Like the 3GPP’s 5G New Radio, the WiFi community’s first ‘5G’ standard, 802.11ax, is close enough to finalization that companies can design ‘pre-standard’ chips, with reasonable confidence that they will only take minor tweaks to comply with the eventual specs. Broadcom announced its first 11ax offerings last week, joining Qualcomm and Quantenna.
Although successive attempts have failed to bring the IEEE and its 802.11 standards, the basis of WiFi, directly into the 5G process, it is probable that 5G networks will rely on a combination of the two technology strands, to an even greater extent than current wireless services. And the WiFi roadmap has many aims in common with the 3GPP’s – increasingly so, as cellular standards focus more on higher frequency spectrum (including WiFi’s ‘own’ 5 GHz band) and on shorter-range connections.
So while an LTE or 5G cellular network in 3.5 GHz or 5 GHz is effectively a wireless LAN (albeit with wide area cellular connectivity via the MNO), WiFi can promise much of the density, low latency and data rates targeted by 5G NR. Some of that promise is enshrined in 802.11ax, which is particularly geared to locations with high device density, such as stadiums. It is designed to support peak speeds of 10Gbps using both 2.4 and 5 GHz spectrum (real world top speeds will be closer to 4.8 Gbps).
Enablers include Multiuser MIMO with four-stream downlink and uplink; simultaneous transmit/receive (STR); and OFDMA signalling, which allows it to move up to 1024 QAM modulation. The extra capacity, then, is achieved by counting in multiple bands; having both ends speak at the same time (STR); and supporting MU-MIMO on the uplink as well as the downlink. Overall, speeds should be four times those of the current top end spec, 802.11ac.
The first company to publicly launch an 802.11ax chip was Quantenna last October, and that product sampled in the first quarter of this year. Qualcomm Atheros followed in Feb-ruary and is sampling around now; Broadcom is only announcing its silicon now, while some Taiwanese, Chinese and Korean companies have done demonstrations of some of the technologies, though they have not actually announced chips yet.
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