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<p> There are two popular approaches in the communication between multiple receivers and a base station with multiple antennas: dirty paper coding and multiuser diversity. Dirty paper coding can be rather difficult to realize, which motivates people to find some practical schemes. When there are a lot of users, multiuser diversity requires a lot of feedback which decrease the uplink spectrum efficiency.</p> <p> In this paper, we aim to minimize the probability of error subject to the total transmit power constraint and decrease the amount of feedback required by the multiuser diversity instead of trying to achieve the dirty paper coding. There are two main results in this thesis: First, we formulate the minimization of the average probability of error of all the users as a convex optimization problem, subject to the peak or the average power constraints. The proposed transmitter represents a nonlinear one-to-one mapping between the transmitted data vector and the symbol vector. The transmitted data vector going through the base station antennas is obtained as a solution to the proposed convex error probability optimization problem that can be solved using computationally efficient interior point algorithms. Furthermore, we propose a random unitary beamforming technique to reduce the feedback by selecting a threshold for the users. To improve fairness, an equal ratio scheduling algorithm which could serve the users with different rate requirements is developed. We also give an upper and lower bound on the sum rate achievable in our approach. Monte Carlo simulation results is provided to verify the performance of the proposed algorithms.</p> / Thesis / Master of Applied Science (MASc)

Thanks to a small wavelength (large bandwidth) combined with a low loss transmission window around 94 GHz and 120 GHz, the 75-120 GHz frequency band in millimeter wave (mm-wave) provides a promising opportunity for high data rate long range wireless communications and high-resolution imaging systems. Large-scale phased arrays have been exploited in such application for their beam forming and null steering capabilities, resulting in high directivity and improved SNR. But growing DC power consumption (Pdiss) in such large scale arrays has become an on-going concern along with noise, linearity and phase resolution trade-offs in current phased array architectures. To address these issues, we propose a power efficient phase shifter (PS) architecture based on quadrature hybrid coupler, which leverages the benefits of conventional active and passive PSs at mm-wave. The phase shifter has low loss, resulting in low power dissipation and the power domain phase interpolation by the quadrature hybrid gives low phase error and high linearity. We design W-band (90-100 GHz) phased array transmit and receive (T/R) modules in 130 nm SiGe BiCMOS technology based on the proposed PS and our measurements show high power efficiency with the lowest power consumption at W-band to our knowledge (18mW and 26mW power dissipations at receiver (Rx) and transmitter (Tx) front-ends respectively). Rx shows 23 to 25 dB peak gain, 6 to 9.3 dB NF and Tx can deliver upto 7 dBm output power with 18% power efficiency. Moreover, our PS can achieve 5-bit phase resolution with <2 degrees RMS phase error and provides 0 dBm saturated output power at 94 GHz. The phase shifter (PS) is also scalable beyond W-band without significant loss. We demonstrate this with a 120 GHz two channel phased array receiver (Rx), where a single channel shows 15.6 dB peak gain with Pdiss=53 mW which shows one of the highest gain efficiency (gain/Pdiss) among D-band phased arrays. We can further reduce the power consumption by leveraging the bidirectional signal processing at the phased array front-end. To achieve this, we designed a W-band bidirectional variable gain amplifier with gain variation ranging from 6 to -1 dB at 94 GHz which can be used along with bidirectional PS. The amplifier will replace the lossy SPDT switch in the conventional bidirectional approach, reducing the overall power consumption. / Ph. D. / The wireless technology is pushing towards the high operating frequencies to achieve high data rate and 75-120 GHz frequency band in millimeter wave (mm-wave) are of great current interest for the backhaul communications, radar and imaging systems. However, high frequency yields high propagation loss which has been overcome with large scale phased arrays in such applications for their high directivity, narrow beam forming capabilities and implementation with silicon technologies. The high dissipation due to large number of elements is a major concern which often requires heat sinks around the sensors leading to increase in cost, size and weight. For the large silicon array to be of practical use in commercial systems, it is paramount to maintain a high power efficiency and low power dissipation in the array element. In this research, a power efficient phased array architecture has been proposed which is implemented to design transmit/receive (T/R) modules in advanced silicon technologies. Experimental results show that the proposed architecture achieves the lowest power consumption and improved power efficiency per T/R element among state-of-the-art mm-wave phased arrays. The research also proposes an alternative way to improve power efficiency of phased arrays by reusing the amplifiers in both transmit and receive path where the amplifier replaces lossy switch as well, resulting in a low loss bidirectional system which can reduce the power consumption further. Finally, we believe that this research contribution has an significant impact in the effort of building low power large-scale phased arrays at mm-wave frequencies.

