Title of Invention

"FIBER ACCESS SYSTEM"

Abstract

The present invention relates to a fiber access system (FAS) which comprises a host digital terminal (HDT), Optical distribution network (ODN) and a plurality of optical network units (ONUs). The HDT has the capability of operating at least 4 ODNs, each of which is supported by a Separate ODN interface. HDT - ODN interface is capable of supporting at least 32 ONUs. The HDT has a management interface to provide appropriate administration and management commands.

Full Text

The present invention relates to a fiber access system comprising a main/station and a number of substations. The telecommunication system of the present invention is an optical network based system referred to as fiber access system (FAS). The present invention further relates to a novel main station for use in such a system. The novel main station of the Fiber access system is a host digital terminal (HDT) which is located in an exchange building. This main station of the fiber access system of the present invention forms subject matter of a co-pending Indian patent application No. 320/DEL/99, The host digital terminal (HDT) interfaces with one or more Optical distribution network (ODNs), and a number of optical network units (ONUs), typically located in a building or street locations. The optical network units employed in the present invention are novel network units and therefore form subject matter of a copending Indian patent application. The main station, i.e., the host digital terminal of the fiber access system of the present invention has a capacity of operating at least 4 ODNs, each ODN being preferably supported by a separate ODN interface. HDT-ODN interface is capable of supporting at least 32 ONUs. The host digital terminal has a management interface which enables communication with the operations system. The fiber access system of the present invention can be provided in various configurations, e.g., FTTC (fiber to the curb), FTTB (fiber to the building) and FTTO (fiber to the office) based on passive optical network (PON). These configurations define only a few configurations and are not defined to restrict the scope of the present invention. The present invention can be understood clearly and explicitly from the accompanying drawings which define the features of the invention. These drawings, however, do not restrict the broad scope of the invention. According to the present invention there is provided a fiber access system (FAS) comprising a host digital terminal (HDT), optical distribution network (ODN) and optical network unit (ONU); said HDT interfacing between at least one ODN and a number of ONUs wherein each said HDT-ODN interface supports at the least 32 ONUs and the said HDT-ONU connection allows point to point transmission (from HDT to ONU's) and multipoint to point transmission (from ONU's to HDT) characterized in that said HDT comprises an operation, administration and management unit, enabling communication with the operating system, capable of operating at least 4 ODNs wherein each ODN is supported by a separate. ODN interface capable of supporting at least 32 ONUs. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure I defines the architecture of the fiber access system of the present invention. Figure 2 shows direct interface of the fiber access system of the present invention with exchange. Figure 3 shows FAS in SDH network. Figure 4 shows the functional block diagram of HDT. Figure 5 shows the ODN block diagram. Figure 1 as accompanied with the present invention defines an outline of the fiber access system of the present invention. This defines the basic architecture of the fiber access system. The Fiber Access system of the present invention finds different uses and applications. Of the various uses and applications of the FAS of the present invention, two major applications are : 1. Direct interface with exchange: This is applicable when HDT and exchange are in the same building or very close to each other. Minimum 32 numbers of 2Mb interfaces exist between HDT and exchange. The direct interface with exchange is clearly brought out and can be understood in a better manner with the help of the accompanying figure 2. 2. Interface via SDH ring: This application is most suitable when a large size exchange is deployed and is extended to FAS subscriber via SDH ring. The SDH/ADM ring network provides transparent transport of the HDTV through 2 Mb interface. An explicit description can be referred to in the accompanying figure 3. The fiber access system of the present invention is capable of supporting many devices such as analog telephony (POTS), analog leased lines, ISDN-BA, ISDN-BRA and the like, and also of upgrading the present system to BISDN. Further, digital video interactive and distributive is done by reconfiguring the prevalent system in a cost effective and practical manner while causing a minimum disturbance to existing customers. GPONA allows for evolution of optical access network (OAN) to enable and support future broad band services with bit rates greater than ISDN primary rate, i.e., to support GPONB. GPON-B supports the digital video (interactive and distributive) as well as BISDN (with different User Network Interfaces) services. The communication mechanism between the host digital terminal (HDT) and optical network unit (ONU) employs use of time division multiplex/time division multiple access (TDM/TDMA) transport protocol over an optical distribution network. The subscriber interfaces are provided at the ONU. Services available to the subscriber are either POTs or ISDN-BA or ISDN-PRA. The TDM/TDMA protocol is well known in passive optical networks wherein it is employed to permit transactions between a single base station and a plurality of base stations. The transmission technique employed by the system of the present invention allows the HDT-ONU connection to be point to multipoint as well as allows point to point transmission. The multiple access is based on TDMA transmission method whereas bi-directional transmission scheme is based on space division multiplexing (SDM). Further, to allow sharing of optoelectronics among many ONU's TDM downward/TDMA upward technique is used. The interactive