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1
Shengxi, Ding, Zhang Qishan, Li Junfeng e Zheng Dayi. "HOW TO USE RBDS TO TRANSMIT DGPS CORRECTION MESSAGE". International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/608250.
Testo completoAbstract (sommario):
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaThis paper introduces the frequency spectrum characteristic of FM radio broadcast and the message format of RBDS (Radio Broadcast Data System). DGPS correction message in RBDS is described in detail. A design method of RBDS/DGPS system is proposed and the RBDS/DGPS system developed by us is introduced. Finally, some special advantages of RBDS/DGPS system are given.
2
Araujo, João Paulo de. "A communication-efficient causal broadcast publish/subscribe system". Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS081.
Testo completoAbstract (sommario):
La Publication/Abonnement (Publish/Subscribe, Pub/Sub) est un paradigme qui permet aux nœuds d'un système distribué de diffuser des informations de manière asynchrone. Cette thèse s'intéresse aux systèmes de Pub/Sub basés sur des sujets (topic-based), en adressant les problèmes de performances et de contention existant dans plusieurs approches reposant sur des arbres. Les solutions proposées utilisent la construction d'arbres couvrants regroupant les abonnés et dont les racines sont les émetteurs. Les arbres associés à différentes sources sont organisés différemment. La première contribution de la thèse propose un protocole de diffusion causal agrégeant des messages et dans lequel aucun temporisateur n'est nécessaire. Le protocole regroupe les messages en un seul message sans utiliser des temporisateurs en tirant parti du délai de livraison supplémentaire imposé à un nœud lorsque les messages sont reçus en dehors de l'ordre causal ainsi que des intersections existantes entre des arbres couvrants. La deuxième contribution est un système de Pub/Sub par sujet, VCube-PS, qui assure l'ordre de traitement causal des messages publiés sur un même sujet et gère efficacement la publication de messages sur des sujets très populaires ("hot topics"). Les résultats des simulations confirment que le protocole d'agrégation causale proposé réduit le trafic réseau ainsi que des latences de livraison, en limitant la contention de messages. Comparé à une approche utilisant un seul arbre par sujet, VCube-PS repartit mieux la charge lors de publications massives sur des "hot topic"The Publish/Subscribe (Pub/Sub) paradigm enables nodes of a distributed system to disseminate information asynchronously. This thesis investigates how to provide a communication-efficient topic-based Pub/Sub system by addressing the problems of traffic overhead and message contention, present in several tree-based solutions. The proposed contributions build distributed spanning trees on top of a hypercube-like topology, such that the source of each message is the root of its own dynamically built spanning tree. Trees rooted at different nodes are differently organized. Initially, it is proposed a causal broadcast protocol which reduces network traffic by aggregating messages without the use of timers. It exploits the causal relation between messages and path intersections between different trees. Different from existing timer-based approaches, it does not increase delivery latency. The second contribution is a topic-based Pub/Sub system, VCube-PS, which ensures causal delivery order for messages published to the same topic and efficiently supports publication of messages to "hot topics'', i.e., topics with high publication rates. Simulation results confirm that the proposed causal aggregation protocol reduces network traffic as well as delivery latencies since there is less message contention. Compared to an approach that uses one single tree per topic, VCube-PS performs better when there is a high publication rate per topic since it provides load balancing of publication
3
Axelsson, Karin, e Cynthia Novak. "Support for Cell Broadcast as Global Emergency Alert System". Thesis, Linköping University, Department of Science and Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-9491.
Testo completoAbstract (sommario):
Cell Broadcast (CB) is a possible technical realisation of a global emergency alert system. It is a technique used for sending short text messages to all mobile stations (MSs) in a defined geographical area. An potential effect of using CB is the increase in battery consumption of the MS due to the fact that an extra channel has to be used to make the service available even when the network is otherwise congested. Another part of the service which leads to a potential problem is making CB messages available in different languages. Investigating these problems is the objective of this thesis and the studies it includes. During the first part of the thesis, we measured the battery consumption of MSs in different modes of operation in order to analyse how CB affects the amount of current drained. The tests showed that battery consumption increased only slightly when CB messages were being received at the MS. Although some of the results can be, and are, discussed, we believe that CB would have a small effect on the power consumption of an MS, particularly in a context where it would be used for emergency warning messages only. This mentioned, it would however be wishful to confirm the conclusions further through the realisation of long-term testing. The second part of the thesis deals with the investigation of the MSs’ support for CB messages with different coding schemes. Based on the investigation’s result, we have come to the conclusion that in the long term the usage of different coding schemes on the same channel is preferred. However, the usage of one, global, emergency channel is hard to realise since that requires a standardisation between all countries. In our opinion this may be achieved first in the long run and until then, the usage of separate channels seems to be necessary.
4
Brentzel, Kelvin, Carol Harris e Patrick Coronado. "NPP IN-SITU GROUND SYSTEM - BRIDGING TECHNOLOGIES BETWEEN EOS, NPP AND THE FUTURE". International Foundation for Telemetering, 2003. http://hdl.handle.net/10150/605585.
Testo completoAbstract (sommario):
International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, NevadaAs part of the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP), the Direct Readout Laboratory (DRL) of NASA/GSFC Code 935, is developing the prototype NPP In-Situ Ground System (NISGS). The NISGS supports earth remote sensing, and its functions bridge from all EOS satellites to planning for future NASA and interagency launches. The NISGS solution enables the end user to acquire and process NPP and predecessor instrument data, and provide a means to make these technologies and data products available to the Direct Broadcast Community. This document describes the NISGS model, methodology, and system architecture.
5
Yang, Yao-Bang Steven. "Interface and performance analysis of a local area differential GPS VHF navigation augmentation broadcast system". Ohio University / OhioLINK, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1184616378.
Testo completo
6
Sun, Frank X. B. "Value added middleware for converged digital broadcast and telecommunication system". Thesis, Brunel University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426232.
Testo completo
7
Shirazi, Hamidreza. "Cooperating broadcast and cellular conditional access system for digital television". Thesis, Brunel University, 2009. http://bura.brunel.ac.uk/handle/2438/3758.
Testo completoAbstract (sommario):
The lack of interoperability between Pay‐TV service providers and a horizontally integrated business transaction model have compromised the competition in the Pay‐TV market. In addition, the lack of interactivity with customers has resulted in high churn rate and improper security measures have contributed into considerable business loss. These issues are the main cause of high operational costs and subscription fees in the Pay‐TV systems. This paper presents a novel end‐to‐end system architecture for Pay‐TV systems cooperating mobile and broadcasting technologies. It provides a cost‐effective, scalable, dynamic and secure access control mechanism supporting converged services and new business opportunities in Pay‐TV systems. It enhances interactivity, security and potentially reduces customer attrition and operational cost. In this platform, service providers can effectively interact with their customers, personalise their services and adopt appropriate security measures. It breaks up the rigid relationship between a viewer and set‐top box as imposed by traditional conditional access systems, thus, a viewer can fully enjoy his entitlements via an arbitrary set‐top box. Having thoroughly considered state‐of‐the‐art technologies currently being used across the world, the thesis highlights novel use cases and presents the full design and implementation aspects of the system. The design section is enriched by providing possible security structures supported thereby. A business collaboration structure is proposed, followed by a reference model for implementing the system. Finally, the security architectures are analysed to propose the best architecture on the basis of security, complexity and set‐top box production cost criteria.
8
Hon, Kenneth Sau-yee 1977. "Design of a real-time broadcast system over the internet". Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/46185.
Testo completoAbstract (sommario):
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science; and, Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (leaves 100-102).
by Kenneth Sau-yee Hon.
B.S.
M.Eng.
9
Mirchandani, Chandru, David Fisher, Kelvin Brentzel, Patrick Coronado e Carol Harris. "HIGH RATE DATA BROADCAST SYSTEM FOR NPP IN-SITU APPLICATIONS". International Foundation for Telemetering, 2003. http://hdl.handle.net/10150/605345.
Testo completoAbstract (sommario):
International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, NevadaA vital part of all satellite development is the ground system that will be used to process the satellite downlink. To support the High-Rate Data (HRD) Downlink satellites planned for launch by the NPOESS Preparatory Project (NPP), GSFC has developed a Single Chassis System (SCS) solution, which provides data processing from RF to data product using leading-edge hardware components. The SCS is a hardware solution that meets and exceeds this rate requirement. In realtime, the SCS autonomously processes and delivers Direct Broadcast data from NPP satellites. An objective of the HRD System development was that it be an integrated processing element housed in a single commercial off-the-shelf PC capable of exceeding the near-term requirements of NPP and moving towards the mid and far term needs of NASA.
10
Suwannarath, Songluk. "The TESLA-alpha broadcast authentication protocol for building automation system". Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10111196.
