Evaluation of 802.11a for Evaluation of 802.11a for Streaming Data in Ad- -hoc hoc Streaming Data in Ad Networks Networks Samip Bararia Bararia, , Shahram Shahram Ghandeharizadeh Ghandeharizadeh, Shyam , Shyam Kapadia Kapadia Samip Computer Science Department Computer Science Department University of Southern California University of Southern California Los Angeles 90089 Los Angeles 90089 bararia@usc.edu,shahram@usc.edu,kapadia@usc.edu bararia@usc.edu,shahram@usc.edu,kapadia@usc.edu
H20 Application class: An example deployment H20 Application class: An example deployment
H20 Application class: An example deployment H20 Application class: An example deployment H2O device roles: H2O device roles: Data producer (source), Data forwarder (router), Data consumer ( Data producer (source), Data forwarder (router), Data consumer (sink) sink)
Candidate wireless technologies Candidate wireless technologies Technology Frequency band Spec B/W Typical B/W Radio-range(indoor) Bluetooth 2.4Ghz 1Mbps 700Kbps 30 feet 802.11b 2.4-2.48Ghz 11Mbps 4-5Mbps 300 feet 802.11a 5.725-5.85Ghz 54Mbps 20-25Mbps 40 feet Note: Note: (1) (1) 802.11a 802.11a turbo provides bandwidths turbo provides bandwidths upto upto 75Mbps (raw) but not supported by all 75Mbps (raw) but not supported by all manufacturers (not a IEEE std) manufacturers (not a IEEE std) (2) (2) Bandwidth required for display of a DVD Bandwidth required for display of a DVD-quality (MPEG quality (MPEG-2) video clip is 4Mbps. 2) video clip is 4Mbps.
Hypothesis: IEEE 802.11a IEEE 802.11a Hypothesis: may be a feasible option for may be a feasible option for the H20 application class. the H20 application class.
Dimensions of the empirical study Dimensions of the empirical study Distance between participating devices Distance between participating devices � Number of intermediate H20 devices used to route a stream Number of intermediate H20 devices used to route a stream � from a producing H20 device to a consuming H20 device from a producing H20 device to a consuming H20 device Number of simultaneous senders in the same radio range Number of simultaneous senders in the same radio range � Operating system level versus application level routing Operating system level versus application level routing � Note: Used INTEL PRO/Wireless 5000 LAN Note: Used INTEL PRO/Wireless 5000 LAN Cardbus Cardbus adapter 802.11a cards at adapter 802.11a cards at 54Mbps ( 54Mbps (Auto data rate control disabled Auto data rate control disabled)
Terminology Terminology In general, any scenario is m transmissions k In general, any scenario is m transmissions k � � hops each hops each Denoted as m:k m:k, , m,k m,k>=1 >=1 Denoted as � � 1 foot 1 foot 1 foot 1 foot 1 foot 1 foot For e.g. For e.g. � � Movie Movie Movie Movie Movie Movie (a) 3:1 hop (a) 3:1 hop � � B A C transmission transmission Node 3 Node 3 Node 4 Node 4 Node 2 Node 2 Node 1 Node 1 (b) 1:3 hop (b) 1:3 hop � � Movie Movie Movie Movie Movie Movie transmission transmission D D D Node 3 Node 3 Node 4 Node 4 Node 1 Node 1 Node 2 Node 2
Terminology (contd contd) ) Terminology ( Data consumer Data consumer Data producer Data producer Data=1GB Data=1GB Data=1GB Data=1GB Application Application Application Application layer layer layer layer ADU ADU ADU ADU ADU ADU ADU ADU ADU ADU ADU ADU TCP/UDP TCP/UDP TCP/UDP TCP/UDP IEEE IEEE 802.11a 802.11a Note: ADU – – Application Data Unit Application Data Unit Note: ADU
TCP and UDP performance for a 1:3 hop connection TCP and UDP performance for a 1:3 hop connection Movie Movie Movie Movie Movie Movie D D D Node 3 Node 3 Node 4 Node 4 Node 1 Node 1 Node 2 Node 2 Bandwidth (Goodput Goodput) and loss rate for a 1:3 hop ) and loss rate for a 1:3 hop Bandwidth ( connection. connection.
