A Study of the Bandwidth Management Architecture over IEEE 802.16 WiMAX

A Study of the Bandwidth Management Architecture over IEEE 802.16 WiMAXStudent : Sih-Han Chen ( 陳思翰 )Advisor : Ho-Ting Wu ( 吳和庭 )Date : 2008.07.25

Background and MotivationProposed QoS System Architecture

Call Admission Control (CAC) Pairing CAC Bandwidth Borrowing on CAC level

Two Stage Bandwidth Allocation Performance EvaluationConclusion and Future Work

2008/07/25 Page 2

Outline

Fixed WiMAX (Worldwide Interoperability for Microwave Access) Specified by IEEE 802.16 d Wireless MAN Network High transmission rate and coverage (75Mbps ,50km) Support QoS Cost saving and easy to deploy Replace last mile (like ADSL)

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Background

2008/07/25 Page 4

MAC Common Part Sublayer

Defines multiple-access mechanism

Functions ： Connection establishment Connection maintenance Call admission control Bandwidth request Bandwidth allocation Packet scheduling

MAC Common Part Sublayer

(MAC CPS)

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IEEE 802.16 TDD Frame Structure

Frame n-1 Frame n Frame n+1

DL Subframe UL Subframe

Preamble FCH DL-Burst #1

DL-Burst #2-4

DL-Burst #5

DL-Burst #6

TTG

RTG

Initialranging

BWrequest

UL-Burst #1

UL-Burst #2

DLFP DL-MAP UL-MAP MAC messages, Mac PDUs

IEIE IE IE IE IE IE IE IE IE

Preamble FCH DL-Bursts#1-4 DL-Burst #5 DL-Burst #6 RangingOpportunity

BWrequest

UL-Burst #1

UL-Burst #2

Preamble(optional)

MACPDU

MACPDU

Pad Preamble(optional)

MACPDU

MACPDU

Midamble(optional)

MACPDU

MACPDU

Pad

These MAC PDUs which are in each UL-Bursthave to come from one SS

These MAC PDUs which are in each DL-Burst Will possibly be sent to different SS

IE IE

2008/07/25 Page 6

Service Classes

Feature ApplicationUGS(Unsolicited Grant Service)

•Real Time •Constant Bit Rate

•T1/E1•VoIP

rtPS(Real-Time Polling Service)

•Real Time•Variable Bite Rate

•MPEG video

nrtPS(Non-Real-Time Polling Service)

•Non-Real Time•Variable Bite Rate

•FTP

BE(Best Effort)

•Non-Real Time•No QoS guarantee

•HTTP•Email

2008/07/25 Page 7

Dynamic Service Establishment

SS-initiated：DSA message flow BS-initiated：DSA message flow

(a) (b)

SS

DSX-RVD

DSA-REQ

(Without SFID and CID)BS

DSA-RSP

DSA-ACK

SS

DSA-REQ

BS

DSA-ACK

DSA-RSP

(SFID and Transport CID)

(SFID and Transport CID)

IEEE 802.16 only defined the basic QoS signaling architecture.

The detail internal algorithm was left as the responsibility of implementers. Call admission control Bandwidth allocation Packet scheduling

Pairing connection property Uplink and downlink connections must coexist for

many network application. (e.g. VoIP, FTP, P2P…) 2008/07/25 Page 8

Motivation

Undefined!!!




2008/07/25 Page 9

Outline

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Proposed QoS Architecture

Two Stage Bandwidth Allocation

Cor

e N

etw

ork

ApplicationsPair Call Admission Control

BandwidthBorrowingAgent

Uplink Packet Scheduler

Downlink Data Traffic

Connection Request

Connection Response

UGS

rtPSnrtPSBE

UplinkData Traffic


UGSrtPS

nrtPSBE

Up Stream(Bandwidth Request)

BS SS

Downlink Packet SchedulerDown Stream(DL/UL MAP)

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Pairing Call Admission Control

Symbol Definition

Remaining Available System Bandwidth Resource

Reserved Bw for Connection, ( X = DL or UL )

Peak Traffic Rate of Connection Request, ( X = DL or UL)

Average Traffic Rate of Connection Request, ( X = DL or UL)

Min Traffic Rate of Connection Request, ( X = DL or UL)

availableB

X

PeakRateCrX

AvgRateCrX

MinRateCr

X

BwRsv

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Is UGS?

