Modelling the energy efficiency of microcell base stations

The power consumption of wireless access networks will become a major issue in the coming years. Therefore, it is important to have a realistic idea about the power consumption of each element in those access networks. In this paper, an energy efficiency model for microcell base stations is proposed. Based on this model, the energy efficiency of microcell base stations is compared for various wireless technologies, namely mobile WiMAX, HSPA and LTE. The power consumption of microcell base stations is about 70-77% lower than for macrocell base stations but a macrocell base station is more energy-efficient than a microcell base station for the same bit rates. However, for the considered case and assuming our parameters are correct, a reduction in power consumption can be obtained by using microcell base stations to fill coverage holes

Towards a deployment tool for wireless access networks with minimal power consumption

The power consumption of wireless access networks will become an important issue in the coming years. In this paper, the power consumption of base stations for mobile WiMAX, HSPA, and LTE is modelled. This power consumption is related to the coverage of the base station. The considered technologies are compared according to their energy efficiency for different bit rates at a bandwidth of 5 MHz. For this particular case and based on the assumptions of parameters of the specifications, HSPA is the least energy-efficient technology. Until a bit rate of 11 Mbps LTE is the most energy-efficient while for higher bit rates mobile WiMAX performs the best. Furthermore the influence of MIMO is investigated. A decrease of about 80% for mobile WiMAX and about 74% for HSPA and LTE for the power consumption per covered area is found for a 4*4 MIMO system compared to a SISO system. The introduction of MIMO has thus a positive influence on the energy efficiency of the considered technologies. The power consumption and coverage model for base stations is then used to develop a prediction tool for power consumption in wireless access networks

Model for power consumption of wireless access networks

The power consumption of wireless access networks will become an important issue in the coming years. In this study, the power consumption of base stations for mobile WiMAX (Worldwide Interoperability for Microwave Access), fixed WiMAX, UMTS (Universal Mobile Telecommunications System), HSPA (High-Speed Packet Access) and LTE (Long-Term Evolution) is modelled and related to the coverage. A new metric, the power consumption per covered area PC(area), is introduced, to compare the energy efficiency of the considered technologies for a basic reference configuration and a future extended configuration, which makes use of novel Multiple Input Multiple Output (MIMO) technology. The introduction of MIMO has a positive influence on the energy efficiency: for example, for a 4 x 4 MIMO system, PC(area) decreases with 63% for mobile WiMAX and with 50% for HSPA and LTE, compared to a Single Input Single Ouptut (SISO) system. However, a higher MIMO array size (i.e. a higher number of transmitting and receiving antennas) does not always result in a higher energy efficiency gain

From Susa to Sippar: the travels of two bulls, a mountain and a tree

Among the Old Babylonian seals of Sippar there is one that appears to be unique. In this study we try to find out whether the motif on this seal was attested elsewhere during the Old Babylonian period and whether it already existed during previous periods. First, we determine the iconographic position of the motif by comparing it to similar ones. Then, by describing the motif’s journey through space and time, we argue that its origin lies in the ancient city of Susa. Finally, we look at the motif’s absence during the Old Babylonian period and link the presence of the motif on a Sippar seal to the fact that it belonged to a Sippar merchant