Spatial Decoupling methods for Digital Suscriber Line

Spatial Decoupling methods for Digital Suscriber Line In this paper, we present a novel method of spatial decoupling method to the pre- and post-processing of bundled digital subscriber line (DSL) systems using polynomial matrix decomposition algorithms. The proposed algorithm introduce a novel analysis and synthesis frequency splits in addition to upper frequency limits that play a major part in achieving the expected data rates. Instead of the traditional discrete multitone (DMT) architecture, sophisticated modulation structures known as filtered multitone (FMT) precoder for the downstream, and its upstream counterpart an inverse FMT equalizer are evaluated. Simulation results confirm that per-band equalization of polynomial matrices can enhance data rates by using this proposed spatial decoupling approach for DSL lines. Index Terms- Polynomial Matrix Decomposition, Filtered Multitone, DSL, DMT, WHAT IS OFDM? In this paper, we present the foundation for a future generation of spatial decoupling method to the pre- and post-processing of bundled digital subscriber lines (DSL) systems. The paper proposed a new analysis and synthesis frequency splits in addition to upper frequency limits that play a major part in achieving the expected data rates. Instead of the traditional discrete multitone (DMT) architecture, a more sophisticated filtered modulation structure known as filtered multitone (FMT) is proposed in the downstream, and its upstream counterpart an inverse FMT operation. DSL have for decades used DMT to allow the transmission of several high speed broadband signals through the twisted pair copper wire at the same time. Each broadband signal is on a separate frequency or, more specifically, assigned to independent DSL tone/ channel. For instance, what we call Channel 2 occupies 54 MHz-60 MHz. Within each channel used for NTSC analog TV transmission, one will find an amplitude modulated (more specifically, vestigial sideband amplitude modulation or VSB-AM) visual carrier located 1.25 MHz above the lower channel edge, and a frequency modulated aural carrier 4.5 MHz above the visual carrier. A color subcarrier is located in between the visual and aural carriers, approximately 3.58 MHz above the visual carrier. When the cable industry made the jump to digital transmission several years ago, the modulation of choice was QAM. Each downstream QAM signal which is really a double-sideband, suppressed-carrier analog RF signal occupies the same six megahertz of bandwidth as an analog TV signal. The current method of QAM transmission is known as single carrier QAM (SC-QAM); the latter is true even when DOCSIS 3.0 channel bonding is used. Each channel slot carries only one modulated carrier a QAM signal hence, the SC-QAM moniker. The entire data payload transmitted in the channel modulates just that one QAM signal. Now imagine transmitting a large number of individual very-narrow-bandwidth QAM signals hundreds or even thousands within a given channel. A 6-megahertz-wide channel could, for example, contain up to 480 narrow QAM signals that are spaced only 12.5 kilohertz apart. Each of these narrow QAM signals, called a subcarrier, subchannel, or carries a small percentage of the total payload at a very low data rate. The aggregate of all of the subcarriers data rates comprises the total data payload. For improved spectral efficiency, the subcarriers actually overlap one another. This sounds counterintuitive, because one would be inclined to think that, if signals overlap each other, interference will occur. With OFDM, the subcarriers are mathematically orthogonal to that is, distinguishable from one another, which takes care of the interference concern. Orthogonal in this case means the subcarriers are independent such that there is no interaction between them despite the overlap in frequency. The concept is analogous to having zero inter-symbol interference (ISI) in the time domain. Orthogonality is achieved by spacing the subcarriers at the reciprocal of the symbol period (T), also called symbol duration time. This spacing results in the sinc (sin x/x) frequency response curves of the subcarriers lining up so that the peak of one subcarriers response curve falls on the first nulls of the lower and upper adjacent subcarriers response curves. Orthogonal subcarriers each have exactly an integer number of cycles in the interval T. With OFDM, the concept of a six-megahertz-wide channel no longer is necessary. The previously mentioned NCTA paper includes an example of a downstream OFDM channels bandwidth being as wide as 192 megahertz, supporting some 15,200 subcarriers spaced 12.5 kilohertz apart. Along with the subcarriers are pilot tones for synchronization and other purposes. There are guard bands at each end of the 192- megahertz-wide