Both AT&T and Verizon Wireless charge $20 per month to use Personal Hotspot, and AT&T requires a certain level of metered service. In brief, make sure you’ve signed up for the feature with your carrier. 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. Over Bluetooth, you’ll cap your highest potential, as Wi-Fi can carry more than 30 Mbps between two devices. 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. That’s fine on Verizon’s 3G network, where average speeds never top 2 Mbps.
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. What’s the biggest downside to Bluetooth tethering? Throughput. Then you put your iPhone away, and your iPad should connect to the iPhone’s mobile hotspot with no prompting. 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.
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. This adds a step to using Personal Hotspot when you’re using it during a commute, for instance. 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.
After 90 seconds with no connections, your phone’s Wi-Fi radio turns off sharing to reduce battery usage. 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. What you’ll like best, though, is that using Bluetooth tethering sidesteps a major inconvenience with the Personal Hotspot feature.
You can also likely save battery power on both the iPhone acting as a hotspot and the device or devices you to tether to it: Bluetooth should consume less power than Wi-Fi, even though modern Wi-Fi has a lot of built-in power-conserving features. The key advantage of Bluetooth tethering is simplicity, especially with a streamlined pairing process for securely connecting two devices over Bluetooth that Apple added to the iOS with the 4.3 update. On an iPhone 3GS with iOS 4.3 installed, it’s labeled Personal Hotspot, though Wi-Fi isn’t available as an option.) (If either phone has iOS 4.0 to 4.2 installed, the sharing option appears as Internet Tethering. For iPhone 3G and 3GS users, this form of tethering also allows other iOS devices to share a connection, which was previously impossible.