M'Tech Seminar

1
M.Tech Seminar

• Survey of Call Admission Control CAC in WiMAX,
  IEEE 802.16 Wireless MAN
• Presented by
• Jeevan B. Chalke (06329011)
• under the guidance of
• Prof. Anirudha Sahoo
• Kanwal Rekhi School of Information Technology
• Indian Institute of Technology

2
Outline

• Introduction
• QoS Architecture
• Call Admission Control
• Bandwidth based
• An efficient CAC for IEEE 802.16 networks
• Token Bucket based
• CAC for real-time video application
• Scheduling
• Uplink packet scheduling
• Scheduling for real-time video application

3
Introduction

• IEEE 802.16 Broadband Wireless Access Networks
• Include P2P, P2MP and mesh access networks
• Provides fixed-wireless access between SS and ISP
  through BS
• Defines the air interface Uplink and Downlink
• Advantages
• Rapid deployment
• High scalability
• Low maintenance
• 2-11GHz Non LOS and 10-66 GHz LOS

4
Broadband Wireless Access
5
Frame Format

• DL-MAP and UL-MAP indicate the resource
  arrangement

6
Services

• Modes of granting bandwidth request by SS
• Grant Per Connection (GPC)
• Grant Per Subscriber Station (GPSS)
• Services
• Unsolicited Grant Service (UGS)
• Fixed size data packets
• E.g. VoIP
• Real Time Polling Service (rtPS)
• Variable size data packets
• E.g. MPEG
• Non-Real Time Polling Service (nrtPS)
• Variable sized data packets
• E.g. FTP
• Best Effort (BE)
• Do not require any minimum transmission rate
• E.g. Web traffic, HTTP

7
Outline

• Introduction
• QoS Architecture
• Call Admission Control
• Bandwidth based
• An efficient CAC for IEEE 802.16 networks
• Token Bucket based
• CAC for real-time video application
• Scheduling
• Uplink packet scheduling
• Scheduling for real-time video application

8
QoS Architecture
Fig. 3 Architecture to provide QoS in IEEE
802.16 standards 11
9
Outline

• Introduction
• QoS Architecture
• Call Admission Control
• Bandwidth based
• An efficient CAC for IEEE 802.16 networks
• Token Bucket based
• CAC for real-time video application
• Scheduling
• Uplink packet scheduling
• Scheduling for real-time video application

10
Motivation

• An important part of IEEE 802.16 networks
• Admits or rejects a new flow to ensure QoS
  guarantees
• No architecture defined in IEEE 802.16 standards
• Left to developer
• Different CACs
• Bandwidth based
• An efficient CAC for IEEE 802.16 networks
• Token Bucket based
• CAC for real-time video application

11
Bandwidth Based CAC

• Admits flows as long as there is enough bandwidth
  
• Simple
• Does not consider the deadline constraints
• Dynamic Admission Control 15
• Provides some QoS guarantee in terms of bandwidth
  fairness
• Different bandwidth for different services

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An Efficient CAC for IEEE 802.16 Networks

• Provides bandwidth guarantees
• Provides QoS guarantees (such as Delay) to
  connection as per their service types
• Here we see
• Architecture
• Base station architecture
• Subscriber station architecture
• QoS-CAC Algorithm

13
Base Station Architecture

• Uses GPC mode
• Application must establish a connection with a
  base station
• Admission Control checks for QoS guarantees and
  accepts or rejects the flow
• Scheduler looks priority and decides on the slot
  allocation
• Periodic Grant Generator ensures the allocation
• Map Generator generates UL-MAP message

Fig. 4 Base station architecture 10
14
Subscriber Station Architecture

• Connection classifier classifies applications
  into various service class types
• FCFS within queue
• Application informs the SS about its traffic
  chara. and then SS informs BS
• BEA estimates the bandwidth and make the
  appropriate BW request for the connection.
• Request generator then generates the appropriate
  request and feeds it to the scheduler

Fig. 5 Subscriber station architecture 10
15
QoS-CAC Algorithm

• Provides delay guarantees
• Considers following parameters
• Nominal grant/polling interval
• Tolerated jitter,
• Maximum and minimum rate
• Traffic priority
• Hiper Interval
• Testing admisssibility
• QoS guarantee at every periodic interval
• If requested slots lt total slots that can
  actually be accommodated, accept else reject
• E.g. for rtPS flow,

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Token Bucket Based CAC

• Mechanism of controlling network traffic rate
• Works well for bursty traffic
• Ensures bandwidth and delay guarantees
• Bandwidth is calculated by

Where, d is max delay, f is frame length, r is
token rate, b bucket size
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CAC for Real-Time Video Application

• Indeterminate time-varying bit rate and delay
• Renders periodicity and regularity in frame
  sequence
• Identified by I, P and B frames according to its
  Group of Picture (GOP) structure
• Introduces Access Pendency
• Finds the earliest proper time within its pending
  period to establish a connection
• Else rejects the flow
• An Example

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Access Pendency
Fig. 6 Two real time video flows, and their
aggregation without/with pendency 6
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CAC for Real-Time Video Application (contd)

• Coordination with I-frames
• Determines any superposition of I-frames and
  examines if it overloads the channel,
• Avoids heavily aggregated I-frames going beyond
  the capacity of a channel
• Connection will be rejected if the I-frames of
  the two connections get too close with each
  other.

