Network Access Technology Consideration in Europe By Helge Tiainen of InCoax and Chair of the MoCA Access Work Group Introduction There is no shortage of networking alternatives to reach multi-dwelling units (MDUs) with fiber-to-the-home (FTTH), fiber-to-the-basement (FTTB extended with Ethernet cabling and fiber-to-the-node (FFTN) extended with VDSL or G.fast. A recent entrant into the MDU broadband market is MoCA Access. Though known as a home networking standard, the Multimedia over Coax Alliance is applying the high performance of its MoCA technology to broadband access applications targeting MDUs. MoCA Access is based on MoCA 2.0 which is capable of more than 1 Gbps actual throughputs and MoCA 2.5 which is capable of up to 2.5 Gbps net throughputs. It is also uses the existing in-building coaxial cabling. The purpose of this document is to outline key differences and identify the most appropriate technology in each application. IPTV and web-based services are driving capacity requirements European homes have an average of two TV sets and three is not uncommon. All are connected to the in-building coaxial network serving digital TV broadcasting, terrestrial or cable. The development of new services such as BBC iplayer and Netflix, changes the way we watch TV and consume content. In addition, the traditional TV set has been upgraded to a large screen TV that requires high-resolution delivery for good picture quality, which drives the transformation from standard definition (SD) to high definition (HD) and ultimately to ultra-high definition (UHD). To meet the transformation from traditional TV to content distribution over IP, operators must increase and manage the sustained capacity delivered to each home or apartment. Many different calculations have been made on the sustained capacity required in an all-ip home. The information presented below is aggregated from numerous sources including news articles and market research reports and is intended as a guideline only. Device type Required speed for online service Number of devices in advanced home Expected number of concurrent devices on-line Estimated capacity requirements IPTV SD 4-8 Mbps 1 1 8 Mbps IPTV HD 8-12 Mbps 1 1 12 Mbps IPTV UHD 8-25Mbps 1 1 25Mbps resolution On-line gaming 2-5 Mbps 2 1 5 Mbps Tablets 1-2 Mbps 1 1 2 Mbps PC/laptops 2-5 Mbps 3 1 5 Mbps Smart phones 1-2 Mbps 4 2 0.5 Mbps Total Table 1. Broadband capacity requirement in a modern home 57.5Mbps
The advent of IPTV makes it difficult to deliver such services over legacy ADSL lines, especially if the subscriber uses multiple devices to consume content and connect to the Internet. HD/UHD formatted content and the influx of other devices in the home are driving broadband requirements to more than 50 Mbps of sustained capacity, and 100 Mbps is becoming common. Cable TV operators today offer 100 Mbps and in some cases up to 400 Mbps. Network Access Alternatives Broadband access technologies can be segmented into whether the operators use active or passive equipment outside the central office (CO) and whether they serve single dwelling units (SDUs) or multi-dwelling units (MDUs). Wire line broadband subscribers are commonly served using one of the following topologies: Active electronics are placed outside the CO location such as in street cabinets or in building basements Passive electronics are placed outside the CO location such as in street cabinets or in the basement of the building. Digital loop carrier represents the most widely adopted active outside CO topology. More recently, FTTN (fiber to the node) or FTTB (fiber to the basement) has been deployed as an active outside plant topology, specifically for deployment of broadband and IPTV services. Passive outside CO topologies are typically comprised of PON technologies. Passive Optical Networking (PON) Gigabit passive optical networking (GPON) and Ethernet passive optical networking (EPON) both meet network bandwidth requirements for 100 Mbps and more. PON-based signals are transmitted and received over a single fiber. The PON optical line terminal (OLT) in the CO is connected through optical splitters installed in the street cabinet or in the MDU basement that divides the in-coming fiber signal to multiple fibers. These fibers are installed in the MDU to reach optical network terminals (ONT) in the apartments. Downstream transmission is broadcast, meaning all customers simultaneously receive the same signal. An addressing time scheme is utilized in the downstream direction to identify data intended for one ONT versus another. Time division multiplexing (TDM) combined with a grant scheme is used in the upstream direction to control and time which ONT has the ability to transmit, thus preventing upstream collisions on the single fiber as it heads toward the PON OLT. A basic PON is illustrated in the figure below. 2
Figure 1. Passive Optical Network Structure for single family home In Figure 1 a single PON connection reaches each individual home. Figure 2- Passive Optical Network Structure for MDU In Figure 2, a PON connection reaches each apartment. It requires the building and apartment owner acceptance and approval. Operators deploying PON-based broadband access to MDUs have identified the following barriers. Though not always a pure technology decision, it should be noted that housing and tenant associations can also pose challenges. Potential Barrier Potential Delay Cause Subscriber reluctant to convert from legacy broadband subscription to high-speed fiber access. Length of existing subscription contracts. Understand the benefits with fiber based services compared to legacy services. Broadband service only from one operator. New cabling in existing inbuilding ducts. A reason for not deploying new access alternatives. Up to 12-18 months Building owner may have difficulty in selecting broadband services on behalf of its tenants open access solution is typical in municipal owned buildings. Will apartment owners give up their landline phone? New cabling in stairwells. Can take 12-18 months Need acceptance from majority of the apartment owners for new services. New cabling and ONT In many cases not accepted at Many apartment owners do 3
