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

Phase-locked loop digital FM receiver for wireless communications

Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (p. 77-79).by Thunyachate Ekvetchavit.S.B.and M.Eng

2022, nr 2, JTIT

kwartalni

Design, Implementation, and Analysis of Electrical System Architecture for CubeSat to Ground Communications

CubeSats facilitate a low barrier to entry in University and Industrial space research. With the rapid, low-cost development of CubeSats, the need for a reliable and ro- bust communications subsystem becomes evident to ensure mission accomplishment. With the advent of Software Defined Radio, Old Dominion University is compelled to upgrade the rigid Legacy Hardware systems in place with inexpensive and flexible Software Defined Radio Solutions. Currently, Old Dominion University is on the cusp of conducting its first space science mission as a member organization of the Virginia Space Grant Consortium Cubesat Constellation and is manifest for launch on April 17, 2019 NASA Wallops Flight Facility. To conduct this mission, the design and construction of a 1U Nano-Satellite and the upgrade to existing ground station architecture was necessary. To relay data in a point-to-point fashion as required by the Science Mission, Old Dominion University has developed custom ground station hardware and software to communicate with its own satellite and the satellites of others. This thesis presents the salient design aspects in implementing a complete electrical system architecture for a 1U spacecraft and the upgrades required in the Ground Station Architecture to support the required demodulation and decoding of a 9600 baud GMSK signal from a model of the deployed satellite necessary to conduct a true science research mission as part of a University Satellite Constellation. The demodulating signal processing steps are designed in GNU Radio Companion and deals with parts of the AX.25 data link layer protocol. Additionally, analysis shall be presented to highlight the design choices made for both the spacecraft and the ground station and will demonstrate various system parameters and characteristics of interest based on the Orbital Simulation results obtained from Systems Toolkit (STK). Finally, results of the architecture design shall be reported on the system by measuring Communications Link Performance benchmarks such as Bit-Error-Rates (BER) and Signal-To-Noise Ratios (SNR)

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

Strategic Analysis of Cellular M2M Communication Opportunities within the Smart Energy Industry

This paper applies a strategic analysis framework to analyze a new market opportunity for Sierra Wireless within the smart energy industry. It considers the industry value chain and competitive forces that influence the market structure to identify opportunities and challenges. The core competence-based view of the firm recognizes the existing strengths and competitive advantages that Sierra Wireless can leverage for profitable growth within the market. As different strategies are required for new and existing markets, this report identifies which of the existing competitive advantages Sierra Wireless should apply to the emerging smart energy market. Recommendations present strategy to manage, develop, and apply Sierra Wireless\u27 core competencies

Hybrid ARQ with parallel and serial concatenated convolutional codes for next generation wireless communications

This research focuses on evaluating the currently used FEC encoding-decoding schemes and improving the performance of error control systems by incorporating these schemes in a hybrid FEC-ARQ environment. Beginning with an overview of wireless communications and the various ARQ protocols, the thesis provides an in-depth explanation of convolutional encoding and Viterbi decoding, turbo (PCCC) and serial concatenated convolutional (SCCC) encoding with their respective MAP decoding strategies.;A type-II hybrid ARQ scheme with SCCCs is proposed for the first time and is a major contribution of this thesis. A vast improvement is seen in the BER performance of the successive individual FEC schemes discussed above. Also, very high throughputs can be achieved when these schemes are incorporated in an adaptive type-II hybrid ARQ system.;Finally, the thesis discusses the equivalence of the PCCCs and the SCCCs and proposes a technique to generate a hybrid code using both schemes