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A smart wearable textile array system (SWTAS) with direction of arrival (DoA) estimation and beamforming is proposed and developed for biomedical telemetry applications. This conformal system enables effective and continuous patient monitoring when combined with one or more health sensors, as information about the subject's health condition is received adaptively to guarantee link reliability. This operation is facilitated by a receiver front-end and a digital baseband beamforming network, which enables scalability and flexibility. The proposed SWTAS also features flexible antenna arrays made using textiles, which are arbitrarily located on a cylindrically shaped body phantom to ensure wide spatial DoA estimation capability. Besides being designed to suit on-body placement, the system performance is also characterized for on-body usage using a commercial body-emulating liquid, and placed at a realistic distance from the body, considering user clothing. Investigation indicated a good performance in the system's 80 forward plane with a DoA accuracy of 3 . Finally, a practical evaluation is presented using two transmitters placed at distinct locations and distances. The system successfully estimated both DoAs and received the telemetry signals using beamforming.Index Terms-Antenna arrays, biomedical communication, biomedical monitoring, biomedical telemetry, conformal antennas, direction of arrival (DoA) estimation, smart antennas.

Future handsets will employ uplink carrier aggregation to increase transmit data rates. This can lead to significant receiver desensitization for a number of LTE band combinations, because of the cross-modulation products created by the nonlinearity of antenna switches and duplexers in the RF front end. To mitigate this effect, an all-digital cancellation algorithm is proposed that relies solely on the digital representation of the signals, a peak covariance search for time alignment, and an adaptive distortion canceller. The recursive least squares (RLS) algorithm is used to find the optimal coefficients for the adaptive filter. Employing the distortion canceller improved the signal-to-interference-plus-noise ratio (SINR) and error-vector-magnitude (EVM) of the desired received signal by up to 20 dB.

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A cost-effective and flexible FPGA-based system architecture for digital predistortion (DPD) based linearization of power amplifiers (PAs) is proposed. The system is used to show the effectiveness of the cross-memory polynomial model (CMPM) for DPD. Two commercial amplifiers are linearized using single and two-carrier Wideband Code Division Multiple Access (WCDMA) signals as excitation and the performance of CMPM for DPD is compared to those of the memory polynomial (MPM) and memoryless models (MLM).

This paper discusses the measurement and modeling of the deterministic components of power amplifier (PA) emissions into neighboring receive (Rx) bands caused by PA nonlinearity, and proposes ways to distinguish these components from stochastic components. A method is presented to determine the orders of nonlinearity that are the principal contributors to the Rx band emissions. A Volterra-based model for their estimation is proposed, along with considerations for estimation accuracy. A criterion based on the matrix condition number for efficient pruning of the Volterra-based models is also presented. The proposed techniques are verified with measurements. The proposed model can be used to gain a deeper understanding of the nonlinearity mechanisms responsible for PA spurious emissions, and offers the possibility of canceling the deterministic components to improve receiver sensitivity.Index Terms-Deterministic noise, even-order terms, matrix condition number, memory polynomials (MPs), offset multisine, power amplifier (PA) emission, pruning, receive (Rx) band noise, spectral regrowth, transmitter leakage, Volterra-based models.

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This paper reports an efficient rectifier operating at 2.45 GHz for wireless energy harvesting applications with low input power levels. Single diode shunt-mounted topology is adopted for operation with low input power level. The efficiency is measured as 27.7% at -20 dBm of input power, 39.2% at -15 dBm, and 51.2% at -10 dBm. The maximum efficiency of 61.7% is measured at -0.4 dBm input power.