CWDM Vs DWDM

-

 

CWDM

A CWDM system commonly supports eight wavelengths per fiber and is designed for short-range communications, using wide-range frequencies with wavelengths spread far apart. 

Since CWDM is based on 20-nm channel spacing from 1470 to 1610 nm, it’s typically deployed on fiber spans up to 80km or less because optical amplifiers cannot be used with large spacing channels. This wide spacing of channels allows the use of moderately priced optics. However, the capacity of the links as well as the distance supported are less with CWDM than with DWDM.

Generally, CWDM is used for lower cost, lower capacity (sub-10G) and shorter distance applications where cost is an important factor.

More recently, the prices for both CWDM and DWDM components have become reasonably comparable. CWDM wavelengths are currently capable of transporting up to 10 Gigabit Ethernet and 16G Fiber Channel, and it is quite unlikely for this capacity to further increase in the future.

 

DWDM

In DWDM systems, the number of multiplexed channels is much denser than CWDM because DWDM uses tighter wavelength spacing to fit more channels onto a single fiber.

Instead of the 20 nm channel spacing used in CWDM (equivalent to approximately 15 million GHz), DWDM systems utilize a variety of specified channels spacing from 12.5 GHz to 200 GHz in the C-Band and sometimes the L-band.

Today’s DWDM systems typically support 96 channels spaced at 0.8 nm apart within the 1550 nm C-Band spectrum. Because of this, DWDM systems can transmit a huge quantity of data through a single fiber link as they allow for many more wavelengths to be packed onto the same fiber.

DWDM is optimal for long-reach communications up to 120 km and beyond due to its ability to leverage optical amplifiers, which can cost-effectively amplify the entire 1550 nm or C-band spectrum commonly used in DWDM applications. This overcomes long spans of attenuation or distance and when boosted by Erbium Doped-Fiber Amplifiers (EDFAs), DWDM systems have the capability to carry high amounts of data across long distances spanning up to hundreds or thousands of kilometers.

In addition to the capability of supporting a greater number of wavelengths than CWDM, DWDM platforms are also capable of handling higher speed protocols as most optical transport equipment vendors today commonly support 100G or 200G per wavelength while emerging technologies are allowing for 400G and beyond.

 

 

 

CWDM DWDM diagram 

CWDM DWDM diagram

Comments

Post a Comment

Popular posts from this blog

What is CDR in Optical Modules

-
  What is CDR (Clock and Data Recovery) in Optical modules?   The full name of CDR is clock and data recovery, which can be simply understood as after the optical signal is converted into an electrical signal, the receiver performs electrical domain shaping and clock recovery.    CDR has two main functions 1. The first is to provide clock signal for each circuit of receiver;  2. The second is to judge the received signal, which is convenient for data signal recovery and subsequent processing.   Because when the optical signal is transmitted to a certain distance, it is usually long-distance transmission, and its waveform will appear a certain degree of distortion. The signals received by the receiver are pulse signals of different lengths. At this time, at the receiver, we can not get the data we need. Therefore, signal regeneration is needed at this time. Signal regeneration functions include re amplification, re shaping and re timin...
Read more

What is OpenZR+ for tranponder/muxponder

-
Image
Introduction OpenZR+ defines specifications for 1 00 - 400G single - wavelength optical ports for transceiver/transponder, muxceiver/ m uxponder ( TRXR/ TRPN , M U XR/M UXP ) node functions and for switch/router optical ports .   Open ZR+ Architecture   The architecture, shown in Figure 1 - 1 includes client sub - layers for up to four 100GBASE - R clients , up to two 200GBASE - R clients and a single 400GBASE - R client . Client data and alignment markers are extracted and re - timed to the line side clock domain using the general mapping protocol ( GMP ) . Retimed data plus GMP timing information is then mapped into one of the OpenZR+ frame formats . Those frames are multiplexed and OFEC encode d and become the payload of a DSP frame with DP - 16QAM, DP - 8QAM, or DP QPSK symbols .
Read more

Bit rate and Baud rate

-
In telecommunication Bit rate and baud rate are two important terms. Bit rate and baud rate play important role when we talk about Serial protocol  UART or modulation schemes like BPSK or QPSK   etc., Bit rate is the transmission of number of bits per second. It determines the number of bits traveled per second. Baud rate is defined as the number of signal units(also called as elements) per second. It determines how many times the state of a signal is changing.  For example baud rate is 9600 means 9600 signal level changes are happening within a second.It can determine how much bandwidth is required to send the signal. Relation between Bit rate(r), Baud rate(R), the number of bit per baud(n) Bit rate(r) = R x n Baud rate(R)= r/n
Read more