# Spatial Positioning Token (SPToken) for Smart Mobility

## TL;DR

This paper presents a novel distributed ledger architecture for smart mobility that uses position-based tokens to enable privacy-preserving data sharing and traffic sampling without affecting vehicle autonomy.

## Contribution

It introduces a permissioned DAG-based DLT with proof-of-position and proof-of-work, enabling secure, privacy-preserving, and lightweight data sharing for smart mobility applications.

## Key findings

- Effective in sampling vehicular traffic flow without perturbing real vehicles
- Supports privacy-preserving machine learning algorithms in IoT environments
- Validated through large-scale simulations demonstrating its practicality

## Abstract

We introduce a permissioned distributed ledger technology (DLT) design for crowdsourced smart mobility applications. This architecture is based on a directed acyclic graph architecture (similar to the IOTA tangle) and uses both Proof-of-Work and Proof-of-Position mechanisms to provide protection against spam attacks and malevolent actors. In addition to enabling individuals to retain ownership of their data and to monetize it, the architecture also is suitable for distributed privacy-preserving machine learning algorithms, is lightweight, and can be implemented in simple internet-of-things (IoT) devices. To demonstrate its efficacy, we apply this framework to reinforcement learning settings where a third party is interested in acquiring information from agents. In particular, one may be interested in sampling an unknown vehicular traffic flow in a city, using a DLT-type architecture and without perturbing the density, with the idea of realizing a set of virtual tokens as surrogates of real vehicles to explore geographical areas of interest. These tokens, whose authenticated position determines write access to the ledger, are thus used to emulate the probing actions of commanded (real) vehicles on a given planned route by "jumping" from a passing-by vehicle to another to complete the planned trajectory. Consequently, the environment stays unaffected (i.e., the autonomy of participating vehicles is not influenced by the algorithm), regardless of the number of emitted tokens. The design of such a DLT architecture is presented, and numerical results from large-scale simulations are provided to validate the proposed approach.