以流量為基礎之 ieee 802.16e 睡眠排程機制 a load-based power saving and scheduling...

以流量為基礎之以流量為基礎之 IEEE 802.16eIEEE 802.16e 睡眠排程機睡眠排程機制制

A Load-based Power Saving and A Load-based Power Saving and Scheduling Scheme in IEEE 802.16e Scheduling Scheme in IEEE 802.16e

國立暨南國際大學國立暨南國際大學資訊工程系 楊峻權資訊工程系 楊峻權

2010.05.042010.05.04

2

Outline Introduction

Wireless Standards, IEEE 802.16e/m Power Saving Techniques IEEE 802.16e/m Power Saving Class Related Work

Load-based Power Saving LBPS-Aggr, LBPS-Split, LBPS-Merge

Performance Evaluation Conclusion

3

Wireless Standards

802.15.1Bluetooth

802.15.3802.15.4Zigbee

Personal Area Network (PAN)

802.11Wi-Fi

Local Area Network (LAN)

802.16/WiMaxFixed Wireless MAN

Metropolitan Area Network (MAN)

802.16e/mNomadic

802.20Mobile

802.21Handoff

802.22WRAN

2, 2.5, 3GCellular

Wide Area Network (WAN)

4

IEEE 802.16 Standards (1)

Standard 802.16 802.16a 802.16-2004 802.16e

應用模式 固定式應用（取代寬頻設備） 移動式應用

應用方向 Last Mile & Backhaul Mobile Device

頻段 10~66 GHz 2~11 GHz 2~6 GHz

傳輸條件 LOS NLOS NLOS

傳輸速率 32~134 Mbps 75 Mbps 15 Mbps

調變技術 QPSK, 16QAM,

64QAM

QPSK, 16QAM, 64QAM

(採 256 Subcarrier OFD

M)

QPSK, 16QAM, 64QAM

(採 257 Subcarrier OFDM

)

移動性 固定性 固定性 移動性

傳輸距離 1~3 Miles 4~6 Miles (Max 30 Miles) 1~3 Miles

5

IEEE 802.16 Standards (2)

6

IEEE 802.16e

Newly developed broadband wireless communication technology

MSS is battery-powered An effective power-saving strategy

is necessary for extending the operation time

Periodically turn off the transceiver to save power (Sleep Mode)

7

IEEE 802.16e MAC protocol Frequency division duplex (FDD) mode and

time division duplex (TDD) mode Downlink: from the BS to MSSs

Point-to-multipoint broadband wireless access Uplink

Multiple MSSs share one slotted uplink channel via TDD on a demand basis for voice, data, and multimedia traffic

The BS handles bandwidth allocation by assigning uplink slots based on requests from MSSs

8

IEEE 802.16e Service classes

Unsolicited Grant Service (UGS) Real-Time Polling Service (rtPS) Non-Real-Time Polling Service (nrtP

s) Best Effort (BE)

IEEE 802.16e IEEE 802.16m (1Gbps, 4G)

9

IEEE 802.16m Service classes

Real-time constant bit-rate (e.g., VoIP without silence suppression) Extended real-time variable bit-rate (e.g., VoIP with silence suppression) Real-time variable bit-rate (e.g., MPEG video) Non-real time variable bit-rate (e.g., FTP, HTTP) Best effort (e.g., E-mail)

RT-CBR ERT-VR RT-VRNRT-VR

BE

Data generated interval

Periodic Periodic PeriodicDynami

cDynami

c

Packet size FixedFixed/

dynamicDynami

cDynami

cDynami

c

Delay sensitivity

High High High Middle Low

10

Power Saving Techniques (1) Application layer

Load partitioning (computation performed at BS)

Reduce # of transmissions for operations (e.g. via data compression)

Transport layer Reduce # of retransmissions

Network layer Power efficient routing through a multi-hop

network

11

Power Saving Techniques (2) Data link layer

Reduce # of packet errors at a receiving node

Automatic Repeat Request (ARQ) and Forward Error Correction (FEC)

MAC layer Sleep scheduling protocols Cycle the radio between its on and off

power states

Physical layer Proper hardware design techniques

12

IEEE 802.16e Power Saving Three types of Power Saving Class (PSC)

Type I: MSS doubles its next sleep period if no packets are sent or received

Type II: MSS repeats the sleeping and listening periods in a round-robin fashion

Type III: MSS sleeps for the predefined period and then returns to normal operation

13

IEEE 802.16e Type I PSC

14

IEEE 802.16e Type II PSC

15

IEEE 802.16e Type III PSC

16

IEEE 802.16m Type IV PSC

17

IEEE 802.16m PSC

18

Related Work (1) Performance analysis (mainly PSC Type I)

