Chun Nie, Thanasis Korakis, and Shivendra Panwar Department of Electrical and Computer Engineering, Polytechnic University, Brooklyn A Multi-hop Polling

Chun NieChun Nie,, Thanasis Korakis Thanasis Korakis,, and and Shivendra PanwarShivendra Panwar

Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering,, Polytechnic University, BrooklynPolytechnic University, Brooklyn

A Multi-hop Polling Service with Bandwidth Request Aggregation in IEEE 802.16j Net

works

A Multi-hop Polling Service with Bandwidth Request Aggregation in IEEE 802.16j Net

works

IEEE VTC 2008IEEE VTC 2008

OutlineOutline OutlineOutline

Introduction

System model

The Multi-hop Polling Service (mPS) Mechanism

Performance evaluation

Conclusions

IntroductionIntroduction IntroductionIntroduction

WiMAX has emerged as an advanced broadband wireless access technology and has attracted a lot of attention.

Recently the 802.16j Relay Task group was formed to standardize a WiMAX multi-hop relay (MMR) system.

In an MMR system, MSs are allowed to route through intermediate RSs to reach the BS, which differs from the single-hop WiMAX topology.


IEEE 802.16j has classified MMR systems into a transparent mode and a non-transparent mode.

BS

RS

MS

BS

RS

MS

User Data

PreambleDL/UL MAP

User Data

PreambleDL/UL MAP

Transparent RS A transparent RS does not transmit preamble,

FCH, DL/UL MAP, and DCD/UCD Centralized scheduling at MR-BS Capacity enhancement only

Non-transparent RS A non-transparent RS transmits preamble, FCH,

DL-/UL-MAP, and DCD/UCD Centralized scheduling or distributed scheduling Capacity enhancement and coverage extension


Conventional scheduling service in WiMAX

Scheduling services in the IEEE 802.16e standard

1) UGS: UGS enables the BS to allocate fixed-size bandwidth periodically to the MS.

2) rtPS: rtPS is designed for RT applications. It enables the BS to poll the MS at fixed intervals for bandwidth requests.

3) ertPS: ertPS is designed for voice application. During voice silence, ertPS decreases the grant size to save bandwidth.

4) nrtPS and BE: nrtPS and BE are two scheduling services for delay-insensitive applications by contention-based bandwidth requests.

MotivationThese scheduling services are basically designed for a single-hop WiMAX system without considering the requirements of a multi-hop system.


Goals: To propose a framework for a multi-hop polling service (mPS) to facilitate efficient UL bandwidth allocation in a centralized non-transparent MMR WiMAX.

• To design a polling service in a multi-hop topology catering to bursty applications.

• To achieve high bandwidth efficiency without compromising delay performance

System modelSystem model System modelSystem model

An RT Bursty ON/OFF Traffic model

Multi-hop Scenarios in IEEE 802.16j Networks

System modelSystem model - An RT Bursty ON/OFF Traffic modelSystem modelSystem model - An RT Bursty ON/OFF Traffic model

An RT Bursty ON/OFF Traffic model

The traffic pattern of applications such as VoIP and gaming, are

characterized by bursty ON/OFF flows with varying rates and packet sizes.

During each ON period:

The variable-sized packets arrive in bursts with variable packet interarrival time

During each OFF period:

No packet is generated and the MS is idle

These applications also have latency constraints on packet delivery.

System modelSystem model - Multi-hop Scenarios in IEEE 802.16j Networks- Multi-hop Scenarios in IEEE 802.16j Networks System modelSystem model - Multi-hop Scenarios in IEEE 802.16j Networks- Multi-hop Scenarios in IEEE 802.16j Networks

One BS, one non-transparent RS, and M MSs

BS

RS

MS

MS

MS

One BS, one non-transparent RS, and M MSs

MS

MS

MS

BS

RS

Data and Signaling

traffic

System modelSystem model - Multi-hop Scenarios in IEEE 802.16j Networks- Multi-hop Scenarios in IEEE 802.16j Networks System modelSystem model - Multi-hop Scenarios in IEEE 802.16j Networks- Multi-hop Scenarios in IEEE 802.16j Networks

The Multi-hop Polling Service (mPS) Mechanism The Multi-hop Polling Service (mPS) Mechanism - Overview- OverviewThe Multi-hop Polling Service (mPS) Mechanism The Multi-hop Polling Service (mPS) Mechanism - Overview- Overview

MS1BS RS

ON Period ON PeriodOFF PeriodRSMS

BSRS

The key idea is how to properly configure polling parameters to achieve the desired delay performance.

ON Period ON PeriodOFF Period

The Multi-hop Polling Service (mPS) MechanismThe Multi-hop Polling Service (mPS) MechanismThe Multi-hop Polling Service (mPS) MechanismThe Multi-hop Polling Service (mPS) Mechanism

MS1

BS RS

The basic idea of mPS:1) MSs send their BWReq to their superordinate RS at their respective polling intervals.

2) RS collects all BWReqs from MSs and generates an Aggregated BWReq to the BS.

MS2

BWReqAggregated

BWReq


MS1BS RS

ON Period ON Period

Ti, min: Minimum polling interval used by the ith MS (1 ≤ i ≤ M)Ni : Number of initial polls with Ti, min during idle period of the ith MS

Ti, max: Maximum polling interval used by the ith MS (1 ≤ i ≤ M)

OFF Period

RSMS


MS1BS RS

ON Period ON Period

T0, min: Minimum polling interval used by the RS N0 : Number of initial polls with T0,min during idle period of RS

T0, max: Maximum polling interval used by the RS

OFF Period

BSRS


An example of mPS mechanism:mechanism:

MS1

BS RS

MS2


RS

MS1

BWReq

T1, min=3

…


An example of mPS mechanism:mechanism:

MS1

BS RS

MS2


RS

MS1

T1, min = 3, T1, max = 9

T2= min{22-1×3, 9} = 6

T3= min{23-1×3, 9} = 9

T4= min{24-1×3, 9} = 9

……

36

99

T1

T2

T3

T4


During ON periods: Polling intervals are fixed and short. During OFF periods: Polling intervals are lengthened exponentially.

mPS can incorporate the use of piggybacking and bandwidth stealing defined in the standards.

Performance evaluationPerformance evaluation Performance evaluationPerformance evaluation

One BS, one RS, and multiple MSs




ConclusionsConclusionsConclusionsConclusions

They have developed a multi-hop polling service for the IEEE 802.16j MMR networks.

The mPS consumes considerably less bandwidth while still satisfying the delay constraints of most RT applications.

Their mPS mechanism enhances bandwidth efficiency significantly, especially when combined with BWReq aggregation.

Thank you

Documents

Chun Nie, Thanasis Korakis, and Shivendra Panwar Department of Electrical and Computer Engineering, Polytechnic University, Brooklyn A Multi-hop Polling