With the announcement of the iPhone 5, Apple released that not only data over the wireless network speed is (thanks 4G/LTE), but also Wi-Fi is much faster. Up to 150 Mbps! That has to do with the iPhone for the first dual-band Wi-Fi in the 5 GHz band support. It means that with the Wi-Fi 802.11n version both 2.4 GHz and 5 GHz have available for Wi-Fi. The advantage of this is that 5 GHz frequency band is less crowded, so there is less chance of interference. The 2.4 GHz band is used for many more applications, not only for Wi-Fi, but also for baby monitors, autoalarms, microwave ovens, cordless phones and Bluetooth.
Because of all these devices, all using the same 2.4 GHz freqentie use may cause interference. The Wi-Fi version is already on 802.11a 5 GHz, but is not much used. While the iPhone 4 and iPhone 4S all 802.11n support, they only use 2.4 GHz. The iPhone 4S is for example equipped with a Broadcom BCM4330 wireless chip, which also supports FM radio. It supports both bands, but only the 2.4 GHz band is enabled, the 5 GHz band and the FM radio is not used. When the iPhone 5 is going to change: it can both 2.4 and 5 GHz (but still not the FM radio, which potentially is present).
The 5 GHz band has another advantage: it has 23 channels that do not overlap. At 2.4 GZ there are only three non-overlapping channels. Even so there is less chance of interference at 5 GHz.
There are also disadvantages to the 5 GHz band: the wavelength is shorter, so the range is shorter. This can be solved with additional powerful aerials or a higher transmission power to be used (provided by the government is allowed). Far as we could ascertain in the Netherlands applies a maximum power of 100 mW. Another disadvantage is that the hand-over with multiple access points (APs) at 5 GHz is not as good as at 2.4 GHz. This is called perhaps to the fact that there are more channels to be scanned. The issue of selection is not only when you're moving, but when you sit still in one place. Defines the iPhone 5 will automatically decide which tire is most appropriate (which is the most obvious, but where you can ask to what extent the algorithm is optimized), or you can manually select it?
The promised speed of 150 Mbps, you will also not always get. It is dependent of the other devices on the same network which also consume data. In reality, you can be happy if you get 50 Mbps. This is evident from experience with devices like the Samsung Galaxy S III and HTC One X the dual band feature already support.
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