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1
Valverde, Martínez David, and Otte Francisco Javier Parada. "Forward Error Correction for Packet Switched Networks." Thesis, Linköping University, Communication Systems, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11093.
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<p>The main goal in this thesis is to select and test Forward Error Correction (FEC) schemes suitable for network video transmission over RTP/UDP. There is a general concern in communication networks which is to achieve a tradeoff between reliable transmission and the delay that it takes. Our purpose is to look for techniques that improve the reliability while the realtime delay constraints are fulfilled. In order to achieve it, the FEC techniques focus on recovering the packet losses that come up along any transmission. The FEC schemes that we have selected are Parity Check algorithm, ReedSolomon (RS) codes and a Convolutional code. Simulations are performed to test the different schemes.</p><p>The results obtained show that the RS codes are the more powerful schemes in terms of recovery capabilities. However they can not be deployed for every configuration since they go beyond the delay threshold. On the other hand, despite of the Parity Check codes being the less efficient in terms of error recovery, they show a reasonable low delay. Therefore, depending on the packet loss probability that we are working with, we may chose one or other of the different schemes. To summarize, this thesis includes a theoretical background, a thorough analysis of the FEC schemes chosen, simulation results, conclusions and proposed future work.</p>
2
Jones, David Rhys. "Forward Error Correction in Memoryless Optical Modulation." UNF Digital Commons, 2011. http://digitalcommons.unf.edu/etd/171.
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The unprecedented growth in demand for digital media has led to an all-time high in society’s demand for information. This demand will in all likelihood continue to grow as technology such as 3D television service, on-demand video and peer-to-peer networking continue to become more common place. The large amount of information required is currently transmitted optically using a wavelength division multiplexing (WDM) network structure. The need to increase the capacity of the existing WDM network infrastructure efficiently is essential to continue to provide new high bandwidth services to end-users, while at the same time minimizing network providers’ costs. In WDM systems the key to reducing the cost per transported information bit is to effectively share all optical components. These components must operate within the same wavelength limited window; therefore it is necessary to place the WDM channels as close together as possible. At the same time, the correct modulation format must be selected in order to create flexible, cost-effective, high-capacity optical networks. This thesis presents a detailed comparison of Differential Quadrature Phase Shift Keying (DQPSK) to other modulation formats. This comparison is implemented through a series of simulations in which the bit error rate of various modulation formats are compared both with and without the presence of forward error correction techniques. Based off of these simulation results, the top performing modulation formats are placed into a multiplexed simulation to assess their overall robustness in the face of multiple filtering impairments.
3
Mei, Yan. "Combined forward error correction and error concealment for digital video transmission." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ64061.pdf.
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Agrawal, Navneet. "Machine Intelligence in Decoding of Forward Error Correction Codes." Thesis, KTH, Teknisk informationsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-215093.
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A deep learning algorithm for improving the performance of the Sum-ProductAlgorithm (SPA) based decoders is investigated. The proposed Neural NetworkDecoders (NND) [22] generalizes the SPA by assigning weights to the edges ofthe Tanner graph. We elucidate the peculiar design, training, and working of theNND. We analyze the edge weight’s distribution of the trained NND and providea deeper insight into its working. The training process of NND learns the edgeweights in such a way that the effects of artifacts in the Tanner graph (such ascycles or trapping sets) are mitigated, leading to a significant improvement inperformance over the SPA.We conduct an extensive analysis of the training hyper-parameters affectingthe performance of the NND, and present hypotheses for determining theirappropriate choices for different families and sizes of codes. Experimental resultsare used to verify the hypotheses and rationale presented. Furthermore,we propose a new loss-function that improves performance over the standardcross-entropy loss. We also investigate the limitations of the NND in termsof complexity and performance. Although the SPA based design of the NNDenables faster training and reduced complexity, the design constraints restrictthe neural network to reach its maximum potential. Our experiments show thatthe NND is unable to reach Maximum Likelihood (ML) performance thresholdfor any plausible set of hyper-parameters. However for short length (n 128)High Density Parity Check (HDPC) codes such as Polar or BCH codes, theperformance improvement over the SPA is significant.<br>En djup inlärningsalgoritm för att förbättra prestanda hos SPA-baserade (Sum-Product Algorithm) avkodare undersöks. Den föreslagna neuronnätsavkodaren(Neural Network Decoder, NND) [22] generaliserar SPA genom att tilldela viktertill bågarna i Tannergrafen. Vi undersöker neuronnätsavkodarens utformning,träning och funktion. Vi analyserar fördelningen av båg vikter hos en tränadneuronnätsavkodare och förmedlar en djupare insikt i dess funktion. Träningenav neuronnätsavkodaren är sådan att den lär sig bågvikter så att effekternaav artefakter hos Tannergrafen (såsom cykler och fångstmängder‡) minimeras,vilket leder till betydande prestandaförbättringar jämfört med SPA.Vi genomför en omfattande analys av de tränings-hyper-parametrar sompåverkar prestanda hos neuronnätsavkodaren och presenterar hypoteser för lämpligaval av tränings-hyper-parametrar för olika familjer och storlekar av koder. Experimentellaresultat används för att verifiera dessa hypoteser och förklaringarpresenteras. Dessutom föreslår vi ett nytt felmått som förbättrar prestanda jämförtmed det vanliga korsentropimåttet§. Vi undersöker också begränsningar hosneuronnätsavkodaren med avseende på komplexitet och prestanda. Neuronnätsavkodarenär baserad på SPA vilket möjliggör snabbare träning och minskadkomplexitet, till priset av begränsningar hos neuronnätsavkodaren som gör attden inte kan nå ML-prestanda för någon rimlig uppsättning tränings-hyperparametrar.För korta (n <= 128) högdensitetsparitetskoder (High-DensityParity Check, HDPC), exempelvis Polarkoder eller BCH-koder, är prestandaförbättringarnajämfört med SPA dock betydande.
5
Kong, Der-Hung. "Simulation of coherent signals with forward error correction coding." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion.exe/07Mar%5FKong.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, March 2007.<br>Thesis Advisor(s): Clark Robertson. "March 2007." Includes bibliographical references (p.47-48). Also available in print.
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Sancho, Sánchez Irene. "On Adaptive Forward Error Correction for Real Time Traffic." Thesis, KTH, Reglerteknik, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109478.
