Can the Hybrid CWDM-DWDM System Work for Higher Capacity?

When facing the capacity-hungry issue, have you ever hesitated over which WDM system should be choose? As the CWDM system is a more economical solution for limited expanding capacity while the expensive DWDM solution enables much higher capacity, which one should be chose is really a tough decision. In order to solve the issue, can we deploy a Hybrid CWDM-DWDM system, for not choosing a wrong solution to increase the network capacity? Thereby, both the bandwidth shortage with CWDM solution or the potential bankruptcy with DWDM solution can be avoided. Let’s seeking the answer.

Can the Hybrid CWDM-DWDM System Work?

Can the Hybrid CWDM-DWDM system work for higher network capacity? The answer is yes. In fact, it is an ideal solution for boosting the network capacity, which is designed with merging DWDM and CWDM traffic seamlessly at the optical layer, taking full use of the WDM technology. In a hybrid CWDM-DWDM system, more channels can be added to deal with the limited capacity and reach in a CWDM system. That’s to say, the hybrid CWDM-DWDM system utilizes the DWDM technology to empower CWDM system, by integrating CWDM and DWDM equipment, which offers true pay-as-you-grow capacity growth and investment protection.

In short, the hybrid CWDM-DWDM system is a simple, plug-and-play option that enables more DWDM channels interleaved with the existing CWDM channels, for transmitting more data signals. It gets the utmost out of CWDM and DWDM technologies in a single system that greatly reduces the cost, simplifies the installation and keeps the system flexibility for bigger network capacity.

How to Build a Hybrid CWDM-DWDM System?

In general, a normal complete optical connection can be simply done by using a length of fiber patch cable to connect two fiber transceivers and then separately inserting the two transceivers into the ports of two switches. While in a hybrid CWDM-DWDM system, both the CWDM Mux Demux and DWDM Mux Demux should be added offering multiple channels to multiplex and demultiplex the signals. Here offers a typical 44 channel hybrid CWDM-DWDM system information for your reference.

From the figure, we can learn that the original CWDM system uses two 8 channel CWDM Mux Demux with wavelengths from 1470 nm to 1610 nm (20nm channel spacing). In order to add more channels for transmitting larger data signals, two pairs of DWDM multi-channel Mux/Demux are deployed separately under the pass band of the existing CWDM filters. In principle, deploying the DWDM multi-channel Mux/Demux in the 1530nm channel can create 25 100 GHz spaced DWDM channels. However, only 19 DWDM channels circled in the following figure are suitable to be added in the hybrid CWDM-DWDM system. It is also the same to the 1550 channel. Hence, this hybrid CWDM-DWDM system totally offers 6 CWDM channels and 38 DWDM channels with less deployment cost but easier installation.

Conclusion

If you come across the capacity-hungry issue and can’t make the decision about which WDM system should be choose for increasing your network capacity, you are highly recommended to deploy a hybrid CWDM-DWDM system. As an economical and future-proofing solution, the hybrid CWDM-DWDM system can completely deal with the issue of bandwidth shortage when building a CWDM system and avoid the potential bankruptcy for a DWDM system. You can just deploy a CWDM system first. Once the capacity the CWDM system offers can’t meet your requirement, you can add DWDM equipment in for more channels to transmit signals. All in all, the hybrid CWDM-DWDM system is an ideal choice that not only costs less for deployment but keeps the flexibility to increase the network capacity.

Choose the Right SFP+ Transceivers for CWDM Mux Demux

Nowadays, CWDM technology is very popularly used as a easy and economical way to extend the network capacity by carrying several signals with different wavelengths through a signal fiber. If your network capacity is not enough for your daily use, deploying a CWDM system is an ideal choice for you. As the CWDM Mux Demux should be finally linked with the switches in a completed CWDM system, the fiber patch cable and 10G CWDM SFP+ transceiver are required to finish the whole CWDM link. Hence, this paper will mainly introduce the CWDM Mux Demux and choose the right CWDM SFP+ transceivers for the CWDM Mux Demux, which may be helpful for you to fast build a CWDM system.

CWDM Mux Demux–Key Component for CWDM System

CWDM Mux Demux is a key component for CWDM system, which should work in pairs. As an optical module, it can act as a multiplexer or demultiplexer at either end of the fiber cable. This kind of optical Mux Demux is much easier to use than the DWDM Mux Demux, but can not support the network as long as that of the DWDM Mux Demux. In general, it can offers several kinds of wavelengths, usually from 1270nm to 1610nm (20nm spacing), to support the signal transmission at lengths up to 80 km. Meanwhile, the CWDM Mux Demux can be designed with 4 channels, 8 channels, 9 channels, 16 channels and 18 channels for transmitting different amount of signals. To better know how does this kind of WDM Mux work, the following figure offers a reliable 4 channel CWDM Mux Demux duplex transmission design.

