To see the other types of publications on this topic, follow the link: Channel capacity.
Dissertations / Theses on the topic 'Channel capacity'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Channel capacity.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
VIEIRA, ROBSON DOMINGOS. "MIMO MEASURED CHANNELS: CAPACITY RESULTS AND ANALYSIS OF CHANNEL PARAMETERS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7954@1.
Full textAbstract:
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOSistemas com múltiplas antenas transmissoras e receptoras, também conhecidos como sistemas MIMO (Multiple Input-Multiple Output), têm sido apontados como uma solução para aumentar a capacidade de enlaces sem fio, permitindo aos usuários utilizar aplicações com altas taxas de dados. Isto é extremamente importante em sistemas onde a capacidade obtida com as técnicas tradicionais é bastante limitada devido às características do ambiente de propagação. Com o sistema MIMO, algumas destas características são exploradas para criar canais paralelos e obter aumento expressivo de capacidade. A análise da capacidade de sistemas MIMO se baseia em uma modelagem desenvolvida a partir do comportamento estatístico dos pares de enlaces existentes entre as múltiplas antenas transmissoras e receptoras. Existe, portanto, um grande interesse em medir este comportamento para situações típicas bem como em relacioná-lo a determinados parâmetros do sistema. Nesta tese apresentam-se os resultados de uma campanha de medidas visando caracterizar canais MIMO de faixa estreita e faixa larga em ambientes fechados (indoor) com uma freqüência de portadora de 2GHz. A partir dos dados medidos, avalia-se a capacidade e diversos parâmetros do canal espaço-temporal. Os parâmetros do canal MIMO são estimados através do algoritmo FD-SAGE e as dispersões temporal e espacial do canal são calculadas a partir dos parâmetros estimados. Uma análise dos autovalores da matriz do canal MIMO é realizada com o objetivo de relacionar os valores da capacidade ao número de canais paralelos. É analisada, ainda, a correlação entre a capacidade e os parâmetros físicos do canal, tais como espaçamento entre os elementos do arranjo, espalhamento angular, espalhamento dos retardos, número e potência dos multipercursos.
Multiple antenna systems known as MIMO (Multiple Input Multiple Output) systems have been proposed as an effective way to address the user demand for high data rate applications in wireless systems. This is especially important in systems where the capacity attained with traditional techniques is very limited due to the adverse characteristics of the propagation environment. With MIMO, some of these characteristics are used to create parallel channels producing significant increase in capacity. The analysis of MIMO capacity is based on models developed from the statistical behavior of the multiple links between the transmitting and receiving antennas, and therefore there has been large interest in measuring these characteristics in typical scenarios and in relating the data to system parameters. In this thesis the results of a MIMO wideband measurement campaign carried out in an indoor scenario with a carrier frequency of 2 GHz is presented. The wideband and narrowband channel capacity and several channel parameters are evaluated from the measured data. The channel parameters are estimated using the frequency domain Space-Alternating Generalized Expectation maximization (FD- SAGE) algorithm. Temporal and spatial dispersions of the multipath channel are calculated from the estimated parameters and an eigenvalue analysis is performed seeking to relate the capacity values to the number of parallel channels. In addition, the correlation between channel capacity and physical parameters as antenna spacing, angle spread, delay spread, number and power of multipath components is investigated.
2
Abdelaziz, Amr Mohamed. "Information Theoretical Studies on MIMO Channel with Limited Channel State Information." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500592938716914.
Full text
3
Reátegui, del Águila Fernando. "On the capacity of cognitive interference channel structures." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/807077/.
Full textAbstract:
The cognitive interference channel extends the classical two-user interference channel to have unidirectional cooperation at the transmitters. In this model, the cognitive transmitter is assumed to have noncausal knowledge of the other transmitter's current message (primary message). This a priori knowledge is used by the cognitive user to accomplish its two main purposes, i.e., to relay the primary message in order to boost the primary user's data rate and to maximise its own data rate by cancelling the interference at its receiver. The cognitive interference channel is well studied in the literature and capacity results are available for the weak and very strong interference regimes, amongst others. A general solution is still elusive. In this thesis we study the capacity region of cognitive structures that are based in their core on the cognitive interference channel but with the aggregate that an additional node is considered, e.g., an additional receiver node, an additional transmitter node or a relay node. The cognitive broadcast interference channel consists of the cognitive interference channel with an additional receiver. The cognitive side serves either one or two receivers and the interference goes from the cognitive transmitter to the primary receiver only. In this model we provide a general achievable rate region when the cognitive side serves two receivers. We analyse the discrete memoryless channel and show that the region simplifies to existing results in the literature when certain assumptions are made. An achievable rate region for the Gaussian channel is also provided for the case where the cognitive side sends common information to both receivers. When the cognitive side serves only one receiver, we provide an achievable rate region and an outer bound and show the gap graphically. The cognitive interference channel with a relay consists of the cognitive interference channel with an additional relay node. In this model we show that as in the interference channel with a relay, interference forwarding is also beneficial. We describe analytically achievable rate regions and show the benefits of interference forwarding. We also provide an achievable rate region with generalised interference forwarding, i.e., the relay forwards the intended message and the interference simultaneously, and show that allowing the relay to allocate part of its power to forward interference is beneficial when we are in the strong but not in the very strong interference regime. The cognitive interference channel with causal unidirectional destination cooperation is formed by transferring the relaying capabilities of the relay node in the previous model to the cognitive receiver and its operation is causal rather than strictly causal. In this model we show that instantaneous amplify and forward is good enough to achieve the capacity region of the Gaussian channel. We derive analytically an inner and outer bounds and show that they coincide for certain values of the antenna gain at the relay in the very strong interference regime. We also analyse the cognitive interference channel with a relay for the case where the relay operates causally. The capacity region is obtained for a special case of very strong interference. The cognitive multiple access interference channel consists of the cognitive interference channel with an additional cognitive transmitter. In this model the interference goes from the primary user to the cognitive receiver only. The cognitive users form a MAC channel. We show for this scenario that dirty paper coding achieves the capacity region in the Gaussian case. In the analysis we make use of encoding techniques first utilised for the MAC with state available noncausally at the encoder.
4
Clower, Terry L. "Increasing Telecommunications Channel Capacity: Impacts on Firm Profitability." Thesis, University of North Texas, 1997. https://digital.library.unt.edu/ark:/67531/metadc279298/.
Full textAbstract:
In calling for the deployment of high-capacity telecommunications infrastructures, the Clinton Administration is relying on market forces to drive demand toward self-sustaining development. There is little doubt that many firms will embrace the new telecommunications services for a variety of reasons including market differentiation, vertical market integration, and other organization-specific factors. However, there is little evidence at the firm level that adopting the use of increased-capacity telecommunications technologies is associated with improvements in firm profitability. This study seeks to identify the presence of impacts on firm income that can be associated with the adoption of T1 telecommunications services.
5
Potter, Christopher G., Adam G. Panagos, Kurt Kosbar, and William Weeks. "OPTIMAL TRAINING PARAMETERS FOR CONTINUOUSLY VARYING MIMO CHANNELS." International Foundation for Telemetering, 2005. http://hdl.handle.net/10150/605025.
Full textAbstract:
ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, NevadaTo correctly demodulate a signal sent through a multiple-input multiple-output (MIMO) channel, a receiver may use training to learn the channel parameters. The choice of training parameters can significantly impact system performance. Training too often yields low throughput while training infrequently produces poor channel estimates and increased transmission errors. Previous work on optimal training parameters has focused on the block fading Rayleigh model. This work examines a more general case; finding the training parameters that maximize throughput for a continuously varying channel. Training parameters that maximize a lower bound on channel capacity are determined via simulation, and general guidelines are presented for selecting optimal training parameters.
6
Guha, Saikat 1980. "Classical capacity of the free-space quantum-optical channel." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/87908.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.MIT Institute Archives copy has MIT Research Laboratory of Electronics t.p.
Also issued with MIT Research Laboratory of Electronics t.p. preceding thesis t.p.
Includes bibliographical references (leaves 114-116).
