ZTE help Indian operator Reliance to build 100G metro optical networks

Recently, ZTE announced with India Reliance Communications (hereinafter referred to as "Reliance") signed a 100G OTN optical transport network orders. Over the next three years, ZTE will provide two cities in Pune and Hyderabad 100G optical transmission network design, site survey, installation, commissioning, maintenance and other services. ZXONE Series devices meet the Reliance offer comprehensive multi-service access and high integration requirements. Low TCO is a major factor in the ZTE she won this order.

Reliance in the Indian market share of 14.35%, is India's top four operators. But with mobile Internet access LTE era, the current network of SDH networks are increasingly unable to carry data traffic surge in demand. ZTE 100G OTN solutions to help Reliance rapidly into the era of 100G metro transport in Pune and Hyderabad two cities, greatly ease the pressure LTE network bearer.

It is reported that ZTE has the industry-leading OTN development platform, its high performance 100G OTN products, easy maintenance, low cost and other characteristics of the most Reliance recognized. ZTE 100G OTN has a high level of integration, from E1 / T1 to 100GE any access rate, client port supports smooth upgrade path 4-22, coarse dense wave unity; at the same time, the efficient performance of the product, to achieve port adaptive, DSS cross , L2 switching aggregation, CPRI transmission and other functions; in addition, OTN package supports the full overhead light layer / dielectric layer control, unified network management easy fault location and service configuration, effectively increasing the efficiency of operation and maintenance.

The basic principle of SDH

The basic principle of SDH

SDH level information structure is referred to as Synchronous Transport Module using STM-N (Synchronous Transport Mode, N = 1,4, 16,64), the basic module STM-1, four STM-1 synchronous multiplexing constitute STM- 4, sixteen STM-1 or four STM-4 synchronous multiplexing constitute STM-16, four STM-16 synchronous multiplexing constitute STM-64, or even four STM-64 synchronous multiplexing constitute STM-256; SDH using massive frame structure to carry information, each frame consists of longitudinal and transverse row 9 column 270 × N bytes, each byte containing 8bit, the entire frame structure is divided into a section overhead (Section OverHead, SOH) area, STM-N payload area and a management unit pointer (AU PTR) three regional areas, where section overhead area is mainly for network operation, management, maintenance and finger together to ensure that information can be transmitted properly flexible, it is divided into regenerator section overhead ( Regenerator Section OverHead, RSOH) and multiplex section overhead (Multiplex Section OverHead, MSOH); with a snap-pointer; payload area used to store bits of real information for business and a small amount of overhead bytes for channel maintenance channel management to indicate when the message payload area at the exact location of the first byte of STM-N frame so that the reception can correctly extract payload. SDH frame transmission when the press from left to right, arranged in order clusters of type stream from top to bottom sequentially transmitted every frame transmission time is 125μs, transmitted per second 1/125 × 1,000,000 frame of STM-1 in terms of per frame bit number 8bit × (9 × 270 × 1) = 19440bit, the STM-1 transfer rate is 19,440 × 8,000 = 155.520Mbit/s; STM-4 and the transfer rate is 4 × 155.520Mbit/s = 622.080Mbit/s; the transmission rate of STM-16 is 16 × 155.520 (or 4 × 622.080) = 2488.320Mbit/s.


When the SDH transmission traffic signal traffic signal to enter a variety of SDH frames to go through mapping, positioning and multiplexing three steps. ITU-T G.707 standard recommendations multiplex mapping structure as shown.

ITU-T G.707 standard recommendations multiplex mapping structure

Mapping is the signal to go through a variety of rate justification loaded into the appropriate standard containers (C), then add the path overhead (POH) forming a virtual container (VC) of the process, the frame phase deviation occurs is called frame offset.

Positioning the frame offset information that is incorporated into the tributary unit (TU) or management unit (AU) process, through tributary unit pointer (TU PTR) or administrative unit pointer (AU PTR) function to achieve.

The concept is relatively simple reuse, reuse is a plurality of signal adaptation into the lower-order channel layer order path layer, or a plurality of higher-order channel layer signal into the multiplexing process of adaptation by layer. Multiplexing is staggered by byte interleaving manner TU organized into higher order VC or the AU organized into STM-N process, since TU and AU pointer after each VC signal processing branch has phase synchronization, so that the complex process is synchronous with string theory and data multiplexing and conversion are similar.

