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Broadcom Unveils New FiFEM Modules to Refine Its Wi-Fi 7 Chips’ Performance

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Broadcom today announced its next step in Wi-Fi 7 optimization, the FBAR integrated front-end module (FiFEM) devices for all Wi-Fi access point (AP) applications.

These new devices can be added to the company’s existing Wi-Fi 7 chips to better the performance of standalone access points, routers, or residential gateways.

FiFEM family
The new FiFEM modules designed for Wi-Fi 7 from Broadcom

Front-end module: Conventional FEM vs. Broadcom’s new FiFEM

Each Wi-Fi broadcaster needs a FEM, an essential accompanying RF module that consists of acoustic filters, amplifiers, and other parts. The FEM decides how signal broadcasting of each radio band takes place and plays an important role in other characteristics of a broadcaster.

FEM and Wi-Fi 7

Like all internal parts of a radio broadcaster, FEMs are generally delicate and easily susceptible to environmental elements, such as sound waves. That’s especially true with the 6GHz frequency band, available in Wi-Fi 6E and Wi-Fi 7.

Additionally, Wi-Fi 7 has many new features that put even more stress on the FEM. Two examples:

  • Multi-Link Operation (MLO) combines multiple bands into a single link, making the coexistence of 5GHz and 6GHz signals a critical part of Wi-Fi hardware.
  • The automated Frequency Coordination (AF) feature means the radio frequency (RF) broadcasting power can reach up to 10 Watts per band (instead of the current 1 Wat ceiling). Consequently, FEM optimization will play an even more important part in Wi-Fi 7 broadcasters.

New to Wi-Fi 7? The cabinet below will fill you in.

Wi-Fi 7 in brief

Wi-Fi 7 has four major improvements over existing standards.

1. The all-new 320MHz channel width

The first thing to note about Wi-Fi 7 is the new and much wider channel width, up to 320MHz, or double that of Wi-Fi 6/6E.

This new channel width is generally available on the 6GHz band, with up to three 320MHz channels. However, Wi-Fi 7 can also combine portions of the 6GHz and 5GHz bands to create this new bandwidth—more in the Multi-Link Operation section below.

Details of Wi-Fi channels can be found here, but the new channel width generally means Wi-Fi 7 can double the base speed, from 1.2Gbps per stream (160MHz) to 2.4Gbps per stream (320MHz).

So, in theory, just from the width alone, a 4×4 broadcaster 6GHz Wi-Fi 7 can have up to 9.6 Gbps of bandwidth—or 10Gbps when rounded up. But there’s more to Wi-Fi 7’s bandwidth below.

Wi-Fi 7 also supports double the partial streams, up to 16. As a result, technically, a 16-stream (16×16) Wi-Fi 7 6GHz band can deliver up to over 40Gbps of bandwidth, especially when considering the new QAM support below.

Like Wi-Fi 6 and 6E, initially, Wi-Fi 7 will be available as dual-stream (2×2) and quad-stream (4×4) broadcasters and dual-stream clients. In the future, the standard might have 8×8 broadcasters and single-stream or quad-stream clients.

Again, you need a compatible client to use the new 320MHz channel width. Existing clients will connect using 160MHz at best. In reality, the 160MHz will likely be the realistic sweet-spot bandwidth of Wi-Fi 7, just like the 80MHz in the case of Wi-Fi 6.

2. The 4K-QAM

QAM, short for quadrature amplitude modulation, manipulates the radio wave to pack more information in the Hertz.

Wi-Fi 6 supports 1024-QAM, which itself is already impressive. However, Wi-Fi 7 will have four times that, or 4096-QAM. Greater QAM means better performance for the same channel width.

As a result, Wi-Fi 7 will be much faster and more efficient than previous standards when working with supported clients.

Wi-F 7 vs. Wi-Fi 6/6E: The realistic real-world speeds

With the support for the wider channel width and higher QAM, Wi-Fi 7 is set to be much faster than previous standards on paper.

You might have read somewhere that Wi-Fi 7 is “up to 4.8 times faster than Wi-Fi 6,” and hardware vendors will continue to combine the theoretical bandwidth of a broadcaster’s all bands into a single colossal number—such as BE19000, BE22000, or BE33000—which is excellent for advertising.

Like always, these numbers don’t mean much, and things are not that simple. In reality, a Wi-Fi connection generally happens on a single band at a time—that’s always true for Wi-Fi 6E and older clients—and is also limited by the client’s specs.

The table below summarizes what you can expect from Wi-Fi 7’s real-world organic performance compared to Wi-Fi 6E when working on the 6GHz.

Wi-Fi 6EWi-Fi 7
Max Channel Bandwidth
(theoretical/top-tier equipment)
160MHz320MHz
Channel Bandwidth
(widely implemented)
80MHz160MHz
Number of Available Channels7x 160MHz, or 14x 80MHz channels3x 320MHz, or
7x 160MHz channels, or
14x 80MHz channels
Highest Modulation 1024-QAM4096-QAM
Max Number
of Spatial Streams
(theoretical on paper / commercially implemented)
8 / 416 / 8 (estimate)
Max Bandwidth
Per Stream
(theoretical)
1.2Gbps (at 160MHz)
600Mbps (at 80MHz)
2.9Gbps (at 320MHz)
1.45Gbps (at 160MHz)
Max Band Bandwidth
(theoretical on paper)
9.6Gbps
(8×8)
46.1Gbps
(16×16)
Commercial Max Band Bandwidth Per Band
(commercially implemented)
4.8Gbps
(4×4)
23Gbps (8×8), or
11.5Gbps (4×4)
Available Max Real-word Negotiated Speeds(*)2.4Gbps (via a 2×2 160MHz client)
1.2Gbps (via a 2×2 80MHz client)
11.5Gbps (via a 4×4 320MHz client)
5.8Gbps (via a 2×2 320MHz client or a 4×4 160MHz client)
2.9Gbps (via a single stream 320MHz client or a 2×2 160MHz client)
1.45Gbps (via a single stream 160MHz client or a 2×2 80MHz client)
Available Clients
(example)
2×2
(Intel AX210)
2×2
(Intel BE200 / Qualcomm NCM865)
Wi-Fi 6 vs. Wi-Fi 7: Theoretical data rates on the 6GHz band
(*) The actual negotiated speed depends on the client, Wi-Fi 7 specs, and environment. Real-world sustained rates are generally much lower than negotiated speeds—capping at about two-thirds at best. Wi-Fi 6/6E has had only 2×2 clients. Wi-Fi 7 will also use 2×2 clients primarily, but it might have 4×4 and even single-stream (1×1) clients.

Like Wi-Fi 6 and 6E, Wi-Fi 7 has been available only in 2×2 specs on the client side. That, plus the sweet-spot 160MHz channel width, means, generally, it’s safe to conservatively expect real-world rates of the mainstream Wi-Fi 7 (160MHz) to be about 20% faster than top-tier Wi-Fi 6E (160MHz) counterparts.

However, the new standard does have more bandwidth on the broadcasting side. So, it can handle more 2×2 clients simultaneously with high-speed real-world rates. And that’s always a good thing.

Multi-Link Operation, or MLO, is the most exciting and promising feature of Wi-Fi 7 that changes the norm of Wi-Fi: Up to Wi-Fi 6E, a Wi-Fi connection between two direct devices occurs in a single band, using a fixed channel at a time—they use a single link to transmit data.

It’s worth noting that MLO is a feature and not the base of the standard, meaning it can be supported by a particular device or not. It’s not expected to be universally available until late 2024.

In a nutshell, MLO is Wi-Fi band aggregation. Like Link Aggregation (or bonding) in wired networking, it allows combining two or more Wi-Fi bands into a single Wi-Fi link—one SSID and connection.

There are two MLO operation modes:

  • STR-MLMR MLO (Simultaneous Transmit and Receive Multi-Link Multi-Radio): It’s multi-link aggregation using all three bands (2.4GHz, 5GHz, and 6GHz) to deliver higher throughput, lower latency, and better reliability.
  • E-MLSR MLO (Enhanced Multi-Link Single Radio): It’s multi-link using dynamic band switching between 5GHz and 6GHz to deliver load balancing and lower latency.

No matter which mode is used, the gist is that the bonded link delivers “better” connection quality and “more” bandwidth.

It’s important to note, though, that at the end of the day, MLO increases the bandwidth, allowing different applications on a client to use the two bands simultaneously. The point here is that no application on the client can have a connection speed faster than the fastest band involved. A speedtest application, for example, still uses one of the bands at a time. This connection speed is still limited by the hardware specs on both ends of the link, whichever is lower.

