White Paper. AON vs. PON A comparison of two optical access network technologies and the different impact on operations

Transcription

1 A comparison of two optical access network technologies and the different impact on operations KEYMILE 2008

2 Table of content 1. Basic facts Passive Optical Networks (PONs) Active Optical Networks (AONs) Network topologies with PON and AON 5 2. Comparison of the technologies Bandwidth Security and quality of services Business case aspects Investment costs (CAPEX) comparison A comparison of operating expenses (OPEX) Flexibility and scope for usage Summary Glossary KEYMILE 2008 Page 2

3 The telecommunications industry has had more than ten years of experience with active and passive optical networks and debates about their advantages and disadvantages have been running for that long at the very least. Fibre optic networks can be laid directly to households (Fibre-to-the-Home [FTTH]) by using Passive Optical Networks (PONs) and Active Optical Networks (AONs). In the mid 1990s, the first large-scale PON installations were commissioned in Japan. In many other parts of the world, FTTH concepts were a long way off. The Internet was still in its infancy, attractive online offerings for private customers were practically non-existent and the technology was much too expensive in any case. As a result, most end customers did not require more bandwidth (i.e. more than ISDN was capable of at the time) till the beginning of the new millennium. The subsequent escalation of bandwidth, fuelled by the availability of broadband DSL connections via copper wire, has turned the Internet and associated services into an unparalleled success story. Today, considering all the new services like high definition IPTV, online gaming and remote surveillance, ICT service providers are well advised to seek access network solutions with even more bandwidth for the post-dsl era. However, due to the physical properties of copper wire in the last mile, VDSL2 has reached its limits, even if technology called DSM (Dynamic Spectrum Management) is being developed to boost the transmission capacity on copper. Communication solutions like WiMAX, or LTE in mobile telephony, reach the limits of their capabilities even more quickly because of poorer physical transmission properties (in comparison with copper). To date, the only solution for seemingly infinite bandwidths has been the optical wave guide, also called fibre optics. 1. Basic facts The key technical difference between active and passive access technology is that a passive splitter is used for passive optical networks. The splitter is basically a kind of multi-mirror that distributes the optical signal for the subscriber line to fibre optic routes without any electrical current (which is why it is called passive). The first active optical access networks used TDM technology. The first passive optical networks on the other hand used ATM for voice and data traffic (APON, BPON, ITU-T Standard G.983). Because early PON systems could already transmit a TV broadcast signal on a separate wavelength in the optical spectrum, simultaneously to the voice-data signal, they were popular in cable TV networks. The topologies of PON and CATV networks are also very similar to one another, so existing cable lines, or ducts can be used and costs saved in the network rollout. The objective of both PON and AON is to get the fibre optics as close as possible, ideally right into the subscribers houses and apartments. This FTTHsolution is technically the best option with respect to the transmission quality and the bandwidth Passive Optical Networks (PONs) As regards the core network, the first network element of a PON network is the OLT (Optical Line Termination Unit), that provides n x 1 Gbps and n x 10 Gbps Ethernet interfaces to the core network and the PON interfaces to the subscriber. The PON types used here today are usually Ethernet-PON (EPON), Gigabit-PON (GPON) or Gigabit-Ethernet-PON (GEPON). Ethernet technology is the common denominator in all these technologies. Nowadays, EPON installations tend to occur more in the Far East and GPON more in the USA and Europe. Consequently, we will be looking at the GPON-type (ITU-Standard G.984) below KEYMILE 2008 Page 3

