MSO Application Challenges - Raman Amplifier Transport by maclaren1



Fiber-to-the-Home in the MSO Community
 Successes in HFC system have led to MSOs generally not as
 enthusiastic as Telcos in FTTH development activities.
 However, Fiber is being perceived as the ultimate transmission
 medium and Fiber-to-the-Home access will some day in future be
 preferred by customers when choosing service provider.
 Most PON-based FTTH systems (EPON, GPON) available today
 were developed to suit the Telco network environment. There are
 some challenges in adopting such system in MSO’s environment.
 This presentation highlights some of those challenges to promote
 dialogues for their resolutions between MSOs, Vendors and
 Standards communities.
 Recently, some systems are available for MSO to carry HFC signals
 on PON. But over the long term, HFC has its own set of challenges
 which is outside the scope of this presentation.

Main Challenges for EPON/GPON Adoption by MSO

 Upstream RF Channel for STB Return
 In-house wiring
 Back Office Support
 Distance Limitations
 Trunk Protection
 Fiber Counts Required
 (Note – This is not an exhaustive list)

The Upstream RF Channel Challenge

 The ‘standard’ way of supporting TV broadcast in EPON/GPON
 system is by mean of RF overlay using an additional wavelength.
 (The next slide shows the configuration)
 The current ‘standard’ only supports RF overlay in the Downstream
 direction using 1550nm wavelength. RF return in the Upstream
 direction, which is needed for Video-on-Demand service, is not
 Currently, there are vendor specific solutions available that convert
 the RF from customer’s STB to Ethernet and then transport the return
 channel as Data. This requires operating the DNCS in a different
 mode that may be incompatible with existing configuration.
 It is highly desirable that a non-vendor specific solution be designed,
 commonly adopted by all vendors, and included as ‘standard’.

EPON/GPON RF Overlay Configuration

                Headend                          Passive Optical Netowork (PON)
                                                             Up to 20 km


                                                             Passive                      Cat.5
                                                          Optical Splitter
                                                            (1:16~32)             ONT      TP

                                   OLT                                                         STB
                                    1310nm                                        ONT                      TV
     IP Network                                                                                       Home

             IPTV                          nm

   Analog Chs                     Analog
                           RF     Optical
    BC DTV                      Transmitter

Current Vendor Specific RF Return Solution



                       OLT                   PON   ONT   Cat.5

                        1310nm        1550
                      1490nm           nm                  RF to Eth.

                  BC+NC                                           STB
  DNCS                                                                       TV
          QPSK                   Optical
          Mod.                   Xmtr.
                                             HFC                 Customer
               QPSK              Optical
              Demod.              Rcvr.

The In-House Wiring Challenge

 ‘Standard’ EPON/GPON ONTs deliver service by separate
   – TV service at Coax port
   – Data service at RJ45 Ethernet port
   – Telephone service at RJ11 POTS port
 MSO’s existing practice is to have all services delivered on Coax
 home wiring.
 MoCA is one possible solution that would enable Data service to be
 carried on the Coax wiring, but this requires MoCA gateway devices
 at home and complicates installation.
 A common solution (whether MoCA or something else) advocated by
 the MSO community will help vendors improve on ONT functions to
 better serve our needs at lower costs.

The Back Office Support Challenge

 Back Office Support includes:
   – Service Provisioning / Activation / Deactivation
   – Traffic volume accounting
   – Billing
 Since MSO are typically delivering services by DOCSIS platform, the
 Back Office systems are tailored based on DOCSIS parameters.
 EPON/GPON FTTH platforms work on different set of protocols and
 will be different in control plane structure and reporting parameters.
 It will not be desirable to have a separate Back Office System to
 support DOCSIS service delivery and another one for FTTH service
 Harmonizing the two different platform with one Back Office support
 is a major undertaking and it requires substantial resources and time.

The Distance Limitation Challenge
 The current distance limit in EPON/GPON standards is 20km.
 20km is not adequate for MSO since CATV hubs typically serve
 distances up to 50~60km.
 Most vendors can support service distances much longer than 20km
 if there is no requirement for the RF Overlay.
 Video quality requirements on the RF Overlay channel limit the
 service distance in the following ways:
   – Optical launch power limited by the SBS (Stimulated Brillouin
     Scattering) threshold which is around +18dBm
   – Optical receiver sensitivity limited by the CNR requirement to
     about -6dBm for channel loading of 80 analog plus 20 QAM
   – Passive splitters required for 1:32 split already consume
     16~17dB of the available optical budget.

The Trunk Protection Challenge
 ‘Standard’ EPON/GPON configuration does not provide diverse path
 protection on the PON line
 MSOs need to cover typical service distances of 50~60km; and
 leaving such distance unprotected is risky
 The need for trunk protection should be advocated to the Vendor
 Community should be made at each possible opportunity
 Even more desirable is that the PON line protection requirement be
 included in the respective EPON and GPON standards so that
 protection schemes across different vendors are compatible.

The Fiber-Counts Challenge

 The ‘Standard’ 1:32 split EPON/GPON model imposes the needs for
 very high count fiber cable in the serving area
 For example: an community of 10,000 homes will need a minimum of
 313 fiber-strands homing at the OLT site
 While the costs for installing high count cable is not prohibitive in
 Greenfield area, it is not the same case in areas where the optical
 fiber infrastructure has been laid
 Some vendor do offer the option of using 1:64 split in the PON line,
 however this will also mean a further reduction of service distance to
 much less than 20km

 Fiber connection all the way from Service Provider to Customers is
 the ultimate future proof access medium.
 MSOs’ existing access method may still be adequate, but its never
 too early to start investigating challenges ahead and planning for next
 generation solutions.
 Although EPON/GPON FTTH solutions have been proven by Telcos
 around the world, it will not be just a simple adoption if MSOs choose
 to use the same solution.
 The willingness of vendors to tailor FTTH systems towards MSO’s
 application environment depends on potential demand. Continuous
 dialogue between MSOs on this subject will help developing common
 demands which in turn will lower the costs for those tailored changes.

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