chun nie, thanasis korakis, and shivendra panwar department of electrical and computer engineering,...
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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.
IntroductionIntroduction IntroductionIntroduction
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
IntroductionIntroduction IntroductionIntroduction
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.
IntroductionIntroduction IntroductionIntroduction
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
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
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
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
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
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
An example of mPS mechanism:mechanism:
MS1
BS RS
MS2
ON Period ON PeriodOFF Period
RS
MS1
BWReq
T1, min=3
…
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
An example of mPS mechanism:mechanism:
MS1
BS RS
MS2
ON Period ON PeriodOFF Period
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
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
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
Performance evaluationPerformance evaluation Performance evaluationPerformance evaluation
Performance evaluationPerformance evaluation Performance evaluationPerformance evaluation
Performance evaluationPerformance evaluation Performance evaluationPerformance evaluation
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
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