Solving Fiber Capacity Issues in the Last Mile

Champion ONE helps clients and service providers maximize the capacity of their fiber networks. We strive to lower the costs of deploying new technology in the least funded part of the network: The Last Mile. Whether you own your own fiber and need additional capacity, or you are leasing the fiber and want to keep your Monthly Recurring Costs (MRC) down, the following architectures can help solve your fiber capacity issues. If you operate a fiber network, it is only a matter of time before you run into a capacity issue. Whether on a single span or a section of the network, C1 has the expertise and the solutions that provide the right balance between performance, reliability, and complexity. C1 can help you extend both the Operational Expenses (OPEX) and Capital Expenditures (CAPEX) budgets now and in the years to come.

When faced with a fiber capacity issue the typical solutions are:

  • Build or lease new fiber: This can be very expensive (e.g., OPEX and CAPEX) and take a long time to deploy. If there is no fiber in place then this may be the only option. But once it is in place, the fiber can be made to handle capacities well beyond a single circuit or service.
  • Increase the data rate: If there is a single circuit on the existing fiber and more capacity is needed, then increasing the data rate of the circuit is one way to fix the problem. For instance, upgrading from a single GigE Ethernet to a 10GigE Ethernet can increase the capacity ten times. This can be done by simply adding cards and optics to the existing shelf. But this may result in adding, commissioning, and connecting a completely new system to your network. In this case, the availability of the equipment, the complexity of deploying the new system, and the CAPEX and OPEX involved often make this option difficult. Keep in mind that the cost of owning these new systems often involves annual contracts for software and maintenance, which adds to the total cost of ownership.
  • Wavelength Division Multiplexing (WDM) infrastructure: Simply put WDM is the process of adding multiple circuits or services over the same fiber, or fiber pair, to increase the transmission capacity of the fiber. This can be done quickly (hours vs. days) with little to no complexity and no provisioning or turn-up, providing a two to eight times capacity increase. WDM can also be deployed without adding new systems to the network.

Passive WDM and 10G Passive Optical Networking (PON) architecture solutions the are most common ways to maximize fiber capacity in the last mile. They are also the simplest and quickest ways to deploy. They are very cost-effective regarding CAPEX and OPEX. We will look at the simplicity of adopting both WDM and 10Gig PON.

Passive WDM architecture: As described above, WDM is simply the process of adding multiple wavelengths (one per circuit or direction) over a single fiber or fiber pair. The filters that make this happen are passive and require no power. They can be deployed indoors or in an outside plant and come in a variety of form factors. Passive WDM modules can be small and add two wide-band channels together with — 1550nm and 1310nm, or very dense. They add upwards of eighty dense Wavelength Division Multiplexing (DWDM) channels together. To make this work, you simply need to add the correct wavelength of pluggable optics to your existing network equipment. For instance, let us say you have an Ethernet switch at two sites connected by a pair of 1550nm optics. You place a pair of passive DWDM filters between them, then replace those 1550nm optics with DWDM optics that line up with the first channel of the filter. That circuit can now be transported with other channels along with the same fiber pair. Refer to Figure 1 below, it shows WDM being used over a single Point to Point (PTP) over a single fiber pair.

WDM Single Fiber

Figure 1. WDM over a single fiber pair

As you can see, solving the issue of fiber capacity using passive WDM and the corresponding WDM Optics is simple and cost-effective. This same approach can be used in point-to-point, linear chain, ring, and hub and spoke architectures. Because passive WDM filters are bidirectional by nature, they can also be deployed as a single fiber architecture by using each wavelength to distinguish between the circuit direction. Figure 2 shows WDM being deployed over a single fiber and how each circuit direction is separated by wavelength.

WDM Fiber Pair

Figure 2. WDM over a single fiber

With extensive expertise and decades of experience building solutions for some of the largest service providers in North America, C1 is here to help you find the solutions that fit your needs.

XGS (10G) PON architecture: For over a decade, Passive Optical Networking (PON) has been established as the least costly way to deliver services to the last mile. PON uses a single fiber architecture, two wavelengths for upstream and downstream traffic, and a point to multipoint structure. Until recently, Gigabit PON (GPON) and Ethernet over PON (EPON) have been the prevailing technologies used in North America. These technologies offer up to 2.5Gbps downstream traffic and up to 1.25Gpbs. Bandwidth can be split or shared between 32, 64, or even 128 end users, making it the most affordable way to deliver service. Figure 3 shows the basic single fiber PON architecture.

Due to the point-to-multipoint nature of PON, latency is a very important metric and is usually limited to ~20km between the Optical Line Terminal (OLT) port at the service provider end and the Optical Network Unit (ONU); which is located at the subscriber end. At the same time, its ability to distribute bandwidth for up to 128 end users makes it an extremely cost-effective way to light the last mile.

Single Fiber PON

Figure 3. Single fiber PON architecture

Whether you are building a new PON network from scratch or have been deploying GPON/EPON for years, the latest technology being deployed is XGS (10G) PON. 10G PON is deployed as a symmetrical service, providing 10Gbps both downstream and upstream. This represents a four times increase in downstream bandwidth, and a ten times increase in upstream traffic over legacy GPON. Both can be deployed over the same single fiber as legacy GPON and EPON. Industry standards for 10G PON have accounted for the Coexistence Elements (CE) that will allow 10G PON to coexist on the same fiber using passive WDM CE modules. Figure 4 shows the coexistence of a legacy GPON network with a new 10G PON service.

Legacy Gpon and 10G PON

Figure 4. Coexistence of legacy GPON and 10G PON

Using the passive CE module allows the service provider the ability to upgrade subscribers based on the take-rate of the upgraded service, or provide business-class services from the same splitter. Based on those same standards these CE modules can also be used to include 1550nm video, RF over a glass (RFOG), or PTP D/CWDM to further expand the capacity of the same single fiber.

We have developed a unique 10G PON ecosystem that provides everything you need to deploy the new 10G PON in your network. Our 10G PON Ecosystem allows you to deploy the OLT port in an existing 10G SFP+ port in any network switch. This offers a pay-as-you-grow cost model, a variety of ONUs (offering everything from a wired bridge mode ONU to a feature-rich Wi-Fi 6 gateway mode ONU with all of the splitters), jumper cables, WDM, and CE modules. Refer to Figure 5 for an overview of our end-to-end XGS (10G) PON Ecosystem.

10G PON Ecosystem

Figure 5. Our 10G PON Ecosystem

Passive WDM is the ideal way to add large amounts of capacity to your existing or leased fiber infrastructure. Once in place, each wavelength or channel acts as a virtual fiber that can be deployed quickly. Passive WDM requires no power or in-depth training to deploy or maintain. When paired with WDM optics, your existing switch ports make for a very robust solution for your current and future needs.

If a single fiber architecture delivering symmetrical 10Gbps capacity that goes up to 128 endpoints better fits your company’s needs, then using a 10G PON is the way to go. Going by the industry standard, mature PON technology is by far the least expensive way to deliver bandwidth to the edge, or last mile, of your network.

Over the last few decades, Approved Networks and Champion ONE have maintained a consultative approach to solving the fiber capacity issue in the last mile for both large and small service providers/customers. In today’s ever-changing environment, the “new normal” of working remotely and the need for super-fast high bandwidth applications (AR and VR) drives us to ensure you have the tools that work best for you.

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