Testo completoAbstract (sommario):
Wireless sensor networks experience an increase of attacks in networks in term of security. However, broadcast communication is an essential algorithm that provides a great benefit for large scale communications, especially in Building Automation System (BAS). Embedding the security in this area becomes the top priority for every industry. TESLA protocol is an algorithm that verifies and authenticates senders and has low overhead and a robust authentication mechanism. The appeal of TESLA motivates us to apply this protocol into a hierarchical wireless network architecture for BAS that has a high flexibility for formation networks. To combine these two architectures we implement the knowledge of zero knowledge protocol and a session key cryptography into the formation phase, and modify packets that were used in this phase to make TESLA-alpha protocol compatible with BAS.
11
Sörman, Simon. "System Information Distribution in Massive MIMO Systems". Thesis, Linköpings universitet, Kommunikationssystem, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-129294.
Testo completoAbstract (sommario):
The 5th generation mobile telecommunication system (5G) is currently being specified and developed, with large expectations on throughput and efficiency. While 4G and more specifically LTE might constitute a basis of the design of the network, there are some parts that should be improved. One thing to improve is the static signalling that occurs very frequently in a 4G network, of which system information such as synchronization signals, detection of network frequencies, operators, configurations etc. is a part. It has been shown that the static signalling requires both much energy and time-frequency resources. Since the system information is not intended for a single user it is always broadcast so that any user, and any amount of users can read it when needed. 5G will use a technique called massive MIMO, where the base station is equipped with a large number of antennas which can be used to direct signals in space, called beamforming. This thesis presents a new method for distribution of system information that can utilize the beamforming capabilities of massive MIMO. A simple model together with simulated user channel statistics from urban 4G scenarios are used to show that the new method outperforms the classical method of only broadcasting the information, with respect to time-frequency resources. Especially if there are high requirements on the latency of the system information, the new method results in a large gain.
12
Shende, Sandeep Subhash. "A MATLAB-based FM demodulator for the radio broadcast data system". [Boise, Idaho] : Boise State University, 2010. http://scholarworks.boisestate.edu/td/85/.
Testo completo
13
Solomon, Bruce Allen. "System analysis using automatic dependent surveillance broadcast (ABS-B) for closely spaced parallel approaches". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9758.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, System Design and Management Program, 1999.Includes bibliographical references (leaves 70-72).
The United States National Airspace System (NAS) is undergoing evolutionary changes in response to growing air traffic demands and aging equipment. In 1981 the Federal Aviation Administration initiated a modernization program to modernize, automate, and consolidate the existing ATC system by the year 2000. This effort is ongoing and will continue well into the 21st century. Improving capacity is one goal of the modernization program. Closely spaced parallel approaches are used at many of the busiest airports to increase capacity. During visual flight conditions parallel runways operate independently at maximum capacity. During non-visual meteorological conditions operating procedures are modified to assure safe operations. Capacity reductions of 50% may occur depending on the runway spacing. New communication, navigation, and surveillance technologies are being developed that offer the potential of improved capacity by enabling closely spaced parallel approaches during non-visual conditions. An analysis was conducted starting with the financial cost of delays resulting from operational procedures required during closely spaced parallel approaches in instrument meteorological conditions. Existing systems were analyzed focussing on capability and the architectural changes enabled by new technologies. System requirements for a new airborne system for lateral spacing were developed with a focus on human factors and automation. Risk analysis indicates that the probability of collision given pilot nonconformance to alerts in airborne systems is 6 times greater than the probability of collision when pilot's conform to system alerts. The per-approach collision rate requirement can be met using a climb-turn escape maneuver given 90% pilot conformance and pilot response times less than 5 seconds.
by Bruce A. Solomon.
S.M.
14
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.
Testo completoAbstract (sommario):
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.
15
Sharman, Kimberly. "A broadcast-based coordination scheme for a system of autonomous mobile robots". Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/42057.
Testo completoAbstract (sommario):
A method for coordinating a homogeneous swarm of autonomous mobile robots is presented. The broadcast-based coordination scheme was developed for the Army Ant swarm—a system of small, relatively inexpensive mobile robots that can accomplish complex tasks by cooperating as a team. The primary drawback of the Army Ant system is that the absence of a central supervisor poses difficulty in the coordination and control of the agents. Our coordination scheme provides a global "group dynamic" that controls the actions of each robot using only local interactions.
Coordination of the swarm is achieved with signals we call "heartbeats". Each agent broadcasts a unique heartbeat and responds to the collective behavior of all other heartbeats. We generate heartbeats with van der Pol oscillators, which are nonlinear oscillators that modify their output when coupled to other oscillators. Van der Pol oscillators have long been utilized in simulations, particularly to model rhythmic behavior in biological systems. In this application, we use the known properties of coupled van der Pol oscillators to create predictable group behavior. We emphasize the use of this controller to allow agents to simultaneously perform an action such as lifting, steering, or changing speed.
For this research we synthesize a three oscillator network to show that we can achieve multi-agent coordination. An inexpensive FM communication link is used to broadcast and receive oscillator signals. We show that the network may be configured to entrain to a leader or to a common frequency. Additionally, we use our coordination scheme to provide global speed control to our three agent system.Master of Science
16
Dogan, Ebru. "Content-based Audio Management And Retrieval System For News Broadcasts". Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611018/index.pdf.
Testo completoAbstract (sommario):
The audio signals can provide rich semantic cues for analyzing multimedia content, so audio information has been recently used for content-based multimedia indexing and retrieval. Due to growing amount of audio data, demand for efficient retrieval techniques is increasing. In this thesis work, we propose a complete, scalable and extensible audio based content management and retrieval system for news broadcasts. The proposed system considers classification, segmentation, analysis and retrieval of an audio stream. In the sound classification and segmentation stage, a sound stream is segmented by classifying each sub segment into silence, pure speech, music, environmental sound, speech over music, and speech over environmental sound in multiple steps. Support Vector Machines and Hidden Markov Models are employed for classification and these models are trained by using different sets of MPEG-7 features. In the analysis and retrieval stage, two alternatives exist for users to query audio data. The first of these isolates user from main acoustic classes by providing semantic domain based fuzzy classes. The latter offers users to query audio by giving an audio sample in order to find out the similar segments or by requesting expressive summary of the content directly. Additionally, a series of tests was conducted on audio tracks of TRECVID news broadcasts to evaluate the performance of the proposed solution.
17
Blunskis, Rimvydas. "Automobilių varžybų Informacijos transliavimo sistema". Bachelor's thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120702_125521-02731.
Testo completoAbstract (sommario):
Paprasčiausias būdas stebėti autosporto lenktynių rezultatus yra internetiniai portalai. Tačiau ir čia Lietuvos autosporto rengėjai nusileidžia pasaulinio lygio automobilių lenktynių rengėjams ir dažnai lenktynių rezultatus pateikia tik pasibaigus lenktynėms. Šio darbo tikslas – sukurti sistemą kurioje būtų galima talpinti ir peržiūrėti šiuo metu vykstančių automobilių sporto lenktynių rezultatus ir įvykius.In Lithuania there is no such web page which would be easy to access and simply to use for autosport information broadcasting online. Many foreign countries‘ web sites have it, but mostly it is created for specific autorace and is not meant for adaption for other autorace information broadcasting. The aim of this study is to create for system which allows its user to upload current events and results of autorace so autosport fans could follow the race online. System is started to create from specifications of requirements and specifications of architecture of the system which follows with actual creation, improvement and testing of the information system itself. After the program is finished, user‘s guide was written and it helps to install the system and indicates its specifics as well as usage. Information system enables to store racing data, information about it, update the ongoing events, that helps to follow the race and the general information about the race itself.
18
Eguchi, Makoto. "System dynamics analysis of incentives for Automatic Dependent Surveillance Broadcast (ADS-B) equipage". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43184.
Testo completoAbstract (sommario):
Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2008.Includes bibliographical references (p. 81-82).
The demand for air transportation is anticipated to continue to grow in the future. In order to accommodate future demands, the U.S. Joint Planning and Development Office (JPDO) proposed the Next Generation Air Transportation System (NextGen). One of the NextGen technologies currently under development is Automatic Dependent Surveillance - Broadcast (ADS-B), which is a new satellite-based surveillance technology. In order to achieve the adoption of ADS-B, equipage by aircraft operators is essential. However, it is sometimes difficult to achieve the transition from a current technology to a new technology. Therefore, encouraging the individual user's adoption is a key factor of the successful technology transition. This thesis develops the system dynamics model to represent how individual users adopt a new technology, and analyzes how the adoption of new technologies can be encouraged using the system dynamics model. The effects of the following four incentive policies are examined: (1) Acceleration of operational benefits, (2) Preferred access, (3) Financial incentive, and (4) Mandate equipage. The result of the policy analysis shows the each incentive policy is effective to encourage the early adoption of ADS-B. Especially, achieving early benefits is important to accelerate equipage. Moving forward the mandate date of ADS-B equipage also can be effective to increase total benefits.
by Makoto Eguchi.