So, the MLO feature affords a supported client the best probability of connecting successfully at the highest possible speed using the fastest band at any given time, which changes depending on the distance between the client and the broadcaster.

MLO can be a game-changer in a wireless mesh network by fortifying the Wi-Fi link between broadcasters—the backhaul—both in terms of speed and reliability. Most systems I’ve tested had the sustained wireless backhauling link over 5Gbps at 40 feet away. In systems with wired backhauling, MLO can make seamless handoff (or roaming) genuinely seamless.

For clients, in more ways than one, MLO is the best alternative to the existing so-called “Smart Connect“—using one SSID (network name) and password for all the bands of a broadcaster—which doesn’t always work as smartly as expected.

In fact, you can think of MLO as the enhanced version of Smart Connect. Specifically, MLO requires Smart Connect for the broadcaster’s primary SSID. As a result, if the hardware doesn’t allow for additional virtual SSIDs, segmenting a network via different SSIDs (such as one for each band) is no longer an option. In other words, with MLO, you have to choose between the following in terms of SSIDs:

  • Having a primary SSID (via Smart Connect), which is MLO-enabled, and an optional 2nd virtual MLO-enabled SSID. Or
  • Turning off Smart Connect to manage the band individually and losing the MLO option.

Additionally, keep the following in mind about this feature:

  • By nature, link bonding will be more complicated than single-band connectivity—there are just too many variables.
  • MLO only works with supported Wi-Fi 7 clients. Some Wi-Fi 7 clients might not support it. Considering the different performance grades and hardware variants, the result of MLO will vary case by case.
  • Wi-Fi 6E and older clients will still use a single band at a time when connecting to a MLO SSID.
  • An MLO SSID requires the WPA2 or higher encryption method and generally won’t work with first-gen Wi-Fi 5 or older clients.
  • The reach of the bonded wireless link is as far as the range of the shorter band.

By default, the 6GHz band has just about 75% of the range of the 5GHz when the same broadcasting power is applied. That said, MLO can only be truly meaningful with the help of Wi-Fi 7’s fifth and optional feature, Automated Frequency Coordination, mentioned below.

4. Flexible Channel Utilization (FCU) and Multi-RU

Flexible Channel Utilization (FCU) (a.k.a. Preamble Puncturing) and Multi-RU are two other items that help increase Wi-Fi 7’s efficiency.

With FCU, Wi-Fi 7 handles interference more gracefully by slicing off the portion of a channel with interference, 20MHz at a time, and keeping the clean part usable.

In contrast, in Wi-Fi 6/6E, when there’s interference, an entire channel can be taken out of commission. FCU is the behind-the-scenes technology that increases Wi-Fi’s efficiency, similar to the case of MU-MIMO and OFDMA.

Similarly, with Wi-Fi 6/6E, each device can only send or receive frames on an assigned resource unit (RU), which significantly limits the flexibility of the spectrum resource scheduling. Wi-Fi 7 allows multiple RUs to be given to a single device and can combine RUs for increased transmission efficiency.

5. Automated Frequency Coordination

Automated Frequency Coordination (AFC) is an optional feature and deals with the 6GHz band, so it’s not Wi-Fi 7-exclusive—the band was first used with Wi-Fi 6E. It’s not required for a Wi-Fi 7 broadcaster’s general function. In fact, it wasn’t even mentioned in the initial certification by the Wi-Fi Alliance.

Due to local regulations, the 6GHz band’s availability differs around the world. For this reason, some Wi-Fi 7 broadcasters will not adopt it and will remain Dual-band.

Still, Wi-Fi 7 makes AFC more relevant than ever. That’s because the 6GHz band has the highest bandwidth (fastest) yet the shortest range compared to the 5GHz and 2.4GHz bands when using the maximum allowed broadcasting power. Originally, AFC was intended only for outdoor applications, but when implemented, it’s significant for all applications.

Here’s how AFC would work when/if available:

The feature enables a 6GHz broadcaster to check with a registered database in real-time to confirm that its operation will not negatively impact other existing registered members. Once that’s established, the broadcaster creates a dynamically exclusive environment in which its 6GHz band can operate without the constraint of regulations.

