Channel Quality Dependent Rate-limited Scheduling Algorithm for IEEE 802.16 Wireless Networks

Cuicui Zhao1, Jinlong Hu2, Jihua Zhou2, Jinglin Shi2, Eryk Dutkiewicz3

1Graduate University of Chinese Academy of Sciences, Beijing, China2Institute of Computing Technology, Chinese Academy of Sciences, China3Wireless Technologies Laboratory, University of Wollonggong

IEEE CMC 2009

Outline

Introduction Related Works Goal

Channel quality dependent rate-limited Scheduling Basic scheduler Extened scheduler Order changing in CD-RL

Simulation Results Conclusions

Introduction

In IEEE 802.16, five data delivery services are defined unsolicited grant service (UGS) real-time variable-rate (RT-VR) extended real-time variable-rate (ERT-VR) non-real-time variable-rate (NRT-VR) best effort (BE)

The standard does not recommend any particular scheme in detail

Background

IEEE 802.16 service classes

n

Introduction

Related Works Deficit round-robin (DRR) [8]

To allow handling variable packet sizes in a fair manner

Low complexity Channel-quality dependent earliest deadline due

(CDEDD) [12] guarantees the targeted delay bounds and ensures that

the number of packets dropped is fairly distributed among users

High complexity

Introduction

Problem How to satisfy the basic QoS requirements, such as

the minimum reserved traffic rate and the maximum latency

How to allocate the rest bandwidth

Goal To satisfy the basic QoS requirements To enhance throughput Low complexity Based on fairness (BE is exclude)

Basic schedulerExtended schedulerOrder changing in CD-RL

Channel quality dependent rate-limited Scheduling ( CD-RL )

Scheduler structure

Basic scheduler

In priority class Fk, service flows are served in descending order of starvation(i,n), which is defined as how long service flow i hasn’t been satisfied with minimum reserved traffic rate till the nth frame

Basic scheduler

Tstart(i) is introduced as a timestamp to record the first time service flow i receives data from upper layer

Quantity of data that have been sent from Tstart(i) to the nth frame

Sending data in the nth frame

Basic scheduler

minimum reserved traffic rate

minimum data quantity

the time in frame nmaximum data quantity

Basic scheduler

Real-time scheduler

real-time data expiring in next frame

Data transmission size for service flow i with s slots remaining in frame n

real data quantity of service flow i

maximum data transmission size for service flow i in frame n with s slots remaining

Basic scheduler

Non-real-time scheduler

real data quantity of service flow i

maximum data transmission size for service flow i in frame n with s slots remaining

Extended scheduler

priorities from highest to lowest are ERT-VR, RT-VR, NRT-VR, and BE.

To allocates bandwidth to service flows of class Fk in descending order of c(i,n)

Order changing in CD-RL

Q1,k

Q2,k

Order changing in CD-RL

Q1,k

Q2,k

Order changing in CD-RL

Q1,k

Q2,k

Starvation flag

Order changing in CD-RL

Q1,k

Q2,k

Starvation flag

Full flag

Full flag： satisfied with maximum sustained traffic rates

Sorting by channel quality

Half-full flag

Order changing in CD-RL

Q1,k

Q2,k

Starvation flag

Full flag

Full flag： satisfied with maximum sustained traffic rates

Half-full flag

Simulation Results

number of slot S for data transmission is assumed to be 300 per frame

Frame duration is 5 ms

Simulation Results

Throughput of RT-VR service

Simulation Results

Fairness of RT-VR service

Simulation Results

User satisfied rate of RT-VR service

Simulation Results

Average Packet Delay of RT-VR servic

Conclusions

CD-RL provides service in class priority with guaranteed data rate while taking throughput enhancement into accoun

CD-RL can be implemented with low complexity

Simulation results show that CD-RL has good performances in fairness, minimum reserved traffic rate and average packet delay

Thank you