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  • Mode Conditioning Patch Cable Tutorial

    There are bandwidth limitations of multimode fiber. Most current LAN networks are composed of about 90% multimode fiber. As the fiber cable plant is upgraded to single mode fiber cables, we must also provide a migration path that continues to reuse the installed multimode cable plant for as long as possible. However, there are some technical issues involved when using single mode equipment on existing multimode cable plant. The biggest problem is caused by Differential Mode Delay (DMD). It refers when a fast rise-time laser pulse is applied to multimode fiber, significant pulse broadening occurs due to the difference in propagation times of different modes within the fiber.

    To solve the problem, mode conditioning patch cable was developed as a solution for network applications where Gigabit Ethernet hubs with laser based transmitters are deployed. Mode conditioning patch cable is the mean to achieve the drive distance of installed fiber plant beyond its original intended applications. It allows customer upgrading their hardware technology without the cost of upgrading fiber plant. In addition, mode conditioning patch cable significantly improves data signal quality while increasing the transmission distance.


    What is Mode Conditioning Patch Cable?



    Mode Conditioning Patch Cable, or Mode Conditioning Patchcord (MCP), is a duplex multimode patch cable that has a small length of single mode fiber at the start of the transmission length. Designed to "condition" the laser launch and obtain an effective bandwidth closer to that measured by the overfilled launch method, the MCP allows for laser transmitters to operate at gigabit rates over multimode fiber without being limited by DMD. The point is to excite a large number of modes in the fiber, weighted in the mode groups that are highly excited by overfill launch conditions, and to avoid exciting widely separated mode groups with similar power levels. This is achieved by launching the laser light into a single mode fiber, then coupling it into a multimode fiber that is off-center relative to the single mode fiber core. This is shown beside.

    Tips: Different offsets are required for 50µm and 62.5µm multimode fibers. Engineers have found that an offset of 17~23 µm can achieve an effective modal bandwidth equivalent to the overfill launch method for 62.5µm multimode fibers. And an offset of 10~16 µm is good for 50µm multimode fibers.

    The basic principle behind the cable is to launch laser into the small section of single mode fiber. The other end of single mode fiber is coupled to the multimode section of the cable with the offset from the center of the multimode fiber. This patch cable is required with transceivers (e.g.1000BASE-LX/LH, 10GBASE-LX4 and 10GBASE-LRM) that use both single mode and multimode fibers. When launching into multimode fiber, the transceiver can generate multiple signals that causes DMD which can severly limit transmission distances. The MCP removes these multiple signals, eliminating problems at the receiver end. Here is a figure that shows an MCP and how it is typically connected to a transceiver module. When required, it is inserted between a transceiver module and the multimode cable plant.

    MCP using with Transceivers


    Requirements for Using MCPs in Laser-Based Transmissions

    Gigabit Ethernet

    The requirement for MCP is specified only for 1000BASE-LX/LH transceivers transmitting in the 1300nm window and in applications over multimode fiber. MCP should never be used in 1000BASE-SX links in the 850nm window. MCP is required for 1000BASE-LX/LH applications over FDDI-grade, OM1, and OM2 fiber types. MCP should never be used for applications over OM3, also known as "laser-optimized fiber".

    1. In some cases, customers might experience that a link would be operating properly over FDDI-grade, OM1 or OM2 fiber types without MCP. However please note there is no guarantee link will be operating properly over time, and the recommendation remains to use the MCP.
    2. There is a risk associated to this type of nonstandard deployment without MCP, especially when the jumper cable is an FDDI-grade or OM1 type. In such case the power coupled directly into a 62.5µm fiber could be as high as a few dBm and the adjacent receiver will be saturated. This can cause high bit error rate, link flaps, link down status and eventually irreversible damaged to the device.
    3. In the event customers remain reluctant to deploy MCP cables, and for customers using OM3 cables, please measure the power level before plugging the fiber into the adjacent receiver. When the received power is measured above -3dBm, a 5dB attenuator for 1300nm should be used and plugged at the transmitter source of the optical module on each side of the link.
    4. Another alternative for short reaches within the same location is to use a single-mode patch cable. There will be no saturation over single-mode fiber.


