Dissertations / Theses on the topic 'Lossy forward'

Abstract In the current LTE-Advanced system, decode-and-forward (DF) is leveraged for cooperative relaying, where the erroneously decoded sequences are discarded at the relay, resulting in a waste of resources. The reason lies in that the erroneously decoded sequence can provide a certain amount of useful information about the source at the destination. Therefore, we develop a new relaying scheme, called lossy DF (also known as lossy forward (LF)), where the relay always forwards the decoded sequence to the destination. Beneficial from the always-forward principle, it has been verified that LF relaying outperforms DF relaying in terms of outage probability, ε-outage achievable rate, frame error rate (FER), and communication coverage. Three exemplifying network scenarios are studied in this thesis: the one-way multiple-input multiple-output (MIMO) relay network, the multiple access relay channel (MARC), and the general multi-source multi-relay network. We derive the outage probability of the one-way MIMO relay networks under the assumption that the orthogonal space-time block code (OSTBC) is implemented at the transmitter side for each individual transmission. Interestingly, we find that the diversity order of the OSTBC based one-way MIMO relay network can be interpreted and formulated by the well-known max-flow min-cut theorem, which is widely utilized to calculate the network capacity. For the MARC, non-orthogonal transmission is introduced to further improve the network throughput compared to its orthogonal counterpart. The region for lossless recovery of both sources is formulated by the theorem of multiple access channel (MAC) with a helper, which combines the Slepian-Wolf rate region and the MAC capacity region. Since the region for lossless recovery is obtained via sufficient condition, the derived outage probability can be regarded as a theoretical upper bound. We also conduct the performance evaluation by exploiting different accumulator (ACC) aided turbo codes at the transmitter side, exclusive or (XOR) based multi-user complete decoding at the relay, and iterative joint decoding (JD) at the destination. For the general multi-source multi-relay network, we focus on the investigation the end-to-end outage probability. The performance improvement of LF over DF is verified through theoretical analyses and numerical results in terms of outage probability
Tiivistelmä Tämän päivän LTE-A-tiedonsiirtojärjestelmissä hyödynnetään dekoodaa-ja-välitä (decode-and-forward, DF) menetelmää yhteistoiminnalliseen tiedon edelleenlähetykseen (relaying) siten, että virheellisesti vastaanotetut sekvenssit hylätään välittimessä (relay). Tämä on resurssien hukkaamista, sillä virheellisissäkin viesteissä on informaatiota, jota voidaan hyödyntää vastaanottimessa. Tässä väitöskirjassa tutkitaan uutta häviöllistä DF-menetelmää, johon viitataan nimellä häviöllinen välitys (lossy forward, LF). Menetelmässä välitin lähettää informaation aina eteenpäin olipa siinä virheitä tai ei. Sen etuna verrattuna perinteiseen DF-menetelmään, on parantunut luotettavuus metriikoilla jossa mitataan vastaanoton todennäköisyyttä ja verkon peittoaluetta. Väitöskirjassa tarkastellaan LF-menetelmää kolmessa eri verkkotopologiassa jotka ovat yksisuuntainen monitulo-monilähtövälitinverkko (multiple-input multiple-output, MIMO), moniliityntävälitinkanava (multiple access relay channel, MARC), sekä yleinen moniläheinen monivälitinverkko. Työssä johdetaan matemaattinen esitys estotilan todennäköisyydelle (outage probability) yksisuuntaisessa MIMO-välitinverkossa olettaen ortogonaalisen tila-aika lohkokoodin (orthogonal space-time block code, OSTBC) käyttö. Estotilan todennäköisyys esitetään käyttäen toisteastta (diversity order), joka saadaan johdettua tunnetusta max-flow min-cut lauseesta, jota puolestaan käytetään yleisesti erilaisten verkkojen kapasiteettien laskentaan. MARC-topologiassa hyödynnetään ei-ortogonaalista lähetystä verkon datavirran kasvattamiseen. Häviöttömän lähetyksen informaatioteoreettinen kapasiteettialue saadaan johdettua MAC-auttajan kanssa. Lähestymistavassa Slepian-Wolf- sekä MAC-kapasiteettialueet yhdistyvät. Alueelle, jossa kahden lähteen lähetysnopeudet ovat sellaiset, että vastaanotto on häviötöntä, annetaan riittävä ehto, jolloin johdettu estotilan todennäköisyys on teoreettinen yläraja. Suorituskykyä evaluoidaan myös tietokonesimulaatioilla, joissa käytetään erilaisia akkumulaattoriavusteisia turbokoodeja lähettimessä, ehdoton tai (exclusive or, XOR) pohjaista monen käyttäjän dekoodausta välittimessä sekä iteratiivista yhteisdekoodausta vastaanottimessa. Yleisessä monilähteisessä monivälitinverkossa keskitytään alkuperäisen lähetyksen estotilatodennäköisyyteen. Teoreettinen analyysi sekä simulaatiot osoittavat, että LF:n estotilan todennäköisyys on pienempi kuin DF:n

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.

