ZTE Corporation ZXG-BTS2 Manuale Utente

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Chapter 3 - Interfaces and Communications 
Confidential and Proprietary Information of ZTE CORPORATION 29 
1.  Layer-1 (physical layer) is the PCM digital link at the rate of 2,048 
Kbit/s. 
2.  Layer-2 (data link layer) is based on the LAPD. 
3. Layer-3 transparently transmits the layer-3 messages on the A 
interface and manages radio resources. 
The protocols related to the Abis interface are as follows:  
GSM 08.52 presents the basic principles and rules of other specifications 
for the Abis interface and how the service functions are divided between 
BSC and BTS. 
GSM 08.54 specifies the physical structure of the Abis interface. 
GSM 08.56 specifies the data link layer protocol for the Abis interface. 
GSM08.58 stipulates the layer-3 protocols of the Abis interface. 
GSM 12.21 specifies the O&M message transmission mechanism on the 
Abis interface.