5G latency is less than 1 millisecond and will it replace Wi-Fi? Not true!

As the fifth generation of mobile communication network, 5G technology has always attracted much attention, especially as the "2020 commercialization" plan is getting closer. At present, governments of various countries are also vigorously deploying and promoting the development and application of 5G networks. However, some "legends" about 5G are becoming more and more bizarre, so we think it is time and necessary to clarify it for everyone in front of the screen.

Since we have already mentioned the topic in the title, let's talk about the issue of "5G network latency is less than 1 second". Latency refers to the time it takes for a data packet to travel from the sender to the receiver. In other words, half of the Ping latency is also called one-way latency. Sometimes, latency refers to the round-trip time for a data packet to be transmitted, which is the same as Ping latency.

In different application scenarios, the latency requirements of 5G networks are also different. For example, in the eMBB scenario, the 5G NR user plane latency (one-way) is 4ms; in the URLLC scenario, the 5G NR user plane latency (one-way) is only 0.5 ms; and the control plane latency is longer, at 10ms. Therefore, it is obviously one-sided to say that "the 5G network latency is less than 1 millisecond."

Next, let's take a look at the issue of "5G will replace Wi-Fi". What do you think of cellular networks and Wi-Fi? The former moves from outdoor to indoor, while the latter moves from indoor to outdoor. The two complement each other and share the wireless traffic. Neither is indispensable, let alone one replacing the other. While cellular networks are evolving from 4G to 5G, Wi-Fi technology is also continuing its own evolution, from 11n to the now widely popular 11ac, aiming to bring us faster and more efficient network connections.

In fact, 5G high-frequency signals are difficult to get indoors because of its shortcomings in indoor coverage. Therefore, when facing the ever-evolving video and IoT applications, we still need to rely on Wi-Fi to supplement coverage and capacity. Therefore, we say that 5G is not to replace Wi-Fi, but the two should work together to expand the scale of the wireless ecosystem .

Do you agree that 5G was born to replace 4G? In fact, the initial 5G is very similar to 4G, and the network deployment mainly uses the existing 4G base station resources. It can be said that this is a very smooth evolution process from 4G to 5G.

Initially, 5G was deployed in NSA mode, which means expanding network capacity and coverage based on existing 4G. However, regardless of whether it is NSA or SA deployment mode, 4G will continue to provide voice, data and IoT services for a long time and coexist with 5G. If 5G wants to have a large-scale impact on society, it still needs time to evolve, which is not possible at this stage .

It is said that 5G not only has a high investment cost, but also has high charges? As we said above, early 5G uses 4G base stations and supporting resources to co-locate, so from the perspective of single-station scale, it can save capital investment to a large extent; and the commonly believed "5G investment is high" is because 5G needs to use higher frequency bands and build more small base stations, which increases the overall investment. But this cannot be generalized, and specific analysis should be made based on the specific deployment plan of the operator.

Therefore, regarding the tariff issue of 5G networks, it will definitely be cheaper than 4G . Since the 5G spectrum efficiency has increased exponentially, the cost per BIT has decreased exponentially. Under the trend of fierce price wars, the tariffs are bound to become cheaper and cheaper.

Is Massive MIMO necessary for 5G? Not at all. We say that Massive MIMO (massive distributed antennas) can greatly improve spectrum efficiency, capacity, and coverage. However, this does not mean that Massive MIMO is perfect. It is mainly reflected in the fact that the antenna will be larger and heavier, and the tower may not be able to bear the load. Not only that, power upgrades and backhaul upgrades are required. It can be applied to some sites, but Massive MIMO cannot be deployed for all sites because it is very uneconomical. Therefore, the low-frequency coverage layer generally uses 4T4R, the mid-frequency capacity layer uses 8T8R or 64T64R, and the millimeter wave high frequency band uses 128*128 or higher-order Massive MIMO.

5G can only be small base stations? Not really, babies. Although higher frequency bands mean smaller coverage of wireless signals, and therefore more base stations need to be built, 5G is not limited by spectrum resources and can be deployed in low, medium, and high frequency bands, which means that 5G has both macro base stations and small base stations . When operators consider 5G full coverage, they usually use low frequency bands as coverage layers, medium frequency bands as capacity layers, and millimeter wave high frequency bands as high capacity layers (hotspots); instead of deploying them all as small/micro base stations, which would cost a lot, so how could operators be so stupid?

***, let's talk about 5G and autonomous driving. There are rumors that "autonomous driving must use 5G", so does autonomous driving need 5G? It depends on the specific level, because autonomous driving is divided into 5 levels (L1-L5), from freeing hands to freeing eyes, and then to unmanned driving.

Among them, if L1 to L4 can collect data through local cameras, radars, lidars and other sensors to achieve local decision-making and control, then at the L5 stage, it is necessary to expand the perception range through network communication to make up for the lack of perception capabilities of local sensors, so as to achieve 100% safety decisions.

Now, the issuance of 5G licenses is imminent, so let us wait and see!