Cellular Base Stations: reducing radio network energy cost and environmental impact
An increasing number of 3G, WiMAX and other advanced broadband radio systems are being installed around the world to improve both coverage and capacity. With the radio networks normally accounting for around 80% of the total electricity used by an operator, the increase in energy usage, coupled to continuing rises in the price of energy, is driving up operational costs for network operators and contributing to an increased environmental impact. Current 3G and WiMAX base stations are very power-inefficient due to the use of linear RF power amplifiers (PAs), which typically account for half of the total power used by a base station.
Another increasingly important consideration is the need to support a wider range of frequency bands, and multi-mode operation, from the same basic PA design to meet the emerging needs of operators worldwide. Current efficiency improvement techniques, being essentially narrow-band, cannot satisfy this requirement.
Application of Nujira Technology
Nujira's High Accuracy Tracking (HAT™) Power Modulator replaces the DC-DC converter which is typically used to provide a fixed drain voltage to the PA. The Power Modulator dynamically varies the voltage supplied to the PA in line with the modulation envelope, thus ensuring that the output device operates in near-compression (even at low output powers), and dramatically improves the PA efficiency. The envelope of the signal passing through the amplifier is derived from the modulator/digital pre-distortion (DPD) function. Interfacing to the DPD function is via a digital LVDS interface.
Benefits
Nujira’s technology has the potential to reduce network energy consumption (and hence CO2 emissions) by 50%, increasing network profitability and helping operators’ ‘green’ credentials.
Nujira’s technology enables lower maintenance costs and greater reliability through reduced heat dissipation, and allows the design of smaller and cheaper base stations, leading to lower site costs. The lower power consumption also reduces the backup power requirements, further reducing CAPEX and OPEX costs. Finally, Nujira's HAT™ technology is a key enabler for broadband, multimode PAs for flexible base stations.
For more information on the OPEX and environmental benefits arising from the use of Nujira's technology, click on the links in the adjoining box.
Product Status
Nujira is currently shipping pre-production Power Modulators to support trials with 10 cellular infrastructure vendors, of which 2 have announced their intention to proceed to full commercialisation. First announcements of volume commitments are expected H2 2008, with volume shipments beginning early in 2009.