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.

Abstract The goal of this thesis is to provide a unified concept of lossy-forwarding from the theoretical analysis to practical scheme design for the decode-and-forward-based multiple access relay channel (MARC) system. To improve the performance of MARC with the relay subject to resources or/and time constraints, the erroneous estimates output from simple detection schemes are used at the relay are forwarded and exploited. A correlation is then found between two sequences: one is the network-coded sequence sent from the relay, and the other is their corresponding exclusive-OR-ed information sequence. Several joint network-channel coding (JNCC) techniques are provided in which the correlation is utilized to update the log-likelihood ratio sequences during the iterative decoding process at the destination. As a result, the bit error rate (BER) and frame error rate (FER) are improved compared with those of MARC with select DF strategy (SDF-MARC). The MARC proposed above is referred to as erroneous estimates-exploiting MARC (e-MARC). To investigate the achieved FER performance of the e-MARC system, the outage probability for e-MARC with two source nodes is theoretically derived. We re-formulate the e-MARC system and identify its admissible rate region according to the Slepian-Wolf theorem with a helper. Then, the outage probability is obtained by a set of integral over the rate region with respect to the probability density functions of all the links' instantaneous signal-to-noise power ratios. It is found through simulations that, as one of the source nodes is far away from both the relay and destination, e-MARC is superior to SDF-MARC in terms of outage performance. Furthermore, a joint adaptive network-channel coding (JANCC) technique is then proposed to support e-MARC with more source nodes. A vector is constructed at the destination in JANCC to identify the indices of the incorrectly decoded source node(s), and re-transmitted to the relay for requesting additional redundancy. The relay performs network-coding only over the estimates specified by the vector upon receiving the request. Numerical results show that JANCC-aided e-MARC is superior to e-MARC in terms of FER and goodput efficiency. In addition, compared iterative decoding is performed at relay with SDF-MARC, the use of differential detection with JANCC-aided e-MARC significantly reduces the computational complexity and latency with only a small loss in the FER
Tiivistelmä Tämän väitöskirjan tarkoituksena on tuottaa yhtenäinen kokonaisuus häviöllisestä lähetyksestä pura-ja-lähetä (DF) -pohjaisessa monikäyttörelejärjestelmässä (MARC) sekä teoreettisesta että käytännöllisestä näkökulmasta. Parantaakseen resurssi- tai aikarajoitetun MARC-järjestelmän suorituskykyä, vastaanotin hyödyntää riippuvuussuhdetta releen välittämien informaatiosekvenssien virheellisten estimaattien ja suoraan lähteestä tulevien informaatiosekvenssien välillä (e-MARC). Työssä ehdotetaan useita yhdistetyn verkko -ja kanavakoodauksen menetelmiä (JNCC), joissa log-uskottavuussuhdesekvenssit iteratiivisen purkamisprosessin aikana päivitetään hyödyntämällä sekvenssien riippuvuussuhdetta vastaanottimessa. Tämän tuloksena sekä bittivirhe- että kehysvirhesuhdetta saadaan parannettua verrattuna selektiiviseen pura-ja-lähetä menetelmää käyttävään MARC-strategiaan (SDF-MARC). Kehysvirheen suorituskyvyn tarkastelua varten työssä johdetaan teoreettinen epäkäytettävyyden todennäköisyys e-MARC-menetelmälle kahden lähettimen tapauksessa. Lisäksi e-MARC-menetelmälle määritetään tiedonsiirtonopeusalue Slepian-Wolf -teoreeman mukaisesti. Tämän jälkeen saadaan epäkäytettävyyden todennäköisyys kaikkien linkkien signaalikohinasuhteen todennäköisyystiheysfunktion integraalina tiedonsiirtonopeusalueen yli. Simulointitulokset osoittavat e-MARC-menetelmän paremman epäkäytettävyyden todennäköisyyden verrattuna SDF-MARC-menetelmään silloin kun yksi lähettimistä on kaukana sekä releestä että vastaanottimesta. Mahdollistaakseen useamman lähteen käytön e-MARC-menetelmässä, työssä ehdotetaan lisäksi adaptiivinen yhdistetyn verkko-ja kanavakoodauksen menetelmä (JANCC). Siinä vastaanotin määrittää väärin purettujen sekvenssien lähettimet ja ilmoittaa ne vektorimuodossa takaisin releelle pyytääkseen näiden lähettimien informaation uudelleenlähetystä. Tämän jälkeen rele suorittaa verkkokoodauksen vain tunnistusvektorin määrittämien informaatiosekvenssien estimaatteihin perustuen. Tulokset näyttävät, että JANCC-menetelmää käyttävä e-MARC saavuttaa paremman kehysvirheen ja hyödyllisen läpäisyn tehokkuuden verrattuna e-MARC-menetelmään

