An Introduction to the Ericsson Transport Network Architecture ...

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84 Fig. 4 AXD 4/1 Devices Devices of AXD 4/1, Fig. 4, can be divided into four different groups: - Terminal Access Units (TAU) interfacing plesiochronous transmission systems: • TAU 140, interfacing 140 Mbit/s signals • TAU 34, interfacing 34 Mbit/s signals • TAU 16x2, interfacing sixteen 2 Mbit/s signals - TAU interfacing transmission signals belonging to the Synchronous Digital Hierarchy (SDH) family: •TAU STM-1E, interfacing 155 Mbit/s electric signals • STM-1 and STM-4 optical TAU will be provided later on - Devices interfacing special external signals: • ESU, External Synchronisation Unit for 2 MHz synchronisation signals - Devices for internal use: • CTU, Control Termination Unit, access unit for the Central Processor. Power distribution Power distribution in AXD 4/1 is decentralised. All boards containing electronic components are equipped with their own DC/DC converters, which produce the necessary voltages from the duplicated -48 V power source. This makes it possible to have truly duplicated power supply all the way from the exchange battery to the PBAs. Hardware Structure Basic Technology and Methodology The major part of the Hardware (HW) of AXD units is realised with Application Specific Integrated Circuits (ASIC). Texas BiC- MOS is used for high-speed applications. BiCMOS is a 0.8 micron process whose available speed in AXD applications exceeds 200 MHz. Gate arrays with a maximum of 100,000 usable gates are available. Motorola HCMOS 0.7 micron circuits are used for other system parts. Max. speed in AXD applications is above 60 MHz, and arrays with 127,000 usable gates are used. Structured HW design methodology has been used when designing ASICs. This means that functions are described in a High Level Language (Verilog); the code is then synthesised to gates and flip-flops by a synthesis program (Synopsys). This procedure increases design efficiency and facilitates the structuring of large arrays. The occurrence of a number of high-speed signals between different units places extremely stringent requirements on the analog parts. Analog parts handle the termination, generation and regeneration of line signals, and phase and frequency control of signals. A library of analog blocks with schematics, component specifications and layouts has been created, which allows identical functions to be implemented in the same way in the different Devices. The use of one standard internal interface reduces to the absolute minimum the problems with analog design. A new metric building practice conforming to ETSI standard is used. Boards with 6 to 10 layers are placed in cabinets with a board spacing down to 16 mm. Circuit ERICSSON REVIEW No. 3, 1992
85 Fig. 5 Functional partioning of Switching Cabinet Only one plane is shown CSB HCB VCB DMB SMB UP DP CSG SWP Rx Tx Clock generation and Synchronisation Board Horizontal Control Board Vertical Control Board Distribution Matrix Board Switching Matrix Board Unit Processor Device Processor Clock and Synchronisation Generator Switch Port Receiver Transmitter packages with a pin spacing down to 0.5 mm are used for some ASICs. Boards can be placed both vertically and horizontally. This allows the use of the crossboard technique: vertical boards are interfacing horizontal boards in the same subrack. The technology and methods described above offer a number of advantages: - Compact design, which gives high functional density per volume unit - Low power dissipation - High testability - Simple verification - Short design time. Switch Fabric The Switch Fabric which is the complete switch with all three planes, is implemented through single-type cabinets. The HW in one cabinet belongs to one Switch Fabric Plane. The maximum capacity of the Switch Fabric, in the present implementation, is 128STM-1 equivalent ports. Modularity The AXD 4/1 features two types of mechanical modularity: - Board modularity - Cabinet modularity. Each Switch Cabinet (SWC) has a capacity of 64 x 128 ports. Two SWCs are required to arrange a 128 x 128-port Switch Fabric Plane. The minimum capacity is four ports, and extensions can be made in steps of four. Board Functions Switching Network Fig. 5 shows the structuring of the main functions of the Switch Fabric on the different board types. The Clock generation and Synchronisation Board (CSB) generates all the clock and synchronisation signals required in the system. Each CSB receives clock frequency and phase information from the other CSBs. Information from the selected synchronisation sources is also received. The CSB boards of the three planes are interconnected to ensure synchronisation of the system. The three signals are also compared for supervisory purposes. The Horizontal Control Board (HCB) is used for distribution of clock and control signals. The clock signal from CSB is distributed through HCB to all vertical boards. ERICSSON REVIEW No. 3, 1992
Page 1: ERICSSON REVIEW 3 1992 An Introduct
Page 4 and 5: An Introduction to the Ericsson Tra
Page 6 and 7: 60 Fig. 3 AXD 155 system integratio
Page 8 and 9: Control and Operation of SDH Networ
Page 10 and 11: 64 These functions and a number of
Page 12 and 13: 66 to the OS upon detection of a se
Page 14 and 15: 68 BOX 3 The SDH NE MANAGEMENT ORGA
Page 16 and 17: Fig. 4 Control System Architecture
Page 18 and 19: 72 Fig. 6 Software Architecture CSA
Page 20 and 21: 74 Functional requirements Certain
Page 22 and 23: 76 Fig 10 SMUX Control System Hardw
Page 24 and 25: AXD 4/1, a Digital Cross-Connect Sy
Page 26 and 27: 80 Fig. 2 AXD 4/1, System Architect
Page 28 and 29: 82 Fig. 3 Time Space Switch structu
Page 32 and 33: 86 The control signals, which come
Page 34: 88 Fig. 8 Protection Switch Unit st

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