Fiber Optic Network Archives - Page 8 of 10

Why Is OTN Becoming More And More Important?

In an era of various services operating, telecom operators will be transformed into the comprehensive service providers of information and communications technology (ICT).The abundant services drive the higher demand for broadband services, directly manifesting the requirement for the ability and performance of the transport network. Owing to meet the needs of all kinds of new services, the Optical Transport Network (OTN) technology comes into being, playing a leading role in the transport network.

OTN, the next-generation backbone transmission network based on WDM techniques, lies in the optical layer network. Standardized by a series of ITU-T advice covering G.872, G.709 and G.798, it is the new generation of digital transmission network and optical transmission network. OTN is based on a fixed frame size with 3 key sections: Overhead, Payload, and Forward Error Correction (FEC). These OTN frames are routed across the network in a connection-oriented way. Similar to a synchronous digital hierarchy/ synchronous optical network (SDH/SONET) frame, the overhead carries the information required to identify, control and manage the payload to maintain the deterministic quality. The payload is simply the data transported across the network, while the FEC corrects errors when they arrive at the receiver. The number of correctable errors depends on the FEC type. The most common is GFEC described in the G.709 standard, which can identify 16 symbol errors and correct 8 symbol errors per frame. As is shown in Figure 1, the OTN concretely operates as follows. What OTN successfully deals with are the traditional WDM net working issues of missing wavelength, weak scheduling ability of subwavelength services, bad networking ability and poor protection ability. Combining the strength of optical-field handling with that of electrical-field treatment, it is the optimal technology for transmitting the large-particles broadband services, providing the huge transmission capacity, the completely transparent connection of end-to-end wavelength and subwavelength as well as the various protection at telecommunication level.

Figure 1:The operation of an OTN network

The core of most current operator networks is SDH/SONET, which has always offered good fault management, performance monitoring, predictable latency, a protection mechanism and, of course, synchronization. This very stable network has become the expected minimum in performance objectives for network operators today and is often described as having “five 9s” (and higher) performance, meaning at least 99.999% up time. On the basis of the current SDH/SONET managerial functions, ONT provides not only the complete transparency of communication protocols, but also the ability of end-to-end connection and networking for WDM, whose technology inherited the dual advantages of SDH and WDM. It solves the SDH issues that the cross particles based on VC-12/VC4 are too small to meet the transmission requirements of large particles services,causing the complicated schedule. At the same time, it also partly settles the WDM problems of the positioning difficulty due to a system fault, weak networking and poor ability and means to provide the network survivability. OTN reduces transport costs and delivers enhanced network and performance management functions. Forward error correction (FEC) algorithms improve the reach of the transmission links, helping to reduce regenerators and optimize the spectral efficiency. Additionally, an OTN “digital wrapper” includes many layers and components known from SDH/SONET but at enhanced performance levels.

The ever-increasing demand of broadband services has significantly contributed to the application of OTN, which is simpler and better than SDH/SONET and increases the scalability of WDM systems. OTN technology comes into being, not only following the development of the communication technology, but also impelling the transmission network to a better stage. What’s more, the transmission requirements of IP services and the adapter IP services OTN facing has become an important issue that the optical communication further develops. As the optimal choice for developing the transport network, OTN is becoming more and more important, and will be extensively applied to play a dominant role in the transmission network in the future!

Fiber Optics is the Ideal Way in Today’s and Future’s Application

As we see, fiber optic transmission has already been the efficient way to transmit a wireless signal and RF signal. Compared to coaxial cable, fiber optic cables has the advantages such as lower signal loss and lower weight, except this, it is also cheaper than coaxial cable. Only by these reasons, fiber optics play an important role in wireless networks. Next we will introduce several fiber optic product in different application for you.

Fiber Optic Transmitter and Receiver

The function of fiber optic transmitter, optical transmitter with AWG see at the figure, is transmitting the RF signal into an optical signal in 1.3μm, the input impedance of the fiber optic transmitter is 50Ω and the output is an optical signal whose brightness is synchronized with the RF voltage. An optical detector internal to the laser transmitter is used to monitor the output power and adjust the bias current of the laser to maintain a constant average optical output. It maintains the consistency in performance, the best linearity and the longest life of the system.

Fiber optic receiver use a high speed detector and for transmitting the optical signal to RF signal. It is usually used with fiber optic transmitter. Low noise linear gain stages boost the signal back up to the desired RF level. Our Fiberstore‘s all fiber optic receivers overtake consistent tests and keep stable and long-term performances.

