| /* |
| * Copyright 2019 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.server.wifi; |
| |
| import android.annotation.NonNull; |
| |
| import com.android.server.wifi.WifiCandidates.Candidate; |
| import com.android.server.wifi.WifiCandidates.ScoredCandidate; |
| import com.android.server.wifi.proto.WifiScoreCardProto; |
| import com.android.server.wifi.proto.WifiScoreCardProto.Event; |
| |
| import java.util.Collection; |
| |
| /** |
| * A candidate scorer that uses the scorecard to influence the choice. |
| */ |
| final class ScoreCardBasedScorer implements WifiCandidates.CandidateScorer { |
| |
| /** |
| * This should match WifiNetworkSelector.experimentIdFromIdentifier(getIdentifier()) |
| * when using the default ScoringParams. |
| */ |
| public static final int SCORE_CARD_BASED_SCORER_DEFAULT_EXPID = 42902385; |
| |
| private final ScoringParams mScoringParams; |
| |
| // config_wifi_framework_RSSI_SCORE_OFFSET |
| public static final int RSSI_SCORE_OFFSET = 85; |
| |
| // config_wifi_framework_RSSI_SCORE_SLOPE |
| public static final int RSSI_SCORE_SLOPE_IS_4 = 4; |
| |
| // config_wifi_framework_5GHz_preference_boost_factor |
| public static final int BAND_5GHZ_AWARD_IS_40 = 40; |
| |
| // config_wifiFramework6ghzPreferenceBoostFactor |
| public static final int BAND_6GHZ_AWARD_IS_40 = 40; |
| |
| // config_wifi_framework_SECURITY_AWARD |
| public static final int SECURITY_AWARD_IS_80 = 80; |
| |
| // config_wifi_framework_LAST_SELECTION_AWARD |
| public static final int LAST_SELECTION_AWARD_IS_480 = 480; |
| |
| // config_wifi_framework_current_network_boost |
| public static final int CURRENT_NETWORK_BOOST_IS_16 = 16; |
| |
| // config_wifi_framework_SAME_BSSID_AWARD |
| public static final int SAME_BSSID_AWARD_IS_24 = 24; |
| |
| // Only use scorecard id we have data from this many polls |
| public static final int MIN_POLLS_FOR_SIGNIFICANCE = 30; |
| |
| // Maximum allowable adjustment of the cutoff rssi (dB) |
| public static final int RSSI_RAIL = 5; |
| |
| private static final boolean USE_USER_CONNECT_CHOICE = true; |
| |
| ScoreCardBasedScorer(ScoringParams scoringParams) { |
| mScoringParams = scoringParams; |
| } |
| |
| @Override |
| public String getIdentifier() { |
| return "ScoreCardBasedScorer"; |
| } |
| |
| /** |
| * Calculates an individual candidate's score. |
| */ |
| private ScoredCandidate scoreCandidate(Candidate candidate) { |
| int rssiSaturationThreshold = mScoringParams.getGoodRssi(candidate.getFrequency()); |
| int rssi = Math.min(candidate.getScanRssi(), rssiSaturationThreshold); |
| int cutoff = estimatedCutoff(candidate); |
| int score = (rssi - cutoff) * RSSI_SCORE_SLOPE_IS_4; |
| |
| if (candidate.getFrequency() > ScoringParams.MINIMUM_6GHZ_BAND_FREQUENCY_IN_MEGAHERTZ) { |
| score += BAND_6GHZ_AWARD_IS_40; |
| } else if (candidate.getFrequency() |
| >= ScoringParams.MINIMUM_5GHZ_BAND_FREQUENCY_IN_MEGAHERTZ) { |
| score += BAND_5GHZ_AWARD_IS_40; |
| } |
| score += (int) (candidate.getLastSelectionWeight() * LAST_SELECTION_AWARD_IS_480); |
| |
| if (candidate.isCurrentNetwork()) { |
| score += CURRENT_NETWORK_BOOST_IS_16 + SAME_BSSID_AWARD_IS_24; |
| } |
| |
| if (!candidate.isOpenNetwork()) { |
| score += SECURITY_AWARD_IS_80; |
| } |
| |
| // To simulate the old strict priority rule, subtract a penalty based on |
| // which nominator added the candidate. |
| score -= 1000 * candidate.getNominatorId(); |
| |
| return new ScoredCandidate(score, 10, |
| USE_USER_CONNECT_CHOICE, candidate); |
| } |
| |
| private int estimatedCutoff(Candidate candidate) { |
| int cutoff = -RSSI_SCORE_OFFSET; |
| int lowest = cutoff - RSSI_RAIL; |
| int highest = cutoff + RSSI_RAIL; |
| WifiScoreCardProto.Signal signal = candidate.getEventStatistics(Event.SIGNAL_POLL); |
| if (signal == null) return cutoff; |
| if (!signal.hasRssi()) return cutoff; |
| if (signal.getRssi().getCount() > MIN_POLLS_FOR_SIGNIFICANCE) { |
| double mean = signal.getRssi().getSum() / signal.getRssi().getCount(); |
| double mean_square = signal.getRssi().getSumOfSquares() / signal.getRssi().getCount(); |
| double variance = mean_square - mean * mean; |
| double sigma = Math.sqrt(variance); |
| double value = mean - 2.0 * sigma; |
| cutoff = (int) Math.min(Math.max(value, lowest), highest); |
| } |
| return cutoff; |
| } |
| |
| @Override |
| public ScoredCandidate scoreCandidates(@NonNull Collection<Candidate> candidates) { |
| ScoredCandidate choice = ScoredCandidate.NONE; |
| for (Candidate candidate : candidates) { |
| ScoredCandidate scoredCandidate = scoreCandidate(candidate); |
| if (scoredCandidate.value > choice.value) { |
| choice = scoredCandidate; |
| } |
| } |
| // Here we just return the highest scored candidate; we could |
| // compute a new score, if desired. |
| return choice; |
| } |
| |
| } |