Broadcom Takes Wi-Fi to the 'Max'

Wi-Fi has been a mainstream technology for the better part of three decades. Despite the longevity of the technology, it still has problems keeping up with the needs of todays mobile user.

Consider an event like Enterprise Connect. Prior to the opening keynotes, when people are sending out tweets and Snapchats making fun of Dave Michels or Kevin Kieller, everything seems fine. Then the keynote starts and stuff stops working -- no tweets, Facebook updates, or emails. Some people will just give up on posting to social media or doing anything else online. Others might only use their mobile phone. I actually carry a mobile hotspot specifically for those times I know Wi-Fi will be spotty. The fact is, it shouldn't be this way, but bandwidth-chewing applications that are synchronous in nature have evolved much faster than Wi-Fi. Wi-Fi speed has steadily increased but it still doesn't handle multiple users or large file uploads very well.

This week Broadcom announced a line of silicon that supports "Max WiFI," Broadcom's term for 802.11ax, the 6th generation of Wi-Fi. Unlike other generations of wireless LAN, the ax standard assumes a world where the amount of traffic being uploaded is equal to that being downloaded. Products that use the Max WiFi chips will have about 4x the download speed, 6x the upload speed, 4x better coverage, and up to 7x battery life than today's 802.11ac products. The improvements in Wi-Fi are made possible by the following features:

• OFDMA -- 802.11ax include something called orthogonal frequency division multiple access, which comes from the world of LTE. Traditional Wi-Fi allocates a channel to a client and then holds it open until the transmission has ended. OFDMA slices the channels into tens or even hundreds of smaller sub-channels, each with a different frequency. Whenever there is a gap in transmission, a different client can fill in that spot. OFDMA can multiplex up to 30 clients on each channel, making the network much more efficient. OFDMA has greatly improved the congestion issues with LTE and should do the same with Wi-Fi. The feature also enables fine grained quality of service for high-bandwidth, latency-sensitive applications via advanced uplink and downlink scheduling.
• Target Wake Time (TWT) -- One of the reasons why battery life suffers in client devices is that they're always checking to see if the AP is available and ready. If the AP is busy, the client needs to keep checking. With TWT, the APs tell the clients it's time to sleep and then provides a schedule of when to wake. These times are literally milliseconds between sleeping and waking, but this will have a significant impact on battery life.
• Spatial frequency re-use -- This feature improves channel capacity efficiency by enabling the APs to make smarter decision on when to transmit data.

802.11ax also includes Multi-User MIMO (MU-MIMO), which was introduced with 802.11ac wave 2. This further increases capacity by allowing multiple devices to communicate with the AP simultaneously.

Broadcom released three chips for different uses cases. The BCM43684 is for residential Wi-Fi, and the BCM43694 is aimed at enterprise APs. These two chips have the following features:

• Support for 4-streams of 802.11ax
• 4.8 Gbps PHY Rate
• 160 MHz Channel Bandwidth
• 1024 QAM Modulation
• Uplink & Downlink OFDMA
• MU-MIMO
• ZeroWait DFS
• AirIQ Interference Identification
• Full compliance to IEEE and WFA 802.11ax specifications

The third chip, BCM4375, is for smart phones and includes these features:

• Support for 2-streams of 802.11ax
• Bluetooth 5.0+ including Low-Energy Long Range (LELR)
• Real Simultaneous Dual-Band (RSDB)
• 1.429 Gbps PHY Rate
• 1024 QAM Modulation
• OFDMA
• MU-MIMO

Now that the chips are available to early access partners, it's likely we'll see the first consumer APs by early 2018, with an outside chance of late 2017. The enterprise devices will follow, and then the client devices. Given the major changes to this standard, it's likely we'll see faster uptake of ax than we did with ac wave 2.

Good quality Wi-Fi is no longer an option. Digital organizations are looking to gather data generated off the Wi-Fi network to make better decisions, but people won't use it if the experience is poor. 802.11ax is bringing an entirely new approach to Wi-Fi and is something network managers should be educating themselves on now.

Broadcom is one of the dominant suppliers of silicon to the networking vendors and its family of chips should enable an ecosystem of devices and APs to come to market quickly. Network managers should be starting the educational process now, as 802.11ax products are literally around the corner.

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