May 20, 2019
Qualcomm products mentioned within this post are offered by Qualcomm Technologies, Inc. and/or its subsidiaries.
At Mobile World Congress 2019 in Barcelona (MWC19) we showed that 5G is here — a collective achievement that we celebrated other industry leaders. But as soon as you achieve one goal, it is time to move forward to the next one.
At Qualcomm, we are excited about one set of new opportunities for 5G. Some call it industrial IOT; others call it vertical use; and, others still refer to it as part of private networks. What we’re talking about is providing much faster and more reliable mobile broadband in factories, warehouses, venues, ports, and other similar settings than what is possible today. Today, these places either use wired connectivity, and thus cannot take advantage of mobility, or they use wireless technology that cannot meet the requirements of the range of existing and new use cases in the aforementioned places like 5G can. Bringing 5G to these places can drive tremendous gains in productivity, economic growth, and other benefits. So, how do we do this? Well, as usual, we need two things: new spectrum and new technology. Let me explain...
In the U.S. and around the world, regulators are turning their attention to the 6 GHz band. This spectrum band consists of up to 1,200 MHz of new spectrum. That’s a large amount of spectrum. Most notably, in the U.S., the FCC has proposed allocating this spectrum as unlicensed (see FCC Notice of Proposed Rulemaking). Qualcomm provided comments to the FCC in mid-February. Regulators in Europe and Asia have also begun working on this 6 GHz band. In some regions, it’s possible that the band will be allocated as licensed (perhaps local licensing) or part licensed and part unlicensed.
No matter the regulatory regime that’s used from region to region, we see great opportunities to use this new spectrum, together with the new 5G technology I describe below to enable these exciting new uses.
I was delighted to see our latest spectrum sharing demonstration in February at MWC19 that showed new spectrum sharing techniques. We remotely showcased our live 5G test network in San Diego based on our Qualcomm Snapdragon 5G device modem. One crucial aspect in these demonstrations is time-synchronized operation, which is designed to provide multiple key benefits when operating in any type of spectrum. But here I will focus on its benefits when applied to unlicensed spectrum:
- Ability to use Coordinated Multi-Point (CoMP) to provide ultra-reliable low latency communication (URLLC), which we believe will be required to support some important industrial IoT applications such as factory automation.
- More predictable quality-of-service when sharing spectrum, such as lower and predictable latency and higher reliability compared to today’s asynchronous networks like Wi-Fi and LAA in unlicensed spectrum, which is a requirement for many industrial IoT applications.
- Ability to increase spectral efficiency — higher system capacity and higher data rates — from CoMP and from spatial sharing based on spatial division multiplexing (SDM) as shown in the video above.
Existing methods of sharing unlicensed spectrum use asynchronous methods
The most common spectrum sharing method used by Wi-Fi and LAA in 5 GHz today is called Listen-Before-Talk with Load-Based-Equipment (LBT-LBE). This is an asynchronous sharing protocol, where each node contends for the channel independently of all other nodes, including nodes in the same network. Basically, each node listens first to determine if the channel is free. If it is free, you may use it. If it is not free, then you follow an agreed method to wait for a little while and then try again. This is a simple method that works in many cases but has shortcomings, especially when network load increases. It also hinders the full realization of the benefits I mentioned earlier, such as predictable latency, CoMP for ultra-reliability and SDM for higher spectral efficiencies.
The technology we call 5G NR-U will support the same asynchronous approach when operating in existing unlicensed bands, such as the global 5 GHz band, to co-exist with today’s Wi-Fi and LAA. 5G NR-U will have an option similar to LAA that is anchored in licensed spectrum and primarily boosts public mobile broadband services as well as a standalone option that only relies on unlicensed or shared spectrum.
Can you have your cake and eat it too?
Spectrum is a scarce and valuable resource, so we want to make the best use possible of this resource for everyone in order to gain the greatest societal benefits. The consumer benefits of wireless connectivity are huge. At the same time, the future economic benefits from high performance private networks for Industrial IoT based on time-synchronized operation are significant. So why can’t we have both?
The challenge is that we can’t operate networks with time-synchronized operation on the same radio channel (same portion of the spectrum) alongside networks with asynchronous operation, such as today’s Wi-Fi and LAA, due to the contention mechanisms being incompatible. To realize the benefits of the synchronized sharing techniques, all networks sharing the same radio channel need to be time synchronized.
We can achieve this is if we define technology-neutral rules that support time-synchronized operation without limiting today’s Wi-Fi and LAA networks with asynchronous operation. Today’s Wi-Fi and LAA will continue to use LBT for spectrum access, but future 5G NR-U and future Wi-Fi could and should be able to take advantage of time-synchronized operation.
Qualcomm has proposed this approach: Set aside a portion of the new 6 GHz unlicensed spectrum band (e.g., the proposed U-NII-7 sub-band, which consists of 350 MHz) optimized for time-synchronized operations. If time-synchronized operations in this portion of the spectrum are not detected, then any asynchronous networks can operate on the channel as is the case in the rest of the band (proposed U-NII-5, U-NII-6 and U-NII-8) as well as 2.4 GHz and 5 GHz U-NII bands.
Under this approach, an asynchronous node could support functionality to detect time-synchronized operations in the part of the spectrum optimized for time-synchronized operation. If time-synchronized operation is not detected, then the node can operate in asynchronous mode. If time synchronized operation is detected, then the node can either operate in a manner compatible with time-synchronized operations or operate asynchronously in another portion of the spectrum.
That means that asynchronous networks can access the entire band while at the same time,time-synchronized operations can be deployed in a portion of the band for high performance use cases, all while ensuring the spectrum is shared fairly between the networks.
A great opportunity
The proposed 6 GHz unlicensed band in the U.S. will provide an excellent new spectrum band to enable advanced spectrum sharing techniques with increased service predictability and improved performance. Our proposals for synchronized sharing in a portion of the 6 GHz band are technology agnostic and apply equally to today’s Wi-Fi, LAA, and 5G NR-U and its future evolutions. It proposes precedence to time-synchronized operations in a portion of the band to accommodate technology advancements, while still supporting asynchronous Wi-Fi and LAA. This will allow the 6 GHz band to support faster mobile broadband and at the same time better quality of service required for these exciting new industrial IOT/private network/vertical uses.
This new spectrum sharing paradigm, which builds on time synchronization, is not limited to unlicensed spectrum. These synchronized sharing techniques could also be beneficial in spectrum that is allocated as licensed (particularly licensed locally) or shared, especially for local networks where there will be extensive boundaries between the networks. Consequently, the potential for this technology is truly global. Let’s grab this opportunity to define the 6 GHz unlicensed spectrum band in the U.S. as the first step toward broader, global use of synchronized sharing.
To learn more how 6 GHz and other spectrum bands can be used for private 5G networks in industrial IoT, please listen to our webinar “The Role of 5G in Private Networks for the Industrial IoT”.