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explainin what is the relation between SDU and PDU and how are they formed in UMTS transport network.
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Understanding SDU and PDU and their application in UMTS
network
By Stefan Dolapchiev
PDU vs. SDU in IP network
4
3
2
1
4
3
2
1
Layer 4 PDU (TCP Segment)
Upper Layer SDU (Data)
L4 (TCP) Header
Layer 1 transmission
Layer 2 PDU (Ethernet Frame)
L2 SDU = L3 PDUL3 SDU = L4 PDU
Upper Layer SDU (Data)
L4 (TCP) Header
L3 (IP) Header
L2 (Ethernet)
Header
L2 (Ethernet)
Footer
Layer 3 PDU (IP Datagram)L3 SDU = L4 PDU
Upper Layer SDU (Data)
L4 (TCP) Header
L3 (IP) Header
In general, LnSDU = Ln+1PDU
UMTS Uu Interface Protocol Stack
Coding, Rate Matching, Spreading, Modiulation
AMR Voice
CS Data
PS Data
Network Control(CC/MM/GMM, etc.)
Radio Resource Control (RRC)
Medium Access Control (MAC)
Radio Link Control (RLC)
Packet Data Convergence
Protocol (PDCP)
Layer 1
Layer 2
Layer 3
Non Access Stratum
(NAS)
Access Stratum
Control Plane User Plane
Radio Access Bearers (RAB)
Radio Bearers (RB)
Logical Channels (DCCH, CCCH, PCCH,
BCCH, DTCH)
Transport Channels (DCH, PCH, BCH, RACH, FACH)
Physical Channels (DPCH, P-CCPCH, PRACH, SCCPCH, AICH, PICH)