Axis adds multi-carrier capability to WiMAX Remote Radio Head

Designing WiMAX basestations using a distributed RRH approach allows the radio to be located alongside the antennas and physically separate from the basestation (BTS), removing the losses associated with long cable runs by replacing them with an optical fibre data interface. This architecture, in combination with highly efficient digital-to-RF conversion and amplification, gives a considerable reduction in both CAPEX and OPEX of the overall system as well as maintenance costs.

The energy efficiency of the basestation is vastly increased by the use of a multi-carrier RRH. This in turn reduces the environmental impact of the basestation, by reducing both its carbon footprint and the physical footprint of the radio mast.

“Axis RRHs are proven to improve basestation efficiency, and to decrease operating and capital costs,” commented Simon Mellor, CEO of AxisNT. “Introducing multi-carrier capability allows OEMS even greater flexibility in deployment and increases the opportunity for them to make network savings.”

Axis WiMAX RRH models are available for use in the 2.3 – 2.7GHz and 3.3 – 3.8GHz spectrum bands, and Axis radios are configurable for frequencies between 400MHz and 4GHz. Each of the models offers dual channel operation for MIMO, to comply with WiMAX and IEEE 802.16 d/e standards. They are also capable of 4-channel MIMO operation using 2-channel units driven separately from OBSAI/CPRI or daisy chained. Channel bandwidth is variable between 3.5MHz and 20MHz for TDD or FDD air interfaces.

Employing high efficiency advanced power amplifier technologies, the RRH units are available in several options with downlink output power levels of up to 28W. The advanced power amplifier design features include PowerDPD™ Digital Pre-Distortion, digitally controlled Doherty amplifiers and flexible wideband crest factor reduction (CFR).
The RRH also features automatic calibration of transmit, receive and PA bias control loops. It presents flexible multi-gigabit BTS connections, and can be fitted with OBSAI RP3-01, CPRI or custom OEM fibre 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 (AAS) and AISG v2.0 antenna control is provided.

Superior receiver performance of better than -98dBm can be achieved with single channel operation, and better than -100dBm using MIMO. A distributed BTS using 2-channel RRH with 28W downlink power is the equivalent of transmitting 56W downlink power from a traditional ground based BTS (assuming 3dB cable losses). Power consumption is reduced to a fraction of a traditional base station, thus reducing OPEX.

The use of RRHs is a key factor in minimising the environmental impact of wireless communication systems, both in terms of enabling a low carbon footprint radio system and in reducing the physical footprint of the radio mast. Because remote radio configurations both minimise RF losses and maximise multi-antenna efficiency, power consumption is fundamentally reduced. Overall power consumption is also driven down by the use of high efficiency signal processing and power amplification within the RRH itself. The Axis range of RRHs deliver high RF power and high capacity while minimising unwanted spectral emissions.

Axis RRHs reuse around 80% of components and materials between the different models. This common platform strategy and modular design format reduces resources during manufacture as well as those required for equipment support in the field.