acs.c revision cce06667447b5aec83452adb0c15100ada531095
1/* 2 * ACS - Automatic Channel Selection module 3 * Copyright (c) 2011, Atheros Communications 4 * Copyright (c) 2013, Qualcomm Atheros, Inc. 5 * 6 * This software may be distributed under the terms of the BSD license. 7 * See README for more details. 8 */ 9 10#include "utils/includes.h" 11#include <math.h> 12 13#include "utils/common.h" 14#include "utils/list.h" 15#include "common/ieee802_11_defs.h" 16#include "common/wpa_ctrl.h" 17#include "drivers/driver.h" 18#include "hostapd.h" 19#include "ap_drv_ops.h" 20#include "ap_config.h" 21#include "hw_features.h" 22#include "acs.h" 23 24/* 25 * Automatic Channel Selection 26 * =========================== 27 * 28 * More info at 29 * ------------ 30 * http://wireless.kernel.org/en/users/Documentation/acs 31 * 32 * How to use 33 * ---------- 34 * - make sure you have CONFIG_ACS=y in hostapd's .config 35 * - use channel=0 or channel=acs to enable ACS 36 * 37 * How does it work 38 * ---------------- 39 * 1. passive scans are used to collect survey data 40 * (it is assumed that scan trigger collection of survey data in driver) 41 * 2. interference factor is calculated for each channel 42 * 3. ideal channel is picked depending on channel width by using adjacent 43 * channel interference factors 44 * 45 * Known limitations 46 * ----------------- 47 * - Current implementation depends heavily on the amount of time willing to 48 * spend gathering survey data during hostapd startup. Short traffic bursts 49 * may be missed and a suboptimal channel may be picked. 50 * - Ideal channel may end up overlapping a channel with 40 MHz intolerant BSS 51 * 52 * Todo / Ideas 53 * ------------ 54 * - implement other interference computation methods 55 * - BSS/RSSI based 56 * - spectral scan based 57 * (should be possibly to hook this up with current ACS scans) 58 * - add wpa_supplicant support (for P2P) 59 * - collect a histogram of interference over time allowing more educated 60 * guess about an ideal channel (perhaps CSA could be used to migrate AP to a 61 * new "better" channel while running) 62 * - include neighboring BSS scan to avoid conflicts with 40 MHz intolerant BSSs 63 * when choosing the ideal channel 64 * 65 * Survey interference factor implementation details 66 * ------------------------------------------------- 67 * Generic interference_factor in struct hostapd_channel_data is used. 68 * 69 * The survey interference factor is defined as the ratio of the 70 * observed busy time over the time we spent on the channel, 71 * this value is then amplified by the observed noise floor on 72 * the channel in comparison to the lowest noise floor observed 73 * on the entire band. 74 * 75 * This corresponds to: 76 * --- 77 * (busy time - tx time) / (active time - tx time) * 2^(chan_nf + band_min_nf) 78 * --- 79 * 80 * The coefficient of 2 reflects the way power in "far-field" 81 * radiation decreases as the square of distance from the antenna [1]. 82 * What this does is it decreases the observed busy time ratio if the 83 * noise observed was low but increases it if the noise was high, 84 * proportionally to the way "far field" radiation changes over 85 * distance. 86 * 87 * If channel busy time is not available the fallback is to use channel RX time. 88 * 89 * Since noise floor is in dBm it is necessary to convert it into Watts so that 90 * combined channel interference (e.g., HT40, which uses two channels) can be 91 * calculated easily. 