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Chapter 6 Interfaces and Protocols
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Broadcast Physical Protocol provides a logical channel struc-
ture.
Abis Interface
Layered Structure
of Abis Interface
Abis Interface
Description
Abis interface is the interface between
BSC
and
BTS
.
The layered structure of Abis interface is shown in
Figure 26
.
F
IGURE
26 L
AYERED
S
TRUCTURE OF
A
BIS
I
NTERFACE
1. Physical Layer
ZXSDR BS8800 employs E1/T1 trunk cable or Ethernet
cable.
2. Link layer
The link layer supports several protocols such as
HDLC
(High
level Data Link Control),
PPP
(Point-to-Point Protocol), PPP-
mux, PPPmultilink etc.
HDLC is bit—oriented data link layer protocol. The feature of
bit-oriented is, taking bit (not character) as the basic unit of
transmission and control information. The format of the data
frame is the same as that of the control frame, with good trans-
mission transparency, high efficiency, and continuous trans-
mission.
PPP is a link layer protocol designed for the simple link trans-
mitting data package between same modules.
PPPmux is to realize single PPP frame transmitting multiple PPP
packaging groups (sub frame), to reduce the PPP overhead
of each group, suitable for transmitting voice and data in low
speed link.
PPPmultilink is a link type, suitable for the link of any point-to-
point type. It is started when the flow exceeds some point in
one link and other link is started.
3.
IP
IP is the network layer protocol in the
TCP/IP
protocol family.
The IP data package includes the IP address of the target end
and the IP address of the source end.
4.
TCP
/
UDP
/cUDP
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