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Dual-modem AISG transceiver for wireless base stations

Posted: 20 Mar 2013 ?? ?Print Version ?Bookmark and Share

Keywords:wireless base station? AISG? modem? transceivers?

NXP Semiconductors has debuted a range of programmable antenna interface standards group (AISG) transceivers for wireless base stations and antenna line devices (ALDs) such as tower-mounted amplifiers (TMAs) and remote electric tilt (RET) antennas. According to the company, the family includes the industry's first fully integrated dual-modem AISG transceivers, as well as the first AISG system solution to integrate an ARM Cortex-M3 processor alongside two AISG modems.

DSP-based and programmable, NXP's AISG transceivers claim to offer significant flexibility, making it easy to change settings during development, manufacturing, or even site installation. While many manufacturers use a separate MCU and a high number of discrete components to deliver AISG on-off keying (OOK) modem functionality, the exceptionally high level of integration delivered by NXP's transceivers helps to reduce the total component count, board space and costs, while introducing advanced functionality, added the company.

Remote electric tilt enables dynamic adjustment of base station antenna beams for optimal network coverage, and is becoming a standard feature for wireless base station antennas. By embedding AISG transceiver functionality inside the antenna itself to control the RET, infrastructure providers can eliminate additional Smart-Bias-T and RS485 cabling to the antenna, increasing reliability while reducing tower costs. NXP's dual-modem AISG devices are particularly suitable for ALDs with multiple feeder cable connections such as TMAs and multi-band antennas.

The single-modem ASC3011 and dual-modem ASC3012 are power-efficient, highly integrated AISG modems in a small HVQFN64 package, stated NXP. The modems can interface via a two- or three-wire UART or with an RS485 transceiver, and modem parameters can be programmed using an I2C interface. Up to four NXP AISG transceivers (providing up to 8 AISG OOK modems) can be connected to a single I2C-bus, and each modem can be programmed with its own settings as required by the base station site.

In addition to the default AISG carrier frequency of 2.176MHz, all NXP AISG transceivers also support 4.352MHz and 6.528MHz carrier frequencies. This offers the possibility of multiplexing three AISG channels on the same RF feeder cable. Receiver bandpass filters are integrated to effectively block any out-of-band interference signals. Users can program the receiver sensitivity to high and ultra-high levels, in addition to standard AISG sensitivity. The transmitter can deliver up to 10dBm power to the RF feeder cable, and can have an integrated 50? receiver and transmitter termination. The transceivers conform to AISG1: Issue 1.1 and AISG v2.0.

The single-modem ASC3101 and dual-modem ASC3112 are optimised AISG controllers, including a 94MHz ARM Cortex-M3 processor with integrated AISG modem(s) and all peripheral interfaces required to control antenna line devices. These peripherals include six PWM outputs to drive RET antenna motors, and a number of general purpose ADCs/DACs for measurement and control functions.

The integrated AISG transceivers with the embedded ARM processor are shipped with a full software development kit (SDK), including the reference AISG stack for basic control and power management, which is provided to all NXP AISG customers to promote device interoperability. Each controller offers up to 256kB of embedded flash and 16kB of SRAM to run the application software. In addition, a real-time clock with 32kHz crystal and 44 configurable GPIOs are available. The DSP-based modem also facilitates field upgrades for higher transfer speeds that comply with future protocols. The programmable modems enable optimisation of receiver sensitivity, based on signal strength.

The ASC3101, ASC3112, ASC3011 and ASC3012 are sampling with lead customers, with volume manufacturing starting at the end of March 2013.

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