Connectivity Q & A: Unscrambling the Wi-Fi 4/5/6/6E Standards

The Wi-Fi Alliance is launching yet another enhancement – further advancing the next standard in wireless communication with Wi-Fi 6E. In this blog, Tony Testa and Jaidev Sharma help us sort out the Wi-Fi 4, 5, 6, and 6E standards for today and tomorrow’s communication networks.

Tony and Jaidev, what are the latest Wi-Fi standards used in today’s wireless products?

Since the release of Wi-Fi more than 20 years ago, the standard has transformed as applications and new technology have emerged. Each new standard was built upon a previous one adding improvements in speed, performance, and signal reliability. Today, there are only a few Wi-Fi standards in use. The three most prevalent in consumer products are 802.11n, ac, and ax. Also known as Wi-Fi 4, 5 and 6. Let’s review some high-level facts and differences among these three standards:

Wi-Fi 4 (802.11n)
 
Wi-Fi 4 was the first time we saw multiple-input-multiple-output (MIMO) added to Wi-Fi products. It added 40 MHz of bandwidth. The separate RF streams in MIMO operate in parallel independent channels. This doubles the channel-width, providing twice the data rate over a single 20 MHz channel. It allows up to 4 spatial streams (4-MIMO) with a theoretical peak throughput of 600 megabits per second, to increase overall throughput.

Wi-Fi 5 (802.11ac)
 
Wi-Fi 5 took MIMO a bit further, creating wider bandwidth up to 8-MIMO spatial streams to achieve 160 MHz of 5 GHz bandwidth. Additionally, to achieve higher capacity and data rates, modulation was increased from 64 quadrature amplitude modulation (QAM) to 256 QAM. Wi-Fi 5 also brought multiple-MIMO. Collectively, it increased the channel bonding, adding the capability of multiple streams to a single user. It also allowed for direct spatial streams to multiple clients simultaneously, thus improving network efficiency. The Wi-Fi 5 technology standard was the first to introduce beamforming. Beamforming allows the antenna to transmit the radio signals so they are directed at a specific device, minimizing interference and optimizing the wireless connection for each user.

Wi-Fi 6 (802.11ax)
 
Wi-Fi 6 brought us the era of more wireless capacity and higher signal reliability. It achieved this by increasing the modulation from 256 QAM to 1024 QAM, reducing the sub-carrier spacing and using scheduled-based resource allocation. Additionally, unlike single-band Wi-Fi 5, Wi-Fi 6 is dual-band, using both 2.4 and 5 GHz technologies simultaneously.

For the two most recent standards, Wi-Fi 5 and Wi-Fi 6 - can you provide additional information outlining how the modulation schemes differ?

Wi-Fi 5 (802.11ac)
 
Wi-Fi 5 standard uses orthogonal frequency-division multiplexing (OFDM) technology with 256 QAM modulation to deliver data packets. Under OFDM, a device uses a fixed bandwidth (i.e., 20/40/80/up to 160 MHz) to deliver the packets, regardless of whether it is transmitting video or sending a simple text message. This means that each user does not always get the same experience with delivery of data packets. It depends on where they fall in the queue (i.e., earlier users in the data queue get a faster data experience than those later in the queue).

Wi-Fi 6 (802.11ax)
 
For Wi-Fi 6, however, orthogonal frequency-division multiplexing access (OFDMA) is used, which allows resource units to divide the bandwidth according to the needs of the user. It provides each user with the same experience at faster speeds. For OFDMA, the same bandwidth can be used to deliver data more efficiently. With the addition of 1024 QAM there are more bits per symbol – 10 bits per symbol versus 8 bits in 256 QAM. Thus, the more bits, the more data - and the delivery of data is much more efficient. Additionally, the use of OFDMA decreases the space between the subcarriers, packing even more resource units into each data delivery payload.

Wi-Fi Tech & Trends

Read other blogs in this series to get practical design advice from Wi-Fi expert Tony Testa.

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With the buzz in the industry about Wi-Fi 6 moving up into the 6 GHz range, can you provide details on the impact it will have on devices?

From the beginning of 4G and now in 5G, the cellular and Wi-Fi communities have cooperated on ways to share frequency bandwidth to accommodate user capacity. In fact, 5G cellular will require even more from Wi-Fi to meet customer needs. As more bandwidth is required to meet 5G use cases, today’s 5 GHz Wi-Fi will strain to help cellular carry the load – especially when it comes to indoor communications.

The solution is to increase the bandwidth of Wi-Fi into the 6 GHz range, as this will improve cellular handoff and user quality-of-service. 6 GHz is well suited to facilitate Wi-Fi's growth and it offers accessibility to a clear spectrum with less interference from Wi-Fi 4 and Wi-Fi 5 devices on the 2.4 GHz and 5 GHz bands. It also provides greater availability of wider channel sizes – enough to accommodate 14 additional 80 MHz channels and seven additional 160 MHz channels. Moreover, this provides forward-looking capabilities for Wi-Fi 7 and beyond, where bandwidths of 320 MHz are being discussed.

For example, during the 2020 Consumer Electronics Show (CES), the Wi-Fi Alliance announced its industry support of the 6 GHz spectrum with a formal naming convention of "Wi-Fi 6E." Edgar Figueroa, president and CEO, Wi-Fi Alliance stated, "6 GHz will help address the growing need for Wi-Fi spectrum capacity to ensure Wi-Fi users continue to receive the same great user experience with their devices. Wi-Fi Alliance is introducing Wi-Fi 6E now to ensure the industry aligns on common terminology, allowing Wi-Fi users to identify devices that support 6 GHz operation as the spectrum becomes available."

Can you offer any projections as to when 6 GHz Wi-Fi 6 products will be available from Qorvo?

We have an entire portfolio for Wi-Fi 6 solutions covering 2.4 GHz and 5 GHz. Regarding the new 6 GHz frequency band, Qorvo's development efforts have been well underway for new front-end modules (FEMs), some of which were demonstrated at customer and partner booths during the recent 2020 CES convention. We will have a full RF portfolio of 6 GHz FEMs and filters that will enable this new spectrum when our customers are manufacturing product.

All Wi-Fi device segments differ slightly regarding parameter requirements (i.e., voltage, output power and frequency of operation). This new Wi-Fi 6E standard is no exception. Given that it’s still in the early stages and end-product design requirements are still being evaluated and established, we are actively collaborating with standards bodies, customers and partners, to help shape the new 6 GHz products.

For example, the filtering requirements at these high 6 GHz frequencies have very narrow transition bands making the design process more highly complex. In this higher frequency realm, it becomes more challenging to achieve the required rejection to meet system isolation with minimal insertion loss. Qorvo's Bulk Acoustic Wave (BAW), along with other broadband filtering capabilities, have several key attributes to help enable such solution requirements. We have already sampled BAW product, provided data, and are working closely with customers and standards bodies to help meet and establish core industry requirements.

Tony and Jaidev's Final Thoughts

Over the course of the last 20 years we have seen each generation of the Wi-Fi standard evolve and bring exciting new advancements for the world of wireless communications. By introducing new protocols, higher orders of modulation schemes, and the implementation of multiple streams using MIMO technology, Wi-Fi has been able to compete and outperform other wireless standards. Moreover, the development of Wi-Fi continues, and we are actively collaborating with customers and standards bodies to develop and shape tomorrow's connectivity solutions to provide our customers with the best wireless experience.