From millimeter wave to low frequency band, what you should know about 5G basic technology
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5G networks are coming, and this next generation of wireless communications is powered by a new technology called millimeter wave (mmWave). Carriers in the United States are particularly interested in this technology, so it may be used to varying degrees around the world. However, not every 5G network has to use mmWave technology, at least not yet. As with every new technology, there will inevitably be some early problems and obstacles to overcome before it becomes mainstream. Over the past few years, mmWave technology has been questioned by more than a few skeptics, who question whether the technology is suitable for long distances, whether it can penetrate walls and even rain, and whether users can even block mmWave signals with their hands. These doubts and opinions are not without basis, but most of them have been solved in recent years. Before millimeter wave technology is about to be officially unveiled to the public, let's take a look at some of the current problems and status of this technology. First, let's quickly review what millimeter wave is. Millimeter wave overview Millimeter wave and 5G are almost synonymous, but there are still some obvious differences between them. Millimeter wave technology is only a part of the future 5G network. Some of you may have heard of "low-band" frequencies and "sub-6GHz," both of which will also be part of the 5G standard and, when combined, will provide users with faster data connections, among other benefits. Millimeter wave refers to a portion of the radio spectrum between 24GHz and 100GHz with very short wavelengths. There is little use in between these bands, so the goal of millimeter wave technology is to significantly increase the available bandwidth. Lower-band TV and radio signals, as well as current 4G LTE networks (typically between 800 and 3,000 MHz), are more crowded by comparison. Another advantage of millimeter wave's short wavelength is that it can transmit data faster, albeit over a much shorter distance. Simply put, low-band waves cover much greater distances but offer slower data speeds, while high-band waves cover smaller areas but can carry much more data loans. Millimeter wave is only part of the 5G vision, but operators are particularly fond of hyping the 5G concept because it allows access to extremely high bandwidths and has demonstrated impressive data connection speeds. The goal of millimeter wave is to increase available data bandwidth within densely populated areas. It will be a key component of 5G in many cities, providing connectivity for data in stadiums, shopping malls, and convention centers, basically anywhere there may be data congestion issues. In rural townships, low-frequency bands below 6Ghz and below 2GHz may play a more important role in ensuring consistent coverage. Mythbusters: mmWave Fact and Fiction mmWave can't go through walls This is probably the most common problem we'll encounter with the upcoming 5G networks, and to some extent it's true. Most building materials, like cement and brick, attenuate and reflect high-frequency signals, causing so much loss in the process that it's unlikely we'll get a very useful signal from inside to outside. Even airborne transmission causes signal loss, which limits frequencies above 28GHz to a range of about 1 km. Likewise, wood and glass attenuate high-frequency signals to a lesser extent, so you can still get 5G mmWave signals next to windows. This reflective property works both ways, so you don't need a 5G antenna to receive the signal. 5G networks will use beamforming to direct the waves away from or around obstacles on your phone. This is partly because 5G devices use multiple antennas to send and receive signals, combining data from multiple streams to strengthen the overall signal and increase bandwidth. This works both outdoors, by bouncing off buildings, and indoors, by bouncing off walls. And carriers can install these beamforming transmitters in stadiums or large shopping malls. To sum up, very high-frequency 5G signals don't travel very far, nor do they transition well from indoors to outdoors. However, massive MIMO and beamforming ensure that strict line of sight is not required to use millimeter wave. Millimeter wave signals may not penetrate buildings, but they will bounce around them to ensure a good signal. Indoors, users will have to rely more on sub-6GHz and LTE signal connections. Hands can't penetrate it either Similar to the reasons mentioned above, this statement also has some truth. The human body is quite "good" at blocking high-frequency radios. After all, most of the human body is made up of water and is quite dense. This is also part of the reason why Bluetooth headsets often fail to work properly when the phone is blocked by the body. 51)]While our hands may not block the entire signal, they will certainly block some of the signal transmission, making an already average or poor signal worse or even unusable. This can