S.M.
19
Kamau, Peter H. "CPU cache dual processor distributed computation system within broadcast-type Local Area Networks". Thesis, Loughborough University, 1985. https://dspace.lboro.ac.uk/2134/27091.
Testo completoAbstract (sommario):
Over the last few years computer hardware has continued to become smaller, cheaper, faster and more numerous. Computer software too has continued to become more efficient and powerful. The result has therefore been an availability of increasingly versatile microcomputers whose power rival that of minicomputers and many of the earlier generations of mainframe computers. At the same time, computers and communications have merged, with the result that computing power has become cheaper than communication. As the computation becomes cheaper and the machines become faster, the desire to solve larger and more complex problems will continue to increase.
20
Uggalla, L. C. "A resilient Ka-band satellite video broadcast system incorporating time diversity and maximal ratio combining". Thesis, University of South Wales, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702332.
Testo completoAbstract (sommario):
Steadily-increasing user demand for a wide range of high-quality video services delivered via satellite has driven broadcasters to move into the Ka-band and higher frequency spectrum in order to accommodate the necessary data rates. However, a major issue at these frequencies is the effect of severe rain-induced fading on link reliability, which requires that the system must be designed to implement mitigation techniques in order to achieve an acceptable quality-of-service. These techniques generally involve the use of adaptive modulation and data rates, together with various forms of diversity, switching or combining. In this thesis, we analyse and quantify the benefits of adding Time Diversity (TD) and Maximal Ratio Combining (MRC) to the widely-used DVB-S2 standard. Our results, which are based on i) 3 years of satellite beacon propagation measurements from 2 UK sites; ii) high-fidelity computer simulations; and iii) our new TD / MRC technology, indicate that substantial improvements in data throughput and significant reductions in outage time are readily achievable. Accurate knowledge of the statistical distribution of rain attenuation is necessary for the proper design of a Fade Mitigation Technique (FMT) to operate with the required level of service availability. Therefore, since July 2010, the University of South Wales and the Science and Technology Facilities Council have undertaken a programme of simultaneous satellite beacon measurements at the University campus in Pontypridd, Wales, and at the STFC Chilbolton Observatory, in Southern England, respectively. Transmissions from the Eutelsat Hotbird l3A (previously Hotbird 6) satellite at 19.7 GHz were recorded, together with meteorological measurements, at both sites. These data enabled reliable estimation of the instantaneous propagation conditions and carrier-to-noise ratio on the Ku-band beacon downlinks. Using standard ITU-R recommendations, the resulting data-set of measured 19.7 GHz attenuations was also frequency- scaled to yield a predicted data-set of 29.5 GHz attenuations. Thereby, the performance of an operationally-representative, hypothetical DVB-S2 communications link, with uplink at 30 GHz (from Chilbolton to the satellite), and downlink at 20 GHz (from the satellite to Pontypridd), was analysed based on l-year's data. The DVB-S2 transmission and reception signal processing architecture has been faithfully implemented in the MATLAB simulation environment with reference to the appropriate technical standards documents. Extensive testing has been conducted to verify that the bit error rate performance of the MATLAB simulation closely matches that defined in the DVB-S2 standard for all combinations of modulation schemes and coding rates. Inputs to the simulator comprise a test data stream (which can be a real HDTV signal), together with the uplink and downlink attenuation time- series data for the fading event being studied. Outputs consist of the bit error rate statistics and modulation scheme / coding rate configuration as a function of time, the total data throughput over the event duration, and the demodulated baseband signal. A novel feature of this work is the extension of the existing DVB-S2 standard to include TD and MRC. During periods of fading, TD is enabled, such that the transmitted data is duplicated into 2 parallel streams with a suitably-chosen time offset between them. In the receiver, MRC is employed in order to obtain a greater SNR improvement than could be achieved by the more traditional switched-combining method. We have designated this extended version of the DVB-S2 standard, incorporating the twin techniques of TO and MRC, as DVB-S2-TD. It provides the potential to continue delivering services at SNRs significantly below the currently acceptable threshold for DVB-S2, such as would be experienced under the propagation impairments associated with severe weather conditions. In this thesis, we describe the experimental systems used to collect the satellite beacon and meteorological measurements. The implementation of the MATLAB simulator for DVB-S2 is then discussed, together with the enhancements for TD and MRC. Finally, we compare the performance of DVB-S2 and DVB-S2-TD, so as to demonstrate the operational benefits of our new techniques.
21
Lai, Shouwen. "Duty-Cycled Wireless Sensor Networks: Wakeup Scheduling, Routing, and Broadcasting". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/27333.
Testo completoAbstract (sommario):
In order to save energy consumption in idle states, low duty-cycled operation is widely used in Wireless Sensor Networks (WSNs), where each node periodically switches between sleeping mode and awake mode. Although efficient toward saving energy, duty-cycling causes many challenges, such as difficulty in neighbor discovery due to asynchronous wakeup/sleep scheduling, time-varying transmission latencies due to varying neighbor discovery latencies, and difficulty on multihop broadcasting due to non-simultaneous wakeup in neighborhood. This dissertation focuses on this problem space. Specifically, we focus on three co-related problems in duty-cycled WSNs: wakeup scheduling, routing and broadcasting.
We propose an asynchronous quorum-based wakeup scheduling scheme, which optimizes heterogenous energy saving ratio and achieves bounded neighbor discovery latency, without requiring time synchronization. Our solution is based on quorum system design. We propose two designs: cyclic quorum system pair (cqs-pair) and grid quorum system pair (gqs-pair). We also present fast offline construction algorithms for such designs. Our analytical and experimental results show that cqs-pair and gqs-pair achieve better trade-off between the average discovery delay and energy consumption ratio. We also study asymmetric quorum-based wakeup scheduling for two-tiered network topologies for further improving energy efficiency.
Heterogenous duty-cycling causes transmission latencies to be time-varying. Hence, the routing problem becomes more complex when the time domain must be considered for data delivery in duty-cycled WSNs. We formulate the routing problem as time-dependent Bellman-Ford problem, and use vector representation for time-varying link costs and end-to-end (E2E) distances. We present efficient algorithms for route construction and maintenance, which have bounded time and message complexities in the worst case by ameliorating with beta-synchronizer.
Multihop broadcast is complex in duty-cycled WSNs due to non simultaneous wakeup in neighborhoods. We present Hybrid-cast, an asynchronous multihop broadcast protocol, which can be applied to low duty-cycling or quorum-based duty-cycling schedules, where nodes send out a beacon message at the beginning of wakeup slots. Hybrid-cast achieves better tradeoff between broadcast latency and broadcast count compared to previous broadcast solutions. It adopts opportunistic data delivery in order to reduce the broadcast latency. Meanwhile, it reduces redundant transmission via delivery deferring and online forwarder selection. We analytically establish the upper bound of broadcast count and the broadcast latency under Hybrid-cast.
To verify the feasibility, effectiveness, and performance of our solutions for asynchronous wakeup scheduling, we developed a prototype implementation using Telosb and TinyOS 2.0 WSN platforms. We integrated our algorithms with the existing protocol stack in TinyOS, and compared them with the CSMA mechanism. Our implementation measurements illustrate the feasibility, performance trade-off, and effectiveness of the proposed solutions for low duty-cycled WSNs.Ph. D.
22
Ljung, Alexander, e Hannes Knutsson. "Cost-Effective Positioning based on WiFi-Probes: A Quantitative Study : Deriving the Position of a Smartphone using the Signal Strength of WiFi-Probes". Thesis, Blekinge Tekniska Högskola, Institutionen för datalogi och datorsystemteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-16776.
Testo completoAbstract (sommario):
In the modern society, almost everyone has a smartphone. These devices tend to almost always use WiFi-networking. For the device to identify nearby WiFi access points it has to send out WiFi probing broadcasts. Nearby access points respond to these broadcasts in order to let the device know that they are within reach. This technique is called active scanning. This paper aims to answer if it is possible to use the signal strength of these broadcasts to localize the device transmitting them. We are interested in the possibility of creating this kind of system and the accuracy that it would be able to provide. This is a quantitative study where we produce our results based on experiments, measurements and observations. The experiments are set in a large square shaped area. A sensor was placed at each corner of the area that the smartphone will be tracked within. The smartphone will be sending WiFi probing broadcasts that will be monitored and measured by the sensors. The strength of the broadcast signal will be converted into the relative distance between the devices position and the sensors. These four distances, collected from each of the sensors, will further be converted into a position within the area by using trilateration. To measure the accuracy of the system, the true position of the device will be compared against the calculated position from the system using only the signal strength. Further, a deviation in the distance between the two locations will be calculated. The experiments resulted in a positioning system that was able to estimate positions within an 80 x 80m area. Fourteen location positions were taken which resulted in a mean deviation of 16.6 meters from the true location and a root mean squared error of 19.5 meters. We concluded that more readings within the same position gave a significant increase in accuracy, to the expense of time. Using single measurements would be more practical, but would not produce reliable positions. Keywords: WiFi, Probe Broadcast, Local Positioning System, Trilateration, RSSI.
