elements of cross-layer system & network design for qos-enabled wi-max networks

Elements of Cross-Layer System Elements of Cross-Layer System and Network Design for QoS-and Network Design for QoS-

Enabled Wi-Max NetworksEnabled Wi-Max Networks

© Copyright 2006-07All Rights Reserved

Dr. Abhay KarandikarIIT Bombayhttp://www.ee.iitb/ac/in/~abhay

Metanoia, Inc.Critical Systems Thinking™

Dr. Vishal SharmaMetanoia, Inc. http://www.metanoia-inc.com

Milcom’07, 29-31 October 2007, Orlando, FL 2Copyright 2006-07All Rights Reserved


Workshop Overview

IEEE 802.16 standards – an introduction

PHY and MAC: Key design QoS design aspects

Scheduling services & design implications

System architectures for QoS

Cross-layer based scheduling techniques for QoS

Implementation issues in algorithms and protocols

Future of WiMax and applicability to military communications

Wi-MAX System ArchitectureWi-MAX System Architecture



Metanoia, Inc.Critical Systems Thinking™IEEE 802.16 Wireless MAN

Standard: Background

Developed by IEEE 802.16. WG

Technologies/protocols for air-interface of BWA systems Specifies PHY and MAC layer

Evolutionary standard … Originally -- stationary, enterprise-class deployments (2001)

Enhanced for residential-class applications (2003)

Extended for mobile + fixed terminals (2002-2005)

1999 2000 2001 2002 2003 2004 2005 2006

IEEE Std. 802.16-2001IEEE Std. 802.16-2004

IEEE Std. 802.16e



802.16 Wireless MAN Standard

PHY layer – primary arbiter of physical environment in which technology can operate

MAC layer – essence of standard – supports … Differentiated QoS – specifies scheduling behavior, not algos.

Many demanding enterprise-class or consumer-class apps.

“Metropolitan” target scale, not geography Size of city, but could be rural or urban

Ensures spectrum efficiency – via techniques we see later


Metanoia, Inc.Critical Systems Thinking™IEEE 802.16 MAN

Market Applications and Deployment

Fiber Extension for Core Infrastructure

Wi-Fi Backhaul

DSL/Cable Alternative

EnterpriseCustomer

Multi-tenantCustomers (condo)

IndustrialEnterprise

Mall/CoffeeShop Hotspot

ResidentialCustomer

Companywarehouse Base Station

(BS)

Base Station(BS)

MobileStation (MS)

Core Network

Mesh Node

WiredBackhaul


Metanoia, Inc.Critical Systems Thinking™A Word on QoS Architecture:

Basic Elements

Servicedefinitions/Rules

PacketClassification

ConnectionAdmission Control

(CAC)

Scheduling

Control Plane

Data Plane

From provisioningsystem

Incoming data

Signaling

MarkingShaping/Policing

Metering

ManagementPlane



802.16 High-Level System Operation

SS1

SS2

SS3

SS4

BS




SS1

SS2

SS3

SS4

BS

1

2

3

4

1 2 3 4



SS1

SS2

SS3

SS4

BS


Requests

Grants

Frame

DL UL

UL Control

UL Data Part Start

1

1

3

3

2

2BS computes non-

conflicting schedule




Fixed BS (one), distributed SS’s (many)

Time-slotted operation

Time adjusted such that receptions at BS arrive in sync.

Initial ranging for each SS

Multiple access to share radio medium

Bandwidth requests SSs BS in UL

BS computes non-conflicting schedule

Based on nature of requests, # of SS’s, channel state

Grants BS SSs in DL

At appointed time, SS’s transmit to BS


Metanoia, Inc.Critical Systems Thinking™System and Protocol Architecture:

Components

System Architecture

Topologies supported

Framing + slot structure

Duplexing

Multiplexing

Multiple access technique

B/w request/grant mechanism

MAC

Adaptive PHY

Protocol Architecture

Layered reference model

Convergence sublayer (CS)

