# Blockchain-Based Licensed Spectrum Fair Distribution Method towards 6G-Envisioned Communications
## 3 BEAST System Model
### System Process
This priority index is meticulously calculated, taking into account two critical factors: the temporal arrival of the resource request and the trustworthiness assessment of the requester. In essence, the priority index acts as an equitable determinant, ensuring that honest nodes with a higher trust value are granted a correspondingly elevated priority index. This priority index, in turn, becomes the key factor in dictating the order in which spectrum resources are allocated. By placing high-priority requests at the forefront of the allocation queue, we achieve a streamlined and efficient process that optimally serves the needs of legitimate users. Crucially, the integrity of this priority-based approach is fortified with the immutability and transparency of the blockchain. Each and every demand for spectrum resources is meticulously documented and indelibly recorded within the blockchain's secure framework. This distributed and tamper-proof ledger ensures that every honest MNO can accurately perceive and access the spectrum demands lodged with the PBS and PU nodes. This visibility, rooted in blockchain's transparency, empowers honest MNOs to promptly recognize and respond to resource requests in accordance with their priority index. As a synthesis of these intricately woven mechanisms, our system exhibits a robust and compelling ability to resist censorship. The amalgamation of priority indexing, trust evaluation and blockchain-backed transparency culminates in a framework where honest PBS and PUs are equipped with the means to surmount any adversarial attempts at censorship with malicious actors or MNOs. In this fashion, we are confident that our system's architecture comprehensively safegueuards the principle of censorship resistance, reinforcing the fundamental ideals of impartial access and the equitable distribution of vital spectrum resources. Other common attacks include identity forgery, data tampering, data theft, etc. Data theft is a kind of passive attack, which mainly destroys the confidentiality of information. Data tampering is a kind of active attack, which mainly destroys the integrity and availability of information. And a forgery attack is when an attacker simulates a legitimate identity and sends false information. These attacks can be solved with blockchain technology and other mature technologies. ### Experiments

We deploy our algorithm on the Ethereum test chain, and the time cost and gas cost of the three main function in the spectrum distribution smart contract are obtained. Table 3 shows the cost for different functions of our contract. For different kinds of 6G wireless applications in the future, the time cost is within the acceptable range for the users. In this paper, we propose a blockchain-based spectrum primary-level distribution method (BEAST) to realize fair and secure spectrum distribution in a 6G network. BEAST introduces a trust-value-based PoT consensus to improve block generating efficiency. BEAST is modeled under the universal composability (UC) security framework and evaluated in the Ethereum test chain. Compared to the fair allocation scheme based on penalties in [15] and weight-value-based scheme in [16], our method achieves two-level fairness. That is, the fairness among spectrum users and the fairness in the consensus protocol. Meanwhile, compared to the others, in addition to providing privacy protection, BEAST can provide similar privacy preservation and security guarantees to a blockchain-based spectrum allocation scheme, such as Block6 Tel [29], the scheme in [30] and TCPP [11]. Furthermore, due to the introduction of PoT, BEAST improves the transaction efficiency from a seconds to milliseconds grade, which is more suitable for the various near real-time applications. ## 6 Conclusions

This paper deals with the licensed spectrum management for 6G networks. Blockchain technology is introduced to solve the unfairness flaw during the spectrum distribution process. And blockchain can also provide surveillance and auditing to the MNOs' service performance.