    10-Gigabit Ethernet

    The requirement for MCP is specified only for 10GBASE-LX4 and 10GBASE-LRM transceivers transmitting in the 1300nm window and in applications over multimode fiber. MCP should never be used in 10GBASE-SR links in the 850nm window. MCP is required for 10GBASE-LX4 and 10GBASE-LRM applications over FDDI-grade, OM1, and OM2 fiber types. MCP should never be used for applications over OM3, also known as "laser-optimized fiber."

    Notes for 10GBASE-LX4:
    1. In some cases, customers might experience that a link would be operating properly over OM2 fiber type without MCP. However chances of experiencing a properly operating link over FDDI-grade or OM1 fiber types without MCP are very low.
    2. In the event customers remain reluctant to deploy MCP cables over OM2, and for customers using OM3 cables, it is required to a plug a 5dB attenuator for 1300nm at the transmitter source of the optical module on each side of the link in order to avoid saturation, and potential subsequent link flaps and damage to the device.
    3. Another alternative for short reaches within the same location is to use a single-mode patch cable. There will be no saturation over single-mode fiber. Please note the 10GBASE-LX4 devices can reach up to 10 km over single-mode fiber as per compliance to IEEE.
    Notes for 10GBASE-LRM:
    1. For customers using OM3 fiber type, MCP should not be used. It is highly recommended to measure the power level before plugging the fiber into the adjacent receiver. When the received power is measured to be above 0.5dBm, a 5dB attenuator for 1300nm should be used and plugged at the transmitter source of the optical module on each side of the link.
    2. Another alternative for short reaches within the same location is to use a single-mode patch cable. There will be no saturation over single-mode fiber. Please note the 10GBASE-LRM devices can reach up to 300 meters over single-mode fiber.


    Notes for the Installation of MCPs

    When using 1000BASE-LX/LH, 10GBASE-LX4 and 10GBASE-LRM transceivers with legacy 62.5µm or 50µm multimode fiber, you must install MCP between the transceiver and the multimode fiber cable on both ends of the link. The MCP is required for all links over FDDI-grade, OM1 and OM2 fiber types, and should never be used for applications over OM3 and more recent fiber types.

    Note: It is not recommended using 1000BASE-LX/LH, 10GBASE-LX4 and 10GBASE-LRM transceivers with multimode fiber and no patch cable for very short link distances (tens of meters). The result could be an elevated Bit Error Rate (BER) and receiver damage.

    The MCP is installed between the transceiver and the patch panel. Two MCPs are required per installation. To install the patch cable, follow these steps:
    Step 1 - Plug the single mode fiber connector into the transmit bore of the transceiver.
    Step 2 - Plug the other half of the duplex connector into the receive bore of the transceiver.
    Step 3 - At the other end of the patch cable, plug both multimode connectors into the patch panel.
    Step 4 - Repeat Step 1 through Step 3 for the second transceiver located at the other end of the network link.
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  • 40G QSFP+ Transceiver Modules and DAC/AOC Cables Installation Guide

    To install and remove the transceiver optics in a right way is very necessary to ensure the network to work stably and efficiently. Today, we are going to introduce an installation guide of QSFP transceivers and DAC/AOC cables in 40G network.