Specifically, the support for AFC means each Wi-Fi 7 broadcaster can use more broadcasting power and better flexible antenna designs. How much more? That depends.

However, it’s estimated that AFC can increase the broadcasting power to 36 dBm (from the current 30 dBm limit) or 4 watts (from 1 wat). The goal of AFC is to make the range of the 6GHz band comparable to that of the 5GHz band—about 25% more.

When that happens, the MLO feature above will be truly powerful. But even then, Wi-Fi 7’s range will remain the same as that of Wi-Fi 6, which is available only on the 5GHz band. Its improvement is that its 6GHz band now has a more extended reach than in Wi-Fi 6E. In other words, AFC allows the 6GHz band to have at least the same range as the 5GHz. And that’s significant.

This feature requires certification, and its availability is expected to vary from one region to another. Hardware released before that is said to be capable of handling AFC, which, when applicable, can be turned on via firmware updates.

A crude AFC analogy

Automated Frequency Coordination (AFC) is like checking with the local authorities for permission to close off sections of city streets for a drag race block party.

When approved, the usual traffic and parking laws no longer apply to the area, and the organizers can determine how fast traffic can flow, etc.

To lessen the negative effects of elements on Wi-Fi 7 broadcasters, Broadcom has created a special filter type called Film Bulk Acoustic Resonator (FBAR) to insulate the FEM.

FBAR filters are slated to be better than conventional Surface Acoustic Wave (SAW) filters by, among other things, featuring 0.3 to 0.5 dB less insertion loss and up to 50mA in current consumption.

Broadcom’s FiFEM

To differentiate, Broadcom calls FEM units with integrated FBAR filter “FiFEM”, an intimidating-sounding acronym that generally means an improved front-end module.

According to Broadcom, the new FiFEM devices “incorporate best-in-class FBAR filter technology to provide superior 5 GHz and 6 GHz
band coexistence and low in-band insertion loss while significantly reducing the bill of materials (BOM) at the RF front end.”

Additionally, they feature “state-of-the-art non-linear power
amplifier (PA) design optimized for Broadcom’s Wi-Fi SoC Digital Predistortion (DPD) operation to deliver up to 40% reduction in RF front-end power.”

To put things in simple terms, Wi-Fi 7 broadcasters’ equipment with the new FiFEM will likely deliver faster-sustained speeds, lower latency, and higher capacities than those that use conventional FEM. That’s the idea, anyway.

Here are the highlights of Broadcom’s new FiFEM products:

  • Integration of 2nd generation Wi-Fi FBAR filter that:
    • Provides superior 5-GHz/6-GHz band isolation and efficiency
    • Reduces RF BOM and board space
    • Avoids yield loss from external filter mismatch
  • First non-linear FEM qualified for Broadcom’s Wireless FEM Active Management (WiFAM) Gen2 using advanced DPD technology with dynamic bias handling that:
    • Enables up to 40% reduction in RF front-end power
    • Enhances gateway energy efficiency via average power consumption.

Most importantly, these new FiFEM devices are designed to meet the system specs of existing Wi-Fi 7 chipsets, including the BCM6726 and BCM67263 SoC reference designs first announced in April last year. And they are available in four conventional (3×5 mm) FEM packages, including:

  • AFEM-W760-HP1 (6 GHz, +25dBm)
  • AFEM-W760-MP1 (6 GHz, +23dBm)
  • AFEM-W750-HP1 (5 GHz, +25dBm)
  • AFEM-W750-MP1 (5 GHz, +23dBm)

Broadcom says it has begun shipping samples of these FiFEM devices to its early-access customers and partners. Consequently, there will likely be routers and access points with them inside sometime later this year.

The takeaway

Despite existing Wi-Fi 7 broadcasters on the market, the new wireless standard is still under development. It’s not yet certified until the end of this year or even earlier next.

These new FiFEMs from Broadcom are one of many reasons it makes sense to get still a Wi-Fi 6 or 6E router that works for your needs today. Wi-Fi 7 only gets better the longer you wait. It won’t go anywhere.

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2 thoughts on “Broadcom Unveils New FiFEM Modules to Refine Its Wi-Fi 7 Chips’ Performance”

  1. As I read this, every time Dong mentions FBAR I kept seeing FUBAR…(Sorry, from my military days). Thanks for the info as always 🙂

    Reply

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