Exploring the limits to reliable communication rates over quantum channels has been the primary focus of many researchers over the past few decades. In the present work, the classical information carrying capacity of the free-space quantum optical channel has been studied thoroughly in both the far-field and near-field propagation regimes. Results have been obtained for the optimal capacity, in which information rate is maximized over both transmitter encodings and detection schemes at the receiver, for the entanglement-assisted capacity, and also for sub-optimal systems that employ specific transmitter and receiver structures. For the above cases, several new broadband results have been obtained for capacity in the presence of both diffraction limited loss and additive fluctuations emanating from a background blackbody radiation source at thermal equilibrium.
by Saikat Guha.
S.M.
7
Bonello, Nicholas. "Near-capacity fixed-rate and rateless channel code constructions." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/68774/.
Full textAbstract:
Fixed-rate and rateless channel code constructions are designed for satisfying conflicting design tradeoffs, leading to codes that benefit from practical implementations, whilst offering a good bit error ratio (BER) and block error ratio (BLER) performance. More explicitly, two novel low-density parity-check code (LDPC) constructions are proposed; the first construction constitutes a family of quasi-cyclic protograph LDPC codes, which has a Vandermonde-like parity-check matrix (PCM). The second construction constitutes a specific class of protograph LDPC codes, which are termed as multilevel structured (MLS) LDPC codes. These codes possess a PCM construction that allows the coexistence of both pseudo-randomness as well as a structure requiring a reduced memory. More importantly, it is also demonstrated that these benefits accrue without any compromise in the attainable BER/BLER performance. We also present the novel concept of separating multiple users by means of user-specific channel codes, which is referred to as channel code division multiple access (CCDMA), and provide an example based on MLS LDPC codes. In particular, we circumvent the difficulty of having potentially high memory requirements, while ensuring that each user’s bits in the CCDMA system are equally protected. With regards to rateless channel coding, we propose a novel family of codes, which we refer to as reconfigurable rateless codes, that are capable of not only varying their code-rate but also to adaptively modify their encoding/decoding strategy according to the near-instantaneous channel conditions. We demonstrate that the proposed reconfigurable rateless codes are capable of shaping their own degree distribution according to the nearinstantaneous requirements imposed by the channel, but without any explicit channel knowledge at the transmitter. Additionally, a generalised transmit preprocessing aided closed-loop downlink multiple-input multiple-output (MIMO) system is presented, in which both the channel coding components as well as the linear transmit precoder exploit the knowledge of the channel state information (CSI). More explicitly, we embed a rateless code in a MIMO transmit preprocessing scheme, in order to attain near-capacity performance across a wide range of channel signal-to-ratios (SNRs), rather than only at a specific SNR. The performance of our scheme is further enhanced with the aid of a technique, referred to as pilot symbol assisted rateless (PSAR) coding, whereby a predetermined fraction of pilot bits is appropriately interspersed with the original information bits at the channel coding stage, instead of multiplexing pilots at the modulation stage, as in classic pilot symbol assisted modulation (PSAM). We subsequently demonstrate that the PSAR code-aided transmit preprocessing scheme succeeds in gleaning more information from the inserted pilots than the classic PSAM technique, because the pilot bits are not only useful for sounding the channel at the receiver but also beneficial for significantly reducing the computational complexity of the rateless channel decoder.
8
Panagos, Adam G., and Kurt Kosbar. "A GRAPHICAL USER INTERFACE MIMO CHANNEL SIMULATOR." International Foundation for Telemetering, 2004. http://hdl.handle.net/10150/605799.
Full textAbstract:
International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, CaliforniaMultiple-input multiple-output (MIMO) communication systems are attracting attention because their channel capacity can exceed single-input single-output systems, with no increase in bandwidth. While MIMO systems offer substantial capacity improvements, it can be challenging to characterize and verify their channel models. This paper describes a software MIMO channel simulator with a graphical user interface that allows the user to easily investigate a number of MIMO channel characteristics for a channel recently proposed by the 3rd Generation Partnership Project (3GPP).
9
Tau, Sieskul Bamrung [Verfasser]. "NLoS Localization and UWB Channel Capacity Analysis / Bamrung Tau Sieskul." Aachen : Shaker, 2010. http://d-nb.info/1080766995/34.
Full text
10
Shukla, Rahul. "Effects of UE Speed on MIMO Channel Capacity in LTE." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc862877/.
Full textAbstract:
With the introduction of 4G LTE, multiple new technologies were introduced. MIMO is one of the important technologies introduced with fourth generation. The main MIMO modes used in LTE are open loop and closed loop spatial multiplexing modes. This thesis develops an algorithm to calculate the threshold values of UE speed and SNR that is required to implement a switching algorithm which can switch between different MIMO modes for a UE based on the speed and channel conditions (CSI). Specifically, this thesis provides the values of UE speed and SNR at which we can get better results by switching between open loop and closed loop MIMO modes and then be scheduled in sub-channels accordingly. Thus, the results can be used effectively to get better channel capacity with less ISI. The main objectives of this thesis are: to determine the type of MIMO mode suitable for a UE with certain speed, to determine the effects of SNR on selection of MIMO modes, and to design and implement a scheduling algorithm to enhance channel capacity.
11
Kariuki, Paul Njoroge 1976. "The capacity of a non-coherent channel : multi user setting." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87238.
Full textAbstract:
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (leaves 34-35).
by Paul Njoroge Kariuki.
M.Eng.
12
Hossan, Mohammad Kamal. "On the Secrecy Capacity of Fading Gaussian Wire-Tap Channel." Thesis, North Dakota State University, 2014. https://hdl.handle.net/10365/27565.
Full textAbstract:
We consider the so called ?wire-tap channel?, where a transmitter sends secret information to its receiver in the presence of an eavesdropping receiver with similar signal processing capability as the desired receiver. It is assumed that all the communication links have time varying signal strengths which are only known at the corresponding receivers and not at the transmitter. In this thesis, we address the problem of characterizing the maximum possible rate of secret and reliable information transmission on such a wire-tap channel. We first characterize the secrecy capacity of a corresponding layered abstraction of the channel, and then, we derive an upper bound to the secrecy capacity of the fading wire-tap channel. Finally, we show that the wireless channels in the urban and most of the rural environments belong to a class of channels called Stochastically degraded channels, for which we have characterized the exact capacity in this thesis work.
13
Klitorakis, Petros. "On the capacity of a cellular CDMA system reverse channel." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://sirsi.nps.navy.mil/uhtbin/hyperion-image/02Mar%5FKlitorakis.pdf.
Full text
14
Yong, Xuerong. "The channel capacity of one and two-dimensional constrained codes /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?COMP%202002%20YONG.
Full textAbstract:
Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 105-110). Also available in electronic version. Access restricted to campus users.
15
Pottkotter, Andrew A. "Maximizing Channel Capacity based on Antenna and MIMO Channel Characteristics and its Application to Multimedia Data Transmission." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1430317210.
Full text
16
King, Timothy William. "Optimization of the Fading MIMO Broadcast Channel: Capacity and Fairness Perspectives." Thesis, University of Canterbury. Electrical and Computer Engineering, 2009. http://hdl.handle.net/10092/3201.
Full textAbstract:
Multiple input multiple output (MIMO) systems are now a proven area in
current and future telecommunications research. MIMO wireless channels, in
which both the transmitter and receiver have multiple antennas, have been
shown to provide high bandwidth efficiency. In this thesis, we cover MIMO
communications technology with a focus on cellular systems and the MIMO
broadcast channel (MIMO-BC).
Our development of techniques and analysis for the MIMO-BC starts with
a study of single user MIMO systems. One such single user technique is that of
antenna selection. In this thesis, we discuss various flavours of antenna selection, with the focus on powerful, yet straightforward, norm-based algorithms.
These algorithms are analyzed and the results of this analysis produce a powerful and flexible power scaling factor. This power scaling factor can be used
to model the gains of norm-based antenna selection via a single signal-to-noise
ratio (SNR)-based parameter. This provides a powerful tool for engineers interested in quickly seeing the effects of antenna selection on their systems. A
novel low complexity power allocation scheme follows on from the selection
algorithms. Named “Poor Man’s Waterfilling” (PMWF), this scheme can provide significant gains in low SNR systems with very little extra complexity
compared to selection alone.