92 * --- 93 * (busy time - tx time) / (active time - tx time) * 94 * 2^(10^(chan_nf/10) + 10^(band_min_nf/10)) 95 * --- 96 * 97 * However to account for cases where busy/rx time is 0 (channel load is then 98 * 0%) channel noise floor signal power is combined into the equation so a 99 * channel with lower noise floor is preferred. The equation becomes: 100 * --- 101 * 10^(chan_nf/5) + (busy time - tx time) / (active time - tx time) * 102 * 2^(10^(chan_nf/10) + 10^(band_min_nf/10)) 103 * --- 104 * 105 * All this "interference factor" is purely subjective and only time 106 * will tell how usable this is. By using the minimum noise floor we 107 * remove any possible issues due to card calibration. The computation 108 * of the interference factor then is dependent on what the card itself 109 * picks up as the minimum noise, not an actual real possible card 110 * noise value. 111 * 112 * Total interference computation details 113 * -------------------------------------- 114 * The above channel interference factor is calculated with no respect to 115 * target operational bandwidth. 116 * 117 * To find an ideal channel the above data is combined by taking into account 118 * the target operational bandwidth and selected band. E.g., on 2.4 GHz channels 119 * overlap with 20 MHz bandwidth, but there is no overlap for 20 MHz bandwidth 120 * on 5 GHz. 121 * 122 * Each valid and possible channel spec (i.e., channel + width) is taken and its 123 * interference factor is computed by summing up interferences of each channel 124 * it overlaps. The one with least total interference is picked up. 125 * 126 * Note: This implies base channel interference factor must be non-negative 127 * allowing easy summing up. 128 * 129 * Example ACS analysis printout 130 * ----------------------------- 131 * 132 * ACS: Trying survey-based ACS 133 * ACS: Survey analysis for channel 1 (2412 MHz) 134 * ACS: 1: min_nf=-113 interference_factor=0.0802469 nf=-113 time=162 busy=0 rx=13 135 * ACS: 2: min_nf=-113 interference_factor=0.0745342 nf=-113 time=161 busy=0 rx=12 136 * ACS: 3: min_nf=-113 interference_factor=0.0679012 nf=-113 time=162 busy=0 rx=11 137 * ACS: 4: min_nf=-113 interference_factor=0.0310559 nf=-113 time=161 busy=0 rx=5 138 * ACS: 5: min_nf=-113 interference_factor=0.0248447 nf=-113 time=161 busy=0 rx=4 139 * ACS: * interference factor average: 0.0557166 140 * ACS: Survey analysis for channel 2 (2417 MHz) 141 * ACS: 1: min_nf=-113 interference_factor=0.0185185 nf=-113 time=162 busy=0 rx=3 142 * ACS: 2: min_nf=-113 interference_factor=0.0246914 nf=-113 time=162 busy=0 rx=4 143 * ACS: 3: min_nf=-113 interference_factor=0.037037 nf=-113 time=162 busy=0 rx=6 144 * ACS: 4: min_nf=-113 interference_factor=0.149068 nf=-113 time=161 busy=0 rx=24 145 * ACS: 5: min_nf=-113 interference_factor=0.0248447 nf=-113 time=161 busy=0 rx=4 146 * ACS: * interference factor average: 0.050832 147 * ACS: Survey analysis for channel 3 (2422 MHz) 148 * ACS: 1: min_nf=-113 interference_factor=2.51189e-23 nf=-113 time=162 busy=0 rx=0 149 * ACS: 2: min_nf=-113 interference_factor=0.0185185 nf=-113 time=162 busy=0 rx=3 150 * ACS: 3: min_nf=-113 interference_factor=0.0186335 nf=-113 time=161 busy=0 rx=3 151 * ACS: 4: min_nf=-113 interference_factor=0.0186335 nf=-113 time=161 busy=0 rx=3 152 * ACS: 5: min_nf=-113 interference_factor=0.0186335 nf=-113 time=161 busy=0 rx=3 153 * ACS: * interference factor