# From 5G to 6G--Challenges, Technologies, and Applications
## 4 Current Research
### Analytical Summary  
In this section of our work, we layout a summary of some of the main papers working on B5G/6G technologies that have been published in the last year. Our findings are shown in Table 3. We discuss here one entry from each category for brevity. For example, the researchers in [118] presented a qualitative analysis of different waveform designs for joint communication and sensing (JCAS) in different 6G scenarios. They concluded that for lower carrier frequency ranges, they can use OFDM for JCAS, as they do not require a strict low-peak-to-average power ratio (PAPR), while single carrier modulation is a better option for higher frequencies (sub-terahertz). The researchers in [122] presented a timeline of the best known quasi-optimal techniques deployed in current multi-beam antennas and the techniques envisioned for 6G networks. It is envisioned that using terahertz frequencies, very narrow multiple THz beams with low probability of intercept (LPI) can be created from physically very compact areas, but the signal attenuation will be severe. AI is a key player in 6G networks, and the literature is rich with 6G-AI implementations. One example is [126], where the researchers identified AI's role in 6G networks to be crucial in novel services, such as auto-encoding, end-to-end modeling, and predictive resource allocation. Security in 6G has gained the central focus of researchers: in [128], new physical layer security (PLS) protocols were designed with priority placed on the optimal use of time-frequency resources, such as PLS security insertion into MIMO precoders. Blockchain is inevitably the way to go in 6G to maintain easy and secure access to heterogeneous parts of the network. In [132], the researchers considered a two-hop edge-caching--which is anticipated to be widely deployed in 6G networks--scheme using blockchain and PLS to preserve data integrity and security. The design was based on deploying a limited version of blockchain for all network users, which would allow them to publish transactions, but not data blocks. Moreover, the two-hop transmission scheme could effectively reduce backhaul traffic and relieve network congestion. Sixth-generation network management is also of great concern to researchers: in [136], a new scheme for bandwidth allocation was proposed and was based on orthogonal and non-orthogonal multi-access resources to meet 6G's passive optical networks' stringent requirements. The results showed that the proposed scheme was able to handle ultra-high throughout in the order of terabits per second combined with latencies down to sub-100 \(\upmu\)s. Lastly, the architecture of 6G is expected to be shaped by numerous new technologies, such as virtual mobile small cells, as proposed in [140]. The small cells are controlled via distributed SDN controllers and are expected to meet the 6G networks' requirements, such as extremely low latency and reliable communications.  
We follow this discussion by building on Table 2 and give an overview of the different works in the literature that have examined future networks beyond 5G over the past year in Table 4.