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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Cooperative diversity and downlink power control using PARPS with application to LTE services (eMBMS and CoMP)

Atif, Sohaib January 2014 (has links)
Mobile devices and their applications are continuing to develop and the more advanced they are, the more they require high data ranges and the more they demand of the available wireless communication networks. At present, LTE (Long Term Evolution) is a good solution as it provides the users of mobile devices with a good throughput and a low latency. In the future, the two most important aspects for end users will be system spectral efficiency and system power controlling. This thesis deals with LTE downlink spectral efficiency and power controlling. The thesis will show how, by using IP multicasting for the LTE downlink, the base station is able to provide the necessary data through a significantly smaller spectrum and, additionally, how cooperative diversity, i.e. the cooperation between several base stations, can improve or even maximise the total network channel capacity, regardless of bandwidth size. A Packet and Resource Plan Scheduling algorithm (PARPS) is used to schedule the transmissions, and the results are calculated in MATLAB. By this means it is possible to analyse the efficiency of the spectrum management, the coverage probability and the power controlling for the different transmitters used for the LTE downlink.The LTE downlink scheme is simulated in Matlab for different numbers of transmitters (2-3). IP multicasting over the LTE downlink manages to transmit the same amount of data using less transmission power (50- 66.6%) with a better system spectral efficiency.


Geoghegan, Mark 10 1900 (has links)
International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Shaped Offset QPSK (SOQPSK), as proposed and analyzed by Terrance Hill, is a family of constant envelope waveforms that is non-proprietary and exhibits excellent spectral containment and detection efficiency. Results using a conventional coherent OQPSK demodulator without any special pulse shaping to recover the SOQPSK signal have been previously presented. This paper describes a trellis detector for SOQPSK-A and SOQPSK-B that provides superior detection performance, as compared to a traditional OQPSK detector, by accounting for the pulse shaping. Analytical error performance bounds, implementation of the trellis demodulator, and computer simulation results are presented.


Geoghegan, Mark 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / The Advanced Range Telemetry (ARTM) program is a tri-service telemetry modernization project whose goal is to assure that all Department of Defense (DoD) test and training ranges are able to use telemetry as necessary to carry out their respective missions. Multi-h Continuous Phase Modulation (CPM) has been selected by the ARTM JPO as the Tier II ARTM waveform, because it offers significant improvements over both legacy telemetry waveforms (PCM/FM) and the newly-introduced Tier I waveform (Feher-patented FQPSK) in terms of spectral containment and detection efficiency, while retaining a constant envelope characteristic. The paper describes the theoretical and measured performance of the ARTM Tier II multi-h CPM waveform, and the implementation of the trellis demodulator being developed for it.

IP Multicasting over DVB-T/H and eMBMS : Efficient System Spectral Efficiency Schemes for Wireless TV Distributions

Rahman, S.M. Hasibur January 2012 (has links)
In today’s DVB-T/H (Digital Video Broadcasting-Terrestrial/Handheld) systems, broadcasting is employed, meaning that TV programs are sent over all transmitters, also where there are no viewers. This is inefficient utilization of spectrum and transmitter equipment. IP multicasting is increasingly used for IP-TV over fixed broadband access. In this thesis, IP multicasting is proposed to also be used for terrestrial and mobile TV, meaning that TV programs are only transmitted where viewers have sent join messages over an interaction channel. This would substantially improve the system spectral efficiency (SSE) in (bit/s)/Hz/site, allowing reduced spectrum for the same amount of TV programs. It would even further improve the multiuser system spectral efficiency (MSSE – a measure defined in this study), allowing increased number of TV programs to be transmitted over a given spectrum. Further efficiency or coverage improvement, may be achieved by forming single-frequency networks (SFN), i.e. groups of adjacent transmitters sending the same signal simultaneously, on the same carrier frequency. The combination of multicasting and SFNs is also the principle of eMBMS (evolved Multicast Broadcast Multimedia Service) for cellular mobile TV over 4G LTE. PARPS (packet and resource plan scheduling) is an optimized approach to dynamically forming SFNs that is employed in this study. The target applications are DVB-T/H and eMBMS. Combining SFNs with non-continuous transmission (switching transmitters on and off dynamically) may give even further gain, and is used in LTE, but is difficult to achieve in DVB-T/H. Seven schemes are suggested and analyzed, in view to compare unicasting, multicasting and broadcasting, with or without SFN, with or without PARPS, and with or without continuous transmission. The schemes are evaluated in terms of coverage probability, SSE and MSSE. The schemes are simulated in MATLAB for a system of 4 transmitters, with random viewer positions. Zipf-law TV program selection is employed, using both a homogeneous and heterogeneous user behavior model. The SFN schemes provide substantially better system spectral efficiency compared to the multi-frequency networks (MFN) schemes. IP multicasting over non-continuous transmission dynamic SFN achieves as much as 905% and 1054% gain respectively in system spectral efficiency and multiuser system  spectral efficiency, from broadcasting over MFN, and 425% and 442% gain respectively from  IP multicasting over MFN, for heterogeneous fading case. Additionally, the SFN schemes gives a diversity gain of 3 dB over MFN, that may be utilized to increase the coverage probability by 4.35% for the same data rate, or to increase the data rate by 27 % for the same coverage as MFN.   Keywords: IP multicasting, broadcasting, coverage probability, system spectral efficiency, multiuser system spectral efficiency, DVB-T/H, eMBMS, mobile TV, IP-TV, SFN, MFN, Dynamic SFN, PARPS, homogeneous, heterogeneous, zipf-law

