Study of continuous-phase four-state modulation for cordless telecommunications. Assessment by simulation of CP-QFSK as an alternative modulation scheme for TDMA digital cordless telecommunications systems operating in indoor applications

One of the major driving elements behind the explosive boom in wireless revolution is the advances in the field of modulation which plays a fundamental role in any communication system, and especially in cellular radio systems. Hence, the elaborate choice of an efficient modulation scheme is of paramount importance in the design and employment of any communications system. Work presented in this thesis is an investigation (study) of the feasibility of whether multilevel FSK modulation scheme would provide a viable alternative modem that can be employed in TDMA cordless communications systems. In the thesis the design and performance analysis of a non-coherent multi-level modem that offers a great deal of bandwidth efficiency and hardware simplicity is studied in detail. Simulation results demonstrate that 2RC pre-modulation filter pulse shaping with a modulation index of 0.3, and pre-detection filter normalized equivalent noise bandwidth of 1.5 are optimum system parameter values. Results reported in chapter 5 signify that an adjacent channel rejection factor of around 40 dB has been achieved at channel spacing of 1.5 times the symbol rate while the DECT system standards stipulated a much lower rejection limit criterion (25-30dB), implying that CP-QFSK modulation out-performs the conventional GMSK as it causes significantly less ACI, thus it is more spectrally efficient in a multi-channel system. However, measured system performance in terms of BER indicates that this system does not coexist well with other interferers as at delay spreads between 100ns to 200ns, which are commonly encountered in such indoor environment, a severe degradation in system performance apparently caused by multi-path fading has been noticed, and there exists a noise floor of about 40 dB, i.e. high irreducible error rate of less than 5.10-3. Implementing MRC diversity combiner and BCH codec has brought in a good gain.Higher Education Ministr

Modulation and Multiple Access Techniques for Ultra-Wideband Communication Systems

Two new energy detection (ED) Ultra-Wideband (UWB) systems are proposed in this dissertation. The first one is an ED UWB system based on pulse width modulation (PWM). The bit error rate (BER) performance of this ED PWM system is slightly worse than ED pulse position modulation (PPM) system in additive white Gaussian noise (AWGN) channels. However, the BER performance of this ED PWM system surpasses that of a PPM system in multipath channels since a PWM system does not suffer cross-modulation interference (CMI) as a PPM system. In the presence of synchronization errors, the BER performance of a PWM system also surpasses that of a PPM system. The second proposed ED UWB system is based on using two pulses, which are the different-order derivatives of the Gaussian pulse, to transmitted bit 0 or 1. These pulses are appropriately chosen to separate their spectra in frequency domain.The receiver is composed of two energy detection branches and each branch has a filter which captures the signal energy of either bit 0 or 1. The outputs of two branches are subtracted from each other to generate the decision statistic and the value of this statistic is compared to a threshold to determine the transmitted bits. This system is named as acf{GFSK} system in this dissertation and it exhibits the same BER performance as a PPM system in AWGN channels. In multipath channels, a GFSK system surpasses a PPM system because it does not suffer CMI. And the BER performance of a GFSK system is better than a PPM system in the presence of synchronization errors. When a GFSK system is compared to a PWM system, it will always achieve approximately 2 dB improvement in AWGN channels, multipath channels, and in the presence synchronization errors. However, a PWM system uses lower-order derivatives of the Gaussian pulse to transmit signal, and this leads to a simple pulse generator. In this dissertation, an optimal threshold is applied to improve PPM system performance. The research results show that the application of an optimal threshold can e

Modulation and Multiple Access Techniques for Ultra-Wideband Communication Systems

Two new energy detection (ED) Ultra-Wideband (UWB) systems are proposed in this dissertation. The first one is an ED UWB system based on pulse width modulation (PWM). The bit error rate (BER) performance of this ED PWM system is slightly worse than ED pulse position modulation (PPM) system in additive white Gaussian noise (AWGN) channels. However, the BER performance of this ED PWM system surpasses that of a PPM system in multipath channels since a PWM system does not suffer cross-modulation interference (CMI) as a PPM system. In the presence of synchronization errors, the BER performance of a PWM system also surpasses that of a PPM system. The second proposed ED UWB system is based on using two pulses, which are the different-order derivatives of the Gaussian pulse, to transmitted bit 0 or 1. These pulses are appropriately chosen to separate their spectra in frequency domain.The receiver is composed of two energy detection branches and each branch has a filter which captures the signal energy of either bit 0 or 1. The outputs of two branches are subtracted from each other to generate the decision statistic and the value of this statistic is compared to a threshold to determine the transmitted bits. This system is named as acf{GFSK} system in this dissertation and it exhibits the same BER performance as a PPM system in AWGN channels. In multipath channels, a GFSK system surpasses a PPM system because it does not suffer CMI. And the BER performance of a GFSK system is better than a PPM system in the presence of synchronization errors. When a GFSK system is compared to a PWM system, it will always achieve approximately 2 dB improvement in AWGN channels, multipath channels, and in the presence synchronization errors. However, a PWM system uses lower-order derivatives of the Gaussian pulse to transmit signal, and this leads to a simple pulse generator. In this dissertation, an optimal threshold is applied to improve PPM system performance. The research results show that the application of an optimal threshold can e

Proceedings of the Fifth International Mobile Satellite Conference 1997

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial communications services. While previous International Mobile Satellite Conferences have concentrated on technical advances and the increasing worldwide commercial activities, this conference focuses on the next generation of mobile satellite services. The approximately 80 papers included here cover sessions in the following areas: networking and protocols; code division multiple access technologies; demand, economics and technology issues; current and planned systems; propagation; terminal technology; modulation and coding advances; spacecraft technology; advanced systems; and applications and experiments

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion