The Wi-Fi landscape is rapidly evolving and its growth continues unabated. A ubiquitous amenity, Wi-Fi is routinely offered across a wide range of locations including carpeted enterprises, school/college/office campuses, stadiums, airports, hotels, MDUs, and transportation hubs. Fast and reliable Wi-Fi connectivity is now considered a basic human need by many. Consequently, Wi-Fi data consumption continues to outstrip cellular by a large margin, despite the promotion of unlimited data plans by major carriers. According to the Cisco VNI forecast, Wi-Fi is expected to carry 2.5x more global internet traffic than cellular by 2021.
The massive increase of devices demanding stable Wi-Fi connections has served as a catalyst for innovation in the unlicensed spectrum. Indeed, the FCC has voted unanimously to release additional 1.2GHz of unlicensed spectrum in the 6 GHz band. The availability of additional spectrum is quite timely, as Wi-Fi uses cases have significantly expanded to accommodate a plethora of Internet of Things (IoT) devices, smart homes, as well as outdoor deployments and high-density environments. These locations typically see a dense aggregation of connected devices contending for airtime, which creates a noisy Wi-Fi spectrum, increases interference, and degrades the user experience.
In particular, high-density environments present a formidable challenge for today’s already overloaded Wi-Fi networks. The harsh reality of limited spectrum is further compounded by the fact that the number of wireless users and clients continues to increase, with approximately 9 billion Wi-Fi devices shipped cumulatively. Moreover, the number of connected devices in a typical home is projected to reach 50+ by 2022. It is quite common to see typical homes in developed countries equipped with Wi-Fi enabled smart security cameras, thermostats, smoke detectors, door bells, sprinkler systems, and garage doors.
High-performance Wi-Fi is clearly becoming a critical requirement for a wide range of new devices, applications, and services. These include low bandwidth, short packet applications such as Wi-Fi calling, IoT sensors that are pushing or polled for data every few seconds, and bandwidth intensive applications like video streaming. Unsurprisingly, video is expected to comprise 75% of all mobile data traffic by 2023. A significant percentage of this non-homogeneous traffic – which is offloaded to the Wi-Fi networks – includes social live streaming apps which are latency sensitive with high link availability requirements and interactive video on demand. Multiple factors are driving an increase in video consumption, such as larger displays and faster processors, more data-intensive content and the growing popularity of AR/VR technologies.
So, what’s really the issue? The explosion of connected devices and traffic requires a more efficient wireless implementation than is offered by today’s network. 802.11 evolution (a, b, g, n, ac) has delivered increasingly higher data rates with improved modulation, channel bonding, and MIMO. In fact, Wi-Fi 5 (802.11ac) has done a phenomenal job of reaching gigabit throughput rates. However, the nuances of real-life Wi-Fi usage, particularly in high density scenarios, prevents users from benefiting from higher data rates. The Wi-Fi 6 (802.11ax) standard bucks this trend by focusing on efficiency instead of raw data rate. Indeed, Wi-Fi 6 (802.11ax) is intelligently deterministic rather than arbitrarily contention-based, with Wi-Fi 6 (802.11ax) APs making effective use of spectrum and optimizing throughput in dense and congested environments.
Put simply, crowded Wi-Fi deployments are analogous to stop-and-go traffic. A growing number of vehicles on the road – sedans, SUVs, big rigs, and two wheelers – reduces average speed and negatively affects the driver (user) experience. However, building a multi-lane Wi-Fi 6 (802.11ax) highway that includes carpool lanes enables a higher average throughput per user by expanding capacity and optimizing efficiency. To be sure, Wi-Fi 6 (802.11ax) is designed for high density environments, with the realization that not every vehicle on the freeway has the same need for speed. For example, some devices and applications have specific latency demands or bursty traffic needs, while other applications require long battery life. Wi-Fi 6 addresses all these requirements.
Let’s take a closer look at the primary features and benefits of Wi-Fi 6 (802.11ax) APs:
- Simultaneous multi-user transmissions: This is effectively achieved with MU-MIMO and OFDMA (two techniques that have been extensively utilized in the cellular domain), by focusing on the average throughput per station, rather than aggregate output. They are complimentary techniques in both directions (uplink and downlink) that efficiently serve diverse traffic types (e.g. text messages, video streaming, etc.) to multiple users concurrently. While MU-MIMO is useful when multiple users have full buffer traffic to send, OFDMA provides maximum benefit when multiple users have small amounts of data.
- Uplink Resource Scheduling: This feature is perhaps the most significant innovation and challenging aspect of Wi-Fi 6 (802.11ax). With uplink resources scheduling, the AP deterministically allocates resources, coordinates and schedules the simultaneous transmission of multiple clients.
- Spatial reuse: Multiple APs operate on a shared channel by mitigating co-channel interference. This is made possible by a spatial reuse technique known as BSS Coloring, which enables devices in one BSS to ignore frames from other BSSs on the same channel, which are typically some distance away.
- Improves power efficiency of station: Using a technique known as Target Wake Time (TWT), STAs can ‘sleep’ longer, thereby reducing power consumption. The AP coordinates with STAs to wake up at specified and scheduled intervals to exchange data frames.
- Bolsters indoor and outdoor operations: Wi-Fi 6 (802.11ax) includes mechanisms such as long OFDM symbols to optimize multi-path and supports robust outdoor deployments.
- Higher order modulation: With 1024QAM, Wi-Fi 6 can deliver 25% increase in capacity over 256QAM particularly at close distances.
In conclusion, delivering fast and reliable Wi-Fi coverage in high-density deployment scenarios with older Wi-Fi 5 (802.11ac) APs is increasingly difficult as streaming 4K video and other forms of immersive content becomes the norm. This is precisely why the new Wi-Fi 6 (802.11ax) standard offers up to a four-fold capacity increase over its Wi-Fi 5 (802.11ac) predecessor. With Wi-Fi 6 (802.11ax), multiple APs deployed in dense device environments can collectively deliver required quality-of-service to more clients with more diverse usage profiles. From our perspective, Wi-Fi 6 (802.11ax) is playing a critical role in helping Wi-Fi evolve into a collision-free, deterministic wireless technology that significantly increases aggregate network throughput to address high-density venues and beyond.