4 Network 1.2. Active Optical Networks (AONs) AON is a point-to-point network structure (PTP), i.e. each subscriber has their own fibre optic line that is terminated on an optical concentrator (Access Node [AN]). Optical Line Termination (OLT) Passive optical Splitter Figure 1: Subscriber line in a PON Optical Network Termination (ONT) GPON s current standard can provide a maximum of 2.5 Gbps towards the subscriber (downlink) and 1.25 Gbps towards the core network (uplink) per PON interface on the OLT. To the subscriber, a passive splitter, that is either fitted to an outdoor cabinet in a collocation room, or in the end subscriber s premises, multiplies the signal on the fibre optics into n optical subscriber branches. In other words, the network structure is a point-to-multipoint structure (PMP). The structure is similar to a tree, colloquially called a PON tree, or a twig or branch is referred to in the subscriber access line (see figure 1). In an FTTH network architecture, subscriber access is implemented using optical network termination (ONT) that terminates the optical signal and converts it into one or more electrical interfaces, such as for example 100BaseTx, POTS, ISDN or Coax. If copper wire is used for the last mile, an optical network unit (ONU) can be used instead of the optical network termination in the PON, which then provides interfaces such as POTS, ISDN or DSL. In this case, the network architecture is a Fibre-to-the-Curb (FTTC) connection. All PON subscribers receive the same optical signal at the end of the fibre optics. The personal allocation of data is carried out via a time multiplex procedure, i.e. each subscriber receives their own time slot to transmit and receive. Synchronisation of the right user time slot is carried out in the ONT. Network Access Node Optical Ethernet Figure 2: Subscriber line in an AON Optical Network Termination (ONT) This type of AN can be designed differently, depending on specifications. Usually Metro- Ethernet-Switches, IP-Edge routers or Multi- Service Access Nodes (MSANs) with optical Ethernet interfaces are used in this case. The fibre optics can be terminated by an ONT here too, but also by any Ethernet switch or IP router with an optical uplink interface. If the last mile to the subscriber is to be bridged using copper wire, DSLAMs or other MSANs are used. When MSANs are used, both copper and optical lines can be used for the last mile from the same access node KEYMILE 2008 Page 4

5 1.3. Network topologies with PON and AON network n x 1000BaseFX OLT Splitter Downlink 2,5 Gbps Uplink 1,25 Gbps net OLT Splitter ONT network OLT ONT net ONU POTS/ISDN VDSL2 OLT Splitter net OLT Splitter ONU ONU POTS/ISDN VDSL2 NT NT NT NT FTTH FTTH FTTC FTTB FTTE CO MDF Curb NT Copper double pair Optical fibre MDU Households Network type Figure 3: Overview of network topologies in PON networks As figure 3 and 4 show, PON and AON can be used to implement all network topologies, starting with Fibre-to-the-Exchange (FTTE), to Fibre-to-the-Curb (FTTC), Fibre-to-the-Building (FTTB) and Fibre-to-the-Home (FTTH). Both technologies have to take the fibre optics to the end subscriber, but can also bridge the last mile with copper wire. For PON this can be implemented directly from the OLT, or in AON from the access node. Optical Network Units (ONUs), or DSL Access Multiplexers (DSLAMs) can be integrated to provide the POTS or ISDN interfaces for telephony and various DSL types for -Speed Internet (HSI). network n x 1000BaseFX AN Ethernet Switch Uplink/Downlink 100 Mbps network AN network ONT ONT network Ethernet Switch AN POTS/ISDN VDSL2 NT AN network Ethernet Switch DSLAM AN POTS/ISDN VDSL2 NT NT NT FTTH FTTH FTTC FTTB FTTE CO MDF Curb NT Copper double pair Optical fibre MDU Households Network type Figure 4: Overview of network topologies in AON networks Despite the obvious aspects both technologies have in common, there are variations inherent in the systems that affect operations, costs and the value they provide differently. Because PON and AON technology is so widespread and changing from one to the other is costly, operators should be aware of all the facts. The main differences are shown below KEYMILE 2008 Page 5