20
Outline

• Introduction
• QoS Architecture
• Call Admission Control
• Bandwidth based
• An efficient CAC for IEEE 802.16 networks
• Token Bucket based
• CAC for real-time video application
• Scheduling
• Uplink packet scheduling
• Scheduling for real-time video application

21
Motivation

• Another important part of IEEE 802.16 networks
• No architecture defined in IEEE 802.16 standards
• Significant impact on system performance and
  end-to-end QoS
• Shares uplink flow effectively
• Scheduling schemes
• Uplink Packet Scheduling
• Scheduling for Real-time Video Application

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Uplink Packet Scheduling

• Uses different scheduling algo. for different
  services
• For UGS Fixed bandwidth
• For rtPS EDF (Earliest Deadline First)
• For nrtPS WFQ (Weighted Fair Queuing)
• For BE Equally distributed
• Consists of three modules
• Information module
• Retrieves information from the BW-Request
  messages
• Scheduling database module
• Serves as the information database
• Service assignment module
• Determines the UL-MAP

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Scheduling for Real-time Video Application

• Uses LST (Latest Starting Time)
• Distributes a packet ranging from the deadline
  column back to the column which corresponds to
  its LST, L columns,
• The first packet of each flow in the L column is
  selected to send (according to the flow's current
  delay performance)

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Scheduling for Real-time Video Application
(contd)

• The scheduler records
• tot, the amount of data which were transmitted
• err, the amount of data which missed their
  deadline
• Minimizes the unfairness

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Conclusion/Summary

• QoS Architecture
• Call Admission Control
• For providing QoS such as delay and fairness
  guarantees
• For real-time application
• Scheduling

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Critique
There are various areas in CAC research such as
estimating bandwidth allocation, bandwidth
borrowing and degradation, token bucket rate
estimation etc. In the future it might be
possible to develop an efficient CAC by combining
these areas together to provide the required and
necessary QoS guarantees.
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References

• 1 IEEE. IEEE Standard for Local and
  metropolitan area networks Part 16 Air Interface
  for Fixed Broadband Wireless Access Systems,
  IEEE standard, December 2001.
• 2 IEEE. IEEE Standard for Local and
  metropolitan area networks Part 16 Air Interface
  for Fixed Broadband Wireless Access Systems,
  IEEE standard, October 2004.
• 3 Carl Eklund, Roger B. Marks, Kenneth L.
  Stanwood and Stanley Wang. IEEE standard
  802.16 A technical overview of the wirelessMAN
  air interface for broadband wireless access,
  IEEE Communications Magazine, vol. 40, no. 6,
  June 2002.
• 4 IEEE 802.16 Working Group on Broadband
  Wireless Access Available http//wirelessman.org
  
• 5 Kitty W., Aura G. Packet scheduling for QoS
  support in IEEE 802.16 broadband wireless access
  systems, International Journal of Communication
  Systems, 2003 1681-96.
• 6 Ou Yang, Jianhua Lu. Call Admission Control
  and Scheduling Schemes with QoS Support for
  Real-time Video Applications in IEEE 802.16
  Networks, Journal of Multimedia, vol. 1, No. 2,
  May 2006.
• 7 Ou Yang, Jianhua Lu. A New Scheduling and
  CAC Scheme for Real-time Video Applications in
  Fixed Wireless Networks, Proceedings of IEEE
  CCNC 2006 303-307.
• 8 Georgiadis L, Guerin R, Parekh A. Optimal
  Multiplexing on a Single Link Delay and Buffer
  Requirements, Proceedings of IEEE INFOCOM 94
  vol. 2, 1994 524-532.

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References (contd)

• 9 Demers A, Keshav S, Shenker S. Analysis and
  Simulation of a Fair Queuing Algorithm, SIGCOMM
  CCR 19, 1989 4.
• 10 Chandra and A. Sahoo. An Efficient Call
  Admission Control for IEEE 802.16 Networks,
  Technical Report,
• Available http//www.it.iitb.ac.in/research/tech
  report/reports/30.pdf
• 11 Alavi H. S., Mojdeh M and Yazdani N. A
  Quality of Service Architecture for IEEE 802.16
  Standards, Communications, 2005 Asia-Pacific
  Conference, Oct 2005.
• 12 IEEE P802.16-REVd/D5-2004. Air Interface
  for Fixed Broadband Wireless Access Systems
• 13 Chi-Hong Jiang and Tzu-Chieh Tsai. Token
  Bucket Based CAC and Packet Scheduling for IEEE
  802.16 Broadband Wireless Access Networks,
  Proceedings of IEEE CCNC 2006 2006.
• 14 Tzu-Chieh Tsai, Chi-Hong Jiang and
  Chuang-Yin Wang. CAC and Packet Scheduling Using
  Token Bucket for IEEE 802.16 Networks,
  International Journal of Communication, vol. 1,
  No. 2, MAY 2006.
• 15 Wang H., Li W. and Agrawal D.P. Dynamic
  admission control and QoS for 802.16 wireless
  MAN, Wireless Telecommunications Symposium,
  2005, vol. no.pp. 60- 66, 6-7 April 2005.