    40GbE QSFP+ Transceivers Overview

    40 Gigabit Ethernet (40GbE) aggregation switches are becoming more common in today's data centers. At the heart of the 40GbE network layer is a pair of transceivers connected by a cable. The transceivers are plugged into either network servers or a variety of components including interface cards and switches and connected via the cables such as OM3 and OM4 for multimode application. Additionally DAC (Direct Attach Copper) cables or AOCs (Active Optical Cables) are used for short interconnection as a more cost-effective alternative solution. QSFP+ (Quad Small Form-factor Pluggable Plus) is the most common 40GbE interface type, and also as a high-density 10GbE interface via QSFP+ breakout cables. QSFP+ interfaces a network device (switch, router, media converter or similar device) to a fiber optic or copper cable, supporting data rates from 4x10 Gbps and supports Ethernet, Fibre Channel, InfiniBand and SONET/SDH standards with different data rate options. Compared to CFP (C form-factor pluggable) transceiver modules, QSFP transceiver modules are more compact and more suitable for port-density application. The two basic interface specifications of QSFP+ modules respectively for multimode and single-mode applications are 40GBASE-SR4 and 40GBASE-LR4.

    40GBASE-SR4 QSFP+ Module

    The 40GBASE-SR4 QSFP+ module, conforming to the 802.3ba D3.2 (40GBASE-SR4) standard, provides a 40Gbps optical connection using MPO/MTP® optical connectors. This optical module integrates four data lanes in each direction with 40Gbps aggregate bandwidth and each lane can operate at 10.3125 Gbps. It is used in data centers to interconnect two Ethernet switches with 8 fiber parallel multimode fiber OM3/OM4 cables (transmission distance can be up to 100 meters using OM3 fiber or up to 150 meters using OM4 fiber).


    40GBASE-LR4 QSFP+ Module

    The 40GBBASE-LR4 QSFP+ module, conforming to the 802.3ba (40GBASE-LR4) standard, provides a 40Gbps optical connection using LC optical connectors. This optical module integrates four data lanes in each direction with 40Gbps aggregate bandwidth and each lane can operate at 10.3125 Gbps. It is most commonly deployed between data center or IXP sites with single-mode fiber up to 10 km.

     In addition, to satisfy a number of different objectives including support for MMF and SMF compatibility, there are other types of QSFP+ modules offered by different vendors.

    How to Install/Remove QSFP+ Transceivers and DAC/AOC Cables

    To protect a QSFP+ module or cable from ESD (electro-static discharge) damage, before installing or removing a QSFP+ module or cable, be remembered that always wear an ESD wrist strap and make sure that it makes good skin contact and is securely grounded (If you are using ESD gloves, wear the wrist strap outside the ESD glove).

    To Install or Remove a QSFP+ Transceiver Module

    There are two types of clasp designed for a QSFP+ transceiver module—plastic clasp or a metallic clasp. Here uses the metallic clasp type as an example.

    To Install a QSFP+ Transceiver Module

    Step 1. Remove the QSFP+ module from its antistatic container and remove the dust covers from the module optical connector.
    Step 2. Remove any rubber dust covers from the port where you are installing the QSFP+ module.
    Step 3. Pivot the clasp of the module up. (Skip this step if the clasp is plastic.)
    Step 4. Align the module with the port in the chassis, as shown in Figure 1.

    Figure 1. Aligning the module with the port
    Figure 1. Aligning the module with the port

    Step 5. Holding the module, gently push in the module until it is firmly seated in the port.(see Figure 2.)

    Figure 2. Install the QSFP+ module to port
    Figure 2. Install the QSFP+ module to port

    Step 6. Immediately attach the patch cord with MPO connector or duplex LC connector to the QSFP+ transceiver module.(see Figure 3.)

    Figure 3. Install the patch cord to the module
    Figure 3. Install the patch cord to the module

    Note: Install the dust plug for the transceiver module if you are not to install an optical fiber into it.

    To Remove a QSFP+ Transceiver Module

    Step 1. Remove the optical fiber if any.
    Step 2. Pivot the clasp of the module down to the horizontal position. (Skip this step if the clasp is plastic.)
    Step 3. Holding the module, gently pull the module out of the port. (Figure 4)
    Step 4. Place the QSFP+ transceiver into an antistatic bag.