6 2. Comparison of the technologies VDSL2 24 [Mbps] Bandwidth [km] Bonded EFM Active 1 Gbps EFM Active 100 Mbps 2.4 GPON (32-split) Source: DSL Forum, FTTx Summit 2007, Munich The trend towards increasing bandwidth continues unabated. Due to the launch of TV-over-IP (IPTV) there is no sign of the increase in bandwidth tailing off, in fact quite the opposite. Because of the recent launch of (HDTV) and other technically complex services such as online gaming, network operators are being encourage to outdo one another by providing more and more bandwidth. The following table compares PON and AON transmission bandwidth. Figure 5: Bandwidth downstream and range AON PON Assessment Bandwidth allocation The amount allocated to the subscriber is governed by the interface type, or traffic shaping on the access node and is therefore adjustable in kilobit increments. Maximum bandwidth per subscriber As each subscriber is connected with their own fibre optics, bandwidth can today be implemented at between 100 Mbps and 1 Gbps per household or company. Increasing bandwidth Simple As the active access node has a modular structure, subscriber interfaces can be upgraded to include more bandwidth. It is often sufficient to just switch the fibre optic lead to be able to operate it again. Average The GPON interface on the OLT nowadays is 2.5/1.25 Gbps (downlink/ uplink). The bandwidth per subscriber is determined by the splitting factor (usually 1:32 or 1:64). Modern PON systems however permit bundling of several time slots and therefore an increase in bandwidth per PON terminal point. Satisfactory With regard to the PON standards available today, the maximum feasible capacity of fibre optics is the same as the total capacity of an OLT port, i.e. 2.5 Gbps (PTP connection without a splitter). Therefore, realistically the bandwidth with splitter and a separation of usually 1:32 is 78 Mbps, or at 1:64 39 Mbps (all figures relate to downstream). Difficult Depending on the systems technology, it would be feasible in the future to bundle several time slots and therefore, at the cost of the maximum number of subscribers per PON branch, to increase individual bandwidth by a factor of n + 1. The bandwidth of the PON port on the OLT is the absolute limit, i.e.. 2.5/1.25 Gbps (down/up). AON clearly has the edge because of its flexibility. Due to the static splitting factor and the interfaces on the OLT, PON is at a disadvantage. AON technology is clearly better as regards the bandwidth per subscriber. The maximum bandwidth per subscriber is a lot higher. The flexibility to allocate different bandwidths to individual subscribers is also greater (e.g. for corporate customers) than when PON systems are used. Depending on the splitting factor, a PON connection via fibre optics supplies less bandwidth than a VDSL2 connection via copper wire. In this case, the PTP architecture is superior to the PON s PMP architecture. Just by converting boards, subscribers can obtain an upgrade, without the network architecture or the service of other subscribers having to be changed KEYMILE 2008 Page 6