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Hvězda, Vojtěch. "Posouzení informačního systému firmy a návrh změn". Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2016. http://www.nusl.cz/ntk/nusl-241507.
Testo completoAbstract (sommario):
The master thesis is solving a problem of physical security of documents in Document Management System (DMS) in the company Icontio CR s.r.o. This fact will improve the security of the whole system and also the security of data placed in it. The main purpose of this thesis is a proposal of a security module, methods of coding and other functionalities which are going to be neccesarily implemented. Side purpose is a creation of the Access management, structures of data libraries in the DMS system, structures of users in the Active Directory and a suggestion of multilevel workflow. Introduction of these changes should bring the physical security of data, new view on data and simplifying the work with them in all fields of interest.
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Coetzee, Dirk Badenhorst. "The development of an efficient and secure product entitlement system for Pay-TV in modern attack scenarios". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80292.
Testo completoAbstract (sommario):
Thesis (MScEng)--Stellenbosch University, 2013.ENGLISH ABSTRACT: A secure product entitlement system allows one party, such as a pay-TV operator, to broadcast the same collection of information to several receiving parties while only allowing a certain subset of the receiving parties to access the information. This system must still be secure in the scenario where all receiving parties who are not allowed access to the information, pool their resources in an attempt to gain access to the information. Such a product entitlement system must also be bandwidth e cient since it can be deployed in networks where bandwidth is at a premium. The foundations of modern encryption techniques is reviewed and a survey of existing techniques, used to secure content in broadcast environments, is studied. From this collection of techniques two were identi ed as bandwidth e cient and are discussed in more detail before being implemented. An attempt is then made to design a new secure bandwidth e cient encryption scheme for protecting content in a broadcast environment. Several iterations of the design is detailed, including the security aw which makes each design insecure. The nal design was implemented and compared in several metrics to the two previously selected bandwidth e cient schemes. A framework to test the correctness of the schemes over a network is also designed and implemented. Possible future avenues of research are identi ed with regards to creating a secure broadcast encryption scheme and improving the software solution in which to use such a scheme.
AFRIKAANSE OPSOMMING: 'n Veilige produk-aanspraak-stelsel stel een party, soos byvoorbeeld 'n betaal-TV-operateur, in staat om dieselfde versameling inligting na verskeie partye uit te saai, terwyl slegs 'n bepaalde deelversameling van die ontvangende partye toegelaat sal word om toegang tot die inligting te bekom. Hierdie stelsel moet steeds die inligting beskerm in die geval waar al die ontvangende partye wat toegang geweier word, hul hulpbronne saamsmee in 'n poging om toegang te verkry. So 'n produk-aanspraak-stelsel moet ook bandwydte doeltre end benut, aangesien dit gebruik kan word in netwerke waar bandwydte baie duur is. Die fondamente van die moderne enkripsietegnieke word hersien. 'n Opname van bestaande tegnieke wat gebruik word om inligting te beskerm in 'n uitsaai omgewing word bestudeer. Uit hierdie versameling tegnieke word twee geïdenti seer as tegnieke wat bandwydte doeltre end benut en word meer volledig bespreek voordat dit geïmplementeer word. 'n Poging word dan aangewend om 'n nuwe veilige bandwydte doeltre ende enkripsietegniek te ontwerp vir die beskerming van inligting wat uitgesaai word. Verskeie iterasies van die ontwerp word uiteengesit, met 'n bespreking van die sekuriteitsfout wat elke ontwerp onveilig maak. Die nale ontwerp is geïmplementeer en aan die hand van verskeie maatstawwe vergelyk met die twee bandwydte doeltre ende tegnieke, wat voorheen gekies is. 'n Raamwerk om die korrektheid van die tegnieke oor 'n netwerk te toets, is ook ontwerp en geïmplementeer. Moontlike toekomstige rigtings van navorsing word geïdenti seer met betrekking tot die skep van 'n veilige uitsaai enkripsietegniek en die verbetering van die sagtewareoplossing wat so 'n tegniek gebruik.
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Laird, Daniel T., e Jon Morgan. "Data Flow and Remote Control in the Telemetry Network System". International Foundation for Telemetering, 2009. http://hdl.handle.net/10150/606151.
Testo completoAbstract (sommario):
ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, NevadaThe Central Test and Evaluation Investment Program (CTEIP) Integrated Network Enhanced Telemetry (iNET) program is currently developing new standards for wired-wireless local area networking (LAN-WLAN) using the Internet Protocol (IP), for use in telemetry (TM) channels, under the umbrella of the Telemetry Network System (TmNS). Some advantages of TmNS are real-time command and control of instrumentation, quick-look acquisition, data retransmission and recovery ('gapless TM' or 'PCM backfill'), data segmentation, etc. The iNET team is developing and evaluating prototypes, based on commercial 802.x and other technologies, in conjunction with Range Commander's Council (RCC) Inter-Range Instrumentation Group (IRIG) standards and standards developed under the iNET program.
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Silva, Simone Aparecida da [UNESP]. "Fontes e épocas de aplicação de nitrogênio em trigo em plantio direto no cerrado". Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/98728.
Testo completoAbstract (sommario):
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silva_sa_me_ilha.pdf: 5361750 bytes, checksum: d4d5363fa37e6fc0364f62dd5fd864a4 (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O nitrogênio é um nutriente de suma importância, tendo em vista sua dinâmica no solo e a exigência da cultura, porém, em muitas situações o solo é incapaz de suprir todo o requerimento de nitrogênio das culturas, o que obriga a utilização de fertilizantes para a obtenção de produtividade satisfatória. Desse modo, propôs-se o estudo com o objetivo de avaliar diferentes fontes e modos de aplicação de nitrogênio em trigo cultivado no sistema de plantio direto, no período de maio a agosto dos anos de 2006 e 2007, em área experimental da UNESP – Campus de Ilha Solteira, localizada no município de Selvíria – MS. A aplicação de nitrogênio na semeadura, em cobertura ou parcelado na semeadura e em cobertura apresentaram produtividades semelhantes, porém superiores ao tratamento sem nitrogênio. O uso da fonte uréia propiciou produtividade de grãos semelhante aos tratamentos com uso de fonte com liberação gradual. As estimativas de custos e lucratividade indicaram que a produção de trigo irrigado em sistema de plantio direto não foi rentável, tendo em vista, que o preço médio considerado nesta safra não foi suficiente para cobrir os custos. As fontes e as épocas de aplicação evidenciaram comportamentos diferentes e pelos níveis da qualidade das sementes, se mostrou mais indicado o uso da fonte Entec com aplicação do N todo na semeadura
Nitrogen is an important nutrient, due to its dynamics in the soil and necessity by the crops; however, in a lot of situations the soil is unable to supply enough amount of nitrogen, needing the use of nitrogen fertilization for obtaining high productivity. In this way, this study was conducted with the objective of evaluating different sources and times of nitrogen application in wheat cropped in no till system, from May to August in 2006 and 2007, in at Experimental Station of UNESP – Ilha Solteira Campus, located in Selvíria County – MS. The different methods yielded similar production results, being all superior to production without application of fertilizer N. Urea-N yielded a similar grain production to slow-release-N. Estimates of costs and profit margin indicate that irrigated no-till wheat production is not profitable when taking into account the average final commercial price, as it does not cover production costs. The different forms of fertilizer N and times of application yielded different production results, and, depending on the seed quality, we would thus recommend applying fertilizer N in the Entec form upon sowing
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Haggar, Bachar Salim. "Auto-organisation et routage dans les réseaux mobiles ad hoc". Thesis, Reims, 2011. http://www.theses.fr/2011REIMS036/document.