channel, resulting in a useful bandwidth of 190 megahertz. The useful symbol duration time is 80 microseconds (ÂÂ µs), the reciprocal of which is the previously noted subcarrier spacing: 1/0.000080 second = 12,500 hertz. The total symbol duration time is 84.13 ÂÂ µs, which includes what are called guard interval samples and symbol shaping samples. Assuming 4096-QAM on each subcarrier, the 192- megahertz-wide channel supports 2.11 Gbps without FEC. Other example channel bandwidths discussed are 96 megahertz and 48 megahertz. All of these particular OFDM channel bandwidths are multiples of six and eight megahertz, which allows easier coexistence with todays North American and European channel plans. If the spectrum doesnt have enough room for a full OFDM channel, some of the subcarriers can be nulled, which effectively turns them off. OFDM can be used for multiple access say, as OFDMA in the upstream by assigning different subcarriers to different users. OFDM also can be used in combination with such other multiple access schemes as time division multiple access (TDMA). In this case, the full channel would be assigned to one user at a time, and the multiple access achieved via time division. When combined with TDMA, OFDM can deliver a very high peak-data rate, which may be desirable for some applications. Pros And Cons Advantages of OFDM include the ability to adapt to such degraded channel conditions as severe microreflections without the need for complex adaptive equalization algorithms. One reason for the latter is that a very narrow bandwidth subcarrier typically experiences what is known as flat fading when micro-reflections affect channel response. This is in contrast to a SC-QAM signal that occupies the full channel bandwidth and is susceptible to amplitude ripple (standing waves) across that full bandwidth. Each OFDM subcarrier sees just a tiny portion of the ripple, which for the most part affects only the amplitude of the narrow subcarrier. Compensating for what amounts to little more than an amplitude variation among subcarriers simplifie s the fix. Likewise, the composite OFDM signal is more robust than SC-QAM in the presence of interference. For example, a narrowband ingressor like a pager transmitters signal affects only a few subcarriers rather than taking out the full channel. Depending on the severity of the interference, FEC may be able to deal with it. Alternatively, the OFDM transmitter simply can disable a few subcarriers to avoid narrowband interference on problem frequencies. Inter-symbol interference is generally less of a problem with OFDM because of the low data rate per subcarrier. As discussed earlier, the overlapping nature of OFDMs subcarrier transmission provides high spectral efficiency. If information about the channels condition is sent back to the transmitter by the receiver, then adaptive modulation, FEC and power allocation can be applied to all subcarriers, blocks of subcarriers or even individual subcarriers. In other words, some subcarriers in the channel can use higher orders of modulation than other subcarriers, some subcarriers can have more aggressive FEC, and the power of individual subcarriers can be varied all on an as-conditions-warrant basis. OFDM does have a few disadvantages: It is susceptible to frequency and clock errors, although the pilot carriers that accompany the subcarriers help to mitigate this by providing the receiver a means of synchronization. OFDM has a high peak-to-average power ratio (PAPR), but a spectrum full of SC-QAM signals does, too. While PAPR-reduction techniques are available for OFDM and OFDMA, they probably wont be necessary in a typical cable network. Some of OFDMs high spectral efficiency is reduced by the use of cyclic prefixes, which help to maintain subcarrier orthogonality. Why Bother? You may be wondering why one would even consider a new PHY for a possible future version of DOCSIS. After all, SC-QAM works well, and channel bonding can be used to significantly increase data throughput. The good news is that OFDM isnt some new-fangled technology without a proved history. It is used in Wi-Fi networks, worldwide interoperability for microwave access (WiMAX), long term evolution (LTE), digital audio broadcasting (DAB), ultra-wideband (UWB) and Europes digital video broadcasting (DVB). A variation of ODFM also is used in asymmetric digital subscriber line (ADSL) and very high-speed digital subscriber line (VDSL). The previously discussed advantages bring a lot of signal transmission flexibility to the table. When OFDM is combined with more powerful FEC like LDPC, higher orders of modulation can be used within the limits of the channel conditions, of course. Toss in new frequency splits and upper frequency limits seem improving the future DSL systems, supporting far higher data rates than are possible the existing DMT-QAM.

