What to Ask for Optimal Design

Since the establishment of the Wi-Fi Alliance in 1999, Wi-Fi technology has consistently advanced to meet the ever-increasing demand for faster speeds and support for a greater number of devices. Its popularity has grown to the extent that it has become a common term in the dictionary. Today, it serves as the ubiquitous internet connection for a diverse array of clients, ranging from data-hungry devices such as laptops, smartphones, TVs, and set-top boxes, to data-tweeting IoT gadgets that send out occasional updates, like home and office appliances.

According to ABI, annual wi-fi-enabled device shipments continually rise and are projected to surpass 5 billion units by 2028, with the primary driving force for future growth expected to come from the Smart/Connected Home, Wearable, and IoT market segments.

Differences Between the Generations and Varieties

What is Wi-Fi 6?

Based on the IEEE 802.11ax standard, it currently stands as the most popular generation utilized in the market. According to ABI, almost half of wi-fi devices shipping in 2023 were Wi-Fi 6, and this will climb to two-thirds of shipments by 2026.

Compared to Wi-Fi 5 (IEEE 802.11ac), Wi-Fi 6 comes with double the maximum MIMO configuration, double the maximum channel bandwidth, and a higher modulation scheme. This translates to more than 5 times the maximum data rate at PHY level. Even though that is quite significant, this is not what has made Wi-Fi 6 so popular, with the fastest penetration rate ever for a new generation.

Wi-Fi 6 offers the primary benefit of increased network efficiency, especially in densely populated areas where it allows for connecting more devices to the same access points. This results in a superior user experience characterized by higher throughput and lower latency. This higher efficiency comes from two major features, among others.

Multi-User MIMO

A multi-user MIMO (MU-MIMO) divides the MIMO operation of an Access Point (AP) between multiple users (or stations). For instance, an 8×8 AP can handle up to eight 1×1 users simultaneously, one per spatial stream.

Multi-User OFDMA

A multi-user OFDMA (MU-OFDMA) allows the total available bandwidth to be divided among several users into Resource Units (RU). This way, more users can connect to the AP. For instance, up to 37 simultaneous users can share an 80MHz channel, each using just 2MHz bandwidth. Furthermore, such a narrow band allows better coexistence with other narrow band technologies such as Bluetooth and 802.15.4 (i.e. Thread, ZigBee).

MU-MIMO and MU-OFDMA enable an AP to better schedule traffic among users, with proper granularity and better control of quality of service.

Another great feature of Wi-Fi 6 is Target Wake Time (TWT). It is particularly interesting for low-power IoT devices. Each Wi-Fi 6 device connected to the AP can go into deep sleep and wake up at its respective scheduled time pre-negotiated with the AP. This minimizes conflicts and significantly reduces the power consumption.

What is Wi-Fi 6E?

Wi-Fi 6 operates on the 2.4GHz and 5GHz bands. The 2.4GHz band is well-known for its congestion due to the presence of other wireless technologies like Bluetooth, Zigbee, and Thread. The 5GHz band is the express highway to avoid this congestion.

However, the demand for data bandwidth is never satisfied. The explosion of video content, the rollout of super-fast fiber-based internet, and a more dispersed workforce stretch the capacity of even the 5GHz express highway of Wi-Fi 6. So Wi-Fi 6E (still derived from IEEE 802.11ax standard) has been released to expand the capacity using the 6GHz band (more precisely, from 5.925GHz to 7.125GHz).

This extra 1.2GHz bandwidth adds up to 7 channels of 160MHz bandwidth (whereas only 2 such wide channels are available on the 5GHz band), or up to 14 80MHz channels (only 5 on the 5GHz band). 6GHz also comes with lower congestion, hence lower latency. This is particularly important for gaming and AR/VR headset applications. However, 6GHz has a more limited range with reduced wall & ceiling penetration capability.

What is Wi-Fi 7?

While the Wi-Fi Alliance has just officially announced the Wi-Fi CERTIFIED 7 program in January 2024, we have already been seeing “pre” Wi-Fi 7 chips and devices on the market in 2023. Originated from the IEEE 802.11be specifications, Wi-Fi 7 comes with bigger muscles:

• Up to 320MHz channel bandwidth, compared to 160MHz in WI-FI 6/6E (802.11ax). This is available only on the 6GHz band.
• Up to 16×16 MIMO configuration, compared to 8×8 in WI-FI 6/6E (802.11ax).
• 4K QAM maximum modulation, compared to 1K QAM in WI-FI 6/6E (802.11ax).

