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RF & MICROWAVE DESIGN WLAN 802.11ad and beyond – what next for 60 GHz WiFi? By Mark Barrett The almost insatiable growth in demand for high volumes of data to be transferred over wireless networks shows no signs of abating, with HD video now being rapidly superseded by 4K and eventually 8K. Downloading and sharing high-definition video consumes huge amounts of bandwidth, and conventional WiFi networks operating in the 2.4GHz and 5GHz bands are already struggling to cope. Although more recent WiFi standards have progressively increased data rates, these new applications demand speeds of tens of Gb/s, which cannot be achieved at these relatively low microwave frequencies. This trend has driven the introduction Fig. 1: Use cases for WiGig/IEEE 802.11ad. of a new networking standard at 60 GHz, designated IEEE 802.11ad, to work alongside the existing WiFi channels in order to ease the demand on them. The standard, also known as WiGig, is being administered by the Wi-Fi Alliance, which is currently working on interoperability testing between 802.11ad devices. Because of the propagation characteristics of 60 GHz electromagnetic waves, WiGig devices work best over a shorter range, such as within a single room, making them ideal for streaming data onto mobile devices for ‘Sync and Go’ applications, or for replacing an HDMI cable for gaming or transferring HD video content. They also lend themselves to entertainment networks on public transport, such as on planes, ships, trains, and buses. Augmented reality (AR) and virtual reality (VR) systems that promise nearto reality user experiences by exploiting 3D video and 7.1 audio are also potential applications for this technology. In cordless computing, 802.11ad can be used for wireless docking and connection to displays, rapid backups and synchronization over wireless, and file transfers between computers and handheld devices. These use cases are summarised in figure 1. The 60 GHz band has wider spectrum availability than the 2.4 GHz and 5 GHz bands — bandwidths range between 7 GHz and 9 GHz although in common with other frequency allocations, the available frequencies and bandwidths vary somewhat between geographical areas. Figure 2 shows the global frequency allocations for wireless networking around 60GHz. The bands are divided into 2 GHz channels. These broader bandwidths allow for wider channels to support faster data rates of up to 7 Gbps using low power modulation schemes, as shown in Table 1. However, even these data rates are not high enough to support the expected demand from the applications outlined above, and consequently work is now focused on developing techniques to increase data rates further up to 30 Gb/s and above. WiGig/IEEE 802.11ad specification Among the key features of the specification is low-power design, including advanced power management, to support extended battery life in handheld mobile devices and laptops. Devices are able to switch seamlessly between 60 GHz operation and the lower WiFi frequencies of 2.4 GHz and 5 GHz. In addition to a wireless implementation of HDMI, the links can also emulate DisplayPort, USB and PCIe connections. A high level of security is integrated into the system using advanced encryption algorithms. Even more significantly, the standard supports beam forming using phased array antennas (PAA), which allows signal strength to be maximised and also enables communication over distances of greater than 10 m. WiGig chip market Figure 3 shows the forecast shipments of chipsets for the different ‘flavours’ of 802.11, according to ABI Research. By 2018, tri-band chipsets incorporating 802.11ad are expected to have a market of around 1.5 billion units per year, out of a total of just under 4 billion chipsets for all 802.11 variants. Over the past five years a number of companies have developed RF chips for 802.11ad, both in 60 GHz RF-on- CMOS technology – initially 65 nm, moving down to 40 nm and now towards 28nm Fig. 2: Global frequency allocations for WiGig/IEEE 802.11ad. and in SiGe. These include an IBM 60 GHz PAA chip, Silicon Image with its 60GHz Gen3 WirelessHD PAA chip, and Wilocity, which has been shipping pre-certified WiGig chipsets for both laptop and mobile phone applications. Despite all the emphasis on developing RF chips, and on overcoming the challenges of designing consumer devices at millimetre-wave frequencies, the baseband is equally important in providing the ability to control the beam forming function Mark Barrett is Chief Marketing Officer at Blu Wireless Technology Ltd – www.bluwirelesstechnology.com – He can be reached at Mark@BluWirelessTechnology.com 26 Electronic Engineering Times Europe October 2014 www.electronics-eetimes.com


EETE OCT 2014
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