Common Part Sublayer (CPS) – discussed in detail

Security sublayer (SS) – not focus of this talk

ARQ protocol



TDD Frame Structure -- Details

j-3 j-1 j j+1 j+2 j+3 j+4j-2

UL-subframe

DIUC a data

DIDU b data

DIDU n data

Adaptive SS1 sched data

SS transition gap

DL-MAP UL-MAP DCD UCD

Collision

Access Burst

Collision

Bandwidth request

Initial Ranging

IE

Data Grant IEs

Gap IE

End of MAP IE

Unicast Poll to

SSi

Unicast Poll to

SSj

Multicast Conten-tion IE

Broadcast Contention

IE

TDM portion

Preamble

Frames

DL-subframe

Frame Control Section

Request IEs

Initial main -tainance

Request contention

MAC and PHY: Key QoS MAC and PHY: Key QoS Design AspectsDesign Aspects




MAC Key Aspects

Centralized scheduling & multiple access Access overhead ~ zero

Nearly no wasted bandwidth

Data encapsulation Small headers -- minimize per-PDU overhead

Packing Multiple SDU’s/PDU for apps. with small pkts. (VoIP, TCP) - efficiency

Fragmentation Split large SDU’s across PDU’s for real-time adaptation to channel



802.16 MAC Layer Basics

Functions Protocol for accessing medium

Radio resource and radio-link control

Security

MAC instance identified by unique 48-bit address SS can have multiple MAC addresses (with multiple I/Fs)

Full MAC address used only during Initial registration

Authentication

Not carried in every 802.16 MPDU



MAC Design Features Supporting QoS

RLC (radio link control) pulled into MAC Enables tighter control of cross-layer scheduling

Connection-oriented MAC Gives notion of connection ID

Allows management + housekeeping per connection

MAC headers for efficient transport of Control/signaling information

Bandwidth requests

Efficient transportation of MAC PDUs Via packing/fragmentation ops.



ARQ + H-ARQ Key Aspects

Process for handling MPDU errors Error detection via CRC/FEC or checksum

Retransmission (ReTX) strategy Selective-Repeat (SR) and Go-Back-N (GBN) variant

ReTX unit – block-based Block size ranging from 1 to 2040 bytes

Compact bitmap-based feedback – for multiple blocks

Cross-layer protocol: involves both PHY and MAC Negotiated during SS initialization; for OFDMA PHY only

Stop-and-wait with immediate/synchronous feedback



802.16 Protocol Reference Model

Service-SpecificConvergence Sublayer

Service-SpecificConvergence Sublayers

MAC Common PartSublayer

Security Sublayer

Physical Layer(PHY)


Security Sublayer

PHY Layer

MAC SAP

PHY SAP

CS SAP

NetworkMgt. Sys.

Data/Control Plane Management Plane

MAC

PHY



Convergence Sub-layer (CS) : Architecture

ATM-CS IP-CS Ethernet CS


MAC Security Sublayer

MAC SAP

PHY SAP

CS SAP CS SAP CS SAP

Data PDU arrives (payload protocol)

1

Compress redundant hdrs., add PDU hdr.

3

Deliver processed pkt. to MAC SAP

4

Receive MSDU2’

Deliver payload protocol PDU to higher layer

4’

Restore compressed protocol headers

3’

Scheduling and transmission

5

Reception and decoding

1’

Map PDU to Svc. Flow

2

Classification & mapping of IP QoS

to 802.16 Qos


Metanoia, Inc.Critical Systems Thinking™Protocol Architecture:

Common Part Sub-layer (CPS)

Supports multiple MAC CSs

Performs core MAC functions, independent of CS Oblivious to internals of MAC

CS PDU

Transforms MSDUs from CS into MPDUs Via various operations, some

of which we see later

Responsible for media access, connection mgt, QoS


MAC Security Sublayer

MAC SAP

PHY SAP

MAC SDU’s

MAC PDU’s

Medium Access,Connection Management,

QoS (scheduling, CAC)

