In this work, one proposes a model to evaluate the optimal deployment of Centralised Radio Access Network (C-RAN) architecture elements, i.e. Base Band processing Units (BBUs) and fronthaul links, in a brown-field scenario, in which traditional base stations are already deployed and a physical network is present. The proposed optimisation framework jointly optimises BBU placement and accesses network infrastructures deployment. It clusterises the Remote Radio Heads in the scenario through a Multicommodity Flow approach and solves the minimum cost fronthaul network deployment through a Rooted Delay-Constrained Minimum Spanning Tree approach. Optical fibre and microwave links are considered as fronthaul infrastructures. The proposed optimisation framework is validated through a comparison with a theoretical output for a canonical scenario, being afterwards applied to a real scenario. A cost analysis for different scenario configurations is presented, and trade-offs and guidelines for a cost optimal deployment of C-RAN are provided. The analysis of results for the real scenario of the city of Lisbon and its surrounding areas shows that the delay budget in the fronthaul network highly impacts on capital expenditures as well as on operational ones. It is shown that a larger delay budget enables an annual cost reduction up to 72% in urban areas and 54% in rural ones.

在这项工作中，提出了一种模型，以评估在传统基站属于棕色场的情况下，集中式无线电接入网（C-RAN）体系结构元素（即基带处理单元（BBU）和前传链路）的最佳部署。已经部署并且存在物理网络。所提出的优化框架共同优化了BBU的放置，并访问了网络基础架构的部署。它通过“多商品流”方法将方案中的远程无线电头簇化，并通过“根延迟限制最小生成树”方法解决了最低成本的前传网络部署。光纤和微波链路被视为前传基础设施。通过与典型场景的理论输出进行比较，对提出的优化框架进行了验证，之后应用于实际场景。提出了针对不同方案配置的成本分析，并提供了针对成本优化部署C-RAN的权衡和指南。对里斯本市及其周边地区真实情景的结果分析表明，前传网络中的延迟预算对资本支出和运营支出都产生了巨大影响。结果表明，较大的延迟预算可使城市地区的年度成本降低多达72％，而农村地区的年度成本降低了54％。对里斯本市及其周边地区真实情景的结果分析表明，前传网络中的延迟预算对资本支出和运营支出都产生了巨大影响。结果表明，较大的延迟预算可使城市地区的年度成本降低多达72％，而农村地区的年度成本降低了54％。对里斯本市及其周边地区真实情景的结果分析表明，前传网络中的延迟预算对资本支出和运营支出都产生了巨大影响。结果表明，较大的延迟预算可使城市地区的年度成本降低多达72％，而农村地区的年度成本降低了54％。