Each Pair Connection Request

X X

Bw PeakRateRsv Cr

2

X XX PeakRate AvgRateBw

Cr CrRsv

2

X XX AvgRate MinRateBw

Cr CrRsv

2

XX MinRateBw

CrRsv

Is rtPS?

Is nrtPS?

Is BE?

X

BwRsvBavailable >= Y

Y

Y

Y

N

N

N Enable BandwidthBorrowing ?

Y

Accept Pair Call

N

Reject Call

N

Y

Go Bandwidth Borrowing Agent

Pairing Call Admission Control

2008/07/25 Page 13

Range of Bandwidth Reservation

Service Type

Upper Bound ofReserved Bandwidth

Low Bound ofReserved Bandwidth

UGS

rtPS

nrtPS

BE

( )2

Peak rate + Avg rate

Peak rate Peak rate

Avg rate

( )2

Avg rate + Min rate Min rate

2Min rate 0

2008/07/25 Page 14

Bandwidth Borrowing on CAC Level

Symbol DefinitionThe current reserved bandwidth for connection i

The low bound of reserved bandwidth for connection i.Amount of bandwidth are needed to be borrowed from system.In system, How many bandwidth can be borrowed from rtPS, nrtPS and BE individually.(X = rtPS , nrtPS or BE )

i

currentRsv

borrowB_

i

low boundRsv

X

CreditB

2008/07/25 Page 15

Operation of Bandwidth Borrowing

Calculate the bandwidth that are needed to be borrowed from system

In system, the bandwidth can be borrowed from rtPS, nrtPS and BE individually

DL UL

borrow availableBw BwRsv RsvB R

_( )

X k kX

C r e d i t c u r r e n t low boundi k

NRsv RsvB

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Bandwidth Borrowing Flow Chart

Is UGS?

Pair Connection Request from CAC Module

Is rtPS?

Is nrtPS?

Is BE?Y

YN

N

Borrow from existing

BE Cons


nrtPS Cons


rtPS Cons

Reject

Reject

Failure FailureFailure

Accept

Success Success Success

Y

Y


BE Cons


nrtPS Cons


rtPS Cons

Reject

Failure FailureFailure

Success Success Success

Accept

2008/07/25 Page 17

Example of Bandwidth Borrowing (BB)BS SS

Existing Connections in SystemCID Type Reserved

BWLow Bound ofReserved Bw

Credit

1 BE 100 Kbps 50 Kbps 50 Kbps

2 nrtPS 150 Kbps 100 Kbps 50 Kbps3 rtPS 300 Kbps 150 Kbps 150 Kbps4 rtPS 200 Kbps 150 Kbps 50 Kbps

After Bandwidth Borrowing Operation

Pairing UGS DSATotal require 160Kbps(80x2)

Now System available Bw= 0Start to BB operations at BS.



Credit


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Credit






(1) Borrow from exiting BE connections.

160 – 50 = 110 Kbps



Credit


2008/07/25 Page 19




Credit







160 – 50 = 110 Kbps(2) Borrow from exiting

nrtPS connections. 110 – 50 = 60 Kbps

2 nrtPS 100 Kbps 100 Kbps 0 Kbps

(3) Borrow 45Kbps from CID3 Borrow 15Kbps from CID4 60 * 150/(150+50) = 45 60 * 50/(150+50) = 15



Credit


2008/07/25 Page 20




Credit













Credit


Accept the Pairing UGS Call2008/07/25 Page 21




Credit









BB Success !!!

2 nrtPS 100 Kbps 100 Kbps 0 Kbps3 rtPS 255 Kbps 150 Kbps 105 Kbps4 rtPS 185 Kbps 150 Kbps 35 Kbps5 UGS 80 Kbps 80 Kbps 0 Kbps6 UGS 80 Kbps 80 Kbps 0 Kbps

2008/07/25 Page 22


Stage One ： Allocate the guaranteed reserved bandwidth for each

existing connection at most.

Stage Two: Allocate the remaining bandwidth First, satisfy all rtPS connections that require more

BW. Final, allocate the remaining BW to nrtPS and BE

evenly.

min UL_Req+DL_Req , UL_Rsv+DL_Rsv

2008/07/25 Page 23

Two Stage Bandwidth AllocationTwo Stage Bandwidth AllocationCollect all of DL_BwReq and UL_BwReq

In current frame, the system can support

all of the DL_BwReq and UL_BwReq?

Grant every received BwReq directly.

Is there any remaining bandwidth

?

Share the remaining bandwidth to every Uplink connection fairly.

Execute “ Stage One” of bandwidth allocation algorithm

Is there any remaining bandwidth

?

Execute“ Stage Two” of bandwidth allocation algorithm

Gather the grant bandwidth according to different service classes.

Gather the grant bandwidth according to each SS.

Downlinkor

Uplink?

N

Y

Y

N

Y

Downlink Uplink

N




2008/07/25 Page 24

Outline

2008/07/25 Page 25

Simulation Environment

Simulation Environment Values

Number of BS 1

Number of SS 5 - 50

Traffic types generated by each SS UGS, rtPS, nrtPS, BE

Total Bandwidth 64 Mbps

Total Simulation Time 1000 Seconds

Frame Duration 10 ms

2008/07/25 Page 26

UGS rtPS nrtPS BEApplication VoIP Video Stream FTP EmailAverage Data Rate

64 Kbps DL ： 387KbpsUL ： 38.7Kbps

DL ： 320KbpsUL ： 32Kbps

192 Kbps

Maximum Sustained Traffic Rate 64 Kbps DL ： 464.4Kbps

UL ： 46.44KbpsDL ： 384KbpsUL ： 38.4Kbps

230.4Kbps

Minimum Reserved Traffic Rate 64 Kbps DL ： 309.6Kbps


153.6Kbps

Low Bound of Reserved BW Max Rate Avg Rate Min Rate 0Call Inter Arrival Time

15 SecondsExponential

37.5 SecondsExponential



Call Duration 120 secondsExponential

240 secondsExponential



Maximum Latency 20 ms 50 ms 100 ms 400 ms

Packet Size 160 BytesFixed-Size

64-1518 BytesUniform



Packet Inter Arrival Time

20 msFixed Period

DL : 16.35 msUL : 163.5msFixed Period

DL ： 20 msUL ： 200msFixed Period

33msFixed Period

Traffic Generation and Simulation Environment

Pairing vs NonPairing Call Admission Control

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Simulation Experiment 1

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Definition of NonPairing CACReject Call

Non-Pairing CAC First Type of Connection Fail

Non-Pairing CAC Second Type of Connection Fail

(a) (b)

BS SSBS SS

Connection Request (Uplink DSA)

Accepted Provisionally

BS want to send a Connection Request(Downlink DSA), but rejected by CAC !

Reject the previous accepted uplink connection and release the reserved BW

Round Trip Time of Downlink Connection Request

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Call Blocking Probability Pairing vs NonPairing

UGS rtPS

III

I + II

I

II

I + II

Pair

Pair

2008/07/25 Page 30

Call Blocking Probability Pairing vs NonPairing

nrtPS BEI II + II

I

Pair

I + II

I I

Pair

I

Pairing CAC is better than NonPairing CAC Pairing CAC really achieves higher performance

than NonPairing CAC on call blocking probability.What cause NonPairing CAC low performance?

The reply connection request is always rejected leading to high blocking probability of NonPairing Type II .

So the following next experiment will base on Pairing CAC scheme to study Bandwidth Borrowing scheme continually.

