Specifications

Radio Frequency Channel Types
August 08, 2000 68P81095E55-E B-1
Appendix B
Radio Frequency Channel Types
This chapter describes the communications model the iDEN
®
system uses on the
Radio Frequency portion of the system. The individual carrier uses several logical
channels in relation to established international standards. The constituent parts of
the model are also discussed in general terms.
Radio Link Communications Model
Various RF channel interface types are required to connect the Fixed Network
Equipment o the MSs. Each channel type is utilized to perform a specific task in a
specific manner of operation. This architecture is more readily visualized if it is
presented as it appears in an Open Systems Interconnection (OSI) 7-layer model.
Implementation of the OSI model is shown in Figure B-1.
Figure B-1 Implementation of OSI model on the iDEN Radio Link
Physical Layer
The physical layer of OSI refers to hardware-based encoding. The physical layer is
concerned with transmitting raw bits over a communication channel. The design
considerations are:
• to assure the data sent is the data received
• the amplitude frequency, time and modulation
• whether transmission is half-duplex or full-duplex
• how the initial connection is established
• how the link is torn down
The design issues here deal largely with electrical characteristics and procedures.
The over-the-air link is a combination of amplitude and phase modulation and digital
encoding on a 4-sideband analog suppressed carrier wave.
Application (7)
Presentation (6)
Session (5)
Transport (4)
Network (3)
Physical (1)
Data Link (2)
Logical Link Control (LLC)
Data Link (2)
Media Access Control (MAC)
Data Link (2)
Speech
VSELP
User Data Stack
L3 Control
BCCH RACH
CCCH TCCH
Random Access
M16-QAM
Reserved Access Packet Access
RF frame strucuture (Radio Link timeslots)
SICH DCCH TCH PCH
DCPVCPACP
ACCH
RAPSIP DPP
PCCH/SCCH
T. N. French