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Most of the real-time applications use user data protocol (UDP) as their transport protocol. The reason is that UDP does not provide flow control or error recovery and does not require connection management. Consequently it is a fast protocol suitable for applications that only need to transmit little data or for delay sensitive applications. Nevertheless, UDP has a major drawback, if some packets are dropped then there is no way to recover them. Some applications as video or audio could accept lower quality and most of the times the lost of some packets is less critic than the delay introduced by error recovery methods. Since more applications with real-time constraints such as video image and audio are introduced both over the wired Internet and over wireless some improvements should be made in order to obtain better performance. The main contribution of this thesis is to study an intermediate solution providing more reliability to the communication between applications running on top of UDP and at the same time support its fast connection quality using already existing protocols. In order to obtain it, real-time transport protocol (RTP) has been chosen as upper level protocol (to provide ”flowcontrol”) and an adaptive forward error correction (AFEC) technique has been studied (to provide error management). The idea of AFEC is to inject an adaptive amount of redundancy packets in every sent block (or datagram) in order to achieve a desired recovery rate at the receiver without using any retransmission mechanism. The sender dynamically uses feedback information from the receiver to decide the optimal amount of redundancy to introduce in every sent block. This decision task is managed by a control system at the sender side. Using the network simulator, ns-2, the performance of three different controllers using AFEC is evaluated. The results show in various scenarios that the amount of discarded blocks due to the corruption of some of its packets (block loss probability after decoding) decrease considerably when the AFEC mechanism is introduced.
7
Westerlund, Johan. "Forward Error Correction in Real-time Video Streaming Applications." Thesis, Umeå universitet, Institutionen för datavetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-99644.
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The Internet is rapidly becoming the dominant platform for video contribution and distribution, but today’s Internet provides a best-effort service without any guarantee of quality. Internet video streaming has to cope with this lack of guarantees. Due to congestion and the heterogeneous infrastructure of the Internet a video transmission will be plagued by packet loss, variability in throughput, and latency. To mitigate some of these these problems f.o.r.w.a.r.d e.r.r.o.r c.o.r.r.e.c.t.i.o.n (F.E.C) can be employed. The aim of this thesis is to present a theoretical introduction to error correcting codes, implement and integrate f.o.r.w.a.r.d e.r.r.o.r c.o.r.r.e.c.t.i.o.n into an existing video streaming application, and test the implementation in both simulated and real-world conditions. Parameters of the F.E.C algorithm will be tweaked and guidelines for parameter selection will be developed
8
Noriega, Alexandra. "Matlab Implementation of a Tornado Forward Error Correction Code." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc84260/.
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This research discusses how the design of a tornado forward error correcting channel code (FEC) sends digital data stream profiles to the receiver. The complete design was based on the Tornado channel code, binary phase shift keying (BPSK) modulation on a Gaussian channel (AWGN). The communication link was simulated by using Matlab, which shows the theoretical systems efficiency. Then the data stream was input as data to be simulated communication systems using Matlab. The purpose of this paper is to introduce the audience to a simulation technique that has been successfully used to determine how well a FEC expected to work when transferring digital data streams. The goal is to use this data to show how FEC optimizes a digital data stream to gain a better digital communications systems. The results conclude by making comparisons of different possible styles for the Tornado FEC code.
9
Li, Wei, and Zhiyuan Guo. "On Forward Error Correction in IEEE 802.15.4 Wireless Sensor Networks." Thesis, Mittuniversitetet, Institutionen för informationsteknologi och medier, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-16614.
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Wireless Sensor Networks (WSN) are used in many applications, for example industrial applications, automatic control applications, monitoring applications, to name but a few. Although WSN can employ different standards in order to achieve short range wireless communication, the mainstream of the market is toadopt the low-power, low-rate IEEE 802.15.4 standard. However, this standard does not specify any block codes on the Physical layer (PHY) and the MAC sublayer. Reliability and energy efficiency are two important metrics used to evaluate the WSN performance. In order to enhance the reliability of the WSN performance, schemes such as Forward Error Correction (FEC) and HybridAutomatic Repeat-reQuest (HARQ) can be introduced on the PHY and MACsublayer when transmitting signals. However, this will reduce the energy efficiency of the WSN. In order to investigate what does affect the reliability and energy efficiency, this thesis has been conducted with the assistance of Matlab simulations, which simulate different transmission schemes proposed by the authors. Based on the simulations, both the reliability and energy efficiency can be evaluated and the results are illustrated for both metrics. The objective of this thesis is to determine a scheme that is able to meet these metric requirements.
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Hashmi, Shafiq Ullah. "Efficient forward error correction coding technique for spread spectrum communications." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0021/MQ54317.pdf.
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Du, Toit F. J. "A fountain code forward error correction strategy for SensLAB applications." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86399.
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Thesis (MScEng)--Stellenbosch University, 2014.<br>ENGLISH ABSTRACT: The discovery of sparse graph codes, used in forward error correction strate-
gies, has had an unrivaled impact on Information theory over the past decade.
A recent advancement in this field, called Fountain codes, have gained much
attention due to its intelligent rate adaptivity, and lend itself to applications
such as multicasting and broadcasting networks. These particular properties
can be considered valuable in a wireless sensor network setting as it is capable of providing forward error correction, and the added conceptual network
protocol related extensions.
A wireless sensor network testbed in France, called SensLAB, provides an
experimental facility for researchers to develop and evaluate sensor network
protocols, aside from a simulation environment. Tremendous value can be
added to the SensLAB community if an appropriate forward error correction
design, such as Fountain codes, is deemed feasible for use on such a platform.
This thesis investigates the use of Fountain codes, in a binary erasure channel environment, as a forward error correction strategy for the distribution of
reliable data content over the SensLAB platform. A short message length LT
code using two different decoding mechanisms were developed and evaluated
for possible implementation. Furthermore, a short message length Raptor code
was developed by using supplementary theory and optimisation techniques
that permit scalability in terms of the message size. The results favoured the
Raptor code design as it performs close to near optimal while still satisfying
the rateless- and universality property, at low computational complexity.<br>AFRIKAANSE OPSOMMING: Die ontdekking van yl-grafiekkodes, van toepassing op foutkorreksie strategieë, het onlangs 'n ongeewenaarde impak op Informasieteorie gehad. In 'n
onlangse vooruitgang in hierdie veld, genoem Fonteinkodes, word daar meer
fokus geplaas op die intelligente tempo aanpassingsvermoë van hierdie kodes,
wat nuttige toepassing kan inhou in multi-saai- en uitsaai netwerke. Hierdie
eienskappe kan moontlik as waardevol beskou word in draadlose sensor netwerke weens die fout regstellingsvermoë en die bykomende konseptuele netwerk protokol verwante uitbreidings.
