only for high rssi) */
};
/*FS=First Step; MRC-CCK: Maximal Ratio Combining for CCK*/
3 重要函数
3.1 加载
ar9300_ani_attach(struct ath_hal *ah)
for (i = 0; i < 256; i++) {
ahp->ah_ani[i].ofdm_trig_high = 1000;
ahp->ah_ani[i].ofdm_trig_low = 400;
ahp->ah_ani[i].cck_trig_high = 600;
ahp->ah_ani[i].cck_trig_low = 300;
ahp->ah_ani[i].rssi_thr_high = 40;
ahp->ah_ani[i].rssi_thr_low =7;
ahp->ah_ani[i].ofdm_noise_immunity_level =3;
ahp->ah_ani[i].cck_noise_immunity_level =2;
ahp->ah_ani[i].ofdm_weak_sig_detect_off = 0;
ahp->ah_ani[i].spur_immunity_level = 3;
ahp->ah_ani[i].firstep_level = 2;
ahp->ah_ani[i].mrc_cck_off =0;
ahp->ah_ani[i].ofdms_turn = true;
ahp->ah_ani[i].must_restore = false;
}
OS_REG_WRITE(ah, AR_PHY_ERR_1, 0); 寄存器MAC_PCU_PHY_ERR_CNT_1 归0
OS_REG_WRITE(ah, AR_PHY_ERR_2, 0); 寄存器MAC_PCU_PHY_ERR_CNT_2归0
ar9300_enable_mib_counters(ah);
归档ACKFAIL,RTSFAIL,FCSFAIL,RTSOK,BEACONCOUNT计数
FLT_OFDM，FLT_CCK计数归0，启动MAC_PCU_PHY_ERR_CNT_1_MASK对错误OFDM计数，启动MAC_PCU_PHY_ERR_CNT_2_MASK对错误CCK计数
ahp->ah_ani_period =1000
如果ANI使能，则ahp->ah_proc_phy_err |= HAL_PROCESS_ANI;
3.2 初始化
ar9300_ani_init_defaults(struct ath_hal *ah, HAL_HT_MACMODE macmode)
index = ar9300_get_ani_channel_index(ah, chan); 基于信道存放
ani_state = &ahp->ah_ani[index];
ahp->ah_curani = ani_state;
val = OS_REG_READ(ah, AR_PHY_SFCORR);取BB_sfcorr值，self-coordinate
利用val值，填充
ani_state->ini_def.m1_thresh，
ani_state->ini_def.m2_thresh，和
ani_state->ini_def.m2_count_thr
val = OS_REG_READ(ah, AR_PHY_SFCORR_LOW);取BB_sfcorr_low值，并填充
ani_state->ini_def.m1_thresh_low，
ani_state->ini_def.m2_thresh_low，
ani_state->ini_def.m2_count_thr_low
val = OS_REG_READ(ah, AR_PHY_SFCORR_EXT); 取BB_sfcorr_ext值，填充
ani_state->ini_def.m1_thresh_ext，
ani_state->ini_def.m2_thresh_ext，
ani_state->ini_def.m1_thresh_low_ext，
ani_state->ini_def.m2_thresh_low_ext
ani_state->ini_def.firstep 源自BB_find_signal的0x0003F000
ani_state->ini_def.firstep_low源自BB_find_signal_low的(0x3f << 6)
ani_state->ini_def.cycpwr_thr1 源自BB_timing_control_5的0x000000FE
ani_state->ini_def.cycpwr_thr1_ext源自BB_ext_chan_pwr_thr_2_b0的0x0000FE00
ani_state->spur_immunity_level=3
ani_state->firstep_level=2
ani_state->ofdm_weak_sig_detect_off=0
ani_state->mrc_cck_off=0
ani_state->cycle_count = 0;
3.3 OFDM抗扰
ar9300_ani_set_odfm_noise_immunity_level(struct ath_hal *ah,
u_int8_t ofdm_noise_immunity_level)
ani_state->rssi =当前值；
ani_state->ofdm_noise_immunity_level = ofdm_noise_immunity_level; 调整值
if (ani_state->spur_immunity_level !=
ofdm_level_table[ofdm_noise_immunity_level].spur_immunity_level)
调用ar9300_ani_control调整SI等级
if (ani_state->firstep_level !=
ofdm_level_table[ofdm_noise_immunity_level].fir_step_level &&
ofdm_level_table[ofdm_noise_immunity_level].fir_step_level >=
cck_level_table[ani_state->cck_noise_immunity_level].fir_step_level)
调用ar9300_ani_control调整FIR阶次；FIRStep是OFDM和CCK中的小者
若ani_state->rssi <= ani_state->rssi_thr_high 且ani_state->ofdm_weak_sig_detect_off，则调用ar9300_ani_control开启HAL_ANI_OFDM_WEAK_SIGNAL_DETECTION
若ani_state->ofdm_weak_sig_detect_off =
ofdm_level_table[ofdm_noise_immunity_level].ofdm_weak_signal_on，则基于后者的值，调用ar9300_ani_control开关HAL_ANI_OFDM_WEAK_SIGNAL_DETECTION
3.4 CCK抗扰
ar9300_ani_set_cck_noise_immunity_level(struct ath_hal *ah,
u_int8_t cck_noise_immunity_level)
更新ani_state->rssi
ani_state->cck_noise_immunity_level = cck_noise_immunity_level;
level = ani_state->ofdm_noise_immunity_level; OFDM抗扰等级
if (ani_state->firstep_level !=
cck_level_table[cck_noise_immunity_level].fir_step_level &&
cck_level_table[cck_noise_immunity_level].fir_step_level >=
