Wi-Fi 6/6E has brought about a new spectrum that greatly enhances the Wi-Fi experience with improved user experience along with the generation of greatly increased revenue streams.

The purpose of this page is to provide insight to the design benefits and concepts of utilizing Wi-Fi 6 and 6E within a Tri-Band AP. Unique technical and business implications of incorporating a dedicated listening radio in the design are explained. The new generation of Tri-Band APs will enable optimal use and utilization of the 2.4, 5 and 6GHz bands.

Readers will learn the benefits of using the Wi-Fi 6/6E spectrum with examples of use cases/products which will greatly benefit from the new 6GHz spectrum along with the addition of a Listening Radio and its features.

The 6GHz Spectrum

The newly added Wi-Fi 6GHz band has huge economic potential and will enable new and exciting industry applications. For example, multi-room gaming as well as AR/VR will benefit from the low latencies and large capacity that the 802.11ax technology brings to the user.

Let’s take a look at the new available spectrum shown in Figure 1.

The new 6GHz spectrum shown in blue within the entire Wi-Fi band
Figure 1. The new 6GHz spectrum shown in blue within the entire Wi-Fi band

Wi-Fi 6+6E Example Use Cases and Related Product Variants

Use Case Example Product Variant
Multi-Gigabit Wireless Network (AP) Tri-Band broadband gateway/AP (2.4+5+6 GHz)
(AP) Tri-Band mesh nodes
(AP) Tri-Band extenders
4K/8K Video to Multi-Screens (AP) Tri-Band multimedia gateway (may be part of broadband gateway)
(STA) Set-top box (switchable 2.4/5/6 GHz)
(STA) Connected screen/TV (switchable 2.4/5/6 GHz)
(Link) 6GHz video-link (video gateway to STB/video bridge)
AR/VR & Gaming (STA) Connected AR/VR goggles
(STA) Connected game control
IoT (AP) Dual-band (2.4+5) or Tri-Band (2.4+5+6) IoT gateway
(STA) connected sensors/controls/things
5G backhaul (Link) 5G CPE (mm wave ODU) connecting to the indoor gateway

Example Applications:

Tri-Band Broadband Gateway

Tri-Band Broadband Gateway—a high-resolution 4K stream to a smart TV streaming from Netflix, will reduce the Wi-Fi speed available to your other devices. A Tri-Band router is essentially hosting three separate Wi-Fi bands offering more capacity to allow for higher speeds to more devices.

Tri-Band Extender

This technology boosts Wi-Fi to the extreme, eliminates Wi-Fi dead zones and extends Wi-Fi range to hard-to-reach areas of the home, such as from a garage to the backyard. A Tri-Band extender can have a dedicated band backhaul link, such as the 6GHz band, while serving clients over the 2.4 and 5GHz bands.

Tri-Band Mesh Nodes

These are designed to replace your complicated router-and-extender setup with multiple identical units placed around your house that are used together. This has advantages over a traditional extender. Mesh nodes are aware of each other, and they wirelessly forward traffic around the network as necessary. All the mesh nodes broadcast the same network name, so the Wi-Fi devices are enabled like phones and laptops to roam between mesh access points as they choose. This makes the handoff much more seamless than extenders. In addition, mesh units are all running the same software, and can relay traffic much more intelligently. So if a user is connected to the second node on the far side of the dwelling, it will just rebroadcast packets if the client in question is actually connected to it. Tri-Band Mesh nodes can have a dedicated band for the backhaul link.

AR/VR & Gaming

Artificial Reality/Virtual Reality sets require high bandwidth and low latency. With Wi-Fi 6E, users can get connectivity wirelessly not needing to be tethered to the wiring that may limit their user experience.

5G Backhaul

6E Wi-Fi will help enable high-speed connection between the high-speed transmission links to the building (5G CPE - millimeter wave wave ODU) and the AP which is usually located in the home living room. Adding 1200 MHz of spectrum will enable this connection. There will be less interference, better performance, and more uncontested airtime.

