mm-Wave Data Transmission and Measurement Techniques: A Holistic Approach

The ever-increasing demand on data services places unprecedented technical requirements on networks capacity. With wireless systems having significant roles in broadband delivery, innovative approaches to their development are imperative. By leveraging new spectral resources available at millimeter-wave (mm-wave) frequencies, future systems can utilize new signal structures and new system architectures in order to achieve long-term sustainable solutions.This thesis proposes the holistic development of efficient and cost-effective techniques and systems which make high-speed data transmission at mm-wave feasible. In this paradigm, system designs, signal processing, and measurement techniques work toward a single goal; to achieve satisfactory system level key performance indicators (KPIs). Two intimately-related objectives are simultaneously addressed: the realization of efficient mm-wave data transmission and the development of measurement techniques to enable and assist the design and evaluation of mm-wave circuits.The standard approach to increase spectral efficiency is to increase the modulation order at the cost of higher transmission power. To improve upon this, a signal structure called spectrally efficient frequency division multiplexing (SEFDM) is utilized. SEFDM adds an additional dimension of continuously tunable spectral efficiency enhancement. Two new variants of SEFDM are implemented and experimentally demonstrated, where both variants are shown to outperform standard signals.A low-cost low-complexity mm-wave transmitter architecture is proposed and experimentally demonstrated. A simple phase retarder predistorter and a frequency multiplier are utilized to successfully generate spectrally efficient mm-wave signals while simultaneously mitigating various issues found in conventional mm-wave systems.A measurement technique to characterize circuits and components under antenna array mutual coupling effects is proposed and demonstrated. With minimal setup requirement, the technique effectively and conveniently maps prescribed transmission scenarios to the measurement environment and offers evaluations of the components in terms of relevant KPIs in addition to conventional metrics.Finally, a technique to estimate transmission and reflection coefficients is proposed and demonstrated. In one variant, the technique enables the coefficients to be estimated using wideband modulated signals, suitable for implementation in measurements performed under real usage scenarios. In another variant, the technique enhances the precision of noisy S-parameter measurements, suitable for characterizations of wideband mm-wave components

An active load-pull technique creating time-variant impedances to emulate coupling between power amplifiers

A method for emulating antenna array coupling effects, based on active load-pull, to present time-varying impedances to power amplifiers is presented. An entire array, given identical elements, can be emulated using a single device-under-test. The method is demonstrated and verified by studying two scenarios, where the resulting adjacent channel power ratio and error-vector magnitude are given as function of delay and coupling for a 6W GaN power amplifier. Differences in adjacent channel power ratio and error-vector magnitude can be attributed to time-variant load impedances

Experimental Demonstration of Multiband Comb-Enabled mm-Wave Transmission

A novel system architecture to realize multiple synchronized sources for multiband millimeter-wave (mm-Wave) transmission has been designed and experimentally demonstrated in two of the W -band subbands at 100 and 112.5 GHz. The technique converts a distributed electro-optic comb, generated off-site, to a local electrical comb. The higher frequency tones in the resulting comb are extracted and used as mm-Wave oscillator sources. Thus, the architecture provides a method to generate multiple frequency-synchronized sources, using only a single electronic oscillator, with exceptionally low phase noise for simultaneous multiband mm-Wave transmission. Additionally, a lower frequency tone at 6.25 GHz is broadcasted over the air, providing synchronization reference between the mm-Wave transmitters and receivers

Measurement Technique to Emulate Signal Coupling Between Power Amplifiers

A measurement technique to emulate coupling between power amplifiers (PAs) such as that in an antenna array is presented. The case that the technique aims to emulate is referred to as the target array. The technique provides emulation of the distorted output signal for each PA under the coupling effect without the requirement for constructing the target physical coupling network or antenna array. Furthermore, given that the target array contains identical elements or PAs, transmitting either identical or different signals, the technique merely requires one PA as the device-under-test (DUT) to produce all output signals. The technique has direct connection to active load-pull, and aims to present the output of the DUT with corresponding time-varying impedances of each transmission path in the target array. The emulated output signals can then be analyzed, for example, in terms of adjacent channel power ratio, error vector magnitude, and normalized mean square error. Such measurement technique provides insight into the distortion and the impairment generated in the target array without the requirement to realize an actual array, and can be used, as an example, during the design stage of an array. The technique is theoretically motivated. The procedure is thoroughly described. The technique is experimentally demonstrated and verified under various usage cases and scenarios. Subsequent comparison to conventional active load-pull is provided

