This article will cover a variety of 5G challenges and solutions. Although 5G has the potential to meet future high data rate and bandwidth demands, there are still some big difficulties to overcome in order to make 5G a reality. We're transitioning from 4G to 5G technology as the number of connected devices to the internet grows fast. The demand for IoTs (Internet of Things) and sensors is steadily increasing these days. For many years, connected vehicles, vehicle-to-vehicle communication (V2V), and vehicle-to-infrastructure (V2I) was a major concern. To connect a large number of devices to a base station, we need more bandwidth as compared to 4G to ensure that all devices can communicate smoothly. The 5G millimeter wave band, on the other hand, offers ample spectrum resources to meet the demands. Now we'll talk about 5G's difficulties and possible solutions:
Main challenges for 5G:
1. Due to the extremely high frequency, there is a significant path loss in omnidirectional EM wave transmission.
2. Due to the very short wavelength, there is a high penetration loss.
3. Interferences and infrastructures
4. Because the coverage zone is small, billions of APs are required.
5. Safety and Privacy
Possible Solutions:
Beam forming and directional transmission to combat high path loss:
As we know, extremely high frequency or millimeter waves suffer from significant path loss due to their high frequency and short wavelength, as they are easily absorbed by air gases, vapor, and other substances. As a result, such a high frequency wave can only travel a short distance through the atmosphere.
To maximize SNR at the receiver, we use directed transmission or beam forming. By using this techniques, extra gain is added, such as transmitter and receiver gains. In contrast, if we increase the strength at the transmitter or make the beam narrower, we can expect longer distance communication than before (without beam forming).
Microcell, APs to combat high penetration loss:
It can barely penetrate thick obstructions due to its high frequency and short wavelength. High frequencies, on the other hand, are more reflective and refractive. It is easily refracted or refracted by barriers such as building walls, glasses, and other objects.
As a result, connecting an outdoor node (in this case, a communication node) to an indoor node is problematic.
We can APs (access points) for indoor in this circumstance. Then we'll be able to link it to outside networks. APs can be used to make microcells. Then we can connect a macro cell to several microcells. The macro cell will then be connected to the BS, and the BS will be connected to the macro cell through backhauls.
Enabling device to device (D2D) communication and repeaters:
For this case, especially for microcell 5G communications, we can employ device to device communication (D2D) to obtain higher spectrum efficiency. Because such communication is ideal here because interference is reduced due to high path loss, and if beam forming is used, it is a significant benefit for D2D communication. You know, if we put APs everywhere, we'll need billions of them to connect (especially, for indoor communication node). To simplify the system, we can use repeaters to replace many APs. This is cost effective also.
Security & Privacy:
All users and personal data should be secure. 5G service providers have to ensure it. Hackers may have access to a large amount of data with high-speed and ubiquitous connections of 5G. That is something that 5G companies must keep in mind.
We also know that the beam forming technique effectively reduces the chances of eavesdropping and jamming (by jammer) at the local level.
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What is s11 and s21 of MIMO antenna
MIMO system was invented to increase the system's capacity. Here capacity of the system increases linearly with the number of antennas at transmitter and receiver increases. But there is a main issue arises in MIMO system is that interference between multiple antenna elements.
MIMO is an important feature of Wi-Fi 4 and 5, as well as 3G and 4G cellular networks. This method was developed to improve the capacity of a channel by sending many data streams simultaneously over a single channel. In a MIMO system, all simultaneous data streams are encoded orthogonally multiplexed, which lowers interference. Massive MIMO is widely utilized in 5G to achieve large capacity and communicate via beam forming or directional transmission.
Here in MIMO systems we can use different types of diversity (time, space, and frequency diversity - three are three main type of diversity) to improve Quality of service (QoS) by reducing inter-element (antenna) interference. We can use different types of different types of polarization and pattern diversity, i.e., LP (linearly polarized antennas), CP (circularly polarized antennas), etc. to cancel interference between MIMO antenna elements. That diversity techniques are widely used in WLAN systems.
Diversity is a technique where, especially, in case of MIMO system, multiple antennas can enable multiple data streams between transmitter and receiver simultaneously. Now, interference occurs in that system if there is no diversity. We know in case of time diversity you can send multiple signals to multiple devices using different time slots. Similar thing happens in TDM (time division multiplexing) modulation system. You know in 2G GSM we use TDM to connect 8 devices to BS thru same channel by 8 different time slots.
Now, we can also reduce interfaces between multiple antenna elements by using good inter element isolation. For that we need to design MIMO antenna elements accordingly so that we can achieve high gain. That is also recommended for higher WLAN frequencies.
In case of designing MIMO antennas we generally get the terms like, S11, S21, S31, etc. Here, S21 represents the reflected signal power from element or antenna no 2 due to transmission from element or antenna 1. Obviously, that causes interference if the intensity is above the acceptable level. Usually, isolation less than -20 dB is considered as good isolation for typical MIMO systems.
Usually, transfer of power between antenna to antenna are measured in dB or decibel. It is a logarithmic scale. In our case it is 10*log(reflected power / total transmission power). Here base of the log is 10.
