Ericsson MINI-LINK BAS, Техническое описание, Страница: 58 / 174

MINI-LINK BAS 5-2
Technical Description EN/LZB 111 0542 P2B
5.1 Introduction
In this chapter it will be presented a brief treatment of the
implementation of the Open Systems Interconnection (OSI) layers,
which are the Physical layer, LLC and MAC layers, in the
MINI-LINK BAS.
The following figure provides a description of the terms used in a
radio fixed or mobile link.
Physical layer handles the conversion between a digital stream and a
Radio Frequency (RF) signal, providing the following functions:
•
Media control loops
•
C-QPSK Modulation in both uplink and downlink
•
Automatic Transmit Power Control (ATPC) in uplink direction,
to prevent the ATs to create unnecessary interference to other
MINI-LINK BAS Cells and limit dynamic range requirements in
RN receiver.
In particular in this chapter it will be considered the Physical Air
Interface, whereas the aspects regarding the Users, Service Network
and Internal interfaces are described in the relative sections.
•
LLC layer creates the information frame structure to be
transported by the link. The LLC provides the following
functions;
•
Downlink Frame Alignment Signal (FAS)
•
Scrambling
•
Forward Error Correction (FEC)
•
Error control, by Cyclic Redundancy Check (CRC)
•
Performance monitoring