Scope
The paper examines the trade-off between video streaming Quality of Experience (QoE) and CO2 emissions, introducing the concept of a “green user” who accepts lower video quality for reduced emissions.
Summary
Hoßfeld et al. quantify and illustrate the trade-off between the QoE of video streaming services and CO2 emissions. The paper considers a “green user,” who values energy efficiency in their Quality of Experience (QoE) assessment, accepting reduced video quality to lower CO2 emissions. Kleinrock’s power metric is used to determine optimal video bitrates balancing QoE and emissions. Specifically, the user satisfaction is considered to be the Mean Opinion Score (MOS) that is a logarithmic function of the video bitrate. Moreover, the model incorporates a greenness factor, which depicts how much a user is willing to accept a reduction of the MOS value for a higher reduction of the carbon footprint produced. Kleinrock’s power metric is used to determine optimal video bitrates balancing QoE and emissions. Specifically, the power metric, which represents the benefit of a user, is defined as the ratio of the QoE over the CO2 emissions.
The paper compares the impact of green user behaviour and green network technologies on CO2 reduction, with recommendations for 6G sustainability. Specifically, for the current Internet‘s energy efficiency and assuming 20%-30% green energy is used by the network operator, the relative CO2 reduction due to green networking technology is larger than the reduction due to green user behaviour. However, as we move towards greener networks, the decision by the user to be green has higher relative importance for CO2 reduction, since the network already has low CO2 emissions. Hence, it is important to raise awareness of users on their CO2 emissions and to provide them with the option of accessing Internet services in a green manner. The results of the paper are relevant to EXIGENCE. Additionally, the approach for modelling “green users” as well as the energy consumption and CO2 emissions of data networks can be adopted to investigate the EXIGENCE use cases.
Relevance for EXIGENCE
Hoßfeld et al.‘s paper model of user behaviour, which considers the user valuation for a particular QoE in terms of video bitrate, can be considered in EXIGENCE for designing a user video streaming model to investigate the performance of different incentive schemes. Additionally, the paper shows that green network technologies have an impact on the overall performance of carbon footprint reduction. Based on this, EXIGENCE can consider a more detailed network model that differentiates OTT video providers, cloud providers, core network providers, access providers, since different types of providers have a different adoption of green network technologies. Additionally, the paper considers the Kleinrock power metric to define the benefit as the ratio of the QoE over the corresponding carbon footprint. EXIGENCE can consider alternate benefit definitions, e.g., the difference of the utility (function of QoE) and the carbon footprint, and investigate not only the optimal operating point as in the above paper, but also the convergence of the corresponding incentive schemes.
T. Hoßfeld, M. Varela, L. Skorin-Kapov and P. E. Heegaard, “A Greener Experience: Trade-Offs between QoE and CO2 Emissions in Today’s and 6G Networks,” in IEEE Communications Magazine, vol. 61, no. 9, pp. 178-184, September 2023 https://martin.varela.fi/pdf/varela-commag-2023.pdf
