Delay-aware green hybrid CRAN

Abstract

Abstract-As a potential candidate architecture for 5G systems, cloud radio access network (CRAN) enhances the system's capacity by centralizing the processing and coordination at the central cloud. However, this centralization imposes stringent bandwidth and delay requirements on the fronthaul segment of the network that connects the centralized baseband processing units (BBUs) to the radio units (RUs). Hence, hybrid CRAN is proposed to alleviate the fronthaul bandwidth requirement. The concept of hybrid CRAN supports the proposal of splitting/virtualizing the BBU functions processing between the central cloud (central office that has large processing capacity and efficiency) and the edge cloud (an aggregation node which is closer to the user, but usually has less efficiency in processing). In our previous work, we have studied the impact of different split points on the system's energy and fronthaul bandwidth consumption. In this study, we analyze the delay performance of the end user's request. We propose an end-to-end (from the central cloud to the end user) delay model (per user's request) for different function split points. In this model, different delay requirements enforce different function splits, hence affect the system's energy consumption. Therefore, we propose several research directions to incorporate the proposed delay model in the problem of minimizing energy and bandwidth consumption in the network. We found that the required function split decision, to achieve minimum delay, is significantly affected by the processing power efficiency ratio between processing units of edge cloud and central cloud. High processing efficiency ratio (≈ 1) leads to significant delay improvement when processing more base band functions at the edge cloud.Index Terms-5G, network architecture, cloud RAN, end-toend delay, network function split, virtualized cloud RAN.

Joint Functional Splitting and Content Placement for Green Hybrid CRAN

“…where the first two terms denote the UP processing delay at CC and EC and the last two terms show that of CP at CC and EC. Each delay component is function of the equipment processing speed and required processing [11]. • D rsf : Delay induced by the number of radio subframes and is calculated as,…”

“…Constraint (11) ensures that, the total number of CP processed by a DU d at EC must not exceed the maximum capacity of the number of CP that can be hosted by a DU at EC. (11) Constraint (12) ensures that, the total number of CP functions processed by a DU d at CC must not exceed the maximum capacity of the number of CP functions that can be hosted by a DU at CC.…”

“…The problem is formulated as an integer linear programming (ILP) problem whose objective is to jointly minimize the inter-cell interference and the fronthaul bandwidth utilization. In [11], an end-toend delay model has been proposed for different functional split options. Considering this delay model, an optimization problem is formulated to reduce the system's power consumption and fronthaul bandwidth consumption.…”

“…Hybrid CRAN (H-CRAN) is proposed in [11] to alleviate the limitations due to delay and fronthaul capacity. H-CRAN leverages the previous CC/EC structure with functional splitting in a three-layer architecture to share the processing tasks between CC and EC [15].…”

An Efficient Content Delivery System for 5G CRAN Employing Realistic Human Mobility

“…The cells are synchronized for multicasting contents as configured in MBMS singlefrequency network (MBSFN), with the transport block index of 9 for all cells. According to [31], [32], [33], [34], we assume a BBU in the BBU pool processes the baseband signal for one cell. Each BBU has one LC, each LC has an optical channel connected to the ONU at each RRH.…”