“WOMEN” Project Final Meeting Trento, Feb. 12th, 2008 1 UNITN: Description of Work Fabrizio...
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Transcript of “WOMEN” Project Final Meeting Trento, Feb. 12th, 2008 1 UNITN: Description of Work Fabrizio...
“WOMEN” Project Final Meeting
Trento, Feb. 12th, 2008 1
UNITN:Description of Work
Fabrizio GranelliDISI – University of [email protected]
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 2
UNITN role in a slide Goal: “Performance Enhancement of Wireless
Mesh Networks and Testbed Implementation”
WP1 WP3
T3.4 Stream Control WP4
T4.5 Network Capacity Analysis WP5 (Resp.)
T5.6 (Testbed) (Resp.) T5.7 (Trials) (Resp.)
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 4
P ay lo adI P
Head er
T3.4 “Stream Control” PAC-IP
Concatenate IP packets into a single link layer payload Share wireless overhead by entire group of packets
P ay lo adI P
Head er
Sender Receiver
P HYHead er
LLHead er
P ay lo adI P
Head er
P ay lo adI P
Head er
Link
Physical
Network
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 5
PAC-IP: Possible Implementations
I P la y e r
PA C -I PC on c ate n ator
L in k L a y e r
D e st 1
D e st 2
D e stN
+
I n t e r f a c eQ ue ue
T im e r s
M e diu m -bu s yIn dic ator
I P la y e r
PA C -I PC on c ate n ator
L in k L a y e r
D e st 1
D e st 2
D e stN
+
I n t e r f a c eQ ue ue
T im e r s
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 6
Evaluation Results Simulation
Ns-2 network simulator
0
1
2
3
4
5
6
7
0 300 600 900 1200 1500Packet size (Bytes)
Thr
ough
put
(Mbp
s)
MAC 802.11bSimulationsSingle-flow testbedMulti-flow testbed
No need to change Link or Transport layers
Good performance for small (< 750 bytes) packets
Testbed Modified Orinoco Silver
card’s driver Iperf traffic generator
ConcatenationON
ConcatenationOFF
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 7
TCP Performance Enhancement:TCP LogWestwood+ Design Objectives
To be more aggressive than Standard TCP to guarantee equal or better throughput and utilization
Fast increase for low window values while accurately approach the available pipe capacity
Small sensitivity with respect to RTT
TCP LogWestwood+ combines smart TCP Westwood window decrease with Logarithmic increase function
Ref.: D. Kliazovich, F. Granelli, and D. Miorandi, "TCP Westwood+ Enhancements for High-Speed Long-Distance Networks,“ ICC'06.
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 8
TCP LogWestwood+
Logarithmic
Linear AIMD(Standard TCP)
On packet loss (3 dup ACKs)
= * 2, if W < Wmax
= / 2, if W ≥ Wmax
≥ 2 (initial value)0 5 10 15 20Acknowledgements
Co
ng
est
ion
Win
do
w
TCP LogWestwood+TCP NewReno
Slow Start Congestion Avoidance
Logarithmic Linear
Window Control during congestion avoidance Wmax – window size before the last packet loss
occurred
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 9
TCP LogWestwood+:Performance Window Evolution
Physical Capacity
Total Capacity (+Buffers)
2Total Capacity
1000 1005 1010 1015 1020 1025 1030 1035 1040 1045 1050300
350
400
450
500
550
600
650
700
750
time (s)
Co
ng
est
ion
Win
do
w (
pa
cke
ts)
LogWestwood+Westwood+NewReno
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 10
Quantifying Cross-layer Design
Quantifying the effect of potential cross-layer interactions is very important to systematically relate such interactions to system outcomes to quantify the decision to take such interactions into account
We propose to quantify cross layer interactions by defining factors (parameters) and effects (measurements) across layers in a way that is common in system science and operations
research
Ref.: F. Granelli, M. Devetsikiotis, “Designing Cross-Layering Solutions for Wireless Networks: a General Framework and Its Application to a Voice-over-WiFi Scenario,” CAMAD 2006.
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 11
Quantifying Cross-layer Design Cross-Layer Sensitivity and Performance
Optimization
020
4060
80100
0
5
10
150
0.02
0.04
0.06
0.08
pkt ratedatarate
d2N
*/dD
dT
0.02
0.03
0.04
0.05
0.06
0.07
DTT
eDTTD
N DT
lnln00852.0ln0372.0278.0
7774.0 lnln0923.08143.05966.0*2
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 12
To define and validate an analytical model for connectivity and capacity of Wireless Mesh Networks, given design parameters n, r, l.