'n Draadlose sensor netwerk toetsplatvorm in Frankryk, genoem die SensLAB, bied navorsers die geleentheid om eksperimentele sensor netwerk protokolle te ontwikkel en te toets buite 'n tipiese simulasie-omgewing. Groot
waarde kan bygevoeg word aan die SensLAB gemeenskap indien 'n geskikte
foutkorreksie strategie ontwikkel word, soos Fonteinkodes, en as geskik beskou
kan word vir hierdie platvorm.
In hierdie tesis word Fonteinkodes saam met die SensLAB platvorm ondersoek, binne die raamwerk van 'n binêre verlieskanaal, om vir foutkorreksie oor die verspreiding van betroubare data in SensLAB op te tree. 'n Kort boodskap
LT kode word voorgestel deur van twee verskillende dekoderings meganismes
gebruik te maak. 'n Alternatief, genaamd Raptorkode, was ook ondersoek. 'n
Raptorkode. 'n Kort boodskap Raptor kode, wat ontwikkel is met bykomende
teorie en optimeringstegnieke, word ook voorgestel. Die bykomende tegnieke
bied 'n skaleerbare boodskap lengte terwyl dit tempoloos en universeel bly, en
lae kompleksiteit bied.
12
Boru, Sileshi, and Diptasree Maitra. "Performance Analysis of iNET Using Forward Error Correction and OFDM." International Foundation for Telemetering, 2010. http://hdl.handle.net/10150/604249.
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ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California<br>This paper shows the improvement in performance for OFDM modulation on aeronautical channels with the addition of convolution coding. OFDM is envisioned for use on the Integrated Network Enhanced Telemetry (INET) on aeronautical channels that experience multipath fading which causes inter-symbol interference (ISI). Forward error correction coding, such as convolution coding (cc), significantly improves the bit error rate (BER) of OFDM with multipath fading. Theoretical and simulated results show a performance increase of up to 10dB with the introduction of coding gain and the cyclic prefix (cp). Such improvements can be applied to reduce errors or increase data rates for INET.
13
McLuckie, Craig Ian. "The application of forward error correction techniques in wireless ATM." Master's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/21685.
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Bibliography: pages 116-121.<br>The possibility of providing wireless access to an ATM network promises nomadic users a communication tool of unparalleled power and flexibility. Unfortunately, the physical realization of a wireless A TM system is fraught with technical difficulties, not the least of which is the problem of supporting a traditional ATM protocol over a non-benign wireless link. The objective of this thesis, titled "The Application of Forward Error Correction Techniques in Wireless ATM' is to examine the feasibility of using forward error correction techniques to improve the perceived channel characteristics to the extent that the channel becomes transparent to the higher layers and allows the use of an unmodified A TM protocol over the channel. In the course of the investigation that this dissertation describes, three possible error control strategies were suggested for implementation in a generic wireless channel. These schemes used a combination of forward error correction coding schemes, automatic repeat request schemes and interleavers to combat the impact of bit errors on the performance of the link. The following error control strategies were considered : 1. A stand alone fixed rate Reed-Solomon encoder/decoder with automatic repeat request. 2. A concatenated Reed-Solomon, convolution encoder/decoder with automatic request and convolution interleaving for the convolution codec. 3. A dynamic rate encoder/decoder using either a concatenated Reed-Solomon, convolution scheme or a Reed-Solomon only scheme with variable length Reed-Solomon words.
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Alheraish, Abdulmohsen Abdulrahman. "Reliable VBR video communications using error control techniques over ATM networks." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248517.
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Alzubi, Jafar A. "Forward error correction coding and iterative decoding using algebraic geometric theory." Thesis, Swansea University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582101.
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Wong, Kitty Kar Yan. "Multi-user interference cancellation in DS-CDMA with forward error correction." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0012/MQ53036.pdf.
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Sefara, Mamphoko Nelly. "Design of a forward error correction algorithm for a satellite modem." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52181.
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Thesis (MScEng)--University of Stellenbosch, 2001.<br>ENGLISH ABSTRACT: One of the problems with any deep space communication system is that information may
be altered or lost during transmission due to channel noise. It is known that any damage
to the bit stream may lead to objectionable visual quality distortion of images at the
decoder. The purpose of this thesis is to design an error correction and data compression
algorithm for image protection, which will allow the communication bandwidth to be
better utilized. The work focuses on Sunsat (Stellenbosch Satellite) images as test
images. Investigations were done on the JPEG 2000 compression algorithm's robustness
to random errors, putting more emphasis on how much of the image is degraded after
compression. Implementation of both the error control coding and data compression
strategy is then applied to a set of test images. The FEe algorithm combats some if not
all of the simulated random errors introduced by the channel. The results illustrates that
the error correction of random errors is achieved by a factor of 100 times (xl00) on all
test images and that the probability of error of 10-2in the channel (10-4for image data)
shows that the errors causes little degradation on the image quality.<br>AFRIKAANSE OPSOMMING: Een van die probleme met kommunikasie in die ruimte is dat informasie mag verlore
gaan en! of gekorrupteer word deur ruis gedurende versending deur die kanaal. Dit is
bekend dat enige skade aan die bisstroom mag lei tot hinderlike vervorming van die
beelde wat op aarde ontvang word. Die doel van hierdie tesis om foutkorreksie en
datakompressie te ontwikkel wat die satelliet beelde sal beskerm gedurende versending
en die kommunikasie kanaal se bandwydte beter sal benut. Die werk fokus op SUNSAT
(Stellenbosch Universiteit Satelliet) se beelde as toetsbeelde. Ondersoeke is gedoen na
die JPEG2000 kompressie algoritme se bestandheid teen toevalsfoute, met klem op
hoeveel die beeld gedegradeer word deur die bisfoute wat voorkom. Beide die
kompressie en die foutkorreksie is ge-implementeer en aangewend op die toetsbeelde.
Die foutkorreksie bestry die gesimuleerde toevalsfoute, soos wat dit op die kanaal
voorkom. Die resultate toon dat die foutkorreksie die toevalsfoute met 'n faktor 100
verminder, en dat 'n foutwaarskynlikheid van 10-2 op die kanaal (10-4 op die beelddata)
weinig degradering in die beeldkwaliteit veroorsaak.
18
Asghari, Hossein. "Bandwidth-efficient forward-error-correction-coding for long burst noise channels." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0012862.
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Döser, Erman. "Tradeoffs between retransmission and forward error correction in the RTP stack." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-160855.
