By David John Urban, Comcast
Historically, Wi-Fi is a polite protocol. Users will take turns in the time dimension to access the radio interface, sending and receiving messages. As the number of devices in the home has grown, more efficient multiple-user technologies have been introduced. The objective is to utilize these advanced multiuser features to benefit broadband customers in a tangible way. Techniques to improve the speed of a single user can be readily observed by customers with a simple speed test. The benefits of multiple user technologies require several devices and applications working in tandem. Laser focus on how technology benefits customer experience rather than technology for technology’s sake is key. A traffic model that accurately reflects the situation in customers’ homes is critical in applying multiuser technology that improves customer experience.
For multiuser techniques such as Multiple User Multiple Input Multiple Output (MU-MIMO) and Orthogonal Frequency Division Multiple Access (OFDMA) to work, a confluence of devices and applications must meet. The customer’s devices must have multiple-user capability. Not all devices can take advantage of multiuser technology. Sometimes, the probability of several devices using applications that need access to the Wi-Fi radio signal at the same time is low; when low probabilities multiply the overall probability gets exponentially lower. The trick is to weed out the low probability use cases and focus on the commonly occurring use cases. This paper identifies the commonly occurring use cases for multiuser Wi-Fi technology and describes the theory behind multiple user techniques of multiple antenna spatial streams, spectrum resource unit allocation, and spatial frequency reuse. The paper sorts out aspects that are mostly for show from the technologies that lead to better user experience.