Broadcom today announced the availability of a new phone-based Wi-Fi chipset, the BCM4389. The new chipset offers support for Wi-Fi 6 and, more interestingly, Wi-Fi 6E.
For those who are not immediately familiar with the latest alphabet soup, Wi-Fi 6E is not a new protocol at all. Instead, it is a brand name for 1200 MHz of additional spectrum in the 6 GHz range. The FCC has not yet officially approved public use of this spectrum, but its chairman, Ajit Pai, has expressed a wish that the agency proceed "quickly" when approved in September. Broadcom's decision to design and approve the actual hardware for use in the spectrum clearly assumes that 6E will become "one thing" sometime this year.
We'll talk a little bit about why Wi-Fi 6E is important before we look at features that are specific to BCM4389 itself – far beyond a simple "connect to 6E if available".
Why Wi-Fi 6E is important
This histogram shows the difference between a noisy 5 GHz channel and a clean 6 GHz channel.
Please note that these are PHY speeds, not throughput rates. However, the difference in throughput should be easily scalable with the PHY. No protocol magic is needed here, only channels that are double wide and not crowded.
We're a little doubtful of how much Wi-Fi 6E you need for in-vehicle entertainment – but it would be surprising for AR / VR where throughput should be high, cables are an abomination, and latency as well.
Honestly, the jury is still not sure how great Wi-Fi 6 really is. Although the Broadcom vice president we spoke to confidently stated that "OFDMA works quite well with Broadcom chipsets and the 4389 is no exception," the manufacturer's unaffected RF engineers we spoke to have one other story written. Even if Broadcom's designs consist of 100% solid OFDMA, this is absolutely not the case for most access points, telephones and laptops, as Tim Higgins from Smallnetbuilder has confirmed in detail.
Without OFDMA, Wi-Fi 6 is a pig in a poke. The protocol offers other functions that are out of the question, such as: B. 1024QAM coding with higher bit rate for devices with very good connections. However, OFDMA is the really mind-blowing feature that Wi-Fi 6 is designed to perform much better and more consistently in crowded environments.
Wi-Fi 6E is in a much better position to show obvious, instant improvements to the fit of the pants as it becomes available. Because of the use of 1200 MHz contiguous, non-congested 6 GHz spectrum, it can offer seven non-overlapping 160 MHz channels compared to 5 GHz two or three 80 MHz channels if you are lucky , This means much easier channel planning for businesses and a much lower chance that neighboring networks will be inevitably congested if you are an urban resident.
In addition, the 160 MHz channels actually mean twice the available throughput – and the lack of older devices in the spectrum means that no old, slow devices devour the entire transmission time. The somewhat lower range and the lower throughput of 6 GHz compared to 5 GHz, which Broadcom characterized as "approximately 10% -20% less range", should also be considered a feature and not an error.
Keep in mind that reduced range and penetration not only means that my router doesn't go that far, it also means that my neighbors' networks don't conflict with my network as much. We are confident that a widespread introduction of 6E will ultimately result in the death of the hugely expensive standalone router and the final move to Wi-Fi mesh APs (or networkable APs) for everyone.
For those of you who want to find out in advance what the slightly reduced range and penetration means to you, we will soon have significantly more detailed recommendations for an access point placement feature. (A really short rule of thumb – which has not changed exactly from 5 GHz, we are now only serious about it – is to plan no more than two walls between the access point and the station.)
Why the BCM4389 is important
BCM4375 is the chipset that powers the WiFi of the Samsung Galaxy S10.
We would recommend taking the actual numbers here with a grain of salt – but "faster, lower latency, lower performance, faster pairing, better BT headphone experience" should be a reasonable assumption due to the technological improvements.
Broadcom's process shrinkage from 28 nm to 16 nm is good for improving power consumption. Adding a low power radio for background scans and wake up calls is even better.
"MIMO BT" is a trademark, not a technical specification, and it is a little misleading. What it really refers to is the beam-forming TX and MRC RX on the chipset radio.
As always, we warn readers against accepting information from providers that have not yet been checked by third parties with a grain of salt. But the technological improvements in the BCM4389 definitely look convincing.
Lower power consumption
A new Broadcom chipset, the BCM4375, powers the WLAN in Samsung's S10 flagship phones. Although our own Ron Amadeo didn't like the S10 + he tested and none of us like the Samsung software, I haven't heard any complaints about the WiFi or the battery life of the S10 line. Therefore use the BCM4375 of this telephone as a reference point for the comparison with the new BCM4389.
First, the power consumption in the BCM4389 should be drastically reduced. Broadcom's process size shrank from 28 nm to 16 nm, which alone should lead to a significant decrease in consumption. It is more interesting, however, that Broadcom has added a new third radio to the new chipset.
The BCM4375 was able to maintain a Wi-Fi connection in both the 2.4 GHz and 5 GHz bands simultaneously, as was the new BCM4389. But there is also a third radio with a much lower power consumption than the other two, which can be used for background scanning (to determine which Wi-Fi SSIDs are available on which channels) and to allow the main radios to go to sleep of inactivity. The TBS radio can detect incoming communications and activate the corresponding large radio in time to receive it without any of the large radio having to waste power when idle.
Faster, better Bluetooth pairing
BCM4389 also brings serious improvements in the pairing of Bluetooth devices. The low-power TBS radio enables much faster scanning for available devices – Broadcom claims the pairing time has improved two to three times.
In addition to the shorter pairing times, Broadcom has added a new feature to its Bluetooth functionality called "BT MIMO" to reduce user problems in technologically crowded environments. BT MIMO is a marketing term, not an established term, and it will likely seem a little misleading to many readers – it does not refer to increasing bandwidth by using multiple spatial streams like Wi-Fi SU-MIMO.
Broadcom's BT MIMO is the use of Beamforming Transmit and MRC (Maximum Ratio Combining) to improve connections and reduce operational latency for connected Bluetooth devices. The company states that by directionally isolating the signals in this way, skipping and stopping audio data is reduced due to the presence of many other active Bluetooth devices. BT MIMO does not require any special functional support from connected devices. it works entirely in the telephone chipset itself.
We don't have a BCM4389 that we can use to test BT MIMO, but we suspect that it falls into the "nice to have but no magic wand" category. The spatial isolation described should help to significantly increase the signal-to-noise ratio, but does not magically make CMDA / TDMA multiplexing problems go away if the competing devices are close enough to receive as Bluetooth transmission from the phone or headset itself to become. This is likely to be a feature to lessen the impact of remote noise rather than dealing with nearby crowds.
Last but not least, BCM4389 naturally brings Wi-Fi 6E support to the table. There is no additional radio for the 6 GHz spectrum. The same radio can be used twice for 5 GHz or 6 GHz connections. Although a BCM4389-equipped phone can be connected to a 2.4 GHz network and a 5 GHz or 6 GHz network at the same time, it cannot be connected to 5 GHz and 6 GHz connections at the same time.
Assuming that usage of the 6 GHz spectrum has been ratified, we expect new models of virtual reality headsets designed to be paired with phones or tablets to introduce 6E fairly quickly. The combination of the new spectrum of high throughput, low latency and short range and penetration (and therefore low congestion) is quite ideal for this type of connection.
Collection image from Broadcom