Quality of Service Scheduling for Broadband Wireless Access Systems Sih-Han Chen Department of Computer Science and Information Engineering National Taipei University of Technology

2006/11/212 Outline Overview IEEE IEEE MAC and QoS Proposed QoS strategy Simulation result Summary and Reference

2006/11/213 Wireless Technologies Bandwidth 1 Gbps 100 Mbps 10 Mbps 1 Mbps PANLANMANWAN <1m 10m 100m Up to 50Km Up to 80Km Bluetooth Wi-Fi a/g Wi-Fi b High Speed Wireless PAN Wi-MAX ( & e) 4G 3G 2.5G IEEE IEEE IEEE GPP PAN: Personal area networksMAN: Metropolitan area networks LAN: Local area networksWide area networks

2006/11/214 IEEE Operation Mode

2006/11/215 IEEE TDD frame structure

2006/11/216 DL-MAP and UL-MAP

2006/11/217 Downlink Subframe Broadcast

2006/11/218 Uplink Subframe

2006/11/219 Outline Overview IEEE IEEE MAC and QoS Proposed QoS strategy Simulation result Summary and Reference

2006/11/2110 IEEE Std MAC Protocol Layering

2006/11/2111 Service Specific Convergence Sublayer

2006/11/2112 MAC Convergence Sublayer Functions: Classification processing of higher-layer PDUs Delivery to proper MAC SAP Receives CS PDUs from peer Two sublayers specified: ATM convergence sublayer Packet convergence sublayer Service Specific Convergence Sublayer (CS)

2006/11/2113 ATM Convergence Sublayer ATM cells mapped to MAC frames Differentiates Virtual Path switched / Virtual Channel switched ATM connections Assigns channel ID (CID) Can perform Payload Header Suppression (PHS)

2006/11/2114 Packet Convergence Sublayer Used for all packet-based protocols, such as IPv4, IPv6, Ethernet, and VLAN Similar functions as ATM convergence sublayer, including PHS

2006/11/2115 MAC Common Part Sublayer Defines multiple-access mechanism Functions ： connection establishment connection maintenance Call admission control bandwidth request bandwidth allocation MAC Common Part Sublayer (MPC)

2006/11/2116 Security Sublayer Two component protocols Encapsulation protocol for data encryption Privacy key management (PKM) describes how the BS distributes keys to client SS Security Sublayer

2006/11/2117 Media Acces Control (MAC) Connection orienteded Service Flow(SF) Connection ID (CID) Channel access: UL-MAP Defines uplink channel access Defines uplink data burst profiles DL-MAP Defines downlink data burst profiles UL-MAP and DL-MAP are both transmitted in the beginning of each downlink subframe (FDD and TDD).

2006/11/2118 Bandwidth Request SSs may request bandwidth in 3 ways: Use the ”contention request opportunities” interval upon being polled by the BS (unicast, multicast or broadcast poll) Send a standalone MAC message called ”BW request” in an already granted slot Piggyback a BW request message on a data packet

2006/11/2119 Bandwidth Allocation BS grants/allocates bandwidth in one of two modes Grant Per Subscriber Station (GPSS) Grant Per Connection (GPC) Decision based on requested BW, QoS parameters and available resources Grants are realized through the UL-MAP

2006/11/2120 Service Classes Unsolicited Grant Services (UGS): Constant Bit Rate (CBR) services, T1/E1 emulation, and Voice Over IP (VoIP) Real-Time Polling Services (rtPS): real-time services variable size data packets MPEG video or VoIP with silence suppression. Non-Real-Time Polling Services (nrtPS): Used for delay tolerant traffic requiring some minimum data rate FTP Best Effort Services (BE) : Used for streams with no rate guarantees. WEB, HTTP

2006/11/2121 QoS mechanisms Classification Mapping from MAC SDU fields (e.g destination IP address or TOS field to CID and SFID Call admission Control Scheduling Downlink scheduling module Uplink scheduling module No algorithms defined in standard

2006/11/2122 IEEE QoS Architecture

2006/11/2123 Call Admission Control in IEEE Admission control To ensure required QoS is guaranteed while admit a new connection Assessment of admission connection Usually use traffic descriptor and effective bandwidth But… Traffic descriptors may not reflect the real traffic Traffic descriptors is very simple (peak rate, avg. rate, etc…) Users may overestimate their requirements QoS is uneasy to guarantee

2006/11/2124 Outline Overview IEEE IEEE MAC and QoS Proposed QoS strategy Simulation result Summary and Reference

2006/11/2125 Hierarchical and Distributed QoS Architecture

2006/11/2126 Scheduling Algorithm at BS Define two types of queue Type ( I) queue Type (I I) queue Admission Control Scheduling Algorithm