    Figure 4. Remove the QSFP+ module
    Figure 4. Remove the QSFP+ module

    To Install or Remove a 40G QSFP+ Cable

    The installation and removal procedures are the same for QSFP+ DAC cables and QSFP+ AOC cables. Here uses a QSFP+ DAC cable as an example:

    To Install a QSFP+ DAC Cable

    Step 1. Align the QSFP+ transceiver module (with the clasp on top) at one end of the cable with the port in the chassis, as shown in Figure 5.
    Step 2. Horizontally and gently push in the module to fully seat it in the port.

    Figure 5. Installing a QSFP+ DAC cable
    Figure 5. Installing a QSFP+ DAC cable

    To remove a QSFP+ DAC Cable

    Step 1. Gently press and release the QSFP+ transceiver module.(see Figure 6.)
    Step 2. Holding the cable, gently pull the clasp on the cable to pull out the transceiver module.

    Figure 6. Removing a QSFP+ DAC cable
    Figure 6. Removing a QSFP+ DAC cable

    To Install or Remove a 40G QSFP+ to 4x10G SFP+ Cable

    40G QSFP+ to 4x10G SFP+ cable combines one 40G QSFP+ module on one end and four 10G SFP+ module on the other end. The installation and removal procedures of 40G QSFP+ connector are introdueced above. Here only introduced the installation and removal of 10G SFP+ module:

    To Install an SFP+ Transceiver Module

    Step 1. Align the module with the SFP+ port, with the golden plating facing the spring tab (see Figure 7.) in the SFP+ port. If the chassis has two rows of ports, the spring tab in a port is on the bottom in the upper row and on the top in the lower row.
    Step 2. Slightly press the module against the spring tab so you can push the module straight into the port.

    Figure 7. Installing an SFP+ transceiver module
    Figure 7. Installing an SFP+ transceiver module

    To Remove an SFP+ Transceiver Module

    Step 1. Press the module with your thumb, as shown by callout 1 in Figure 8.
    Step 2. Gently pull the clasp on the cable to pull out the transceiver module, as shown by callout 2 in Figure 8.

    Figure 8. Removing an SFP+ transceiver module
    Figure 8. Removing an SFP+ transceiver module

    Verifying the installation

    Execute the display transceiver interface command on the device to verify that the transceiver module or DAC/AOC cable is installed correctly. If the transceiver module and DAC/AOC cable information is displayed correctly, the installation is correct. If an error message is displayed, the installation is incorrect or the transceiver optics is not compatible.

    transceiver interface command


    As 40 GbE are widely deployed, 40G transceiver optics are ubiquitous. A good practice and correct installation are very important for 40G network system, not only to protect the 40G transceiver optics and device from damage, but also to ensure a stable performance for system. In addition, by executing the display transceiver interface command, we can verify whether the installation is correct. Of course, the premise is that the transceiver optics you use is fully compatible with your device. COMPUFOX offers a comprehensive line of high-compatible 40G transceiver optics, such as 40GBASE-SR4 QSFP+, 40GBASE-LR4 QSFP+ and 40G DACs and AOCs with competitive prices. See Links below:


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  • WDM Optical Networking Solutions

    COMPUFOX offers a number of  WDM Optical Networking solutions which allow transport associated with a mix of services up to 100 GbE over dark fiber and WDM networks providing for the whole set of probably the most demanding CWDM and DWDM network infrastructure needs. Because the physical fiber optic cabling is expensive to implement for every single service separately, its capacity expansion using a WDM is a necessity.

    WDM Architectures

    WDM architecture


    WDM (Wavelength Division Multiplexing) is a concept that describes combination of several streams of data/storage/video or voice on the same physical fiber optic cable by utilizing several wavelengths (or frequencies) of light with each frequency carrying a different sort of data. There's two types of WDM architectures: CWDM (Coarse Wavelength Division Multiplexing) and DWDM (Dense Wavelength Division Multiplexing). CWDM systems typically provide 18 wavelengths, separated by 20 nm, from 1470nm to 1610nm according to ITU-T standard G.694.2. However, for different applications, there are different ITU-T standard to define the specific wave range and channels. Compared to CWDM, DWDM is defined in terms of frequencies. Some DWDM network systems provide up to 96 wavelengths, typically without any more than 0.4 nm spacing, roughly over the C-band range of wavelengths.