7 To sum up, the PON network s predefined topology makes individual changes more difficult. By terminating all the fibre optics at the OLT, i.e. the same fibre optic topology as in the AON (point-to-point), this disadvantage can be overcome. Therefore, for future-proof infrastructure investment, reliable point-topoint fibre optics technology should always be considered Security and quality of services An aspect in public networks that is regaining importance is Quality-of-Service (QoS), which considering today s financial restraints is often forced to take a back seat. At the dawn of the ADSL rollout, the majority of services offered took a best effort approach, i.e. the data channel guaranteed neither a minimum bandwidth, nor any other quality features worth mentioning. As today however, Triply Play services (telephony, data and TV down one single line) are already transmitted to the subscriber, QoS applies more than ever. When surfing the Web, short delays of 1 2 seconds, e.g. when clicking on a link, do not really matter. During a phone call, this level of delay is however completely unacceptable. When watching TV, it is also no fun if the picture freezes before a goal is scored. As a result, the Triple Play services must be clearly separate and allocated priority. Although theoretically unlimited bandwidth is available in a fibre optic line, QoS not be forgotten. Not all QoS aspects can be responded to with bandwidth and neither PON nor AON can really provide unlimited bandwidth. Nowadays, the Triple Play offerings, implemented via copper wire often consist of two television channels with standard resolution (SDTV), a high-speed Internet connection (>3 Mbps) and at least one POTS or ISDN telephone connection. The current state of the art is that network operators are planning approx. 15 Mbps downlink capacity. In the future the end customer will be demanding high definition TV (HDTV). Two simultaneous TV channels will mean an unacceptable restriction for a family of four in the long term. Furthermore, currently ADSL 16 Mbps Internet access is already being marketed to private customers and including n telephone lines. Online gaming in the Far East popular for years is also looking promising in Europe. In this case, top rates of 50 Mbps per subscriber line could easily be reached. Today, standard VDSL2 access would not be able to cope. The scenario described above indicates what the private consumer will look like in the near future. If such a scenario appears exaggerated, we only have to recall the situation 10 years ago when modern end customers still used 56 kbps dial-up modems to read s, for sending faxes and for home banking. In comparison to today s standard 3.5 Mbps ADSL connection, the bandwidth has increased 62-fold! Special requirements from business customers, or demands for the backhaul of sub-networks, server connections or high performance IT applications would easily exceed these quality specifications and require even greater high quality performance. AON PON Assessment Temporary increase in bandwidth (e.g. server back-up over night) Simple In an active access node, traffic shaping can regulate the bandwidth from the NMS control centre and for example during constant operation be switched to 100 Mbps, or ad-hoc to 1 Gbps. Prioritising services Simple Standard mechanisms at Ethernet/IP level can be used. Difficult Due to the TDM procedure, a fixed time slot is allocated to each customer. The signal must also be separated using a passive splitter, as passive splitters are not manageable. A further allocation of another time slot must be carried out. Simple Standard mechanisms at Ethernet/IP level can be used. Compared with an AON, the structure of the PON limits the flexibility to make any changes in bandwidth. Undecided In this case there are no significant differences KEYMILE 2008 Page 7

8 AON PON Assessment Delay, jitter and other effects on quality Mainly influenced by the design of the core network. Impact of faults in the access node As n subscribes in an active access node use n optical interfaces and the subscriber density of the interface card is relatively low compared with a PON-OLT, relatively few subscribers are affected if there is a malfunction. Effect of malfunctions and manipulation Thanks to the PTP architecture, each path can be assessed exactly right up to the end customer s ONT at the very least. In the worst case scenario, the laser on the AN for each subscriber can be deactivated by the control centre. Risk of eavesdropping (espionage) Each customer has dedicated fibre optics. In general, eavesdropping is not possible. Mainly influenced by the design of the core network. In an OLT, a passive splitter separates the optical subscriber interfaces into 32 or 64 signals. A subscriber subrack usually provides several subscriber interfaces. In comparison with an AON AN, a lot of subscribers are affected if a port, or even a card fails. Within a PON tree, all the subscribers are on the same optical point. If a faulty ONT causes faulty synchronisation, or produces an optically indefinable signal, a remote localisation of the malfunction in the ONT involved is not possible. As the ONTs are often in the end customer s home, it is impossible to estimate how long it will take to exchange an ONT. A PON tree is known as a shared medium, i.e. all subscriber signals are on one fibre optic terminal point. By allocating the time slot, the data is separated. The setup is in the customer s network termination. Reliability of the subscriber line (between the customer and AN and passive splitter) In an active network, a customer can basically be connected in a ring, or using dual-homing. In other words, a customer can be connected twice. Poor To date, there are no plans to connect customers twice in one PON. Reliability of the subscriber line (between passive splitter and OLT, or AN and edge switch) Poor If the connection is cut here, several hundred fibre optics are interrupted and have to be repaired. In this case, only one fibre optic line has to be maintained. Undecided In this case there are no significant differences. Any faults in the AN affect fewer customers than in an OLT. In the worst case scenario, a single ONT can bring an entire PON tree with up to 64 subscribers down if a technical malfunction or deliberate manipulation occurs. A faulty subscriber line on the AON can be very easily identified and eradicated. The data in the PON network is encrypted in a similar way to WLAN, nevertheless it is technically still possible to eavesdrop on another subscriber on the same PON tree. However, in-depth technical knowledge is required to do so. Availability of the PON, compared with the AON, is much worse. In reality cables are cut more often than is generally thought. A PON link between the splitter and OLT consists of a tiny fibre optic that can be repaired in a few hours KEYMILE 2008 Page 8

