Mobile relay based energy saving scheme of femto basestations

Abstract

Recently, green communication is a rising issue due to the energy shortage, CO2 emission, and operating cost. To meet the network operators` interest, a number of green radio techniques were proposed. Green communication also called as green radio includes energy saving techniques in view of PHY layer, MAC layer and network layer. In the PHY layer, antenna and power amplifier circuits are designed to increase the energy efficiency. A basestation has many components such as power amplifier, RF circuit, signal processing processor and air conditioner. For example, feeder loss from RF to antenna can be decreased by system design. Air conditioner might look like a negligible issue, however, air conditioning power consumption can be up to 40% of total basestation power consumption. In MAC layer, power allocation is a major issue for energy saving technique. In the network level, the deployment of basestation and heterogeneous network are proposed for more efficient network. In this paper, we propose novel sleep mode basestation selection scheme using the mobile stations as mobile relay stations. Conventional researches have investigated the basestation sleep mode in the situation of low traffic. Therefore, even the optimal energy saving policy of basestation sleep mode is within the traffic limitation. However, when light traffic basestations can pass over their traffic to neighbor basestations, the basestations have more chances to be in sleep mode. Once we assume the forced handover to other basestation is possible, driving force to the basestation sleep mode is strengthened. Forced-handover is a concept of forcing edge mobile stations to neighbor mobile stations for both spectral efficiency and energy saving of the network. As users move around the system, the network central management unit faces maximization problem of choosing additional sleep mode basestations constrained by relay relations between basestations. The relay relation refers that the bas...