Tuesday, August 28, 2007

E1 Multi Frame Structure

E1 Multi Frame Structure
- A multi-frame is formed from consecutive 16 frames numbered 0-15
- It is used for adding information regarding the data:
- In TS0 ? synchronization between frames & Error Correcting
- In TS16 ? Signaling

TS-0 in E1 Multi Frame Structure
- Synchronization is gained in every 2nd frame. The synchronization pattern is 0011011.
Specifically in the even numbered frames (0, 2?) bits 1-7 (from 0-7) holds the mentioned

- Note that this synchronization does not involves a clock, but bits are transmitted

constantly even when the line is idle.
- Error correcting (optional) is done using a Cyclic Redundancy Check (CRC-4) that uses

4 bits for every half multi-frame (8 frames). specifically the 4 bits are placed in bit

0 of every 2nd (even) frame, before the synchronization pattern.
- Error indication bits using CRC-4 are held in frames 13 and 15
- Remote alarm indication bit is held in bit 3 of odd numbered frames (1, 3?)
- Other bits in the odd frames are spare bits.

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