services employs use of 1260nm-1360nm for both upstream and downstream transmission on separate fibers for both simplex and duplex transmission system. The system of the present invention also uses 1475nm-1565nm wavelength for analog CATV distribution and B-ISDN services. The novel host digital terminal of the fiber access system of the present invention provides network side interface of the Optical access network and is connected to at least one ODNs. There are different interfaces associated with the Host digital terminal which are ODN interface, exchange interface, TMN interface and user interface. Host digital terminal of the system of the present invention operates at least four ODNs through the specified interfaces. On the optical distribution network side, one HOT interfaces with upto four passive optical networks (PONs) each containing upto 32 optical network units (ONUs) located near the customer premises. Each ODN interface uses separate fibers for upstream (ONU-HDT) and downstream (HDT-ONU) transport. A TMN interface accesses the FAS system through control terminal via a defined interface. This module sends or receives messages to/from network manager and translates them to appropriate operation administration and management (OAM) commands. The user interface, a proprietary interface, is in the form of a PC which has a serial link with a single HDT. It provides a graphical user interface to an operator for administration or maintenance commands. The HDT provides at least one optical interface towards the optical distribution network and provides at least one network interface on the network side of the OAN. The HDT is co-located with in a local exchange or at a remote location. It comprises the means necessary for delivering different services to the required ONUs. It multiplexes and cross connects the bearer channel and other information channels onto appropriate timing slots of transmit and receive paths. All maintenance and operation functions for the fiber access system of the present invention are supported by host digital terminal (HDT) of the present invention. Various sub units of HDT which are: • VPU V5 protection unit • VLT V5 line termination unit • VSP V5 signal processing unit • XTU Cross connect and timing units • TTC TDM/TDMA termination controller • OAM Operation Administration and Management unit Figure 4 represents the functional block diagram of HDT. All sub units of the host digital terminal (HDT) have following features in common: • The front plate of each plug in unit includes on line and fail indicators to provide continuous status indication and immediate indication of a failed component. • Units protected by redundant units are designed such that failures do not interrupt service. • Plugging and unplugging HDT sub units from a line backplane does not affect services on other units. • HDT sub units are keyed to prevent insertion into the wrong slot. Therefore the host digital terminal employed by the system of the present invention is designed to prevent any loss or damage to the system due to failure of a component. Not only indications of failure of a component are given, but the system is designed to prevent interruption of system despite failure of a component. OPTICAL DISTRIBUTION NETWORK The ODN provides the optical transmission means from the HDT towards the users and vice versa. ONU's provide the user side interface of the OAN and are connected to the ODN. The optical distribution network is made up of splitter based passive optical network consisting of single mode fibers, splitters, splitter housing. One down stream fiber from the host digital terminal is divided through one or more splitters into as many as 32 fibers each connecting to an ONU. The upstream fibers from those 32 possible ONUs are combined into a single fiber leading back to host digital terminal. One host digital terminal can supports upto four such networks for a total of 128 ONUs each with 32 B channel capacity. The optical distribution network has been clearly shown in the accompanying figure 5. OPTICAL NETWORK UNIT This unit is a novel unit and forms subject matter of a copending Indian patent application. ONUs provide the interface between the ODN and the subscribers. Each ONU is connected to the end of a branch fiber pair near the subscriber that it serves. The ODN interface of the optical network unit provides a set of optical physical interface functions terminating the relevant set of optical fibers of the ODN. Regarding power supply there is a centralised supply unit which receives a predetermined input and generates a specific output. Through the backplane power is fed to the subsystem of ONU. A battery back up is provided which allows ONU to continue to function in the event of the failure of the main supply . During change over to backup batteries, ONU configuration is retained. Status of battery back up is constantly monitored and recorded at the host digital terminal. There are various modules associated with the fiber access system of the present invention for effective functioning of the communication system of the present invention. The administration module performs functions such as provisioning, configuration and inventory management of various logical resources. This functionality is concentrated mainly in the host digital terminal and the UT. Maintenance module of the fiber access system relates all hardware and software maintenance functions and performance monitoring and is in the form of embedded software distributed across the host digital terminal and the optical network units. Transport module is localized to the TTC and OCC for the transport control functions. The signalling module is distributed across the ONU and the HDT to provide multiplexed interfaces for bearer channels between the LE and the HDT. The V5 interface is of the dynamic concentrator type and includes link control procedures, PSTN protocols, bearer channel control, protection control and ISDN-D channels protocols. There are two types of messages which flow in the system and these are call supervision messages and the other are operations related messages. The ONU-HDT link is transparent to the type of messages. All messages go through an EOC channel. There are three