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High-power WiMAX base stations fit multiGbit links

Posted: 25 Aug 2008 ?? ?Print Version ?Bookmark and Share

Keywords:radio? WiMAX? base station?

Axis Network Technology (AxisNT) has launched a family of MIMO Remote Radio Heads (RRHs) for OEM deployment of WiMAX networks globally. The RRHs are suitable for both 2.5GHz and 3.5GHz networks. When customized, these can meet the specific interface and packaging needs of the OEM. The WiMAX base stations usually when used with a distributed RRH approach and highly efficient digital-to-RF conversion and amplification may decrease both capital and operating expenses of the overall system, including maintenance costs.

The RRH provides the radio to be stationed near the antennas and physically separated from the base station, eliminating the losses related to long cable runs by making use of an optical fiber data interface. The RRH presents flexible multiGbit base station connections, communicating via Open Base Station Architecture Initiative (OBSAI), Common Public Radio Interface (CPRI) or custom OEM fiber interfaces.

The RRH models can be employed in the 2.3GHz to 2.7GHz and 3.3GHz to 3.8GHz spectrum bands, and the radios are adjustable for frequencies between 400MHz and 4GHz. Each of the models gives dual channel operation for MIMO to meet WiMAX and IEEE 802.16 d/e standards. They can also accomplish four-channel MIMO operation with two-channel units driven separately from OBSAI/CPRI or daisy chained. Channel bandwidth ranges from 3.5MHz and 20MHz for time division duplex or frequency division duplex air interfaces.

With the use of high efficiency advanced power amplifier technologies, the RRH units are used in several options with downlink output power levels of up to 28W. The improved power amplifier design features have PowerDPD Digital Pre-Distortion, digitally controlled Doherty amplifiers and flexible wideband crest factor reduction.

The RRH also has automatic calibration of transmit, receive and power amplifier bias control loops, and used with OBSAI RP3-01 or CPRI V2 digital baseband interfaces with either 1 or 2 optical connectors as required. They integrate an AxisIPR configurable IP radio processor, along with an AxisOS remote management and local craft interfaces. Support for Adaptive Antenna Systems and AISG ver 2.0 antenna control is given.

Superior receiver capability better than -98dBm can be reached with one channel operation and more viable than -100dBm using MIMO. A distributed base transceiver station (BTS) with two-channel RRH having 28W downlink power is the equivalent of giving away 56W downlink power from a traditional ground based BTS (assuming 3dB cable losses). Power use is decreased to a fraction of a traditional base station, thus lowering OPEX.

"With a distributed RRH design triples base station efficiency, which makes them roughly 60 percent cheaper to run and provides them a greener option," said Simon Mellor, CEO, AxisNT. "The deployment flexibility that springs from using fiber optic cables rather than RF cables also lowers the base station footprint lessening the site rental costs for the operator and a further decrease in environmental impact," he added.

A standard RRH management has collaboration between the customer and the AxisNT engineering team in doing interoperability on the OBSAI and/or CPRI digital interface implementation. Products have a variety of interface connector choices, with a single or dual fiber optic interface for up to 10km of FO cables, a choice of compact and lightweight packaging, and they can be suited with an optional customized solar shield. The RRHs have low power use and a wide input voltage range to provide flexibility in site installation. A built in handle and a variety of mounting brackets simplify installation.





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