Testo completoAbstract (sommario):
Nos travaux se positionnent dans le cadre de l'algorithmique distribuée et plus particulièrement des réseaux ad hoc. Les réseaux ad hoc sont auto-organisés en permettant des échanges directs entre nœuds mobiles et ne reposent sur aucune infrastructure. Chaque nœud peut se déplacer librement et indépendamment des autres impliquant une modification perpétuelle de la topologie. Dans ce contexte, la probabilité que des défaillances surviennent dans le réseau est importante. Ces défaillances gênent le bon fonctionnement du réseau et peuvent même entrainer une paralysie de celui-ci. C'est pourquoi la conception de solutions pour de tels réseaux nécessitent des mécanismes de gestion de fautes. Parmi ceux-ci, l'approche d'auto-stabilisation permet à un système de gérer les fautes transitoires. Nous étendons cette approche pour répondre aux principaux problèmes liés à la mobilité des nœuds. Notre objectif est de répondre à un double besoin d'auto-organisation du réseau et d'optimisation du nombre de messages échangés. Notre approche consiste à découper le réseau en clusters afin de lui donner une structure hiérarchique. Cette dernière rend l'utilisation du réseau plus efficace et plus performante. L'algorithme que nous avons développé à cet effet est auto-stabilisant et n'est basé que sur des connaissances locales. Nous exploitons cette solution pour proposer deux utilisations efficaces : la diffusion d'informations dans le réseau et le routage. La diffusion d'informations exploite un arbre couvrant inter-clusters, construit sans surcoût, en parallèle de la clusterisation. Le routage quant à lui exploite cet arbre pour permettre à la fois d'optimiser le délai de bout en bout et le nombre de messages échangésOur work relies in the domain of distributed system, more preciselly ad hoc networks. Ad hoc networks are self-organized allowing direct exchanges between mobile nodes and do not rely on any infrastruture. Each node can move freely and independently of each others involving continuous topology variability. In this context, the probability that a failure occurs in the network is high. These failures hinder the proper functioning of the network and even causes its paralysis. Therefore, designing solutions for such networks requires fault management mechanisms. Among these, a self-stabilizating approach allows the system to withstand transient faults. We extend this approach to answer the problems induced by nodes mobility. We have two main objectives: a self-organizing network and optimizing number of exchanged messages. Our approach consists in dividing the network into clusters in order to give it a hierarchical structure. This solution allows a more efficient and effective network use. The algorithm that we developed for this purpose is a self-stabilizing algorithm based only on local informations. Based on this solution, we propose two efficient use cases: Information broadcast and a routing protocol. Information broadcast uses an inter-cluster spanning tree, generated without any overhead. In the same time as the clustering process. The routing protocol uses this tree for both round trip and number of exchanged messages optimization
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Aymak, Onur. "Ad Hoc Packet Routing Simulation And Tactical Picture Display Tool For Navy". Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12605266/index.pdf.
Testo completoAbstract (sommario):
The importance of communication is vital in wartime. The capability of having all the position information of the allied and enemy forces in a single Tactical Information Display System (TIDS), maintains a great advantage for deciding what to do before the enemy reacts. A Naval Information Distributing System (NIDS) is developed for building an effective communication infrastructure between the war ships. In the designed network, besides the mobile platforms (ships), some fixed platforms (land stations) are used to transfer the information coming from these mobile platforms to all the other platforms. To demonstrate the performance and effectiveness of the Naval Information Distribution System, a discrete event simulation model is developed on a Geographic Information System. The goal of this thesis is to describe and experimentally evaluate an effective and feasible information sharing and routing system for Navy.
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Šostý, Radim. "Časomíra pro požární sport využívající bezdratové technologie". Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2014. http://www.nusl.cz/ntk/nusl-413349.
Testo completoAbstract (sommario):
This thesis deals with design and implementation of flexible modular electronic stopwatch system for use in resport. One of the advantages of the system is possibility of using wireless communication with sensors and displays. Developed system consist of main control unit, external display, wireless modules for communication with the sensors and desktop application that collects data and controls the system. Solution of system components, communication between them and method of time synchronization of wireless devices is also described in this thesis.
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Silva, Simone Aparecida da. "Fontes e épocas de aplicação de nitrogênio em trigo em plantio direto no cerrado /". Ilha Solteira : [s.n.], 2009. http://hdl.handle.net/11449/98728.
Testo completoAbstract (sommario):
Orientador: Orivald ArfBanca: Maria Aparecida Anselmo Tarsitano
Banca: Domingos Fornasieri Filho
Resumo: O nitrogênio é um nutriente de suma importância, tendo em vista sua dinâmica no solo e a exigência da cultura, porém, em muitas situações o solo é incapaz de suprir todo o requerimento de nitrogênio das culturas, o que obriga a utilização de fertilizantes para a obtenção de produtividade satisfatória. Desse modo, propôs-se o estudo com o objetivo de avaliar diferentes fontes e modos de aplicação de nitrogênio em trigo cultivado no sistema de plantio direto, no período de maio a agosto dos anos de 2006 e 2007, em área experimental da UNESP - Campus de Ilha Solteira, localizada no município de Selvíria - MS. A aplicação de nitrogênio na semeadura, em cobertura ou parcelado na semeadura e em cobertura apresentaram produtividades semelhantes, porém superiores ao tratamento sem nitrogênio. O uso da fonte uréia propiciou produtividade de grãos semelhante aos tratamentos com uso de fonte com liberação gradual. As estimativas de custos e lucratividade indicaram que a produção de trigo irrigado em sistema de plantio direto não foi rentável, tendo em vista, que o preço médio considerado nesta safra não foi suficiente para cobrir os custos. As fontes e as épocas de aplicação evidenciaram comportamentos diferentes e pelos níveis da qualidade das sementes, se mostrou mais indicado o uso da fonte Entec com aplicação do N todo na semeadura
Abstract: Nitrogen is an important nutrient, due to its dynamics in the soil and necessity by the crops; however, in a lot of situations the soil is unable to supply enough amount of nitrogen, needing the use of nitrogen fertilization for obtaining high productivity. In this way, this study was conducted with the objective of evaluating different sources and times of nitrogen application in wheat cropped in no till system, from May to August in 2006 and 2007, in at Experimental Station of UNESP - Ilha Solteira Campus, located in Selvíria County - MS. The different methods yielded similar production results, being all superior to production without application of fertilizer N. Urea-N yielded a similar grain production to slow-release-N. Estimates of costs and profit margin indicate that irrigated no-till wheat production is not profitable when taking into account the average final commercial price, as it does not cover production costs. The different forms of fertilizer N and times of application yielded different production results, and, depending on the seed quality, we would thus recommend applying fertilizer N in the Entec form upon sowing
Mestre
31
Rehn, Michael. "Garbage Collected CRDTs on the Web : Studying the Memory Efficiency of CRDTs in a Web Context". Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-413299.
Testo completoAbstract (sommario):
In today's connected society, where it is common to have several connected devices per capita, it is more important than ever that the data you need is omnipresent, i.e. its available when you need it, no matter where you are. We identify one key technology and platform that could be the future—peer-to-peer communication and the Web. Unfortunately, guaranteeing consistency and availability between users in a peer-to-peer network, where network partitions are bound to happen, can be a challenging problem to solve. To solve these problems, we turned to a promising category of data types called CRDTs—Conflict Free Replicated Data Types. By following the scientific tradition of reproduction, we build upon previous research of a CRDT framework, and adjust it work in a peer-to-peer Web environment, i.e. it runs on a Web browser. CRDTs makes use of meta-data to ensure consistency, and it is imperative to remove this meta-data once it no longer has any use—if not, memory usage grows unboundedly making the CRDT impractical for real-world use. There are different garbage collection techniques that can be applied to remove this meta-data. To investigate whether the CRDT framework and the different garbage collection techniques are suitable for the Web, we try to reproduce previous findings by running our implementation through a series of benchmarks. We test whether our implementation works correctly on the Web, as well as comparing the memory efficiency between different garbage collection techniques. In doing this, we also proved the correctness of one of these techniques. The results from our experiments showed that the CRDT framework was well-adjusted to the Web environment and worked correctly. However, while we could observe similar behaviour between different garbage collection techniques as previous research, we achieved lower relative memory savings than expected. An additional insight was that for long-running systems that often reset its shared state, it might be more efficient to not apply any garbage collection technique at all. There is still much work to be done to allow for omnipresent data on the Web, but we believe that this research contains two main takeaways. The first is that the general CRDT framework is well-suited for the Web and that it in practice might be more efficient to choose different garbage collection techniques, depending on your use-case. The second take-away is that by reproducing previous research, we can still advance the current state of the field and generate novel knowledge—indeed, by combining previous ideas in a novel environment, we are now one step closer to a future with omnipresent data.I dagens samhälle är vi mer uppkopplade än någonsin. Tack vare det faktum att vi nu ofta har fler än en uppkopplad enhet per person, så är det viktigare än någonsin att ens data är tillgänglig på alla ens enheter–oavsett vart en befinner sig. Två tekniker som kan möjliggöra denna ``allnärvaro'' av data är Webben, alltså kod som körs på en Webbläsare, tillsammans med peer-to-peer-kommunikation; men att säkerställa att distribuerad data både är tillgänglig och likadan för alla enheter är svårt, speciellt när enhetens internetanslutning kan brytas när som helst. Conflict-free replicated data-types (CRDT:er) är en lovande klass av datatyper som löser just dessa typer av problem i distribuerade system; genom att använda sig av meta-data, så kan CRDT:er fortsätta fungera trots att internetanslutningen brutits. Dessutom är de garanterade att konvergera till samma sluttillstånd när anslutningen upprättas igen. Däremot lider CRDT:er av ett speciellt problem–denna meta-data tar upp mycket minne trots att den inte har någon användning efter en stund. För att göra datatypen mer minneseffektiv så kan meta-datan rensas bort i en process som kallas för skräpsamling. Vår idé var därför att reproducera tidigare forskning om ett ramverk för CRDT:er och försöka anpassa denna till att fungera på Webben. Vi reproducerar dessutom olika metoder för skräpsamling för att undersöka om de, för det första fungerar på Webben, och för det andra är lika effektiv i denna nya miljö som den tidigare forskningen pekar på. Resultaten från våra experiment visade att CRDT-ramverket och dess olika skräpsamlingsmetoder kunde anpassas till att fungera på Webben. Däremot så noterade vi något högre relativ minnesanvändning än vad vi har förväntat oss, trots att beteendet i stort var detsamma som den tidigare forskningen. En ytterligare upptäckt vad att i vissa specifika fall så kan det vara mer effektivt att inte applicera någon skräpsamling alls. Trots att det är mycket arbete kvar för att använder CRDT:er peer-to-peer på Webben för att möjliggöra ``allnärvarande'' data, så innehåller denna uppsats två huvudsakliga punkter. För det första så fungerar det att anpassa CRDT-ramverket och dess olika skräpsamlingsmetoder till Webben, men ibland är det faktiskt bättre att inte applicera någon skräpsamling alls. För det andra så visas vikten av att reproducera tidigare forskning–inte bara visar uppsatsen att tidigare CRDT-forskning kan appliceras i andra miljöer, dessutom kan ny kunskap hämtas ur en sådan reproducering.