Thesis (Ph. D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 1993.
Copies of author's previously published articles inserted. Includes bibliographical references (leaves 179-186).

In previous research, aggregation of returns has been found as a way to counteract the risk averse behavior that is the result of investors' myopia. This paper expands the study of aggregation by analyzing its effect on forward looking probabilities. Namely, through the disaggregation of future information, subjects become myopic and trade with varying risk preferences. In an experimental market, subjects trading securities with disaggregated forward looking information are found to 'buy high and sell low', while subjects trading the same securities, but with aggregated information, trade with more consistent risk preferences.

In today’s world economy, many companies produce where it is most cost effective to produce goods, sell where it is most profitable and source capital where it is cheaper than anywhere else, without worrying about national boundaries. However, this stage were the world has reached began three decades ago with the freeing of exchange rate, capital and interest rate controls. Additional business risks have arisen as a result of this free world and they are such that interest and exchange rates have become more variable requiring innovative financial products to help companies manage these business risks. Companies can now buy financial derivatives to help manage their exposure to variable exchange rates. As such it was the purpose of this paper to assess the effectiveness of exchange traded currency futures contracts in managing exposure to exchange rates. This was to be achieved through answering two research questions (1) how successful are exchange traded futures derivatives and (2) what is the significance of these success rates. The study established that futures contracts with maturity in three, six and nine-months have 52%, 72% and 45% success rates respectively and however only the three month success rate was confirmed by hypothesis tests.

Master´s thesis deals with possibilities of exchange rates risk reduction in the company FLÍDR, s.r.o. Exchange rate volatility has begun to be a serious problem of many business entities. Unfortunately, the Czech Republic will not join Economic and Monetary Union of the European Union for longer time. The outcome of Master´s thesis is the suggestion of utilization of financial derivatives and proposal of new financial derivatives. Proposed financial derivatives are composed to minimize exchange rate risk in the company FLÍDR, s.r.o., and to minimize losses caused by exchange rate volatility of Euro currency.

Vad gäller reglerna om tidigare års underskott utgör koncernbidragsspärren en spärregel till den annars gällande huvudregeln att tidigare års förluster får kvittas mot framtida vinster. Koncernbidragsspärren inträder vid ägarförändringar och innebär förenklat att ett underskottsföretag är förhindrat att, under en period om fem år, kvitta kvarstående underskott mot koncernbidrag som underskottsföretaget mottar från företag som inte ingick i koncernen före ägarförändringen (nya företag). Underskott som uppkommer efter ägarförändringen får dock kvittas mot koncernbidrag från nya företag. Uppsatsen syftar till att analysera och granska reglerna om koncernbidragsspärren ur ett företagsperspektiv, vilket innebär att uppsatsen ser till reglernas bakomliggande syfte och till hur reglerna fungerar vid en praktisk tillämpning. Uppsatsen har ett särskilt fokus kring i vilken turordning koncernbidrag ska beaktas vid avräkning mot befintliga underskott när ett underskottsföretag mottar koncernbidrag både från gamla och nya företag i en koncern. I RÅ 2008 ref. 69 ställdes frågan på sin spets och Högsta Förvaltningsdomstolen befäste en ny turordningsprincip där koncernbidrag från gamla företag ska beaktas före koncernbidrag från nya företag i koncernen. Det har genom uppsatsens analys av reglerna om koncernbidragsspärren påvisats att reglerna är svåra att tillämpa och i många fall råder det osäkerhet om hur reglerna ska tolkas. Det kan konstateras att problematik kvarstår avseende frågan om i vilken turordning koncernbidrag från så kallade gamla respektive nya företag ska beaktas vid avräkning mot befintliga underskott även efter RÅ 2008 ref. 69. En rådande osäkerhet om hur reglerna ska tolkas kan inte anses tillfredsställande ur ett företagsperspektiv och en översyn av reglerna vore välkommen.
According to the Swedish legislation tax losses can normally be carried forward and settled against future profits in the same company unlimited of time. However, a restriction of losses being carried forward may occur in situations where change of ownership is at hand. The restrictive rule prohibits offsetting tax losses in an acquired loss-making company against group contributions received from other group companies. The restrictive rule applies up until, and including, the end of the fifth year after the year when the restriction occurred. However, losses that occur after the change of ownership are possible to offset against group contributions from other group companies. The thesis aims to analyze and review the restrictive rule from a business perspective which means that the underlying purpose of the restrictive rule and how it works in practice is examined. The thesis has a particular focus on in what order group contributions should be considered when being offset against existing deficits when the deficit company receives group contributions from old and new companies in the corporate group. In the Swedish case law RÅ 2008 ref. 69 the Supreme Administrative Court laid down a new principle of order where group contributions from an old company should be regarded before a group contribution from a new company. Through the analysis of the restrictive rule it has been demonstrated that the rule is difficult to conform to and that there is an uncertainty regarding the interpretation of it. Through the analysis of this thesis it is established that, even after RÅ 2008 ref. 69, the complexity of problems remains concerning in what order group contributions from old respectively new companies should be considered when being offset against existing deficits. A such prescribed uncertainty regarding the interpretation of the restrictive rule cannot be considered satisfactory from a business perspective and a review of the rules would be preferable.