at least slow down the network connection or cause data flow interruptions. In the worst case, the mobile phone signal blocked by the hand will result in a single signal or even no signal. The solution to this problem is to install more millimeter wave antennas around the phone. After all, in most cases we will use our hands to block both sides and the top of the phone at the same time. According to Qualcomm's reference design recommendations, smartphones should use three antenna modules to ensure comprehensive signal coverage. If you want to upgrade to a 5G hotspot that can handle the additional power consumption, you will need to go through four processes. The three antenna modules mentioned do not need to be turned on at the same time. The smartphone will automatically choose to switch these modules on and off based on the module that receives the best coverage to reduce power consumption. 5G doesn't work when it rains It sounds like it couldn't be worse, but that's not to say that 5G doesn't work completely in the rain, at least there's some truth to it. Just like the first two points, precipitation in the air adds extra density, which can attenuate the signal as it travels, and too much humidity can cause the same problem. This isn't a new phenomenon for 5G, though. Rain-out is a common problem for modern GPS and other high-frequency satellite communications systems, which of course operate in space all the time, but 5G can have problems at distances of just a few hundred meters. When it rains, the millimeter wave signal strength decreases, which will first result in slightly slower speeds and then potentially connection problems. How much it attenuates depends on how heavy the rain is and other factors, such as distance from the tower. Rain causes the biggest problems when the connection location is at the edge of range to a millimeter wave base station. Millimeter wave harms health I've mentioned before that I'm not going to use anything to "beautify" conspiracy theories. No, absolutely not. Of course, I still welcome comprehensive research to help us better understand any risks, but there are already reliable signs of health risks from 5G. Millimeter wave coverage is not wide enough Millimeter wave is undoubtedly the shortest distance technology for next-generation networks, but it is not so short that it becomes "useless". Base stations may provide directional coverage of up to one kilometer, but considering the influence of obstacles and trees, a distance of 500 meters may be a safer choice. Obviously that's not a very large area, so more base stations would be needed clustered closer together to cover the same area that 4G networks currently cover. That's why we're unlikely to see mmWave deployed in rural areas or small towns. It'll probably only be used in urban centers, where it's needed to cover the maximum number of consumers in a small space. Remember, mmWave technology is just a small part of the much larger 5G spectrum. Sub-6GHz and low-band spectrum like Wi-Fi should be able to reach where higher-frequency signals can't, providing backbones that still offer fast data speeds. 5G isn't as fast as Gigabit LTE, so what's the point? We've already seen our first Gigabit LTE networks turn on, offering speeds faster than we can actually use, so what's the point of expensive new 5G technology? Speed and reduced latency are two big selling points for consumers, and 5G just makes that more attainable. While 4G LTE can reach Gigabit speeds or higher in ideal conditions, in many countries there simply isn't enough spectrum or capacity available for users on existing LTE networks to deliver those speeds. 5G is about increasing available bandwidth by using a wider spectrum, making Gigabit and higher speeds more attainable. In addition, the final launch of the 5G standalone specification in the next few years will bring many technical improvements. This will lead to some more meaningful changes in application scenarios such as 5G's ability to power supply, large-scale IoT and smart cities. 5G and millimeter wave: the next big thing? Millimeter wave technology is the cornerstone of the upcoming 5G networks, which support faster data speeds and higher bandwidth than ever before. The technology has limitations, mainly in terms of coverage and propagation, but it's still viable. Carriers and equipment vendors such as Samsung and Qualcomm say that current 5G prototypes are working very well. While carriers love to tout their new technologies, millimeter wave isn't the only area of spectrum that's helping to build next-generation networks. I'm still on the fence about how much of an impact 5G will have on the way we use our smartphones. I'm still waiting for that must-have app, so to speak. 5G's promise of faster data speeds, potentially replacing the need for wired fiber, lowering latency for AR and VR applications, and improving mobile connectivity are all pretty good for us. Therefore, millimeter wave is a key part of building the next generation of 5G applications.
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