cnc_ppt

An Adaptive Call Admission Control in WiMAX Networks with Fair

Tradeoff Analysis

R.K. MANGANG

OUTLINE

Introduction IEEE 802.16 and WiMAXCall Admission Control(CAC)Adaptive Bandwidth Degradation CAC (ABD-CAC)Trade off analysisConclusion

INTRODUCTIONBackground and Motivation

Broadband Wireless Access(BWA)Promising solution for last mile accessHigh speed internet access in residential as well as small

and medium sized enterprise sectorFill the gap between high data rate wireless LAN and very

mobile cellular networks. Advantages of BWA Ease of deployment and installation Capacity can be increased by installing more base stations Challenges for BWA Price Performance Interoperability issues IEEE 802.16 standard is the first industry based standard for BWA

IEEE 802.16 Overview • Family of standards for wireless metropolitan area

networks (WMAN)• Provide broadband (i.e., voice, data, video) connectivity• Specifies the air interface, including the medium access

control (MAC) layer and multiple physical layer specifications

• promises to provide different kinds of services with guaranteed QoS.

Evolution of IEEE 802.16 Standards

802.16 802.16a 802.16-2004(Fixed WiMAX)

802.16e-2005(Mobile WiMAX)

Date Completed

December 2001

January 2003

June 2004 December 2005

Spectrum 10-66 GHz < 11 GHz < 11 GHz < 6 GHz

Operation LOS Non-LOS Non-LOS Non-LOS and Mobile

Bit Rate 32-134 Mbps

Up to 75 Mbps

Up to 75 Mbps

Up to 35 Mbps

Cell Radius 1-3 miles 3-5 miles 3-5 miles 1-3 miles

Service Flows supported in WiMAX

Service Flow Designation Defining QoS Parameters Application Examples

Unsolicited Grant Service (UGS)Maximum Sustained Rate(MSR)Maximum Latency ToleranceJitter Tolerance

Voice over IP (VoIP) without silence supression

Extended Real-time Polling Service (ertPS)

(included in IEEE 802.16e)

Minimum Reserved Rate (MRR)Maximum Sustained Rate(MSR)Maximum Latency ToleranceJitter ToleranceTraffic Priority

VoIP with silence suppression

Real-time Polling Service (rtPS)

Minimum Reserved Rate(MRR)Maximum Sustained Rate(MSR)Maximum Latency ToleranceJitter Tolerance

Streaming audio and video, MPEG (Motion Picture Expert Group) encoded

Non Real-time Polling Service (nrtPS)

Minimum Reserved Rate (MRR)Maximum Sustained Rate MSR)

File Transfer Protocol (FTP)

Best Effort Service (BE)Maximum Sustained Rate(MSR) Web browsing, data transfer

Basics of Call Admission Control (CAC) WHAT IS CAC ? A QoS mechanism that decides whether a new session

(connection) can be established. WHY CAC ? This mechanism will ensure that existing sessions’ QoS will not be degraded and the new session will be provided QoS support. HOW ?A connection is admitted if

There is enough bandwidth to accommodate the new connection The new admitted connection will receive QoS guarantees QoS of existing connections is maintained.

CAC ALGORITHMS

I. Reservation Based CAC

II. Non-Reservation Based CAC

No Bandwidth Degradation

Bandwidth Degradation

Adaptive Bandwidth Degradation-CAC Scheme [6]

Features Non-Reservation Based CAC Modified from FBD-CAC[5]

Bandwidth guarantee to all the connections Delay guarantee to rtPS connections Excellent Bandwidth Utilization

Fixed Bandwidth Degradation-CAC (FBD-CAC)[19]

In this scheme the bandwidth of lower priority connections are degraded to accommodate more connections.

The degradation is done in steps with an initially assigned step size (delta). Degradation is performed on rtPS and nrtPS connections to allow more

handoff calls. To allow more new UGS connections the degraded bandwidth from nrtPS

connections is also allocated to UGS connections.

Example :-Let B= 10240 kbpsBUGS= 256 kbps

BRTPSMAX = 1024 kbps; BRTPSMIN=512 kbpsBNRTPSMAX= 1024 kbps; BNRTPSMIN=512 kbpsLet at any instant the numbers calls admitted in the system as

given below :-Nu=8; Nr=3; Nn=5Total used bandwidth=Nu*BUGS+Nr*BRTPSMAX+Nn*BNRTPSMAX =10240 kbps.

• When a new UGS call arrives degradation will be performed on nrtPS connections• After degradation the Bandwidth available for nrtPS connection is given by

Bn=BNRTPSMAX-delta Let delta=256 kbps

Therefore Bn =768 kbps.NowTotal used bandwidth=(Nu+1)*BUGS+Nr*BRTPSMAX+Nn*Bn =9216 kbpsTotal bandwidth degraded = Nn*delta =5*256 =1280 kbps.

Disadvantage of FBD-CAC Scheme

Degradation more than necessaryStep size initially assigned arbitrarilyAvailable bandwidth for rtPS and nrtPS

connections are lessComputation time is longer because of the

degradation loopBandwidth utilization of the system is greatly

affected.

Adaptive Bandwidth Degradation(ABD)-CAC scheme

No fixed step size degradation.No need to assigned initial step size.Instead calculate the minimum required

bandwidth and then degrade.The degradation is adaptive to the required

bandwidth.

