Dynamics and controls of ecosystem multiserviceability across the Qingzang Plateau

Ecosystem multiserviceability(EMS),a comprehensive and significant ecological indicator,reflects the capacity of ecosystems to offer multiple services concurrently.Intensified climate change and human activity are continu-ously altering ecosystem functions,services,and EMSs.However,numerous studies have only focused on one or a few ecosystem services,rarely taking into account spatial-temporal distribution and drivers of EMS on behalf of different agencies.We calculated EMS including pastoralist(PA),environmental protection agency(EPA),bio-diversity conservation agency(BCA),and climate change mitigation agency(CCMA)using grassland production,habitat quality,water conservation,and carbon sequestration.Then,the effects of geographical features,climate factors,and human activities on spatial-temporal patterns of EMS were explored.The result indicated that EMS showed a decreasing tendency from the southeast to northwest on the Qingzang Plateau(QZP).Meanwhile,there were no obvious fluctuations in four simulated scenarios(PA,EPA,BCA and CCMA)among different vegetation types during 2000 to 2015.Notably,EMS of all simulated scenarios decreased in the alpine steppe ecosystem,but negligible changes were found in other ecosystems from 2015 to 2020.Moreover,the relative importance of precipitation in annual mean value(from 2000 to 2020)of PA,EPA,BCA and CCMA were 0.13,0.11,0.30 and 0.19,respectively.Overall,precipitation played the dominant role on the dynamics of EMS,followed by elevation and human footprint.Our findings highlighted that understanding the patterns and drivers of EMS could provide a reference for the regional management and maintenance of ecosystem stability on QZP.

A QoE-based jointly subcarrier and power allocation for multiuser multiservice networks

Quality of experience(QoE) is widely applied to reflect user's satisfaction of the network service,which exactly conforms to the user-centric concept in 5G. In this paper, we propose a QoE-based subcarrier and power allocation algorithm for the downlink transmission of a multiuser multiservice system. For the subcarrier allocation algorithm, the rate proportional fairness factor is defined to ensure the fairness between users. Based on different QoE models of three services, i.e., file down(FD), video streaming and voice over internet protocol(VOIP), a multi-objective optimization method is exploited to allocate the power resource by minimizing the total power consumption and maximizing the mean opinion score(MOS) value of users simultaneously. Simulation results indicate that the proposed algorithm has less power consumption and higher QoE performance than the traditional proportional fairness(PF) algorithm. In addition, the proposed algorithm can achieve nearly the same fairness performance as the PF algorithm. Moreover, when the number of subcarriers becomes larger, the power assumption will be less but with little influence on both the QoE and fairness performances.