From the figure above, we can learn that two CWDM Mux Demux are connected by a length of duplex patch cable, and they are designed with four channels multiplexing the 1470nm, 1490nm, 1510nm and 1530nm over the same fiber. To complete the transmission link, four pairs of CWDM SFP+ transceivers with 1470nm, 1490nm, 1510nm and 1530nm TX and RX should be separately inserted into the ports of these two WDM Mux Demux. When the CWDM system works, the four different signals from the left to the right will be multiplexed in the CWDM Mux, transmitted over the duplex fiber and demultiplexed in the CWDM Demux, and vice versa for the signals from the right to the left.

How to Choose the CWDM SFP+ Transceivers for CWDM Mux Demux?

As mentioned above, the CWDM SFP+ transceivers are required for building a CWDM system which should be correctly inserted into the SFP+ ports of the CWDM Mux Demux. Thereby, here offers three factors that should be taken into consideration when choosing the CWDM SFP+ transceivers for the CWDM Mux Demux.

The first factor is the working wavelengths of the CWDM SFP+ transceivers. In order to ensure the CWDM system performance, the SFP+ transceiver working wavelengths should be the same to the SFP+ ports of the CWDM Mux Demux. Just like the first figure, when the working wavelengths of the first pair of CWDM SFP+ transceivers are 1470 nm, the first ports of the two CWDM Mux Demux should be also 1470 nm, so that the signal with 1470 nm can be successfully transmitted in the CWDM system. As the CWDM working wavelengths are available from 1270 nm to 1610 nm and the channel spacing is 20 nm, there are 18 kinds of working wavelengths for CWDM SFP+ transceivers, as shown in the following figure.

The second factor is the compatibility of the CWDM SFP+ transceivers. As the third party transceivers are more cost effective than the original one, the former kinds are always the choices for most users. However, the users are always unassured about the quality and compatibility of the third party transceivers for their low price. Here FS.COM is recommendable who offers the CWDM SFP+ transceivers fully tested on most famous original brand switches like Cisco, Brocade, Juniper and Arista. FS.COM CWDM SFP+ transceivers are less expensive but can perform as well as the original branded transceivers, without the compatible issue.

The third factor is the transmission distance the CWDM SFP+ transceivers can support. Although the CWDM system can not support the transmission as long as the DWDM one, it still can reach the lengths 80 km. At present, 10G CWDM SFP+ transceiver can be available at lengths of 20km, 40km, 60km, 80km or even longer on the market. Hence, you can also choose the CWDM SFP+ transceivers according to the transmission distance you system needs.

Conclusion

Building a CWDM system for carrying more data signals is a good choice if the existing network has insufficient capacity. To ensure the performance of the whole CWDM link, it is necessasry to choose the right CWDM SFP+ transceivers for the CWDM Mux Demux. From this paper, it can be concluded that there are mainly three factors, the working wavelength, the compatible issue and the transmission distance the CWDM SFP+ supports, should be taken into account when making the decision about which kind of CWDM SFP+ should be selected for the CWDM Mux Demux.

Single Fiber Solutions for CWDM and DWDM Networks

It is well known that there are two transmission ways for fiber optical network, single fiber transmission and dual fiber transmission. From the name, it is easy to learn that the fiber amount is the main difference of these two transmission ways. For the dual fiber transmission, there should be totally two optical fibers, one for transmitting signals, and the other for receiving signals. But for the single fiber transmission, it only requires one optical fiber that can transmit and receive signals at the same time. This feature makes the network deployment easier and the network deployment cost lower than that of dual fiber one, especially in WDM network deployment. In this paper, it will mainly introduce the single fiber solution and its applications in CWDM and DWDM networks.

Single Fiber Solution

Single fiber solution can be also called bidirectional (BiDi) solution designed for carrying signals in both sides of one optical fiber simultaneously. When the single fiber network runs, the signals transmitted from the two sides feature different wavelengths to ensure the dual way transmission. Compared to the dual fiber network, the easy-to-deploy single fiber network would be a good choice for those who have limited budgets but need for bigger network capacity. As for its application, it is very popularly used in Point to Point, Ring or linear Add and Drop, where installing new fibers is impracticable or uneconomical. It can be also used for promoting the reliability of an existing dual fiber network, in which there are one optical fiber for work and the other one for protection.

Single Fiber CWDM Network

The single fiber CWDM network enables the signals with different wavelengths to be transmitted through a signal fiber, which results in a network capacity boost in metro and access networks. As each signal beam can be carried via different channel independently, the different data rates and protocols (T1, T3, Ethernet, Serial, etc) can be transmitted for the different users or applications. To better know how does the single fiber CWDM network work, here offers a figure that shows a 8 channel single fiber CWDM network design.

From the figure, we can learn there are two 8 channel CWDM Mux Demux connected by a single fiber for transmitting 16 signals with different wavelengths and the 16 wavelengths are divided into 8 pairs for bidirectional transmission. On the site A, 8 wavelengths are used for transmitting signals and others for receiving signals. While on the site B, the wavelengths for the TX and RX on the CWDM Mux Demux are all reversed to ensure the performance of the single fiber CWDM network. For instance, the 1270 nm on the site A is the first transmitting wavelength but the first receiving wavelength on the site B. As a result, the signal with 1270 nm can be totally transmitted from site A to site B via the single fiber.