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Video conferencing applications has reached worldwide usage in recent years by the help of the improvements in network infrastructures for public services. Media data covers a significant ratio of data traffic over IP networks. However, it is challenging to ensure a decent quality of service (QoS) on public networks in terms of video and audio quality. The main factor that may cause degradation in media playback quality is packet losses. There are various techniques available to conceal packet losses in lossy channels. According to the application needs and channel characteristics such as loss patterns and round trip times, retransmission or forward error correction techniques may be applied at application level. These two techniques have different challenges which lead to tradeoffs between them, thus one might be chosen over the others. In this thesis work, retransmission’s worst case performances under considered packet loss patterns and various round trip times are compared to performances of forward error correction schemes. In addition, implementation details with respect to the relevant RFCs are provided as an example to give a better judgement on the obtained results. Results obtained under the packet loss patterns that are generated with a simple Gilbert-Elliot 2-state model shows that forward error correction techniques are a reasonable choice of error concealing in the real-time transport protocol (RTP) stack where round trip time in the channel is greater than 200 ms. In addition, bandwidth overhead revealed by forward error correction stays higher than retransmission’s bandwidth overhead in all sample runs. In cases where round trip times are high, then the choice of forward error correction scheme is bound to the packet loss pattern. In the results section, it is obtained that ReedSolomon performs well in terms of residual packet losses, which are the packets not being recovered, and bandwidth overhead when losses occur in long bursts.
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Wang, Xiaohan Sasha. "Investigation of Forward Error Correction Coding Schemes for a Broadcast Communication System." Thesis, University of Canterbury. Computer Science and Software Engineering, 2013. http://hdl.handle.net/10092/7902.
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This thesis investigates four FEC (forward error correction) coding schemes for their suitability
for a broadcast system where there is one energy-rich transmitter and many energy-constrained
receivers with a variety of channel conditions. The four coding schemes are: repetition codes (the
baseline scheme); Reed-Solomon (RS) codes; Luby-Transform (LT) codes; and a type of RS and
LT concatenated codes. The schemes were tested in terms of their ability to achieve both high
average data reception success probability and short data reception time at the receivers (due to
limited energy). The code rate (Rc) is fixed to either 1/2 or 1/3. Two statistical channel models were
employed: the memoryless channel and the Gilbert-Elliott channel. The investigation considered
only the data-link layer behaviour of the schemes. During the course of the investigation, an
improvement to the original LT encoding process was made, the name LTAM (LT codes with
Added Memory) was given to this improved coding method. LTAM codes reduce the overhead
needed for decoding short-length messages. The improvement can be seen for decoding up to
10000 number of user packets. The maximum overhead reduction is as much as 10% over the
original LT codes.
The LT-type codes were found to have the property that can both achieve high success data
reception performance and flexible switch off time for the receivers. They are also adaptable to
different channel characteristics. Therefore it is a prototype of the ideal coding scheme that this
project is looking for. This scheme was then further developed by applying an RS code as an
inner code to further improve the success probability of packet reception. The results show that
LT&RS code has a significant improvement in the channel error tolerance over that of the LT
codes without an RS code applied. The trade-off is slightly more reception time needed and more
decoding complexity. This LT&RS code is then determined to be the best scheme that fulfils the
aim in the context of this project which is to find a coding scheme that both has a high overall data
reception probability and short overall data reception time.
Comparing the LT&RS code with the baseline repetition code, the improvement is in three
aspects. Firstly, the LT&RS code can keep full success rate over channels have approximately
two orders of magnitude more errors than the repetition code. This is for the two channel models
and two code rates tested. Secondly, the LT&RS code shows an exceptionally good performance
under burst error channels. It is able to maintain more than 70% success rate under the long
burst error channels where both the repetition code and the RS code have almost zero success
probability. Thirdly, while the success rates are improved, the data reception time, measured in
terms of number of packets needed to be received at the receiver, of the LT&RS codes can reach a
maximum of 58% reduction for Rc = 1=2 and 158% reduction for Rc = 1=3 compared with both
the repetition code and the RS code at the worst channel error rate that the LT&RS code maintains
almost 100% success probability.
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Pénicaud, Michel. "Iterative decoding for rate adaptive forward error correction on the mobile satellite channel." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10169.
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In this thesis, we examine rate adaptive forward error correction codes for the mobile satellite channel. We are especially interested in codes that can be iteratively decoded. Multilevel coded modulations are considered: partitioning of constellations, coding principle and iterative decoding are studied. We present design rules for multilevel coded modulations through the asymptotic coding gain, the minimum Hamming distance of the code and with information theory arguments. Computer simulations have been run to confirm the validity of the design rules and to determine the impact of the interleaver size on the performance of a coded modulation scheme. A new construction for multilevel coded modulation with parallel concatenation is suggested. Computer simulations have confirmed the efficiency of this new technique. Product codes are also considered: code construction and iterative decoding algorithms are studied. We focus on the two-dimensional (24, 12) Golay product code and find its performances on AWGN and Rayleigh fading channels through computer simulations. Three rate coding systems for the mobile satellite channel are presented. A performance criterion for speech transmission with such systems have been determined. Adaptive rate techniques can save up to 5.0 dB and 8.8 dB (depending on the type of environment) in terms of transmitted power.
22
Zhang, Liren. "Recovery of cell loss in ATM networks using forward error correction coding techniques /." Title page, contents and summary only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09phz6332.pdf.
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Thesis (Ph. D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 1993.<br>Copies of author's previously published articles inserted. Includes bibliographical references (leaves 179-186).
23
Rawat, Sachin. "Implementation of a Forward Error Correction Technique using Convolutional Encoding with Viterbi Decoding." Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1088439298.
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Temple, Kip. "PERFORMANCE TRADE-OFFS WHEN IMPLEMENTING TURBO PRODUCT CODE FORWARD ERROR CORRECTION FOR AIRBORNE TELEMETRY." International Foundation for Telemetering, 2005. http://hdl.handle.net/10150/604798.
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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, Nevada<br>Hardware implementing forward error correction (FEC) is currently available for utilization by the
airborne telemetry system designer. This paper will discuss the potential benefits along with drawbacks
when using this technology. Laboratory testing is supplemented with real-world flight testing.
Performance results comparing FEC and non-FEC systems are presented for both IRIG-106 Pulse Code
Modulation/Frequency Modulation, PCM/FM, (or Continuous Phase Frequency Shift Keying, CPFSK,
with filtering, or ARTM Tier 0) and Shaped Offset Quadrature Phase Shift Keying, Telemetry Group
version (SOQPSK-TG or ARTM Tier I) waveforms.
