LED Backhaul Project Engineer Blog

What's Li-Fi? (5) Will Li-Fi be used in smartphones? (Part 2)

Last Update: Oct 11th, 2021

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Introduction.

In Part 1, I explained why Li-Fi is not and has not been incorporated in smartphones and notebooks. The reason was not that it could not be physically built in, but that Li-Fi was inferior to Wi-Fi in terms of speed, and there was no pure advantage to having it, but that could be solved by using laser diodes (LDs) as the light source. However, even if the light source of Li-Fi is now an LD, and even if it is able to stably transmit at over 2 Gbps, will Li-Fi become as popular as Wi-Fi, or even if not as popular as Wi-Fi, will it become so popular that ordinary users will see it? This is what I am talking about this time. As I emphasized in the previous article, the content of this article is also the author's "personal forecast as an optical wireless communication engineer. It is not the official opinion of the company (Sangikyo).

About Wi-Fi 6

The basic premise of Li-Fi diffusion is that the "minimum" speed that Li-Fi must beat is Wi-Fi. There is also 5GNR (or Beyond5G, 6G) as a means of communication, but that is "cellular" that requires a contract, so we consider it different. Wi-Fi is now in the process of transitioning from Wi-Fi 5 (IEEE802.11ac) to Wi-Fi 6 (IEEE802.11ax), and the most important feature of Wi-Fi 6 is that it uses OFDMA. Up until now, Wi-Fi has been an extension of wireless Ethernet, and has followed the Ethernet principle of "start communication on your own, and retransmit if you can't transmit because of a collision with another. In order to overcome this shortcoming, Wi-Fi 6 has abandoned the Ethernet way of thinking and has adopted the cellular way of thinking. With Wi-Fi 6, the AP assigns a transmission time and subcarrier to each terminal, and each terminal moves accordingly, eliminating collisions within an area and improving overall area throughput and connection stability. If Wi-Fi 6 becomes widespread in the future, it will dramatically improve the experience of communication in places where people gather, which has been a problem until now.

Wi-Fi 6 Status and Issues

Theoretically, there is no reason not to use Wi-Fi 6, since it would be a good thing to implement, and I thought, "Won't it spread rapidly? I thought it would spread rapidly, but it seems that it is not as widespread as I expected. Here is a list of the latest (or close to it) smartphone models from two OS developers and three major manufacturers, sorted by grade (including models that will not be released in Japan).

model name	manufacturer	price range	cellular support	Wi-Fi support
iPhone 13	Apple	High	5G	6
iPhone SE(2)	Apple	Middle	LTE	6
Pixel 5	Google	High	5G	5
Pixel 5a	Google	Middle	5G	5
Galaxy S21	Samsung	High	5G	6
Galaxy M22	Samsung	Middle	LTE	5
Galaxy A03s	Samsung	Low	LTE	5
Mix4	Xiaomi	High	5G	6E
11T	Xiaomi	Middle	5G	6
Redmi 10	Xiaomi	Low	LTE	5
Reno 6 Pro 5G	OPPO	High	5G	6
Reno 6 Z	OPPO	Middle	5G	5
A35	OPPO	Low	LTE	4

As you can see, the only devices that support Wi-Fi 6 are high-end devices that support 5G. There are also a number of devices that support 5G but do not support Wi-Fi 6, such as Google. I also checked other manufacturers (Huawei, ZTE, etc.) and found the same trend of "high-end only" support. (Incidentally, as far as we can tell, the only phones that do not support 5G but do support Wi-Fi 6 are the iPhone SE and some HUAWEI Whether or not Wi-Fi 6 is supported is probably due to the chipset, but in other words, it's not worth changing chipsets to support Wi-Fi 6. In other words, for smartphone manufacturers (except Apple), Wi-Fi 6 is just an add-on to 5G support.

The fact that "new standards take time to spread" wasn't much of a problem until Wi-Fi 5, which was a feature addition compared to the previous generation, so the first adopters were the first to benefit. Wi-Fi 6 will use a very different method of communication. Wi-Fi 6 uses a very different method of communication, and yet the old and new Wi-Fi systems use the same frequencies, so if Wi-Fi 5 or lower APs and devices are mixed in with Wi-Fi 6 areas, the scheduling and collision methods will be mixed, and the full benefits of Wi-Fi 6 will not be realized^*1. Of course, Wi-Fi 6 is backward compatible and there are many complicated features to avoid the above problem, but even if you do that, the effect of Wi-Fi 6 will still be reduced. Therefore, it would be desirable for everyone to switch to Wi-Fi 6 at once, and I'm sure the smartphone manufacturers are well aware of this...