Test and evaluation (TandE) is a critically important step before in-the-field deployment of radio-frequency (RF) hardware in order to assure that the hardware meets its design requirements and specifications. Typically, TandE is performed either in a lab setting utilizing a software simulation environment or through real-world field testing. While the former approach is typically limited by the accuracy of the simulation models (particularly of the anticipated hardware effects) and by non-real-time data rates, the latter can be extremely costly in terms of time, money, and manpower. To build upon the strengths of these approaches and to mitigate their weaknesses, this work presents the development of an FPGA-based TandE tool that allows for real-time pseudo-random aggregate signal generation for testing RF receiver hardware (such as communication receivers, spectrum sensors, etc.). In particular, a framework is developed for an FPGA-based implementation of a test signal emulator that generates randomized aggregate spectral environments containing signals with random parameters such as center frequencies, bandwidths, start times, and durations, as well as receiver and channel effects such as additive white Gaussian noise (AWGN). To test the accuracy of the developed spectrum generation framework, the randomization properties of the framework are analyzed to assure correct probability distributions and independence. Additionally, FPGA implementation decisions, such as bit precision versus accuracy of the generated signal and the impact on the FPGA's hardware footprint, are analyzed.This analysis allows the test signal engineer to make informed decisions while designing a hardware-based RF test system. This framework is easily extensible to other signal types and channel models, and can be used to test a variety of signal-based applications. / Master of Science / Test and evaluation (TandE) is a critically important step before in-the-field deployment of radio-frequency signal hardware in order to assure that the hardware meets its design requirements and specifications. Typically, TandE is performed either in a lab setting utilizing a software simulation or through real-world field testing. While the former approach is typically limited by the accuracy of the simulation models and by slower data rates, the latter can be extremely costly in terms of time, money, and manpower. To address these issues, a hardware-based signal generation approach that takes the best of both methods mentioned above is developed in this thesis. This approach allows the user to accurately model a radio-frequency system without requiring expensive equipment. This work presents the development of a hardware-based TandE tool that allows for real-time random signal generation for testing radio-frequency receiver hardware (such as communication receivers). In particular, a framework is developed for an implementation of a test signal emulator that allows for user-defined randomization of test signal parameters such as frequencies, signal bandwidths, start times, and durations, as well as communications receiver effects. To test the accuracy of the developed emulation framework, the randomization properties of the framework are analyzed to assure correct probability distributions and independence. Additionally, hardware implementation decisions such as bit precision versus quality of the generated signal and the impact on the hardware footprint are analyzed. Ultimately, it is shown that this framework is easily extensible to other signal types and communication channel models.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Flight Safety concerns increase proportionally with increasing missile performance. These concerns are greatest in the near launch arena where a missile has the greatest potential energy. Systems such as radar, GPS tracking systems, and optics are normally of limited use in this arena for a number of reasons. A system was required that would provide useful tracking data in the first few seconds of a missile launch. This system has met that requirement providing nominal path deviation data from the launcher out to as much as 120 seconds. The tracking system described herein uses the principle of radio interferometry to derive phase difference measurements between carefully spaced antennas. These measurements are transmitted to the Operational Display Facility and converted to a usable angular deviation plot for use by Flight Safety Personnel. This paper provides an elementary radio interferometer system background and discusses this particular system setup and use. Some detail is provided on the premission simulation and setup of the system as well as the real-time display setup and output of the final data product.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / With every new spacecraft that is designed comes a greater density of information that will be stored once it is in operation. This, coupled with the desire to reduce the number of ground stations needed to download this information from the spacecraft, places new requirements on telemetry transmitters. These new transmitters must be capable of data rates of 320 Mbps and beyond. Although the necessary bandwidth is available for some non-bandwidth-limited transmissions in Ka-Band and above, many systems will continue to rely on more narrow allocations down to X-Band. These systems will require filtering of the modulation to meet spectral limits. The usual requirements of this filtering also include that it not introduce high levels of inter-symbol interference (ISI) to the transmission. These constraints have been addressed at CE by implementing a DSP technique that pre-filters a QPSK symbol set to achieve bandwidth-limited 320 Mbps operation. This implementation operates within the speed range of the radiation-hardened digital technologies that are currently available and consumes less power than the traditional high-speed FIR techniques.