Traffic from/to mesh base station ≠ ad-hoc scenario
Network Capacity Analysis: goal
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 13
Problem Statement• Single-cell analysis
→ squared area
→ m = 1
→ interfering nodes
• Traffic to/from BS
• Hyp.: → IEEE 802.11 CSMA/CA – RTS/CTS*
→ MFR routing
→ r = 250 [m]
* → “Performance Analysis of the IEEE 802.11 Distributed Coordination Function”, by G. Bianchi (JSAC, March 2000)
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 14
Connectivity analysis
No. offorwarding nodes*
Poisson distribution: λ = nf
!);(
k
ekf
k
fnfisol enfp );0(
* → “Optimal Transmission Ranges for Randomly Distributed Packet Radio Terminals”, by Takagi e Kleinrock (March 1984)
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 15
Connectivity analysis
hisolconn pp 1
*
apprd
Dh
dpd
dpd
l
D
disol
D
r
disol
appr
appr
2
12
0
2
12
0
)1(
)1(
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 16
Capacity Analysis
Gn
n
n
n
n
nnnB
conn
connconn
2
1
11
3
12
ni → connected nodes at i-hops distance from the BS
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 17
Experimental Results: Capacity
Averaged on 50 runs
variable nl = 2500r = 250
Avg. error:17,53 %
Avg. stdev:22,85 %
Cumulative throughput
0
500
1000
1500
2000
2500
3000
3500
0 0,5 1 1,5 2 2,5 3 3,5 4 4,5
# forward nodes
[kbi
t/sec
] analysis
simulation
[kb
it/se
c]
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 18
Conclusions
A first model for connectivity and capacity of WMNs was developed and validated
Good accuracy Open Points:
Inter-cell interferenceHeterogeneous WMN (e.g. WiMAX+WiFi)Node movement (statistical model)
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 19
TCP over Infrastructure WiFi
LL-ACK
TCP Data
Mobile Node(MN)
Base Station(BS)
Channel Contention
Channel Contention
LL-ACKTCP ACK
WiFi (IEEE 802.11)IP Network
TCP DataPHY
HeadersLL
Headers
TCP ACKPHY
HeadersLL
Headers
Legend:
Transmitted at Basic rateTransmitted at Data rate
ApplicatioApplication Datan Data
AcknowledgementAcknowledgements at different s at different
layerslayers
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 20
ARQ Proxy - Approach
Idea: To substitute the transmission of TCP ACK packets with a short MAC layer request on the radio link for multilayer ARQ overhead reduction
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 21
ARQ Proxy - Approach
TCPData
PHY /LLHeaders
LL-ACK
Fixed Host(FH)
IP Network
ARQ Proxy MAC ARQ ClientMAC TCP
TCP Data
Mobile Node(MN)
Base Station(BS)
TCP
o Access TCP header
o Get IP addr, port, etc.
o Generate TCP ACK & store
o Compute TCP ACK identification index
GenerateTCP ACK
TCP ACKIndex
TCP Data
TCP ACK
TCP ACKIndex
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 22
ARQ Proxy - Benefits
Performance and System Capacity Increase
LL-ACK
TCP Data
Mobile Node(MN)
Base Station(BS)
Channel Contention
Channel Contention
LL-ACKTCP ACK
WiFi (IEEE 802.11)IP Network
TCP DataPHYHeaders
LLHeaders
TCP ACKPHYHeaders
LLHeaders
Overhead Overhead reductionreduction
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 23
Evaluation Results
Throughput performance
0 300 600 900 1200 15000
1
2
3
4
5
6
TCP/IP datagram size (Bytes)
Th
rou
gh
pu
t (M
b/s
)
ARQ proxy ONARQ proxy OFF
Improvement: 20%
Improvement:up to 100%
VoIP and MultimediaApplications
TCP file transfer, Ethernet MTU
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 24
Evaluation Results
Round Trip Time (RTT) improvement
0 10 20 30 40 500
10
20
30
40
50
60
Simulation time (seconds)
Sm
oo
th R
TT
(m
sec)
ARQ proxy OFF
ARQ proxy ON
Order of millisecond
s
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 25
Evaluation Results
High error rate tolerance
0 0.05 0.1 0.15 0.2 0.25 0.3 0.350
1
2
3
4
5
6
7
Packet Error Rate (PER)
Th
rou
gh
pu
t (M
b/s
)
ARQ proxy ONARQ proxy OFF
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008
RoofNet - Main Features: Wireless Mesh Networking SW developed by MIT
(based on Click Modular Router architecture) Multi-hop transmission Optimized routing using a specific metric
Limitations: Need for WiFi cards with Atheros chipset Madwifi driver
Goal: To port RoofNet to any hw/sw platform
Testbed Development
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008
RoofNet - Why dedicated HW? Probe transmission for link quality measurements in
