New iPod Touch Hides an 802.11n Wi-Fi Chip

The new Apple iPod Touch uses a Wi-Fi chip that can support the just-approved high-throughput 802.11n standard, though Apple apparently has not switched on the cranked-up wireless link.

If it does, the iPod Touch (which is almost identical to the iPhone but lacks the 3G cellular radio) could support a 50Mbps data rate, more than twice that of the current 802.11ag radios used by the product family.

Apple this week lowered the price for the original 8GB iPod Touch and introduced two new higher-priced models, with 32 and 64Gbytes of memory respectively.

The chip inside is the Broadcom BCM4329, announced last December, the first Broadcom 11n product designed for mobile devices. The single chip combines 802.11n with 802.11abg, Bluetooth, and FM radio. It runs in both the 2.4 GHz and 5 GHz bands. Full details are in the company's data sheet for the chip.

The chip was discovered during a step-by-step disassembly of a brand-new 32GB iPod Touch by iFixit, a Web site founded in 2003 by a pair of Cal Poly tinkerers, to help other people tinker with their electronics.

They discovered the Broadcom chip at step 14. An enlarged image shows the Broadcom name and chip identification.

The chip reflects the range of implementations available to chip and equipment vendors. The 802.11n technology exploits multiple-input multiple-output – splitting a high-rate data stream into, today, two slower streams, each sent from and to a corresponding pair of antennas. It creates a kind of parallel transceiving capability, which dramatically multiplies 11n's capacity.

But the BCM4329 uses only one 11n data stream with one antenna, compared to the 11n radios in most laptops, which use two. With the other 11n technologies, that means the Broadcom chip maxes out at "just" 50Mbps.

Wi-Fi becomes a big drain on mobile batteries. Broadcom used a range of technologies to minimize power demand by reducing power consumption when active, and when idle.

The chip supports Bluetooth data rates from 1Mbps to 3Mbps, based on the Bluetooth 2.1 specification with Enhanced Data Rate. A set of Broadcom algorithms let the Wi-Fi and Bluetooth radios operate at the same time in the 2.4-GHz band without interfering with each other, and to use a common antenna system.

Apple has been aggressively deploying 11n in its desktop products for two years. Will it be as aggressive in bringing high-throughput Wi-Fi to its mobile products?