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ADAPTIVE POWER ALLOCATION AND

CALL ADMISSION CONTROL IN

MULTISERVICE WIMAX ACCESS NETWORKS

IEEE Wireless Communications February 2007Radio Resource Management And Protocol

Engineering For IEEE 802.16

Reporter 陳宗涵

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Outline

1. Abstract2. Introduction3. Wimax Downlink APA Optimization4. Deploying CAC In Wimax Access Networks5. The Cooperation Between APA and CAC6. Conclusions

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Abstract

From a technical viewpoint, WiMAX is a feasible alternative to the wired internet access solutions such as cable modem and DSL

From the commercial viewpoint, whether th

e promise of WiMAX will be materialized still depends on its revenue rate to telecom operators and its service quality to the subscribers

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Introduction

The choice of broadband Internet access T1 、 ADSL 、 CABLE

However, these wired infrastructures can be considerably more expensive and time consuming to deploy than wireless ones

WiMAX, an IEEE 802.16 standardized wireless technology

10Km single-channel data rate of up to 75 Mb/s on both the u

plink and downlink. use multiple WiMAX channels for a single transmission t

o reach a bandwidth of up to 350 Mb/s.

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Introduction

WiMAX technology supports both mesh and point-to-multipoint (PMP) networks.

mesh network is usually used for constructing wide-area wireless backhaul network

PMP network aims at providing the last-mile access to a broadband ISP.

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Introduction

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Introduction

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Introduction

Transmission OFDM (orthogonal frequency division

multiplexing) OFDMA (orthogonal frequency division

multiple access)

Duplex FDD (Frequency Division Duplex) TDD (Time Division Duplex) TDD is more flexible

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Introduction

As one of the most expected features, WiMAX is supposed to have the capability of accommodating a variety of traffics, including data transfer, voice, and video.

WiMAX Forum define Unsolicited Grant Service (UGS) Real-Time Polling Service (rtPS) Non-Real-Time Polling Service (nrtPS) Best Effort (BE)

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Introduction

This article addresses two resource management mechanisms in WiMAX access networks

Adaptive power allocation (APA)

Call admission control (CAC)

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Wimax Downlink APA Optimization

The WiMAX uplink and downlink transmission can be optimized by APA, which allows the transmitter to grant different power levels to different subcarriers according to the channel state information from the physical layer

The service providers usually expect a power allocation scheme that produces optimal revenue.

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Wimax Downlink APA Optimization

To investigate the APA revenue of a certain scheme, we define the revenue rate of each type of service as the revenue generated by a bandwidth unit. We let rerUGS, rerrtPS, rernrtPS, and rerBE be the revenue rates of the following

Unsolicited Grant Service Real-Time Polling Service Non-Real-Time Polling Service Best-Effort Service

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Wimax Downlink APA Optimization

arriving downlink traffic load in subscriber k's local net

work

traffic load can generate potential revenue in subscriber k's local network

revenue-to-bandwidth ratio of the kth subscriber

The optimal revenue-criterion-based APA allocate more power resource to the subcarriers that belong to the subscriber of high revenue-to-bandwidth ratio.

DKTL

KRD

DKK

DK TLRDRBR /

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Wimax Downlink APA Optimization

This consideration leads to fairness-constrained optimal revenue criterion

Simulation

OFDMA 32 subscribers BS-SS distances → 2 to 10 km Power level → MQAM

• M-ary quadrature amplitude modulation is 80% In our simulation, the channel is assumed to have a ba

d-urban (BU) delay profile [Principles of Mobile Communication]

Davgth

DK trFtr

thF

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Wimax Downlink APA Optimization

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Deploying CAC In Wimax Access Networks

To handle a multiservice WiMAX access network, it is very important to employ the CAC mechanism.

CAC is a crucial step for the provision of QoS guaranteed service, because it can prevent the system capacity from being overused.

We suppose a CAC manager is placed in a WiMAX base station.

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Deploying CAC In Wimax Access Networks

1. When an application in subscriber k's local network initiates a connection to the Internet, it sends connection request to the CAC manager with upstream bandwidth requirement bU and downstream bandwidth requirement bD.

2. the CAC manager employs uplink CAC policy and downlink CAC policy to make admission tests on the uplink and downlink separately, and only the connection request passing both admission tests can be accepted eventually

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Deploying CAC In Wimax Access Networks

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Deploying CAC In Wimax Access Networks

From the perspective of service provider, the admission control policy that produces optimal revenue is desired.

From the perspective of WiMAX subscribers, the admission control policy of optimal utility is expected, since it can produce the maximum access bandwidth.

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The Cooperation Between APA and CAC

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Conclusion

Since the current standardization activities of IEEE 802.16 leave service providers a chance to have their own selections in these two technical aspects, distinct designing criteria that follows can be chosen.

From the perspective of service providers, optimal revenue is the major concern of both APA and CAC design

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Conclusion

From the perspective of subscribers, fairness is the requirement of APA design, while optimal utility is the requirement of CAC design.

To successfully deploy a commercial WiMAX system, we have to take into account the demands of both service providers and subscribers.