# Evolution of Access Network Sharing and Its Role in 5G Networks
## 5 Fixed Access Network Sharing Economics
### New Ownership Models
Finally, the concept of purchasing assured capacity-on-demand at small granularity can support novel, revenue-generating applications, which require deterministic delivery of network capacity to operate correctly (e.g., those based on augmented reality). 2. **Anti-competitive behaviour**, including hoarding of resources and excessive pricing [88]. _State-of-the-Art solution:_ Economically robust auction mechanisms designed for preventing manipulative market behaviours. For example, in [91], an auction mechanism is proposed for a shared PON, which provides positive incentives for the operators to avoid malicious conduct in the market. The proposed double auction can support simultaneous multiple-item trades. It does not impose any additional communication delay to the time-critical scheduling process of the PON as it relies on a sealed-bid bidding process which, unlike common open auctions, does not involve any tug of war bidding among the participants. 3. **Lack of trustworthy central authority**, including scenarios where the infrastructure provider is also a competing operator. _State-of-the-Art solution:_ Most of the scenarios in the state-of-the-art have considered cases where infrastructure is provided by a trusted third-party (e.g., a government authority). The InP is assumed to be trusted by all of the parties and provides a secure and reliable platform for the networks operators to trade. However, this approach overlooks the other network ownership models where either the InP is not trusted by all of the participants to be entirely impartial, or an ownership model does not involve a central InP, and the role of providing the infrastructure is distributed among the operators. Blockchain technology uses a distributed consensus mechanism relying on a distributed ledger to assure trust among a number of participants without a central entity. Empowered by smart contracts (i.e., a piece of code that digitally verifies and enforces a contract), Blockchain can take a step forward and operate trustworthy technical/business processes with no intermediary involved. In [92], the authors describe how smart contracts can facilitate the automation of complex multi-step processes in an Internet of Things (IoT) ecosystem. The application of Blockchain in the creation of machine to machine service and resource marketplaces has also been addressed in [92]. In [93], the authors have studied a blockchain solution for network slice brokering in 5G networks. In [94] a blockchain-based distributed bilateral trade mechanism is introduced. Using the mechanism presented in [94], bilateral trade markets that are widely used in telecommunication networks (e.g., resource allocation in NFV markets [95], femtocell access [96], mobile crowd sensing [97], spectrum sharing [98] and PON Sharing [91]) can function in an untrusted environment. The proposed solutions facilitate leasing resources from infrastructure providers dynamically according to the needs of the operators. The same approach could also come into help in FANS peer-to-peer trust issue. However, further research is required to address application-specific requirements in FANS, such as latency limitations. These findings open up new possible research areas. For example, in [99] a CapEx cost model for PON technology has been proposed. However, this cost model does not account for infrastructure sharing. A greater focus on designing a cost model for fixed access network sharing could produce interesting findings when also considering more heterogeneous use cases, e.g., merging residential, business and Cloud-RAN services. In [100], for example, the authors investigate the advantage of PON sharing for implementing distributed Multiple Input Multiple Output (MIMO) in C-RAN. Additional work could provide a quantitative analysis of the OpEx reduction enabled by the deployment of Blockchain and smart contract technology.