Green Distributed Antenna Systems

Green Distributed Antenna Systems (Green DAS) is a seed project within a joint collaboration between Acreo Swedish ICT AB, Wireless@KTH, and MIC Nordic AB.

The project addresses the formulation of the energy efficient DAS solution and its main components with the goal to optimize the energy consumption in the access segment of mobile communication networks. The project specifically focuses on optical fiber-based DAS.

Motivation and objectives

DAS are used to improve coverage of a single or multiple base stations (combined in a base station hotel) by using a distributed infrastructure of remote antenna connected to the base station/base stations (2G, 3G or LTE) via fibers or coaxial cables. The fiber-based DAS (F-DAS) is a primary goal of the present proposal.

So far, the architecture, planning and deployment of DAS do not take the energy consumption factor into consideration – the goal is at present to provide the required coverage over a defined area. It is still an open general question on how the architecture and other parameters of F-DAS can affect its total energy consumption. In particular, the open questions may include:

  • Given that the environment (area of coverage, physical properties of surroundings) is known, what is the optimal balance between the number nodes and their power to provide a defined QoS?
  • The fiber-based DAS allows for dynamic capacity allocation (using e.g. wavelength division multiplexing for analogue solutions, or digital multiplexing for the standardised CPRI/OBSAI solutions). How using this dynamic allocation affects the total energy consumption in various scenarios?
  • What is the impact of various scenarios for distributed infrastructure (more fibers, less fibers) on the business case of deployment (CapEx)? What will be the approximate Total Cost of Ownership (TCO), which depends on both CapEx and OpEx, over the lifetime of the system?
  • What will be the impact of basestation collocation (“basestation hotelling”) in terms of Total Cost of Ownership (TCO) comparing to normal distributed basestation scenario?

Another open question is whether the technology for remoting remote radio unit within the basestation (using similar fiber or coax-based solutions) can be combined with the stand-alone DAS and whether and which energy efficiency gain can be achieved through this combination?