Example :- When a new UGS connection arrives degradation is performed to obtain the minimum required bandwidth as follows:

delta= [{(Nu+1)*BUGS+Nr*BRTPSMAX+Nn*BRTPSMAX} – B]/Nn =51.2 kbps.Available bandwidth of nrtPS connections = BNRTPSMAX-delta =1024-51.2 = 972.8 kbps Total bandwidth degraded = 5*51.2 = 256 kbps.Now,Total used bandwidth=(Nu+1)*BUGS+Nr*BRTPSMAX+Nn*Bn =10240 kbps.

Simulation Setup

Simulation was performed in MATLAB environment. The parameters taken for the simulation are:

B=10240 kbps. f=1 ms

TRAFFIC LOAD CONFIGURATION

g is defined as service request parameter

Simulation results

Fig. 1: Comparison NCBP and HCDP of UGS Connections Fig 2: Comparison NCBP and HCDP of rtPS Connections

Fig 3: Comparison NCBP and HCDP of nrtPS Connections Fig 4: Comparison of Bandwidth Utilization

Simulation results

Average Bandwidth Allocated to different services

TRADE OFF ANALYSIS

Design a tradeoff between HCDP and NCBPWHY?Giving more priorities to hand off calls

deprived the new incoming new calls from its own cell.

NCBP may be beyond an acceptable limit

APPROACH Define Two metrics1. Grade of Service (GoS)GoSk=NCBPk+bk.HCDPk, k ε {u, r, n} Where u, r, n denotes UGS, rtPS and nrtPS connections

respectively.bk= penalty weight for handoff calls relative to new calls >>1** Small GoS means better performance2. Cost function (CF) CF=w1*GoSu+w2*GoSr+w3*GoSn

Where w1+w2+w3=1 and different w1, w2 and w3 means different priority of the services. Therefore the weights are selected such that w1>w2>w3.

Define a Degradation threshold variable Bth which is optimized according to the minimum cost function.

Basic Steps

• For a particular arrival rate vary Bth in the interval 0 < Bth < Bmin

• For every value of Bth Calculate CF.

• The value Bth that gives the smallest CF is the optimal value of Bth for that arrival rate.

Simulation results

Fig 5 : Comparison of NCBP of UGS connections Fig 6 : Comparison of NCBP of rtPS connections

Fig 7 : Comparison of NCBP of nrtPS connections Fig 8 : Comparison of HCDP of UGS connections

Simulation results

Fig 9 : Comparison of HCDP of rtPS connections Fig 10 : Comparison of HCDP of nrtPS connections

Simulation results

Fig 11: The Optimal value of degradation variable Bth

Simulation results

CONCLUSIONAdaptive Bandwidth Degradation-CAC is further

extended to achieve fairness among new calls and handoff calls.

The proposed scheme has shown improvement in NCBP without affecting the HCDP.

The bandwidth utilization remains unaffected as obtained in ABD-CAC.

Tuning of the parameters used in tradeoff analysis is required which may be done using robust optimization techniques.

REFERENCE1. IEEE Standard: Air Interface for Fixed Broadband Wireless Access System. IEEE STD 802.16 – 2004,

October, 2004.2. IEEE Standard: Air Interface for Fixed and Mobile Broadband Wireless Access System. IEEE

P802.16e/D12, February, 2005.3. Fen Hou, Pin-Han Ho, and Xuemin (Sherman) Shen: Performance Analysis of Reservation Based

Connection Admission Scheme in IEEE 802.16 Networks. Global Telecommunications Conference, GLOBECOM’06, November 2006, pp. 1-5.

4. Xiang Chen, Bin Li, and Yuguang Fang: A Dynamic Multiple-Threshold Bandwidth Reservation (DMTBR) Scheme for QoS Provisioning in Multimedia Wireless Networks. IEEE Trans. on Wireless Communications, vol. 4, no. 2, pp. 583-592, March 2005.

5. Kalikivayi Suresh, Iti Saha Misra and Kalpana Saha (Roy): Bandwidth and Delay Guaranteed Connection Admission Control Scheme for QoS Provisioning in IEEE 802.16e Mobile WiMAX. proc. IEEE GLOBECOM 2008.

6. Romesh Laishram, Iti Saha Misra: A Bandwidth Efficient Adaptive Call Admission Control Scheme for QoS Provisioning in IEEE 802.16e Mobile Networks.Int J Wireless Inf Networks, vol.18 no.2: 108-116 (2011)

7. D. S. Shu'aibu, S. K. Syed Yusof, N. Fisal et al: Fuzzy Logic Partition-Based Call Admission Control for Mobile WiMAX. ISRN Communications and Networking, vol. 2011, Article ID 171760, 2011.

8. Sabari Ganesh.J, Bhuvaneswari P.T.V.: Enhanced Call Admission Control for WiMAX Networks. IEEE-International Conference on Recent Trends in Information Technology, ICRTIT 2011, Chennai. June 3-5, 2011, pp 33-36.

9. Wan Kim and Hwang Jun S.: QoS-aware joint working packet scheduling and call admission control for video streaming service over WiMAX network. Wirel. Netw. 17, 4 (May 2011), 1083-1094.

10. Shengdong Xie, Meng Wu: Optimized Call Admission Control in Wireless Networks. proc. International Conference on Advanced Infocomm Technology 2008.