9 2.3. Business case aspects Using fibre optic cable promises virtually unlimited bandwidths, however the network operator only ever has just the copper wire line in the last mile. That means that if the DSL technology is no longer adequate, new optical cables must always be laid. The high investment costs of this infrastructure, combined with telecommunications providers falling revenue at the same time, mean it is often difficult to put a business case to investors and network providers management boards. Nowadays the ICT industry is spoilt with returns on investment of 1 3 years. But when expanding FTTH and FTTC networks, (regardless of whether PON or AON technology is used), it sometimes takes more than 10 years. Nevertheless, depending on the application and conditions at the time, business cases vary greatly, depending on whether passive or active access technology is used for an FTTH rollout. The main differences in investment costs (capital expenses, CAPEX) and operating costs (operational expenses, OPEX) are compared with one another below Investment costs (CAPEX) comparison AON PON Assessment Costs of the subscribers terminal equipment (CPE) As standard Ethernet technology can be used. Today, simple ONTs (e.g. Ethernet media converters), with functions similar to an ADSL-NT, are available for under $30. Costs of the network technology (active components) Because each subscriber has a dedicated laser port on the AN. If a fibre optic path is divided up into several customer connections, additional active equipment is required. As ONTs in the PON environment are (despite standardisation) not interchangeable between different manufacturers. Which means the selection of models is restricted and the savings provided, because a larger number is produced, are negligible. As a single port on the OLT can be shared by several customers. If a fibre optic has to be shared by several customers, a simple passive splitter can be used. Costs of the network technology (passive components and infrastructure) Because of the greater number of optical subscriber interfaces in the access node. Network rollout costs Each subscriber must be connected individually in a star shape. As one laser on the OLT is shared by n subscribers because the passive splitter is used. Different Depends on the fibre optic topology. If the same topology is used as in an AON, the costs are similar (fibre-rich approach). If the fibre optic network is tree shaped, cost savings are possible compared with an AON. A PON network architecture using a small splitter with 2 or 4 branches allows costs to be shared efficiently (e.g. in terraced houses). The CAPEX bonus of AON networks should not be underestimated, because the CPE share in the total costs is usually the greatest (often >50 %). Because optical paths can be used by several subscribers, PON is a bonus because of the price per subscriber. In this case, passive technology clearly has the upper hand. Depending on the fibre optic topology, PON network architecture can be cheaper in large-scale rollouts KEYMILE 2008 Page 9

10 2.3.2 A comparison of operating expenses (OPEX) AON PON Assessment Space required for systems technology Because of the port density of the active AN, the space required is just as great as for a DSLAM. Space required by cable Great One fibre optic cable at the AN per subscriber. Energy consumption Because of the high number of laser interfaces. Because a single optical port on the OLT for up to 64 customers is used, the space required at the OLT for systems technology is very low. Over 8,000 subscribers can be placed on a single rack using today s technology. One fibre optic cable can supplied to up to 64 subscribers. Because of the passive splitting. Level of maintenance Active access nodes require an external In an outdoor cabinet, the passive power supply, plus battery to supply splitter needs virtually no maintenance. emergency electricity. This is a disadvantage, above all in FTTC networks, Malfunctions are very seldom. External power supply is not required. where the AN is on the outdoor cabinet. Level of difficulty in identifying and eradicating malfunctions Because in AON networks it is easy to carry out an end-to-end diagnosis right into the subscriber's home, due to the PTP topology and the possibility of assessing the dedicated optical transmission path via the NMS. Follow-up costs for upgrades Because of the better granularity of the ANs and the separation of the customers (PTP), individual upgrades can be carried out in the AON and for example CPE can be exchanged. As in the worst case scenario, a faulty ONT cannot be deactivated by the NMS centre. A local visit to the customer is required. Depending on the accessibility of the ONT, this can take a long time. An entire PON tree is affected by an upgrade. All ONTs have to be exchanged at the same time. As a result, individual upgrades are virtually precluded. PON s space-saving potential in the collocation room is greater compared with AON. Due to the wide ranges of PON paths, in comparison with copper wire, some MDF sites may not be necessary at all. The space PON saves in fibre optic cable is particularly critical in central OLT locations. Because of the passive splitter and higher subscriber density on the OLT, the PON is much better in this case. In this case, the PON is also at an advantage because there are fewer active components in the network. Identifying and eradicating faults in the AON is a lot easier than in the PON, due to the PTP topology. Nevertheless, in the PON the ability to analyse faults by using monitoring systems can be improved. Because of the greater individual flexibility, AON has an advantage where upgrades are concerned KEYMILE 2008 Page 10