average: 0.0148838 154 * ACS: Survey analysis for channel 4 (2427 MHz) 155 * ACS: 1: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0 156 * ACS: 2: min_nf=-114 interference_factor=0.0555556 nf=-114 time=162 busy=0 rx=9 157 * ACS: 3: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=161 busy=0 rx=0 158 * ACS: 4: min_nf=-114 interference_factor=0.0186335 nf=-114 time=161 busy=0 rx=3 159 * ACS: 5: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1 160 * ACS: * interference factor average: 0.0160801 161 * ACS: Survey analysis for channel 5 (2432 MHz) 162 * ACS: 1: min_nf=-114 interference_factor=0.409938 nf=-113 time=161 busy=0 rx=66 163 * ACS: 2: min_nf=-114 interference_factor=0.0432099 nf=-113 time=162 busy=0 rx=7 164 * ACS: 3: min_nf=-114 interference_factor=0.0124224 nf=-113 time=161 busy=0 rx=2 165 * ACS: 4: min_nf=-114 interference_factor=0.677019 nf=-113 time=161 busy=0 rx=109 166 * ACS: 5: min_nf=-114 interference_factor=0.0186335 nf=-114 time=161 busy=0 rx=3 167 * ACS: * interference factor average: 0.232244 168 * ACS: Survey analysis for channel 6 (2437 MHz) 169 * ACS: 1: min_nf=-113 interference_factor=0.552795 nf=-113 time=161 busy=0 rx=89 170 * ACS: 2: min_nf=-113 interference_factor=0.0807453 nf=-112 time=161 busy=0 rx=13 171 * ACS: 3: min_nf=-113 interference_factor=0.0310559 nf=-113 time=161 busy=0 rx=5 172 * ACS: 4: min_nf=-113 interference_factor=0.434783 nf=-112 time=161 busy=0 rx=70 173 * ACS: 5: min_nf=-113 interference_factor=0.0621118 nf=-113 time=161 busy=0 rx=10 174 * ACS: * interference factor average: 0.232298 175 * ACS: Survey analysis for channel 7 (2442 MHz) 176 * ACS: 1: min_nf=-113 interference_factor=0.440994 nf=-112 time=161 busy=0 rx=71 177 * ACS: 2: min_nf=-113 interference_factor=0.385093 nf=-113 time=161 busy=0 rx=62 178 * ACS: 3: min_nf=-113 interference_factor=0.0372671 nf=-113 time=161 busy=0 rx=6 179 * ACS: 4: min_nf=-113 interference_factor=0.0372671 nf=-113 time=161 busy=0 rx=6 180 * ACS: 5: min_nf=-113 interference_factor=0.0745342 nf=-113 time=161 busy=0 rx=12 181 * ACS: * interference factor average: 0.195031 182 * ACS: Survey analysis for channel 8 (2447 MHz) 183 * ACS: 1: min_nf=-114 interference_factor=0.0496894 nf=-112 time=161 busy=0 rx=8 184 * ACS: 2: min_nf=-114 interference_factor=0.0496894 nf=-114 time=161 busy=0 rx=8 185 * ACS: 3: min_nf=-114 interference_factor=0.0372671 nf=-113 time=161 busy=0 rx=6 186 * ACS: 4: min_nf=-114 interference_factor=0.12963 nf=-113 time=162 busy=0 rx=21 187 * ACS: 5: min_nf=-114 interference_factor=0.166667 nf=-114 time=162 busy=0 rx=27 188 * ACS: * interference factor average: 0.0865885 189 * ACS: Survey analysis for channel 9 (2452 MHz) 190 * ACS: 1: min_nf=-114 interference_factor=0.0124224 nf=-114 time=161 busy=0 rx=2 191 * ACS: 2: min_nf=-114 interference_factor=0.0310559 nf=-114 time=161 busy=0 rx=5 192 * ACS: 3: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=161 busy=0 rx=0 193 * ACS: 4: min_nf=-114 interference_factor=0.00617284 nf=-114 time=162 busy=0 rx=1 194 * ACS: 5: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0 195 * ACS: * interference factor average: 0.00993022 196 * ACS: Survey analysis for channel 10 (2457 MHz) 197 * ACS: 1: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1 198 * ACS: 2: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1 199 * ACS: 3: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1 200 * ACS: 4: min_nf=-114 interference_factor=0.0493827 