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Ghimire, L. (Lalit). "Joint analysis of packet size and forward error correction in IEEE 802.15.4 type networks." Master's thesis, University of Oulu, 2015. http://urn.fi/URN:NBN:fi:oulu-201512052255.
Full textAbstract:
Wireless sensor networks (WSNs) are gaining popularity in different areas of applications like industrial monitoring, military applications, home automation, smart grid applications, body organ monitoring, etc. A WSN is a wireless network comprising of a number of devices, called sensor nodes. A sensor node, usually battery powered, is capable of detecting physical phenomena, such as light, temperature, movement, noise, pressure, humidity, etc. Medium access control (MAC) protocols are in a key role for determining the energy efficiency of a WSN, which is a key design issue for battery operated sensor nodes. Alongside energy efficiency, reliable transmission is also always preferred in communication networks. The IEEE 802.15.4 standard provides low power solutions to the WSN applications by specifying physical and MAC layer functions for low rate wireless personal area networks.
In this thesis, Markov chain models are derived to study the throughput and the energy consumption of IEEE 802.15.4 MAC taking into account the packet corruption by both collisions and channel errors. An increase in reliability reduces retransmissions of erroneous packets, which in turn reduces the energy consumption. Therefore, a network with low energy consumption and high reliability is always desired. Wireless radio channel is the medium used for the transmissions in WSNs and it is error prone leading to received data corruption. To mitigate this influence of channel to some extent, forward error correction (FEC) may be employed. FEC provides error correction with the addition of redundant bits to the original message. Various FEC codes are analysed to study the influence of coding on the performance of the IEEE 802.15.4 type networks. Along with the FEC, influence of data frame payload size on performance is also studied. Numerical analyses are carried out and illustrated using Matlab. The results show that the performance of an IEEE 802.15.4 type network can be improved using an appropriate choice of payload size and FEC.
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Fagervik, Kjetil. "Iterative decoding of concatenated codes." Thesis, University of Surrey, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268307.
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Temple, Kip. "Performance Evaluation of Low Density Parity Check Forward Error Correction in an Aeronautical Flight Environment." International Foundation for Telemetering, 2014. http://hdl.handle.net/10150/578364.
Full textAbstract:
ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA<br>In some flight test scenarios the telemetry link is noise limited at long slant ranges or during signal fade events caused by antenna pattern nulls. In these situations, a mitigation technique such as forward error correction (FEC) can add several decibels to the link margin. The particular FEC code discussed in this paper is a variant of a low-density parity check (LDPC) code and is coupled with SOQPSK modulation in the hardware tested. This paper will briefly cover lab testing of the flight-ready hardware then present flight test results comparing a baseline uncoded telemetry link with a LDPC-coded telemetry link. This is the first known test dedicated to this specific FEC code in a real-world test environment with flight profile tailored to assess the viability of an LDPC-coded telemetry link.
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Hayes, Bob. "LOW DENSITY PARITY CHECK CODES FOR TELEMETRY APPLICATIONS." International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604497.
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, Nevada<br>Next generation satellite communication systems require efficient coding schemes that enable high data rates, require low overhead, and have excellent bit error rate performance. A newly rediscovered class of block codes called Low Density Parity Check (LDPC) codes has the potential to revolutionize forward error correction (FEC) because of the very high coding rates. This paper presents a brief overview of LDPC coding and decoding. An LDPC algorithm developed by Goddard Space Flight Center is discussed, and an overview of an accompanying VHDL development by L-3 Communications Cincinnati Electronics is presented.
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Chan, Morgan Hing Lap. "Channel characterization and forward error correction coding for data communications on intrabuilding electric power lines." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/29071.
Full textAbstract:
The use of intrabuilding electric power lines for data communications and local area networking is of growing interest. In this thesis, an original work to study the very important signal propagation and noise characteristics of the complex and hostile power line networks has been completed. Various impairments such as high and varying signal attenuation levels, periodic signal fading and impulse noise were identified. Estimates of the amplitude, pulse width and interarrival distributions of impulse noise were obtained. Communication signal attenuation of power line networks was explored. The effects of electrical loading on these communication channel factors were examined. Implications of the results for intrabuilding communications are addressed.
To combat power line impulse noise, channel fading, attenuation and other impairments, forward error correction (FEC) coding and bit interleaving is proposed and shown to be very effective, and is an essential component for reliable communication over power lines. The performance of interleaved hard and soft decision decoding of repetition codes with or without erasure has been analysed, using a simple first order power line noise model. Various random and burst error correcting block codes have been evaluated, using actual recorded bit error patterns encountered on power line data channels.
Based on studies of the channel and error correction coding, an actual low cost FEC coded communication system for use on intrabuilding power lines was successfully designed, implemented and tested. Real time performance results of coded and uncoded data transmissions on typical power lines were experimentally determined. Convolutional codes as well as repetition coding and bit interleaving are used to overcome burst errors and other impairments encountered on power line channels. The emphasis is on high speed transmission at bit transmission rates up to 57.6 kbits/s. Typical practical coding gains from 10 to 20 dB were achieved at bit error rate of 10⁻⁴ on various noisy links. It is successfully demonstrated that with appropriate and inexpensive FEC coding, reliable high speed data transmission over power lines is feasible, even at very small interleaving delay.<br>Applied Science, Faculty of<br>Electrical and Computer Engineering, Department of<br>Graduate
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Cirineo, Tony, and Bob Troublefield. "STANDARD INTEROPERABLE DATALINK SYSTEM, ENGINEERING DEVELOPMENT MODEL." International Foundation for Telemetering, 1995. http://hdl.handle.net/10150/608398.
Full textAbstract:
International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada<br>This paper describes an Engineering Development Model (EDM) for the Standard
Interoperable Datalink System (SIDS). This EDM represents an attempt to design and
build a programmable system that can be used to test and evaluate various aspects of a
modern digital datalink. First, an investigation was started of commercial wireless
components and standards that could be used to construct the SIDS datalink. This
investigation lead to the construction of an engineering developmental model. This
model presently consists of wire wrap and prototype circuits that implement many
aspects of a modern digital datalink.
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Iltis, Ronald A. "Decoding and Turbo Equalization for LDPC Codes Based on Nonlinear Programming." International Foundation for Telemetering, 2010. http://hdl.handle.net/10150/605945.
