Tag Archives: OTN networks

400G OTN Technologies: Single-Carrier, Dual-Carrier and Quad-Carrier

400G

In order to achieve 400G long-haul (LH) transmission, three 400G Optical Transport Network (OTN) technologies come into being to meet the needs: single-carrier 400G, dual-carrier 400G, and quad-carrier 400G. They differ from each other mainly in the number of wavelengths used for transmission. This post will reveal what they are and their respective pros and cons.

Single-Carrier for 400G OTN

Single-carrier 400G, or single-wavelength 400G, means there is 400G capacity on a single wavelength. The single-carrier 400G adopts high-order modulation formats such as PM-16QAM, PM-32QAM and PM-64QAM. Normally, a single-carrier for 400G optical transport network is used only in network access, metro, or DCI (Data Center Interconnection) transmission.

Single-Carrier for 400G OTN

Figure 1: Single-Carrier for 400G OTN

Take PM-16QAM (Polarization-Multiplexed-16 Quadrature Amplitude Modulation) as an example. PM refers to a process where the 400G (448Gbit/s) optical signal is separated into two signals and modulated to transmit in two polarization directions – X and Y, which can cut the original signal rate in half (224Gbit/s). QAM is a process of separating the signals in X and Y to further reduce the rate. 16 stands for 4 bits, which means the signal in X and Y is respectively divided into 4 signals and the rate will accordingly decrease to 1/4 on the basis of the previous 224Gbit/s. By using PM-16QAM, the signal rate at this moment becomes 56G Baud (the rate of electrical processing).

Note: Because in current circuit technology, 100Gbit/s has approached the limit of the electronic bottleneck. If the Baud continues to increase, problems like signal loss, power dissipation, and electromagnetic interference will remain a hassle, which will, even if solved, require tremendous costs.

PM-16QAM

Figure 2: PM-16QAM

Pros of Single-Carrier for 400G Optical Transport Network

  • Compared with the multi-carriers scheme, single-carrier 400G is an easier wavelength allocation solution with simpler structure and smaller size that can provide easy network management and low power consumption.
  • With higher-order QAM, single-carrier for 400G OTN network can increase signal rates and spectrum efficiency, which will significantly expand network capacity and increase the number of users to support.
  • Also, with high system integration, it can connect the separate subsystems into a complete one and make them work in coordination with each other and achieve the best overall performance.

Cons of Single-Carrier for 400G Optical Transport Network

Since single-carrier for 400G OTN network adopts more advanced QAM, it requires a higher OSNR (Optical Signal Noise Ratio) and greatly reduces transmission distance (less than 200km). Also, single-carrier is more susceptible to laser phase noise and fiber nonlinear effects. Therefore, it is the best solution only for some specific applications that don’t require ultra long-haul transmission distance, but need large bandwidth capacity.

Dual-Carrier for 400G OTN

Dual-carrier 400G, also named dual-wavelength 400G, offers 400G capacity via two 200G wavelengths. The dual-carrier 400G system based on the 2× 200G super-channel scheme adopts lower-order modulation formats like PM-QPSK (Quadrature Phase Shift Keying, a symbol represents two bits, which means the rate is reduced to 1/2), PM-8QAM or PM-16QAM. Dual-carrier for 400G optical transport network is applied in more complex metro networks to achieve 400G long-haul transmission.

Dual-Carrier for 400G OTN

Figure 3: Dual-Carrier for 400G OTN

Pros of Dual-Carrier for 400G Optical Transport Network

  • The spectrum efficiency of dual-carrier 400G has increased by more than 165%, with relatively high system integration, small size, low power consumption. Dual-carrier 400G is regarded as the most commonly-used technology for 400G OTN.
  • The span of dual-carrier 400G is longer than single-carrier 400G, which can reach up to 500km for commercial use. When deployed with low-attenuation fiber optic cable and EDFA (Erbium Doped Fiber Amplifiers), dual-carrier for 400G OTN network can cover more than 1000km, which can basically satisfy the 400G long-haul transmission application.

