Specifications

Radio Link Communications Model
Radio Frequency Channel Types
August 08, 2000 68P81095E55-E B-3
Data Link Layer
The data link layer is used to create and recognize frame boundaries. The sender
breaks the input data up into data frames, transmit the frames sequentially, and
process the acknowledgment frames sent back by the receiver.
This layer incorporates a subset of the Motorola Implementation of A-bis (Mobis).
Mobis provides the control and interactive capabilities to support the GSM A-bis
radio link standards. To accomplish this, the layer is subdivided into
• Logical Link Control
• Media Access Control
Logical Link
Control
Logical Link Control procedures are algorithms that operate on logical channels in
the Radio Link. The procedures are summarized in Table B-1
Table B-1 Logical Link Control Contents
Media Access
Control
Media Access Control entities are logical paths in the radio link that support
the control and transmission of voice and data from the 16-QAM carrier to
Radio Link Protocol. These pathways are applied to one or more of the
sidebands in the on-air carrier frequency. The major channel paths are
described in Table B-2.
Logical Link Control Function
Slot Information Procedure (SIP) Runs on the Slot Information Channel (SICH) and
allocates outbound point-to-multipoint timeslots
without regard to confirmation or connection
Random Access Procedure (RAP) Operates on the Primary Control Channels (PCH)
and Temporary Control Channels (TCCH).
Transfers short fixed-length control message units
on multiple-access channels to the L3 Control of the
network layer. This is used to control initial access
to the Cell’s Traffic Channels and Dedicated
Control Channels. RAP is a multiple-access,
unconfirmed, connectionless packet data protocol.
Associated Control Procedure (ACP) Operates in the Dedicated Control Channels
(DCCH) and Associated Control Channels
(ACCH). It provides the point-to-point data
protocol with connection-oriented and unconfirmed,
connectionless radio link controls to the L3 Control
of the network layer
Voice Channel Procedure (VCP) An unconfirmed data protocol used to transport
fixed-size voice VSELP-coded frames on the
Traffic Channels (TCHs).
Data Channel Procedure (DCP) Operates on the TCHs and is used to provide point-
to-point, circuit-switched, unconfirmed
transmission of data frames.
Data Packet Procedure (DPP) The DPP is a packet data protocol that provides
reliable connection-oriented and unconfirmed
connectionless service on a multiple-access channel
to the User Data stack.