Wi-Fi 7 is almost 5 times faster than Wi-Fi 6/6E. But this is not the only reason for the sudden appetite for Wi-Fi 7. Two very important features are driving attention to this latest and greatest Wi-Fi generation.

Multi-Link Operation

Multi-link operation (MLO) provides the ability to aggregate two channels from the same or different bands to increase the throughput, stepping around interference and reducing latency.

MLO also offers the capability for load balancing, enabling rapid and seamless channel switching to minimize contentions/retries. This also translates into a reduction of the latency.

Multi Resource Unit

When there is a need for a “large” resource unit driven by the user’s throughput requirement, such a large bandwidth may not be free throughout the whole channel bandwidth. Thus, employing a concept similar to MLO, called a multi-resource unit (MRU) could be more effective. In this instance, two contiguous or disjointed Resource Units on the same channel may be aggregated for a single user to meet the throughput requirement.

Thanks to MLO and MRU, Wi-Fi 7 (802.11be) is very attractive, particularly in applications with high throughput, low latency, and high link reliability requirements. How, when, and which channels to aggregate is where the Wi-Fi 7 infrastructure providers will differentiate.

What Is the Best Version and Configuration for My Application?

It is not always appropriate to select the latest and greatest version and configuration as this could lead to expensive overkill. The challenge is to select the version and configuration that provides the best compromise between performance, cost, and power consumption. Let’s have a look at a few examples.

Low-Power IoT Devices

Cost often takes precedence in low-power IoT, followed by power consumption. This is why Wi-Fi 4 (derived from IEEE 802.11n specification) single band 2.4GHz is still dominant, as one can find chips far below $1 that are good enough. But as volumes are picking up, the Wi-Fi 6 chip cost is getting very close to WI-FI 4 chips. It also brings additional benefits:

• Higher data throughput thanks to higher data rates.
• Lower power consumption thanks to the TWT feature.
• Lower power consumption thanks to lower duty cycle.
• More WI-FI 6 devices can connect to a WI-FI 6 access point.
• Slow low-power Wi-Fi 6 IoT devices do not slow down the Wi-Fi network.

If reliability is key, it is important to at least support dual-band, as often seen in some industrial applications.

If latency is critical, it is advisable to support Wi-Fi 7 with MLO or MLSR (Multi Link Single Radio).

High-End Devices

High-end Wi-Fi-enabled devices usually deal with high-volume data transfer such as video streaming and file sharing. These devices include smartphones, tablets, PCs/laptops, TVs, STBs, cameras, AR/VR headsets, and more. They predominantly have MIMO 2×2 multi-band configuration.

While we still see a lot of Wi-Fi 5 chips on the market, new designs are predominantly at least Wi-Fi 6 (802.11ax) to get the benefits of throughput efficiency, particularly as the number of devices connected to the access point is growing. Some of them such as smartphones, gaming consoles, and AR/VR headsets will see great benefits in moving to Wi-Fi 6E or even Wi-Fi 7 (802.11be) to enjoy even higher reliability and lower latency.

Access Points

When designing, deploying, or upgrading infrastructure it is recommended to go for Wi-Fi 7 (802.11be) access points, particularly in dense environments such as airports, stadiums, shopping centers, and offices, where up to thousands of users are connected, moving, and having dynamic Wi-Fi requirements, regularly switching between emailing, browsing, chat, file transfer and video conferencing. These access points predominantly have a 4×4 MIMO configuration.

For smaller environments such as homes or small offices, access points with 2×2 MIMO configurations are usually enough. According to ABI, 2×2 configuration represents over 40% of the total networking and access point Wi-Fi chipset shipments. If there is not a very strong latency requirement, Wi-Fi 6 or 6E can be enough from a technical point of view, but the marketing value of WI-FI 7 in relation to competition must be considered.

Wi-Fi for Today and Tomorrow

Wi-Fi technology today exists in many varieties and configurations, supporting hundreds of features with various levels of complexity. It may be challenging for a device maker to select the right specification that fulfills the functionality, performance, cost, and power consumption constraints. But with some careful consideration of the relative strengths of each incremental standard and a specific understanding of the use case needs, there are exciting opportunities to increase the performance of next-generation connected devices.