-
Makidis [email protected]
mailto:[email protected]
-
RLC protocol overviewRLC/AM proceduresSimulation
setupPerformance of applications without contentionPerformance of
applications with contentionPerformance of CBR Media Distribution
applicationSDU discard policy impactConclusion
[email protected] 2
-
The RLC protocol
RLC/AM Functions
Frame types
SUFIs for the Status PDU
Windows
Protocol States
[email protected] 3
-
Radio Link Control protocol: link layer protocol for the
UMTS
Transparent Mode : No services provided by the RLCe.g. voice
calls
Unacknowledged Mode : Duplicate avoidance & reordering
only
Low delay and higher reliability than the raw link
e.g. video streaming using UDP
Acknowledged Mode : Reliable data transfer (mostly)
Sliding window protocol (like Selective Repeat, GBN)
Uses sequence numbers, performs retransmissions
[email protected]
All logos and trademarks are property of their respective
owners.
-
Not implemented
Transfer of user dataMostly reliable data transferDiscards data
after time period or number of (re)transmissions
Error correction
Sequence number check, duplicate detection, in - sequence
delivery
Protocol error detection & recovery
Flow control
Segmentation & reassembly, concatenation, padding
Ciphering
[email protected] 5
-
Re
se
t & R
ese
t A
CK
PD
US
tatu
s P
DU
Da
ta P
DU
Data (AMD) PDU
Has a sequence numberin [0, 4096)Contains segments of SDUs from
upper layersHas a polling bitCan have a piggybacked Status PDU in
the padding space
Status PDUHas one or more SUFIs (Super Fields)Used for reporting
ACKs/NACKsUsed by the SDU Discard functionUsed by the Flow Control
function
RESET & RESET ACK PDUUsed by the RLC Reset procedure
[email protected] 6
DATA
Sequence number
Length Indicator (LI) E
D/C
Length Indicator (LI) E
Padding orPiggybacked Status PDU
Byte 1
Byte 2
Byte 3 (opt)
Byte N
Sequence number P HE
SUFI 1D/C
Padding
Byte 1
Byte 2
Byte N
PDU type
SUFI k
SUFI 1
R1D/C
Padding
Byte 1
Byte N
PDU type RSN
HFNI
HFNI
HFNI
-
ACK/NACK SUFIsACK: Acknowledges all PDUs up to the ACKed
SNBITMAP: Contains bitmap indicating ACKed/ NACKed PDUs of the
LIST: List of SN/length pairs indicating NACKed PDUsRLIST: List
of NACKed PDUs in encoded, relative formThe spec does not specify
which SUFIs to use (other than ACK). We used ACK & BITMAP.
Move Receiving Window SUFIsMRW: Request from the Sender to
discard SDUs and Move the
MRW_ACKposition
Other SUFIsWINDOWwindow size (used for Flow Control )NO_MORE:
Indicates the end of the Status PDU
[email protected] 7