We then compare a variety of algorithms for the MIMO-BC, ranging from
selection to beamforming, to the optimal, yet complex, iterative waterfilling
(ITWF) solution. In this thesis we show that certain algorithms perform better
in different scenarios, based on whether there is shadow fading or not. A power
scaling factor analysis is also performed on these systems. In the cases where
the user’s link gains are widely varying, such as when shadowing and distance
effects are present, user fairness is impaired when optimal and near optimal
throughput occurs.
This leads to a key problem in the MIMO-BC, the balance between user
fairness and throughput performance. In an attempt to find a suitable balance
between these two factors, we modify the ITWF algorithm by both introducing extra constraints and also by using a novel utility function approach. Both
these methods prove to increase user fairness with only minor loss in throughput over the optimal systems.
The introduction of MIMO systems to the cellular domain has been hampered by the effects of interference between the cells. In this thesis we move
MIMO to the cellular domain, addressing the interference using two different
methods. We first use power control, where the transmit power of the base
station is controlled to optimize the overall system throughput. This leads
to promising results using low complexity methods. Our second method is a
novel method of collaboration between base stations. This collaboration transforms neighbouring cell sectors into macro-cells and this results in substantial
increases in performance.
17
Potter, Chris. "Single Bounce Air to Ground Communication Channel Capacity for MIMO Applications." International Foundation for Telemetering, 2006. http://hdl.handle.net/10150/604770.
Full textAbstract:
ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, CaliforniaThis paper addresses the air-to-ground communication problem, where multiple transmit antennas are used on the aircraft to combat multi-path interference. The channel is assumed to have a line-of-sight component and a single ground reflection. Multiple input multiple output (MIMO) techniques can be used in this situation, to increase the reliability and data rate. In this paper we discuss how the MIMO channel capacity changes, with the aircraft antenna configuration, altitude, velocity, range, and a number of other parameters. For comparison, the MIMO results are compared to systems which have single antennas at the transmitter, at the receiver, or at both ends.
18
Mowinckel, Erland Kragh. "Flood Capacity Improvement of San Jose Creek Channel Using HEC-RAS." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/583.
Full textAbstract:
The Santa Ynez Mountains of Santa Barbara County, California, have seen many major storm events during the past century. San Jose Creek, which runs out of these mountains, through the town of Goleta, and into the Pacific Ocean, has experienced several intense flood events as a result. The lower portion of the creek was diverted in 1960 to alleviate flooding through Old Town Goleta. However, flooding still occurred in the storms of 1995 and 1998. This study incorporates a hydraulic analysis component of a project aimed at re-designing this diverted portion of the channel. It presents an analysis of modifications to this reach in order to improve its capacity and reduce flooding during a 100-year event. As one of the most prominent software for hydraulic modeling for steady and unsteady state open channel flow, HEC-RAS is used to analyze multiple variations in channel geometry and combinations of lining materials. Of these modifications, the best configuration is suggested.
19
Fiacco, Mauro. "Intelligent picocells for adaptive indoor coverage and capacity." Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/844492/.
Full textAbstract:
This dissertation presents and develops the Intelligent Picocell as a solution for high bit rate, efficient bandwidth indoor wireless communication. The research has examined different aspects of the indoor radio propagation environment and system implementation in order to highlight key benefits of the proposed architecture. Explosive growth in demand for indoor wireless communications motivates research into this novel radio architecture. The architecture should be capable of tailoring capacity and coverage to the needs of the specific indoor environment, while maximising spectral efficiency. The Intelligent Picocell is based on an evolution of the distributed antenna concept to provide macrodiversity, microdiversity and interference cancellation. The architecture is fully scalable to large numbers of users and can provide plug-and-play operation, with no need for detailed system planning beyond the antenna locations. The research examines different aspects of picocell system performance and design, including: Investigation on the indoor radio environment. Through measurements, the effects of building features on path loss and shadowing are analysed and propagation models are proposed for simulating picocell systems. Analysis of the Intelligent Picocell architecture, two algorithms are proposed for interference reduction, one based on a distributed narrowband optimum combiner and the other on a dynamic channel assignment and allocation scheme. Through simulation, it was demonstrated that the mobile transmitted power for an Intelligent Picocell is lower than the power required in a distributed antennas system. It was also shown that the capacity of the system depends on the number of antennas distributed in the building. Key words: Intelligent picocell, adaptive antennas, diversity, distributed antennas, dynamic channel allocation, propagation measurements.
20
Taparugssanagorn, A. (Attaphongse). "Evaluation of MIMO radio channel characteristics from TDM-switched MIMO channel sounding." Doctoral thesis, University of Oulu, 2007. http://urn.fi/urn:isbn:9789514286506.
Full textAbstract:
Abstract
The present dissertation deals with the evaluation of multiple-input multiple-output (MIMO) radio channel characteristics from time-division multiplexing (TDM)-switched MIMO channel sounding. The research can be divided into three main areas. First, the impacts of phase noise in TDM-switched MIMO channel sounding on channel capacity are studied. Second, we focus on those impacts on channel parameter estimation using the SAGE algorithm. And in the last part, spatial correlation, channel eigenvalue distribution, and ergodic capacity in realistic environments are analyzed.
The rationale behind the first two areas is that most advanced MIMO radio channel sounders employ the TDM technique, which has significant problems from phase noise of the TX and RX phase locked loop (PLL) oscillators causing measurement errors in terms of estimated channel capacity and parameters. We propose statistical models that reproduce the capacity estimates. The effects of the sounding mode (SM), the length of pseudo-random noise (PN) sequence L of the sounding signal, and the system size are disclosed. The distinctive basis is to consider the impact of the actual phase noise in TDM switched MIMO channel sounding, instead of assuming white Gaussian-type phase noise. In a reality, the short-term phase noise component affecting one measurement cycle of a MIMO system plays an important role in the traditional estimators of the radio channel parameters and capacity. We show that the performance impairment is less than that been under the hypothesis of uncorrelated white Gaussian phase-noises samples. The difference is due to the non-vanishing correlation of phase-noise within the measurement cycle. Two approaches to mitigating the impact of phase noise are proposed. The former is the simple and efficient sliding averaging method, where the signal-to-noise ratio (SNR) of the channel impulse response can be increased. The latter is the choice of SM and L, which is more thorough. In the second part, two approaches to mitigating its impact on channel parameter estimation using the SAGE algorithm are also discussed. Besides the sliding averaging, which in general can increase the SNR, the new SAGE algorithm based channel parameter estimation based on the improved signal model accounting for the phase noise in the measurement device is proposed. Finally, the channel eigenvalue distribution and ergodic capacity based on complex hypergeometric functions and their asymptotic characteristics are analyzed. It is shown that the derived theoretical expressions closely approximate the simulated results of the measured finite-dimensional MIMO channels. The spatial correlation and the eigenvalue statistics in frequency selective channels for single and dual polarized antennas are investigated. This knowledge is useful when different MIMO and beamforming techniques are applied.
21
Teotia, Seemant. "Influence of the Number of Degrees of Freedom on the Capacity of Incoherent Optical Fiber Communication Systems." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27497.
Full textAbstract:
The purpose of this dissertation is to find the channel capacity in optical fiber communication systems when incoherent detection is used with single (polarization filtering) and two-polarizations (no polarization filtering).
Optical fiber systems employ photodetectors that convert optical intensity to electrical current. Bandpass vector fields may be represented by four orthogonal baseband components corresponding to two quadrature phases and two orthogonal polarizations. Intensity is proportional to the sum of the squares of these four components. In the case of a coherent receiver, a strong optical local oscillator (in phase and with same polarization as the signal) is added to the signal prior to the photodetector. This results in the removal of the quadrature phase and polarization components, and reduces to the one degree of freedom (DOF) case of signal plus local oscillator shot noise for which the Shannon channel capacity formula applies. Electrical noise following the photodetector may also be neglected if there is an optical amplifier before the photodetector in the receiver. The amplifier introduces amplified spontaneous emission noise containing both quadrature phase components and both polarizations (4 DOFs), but the 2 DOF case would result if a polarization filter were used. Although the 1 and 2 DOF cases are of less practical interest than the 4 DOF case, they provide useful benchmarks for comparing performance limits.
