Wi-Fi 6 For Low-Power IoT

The internet of things, known as the IoT, is a rapidly growing market, and no surprise. While some question the need to connect everything to the internet, if it’s simple and cost-effective it’s a no brainer.

Wireless sensors are a case in point. You can monitor equipment to detect any indication of equipment failure, check temperatures in your restaurant to ensure your fridge remains cool, or measure for carbon monoxide levels in a residential care home, to give just a few examples. Then there are new categories such as “hearables,” essentially miniaturized in-ear computers that can be used to measure activity and monitor health.

Whatever the application, though, these devices need to be battery operated, so power efficiency is paramount. Therefore, when we designed IMG iEW400, our latest IP for low-power connectivity, we looked to the new IEEE 802.11ax standard, now widely referred to as Wi-Fi 6.

When it comes to low-power connectivity Wi-Fi might not be everyone’s first choice, especially compared to Bluetooth. However, as this post focused on we believe that Wi-Fi is the first-choice option for IoT connectivity.

First, Wi-Fi is ubiquitous, with near to 4 billion units expected to ship by 2021 and as it’s built into so many devices it’s easy for end-users to interact with endpoint IoT devices. It also offers several benefits that other low-power connectivity solutions can’t. First, is the potential for much higher data rates; it can reach up to 230 Mbps.

Wi-Fi also offers a better range than competitors and it also operates at 5GHz, which is a much less congested frequency band than 2.4GHz. Finally, it also supports IP networking, which is important if you want to send data into the cloud without any complexity.

Wi-Fi 6: the key to low power consumption
However, Wi-Fi has generally been thought of as a higher power consumption technology compared to alternatives. Enter Wi-Fi 6, which brings several new features designed to address this. In fact, it’s been designed to both improve data throughput, increase robustness and reduce power consumption, all at the same time. For us though, our primary concern is how it makes Wi-Fi the ideal choice for low-power IoT applications.

Here we’ll run through some of the key features in Wi-fi 6 that we have implemented in iEW400 that make it so power efficient.

Stop, collaborate and listen
First, up is a feature called Target Wait Time (TWT). In many of the use-cases we described above, the device doesn’t need to be awake the entire time. It only needs to wake up even now and then to report its status. It could be hours, days, or even weeks before it needs to do anything, so why waste all that energy waking up to check if it needs to communicate with the access point?

Target Wake Time is a new Wi-Fi 6 feature where the access points negotiate with attached devices to agree when they should wake up to transmit data. This pre-scheduling means devices can deep-sleep for extended periods, dramatically reducing current consumption and significantly increase battery life. It means that sensors could potentially be left usefully gathering data in the field for years at a time.

Fig. 1: OFDMA is a major new feature for Wi-Fi 6 that significantly boosts data transfer efficiency

Another great Wi-Fi 6 features is Orthogonal frequency-division multiple access. This is a bit of a mouthful, so it is more commonly referred to as (OFDMA). This improves performance in high-density environments. By enabling bandwidth within channels to be segmented, multiple devices can receive data in the same time frame. This smart use of bandwidth increases data transmission efficiency, reducing power consumption, and dramatically increasing data throughput.

Fig. 2: Before BSS Coloring

Next is BSS Coloring. In areas where there are multiple access points and many clients, such as large crowds, Wi-Fi typically struggles to deliver consistent throughput. This is because the data from different access points can overlap, causing contention and interference. With the new Basic Service Set (BSS) Coloring feature in Wi-Fi 6, each data from each access point is prescribed a “color”, so clients can identify which one is transmitting, resulting in improved network performance.

Fig. 3: After BSS Coloring

Finally, for when signal robustness is paramount, iEW400 also supports dual-carrier mode. Dual subcarrier modulation (DCM) is where the same information is modulated on a pair of sub-carriers, which can ensure data gets through even in challenging scenarios.

The one-stop-shop solution
What makes our iEW400 unique in the market is that it’s a one-stop-shop solution. If you’re looking to integrate Wi-Fi into your IoT design you don’t need to look around – the iEW400 contains RF, baseband, the lower and upper MAC components, and we’re the only supplier in the market that can do this.

Fig. 4: System block diagram of iEW400 with both upper and lower MAC

The upper MAC allows you to offload work from the host processor to reduce total system power consumption, but we’re also flexible and it’s optional, should you prefer you can choose not to take it. The same goes for the power management unit. Our PMU supports 2.7-4.5v DC, making it optimized for low power but you can use your design should you prefer.

The iEW400 is also easy to integrate and is supplied as a silicon-ready design, including analogue pads, in TSMC 40nm LP. When delivered, it will also be pre-certified to conform to Wi-Fi Alliance standards, all of which can accelerate your time to market. This alone could be what helps you build a winning product.

Conclusion
With iEW400 we’re excited about the possibilities that Wi-Fi 6 can bring to the market. With our unrivaled ability to provide a complete solution, with flexible options, in a silicon-proven design, you can reduce risk and reduce the total cost of your solution, while accelerating your time to market. The result is a product based on the latest technology that will cost the end-user less, while also increasing your margins. There’s no downside, and we’re excited to see IoT products based on iEW400 coming to market in the future.