ANI功能分析

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。