Full textAbstract:
ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California<br>Decoding and Turbo Equalization (TEQ) algorithms based on the Sum-Product Algorithm (SPA) are well established for LDPC codes. However there is increasing interest in linear and nonlinear programming (NLP)-based decoders which may offer computational and performance advantages over the SPA. We present NLP decoders and Turbo equalizers based on an Augmented Lagrangian formulation of the decoding problem. The decoders update estimates of both the Lagrange multipliers and transmitted codeword while solving an approximate quadratic programming problem. Simulation results show that the NLP decoder performance is intermediate between the SPA and bit-flipping algorithms. The NLP may thus be attractive in some applications as it eliminates the tanh/atanh computations in the SPA.
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Geoghegan, Mark. "EXTENDING THE RANGE OF PCM/FM USING A MULTISYMBOL DETECTOR AND TURBO CODING." International Foundation for Telemetering, 2002. http://hdl.handle.net/10150/607538.
Full textAbstract:
International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California<br>It has been shown that a multi-symbol detector can improve the detection efficiency of PCM/FM by 3 dB when compared to traditional methods without any change to the transmitted waveform. Although this is a significant breakthrough, further improvements are possible with the addition of Forward Error Correction (FEC). Systematic redundancy can be added by encoding the source data prior to the modulation process, thereby allowing channel errors to be corrected using a decoding circuit. Better detection efficiency translates into additional link margin that can be used to extend the operating range, support higher data throughput, or significantly improve the quality of the received data. This paper investigates the detection efficiency that can be achieved using a multisymbol detector and turbo product coding. The results show that this combination can improve the detection performance by nearly 9 dB relative to conventional PCM/FM systems. The increase in link margin is gained at the expense of a small increase in bandwidth and the additional complexity of the encoding and decoding circuitry.
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Faucher, Julien. "An optoelectronic-VLSI chip with forward error correction to improve the reliability of parallel optical data links /." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32957.
Full textAbstract:
Parallel optical interconnects (POIs) promise to deliver tremendous gains in bandwidth for applications such as massively parallel computing systems and telecommunication switches. At the core of any interconnect solution lies the fundamental problem of reliable transmission. Next-generation optical communication designers are running into hard limits when it comes to increasing data transmission rates and reducing errors. These two factors are typically in opposing balance: minimize bit error rate (BER) and data rates suffer, increase transmission rates and data integrity is compromised.<br>To answer these design challenges, this thesis proposes to use forward error correction (FEC) codes in an attempt to simultaneously improve data throughput, reduce BER and reduce power consumption. To verify that this is indeed possible, an optoelectronic-VLSI (OE-VLSI) chip with a FEC module was implemented in CMOS. This chip was designed in the context of a POI prototype system to demonstrate 1080 optical interconnections between two OE-VLSI chips.
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Eriksson, Oskar. "Error Control in Wireless Sensor Networks : A Process Control Perspective." Thesis, Uppsala universitet, Signaler och System, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160784.
Full textAbstract:
The use of wireless technology in the process industry is becoming increasingly important to obtain fast deployment at low cost. However, poor channel quality often leads to retransmissions, which are governed by Automatic Repeat Request (ARQ) schemes. While ARQ is a simple and useful tool to alleviate packet errors, it has considerable disadvantages: retransmissions lead to an increase in energy expenditure and latency. The use of Forward Error Correction (FEC) however offers several advantages. We consider a Hybrid-ARQ-Adaptive-FEC scheme (HAF) based on BCH codes and Channel State Information. This scheme is evaluated on AWGN and fading channels. It is shown that HAF offers significantly improved performance both in terms of energy efficiency and latency, as compared to ARQ.
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Robie, David Lee. "Error Correction and Concealment of Bock Based, Motion-Compensated Temporal Predition, Transform Coded Video." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7101.
Full textAbstract:
Error Correction and Concealment of Block Based, Motion-Compensated Temporal Prediction, Transform Coded Video
David L. Robie
133 Pages
Directed by Dr. Russell M. Mersereau
The use of the Internet and wireless networks to bring multimedia to the consumer continues to expand. The transmission of these products is always subject to corruption due to errors such as bit errors or lost and ill-timed packets; however, in many cases, such as real time video transmission, retransmission request (ARQ) is not practical. Therefore receivers must be capable of recovering from corrupted data. Errors can be mitigated using forward error correction in the encoder or error concealment techniques in the decoder. This thesis investigates the use of forward error correction (FEC) techniques in the encoder and error concealment in the decoder in block-based, motion-compensated, temporal prediction, transform codecs. It will show improvement over standard FEC applications and improvements in error concealment relative to the Motion Picture Experts Group (MPEG) standard. To this end, this dissertation will describe the following contributions and proofs-of-concept in the area of error concealment and correction in block-based video transmission. A temporal error concealment algorithm which uses motion-compensated macroblocks from previous frames. A spatial error concealment algorithm which uses the Hough transform to detect edges in both foreground and background colors and using directional interpolation or directional filtering to provide improved edge reproduction. A codec which uses data hiding to transmit error correction information. An enhanced codec which builds upon the last by improving the performance of the codec in the error-free environment while maintaining excellent error recovery capabilities. A method to allocate Reed-Solomon (R-S) packet-based forward error correction that will decrease distortion (using a PSNR metric) at the receiver compared to standard FEC techniques. Finally, under the constraints of a constant bit rate, the tradeoff between traditional R-S FEC and alternate forward concealment information (FCI) is evaluated. Each of these developments is compared and contrasted to state of the art techniques and are able to show improvements using widely accepted metrics. The dissertation concludes with a discussion of future work.
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Reimers, Stephen Paul. "Towards Internet Protocol over seawater (IP/SW) : forward error correction (FEC) using Hamming codes for reliable acoustic telemetry /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA306010.
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Norbraten, Terry D. "Utilization of forward error correction (FEC) techniques with extensible markup language (XML) schema-based binary compression (XSBC) technology." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FNorbraten.pdf.
Full textAbstract:
Thesis (M.S. in Modeling, Virtual Environments and Simulation (MOVES))--Naval Postgraduate School, December 2004.<br>Thesis advisor(s): Don Brutzman, Don McGregor. Includes bibliographical references (p. 165-169). Also available online.
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Fewer, Colm, and Sinbad Wilmot. "ENHANCING THE PCM/FM LINK - WITHOUT THE MATH." International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604575.
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, Nevada<br>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.
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Bisplinghoff, Andreas [Verfasser]. "Design of Efficient and Robust Forward Error Correction for Real-Time Application in Coherent Optical Communication Systems / Andreas Bisplinghoff." Aachen : Shaker, 2016. http://d-nb.info/1101184965/34.