Death of a Salesman by Arthur Miller Essay -- business trip, aristotle

The tragic tale Death of a Salesman fulfills Aristotle’s definition of a tragedy to a great degree. The play conforms to Aristotle’s definition seamlessly for the factors of plot, thought, diction, and spectacle, satisfying all of the key necessities for each section. Character, also, fits well with his definition, but there are a few deviations from Aristotle’s perfect tragedy that prevent a seamless fit. The use of a chorus is completely ignored in this play, but being one of the least important elements, it does not affect the overall worth of the play. When the individual parts of the play are examined, it satisfies Aristotle’s requirements for a perfect tragedy. In Aristotle’s definition of a perfect tragedy he delegates plot as the most important component of the play. According to Aristotle, plot can be defined as the cause-and-effect chain that presents the incidents to the audience. This chain must have rising action, a climax, and falling action, as well as being self-contained, complex, and contain a significant meaning (McManus). Arthur Miller’s Death of a Salesman satisfies all of these stipulations completely. The structure of Death of a Salesman has a beginning, middle, and end as required by Aristotle, however the order of these are not necessarily true to form. Some events that occur in the middle of the play should be at the beginning if examined as purely a cause and effect chain, and some events at the beginning should be at the middle. The inciting action when Biff discovers his father’s infidelity during one of Willy’s business trips. The climax of the play is the argument between Willy and Biff where Biff realizes that Willy is a cause of his short comings. Biff’s statement, â€Å"And I never got anywhere becau... ...financial situation in which they live, enticing pity from the audience. This limited use of spectacle would be applauded by Aristotle. Arthur Miller succeeds as playwright with Death of a Salesman, at least according to Aristotle. He successfully blends the elements of plot, character, thought, diction, and spectacle in to a tragic tale that Aristotle would deem perfect. He took all of Aristotle’s requirements and with a few deviations put forth a true tragic tale. All things considered, Aristotle would commend this as a perfect tragedy. Works Cited Arthur Miller's Death of a Salesman. Dir. Volker Schlöndorff. By Arthur Miller. Perf. Dustin Hoffman and John Malkovich. CBS Presents, 1985. DVD. McManus, Barbara F. "Outline of Aristotle's Theory of Tragedy." Outline of Aristotle's Theory of Tragedy. The College of New Rochelle, Nov. 1999. Web. 01 Feb. 2014.

Record Controls

Record Controls Valerie Chacon Axia College November 21st, 2010 HCR 210 Lisa Israel Today, there are many security measures within small, medium and large facilities. There are secure rooms, passwords, access codes and other things to keep records safe. If these security measures are not in place, then the medical facility could be at risk for letting confidential information get to the wrong people. There are differences and similarities in ways each medical facility handles their medical records. Small, medium, and large facilities seem to use similar security measures within an electronic record filing system.Most facilities use passwords, usernames, and access codes. With this said, only certain staff members have these access codes. Sometimes, one person has these access codes depending on how big the facility is. Sometimes files are only kept in a filing cabinet that is locked, along with the building locked when no one is there. Many small facilities seem to still use paper re cords. Paper records can have their positives and negatives. Small facilities do not have many doctors which in this case they know many of their patients on a personal level. This is a good aspect, especially for looking up records.Many small facilities keep their records in a secured room that is locked. Some facilities use only one person with one key, and others have access codes to get into the secured room. Depending on the facility and how many patient records there are, they all follow certain rules in their facility. Some facilities follow color coded record filing, numeric filing, and alphabetical filing. Some facilities keep their record in one place, other facilities have 2. If it is paper filing and they have 2 secure rooms, usually one room is for current patients and the other room is for old patient record.Records are kept from eight to ten year, depending on facilities regulations, and then destroyed of properly according to privacy information (Robinson, 2010). Wit h smaller facilities, this may happen more often than a larger facility, most likely because they use the paper filing system. With medium to large facilities, these facilities seem to use the electronic filing system. Although some medium and large facilities still use paper filing, more medium and large facilities have and are converting to electronic filing. The electronic filing systems seem to be more convenient for larger facilities.The hassle of so many patient records in paper form can be huge responsibility. This is why electronic filing is so much easier. The less hassle for records management, the less stress. Many larger facilities agree that electronic filing is much easier and can help control the records management. The storage for electronic filing is much easier too. The only downside with electronic filing is the unknown system downs for restoring or upgrading system requirements (Robinson, 2010). Sometimes when the system goes down, they may have to write down rec ords until systems are up and running.Each facility follows a strict policy in the scenario. Large facilities handle more patient records than a small and medium facility. There are not many facilities that still have paper records management. If security procedures are not followed correctly then there can be major problems. Mix up’s of patient records are at stake, patient confidentiality could be at stake. All facilities follow procedures to ensure patient privacy. In certain cases that a file may be lost or stolen, there are rules regulations and consequences on behalf of the facility. This is why it is so important for security measure to be met.It is the law that all confidential information is secured and locked, whether it is in a room or a filing cabinet. If a fire were to happen, patient records could be damaged, this is why it is equally important to have a sprinkler system set up in the case of a fire (Green & Bowie,  2005). No matter if the facility is smal l medium or large, each medical facility follows security Measure’s to ensure record confidentiality and keeping records safe. The follow specific guidelines and if these guidelines are not followed, serious consequences can come to the facility and the staff members.If it is a single staff member that is not following guidelines, this staff member can be written up and/or subject to termination from their job/career. To ensure this does not happen, many facilities offer training and most need a degree in having a job like this.References Robinson, S. (2010, November  7). Interview Data Thread: Group C []. Message posted to http://University of Phoenix class forum, HCR/210 Patient Records: Keeping it Real course website. Green, M. A. , & Bowie, M. J. (2005). Essentials pf Health Information Management: Principles and Practices. Clifton Park , NY: Thomson Felmar Learning.