Experimental Demonstration of Spectrally Efficient Frequency Division Multiplexing Transmissions at E-Band

This paper presents the design and the experimental demonstration of transmission of spectrally efficient frequency division multiplexing (SEFDM) signals, using a single 5-GHz channel, from 81 to 86 CHz in the E-hand frequency allocation. A purpose-built E-band SEFDM experimental demonstrator, consisting of transmitter and receiver GaAs microwave integrated circuits, along with a complete chain of digital signal processing is explained. Solutions are proposed to solve the channel and phase offset estimation and equalization issues, which arise from the well-known intercarrier interference between the SEFDM signal subcarriers. This paper shows the highest transmission rate of 12 Gb/s over a bandwidth varying between 2.67 to 4 CHz depending on the compression level of the SEFDM signals, which results in a spectral efficiency improvement by up to 50%, compared to the conventional orthogonal frequency division multiplexing modulation format

Emulation of array coupling influence on RF power amplifiers in a measurement setup

A new method for emulating array coupling influence on RF power amplifiers in a measurements setup is presented. This method is based on an iterative procedure, where a signal is injected towards the output of the power amplifier, based on the output signal of the power amplifier measured in the previous iteration. Thus any coupling can be emulated by injecting an appropriately scaled signal. Emulation results are presented for a 6 W GaN amplifier. The results are verified using two identical amplifiers connected by a fixed attenuator

Estimation of Load-Pull Reflection Coefficients for Modulated Signals

A method to estimate reflection coefficients in a loadpull environment with modulated signals is proposed, which can be applied during the design stage and characterization of devices and components for next generation systems. The technique is based on least-square estimation of the impulse response of a finite impulse response filter. The proposed technique along with the conventional method are described and analyzed theoretically. The two approaches are experimentally demonstrated, verified, and compared using a load pull measurement setup with 6W GaN power amplifier as the device under test. The proposed technique shows better performance for both in-band and out-of-band estimation of reflection coefficients

Blind Receiver Distortion Compensation

A novel technique to compensate for the nonlinearity of a receiver (RX) is proposed and demonstrated experimentally. The adaptive technique is fully blind and does not require any prior knowledge of the transmitting signal. The technique has the capability to both characterize and compensate for the nonlinearity of the RX, making it suitable for implementations in both communication and instrumentation systems. For the former, two RXs operating simultaneously and an attenuator are required to enable real-time data transmission. For the latter, measurements using a single RX and an attenuator can be done instead. By utilizing the knowledge of the signals received at different input power levels, the proposed technique provides improvements to the RX linearity. The technique is demonstrated experimentally with an RF amplifier, where significant improvements quantified through multiple indicators, e.g., the adjacent channel power ratio, are observed

Measurement of Reflection and Transmission Coefficients Using Finite Impulse Response Least-Squares Estimation

A measurement technique to reduce the error of measured frequency-domain reflection and transmission coefficients, in particular, scattering parameters (S-parameters) measured with a vector network analyzer (VNA), and load reflection coefficients measured in wideband active load-pull system, is proposed. The technique models either the incident or reflected wave as the output of a finite impulse response (FIR) filter, and subsequently apply least-squares estimation (LSE) to estimate the reflection or transmission coefficients which minimize the error of said wave. When compared against the existing technique, the proposed technique offers precision improvement to the estimated reflection and transmission coefficients. Faster VNA measurements using up to 15-MHz intermediate frequency (IF) bandwidth are experimentally shown to be significantly improved to give good correspondence with slower measurements using 100-Hz IF bandwidth as reference. Error improvement across the measurement bandwidth of more than 17 dB is experimentally observed. Furthermore, the improvement is applicable to both the frequency regions with higher and lower signal to noise ratios of the reflected waves. On the other hand, applying the proposed technique in a wideband active load-pull system to estimate the load reflection coefficients, results in significant error improvement over the existing technique. The error improvement is also experimentally observed both in the in-band 3-dB bandwidth frequency region of the wideband modulated test signal and the out-of-band intermodulation frequency regions, where error improvement of 36 dB is observed