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Cason, Daniel 1987. "Protocolo de difusão síncrona totalmente ordenada para aglomerados de alto desempenho". [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/275659.
Testo completoAbstract (sommario):
Orientador: Luiz Eduardo BuzatoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação
Made available in DSpace on 2018-08-22T08:23:33Z (GMT). No. of bitstreams: 1 Cason_Daniel_M.pdf: 1133475 bytes, checksum: 2c269ea2aec943999c502cd1944b09ae (MD5) Previous issue date: 2013
Resumo: Protocolos de Difusão Totalmente Ordenada (DTO) constituem o núcleo de diversas soluções que dão suporte ao desenvolvimento de aplicações distribuídas tolerantes a falhas. O longo período no qual este problema vem sendo objeto de pesquisa e a quantidade de algoritmos que foram para ele propostos atestam, não só a sua importância, mas também a dificuldade de se obter soluções eficientes para DTO. Este trabalho apresenta um novo algoritmo de DTO, que explora a sincronia e a confiabilidade inerentes ao ambiente dos aglomerados ou clusters de alto desempenho para construir uma solução bastante simples de Difusão Totalmente Ordenada, cujo desempenho experimental mostrou-se comparável ao obtido por soluções de DTO projetadas para modelos assíncronos de computação. O protocolo proposto destina-se ao modelo assíncrono temporizado de computação, aumentado com um mecanismo simples, baseado na difusão de pulsos, para sincronizá-la a execução dos processos. A hipótese que sustenta este mecanismo de sincronização é que os aglomerados modernos, dado que se controle a carga a eles aplicada, podem executar por períodos razoavelmente longos sem que ocorram falhas de processos e apresentando um comportamento bastante similar ao de sistemas síncronos. Dada esta hipótese, os processos que realizam Difusão Totalmente Ordenada tornam-se capazes de construir visões globais da computação distribuída, e a construção de visões globais, por sua vez, torna trivial a resolução de Difusão Totalmente Ordenada. O protocolo proposto tolera uma quantidade ilimitada de falhas de desempenho, que previnem o progresso da solução de DTO, mas que não levam à violação de suas propriedades de segurança, que são asseguradas na presença de assincronia e de falhas de processos. O protocolo foi implementado em Java e o seu desempenho foi avaliado em um aglomerado com máquinas interconectadas via Ethernet. A comparação dos resultados obtidos com os resultados de desempenho publicados para as principais soluções de DTO existentes nos permite afirmar que nossa solução representa um interessante compromisso entre desempenho experimental e simplicidade de projeto e implementação de soluções de Difusão Totalmente Ordenada. Além dos resultados de desempenho, esta pesquisa também revela que ainda há espaço para a exploração prática da interação entre sincronia e assincronia na engenharia de protocolos distribuídos
Abstract: Total order broadcast algorithms are at the core of several toolkits for the construction of fault-tolerant applications. The importance and the difficulty of finding efficient total order broadcast (TOB) algorithms is attested by the long period that such algorithms have been the object of intense research and by the large number of algorithms already proposed. This work presents a new algorithm for total order broadcast that takes advantage of the inherent reliability and timeliness of high performance clusters in its design. Experimental results show that the performance of this very simple TOB is on a par with the performance of TOBs designed for asynchronous computing models. The proposed protocol has been designed for the timed asynchronous computing model, enhanced with a simple pulse-based mechanism that is used to synchronize the processes' execution. The assumption behind the pulse-based synchronization is that modern clusters, given some workload conditioning, can maintain reasonably long failure-free execution periods in which they behave very much as synchronous system. This assumption allows the processes that engage in total order broadcasts to build a global view of their joint computation and this global view, in its turn, allows them to solve total order broadcast in a straightforward way. The protocol tolerates an unbounded number of timing failures, that can prevent its progress but have no impact on its safety, it is also safe in the in the presence of asynchrony, and processes failures. The protocol has been implemented in Java and tested on an Ethernet-based cluster. A comparison of the results obtained in the experiments with results published for other well-known TOBs allow us to conclude that our solution represents an interesting trade-o_ between performance and simplicity of design and implementation for total order broadcasts protocols. Beyond performance, this research seems to indicate that there is still room for the practical exploration of the interplay between synchronicity and asynchronicity in the engineering of distributed protocols
Mestrado
Ciência da Computação
Mestre em Ciência da Computação
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Trujillo, Castañeda Eduardo Daniel. "Resource allocation for multiple-user multiple-antenna cellular systems". Doctoral thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14078.
Testo completoAbstract (sommario):
Doutoramento em Engenharia ElectrotécnicaThe thesis addresses the sum rate or spectral e ciency maximization problem in cellular systems with two main components, multiple antennas and multiple users. In order to solve such a problem, several resource allocation techniques are studied and developed for di erent cellular scenarios. The antennas at the transmitters are arranged in several con gurations, i.e., co-located or distributed and for such arrangements di erent levels of coordination and cooperation between transmitters are investigated. Accounting for more receiver antennas than transmitter antennas implies that system optimization must select the best transmitter-receiver match (combinatorial problem) which can be solved with di erent degrees of cooperation between transmitters. The system models studied can be classi ed either as interference limited or as power limited systems. In interference limited systems the resource allocation is carried out independently by each transmitter which yield power leakage to unintended receivers. For this kind of systems, the access network using distributed antenna architectures is examined. The properties of distributed antenna in cellular systems as well as the gains they provide in terms of frequency reuse and throughput are assessed. Accounting for multiple user scenarios, several techniques and algorithms for transmitter-receiver assignment, power allocation, and rate allocation are developed in order to maximize the spectral e ciency. In power limited systems the transmitters jointly allocate resources among transmit and receive antennas. The transmitters are equipped with multiple antennas and signal processing is implemented in order to suppress inter-user interference. Single-cell and multi-cell systems are studied and the problem of sum rate maximization is tackled by decoupling the user selection and the resource allocation (power and precoding) processes. The user selection is a function of the type of precoding technique that is implemented and the level of information that can be processed at the transmitter. The developed user selection algorithms exploit information provided by novel channel metrics which establish the spatial compatibility between users. Each metric provides a di erent trade-o between the accuracy to identify compatible users, and the complexity required to compute it. Numerical simulations are used to assess the performance of the proposed user selection techniques (metrics and algorithms) whose performance are compared to state-of-the-art techniques.
