NXP unveils first dual-modem AISG transceiver for wireless base stations

NXP Semiconductors has introduced a new family of programmable AISG transceivers for wireless base stations and antenna line devices (ALDs) such as tower-mounted amplifiers (TMAs) and remote electric tilt (RET) antennas. 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 are able to offer significantly more flexibility, making it easier to change settings during development, manufacturing, or even site installation. While many manufacturers currently use a separate microcontroller and a high number of discrete components to deliver AISG on-off keying (OOK) modem functionality, the high level of integration in these transceivers helps to reduce the total component count, board space and costs, while introducing advanced functionality.

Remote electric tilt enables the dynamic adjustment of base station antenna beams enhancing 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, like TMAs and multiband antennas. Further, the AISG transceivers can be used as part of a larger framework, outlined separately by NXP in a white paper released today, to enable remote “site scans” and monitoring of mobile tower cabling connectivity failures, which typically requires costly, inefficient tower climbing and visual inspections.

“While the Antenna Interface Standards Group protocol has been a major step in the right direction, the fact remains that there is still no way to effectively gather information on mobile tower connectivity remotely. With the growth of 3G and LTE, the complexity of wireless base stations and the number of antennas and other devices installed from various manufacturers will increase dramatically – compounding maintenance costs and headaches for both network operators and equipment manufacturers,” said Rick Dumont, global marketing director for AISG products, NXP Semiconductors. “Our new AISG transceivers provide a compact and cost-effective solution for multi-channel AISG communication between tower-mounted ALDs and the base station to optimize base station site performance. At the same time, we’re opening the door to better interoperability across components, which could ultimately allow remote monitoring, diagnostics and debugging of a wider range of devices in the tower.”

The single-modem ASC3011 and dual-modem ASC3012 are power-efficient, highly integrated AISG modems in a small HVQFN64 package. 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 4 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 2.176 MHz, all NXP AISG transceivers also support 4.352-MHz and 6.528-MHz carrier frequencies, offering the possibility of multiplexing 3 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 10 dBm power to the RF feeder cable, and can have an integrated 50-ohm 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 94-MHz ARM Cortex-M3 processor with integrated AISG modem(s) and all peripheral interfaces required to control antenna line devices. These peripherals include 6 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 256 kB of embedded flash and 16 kB of SRAM to run the application software. In addition, a real-time clock with 32 kHz 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 optimization of receiver sensitivity, based on signal strength.

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