# Revolution or Evolution? Technical Requirements and Considerations towards 6G Mobile Communications
## 6 Enablers for 6G and Relevant Technical Preparation and Implementation
### New Coding Techniques  
With the development of 5G networks, the upgrading of communication technology and devices has been approaching [PERSON]'s limits. In the traditional [PERSON] information theory, the correct transmission of information can be achieved based on the forward error correction coding schemes. However, as the number of IoT devices increases, it is very challenging to import massive data into the core network, and network blocking and service quality decline can easily occur. Moreover, the existing modulation and coding techniques are insufficient for the 6G applications operating in the THz band.  
Therefore, new coding techniques are crucial for various 6G use cases. For IoT applications that require short packets, the low-density parity check (LDPC) codes and polar codes with short block lengths have been employed for 5G systems for use in traffic and control uplink/downlink channels. However, codes with short block lengths have reduced reliability such that error-free transmission cannot be easily guaranteed [112]. This can lead to an increase in the error probability and a higher requirement for retransmissions, which is not suitable for 6G applications involving ultra-low latency requirements or limited energy capability. Furthermore, low-energy applications are often not suitable for retransmissions, because this requires the device to stay in a non-sleep mode for an extended duration, leading to an increase in energy consumption.  
On the other hand, codes with longer block lengths usually result in increased latency. Therefore, new coding strategies should both encompass forward error correction and include novel iterative retransmission/feedback mechanisms and ML-based methods. For long codewords in channels without fading, existing methods, such as turbo decoding and belief propagation, are highly efficient and able to operate close to [PERSON]'s theoretical limits [113].  
In [114], several THz signal coding and modulation techniques, such as high-speed and high-accuracy acquisition and tracking mechanisms, waveform and channel coding, THz direct modulation, THz hybrid modulation, and THz broadcast modulation, have been proposed.  
Meanwhile, in [115], a cognitive information transmission based on a 6G \"mailbox theory\" has been proposed. The mailbox theory requires a smaller amount of data for transmission while achieving higher reliability of decision-making using cognitive information transmission. It is based on the concept of a twin intelligent agent that integrates communication, computing, and caching capabilities. It features self-organization, self-learning, self-adaptation, and continuous evolution capabilities based on information value. The  
Figure 9: Classification of the potential multiple access techniques for 6G. * Note 2: Ref. [109], * Note 3: Ref. [110], * Note 4: Ref. [111], * Note 5: Ref. [108].  
process of interpreting information value is dependent on data attributes such as polarity, dependence, figurability, convergence, dynamics, and traceability.