The STM-1 (Synchronous Transport Module level-1) is the

SDH SDH may refer to: Science, medicine and technology * Serine dehydratase, an enzyme * L-sorbose 1-dehydrogenase, an enzyme * Succinate dehydrogenase, an enzyme * Shubnikov–de Haas effect * Social Determinants of Health, economic and social condi ...

ITU-T The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Commu ...

fiber optic An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to ...

network Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics ...

transmission standard. It has a bit rate of 155.52 Mbit/s. Higher levels go up by a factor of 4 at a time: the other currently supported levels are

STM-4 The STM-4 (Synchronous Transport Module) is a SDH ITU-T fiber optic network transmission standard. It has a bit rate of 622.080 Mbit/s. The STM-4 specification is designed to carry 7,680 8-bit "voice" frames every 125 micro-seconds for a total pa ...

STM-16 Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting diodes ...

STM-64 Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting dio ...

and

STM-256 Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting diodes ...

. Above

wavelength-division multiplexing In fiber-optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i.e., colors) of laser light. This techniq ...

(WDM) is commonly used in submarine cabling.

Frame structure

The STM-1 frame is on the basic transmission format for

(Synchronous Digital Hierarchy). An STM-1 frame has a byte-oriented structure with 9 rows and 270 columns of bytes, for a total of 2,430 bytes (9 rows * 270 columns = 2430 bytes). Each byte corresponds to a 64kbit/s channel.3.3 Basic principles of SDH
Networks: internet, telephony, multimedia : convergences and complementarities By Daniel Hardy, Guy Malléus, Jean-Noël Méreur TOH: Transport Overhead ( + + ) * : Multiplex Section Overhead * : Regeneration Section Overhead * : AU-4 Pointers VC4: Virtual Container-4 payload ( + ) * : Path Overhead

Frame characteristic

The STM-1 base frame is structured with the following characteristics: * Length: 270 column × 9 row = 2430 bytes * Byte: 1-byte = 8 bit * Duration (Frame repetition time): 125 μs i.e. 8000 frame/s * Rate (Frame capacity): 2430 × 8 × 8000 = 155.52 Mbit/s * Payload = 2349 bytes × 8 bits × 8000 frames/sec = 150.336 Mbit/s

RSOH (regenerator section overhead)

* 1st row = Unscrambled bytes. Their contents should therefore be monitored * X = Bytes reserved for national use * D = Bytes depending on the medium (satellite, radio relay system, ...) The Regenerator Section OverHead uses the first three rows & nine columns in the STM-1 frame * A1, A2 The Frame Alignment Word is used to recognize the beginning of an STM-N frame * A1: 1111 0110 = F6 (HEX) * A2: 0010 1000 = 28 (HEX) * J0: Path Trace. It is used to give a path through an SDH Network a "Name". This message (Name) enables the receiver to check the continuity of its connection with the desired transmitter * B1: Bit Error Monitoring. The B1 Byte contains the result of the parity check of the previous STM frame, after scrambling of the actual STM frame. This check is carried out with a Bit Interleaved Parity check ( BIP-8). * E1 Engineering Orderwire (EOW). It can be used to transmit speech signals between Regenerator Sections for operating and maintenance purposes * F1 User Channel. It is used to transmit data and speech for service and maintenance * D1 to D3 Data Communication Channel at 192 kbit/s (DCCR). This channel is used to transmit management information via the STM-N frames

MSOH (multiplex section overhead)

X = Bytes reserved for national use. The Multiplex Section OverHead uses the 5th through 9th rows, and first 9 columns in the STM-1 frame. * B2 : Bit Error Monitoring. The B2 Bytes contains the result of the parity check of the previous STM frame, except the RSOH, before scrambling of the actual STM frame. This check is carried out with a Bit Interleaved Parity check (BIP24) * K1, K2 Automatic Protection Switching (APS). In case of a failure, the STM frames can be routed new with the help of the K1, K2 Bytes through the SDH Network. Assigned to the multiplexing section protection (MSP) protocol * K2 (Bit6,7,8) MS_RDI: Multiplex Section Remote Defect Indication (former MS_FERF: Multiplex Section Far End Receive Failure) * D4 to D12 Data Communication Channel at 576 kbit/s (DCCM). (See also D1-D3 in RSOH above) * S1 (Bit 5 - 8) Synchronisation quality level: ** 0000 Quality unknown ** 0010 G.811 10-11/day frequency drift ** 0100 G.812T transit 10-9 /day frequency drift ** 1000 G.812L local 2*10-8/day frequency drift ** 1011 G.813 5*10-7/day frequency drift ** 1111 Not to be used for synchronisation * E2 Engineering Order wire (EOW). Same function as E1 in RSOH * M1 MS_REI: Multiplex Section Remote Error Indicator, number of interleaved bits which have been detected to be erroneous in the received B2 bytes. (former MS_FEBE: Multiplexing Section Far End Block Errored) * Z1, Z2 Spare bytes

References

{{DEFAULTSORT:Stm-1 Synchronous optical networking de:Synchrone Digitale Hierarchie#SDH Hierarchiestufen