Post on 22-May-2020
Implementa)onandValida)onofanIEEE802.11ahModuleforns-3LeTian,Sébas)enDeronney,StevenLatré,JeroenFamaey
UniversityofAntwerpeniMinds,Belgium
https://www.uantwerpen.be/en/rg/mosaic/software/ieee-802-11ah/
Tableofcontent
1. 802.11ah overview
2. Implementation in ns-3
3. Evaluation
1. 802.11ah overview
2. Implementation in ns-3
3. Evaluation
Comparing802.11ahtoWPANandLPWAN
Distance (m)
Rate (kbps)
10 100 1000
10
100
1000
1 LoRa
Sigfox
Dash7
802.11ah
ZigBee BLE
10x 10x
802.11ahinnumbers
ZigBee (802.15.4)
Bluetooth Smart
(802.15.1) HaLow
(802.11ah)
Frequency band
Sub-1Ghz, 2.4Ghz 2.4Ghz Sub-1Ghz
Channel bandwidth 0.3 – 2Mhz 2Mhz
1 – 2 Mhz (4, 8, 16 optional)
Data rate 20 – 250 kbps up to 1Mbps 0.15 –78 Mbps
Range 10 – 100m 300m 100 – 1000m
New802.11ahMACfeatures
High scalability
Fast association
Restricted Access
Window (RAW)
Low power consumption
TIM segmentation
Target Wake Time (TWT)
Subchannel selective
transmission
Fastassocia)on
Send association
request Association processing
Stations AP
Normal association
Fastassocia)on
generate value V
generate random number R
R <=V?
Yes
Send association
request
Waiting next beacon
No Add V to
beacon frame
Association processing
Stations AP
Fast association
AP set a threshold T
QL > T?
Yes AP decrease threshold T
AP increase threshold T
No
AP Check its queue length QL
Example of changing value v
“11-12-0112-04-00ah-supporting-of-the-authentication-association-for-large-number-of-stations.pptx”
RestrictedAccessWindow(RAW)beacon beacon
Without RAW, any stations can access
Time T Time T+1
RestrictedAccessWindow(RAW)
RAW 1 RAW 2
slot 0 slot 1 … slot N
Equal size RAW slots
beacon beacon
Any stations can access Any stations can access
Only be accessed by stations belong it
50%
Without RAW 32 RAW slots
Beacon !carrying RPS!
Beacon!carrying RPS!
1st back !off function!
Doze state!
1st back !off function!
1st back !off function!
1st back !off function!
slot 0! Slot 1! … …! Slot NRAW-1!
Doze state! 2nd back! off function! Doze state!
RAW!
Station 1, assigned to RAW slot 1!
Station 2, not belongs to current RAW group !
Two stage backoff of RAW!
AP!
Tableofcontent
1. 802.11ah overview
2. Implementation in ns-3
3. Evaluation
1. 802.11ah overview
2. Implementation in ns-3
3. Evaluation
PHYandMACimplementa)oninns-3
• Physical layer • MCS0~10 modulation/coding schemes for bandwidths 1—
16Mhz
• MAC layer • Association ID (AID) assignment • Fast association mechanism • Restricted access window (RAW)
Source code: https://github.com/MOSAIC-UA/802.11ah-ns3
ns-3wifimodel
DcaTxop/EdcaTxopN
MacHigh (ApWifiMAC/StaWifiMac)
MacLow
star transmission
enqueue packets
MacRxMiddle DcfManager
WifiPhy/YansWifiPhy
send packets receive packets
RTS/CTS /DATA/ACK transaction
receive
packet queue fragmentation retransmission
receive packets DCF function
access granted
request access
listener
listener
WifiChannel PropagationDelayModel
PropagationLoss Model
get delay get signal strength
send packets
InterferenceHelper/ErrorRateModel
get PER
PHY
MAC
RAWrelatedmodulesinAPside
Set RAW attributes
Create RPS element
SendOneBeacon ( )
Assign AID to stations SendAssocResp ( )
Create AuthenCtrl element
Add these element into Beacon
Adjust Authencation Threshold
Extract RPS element
Get its own RAW slot
Control two stage back-off
StaWifiMac:: startRAW ( )
Get AID
Read association response packets
Extract AuthenCtrl element
Get association threshold
Send association request or not
StaWifiMac::received ( )
Start/stop second back-off
Store/restore back-off value
Read received beacon
RAWrelatedmodulesinsta)onside
DcaTxop/EdcaTxopN module DcfManager module
StaWifiMac:: startRAW ( )
Fastassocia)onrelatedmodulesinAPside
Add RAW attributes
Create RPS element
SendOneBeacon ( )
Assign AID to stations SendAssocResp ( )
Create AuthenCtrl element
Add these element into Beacon
Adjust Authencation Threshold
DcaTxop/EdcaTxopN class DcfManager class
Extract RPS element
Get its own RAW slot
Control two stage back-off
StaWifiMac:: startRAW ( )
Get AID
Read association response packets
StaWifiMac:: SendAssociationRequest ( )
Extract AuthenCtrl element
Get association threshold
Send association Request or not
StaWifiMac::received ( )
Start/stop second back-off
Store/restore back-off value
Read received beacon
Fastassocia)onrelatedmodulesinsta)onside
Tableofcontent
1. 802.11ah overview
2. Implementation in ns-3
3. Evaluation
1. 802.11ah overview
2. Implementation in ns-3
3. Evaluation
Simula)onsetup
• STAs randomly placed around the AP • Log Distance Propagation Loss Model • Constant rate model • Variables
• Number of STA • Traffic load • Number of RAW groups(slots)
• Metrics • Throughput • Latency
Pathlosswithdifferentrange
NistErrorRate Model YansErrorRate Model
Date rate model MCS10, 1 MHz need to be implemented
Fastassocia)onVSnormalassocia)on
Fast association scales better as number of stations increase.
PerformanceofvariousRAWslotsnumbers(oneRAWgroup)
For large scale/traffic network, larger number of RAW slots performs better in terms of throughput and latency.
Queue of 10 packets
PerformanceofvariousRAWgroups
L. Tian, J. Famaey, and S. Latre. Evaluation of the ieee 802.11ah restricted access window mechanism for dense iot networks. WoWMoM, June 2016.
RAW results in bigger gain at higher traffic loads.
Many RAW groups is catastrophic for latency.
Simula)onresultssummary
• Fast association scales better as number of stations increase.
• RAW achieves better performance for large scale/traffic load.
• Optimal RAW groups determined by • metric (throughput, latency) • traffic load,station number
• RAW optimization algorithm needed !