For 5G networks in 2018, two of the five most important wireless technologies-MIMO and beamforming-have always been very important to 5G networks.
MIMO and beamforming
For LTE / 4G, the industry is approaching the theoretical limits of time and frequency utilization. The next step in 5G wireless technology is to take advantage of the spatial dimension by transmitting strictly focused signals in different directions and using any given frequency simultaneously as frequently as possible. The industry still needs to overcome challenges when using these two technologies for 5G. In 2017, these two themes have been progressing and changing, and 2018 may see more in these two areas.
Figure 1: 5G will rely on antenna arrays to provide a large number of inputs and a large number of outputs (or MIMO). Beamforming directs signals to specific devices. (Source: T-Mobile)
MIMO describes that more and more antennas are aggregated into increasingly dense arrays at the transmitting and receiving ends to create more data stream layers. At the same time, beamforming and beam tracking technology are closely related to guide each signal to the optimal path of the receiver while avoiding signal interference. Beamforming will make MIMO more efficient.
To be applied to 5G network systems, these two technologies need to be further improved.
It is still difficult to physically reduce the size of the antenna; 5G-oriented MIMO arrays are very large (this is one of the reasons that practical 5G smartphones are unlikely to come out before 2020, and perhaps later). The power consumption of most existing arrays is still too high to be completely practical.
Figure 2: The signal must be guided along two dimensions, height and azimuth, which complicates the beamforming task. (Source: Qorvo)
The nature of beamforming is as the name implies, but the term does not imply the complexity involved. In 4G, the transmitter triangulates the receiver. The same is true in 5G, but in 5G, the transmitter will also be able to map the physical environment, and then not only calculate the multipath bounce, but also calculate how to stagger the signal flow and use multipath in a way that does not interfere with the synchronization signal. The task becomes more difficult when either or both of the transmitter and receiver are moving.
All of this is further complicated by the additional inherent technical challenges in the next important aspect of 5G wireless.
The frequency originally allocated for 5G was overcrowded at 6GHz. Most of the spectrum recently allocated to 5G services in different jurisdictions around the world is distributed across millimeter wave frequencies.
The millimeter-wave range is from 30GHz to 300GHz. New 5G spectrum allocations worldwide, ranging from 20 GHz to 20 GHz (such as 26 GHz and 28 GHz, which are not technically millimeter waves, but are generally classified in this category), to several frequency bands within 30 to 40 GHz and 40 to 50 GHz Within several frequency bands. There is a 60GHz Wi-Fi band available for 5G wireless. Other higher frequencies are being considered.
Figure 3: The spectrum near and within the millimeter-wave range (30GHz to 300GHz) is particularly suitable for higher data rates, and despite its flaws, it is attractive.
On the one hand, these higher-frequency signals will support much higher data rates specified by 5G. The industry still has work to do to improve the spectral efficiency it has managed to achieve so far.
On the other hand, the transmission rate of millimeter-wave signals is significantly lower than expected. Millimeter-wave signals and signals below 6GHz cannot travel very far, nor can they penetrate obstacles.
In general, many components of 5G are still expensive, especially in the millimeter-wave spectrum. As economies of scale are driven and based on possible future innovations, further integration will definitely reduce costs.
In the previous evolution of wireless networks, the basic goal was to send data to mobile phones. That’s right, this started with a simple phone and developed to increase broadband access; yes, other types of devices are supported by 4G / LTE networks, but the vast majority of wireless network users are sending and receiving data to and from mobile phones. This will change with 5G. 5G will become the enabling technology for many IoT applications, but just as importantly, these IoT applications will help prove the correctness of 5G evolution. The use cases including the Internet of Things are actually built into the 5G technology roadmap, which is inherent in the development of the 5G market.
While many IoT devices will connect directly to 5G, others will not. Many IoT applications will rely on a large number of simple, inexpensive sensors or other relatively simple devices. These devices may require low or ultra-low power consumption; they may or may not require low latency; they may or may not need to communicate with each other; the amount of data they generate (and may receive) may vary from device to device The differences are huge; they may need to be polled in real time, or they may be polled only once a day, a week, or even a month. In many of these applications, 5G connectivity is not only an excessive waste of technology, but it is also so expensive that many of them are not economically feasible.
This is why the next theme is also very useful for the 5G market.
In many IoT applications, a large number of devices will be connected to the base station through some wireless technologies specifically designed for LP-WAN, and the base station will be connected to a high-speed and high-bandwidth network. The network may be 5G, but not necessarily; 4G connectivity is sometimes sufficient-3G is sometimes sufficient. It is also possible to have wired access nearby, it may be equally useful (if not more ideal); but in many places, there is no wired network nearby, which is conducive to the adoption of 5G network connections.
There are currently several LP-WAN options. They include LoRaWAN, Sigfox, Weightless, NB-IoT, LTE M, Ingenu, and Symphony Link. The next version of Wi-Fi 802.11ax has low-power options in the specification, and it may also be added.
Some LP-WAN technologies are proprietary and others are the result of a more inclusive development process. They are different degrees of openness. It is too early to tell which one will become popular, but it is certain that in the long run, LP-WAN has more wireless options than the market may accommodate.
In some IoT applications, the use of wireless transmission technology is not only suitable for connecting a large number of simple and cheap devices, but also for interconnecting them with each other. This is the world of mesh networks. Some LP-WAN technologies did not initially support mesh networks, but now almost all technologies provide support.
Mesh networks are not unique to LP-WAN. It has been incorporated into wireless LAN technology. Zigbee and Thread support mesh technology from the beginning, Bluetooth has added it, and it will be included in the next version of Wi-Fi. This next version of Wi-Fi is called 802.11ax, also called Max (look at “11ax”-turn the first 1 over and it faces the other 1 and together it is an “M”)
Wireless mesh networks can certainly be useful in 5G. In a local area network where all connected devices are stationary, the mesh network is not yet easy to make; considering mobile devices (walking people, drones, cars), the difficulty is getting worse. The industry is starting to make 5G support for mesh networks.