# CoNTe: A Core Network Temporal Blockchain for 5G
## 1 Introduction
Tendermint provides for scaling up and down by implementing federation in consensus that creates smaller clusters of consensus that overlap to guarantee a minimum byzantine fault tolerance [13]. These smaller clusters of consensus allow for controlled network segmentation and isolation, but lose the ability to deploy permissionless, as network topology and membership must be known to enforce its consensus cluster overlap for fault tolerance. The Stellar project is structurally similar to Tendermint, but it does not guarantee fault tolerance [14]. This federated model of consensus that removes fault tolerance but still guarantees safety and liveliness was named Federated Byzantine Agreement and first appeared with Stellar. Removing the guarantee of fault tolerance has the added benefit of allowing the consensus model to be used permissionless, but, because Stellar also includes a native currency, its ledger is monolithic and cannot be made temporal, so long as any participant carries a balance or need to transact on a previous history. In each of these systems, a work around for perpetual storage, and to assign a lifecycle terminus, is to use the systems in private deployment. In this model, a smaller group of participants can deploy ledgers for a single use and retire the ledger when that use is complete. However, in private deployment, these systems again lose any ability to function permissionless and, instead, behave in a manner similar to the permissioned and enterprise focused Hyperledger Sawtooth [15]. Table 1 provides an overview and comparison of these systems, as well as _Cone_, a new blockchain system presented in this research. \begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Ledger** & **Consensus** &
\begin{tabular}{l} **Compute** \\ **Complexity** \\ \end{tabular} & **Model** & **Currency** & **Temporal** \\ \hline Ethereum (Casper) [12] & Proof of Stake & O(n) & Permissionless & Yes & No \\ Tendermint [13] & BFT & O(n) & Permissioned & Yes & No \\ Hyperledger Sawtooth [15] & PBFT & O(n\({}^{2}\)) & Permissioned & No & Yes \\ Stellar [14] & FBA & O(n\({}^{2}\)) & Permissionless & Yes & No \\ Conte & FBA & O(n) & Permissionless & No & Yes \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison of selected blockchain distributed ledger systems. To the authors knowledge, we present the first permissionless blockchain which achieves the following properties:  
* _Lifecycle Control:_ Participants create single use chains that are immutable while being updated, and can be retired when no longer in use. By removing currency and contract functions, the remaining data storage function does not play a role in forward balance history, nor is it required for ledger security. * _Network Function Compatibility:_ As a data store, the blockchain is made agnostic to use case; combining this with lifecycle control allows for the system to be used for temporal 5G virtual network functions. This research diverges from currency and contract focused research in two important ways; first, a deliberate focus is placed on blockchain use solely as secure, decentralized storage, rather than a mechanism of direct policy and incentive control; second, cellular design was given priority, with the goal of packaging blockchain to accommodate cellular operations rather than the inverse. This second goal, meaning to package blockchain as a standard virtual network function, one that can be scaled up, down, deploy, and to retire-allowing orchestration and lifecycle management, fitting 3 GPP 5G Core [16], and Common API Framework [17] designs. To achieve this, a wholly new blockchain design is required. This research presents this design, which we name _Cnote_. The following research is split into six parts. The first provides an overview of the modular structure of the 5G cellular core, and presents areas where blockchain can be matured to improve its general compatibility by moving to a format as temporal general storage, rather than more prescriptive currency and contract designs.