Encapsulation of MACpayload, privacy key mgt.protocol



PHY Key Aspects

WirelessMAN-SC

10-66 GHz operations

LOS necessary

WirelessMAN-SCa

2-11 GHz operation

Simpler Tx, complex Rx due to multipath

OFDM

2-11 GHz operation

NLOS transmission

Modulation

BPSK

QPSK

QAM

Physical slot-WirelessMAN-SC

4 QAM symbols


Metanoia, Inc.Critical Systems Thinking™PHY Modulation and Coding

Schemes for 802.16d

Rate ID

Modulation rate

Coding

Information bits/symbol

Information bits/OFDM symbol

Peak data rate in 5MHz (Mb/s)

0 BPSK 1/2 0.5 88 1.89

1 QPSK 1/2 1 184 3.95

2 QPSK 3/4 0.5 280 6.00

3 16QAM 1/2 2 376 8.06

4 16QAM 3/4 3 568 12.18

5 64QAM 2/3 4 760 16.30

6 64QAM 3/4 4.5 856 18.36

Source: [GWA05]

Scheduling Services and Scheduling Services and Design ImplicationsDesign Implications




Enforcing QoS Requirements -- Options

Applications: voice, video, data, multi-media, gaming

Widely varying QoS needs

Prioritized QoS Network treats traffic based on

relative priority

E.g. Diffserv approach

Parameterized QoS Network guarantees a set of

QoS parameters for traffic

E.g. ATM approach

Quality-of-Service



Quality of Service (QoS) Parameters

Bit level Minimum BER

Packet level Throughput Delay Jitter Packet Loss

Call level Blocking probability Dropping probability

Application level End-to-End Throughput / response time Peak signal-to-noise ratio

Requires Effective Link level

Scheduling Algorithms



QoS in Access Networks

# flows limited per-flow QoS possible

Adverse channel environment, b/w scarcity

Wireless access is the bottleneck

Connection-oriented services with guaranteed perf. will help ensure end-to-end QoS



Wireless QoS: What’s Different?

Variable capacity networks

High probability of error

Variable airtime for transmitting data

Depends on AMC, FEC, link quality

Fairness is an issue



Differentiated QoS: What is needed?

Flexible PHY and MAC framing

Centrally-controlled MAC

Sophisticated AMC, FEC, retransmission schemes

Ability to give QoS on DL and UL

Symmetric operation – high throughput in both UL/DL

Efficient scaling with sufficient per-subscriber throughput



Wi-MAX QoS Classes

De

lay

To

lera

nce

Low

HighBest Effort

(BE)

E

mai

l

FTP

Non Real Time Polling Service(nrtPS)

Unsolicited Grant Service(UGS)

W

eb B

rowsi

ng

High S

peed F

TP

T

DM

T1/E1

S

tream

ing V

ideo

IPTV, V

oIP

Real Time Polling Service(rtPS)


Metanoia, Inc.Critical Systems Thinking™QoS Classes in 802.16 and

Characterizing Parameters

Best Effort(BE)

Non Real-Time Polling Service(nrtPS)

Unsolicited Grant Service(UGS)

Real-Time Polling Service(rtPS)

Type Service Flow Parameters

UGS

- Max. sustainable traffic rate - Max. latency - Tolerated jitter - Request/transmission policy

rt-PS

- Min. reserved traffic rate - Max. sustainable traffic rate - Max. latency - Request/transmission policy

nrt-PS

- Min. reserved rate - Max. sustainable rate - Priority - Request/transmission policy

BE - Max. sustainable traffic rate - Priority - Request/transmission policy



Mapping Applications to 802.16 QoS

Real-time

Control

Critical

Bulk

BE

EF

AF3, CS6,CS3

AF2, CS2

AF1

BE

UGS

rt-PS

nrt-PS

BE

Voice

Video

Signaling

Control

Critical Data

Bulk Data

Best Effort

Scavenger

VoIP

VoD

H.323, SIP

OSPF, RIP, BGP,SNMP, NFS

SAP, Oracle, BEA

SNA

Messaging

Email

FTP/HTTP

Data apps., IntranetWeb

KaZaa, Quake,recreational video

Enterprise Applications (100s)

Enterprise Service Classes

(8-11)

Provider Service Classes

(3-5)

IP QoSPHBs (5-8)

802.16 Traffic Types

(4)