Fiber Optic Cables and Fiber Optic Connectors

Well, based on the special characteristic of RF in fiber optic applications, single mode fiber cable is the choice for it. The fiber has a core and cladding size of 9/125μm, and the fiber optic connector mainly for the stability and coupling of the light. But in the RF/fiber optic system, angle polished connectors are used more often, such as APC, UPC. Due to them, they can reduce the optical reflections at the connector. At the same time, we need to know that reflection in the system can cause increased noise, dirt and so on, then the connector will cause higher connector loss but also reflections. So the connector need to keep clean, the right way to keep clean is that using 99% alcohol and lint free wipes, always replace the cap on the ferrule when the connector is not in use.

Applications

In Building public safety, Fiberstore’s technology and Bidi fiber optic transceiver deliver the signal across the fiber optic network for in-building signal distribution. The benefits of fiber optics are endless. Fiberstore’s modular devices transmit RF signal in fiber easily and they keep distortion-free communications in the building of emergency, fire and police radio RF systems. Facing with the system capacity and improving the reliability of the network. Fiberstore is toward the direction of lower telecommunication cost, safe and reliable for users.

In military aspect, Today’s global battlefields are sophisticated networks of Army, Navy, Coast Guard and Air Force defense organizations requiring robust, they need monitoring and tracking, as well as high quality voice, video and data communications, as for this requirements, Fiberstore RF solution unmatched performance for radio frequency transport applications ranging from low frequency through VHF, UHF to satellite-band transmissions. Fiber optic cables provide the highest performances for soldier’s safety in military applications. The figure shows the special connector that can be used in the military application. We are very strict with the design and quality of fiber optic connector.

With the developments of the Internet, wireless LAN technology and protocols such as IEEE 802.11, Fiberstore;s fiber optic transceiver technology provides flexibility in architecture design, extended radio frequency coverage and enhanced performance in the wireless spectrum, and provide higher ability for wireless users. Fiberstore is doing his best for faster and more reliable communications solutions.

Fiber Optics Based on Multi Point Fiber Distribution Systems

Multi point distribution system is the broad wireless technology used to deliver voice, data, Internet, and video services. It has been allocated for that deliever broadband services in a point to point or point to multi point configuration to residential and commercial customers. As a result of the propagating characteristics of signals so that the systems use a cellular like network architecture, though services provided are fixed, not mobile.

In some cases fiber distribution systems have an ability to connect several remote sites to one base station. One common application is that the repeaters based on a major building and others building such as RF shielding areas and basement which all located in a few miles repeater building. A and the repeater use the head end. A multiple fiber optic transceiver assembly at the base station is commonly called a “head end” The distance end of the fiber is called “remote hub” equipment.

We need to pay attention to that each fiber optic receiver output at the repeater site has individual pads to reduce the composite noise floor. For example, if used the 40dB, an additional 80 dB of combiner port-to-port isolation occurs. In real application, it is a good idea, including regard the taps at test point to read the RF levels. Just used for testing and protection. A similar system that when we used the WDM, if the numbers of fibers are reduced by 50% but a WDM must be added at each remote site and another WDM for each fiber added at the repeater site. In the 4 remote site example, it would be taking 8 WDM’s to operate all the fibers full duplex and 4 fiber optic transmitters would have to be 1550nm models. Then there also a point we need to be careful. Fiber optic transceiver is not frequency selective and the same unit can receive 1330 or 1550nm optical signals equally well. We also measured the noise performance and we are happy to inform you that in line with theory, optic splitters practically do not add any noise. No matter what output we tested, this means that your receiver connected to such network would also show very high quality readings.

When we use the fiber optic links in the fiber distribution system, sometimes we need fiber optical splitter to split the signal which carried. The systems designer has the choice of splitting either the optical or RF domain. The function of optical splitter is familiar to RF splitter. Other parts of the incoming fiber optic network are connected to the transmission of output, and the terminal device is connected and the another main part is its direct part. There are also splitters that divided the input into 2, 4 or more outputs. According to the structure and locations of fiber optic splitter, in the fiber optic network, we need different split ratios of splitter, such as 1×2, 1×4 and 1×8 splitter and so on. Moreover unused single mode fiber cable, specific products can see at 50m single mode, it also can strengthen the signal used for the RF over fiber systems between the connected buildings for data communication and spare fibers.