We evaluate both spectral efficiency limits (bps/Hz) in the limit of high and low SNR for the 1,2 and 4 DOF cases and also find the power efficiency (minimum number of photons per bit) for each of these cases. It is shown that for high SNR the spectral efficiency is the same independent of the number of DOFs and that the half-Gaussian distribution is the optimum distribution. We are able to thus obtain a compact equation for spectral efficiency which behaves in a similar way to the Shannon capacity formula but with the SNR scaled by a constant.
We also show that for low SNR the half-Gaussian distribution is not the optimum distribution as the slope of the mutual information changes with the square of SNR which would lead to the number of photons per bit becoming infinite in the limit of SNR going to zero. We use a modified half-Gaussian distribution which has a discrete component (an impulse function at the origin) and provide a simple proof that this distribution results in a mutual information that goes to zero linearly with SNR resulting in a minimum number of photons per bit. Furthermore, by increasing the magnitude of the discrete component at the origin, it is shown that the minimum number of photons per bit for the incoherent channel approaches that of the coherent channel.Ph. D.
22
Jiang, Jing. "Capacity-approaching data transmission in MIMO broadcast channels." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/11208.
Full textAbstract:
This dissertation focuses on downlink multi-antenna transmission with packet scheduling in a wireless packet data network. The topic is viewed as a critical system design problem for future high-speed packet networks requiring extremely high spectral efficiency. Our aim is to illustrate the interaction between transmission schemes at the physical layer and scheduling algorithms at the medium access control (MAC) layer from a sum-capacity perspective. Various roles of multiple antennas are studied under channel-aware scheduling, including diversity, beamforming and spatial multiplexing. At a system performance level, our work shows that downlink throughput can be optimized by joint precoding across multiple transmit antennas and exploiting small-scale fading of distributed multiple input and multiple output (MIMO) channels.
There are three major results in this dissertation. First, it is shown that over a MIMO Gaussian broadcast channel, and under channel-aware scheduling, open-loop transmit antenna diversity actually reduces the achievable sum rate. This reveals a negative interaction between open-loop antenna diversity and the closed-loop multiuser diversity through scheduling. Second, a suboptimal dirty paper coding (DPC) approach benefits greatly from multiuser diversity by an efficient packet scheduling algorithm. Performance analysis of a suboptimal greedy scheduling algorithm indicates that, compared with the receiver-centric V-BLAST method, it can achieve a much larger scheduling gain over a distributed MIMO channel. Further, pre-interference cancellation allows for transmissions free of error propagation. A practical solution, termed Tomlinson-Harashima precoding (THP), is studied under this suboptimal scheduling algorithm. Similar to V-BLAST, a reordering is applied to minimize the average error rate, which introduces only a negligible sum-rate loss in the scenarios investigated. Third, for an orthogonal frequency division multiplexing (OFDM) system using MIMO precoding, it is shown that a DPC-based approach is readily applicable and can be easily generalized to reduce the peak-to-average power ratio (PAR) up to 5 dB without affecting the receiver design. Simulations show that in an interference-limited multi-cell scenario, greater performance improvement can be achieved by interference avoidance through adaptive packet scheduling, rather than by interference diversity or averaging alone. These findings suggest that, coordinated with channel-aware scheduling, adaptive multiplexing in both spatial and frequency domains provides an attractive downlink solution from a total capacity point of view.Ph. D.
23
MEDEIROS, Rex Antonio da Costa. "Zero-Error capacity of quantum channels." Universidade Federal de Campina Grande, 2008. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1320.
Full textAbstract:
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-08-01T21:11:37Z
No. of bitstreams: 1
REX ANTONIO DA COSTA MEDEIROS - TESE PPGEE 2008..pdf: 1089371 bytes, checksum: ea0c95501b938e0d466779a06faaa4f6 (MD5)Made available in DSpace on 2018-08-01T21:11:37Z (GMT). No. of bitstreams: 1 REX ANTONIO DA COSTA MEDEIROS - TESE PPGEE 2008..pdf: 1089371 bytes, checksum: ea0c95501b938e0d466779a06faaa4f6 (MD5) Previous issue date: 2008-05-09
Nesta tese, a capacidade erro-zero de canais discretos sem memória é generalizada para canais quânticos. Uma nova capacidade para a transmissão de informação clássica através de canais quânticos é proposta. A capacidade erro-zero de canais quânticos (CEZQ) é definida como sendo a máxima quantidade de informação por uso do canal que pode ser enviada através de um canal quântico ruidoso, considerando uma probabilidade de erro igual a zero. O protocolo de comunicação restringe palavras-código a produtos tensoriais de estados quânticos de entrada, enquanto que medições coletivas entre várias saídas do canal são permitidas. Portanto, o protocolo empregado é similar ao protocolo de Holevo-Schumacher-Westmoreland. O problema de encontrar a CEZQ é reformulado usando elementos da teoria de grafos. Esta definição equivalente é usada para demonstrar propriedades de famílias de estados quânticos e medições que atingem a CEZQ. É mostrado que a capacidade de um canal quântico num espaço de Hilbert de dimensão d pode sempre ser alcançada usando famílias compostas de, no máximo,d estados puros. Com relação às medições, demonstra-se que medições coletivas de von Neumann são necessárias e suficientes para alcançar a capacidade. É discutido se a CEZQ é uma generalização não trivial da capacidade erro-zero clássica. O termo não trivial refere-se a existência de canais quânticos para os quais a CEZQ só pode ser alcançada através de famílias de estados quânticos não-ortogonais e usando códigos de comprimento maior ou igual a dois. É investigada a CEZQ de alguns canais quânticos. É mostrado que o problema de calcular a CEZQ de canais clássicos-quânticos é puramente clássico. Em particular, é exibido um canal quântico para o qual conjectura-se que a CEZQ só pode ser alcançada usando uma família de estados quânticos não-ortogonais. Se a conjectura é verdadeira, é possível calcular o valor exato da capacidade e construir um código de bloco quântico que alcança a capacidade. Finalmente, é demonstrado que a CEZQ é limitada superiormente pela capacidade de Holevo-Schumacher-Westmoreland.
24
Strelchuk, Sergii. "Superactivation of the channel capacity and teleportation protocols in quantum information theory." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648259.
Full text
25
He, Rong. "AMPS co-channel interference rejection techniques and their impact on system capacity." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-10022008-063026/.
Full text
26
Alonso, Javier. "M.I.M.O Channel Model for High Capacity Wireless Networks and Simulator for Performance Analysis." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7784.
Full textAbstract:
The wireless communications have suffered, in these last years, one of the greater technological growth within the communications via radio. The application of multiple antennas, as much in transmission as in reception has taken to an impulse of the study of different models from propagation channels.
Taking this into consideration, the different types from mentioned models are going to be studied.
The work that the ISY department at the Institute of Technology of the Linköping University has proposed is to develop to a propagation channel model, with several antennas in reception and transmission, that one first approach allows a capacity of the channel study, in absence of measures of possible scenarios, as well as the development of a small simulator that allows to analyze its benefits.
27
Guvensen, Gokhan Muzaffer. "Near Capacity Operating Practical Transceivers For Wireless Fading Channels." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610398/index.pdf.
Full textAbstract:
Multiple-input multiple-output (MIMO) systems have received much attention due to their
multiplexing and diversity capabilities. It is possible to obtain remarkable improvement
in spectral efficiency for wireless systems by using MIMO based schemes. However, sophisticated
equalization and decoding structures are required for reliable communication at
high rates. In this thesis, capacity achieving practical transceiver structures are proposed for
MIMO wireless channels depending on the availability of channel state information at the
transmitter (CSIT).