System Architectures for QoSSystem Architectures for QoS



Metanoia, Inc.Critical Systems Thinking™System-Level View of QoS in 802.16

Networks: Building Blocks

@ Subscriber Station (SS) SS UL scheduler

Request generator

Contention resolution module

UL traffic classifier

DL channel monitor

@ Base Station (BS) BS UL grant scheduler

UL/DL MAP generators

DL/UL data schedulers

UL channel monitor

BS periodic grant generator

Contention ratio calculator (CRC)

Contention slot allocator (CSA)

Frame partitioner

Frame generator


Metanoia, Inc.Critical Systems Thinking™Representative Subscriber Station

(SS) QoS Architecture

Class n

Class 3

Class 2

Class 1

UL

Tra

ffic

Cla

ssif

ier

SS UL DataScheduler

CRM

ULTraffic

Downlink Data(to clients)

GrantSize

RequestSize

RetrySignal

BandwidthRequests

Downlink

GrantSize

QueueInformation

Uplink Multi-classData Queues

Uplink Data(to BS)

UL B/w RequestGenerator


Metanoia, Inc.Critical Systems Thinking™Representative Base Station (BS)

QoS Architecture

Class n

Class 3

Class 2

Class 1

Tra

ffic

Cla

ssif

ier

BS DL DataScheduler

DL Data Queues

Tra

ffic

Sh

ape

r

DL data fromnetwork

DL Scheduler

DL

MA

PG

ener

ato

r

Frame Partitioner

DL SubframestartDL Data queue

status

UL MAPGenerator

BS Upstream GrantsScheduler

BS Periodic B/wGrant Generator

UL Subframestart

UL B/w RequestQueue Status

AdmissionControl

ChannelMonitor

CRC

CSA

Requeststatus

Contentionratio

DSA_REQ

DSA_RSP

Slots allocated

Outgoingframe to SSs

UL DataTraffic Shaper

B/w requests

To network

UL data

Periodic PollGenerator

Frame Generator

Channelsense

Uplink

Queue info.

Downlink

Cross-Layer Based Cross-Layer Based Scheduling Techniques for Scheduling Techniques for

QoSQoS

© Copyright 2006All Rights Reserved


At the start …At the start …





A Layered View of Networks

Network engineer’s viewpoint Allocate the resources of the reliable bit-pipe efficiently

Communication engineers viewpoint Build better pipes

Higher reliability, better spectral efficiency

Transport

Network

MAC

PHY

Application

View the physical layer as a “reliable bit pipe”


Metanoia, Inc.Critical Systems Thinking™Scheduling in Wireline Networks

(Network Layer)

Frame-based scheduling

Time split into frames

Max. amount of traffic that session may transmit during the frame is reserved

e.g., Round Robin, Deficit Round Robin

S


Metanoia, Inc.Critical Systems Thinking™Scheduling in Wireline Networks

(Network Layer)

Sorted-priority scheduling

Global parameter p associated with each user

Updated on packet arrival and departure

Packet time-stamped with a value = f(p)

Packets sorted based on their timestamps

S

34

57

26 1

1 2 3 4 5 76



Cross-Layer Design Wireless channel characterized by …

Signal strength variation (fading) over time, frequency, space

Interference

Limited battery life at hosts

Physical layer no longer viewable as fixed-rate bit pipe

Resource allocation must account for channel quality Adaptive MAC

Adaptive PHY – modulation and coding

Significant performance gains in wireless networks

by Cross-Layer Design



Scheduling in Wi-Max Determines

Transmission opportunities Appropriate burst profile

Transmission Opportunities TDMA

Timeslots

OFDM PHY DL – (Time slots) UL – (Time slots within individual sub-channels)