    CWDM Technology

    CWDM is proved to be the initial access point for many organizations due to its lower cost. Each CWDM wavelength typically supports as much as 2.5 Gbps and could be expanded to 10 Gbps support. This transfer rates are sufficient to aid GbE, Fast Ethernet or 1/2/4/8/10G Fibre Channel, along with other protocols. The CWDM is limited to 16 wavelengths and is typically deployed at networks as much as 80 km since optical amplifiers can't be used due to the large spacing between channels.

    DWDM Technology

    DWDM is a technology allowing high throughput capacity over longer distances commonly ranging between 44-88 channels/wavelengths and transferring data rates up to 100 Gbps per wavelength. Each wavelength can transparently have a wide range of services. The channel spacing from the DWDM solutions is defined by the ITU standards and can range from 50 GHz and 100 GHz (the most widely used today) to 200 GHz. DWDM systems can provide up to 96 wavelengths (at 50 GHz) of mixed service types, and can transport to distances up to 3000 km by deploying optical amplifiers (e.g., DWDM EDFA) and dispersion compensators thus enhancing the fiber capacity with a factor of x100. Due to its more precise and stabilized lasers, the DWDM technology tends to be more expensive in the sub-10G rates, but is really a more appropriate solution and it is dominating for 10G service rates and above providing large capacity data transport and connectivity over long distances at affordable costs.

    Note: COMPUFOX WDM optical networking goods are designed to support both CWDM and DWDM technology by utilizing standards based pluggable  CWDM/DWDM Transceivers such as SFP, XFP and SFP. The technology used is carefully calculated per project and according to customer requirements of distance, capacity, attenuation and future needs.


    The main benefit of CWDM is the price of the optics that is typically 1 / 3 of the price of the equivalent DWDM optics. This difference in economic scale, the limited budget that lots of customers face, and typical initial requirements to not exceed 8 wavelengths, means that CWDM is a popular entry point for a lot of customers. With COMPUFOX WDM equipment, a customer can start with 8 CWDM wavelengths however grow by introducing DWDM wavelengths in to the mix, utilizing the existing fiber and maximizing roi. By utilizing CWDM and DWDM network systems or the mixture of thereof, carriers and enterprises are able to transport services as much as 100 Gbps of data.

    Typically CWDM solutions provide 8 wavelengths capability enabling the transport of 8 client interfaces over the same fiber. However, the relatively large separation between your CWDM wavelengths allows growth of the CWDM network with an additional 44 wavelengths with 100 GHz spacing utilizing DWDM technology, thus expanding the present infrastructure capability and making use of the same equipment included in the integrated solution.


    Additionally, the normal CWDM spectrum supports data transport rates as high as 4.25 Gbps, while DWDM is utilized more for large capacity data transport needs as high as 100 Gbps. By mapping DWDM channels inside the CWDM wavelength spectrum as demonstrated below, higher data transport capacity on the same fiber optic cable is possible without any requirement for changing the existing fiber infrastructure between the network sites. As demonstrated through the figure beside, CWDM occupies the following ITU channels: 1470 nm, 1490 nm, 1510 nm, 1530 nm, 1550 nm, 1570 nm, 1590 nm, and 1610 nm, each separated from the other by 20 nm. COMPUFOX can insert into the of the 4 CWDM wavelengths (1530 nm,1550 nm,1570 nm and 1590 nm), a set of additional 8 wavelength of DWDM separated from one another by only 0.1 nm. By doing so up to 4 times, the CWDM network capability can easily expand by up to 28 additional wavelengths.

