NO.OF GBPS DATA TRANSMITED THROUGH THIS METHOD!!

OFDM(orthogonal frequncy division multiplexing)

OFDM is a high speed data trancfer method.using this method we can transmit data at a rate of 100gbps.

To overcome the effect of multi path fading problem available in UMTS, LTE uses Orthogonal Frequency Division Multiplexing (OFDM) for the downlink - that is, from the base station to the terminal to transmit the data over many narrow band careers of 180 KHz each instead of spreading one signal over the complete 5MHz career bandwidth ie. OFDM uses a large number of narrow sub-carriers for multi-carrier transmission to carry data.

Orthogonal frequency-division multiplexing (OFDM), is a frequency-division multiplexing (FDM) scheme used as a digital multi-carrier modulation method.

OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates. The basic LTE downlink physical resource can be seen as a time-frequency grid, as illustrated in Figure below:

The OFDM symbols are grouped into resource blocks. The resource blocks have a total size of 180kHz in the frequency domain and 0.5ms in the time domain. Each 1ms Transmission Time Interval (TTI) consists of two slots (Tslot)

Each user is allocated a number of so-called resource blocks in the time.frequency grid. The more resource blocks a user gets, and the higher the modulation used in the resource elements, the higher the bit-rate. Which resource blocks and how many the user gets at a given point in time depend on advanced scheduling mechanisms in the frequency and time dimensions.

The scheduling mechanisms in LTE are similar to those used in HSPA, and enable optimal performance for different services in different radio environments

Advantages of OFDM

The primary advantage of OFDM over single-carrier schemes is its ability to cope with severe channel conditions (for example, attenuation of high frequencies in a long copper wire, narrowband interference and frequency-selective fading due to multipath) without complex equalization filters.

Channel equalization is simplified because OFDM may be viewed as using many slowly-modulated narrowband signals rather than one rapidly-modulated wideband signal.

The low symbol rate makes the use of a guard interval between symbols affordable, making it possible to eliminate inter symbol interference (ISI).

This mechanism also facilitates the design of single frequency networks (SFNs), where several adjacent transmitters send the same signal simultaneously at the same frequency, as the signals from multiple distant transmitters may be combined constructively, rather than interfering as would typically occur in a traditional single-carrier system.

!!WOW !! FIBER CREATED!! OPERATS AT 99.7% SPEED OF LIGHT!!

!!record !! fiber Created, that operates at 99.7% speed of light!!!

Researchers at the University of Southampton in England have produced optical fibers that can transfer data at 99.7% of the universe’s speed limit: The speed of light. The researchers have used these new optical fibers to transfer data at 73.7 terabits per second — roughly 10 terabytes per second, and some 1,000 times faster than today’s state-of-the-art 40-gigabit fiber optic links, and at much lower latency.

The speed of light in a vacuum is 299,792,458 meters per second, or 186,282 miles per second. In any other medium, though, it’s generally a lot slower. In normal optical fibers (silica glass), light travels a full 31% slower. Light actually travels faster through air than glass — which leads us neatly onto the creation of Francesco Poletti and the other members of his University of Southampton team: A hollow optical fiber that is mostly made of air. 


It might seem counterintuitive, transmitting light down fibers made primarily of air, but look around you: If light didn’t travel well through air, then you’d a hard time seeing. It isn’t like researchers haven’t tried making hollow optical fibers before, of course, but you run into trouble when trying to bend around corners. In normal optical fiber, the glass or plastic material has a refractive index, which causes light to bounce around inside the fiber, allowing it to travel long distances, or Remove the glass/plastic and the light just hits the outer casing, causing the signal to fizzle almost immediately. The glass-air interface inside each fiber also causes issues, causing interference and limiting the total optical bandwidth of the link.

!! 43 TBPS OVER A SINGLE FIBER!!