OFDMA DL/UL opportunities -- time slots within sub-channels

MIMO Normal zone Transmit diversity zone AAS zone

Transm

issi

on

Zone

SubChannel

Time slot

Scheduling Axes



Wireless Channel Fading

Large-scale

Signal-strength variation due to path loss

Medium-scale

Caused by shadowing due to obstructions

Buildings, hills, rain, and foliage

Small-scale

Due to multipath between transmitter and receiver

Constructive/destructive interference by signals from multiple paths



Small-Scale Fading

SignalStrength

Time

Variation over frequency Frequency selective

Amp. gains, phase shifts vary with freq. Flat fading

Multipath delay < Symbol period T

Delay spread Td << Symbol period T

Coherence b/w Wc >> Signal b/w W

Variation over time Fast

Coherence time Tc < Symbol period T

Slow

Coherence time Tc >> Symbol period T



Effects of Channel Fading

BER: additive white Gaussian noise (AWGN) without fading

Constants K1 and K2 depend on the modulation scheme

BER: AWGN wireless channel with fading

Non-fading channel BER decays exponentially with SNR

Fading channel BER decays inversely with SNR

21

( )e

K SNRP K e

1( )eP K SNR



Fading Countermeasures

Base Station

(Soft Handoff)

MIMO

MIMOSpatial

CodingAdaptive Modulation and

Coding (AMC)Time

Rake ReceiverMulti Carrier Modulation

(OFDM)Frequency

CDMAWiMAXDiversity Type

Multiuser Diversity: A New Paradigm for Multiuser Diversity: A New Paradigm for

SchedulingScheduling





SNR Fluctuations in a Multiuser System

SNR

Time

User 1

User 2

User 3



SSk

SS1

SS2

BS

h1

h2

hk

S

Scheduler

Multi-User Diversity and Opportunistic Scheduling

Channel fades independently for each user so

… different users experience different channel gains

High prob. that some user will have strong channel

BS schedules the user with strongest (best) channel

Hence … “Opportunistic Scheduling”



Opportunistic Scheduling in WiMAX

Channel-quality measurements

Each user performs RSSI and CINR measurements

Reports to BS via REP-RSP messages

BS changes data rate adaptively as a function of channel gain

Adaptive modulation and coding

Transmit at a high rate when the channel is good

Higher constellation 64-QAM and ¾ rate convolutional coding

Transmit at a lower rate when the channel is bad

Lower constellation QPSK and ½ rate convolutional coding


Metanoia, Inc.Critical Systems Thinking™DRR: A Practical Scheduling

Algorithm

300500400

200400300

250400550

300

650200350

600

0

0

0

1

Round RobinPointer

DeficitCounter

600

QuantumSize

1

2

3

4

500400

200400300

250400550

300

650200350

300

600

0

0

2

Round RobinPointer

DeficitCounter

1

600

QuantumSize

2

3

4

Balance

Packet sent

FairnessDRR = 3*(FairnessWFQ) Time complexity O(1)

Adapted from: [ShV96]


Metanoia, Inc.Critical Systems Thinking™Opportunistic DRR (O-DRR):

Fairness and Throughput: Fair among users

Max. difference in allocated bandwidth < 10 % of average

Fair among traffic classes Both class1 and class2 traffic get almost equal number of slots

As k increases, fairness decreases (intuitively expected)

Source [RBS06a,b]



O-DRR: Delay Performance Meets delay guarantees of different classes of traffic

Packets dropped only if delay is violated

Packet drop < 8.5% for both classes of traffic

For larger k, the dropping percentage is higher

For worst case k=100, 91.5% of traffic meets its delay

Source [RBS06b]

Cross-Layer Scheduling in OFDMACross-Layer Scheduling in OFDMA





OFDM Basics

If coherence bandwidth signal bandwidth

Signal experiences frequency-selective fading

Split transmission b/w into large number of sub-carriers

Create N sub-carriers with bandwidth

Symbol time (delay spread)

No inter-symbol interference (ISI)

Overlapping bands possible, if sub-carriers are orthogonal

N

WW

N

1 1N m

N c

T TW W

WcW



OFDM Symbol in the Frequency Domain

. . .