11 2.4. Flexibility and scope for usage Previous findings in the comparison of AON and PON have already highlighted key differences. Apart from technological differences, there are further differences between the two optical access technologies, depending on the operator s business strategy. AON PON Assessment Suitability for connecting up housing estates (green field) Satisfactory The requirements for rolling out active networks are higher. The fibre optic infrastructure is simpler. The requirements for passive splitters in outdoor cabinets are low (no power needed, no problems with heat/cold). Level of suitability for connecting large-scale/business customers Very good In this case advantages on flexibility, security and performance really pay out. A router or switch can be used as an optical network termination to separate services. Poor The customers in a PON tree are all treated the same. Individual features can only be implemented at protocol level above layer 3. Level of suitability to provide telephony and high-speed Internet (HIS) at the same time No major restrictions. No major restrictions. Level of suitability to provide telephony, HSI and television (Triple Play) at the same time For transmitting n HDTV channels, AON can also mobilise enough bandwidth reserves. Suitability to provide additional services AON technology can be adapted to suit individual requirements. Satisfactory PON does have the advantage that some systems are capable of transmitting analogue TV (similar to a CATV network), however the usual bandwidth for broadcasting several HDTV channels might not be sufficient. Poor The range of specialised terminal equipment is very limited because of dependency on manufacturers. The rather inflexible bandwidth management, based on TDM procedures, is a disadvantage. Flexibility of usages as regards optical network termination As AON uses standardised Ethernet interfaces, a variety of different devices can be used for network termination. Ranges (max. length of the subscriber access line) Very good Maximum of about 70 km without repeaters. Backhaul of sub-networks and network elements A normal AN subscriber interface can also be used for backhaul jobs (e.g. of a DSLAM, radio equipment etc). Poor Today there is no real interoperability between rival PON technologies, even within the same PON technology. Operators are forced to purchase the ONTs and ONUs from the OLT supplier (dependency). Up to 20 km depending on passive splitter. Poor A PON interface board can only be used for implementing PON trees. Because of the lower requirements, a PON network can be installed more quickly and cheaply. Requirements from bulk customers are always special, PON network concepts tend to be more static. Therefore, in this case the active approach is a lot better. Undecided From a technical point of view, both PON and AON can be used here without any problems. An optical network rollout is a long term investment. If we assume that HDTV will be the standard format in the future, active networks have the upper hand, due to their high levels of bandwidth reserves. The requirements for additional and possibly new services when designing a new network are often not specified to the last detail. PON's limits could significantly inhibit business cases in the future. In this case, the operator of an AON network can act more flexibly and make use of real price savings. When using feature-rich IP equipment instead of an ONT, the provider can expand his range of services by leasing additional features (additional VPNs, hosted PBX ) Optical components can be selected individually As an active access node is similar to an Ethernet switch in the way it works and provides standard Ethernet interfaces, it can also be used for various backhaul jobs KEYMILE 2008 Page 11