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Tanonklin, Tippawan. "The cointegrating relationship in Asian markets with applications to stock prices, exchange rates and interest rates." Thesis, Brunel University, 2013. http://bura.brunel.ac.uk/handle/2438/7364.
Full textAbstract:
The aim of this research is to investigate the long-run co-integrating relationships in the Asian markets. Our research focuses on 4 areas; pair trading, out-of-sample forecasting, testing the unbiased forward exchange rate hypothesis and testing the expectation hypothesis of the term structure of interest rates. The introduction is provided in chapter one. In chapter two, we develop a pairs trading strategy using individual stocks listed in the Stock Exchange of Thailand. Engle and Granger approach is used to identify the potential pairs that are cointegrated. The results show that pairs trading strategy is profitable in this market. Chapter three examines the forecasting performance of the error correction model on daily share price series from the Stock Exchange of Thailand. The disequilibrium term is classified into “correct” and “mix” sign based on Alexander (2008)’s criterion; the results indicate that the error correction component can help to improve the predictability in the long run. Chapter four tests the unbiased forward rate hypothesis of 11 Asian exchange rates using linear conventional regression, ECM and logistic smooth transition regression with the forward premium as the transition variable. Out-of-sample forecasting results also suggest that inferior forecasting performance could be obtained as a result of using linear models. In chapter five, we investigate the expectation hypothesis of the term structure of interest rate for four Asian countries. We employ linear models and nonlinear approaches that allow to capture asymmetric and symmetric adjustments. The result also indicates that the term structure can be better modeled by means of LSTR models. The forecasting exercise also confirms these findings.
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Hill, Terry, and Jim Uetrecht. "SOQPSK with LDPC: Spending Bandwidth to Buy Link Margin." International Foundation for Telemetering, 2013. http://hdl.handle.net/10150/579588.
Full textAbstract:
ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV<br>Over the past decade, SOQPSK has been widely adopted by the flight test community, and the low density parity check (LDPC) codes are now in widespread use in many applications. This paper defines the waveform and presents the bit error rate (BER) performance of SOQPSK coupled with a rate 2/3 LDPC code. The scheme described here expands the transmission bandwidth by approximately 56% (which is still 22% less than the legacy PCM/FM modulation), for the benefit of improving link margin by over 10 dB at BER = 10⁻⁶.
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Horne, Lyman D., and Ricky G. Dye. "AN INEXPENSIVE DATA ACQUISITION SYSTEM FOR MEASURING TELEMETRY SIGNALS ON TEST RANGES TO ESTIMATE CHANNEL CHARACTERISTICS." International Foundation for Telemetering, 1995. http://hdl.handle.net/10150/608407.
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International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada<br>In an effort to determine a more accurate characterization of the multipath fading
effects on telemetry signals, the BYU telemetering group is implementing an
inexpensive data acquisition system to measure these effects.
It is designed to measure important signals in a diversity combining system. The
received RF envelope, AGC signal, and the weighting signal for each beam, as well as
the IRIG B time stamp will be sampled and stored.
This system is based on an 80x86 platform for simplicity, compactness, and ease of
use. The design is robust and portable to accommodate measurements in a variety of
locations including aircraft, ground, and mobile environments.
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Zahálka, Patrik. "Implementace vrstvy RS-FEC pro 400 Gb/s Ethernet." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413233.
Full textAbstract:
Tato diplomová práce se věnuje problematice VLSI návrhu a implementaci vrstvy RS-FEC pro 400 Gb/s Ethernet do FPGA Intel® Stratix® 10 DX 2100. V práci je charakterizován současný stav rychlostí Ethernetu, význam a kontext samoopravných kódů v rámci protokolu Ethernet. Dále je popsána výroba PLD čipů i matematická podstata RS sa moopravných kódů. V části praktické je představen návrh řešení systému RS-FEC, který byl realizován genericky pomocí jazyka VHDL. Zároveň byly jeho komponenty implementovány a v závěrečné diskusi je popsáno jeho řešení, dosažené výsledky včetně jeho budoucího rozšíření.
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Eshler, Todd Jacob. "Adaptive Protocols to Improve TCP/IP Performance in an LMDS Network using a Broadband Channel Sounder." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/42190.
Full textAbstract:
Virginia Tech researchers have developed a broadband channel sounder that can
measure channel quality while a wireless network is in operation. Channel measurements
from the broadband sounder hold the promise of improving TCP/IP performance by
trigging configuration changes in an adaptive data link layer protocol. We present an
adaptive data link layer protocol that can use different levels of forward error correction
(FEC) codes and link layer automatic retransmission request (ARQ) to improve network
and transport layer performance.<p>
Using a simulation model developed in OPNET, we determine the effects of
different data link layer protocol configurations on TCP/IP throughput and end-to-end
delay using a Rayleigh fading channel model. Switching to higher levels of FEC
encoding improves TCP/IP throughput for high bit error rates, but increases end-to-end
delay of TCP/IP segments. Overall TCP/IP connections with link layer ARQ showed
approximately 150 Kbps greater throughput than without ARQ, but lead to the highest
end-to-end delay for high bit error rate channels.<p>
Based on the simulation results, we propose algorithms to maximize TCP/IP
throughput and minimize end-to-end delay using the current bit error rate of the channel.
We propose a metric, carrier-to-interference ratio (CIR) that is calculated from data
retrieved from the broadband channel sounder. We propose algorithms using the carrier-to-interference ratio to control TCP/IP throughput and end-to-end delay.<p>
The thesis also describes a monitor program to use in the broadband wireless
system. The monitor program displays data collected from the broadband sounder and
controls the settings for the data link layer protocol and broadband sounder while the
network is in operation.<br>Master of Science
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Susanto, Misfa. "Network Coding for Multihop Wireless Networks: Joint Random Linear Network Coding and Forward Error Correction with Interleaving for Multihop Wireless Networks." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14864.
