QoS Support in Ad Hoc Networks

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QoS Support in Ad Hoc Networks

• Mario Gerla
• UCLA, Computer Science Dept

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QoS Support in the Ad Hoc Backbone Network

• Quality of service is critical in the WHYNET
  testbed
• Various multimedia applications ( VoIP, video
  streaming etc.)
• Different Priorities for different data flows
• Challenges in emerging ad hoc networks
• Heterogeneity Different radio and access
  technologies and handoffs due to mobility
• Scalability Network size is usually large from
  hundreds to thousands
• Reliability Must avoid single point failures
• Variety of users and applications

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QoS Support in the Ad Hoc Network

• QoS support in the ad hoc net requires the
  cooperation of physical, MAC and network layers
• Wireless ad hoc net QoS protocol design much more
  challenging than in wired nets
• the virtual circuit is volatile (difficult to
  commit resources)
• scheduling (eg weighted fair queueing) of
  distributed queues is complex
• avail bandwidth advertising (as per Q-OSPF in
  wired nets), CAC and bandwidth allocation not
  easy when resources dynamically change

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Proposed 2-tier Architecture
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Proposed QoS Solution

• Heterogeneous network is usually organized as
  multiple groups / swarms
• Each swarm has a common function and task (e.g.
  video scouting )
• A swarm leader (SL) is elected in each swarm
• QoS architecture consists of Intra-Swarm QoS and
  Inter-Swarm QoS
• LANMAR routing and mobile backbone network (MBN)
  are adopted to improve scalability

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Intra-Swarm QoS Scheme

• Swarm Leader (SL) schedules all flows within its
  swarm
• SL in charge of CAC (Call Acceptance Control) and
  precedence/priority policy
• At any time, only one flow can transmit
  Scheduling is token based
• Token is broadcasted, data packets can be both
  unicast or broadcast
• Advantages
• Priority to real time traffic over best effort is
  guaranteed
• Service quality within a swarm is guaranteed
• Robust to mobility and Leader failure
• Broadcast efficient within swarm

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Performance of Intra-Swarm QoS Scheme

• Simulation Configurations
• Single swarm with 30 nodes in a 1000mX1000m field
• Intra-Swarm QoS scheme Token based scheduling
• Routing protocol LANMAR routing (equal to
  Fisheye)
• Swarm internal mobility random waypoint mobility
• IEEE 802.11 Radio
• Channel rate 2Mbps, 5.5Mbps, 11Mbps
• QoS traffic CBR/UDP flows with packet size 1024
  bytes and flow rate as 32Kbps, 64Kbps, 96Kbps,
  128Kbps, 160Kbps

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Performance of Intra-Swarm QoS Scheme

• Call Acceptance Control vs. Flow Rate

of Admitted Flows
Rate of the QoS flow (bps)
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Performance of Intra-Swarm QoS Scheme

• Data Packet Delivery Ratio vs. Node Mobility
• Traffic 10 CBR/UDP flows with rate 100Kbps

Packet Delivery Ratio
Mobility Speed (m/s)
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Performance of Intra-Swarm QoS Scheme

• Data Packet Delay vs. Node Mobility
• Traffic 10 CBR/UDP flows with rate as 100Kbps

Packet Delay (ms)
Mobility Speed (m/s)
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Inter-Swarm QoS Scheme

• LANMAR routing is QoS extended to support
  scalable QoS service
• Available bandwidth estimate to destinations at
  each swarm leader
• Available bandwidth information piggybacked on
  the landmark distance vectors
• Call Acceptance Control (CAC)
• If destination is within the swarm, local CAC
  exercised by SL
• If destination is in other swarms, consult
  landmark routing table
• Other routing schemes such as QoS-AODV, QoS-OLSR
  can be used for inter-swarm when network size is
  small

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QoS Support in the Ad Hoc Backbone Network
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QoS Backbone efficiency

• Packet Delivery Ratio vs. Network Size

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QoS Backbone efficiency (cont)

• Average Packet Delay vs. Network Size

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Progress So Far

• Extended the LANMAR routing and AODV routing to
  support QoS flows
• Extended mobile backbone network to enhance QoS
• Implemented intra-swarm scheduling scheme
• Simulation investigation of the QoS extended
  LANMAR and AODV and MBN
• Preliminary performance investigation
• The QoS schemes improve performance of QoS flows
• Mobile backbone network is important to large
  scale networks
• QoS enabled mobile backbone network achieves both
  scalability and good network performance

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Future Work

• QoS models and schemes
• Incorporation with QoS MAC such as IEEE 802.11e
• DiffServ in ad hoc networks for supporting
  differentiated services
• Explore other QoS routing protocols such as QoS
  OLSR and FSR
• Building small Linux testbed to be integrated
  into the WHYNET testbed system