Blockchain-Enabled Dynamic Spectrum Access: Cooperative Spectrum Sensing, Access and Mining

Traditionally, dynamic spectrum access (DSA) based on cooperative spectrum sensing relies on a centralized fusion centre to fuse and store the sensing results, which is vulnerable to single point of failure. In this paper, we propose a sensing-based DSA framework which is enabled by blockchain. The proposed DSA framework includes a protocol that specifies a time-slotted-based five-phase operations. In the proposed framework, each secondary user (SU) acts as both a sensing node for cooperatively sensing the spectrum and a node, i.e., a miner and a verifier, in the blockchain network for mining and updating the sensing and access results in a distributed and secure manner without the need for a fusion centre. In order to incentivize SUs for participating in such energy-consuming operations of the blockchain network, we reward them with tokens for sensing and mining, which can be used to bid for the access to the spectrum opportunities. The sensing and mining policies which they use to determine when to sense and mine affect the number of tokens they can obtain and subsequently how they bid for the spectrum. Hence, the performance of the system depends on their sensing-access-mining policy. Therefore, we consider a heuristic sensing- access-mining policy that determines whether to participate in sensing and mining in a probabilistic manner and that determines how much to bid based on its buffer occupancy and the number of available tokens. Simulation results show that although increasing sensing and mining probabilities can increase average transmission rate, it also leads to higher energy consumption. Moreover, there exists an optimal set of sensing and mining probabilities that maximize the system energy efficiency.