installation in the apartment. all. not like new wiring inside their apartments Access to apartments and apartment key handling. May take several weeks for installation. Apartment owners do not accept strangers visiting their apartments. In-building wiring cost. Fiber to the Node If potential take-up rate is low then the in-building investment pay-back time can be very long. In-building fiber investment is 200-400. ONT and home network add to the cost per apartment and can be up to 500-800 per apartment. Table 2 Barriers for PON-based broadband access in MDUs FTTN-based networks employ deep fiber to feed remote nodes as street cabinets are located closer to the subscriber premises than the CO. This helps achieve higher line rates for VDSL deployment. Street cabinets must be able to operate in extreme weather with a temperature range of -40 to 65 degrees Celsius. The power supply must be protected from various external voltages that can harm the equipment such as lightning and AC cross voltages. The FTTN system often requires additional space in the street cabinets which usually means a cabinet exchange. FTTN networks can provide VDSL at a higher speed than a VDSL installation at the CO. The VDSL subscriber speed depends on the distance between the street cabinet and the apartment. Using existing phone line and at a distance of 400-500 meters, the broadband transmission rate is not likely to achieve 100 Mbps with any reliability. 30-60 Mbps is most likely. Figure 3. Fiber to the Node structure FTTN provides an alternative to CO location-based network topology that will increase broadband speed. Operators deploying FTTN have identified the following barriers to deployment. 4
Potential Barrier Potential Delay Cause Subscriber reluctance to convert from legacy broadband subscription and contract to VDSL. Length of existing subscriptions and length of cancellation period. Doesn t understand the additional benefit with VDSLbased services compared to legacy services. Power supply to street cabinet if power feed is not from subscriber modem. Does not support 100 Mbps actual throughputs. Building permits and installation work can delay deployment with months. Broadband speed improvement is not substantial. Power supply is usually not present in street cabinets. Not future-proof. Table 3. Barriers for FTTN-based VDSL broadband access. In a FTTN-based approach uses existing copper phone lines eliminating the need for new wires. But this isn t a long-term solution as it will be necessary to provide vectored VDSL to reduce cross-talk problems. Fiber to the Building (FTTB) Networks (Point-to-Point) An attractive alternative to PON and FTTN for MDUs is FTTB where the equipment is placed both at the CO and at the subscriber premises using a passive, point-to-point fiber connection. Figure 4. Fiber to the building structure FTTB is very scalable for individual or multiple subscribers when serving a MDU. When terminating subscribers, the FTTB-MDU system can use a DSLAM, Ethernet switch or a network access controller based on MoCA Access located at the subscriber premises (usually in the basement). The in-building wiring consists of existing phone lines for VDSL or G.fast, new Cat5/6 cabling or existing coax cabling. Cat 5/6 cabling can be used up to 90-100 meters. This enables the MDU building to be served by one or more Gigabit Ethernet connection(s), and a combination of statistical, multicast, and multiplex gain to be applied by the switching or controlling equipment in the FTTB-MDU system. 5
FTTB-MDU deployments are often different from the FTTN street cabinet variant. Equipment located outside must be temperature hardened, in the MDU premises normally room temperature conditions exists. To speed up broadband deployment it is important to select an in-building network alternative that does not pose challenges for new broadband connectivity among building or apartment owners. Operators deploying FTTB-based networks have identified the following barriers. Potential Barrier Potential Delay Cause Broadband service only from one more operator. A reason for not deploying new access alternatives. Not all tenants may agree on a specific broadband service. Open access solutions are typical in municipal owned buildings. New cat5/6 cabling in existing in-building ducts. New fiber cabling in existing inbuilding ducts. If replacement of existing POTS wiring is required, it can delay deployment with 12-18 months. If replacement of existing POTS wiring is required, it can delay deployment with 12-18 months. Apartment owners may not all agree to give up their landline? Can apartment owners accept to give up the landline phone connections? New cabling in stairwells. Up to 12-18 months Need acceptance for new services by a majority of the apartment owners. New cabling in the apartment. In many cases not accepted at all Many owners do not accept new wiring inside their apartments. Existing exclusive usage contract between building owner and cable-tv operator. Installation of active equipment in the basement. Access to apartments and apartment key handling. Power consumption of the active basement equipment. It can delay deployment of broadband access over coax until cable-tv contract is renewed. Usually this is a cost for the operator and the building owner only need to provide power to the equipment. Several weeks during installation if new cabling is required within the apartment. Can cause long delay if operator is not compensating building owner for the power consumption. Table 4. Barriers for FTTB in-building networks. Some cable-tv operators have invested in re-placement of the inbuilding coaxial cable network and have exclusivity protection before investment is paid back. New equipment requires space and access by the operator. Apartment owners do not accept strangers visiting their apartments. Additional energy costs also paid by apartment owner who do not subscribe to the new broadband services. A FTTB-based approach can pose challenges if new cabling is required as cost and time to deploy increase. These barriers are reduced if the existing copper phone lines or coaxial cabling is used. There is no sacrifice in bandwidth when using coax. One Gbps actual 6
