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Consumers require more speed therefore data providers are bound to move towards faster speed and higher connections – specifically to increase the ability to cope the current needs like Amazon, Google, Apple, Facebook and Microsoft. More common speed scales like 25-100G Ethernet are constantly becoming an adaptive unit in such massive companies, and the whole industry has joined hands together for the Ethernet next generation development to produce 200 and 400G Ethernet.
In today’s world Multimode type fiber is a very good solution for such environments where speed is required; it has very high enduring capabilities for disarrayed fiber cases and has comparatively Weak connection losses at both ends. The cabling system that has been introduced for it has LEDs and VCSEL combined optical transceivers that are best for short as well as long extent optical to connect with each other.
MMF has raised the channel capacity by using aligned transmission and many fiber strands but this has caused raise in its pricing too.
Multimode Fiber Limitations
In the first go OM1 & OM2 Multimode fiber cables were designed to support 100 & 1000G Fast Ethernet (100BASE-SX & 1000BASE-FX) and could not prove to be effective for 10and 25Gbps data speeds. Standards such as TIA-568.3-D does not recommend OM1 and OM2 MMF for newer installations.
Until recently, OM3 & OM4 (LOMMF) cables were recommended for Fiber Channel, InfiniBand, 100G, 10G and 40G protocols.
It’s a fact that by the increase of bandwidth requirements faster to a great extent than VCSEL-basis transceiver will kick in and it will cause a raise in pricing for the optical fiber connection system to cope with the new-generation Ethernet pace and its migration. As an example, consider the IEEE 802.3bs worth draft, 400GBASE-SE-SR16 has to reuse the old technology 100GBASE-SR4, and for connectors instead of MPO-12 to MPO-32.
Wideband Multimode Fiber – a Possible Alternative
ANSI/TIA developed Wideband multimode fiber can be settled with the high inflating data’s values and upper bandwidth. It works on wavelengths to raise each fiber’s capacity up to four factors, which caters high data-rate increments. By this route one fiber signal can be transmitted to four operating windows instead of creating four distinct fibers for the same purpose.
The new wide band multimode fiber standard (TIA-492AAAE) was considered for publishing in June of 2016 after a TIA taskforce completed an industrial-wide study which lasted for 20 months. Very recently, The International institution for Standardization/International Electro technical Commission (ISO/IEC) has also decided to suggest; OM5 as the name for wide band multi-functional fiber. OM5 is recommended by IEEE 802.3 for the development of upcoming Ethernet generations.
Multi-mode fiber can support:
- Wavelength dividing multiplexing (WDM) over 840nm -953nm wavelength range
- OM4 multi-mode fiber at 850 nanometers.
The effectual modal bandwidth (EMB), not only help out the Bit Rate of 25.78125Gbps as per standard of 100GBASE-SR4 (IEEE 802.3bm) but it can also support 28.05Gbps as required in 32G Fiber Channel standard, Is the highest signaling rate for a given distance of any wideband multimode fiber at 100 meters minimum reach all over the whole wavelength range.
The limitation in multi-mode fiber link of data rate and utmost reach is:
- Fiber cable special attenuation (minimize the signal strength) and facing problem of disconnection.
- Chromatic dispersion in the fiber (out spread of light pulses over time because of different wave-lengths traveling at contrasting speeds)
- Modal band-width of the fiber
Since multimode fiber (MMF) chromatic dispersion and cable attenuation is different in lower and upper wave-lengths, the supported lowest EMB is comparatively lower at 953nautical miles than at the 840-nanometer end. To guarantee backward compatibility the minimum operable EMB (effective modal bandwidth) of wideband multimode fiber (MMF) at 850 nanometers is said to be of the equal point as for OM4.
Other considerable link impairment aspects;
- Transmitter power
- Optical variation in the strength.
- Signal-noise ratio (SNR)
- Bandwidth and sensitivity of the photo-detector
- Crosstalk between two or more adjacent channels
Above mentioned factors are devised by IEEE 802.3 specifically to have a technically better, feasible and adequate mass output margin for transceiver product.
Possible SWDM Applications
It is wise to use single pair of fiber instead of MPO trunks for straight point-to-point connections to reduce cost. As it can be established with the help of the following illustrations; multimode fiber patch-cord cabling comes at a reduced cost than the parallel multimode fiber;
This idea is not new to use a single fiber for carrying multiple wavelengths since it is commonly used in telecomm industry to decrease single mode fiber numbers. Likewise, for short reach data comm applications the use of two and four wavelengths transceiver solutions by Cisco BiDi and Arista Universal are also proven to be market favorites.
The SWDM - a federation was formed in 2015 by a consortium of optical fiber hardware vendors to form a multisource agreement keeping in mind the characteristics of OM5 wideband multimode fiber which supports the wider range of wavelength of 850 to 953nm and more likely to reduce fiber number by transmitting multiple VCSEL wavelength while remaining in the same multimode fiber.
Grids for potential wavelengths are designated with a spacing of 30nm as 850 nanometers (λ1), 880 nanometers (λ2), 910 nanometers (λ3) and 940 nanometers (λ4). Samples for both 40 and 100G QSFP SWDM4 are open for demonstration and it is said to be released in early 2017.
The progress in the field of multimode fiber development as it continues each day we will keep you updated here. Belden’s wideband multimode solutions encompass the best and optimal fiber to add bandwidth by utilizing multiple wave-lengths in extreme end of the spectrum. Know more about the proficiencies and experiences we can lead forth to decrease costs, improve service time, take advantage of area and guarantee security.
