Editor’s Note: The following article is reprinted from Network World.
Apple seems to be laying the groundwork to introduce high-capacity, low-power 802.11n Wi-Fi to the iPod touch, and presumably to its 3G-enabled companion, the iPhone.
The change would be a huge jump in performance for users of both devices, which now use a Wi-Fi chip that supports 802.11b/g, with a throughput of less than 25Mbps on the 2.4GHz band. But the change would almost certainly mean having to buy a new touch or iPhone with the 11n chip, and some observers say Apple also needs to upgrade the CPU to enable both handhelds to fully exploit 11n performance.
Speculation about 11n support has been rife. But programmers sifting through the recently unveiled beta code of the iPhone 3.0 operating system uncovered some radio component specifications that show a shift to a different Broadcom Wi-Fi chip, the BCM4329, for a future iPod Touch model.
The 3.0 firmware is due to be released this summer, and speculation is circulating that it may coincide with new models of the iPhone 3G and iPod touch.
Announced last December, the highly integrated Broadcom chip combines a complete 802.11 a/b/g/n system (MAC/baseband/radio) with Bluetooth 2.1 + Enhanced Data Rate, and an FM radio receiver and transmitter. It supports both the 2.4GHz and 5GHz bands. (A detailed vendor spec sheet is available here.)
The dual-band support is important: It lets the device connect to existing Wi-Fi networks at their maximum 54Mbps data rate for 11g on 2.4GHz or 11a on 5GHz. But it also opens up the option of exploiting the much higher 11n data rate in the much less crowded 5GHz band. Wireless LANs based on Apple’s AirPort Extreme base station, and the AirPort Express portable unit, could be segmented to handle future 11n iPhone and touch clients on 5GHz, while keeping 11b/g devices on the 2.4GHz band.
Because the Broadcom chip is aimed at mobile devices, it supports only one data stream and one antenna, instead of the more conventional two or three streams, each with a corresponding antenna. So the chip’s throughput tops out at about 50Mbps, with a typical range of 30M to 50Mbps, according to Broadcom. Even so, that’s a big jump over what users can realize today with 11g and 11a.
One of the key design goals was to reduce power consumption. Broadcom used a number of techniques to cut the chip’s active and idle power consumption, minimizing the drain on the device’s battery. Depending on how well Broadcom has done that, the chip may take no more power to deliver twice the throughput, or possibly use even less.
The initial usefulness of mobile 11n may be somewhat limited, according to Glenn Fleishman, editor of Wi-Fi Net News. That’s because the existing iPhone (and other similar mobile devices) lack a CPU that can process that gush of data from a faster Wi-Fi connection, he wrote in March.
But single-stream 11n will let users quickly load or unload a ton of content, such as movie files, pictures, and video, a much better alternative than “having to fiddle with iTunes or sync software on a USB-connected computer,” according to Fleishman. Another benefit he noted: 11n acts as a high-capacity, direct conduit to Internet-based storage and processing, a link that’s likely to become increasingly important to mobile users.
Even now, Wi-Fi is widely and heavily used by iPhone customers. Last December, a survey by AdMob, the world’s biggest mobile ad network, found that more than 40 percent of recent U.S. traffic between iPhones and the network’s 6,000 ad partners passed over Wi-Fi connections, not over AT&T’s cellular network. That compares to 10 to 20 percent of the traffic from other Wi-Fi-equipped smartphones.