N092-159 TITLE: High Efficiency WCDMA Power Amplifier for MUOS Handheld Radio

TECHNOLOGY AREAS: Information Systems, Electronics

ACQUISITION PROGRAM: Mobile User Objective System (MUOS), an ACAT I program.

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.

OBJECTIVE: Advance the state of the art for multi carrier power amplifiers for WCDMA radios. Design a high efficiency (50% or higher) multi carrier power amplifier for WCDMA handheld radios for transition to MUOS. Develop a prototype amplifier and evaluate its performance.

DESCRIPTION: The Navy�s Communications Satellite Program Office (PMW 146) is developing the Mobile User Objective System (MUOS), a narrowband satellite communications (SATCOM) system. It is based on a third generation cellular phone system using Wideband Code Division Multiple Access (WCDMA) and Universal Mobile Telecommunications System (UMTS). It is expected to begin operation in 2010, with world-wide coverage by 2015. To fully utilize the MUOS satellites, new user terminals using WCDMA are required.

Commercial cell phone systems are optimized to reduce cost. Single carrier WCDMA amplifiers are approximately 37% to 40% power efficient. This level of performance has been adequate due to the need to have very cheap cell phones to entice consumers, and because of the relatively low power requirements of commercial cellular networks due to the close proximity of cell towers to the users.

Military radios generally have more stringent requirements than commercial ones. They transmit at higher power, must be more reliable and include additional processing components for encryption. Additionally, MUOS will allow the deployment of smart radio terminals, similar to today�s commercial smart phones. With MUOS, the cell tower is located in the satellite, approximately 36,000 kilometers away. This is three orders of magnitude farther than in existing commercial cellular systems. MUOS operates on different frequencies than commercial cellular systems, which are optimized for a very specific frequency range. Another difference from commercial systems is that military users are not always in a position to easily re-charge the batteries in their radio, making power efficiency even more important.

The maximum output power for the MUOS radio amplifier is expected to be 8 W versus 800mW for a typical commercial amplifier. MUOS must amplify a frequency "notched" WCDMA signal to allow for simultaneous legacy users. The notched WCDMA signal has a 2-3 dB larger peak-to-average ratio (PAPR) than the WCDMA signal amplified by a commercial phone. MUOS operates over the 280-320 MHz frequency band while the current commercial systems operate over the 1920-1980 MHz band. The MUOS radio must therefore operate over a much larger percentage bandwidth (12.5% versus 3.6%).
Higher efficiency and linearity performance will be the two primary improvements required by the MUOS HHT PA. Higher efficiency will be critical for battery life and thermal considerations. Higher linearity will be necessary to maintain signal fidelity of the "notched" MUOS WCDMA signal. High efficiency and linearity will be especially difficult to achieve since the MUOS HHT PA must operate over a higher percentage bandwidth.
Joint warfighters require a beyond state-of-the-art power amplifier to realize a small, lightweight handheld radio for MUOS. Achieving power efficiency of 50% or more would be a significant step beyond current technologies and enable a more reliable, better performing handheld radio for MUOS.

PHASE I: Design a high efficiency multi carrier power amplifier for WCDMA handheld radios.
Tasks under this phase could include: