HYTAS

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HYTAS ( hybrid subscriber connection system ) is a technology developed by ke Kommunikation-Elektronik in 1994 to implement an active optical network architecture in a fiber optic network .

The system is part of the ISIS concept (integrated system for the provision of network infrastructure on an optical basis) from Deutsche Telekom .

HYTAS has a V5 interface for direct connection to the switching technology ( e.g. EWSD or S12 ) and is administered via the network management system KENOS NMS.

In essence, HYTAS implements a network structure as proposed in 1991 by the then Board Member for Technology and Networks at Deutsche Bundespost Telekom.

history

Based on experience with the development of optical line equipment for 34 and 140 Mbit / s from 1983, with PCM 2 systems from 1987 and the first transmission systems for the subscriber line area ( FONTAS ), which were supplied from 1991, HYTAS was launched in 1994, which included the The main product of ke communication electronics became and in 1997 made up the largest part of the optical access networks of the Deutsche Telekom AG.

Alcatel , Bosch and Siemens received orders to expand the HYTAS networks because the amount of technology to be installed exceeded ke's capacities.

In 1998, 30 network operators in 7 countries supplied a total of 5 million customers with voice and data services with HYTAS. In the course of closer integration into Alcatel, HYTAS was given the name Alcatel 1575 , initially competed internally with Alcatel 1540 Litespan, but was then discontinued.

Component overview

Optical Line Termination (OLT)

The exchange-side network termination of the OLT consists of:

  • TU2M and TUSig for connecting the switching technology via V5 interface
    • Alternatively, also Channel Banks (CHB) for leased lines are used.
  • Crossconnect (CC) for free interconnection of the B-channel and D-channel of the ISDN connections with a capacity of 1664 × 64 kbit / s
  • Optical multiplexer, transmitter and receiver (OMTR) assemblies that each optically transport up to 140Mbit / s (557 Mbit / s) to the OLD.
    • Alternatively, EMTR assemblies can also be used that transport electrically.
    • Alternatively, OMTR4 modules can also be used, which transport 557 Mbit / s.
  • A system management unit (SMU) that connects the system with the KENOS NMS and manages the assemblies in the OLT

Optical Line Divisor (OLD)

Available in different versions with 140 Mbit / s for outdoor installations or 557 Mbit / s for indoor installations. Divides the incoming signal into 10.24 Mbit / s (34 Mbit / s) data streams and distributes it to the ONUs or ONTs.

Optical Network Unit (ONU)

With FTTD consisting of ONT + SU.

ONU designs:

  • ONU-B: installation in building, for 16 SU
  • ONU-C: ONU-Curb for installation in KVz 83 MX for 16 SU
  • ONU-E: BGTR for installation in a system cabinet for 16 SU
  • ONU / NT: Combination of ONU-B and ONT-B for 16 SU + 12 ports
  • ONU-U: for installation in underfloor containers for 1 SU
  • ONU-S: for installation in KVz 92 for 1 SU
  • ONU-VE (ONU 5 Exchange): for installation in BVSt (area switching center), up to 472 TelAs per ONU
  • ONU-VC (ONU 5 Curb): for installation in KVz 83 MX, each ONU up to 376 TelAs
  • ONU-VB (ONU 5 Building): for installation in a system cabinet, up to 472 TelAs per ONU

The ONU terminates the 10.24 Mbit / s (34 Mbit / s) data stream from the OLD, divides it into four 2.56 Mbit / s data streams and distributes them to the integrated subscriber modules via a bus.

Optical Network Termination (ONT)

ONT designs:

  • ONT-S: Installation in KVz 92
  • ONT-U: Installation in underfloor containers
  • ONT-B: installation in the building
  • ONT-B / L: Installation in the building with local power supply
  • ONT 64: Installation in the customer's system cabinet
  • ONU / NT: Combination of ONU-B and ONT-B for 16 SU + 12 ports.

