Reducing the power consumed in mobile base stations is an important way to support the effort for energy reduction in communication systems. Mobile base stations are designed for peak load situations, which only occur rarely relative to the overall daily traffic profile. This means, that daily operation of mobile communication networks especially in LTE systems shows a significant amount of time periods without data transmission, leading to reduced average energy efficiency. Sleep modes in base station transceivers, based on the deactivation of components and especially of the power amplifier in time slots of no signal transmission, show a significant potential to reduce the average energy consumption in base stations. This is demonstrated by experimental evaluations, done for different traffic load conditions, on hardware prototypes, dedicated for macro-cell base station. Index Terms -Mobile base stations, power saving, component sleep modes, power amplifiers.
This paper presents a novel system architecture for small cell base stations with integrated millimeter-wave wireless backhaul. In contrast to existing systems, the data signal on the wireless backhaul uses the same 3GPP compliant signal than on the access link serving the users. The small cell omits the 60GHz local oscillator source completely by using the self-heterodyning mixing approach and transmits only a suppressed carrier. Measurements of a single-carrier WCDMA signal on a simplified setup with lower carrier frequency demonstrated that due to successful phase noise cancellation the 3GPP ACLR and EVM requirements are easily met, even with 15dB dynamic on the backhaul link. Moreover, the required broadband capability is proven using an LTE signal with 20MHz bandwidth.Index Terms -Millimeter-wave, phase noise cancellation, self-heterodyne mixing, small cells, wireless backhaul.978-1-4799-5507-7/15/$31.00
ru ¤ diger quay 2 and friedbert van raay 2 This paper gives a summarized overview on the progress and achievements on AlGaN/GaN high electron mobility transistors (HEMT)-based power amplifiers (PAs) for mobile radio applications which have been achieved within two national funded German projects during a period of six years. Starting with a first 34 dBm (2.5 W, peak) amplifier in 2003 the impressive progress toward highly efficient S-band mobile radio PAs with up to .50 dBm (100 W) peak output power is described by means of some selected single-and multiband amplifier demonstrators. This progress has been mainly enabled by clear progress on GaN technology, device packaging, and PA design. Targeting at highly efficient single-band amplifier applications, a 2.7 GHz symmetrical Doherty amplifier with up to 45% drain efficiency at close to 45 dBm average output power under single-carrier W-CDMA (Wideband Code Division Multiple Access) operation using digital predistortion can be highlighted. In case of multiband capable amplifiers addressing software-defined radio applications, a class-AB-based demonstrator covering a frequency range from 1.8 to 2.7 GHz was realized. The amplifier showed .30% drain efficiency up to 2.5 GHz as well as up to 40 dBm average output power under single-carrier W-CDMA operation using proprietary digital predistortion. Finally, Alcatel-Lucent's activities on envelope tracking for future efficiency improved GaN-based amplifiers are described.
In era of exploding energy consumption and thus equipment operating cost as well as the parallel environmental need to reduce the carbon footprint, energy efficient mobile radio is a very important issue and future challenge. Additionally, increased number of standards, frequency bands and applications require flexible and sustainable solutions. On both fields the power amplifier constitutes one of the setscrews to be addressed. On the one hand, the power amplifiers cause up to 60 % of the power dissipation of a base station, on the other hand it constitutes a bottleneck concerning transmit bandwidth. The following paper presents a very promising concept of a highly efficient Doherty which supports multiband capability in order to enable future efficient, flexible and sustainable mobile radio applications. The basic functionality of the proposed concept is verified by simulation and promising simulated results, based on AlGaN/GaN-HEMTs from FhG-IAF (Fraunhofer Freiburg) indicate the benefits of the new concept compared to conventional Class-AB and Doherty amplifiers.
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