throughputs and beyond are available via technology standards such as MoCA Access. This type of speed is not available using VDSL or G.fast over phone lines. In-building Access Alternatives FTTB-MDU applications have several benefits over FTTN street cabinet deployments. Local power supply is always available in the building and the temperature is generally controlled. An FTTB installation is also future-proof since the fiber is available much closer to subscribers apartment than the FTTN street cabinets. Also to be considered is cost of a new in-building network which can be as much as 40 percent of the total cost of a fiber rollout. Below is a list of the most typical in-building access alternatives. New Cat5/6 cabling Existing phone wires Existing coax cables Fiber New Cat 5/6 cabling from the fiber entry point, where an Ethernet switch is installed, to each apartment Ethernet outlet typically installed inside the apartments entrance door. It also requires new in-apartment Cat5/6 cabling to several Ethernet outlets. Using the existing in-building phone wires connected to an in-building DSLAM. It can requires new phone line wiring to the fiber entry point. In many cases the phone lines are not available in the building basement. Phone lines go from raisers in the building to a street cabinet that can be located some hundred meters away. Uses the in-building coaxial wiring which is connected to an in-building coax link controller. Coax is always available in the basement or in the loft of the building. Change of in-building splitters and taps are usually required to support higher MoCA frequencies. The Coax Link Controller is connected to the incoming fiber and operates as an Ethernet switch bridge with Ethernet ports in a coax modem in each apartment. New fiber cabling from the buildings fiber entry point where an Ethernet switch with fiber ports is installed. Each apartment is reached through an in-building fiber network to a point inside the apartment entrance door where an ONT is installed. An in-apartment Cat5/6 network is installed to serve several Ethernet outlets. Table 5. MDU in-building cabling alternatives for broadband access Fast in-building deployment is crucial in order to get quick subscriber acquisition. Thus, it is important to understand advantages and disadvantages of different network alternatives. Type of in-building Advantages network New LAN cat5/6 cabling - Future-proof network for up to Gigabit traffic Disadvantage - High cost to reach apartment, 200-300/apt. 7
- Low power consumption for the Ethernet switch; approx. 250 kwh per year New fiber cabling - Future-proof for gigabit traffic - Active equipment not required in the building. Using phone wires for VDSL / G.fast Using existing coaxial cables with MoCA Access TM - No apartment visits or key handling - Suitable even for low initial penetration levels - No new cabling - No apartment visits or key handling - Reaches all apartments antenna outlets - Support 1Gbps with a 2.5 Gbps migration path. - Supports IPTV - Fast installation - Low power consumption on a coax link controller of 175 - Apartment cabling cost range of 100-150/Ethernet outlet - Surface mounted stripes for new cabling in stairwells are not accepted. - Apartment key handling for apartment installation visit. Some do not accept strangers to visit their apartments. - High per port cost if number of apartments are higher than number of switch ports. - High cost to reach apartment, 300-500/apt. - Apartment cabling cost from 100-150 / Ethernet outlet - Surface mounted stripes for new cabling in stairwells are not accepted - Apartment key handling for apartment installation visit. Some do not accept strangers to visit their apartments - Power consumption approx. 450 kwh / year - High per port cost if number of apartments are higher than number of switch ports - VDSL supports 60-100 Mbps. - G.fast peaks at around 500Mbps and while higher speeds have been touted, these have not been proven. This is not a future-proof technology especially when the market is demanding 1 Gbps today. - Vectored VDSL required to eliminate crosstalk. - New cabling from in-building cross connection point to the basement DSLAM, if available. - High DSLAM power consumption is approximately 1300 kwh per year. - Exclusive usage rights of the inbuilding coaxial networks for a cable- TV operator limits other operators usage of existing coax. - Coaxial cable network needs to be checked. - Splitters and taps have to be replaced to cover higher MoCA frequency range. 8
kwh/year Table 6. Advantages and disadvantages for different in-building alternatives Conclusions Choice of access technology is dependent on in-building wiring and the interests and agendas held by building owners and tenants. PON should be deployed in new buildings with existing fiber or LAN cabling or SDUs where the decision is up to the homeowner and no new in-building cabling is required. FTTN can be used in situations where modest broadband capacity is required. It means installing VDSL in street cabinets. FTTN deployment can be an interim solution awaiting the next step, to reach into the building with fiber. Due to its bandwidth and flexibility, serving both residential and business customers, FTTB should be used in existing MDU buildings. Using in-building coax as an extension to each unit provides performance and reliability and does not require new wiring. 9