Energy Efficiency Performance ImprovementsThrough Two-Tier Cellular Networks

Mobile communication network is consuming 0.5 percent of the global energy supply alonethese days. While the unrelenting increase in user capacity requirement, which is expected togrow 1000 times in 10 years, will lead to even more energy consumption in this filed. On theone hand, the energy cost which has covered half of the operators’ operation fee willcontinually increase; On the other hand, global warming problem may be still more severedue to the rising amount of carbon emissions caused by the increasing energy consumption.Although the system spectrum efficiency is improved significantly by the introduction oflatest cellular network standards 3G and 4G, and the incremental enhancements in electronicsand signal processing are bringing the energy consumption down in base stations, theseimprovements are still not enough to match the huge increase in energy consumption which isrealted to the surging increase demands for more capacity. It is clear that solutions have to befound at the architectural layer. Besides, more and more capacity requirement is generatingfrom indoor environment, it has been a vital concern for operators to consider how to provideenough service coverage with the existing macro-only network due to the complex indoorenvironment and high wall penetration loss. All these cause urgent demand for more energyefficient cellular networks to deal with the capacity challenges. One of the promisingtechnologies to this situation is macro-femto heterogeneous networks by offloading indoortraffic to femtocells. Considering the shorten distance between indoor users and base stationsand spacial frequency reuse advantages, as well as the drawbacks on introduced interferenceand extra power consumption by femto base stations, this report proposes a simulationframework to study whether this network topology could enhance the system energyefficiency or not. The results suggest that the introduction of femtocells may be a promisingmethod to save energy consumption in the future and meet the increasing user data rate accessrequirements, especially in high user capacity demand networks, macro-femto deploymentcould save more energy consumption