SDH Background

Birth SDH technology has its inevitability, with the development of communications, information transfer requires not only a voice, as well as text, data, images and video. Coupled with the development of digital communications and computer technology in the 1970s and 1980s, has been found in the T1 (DS1) / E1 carrier systems (1.544 / 2.048Mbps), X.25 frame relay, ISDN (Integrated Services Digital Network) and FDDI ( Fiber Distributed Data Interface) and other network technologies. With the advent of the information society, people want modern information transmission network quickly and cost-effectively provide a variety of circuits and services, and the complexity of the bandwidth limitations of the above-mentioned network technology because of its monotony of business, expanded only in the original modify or improve within a frame has been of no avail. SDH is in this context to develop. In a variety of broadband fiber access network technologies, using SDH technology access network system is the most common. SDH solve the birth home due to bandwidth limitations behind the development of the medium and the backbone network and customers' business needs, and user generated between the access and core network "bottleneck" problem, while improving the lot of bandwidth transmission line utilization. SDH technology since the introduction of the 1990s, it has been a mature, standard technology, the backbone network is widely used, and the price is getting lower and lower, application SDH technology in the access network can be enormous bandwidth in the core network and technology advantages into access networks and take advantage of SDH synchronous multiplexing, standardized optical interface, a powerful network management capabilities, flexible network topology capability and high reliability benefits, benefit from long-term construction and development of the access network .

OTN development process

Through a new generation OTN G.872, G.709, G.798 ITU-T recommendations are canonical "digital transmission system" and "light delivery system." OTN will solve the traditional WDM networks without wavelength / sub-wavelength service dispatch capability, network capacity is weak, weak protection and other issues.

Optical transport network for IP services, IP transport requirements adaptation service has become an important issue in the further development of optical communication. Optical transport network from a variety of angles and provide a solution compatible with the existing technology in the premise, because the large number of applications SDH equipment, in order to solve the processing and transmission of data services, based on SDH technology developed MSTP equipment and has a large number of applications in the network, it is well compatible with existing technology, but also to meet the transfer function data services. But with the increasing processing power and requires more detailed data services particles, business demand for transport network presented two aspects: on the one hand the transmission network to provide a large pipeline, then generalized OTN technology (in the electric field is OTH, in the optical domain ROADM) provides a new solution that solves the SDH-based cross particles VC-12 / VC4 is small, scheduling more complex issues not meet service delivery needs of large particles, in part, to overcome the WDM System fault location difficult to point to point connection-oriented networking, network capacity is weak, network survivability and ability to provide a means shortcomings weak; on the other hand service optical transport network to propose a more detailed processing requirements, the industry also made a packet transport network solution, the main technologies involved include T-MPLS and PBB-TE and the like.

As network traffic growing demand for bandwidth, operators and system manufacturers have been constantly consider ways to improve service delivery technology issues.

Digital transmission network evolution from the original based T1 / E1 of the first generation of digital transmission network, experienced-based SONET / SDH second generation digital transmission network, to the development in the third generation of OTN-based digital transmission network. First and second generation transport network was originally designed for voice services specifically designed, though can also be used to transmit data and video services, but the transmission efficiency is not high. In contrast, the third-generation transport network technology, from the design to support voice, data and video services to support the bandwidth on demand (BOD) when with other protocols, quality cut of service (QoS) and optical virtual private net (OVPN) and other functions.

In 1998, the ITU Telecommunication Standardization Sector (ITU-T) formally proposed the concept of OTN. From the functional point of view, OTN can be transmitted in the form of all-optical subnet, and the use of light at the boundary of sub - electricity - light conversion. Thus, each subnet can 3R regenerator coupled to constitute a large optical network, as shown in FIG. Therefore, OTN transport network can be seen as the all-optical network evolution process of a transition application.

In the OTN functional description, the optical signal is wavelength (or center wavelength) to characterize. Optical signal processing may be based on a single wavelength, or based on a WDM group. (Based on other optical multiplexing, time division multiplexing, optical time division multiplexing, or optical code division multiplexing OTN, remains to be studied.) OTN can be achieved in the optical domain transfer service signals, multiplexing, routing, monitoring, and to ensure its performance and survivability. OTN can support a variety of top business or protocols, such as SONE / SDH, ATM, Ethernet, IP, PDH, Fibre Channel, GFP, MPLS, OTN virtual concatenation, ODU multiplexing, is the ideal foundation for future network evolution. More and more operators worldwide start constructing a new generation of OTN-based transport networks, systems manufacturers have also introduced a more OTN features of the product to support building the next generation transport network.

WDM and SDH difference?

SDH, called "digital synchronization sequence", mainly used for drop multiplexing E1 (2M), E3, T3, STM-1 ~ STM-64 and other ranking data transmitted. And it can be various types of data such as: ATM, E1, FE, GE and other types of data transmission unified package, compatibility strong;WDM, called wavelength division multiplexing system with DWDM and CWDM points, primarily distinguished by the frequency of the light wave signals of different channels used to transmit signals, which can carry include transmission SDH, FCOM, GE and other large particles of business, Mainly used for inter-provincial and provincial transport network.