nf=-114 time=162 busy=0 rx=8 201 * ACS: 5: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0 202 * ACS: * interference factor average: 0.0136033 203 * ACS: Survey analysis for channel 11 (2462 MHz) 204 * ACS: 1: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=161 busy=0 rx=0 205 * ACS: 2: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=161 busy=0 rx=0 206 * ACS: 3: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=161 busy=0 rx=0 207 * ACS: 4: min_nf=-114 interference_factor=0.0432099 nf=-114 time=162 busy=0 rx=7 208 * ACS: 5: min_nf=-114 interference_factor=0.0925926 nf=-114 time=162 busy=0 rx=15 209 * ACS: * interference factor average: 0.0271605 210 * ACS: Survey analysis for channel 12 (2467 MHz) 211 * ACS: 1: min_nf=-114 interference_factor=0.0621118 nf=-113 time=161 busy=0 rx=10 212 * ACS: 2: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1 213 * ACS: 3: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=162 busy=0 rx=0 214 * ACS: 4: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=162 busy=0 rx=0 215 * ACS: 5: min_nf=-114 interference_factor=0.00617284 nf=-113 time=162 busy=0 rx=1 216 * ACS: * interference factor average: 0.0148992 217 * ACS: Survey analysis for channel 13 (2472 MHz) 218 * ACS: 1: min_nf=-114 interference_factor=0.0745342 nf=-114 time=161 busy=0 rx=12 219 * ACS: 2: min_nf=-114 interference_factor=0.0555556 nf=-114 time=162 busy=0 rx=9 220 * ACS: 3: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0 221 * ACS: 4: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0 222 * ACS: 5: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0 223 * ACS: * interference factor average: 0.0260179 224 * ACS: Survey analysis for selected bandwidth 20MHz 225 * ACS: * channel 1: total interference = 0.121432 226 * ACS: * channel 2: total interference = 0.137512 227 * ACS: * channel 3: total interference = 0.369757 228 * ACS: * channel 4: total interference = 0.546338 229 * ACS: * channel 5: total interference = 0.690538 230 * ACS: * channel 6: total interference = 0.762242 231 * ACS: * channel 7: total interference = 0.756092 232 * ACS: * channel 8: total interference = 0.537451 233 * ACS: * channel 9: total interference = 0.332313 234 * ACS: * channel 10: total interference = 0.152182 235 * ACS: * channel 11: total interference = 0.0916111 236 * ACS: * channel 12: total interference = 0.0816809 237 * ACS: * channel 13: total interference = 0.0680776 238 * ACS: Ideal channel is 13 (2472 MHz) with total interference factor of 0.0680776 239 * 240 * [1] http://en.wikipedia.org/wiki/Near_and_far_field 241 */ 242 243 244static int acs_request_scan(struct hostapd_iface *iface); 245 246 247static void acs_clean_chan_surveys(struct hostapd_channel_data *chan) 248{ 249 struct freq_survey *survey, *tmp; 250 251 if (dl_list_empty(&chan->survey_list)) 252 return; 253 254 dl_list_for_each_safe(survey, tmp, &chan->survey_list, 255 struct freq_survey, list) { 256 dl_list_del(&survey->list); 257 os_free(survey); 258 } 259} 260 261 262static void acs_cleanup(struct hostapd_iface *iface) 263{ 264 int i; 265 struct hostapd_channel_data *chan; 266 267 for (i = 0; i < iface->current_mode->num_channels; i++) { 268 chan = &iface->current_mode->channels[i]; 269 270 if (chan->flag & HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED) 271 acs_clean_chan_surveys(chan); 272 273 dl_list_init(&chan->survey_list); 274 chan->flag |= HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED; 