Semiconductor IP News and Trends Blog
Why Should Semiconductor IP Designers Care about WiGig?
WiGig is here but few designers understand its basic architecture, beamforming, market categories, semiconductor IP usage, and design challenges.
By John Blyler, Editorial Director
The Wireless Gigabit Alliance (WiGig), now part of the Wi-Fi Alliance, develops and promotes the adoption of multi-gigabit speed wireless communications technology that operates over the unlicensed 60 GHz frequency band. It enables high performance wireless data, display and audio applications to extend the capabilities of previous wireless LAN devices by enabling new use cases that complement traditional Wi-Fi®. Popular use cases for WiGig® include cable replacement for popular I/O and display extensions, wireless docking between devices like laptops and tablet, instant sync and backup and simultaneous streaming of multiple, ultra-high definition and 4K videos.
As an amendment to IEEE 802.11, the WiGig/IEEE 802.11ad specification defines Physical (PHY) and Medium Access Control (MAC) layers (see Figure 1). It enables native support for Internet Protocol (IP) networking over 60 GHz. This support makes it simpler to produce devices that can communicate over both 60 GHz and existing Wi-Fi applications by using tri-band radios which operate in 2.4 GHz, 5 GHz, and 60 GHz.
These tri-band enabled devices deliver data transfer rates up to 7 Gbit/s, about as fast as an 8-antenna 802.11ac transmission, and nearly 50 times faster than the highest 802.11n rate. Best of all, the WiGig devices maintain compatibility with existing Wi-Fi devices. While the 60 GHz signal cannot typically penetrate walls, they can propagate off reflections from walls, ceilings, floors and objects using beamforming built into the WiGig system. When roaming away from the main room the protocol can switch to make use of the other lower bands at a much lower rate, but which propagate through walls.
WiGig signals in the 60 GHz band are more susceptible to disruption from physical barriers than at lower frequencies. This problem is addressed by using adaptive beam forming, which allows for multi-gigabit communications at distances greater than 10 meters. Beam forming uses directional antennas to reduce interference and focus a signal between two devices into a concentrated “beam,” allowing faster data transmission over longer distances. Specifically, beam forming or spatial filtering combines elements in a phased antenna array such that signals create constructive and destructive interference, effectively changing the shape of the radiated or received beam.
The IEEE 802.11ad specification supports beamforming within the PHY and MAC layers. According to the WiGig alliance, two devices establish communication during the beamforming process. These devices then fine-tune their antenna settings to improve the quality of directional communication until there is enough capacity for the desired data transmission. If an obstacle blocks the line of sight between two devices – if someone walks between them, for example – the devices can quickly establish a new communications pathway.
According to a recent ABIResearch report, companies marketing their WiGig or future WiGig chipsets fall into three categories:
- 60 GHz backhaul companies that are leveraging their RF expertise to create WiGig chipsets. Some of these are creating single antenna solutions that will not perform well.
- WiGig chipset vendors with solutions for PC-centric products that are shifting to mobile products, such as Intel. Intel will be focused on its PC platform first, and then on mobile devices later.
- WiGig chipset vendors that have announced mobile device solutions. Wilocity came from the PC side and is here now after announcing its mobile solution. Qualcomm will help refine Wilocity’s mobile solution for the Snapdragon 810, and will likely have solutions under Qualcomm Atheros where only wireless connectivity is involved.
Semiconductor IP Useages
Several familiar analog designs will be needed to extend Wi-Fi to WiGig applications. These IP cores extend existing functionally to IEEE 802.11ad (WiGig) technology (see the Chipestimate.com portal for specific information):
- Wireless Display Extension (WDE) codecs such as H.264 that are used to implement the Protocol Adaptation Layer (WDE PAL) of the WiGig-(IEEE 802.11 ad) standard.
- Low-density parity-check (LDPC) decoder IP cores with data rates of up to 7 Gbit/
- Baseband technology unique to WiGig, which requires a complex digital sample rate of 2.64GHz. This rate is an order of magnitude higher than current wireless standards.
- Security content protection accelerator cores:. Accelerators provides the required technology for implementing all the secure access, cryptographic computations and cipher engine as defined in the HDCP2.2
- OFDM modes and MAC IP cores for backhaul baseband applications.
For the currently uncrowded, free 60-GHz spectrum, versatility will require improved radio platforms to meet the need for cheap, small, and low-power modules for the consumer markets (see Figure 2). This means using leading-edge, 40nm, low-power CMOS processes. Phased-array radio transmitters and receivers will be needed as well as new beamforming functionality. Power consumption must be low: 260 mW for the multiple receivers and 420 mW for the transmitters. Standards bodies have been formed to address this new technology—including a group within the IEEE and the Wireless Gigabit Alliance (WGA).
As always, the big question boils down to balancing performance (speed) and power. How can we design ultra-high-speed, versatile radios that consume ultra-low power? The good news is that we can. The bad news is that it takes a comprehensive, co-designed approach that requires system, architecture, and technology consideration.
At a system level, the challenge is to move from a performance and coverage mindset to one of capacity and energy. Meeting this challenge will mean connecting via the shortest and best direct link. Designs will need to enable the versatility to determine—on the fly—what type of link is the best for any given connectivity scenario.
Architecturally, connectivity platforms must be multi-mode and scalable. Improved designs will be needed for the next generation of power-efficient transmitters. Technology will help through further process scaling below 40 nm and with more heterogeneous integration of chip dies and related structures, such as MEMS and interposers.
From a wireless perspective, all of these challenges and solutions will welcome a future of very versatile radio devices that can operate at ultra-low power over a variety of heterogeneous networks. These platforms will then provide the technology upon which a sensor-rich, context-aware, user-experience-driven world can exist. Whether it proves to be more beneficial or distracting for most of us remains to be experienced. (see, “See MEMS And Packaging Hold Keys To Radio Connectivity”)