The New Normal: Tri-Band 6+6E is Becoming the New "Entry Level" AP Infrastructure

In Wi-Fi 5, a dual-band AP was typically used to utilize the 2.4 and 5 GHz bands. High-end AP solutions offered Tri-Band designs that used low and high frequencies on the 5GHz band to enable simultaneous use of three bands. However, a Tri-Band of 2.4, 5 Low and 5 High came with many challenges. The costs were very high and in terms of design there was a challenge to operate two radios on adjacent frequencies in the 5GHz band. Without proper filtration, the two radio systems would block and interfere with each other. The extra complexity and cost of the Tri-Band solutions were accepted by the market because such products were positioned as higher-performing than the conventional dual-band APs.

Now, new APs aiming to support the promising 6GHz band have to consider the installed base of legacy clients using the 2.4 and 5 GHz bands. This means that they must support 2.4 and 5 GHz bands in addition to the new 6 GHz band. Tri-Band will become the new norm, or the new entry-level for APs.

The different AP infrastructure types and their band support are illustrated in Figure 2.

AP Architectures and Band Support for Wi-Fi 5 and Wi-Fi 6/6E
Figure 2. AP Architectures and Band Support for Wi-Fi 5 and Wi-Fi 6/6E

We have already discussed Wi-Fi 6/6E use cases and derived Wi-Fi AP architectures which include Tri-band AP and how network devices utilize the 6E/6GHz band. Now, let’s discuss design considerations when you want to develop a device that supports all of those bands.

The Benefits of a Tri-Band AP

We will now discuss the cases where it makes the most sense to add better spectrum agility and a sensing radio when designing your box.

Utilize the 6GHZ Band

6GHz adds a new spectrum that will enable better channel utilization and increased throughput. However, on day one, most client devices will most likely operate at 2.4GHz or 5GHz and will not necessarily support 6GHz. A Tri-Band design will enable the new generation of Wi-Fi 6E devices to benefit from the new band. The solution will also support a topology that would not be hard-wired limited in the many geographies that still do not have 6GHz available or in areas that do not have the devices that can benefit from the 6GHz. Both 5 and 6 GHz interfaces are necessary for a good design.

6GHZ Band Can Utilize Higher Throughput

The 6GHz band doubles the effective throughputs compared to the practical throughputs achieved in the 5GHz and 2.4GHz bands. Because legacy devices will not operate on the 6GHz band, it will be used exclusively for Wi-Fi 6 traffic which will improve performance further compared to the congested 2.4GHz and 5GHz bands.

Dedicated MAC/PHY and RF for Zero-Wait DFS Packet Capture/Sniffing Spectrum Analysis

Having the ability to enrich a design solution with insights of spectrum sensing and of zero-wait DFS, will enhance and position the product as a high-performing/high-value asset as compared to conventional products that do not support this functionality.

Packet Sniffing is the process of monitoring every packet that is passing through a network and provides insights on which frequency channels are used and how crowded they are. Sniffing capabilities in an AP design will provide better efficiency by selecting the best channels for maximum communication efficiency.

Value and Cost Benefits of Including a Dedicated Listening Radio in a Wi-Fi AP

Wi-Fi networks that exist in a dense environment often overlap with one another. This can result in interference and poor connectivity due to the close locations of the Access Points (AP).

One means to ensure high performance/high value is the addition of a better spectrum agility to those engineered devices.

The Benefits of a Tri-Band AP with a Listening Radio

  • Better visibility of interferers
  • Smarter channel selection
  • Having the ability to refresh the AP's view of the entire spectrum and its current congestion statistics faster can improve the AP’s performance enormously, and yield proactive actions (e.g. transition to a higher power channel if available) or to a less occupied channel
  • Optimized whole network channel assignment
  • Avoid overlapping channels and potentially interfering with each other

In many countries, regulatory requirements may limit the number of 5 and 6 GHz channels available or place additional restrictions on their use because the spectrum is shared with other technologies and services. For instance, in the US and other countries, some of the Unlicensed National Information Infrastructure (U-NII) bands are used by radar systems. Wi-Fi networks operating in those bands are required to employ a radar detection and avoidance capability. The Wi-Fi standard addresses this requirement by adding support for DFS and transmit power control (TPC) on every DFS channel. In DFS, the system would need to listen for one minute of silence, or ten minutes of silence before using this band. This can cause service interruption.

