Sharing a actual CWDM project system design case

WDM: wavelength division multiplex; OTU: Optical Transform Unit; SFP/SFP+: small form-factor pluggable/plus; 3R: Re-amplifying, Re-timing, Re-shaping.

Customer detail requirement:

  1. A–B existing cable core;
  2. A–B opens 4 independent services in the first phase and expands to 8 services in the latter phase;
  3. Optical cable distance and loss are unknown, taking 80km, 20dB as an example;
  4. The traffic rate is unknown. Take 4*1.25G as an example.

FOT C/DWDM solution

CWDM project system design(draft)

  In accordance with the specific needs of customers, we only need to use a set of 8-wave CWDM wavelength division system to solve this demand. The detailed scheme is as follows:

  A end view (need a set of CWDM wavelength division system), by using OTU (Optical Transform Unit), the 8-channel ordinary wavelength 850nm/1315nm optical signal of the customer switch are converted into standard CWDM wavelength optical signal. Then, through CWDM wavelength division multiplexer, put the 8 different wavelength multiplexed optical signal into an single optical fiber to transmit.
At the B end, through the CWDM wave demultiplexer, similarly the multiple optical signals (transmitted from the A end) were converted to 8 different wavelength optical signals of the S/W(switch). And then again, the optical signals of different wavelengths convert to the switch 8 ordinary 850 nm/ 1315nm via the OUT device at the B end.

  B end view, completely acting as opposite of working flow as the situation form A end view. Similarly, a set of CWDM wavelength division system and OTU product is need too. Detail working flow please check the diagram as following.

C/DWDM platform’s features:

  • Large capacity, total capacity up to 2.5G*8, large data transmission capacity expansion;
  • Save fiber optic cable, realize big data expansion under limited fiber optic cable resources, and save costs;
  • It is easy to expand capacity, and there is no need to interrupt existing services during capacity expansion. You only need to increase the service board.
  • High security, the equipment adopts a modular design and supports hot swap;
  • Power supply supports 1+1 hot backup, AC 220/DC -48v optional;
  • Each business channel is independent of each other, and it truly realizes the exclusive use of large bandwidth.
  • OTU card adopts 3R design to achieve signal wavelength conversion, waveform shaping, and clock retiming to ensure that the signal is not distorted;
  • Unified network management platform, visual management, truly end-to-end management;

C/DWDM product description

FOT C/DWDM platform series

  The optical transmission network system integrates the C/DWDM platform, which is mainly applied to the metropolitan access layer network. It can complete functions such as optical fiber saving, multiplexing, and distance expansion, and solves the problem of insufficient optical fiber resources in the access layer network, providing customers with Low-cost, multi-service access, efficient bandwidth multi-service access scheme.

Performance parametersTechnical indicators     
ProductFOT C/DWDM platform series
Equipment size2U: 88mm (high) * 442mm (width) * 220mm (deep)
Service slot8 slots (One slot can be equipped with a network management card)
Single device transmission capacity32 wave *10G bidirectional transmission
64-wave *10G unidirectional transmission
4 wave *100G single bidirectional transmission
wavelengthCWDM: 1271nm~1611nm
DWDM: C Band, 100GHz & 50GHz
Single channel maximum rate100Gbit/s
Transmission distanceFor DWDM systems, support for transmission distances of up to 130km (36dB) in a single span
For CWDM systems, support up to 80km transmission distance
Optical amplifier25dB (nominal gain)
Service interface typeSTM-1/4/16/64, OC-3/12/48/192, FE,GE,10GE,100GE, FC100/200/400/800/1200, FICON,ESCON,EPON,GPON, CPRI 1/2/3/6/7 Interface service etc.
Clock characteristicsIEEE 1588V2
Optical connectorSFP/SFP+, Connector type: LC
Network topologyPoint to point, chain, star, ring
Installation method19" or 23" cabinet, ETSI 300mm/600mm cabinet, wireless outdoor base station cabinet, FTTx outdoor cabinet, wall mount
range of working temperature‘-10℃~60℃
Operating humidity range‘5~95%
Storage temperature range‘-40~85℃
CoolingFan cooling
Power supplyAC: 90 to 260 or DC: -36 to -72v (supports 1+1 power input backup)
Power consumption120W

OTU service board

  OTUQS2S-2.5 is a four-channel 2.5G service access board introduced by our company; its main function is to promote the 3R regeneration of service signals of any protocol within the range of 4 access 42Mbit/s~2.67Gbit/s rate, and Can be converted to DWDM or CWDM standard wavelength optical signals, so that the combining unit can perform wavelength division multiplexing on optical signals of different wavelengths, and at the same time realize your process of the above process. Especially suitable for any service access at 2.5G or below, providing a low-cost WDM transmission solution.

OTU product and Functional structure

Product model numberOTUQS2S-2.5     
Basic functionSupports 4-way 42Mbit/s~2.67Gbit/s two-way transmission at any rate;
Supports 8-way 42Mbit/s~2.67Gbit/s single-way transmission at any rate;
Access service typeFE,GE,STM-1/4/16/
CPRI: 614.4 Mbit/s, 1.23/2.46Gbit/s
Occupied slot numberOccupies 1 slot
WDM technologySupports DWDM: C Band, 100GHz & 50GHz
Support CWDM: 1271nm~1611nm
3R technologySupport 3R function, Re-amplifying, Re-timing, Re-shaping
Network management functionSupport port real-time detection of operating status, including transmit power, receive power, temperature, etc.
Supports power adaptation
InterfaceSupports 8 SFPs that can be plugged in and out, and SFPs can be configured when an electrical port is accessed.
Typical power consumption15W
MTBF> 100,000 hours


  WDM: multiplexes optical signals of different wavelengths into the same fiber for transmission. We call it Wavelength Division Multiplexing in this way.
  At the receiving end, the optical carriers of various wavelengths are separated by a demultiplexer, and then the original signals are restored by the optical receiver for further processing.

DEMUX/MUX product and Functional structure

Common channels2*42*81*16   
Occupied slot number111
WM specificationSupport CWDM / DWDMSupport CWDM / DWDMSupport CWDM / DWDM
CraftsmanshipWave FilterWave FilterWave Filter
Insertion loss of each channel<1.5dB<2.5dB<3.5dB
Adjacent channel isolation>30dB>30dB>30dB
Non-adjacent channel isolation>40dB>40dB>40dB
Reflection coefficient<-45dB<-45dB<-45dB
Interface TypeAll interfaces are LC type
Typical power consumption0W, Passive components
MTBF>200,000 hours

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