What I'm trying to say about Wi-Fi 6 is that smartphone manufacturers (other than Apple) are not actively working to increase Wi-Fi speed. Maybe even 5G is only added because it's a "selling point" and not because it's a functional necessity. If you think about it, we haven't seen any smartphone that takes advantage of 5G performance in the first place, not even the $1,000+ iPhone 13Pro or the Samsung foldable. Smartphone manufacturers are very serious. They won't adopt useless features that cost money and don't "sell". They will support "5G" because it is a selling point, but they don't care about "Wi-Fi 6" because it is not a selling point. In other words, smartphone manufacturers must have decided that a simple increase in communication speed will not lead to sales.

Demand for Li-Fi as a high-speed communication application

Even so, cell phone base stations will eventually be replaced by 5G, and in 5 years, almost all new smartphones released (in telecom-advanced countries) will be 5G-compatible, and Wi-Fi 6-compatible along with them. And since AP manufacturers who are expecting replacements will also actively recommend Wi-Fi 6 support, notebook PCs will also become Wi-Fi 6 compatible.

So, after the spread of 5G + Wi-Fi 6, will there be a need for higher speed communication than 5G + Wi-Fi 6?　For example, for downloading, even now the communication speed is faster than the storage speed of the server or terminal, which is a "speed overload" situation. Rather, the problem for wireless communication in the future will be real-time transmissions that require "medium speed but stability," specifically, IP simulcasting of TV and cloud streaming games. However, the current largest real-time content is "BS 8K" and its speed is about 80~90Mbps, which is not so difficult to achieve after the spread of Wi-Fi 6...

So, is it possible that smartphones and laptops will never be equipped with Li-Fi just because they can communicate faster than Wi-Fi? In my personal opinion, unfortunately, the possibility of Li-Fi being installed for high-speed communication purposes is close to zero. If content that requires higher speed communication than currently expected becomes popular... For example, if uncompressed video is desperately needed, the situation may change, but based on the content we see now, we cannot assume that this will happen.

So is Li-Fi unnecessary?

So is there no possibility of Li-Fi being used in smartphones and laptops? I think there is a possibility that Li-Fi will be installed in notebook PCs, taking advantage of its original features such as security and high-density installation. For example, Li-Fi is suitable for educational PCs and tablets. For example, Li-Fi is suitable for educational PCs and tablets, as each classroom can have its own communication without interference, and the security of the school network can be ensured by using different communication than usual. However, this is an extremely limited application, and it is not an answer to the theme of this blog, "Will it be used in smartphones? However, this is a very limited use and does not answer the question "Will it be used in smartphones?

There is a possibility that Li-Fi will be used for contactless communication in a more numerous application that will answer the question "Will it be used in smartphones?". Since smartphones these days are naturally waterproof, they don't want to use connectors such as Lightning or Type-C as much as possible. If you've been shooting 4K videos, you probably know that the file size of a video is huge! If you've been shooting 4K video, you know that the file size is huge! If I had to sync all this stuff to the cloud, it wouldn't matter how much I paid. If you want to sync all this data to the cloud, it doesn't matter how much you pay, you need to connect to the mothership. In order to avoid this, you can use a wireless charger with Li-Fi for contactless communication as shown in the figure. Since the distance is so close, Li-Fi will be able to provide a stable speed of 1 Gbps or more, which is not quite as fast as Thunderbolt4/USB4.0 that can communicate at 40 Gbps, but much faster than Lightning, so it should be enough to send 4K video. It should be able to do the job of sending 4K videos. This could be called one of the "wirelessization of short-range wired communication" that I discussed in previous article.

Summary After all...

5GNR and Wi-Fi 6 will surely become more widespread as chipsets in smartphones and PCs support them, even if the speed is not fast enough. However, as far as the current world is concerned, or even looking ahead five years or so, there is no demand for communication at the terminal level that can exceed Gbps. Therefore, no matter how fast the Li-Fi communication speed becomes, if there is no "need" for it, smartphone manufacturers will not adopt it. On the other hand, I think there is a possibility that Li-Fi will be adopted in places where its inherent merits can be utilized, such as high-density installation and security, especially for educational PCs, but that is only for special terminals.

Now, as I have explained in two articles, "Will Li-Fi be used in smartphones? I'm sorry to say, but I have to say that it is extremely unlikely. This is not because of Li-Fi's technical reasons, but for the reason that the need for higher speed communication is diminishing. If a groundbreaking service comparable to the iPhone in 2008 comes out, and if stable high-speed communication is needed for smartphones and PCs, then perhaps Li-Fi will be used in smartphones.

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