Low power, high speed serial transceivers are employed in a wide range of applications ranging from chip-to-chip, backplane, and optical interconnects. Apart from being capable of handling a wide range of data rates, the transceivers should have low power consumption (mW/Gbps) and be fully integrated. This work discusses enabling techniques to implement such transceivers. Specifically, three designs: (1) a 0.5-4 Gbps serial link which uses current recycling to reduce power dissipation and (2) a 0.5-2.5 Gbps reference-less clock and data recovery circuit which uses a novel frequency detector to achieve unlimited acquisition range and (3) a 2-4 Gbps low power receiver architecture capable of resolving multiple signalling formats with a simplified XOR based phase rotating PLL will be presented. All the three circuit topologies are highly digital and aim to address the requirements of wide operating range, low power dissipation while being fully integrated. Measured results obtained from the prototypes illustrate the effectiveness of the proposed design techniques. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from Dec. 2, 2011 - June 2, 2012

The objective of the proposed research is to develop simplified reconfigurable transmission systems with frequency multipliers for the transmission of complex modulated signals. Because they rely on nonlinear properties, frequency multiplier-based transmission systems require proper linearization techniques and accurate modeling of the signal transfer function. To accomplish these two goals, the author has developed techniques to model and linearize frequency multipliers and to digitize feedback signals for nonlinear characterization. First, adaptive predistortion techniques and zonal transfer theories have been developed for modeling and linearization. The predistortion system has been verified by applying an IS-95B signal to various frequency multipliers built by the author. Second, because the output signals at higher harmonic zones occupy wider frequency bandwidths than the signal in the fundamental zone does and thus make it harder to use traditional sampling techniques, a simplified but effective method called the sub-Nyquist sampling rate was developed and verified. Third, two methods for reconfigurable transmitters using frequency multipliers in conjunction with digital predistortion linearizers were developed. Both methods make it possible to transmit complex signals via frequency multipliers by using dual-band transmission systems that incorporate frequency multipliers that are based on linearization techniques. One of these methods uses a circuit topology that can be switched between a fundamental-mode in-phase combined amplifier and a push-push frequency doubler using input phasing. The second suggested method uses a fundamental-frequency power amplifier followed by a varactor multiplier that can be bypassed with an RF switch. This work will contribute to the development of low-cost and size-effective reconfigurable transmission systems because it requires fewer transmitting components and needs less sampling of the feedback networks.

This dissertation is aimed at examining signal integrity degradation factors and realizing signal integrity enhancement circuits for both wired and wireless communication systems. For wired communication systems, an optical coherent system employing an electrical equalization circuit is studied as a way of extending the transmission distance limited by optical fiber dispersion mechanisms. System simulation of the optical coherent receiver combined with the feed-forward equalizers is performed to determine the design specification of the equalizer circuit. The equalization circuit is designed and implemented in a 0.18 µm complementary metal-oxide semiconductor (CMOS) process and demonstrates the capability to extend the transmission reach of long-haul optical systems over single-mode fiber to 600 km. Additionally, for wireless applications, signal integrity issues found in a full-duplex wireless communication network are examined. Full-duplex wireless systems are subject to interference from their own transmitter leakage signals; thus, a transmitter leakage cancellation circuit is designed and implemented in a 0.18 µm CMOS technology. The proposed cancellation circuit is integrated with a low-noise amplifier and demonstrates over 20 dB of transmitter leakage signal suppression.