2008/4/101 A DAPTIVE P OWER A LLOCATION AND C ALL A DMISSION C ONTROL IN M ULTISERVICE W IMAX A CCESS N ETWORKS IEEE Wireless Communications February 2007 Radio Resource Management And Protocol Engineering For IEEE Reporter 陳宗涵

2008/4/102 Outline 1. Abstract 2. Introduction 3. Wimax Downlink APA Optimization 4. Deploying CAC In Wimax Access Networks 5. The Cooperation Between APA and CAC 6. Conclusions

2008/4/103 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 the promise of WiMAX will be materialized still depends on its revenue rate to telecom operators and its service quality to the subscribers

2008/4/104 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 standardized wireless technology  10Km  single-channel data rate of up to 75 Mb/s on both the uplink and downlink.  use multiple WiMAX channels for a single transmission to reach a bandwidth of up to 350 Mb/s.

2008/4/105 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.

2008/4/106 Introduction

2008/4/107 Introduction

2008/4/108 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

2008/4/109 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)

2008/4/1010 Introduction  This article addresses two resource management mechanisms in WiMAX access networks  Adaptive power allocation (APA)  Call admission control (CAC)

2008/4/1011 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.

2008/4/1012 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

2008/4/1013 Wimax Downlink APA Optimization  arriving downlink traffic load in subscriber k ' s local network  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.

2008/4/1014 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 bad- urban (BU) delay profile [Principles of Mobile Communication]

2008/4/1015 Wimax Downlink APA Optimization

2008/4/1016 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.

2008/4/1017 Deploying CAC In Wimax Access Networks  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.  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

2008/4/1018 Deploying CAC In Wimax Access Networks

2008/4/1019 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.

2008/4/1020 The Cooperation Between APA and CAC

2008/4/1021 Conclusion  Since the current standardization activities of IEEE 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

2008/4/1022 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.