2006/11/2127 At BS Scheduling for Type I queue Type I queue Use for UGS Dedicated request opportunities for rtps and nrtps Guarantee grants to be scheduled without interrupt First-in First-out (FIFO) ， is employed

2006/11/2128 At BS Scheduling for Type II queue Type II queue Use for rtPS ， nrtPS ， and BE To Guarantee Minimum bandwidth for each service flow Fairness to distributing excess bandwidth To propose a fair queuing algorithm

2006/11/2129 Type II Queue Bandwidth Allocation Grant Per Connection (GPC) BiMIN ： the minimum reserved bandwidth for connection i BRi ： bandwidth currently demanded by the connection

2006/11/2130 Call Admission Control (CAC) The sum of minimum reserved bandwidth for all the connection should not exceed the available bandwidth B

2006/11/2131 Fairness to distributing excess bandwidth

2006/11/2132 A Extended Issue It also can be wasted when ： Certain of connections don’t need so much bandwidth Solution ： It allows the empty connection queue to contribute its unused portion to the next round of excess bandwidth allocation

2006/11/2133 Scheduling Algorithm at SS WHY ? Due to the large Round Trip Delay (RTD) Possible collision occurred in the uplink channel So … BS has only limited or even outdated information about each uplink connection

2006/11/2134 At SS Priority of scheduling service

2006/11/2135 At SS UGS Queue Scheduling Properties Critical delay Critical delay jitter Firstly guarantee the bandwidth

2006/11/2136 At SS rpPS Queue Scheduling Properties Should meet tight delay bound Each packet of rtPS should be mark a deline t ： arrival time tolerated delay ： Maximum Latency for each service flow Schedule base on the deadline stamp

2006/11/2137 At SS nrtPS Queue Scheduling Properties Target at maintaining throughput Each packed with a virtual time stamp When a new packer arrives in ， the virtual time must be calculated at first

2006/11/2138 Virtual Time Stamp

2006/11/2139 At SS BE Queue Scheduling Properties There is no QoS guarantee required A simple FIFO mechanisms is applied

2006/11/2140 Outline Overview IEEE IEEE MAC and QoS Proposed QoS strategy Simulation result Summary and Reference

2006/11/2141 Simulation Environment Used NS2 PMP MAC operation TDD-OFDM One BS and 20 SSs SS UGSrtPSnrtPSBE First 1111 Second 1111 Third 2 Fourth 2 Fifth 2 Other v

2006/11/2142 PHY layer parameters

2006/11/2143 The End-to-End Delay

2006/11/2144 The End-to-End Delay (for UGS_1)

2006/11/2145 Compare Delay of rtPS_1 service

2006/11/2146 For rtPS Different number of background SS

2006/11/2147 Throughput of nrtPS

2006/11/2148 Outline Overview IEEE IEEE MAC and QoS Proposed QoS strategy Simulation result Summary and Reference

2006/11/2149 Summary Introduced a hierarchical distributed QoS At BS Guarantee the minimum bandwidth Fairness distributing excess bandwidth At SS Flexible QoS support four service flow Reduce the delay of real-time application Guarantee the throughput of non-real-time application

2006/11/2150 References [1] Sun, J.; Yanling Yao; Hongfei Zhu, “ Quality of Service Scheduling for Broadband Wireless Access Systems ” Vehicular Technology Conference, VTC 2006-Spring. IEEE 63 rd Volume 3, 2006 Page(s): [2] Jayaparvathy, R.; Sureshkumar, G.; Kanakasabapathy, P., “ Performance evaluation of scheduling schemes for fixed broadband wireless access systems ”, th IEEE International Conference on Volume 2, Nov Page(s):6 pp. [3] IEEE Standard (2004), "IEEE Standard For Local and Metropolitan Area Networks - Part 16:Air Interface for Fixed Broadband Wireless Access Systems".

2006/11/2151 OFDM Frame Structure with TDD: PMP mode

2006/11/2152 Service Specific Convergence Sublayer The service specific convergence sublayer (CS) provides any transformation or mapping of external network data, received through the CS service access point (SAP) Object : classifying external network service data units (SDU) and associating them to the proper service flow identified by the connection identifier (CID)

2006/11/2153

2006/11/2154 IEEE Scope : Specifies the air interface, MAC (Medium Access Control), PHY(Physical layer) Purpose : Enable rapid worldwide deployment of cost-effective broadband wireless access products Facilitate competition in broadband access by providing alternatives to wireline broadband access Main advantage : Fast deployment, dynamic sharing of radio resources and low cost

2006/11/2155 IEEE Deployment