Cons of Dual-Carrier for 400G Optical Transport Network

Even with low-attenuation fiber optic cable and EDFA, dual-carrier 400G still fails to reach as long as quad-carrier 400G does, not suitable for ultra long-haul (ULH) transmission over 2000km.

Quad-Carrier for 400G OTN

Quad-carrier 400G refers to a solution that offers 400G capacity through four 100G wavelengths. It is achieved by constructing a 400G super-channel based on 100G PM-QPSK with four carriers, suitable for ultra long-haul (ULH) transmission over 2000km.

Quad-Carrier for 400G OTN

Figure 4: Quad-Carrier for 400G OTN

Pros of Quad-Carrier for 400G Optical Transport Network

  • Quad-carrier for 400G OTN network adopts the mature 100G transmission technology that has been widely-used for commercial purpose.
  • It can achieve ultra long-haul transmission of more than 2000km at relatively low cost.

Cons of Quad-Carrier for 400G Optical Transport Network

Quad-carrier 400G system makes sense only when spectrum compression technology is introduced to improve spectrum efficiency, and the 100G chip is upgraded to solve the problems of integration and power consumption. Otherwise, a 400G system built on the current 100G chip is essentially a 100G system.

Conclusion

In all, 400G long-haul transmission is mainly realized by single-carrier, dual-carrier and quad-carrier. Single-carrier for 400G OTN network can only cover a distance of less than 200km; dual-carrier for 400G OTN network is the ideal solution for MAN transmission (with PM-16QAM) and medium long-haul transmission (with PM-QPSK); quad-carrier for 400G OTN network has the same transmission distance as 100G and is appropriate for ULH transmission. As global data traffic keeps climbing, there is no end to bandwidth demands. While it may take time to transit to 400G, you can learn about What’s the Current and Future Trend of 400G Ethernet? to make preparations first.

Original Source: 400G OTN Technologies: Single-Carrier, Dual-Carrier and Quad-Carrier

100G Global Market Has Got into the “Blowout Times”

With cloud computing, networking, the Internet and other new demands of future broadband transmission powered, the “short board” of the existing 10G/40G wave subsystem’s ability gets increasingly prominent, and 100G has gradually shifted from behind the scenes of commercial technology research toward the front. Around the world, 100G commercial deployment starts hotly. In China, the domestic development is rapid in recent years. The three operators have opened 100G Central Purchasing gradually to promote improvement of the industry chain continuous.

Global Commercial Deployment Accelerated

Ovum data has shown that, since the global scale deployments starting 100G in 2012, 100G market is up to 943 million dollars fivefold than in 2011. The growth of the global market size of 100G is so rapid. The agency has predicted that by 2016, 100G optical networking market will maintain an annual growth rate of over 100%. Dell’Oro Group report also points that the industry is moving towards next generation networks to 100G-based rapid transformation, and the annual compound growth rate of 100G will be up to 120% in the next five years.

The industry is optimistic about 100G market because the bandwidth telecom operators are facing pressure and 100G technology is mature. On the one hand, the bandwidth pressure has to be placed in front of the operator’s most pressing issues. On the other hand, in the past year, 100G relevant technical standards have matured, and achieved innovations and breakthroughs in the pattern, multiplexing, and many other technical areas, ready to do a large-scale pre-deployment preparations. 100G industry chain has been basically mature, and the price is already suitable scale deployments. The deploy volume will continuously improve the cost performance of 100G as well as other products.

Currently, the global super-broadband network construction is accelerating, a year around the world to deploy 100G fiery. In Europe, including the Netherlands KPN International, French SFR, Denmark TDC and many other leading global telecom operators, endorse efforts to build 100G commercial WDM network as 100G solution is recognized. Last November, the Angolan mobile operator UNITEL build Africa’s first 100G-wave splitting networks. In early 2012, the Latin American regional operator TIM successfully deployed the world’s first 100G coherent G.653 fiber based WDM networks, which achieved a breakthrough in G.653 fiber WDM transmission. In 2012, the CIS region has also launched a commercial network construction 100G. Poland GTS, Russia Rostelcom, Russia Megafone, Russia MTS, Belarus Beltelecom and other operators are actively deployed 100G networks.

