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18 quickly integrate the new technology into their products. Security Wi-Fi Protected Access II (WPA2), which was introduced in 2004 and based on the IEEE 802.11i specification, currently protects Wi-Fi from malicious attacks. The WPA2 protection operates under the Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP), which is based on Advanced Encryption Standard (AES) processing and uses a 128-bit block size and a 128-bit key. IEEE 802.11ax could be the first amendment to take advantage of Wi-Fi Protected Access "III" (WPA3), the replacement for WPA2, announced by the Wi-Fi Alliance™ in January 2018. The new security standard uses a 192-bit key encryption and encryption individualization for each user. Supposedly, WPA3 also simplifies the process of setting up devices with no display interface, which is an essential requirement for units such as wireless sensors that connect to IoT. Availability Uncertified Wi-Fi technology and associated development tools typically hit the market before the formal adoption of a new amendment to allow engineers to start on new projects. If the amendment specification changes after uncertified products have been introduced, then firmware updates are usually permissible to bring deployed units into full compliance. With IEEE 802.11ax slated for adoption in 2019, silicon vendors have already started introducing chipsets. For example, Qorvo, a radio frequency (RF) systems company, has launched the QPL7210 2.4GHz Wi-Fi The increase in symbol duration helps to ensure reliable service for a technology that promises an ambitious 8 x 8 MU- MIMO scheme. The additional guard band interval of 3.2µs adds robustness in demanding, outdoor, and dense deployment situations (Table 1). Table 1: This table compares IEEE 802.11ac and IEEE 802.11ax. (Source: Mouser Electronics) IEEE 802.11ax also introduces a feature that aims to reduce the power consumption of battery-powered devices. Called target wake time (TWT), this feature supports resource scheduling by enabling devices to negotiate when and how often they will wake up to send or receive data. Because their communication is scheduled via the TWT rather than by an ad hoc time, devices can safely spend non-scheduled communication time in a low power, sleep mode. Target Applications HEW was designed to succeed IEEE 802.11ac as the mainstay of Wi-Fi communication. With the significant advantages of greater throughput and more robust service, HEW will support the ubiquitous Wi-Fi to which mobile-device consumers have become accustomed in both domestic and commercial environments. After adoption of the amendment, it's likely that consumer- electronics firms and domestic and commercial access-point makers will LNA Receive Module, a front-end module (FEM) for Wi-Fi 802.11ax as well as "n" and "ac" applications. The QPL7210 integrates a 2.4GHz low noise amplifier (LNA), an LNA bypass, and a high- selectivity receiving bulk acoustic wave (BAW) filter for wireless coexistence. By integrating this functionality into a single module (measuring 3.0 x 3.5 x 1.0mm), the QPL7210 addresses some of the design complexity that IEEE 802.11ax introduces. Design Challenges IEEE 802.11-based RF design requires a high level of expertise even when leveraging proven technology, firmware, and operating systems from leading vendors. This is because IEEE 802.11ax, for example, introduces modulation techniques from LTE cellular technology, brings extra complexity, and adds to the design challenges. However, with a knowledgeable silicon and firmware vendor and previous experience (particularly with IEEE 802.11ac), developing with IEEE 802.11ax can certainly fall within the scope of capability for most competent engineers. One approach that eases design complexity is to select a module that incorporates the designer's selected technology. Modules offer good RF performance directly out of the box and are typically verified and certified solutions. Modules come with tested Wi-Fi and Transmission Control Protocol/Internet Protocol (TCP/IP) firmware stacks, leaving the designer to focus on differentiating his or her product via the application software. Module downsides include a higher bill of materials (BOM) and a larger space requirement compared to the requirement of a discrete solution. In addition to the overall complexity of IEEE 802.11ax, certain design challenges exist of which engineers should be aware. First, the technology is more prone to narrowband interference than previous versions; overcoming such interference may require the engineer to employ Table 1 Feature IEEE 802.11ac IEEE 802.11ax Operating frequency (GHz) 5 2.4, 5 Channel bandwidths (MHz) 20, 40, 80, 160 20, 40, 80, 160 Highest modulation rate 256-QAM 1024-QAM Data rate (Mbps), required channel (MHz) 433, 80MHz channel 6933, 160MHz channel 600, 80MHz channel 9607, 160MHz channel Capacity increase vs previous version 2X 4X BSS coloring No Yes MU-MIMO Downlink only Uplink and downlink OFDMA No Yes TWT No Yes Range (ft.) About 800 800+

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