random access procedure capacity evaluation in lte-a
TRANSCRIPT
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Random access procedure capacityevaluation in LTE-A
Soukaina Cherkaoui Herve Rivano Fabrice Valois
(1)
(2)
27, March 2015
1 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Outline
1 Contex & problem statementAccess capacity of a cellSlotted aloha
2 Contention-based random access: 4-steps procedure
3 Collision scenario
4 Access capacity evaluationAssumptions & parametersResults & discussion
5 Perspectives
2 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Access capacity of a cellSlotted aloha
Outline
1 Contex & problem statementAccess capacity of a cellSlotted aloha
2 Contention-based random access: 4-steps procedure
3 Collision scenario
4 Access capacity evaluationAssumptions & parametersResults & discussion
5 Perspectives
3 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Access capacity of a cellSlotted aloha
Targeted environment
Dense cellsSmall packets
Smartphones
MTC i.e sensors of smart-*environment
Access capacity of a Cell?
4 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Access capacity of a cellSlotted aloha
Netwok access metrics
Access Capacity:Number of successful simultaneous accessUnit = number of succesful access request/ period
Blocking probabilityNumber of failed request access
Access delay
5 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Access capacity of a cellSlotted aloha
1st random access protocolSatellite system, wireless..Principle:
When a node has a packet to send, itwaits unitil the beginning of the next slotIf no other nodes attempt transmissionduring that slot, the transmission issuccessful
Otherwise, CollisionCollided packet are retransmitted aftera random delay
Capacity evaluation in term of throughput
6 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Access capacity of a cellSlotted aloha
Access management techniques
7 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Access capacity of a cellSlotted aloha
Always Aloha for cellular networks access
Core of the access process in cellular networksfreedom degrees:
Contention spaceResources
Idea: decrease message lengthAloha: Full messageCSMA/CA: RTS/CTSLTE: preambles
Limit: ability to distinguish users
8 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Outline
1 Contex & problem statementAccess capacity of a cellSlotted aloha
2 Contention-based random access: 4-steps procedure
3 Collision scenario
4 Access capacity evaluationAssumptions & parametersResults & discussion
5 Perspectives
9 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
step1: Slotted-Aloha + preamble
10 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Step2: transmission of random access response
11 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Step 3: transmission of message 3
12 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Step 4: Contention resolution
13 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Outline
1 Contex & problem statementAccess capacity of a cellSlotted aloha
2 Contention-based random access: 4-steps procedure
3 Collision scenario
4 Access capacity evaluationAssumptions & parametersResults & discussion
5 Perspectives
14 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Cell view point
15 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
User view point
16 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Outline
1 Contex & problem statementAccess capacity of a cellSlotted aloha
2 Contention-based random access: 4-steps procedure
3 Collision scenario
4 Access capacity evaluationAssumptions & parametersResults & discussion
5 Perspectives
17 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Network level model
PerspectiveCell view point
Parameters impactNumber of available preamble for contention-based accessFrequency of Random Access slots
Performance metricSuccess ratio
18 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Assumptions & parameters
Periodic traficOne packet arrival per periodPackets are independent and identically distributed over a periodA user is either in:
Transmission mode (T-mode)Idle mode (I-mode)Backlogged mode (B-mode)
No radio propogation model integratedTransmission failure due to bad radio propagation: simulation inputparameter
19 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Model parameters
Notation parameter defaultsetting
Pd detection probability of pream-ble transmission
0.95
Pc collision probability of message3transmission
0.2
Pr reception probability on mes-sage3 transmission
0.9
backoffmax maximum value of backoff win-dow
5
maxretransmit number of allowed retransmis-sions
5
oppperiod number of opportunities per pe-riod
50
K number of available preambles 48
Table : Parameter setting
20 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Model parameters (cont’d)
Figure : Detectionprobability impact onsuccess ratio
Figure : Collisionprobability impact onsuccess ratio
Figure : Recetionprobability impact onsuccess ratio
21 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Figure : Impact of number of available preambles on success ratio
21 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Figure : Impact of number of opportunities per period on success ratio
21 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Figure : Minimum required preambles for supporting new arrivals peropportunity
22 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Outline
1 Contex & problem statementAccess capacity of a cellSlotted aloha
2 Contention-based random access: 4-steps procedure
3 Collision scenario
4 Access capacity evaluationAssumptions & parametersResults & discussion
5 Perspectives
22 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Perspectives
Short-term perspectives
Access capacity share between different user types (H2H - MTC)
User point simulationDistribution of # of retrialsAccess delay
Medium to long perspectives
MTC grouped accessGathering data to group headsAccess performed only by group headsGroup by application, localization..?
Virtualization of devices accessSpecially for V2I, MTC appliactions1 C-RNTI per application (instead of 1 C-RNTI per device)
23 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A
Contex & problem statementContention-based random access: 4-steps procedure
Collision scenarioAccess capacity evaluation
Perspectives
Questions?
24 / 24 Soukaina CHERKAOUI Random access procedure capacity evaluation in LTE-A