experimental evaluation of reverse direction transmissions in wlan using the warp platform
TRANSCRIPT
IEEE ICC 2015, 8–12 June, London, UK
Raul Palaciosa, Francesco Francha, Francisco Vazquez-Gallegob, Jesus Alonso-Zarateb, and Fabrizio Granellia
aDISI, University of Trento, Italy
bCTTC, Barcelona, Spain
Experimental Evaluation of Reverse Direction Transmissions in WLAN Using the
WARP Platform
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Outline
Scope
• Wi-Fi Footprint• IEEE 802.11 MAC Layer
• Energy Issues• Weaknesses of Theoretical Analyses and Simulations
Contribution
• BidMAC: Reactive Reverse Direction TXs
• Implementing BidMAC on WARPv3
• Experiments
Outcome
• Energy Efficiency
• Net/AP/STAs• Vs. Traffic Load
• Vs. Data packet Length
• Vs. PHY Data Rate
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Residential
Public
Enterprise
WLAN AP(Wi-Fi) User Wi-Fi-enabled
devices
The Big Picture
Source: Wireless Broadband Alliance (WBA), Informa, Nov. 2011
• Wide deployment of Wi-Fi hotspots worldwide.
• Increasing diversity of Wi-Fi-enabled devices.
3.300.000 Public Hotspots Worldwide in 2013
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Wi-Fi Footprint
• The number of Wi-Fi public hotspots will increase by 350% from 2011 to 2015.
• Wi-Fi home and hotspots will contribute by 31%-34% to the overall yearly cloud energy consumption, being the second main contributor after mobile networks.
Source: The Power of Wireless Cloud, Alcatel-Lucent’s Bell Labs, Centre for Energy-Efficient Telecommunications (CEET), University of Melbourne, Apr.
2013
Source: Wireless Broadband Access (WBA), Informa, Nov. 2011
1%
1%
2009 2010 2011 2012 2013 2014 2015
0.5 0.81.3
2.13.3
4.55.8
350%
Number of Wi-Fi Public Hotspots in the World (in million), 2009-2015
Metro & Core Networks
Data centers
Local (Wi-Fi Home/Wi-Fi Hotspots)
Mobile access networks (4G LTE)
2012 2015 Lo 2015 Hi
9173
32424
42957
57%55%
59%16%26%
1%
34%
31%10%
9%
Total Annual Wireless Cloud Energy Consumption (GWh), 2012-2015
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Nokia N95 Energy Consumption
• Downloading data using the WLAN radio interface consumes more energy that what is consumed by the CPU or the display in a Nokia N95 smart phone.
N95 8GB
Downloading data using HSDPADownloading datausing WLANSending an SMS
Making a voice call
Playing an MP3 file
Display backlightN
orm
alis
ed
ene
rgy
co
nsu
mp
tion (
%)
100
90
80
70
60
50
40
30
20
10
0
Source: Nokia Research Centre, 2012
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Energy Efficiency via the MAC Layer
MAC
PHY
NET
ChannelStatus
Transmission Control
Reliabledata
Routinginformation
Takes decisions on the usage of the wireless
interface to regulate the access to the channel
Best place for energy consumption control and
energy saving through cross-layer methods
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DCF Example (With RTS/CTS)
STA1
AP
Other STAs
RTS
CTS
DATA
ACK
TDIFS TDIFSTSIFS TSIFS TSIFS
T0
CTS
TSIFS TSIFS TSIFS
Time +
ACK
Time +
Time +
NAV RTS
RTS DATA
NAV CTSNAV DATA
NAV RTSNAV CTSNAV DATA
PiPt Pr
PtPr
T1
PiPr
Pi
TDIFSTBO TRTS TDATA TCTS TACKTCTS TACK TRTS TDATATBO
DIFS SIFS SIFS SIFS DIFS SIFS SIFS SIFS DIFS
RTS/CTS exchange RTS/CTS exchange
AP: Access PointSTA: Wireless StationDIFS: DCF Interframe SpaceSIFS: Short Interframe
SpaceRTS: Request-To-SendCTS: Clear-To-SendACK: AcknowledgmentNAV: Network Allocation
VectorBO: Slotted Backoff Time
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DCF Energy Inefficiencies
Control packet overhead
Silent and backoff periods
Idle listening and overhearing
Collisions of control and data packets
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IEEE 802.11n RDP
RDP
Allocate unused
TXOP time
To one or more
receivers
Reverse direction transfer
Good for bidirectional
traffic
Reduce channel
contention
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Proactive RD Protocols [1],[2]
• RD transfer initiated by the transmitter
• Grant remaining TXOP duration
• Based on 802.11n RDP operation
Types of RD-based Protocols
Reactive RD Protocols [3]-[6]
• RD transfer initiated by the receiver
• Reserve extended TXOP duration
• More adaptive to receiver needs
[1] M. Ozdemir, G. Daqing, A. B. McDonald, and J. Zhang, “Enhancing MAC Performance with a Reverse Direction Protocol for High-Capacity Wireless LANs,” in IEEE VTC 2006, Sep. 2006, pp. 1–5.