Spatial Spectral Efficiency Analysis for Wireless Communications

Zhang, Lei 19 August 2014 (has links)
Spectrum utilization efficiency is one of the primary concerns in the design of future wireless communication systems. Most performance metrics for wireless communication systems focus on either link level capacity or network throughput while ignore the spatial property of wireless transmissions. In this dissertation, we focus on the spatial spectral utilization efficiency of wireless transmissions. We first study the spatial spectral efficiency of single-cell and multi-cell wireless relay systems using area spectral efficiency (ASE) performance metric. We then generalize the performance metric, termed as generalized area spectral efficiency (GASE), to measure the spatial spectral utilization efficiency of arbitrary wireless transmissions. In particular, we first introduce the definition of GASE by illustrating its evaluation for conventional point-to-point transmission. Then we extend the analysis to four different transmission scenarios, namely dual-hop relay transmission, three-node cooperative relay transmission, two-user X channels, and underlay cognitive radio transmission. Finally, we apply the GASE performance metric to investigate the spatial spectral efficiency of wireless network with Poisson distributed nodes and quantify the spatial spectral opportunities that could be explored with secondary cognitive systems. Our research on the spatial spectral utilization efficiency provides a new perspective on the designing of wireless communication systems, especially on the transmission power optimization and space-spectrum resource exploitation. / Graduate / 0544 / leizhang@uvic.ca


Shaw, Christopher, Rice, Michael 10 1900 (has links)
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 / This paper considers the use of Amplitude-Phase Shift Keying (APSK) for a telemetry system. Variable rate turbo codes are used to improve the power efficiency of 16- and 32-APSK. We discuss compensation techniques for power amplifier nonlinearities. Simulation results show the improved spectral efficiency of this modulation scheme over those currently defined in telemetry standards.


Bruns, Tom 10 1900 (has links)
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.


Fewer, Colm, Wilmot, Sinbad 10 1900 (has links)
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 / Since the 1970s PCM/FM has been the dominant modulation scheme used for RF telemetry. However more stringent spectrum availability as well as increasing data rates means that more advanced transmission methods are required to keep pace with industry demands. ARTM Tier-I and Tier-II are examples of how the PCM/FM link can be enhanced. However these techniques require a significant increase in the complexity of the receiver/detector for optimal recovery. This paper focuses on a quantitative approach to improving the rate and quality of data using existing PCM/FM links. In particular ACRA CONTROL and BAE SYSTEMS set themselves the goal of revisiting the pre-modulation filter, diversity combiner and bit-sync. By implementing programmable adaptive hardware, it was possible to explore the various tradeoffs offered by modifying pulse shapes and spectral occupancy, inclusion of forward error correction and smart source selection. This papers looks at the improvements achieved at each phase of the evaluation.