    The other figure below further demonstrates in detail the expansion capabilities via the DWDM spectrum. As seen below, just one outgoing and incoming wavelength of the existing CWDM infrastructure can be used for 8 DWDM channels multiplexing in to the original wavelength. Since this DWDM over CWDM network solution is integrating the DWDM transponders, DWDM MUX/DeMUX and EDFA (optical amplifier if needed), the entire solution is delivered simply by adding a really compact 1U unit. This expansion is achieved with no service interruption to the remaining network services, or to the data, and with no need to change or replace any of the working CWDM infrastructures.


    Advantages of COMPUFOX WDM Optical Networking Solutions

    COMPUFOX CWDM and DWDM network equipment provides the following advantages:
    Low-cost initial setup with targeted future growth path.
    Easy conversion and upgrade capabilities up to 44 wavelengths
    Easy upgrade to support 10G, 40G and 100G services
    Seamless, non traffic effective network upgrades
    Reliable, secure, and standards based architecture
    Easy to install and maintain
    Full performance monitoring

    With COMPUFOX compact CWDM solutions, you could get all of the above benefits and much more (such as remote monitoring and setup, integrated amplifiers, protection capabilities, and integration with 3rd party networking devices, etc.) inside a cost effective 1U unit, enabling you to expand as you grow, and utilize your financial as well as physical resources towards the maximum.

    To purchase your CWDM and DWDM transceivers, please click on the links below:


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  • Huawei Completes 5G Key Technology Tests in the Field Trial Sponsored by IMT-2020 5G Promotion Group

    [Shenzhen, China, May 27, 2016] Huawei completed the first phase of key 5G technology tests as a part of a series field trials defined by the IMT-2020 5G Promotion Group. In April 2016, the outdoor macro-cell tests, conducted in Chendu, China, consist of a number of the foundational key enabling technologies and an integrated 5G air-interface. The test results successfully demonstrated that the new 5G air interface technology can effectively improve spectrum efficiency and to meet diverse service requirements for 5G defined by ITU-R.

    Huawei completes 5G key technology tests in 5G field trial

    Strong Promotion for Global Partnership on 5G Technology Innovation and a Global 5G Standard

    Launched by China Academy of Information and Communication Technology (CAICT), the IMT-2020 5G Promotion Group aims to foster a joint effort to promote 5G technology evaluation and field test among the global mobile industry and ecosystem to ensure the successful commercial deployment by 2020. One of the key objectives for IMT-2020 5G Promotion Group is to realize the 5G vision for the enhanced mobile broadband service as well as to create the new capabilities for 5G to enable the IoT and vertical services, this represents the unprecedented technical challenges such as to realize 10Gbps or peak rate 20Gbps user data rate, 100 billion connections, and 1 ms of end-to-end network latency for the 5G air interface.

    Early this year, IMT-2020 5G Promotion Group announced a three phase 5G networks trial plan, spanning from 2016 to 2018, with a first phase test from September 2015 to September 2016. The first phase test is focused on key radio technologies and performance test.

    As one of the core members in the IMT-2020 5G Promotion Group, Huawei actively contributed IMT-2020 5G Promotion Group and 5G technology test. In addition, Huawei established an extensive collaboration with CAICT, China Mobile, China Unicom, and China Telecom in the Chinese operator community to explore the innovative air-interface technologies to achieve best spectral efficiency and massive links capabilities. Huawei’s effort is focused on New Radio (NR) technology, which includes the optimized new air-interface, full-duplex and massive MIMO technologies, these are the enabling technologies to achieve the superior end-user experience for the emerging mobile broadband service such as 4K, 8K and virtual reality and augmented reality.

    Best-in-Class Test Results Using 5G New Air Interface

    The 5G air interface technology has been implemented through three novel foundational technologies, i.e., filtered Orthogonal Frequency Division Multiplexing (F-OFDM), Sparse Code Multiple Access (SCMA) and Polar code to meet 5G requirements and performance targets.

