Monday, December 19, 2011

Wireless chip companies target 802.11ac Gigabit WiFi in 2012, but it's not all about the speed

Following on Quantenna Communications' recent claim to be first to market with a  802.11ac chipset and reference design, add Broadcom and Redpine Signals to the companies planning to rollout chipsets for the next-generation IEEE WiFi standard. Though the standard will not complete the IEEE 802.11 Working Group ratification process until December 2013, Broadcom and Redpine have both announced plans to have chipsets available by the 2nd half of 2012.

In a pre-Consumer Electronics Show (CES) briefing on December 8th, Broadcom's VP for the Mobile and Wireless Group - Rahul Patel talked about his companies plan to develop "several types of .11ac chipsets" targeting Consumer Electronics (CE) devices. Patel focused on shifts in video consumption in the "post-PC" era, citing statistics from the October, 2011 Sandvine Broadband Report. Sandvine found that real-time on-demand entertainment now accounts for 60% of North America’s fixed access network traffic during the evening’s peak period. Broadcom's target for their new wireless chipsets is the "post-PC era" shift, which Sandvine identified, in the type of devices consumers are using to consume their digital entertainment:

By volume, 55% of Real-Time Entertainment traffic is destined for the television (either directly to a smart TV or via an intermediary like a game console or set-top device), a mobile device or tablet. The remaining 45% is being delivered to desktop and laptop computers; even then, some will be forwarded to a television. (source: Sandvine - "Global Internet Phenomena Report", Fall 2011)
The digital living room is now becoming a network of wireless connected devices, with game consoles, smartphones and tablet PCs increasingly used to deliver video to the TV, typically via an HDMI cable.  Broadcom sees the emerging 802.11ac standard, which will shift use entirely to the 5GHz band, as the enabler to deliver faster throughput and broader coverage to CE, while supporting simultaneous connections for a larger number of devices. The new standard allows for wider channels, up from 40Mhz in IEEE 802.11n to 80MHz and 160MHz, with doubling of support for up to eight Multiple-Input/Multiple-Output (MIMO) streams, and an increase from 64-Quadrature Amplitude Modulation (QAM) to 256-QAM. Broadcom says that they expect to begin shipping  802.11ac products in the second half of 2012.

Ten-year old Redpine Signals has announced that they are ready to  take 802.11ac to mobile devices, with their claim to have the "industry’s first IEEE 802.11ac technology offering for integration into smartphone application processors". Venkat Mattela, Chairman and Chief Executive Officer of Redpine, says that the company's focus from the beginning has been on low power techniques for WiFi chipsets. In 2005 Redpine licensed their 802.11b/g technology to PortalPlayer, a company that NVIDIA acquired in 2007, which had been providing SoCs to Apple for the iPod. Mattela says that two years later, Infineon also licensed Redpine's low power technology.  

In March of this year Redpine completed development of their 802.11ac technology, and for the last nine months, according to Mattela, they have been working with "a big mobile company" for integration into their smartphone platform.  Mattela says that he only licenses to companies that ship 300M-400M devices per year, and his 3rd licensing deal is "happening anytime". Redpine also manufactures their own chips and modules, the latter focused on industrial market segments. 

Although Redpine designs the complete RF/Analog Front-End (AFE) for their WiFi subsystems, they have licensed just the analog and digital baseband functions, as a combination of hard and soft IP, to companies who have their own RF designs and Power Amplifiers (PAs). Mattela says that licensees gain assurance from access to the soft IP,  but due to complexity of the WiFi subsystem it is always his company's team that develops the complete macro for integration into a customer's SoC.  Rather than use an ARM or MIPS processor in their WiFi subsystem, Redpine developed their own "ThreadArch" processor for Layer-2 WiFi processing. Mattela says that this, and their low-power Orthogonal Frequency-Division Multiplexing (OFDM) engine, are key differentiating factors that contribute to lower power consumption by requiring fewer CPU cycles .

For mobile handset applications, Mattela says that initially the industry thought that only single-stream WiFi implementations would be required, but the need for higher data rates has driven the use of MIMO with dual antennas. He sees this being the case for 802.11ac as well, with handsets employing up to 80MHz channels on the 5GHz carrier. The standard allows up to 160MHz channels, but this causes other problems, says Mattela, and is not necessary for mobile devices.  Along with the Gigabit data rates of 802.11ac, Mattela sees the capability for multi-user MIMO, which will enable spreading the bandwidth over a larger number of users, as being the most critical factor that will drive adoption of the new standard. This will alleviate the problem of hotspots with high user density, common to demos at places like CES, where connectivity can be locked out by a single user consuming all of the available channel bandwidth. 

The higher data rates of 802.11ac could be expected to result in higher power consumption, but Redpine used the profile of their previous generation  802.11n design, with <1mW consumption while connected to an access point, as a reference for the new design. Mattela says that they have been able to achieve the same power profile, through changes to the analog front end and other engineering innovations, so that users will not experience any penalty when the new devices come online in the 2nd half of next year. 

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