What you’ll like best, though, is that using Bluetooth tethering sidesteps a major inconvenience with the Personal Hotspot feature. When you turn on the feature on your iPhone, Wi-Fi sharing is only enabled for 90 seconds unless a device connects via Wi-Fi within that period. After 90 seconds with no connections, your phone’s Wi-Fi radio turns off sharing to reduce battery usage. The same is true if you have Wi-Fi devices connected, and then disconnect or power down all of them: a 90-second countdown ensues.
This adds a step to using Personal Hotspot when you’re using it during a commute, for instance. Instead of just pulling out your iPad, and waiting for it to connect, you have to first extract your iPhone, and navigate to the Personal Hotspot screen. Wi-Fi availability should automatically start up just by visiting that screen, although I found in testing that I sometimes had to tap the Personal Hotspot switch from On to Off and back to On again. Then you put your iPhone away, and your iPad should connect to the iPhone’s mobile hotspot with no prompting.
Bluetooth sharing, in contrast, is always available with Personal Hotspot. In the scenario above, you’d leave your iPhone stowed and simply wake your iPad. The tablet should connect automatically. If it does not, you navigate to Settings, go to General -> Bluetooth, and tap the iPhone hotspot in the list of Bluetooth devices. The iPad then connects.
Bluetooth offers a level of security that’s equivalent to the WPA2 flavor of Wi-Fi encryption required by Apple for the Personal Hotspot feature. However, with Bluetooth, all the security is handled for you automatically. The pairing process confirms that no other party intercepted a key exchange; after that, strong encryption is used automatically with no data entry.
What’s the biggest downside to Bluetooth tethering? Throughput. Bluetooth 2.1+EDR, the flavor built into all iOS devices, has a raw rate of 3 Mbps and a net throughput that’s just a bit over 2 Mbps. That’s fine on Verizon’s 3G network, where average speeds never top 2 Mbps. On AT&T’s network—and many other GSM networks worldwide—the HSPA 7.2 standards allow realistic average speeds of 1 to 4 Mbps. Over Bluetooth, you’ll cap your highest potential, as Wi-Fi can carry more than 30 Mbps between two devices.
Now, how would one set this up, I hear you ask? For setting up the Personal Hotspot, please consult our earlier coverage of that feature, which we linked to above. In brief, make sure you’ve signed up for the feature with your carrier. Both AT&T and Verizon Wireless charge $20 per month to use Personal Hotspot, and AT&T requires a certain level of metered service. (Carriers outside the U.S. may include the feature at no charge or require certain service levels or surcharges.) Then launch Settings on your iPhone, tap General -> Network -> Personal Hotspot, and tap the switch to On. (If you’ve already used Personal Hotspot, the menu item appears in the main level of the Settings app at the top.)
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