In this thesis, we take an application of multiple symbol differential detection (MSDD) technique in direct-sequence code division multiple access (CDMA) system. It is well- known that MSDD is an effective noncoherent demodulator which outperform the conventional M-ary differential phase shift keying (MDPSK) in additive white Gaussian noise (AWGN) channel. Take MPSK demodulator into consideration, the performance of MSDD based on noncoherent demodulation approaches the performance of coherent demodulation. However, there is little research about MSDD in frequency-selective fading channel. We are now combining the MSDD and Rake receiver to be the signal demodulator. In conventional, there are two kinds of Rake receivers. One is coherent demodulator. Another is noncoherent demodulator. For coherent demodulation, it needs to have channel estimation at each path. The advantage is that the performance will be improved. On the other hand, the disadvantage is complexity and operation will increase. On the contrast, for noncoherent demodulation, it is the performance degradation and complexity simplification. In this thesis, We suggest a multiple symbol differential detection on Rake receiver for CDMA system. From our computer simulation, only for hard decision, the performance is improved and the improvement is proportional to the number of multipath and the number of the length of multiple symbol. This will not happen in conventional MDPSK. However, from our observation, the improvement of performance is degrading as the number of multipath increase. Thus, we employee the technique of Viterbi decoding differential detection (VDDD) to demodulate the differential sequence. By the property of decision interval, the VDDD can obtain additional improvement.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / Shaped Offset Quadrature Shift Keying (SOQPSK) is a spectrally efficient modulation that has been promoted in the airborne telemetry community as a more spectrally efficient alternative for legacy PCM/FM. First generation demodulators for SOQPSK use coherent detectors which achieve good bit error rates at the expense of long synchronization times. This paper examines the performance of a noncoherent SOQPSK detector which significantly improves the signal acquisition times without impacting BER performance in the AWGN environment. The two detection methods are also compared in their ability to combat other channel impairments, such as adjacent and on-channel interference.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Binary PCM/FM has been widely adopted as a standard by the telemetry community. It offers a reasonable balance between detection efficiency and spectral efficiency, with very simple implementation in both the transmitter and receiver. Current technology, however, allows practical implementations of more sophisticated demodulators, which can substantially improve the detection efficiency of the waveform, with no changes to the modulator. This is accomplished by exploiting the memory inherent in the phase continuity of the waveform. This paper describes the implementation and performance of a noncoherent multi-symbol demodulator for PCM/FM. Sensitivity to offsets in carrier frequency, timing, and modulation index is also examined. Simulation results are presented which demonstrate improvements in detection efficiency of approximately 2.5 dB over traditional noncoherent single symbol detectors.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / It has been previously shown, through computer simulations, that a multiple symbol detector can provide substantial gains in detection efficiency (nearly 3 dB) over traditional PCM/FM detectors. This is accomplished by performing correlations over multiple symbol intervals to take advantage of the memory inherent in the continuous phase PCM/FM signal. This paper presents measured hardware results, from a prototype developed for the Advanced Range Telemetry (ARTM) Project, that substantiate the previously published performance and sensitivity predictions. Furthermore, this work confirms the feasibility of applying this technology to high-speed commercial and military telemetry applications.

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / With the characteristics of constant envelope and continuous phase, Continuous Phase Modulation (CPM) signal has higher spectrum efficiency and power efficiency than other modulation forms. A noncoherent demodulation with Viterbi decoding for partial response CPM signals is proposed. Simulation results indicate that the demodulation performance of proper partial response CPM is better than the traditional PCM-FM, which is a typical modulation of full response CPM. And higher spectral efficiency is also obtained by partial response CPM.

Noncoherent modulation is an important technique in wireless communication systems. Although noncoherent modulation usually does not perform as well as its coherent counterpart it is practical and useful in some applications, such as paging systems. In this thesis we investigate ways to improve the performance of noncoherent FSK in narrowband channels. It is shown that FSK permutation modulation has better spectral efficiency than conventional FSK modulation" but with the tradeoff on reduced energy efficiency. To overcome this problem, we apply trellis-coded modulation (TCM) , which is a combined technology of convolutional coding and modulation, to FSK permutation. TCM was originally designed for coherent modulation. The application of TCM to permutation modulation retains the fundamental concepts of TCM. The simulation results show that trellis-coded permutation modulation provides a better combination of energy efficiency and spectral efficiency than conventional FSK noncoherent demodulation. / Master of Science

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Approved for public release, distribution is unlimited / The performance of coherent and noncoherent RAKE receivers over a fading channel in the presence of pulse-noise interference and additive white Gaussian noise is analyzed. Coherent RAKE receivers require a pilot tone for coherent demodulation. Using a first order phase-lock-loop to recover a pilot tone with additive white Gaussian noise causes phase distortions at the phase-lock-loop output, which produce an irreducible phase noise error floor for soft decision Viterbi decoding. Both coherent and noncoherent RAKE receivers optimized for additive white Gaussian noise perform poorly when pulse-noise interference is present. When soft decision convolutional coding is considered, the performance degrades as the duty cycle of the pulse-noise interference signal decreases. The reverse is true for hard decision Viterbi decoding, since fewer bits experience interference and bit errors with high noise variance cannot dominate the decision statistics. Soft decision RAKE receiver optimized for pulse-noise interference and additive white Gaussian noise performed the best for both the coherent and noncoherent RAKE receivers. This receiver scales the received signal by the inverse of the variance on a bit-by-bit basis to minimize the effect of pulse-noise interference. The efficacy is demonstrated by analytical results, which reveal that this receiver reduces the probability of bit error down to the irreducible phase noise error floor when pulse-noise interference is present. This demonstrates how important it is to design the receiver for the intended operational environment. / Civilian, Department of Defense

This thesis focuses on the concept of uniquely factorable constellations (UFCs) in the design of space-time block codes (STBCs) for wireless communication systems using three different approaches. Based on intelligent constellation collaboration, UFCs can provide the systematic design of a full diversity code with improved coding gain. Firstly, motivated by the energy-efficient hexagonal lattice carved from the Eisenstein integer domain, hexagonal UFCs and hexagonal uniquely factorable constellation pairs (UFCPs), of various sizes, are constructed for a noncoherent single-input multiple-output (SIMO) system. It is proved that these designs assure the blind unique identification of channel coefficients and transmitted signals in a noise-free case and full diversity for the noncoherent maximum likelihood (ML) receiver in a noisy case. In addition, an optimal energy scale is found to maximize the coding gain. Secondly, using a matrix similar to the Alamouti matrix and the UFCP concept based on the quadrature amplitude modulation (QAM) constellation, a novel energy-efficient unitary STBC is designed for a noncoherent multiple-input single-output (MISO) system with two transmitter antennas and one receiver antenna by using the QR decomposition. It is shown that the proposed UFCP-STBC design also allows for the blind unique identification of both the transmitted signals and channel coefficients as well as full diversity. In addition, an optimal unitary UFCP-STBC is devised to maximize the coding gain subject to a transmission bit rate constraint. The last approach is to demonstrate how the UFCP concept is applied to the systematic design of a coherent relay network coding system. A class of uniquely factorable Alamouti matrix pairs is proposed for the design of a novel amplify-forward relay network coding scheme, which allows the relay node to transmit its own information. By carefully making use of the Alamouti coding structure and strategically encoding the signals from the two antennas at the relay node, the resulting coding scheme enables the optimal full diversity gain and better coding gain for the ML detector. Comprehensive computer simulations show that the three uniquely factorable designs presented in this thesis have the best error performance compared to the current designs in literature. / Thesis / Candidate in Philosophy