# Evolution of Access Network Sharing and Its Role in 5G Networks
## 5 Fixed Access Network Sharing Economics
### Fixed Access Network Sharing for 5G  
Considering cooperation and competition amongst operators, in [73] the authors study how the Swedish telecommunications business landscape changed throughout the different mobile network generations (GSM, 3G, and 4G) and competing mobile operators started to share network resources. However, this trend changed with the deployment of 4G networks, where reduced equipment costs and re-usability of the base station sites between 3G and 4G played a role in disincentivizing operators to share. Based on the market reports in [74], the upgrade pattern to 5G will be radically different from 3G and 4G, where an increment of 23% in CapEx is expected between 2018 and 2025.  
In [75] the authors conduct a cost assessment studying how PON/FTTH network could affect factors such as initial investment, cost per home connected and the payback period. Their study covers the most popular optical access technologies and standards, namely GPON, XG-PON, TWDM-PON, and AWG-based WDM-PON in urban and suburban regions. They conclude that while employing a network-sharing scheme increases the cost per home connected and the payback period, the required initial investment is strongly reduced.  
These solutions bring cost savings of up to 40% in terms of CapEx, and up to 15% in OpEx over a five-year period [76]. By other figures, the number of announced network sharing agreements between network operators worldwide has increased almost 20 fold in 7 years (five agreements in 2010 and 98 in 2017) [77]. We believe this vision will require the operators to think beyond simply sharing the feeder fibre cables or site-reduction [78] as a cost-saving approach towards their infrastructure.  
In addition to cost reduction, infrastructure sharing can facilitate the expansion of coverage, therefore, helping the operators to grow their customer base and access new sources of revenue.  
The large potential capacity of optical access networks makes a strong case for the operators to reduce their costs by exploiting the efficiency of scale that can be achieved by sharing. This is especially important to facilitate new entrants and promote competition. However, this comes at the cost of incentivizing operators to share their infrastructure and resources. In some countries, the regulator may attempt to enforce sharing, but this has been met with limited success as operators try to circumvent regulations by using legal loopholes, for instance, by not providing the required interfaces. We believe that as the cost for 5G network deployment soars, the potential reduction in the total cost of ownership (TCO) achievable through new models of infrastructure sharing will provide a better driving force than the legacy regulatory enforcement.  
SDN and virtualization can facilitate sharing primarily in two ways:  
1. By providing simplified and standardized interfaces to connect to other operators network.
2. By virtualizing the critical network control functions and provide customizable functions for the guest operators.  
The general architectural guidelines for FANS were set out by the BroadBand Forum (BBF) in the TR-370 standard [79], which defined mechanisms to enable sharing of multi-service broadband access networks for new Virtual Network Operators (VNOs), using ETSI NFV virtualization standards. The standard is currently being updated [80], to further specify the roles of VNOs and InPs, as well as improving the definition of the interfaces between the two.  
In the last few years, many 5G trials have been carried out worldwide. For example, up until early 2019, only in Europe there have been 138 trials in 23 countries [81], often with partnerships between Industry and University [82]. Some of the trials were carried out specifically on FANS, by vendors and operators, as reported in [83; 84], emphasising the important role that infrastructure sharing plays in 5G networks.