broadcast mode at arbitrary rate BSSID partitioning Routing metric is calculated by ETT
ETT = ETX * S/B
(S=data size, B=used bandwidth)
Problem: IEEE 802.11 does not enable arbitrary rate in
broadcast signalling
Testbed Development
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008
Change from monitor mode to ad-hoc mode (supported by any IEEE 802.11 NIC)
Introduction of an element for static setting of preamble parameters
link-quality evaluation using ETX
flags = 0;
power = 60;
rssi = 8;
rate = 2;
retries = 0;
“BlankDecap” module settings
Roofnet Modifications
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 30
Service differentiation in Wi-Fi based Wireless Mesh NetworksSystem architectureSystem architecture Layer 2.5: interposition layer
with own headers ToS byte-based IP packet
classification Four classes with dedicated
buffering Transmissions scheduled by
a modifiedmodified Weighted Weighted Round Robin schemeRound Robin scheme
Software architectureSoftware architecture Click modular router Roofnet WMN features Elements added as C++
code
from Network Layer
to MAC layer
Layer 2.5
Routing probes
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 31
Experimental validation: results
1 hop1 hop 2 hops2 hops
UDP noise (diff)
UDP noise (no diff)
TCP hi-priority (no diff)
TCP hi-priority (diff)
Data-set C hi-priority TCP flow in class 4 UDP noise in class 1 at increasing bitrates
Figure 1: TCP resistance to UDP noise comparison (1 hop)
Figure 2: TCP resistance to UDP noise comparison (2 hops)
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 32
Experimental validation: results
Issues:Issues:1. Traffic generator issue:
TCP ACKS with ToS not set differentiation only on the feed-forward and
not on the feed-back ACKS scheduled with the lowest priority
2. Differentiation at Layer 2.5: Hi priority flows may lose MAC contentions
with low priority flows
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 34
AP3
AP4AP6
AP5
AP2
AP1
Control
Data
WOMEN Testbed Implementation
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 35
AP5
AP4
AP2
AP1
AP3
X
XX
XX
WOMEN Testbed Implementation
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 38
Dissemination activities - Project 11th Intenational Workshop on Computer-Aided
Modeling, Analysis and Design of Communication Links and Networks (CAMAD 2006, Trento, June 8-9, 2006)WOMEN leaflet CAMAD’06 website, dinner ticket Contribution to organization
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 39
Dissemination activities - Papers D. Kliazovich, F. Granelli, G. Pau, and M. Gerla
"APOHN: Subnetwork Layering to Improve TCP Performance over Heterogeneous Paths,“IEEE Next Generation Internet Design and Engineering (NGI), Valencia, Spain, April 2006.
D. Kliazovich, F. Granelli, and D. Miorandi"TCP Westwood+ Enhancements for High-Speed Long-Distance Networks,“IEEE International Conference on Communications (ICC'06), Istanbul, Turkey, June 2006.
F. Granelli, M. Devetsikiotis“Designing Cross-Layering Solutions for Wireless Networks: a General Framework and Its Application to a Voice-over-WiFi Scenario,”CAMAD 2006, June 8-9, 2006, pp. 1-7.
C.E. Costa, F. Granelli,"Optimal power control for embedded packet video transmission over WiFi“,1st Workshop on multiMedia Applications over Wireless Networks (MediaWIN 2006), Athens, Greece, April 2nd, 2006.
“WOMEN” Project Final MeetingTrento, Feb. 12th, 2008 40
Dissemination activities - Papers E. Miorando, and F. Granelli
"On Connectivity and Capacity of Wireless Mesh Networks,“IEEE International Conference on Communications (ICC’07), Glasgow, Scotland.
D. Kliazovich, N. Ben Halima, F. Granelli,"Cross-layer error recovery optimization in WiFi networks“,2007 Tyrrhenian International Workshop on Digital Communications (TIWDC 2007), Island of Ischia, Italy, Sept. 9-12, 2007.
R. Riggio, N. Scalabrino, D. Miorandi, F. Granelli, Y. Fang, E. Gregori, I. Chlamtac,"Hardware and Software Solutions for Wireless Mesh Networks Testbeds“submitted to IEEE Communications Magazine (minor revision requested).
D. Kliazovich, F. Granelli, D. Miorandi,"Logarithmic Window Increase for TCP Westwood+ for Improvement in High Speed, Long Distance Networks“,submitted to Computer Networks Journal (minor revision requested).