Is backhaul becoming a bottleneck for green wireless access networks?

Abstract

Mobile operators are facing an exponential traffic growth due to the proliferation of portable devices that require a high-capacity connectivity. This, in turn, leads to a tremendous increase of the energy consumption of wireless access networks. A promising solution to this problem is the concept of heterogeneous networks, which is based on the dense deployment of low-cost and low-power base stations, in addition to the traditional macro cells. However, in such a scenario the energy consumed by the backhaul, which aggregates the traffic from each base station towards the metro/core segment, becomes significant and may limit the advantages of heterogeneous network deployments. This paper aims at assessing the impact of backhaul on the energy consumption of wireless access networks, taking into consideration different data traffic requirements (i.e., from todays to 2020 traffic levels). Three backhaul architectures combining different technologies (i.e., copper, fiber, and microwave) are considered. Results show that backhaul can amount to up to 50% of the power consumption of a wireless access network. On the other hand, hybrid backhaul architectures that combines fiber and microwave performs relatively well in scenarios where the wireless network is characterized by a high small-base-stations penetration rate.

Cost- and energy-efficient backhaul options for heterogeneous mobile network deployments

“…The inputs are the population density and other relevant data describing the network and service usage such as: the number of active mobile subscribers, the user profile (e.g., heavy or ordinary), the daily traffic variation, and the penetration rate of different mobile terminals. Using the long-term large-scale traffic model proposed in [6] this phase returns the value of the area traffic demand.…”

“…It is used to determine the number of BSs to be deployed in the area. In this case the inputs are the area traffic demand from the previous step in addition to other parameters related to the wireless network technologies to be used, i.e., the capacity of all BS types and the penetration rate of the small cells [6]. Accordingly, it is possible to obtain the number of macro BSs and small cells required to cover the area and to satisfy the wireless traffic requirements of a given year.…”

“…The first set of papers addressing the design of backhaul architectures for HetNets, i.e., [3,5,6], focused mostly on energy consumption evaluation.…”

“…The authors also showed that fiber-based backhaul architectures are significantly more energy efficient than their microwave-based counterparts. Finally, the authors in [6] analyzed several backhaul options for indoor small cell based on copper, fiber, and microwave. The objective was to evaluate whether backhaul might become a bottleneck when providing mobile broadband services to indoor users.…”

“…It combines the work of [6] and [4] by analyzing both the power consumption and the TCO value of different backhaul architectures in a Greenfield scenario. This allows new important considerations, with respect to the ones already discussed in [6] and [4]. Second, this paper presents and compares the power consumption and the TCO value of different migration options for backhaul networks in a number of Brownfield deployment scenarios.…”