Scope
The ITU-T Recommendation L.1331 defines metrics and assessment methods for energy efficiency in operational networks, covering various network elements like base stations, backhauling systems, and radio controllers. It includes technologies from GSM to 5G NR and considers both homogeneous (e.g., only macro-only BTS) and heterogeneous networks (Small cells). The energy efficiency metrics also consider the slicing approach of 5G, incorporating latency energy efficiency in addition to metrics based on traffic and on coverage, already existing for legacy networks.
Summary
Assessing the energy efficiency of the mobile network requires determining the energy consumption metrics and the network performance metric. The performance encompasses data volume, coverage area (CoA), latency (Te2e), and number of subscribers (N) with specific calculations for different services and network types. For each performance metric, the energy efficiency metric is determined as follows:
1) Mobile network data energy efficiency (EEMN,DV): is the ratio between the data volume (DVMN) and the energy consumption (ECMN) when assessed during the same time period.
where EEMN,DV is expressed in bit/J.
2) Mobile network coverage energy efficiency (EEMN,CoA) is the ratio between the area covered by the MN and the EC when assessed for one year. The area covered (CoA) shall be assessed using rules (i.e., derived from geographic data or propagation models)
EEMN,CoA is expressed in m2/J and ECMN is the yearly energy consumption and is the “coverage area”.
3) Latency based metric (e.g., for ultra-reliable low latency communication, URLLC) is the inverse ratio of the end-to-end user plane latency and the energy consumed by the MN:
where πΈπΈππ,πΏ is expressed in ms-1/J.
4) Massive Machine-Type Communication (mMTC): Energy Efficiency for mMTC (EEMN,MMTC) is defined as follows (NMMTC is the mMTC number of subscribers):
5) Network Slicing (NS): Energy Efficiency with Network Slicing (EE NS) functionality:
where the performance Pns is related to the type of NS implemented in the network:
πππ =π·πMN for the eMBB NS type
πππ = Β for the URLLC NS type
πππ =πππππΆ for the MMTC NS type
Calculating the Energy consumption metrics (ECMN):
ECMN is computed as the sum of the energy consumption of each piece of equipment in the mobile network, including the BTS (BS), site infrastructure (SI), small cells (Cells), backhauling (BH), radio control nodes (RC), central cloud (CC), local cloud (LC), provided per radio access technologies and per MNO:
πΈπΆππ = βπ(βπ πΈπΆπ΅ππ,π + πΈπΆππΌπ) + βπ πΈπΆπππππ + βπ πΈπΆπ΅π»π + βπ πΈπΆπ πΆπ + βπ πΈπΆπΆπΆπ + βπ πΈπΆπΏπΆπ (1)
πΈπΆππ shall be measured in Wh over the period of measurement T.
The measurement duration (T) options are one week, one month, or one year. However, for the CoA metric, energy consumption is always extrapolated to one year.
This Recommendation also explains how to extrapolate the measurements made on partial networks to the level of the total network. Additionally, it provides methods for measuring network performance using standard counters for GSM, UMTS and LTE.
Relevance for EXIGENCE
The metric and methods for calculating energy consumption and energy efficiency are relevant for requirements and scenarios;Β energy metricsΒ andΒ energy measurements.