275 chan->min_nf = 0; 276 } 277 278 iface->chans_surveyed = 0; 279 iface->acs_num_completed_scans = 0; 280} 281 282 283void acs_fail(struct hostapd_iface *iface) 284{ 285 wpa_printf(MSG_ERROR, "ACS: Failed to start"); 286 acs_cleanup(iface); 287} 288 289 290static long double 291acs_survey_interference_factor(struct freq_survey *survey, s8 min_nf) 292{ 293 long double factor, busy, total; 294 295 if (survey->filled & SURVEY_HAS_CHAN_TIME_BUSY) 296 busy = survey->channel_time_busy; 297 else if (survey->filled & SURVEY_HAS_CHAN_TIME_RX) 298 busy = survey->channel_time_rx; 299 else { 300 /* This shouldn't really happen as survey data is checked in 301 * acs_sanity_check() */ 302 wpa_printf(MSG_ERROR, "ACS: Survey data missing"); 303 return 0; 304 } 305 306 total = survey->channel_time; 307 308 if (survey->filled & SURVEY_HAS_CHAN_TIME_TX) { 309 busy -= survey->channel_time_tx; 310 total -= survey->channel_time_tx; 311 } 312 313 /* TODO: figure out the best multiplier for noise floor base */ 314 factor = pow(10, survey->nf / 5.0L) + 315 (busy / total) * 316 pow(2, pow(10, (long double) survey->nf / 10.0L) - 317 pow(10, (long double) min_nf / 10.0L)); 318 319 return factor; 320} 321 322 323static void 324acs_survey_chan_interference_factor(struct hostapd_iface *iface, 325 struct hostapd_channel_data *chan) 326{ 327 struct freq_survey *survey; 328 unsigned int i = 0; 329 long double int_factor = 0; 330 331 if (dl_list_empty(&chan->survey_list)) 332 return; 333 334 if (chan->flag & HOSTAPD_CHAN_DISABLED) 335 return; 336 337 chan->interference_factor = 0; 338 339 dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list) 340 { 341 int_factor = acs_survey_interference_factor(survey, 342 iface->lowest_nf); 343 chan->interference_factor += int_factor; 344 wpa_printf(MSG_DEBUG, "ACS: %d: min_nf=%d interference_factor=%Lg nf=%d time=%lu busy=%lu rx=%lu", 345 ++i, chan->min_nf, int_factor, 346 survey->nf, (unsigned long) survey->channel_time, 347 (unsigned long) survey->channel_time_busy, 348 (unsigned long) survey->channel_time_rx); 349 } 350 351 chan->interference_factor = chan->interference_factor / 352 dl_list_len(&chan->survey_list); 353} 354 355 356static int acs_usable_ht40_chan(struct hostapd_channel_data *chan) 357{ 358 const int allowed[] = { 36, 44, 52, 60, 100, 108, 116, 124, 132, 149, 359 157, 184, 192 }; 360 unsigned int i; 361 362 for (i = 0; i < ARRAY_SIZE(allowed); i++) 363 if (chan->chan == allowed[i]) 364 return 1; 365 366 return 0; 367} 368 369 370static int acs_survey_is_sufficient(struct freq_survey *survey) 371{ 372 if (!(survey->filled & SURVEY_HAS_NF)) { 373 wpa_printf(MSG_ERROR, "ACS: Survey is missing noise floor"); 374 return 0; 375 } 376 377 if (!(survey->filled & SURVEY_HAS_CHAN_TIME)) { 378 wpa_printf(MSG_ERROR, "ACS: Survey is missing channel time"); 379 return 0; 380 } 381 382 if (!(survey->filled & SURVEY_HAS_CHAN_TIME_BUSY) && 383 !(survey->filled & SURVEY_HAS_CHAN_TIME_RX)) { 384 wpa_printf(MSG_ERROR, "ACS: Survey is missing RX and busy time (at least one is required)"); 385 return 0; 386 } 387 388 return 1; 389} 390 391 392static int acs_survey_list_is_sufficient(struct hostapd_channel_data *chan) 393{ 394 struct freq_survey *survey; 395 396 dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list) 397 { 398 if (!acs_survey_is_sufficient(survey)) { 399 wpa_printf(MSG_ERROR, "ACS: Channel %d has insufficient survey data", 400 chan->chan); 401 