Esta tese descreve o problema da maximização da taxa de transmissão ou e ciência espectral em sistemas moveis tomando em atenção duas características fundamentais destes, o número de antenas e utilizadores. A fim de resolver este tipo de problema, várias técnicas de alocação de recursos foram estudadas e propostas para diferentes cenários. As antenas nos transmissores estão organizadas em diferentes configurações, podendo ser localizadas ou distribuídas e para estes esquemas, diferentes níveis de cooperação e coordenação entre transmissores foram investigados. Assumindo mais antenas receptoras do que antenas transmissoras, implica que a otimização do sistema seleccione as melhores combinações de transmissor-receptor (problema combinatório), o que pode ser concretizado usando diferentes graus de cooperação entre transmissores. Os modelos de sistemas estudados, podem ser classificados como sistemas limitados por interferência ou sistemas limitados por potência. Em sistemas limitados por interferência a alocação de recursos e feita independentemente para cada transmissor o que resulta em perda de energia para os receptores não tomados em consideração. Para este tipo de sistemas, e considerado o caso em que a rede de acesso e constituída por antenas distribuídas. Os ganhos obtidos devido ao uso de antenas distribuídas, quer em termos do planeamento de frequências quer da maximização da taxa de transmissão são considerados. Assumindo esquemas multi-utilizador, várias técnicas e algoritmos de transmissão-recepção, alocação de potência e de taxa de transmissão foram desenvolvidos para maximizar a e ciência espectral. Para sistemas limitados em potência os transmissores alocam os recursos quer de antenas de transmissão quer de recepção conjuntamente. Os transmissores estão equipados com várias antenas e o processamento de sinal e implementado de modo a eliminar a interferência entre utilizadores. Sistemas de célula única e de múltiplas células foram estudados. Para estes foi considerado o problema da maximização de taxa de transmissão o qual foi resolvido heuristicamente, através do desacoplamento do problema em duas partes, uma onde se efectua a seleção de utilizadores e outra onde se considera a alocação de recursos. A seleção de utilizadores e feita em função do tipo de técnicas de pré-codificação implementadas e do nível de informação que o transmissor possui. Os algoritmos de seleção de utilizadores desenvolvidos verificam a compatibilidade espacial entre utilizadores, usando para tal métricas propostas. Cada uma das métricas oferece um trade-off diferente entre a precisão para identificar um utilizador compatível e a complexidade necessária para a implementar. Foram usadas simulações numéricas para avaliar a performance das técnicas de seleção de utilizadores propostas (métricas e algoritmos), performance que foi comparada com as técnicas mais inovadoras.
34
Lotter, Theresa E. "An investigation into the sustainability of community radio. Campus radio as case-study". Diss., 2007. http://hdl.handle.net/2263/29567.
Testo completoAbstract (sommario):
There is a dearth of information on community radio in South Africa; although much attention has been given to the role of community radio in development, education and community representation, there has been very little focus on community radio’s functioning within South Africa’s current broadcast system. The researcher explored the viability of the current conception of community radio by means of a literature review, as well as an examination of the South African Advertising Research Foundation’s listener figures for community radio stations across South Africa. The researcher then investigated how conducive the present broadcasting climate is to the growth of this medium through the use of a campus radio station as case-study. Semi-structured interviews were held with the management staff of a campus radio station; a thematic analysis was then conducted on the completed interviews so as to extract the meanings inherent in the participant’s experience. As such, the question of whether community radio can continue to survive within South Africa’s three-tier system of broadcasting without a radical re-conceptualization of the broadcasting system itself, was addressed. The researcher explored what community radio gives to the world of broadcasting that commercial and public radio does not, and how these contributions can be compounded to ensure the long term sustainability of this medium. These arguments were then put forth in the creation of a hypothetical re-conceptualization of a new broadcasting system.Dissertation (M (Research Psychology))--University of Pretoria, 2007.
Psychology
M (Research Psychology)
unrestricted
35
HAN, BING-RUEI, e 韓秉瑞. "Broadcast Interpolation System Research". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/c2q76n.
Testo completoAbstract (sommario):
碩士國立高雄科技大學
電腦與通訊工程系
107
This paper is mainly to study the principle of the amplifier, how to increase the voltage and the effect on the signal, so that it can generate the optimal gain for the signal to be amplified, and it is applied by our experiment. It also contains a discussion of the Frisian equation of transmission, the relationship between the distance of two antennas, the transmission power, and the received power. Then measure the power of the FM radio station, and based on Kaohsiung, take six radio stations as the benchmark, and actually measure the power of each station to the laboratory. With these, we can target the general FM radio. The radio, through our amplifier, achieves the effect of coverage, that is, the cover. Then use the Bluetooth transmission to transmit the already recorded sound to the car audio converter, and then, through our amplifier, amplify the signal source in the same frequency band, increase its power, and then transmit the amplified signal through the antenna. And then received by the broadcast system.
36
Liao, Jhen-Hong, e 廖振宏. "Implementation of the Addressable Broadcast System". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/3q5rxa.
Testo completoAbstract (sommario):
碩士景文科技大學
電腦與通訊研究所
99
The campus broadcast system is a commonly being used system such that its stability is most essential. The traditional campus broadcast system often operates to the entire campus, which in turn affects irrelevant classes, staffs and students. This paper proposes an addressable broadcast system which can send message to selected class without interfering with others. This system replaces the traditional broadcast system with network communication, which is easy to install and repair, and also improves the controllability and scalability. This system provides a main station and several subsidiary stations for system management. The main station can broadcast directly to every selected point through controlling the addressing decoder belonging to certain subsidiary station. The subsidiary station can broadcast to every selected point of its jurisdiction as well. The system can be easily handled via graphical human-machine interface and features the functions of regional broadcasting, group broadcasting, two-way communication between main and subsidiary stations, and priority control. In addition, the main and each subsidiary station possess the abilities of connection detection, reconnecting, and recording the scan log file. By which, the system can monitor the connection status at all times to provide various broadcasts with the least class interference and the most convenient operation.
37
Hung, Mao-hsiung, e 洪茂雄. "Event Detection System of Broadcast Baseball Videos". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/03921360663118309006.
Testo completoAbstract (sommario):
博士義守大學
資訊工程學系博士班
97
In the past decade, because the information amounts of broadcast sport videos have increased explosively, in order to manage the large amount of data, automatic high-level semantic analysis for sport videos has received intensive attention. This dissertation presents an effective and efficient event detection system for broadcast baseball videos. It integrates mid-level cues including scoreboard information and shot transition patterns into event classification rules. First, a simple scoreboard detection and recognition scheme is developed to extract the game status from videos. Then, a shot transition classifier is designed to obtain the shot transition patterns, which contains several novel schemes including adaptive playfield segmentation, pitch shot and field shot detection, as well as infield/outfield classification. The extracted mid-level cues are used to develop an event classifier based on a Bayesian Belief Network. The network is with low complexity because the number of these cues used is small, which not only improves the performance of the event classifier but also reduces system complexity as well as training efforts. Using the inference results of the network, we further derive a set of classification rules to identify baseball events. The sets of rules are stored in a look-up table such that the classification is only a simple table look-up operation. The proposed approach is very simple and computationally efficient. More importantly, the simulation results indicate that it identifies ten significant baseball events with 95% of precision rate and 92% of recall rate, which is very promising.
38
Yang, Wenpin, e 楊文斌. "Broadcast System Performance Improvement in Noisy Environment". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/45847996455741130057.
Testo completoAbstract (sommario):
碩士長榮大學
職業安全與衛生學系碩士班
99
This study is to conduct fire horn speaker of performance-improving designing approach, assisted with the software of theater sound simulation－Yamaha Sound System Simulator－designed by a Japanese corporation, YAMAHA, to probe into the noisy environment (such as air compressor room, etc) to help solving the ineffective receiving from speakers. Via the result of the live testing, we find the computed values of sound pressure of different setting distances under the functional formula set according to the Standard of Fire Safety Code 133 are higher than those actually gauged by sound level meter. Moreover, the distribution of the values of sound pressure simulated by Y-S3 also accord with those actually gauged of the curve of minimum sound pressure. This result provides the basis for the research of speaker performance-improving designing and also suggests that the values of sound pressure simulated by Y-S3 are conservative and referable in the following research. During the unwarned fire evacuation drill in small noisy environment, the personnel can clearly identify the human voices and alarming sirens issued by the emergency-broadcasting speakers if the comprehensive values (noises of targeting field and of speakers) of sound pressure lively gauged by the sound level meter is higher than the net sound pressure solely issued by the speakers within 6 dB. This research took a factory for experiment, by using Y-S3 to proceed with the performance improvement of the speakers, and the effects of the emergency broadcasting system are obviously promoted.
39
Chung, Yu-Feng, e 鍾裕峰. "The Teaching Broadcast System Design Under Windowize". Thesis, 1999. http://ndltd.ncl.edu.tw/handle/19884610748377106013.
Testo completoAbstract (sommario):
碩士國立成功大學
電機工程學系
87
Under the fast developing era of the computer information, it is very important to improve the teaching efficiency of the courses. Therefor, if we could build an efficient and convenient teaching system, it would give a great help to the education of the computer course. For this purpose, this thesis proposes windows operating interface as the basic structure of the teaching broadcast system, and, based on the structure, builds a system to transmit screen immediately without the limitation by any Operating System.
40
Chen, Yan-Jun, e 陳彥鈞. "MP3 Audio Broadcast System Based on Bluetooth Technique". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/45584522211953083934.
Testo completoAbstract (sommario):
碩士國立成功大學
工程科學系碩博士班
96
Recently, the digital multimedia is becoming a major issue because of it has some significant properties such as high compression rate, noise reduction, secrecy, and pocketable. Therefore, the most data of the multimedia are presented with digital format. Furthermore, Bluetooth wireless network provides a convenient environment which can connect to the local area network without any wiring efforts and enjoy reliable high-speed connectivity. Inspired by the advantages mentioned above, a PC-based wireless audio broadcast system is proposed this study. Firstly, the audio database with MP3 format have been built and encrypted in the host. Secondly, the encrypted data are broadcasted by Bluetooth USB dongle. Finally, these data are decrypted and displayed on FPGA-based receiver. The works of this study include: (1) design of GUI command window; (2) connection between Bluetooth Dongle and Bluetooth module; (3) integration among FPGA developed board, Bluetooth module, MP3 decoder, and DES for implementing the broadcast platform. In practical, the proposed system can work effectively and ensure data accuracy.