[2] D.Akhmetov,“802.11n: Performance Results of Reverse Direction Data Flow,” in IEEE PIMRC 2006, Sep. 2006, pp. 1–3.
[3] H. Wu, Y. Peng, K. Long, S. Cheng, and J. Ma, “Performance of Reliable Transport Protocol over IEEE 802.11 Wireless LAN: Analysis and Enhancement,” in IEEE INFOCOM 2002, vol. 2, Jun. 2002, pp. 599–607.
[4] D.-H. Kwon, W.-J. Kim, and Y.-J. Suh, “A Bidirectional Data Transfer Protocol for Capacity and Throughput Enhancements in Multi-rate Wireless LANs,” in IEEE VTC 2004, vol. 4, Sep. 2004, pp. 3055–3059.
[5] W. Choi, J. Han, B. J. Park, and J. Hong, “BCTMA (Bi-directional Cut- Through Medium Access) Protocol for 802.11-based Multi-hop Wireless Networks,” in ACM ISSADS 2005, Jan. 2005, pp. 377–387.
[6] N. S. P. Nandiraju, H. Gossain, D. Cavalcanti, K. R. Chowdhury, and D. P. Agrawal, “Achieving Fairness in Wireless LANs by Enhanced IEEE 802.11 DCF,” in IEEE WiMob 2006, Jun. 2006, pp. 132–139.
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BidMAC [7],[8]: A Reactive RD Protocol for Infrastructure WLANs
BidMAC
Receiver- initiated
bidirectional transmission
s
Transmit data after receiving
data
Backwards compatible with IEEE
802.11 DCF Balanced DL/UL
channel share
Improved WLAN
performance
[7] R. Palacios, F. Granelli, D. Gajic, and A. Foglar, “An Energy-Efficient MAC Protocol for Infrastructure WLAN Based on Modified PCF/DCF Access Schemes Using a Bidirectional Data Packet Exchange,” in IEEE CAMAD 2012, Sep. 2012, pp. 216–220.[8] R. Palacios, F. Granelli, D. Kliazovich, L. Alonso, and J. Alonso- Zarate, “Energy Efficiency of an Enhanced DCF Access Method Using Bidirectional Communications for Infrastructure-based IEEE 802.11 WLANs,” in IEEE CAMAD 2013, Sep. 2013, pp. 38–42.
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BidMAC Example (Without RTS/CTS)
AP: Access PointSTA: Wireless StationDIFS: DCF Interframe SpaceSIFS: Short Interframe
SpaceACK: AcknowledgmentNAV: Network Allocation VectorBO: Slotted Backoff Time
RD: Reverse Direction
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Motivations of The PaperA
naly
sis
No channel errors
No collisions
Infinite queues
Saturated conditions S
imu
lati
on No channel
errors
Infinite queues
Infinite retransmission
sNo underlying physical layer
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Anlys
Simul
Exp
Complete performance assessment
802.11g DCF
BidMAC
Contributions of The Paper
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MAC Prototyping Platforms
WARP• Wi-Fi compliant• Flexible• Open source
Platforms
TUTWLAN
WARP
CALRADIO
USRP
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WARPv3 and Its HW Features
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802.11g Reference Design for WARPv3
BidMAC is implemented here!
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Testbed Layout
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Energino Hardware Energino Software
Energino: An Energy Consumption Monitoring Toolkit
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Network Energy Efficiency Vs. Traffic Load
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Downlink Energy Efficiency Vs. Traffic Load
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Saturation Network Energy Efficiency Vs. Data Packet Length
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Summary
• Wi-Fi (IEEE 802.11 DCF MAC): Not energy efficient• IEEE 802.11n RDP(proactive, transmitter-initiated, RD-based
protocol): outperforms DCF but is not an optimal solutionProblem
• BidMAC: reactive (receiver-initiated) RD-based protocol (i.e., transmit after receive) for infrastructure WLANs
• More adaptive to the actual needs of a network than RDPSolution
• BidMAC implementation on an IEEE 802.11g WARPv3 platform• Experimental results of energy efficiency in a proof-of-concept
network formed by an AP and 2 STAsContribution
• Maximum energy efficiency gains of BidMAC versus DCF:• From 63% to 29% as the packet length grows• From 15% to 29% as the PHY data rate increases
Result
• Improve the current BidMAC implementation by incorporating packet aggregation and block ACK
• Evaluate the new implementation with different traffic classesFuture Work
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MAC/PHY System Parameters*
Parameter Value Parameter Value
SIFS, DIFS, EIFS 10, 28, 88 μs
ACK size 14 bytes
Slot time 9 μs MAC Header 24 bytes
Preamble 16 μs WARPv3 LLC Header 8 bytes
Signal 4 μs MSDU Size 50-1500 bytes
Signal Extension 6 μs Data Rate 6-54 Mbps
CWmin, CWmax 15, 1023 Control Rate 6,12,24 Mbps
Service 6 bits WARPv3 Power Consumption 18.95 W
Tail 16 bits Trial Time 30 s x10 times*IEEE 802.11g MAC/PHY
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Saturation Network Energy Efficiency Vs. PHY Data Rate
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Uplink Per Station Energy Efficiency Vs. Traffic Load