博士
國立成功大學
電腦與通信工程研究所
103
Unequal error protection systems are a popular technique for video streaming. Forward error correction (FEC) is one of error control techniques to improve the quality of video streaming over lossy channels. Moreover, frame-level FEC techniques have been proposed for video streaming due to different priority video frames within the transmission rate constraint on a Bernoulli channel. However, various communication and storage systems are likely corrupted by bursts of noise in the current wireless behavior. If the burst losses go beyond the protection capacity of FEC, the efficacy of FEC can be degraded. Therefore, our proposed model allows an assessment of the perceived quality of H.264/AVC video streaming over a bursty channel, and was validated by simulation experiments on the NS-2 network simulator at a given estimate of the packet loss ratio and average burst length. The results suggest a useful reference in designing the FEC scheme for video applications, and as the video coding and channel parameters are given, the proposed model can provide a more accurate evaluation tool for video streaming over bursty channels and help to evaluate the impact of FEC performance on different burst-loss parameters.

碩士
東吳大學
財務工程與精算數學系
104
By the internationalization of the RMB, the exchange rate of USD against RMB fluctuates bilaterally, the RMB no longer unilaterally appreciates as before. The domestic manufacturer who bet on the appreciation of RMB, and purchase the RMB-related derivatives such as target redeemable forward contracts (TRF) therefore suffers. This paper investigates the TRF issued by the E-SUN bank in Taiwan, and employing the Monte Carlo simulation for the valuation and risk analysis of TRF. Also this paper uses regression for analyzing the sensitivity of the value and VaR (value at risk) of TRF to key parameters. This paper finds that the value of TRF with stop-loss mechanism is higher than that of TRF without stop-loss mechanism, moreover, the VaR of TRF with stop-loss mechanism is lower than that of TRF without stop-loss mechanism. Keywords: Barrier option, Monte Carlo simulation, Structured Note, Value at Risk, Target Redemption Forward.

碩士
東吳大學
財務工程與精算數學系
104
As the RMB depreciates recently, many investors suffers from the purchase of target redeemable forward contracts (TRF). This paper investigates the TRF issued by the Bank SinoPac in Taiwan, and employing the Monte Carlo simulation for the pricing and risk analysis of TRF. Also this paper uses regression for analyzing the sensitivity of the value and VaR (value at risk) of TRF to key parameters. This paper also considers the impacts of stop-loss condition to the pricing and risk of TRF. This paper finds that the price of TRF with stop-loss condition is higher than that of TRF without stop-loss condition, on the other hand, the VaR of TRF with stop-loss condition is lower than that of TRF without stop-loss condition. This paper also finds that many parameters influence the price and VaR of TRF significantly. Keywords: Monte Carlo simulation, Structured Note, Value at Risk, Target Redemption Forward.

