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2. Video Network Designing
2.3. 10 Gigabit Ethernet Designing
The video transmission is taken over the SFP+ interfaces which are required to build in 2x 10 Gigabit Ethernet
connection between the UBEX transmitters and receivers. The fiber optical network solutions provide stable
and trustworthy signal transmission in the video network. This section describes the details about the video
matrix designing in the fiber optical network point of view.
2.3.1. Multimode Fiber
Multimode fiber is used in the LAN environment where distances between the rooms are 300 m or less.
The IEEE 802.3ae 10 Gigabit Ethernet specification includes a serial interface referred to as 10GBASE-SR (the
"S" stands for short wavelength) that is designed for 850 nm transmission on multimode fiber. The table
below provides the wavelength, modal bandwidth, and operating distance for different types of multimode
fiber operating at 10 Gbps.
Description
Wavelength (nm)
850
Modal bandwidth (MHz*km)
160
Operating range (m)
2-26
10GBASE-SR operating range for various multimode fiber sizes
To address the operating range concern, a new multimode fiber specification had to be created for 10GbE
to achieve multimode fiber operating distances of 300 m (as specified in the TIA/EIA-568 and ISO/IEC
11801 cabling standards). This new fiber is referred to by some as "10 Gigabit Ethernet multimode fiber"
and is an 850 nm, laser-optimized, 50/125 micron fiber with an effective modal bandwidth of 2000 MHz*km
and is detailed in TIA-492AAAC. Its key difference, relative to legacy multimode fibers, are the additional
requirements for DMD specified in TIA-492AAAC enabled by a new measurement standard for DMD (TIA
FOTP-220). As shown in the table, this fiber can achieve 400 m of distance with a 10GBASE-SR interface.
Many leading optical fiber vendors are actively marketing this new multimode fiber for 10GbE applications.
2.3.2. Singlemode Fiber
Singlemode fiber is used in the LAN environment where distances between the buildings are 80 km or less.
Standard singlemode fiber can address nearly any application, depending on the level of cost and complexity
that an operator is willing to employ. The latter issues become more significant as higher data rates, different
wavelengths, and/or longer distances are adopted.
Attenuation
DEFINITION: Attenuation: Reduction in transmitted optical power. Attenuation as a function of distance in
optical fiber is logarithmic. Attenuation as a function of optical wavelength is dominated by the degree to
which light is scattered by the molecular structure of the optical fiber ("Rayleigh scattering").
For short fiber spans, optical transmission at 1310 nm remains an appealing option due to the price and
availability of lasers at this wavelength. Several factors drive consideration of transmission at higher
wavelengths, however. At higher data rates, requirements on receiver sensitivity typically grow more stringent,
requiring higher received optical powers to maintain low error rates. Due to relatively high fiber attenuation
62.5 micron fiber
50 micron fiber
850
850
850
200
400
500
2-33
2-66
2-82
Installation and Network Setup Guide for UBEX
at 1310 nm (see the table on the right side), maximum allowable transmission distances are reduced at
1310 nm compared to 1550 nm. At extended distances, which exceed the allowable sensitivities of optical
receivers, signals in the 1550 nm region can be optically amplified (usually with an EDFA) whereas optical
amplification is not commonly available at 1310 nm. As a result, 1310 nm transmission requires electrical
regeneration, which is fundamentally more expensive than optical amplification.
WaveLenght
(nm)
1310
1550
2.3.3. 10 Gigabit Ethernet Fiber Design Considerations
Key factors to consider in the design of 10 Gigabit Ethernet networks are:
850
The network topology, including operating distances, splice losses and numbers of connectors (i.e.
▪
2000
the link power budget).
▪
The fiber cabling type (i.e. singlemode or multimode fiber) and the performance at a specified
2-400
wavelength. The performance is characterized by channel insertion loss (cabling attenuation), and
modal bandwidth(for multimode fiber).
▪
The use of mode-conditioning patch cords if required. The 1310 nm CWDM solution, 10GBASE-LX4,
requires the use of a mode-conditioning patch cord on multimode fiber to achieve its specified range
of operating distances.
▪
The implementation of a cabling design, compatible with LED and laser-based Ethernet network
devices, which will allow the integration of current LED based 10 Mbps and 100 Mbps networks and
laser-based 1 Gbps and 10 Gbps networks.
When designing individual fiber links, the first step is the characterization of the link power budget. This
value (expressed in dB) is specified in the 10GbE standard for each optical interface. Tables for all interfaces
are shown in this section. The link power budget is calculated by taking the difference between the minimum
transmitter power launched into the fiber, and the minimum receiver sensitivity (see the figure below). The
receiver sensitivity is the minimum amount of power that is necessary to maintain the required signal-to-
noise ratio over the specified operating conditions. The link power budget determines the amount of total
loss due to attenuation and other factors that can be introduced between the transmitter and the receiver.
MAIN MENU
TX
Ports
EDID
System status
System settings
Transmitter
minimum power
Link Power Budget = Minimum transmit power - Minimum receiver sensitivity
Maximum fiber attenuation per IEC 60793-2
(dB/km)
0.40
0.30
Attenuation of standard singlemode fiber at 1310 nm and 1550 nm
Channel
Power
Power
Insertion Loss
Penalties
Budget Margin
Link Power Budget
7
Typical cabled attenuation
(dB/km)
0.35
0.25
MAIN MENU
RX
Ports
EDID
System status
System settings
Receiver
minimum sensitivity
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