The world is a-buzz with the release of the new iPhone 5. I’m sure everyone has heard by now that it supports 5GHz Wi-Fi. This expanded frequency band support will be of critical importance for enterprise Wi-Fi networks adopting mobile devices and BYOD initiatives to distribute the growing network load among multiple APs on different channels for increased capacity and performance.
So, let’s dig into the new iPhone 5 and discover all the new Wi-Fi capabilities that it has in store for us!
The U.S. iPhone 5 uses a model numbers of A1428 and A1429, and an FCC ID of BCG-E2599A. Looking up the device in the FCC OET Equipment Authorization database gives us the following information.
Note – the Canadian IC is 579C-E2599A, the European CE Mark is CE0682, and the ANZA is N122 Z844.
The chipset used is the Broadcom BCM4334. This is the chip that I originally speculated might be included in the new iPad (3rd gen) but was not. Broadcom product literature on this chip includes very "Apple-esque" verbiage around highly mobile devices and push-email. This is an intriguing choice since the chip offers single-stream 802.11n, dual-band operation, and 40MHz wide channels. Broadcom also lists concurrent dual-band capability for Wi-Fi client access on one band while simultaneously using Wi-Fi Direct or Wireless Display on the other band using what they call "advanced switching techniques."
We can gather from the chipset and FCC test reports the following information:
- 1x1:1 MIMO (1 Spatial Stream)
- 40 MHz wide channels (in the 5 GHz bands only)
- 150 Mbps max data rate
- Bluetooth 4.0 (supports switching to Wi-Fi for bulk data transfer)
- Supports optional 11n features, including STBC (space-time block coding) and LDPC (low-density parity check) for improved range and reliability
- Ultra-low power draw
The antenna gain is fairly typical for a mobile device (very low; actually antenna loss in 4 of the 5 frequency bands) due to the use of PIFA antennas, which take up little space inside the phone:
The use of only 1 antenna chain is understandable for power conservation and battery life concerns, since additional antenna chains would consume more power and impacts the user experience. Unfortunately, this also means that the device will still be susceptible to multipath and null fading. So the occasional packet loss and application latency may still be observed.
Frequency Band Support and Power Output
We know it supports 5GHz in general, but there are technically 5 different 5GHz frequency bands, and not all devices support them all. So, it’s important to know which channels it does support so you can properly design your network to avoid placing APs on channels the iPhone can’t communicate on and introducing coverage gaps in your network.
Frequency bands supported:
• 2.4 GHz ISM (Channels 1 – 11), Power Output ~16dBm
• 5 GHz UNII-1 (Channels 36 – 48), Power Output ~14dBm
• 5 GHz UNII-2 (Channels 52 – 64), Power Output ~13.5dBm
• 5 GHz UNII-2Ext. (Channels 100 – 140), Power Output ~12dBm
• 5 GHz UNII-3 (Channels 149 – 161), Power Output ~13dBm
• 5 GHz ISM (Channel 165), Power Output ~13dBm
So, it supports a total of 24 non-overlapping 20MHz channels, and 9 non-overlapping 40MHz channels. Note that 3 channels are disabled (ch 120-128) in the 5 GHz UNII-2Ext. range because they are disallowed for operation in the U.S. by the FCC DFS regulations due to Terminal Doppler Weather Radar (TDWR) systems.
And once again, we see the DFS Attestation Letter submitted by Apple to the FCC, which allows client devices to use DFS bands without having to be certified for radar detection and avoidance because it does not initiate transmission (e.g. does not probe), but relies on an AP to do so and will connect if one is found through passive scanning (listening to AP beacons).
TCP throughput should be around ~80 Mbps TCP and ~110 Mbps UDP. Quite a bit more than previous generation iPhones, which peaked around ~40 Mbps TCP.
The iPhone 5 is capable of achieving much higher bandwidth and the inclusion of 5GHz support will enable much better performance in high-density and enterprise environments with BYOD initiatives. These enhancements are a welcome addition for Wi-Fi network administrators everywhere!
Now here’s to hoping the next generation iPhone and iPad will find a way to support multiple antenna chains for better signal reception using MRC and resistance to multipath and null fading! You always need to have a wish list, right?!
Andrew von Nagy