ofdm_level_table[level].fir_step_level)
调用ar9300_ani_control调整FIR 阶次
DRAGONFLY和SCORPION型硬件，不调整MRC_CCK;否则，
若ani_state->mrc_cck_off ==
cck_level_table[cck_noise_immunity_level].mrc_cck_on
则调用ar9300_ani_control调整mrc_cck开关。
3.5 ANI控制
ar9300_ani_control(struct ath_hal *ah, HAL_ANI_CMD cmd, int param)
case OFDM_WEAK_SIGNAL_DETECTION
基于param为0或1，为BB_sfcorr_low,BB_sfcorr,BB_sfcorr_ext寄存器分别写入关闭检测的值，或由ar9300_ani_init_defaults初始化好的值。
BB_self_corr_low的0x00000001基于param值复位或置位。
ani_state->ofdm_weak_sig_detect_off =param值取反
case FIRSTEP_LEVEL
value =
firstep_table[param] - firstep_table[2] + ani_state->ini_def.firstep;
设置BB_find_signal中0x0003F000位为value
value2 =
firstep_table[param] -firstep_table[2] + ani_state->ini_def.firstep_low;
设置BB_find_signal_low中(0x3f << 6)位为value2
ani_state->firstep_level = param;
case SI_LEVEL
value =
cycpwr_thr1_table[param] - cycpwr_thr1_table[3] + ani_state->ini_def.cycpwr_thr1;
设置BB_ext_chan_pwr_thr_2_b0中0x0000FE00位为value
ani_state->spur_immunity_level = param;
case MRC_CCK
若为on，则为低级别抗噪，也是缺省；否则，为高等级抗噪
非POSEIDON平台时，BB_mrc_cck_ctrl的bit0，bit1设置为param值。
ani_state->mrc_cck_off =param值取反
3.6 OFDMERR触发器处理
ar9300_ani_ofdm_err_trigger(struct ath_hal *ah)
调用ar9300_ani_set_odfm_noise_immunity_level上调
ani_state->ofdm_noise_immunity_level 1个等级
CCKERR触发器处理
ar9300_ani_cck_err_trigger(struct ath_hal *ah)
调用ar9300_ani_set_cck_noise_immunity_level 上调
ani_state->cck_noise_immunity_level 1个等级
总之，只要OFDM/CCK错误统计越界，则上调抗噪等级，灵敏度降低。
3.7 抗噪调低处理
ar9300_ani_lower_immunity(struct ath_hal *ah)
优先调用ar9300_ani_set_odfm_noise_immunity_level调低ofdm_noise_immunity_level 1个等级
或者调用ar9300_ani_set_cck_noise_immunity_level 调低cck_noise_immunity_level 1个等级
4 抗噪处理
ar9300_ani_ar_poll(struct ath_hal *ah, const HAL_NODE_STATS *stats,
HAL_CHANNEL *chan, HAL_ANISTATS *ani_stats)
ani_state = ahp->ah_curani;
ahp->ah_stats.ast_nodestats = *stats;
listen_time = ar9300_ani_get_listen_time(ah, ani_stats); 返回一个0（非法）或正值
ani_state->listen_time += listen_time;
ar9300_update_mib_mac_stats(ah);
ofdm_phy_err_cnt = OFDM错误统计值;
cck_phy_err_cnt = CCK错误统计值
ahp->ah_stats.ast_ani_ofdmerrs和ahp->ah_stats.ast_ani_cckerrs 累加本轮递增值
统计ofdm_phy_err_rate和cck_phy_err_rate 值，均为本listen_time期内的错误比率
若ani_state->listen_time >=100 则
old_phy_noise_spur = ani_state->phy_noise_spur;
若ofdm_phy_err_rate <= ani_state->ofdm_trig_low 且
cck_phy_err_rate <= ani_state->cck_trig_low) 则
若ani_state->listen_time >= 5000 则ani_state->phy_noise_spur = 0;
否则ani_state->phy_noise_spur = 1;
若ani_state->listen_time > 5 * ahp->ah_ani_period 则
若ofdm_phy_err_rate <= ani_state->ofdm_trig_low 且
cck_phy_err_rate <= ani_state->cck_trig_low 则
调用ar9300_ani_lower_immunity 调低抗噪等级
调用ar9300_ani_restar重启计数
否则若ani_state->listen_time > ahp->ah_ani_period 则
若ofdm_phy_err_rate > ani_state->ofdm_trig_high 且
cck_phy_err_rate <= ani_state->cck_trig_high 或 检测odfm 则
调用ar9300_ani_ofdm_err_trigger，上调抗噪等级
调用ar9300_ani_restart重启计数
检测ofdm标记复位
否则 若cck_phy_err_rate > ani_state->cck_trig_high 则
调用ar9300_ani_cck_err_trigger，上调抗噪等级
调用ar9300_ani_restart 重启计数
检测ofdm标记置位
5 总结
启用了ANI（缺省）时，会基于OFDM Err和CCK Err统计值，自动调整抗噪等级，从而提高或降低接收机灵敏度（是否能调整PLCP灵敏度未知）。所以在一个需要高灵敏的场景下，需要先关闭ANI功能，然后直接手工调整：
弱信号寄存器：BB_sfcorr_low, BB_sfcorr, BB_ext_chan_scorr_thr的值，并确保BB_sfcorr_low的bit0为1（启用）或为0（关闭）；
FIR阶次寄存器：BB_find_signal，BB_find_signal_low
冲激（毛刺）寄存器：BB_timing_control_5，BB_ext_chan_pwr_thr_2_b0
MRC（Maximal Ratio Combining）寄存器： BB_mrc_cck_ctrl的bit1-0，全为0或1；MRC对CCK有额外要求，如果低速下效果满意，可以取反测试一下。
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