Centralized Resource Allocation for Multimedia Traffic in IEEE 802'16 Mesh Networks

1
Centralized Resource Allocation for Multimedia
Traffic in IEEE 802.16 Mesh Networks

• S. Xergias, N. Passas, and A.K. Salkintzis
• Proceeding of IEEE, 2008

2
Outline

• Introduction
• IEEE 802.16 Broadband Access Network
• Extended Frame Registry Tree Scheduler
• Simulation
• Conclusions

3
Introduction

• IEEE 802.16
• Metropolitan environment
• Point-to-multipoint mode
• Mesh mode
• Supports QoS
• Enhanced Frame Registry Tree Scheduler (E-FRTS)
• Avoid complex computation

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IEEE 802.16 Broadband Access System

• Physical layer
• 10-66 GHz and below 11 GHz
• Data rate between 32 to 130 Mbps
• Operation modes
• Point-to-Multipoint (PMP)
• Centralized and Distributed mesh
• Base station (BS for PMP, and MBS for mesh)
• SS
• MSS

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IEEE 802.16 Broadband Access System

• Time-division duplex (TDD)
• Frequency-division duplex (FDD)
• Time frame for TDD
• 0.5, 1 or 2 for PMP mode
• 2.5, 4, 5, 8, 10, 12.5, or 20 ms for mesh mode
• Coding and modulation may be adjusted
  individually for each SS on a frame-by-frame
  basis

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IEEE 802.16 Broadband Access System

• PMP mode
• DL-MAP and UL-MAP
• Mesh mode
• DL-MAP and UL-MAP are combined in one control
  message
• Mesh centralized scheduling (MSH-CSCH) for
  centralized mesh mode
• Mesh distributed scheduling (MSH-DSCH) for
  distributed mesh mode

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IEEE 802.16 Broadband Access System

• Data bit are randomized, forward error correction
  encoded, and mapped to one of the mandatory
• Spread binary phase-shift keying (BPSK)
• Quadrature phase-shift keying (QPSK)
• 16-quadrature amplitude modulation (QAM)
• 64-QAM
• 256-QAM (optional)

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IEEE 802.16 Broadband Access System

• Scheduling service and QoS in IEEE 802.16
• Unsolicited grant service (UGS)
• Real-time polling service (rtPS)
• Non-real-time polling service (nrtPS)
• Best effort service (BE)
• Enhanced rtPS (ertPS)

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Extend Frame Registry Tree Scheduler (E-FRTS)

• The traffic schedulers for TDD system
• Schedule complete before the beginning of each
  time frame
• Efficient traffic scheduling implies complex
  calculations
• More expensive hardware

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Extend Frame Registry Tree Scheduler (E-FRTS)

• The basic idea
• Schedule the transmission of each piece of data
  in the last time frame before its deadline
• The main objectives
• Each frame has its transmissions organized in
  modulation order from BPSK to 256-QAM
• A per QoS service treatment of the transmissions
  should be possible
• Data packets transmission should be based on
  their deadline
• Changes in network topology, node modulation, or
  QoS service should be possible with minimum
  processing effort

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Extend Frame Registry Tree Scheduler (E-FRTS)

• 1st level different neighborhood
• 2nd level time frames immediately following the
  present one, in a sequential order

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Extend Frame Registry Tree Scheduler (E-FRTS)

• 3rd level the direction (uplink or downlink)
• 4th level different sectors where the children
  SSs belong to
• 5th level the available modulation types
• 6th level connections are organized per SS
• 7th level the number of data packets scheduled
  for transmission in that time frame

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Extend Frame Registry Tree Scheduler (E-FRTS)

• The scheduler operation
• Packet/Request Arrival
• C(Pi) is the connection that packet Pi belongs to
  
• H(C(Pi)) is the number of hops to the destination
  of C(Pi)

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Extend Frame Registry Tree Scheduler (E-FRTS)
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Extend Frame Registry Tree Scheduler (E-FRTS)
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Extend Frame Registry Tree Scheduler (E-FRTS)

• Frame Creation
• Which is responsible for deciding on the contents
  and structure of the next time frame of all
  neighborhoods
• The number of packets under subtree TFi fits
  exactly into one time frame
• The number of packets under subtree TFi is less
  than the capacity of a time frame
• The number of packets under subtree TFi is more
  than the capacity of a time frame
• nrtPS and BE packets can be moved to the next
  time frame
• UGS, ertPS, and rtPS some of them should be
  rejected

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Simulations

• Multiple Traffic Types Scenario
• One UGS with constant data rate of 64 Kbps and
  latency equals to 20ms
• One rtPS with mean data rate 256Kbps and latency
  equals to 40ms
• One nrtPS with mean data rate of 128Kbps
• One BE with mean data rate of 128Kbps

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Simulations

• Time frame sets to 1ms and the packet size sets
  to 54 bytes
• The modulation is 64-QAM for SS
• The transmission speed of BS is 120Mbps
• The simple scheduler uses FIFS to serve the
  packets

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Packet losses per service type
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Mean delay per service type
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Throughput per service type
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Simulation

• Multicast Scenario
• One voice connection of type adaptive multi-rate
  (AMR)
• One real-time compressed video connection
• Half of the SSs belonged to multicast group
• Two multicast cases were tested

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The simulation example

• Unicast
• AMR voice
• ON-period
• 4.75, 10.2, and 12.2 Kbps
• OFF-period
• 1.95Kbps
• Latency is 30 ms
• Real-time video
• rtPS
• Min bit rate from 64 to 128 Kbps
• Max bit rate from 256 to 512 Kbps
• Latency is 40 ms

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Simulation

• Multicast
• rtPS
• Min bit rate from 1 to 2 Mbps
• Max bit rate from 2 to 4.5 Mbps
• Latency is 50 ms

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Simulation
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Simulation
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Conclusion

• A deadline-based logic are considered essential
  for supporting real-time traffic
• Reduce data fragmentation and physical overhead
  due to modulation changes
• QoS classification is attained by transmitting
  high-priority before low-priority
• Starting from low priority when packets have to
  be rejected
• The scheduler maintains low computational
  complexity by distributing the required
  processing in time
• Simulation results show that distributed
  multimedia traffic can be efficiently served with
  a reasonable number of hops