First, an adaptive MIMO scheme based on the use of quantized CSIT and reduced precoding
idea is proposed. With the help of a very tight analytical upper bound obtained for limited
rate feedback (LRF) MIMO capacity, it is possible to construct an adaptive scheme varying
the number of beamformers used according to the average SNR value. It is shown that
this strategy always results in a significantly higher achievable rate than that of the schemes
which does not use CSIT, if the number of transmit antennas is greater than that of receive
antennas.
Secondly, it is known that the use of CSIT does not bring significant improvement over
capacity, when similar number of transmit and receive antennas are usedon the other hand, it reduces the complexity of demodulation at the receiver by converting the channel into noninterfering subchannels. However, it is shown in this thesis that it is still possible to achieve a performance very close to the outage probability and exploit the space-frequency diversity benefits of the wireless fading channel without compromising the receiver complexity, even if the CSIT is not used. The proposed receiver structure is based on iterative forward and backward filtering to suppress the interference both in time and space followed by a spacetime decoder. The rotation of multidimensional constellations for block fading channels and the single-carrier frequency domain equalization (SC-FDE) technique for wideband MIMO channels are studied as example applications.
28
Khatami, Seyed Mehrdad. "Read Channel Modeling, Detection, Capacity Estimation and Two-Dimensional Modulation Codes for TDMR." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/577306.
Full textAbstract:
Magnetic recording systems have reached a point where the grain size can no longer be reduced due to energy stability constraints. As a new magnetic recording paradigm, two-dimensional magnetic recording (TDMR) relies on sophisticated signal processing and coding algorithms, a much less expensive alternative to radically altering the media or the read/write head as required for the other technologies. Due to 1) the significant reduction of grains per bit, and 2) the aggressive shingled writing, TDMR faces several formidable challenges. Firstly, severe interference is introduced in both down-track and cross-track directions due to the read/write head dimensions. Secondly, reduction in the number of grains per bit results in variations of bit boundaries which consequently lead to data-dependent jitter noise. Moreover, the bit to grain ratio reduction will cause some bits not to be properly magnetized or to be overwritten which introduces write errors to the system. The nature of write and read processes in TDMR necessitates that the information storage be viewed as a two-dimensional (2D) system. The challenges in TDMR signal processing are 1) an accurate read channel model, 2) mitigating the effect of inter-track interference (ITI) and inter-symbol interference (ISI) by using an equalizer, 3) developing 2D modulation/error correcting codes matching the TDMR channel model, 4) design of truly 2D detectors, and 5) computing the lower bounds on capacity of TDMR channel. The work is concerned with several objectives in regard to the challenges in TDMR systems. 1. TDMR Channel Modeling: As one of the challenges of the project, the 2D Microcell model is introduced as a read channel model for TDMR. This model captures the data-dependent properties of the media noise and it is well suited in regard to detector design. In line with what has been already done in TDMR channel models, improvements can be made to tune the 2D Microcell model for different bit to grain densities. Furthermore, the 2D Microcell model can be modified to take into account dependency between adjacent microtrack borders positions. This assumption will lead to more accurate model in term of closeness to the Voronoi model. 2. Detector Design: The need for 2D detection is not unique to TDMR systems. However, it is still largely an open problem to develop detectors that are close to optimal maximum likelihood (ML) detection for the 2D case. As one of the important blocks of the TDMR system, the generalized belief propagation (GBP) detector is developed and introduced as a near ML detector. Furthermore, this detector is tuned to improve the performance for the TDMR channel model. 3. Channel Capacity Estimation: Two dimensional magnetic recording (TDMR) is a new paradigm in data storage which envisions densities up to 10 Tb/in² as a result of drastically reducing bit to grain ratio. In order to reach this goal aggressive write (shingled writing) and read process are used in TDMR. Kavcic et al. proposed a simple magnetic grain model called the granular tiling model which captures the essence of read/write process in TDMR. Capacity bounds for this model indicate that 0.6 user bit per grain densities are possible, however, previous attempt to reach capacities are not close to the channel capacity. We provide a truly two-dimensional detection scheme for the granular tiling model based on generalized belief propagation (GBP). Factor graph interpretation of the detection problem is provided and formulated in this section. Then, GBP is employed to compute marginal a posteriori probabilities for the constructed factor graph. Simulation results show huge improvements in detection. A lower bound on the mutual information rate (MIR) is also derived for this model based on GBP detector. Moreover, for the Voronoi channel model, the MIR is estimated for the case of constrained and unconstrained input. 4. Modulation Codes: Constrained codes also known as modulation codes are a key component in the digital magnetic recording systems. The constrained code forbids particular input data patterns which lead to some of the dominant error events or higher media noise. The goal of the dissertation in regard to modulation codes is to construct a 2D modulation code for the TDMR channel which improves the overall performance of the TDMR system. Furthermore, we implement an algorithm to estimate the capacity of the 2D modulation codes based on generalized belief propagation (GBP) algorithm. The capacity is also calculated in presence of white and colored noise which is the case for TDMR channel. 5. Joint Detection and Decoding Schemes: In data recording systems, a concatenated approach toward the constrained code and error-correcting code (ECC) is typically used and the decoding is done independently. We show the improvement in combining the decoding of the constrained code and the ECC using GBP algorithm. We consider the performance of a combined modulation constraints and the ECC on a binary-input additive white Gaussian noise (AWGN) channel (BIAWGNC) and also over one-dimensional (1D) and 2D ISI channels. We will show that combining the detection, demodulation and decoding results in a superior performance compared to concatenated schemes.
29
Das, Gupta Jishu. "Effect of pedestrian movement on MIMO-OFDM channel capacity in an indoor environment." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/38632/1/Jishu_Das_Gupta_Thesis.pdf.
Full textAbstract:
The rapid growth of mobile telephone use, satellite services, and now the wireless Internet and WLANs are generating tremendous changes in telecommunication and networking. As indoor wireless communications become more prevalent, modeling indoor radio wave propagation in populated environments is a topic of significant interest. Wireless MIMO communication exploits phenomena such as multipath propagation to increase data throughput and range, or reduce bit error rates, rather than attempting to eliminate effects of multipath propagation as traditional SISO communication systems seek to do. The MIMO approach can yield significant gains for both link and network capacities, with no additional transmitting power or bandwidth consumption when compared to conventional single-array diversity methods. When MIMO and OFDM systems are combined and deployed in a suitable rich scattering environment such as indoors, a significant capacity gain can be observed due to the assurance of multipath propagation. Channel variations can occur as a result of movement of personnel, industrial machinery, vehicles and other equipment moving within the indoor environment. The time-varying effects on the propagation channel in populated indoor environments depend on the different pedestrian traffic conditions and the particular type of environment considered. A systematic measurement campaign to study pedestrian movement effects in indoor MIMO-OFDM channels has not yet been fully undertaken. Measuring channel variations caused by the relative positioning of pedestrians is essential in the study of indoor MIMO-OFDM broadband wireless networks. Theoretically, due to high multipath scattering, an increase in MIMO-OFDM channel capacity is expected when pedestrians are present. However, measurements indicate that some reductions in channel capacity could be observed as the number of pedestrians approaches 10 due to a reduction in multipath conditions as more human bodies absorb the wireless signals. This dissertation presents a systematic characterization of the effects of pedestrians in indoor MIMO-OFDM channels. Measurement results, using the MIMO-OFDM channel sounder developed at the CSIRO ICT Centre, have been validated by a customized Geometric Optics-based ray tracing simulation. Based on measured and simulated MIMO-OFDM channel capacity and MIMO-OFDM capacity dynamic range, an improved deterministic model for MIMO-OFDM channels in indoor populated environments is presented. The model can be used for the design and analysis of future WLAN to be deployed in indoor environments. The results obtained show that, in both Fixed SNR and Fixed Tx for deterministic condition, the channel capacity dynamic range rose with the number of pedestrians as well as with the number of antenna combinations. In random scenarios with 10 pedestrians, an increment in channel capacity of up to 0.89 bits/sec/Hz in Fixed SNR and up to 1.52 bits/sec/Hz in Fixed Tx has been recorded compared to the one pedestrian scenario. In addition, from the results a maximum increase in average channel capacity of 49% has been measured while 4 antenna elements are used, compared with 2 antenna elements. The highest measured average capacity, 11.75 bits/sec/Hz, corresponds to the 4x4 array with 10 pedestrians moving randomly. Moreover, Additionally, the spread between the highest and lowest value of the the dynamic range is larger for Fixed Tx, predicted 5.5 bits/sec/Hz and measured 1.5 bits/sec/Hz, in comparison with Fixed SNR criteria, predicted 1.5 bits/sec/Hz and measured 0.7 bits/sec/Hz. This has been confirmed by both measurements and simulations ranging from 1 to 5, 7 and 10 pedestrians.