Ideal sampling positions(in frequency domain)

N Sub-carriers

Frequency

sf



OFDMA Explained

OFDM: PHY layer technique

OFDMA: multiple-access scheme

User occupies subset of sub-carriers (traffic channels)

Sub-carriers assigned to a particular user may change over time

11

2 2

2

33

33

Frequency

Time

User 3

User 2

User 1



OFDMA Explained

OFDM: PHY layer technique

OFDMA: multiple-access scheme

User occupies subset of sub-carriers (traffic channels)

Sub-carriers assigned to a particular user may change over time

Time

23

11

2 233

3Frequency 1

12

2 233

33



Pre

am

ble

ULMAP

DLMAP

FCH

DL Burst #1

DL Burst #3

DL Burst #4

DL Burst #2

DL Burst #6

DL Burst #7

DL Burst #5

OFDM Symbol Number

Su

b-c

han

ne

l L

og

ical

Nu

mb

er

Downlink Subframe

ULMAP

(cont.)

0 1 3 5 7 9 . . . . . . N-1

1

S-1

SS+1

Ns

802.16 OFDMA Frame Structure

Guard

0 . . . . . . . . . M-1

Uplink SubframeR

an

gin

g

ACKCH

Fast Feedback (CQICH)

UL Burst #1

UL Burst #2

UL Burst #3

UL Burst #4

UL Burst #5



Opportunistic OFDMA

Total sum capacity is maximized …

… if throughput in each sub-carrier is maximized

Schedule each sub-carrier to user with best channel gain

Optimum power allocation

Water-filling

Proportional fairness can be extended to OFDMA

Select users with largest ratio of instantaneous data rate to average data rate



OFDMA Scheduling in IEEE 802.16

Users allocated groups of sub-carriers (sub-channels)

Smallest allocation unit – a slot

Single sub-channel, spanning over 1 to 3 OFDM symbols

Subscriber stations (SSs)

Perform channel-quality measurements

Send feedback to Base Station (BS)

Fast feedback channel (CQICH) allocated

MAC sub-header

DL MAP

Implementation Issues in Implementation Issues in Protocols and AlgorithmsProtocols and Algorithms




System Design Issues

End-to-end QoS is a must for growing multimedia applications

Access network is the usual bottleneck – more so, if wireless!

Provisioned & perceived QoS may differ markedly for wireless

Must address fading and interference

Wireless QoS thus requires:

Connection-oriented service

Implies a centralized coordinated MAC

Cross-layer based resource allocation

Adaptive MAC

Adaptive PHY



Wi-Max Protocol Implementation Model

Service-SpecificConvergence

Sublayer

Service-SpecificConvergence Sublayers


Security Sublayer

Physical Layer(PHY)


Security Sublayer

PHY Layer

MAC SAP

PHY SAP

CS SAP

NetworkMgt. Sys.

Data/Control Plane Management Plane

MAC

PHY

TuningLayer

Mapping Layer

IP QoS

Mapping Layer

Mapping Layer

Realizes cross-layer functions



Implications …

WiMAX has many options and features

Requires a mapping and tuning layer for translating provider managed services finally to bit/packet-level QoS

Mapping and tuning layer must integrate with service provisioning platform

Requires a unified implementation framework



802.16 Challenges in Practice

Fluctuating channel Adaptive modulation based on link quality

Link quality fluctuation between very high to very low SNR lead to wide variation in data rates

May affect pkt level performance

TCP and BS scheduler Inappropriate scheduling may lead to time-outs

BW grants need to take into account congestion window

TCP over OFDM Interactions of TCP over OFDM and fading channel not yet fully

understood

OFDMA Performance degrades due to Doppler spread

Future of WiMax and Future of WiMax and Applicability to Military Applicability to Military

CommunicationsCommunications



Metanoia, Inc.Critical Systems Thinking™IEEE 802.16j Mobile Multi-hop

Relay for Military Mesh Network

Network Elements

MMR BS

Relay Station (RS)

Fixed RS (FRS)

Nomadic Relay Station (NRS)

Typical military environment …

RS pre-planned

Antenna heights less than in a commercial env.