43Tbps over a single fiber: World’s fastest network would let you download a movie in 0.2 seconds

A research group at the Technical University of Denmark (DTU), which was the first to break the one-terabit barrier in 2009, has today managed to squeeze 43 terabits per second over a single optical fiber with just one laser transmitter. In a more user-friendly unit, 43Tbps is equivalent to a transfer rate of around 5.4 terabytes per second — or 5,375 gigabytes to be exact. Yes, if you had your hands on DTU’s new fiber-optic network, you could transfer the entire contents of your 1TB hard drive in a fifth of a second — or, to put it another way, a 1GB DVD rip in 0.2 seconds.



The previous record over a single optical fiber — 26 terabits per second, set by Karlsruhe Institute of Technology way back in 2011 — had remained unbroken for a surprisingly long period of time. DTU set a series of single-fiber world records in 2009 and 2011, but had since been forced to sit in Karlsruhe’s shadow — until now. This was obviously a pain point for the DTU researchers — the press release [Danish] announcing the new world record actually calls out Karlsruhe by name. I guess a bit of friendly competition never hurt anyone though, right?

The main thing about this world record is DTU’s use of a single laser over a single fiber. There have been plenty of network demonstrations of hundreds or even thousands of terabits (petabits) per second with multiple lasers over multiple fibers — but those demos are so far removed from the reality of fiber-optic networking that they’re not really worth discussing. When we talk about commercial fiber-optic links, we’re nearly always talking about single-laser-single-fiber, because that’s what the entire internet backbone is built upon. In other words, the techniques used by DTU to hit 43Tbps actually have a chance of making it into real-world networks in the next few years. You might soon be able to download a TV show or movie in quite literally the blink of an eye. [Read: Infinite-capacity wireless vortex beams.]

How did the DTU hit 43Tbps and steal the world record away from Karlsruhe? Well, rather amusingly, they kind of cheated. While the researchers did only use a single laser, it used multi-core fiber. This is still a single filament of glass fiber, but it has multiple individual channels that can each carry their own optical signal. In this case, DTU used multi-core optical fibers with seven cores, produced by Japanese telecom giant NTT. Back in 2011 when Karlsruhe set its 26Tbps record (with a single-core fiber), multi-core fibers were both difficult and expensive to manufacture — now, in 2014, it would seem the bugs have been ironed out and NTT is moving ahead with commercial deployments. 

400 GBPS TRANSFER SPEED ACHIEVE! NOW !!!

43 TERA BITS PER SECOND!! YES NEW RECORD!!

A new data transfer record: 43 terabits per second

A team in Denmark has broken the world record for single fibre data transmission, achieving a transfer rate of 43 terabits per second over a distance of 41 miles (67 km). They also report a speed of 1 petabit (1000 terabits) when combining multiple lasers.

 In 2009, a research group at the Technical University of Denmark (DTU) was the first to break the 1 terabit barrier for data transfer. Their record was shattered in 2011, when the Karlsruhe Institute of Technology in Germany achieved 26 terabits per second. Now, DTU have regained the title, demonstrating 43 terabits per second (Tbps) through a single optical fibre. This is fast enough to download a 1GB file in about 0.0002 seconds – or the entire contents of a 1TB hard drive in 0.2 seconds.

The Danish team's effort may seem almost excessive, to the point of comedy. However, current trends show that insanely fast transfer speeds like this will be necessary in the relatively near future. Like a digital explosion, the Internet continues to expand and grow exponentially – doubling in size every two years. Improvements in video quality and image resolution mean the amount of data appearing online is mushrooming to enormous proportions, while at the same time, billions more people are gaining access to the web.

This also requires energy which currently generates about two percent of CO2 emissions. Therefore, it is essential to identify solutions for the Internet that make significant reductions in power consumption while simultaneously expanding the bandwidth.

DTU's researchers achieved their latest record by using a new type of optical fibre borrowed from the Japanese telecoms giant NNT. This type of fibre contains seven cores (glass threads) instead of the single core used in standard fibres, making it possible to transfer even more data. Despite the fact that it comprises seven cores, the new fibre does not take up any more space than the standard version.

As to when speeds in the tens of terabits range might be affordable to mainstream consumers, we reckon sometime in the 2030s.