Multimedia applications over the Internet are getting more and more popular. While non-real-time streaming services, such as YouTube and Megavideo, are attracting millions of visiting per day, real-time conferencing applications, of which some instances are Skype and Yahoo Voice Chat, provide an interesting experience of communication. Together, they make the fancy Internet world become more and more amusing. Undoubtedly, multimedia flows will eventually dominate the computer network in the future. As the population of multimedia flows increases gradually on the Internet, quality of their service (QoS) is more of a concern. At the moment, the Internet does not have any guarantee on the quality of multimedia services. To completely surpass this limitation, modifications to the network structure is a must. However, it will take years and billions of dollars in investment to achieve this goal. Meanwhile, it is essential to find alternative ways to improve the quality of multimedia services over the Internet. In the past few years, many endeavors have been carried on to solve the problem. One interesting approach focuses on the development of end-to-end congestion control strategies for UDP multimedia flows. Traditionally, packet losses and delays have been commonly used to develop many known control schemes. Each of them only characterizes some different aspects of network congestion; hence, they are not ideal as feedback signals alone. In this research, the flow accumulation is the signal used in feedback for flow control. It has the advantage of reflecting both packet losses and delays; therefore, it is a better choice. Using network simulations, the accumulations of real-time audio applications are collected to construct adaptive flow controllers. The reason for choosing these applications is that they introduce more control challenges than non-real-time services. One promising flow control strategy was proposed by Bhattacharya and it was based on Model Predictive Control (MPC). The controller was constructed from an ARX predictor. It was demonstrated that this control scheme delivers a good QoS while reducing bandwidth use in the controlled flows by 31 percent to 44 percent. However, the controller sometime shows erratic response and bandwidth usage jumps frequently between lowest and highest values. This is not desirable. For an ideal controller, the controlled bandwidth should vary near its mean. To eliminate the deficiency in the strategy proposed by Bhattacharya, it is proposed to introduce a feed forward term into the MPC formulation, in addition to the feedback terms. Simulations show that the modified MPC strategy maintains the benefits of the Bhattacharya strategy. Furthermore, it increases the probability of bandwidth savings from 58 percent for the case of Bhattacharya model to about 99 percent for this work.

碩士
淡江大學
電機工程學系碩士班
102
As the Internet grows, Wireless Fidelity (Wi-Fi) has become more and more popular after the upgrades of transmission rate and transmission volume, which is attracting more network researchers in the study of high-quality video transmission. Meanwhile, more Internet users choose to connect to Internet services with mobile devices, like Tablets PCs and Smartphones. Of the many Internet services, video streaming is a frequently used Internet service. The appearance of MPEG-4 has made video streaming transmission become easier, which is the first video streaming protocol that includes network abstraction layer in it. The transmission of live streaming video has become better thanks to MPEG-4’s good network adaptability and its great fault tolerance on packet loses. However, there are still many unsolved problems such as packet loss and burst packet error.Forward Error Correction (FEC) is a common technology to protect data loss by redundant packets. Today there are various kinds of FEC to explore how to adaptively adjust the redundant packet amount and make adequate redundant packet overcome source error and loss. Both block size and packet size would affect the screening rate of source error and loss. When block size is small then the screening rate, it would be better than the case that block size is large; The impact on the quality of video streaming is greater when smaller packets are used. In this paper, we study the packet loss impact on the transmission quality of MPEG transmission with FEC in wireless networks. We are not only to consider the impacts in distributed packet loss, but also to study the impact in burst packet loss, which would affect the video transmission quality. Finally, we propose a new scheme called “Dynamically Adjust Block Size and Block Size (DABSPS)”. DABSPS adjusted the transmission packet size according to the wireless network environment, which reduced the impact on video quality and FEC packet screening error rate.

碩士
淡江大學
國際企業學系碩士在職專班
100
This study focused on the present situation and future development of the non-life insurance industry that how they used the technical service to control the losses caused by a natural disaster of the climatic changed and to achieve the regional developing strategies through this advantage. In this paper, non-life insurance company F as a case study to Lin and Pao (2004) theoretical framework for analysis of non-life insurance company F of competitive strategy to form element, it uses the 7S Model to analyze the internal environment. Furthermore, it uses Five Forces Model to make industrial environmental assessment. Lastly, it uses PESTEL to analyze and evaluate their macro environment. Based on all the above analyses, the frame of this research is built; the key factors in industrial competitive strategy formation are summed up, and these provide references to the remedial non-life insurance industry, this study summarizes the conclusion as below: 1.The F Company is a good example that providing additional loss control analysis for clients to maintain the highly level of profits that help for the regional developing strategy. 2.Under the mission statement of the Company F, “Become the First-class Non-life Insurance Company in Asia.” After the institution forms the best competitive strategy, it is appropriate to make the promotion of the Regional Development Strategy by Loss Control its specific strategy.