Single Fiber DWDM Network

The single fiber DWDM network also takes full use of the wavelength division multiplexing technology that can greatly expand the capacity over the existing optical network, especially for the long transmission network. Compared to the CWDM one, it can be designed with more channels for larger data signals and can support the network with a much longer distance. What’s more, if the transmission distance is too long, the optical amplifier can be used to enhance the signals. On the other hand, all these advantage makes the cost to deploy a single fiber DWDM network much higher than the CWDM one. Besides, here offers the figure of a single fiber DWDM network design for your reference.

The figure shows a complicated a single fiber DWDM network design that uses two 8 channel DWDM Mux Demux in the main link for single fiber transmission. As for the wavelength feature of the TX and RX for the ports on the DWDM Mux Demux, it is similar to the CWDM one, but the channel spacing is denser. What’s more, except for the existing channels in the main single fiber DWDM link, there can be more channels added into the expansion port of the link for carrying larger data signals. In short, although the cost for deploying single fiber DWDM network is so expensive, it is still a good solution that can make full use of the fiber link to transmit more signals at a much longer distance.

Conclusion

Undoubtedly, the single fiber WDM solution is an ideal choice for those who have limited budgets but need for bigger network capacity. As there are two single fiber WDM solutions available, which one to choose just depends on the network need and budget. The single fiber CWDM network would be more economical but can not transmit as much signals as the DWDM one can, while the DWDM is highly recommended for large and long transmission that would cost more.

Single Fiber CWDM Network Overview

When designing the fiber optical network, we used to choose the duplex fiber cable as the first choice to finish the dual-way transmission, which transmits the dual-way signals via two separate simplex cables from the opposite sides. However, in some typical dual-way applications like working with BiDi fiber optic transceiver, the simplex fiber cable is required to transmit the dual-way signals respectively over only one fiber cable by using two different wavelengths that has a more complicated working principle than the duplex one. If we want to deploy a single fiber CWDM network, the basic principle is similar to simplex fiber cable but would be much more complicated, which will be explained detailedly in this post.

What Is the Single Fiber CWDM Network?

Single fiber CWDM network is a special kind of WDM network that can greatly increase the network capacity by combining and transmitting several pairs of signals with different wavelengths over a single fiber, with the aim of supporting several dual-way connections at the same time. To deploy the single fiber CWDM network, a pair of single fiber CWDM multi-channel Mux/Demux and several pairs of CWDM transceivers are needed. When the single fiber CWDM network works, the two single fiber Mux Demux require different wavelengths for each pair of dual-way transmission, which is very different from the dual fiber Mux Demux using the same wavelength for a pair of dual-way transmission. That’s to say, there are only four different wavelengths used for 4-channel dual fiber CWDM Mux Demux, but eight different wavelengths divided into four pairs for 4-channel single fiber CWDM Mux Demux.

How Does the Single Fiber CWDM Network Work?

Before talking about the single fiber CWDM network, let’s take a simple BiDi network as an example first. In the BiDi network, only one simplex fiber cable and a pair of BiDi fiber optic transceivers are required to finish the dual-way connection. In details, the two BiDi fiber optic transceivers should be almost the same but has reversed wavelengths for TX and RX. For instance, if one transceiver with 1490nm for TX and 1310nm for RX is installed in one end of the fiber link, the other one in the opposite end should use 1310nm for TX and 1490nm for RX, as shown in the following figure. Hence, the dual-way signals with two different wavelengths can be transmitted over only one fiber cable.

As for the single fiber CWDM network, its basic principle is similar to the BiDi network but would be much more complicated, which can be also learned from the following figure. In the figure, there are two 4-channel single fiber CWDM Mux Demux connected to each ends of the single fiber, and four pairs of CWDM SFP+ transceivers designed with eight different wavelengths, totally achieving the 4-channel single fiber CWDM network. It is easily to learn that these eight different wavelengths are divide into four pairs and each pair has the complete reversed TX and RX. For instance, the first pair of CWDM transceivers consist of a transceiver with 1490nm for TX and 1310nm for RX in the left side and a transceiver with 1490nm for TX and 1310nm for RX in the right side, thereby a pair of dual-way signals with two different wavelengths will be transmitted through the first channel. To better understand how does the single fiber CWDM network work, the following table lists the eight ports with four pairs of wavelengths for TX and RX that are all reversed to ensure the dual-way transmission.

Conclusion

The single fiber CWDM network can greatly increase the network capacity for transmitting larger dual-way data signals, which is able to combine several pairs of signals with different wavelengths into an integrated signal and carry it through a single fiber. To build a smooth single fiber CWDM network, you should firstly install the CWDM fiber optic transceivers into two switches and then connect them into the channel ports of the two single fiber CWDM Mux Demux, finally use a single-mode simplex fiber cable to link the two CWDM Mux Demux together. Besides, to ensure the performance of the single fiber CWDM network, there are some important factors like light loss, transmission distance, and optical signal dropping and adding should also be taken into consideration.