# 6G Mobile Networks: Key Technologies, Directions, and Advances
## 4 6G Technologies
### Spectrum-Sharing  
In order to handle the issue of variable spectrum demand across various networks, spectrum sharing is widely adopted. On the one hand, it's crucial to expand the spectrum that is presently usable, including the terahertz and visible light spectrums. On the other side, it's also necessary to alter the guidelines for spectrum operation. The majority of permitted carriers used by cellular networks are spectrum resource owners, who also have the only right to utilise the spectrum. In fact, if spectrum coffers are momentarily unused, no one else has a reason to utilise them. Strict limitations and criteria apply to users' customised pointers and operating ranges within the alone approved spectrum. It may be utilised for a long period and successfully prevents interference between systems. Despite the high level of stability and reliability of this system, there are still problems, such as inefficient bandwidth utilization and idle applications caused by the allocated frequency spectrum of authenticated persons. The conflict between forces and demands on the spectrum is exacerbated as a result [12]. The 6G's terahertz-frequency features raise the viscosity of its network. Dynamic diapason sharing has emerged as a key tool for improving spectrum efficiency and streamlining network construction. In order to comply with the requirements of the 6G system's spectrum resource operation, dynamic spectrum participation makes use of a knowledgeable dispersed diapason sharing access medium that can dynamically increase the available spectrum range and optimise spectrum operating regulations. The advancement of blockchain, variable spectrum allocation, machine learning, as well as other techniques in order to achieve intelligent spectrum sharing and 6G network security is another advantage [12]. In [49], the reshaping of the spectrum by customised innovation has been demonstrated. The commons and property models are advocated by lawyers, but there are additional systems to consider as well, each with their own advantages. In different bands, many models might be used. Models should be given names based on practical concerns for perpetration. The activities must come first and foremost. Should unlicensed spectrum bands be used instead of certified primary spectrum druggies? It varies. With its stringent QoS requirements, licensing works well for television broadcasting [50]. Due to their irregular transmissions and ability to retransmit, wireless connections between computers and string modems perform better across unlicensed airwaves. Should secondary bias coordinate via a dynamic secondary request or employ spectrum opportunistically? It varies. Technically speaking, opportunistic access is easier if agent broadcasts are predictable, as they are with broadcasters [51]. Although there are no QoS assurances for secondary bias, this is acceptable for certain (but not all) processes [52]. On the other hand, if agents are cellular carriers, the dynamic secondary Request would be more appropriate since, with a little cooperation, several secondary biases can transmit while still protecting the QoS of both cellular visitors and secondary bias [49]. In [5], in relation to the ongoing purposeful effort to adopt successful changes towards how they managed and utilised radio spectrum, it has provided a complete overview of major trends, unplanned reform activities, and research issues. It is difficult to use spectrum properly and to its full capacity since the majority of the traditional spectrum administrations now in use are highly strict and inflexible. Devoted exclusive-use contracts, based on outmoded radio-technological accessories, reduced the drive to use spectrum efficiently and caused problems with artificial failure, impeding the creation of innovative wireless technology and services.