Nsl seminar(2)

Wireless Embedded & Networking System Laboratory

Low-overhead Uplink Scheduling
Through Load Prediction for
WiMAX real-time services
W. Nie, H. Wang, N. Xiong2
IET Commun., 2011, Vol. 5, Iss. 8, pp. 1060–1067

Thomhert Suprapto Siadari
Dept. IT Convergence
Kumoh National Institute of Technology

February 3rd., 2012

 Introduction

 Problems & Solutions

 WiMAX Sample Frame

 WiMAX Service Classes

 Low-overhead Scheduling

 Simulation Results

 Conclusion & Future Works

DOC ID

 IEEE802.16

 WiMAX 300 trials worldwide

 Connection oriented

 PHY & MAC Layer

 Suffers problem of huge MAC overhead

 No scheduling Algorithm standard

DOC ID

Problems:

1. Large overhead uplink scheduling

2. Real-time services

3. Scheduling algorithm

Solutions/ Contributions:

1. Low-overhead uplink scheduling

2. Load prediction

DOC ID

 PMP (BS to MSs)

 Transmission: Downlink & Uplink

 TDD

DOC ID

WiMAX service classes:

 Unsolicited Grant Service (UGS)  fixed-size data packets

 Real-time polling service (rtPS)  generate variable-size data
packets periodically

 Non-real-time polling service (nrtPS)  bandwidth not on the
basis of fixed packet size

 Best Effort (BE)  efficient service (web surfing)

DOC ID

- Earlier Deadline First (EDF) scheduling

- Adaptive Bandwidth Scheduling

DOC ID

- Information Module

- Scheduling Database Module

- Service Assignment Module

f : frame size (ms), uplink and downlink subframe contains;

di : the maximum delay of connection i (ms);

qi(t) : the queue length of connection i at time t(bit);

si [t, t + f ]: the number of bits required to be transmitted for connection i in the time interval [t, t + f ];

ai[t, t + f ]: the number of bits arriving for connection i in the time interval [t, t + f ];

Ndi[t, t + f ]: the number of bits waiting in the queue for connection i, which will expire in the time interval [t, t + f ].

DOC ID

- Selects SSs based on delay requirement

- Suitable for real-time services

- Deadline to each packet

- Allocate bandwidth to SS based on earliest deadline

Information Module
 Firstly  delay requirement

rtPS connection input information module:

Output:

 Secondly  expiration time

DOC ID

Scheduling Database Module  serves as a database of information for all
connections

Service Assignment Module

- Determine uplink subframe allocation in terms of the number of bits per SS

DOC ID

Specific implementation steps:

Check BWrtps & Bufferi_deadline (bandwidth required by the deadline frame in cureent
time

If

Guarantee the bandwidth of deadline packets

Allocate more bandwidth to active SS

If

The bandwidth requirement will be scheduled:

DOC ID

C: the uplink channel capacity;

F: set of all SSs belonging to the rtPS class;

Bi: bandwidth allocated to connection i;

Dequeue i: remove packet P from the queue of
connection i;

amount(P,): retrieve the packets P from the
connection i. Convert the packets to number of
symbols according to the signal-to-interference
noise ratio [SINR(ji)] of connection i.

CreateIE(amount(P, ji)): create an IE for
connection i with

amount(P, ji) number of symbols. Then, IE is
added to the UL-MAP message.

Drop(rtPS): drop packets from the queues for all
connections.

DOC ID

- Modeling the Arrival Process

PDF:

CDF of inter-arrival time:

- Estimation of Time: predict the response time when BS
allocates the bandwidth to SS
- Tr = Reuest time

- Ti = Bandwidth response time

DOC ID

Adaptive time slots calculating:
To calculate expected bandwidth:

To calculate required time slots

Given buffer  calculate required time slot

Si(0,1)  smooth parameter  give ratio of the actual allocation bandwidth to
previous predictions and requirements

If ε > 1  calculated bandwidth is closer to predicted bandwidth

If ε < 1  calculated bandwidth is closer to requested bandwidth

So, use ω = 0.05 to adjust Si.

DOC ID

- Better performance than WFQ & WRR

- Sharply reduce MAP & MAC SDUs subheader overhead

- Improves system throughput

DOC ID

- Problem yg ada itu apa?

- Solusi dan kontribusi yang ditwarkan apa?

- Metodenya? LOH: EDF & Adaptive sched schem?

- EDF utk apa sebenarmya? Ad a 3 module disini? Information module? Sched database module? Service assignment module?
Specific implementation steps?

- Adaptive sched scheme: modeling Arrival process? estimation time? Adaptive time slots calculating?  apa tujuannya semua
ini?

- Simulasi  frame ultilisation, average throughput, average queuing delay, packet loss?  kenapa dalam real-time
communication harus pake ini? Alasannya?

- Dia pake perbandingan WFQ dan WRR? kenapa? Dan hasilnya lebih baik? Kenapa? Ada apa dengann WFQ dan WRR?

- Dia kan pake load prediction? Kalo WFQ dan WRR pake load prediction juga gimana?

DOC ID

Nsl seminar(2)

More Related Content

What's hot (20)

Similar to Nsl seminar(2) (20)

Recently uploaded (20)

Nsl seminar(2)

Editor's Notes