Redundant routes between RS and MMR-BS

Support for NRS



Features of 802.16e

PHY Layers

OFDMA 2048, 1024, 512 FFT modes

STC, MIMO

Extensions for H-ARQ

MAC

Handover support

Power management

Multi-zone frame structure

Frame partitioned into multiple zones

Different sub-channelization schemes supportable in each zone



Mobile Broadband Standardization

Various standards (all based on OFDMA + MIMO)

802.16e

802.16m

3GPP Long Term Evolution (LTE)

3GPP UMB

802.20

IMT-Advanced

May harmonize various projects

Global low-cost 4G standard may emerge based on OFDMA

Thank You!Thank You!Questions?Questions?


Glossary and ReferencesGlossary and References




GlossaryAAS Adaptive Antenna Systems

ABR Available Bit Rate

ACK Acknowledgement

ADSL Assymetrical Digital Subscriber Line

AMC Adaptive Modulation and Coding

ARQ Automatic Repeat Request

ATM Asynchronous Transfer Mode

AWGN Additive White Gaussian Noise

BE Best Effort

BER Bit Error Rate

BoD Bandwidth-on-Demand

bps bits per second

BPSK Binary Phase Shift Keying

BS Base Station

BSN Block Sequence Number

BWA Broadband Wireless Access

CAC Connection Admission Control

CBR Constant Bit Rate

CDMA Code Division Multiple Access

CH Channel

CI CRC Indicator

CID Connection Identifier

CINR Carrier to Interference plus Noise Ratio

CLP Cell Loss Priority

CLR Cel Loss Ratio

CoS Class-of-Service

CPS Common Part Sublayer

CQICH Channel Quality Indicator Channel

CRA Contention Ratio Algorithm

CRC Cyclic Redundancy Check

CRC Contention Ratio Calculator

CS Convergence Sublayer

CSA Contention Slot Allocator

CSMA/CA Carrier Sense Multiple Access/Collision Avoidance

DA-FDRR Demand-Aware Fair Deficit Round Robin

DC Direct Current

DCD Downlink Channel Descriptor

Diffserv Differentiated Services

DIUC Downlink Interval Usage Code

DL Downlink

DOCSIS Data Over Cable Service Interface Specification



GlossaryDRR Deficit Round Robin

DSL Digital Subscriber Line

EC Encryption Control

EKS Encryption Key Sequence

EV-DO EVolution Data Optimized

FDD Frequency Division Duples

FDMA Frequency Division Multiple Access

FEC Forward Error Correction

FFSH Fast-Feedback Allocation Sub-Header

FFT Fast Fourier Transform

FIFO First-In First-Out

FSH Fragmentation Sub-Header

FSN Fragment Sequence Number

FTP File Transfer Protocol

FUSC Full Usage of Sub-Channels

GBN Go-Back-N

GFR Generic Frame Rate

GMSH Grant Management Sub-Header

GSM Global System for Mobile Communications

HARQ Hybrid ARQ

HCS Header Check Sequence

H-FDD Half Frequency Division Duplex

HT Header Type

HTTP Hyper-Text Transfer Protocol

IFFT Inverse Fast Fourier Transform

IFS Inter-Frame Spacing

Intserv Integrated Services

IP Internet Protocol

ISI Inter-Symbol Interference

KHz Kilohertz

LAN Local Area Network

LEN Length

LOS Line-of-Sight

MAC Media Access Control

MAN Metopolitan Area Network

MHz Megahertz

MIMO Multi-Input Multi-Output

MPDU MAC Protocol Data Unit

MPLS Multi-Protocol Label Switching

MSDU MAC Service Data Unit

NACK Negative Acknowledgement



Glossary

NFS Network File System

NLOS Non Line-of-Sight

nrt-PS Non Real-Time Polling Service

O-DRR Opportunistic Deficit Round Robin

OFDM Orthogonal Frequency Division Multiplexing

OFDMA Orthogonal Frequency Divison Multiple Access

O-FUSC Optional-Full Usage of Sub-Channels

O-PUSC Optional-Partial Usage of Sub-Channels

PAR Project Authorization Request

PCR Peak Cell Rate

PDU Protocol Data Unit

PER Packet Error Rate

PHSI Payload Header Suppression Index