return 0; 402 } 403 } 404 405 return 1; 406 407} 408 409 410static int acs_surveys_are_sufficient(struct hostapd_iface *iface) 411{ 412 int i; 413 struct hostapd_channel_data *chan; 414 int valid = 0; 415 416 for (i = 0; i < iface->current_mode->num_channels; i++) { 417 chan = &iface->current_mode->channels[i]; 418 if (chan->flag & HOSTAPD_CHAN_DISABLED) 419 continue; 420 421 if (!acs_survey_list_is_sufficient(chan)) 422 continue; 423 424 valid++; 425 } 426 427 /* We need at least survey data for one channel */ 428 return !!valid; 429} 430 431 432static int acs_usable_chan(struct hostapd_channel_data *chan) 433{ 434 if (dl_list_empty(&chan->survey_list)) 435 return 0; 436 if (chan->flag & HOSTAPD_CHAN_DISABLED) 437 return 0; 438 if (!acs_survey_list_is_sufficient(chan)) 439 return 0; 440 return 1; 441} 442 443 444static void acs_survey_all_chans_intereference_factor( 445 struct hostapd_iface *iface) 446{ 447 int i; 448 struct hostapd_channel_data *chan; 449 450 for (i = 0; i < iface->current_mode->num_channels; i++) { 451 chan = &iface->current_mode->channels[i]; 452 453 if (!acs_usable_chan(chan)) 454 continue; 455 456 wpa_printf(MSG_DEBUG, "ACS: Survey analysis for channel %d (%d MHz)", 457 chan->chan, chan->freq); 458 459 acs_survey_chan_interference_factor(iface, chan); 460 461 wpa_printf(MSG_DEBUG, "ACS: * interference factor average: %Lg", 462 chan->interference_factor); 463 } 464} 465 466 467static struct hostapd_channel_data *acs_find_chan(struct hostapd_iface *iface, 468 int freq) 469{ 470 struct hostapd_channel_data *chan; 471 int i; 472 473 for (i = 0; i < iface->current_mode->num_channels; i++) { 474 chan = &iface->current_mode->channels[i]; 475 476 if (chan->flag & HOSTAPD_CHAN_DISABLED) 477 continue; 478 479 if (chan->freq == freq) 480 return chan; 481 } 482 483 return NULL; 484} 485 486 487/* 488 * At this point it's assumed chan->interface_factor has been computed. 489 * This function should be reusable regardless of interference computation 490 * option (survey, BSS, spectral, ...). chan->interference factor must be 491 * summable (i.e., must be always greater than zero). 492 */ 493static struct hostapd_channel_data * 494acs_find_ideal_chan(struct hostapd_iface *iface) 495{ 496 struct hostapd_channel_data *chan, *adj_chan, *ideal_chan = NULL, 497 *rand_chan = NULL; 498 long double factor, ideal_factor = 0; 499 int i, j; 500 int n_chans = 1; 501 502 /* TODO: HT40- support */ 503 504 if (iface->conf->ieee80211n && 505 iface->conf->secondary_channel == -1) { 506 wpa_printf(MSG_ERROR, "ACS: HT40- is not supported yet. Please try HT40+"); 507 return NULL; 508 } 509 510 if (iface->conf->ieee80211n && 511 iface->conf->secondary_channel) 512 n_chans = 2; 513 514 if (iface->conf->ieee80211ac && 515 iface->conf->vht_oper_chwidth == 1) 516 n_chans = 4; 517 518 /* TODO: VHT80+80, VHT160. Update acs_adjust_vht_center_freq() too. */ 519 520 wpa_printf(MSG_DEBUG, "ACS: Survey analysis for selected bandwidth %d MHz", 521 n_chans == 1 ? 20 : 522 n_chans == 2 ? 40 : 523 n_chans == 4 ? 