For downlink traffic by semi-Markov chain (IEEE Comm. Mag. 2005)

For downlink & uplink by Poisson traffic pattern (IEEE Comm. Mag. 2006)

Hyper-Erlang distributed inter-arrival time (IEEE WCNC 2007)

Optimal selection of PSC I and II (IEEE WCNC 2007)

19

Related Work (2)

Adaptive power saving mechanisms Adjusting the waiting time before enterin

g the sleep mode Adjusting the initial and final sleep windo

ws (IEEE Globecom 2006) Delay-based sleep scheduling Latest enhancements (IEEE Trans. VT 2009, 2

010)

20

Load-based Power Saving Weakness of PSC I and PSC II

Exponential increase or constant pattern Traffic modeling and Measurement

Poisson arrival process (uplink & downlink) MSS’s load sleep cycle length

Data accumulation threshold (1 time frame) BS responsible for sleep schedule

21

LBPS in light load

22

LBPS in heavy load

23

LBPS-Aggr Protocol

24

LBPS Mathematics (1)

25

LBPS Mathematics (2)

Data_TH = one time frame of data

Prob_TH = 0.8 in the simulation

26

Problem with LBPS-Aggr Unrealistic assumption of synchronize

d sleep cycle for all MSSs Low utilization of mini-slots in a time f

rame Two enhancements

LBPS-Split LBPS-Merge

27

LBPS-Split Protocol (1)

28

LBPS-Split Protocol (2)

29

Features of LBPS-Split

Dividing MSSs to separate groups All MSSs with the same length (K*) of t

he sleep cycle Is it possible to use different value of

K* for different MSS? LBPS-Merge Schedulability for different K*

30

LBPS-Merge Protocol (1)

2

31

LBPS-Merge Protocol (2)

32

Simulation Study

# of MSS (one BS) 10, 20, 40, 80

# of mini-slots in a time frame 160

Value of Prob_TH 0.8

Packet size 1 mini-slot

Simulation time 1*107 time frames

Type I initial sleep interval 20 time frames

Type I maximal sleep interval 29 time frames

Length of listening window 1 time frame

Load distribution among MSS Equal, 8:2, Random

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Performance Criteria

Power Saving Efficiency (PSE)

PSE = (K-1)/K

Access delay

K-1 time frames 1 time frame

K time frames

S A

S ASleep_window size Awake_window size

... ...

34

Power Saving Efficiency (1)

10 MSSs, Equal Load

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.95Total load

Pow

er S

avin

g E

ffic

ienc

y

LBPS-Split LBPS-Merge LBPS-Aggr Standard Type I

35

Power Saving Efficiency (2)

10 MSSs , 8:2 Load

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.95

Total load

Pow

er S

avin

g E

ffic

ienc

y

LBPS-Split LBPS-Merge LBPS-Aggr Standard Type I

36

Access Delay (1)10 MSSs, Equal Load

0

5

10

15

20

25

30

35

40

45

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.95Total load

Del

ay (

time

fram

e)

LBPS-Split LBPS-Merge LBPS-Aggr Standard Type I

37

Access Delay (2)10 MSSs, 8:2 Load

0

5

10

15

20

25

30

35

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.95Total load

Del

ay (

tim

e fr

ame)

LBPS-Split LBPS-Merge LBPS-Aggr Standard Type I

38

LBPS-Split: Impact of # MSS (1)

LBPS-Split, Equal Load

00.10.20.30.40.50.60.70.80.9

1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.95Total load

PS

E

10 MSSs 20 MSSs 40 MSSs 80 MSSs

39

LBPS-Split: Impact of # MSS (2)

LBPS-Split, 8:2 Load

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.95Total load

PS

E

10 MSSs 20 MSSs 40 MSSs 80 MSSs

40

LBPS-Merge: Impact of # MSS (1)

LBPS-Merge, Equal Load

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.95Total load

PSE

10 MSSs 20 MSSs 40 MSSs 80 0 MSSs

41

LBPS-Merge: Impact of # MSS (2)

LBPS-Merge, 8:2 Load

00.10.20.30.40.50.60.70.80.9

1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.95Total load

PSE

10 MSSs 20 MSSs 40 MSSs 80 MSSs

42

Impact of load distribution (1)

LBPS-Split, 10MSSs

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.95Total load

PS

E

Equal Load 8:2 Load Random

43

Impact of load distribution (2)

LBPS-Merge, 10MSSs

00.10.20.30.40.50.60.70.80.9

1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.95Total load

PS

E

Equal Load 8:2 Load Random

44

Conclusion & Future Work

Load-Based Power Saving Traffic Modeling & Measurement LBPS-Aggr, LBPS-Split, LBPS-Merge Better power saving efficiency

Future work Integrated real-time and non-real-time More general traffic modeling