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Summary of Experiment 1

Based on Pairing Call Admission Control

Bandwidth Borrowing vs

Non Bandwidth Borrowing

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Simulation Experiment 2

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Pairing CAC without BB Pairing CAC with BB

Call Blocking Probability Using Bandwidth Borrowing (BB)

rtPS

rtPS

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Packet Drop Rate ─ Non BB vs BB

nrtPS BE

rtPS

Proposed a novel QoS architecture over WiMAX, including : Pairing Call Admission Control (CAC) Bandwidth Borrowing scheme on CAC level Two Stage Bandwidth Allocation

Dynamic Downlink and Uplink bandwidth allocation.

2008/07/25 Page 35

Conclusion

Different traffic pattern (self-similar traffic)Extent to IEEE 802.16e mobility issue

(handover call, signal strength)

End to End QoS guarantee (ASN, CSN)Heterogeneous Network (integrated with

WiFi, 3G system, or EPON)

2008/07/25 Page 36

Future work

Q & AThanks for Your Attention

2008/07/25 Page 38

Worldwide Interoperability for Microwave Access ( WiMAX )

Wi-Fi802.11a/b/g

802.15.1Bluetooth

802.15.3High Speed

WirelessPAN Wi-Fi

802.11n

Bandwidth

1 Gbps

100 Mbps

10 Mbps

1 Mbps

PAN LAN MAN WAN<1m 10m 100m Up to 50Km Up to 80Km

WiMAX802.16

(802.16-2004 & 802.16e)

4G

3G

2.5G

IEEE 802.15 IEEE 802.11 IEEE 802.16 3GPP

PAN: Personal area networks MAN: Metropolitan area networks

LAN: Local area networks Wide area networks

IEEE 802.16 Operation Mode

Page 392008/07/25

Point to MultiPoint (PMP) Mode Mesh Mode (Optional)

(a) (b)

Mesh SS

Mesh SS WiMAXBackhaulnetwork

SS

SS

SS

SSBS

Mesh SS

Base Station (BS)

Specify area MAC layer PHY layer

Topology of Operation Mode PMP (Point to Multiple Point) Mesh

Multiplex TDD FDD

2008/07/25 Page 40

IEEE 802.16 d

2008/07/25 Page 41

Bandwidth Request

SSs may request bandwidth in 3 ways: Contention-based bandwidth requests

(Broadcast Polling or Multicast Group Pollng) Contention-free bandwidth requests (Unicast

Polling) Piggyback a BW request message on a data

packet

2008/07/25 Page 42

Bandwidth Allocation

BS grants/allocates bandwidth in one of two modes Grant Per Subscriber Station (GPSS) Grant Per Connection (GPC)

How much bandwidth to be granted based on - Requested BW QoS parameters Available resources

Grants are realized through the UL-MAP

The central concept of the MAC protocolA service flow is a unidirectional flow of

packets that is provided a particular QoS.SS and BS provide this QoS according to the

QoS parameter set.Existing in both uplink and downlink and may

exist without being activated.Must have a 32bit SFID, besides admitted and

active status also have a 16-bit CIDPage 43

Service Flow

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2008/07/25 Page 44

BS SS

BidirectionalConnection Request

(Uplink and Downlink DSA)

Accepted or Reject

Definition of Pairing and Non Pairing CAC

BS SS

Uplink Connection Request (Uplink DSA)

Uplink Connection Request(Uplink DSA)


BS send the Downlink Connection Request(Downlink DSA)

to SS after admitted by CAC


Uplink DSA Accepted Finally

Pairing Non Pairing

2008/07/25 Page 45

Definition of NonPairing CAC Accept Call

Round Trip Time: The duration time

between admitting Uplink Connection Reqest and BS send out the Downlink Connection Request.

BS SS

Uplink Connection Request (Uplink DSA)

Uplink Connection Request(Uplink DSA)


BS send the Downlink Connection Request(Downlink DSA)

to SS after admitted by CAC


Uplink DSA Accepted Finally

2008/07/25 Page 46

Operation of Bandwidth Borrowing (2)

If the bandwidth borrowed from every exiting

BE connection i is ：

Else, try to borrow bandwidth from nrtPS after borrowing all bandwidth of

BE

borrow C r e d i tB B

BE

C r e d i tB

_

_1

( )

