Optimal BBU Placement for 5G C-RAN Deployment Over WDM Aggregation Networks

Abstract

5G mobile access targets unprecedented performance, not only in terms of higher data rates per user and lower latency, but also in terms of network intelligence and capillarity. To achieve this, 5G networks will resort to solutions as small cell deployment, multipoint coordination (CoMP, ICIC) and centralized radio access network (C-RAN) with baseband units (BBUs) hotelling. As adopting such techniques requires a high-capacity low-latency access/aggregation network to support backhaul, radio coordination and fronthaul (i.e., digitized baseband signal) traffic, optical access/aggregation networks based on wavelength division multiplexing (WDM) are considered as an outstanding candidate for 5G-transport. By physically separating BBUs from the corresponding cell sites, BBU hotelling promises substantial savings in terms of cost and power consumption. However, this requires to insert additional high bit-rate traffic, i.e., the fronthaul, which also has very strict latency requirements. Therefore, a tradeoff between the number of BBU-hotels (BBU consolidation), the fronthaul latency and network-capacity utilization arises. We introduce the novel BBU-placement optimization problem for C-RAN deployment over a WDM aggregation network and formalize it by integer linear programming. Thus, we evaluate the impact of 1) jointly supporting converged fixed and mobile traffic, 2) different fronthaul-transport options (namely, OTN and Overlay) and 3) joint optimization of BBU and electronic switches placement, on the amount of BBU consolidation achievable on the aggregation network.

Multi-objective placement of virtual network function chains in 5G

“…Moreover, they suppose that the Cloud has ideal characteristics, with neither processing delay nor computational cost (i.e., the cost of embedding a BBU function) in the Cloud, which is not realistic. The authors of [9] tackle the problem of BBU hoteling, i.e. finding the best location for the BBU to be placed in the Central Office (CO).…”

“…While in the literature many works address the problem of elastic network function placement [7], [8], there exists few work considering the placement of time critical network functions and the associated service chain. The authors in [9] formulate an Integer Linear Programming (ILP) model to maximize the number of cloudified BBUs with unlimited resources. Another approach proposed for the problem of BBU placement is the one presented in [10], where a graph-based model is introduced to decide whether the BBU functions need to be placed in the cloud or in the cell site.…”

Dynamic Virtual Network Connectivity Services to Support C-RAN Backhauling

“…The algorithm runs a number of iterations (line 2 in Table I), where at every iteration the set of requested CVN links (demands) is randomly sorted and served sequentially in the resulting order (lines [3][4][5][6][7][8][9][10][11][12][13][14]. At the end of each iteration the obtained solution is compared against the best solution obtained so far and, in case the latter is improved, it is updated (lines [15][16].…”

Real-life C-RAN deployment considerations

“…This paper introduces a case study scenario where a part of the network owned by the Danish mobile network operator TDC is investigated in terms of C-RAN implementation. The work in [3] uses an integer linear programming model to solve a BBU placement problem and investigates the model using three case study scenarios. [4] presents a model computing the number and placements of processing units, and considers the city of Lisbon as a scenario.…”