LWDM Channel Plan
LWDM channel plan – 800 GHz O-BAND LWDM channels overview, wavelengths, list of channels, and xWDM systems in this support article.
LWDM (Local Area Network Wavelength Division Multiplexing) is one of the newest xWDM technologies and is used in 100G, 200G, 400G optical links that have been adapted for use in 25G SFP28 transceivers. This innovation provides greater flexibility in network design and enables 5G implementation using available 100G and 200G LAN-WDM transceivers by utilizing LAN WDM wavelengths. LWDM ITU-T standardization is under way should be available by 2021.
A quick recap of bands and defined wavelength can be found below and in the DWDM Channel Plan:
- •Original O-Band 1260-1360 nm
- •Extended E-Band 1360-1460 nm
- •Short Wavelength S-Band 1460-1530 nm
- •Conventional C-Band 1530-1565 nm
- •Long Wavelength L-Band 1565-1625 nm
- •Ultralong Wavelength U-Band 1625-1675 nm
Currently, LWDM systems are based on O-Band with an 800 GHz spectral grid with 12 Channels total. Inter-channel spacing deviates from channel to channel and is in the range from 4.26 nm to 4.62 nm (detailed channel list in LWDM 800GHz O-Band Channels table). Additional information regarding transceiver functionality and applications can be found on the LWDM eCPRI page.
For ease of comprehension, below is an image that depicts CWDM Channels (at the top of the image) and LWDM channels (at the bottom of the image). It is visible that LWDM channel spacing is much narrower than CWDM’s (More on CWDM at CWDM Channel Plan). Some LWDM channels do overlap with CWDMs. Benefits are reduced dispersion and less power required for signal transmission.
Although, clear nomenclature for the LWDM Channel is not defined, it is preferred to use the channel’s center wavelength to differentiate between channels.
By using the center wavelength (λ) to calculate frequency (f) and vice versa.
For example: Channel 269 with a center wavelength of 1269.23 nm and frequency of 236200 (GHz). If you know one, the other can be calculated as below:
For calculations speed of light in vacuum, constant c=299792458 m/s2, is used:
In the LWDM 800GHz O-Band Channels table is a list of all possible O-Band Channels from which 12 are used for communication, and those are from Channel 269 to 318, inclusive.
LWDM Channel Plan for 800GHz O-Band Systems:
| Channel | Wavelength | Frequency |
|---|---|---|
| # | nm | GHz |
| 260 | 1260.69 | 237800 |
| 264 | 1264.95 | 237000 |
| 269 | 1269.23 | 236200 |
| 273 | 1273.54 | 235400 |
| 277 | 1277.89 | 234600 |
| 282 | 1282.26 | 233800 |
| 286 | 1286.66 | 233000 |
| 291 | 1291.10 | 232200 |
| 295 | 1295.56 | 231400 |
| 300 | 1300.05 | 230600 |
| 304 | 1304.58 | 229800 |
| 309 | 1309.14 | 229000 |
| 313 | 1313.73 | 228200 |
| 318 | 1318.35 | 227400 |
| 323 | 1323.00 | 226600 |
| 327 | 1327.69 | 225800 |
| 332 | 1332.41 | 225000 |
| 337 | 1337.17 | 224200 |
| 341 | 1341.95 | 223400 |
| 346 | 1346.78 | 222600 |
| 351 | 1351.63 | 221800 |
| 356 | 1356.53 | 221000 |
LWDM can be used either with or without MUX and DEMUX units for operational uses. More on LWDM MUX/DEMUX units will be available soon.
For the time being, a Great introduction to MUX/DEMUX systems can be found at both the CWDM Channel Plan support article and DWDM Channel Plan support article, as these xWDM solutions also require a MUX and a DEMUX unit for operation. More detailed information regarding MUX/DEMUX units is in the PASSIVE xWDM section.
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Products and categories featured in this article.