30
Fu, Weihuang. "Analytical Model for Capacity and Delay Optimization in Wireless Mesh Networks." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1289937944.
Full text
31
Chow, Y. C. "Performance analysis of bandwidth-efficient modulation schemes for high capacity wireless networks 1." Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337257.
Full text
32
Nair, Lakshmi Ravindran. "Industrial and office wideband MIMO channel performance." Diss., Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-11262009-181005/.
Full text
33
Zhou, Wen, and 周雯. "A study of channel estimation for OFDM systems and system capacity forMIMO-OFDM systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45555850.
Full text
34
Pal, Arindam. "Modelling the impact of antenna radiation patterns and propagation conditions on MIMO channel capacity." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435739.
Full text
35
Panagos, Adam, and Kurt Kosbar. "The Sum-Rate Capacity of a Cognitive Multiple Access Sensor Network." International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604466.
Full textAbstract:
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, NevadaThis paper investigates the sum-rate capacity of a cognitive multiple access (MAC) sensor network. The multiple access network consists of K sensors communicating to a common base station. Outside of the network exists another user of the radio spectrum. Each sensor of the MAC network is aware (i.e. cognitive) of this user, denoted the primary user, and transmits in a manner to avoid any interference to this user. No interference transmission is achieved using the dirty-paper coding technique. The sum-rate capacity is the theoretical maximum of the sum of the simultaneously achievable rates of each sensor within the network. Using a recently derived iterative algorithm, we quantify the sum-rate capacity of this network and investigate its behavior as a function of the number of sensors, cognitive signal-to-noise ratio (CSNR) and primary SNR (PSNR) in a Rayleigh fading environment. We also derive bounds and scaling results for the ergodic sum-rate capacity.
36
Li, Longguang. "On the capacity of free-space optical intensity channels." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLT028/document.
Full textAbstract:
Les systèmes de communication à intensité optique en espace libre (FSOI) sont largement utilisés dans les communications à courte portée, telles que les communications infrarouges entre des dispositifs électroniques portables. L’émetteur de ces systèmes module sur l’intensité des signaux optiques émis par des diodes électroluminescentes (LEDs) ou des diodes laser (LDs), et le récepteur mesure les intensités optiques entrantes au moyen de photodétecteurs. Les entrées ne sont pas négatives car elles représentent des intensités. En outre, ils sont généralement soumis à des contraintes de puissance de pointe et moyenne, la contrainte de puissance de pointe étant principalement dû aux limitations techniques des composants utilisés, alors que la contrainte de puissance moyenne est imposée par des limitations de batterie et des considérations de sécurité. En première approximation, le bruit dans de tels systèmes peut être supposé être gaussien et indépendant du signal transmis. Cette thèse porte sur les limites fondamentales des systèmes de communication FSOI, plus précisément sur leur capacité. L’objectif principal de notre travail est d’étudier la capacité d’un canal FSOI général à entrées multiples et sorties multiples (MIMO) avec une contrainte de puissance de crête par entrée et une contrainte de puissance moyenne totale sur toutes les antennes d’entrée. Nous présentons plusieurs résultats de capacité sur le scénario quand il y a plus d’antennes d’émission que d’antennes de réception, c’est à-dire, nT > nR > 1. Dans ce scénario, différents vecteurs d’entrée peuvent donner des distributions identiques à la sortie, lorsqu’ils aboutissent au même vecteur d’image multiplié par la matrice de canal. Nous déterminons d’abord les vecteurs d’entrée d’énergie minimale permettant d’atteindre chacun de ces vecteurs d’image. Il définit à chaque instant dans le temps un sous-ensemble de nT − nR antennes à zéro ou à pleine puissance et utilise uniquement les nR antennes restantes pour la signalisation. Sur cette base, nous obtenons une expression de capacité équivalente en termes de vecteur d’image, ce qui permet de décomposer le canal d’origine en un ensemble de canaux presque parallèles. Chacun des canaux parallèles est un canal MIMO nR x nR à contrainte d’amplitude, avec une contrainte de puissance linéaire, pour laquelle des limites de capacité sont connues. Avec cette décomposition, nous établissons de nouvelles limites supérieures en utilisant une technique de limite supérieure basée sur la dualité, et des limites inférieures en utilisant l’inégalité de puissance d’entropie (EPI). Les limites supérieure et inférieure dérivées correspondent lorsque le rapport signal sur bruit (SNR) tend vers l’infini, établissant la capacité asymptotique à haut SNR. À faible SNR, il est connu que la pente de capacité est déterminée par la trace maximale de la matrice de covariance du vecteur image. Nous avons trouvé une caractérisation de cette trace maximale qui est plus facile à évaluer en calcul que les formes précédentesFree-space optical intensity (FSOI) communication systems are widely used in short-range communication such as the infrared communication between electronic handheld devices. The transmitter in these systems modulates on the intensity of optical signals emitted by light emitting diodes (LEDs) or laser diodes (LDs), and the receiver measures incoming optical intensities by means of photodetectors. Inputs are nonnegative because they represent intensities. Moreover, they are typically subject to both peak- and average-power constraints, where the peak-power constraint is mainly due to technical limitations of the used components, whereas the average-power constraint is imposed by battery limitations and safety considerations. As a first approximation, the noise in such systems can be assumed to be Gaussian and independent of the transmitted signal. This thesis focuses on the fundamental limits of FSOI communication systems, more precisely on their capacity. The major aim of our work is to study the capacity of a general multiple-input multiple-output (MIMO) FSOI channel under a per-input-antenna peak-power constraint and a total average-power constraint over all input antennas. We present several capacity results on the scenario when there are more transmit than receive antennas, i.e., nT > nR > 1. In this scenario, different input vectors can yield identical distributions at the output, when they result in the same image vector under multiplication by the channel matrix. We first determine the minimum-energy input vectors that attain each of these image vectors. It sets at each instant in time a subset of nT − nR antennas to zero or to full power, and uses only the remaining nR antennas for signaling. Based on this, we derive an equivalent capacity expression in terms of the image vector, which helps to decompose the original channel into a set of almost parallel channels. Each of the parallel channels is an amplitude-constrained nR⇥nR MIMO channel, with a linear power constraint, for which bounds on the capacity are known. With this decomposition, we establish new upper bounds by using a duality-based upper-bounding technique, and lower bounds by using the Entropy Power Inequality (EPI). The derived upper and lower bounds match when the signal-to-noise ratio (SNR) tends to infinity, establishing the high-SNR asymptotic capacity. At low SNR, it is known that the capacity slope is determined by the maximum trace of of the covariance matrix of the image vector. We found a characterization to this maximum trace that is computationally easier to evaluate than previous forms
37
Holzer, Justin T. "Wideband Channel Characterization for MIMO Scenario." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd481.pdf.
Full text
38
Gulati, Vivek. "Concatenated codes for the multiple-input multiple-output quasi-static fading channel." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1477.
Full textAbstract:
The use of multiple antennas at the transmitter and/or the receiver promises
greatly increased capacity. This can be useful to meet the ever growing demand
of wireless connectivity, provided we can find techniques to efficiently exploit the
advantages of the Multiple-Input Multiple-Output (MIMO) system.