Only with FTTD. Consists of Line Interface Network Termination (LI-NT or LIH-NT), System Management Unit (SMU-NT) and 4 Port4 cards. The voltage is supplied from the OLD via a copper cable (exception ONT-B / L), this is operated with 110 V.

The line interface carries out the optical-electrical conversion and generates the 16 2.56 Mbit / s frames for the Port4 modules from the incoming 10.24 Mbit / s (34 Mbit / s) data stream from the OLD. The 4 Port4 cards each form 4 2.56 Mbit / s buses as a 4-wire interface towards the service unit. The remote supply voltage is also coupled in here via a phantom circuit. Depending on the cable type, the distance is limited to max. 200 m (6 dB at 1 MHz) to the remote SUs.

Service Unit (SU)

There are two types of construction:

  • for ONT and ONU in Euro card format
  • for ONU type V in double European card format

Euro card format: plugged into the ONU in the subrack (BGTR), with the ONT in a separate housing frame (GEHRA SU).

Provides the subscriber interface ready: U K0 interface for ISDN - basic access , S 0 interface for ISDN basic rate interface without NT , S 2M interface for ISDN primary rate interface and from interface for analogue phone lines . Depending on the type and connection, one to eight participants can be connected to each SU. The service units are powered remotely by the ONT .

variants

In Germany there are two different HYTAS variants based on Telekom's ISIS concept.

HYTAS indoor

The HYTAS components (OLT, ONU) are located exclusively within the local exchange and replace part or all of the remote peripheral unit (APE). According to the ISIS concept, this represents a preliminary stage of the outdoor expansion.

HYTAS outdoor

HYTAS-Outdoor with three different expansion levels:

The fiber optic connection extends to the cable distributor (KVz). This is where the ONU is located, which provides the subscriber interfaces.

  • FTTD - Fiber to the Door (glass fiber to the house)

The fiber optic connection extends to a few meters from the house. There is a container embedded in the street (or as ONT-S in KVz 92), in which the ONT is located, which provides up to 16 HYTAS buses.

  • FTTB - Fiber to the Building (glass fiber to the house)

This variant is less common in Germany and is basically comparable to the FTTC expansion. In this case, the ONU is located in a technical cabinet in the house.

Technical problems

In many cases, DSL is not available in the outdoor variant. For some time now, however, Telekom has been equipping certain cable distributors with outdoor DSLAMs for the FTTC expansion , provided that it appears economical for the company. FTTD installations do not benefit from such upgrades.
  • Low bandwidths
Within the HYTAS network there are bandwidth bottlenecks in many connection areas, as HYTAS is technically based on the plesiochronous digital hierarchy (PDH).

These problems mostly occur with older versions of the system. In some regions, Telekom is switching to replacing HYTAS with other technologies from other manufacturers in order to remedy these problems.

The broadband OLT (BOLT) was advertised as early as 1997, which should provide up to 442 2 Mbit / s through the integration of additional SDH interfaces on the exchange side. As part of the takeover of ke Kommunikation-Elektronik by Alcatel , the further development of HYTAS and thus also of the BOLT was stopped because Alcatel wanted to offer its own competing technology for network expansion.

swell

  1. ↑ Gerd Tenzer: Glass fiber to the house / Fiber to the home. Decker R. Von, 1991, ISBN 978-3-7685-0891-9 .
  2. ↑ ke communication electronics: a young company with a long tradition ( Memento from February 3, 1999 in the Internet Archive )
  3. ^ R. Ranft: Optical access networks of Deutsche Telekom. ( Memento of the original from February 27, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Deutsche Telekom instruction sheets April 1997 p. 212ff (PDF file; 726 kB) @1@ 2Template: Webachiv / IABot / www.training.telekom.de
  4. ↑ fiber optic technology. In: Onlinekosten.de
  5. ↑ Hybrid subscriber connection system . ke communication electronics. Undated publication by the manufacturer.
  6. ↑ More capacity for broadband connections in the HYTAS network . ke communication electronics. May 1997

Web links

See also