Fiber Optic Access Network Will Be The Main Force Of Internet Information Highway In The Future

As with the rapid development of social information, fiber optic technology and devices which are dedicated to provide transfer of a new business for WAN and fiber optic access network. Developments of MSTP and PON are the most representative. They are also the best solution to provide various new business in the MAN and fiber optic access network which are based on fiber optic transmission technology. As water to the fish, the developments of fiber optic access technology can not without the support and development of fiber optic access devices.

Due to the constantly updated fiber optic access technology and more and more manufacturers’ accession, nowadays the fiber optic access devices categories are more and more obvious, mainly divided into three categories:

Fiber optic connection elements, it is applied into telecommunications and computer network terminal connections, related product: Fiber optic patch cable, fiber optic connector and so on.
Fiber optic transceiver, it is utilized for computer network data transmission, related products: Fiber optic splitter, fiber patch panels and so on.
Fiber optic engineer devices and fiber optic testers, it is specially for large-scale project, related products: Fiber optic fusion splicer, fiber optic testers.

Next we will introduce these three fiber optic access devices with a representative products respectively, they are fiber patch cables, fiber optic splitter, fiber optic fusion splicer.

Fiber optic patch cable (shown as the figure）is fiber optic cable or fiber optical unit which without fiber optic connector, it is used in fiber distribution frames on various link roads. Fiber patch cables are also used in long distance local optical network, data transmission and private network, various testing and control system.

Fiber optic splitter （shown as the figure), someone calls it as fiber coupler, it belongs to optical passive components, it is used in the telecommunications networks, fiber cable television networks, subscriber loop system. Fiber optic splitters can be divided into standard coupler (double branch, unit 1 x 2, that is, the light signal into two power, for example, 1×2 fiber optic splitter, 1 x4 fiber optic splitter, 1 x 8 fiber optic splitter and so on), star/tree fiber splitters and wavelength division multiplexer (WDM, if the wavelength is a high-density separation and wavelength spacing is narrow, it belongs DWDM).

Fiber optic fusion splicer（shown as the figure) is mainly used in telecommunication for fiber optic cables construction and maintenance, it is applied into telecommunication operators, engineering companies, private network, also used in the production of optical passive and active devices and fiber optical modules for fiber splicing.

All above the fiber optic access devices highly improve the data transmission and processing capabilities of fiber optic access network, and at the same time they can bring two advantages:

First, it solved the long distance transmission problems of fiber line attachment,and made its coverage range more widely. In this way, then it can reduce the number of transit nodes through whole the coverage network, make the structure of the network easier.

Second, it satisfied people’s needs to various broadband business, and improve the quality of new business data. It solved the problem of traditional copper cable access network fundamentally and laid a good foundation for achieving the dream of FTTH. I believe that in the future, fiber optic access network will be the main force of internet information highway.

Present Great Developments and Expections for FTTH

FTTH, Fiber to the home, you know. It provides the final customer access technology. There is a situation that fiber optic cables are extended to the ONU (Optical Network Unit) based on the customer’s premises, it also supply the customer virtually unlimited bandwidth for all the applications such as video, voice and high speed data and the speed can reach up to 1G per customer. Related passive optical product: PLC splitter . And the FTTH is future proof, it becomes the only one technology that can meet the requirements for such high bandwidth, the FTTH architecture is shown at the Figure.

We know ONU is required for each client rather than for a group of up to several hundred customers. FTTH is not cost effective at this time, and is dependent upon advances in technology to provide a more cost effective bandwidth on fiber optic cables and effective ONU technology.

Well, FTTH will be many people’s preference. We can know after comprehensive knowledge that the easiest way to provide FTTH is to use passive 1:N optical splitter to divide the optical bandwidth roughly equally between the N customers. Alternatively, a single fiber can also apply for both directions od transmission using wavelength division multiplexing (WDM). The splitting of the optical power among many consumers in a PON (Passive Optical Network) has significant optical power budget.

Recent years FTTH has some developments, such as a proposal for the creation of a GNDG (gigabit national data grid), it can overcome the bandwidth communications requirements for the future and the proposal also allows the use of the alternative access technologies, already discussed, such as XDSL, coax or wireless to provide service at lower data rates. However, interfacing to such solutions may well cost nearly as much as the final FTTH infrastructure. In fact, WDM with optical splitters or optical amplifiers are the main technologies required to implement such a FTTH network. Now WDM systems can provide bandwidths of 40G per fiber, use 16 wavelengths at 2.5 G each, and hope it can reach 100 rerabits in the next 5 years.