This work explores the MIMO system in a flat quasi-static fading scenario. Such
a channel occurs, for example, in packet data systems, where the channel fade is constant
for the duration of a codeword and changes independently from one transmission
to another. We first show why it is hard to compute the true constrained modulation
outage capacity. As an alternative, we present achievable lower bounds to this capacity
based on existing space-time codes. The bounds we compute are the fundamental
limits to the performance of these space-time codes under maximum-likelihood decoding,
optimal outer codes and asymptotically long lengths. These bounds also indicate
that MIMO systems have different behavior under Gaussian signaling (unconstrained
input) and under the finite alphabet setting. Our results naturally suggest the use of
concatenated codes to approach near-capacity performance. However, we show that a
system utilizing an iterative decoder has a fundamental limit it cannot be universal
and therefore it cannot perform arbitrarily close to its outage limit.
Next, we propose two different transceiver structures that have good performance.
The first structure is based on a novel BCJR-decision feedback decoder which
results in performance within a dB of the outage limit. The second structure is based
on recursive realizations of space-time trellis codes and uses iterative decoding at the
receiver. This recursive structure has impressive performance even when the channel
has time diversity. Thus, it forms the basis of a very flexible and robust MIMO
transceiver structure.
39
Yu, Kai. "Modeling of Multiple-Input Multiple-Output Radio Propagation Channels." Licentiate thesis, KTH, Signals, Sensors and Systems, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1478.
Full textAbstract:
In recent years, multiple-input multiple-output (MIMO)systems appear to be very promising since they can provide highdata rates in environments with sucient scattering byexploiting the spatial domain. To design a real MIMO wirelesssystem and predict its performance under certain circumstances,it is necessary to have accurate MIMO wireless channel modelsfor dierent scenarios. This thesis presents dierent models forindoor MIMO radio propagation channels based on 5.2 GHz indoorMIMO channel measurements.The recent research on MIMO radio channel modeling isbriey reviewed in this thesis. The models are categorized intonon-physical and physical models. The non-physical modelsprimarily rely on the statistical characteristics of MIMOchannels obtained from the measured data while the physicalmodels describe the MIMO channel (or its distribution) via somephysical parameters. The relationships between dierent modelsare also discussed.For the narrowband case, a non line-of-sight (NLOS)indoor MIMO channel model is presented. The model is based on aKronecker structure of the channel covariance matrix and thefact that the channel is complex Gaussian. It is extended tothe line-of-sight (LOS) scenario by estimating and modeling thedominant component separately.As for the wideband case, two NLOS MIMO channel modelsare proposed. The rst model uses the power delay prole and theKronecker structure of the second order moments of each channeltap to model the wideband MIMO channel while the second modelcombines a simple single-input single-output (SISO) model withthe same Kronecker structure of the second order moments.Monte-Carlo simulations are used to generate indoor MIMOchannel realizations according to the above models. The resultsare compared with the measured data and good agreement has beenobserved.
40
Onubogu, Okechukwu J. "Simulation and measurement based MIMO & vehicular channel characterization at 920 MHz and 5.8 GHz." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/96272/1/Okechukwu_Onubogu_Thesis.pdf.
Full textAbstract:
This thesis is a step forward in characterizing radio propagation channels in vehicular communications systems using multiple transmitting and receiving antennas. The vehicular channel measurement, modelling and characterization performed in this thesis would help system designers to develop a deeper understanding of the underlying propagation channels needed for the design of efficient and reliable vehicular communications systems.
41
Sato, Takeshi, Abbas Sandouk, Takaya Yamazato, Masaaki Katayama, and Akira Ogawa. "System Capacity of an Integrated Voice and Data CDMA Network in Channel Load Sensing Protocol." IEEE, 1997. http://hdl.handle.net/2237/7783.
Full text
42
JEAN-PIERRE, Edler, and 尚必威. "Channel Capacity over Rice Fading Channels." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/49468853152491815537.
Full textAbstract:
碩士中華技術學院
電子工程研究所碩士班
94
In this thesis, information rates of mobile radio channels are studied (precisely in the second chapter), the channel state information (CSI) being known by neither the transmitter nor the receiver. The channel considered is a time varying Rice fading process in which one of the characteristics is the presence of a Doppler spectrum with specified normalized fading rate. In the last chapter, the concept of combined equalization for uplink multi-carrier code-division multiple access (MC-CDMA) is studied and a theoretical analysis indicates that better single-user bounds than the classical matched-filter bounds are achieved with this new concept within the scope of Rice fading environment is computed. In this last part the CSI is assumed to be known. Finally, it is illustrated how to properly design an uplink MC-CDMA transmitter and receiver for combined equalization.
43
Perera, Ranjana. "On capacity of fading channels with no channel state information." Phd thesis, 2006. http://hdl.handle.net/1885/10354.
Full textAbstract:
The rapid development of communication systems with mobile receivers at higher data rates has lead to the importance of studies on information transfer over highly time varying channels. Under such circumstances, the channel variations become fast and the receiver is unable to track the channel during the predefined block length. Here existing results for the channel capacity and the optimal input distribution, under the assumption of knowledge of the channel state information (CSI) are no longer valid. In reality the capacity is significantly reduced in the absence of the CSI at both the transmitter and the receiver. Furthermore, finding the optimal input distribution with no CSI is considered an important problem in information theory.
This thesis first considers the important case of Gaussian signalling in both single input single output (SISO) and multiple input multiple output (MIMO) fading channels with no CSI. For such a signalling scheme we develop closed form solutions for the mutual information at any signal to noise ratio (SNR) for any number of antennas. Furthermore, we use these new expressions to identify the bounds at high SNR and particularly the use of optimal antennas at both ends of a communication system.
To overcome the existing di±culties in calculating the optimal input and the capacity, a novel approach is shown to identify the key characteristics of the optimal input in non-coherent Rayleigh fading MIMO channels. Unlike most work in the literature, this leads to a capacity upper bound which can be obtained without extensive simulations for any antenna number at any SNR. Furthermore, the capacity is shown numerically, deriving the optimal input distribution for any antenna number using a scaler channel model. In particular, some key properties of the optimal input distribution at low SNR is investigated studying the loss in information transfer due to unknown CSI in MIMO wireless communication systems.
44
Li, I.-Hsueh, and 李宜學. "Channel Capacity Evaluation for MIMO-OFDM." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/44142752589974267749.
Full textAbstract:
碩士國立暨南國際大學
電機工程學系
91
In this thesis two multi-path channel models, the indoor IEEE 802.11 channel and the outdoor COST 207, are used to evaluate the channel capacity and performance of MIMO-OFDM systems. According to some statistic characteristics over various channel models, the variations of sub-channel capacity over MIMO-OFDM are observed and analyzed. Computer simulations and illustration demonstrate that the MIMO-OFDM systems can effectively combat frequency-selective fading and meanwhile maintain very high spectrum efficiency. MIMO-WLAN is selected as a study example to illustrate the balance between system complexity and performance over fading channel. It is recommend that a 3Í3 MIMO-OFDM structure might be a good choice for the WLAN systems.
45
Huang, Wei-Chen, and 黃偉誠. "Under Channel Capacity Constraint - Joint Source/Channel Coding in Video Transmission." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/89618596255742870538.
Full textAbstract:
碩士國立臺灣海洋大學
導航與通訊系
93
Abstract The objective of this thesis is to investigate the joint source/channel coding algorithm, which provides a uniform video transmission rate to achieve better system performance with limited channel capacity. In the proposed algorithm we provid MPEG2 video coding scheme , and turbo channel coding technique as well as BPSK/QPSK for modulation method. In general, source coding and channel coding have been separately designed in order to achieve the best system performance, but which does not show a better performance while simply connecting the best Source coding scheme with the best channel coding scheme together.. Consequently, this study employs joint source-channel coding scheme and considers modulation to get the best performance in the system design. The proposed assigned rates to MPEG2 source coding and turbo channel coding schemes based upon the feedback information from Performance Control Unit(PCU) as well as system channel capacity limitation, which ensures the given system can achieve the best performance compared to conventional systems.
46
Li, Chen-Yu, and 李鎮宇. "Channel Capacity Limitation and Joint Source-Channel Coding Applied in Image Transmission." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/00607823055895769797.
