Development of a blockchain consensus evaluation platform for dynamic spectrum management

Abstract

A founding principle of spectrum regulation is to ensure the efficient use of the limited natural resource of radio spectrum.

In 2015, the Citizens Broadband Radio Service (CBRS) emerged as a three-tier Dynamic spectrum management (DSM) framework, enabling diverse spectrum users to co-exist within the 150 MHz spectrum between 3550 and 3700 MHz in the USA. The Spectrum access system (SAS) is crucial to this framework, ensuring incumbents enjoy priority access and protection against interference. The SAS allows licenced tier 2 Priority access license (PAL) users to access the spectrum through a bidding mechanism while also mitigating potential interference from unlicenced tier 3 General authorised access (GAA) users. A critical aspect of this system is the registration of PAL Citizens Broadband Radio Service Devices (CBSDs) with the SAS, which manages interference across all tiers and designates PAL protection areas (PPAs) to isolate PAL services from harmful interference.

Current implementations reject CBSD requests that encroach on existing PAL PPAs, which require manual resolution between PALs. This binary decision logic can be improved by allowing PALs to accept additional CBSD requests if the PPA encroachment is deemed acceptable or geographically irrelevant.

Research efforts have explored incorporating blockchain into CBRS, optimising access and controls around GAA users and improving spectral utilisation through smart contracts. Some researchers have considered using consensus algorithms to grant CBRS participants more autonomy rather than relying solely on the SAS.

This study specifically aims to integrate blockchain-inspired consensus algorithms into the PAL CBSD registration process, allowing existing PAL CBSDs to vote on the inclusion of new CBSDs, thus democratising additions and reducing dependence on the SAS. A platform was developed to compare three consensus algorithms based on coverage, encroachment, average Signal-to-interference-and-noise ratio (SINR), and channel sharing ratio. The simulation results are promising, with one example allowing 123.77% more CBSDs while increasing allowable encroachment from 0% to 1%, while only reducing the SINR by 0.1743 dB, and increasing the total area encroached by 0.2%.

The CBRS implementation could potentially be applied to other frequency bands, indicating the broader applicability of these concepts of democratisation.