Full textAbstract:
Optimising the throughput performance for wireless networks is one of the challenging tasks in the objectives of communication engineering, since wireless channels are prone to errors due to path losses, random noise, and fading phenomena. The transmission errors will be worse in a multihop scenario due to its accumulative effects. Network Coding (NC) is an elegant technique to improve the throughput performance of a communication network. There is the fact that the bit error rates over one modulation symbol of 16- and higher order- Quadrature Amplitude Modulation (QAM) scheme follow a certain pattern. The Scattered Random Network Coding (SRNC) system was proposed in the literature to exploit the error pattern of 16-QAM by using bit-scattering to improve the throughput of multihop network to which is being applied the Random Linear Network Coding (RLNC). This thesis aims to improve further the SRNC system by using Forward Error Correction (FEC) code; the proposed system is called Joint RLNC and FEC with interleaving. The first proposed system (System-I) uses Convolutional Code (CC) FEC. The performances analysis of System-I with various CC rates of 1/2, 1/3, 1/4, 1/6, and 1/8 was carried out using the developed simulation tools in MATLAB and compared to two benchmark systems: SRNC system (System-II) and RLNC system (System- III). The second proposed system (System-IV) uses Reed-Solomon (RS) FEC code. Performance evaluation of System IV was carried out and compared to three systems; System-I with 1/2 CC rate, System-II, and System-III. All simulations were carried out over three possible channel environments: 1) AWGN channel, 2) a Rayleigh fading channel, and 3) a Rician fading channel, where both fading channels are in series with the AWGN channel. The simulation results show that the proposed system improves the SRNC system. How much improvement gain can be achieved depends on the FEC type used and the channel environment.
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Iltis, Ronald A. "Turbo Equalization for OFDM over the Doubly-Spread Channel using Nonlinear Programming." International Foundation for Telemetering, 2011. http://hdl.handle.net/10150/595779.
Full textAbstract:
ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada<br>OFDM has become the preferred modulation format for a wide range of wireless networks including 802.11g, 802.16e (WiMAX) and 4G LTE. For multipath channels which are time-invariant during an OFDM symbol duration, near-optimal demodulation is achieved using the FFT followed by scalar equalization. However, demodulating OFDM on the doubly-spread channel remains a challenging problem, as time-variations within a symbol generate intercarrier interference. Furthermore, demodulation and channel estimation must be effectively combined with decoding of the LDPC code in the 4G-type system considered here. This paper presents a new Turbo Equalization (TEQ) decoder, detector and channel estimator for OFDM on the doubly-spread channel based on nonlinear programming. We combine the Penalty Gradient Projection TEQ with a MMSE-type channel estimator (PGP-TEQ) that is shown to yield a convergent algorithm. Simulation results are presented comparing conventional MMSE TEQ using the Sum Product Algorithm (MMSE-SPA-TEQ) with the new PGP-TEQ for doubly-spread channels.
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Frei, Lukas. "The Markov-switching vector error correction model: dynamics, bayesian inference, and application to the spot and forward Swiss Franc, US Dollar exchange rates." Berlin dissertation.de, 2007. http://d-nb.info/989281892/04.
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Frei, Lukas. "The Markov-switching vector error correction model : dynamics, Bayesian inference, and application to the spot and forward Swiss franc/US dollar exchange rates /." Berlin : dissertation.de, 2008. http://www.dissertation.de/buch.php3?buch=5540.
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Lin, Jinsong, and Kamilo Feher. "BANDWIDTH EFFICIENCY AND BER PERFORMANCE OF ENHANCED AND FEC CODED FQPSK." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/607727.
Full textAbstract:
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California<br>Bit error rate (BER) and bandwidth efficiency of several variations of enhanced Feher patented quadrature phase shift keying (FQPSK) [1] are described. An enhanced FQPSK increases the channel packing density of that of the IRIG 106-00 standardized FQPSK-B by approximately 50% in adjacent channel interference (ACI) environment. As the bandwidth efficiency of FQPSK-B DOUBLES (2×) that of pulse code modulation/Frequency modulation (PCM/FM) [5], the enhanced FQPSK, with a simpler transceiver than FQPSK-B, has a channel packing density of TRIPLE (3×) that of PCM/FM. One of the other enhanced FQPSK prototypes has an end to end system loss of only 0.4 dB at BER=1x10^(-3) and 0.5 dB at BER=1x10^(-4) from ideal linearly amplified QPSK theory. The enhanced FQPSK has a simple architecture, thus is inexpensive and has small size, for ultra high bit rate implementation. With low redundancy forward error correction (FEC) coding which expands the spectrum by approximately 10%, further improvement of about 3-4.5dB E N b o is attained with NLA FQPSK-B and enhanced FQPSK at BER=1x10^(-5) .
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Mumtaz, Sami. "Nouvelles techniques de codage pour les communications optiques à haut-débit." Paris, Télécom ParisTech, 2011. https://pastel.hal.science/pastel-00679068.
Full textAbstract:
Depuis le développement de l’électronique à très hauts débits, les techniques de traitement du signal ont pris une part essentielle dans les systèmes de communications optiques. Dans cette thèse nous nous intéressons principalement aux techniques de codage du signal. Nous présentons trois nouveaux procédés qui permettent d’améliorer grandement les performances et la complexité des systèmes de transmission optiques à hauts débits. Les techniques proposées couvrent plusieurs domaines : les codes correcteur d’erreur, l’entrelacement des données et le codage espace-temps. Le codage correcteur d’erreurs est utilisé depuis des dizaines d’années dans les systèmes optiques pour assurer des taux d’erreurs extrêmement bas. Les promesses faites par le développement de l’électronique permettent d’envisager une implémentation prochaine de codes de dernière génération, les codes LDPC. Nous proposons une nouvelle construction de code LDPC qui obtient des performances optimales en comparaison aux autres constructions proposées dans la littérature. Dans un second temps, nous présentons une nouvelle technique d’entrelacement qui en générant une structure de donnée très particulière, permet d’améliorer les performances et surtout de réduire très fortement la complexité du décodage des systèmes optiques utilisant un encodage différentiel. Pour finir nous présentons une nouvelle technique de codage basé sur les codes espace-temps. Nous montrons que cette technique permet de lutter très efficacement contre les pertes dépendantes de la polarisation<br>Since the development of high-speed electronics, digital signal processing has become essential to optical transmission systems. In particular, equalization now allows compensating signal distortions resulting from the propagation in the fiber. In this thesis, we focus on another type of signal processing: the coding techniques. We present three new ideas in order to improve systems performance by reducing either the bit-error rate or the receiver complexity. Forward-error correction has been used for many years in optical transmission systems in order to guarantee very low bit-error rates. With the increase of transmission bit rates, more powerful codes are expected such as low-density parity check (LDPC) codes. We study this new family of codes and show its impressive performance. We also propose a new construction of LDPC code that has optimal performance in comparison to codes proposed in the literature. Then we present a new interleaving scheme for optical transmission systems using differential encoding. Our technique leads to performance improvement and allows a large complexity reduction of the receiver. Finally we present a new coding technique for optical systems, based on space-time coding. We show that polarization dependent loss can be almost entirely suppressed in transmissions systems using polarization division multiplexing