Full textAbstract:
碩士國立臺灣海洋大學
通訊與導航工程學系
100
Since the noise varies with the time variable and affects the communication channel, the signal-to-noise ratio of channel constantly varies while the signal transmits. Consequently, the available channel capacity will change while signal-to-noise ratio varies. The objective of this thesis is to investigate the appropriate combination of source coding and channel coding while the channel capacity changes. Since both code rates are different, there is a variety of image system transmission rate. With so many combinations, the key point is to research how to achieve the best system performance. Images are first processed by the Quadtree Segmentation. To acquire the source code, the result is processed by the Wavelet Transform and Vector Quantization. Within channel code, the turbo code is selected.Finally, the source code and channel code are combined. With the various channel capacity combinations, the simulated results are compared and analyzed for the best system performance conditions.
47
SEN, NEVROZ. "Channel Capacity in the Presence of Feedback and Side Information." Thesis, 2013. http://hdl.handle.net/1974/8112.
Full textAbstract:
This thesis deals with the Shannon-theoretic fundamental limits of channel coding for
single-user channels with memory and feedback and for multi-user channels with side information. We first consider the feedback capacity of a class of symmetric channels with memory modelled as nite-state Markov channels. The symmetry yields the existence of a hidden Markov noise process that facilitates the channel description as a function of input and noise, where the function satisfies a desirable invertibility property. We show that feedback does not increase capacity for such class of finite-state channels and that both their non-feedback and feedback capacities are achieved by an independent and uniformly distributed input. As a result, the capacity is given as a difference of output and noise entropy rates, where the output is also a hidden Markov process; hence, capacity can be approximated via well known algorithms.
We then consider the memoryless state-dependent multiple-access channel (MAC) where the encoders and the decoder are provided with various degrees of asymmetric noisy channel state information (CSI). For the case where the encoders observe causal, asymmetric noisy CSI and the decoder observes complete CSI, inner and outer bounds to the capacity region, which are tight for the sum-rate capacity, are provided. Next, single-letter characterizations for the channel capacity regions under each of the following settings are established: (a) the CSI at the encoders are non-causal and asymmetric deterministic functions of the CSI at the decoder (b) the encoders observe asymmetric noisy CSI with asymmetric delays and the decoder observes complete CSI; (c) a degraded message set scenario with asymmetric noisy CSI at the encoders and complete and/or noisy CSI at the decoder.
Finally, we consider the above state-dependent MAC model and identify what is required to be provided to the receiver in order to get a tight converse for the sum-rate capacity. Inspired by the coding schemes of the lossless CEO problem as well as of a recently proposed achievable region, we provide an inner bound which demonstrates the rate required to transmit this information to the receiver.Thesis (Ph.D, Mathematics & Statistics) -- Queen's University, 2013-07-12 13:48:59.849
48
Khare, Aparna. "Capacity and Coding for 2D Channels." 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8774.
Full textAbstract:
Consider a piece of information printed on paper and scanned in the form of an
image. The printer, scanner, and the paper naturally form a communication channel,
where the printer is equivalent to the sender, scanner is equivalent to the receiver,
and the paper is the medium of communication. The channel created in this way is
quite complicated and it maps 2D input patterns to 2D output patterns. Inter-symbol
interference is introduced in the channel as a result of printing and scanning. During
printing, ink from the neighboring pixels can spread out. The scanning process can
introduce interference in the data obtained because of the finite size of each pixel and
the fact that the scanner doesn't have infinite resolution. Other degradations in the
process can be modeled as noise in the system. The scanner may also introduce some
spherical aberration due to the lensing effect. Finally, when the image is scanned,
it might not be aligned exactly below the scanner, which may lead to rotation and
translation of the image.
In this work, we present a coding scheme for the channel, and possible solutions for a
few of the distortions stated above. Our solution consists of the structure, encoding
and decoding scheme for the code, a scheme to undo the rotational distortion, and
an equalization method.
The motivation behind this is the question: What is the information capacity of paper. The purpose is to find out how much data can be printed out and retrieved
successfully. Of course, this question has potential practical impact on the design of
2D bar codes, which is why encodability is a desired feature. There are also a number
of other useful applications however.
We could successfully decode 41.435 kB of data printed on a paper of size 6.7 X 6.7
inches using a Xerox Phasor 550 printer and a Canon CanoScan LiDE200 scanner. As
described in the last chapter, the capacity of the paper using this channel is clearly
greater than 0.9230 kB per square inch. The main contribution of the thesis lies in
constructing the entire system and testing its performance. Since the focus is on
encodable and practically implementable schemes, the proposed encoding method is
compared with another well known and easily encodable code, namely the repeat
accumulate code.
49
Chun-Mo, Lee, and 李俊模. "MIMO Capacity Evaluation and Performance in Fading Channel." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/ppbg3x.
Full textAbstract:
碩士亞東技術學院
資訊與通訊工程研究所
96
In recent year, wireless communication systems are required to provide high data rate service within very limited bandwidth. Therefore, most wireless communication systems lay stress on the enhancement of spectral efficiency. The worldwide interoperability for microwave access（WiMAX）is a newly developed technology system, which aims at providing high data rate service and employs MIMO technique with BPSK, QPSK, 16-QAM, 64-QAM modulations. In this paper, we focus on MIMO capacity analysis and link performance evaluation in Rayleigh fading channel in reference of Shannon capacity on the bandwidth efficiency plot. We use Monte-Carlo method to simulate systems under the same signal-to-noise ratio（SNR）for SISO, SIMO, MISO and MIMO system architectures. There are totally 100,000 random signal symbols that are transmitted through Rayleigh fading channel. We deploy Maximum-likelihood detector in the receiving end to plot the waterfall curves for the four kinds of different system architectures in BPSK, QPSK, 16-QAM, 64-QAM modulations. In simulation result, we can find at the same signal-to-noise ratio, MIMO system architecture can decreased system bit error rate. We choose the system bit error rate at 10-5 to analyze system bandwidth efficiency of the four kinds of system architectures in figure 4.6.1 and 4.6.2. In order to prove the accuracy of the simulation results, we verify the simulated data of BPSK modulation in Rayleigh fading channel with the data obtained by Siavash M. Alamouti[7], and compare 16-QAM modulation in Rayleigh fading channel with the results in Xiayu Zheng[8] as well. All these two comparisons show excellent consistent. Finally, we come to conclusion that the system in MIMO architecture can increase bandwidth efficiency and offer diversity gain over traditional SISO system architecture. The diversity gains of the four kinds of system architectures in Rayleigh fading environment are shown in figure 5.3.2.
50
Lin, Gu-Rong, and 林谷嶸. "Capacity Analysis of Multiple-Access Rician Fading Channel." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/95493875007894211721.
Full textAbstract:
碩士國立交通大學
電信工程系所
97
In this thesis the channel capacity of the noncoherent multiple-access Rician fading channel is investigated. In this channel, the transmitted signal is subject to additive Gaussian noise and Rician fading, i.e., the fading process is Gaussian in addition to a line-of-sight component. On the transmitter side the cooperation between users is not allowed, i.e., the users are assumed to be statistically independent. Based on the known result of the asymptotic capacity of a single-user fading channel, our work is to generalize it to the multiple-user sum-rate capacity. We study the single-antenna case only: all transmitters and the receiver use one antenna. We get a natural upper bound on the capacity if the constraint of independence between the users is relaxed, in which case the channel becomes a multiple-input single-output (MISO) channel. Also, a lower bound can be obtained if all users apart from one are switched off, which corresponds to a single-input single-output (SISO) channel. We improve these bounds and get an exact formula of the asymptotic capacity. The main concept we use in this thesis is escaping to infinity of input distributions, which means that when the available power tends to infinity, the input must use symbols that also tend to infinity. We propose that in the multiple-access fading channel, at least one user's distribution must escape to infinity. Based on this we obtain the result that the asymptotic sum-rate capacity is identical to the previously mentioned lower bound: the single-user SISO capacity. We conclude that in order to achieve the best sum-rate capacity in the multiple-access system, we have to switch off the users with bad channels and only allow those with the best channel to transmit.