( )B E

i i

c u r r e n t low boundborrow

i i

c u r r e n t low boundi

NRsv Rsv B

Rsv Rsv

2008/07/25 Page 47

Operation of Bandwidth Borrowing (3)If

the bandwidth borrowed from every exiting nrtPS connection i is ：

Else, try to borrow bandwidth from rtPS after borrowing all bandwidth of

BE n r t P S

borrow C r e d i t C r e d i tB B B

_

_1

( )

( )n r t P S

i iBEc u r r e n t low bound

borrow C r e d i tj j

c u r r e n t low boundj

NRsv Rsv B B

Rsv Rsv

n r t P S

C r e d i tB

2008/07/25 Page 48

Operation of Bandwidth Borrowing (4)

If the bandwidth borrowed from every exiting rtPS

connection i is ：

Else, Bandwidth Borrowing Fail ! Reject the connection request.

BE n r t P S r t P S

borrow C r e d i t C r e d i t C r e d i tB B B B

_

_1

( )

( )r t P S

i iBE n r t P Sc u r r e n t low bound

borrow C r e d i t C r e d i tk k

c u r r e n t low boundk

NRsv Rsv B B B

Rsv Rsv

2008/07/25 Page 49

Mandatory Packet Scheduling Algorithm

Scheduling Service

Mandatory Algorithm

UGS First In First Out (FIFO)rtPS Earliest Deadline First (EDF)nrtPS Weighted Fair Queue (WFQ)BE Round Robin (RR)

2008/07/25 Page 50

BS

.

.

.

.

.

WiMAXBackhaulNetwork

SS-1 Local Network SS-1

SS-2

UGSrtPSnrtPSBE

SS-2 Local Network

UGSrtPSnrtPSBE

SS-N Local Network

UGSrtPSnrtPSBE

SS-N

電腦電腦電腦電腦

System Model of Simulation Experiment

Note : We assume that only SS can send the connection request to BS actively

2008/07/25 Page 51

UGS rtPS nrtPS BEApplication VoIP Video Stream FTP EmailAverage Data Rate

64 Kbps DL ： 387KbpsUL ： 38.7Kbps

DL ： 320KbpsUL ： 32Kbps

192 Kbps

Maximum Sustained Traffic Rate

64 Kbps DL ： 464.4KbpsUL ： 46.44Kbps

DL ： 384KbpsUL ： 38.4Kbps

230.4Kbps

Minimum Reserve Traffic Rate 64 Kbps DL ： 309.6Kbps


153.6Kbps

Accept Call Criteria Max Rate

64Kbps

(Max+Avg)/2DL ： 425.7KbpsUL ： 42.57Kbps

(Avg+Min)/2DL ： 288KbpsUL ： 28.8Kbps

Min / 276.8Kbps

Low Bound of Guarantee Bw Max Rate Avg Rate Min Rate 0

Call Inter Arrival Time


37.5 SecondsExponential



Call Duration 120 secondsExponential





2008/07/25 Page 52

UGS rtPS nrtPS BEMaximum Latency 20 ms 50 ms 100 ms 400 ms

Schedule Scheme FIFO EDF WFQ RR

Packet Size 160 BytesFixed-Size




Packet Fragment 80 Bytes 240 Bytes 120 Bytes 120 Bytes

Packet Inter Arrival Time

20 msFixed Period

DL : 16.35 msUL : 163.5msFixed Period

DL ： 20 msUL ： 200msFixed Period

33msFixed Period

Reserve Bw Per frame (Non Bandwidth Borrowing Mode)

80 Bytes

DL ： 532.125 BUL ： 53.2125 B

DL ： 360 BUL ： 36 B

96 Bytes


Performance Metric

Call Blocking Probability :

Packet Drop Rate :

UL Blocking Calls DL Blocking CallsUL Total Calls DL ToTal Calls

Total Dropped PacketsTotal Generated Packets

Page 532008/07/25

Definition of Pairing CAC

Accepted :

Reject : UL Total Calls DL Total Calls ；

UL Total Calls UL Blocking Calls ；

BS SS

BidirectionalConnection Request

(Uplink and Downlink DSA)

Accepted or Reject

Master's Defense

Page 54

2008/07/25

Non-Pairing CAC First Type of Connection Fail

Non-Pairing CAC Second Type of Connection Fail

(a) (b)

BS SSBS SS

Connection Request (Uplink DSA)


BS want to send a Connection Request(Downlink DSA), but rejected by CAC !