Observations Observations UDP Loss rate between 15- -30% with a large 30% with a large UDP Loss rate between 15 � � variance variance Losses occur due to transient bottlenecks at Losses occur due to transient bottlenecks at � � intermediate routers intermediate routers k participants competing for the channel k participants competing for the channel � � Due to randomness intermediate router is Due to randomness intermediate router is � � flooded occasionally and drops data flooded occasionally and drops data TCP performs well even though there is the ACK TCP performs well even though there is the ACK � � overhead overhead A protocol with flow control and congestion A protocol with flow control and congestion � � control does well in case multiple senders in control does well in case multiple senders in the same radio range the same radio range System may produce data at a slower rate than System may produce data at a slower rate than � � available network bandwidth available network bandwidth Introduce a delay between successive ADUs Introduce a delay between successive ADUs � �
Terminology (contd contd) ) Terminology ( Data consumer Data consumer Data producer Data producer Data=1GB Data=1GB Data=1GB Data=1GB Application Application Application Application layer layer layer layer ADU ADU ADU ADU ADU ADU ADU ADU ADU ADU ADU ADU Wait- -time time Wait TCP/UDP TCP/UDP TCP/UDP TCP/UDP IEEE IEEE 802.11a 802.11a Note: ADU – – Application Data Unit Application Data Unit Note: ADU
Data Flow Control Data Flow Control Bandwidth and loss rate with UDP for a 1:3 hop connection with wait ait- - Bandwidth and loss rate with UDP for a 1:3 hop connection with w time. time.
Data Flow Control Data Flow Control 0ms wait 0ms wait-time: Time=961s time: Time=961s 1ms wait 1ms wait-time: Time=1106s time: Time=1106s Bandwidth and loss rate with UDP for a 1:3 hop connection with wait ait- - Bandwidth and loss rate with UDP for a 1:3 hop connection with w time. time.
TCP and UDP performance for TCP and UDP performance for 3:1 hop connection 3:1 hop connection 1 foot 1 foot 1 foot 1 foot 1 foot 1 foot Movie Movie Movie Movie Movie Movie A B C Node 3 Node 3 Node 4 Node 4 Node 1 Node 1 Node 2 Node 2
Observations Observations TCP and UDP bandwidth drops by 1/3 as compared to 1:1 TCP and UDP bandwidth drops by 1/3 as compared to 1:1 � 3 senders contending for the medium � 3 senders contending for the medium Loss rate for UDP is about 0.2% � Loss rate for UDP is about 0.2% Allocation of bandwidth is approximately fair Allocation of bandwidth is approximately fair �
d feet d feet Distance experiments Distance experiments Movie Movie A Node 1 Node 1 Node 2 Node 2 Carried out experiments with a 1:1 configuration at USC Carried out � track field, university housing (indoor experiments) and Marina-del-Rey beach
Exposed node limitation Exposed node limitation Related work has shown that exposed node[6] � degrades the performance of 802.11 severely Experimental setup � d feet d feet 10 feet 10 feet 10 feet 10 feet Stream Stream Stream Stream 1 2 Node 4 Node 4 Node 3 Node 3 Node 2 Node 2 Node 1 Node 1 1:1 1:1 1:1 1:1 Two pairs of nodes spaced d feet apart � 100 MB of data with ADU size of 1KB �
Results Results Session 1 Session 2 d (feet) Bandwidth Bandwidth 100 12.24468 12.99614 150 12.2803 12.5572 200 13.02289 13.65804 250 14.09932 14.01428 300 16.23252 14.04708 400 17.80064 16.95107 450 17.34653 17.06635 500 18.8331 17.79747 Results show that each stream observes a bandwidth of 12.2 – � 14.4 Mbps up to 250 feet.
Related work Related work [5] studies the feasibility of IEEE 802.11b as a viable candidate e [5] studies the feasibility of IEEE 802.11b as a viable candidat � for wireless ad hoc networks for wireless ad hoc networks TCP one- -hop unfairness problem hop unfairness problem TCP one � Simulation study verified with empirical deployment � Simulation study verified with empirical deployment 1:1 1:2 1:1 1:2
No Dropped connections No Dropped connections Experimental setup � 50 feet 50 feet 50 feet 50 feet 50 feet 50 feet 50 feet 50 feet Movie Movie Movie Movie Movie Movie A A B Node 1 Node 1 Node 4 Node 4 Node 3 Node 3 Node 2 Node 2 Node 5 Node 5 1:1 1:1 1:2 1:2 Even with the 1- � hop flow running on UDP, TCP does not drop connections. Allocation of � bandwidth is fair across UDP and TCP flows
Differences between IEEE 802.11a and Differences between IEEE 802.11a and IEEE 802.11b IEEE 802.11b IEEE 802.11a IEEE 802.11a � � Has 12 channels (compared to 3 for 802.11b) Has 12 channels (compared to 3 for 802.11b) � 8 for indoor and 4 for outdoor use � 8 for indoor and 4 for outdoor use Lower co- -channel interference channel interference � Lower co Allows for higher user densities and higher system Allows for higher user densities and higher system � � data throughput data throughput Higher bandwidth 54Mbps as compared to Higher bandwidth 54Mbps as compared to � � 11Mbps for 802.11b 11Mbps for 802.11b Higher system capacity � Higher system capacity
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