80 : 524 -1); 525 526 for (i = 0; i < iface->current_mode->num_channels; i++) { 527 chan = &iface->current_mode->channels[i]; 528 529 if (chan->flag & HOSTAPD_CHAN_DISABLED) 530 continue; 531 532 533 /* HT40 on 5 GHz has a limited set of primary channels as per 534 * 11n Annex J */ 535 if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A && 536 iface->conf->ieee80211n && 537 iface->conf->secondary_channel && 538 !acs_usable_ht40_chan(chan)) { 539 wpa_printf(MSG_DEBUG, "ACS: Channel %d: not allowed as primary channel for HT40", 540 chan->chan); 541 continue; 542 } 543 544 factor = 0; 545 if (acs_usable_chan(chan)) 546 factor = chan->interference_factor; 547 548 for (j = 1; j < n_chans; j++) { 549 adj_chan = acs_find_chan(iface, chan->freq + (j * 20)); 550 if (!adj_chan) 551 break; 552 553 if (acs_usable_chan(adj_chan)) 554 factor += adj_chan->interference_factor; 555 } 556 557 if (j != n_chans) { 558 wpa_printf(MSG_DEBUG, "ACS: Channel %d: not enough bandwidth", 559 chan->chan); 560 continue; 561 } 562 563 /* 2.4 GHz has overlapping 20 MHz channels. Include adjacent 564 * channel interference factor. */ 565 if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211B || 566 iface->current_mode->mode == HOSTAPD_MODE_IEEE80211G) { 567 for (j = 0; j < n_chans; j++) { 568 /* TODO: perhaps a multiplier should be used 569 * here? */ 570 571 adj_chan = acs_find_chan(iface, chan->freq + 572 (j * 20) - 5); 573 if (adj_chan && acs_usable_chan(adj_chan)) 574 factor += adj_chan->interference_factor; 575 576 adj_chan = acs_find_chan(iface, chan->freq + 577 (j * 20) - 10); 578 if (adj_chan && acs_usable_chan(adj_chan)) 579 factor += adj_chan->interference_factor; 580 581 adj_chan = acs_find_chan(iface, chan->freq + 582 (j * 20) + 5); 583 if (adj_chan && acs_usable_chan(adj_chan)) 584 factor += adj_chan->interference_factor; 585 586 adj_chan = acs_find_chan(iface, chan->freq + 587 (j * 20) + 10); 588 if (adj_chan && acs_usable_chan(adj_chan)) 589 factor += adj_chan->interference_factor; 590 } 591 } 592 593 wpa_printf(MSG_DEBUG, "ACS: * channel %d: total interference = %Lg", 594 chan->chan, factor); 595 596 if (acs_usable_chan(chan) && 597 (!ideal_chan || factor < ideal_factor)) { 598 ideal_factor = factor; 599 ideal_chan = chan; 600 } 601 602 /* This channel would at least be usable */ 603 if (!rand_chan) 604 rand_chan = chan; 605 } 606 607 if (ideal_chan) { 608 wpa_printf(MSG_DEBUG, "ACS: Ideal channel is %d (%d MHz) with total interference factor of %Lg", 609 ideal_chan->chan, ideal_chan->freq, ideal_factor); 610 return ideal_chan; 611 } 612 613 return rand_chan; 614} 615 616 617static void acs_adjust_vht_center_freq(struct hostapd_iface *iface) 618{ 619 wpa_printf(MSG_DEBUG, "ACS: Adjusting VHT center frequency"); 620 621 switch (iface->conf->vht_oper_chwidth) { 622 case VHT_CHANWIDTH_USE_HT: 623 iface->conf->vht_oper_centr_freq_seg0_idx = 624 iface->conf->channel + 2; 625 break; 626 case VHT_CHANWIDTH_80MHZ: 627 iface->conf->vht_oper_centr_freq_seg0_idx = 628 iface->conf->channel + 6; 629 break; 630 default: 631 /* TODO: How can this be calculated? Adjust 632 * acs_find_ideal_chan() */ 633 wpa_printf(MSG_INFO, "ACS: Only VHT20/40/80 is supported now"); 634 break; 635 } 636} 637 638 639static int acs_study_survey_based(struct hostapd_iface *iface) 640{ 641 wpa_printf(MSG_DEBUG, "ACS: Trying survey-based ACS"); 642 643 if (!iface->chans_surveyed) { 644 wpa_printf(MSG_ERROR, "ACS: Unable to collect survey data"); 645 return -1; 646 } 647 648 if (!acs_surveys_are_sufficient(iface)) { 649 wpa_printf(MSG_ERROR, "ACS: Surveys have insufficient data"); 650 return -1; 651 } 652 653 acs_survey_all_chans_intereference_factor(iface); 654 return 0; 655} 656 657 658static int acs_study_options(struct hostapd_iface *iface) 659{ 660 int err; 661 662 err = acs_study_survey_based(iface); 663 if (err == 0) 664 return 