41
楊長翰. "Study of Remote Control for Broadcast Operating System". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/v2e23u.
Testo completo
42
Huang, Yi-chin, e 黃奕欽. "Emotional Text-to-Speech System of Baseball Broadcast". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/7595f3.
Testo completoAbstract (sommario):
碩士國立中山大學
資訊工程學系研究所
96
In this study, we implement an emotional text-to-speech system for the limited domain of on-line play-by-play baseball game summary. TheChinese Professional Baseball League (CPBL) is our target domain. Our goal is that the output synthesized speech is fluent with appropriate emotion. The system first parses the input text and keeps the on-court informations, e.g., the number of runners and which base is occupied, the number of outs, the score of each team, the batter''s performance in game. And the system adds additional sentences in the input text. Then, the system outputs neutral synthesized speech from the text with additional sentences inserted, and subsequently converts it to emotional speech. Our approach to speech conversion is to simulate a baseball braodcaster. Specifically, our system learns and uses the prosody from a broadcaster. To learn the prosody, we record two baseball games and analyze the prosodic features of emotional utterances. These observations are used to generate some prosodic rules of emotional conversion. The subjective evaluation is used to study the preference of the subjects about the additional sentences insertion and the emotion conversion in the system.
43
Han, Chung-Ping, e 韓忠平. "Cross platform network broadcast system research and develop". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/80050863192860168542.
Testo completo
44
Chen, Ming-Chi, e 鄭明祈. "Design and Implementation of the Broadcast-interruption Processing System". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/52993566715633456966.
Testo completoAbstract (sommario):
碩士義守大學
電子工程學系碩士在職專班
99
This thesis proposes a system by using the devices of electrical communication and a computer to monitor the sound of the broadcasting and TV programs. This system can substitute traditional manual monitor to maintain the high quality mass media program smoothly and guarantee the audience’s rights.
45
CHIANG, MING-SUNG, e 江明松. "A Study on Spatial Queries in Wireless Broadcast System". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/24179805271691292862.
Testo completoAbstract (sommario):
碩士國立臺灣科技大學
資訊工程系
94
Because of the growing popularity of digital mobile devices and rapid advent of wireless technology, it become an import issue that provide user with information via wireless channel to solve the query, and wireless broadcast system that is high scalability is very suitable for this. In the past, the research is only concerned with location independent data such as stock price and race score. In mobile computing era, location is also a dimension of data and spatial query gradually becomes important. Spatial query is always a researchable topic in the field of database, and tree index which have been developed is not suitable for wireless broadcast system. In a recent paper, a new index structure based on the Hilbert curve is proposed, and it is linear and more proper than tree index in wireless broadcast system. In this paper, we address the issue of KNN (K Nearest Neighbor) query and try to add a little important geographic data on Hilbert Curve Index Structure. Let the KNN query be able to finish more efficiently.
46
Shiu, Kuo-Cheng, e 徐國正. "Multi-wavelength Laser Module for Broadcast and Communication System". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/4nhwm7.
Testo completoAbstract (sommario):
碩士國立臺北科技大學
光電工程系研究所
101
Recently, there have tremendous bandwidth demand of broadcast service such as DVB, HDTV, and IPTV. In order to fulfill the bandwidth demand, radio over fiber (ROF) communication systems which integrates optical and radio signal is highly promising for satisfy such requirements. So, this work presents a multi-wavelength laser diode for broadcast and communication system applications using a reflective semiconductor optical amplifier (RSOA). In contrast to the previously broadcast transport systems, this broadcast light source free spectral range (FSR) can tunable. Additional, to demonstrate systems performance, which is analyzed pseudo random binary sequence (PRBS) 625Mb/s or orthogonal frequency division multiplexing (OFDM) - quadrature phase shift keying (QPSK) 312.5Mb/s broadcast signal by using bit-error-rate (BER) measurements for back to back (BTB) and 25km fiber transmission. According to the experimental results, excellent performances of BER is achieved for PRBS broadcast signal applications, along with OFDM broadcast signal transmission achieved as well.
47
Hwa, Wei-Ru, e 華濰儒. "The Research and Implement on SIP-based Broadcast System". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/g4vsjm.
Testo completoAbstract (sommario):
碩士國立臺北科技大學
電機工程系研究所
99
This paper offers a solution for internet broadcast system by using SIP protocol. The broadcast system can change the point-to-point calling mode to the point-to-multipoint calling mode, and also can overcome the limitation of NAT and ROUTER on the internet environment. The broadcast system advances IP phone’s function, so IP phones can not only make a phone call but also broadcast. The SIP-based Broadcast System can do broadcast, scheduled broadcast, class bell, setting broadcast group, grouping broadcast, adding some groups on broadcast ,cancelling some groups on broadcast. This paper focuses on two topics: 1. The research and implementation of SIP and RTP protocol. 2. The research and implementation of SIP-based broadcast system.
48
Chiang, Yi-Fu, e 蔣逸夫. "A Radio-broadcast-based Information and Service Providing System". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/23957915474210029939.
Testo completoAbstract (sommario):
碩士國立臺灣科技大學
電機工程系
96
Radio broadcasting is one of the most early-developed mass media. Through audio communication, radio broadcasting serves a variety of functions such as providing information, educational training and entertaining. In addition, thanks to its low-cost, universal, portable, and user-friendly features, broadcasting has been an essential part of human life. The Internet has been the fastest-growing product of digital revolution in the 21st century. Multi-media information and highly-interactive platform allow more and more modern people enjoy their convenience, and many of the latest applications are highly related it. This thesis combines the properties of both the radio and internet, proposing the Radio-broadcast-based information and service providing system. Through the Radio Data System (RDS), the system allows users to access information or services via the Internet while receiving a particular radio program. Meanwhile, the users are welcomed to obtain or download the digital information or services provided by an information and services platform that is associated with the radio broadcaster. The cross-media combination not only retains the traditional usage of the radio broadcasting, besides, thanks to the Internet, it meets the convenience of the integration of visual communication and information.
49
Hsieh, Chi-Jung, e 謝季融. "Design and Implement of a P2P Streaming Broadcast System". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/75629071859511618911.
Testo completoAbstract (sommario):
碩士國立臺灣海洋大學
資訊工程學系
92
Among Client/(Centralized) Server structure, no matter how big bandwidth a server might have, the effective bandwidth could be consumed quickly by enormous numbers of internet users. Though IP-Multicast can alleviate demands of network bandwidth, it suffers availability of word-wide deployment so far. An alternative way to solve this problem is to use Application Layer Multicast (ALM). Comparing with the limitation of IP-Multicast approaches, ALM is more promising to deploy, since ALMs need not count on other advanced internet functionalities/facilities. In this these, we discuss design and implementation of a P2P streaming system, which is based on ALMs. A prototype system, named NtouPCast, is built to justify out design considerations. In the NtouPCase, we completely implements all necessary functions to deal with Peer join, leave, failure, and redirect. Besides, we pay attend to issues on frame buffer management so that skews of viewing-frame between peers can be minimized. From intensive tests in real environment, we show our prototype system can work equally well, subject to network dynamics, peer heterogeneity and unexpected peer behaviors.
50
Der-Hua, Wu, e 吳德華. "The Radio Positioning Simulation System Using AM Broadcast Stations". Thesis, 1993. http://ndltd.ncl.edu.tw/handle/43224979003647159634.
Testo completoAbstract (sommario):
碩士國立中央大學
資訊及電子工程研究所
81
In this thesis, a relative time positioning algorithm is proposed to determine the three-dimensional coordinates of a measured point. It requires four transmitters. One provides the reference timing signal and the others receive and retransmit it to the measured point. The receiver at the measured point receives the timing signal from each of four transmitters, then detects three propagation time delays and uses three formulas to determine the position. We will make use of the existing AM broadcast stations with hybrid AM-BPSK modulation to accomplish the positioning measurement. The coverage area of AM propagation wave is limited so that this algorithm should provide the measurement in the local positioning region. The handoff is necessary during the measured point moving from one to another local positioning region. Therefore, using the handoff algorithm described in this thesis the positioning measurement can be executed in any region. In addition to describe the whole system principles, this thesis places emphasis upon the hardware and software design. The proposed positioning system possesses some superior characteristics. It merely adds some equipment in the AM station and then we can achieve the positioning measurement using the user equipment designed in this thesis. Hence, it is a convenient and accurate Radio Positioning System (RPS).