LOGICAL CHANNELS
The 3G interface is layered into three
protocol layers:
-The physical layer (L1)
-The data link layer (L2)
- Network layer (L3)
Logical Channels
•What
Type of data I will sent
•It
may carry control data or carry user traffic
Transport Channels
•How
do I sent the information (the manner in which the data will be Transferred)
•Weather
the data is protected from errors
•Size
of the data packets
Physical channels
•Define
the way I sent the data
•What
is modulation
Logical channel types are classified into two groups:
-Traffic channels (user data)
-Control channels (Signaling )
Broadcast Control Channel (BCCH)
-Downlink channel for broadcasting system information.
Paging Control Channel (PCCH)
-Downlink channel transfers paging information when the UE is in idle mode.
Common Control Channel (CCCH)
-UE needs to access the network.
Dedicated Control Channel (DCCH) (Call signaling, handovers commands)
-Call Signaling between UE and the network.
Dedicated Traffic Channel (DTCH)
-User Data
Transport CHANNELS
•Dedicated
Transport Channel (DCH)
User Data
Call
Signaling between UE and the network (handover commands)
Common
Transport Channels
•Broadcast
Channel (BCH)
Continuous
transmission of system and cell information
•Forward
Access Channel (FACH)
Packet
data transmission in low rates
•Paging
Channel (PCH)
When
the network wants to initiate communication with the terminal.
•RACH
Uplink
transport channel used to make requests
to set up a connection
•HS-DSCH
Packet
data transmission in high rates
Physical CHANNELS
•P-CCPCH
Primary Common Control Physical Channel (DL)
Broadcasts
cell information
•SCH
Synchronization Channel (DL)
Fast Synch.
•S-CCPCH
Secondary Common Control Physical Channel (DL)
Carries
both the Paging Channel (PCH) and the Forward Access Channel (FACH).
•P-CPICH
Primary Common Pilot Channel (DL).
Aids
channel estimation (handover and cell selection).
•Physical
Random Access Channel (PRACH) UL
This
channel is used to carry access requests
•DPDCH (Dedicated Physical Data Channel)
User data and Call
Signaling
•DPCCH (Dedicated
Physical Control Channel )
Control to UE’s
Transmit Power
Control (TPC) bits used in Power Control
Pilot bits which are
used by the receiver to test decoding
Transport Format
Combination Indicator (TFCI)
•AICH Acquisition
Indication Channel
Acknowledges that
node-B has acquired a UE Random Access attempt
•PICH Page Indication
Channel
Informs a UE if it
should monitor the Paging Channel
Mapping of Transport Channels onto the
Physical Channels
•The different
transport channels are mapped to different physical channels.