Reject the previous accepted uplink connection and release the reserved BW


Definition of NonPairing CAC Reject Call

Master's Defense

Page 55

2008/07/25

Definition of NonPairing CACMaster's Defense

Page 56

Default RTT of DL connection request ： 0.5 secondsAccepted :

First Type of Connection Fail :

Second Type of Connection Fail : UL Total Calls UL Blocking Calls ；

UL Total Calls DL Total Calls ；

UL Blocking Calls DL Blocking Calls ；

UL Total Calls DL Total Calls ；

2008/07/25

2008/07/25 Page 57

Where is the issue ?Call Blocking Probability - Pairing and NonPairing

Non Pairing CAC without BB Pairing CAC without BB

2008/07/25 Page 58

Call Blocking Probability Non BB vs BB

UGS rtPS

2008/07/25 Page 59

Call Blocking Probability Non BB vs BB

nrtPS BE

Introduction of IEEE802.16 and QoSProposed QoS System Architecture


Two Stage Bandwidth AllocationPerformance EvaluationConclusion and Future Work

2008/07/25 Page 60

Outline


System available Bw = 0CID Type Reserved


Credit


Accept the Pairing UGS Call2008/07/25 Page 61


System available Bw = 0CID Type Reserved


Credit





Now System avaible Bw= 0Start to BB operations at BS.




BB Success !!!

2 nrtPS 100 Kbps 100 Kbps 0 Kbps3 rtPS 255 Kbps 150 Kbps 105 Kbps4 rtPS 185 Kbps 150 Kbps 35 Kbps5 UGS 80 Kbps 80 Kbps 0 Kbps6 UGS 80 Kbps 80 Kbps 0 Kbps

2008/07/25 Page 62

Range of Bandwidth Reservation

PeakRate

0 (Peak+Average)/2

(Average+Min)/2

Min/2

Rsv-BE

Rsv-rtPS Low Bound

AverageRate

Rsv-nrtPS Low Bound

MinRate

Rsv-BE Low Bound

Rsv-nrtPS Rsv-rtPS Rsv-UGS

2008/07/25 Page 63

Call Blocking Probability Pairing CAC vs NonPairing

2008/07/25 Page 64

NonPairing Call Blocking Probability (UGS) Type I vs Type II

2008/07/25 Page 65

NonPairing Call Blocking Probability (rtPS) Type I vs Type II

2008/07/25 Page 66

NonPairing Call Blocking Probability (nrtPS) Type I vs Type II

2008/07/25 Page 67

NonPairing Call Blocking Probability (BE) Type I vs Type II

2008/07/25 Page 68

Bandwidth Borrowing Schemes

Service Class

of

Connection Request

Bandwidth Borrowing

from the exiting connections in system

Scheme_1 Scheme_2 Scheme_3

UGS BE nrtPS BE nrtPS rtPS BE nrtPS

rtPS BE nrtPS BE nrtPS rtPS BE nrtPS

nrtPS N/A N/A BE nrtPS

BE N/A N/A N/A

2008/07/25 Page 69

Pairing Call Blocking Probability (UGS) BB vs NonBB

2008/07/25 Page 70

Pairing Call Blocking Probability (rtPS) BB vs NonBB

2008/07/25 Page 71

Pairing Call Blocking Probability (nrtPS) BB vs NonBB

2008/07/25 Page 72

Pairing Call Blocking Probability (BE) BB vs NonBB

2008/07/25 Page 73

Packet Drop Rate (rtPS) BB vs NonBB

2008/07/25 Page 74

Packet Drop Rate (nrtPS) BB vs NonBB

2008/07/25 Page 75

Packet Drop Rate (BE) BB vs NonBB

A Study of the Bandwidth Management Architecture over IEEE 802.16 WiMAX

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