Unitrans ZXSM-600 (V2) SDH

Technical Manual

1. Digitization of vice signals : PCM communication techniques consist of three techniques

I. Sendin g end,

including low pass filter ,sampling, quantization, encoding (analog to digital conversion)

II. Channel part ,including transmission part and regeneration III. Receiving end , regeneration, Digital to analog conversion (decoding),low pass filter

2. PCM: E1=32 channels ,one channel rate 64kbit/sec, frame length 125micro sec T0: bit arrangement, T16: signaling, 32 channel rate is 2.048 Mbit/sec

3. Classification of optical Fiber: I. Uniform fiber: reflection rate n, n1>n2

II. Non – Uniform fiber reflection rate n, n2>n11. Single mode fiber: diameter about 10 micro meter, long distance fiber2. Multimode fiber : diameter about 50 to 75 micro meter,850 nanometer

4. Synchronous Digital Hierarchy (SDH): the synchronous Digital hierarchy (SDH) specified such attributes of the digital signals as frame structure, multiplexing mode, transmission rate level and interface code type, and provide a frame which is internationally supported, on which a flexible, reliable and convenient world class communication transmission network can be deployed.

I. Defects of PDH: Plesiochronous Digital hierarchy (PDH)There are three signals rate in the world: European, North American and JapaneseNorth America adopt system are: 1.5 Mbit/s (T1), 6.3(T2) , 45(T3)Japanese adopt the system are: 1.5 Mbit/s, 6.3, 32Europe adopt the system are: 2Mbit/s(E1), 8(E2), 34(E3) and 140 (E4)These three signals rate level are not compatible with each other which make it difficult for international internetworking.

II. There interfaces are incompatible with one another. Therefore network complexity and cost are increased.

III. PDH multiplexing structure base on point to point transmission in PDH ring shape protection cannot be implemented it work in unified way

a) Advantage of (SDH): Unified the regional standard of north America , Japan and Europe at the STM-1 level or higher

b) Unified the standard optical interface, which means the equipment from different manufacturer can be inter connected

c) After adoption of Add/drop multiplexer ADM software can be used to directly drop 2 Mbit/s low speed tributary signal from high speed 155Mbit/s code stream while PDH MUX and DEMUX are

d) 5% overhead bits have been allocated in the SDH frame structure, overhead bits that the network operator, management and maintenance ability can be greatly enhanced.

I. SDH Rates: STM-1: 155.529 Mbit/s STM-4: 622.080 Mbit/s

STM-16: 2488.320 Mbit/s STM-64: 9953.280 Mbit/s

a. SDH Frame Structure:

SOH area: Regeneration section overhead area (RSOH), Multiplex section overhead (MSOH) and administrator unit-pointer (AU-PTR)

Logic composition of SDH equipment: TM, ADM, REG , electrical REG and DXC.

Terminal multiplexing (TM): multiplex low speed signal on the tributary port into high speed STM-N of the line port or to drop low-speed signal from the STM-N.

Add drop Multiplexing (ADM):

Regenerator (REG): mainly perform optical power amplifier and increase transmission distance.

Cross connection equipment (DXC) .

SDH physical topologies: bus/line, star, ring, mesh topologies

SDH self-Healing Network: detect any failure communication will be re-established automatically

a) Line protection switching: when present fiber disconnected or some other fault occurred communication switched to standby fiber

b) self-healing ring network: i. dual fiber unidirectional path protection switching ring (1.8-1)

ii. Dual fiber unidirectional MS protection switching ring (1.8-2) iii. 4-fiber bidirectional MS switching ring (1.8-3)

II.