High-density scenarios are places crowded with many users and terminals. Typical high density scenarios include both permanent deployments – such as airports or stadiums – and temporary ones, for concerts and special events. A prime example is Mobile World Congress, which is as intense as it can be!
In a high-density wireless network, the required throughput and number of client devices exceed the capacity of traditional coverage-oriented Wi-Fi networks. High density networks are primarily limited by the availability of airtime, as traditional network considerations—such as coverage, signal strength, and signal-to-noise ratio (SNR)—are insufficient to overcome the capacity concerns. Since all users of a Wi-Fi network must share the same medium of transmission (air), a high number of client devices means a high number of users that must share airspace, and thus compete for limited airtime.
The IEEE 802.11ax spec is particularly geared to high density, high throughput environments such as stadiums or large apartment blocks, boosting data rates and allowing more simultaneous clients to be supported. It is primarily for indoor use – outdoor operation will be limited to stationary and pedestrian speeds. While most Wi-Fi standards focus on the data capacity of a whole network shared by multiple users, 11ax will address and boost the actual data rate to each individual device. With this standard, it is anticipated to increase that speed at least fourfold and to ratify the specifications in 2018. Some of the technologies which are likely to be harnessed will also be part of the next wave of cellular standards e.g. MIMO-OFDA, dynamic spectrum allocation, interference coordination and hybrid access techniques. Meanwhile, 802.11ay will aim to boost the speeds of 60 GHz WiGig to 40Gbps and beyond.
Concurrently, the Wi-Fi Alliance has announced another certification called Wi-Fi Certified Optimized Connectivity, which is designed to optimize client connection setup in high density environments and is based on the IEEE 802.11ai standard that was ratified earlier in 2017. The certification introduces two main enhancements: probing flood reduction during AP discovery performed by WiFi clients and fast initial link setup to the selected AP after discovery.
As Hemant Chaskar, VP Technology, Mojo Networks indicated in his blog Improving WiFi Connections in High-Density Environments, the Wi-Fi Alliance’s interest in improving public WiFi performance is in part motivated by the desire to stand up to License Assisted Access LTE technology. LAA-LTE allows operators and service providers to operate LTE wireless access networks in the 5 GHz unlicensed spectrum. One of the benefits cited for LAA-LTE is its efficient air interface that performs better in high-density networks compared to traditional WiFi. However, LAA-LTE requires a leg in the licensed spectrum to support its control channel; WiFi does not require any licensed spectrum at all.
By introducing features that make WiFi air interfaces more efficient, WiFi can remain a viable technology for public wireless access. Expect to see more such enhancements in the future, particularly to align with mainstream adoption of 802.11ax.