The Need for Better Utilization of DFS Channels

Zero-Wait-CAC a.k.a. Dynamic-In-Service-Monitoring (North America)

  • Monitoring a DFS channel in parallel to operation - Clearing the DFS channel by performing Channel Availability Check (CAC) of 1 or 10 minutes just before using the DFS channel.

Off-Channel-CAC, a.k.a Zero-Wait-DFS (Europe)

  • Monitoring a DFS channel in parallel to operation – verifying lack of Radar signals.
  • Once pre-clearance is completed, the AP can store the channel scan status and use the channel at any given time (without the need to perform a long CAC, as required in North America).

There is an added value and benefit of monitoring other channels during service.

Advanced Radio Capabilities with a Dedicated Listening Radio

  • Interference characterization - an access point can monitor a channel for a long duration period (Continuous Monitoring)
  • Spectral analysis of the scanned channel to characterize the interference
  • Coexistence between neighboring APs – enabling smart management of power and access policies
  • Sniffing and Debugging Connectivity Issues
  • Sniffing and decoding packets on the scanned channel to build longer-term statistical characterization of interferences or channel occupancy

A dedicated listening radio is not bounded by the needs of sharing RF resources (e.g. certain antenna, RF synthesizer) or MODEM resources (e.g. the MAC, PHY, DSP, DFS circuitry) between the Prime channel service and the scanning function.

How is a Dedicated Listening Radio Different from Other Methods of Listening?

A dedicated listening radio is much more capable than a single radio sharing service/scanning roles.
A dedicated listening radio performs the scan in parallel to the prime modem, and not in a limited timeshare fashion.


Tri-Band AP Plus - AP with a Built-in Listening Radio – An Optimal Design with the CL8000 Product Family

Renesas' unique chipset architecture allows a full Tri-Band Plus dedicated listening radio with no extra costs and no additional host interface needed, with only a minor BOM population.

It provides a dedicated resource that is fully parallel to main serving radios:

  • No frequency hopping, no context switching, no time scaling, and no MIMO downsizing
  • Covers the complete 5 and 6 GHz bands (5.15GHz to 7.125GHz)

A single listening antenna enables:

  • Spectrum sensing, channel occupancy, and utilization characterization
  • Zero-Wait DFS with dedicated DFS circuitry
  • Packet sniffing (promiscuous mode) of beacons and management frames. Enabling characterization of the overlapping APs for better cross-network optimization (channel and power settings)

The CL8000 Chip

Our range of high-performing, highly integrated Wi-Fi 6 (802.11ax)/6E (6GHz band) single PCIe chips deliver the best Wi-Fi network performance for their size by combining two Wi-Fi 6 radios into a single 11x11mm PCIe chip. The chips employ two concurrent dual-band Wi-Fi 6 modems.

The unique chip architecture provides a built-in 4th radio transceiver for advanced interference mitigation and spectrum scanning.

CL8000 Chip
Tri-Band Architectures

Unique Chip Architecture

The CL8000 chipsets interface to the Host over a single PCIe 3.0 Dual Lane port. This interface supports very high data rates. The two PCIe lines wired to each chip in the above diagram represent the 2 lanes of the interface.

This solution is unique in the sense that it incorporates two transceivers supporting two bands in a single chip which requires only one PCIe interface. As depicted in the diagram above, other vendor solutions typically support only one band in each chip; therefore, to achieve the same Tri-Band solution they use more chipsets, requiring more PCIe interfaces to the host CPU. The number of PCIe ports can become critical as host CPUs typically have a limited number of ports.

Since each chip can support full dual-band functionality, we can use one chip for supporting 2.4 + 5 GHz bands (such as the CL8080) and a second chip for 6GHz + Sensing/listening radio (such as the CL8086). This additional chip capability will not incur the cost of an extra chip and interface as required by other vendor solutions.

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