It is worth mentioning that the CIS region is vast, 100G projects often are based on long-distance transmission, which is more demanding equipment manufacturers programs, such as the construction of Russia’s Rostelecom 100G network reached 25,000 kilometers. Russia’s Megafone is building 100G long-distance network cross Eurasia. It is reported that two projects are undertaken by Huawei Technologies, whose coherent 100G solution is based on flexible scheduling OTN architecture, using soft decision leading technology, modulation technique and DSP (digital signal processing) algorithms, providing the industry’s best long-distance transmission performance, and can support 2,500 kilometers without electricity relay transmission. It is particularly appreciated by CIS operators.

Three operators have turned Central Purchasing

The acceleration of global commercial 100G promoted the maturity of 100G equipment and devices in certain extent, especially the realization of ultra-long distance transmission projects, which further validates the maturity of related technologies.

Meanwhile, the Chinese 100G market has also ushered in the first commercial year. The education network and broadcasting have built the 100G OTN networks first. By 2013, with the three major domestic carriers 100G building turned into 100G, transmission network will be truly high-speed rail.

In the end of 2012, China Mobile launched the Central Purchasing of 100G, which opened the 100G prelude of the domestic commercial. It is reported that China Mobile the Central Purchasing cards total more than 1,500 for the first time, which is the world’s largest ever deployment of 100G so far. From the device level, China Mobile’s main deployment 100G OTN systems, building from Beijing – Shanghai – Guangzhou – Hong Kong’s Eastern OTN trunk. Published in April this year, the tender results, Huawei won the bid ITMC International Bureau Internet and eastern 100G +10 G OTN country dry, the flames of the western and northeastern successful communication 10G cadres of the country, Huawei, Shanghai Bell, winning the province 100G OTN section.

In early May, China Unicom 100G WDM experimental network project settled, the project marks China Unicom’s 100G WDM Evolution Plan has entered the final stage of implementation of the deployment of the network. The experimental network project contains a total of two links, respectively, by two vendors bid. Huawei forefront of the industry with the current soft decision 100G technology, the construction of this project’s experimental network 100G ultra-long haul transmission parts.

Technology leader to occupy the market

100G era, along with the acceleration of competing industrial chain, industrial centralization features will become more apparent. In the 10G market, the former three companies account for 45% of global share; in the 40G market, this accounted for a further increase to 68%; while to 100G era, Huawei, Alcatel-Lucent, Ciena these first three company’s market share has reached 90%. Another 10% were Infinera, Cisco, Nokia Siemens and other manufacturers divided.

Face of market opportunities, 100G equipment manufacturers showed positive, but only preliminary extensive R & D investment and accumulated abundant technology manufacturers in order to win the customer 100G testing. Alcatel-Lucent, Huawei and other related technology research earliest, because Huawei attaches great importance to the technical lead. Ovum data show that in the first quarter of 2012 before, Alcatel-Lucent is also ranked first; After this, Huawei has a rolling four quarter, 34% of the market share leapt to the top.

Huawei 100G perfect solution containing soft decision 100G / hard decision both, 100G OTN, 100G online OSNR testing, as well as the maturity and 100G router docking. According to Huawei Transport Network Product Line CEO Wang Weibin introduction: “In China Telecom and China Mobile tests, Huawei is the only way to provide both soft decision and hard decision 100G manufacturers. Moreover, Huawei’s 100G in the transmission performance, system stability, etc. also has obvious advantages. “which, in the Chinese mobile 100G WDM network test now, Huawei is also the most comprehensive test items, covering the full range of OTN products 100G/40G, soft decision and hard decision, OTN cross, clock, protection switching and thermal cycling characteristics.
Published by FiberStore, industrial news – www.fs.com