PHSI Payload Header Suppression

PHY Physical Layer

PM Poll Me

PSH Packing Sub-Header

PTI Payload Type Indicator

PUSC Partial Usage of Sub-Channels

QAM Quadrature Amplitude Modulation

QoS Quality-of-Service

QPSK Quadrature Phase Shift Keying

Rcv Receive

Rcvr Receiver

REQ Request

RNG Ranging

RSP Response

RSSI Received Signal Strength Indicator

Rsv Reserved

rt-PS Real-Time Polling Service

Rv Reserved

Rx Receiver

SAP Service Access Point

SC Single Carrier

SCR Sustainable Cell Rate

SDU Service Data Unit

SFID Service Flow ID

SI Slip Indicator

SINR Signal to Interference plus Noise Ratio

SNMP Simple Network Management Protocol



GlossarySNR Signal to Noise Ratio

S-OFDMAScalable Orthogonal Frequency Division Multiple Access

SR Selective Repeat

SS Subscriber Station

TC Traffic Category

TCP Transmission Control Protocol

TDD Time Division Duplex

TDMA Time Division Multiple Access

TFTP Trival File Transfer Protocol

TLV Type-Length-Value

Tx Transmitter or Transmit

UBR Unspecified Bit Rate

UCD Uplink Channel Descriptor

UF-DRR Uniformly Fair Deficit Round Robin

UGS Unsolicited Grant Service

UIUC Uplink Interval Usage Code

UL Uplink

VBR Variable Bit Rate

VCI Virtual Circuit Identifier

VOD Video-on-Demand

VoIP Voice-over-IP

VPI Virtual Path Identifier

WDRR Wireless Deficit Round Robin

WG Working Group

Wi-Fi Wireless Hi-Fidelity

WLAN Wireless LAN



References and Readings (1) [FaL02] H. Fattah and C. Leung, “A Efficient Scheduling Algorithm for Packet

Cellular Networks,” in Proc. VTC, vol. 4, pp. 2419-2423, September 2002.

[GWA05] A. Ghosh, G. R. Walter, J. G. Andrews, and R. Chen, “Broadband Wireless Access withWiMax/8O2.16: Current Performance Benchmarks and Future Potential,” IEEE Commun. Magazine, vol. 45, pp. 129-136, February 2005.

[IEEE04] LAN/MAN Standards Committee, “IEEE Standards for Local and Metropolitan Area Network: Part 16: Air Interface for Fixed Broadband Wireless Access Systems,” IEEE Computer Society and IEEE Microwave Theory and Techniques Society, May 2004.

[IEEE05] LAN/MAN Standards Committee, “IEEE Standards for Local and Metropolitan Area Network: Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems (Amendments for Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands),” IEEE Computer Society and IEEE Microwave Theory and Techniques Society, September 2005.

[RBS06a] H. Rath, A. Bhorkar, and V. Sharma, “An Opportunistic Deficit Round Robin (O-DRR) Uplink Scheduling Scheme for Wi-Max Networks,” Proc. IETE Int’l Conf. on Next-Generation Networks (ICNGN’06), Mumbai, 9-11 February, 2006.



References and Readings (2)

[RBS06b] H. Rath, A. Bhorkar, and V. Sharma, “An Opportunistic Uplink Scheduling Scheme to Achieve Bandwidth Fairness and Delay for Multiclass Traffic in Wi-Max (IEEE 802.16) Broadband Wireless Networks,” to appear IEEE Globecom’06, San Francisco, CA, 27 Nov. – 1 Dec. 2006.

[ShV96] M. Shreedhar and G. Varghese, “Efficient Fair Queueing Using Deficit Round Robin,” IEEE/ACM Trans. on Networking, vol. 4, no. 3, pp. 375-385, June 1996.

[SRK03] S. Shakkottai, T. S. Rappaport, and P. C. Karlsson, “Cross Layer Design for Wireless Networks,” IEEE Commun. Magazine, vol. 41, no. 10, pp. 74-80, October 2003.

[Vam06] N. Vamaney, “Scheduling in IEEE 802.16 Metropolitan Area Networks,” M. Tech. Dissertation, Dept. of Electrical Engineering, IIT Bombay, September 2006.

elements of cross-layer system & network design for qos-enabled wi-max networks

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