    F-OFDM technology is the basis for creating ultra-flexible air-interface to adaptively fit all the 5G use-case scenarios defined by ITU-R with a single radio technology platform. It allows multiple concurrent radio numerologies and frame structure to deliver very diverse services; F-OFDM can ensure the future-proof for the 5G system to meet emerging innovative services requirements. The test results showed that F-OFDM can increase system throughput by 10% using those free guard bands in LTE system. In addition, F-OFDM supports asynchronous transmission from different users. Test results showed that it will provide 100% higher system throughput compared with that in LTE system in the presence of mixed service on the same carrier frequency with mixed radio numerologies. .

    SCMA is to support massive connections and obtain higher system throughput simultaneously via the joint optimization on sparse SCMA codebook design and multi-dimensional modulation. It can further consider optimization on power allocation among different SCMA layers especially in downlink to improve total system throughput. The test results showed that SCMA is to increase the uplink connection number by 300% and at the same time increased the downlink system throughput up to 80%.

    For Polar code, it allocates information to the highly reliable data locations in the code structure to transmit useful information of user and at the same time it supports channel coding of any code rate with an appropriate code construction to fit any future service requirements. The test results showed that Polar code provided coding gain from 0.5dB to 2.0dB compared with Turbo code used in LTE system.

    System Integration of Innovative 5G Air Interface Technologies

    The flexible system integration of several innovative 5G air-interface technologies, namely, F-OFDM, SCMA and massive MIMO has been verified in the first phase of key 5G technology tests. In the test, multi-user MIMO (MU-MIMO) supported up to 24 users and up to 24 parallel layers transmission on the same time-frequency resources. The test results showed that MU-MIMO can achieve 3.6Gbps cell average throughput using 100MHz system bandwidth, it is almost 10 times of that in LTE baseline system.

    The trial has validated the optimal integration of the above new radio technologies and the capability of flexible 5G air-interface technologies, the trial is also served as a technical re-risk to support the on-going 3GPP standardization work.

    Full Duplex Implemented in the First Phase of 5G Test

    Full Duplex mode has also been tested in the first phase of 5G test. In the initial test stage on Full Duplex, it allows simultaneous transmitting and receiving of data at the base station with three level cascaded technologies, namely, passive analog cancellation, active analog cancellation, and digital cancellation. The test results showed that the Full Duplex can provide self-interference cancellation capability more than 113dB in real world environment and result in a total 90% system throughput gain over the conventional half duplex mode used today.

    Huawei has successfully completed the first phase test of 5G technologies in China. "The trial of 5G technologies in China will be a great contribution to 5G applications in the future.” Dr. Wen Tong, Huawei 5G Chief Scientist emphasized that, "As a member of the IMT-2020 5G Promotion Group, Huawei is pleased to work with CAICT, China Mobile, China Unicom, and China Telecom, and took the initiative to be the first to complete 5G key technologies tests and corresponding system integration test based on our proposed 5G new air interface."

    He also announced the plan of the second phase of 5G test which will focus mainly on the wide coverage, high hotspot capacity, and massive connections with high reliability, low latency with reduced power consumption.

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  • Ethernet Passive Optical Network Tutorial

    EPON is a PON-based network that carries data traffic encapsulated in Ethernet frames. Unlike other PON technologies which are based on the ATM standard, it uses a standard 8b/10b line coding and operates at standard Ethernet speed. This lets you utilize the economies-of-scale of Ethernet, and provides simple, easy-to-manage connectivity to Ethernet-based, IP equipment, both at the customer premises and at the central office.

    EPON Network Structure

    A typical EPON system is composed of OLT, ONU, and ODN (Figure 1).