12 3. Summary Finally we should not forget that a generic comparison of technologies, such as this one, cannot always apply in all cases. The balance can easily shift from one side or the other depending on statutory, commercial or structural constraints. Basically, passive optical networks are a better choice for network operators who want to supply a very large number of subscribers, like the (previous) network operators who had a monopoly. These operators tend to aim more for the mass and private customer market. In this case, PON can throw its commercial benefits into the balance and at the end of the day compensate for various operational disadvantages. Active optical technology is more suitable for private network operators, that either lay their own fibre optic infrastructure, or use debundled fibre optic lines (Fibre Local Loops). customers, multi-dwellings, universities, local authorities etc ), as in these cases flexibility, quality and security are demanded. And because of the way they are structured, PON networks struggle to fulfil these requirements. As standardised ONTs are used, the commercial aspects of supplying households on a large scale should be weighed up too and can compete with PON systems. Nevertheless, as PON networks are on the increase, it is likely that some of the disadvantages of PON listed here will gradually be eliminated. However some of the inherent features of a PON will remain. But one thing is almost certain, the fibre optic based access network, and therefore end customer products too, will constantly be upgraded to handle more than 50 Mbps. The whole issue is set to stay an exciting one AON is perfect for high-profit end customer segments (such as for example business Requirement AON s suitability PON s suitability Individual assessment Bandwidth Bandwidth allocation Maximum bandwidth per subscriber Bandwidth increase Security and quality services Temporary increase in bandwidth e.g. Overnight server mirroring Prioritising services Delay, jitter and other effects on quality Impact of malfunctions in the access node Effect of malfunctions and manipulation Risk of eavesdropping (espionage) Transmission reliability, I. Transmission reliability, II. Operating costs (OPEX) Place required for systems technology Room required by cable Energy consumption Level of maintenance Level of difficulty in identifying and eradicating faults Follow-up costs for upgrades Investment costs (CAPEX) Costs of the subscribers terminal equipment (CPE) Costs of the network technology (active components) KEYMILE 2008 Page 12

13 Requirement AON s suitability PON s suitability Costs of the network technology (infrastructure) Rollout costs Flexibility and scope for usage Suitability for connecting up housing estates (green field) Suitability for connecting bulk/business customers Suitability for providing telephony and high-speed Internet (HSI) Suitability for providing telephony, HIS and TV Suitability for providing additional services Flexibility of usage re optical network termination Ranges Backhaul of sub-networks and network elements Individual assessment 4. Glossary Abbreviation Description Abbreviation Description 100BaseTx 100Mbit/s Ethernet, copper interface ISDN Integrated Services Digital Network 3G 4G Third generation of the mobile telephony standard Fourth generation of the mobile telephony standard ITU-T LTE International Telecommunication Union, Telecommunication Standardisation Sector Long Term Evolution ADSL Asymmetrical DSL MDF Main Distribution Frame AN Access node MDU Multi Dwelling Unit AON Active Optical Network MSAN Multi-Service Access Node APON ATM PON NMS Network Management System ATM Asynchronous Transfer Mode OLT Optical Line Termination BPON Broadband PON ONT Optical Network Termination CaTV Cable television P(A)BX Private (Automatic) Branch Exchange CO Central Office PMP Point-to-Multipoint DSL Digital Subscriber Line PON Passive Optical Network DSLAM DSL Access Multiplexer POTS Plain Old Telephony Service EFM Ethernet First Mile PTP Point-to-Point EPON Ethernet PON QoS Quality of Service FTTC Fiber-to-the-Curb SAL Subscriber access line FTTE Fiber-to-the-Exchange SDTV Standard Definition TV FTTH Fiber-to-the-Home TDM Time Division Multiplex GEPON Gigabit Ethernet PON VDSL Very high-speed Digital Subscriber Line GPON HDTV Gigabit PON Definition TV WiMAX Worldwide Interoperability for Microwave Access ICT Information Communication Technology IP Internet Protocol IPTV Television over IP KEYMILE 2008 Page 13

14 Publisher KEYMILE International GmbH Europaring F Brunn am Gebirge, Austria Phone Fax Internet Mail KEYMILE 2008 Page 14