Energy-efficient design in wireless communications networks

Xiong, Cong 27 August 2014 (has links)
The widespread application of wireless services and the requirements of ubiquitous access have recently triggered rapidly booming energy consumption in wireless communications networks. Such escalation of energy consumption in wireless networks causes high operational expenditure from electricity bills for operators, unsatisfactory user experience due to limited battery capacity of wireless devices, and a large amount of greenhouse gas emission. Green radio (GR), which emphasizes both energy efficiency (EE) and spectral efficiency (SE), has been proposed as an effective solution and is becoming the mainstream for future wireless network design. Unfortunately, EE and SE do not always coincide and may even sometimes conflict. In this dissertation, we focus on energy-efficient transmission and resource allocation techniques for orthogonal frequency division multiple access (OFDMA) networks and the joint energy-efficient design of OFDMA and other promising wireless communications techniques, such as cognitive radio (CR) and two-way relay. Firstly, we investigate the principles of energy-efficient design for pure OFDMA networks. As the first step, we study the fundamental interrelationship between EE and SE in downlink OFDMA networks and analyze the impacts of channel gain and circuit power on the EE-SE relationship. We establish a general EE-SE optimization framework, where the overall EE, SE and per-user quality-of-service (QoS) are all considered. Under this framework, we find that EE is quasiconcave in SE and decreases with SE when SE is large enough. These findings are very helpful guidelines for designing energy- and spectral-efficient OFDMA. To facilitate the application of energy-efficient resource allocation, we then investigate the energy-efficient resource allocation in both downlink and uplink OFDMA networks. For the downlink transmission, the generalized EE is maximized while for the uplink case the minimum individual EE is maximized, both under prescribed per-user minimum data rate requirements. For both transmission scenarios, we first provide the optimal solution and then develop an computationally efficient suboptimal approach by exploring the inherent structure and property of the energy-efficient design. Then we study energy-efficient design in downlink OFDMA networks with effective capacity-based delay provisioning for delay-sensitive traffic. By integrating information theory with the concept of effective capacity, we formulate and solve an EE optimization problem with statistical delay provisioning. We also analyze the tradeoff between EE and delay, the relationship between spectral-efficient and energy-efficient designs, and the impact of system parameters, including circuit power and delay exponents, on the overall performance. Secondly, we consider joint energy-efficient design of OFDMA and CR and two-way relay, respectively, to further enhance the EE and SE of wireless networks. We study energy-efficient opportunistic spectrum access strategies for an OFDMA-based CR network with multiple secondary users (SUs). Both worst EE and average EE of the SUs are considered and optimized subject to constraints including maximum transmit power and maximum interference to primary user (PU) system. For both cases, we first find the optimal solution and then propose a low-complexity suboptimal alternative. The results show that the energy-efficient CR strategies significantly boost EE compared with the conventional spectral-efficient CR ones while the low-complexity suboptimal approaches can well balance the performance and complexity. Then we study energy-efficient resource allocation for OFDMA-based two-way relay, which aims at maximizing the aggregated EE utility while provisioning proportional fairness in EE among different terminal pairs. Different from most exist energy-efficient design, we consider a new circuit power model, where the dynamic circuit power is proportional to the number of active subcarrier. For low-complexity solution, we propose an EE-oriented sequential subchannel assignment policy and discover the sufficient condition for early termination of the sequential subchannel assignment without losing the EE optimality. It is found that the energy-efficient transmission does not necessarily make all the subcarriers active, which is another useful principle for practical energy-efficient system design.


Gao, Wei, Feher, Kamilo 10 1900 (has links)
International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / A simple, low cost radio frequency (RF) power and spectrally efficient integrated transceiver/modem architecture employing Feher’s patented Quadrature Phase Shift Keying (FQPSK) is described. The FQPSK signals presented in this paper are obtained by using additional post low-pass filters in the FQPSK architecture. This implementation significantly improves the spectral efficiency of the worldwide commercially standardized Gaussian Minimum Shift Keying (GMSK) systems. The Bit Error Rate (BER) performance of FQPSK in additive white Gaussian noise (AWGN) channel has been investigated by means of computer simulation and hardware prototype measurements. The results of the hardware and software simulations are compared to GMSK and QPSK/OQPSK performance. These results show that the filtered FQPSK modulated signal passing through a non-linear amplifier (NLA) can achieve a spectral efficiency improvement of about 60% over NLA filtered OQPSK and an integrated spectral efficiency improvement of 50% over GMSK and a better BER performance. In particular, 100 kb/s to 34 Mb/s hardware experimental results over 2.4 GHz NLA (saturated) 1 Watt system confirmed that FQPSK hardware systems attain a BER=f(Eb/N0) performance within 1 dB to 2 dB of predicted theoretical results.

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