WiFi的2.4G、5G、6G频段

目前WiFi已经推出了6G频段,Android源码中也增加了相关的功能，这里总结一下。

2.4G一共分为14个信道（1-14），从2412到2484，每个信道的有效宽度是 20MHz，另外还有2MHz的强制隔离频带（类似于公路上的隔离带）。即，对于中心频率为 2412 MHz 的1信道，其频率范围为2401~2423MHz。

5G一共有60个信道（32-173），从5160到5865，在中国支持的5G信道为36 38 40 44 46 48 52 54 56 60 62 64，后六个是DFS。

6G为1-233，从5946到7105。大概为1.2GHz的总带宽，可以分成15个80MHz的频谱。

Android源码中对2.4g、5g、6g的定义：
ScanResult.java

public static final int BAND_24_GHZ_FIRST_CH_NUM = 1;
/**
 * 2.4 GHz band last channel number
 * @hide
 */
public static final int BAND_24_GHZ_LAST_CH_NUM = 14;
/**
 * 2.4 GHz band frequency of first channel in MHz
 * @hide
 */
public static final int BAND_24_GHZ_START_FREQ_MHZ = 2412;
/**
 * 2.4 GHz band frequency of last channel in MHz
 * @hide
 */
public static final int BAND_24_GHZ_END_FREQ_MHZ = 2484;

/**
 * 5 GHz band first channel number
 * @hide
 */
public static final int BAND_5_GHZ_FIRST_CH_NUM = 32;
/**
 * 5 GHz band last channel number
 * @hide
 */
public static final int BAND_5_GHZ_LAST_CH_NUM = 173;
/**
 * 5 GHz band frequency of first channel in MHz
 * @hide
 */
public static final int BAND_5_GHZ_START_FREQ_MHZ = 5160;
/**
 * 5 GHz band frequency of last channel in MHz
 * @hide
 */
public static final int BAND_5_GHZ_END_FREQ_MHZ = 5865;

/**
 * 6 GHz band first channel number
 * @hide
 */
public static final int BAND_6_GHZ_FIRST_CH_NUM = 1;
/**
 * 6 GHz band last channel number
 * @hide
 */
public static final int BAND_6_GHZ_LAST_CH_NUM = 233;
/**
 * 6 GHz band frequency of first channel in MHz
 * @hide
 */
public static final int BAND_6_GHZ_START_FREQ_MHZ = 5945;
/**
 * 6 GHz band frequency of last channel in MHz
 * @hide
 */
public static final int BAND_6_GHZ_END_FREQ_MHZ = 7105;