25G SFP28 Optical Transceivers
The 25G SFP28 transceiver portfolio is designed to meet the demands of high-speed, low-latency data transmission across a variety of network applications. Offering a comprehensive range of 25G solutions, our lineup includes SR, LR, ER, and ZR transceivers, along with their industrial-grade versions. Additionally, we provide 25G BIDI modules and CWDM, DWDM, and LWDM variants to support flexible and scalable network architectures. Engineered for superior performance, power efficiency, and reliability, The 25G SFP28 modules are optimized for data center, enterprise, and telecom deployments.
25G Fronthaul LWDM SFP28 Transceivers
5G Mobile Networks use much higher radio frequency bands, Massive MIMO and Beamforming technologies which require bringing Remote Radio Unit (RRU) closer to the end users and therefore much denser RRU distribution. Centralized Radio Access Networks (CRAN) are favored by many Mobile Network Architects, where remote BBU farms are built in centralized equipment rooms from where services are provided to many RRUs. Such approach fastens the 5G roll-out, reduces space requirements and rental costs in remote sites, improves maintenance and significantly simplifies transport network architecture. LAN WDM (Local Area Network Wavelength Division Multiplexing) is a new promising way for 5G Fronthaul network design to interconnect BBUs to RRUs. LAN WDM use Wavelength Grid with 800 GHz (approximately 4.4 nm) channel spacing and has 12 Wavelengths from whom 4 center wavelength are according to newly released 400G LR8 (IEEE 802.3bs) standard, 4 center wavelengths are used in 100G LR4/ER4, 200G LR4, 400G LR8 (IEEE 802.3ba) standard and 4 center wavelength are not yet standardized. If we look at the WDM Fronthaul, LWDM eCPRI has some potential advantages when compared to CWDM eCPRI and DWDM eCPRI. As LWDM is in the O band optical wavelength range it helps to have low dispersion penalty when compared to CWDM eCPRI 5G Fronthaul approach which leads to less expensive laser/receiver components, however as LWDM has narrow channel plan, therefore modules are very sensitive to the temperature shifts (similar as DWDM modules) and require TEC (Thermo-Electric Cooler) Controller which increase the cost. LWDM eCPRI potential advantage when compared with DWDM eCPRI could be the ability in similar Fronthaul scenarios to use DML lasers instead of more expensive EML lasers, but this potential advantage will depend on industries maturity for DML chips in LAN WDM spectrum. One of most the important advantages for LWDM eCPRI when compared to CWDM or DWDM eCPRI in mobile Fronthaul could be the ability to build scenarios where we have LAN WDM 100G/200G/400G modules in the BBU unit and 25G LAN WDM at the RRU side. Let’s look at such a scenario if we have 100G in BBU and 4x25G in RRU. LAN WDM 100G module has 1295.56, 1300.05, 1304.58, 1309.14nm wavelength and on each wavelength we have 25G signal and then at the RRU side we would use passive LAN WDM filter to split the 100G signal in 4x25G, we would use 25G LWDM eCPRI modules and connect them to RRU and would be able to provide 25G for particular sector in case we have 4 sector base station. Such an approach would simplify the network structure, make the installation process much smoother and drive down the total cost. LWDM eCPRI 25G modules support latest 5G Fronthaul bit rate requirements and such applications as CPRI Option 10 (24.33 Gbps), CPRI Option 9 (12.165 Gbps), CPRI Option 8 (10.138 Gbps) and CPRI option 7 (9.830 Gbps) at the same time our LWDM CPRI 25G SFP28 optical transceivers are backwards compatible with older generation 4G/3G Mobile Base Stations. Typical LWDM eCPRI 25G SFP28 deployment scenarios are: LWDM 25GE LR (Long Range) eCPRI / CPRI, applications up to 10km over OS2 fiber LWDM 25GE LR 20km (Long Range) eCPRI / CPRI, applications up to 20km over OS2 fiber LWDM 25GE ER (Extended Range) eCPRI / CPRI, applications up to 40km over OS2 fiber