# 6G Mobile Networks: Key Technologies, Directions, and Advances
## 4 6G Technologies
### Terahertz-Communication  
Terahertz waves are electromagnetic waves with wavelengths between 0.1 mm and 10 mm, and frequencies ranging from 0.1 to 10 THz. The intermediate and very far infrared light are separated by frequency. Between macro and microelectronics, THz swells in real time. Terahertz communication offers the dual benefits of a strong transmission rate and an abundance of diapason coffers [12]. This is a successful wireless broadband access (Tb/s communications) technology for future mobile dispatching. The Federal Dispatches Commission was there in September 2018 at the World Mobile Congress (FCC) of the United States stated that 6G can utilise THz diapason-grounded networking and spatial multiplexing technology. Terahertz technology is a frequently emerging technology that will alter the future of the planet. Terahertz technology's widespread use is a key aspect of 6G. The ultra-wideband technologies include the following, depending on the 6G technology network and business conditions:  
1. Proposals for transmission channels for terahertz space & terrestrial communications that are comparable in terms of channel size, modeling, and algorithms. 2. THz Straight transmission, terahertz mongrel modulation, waveforms, multichannel coding, and terahertz broadcast modulation are a few examples of terahertz signal coding and modulation techniques. 3. Synchronous THz transmission, essential transmitter architecture, increased baseband, signal technology computation, and design of integrated circuits methodologies are some examples of the research and development that goes into Radio wave system and THz tower architecture [12]. 4. Trials and error with the terahertz communication network and outfit developmental progress. In comparison to wireless optic and fryer transmissions, terahertz swells offer additional benefits. Broad application possibilities exist for terahertz surges in space dispatches, broadband wireless security access, and high-speed and short-distance wireless dispatches:  
1. The air's humidity readily absorbs the terahertz spike as it travels through it. Additionally, it is appropriate for wireless high-speed and close-range communication. 2. The beam is more focused, has greater directionality, and is more capable of interfering. 3. Wider bandwidth and an advanced frequency characterise terahertz swells. They are able to satisfy the need for dB of wireless broadband transmission. The potential diapason bandwidth is knockouts of GHz, and the terahertz surge diapason has a frequency between 108 and 1013 GHz. It is capable of communicating at speeds more than Tb/s. 4. The frequency of terahertz waves is a clear window in the atmosphere itself around bands of 350 \(\upmu\)m, 450 \(\upmu\)m, 620 \(\upmu\)m, 735 \(\upmu\)m, and 870 \(\upmu\)m for communication in outer space. They are able to communicate across great distances with less power and reduced transmission rates. 5. The Terahertz wavelengths, which have a limited spectrum, can also be used for Massive MIMO with extra antenna rudiments. 6. Despite having a better energy efficiency than wireless optical communications, terahertz swells photon energy is very low--roughly \(10^{-3}\) eV. There is just 1/40 th of visible light. It has an exceptionally high energy efficiency while carrying information. 7. Robust penetration Matter may be accessed by terahertz waves with less attenuation. In certain unique instances, they're appropriate for communication requirements [12]. In [41], the goal is stated, and it offers various key technologies encountered in THz wireless communication systems as well as a thorough literature analysis on the advancement of THz dispatches. THz solid-state superheterodyne receivers, high-speed THz modulators, and THz antennas still need to be developed despite the considerable difficulties. Additionally, two different kinds of lab-position THz communication systems are provided roundly, separately: a solid-state THz communication system and a spatial direct modulation THz communication system.