types of message links between ONU and HDT. • Operations message link • PSTN message link • ISDN-D channel link Operations message link is a logical link for the remote operations messages from the OAM controller in HDT and TDMA port at ONU. The operations message packets are identified by the packet handling block in the HDT and sent to the testing block or the customer interface. The packets in the HDT are picked up by the packet handler. All operations messages are directed to the OAM controller. In PSTN message link all PSTN signalling messages generated by the user port in the customer interface units is handled by a network layer over shared HDLC k links between all the cards in ONU and the TDMA port. There packets are consolidated into a common message link and all packets are sent to the packet handler in HDT. The message flow between HDT V5 and LE V5 consists of five types of logical message links between HDT and LE. All these links are facilitated via a data link based on the LAPD. Layer two peer to peer messages are exchanged at the time of system initialization between LAPD processes at the two ends and multiple data links are established. There are separate data links for each protocol. The link control messages are between the link manager and the data link layer at the two sides that is HDT and LE. All control messages are multiplexed at layer 3 and carried over the control layer 2 data link over V5.1 interface. There are four type of messages flowing between AN protocol and LE control protocol in either direction over a control data link. They are port control messages, port control ack, common control and common control ack. The port control type of messages flow between individual port related control entities on either side by means of layer 3 address. The common control message is exchanged between two common control entities on either side of the V5.1 interface. The PSTN signalling messages from the ONUs are demultiplexed at the TDMA card in the HDT and sent to PSTN protocol in V5 processing block. The PSTN messages are exchanged between the HDT and the LE-PSTN protocols over one data link per V5.1 interface. The protocol is disconnected by disconnect request message. The ISDN D-channel data packets are multiplexed through a from envelope function in the V5 and are sent over a data link to the ISDN-D channel handling block in the LE. Further the bearer control message link applies only to V5.2 while protection protocol messages are as per V5.2. When system is powered on it performs self check of all the module and enables sequential initialization of the system (for HDT and ONU). After the boot up of system (HDT or ONU) following information is to be downloaded to HDT and ONUs from the user terminal: • Subscriber information-class and priority • Cross connection mapping Exchange interface initialization Automatic reconfiguration occurs in case of switch over of traffic on any PON to redundant TTC card. In case of card replacement or ONU upgradation inventory and reconfiguration information is exchanged with the user terminal. All testability features are inbuilt in the system. While designing the system following points are considered: • Self test features • Monitoring points to be provided for critical signals • Easy accessibility to the critical signal The invention hereby has been described in brief and is a mere statement of invention, which does not and shall not restrict the broad scope of the invention. WE CLAIM: 1. A fiber access system (FAS) comprising a host digital terminal (HDT), optical distribution network (ODN) and optical network unit (ONU); said HDT interfacing between at least one ODN and a number of ONUs wherein caeh said HDT OBN interface supports at the least 32 ONUs and the said HDT-ONU connection allows point to point transmission (from HDT to ONU's) and multipoint to point transmission, (from ONU's to HDT) characterized in that said HDT comprises an operation, administration and management unit, enabling communication with the operating system, capable of operating at least 4 ODNs wherein each ODN is supported by a separate. ODN interface capable of supporting at least 32 ONUs. 2. A FAS as claimed in claim 1, wherein the said HDT interfaces with maximum 4 ODNs , each ODN being supported by a separate HDT-ODN interface. 3. A FAS as claimed in claim 1, wherein the said HDT has four types of interfaces viz HDT-ODN interface, HDT-exchange interface, HDT-TMN interface and HDT-user interface. 4. A FAS as claimed in claim 1, wherein the said HDT-TMN interface accesses the FAS through control terminal and sends or receives messages to/from network manager and translates them to appropriate administration and management commands. 5. A FAS as claimed in claim 1, wherein the said HDT-user interface is a proprietary. 6. A FAS as claimed in claim 1, wherein the said ODN provides optical transmission means from the HDT towards the user and vice versa. 7. A FAS as claimed in claim 1, wherein the said ONU provides the interface between the ODN and the subscribers. 8. A FAS as claimed in claim 1, wherein the said ODN interface of the ONU provides a set of optical physical interface functions terminating the relevant set of optical fibers of the ODN. 9. A FAS as claimed in claim 1, wherein the said HDT comprises an administration module for provisioning as well as configuring and inventory management of various logical resources. 10. A FAS as claimed in claim 1, wherein the said HDT and ONU comprise a maintenance module and a signalling module for maintenance functions and to provide multiplexed interfaces for the bearer channels between the LE and HDT respectively 11 A fiber access system (FAS) comprising a host digital terminal (HDT), optbal distribution network (ODN) and optical network unit (ONU) substantially as herein before described with reference to the accompanying drawings.

Documents:

319-del-1999-abstract.pdf

319-del-1999-claims.pdf

319-del-1999-correspondence-others.pdf

319-del-1999-correspondence-po.pdf

319-DEL-1999-Description (Complete).pdf

319-del-1999-drawings.pdf

319-del-1999-form-1.pdf

319-del-1999-form-19.pdf

319-DEL-1999-Form-2.pdf

319-del-1999-form-4.pdf

319-del-1999-form-5.pdf

319-del-1999-gpa.pdf

abstract.jpg