WLAN
- WPS：Wi-Fi Protected Setup；
- Most modern WLANs are based on IEEE 802.11 standards and are marketed under the Wi-Fi brand name.
- Wi-Fi 4 (802.11n), Wi-Fi 5 (802.11ac) and Wi-Fi 6 / Wi-Fi 6E (802.11ax 10G).
- Wi-Fi 7 (802.11be 30G) 2022 联发科 MediaTek Filogic。
- RouterCtrl：help regular internet users with every network and network equipment issue。
Wi-Fi Education
BLE：Bluetooth Low Energy
- Introduction to GATT: Generic ATTribute Profile. 知乎。
- Services, characteristics, and descriptors are collectively referred to as attributes, and identified by UUIDs：128 bit，通常标识为 16 bit（2个字节），Allocated UUID、Bluetooth Assigned Numbers。例如：
0x1131 Headset - HS，0x1112 Headset - Audio Gateway (AG)，0x1131和0x1112就是为 Headset Profile两个角色HS和AG分配的UUID。 - List of Bluetooth profiles.
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HSP @bluetooth.com: Headset Profile 1.2，2008年。
AT command set、及其 External links。 -
HRP: Heart Rate Profile 1.0，2011年。
All transactions are started by the main device(Central role), the GATT Client, which receives response from the secondary device(Peripheral role), the GATT Server.
Profile, Services and Characteristics
Heart Rate Profile 1.0 - Heart Rate Service Characteristic Discovery:
1、Heart Rate Measurement Characteristic (shall)
2、Body Sensor Location Characteristic (may)
3、Heart Rate Control Point Characteristic (may)
SmartPhone
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IMEI：International Mobile Equipment Identity。在 这里 可以查一下手机终端的型号参数，还挺准。
15位：8位TAC+6位序列号+1位校验码，例如：356709086591456。iPhone 8 plus 实现 Bluetooth 5.0。 - MEID 和 IMEI 类似。手机拨号键入
*#06#即可显示。 - ICCID：SIM 卡号。比如：89860316xx010yyyyyy0。共20位：89产业代码，8603 表中国电信，16表年份，010表地区，0校验码。
- 流畅性/卡顿：在用户有操作的前提下平均掉帧率。只有在某一时刻发生的掉帧（跳帧）情况远远大于其他时刻，那么才界定为卡顿。界面的掉帧程度更直观的反映出卡顿。帧率 FPS (每秒显示帧数)。12 FPS 连贯，一般电影 25 ~ 30FPS，游戏画面体验 60FPS。首先反映的是播放的稳定性。
- DROP LEVEL：frozen high middle normal best.
WLAN
WLAN 工作在 OSI 的层一和层二，即 Physical layer （PHY）and Data Link layer（MAC & LLC）。如果你熟悉 wired network，如 Ethernet，对照了解即可。
A wireless local area network (WLAN) is a wireless computer network that links two or more devices using a wireless distribution method (often spread-spectrum or OFDM radio) within a limited area such as a home, school, computer laboratory, or office building.
Wi-Fi
简单地说，Wi-Fi 是 WLAN 的一个具体实现技术，基于 802.11 标准，致力于业界产品互操作性的测试和认证，Wi-Fi 商标由 Wi-Fi 联盟拥有。追溯起来，Wi-Fi 不是什么缩写，就是选出的一个 名字。
Wi-Fi is a trademark of Wi-Fi Alliance. It is actually not a standard and only ensures that products using this trademark can interoperate with each other. As most Wi-Fi products use the IEEE 802.11b standard, Wi-Fi usually refers to 802.11b. Wi-Fi is a new technology that uses the WLAN protocol.
Wi-Fi can provide wireless coverage in an area with a radius of up to 90 m (300 inches), while the WLAN can provide wireless coverage in an area with a radius 5 km (with antennas used). The biggest advantage of Wi-Fi is its high transmission speed (up to 11 Mbit/s). Wi-Fi is a short-distance wireless transmission technology applicable to offices and households.
Hotspot (Wi-Fi)
A hotspot is a physical location where people may obtain Internet access, typically using Wi-Fi technology, via a wireless local area network (WLAN) using a router connected to an internet service provider.
- Apple OS 7 以上，通过 Personal Hotspot 可以对外共享 3G/4G 互联网连接，这是以软件实现的 Wi-Fi 热点（Software hotspots）。
Wi-Fi、Access Point and Hotspot
Wi-Fi is the technology. You build a wireless network based on the Wi-Fi specifications and principles.
An Access Point is a physical device which is used to offer Wi-Fi service to a small area.
A Hotspot is the area served by an access point.
So, you go to a hotspot so you can connect with an access point using Wi-Fi.
Hotspot is the where, access point is the what, Wi-Fi is the how.
Wi-Fi and Internet 示意
Residential gateway
简单的一个应用场景就是你家的家用网关，也能了解到不少知识。