    EPON Network Structure
    Figure 1. EPON Network Structure

    The OLT(Optical Line Terminal)resides in the Central Office (CO) and connects the optical network to the metropolitan-area network or wide-area network, also known as the backbone or long-haul network. OLT is both a switch or router and a multi-service platform which provides EPON-oriented optical interfaces. Besides the network assembling and access functions, OLT could also perform bandwidth assignments, network security and management configurations according to the customers’ different QoS/SLA requirements.

    The ONU(Optical Network Unit)is located either at the end-user location or at the curb and provides optical interfaces which are connected to the OLT and service interfaces at users’ side such as voice, data and video.

    The ODN(Optical Distributed Network)is an optical distribution network and is mainly composed of one or more passive optical splitters which connects the OLT and ONU. Its function is to split downstream signal from one fiber into several fibers and combine optical upstream signals from multiple fibers into one. Optical splitter is a simple device which needs no power and could work in an all-weather environment. The typical splitters have a splitting ratio of 2, 4, 8, 16 or 32 and be connected to each other. The longest distance the ODN could cover is 20 km.

    EPON Downlink and Uplink Technology

    In an EPON the process of transmitting data downstream from the OLT to multiple ONUs is fundamentally different from transmitting data upstream from multiple ONUs to the OLT.

    In the downstream direction, Ethernet frames transmitted by the OLT pass through a 1:N passive splitter and reach each ONU. N is typically between 4 and 64. This behavior is similar to a shared-medium network. Because Ethernet is broadcast by nature, in the downstream direction (from network to user), it fits perfectly with the Ethernet PON architecture: packets are broadcast by the OLT and extracted by their destination ONU based on the media-access control (MAC) address (Figure 2).

    Downstream Traffic in EPON
    Figure 2. Downstream Traffic in EPON

    In the upstream direction, due to the directional properties of a passive optical combiner, data frames from any ONU will only reach the OLT, and not other ONUs. In that sense, in the upstream direction, the behavior of EPON is similar to that of a point-to-point architecture. However, unlike in a true point-to-point network, in EPON data frames from different ONUs transmitted simultaneously still may collide. Thus, in the upstream direction (from users to 13 network) the ONUs need to employ some arbitration mechanism to avoid data collisions and fairly share the fiber-channel capacity (Figure 3).

    Upstream Traffic in EPON
    Figure 3. Upstream Traffic in EPON

    EPON and ADSL Comparison

    The requirement of bandwidth is increasing crazily with the incoming of digital age. Therefore the current high speed copper cable ADSL (Asymmetric Digital Subscriber Line) cannot meet our needs longer. The bandwidth of ADSL is limited to only a few megabit per second and the upstream and downstream bandwidth are not equal either. However, optical fiber has larger bandwidth and superior transmission capability which reaches gigabit per second. Hence, optical fiber used in access network is the future trend. And since Ethernet is low cost, uncomplicated widely-used in current network, and its application is very popular nowadays. So it is not hard to see that it is feasible and economical to combine them together. EPON technology combines a mature Ethernet technology and high-bandwidth PON technology, which is an ideal access method to achieve integrated services. In the future, highbandwidth business will surely drive up existing EPON which has the rate of 1.25Gbps in both the downstream and upstream directions.

    EPON Technical Advantages

    EPONs are simpler, more efficient, and less expensive than alternate multiservice access solutions. Key advantages of EPONs include the following:

    Higher bandwidth: up to 1.25 Gbps symmetric Ethernet bandwidthLower costs: lower up-front capital equipment and ongoing operational costsMore revenue: broad range of flexible service offerings means higher revenues


    With the growing of EPON technology, interaction standards and EPON devices, EPON has entered the large scale application phase driven by the huge market demands. EPON is fit for the access market which is at the end of the fibers and which has a certain density and these markets include FTTH, FTTP, FTTB, FTTN etc.

    EPON becomes a very economical and effective broadband access solution because of its predominance in equipment investment and also the operations, maintenance and etc. It could be said that the EPON technology has become the developing direction of access network’s technologies in the future as an ideal solution for FTTH.

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