0; 665 666 /* TODO: If no surveys are available/sufficient this is a good 667 * place to fallback to BSS-based ACS */ 668 669 return -1; 670} 671 672 673static void acs_study(struct hostapd_iface *iface) 674{ 675 struct hostapd_channel_data *ideal_chan; 676 int err; 677 678 err = acs_study_options(iface); 679 if (err < 0) { 680 wpa_printf(MSG_ERROR, "ACS: All study options have failed"); 681 goto fail; 682 } 683 684 ideal_chan = acs_find_ideal_chan(iface); 685 if (!ideal_chan) { 686 wpa_printf(MSG_ERROR, "ACS: Failed to compute ideal channel"); 687 err = -1; 688 goto fail; 689 } 690 691 iface->conf->channel = ideal_chan->chan; 692 693 if (iface->conf->ieee80211ac) 694 acs_adjust_vht_center_freq(iface); 695 696 err = 0; 697fail: 698 /* 699 * hostapd_setup_interface_complete() will return -1 on failure, 700 * 0 on success and 0 is HOSTAPD_CHAN_VALID :) 701 */ 702 if (hostapd_acs_completed(iface, err) == HOSTAPD_CHAN_VALID) { 703 acs_cleanup(iface); 704 return; 705 } 706 707 /* This can possibly happen if channel parameters (secondary 708 * channel, center frequencies) are misconfigured */ 709 wpa_printf(MSG_ERROR, "ACS: Possibly channel configuration is invalid, please report this along with your config file."); 710 acs_fail(iface); 711} 712 713 714static void acs_scan_complete(struct hostapd_iface *iface) 715{ 716 int err; 717 718 iface->scan_cb = NULL; 719 720 wpa_printf(MSG_DEBUG, "ACS: Using survey based algorithm (acs_num_scans=%d)", 721 iface->conf->acs_num_scans); 722 723 err = hostapd_drv_get_survey(iface->bss[0], 0); 724 if (err) { 725 wpa_printf(MSG_ERROR, "ACS: Failed to get survey data"); 726 acs_fail(iface); 727 } 728 729 if (++iface->acs_num_completed_scans < iface->conf->acs_num_scans) { 730 err = acs_request_scan(iface); 731 if (err) { 732 wpa_printf(MSG_ERROR, "ACS: Failed to request scan"); 733 goto fail; 734 } 735 736 return; 737 } 738 739 acs_study(iface); 740 return; 741fail: 742 hostapd_acs_completed(iface, 1); 743 acs_fail(iface); 744} 745 746 747static int acs_request_scan(struct hostapd_iface *iface) 748{ 749 struct wpa_driver_scan_params params; 750 struct hostapd_channel_data *chan; 751 int i, *freq; 752 753 os_memset(¶ms, 0, sizeof(params)); 754 params.freqs = os_calloc(iface->current_mode->num_channels + 1, 755 sizeof(params.freqs[0])); 756 if (params.freqs == NULL) 757 return -1; 758 759 freq = params.freqs; 760 for (i = 0; i < iface->current_mode->num_channels; i++) { 761 chan = &iface->current_mode->channels[i]; 762 if (chan->flag & HOSTAPD_CHAN_DISABLED) 763 continue; 764 765 *freq++ = chan->freq; 766 } 767 *freq = 0; 768 769 iface->scan_cb = acs_scan_complete; 770 771 wpa_printf(MSG_DEBUG, "ACS: Scanning %d / %d", 772 iface->acs_num_completed_scans + 1, 773 iface->conf->acs_num_scans); 774 775 if (hostapd_driver_scan(iface->bss[0], ¶ms) < 0) { 776 wpa_printf(MSG_ERROR, "ACS: Failed to request initial scan"); 777 acs_cleanup(iface); 778 return -1; 779 } 780 781 os_free(params.freqs); 782 return 0; 783} 784 785 786enum hostapd_chan_status acs_init(struct hostapd_iface *iface) 787{ 788 int err; 789 790 wpa_printf(MSG_INFO, "ACS: Automatic channel selection started, this may take a bit"); 791 792 acs_cleanup(iface); 793 794 err = acs_request_scan(iface); 795 if (err < 0) 796 return HOSTAPD_CHAN_INVALID; 797 798 hostapd_set_state(iface, HAPD_IFACE_ACS); 799 wpa_msg(iface->bss[0]->msg_ctx, MSG_INFO, ACS_EVENT_STARTED); 800 801 return HOSTAPD_CHAN_ACS; 802} 803