What Is CORDS (Connecting Organizations for Regional Disease Surveillance)

Borders between countries are purely human invention and abstraction – they exist for us because we believe in them. But for infectious diseases there are no borders – they travel freely from nation to nation, no matter how hard we try to prevent it. A disease that appears in one country cannot be considered only that particular country’s problem – it is a problem of the entire world, as current situation with Ebola virus clearly shows. Infectious diseases cannot be ignored – their impact is not limited to disrupting economic and social stability. The entire humankind can be wiped out if a sufficiently lethal and contagious new infection emerges and is not kept in check during the initial stage of its spread. That was precisely the reason for the creation of CORDS (Connecting Organizations for Regional Disease Surveillance). It was founded in 2009 and intended as a platform for a world-wide international disease surveillance network. Right now regional disease networks are pretty much autonomous and communication between them leaves much to be desired, which leads to slower response to new threats, than necessary. CORDS is aimed to improve this situation, bringing regional networks together, uniting them into one universal network that would swiftly and effectively react to any potential pandemics and biological weapon threats. With the help of CORDS and under the aegis of World Health Organization regional networks are supposed to share information, experience and expertise to develop and prepare new, more effective and universal response patterns to the potential outbreaks of new and old diseases. The best tools and practices are to be shared among the healthcare specialists across the world, and their combined experience is to be used in preparation of case studies, education courses, innovative approaches to disease treatment and general technological data. As a result, each new outbreak is to be met in a cohesive way, by unifying the efforts of the entire human race. However, CORDS is well aware of the fact that certain Third World regions, stricken with poverty, ignorance and civil strife are much more susceptible to infectious diseases. What’s more, they are not simply in greater danger, in their current state they represent a threat to the entire world, because a new lethal disease may emerge in one of such regions and remain unnoticed for a considerable amount of time. And after it is noticed it may turn out to be too late to effectively counteract it. That is why one of the major efforts initiated by CORDS is establishment of regional partnerships in Southern Africa, Middle East and South-Eastern Asia, to provide them with the resources necessary for early detection of new pathogens. All this taken into account, CORDS was and is a strictly non-governmental organization, with its funding coming from the Rockefeller Foundation, the Bill Melinda Gates Foundation and the Skoll Global Threats Fund. It follows its own vision of how global health should be achieved, promoting the concept of One Health – i.e., holistic approach to fighting the disease, based on the assumption that human, animal and environmental health are all interconnected, and thus it’s necessary to work on these three spheres simultaneously. This approach seems to be more and more logical, as recent years clearly show that animal health is just as serious global health issue as our own. New epidemics most often seem to be spreading via animals, both domesticated and wild, and without understanding the principles that rule their emergence we cannot hope to battle those that pose threat to humans. Hopefully, CORDS can play a vital role in it.