iPhone如何在使用它们进行位置估算时学习新的WiFi位置 [英] How does the iPhone learn new WiFi locations in terms of using them for location estimates
问题描述
我知道iPhone可以并且确实使用WiFi邻近度来获取大致位置。这显然只有当天空中的某个数据库知道该WiFi热点的大概位置时才会发生。我的问题是热点如何进入该数据库？当iPhone具有相当准确的GPS位置并检测到WiFi或者是否存在一些手动或程序化的添加热点的方式时，它是否会自动添加？ 解决方案
苹果自iOS 3.2以来使用自己的数据库（之前他们使用Skyhook Wireless）。这可以通过使用支持GPS的iOS设备向Apple发送WiFi MAC地址来实现。因此，如果设备具有GPS定位功能，它会自动将所见到的所有WiFi MAC地址与GPS检测到的位置一起发送给Apple。除了主核心位置开关之外，没有其他选项可以更改此行为。用户必须接受EULA中已发现的WiFi MAC地址的传输。
通过WiFi的位置检测以相反的方式发送所有可见的WiFi MAC地址给Apple，与位置。实际上，他们通过在手机上缓存尽可能多的WiFi地址来大量优化这一点。因此，这甚至可以在iPod touch上运行（在某种程度上），而无需任何网络连接。
这个算法的一个弱点是MiFi和类似设备（重新定位WiFi热点）。目前，Core Location在丢弃明显错误的WiFi位置方面做得不是很好。例如，在没有GPS接收功能的室内贸易展会上，由于有许多MiFi设备，准备获取错误的位置更新。
要回答您关于手动添加WiFi热点：不，没有办法做到这一点。只需使用运行iOS 3.2或更高版本的支持GPS的iPhone / iPad，MAC地址最终将进入数据库。根据我的经验，这很快发生。
I know the iPhone can and does use WiFi proximity to get approximate location. This obviously only can occur when some database in the sky knows the approximate location of that WiFi hotspot. My question is how do hotspots get into that db? Is it automatically added whenever the iPhone has a reasonably accurate GPS position and detects the WiFi or is there some manual or programatic way of adding hotspots?
Apple uses their own database since iOS 3.2 (prior to that they used Skyhook Wireless). This works by sending WiFi MAC addresses to Apple by GPS-enabled iOS devices. So if the device has a GPS fix, it automatically sends all WiFi MAC addresses it sees alongside with the GPS-detected location to Apple. There's no option to change this behavior except the master Core Location switch. Users have to accept this transmission of seen WiFi MAC addresses in the EULA.
Location detection via WiFi works the opposite way by sending all seen WiFi MAC addresses to Apple and they respond with the location. Actually they heavily optimize this by caching as many WiFi addresses on the phone as possible. So this even works (to some degree) on iPod touch without any network connectivity.
A weak spot of this algorithm are MiFi and similar devices (relocating WiFi hotspots). Currently, Core Location does not do a very good job of discarding obviously wrong WiFi locations. For instance, on indoor trade shows without GPS reception, be prepared to get wrong location updates because of the many MiFi devices out there.
To respond to your question about manually adding WiFi hotspots: no, there's no way to do that. Just use a GPS enabled iPhone/iPad running iOS 3.2 or higher and the MAC address will make its way into the database eventually. In my experience, this happens rather quickly.
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