impact on service quality by coexisting wireless...

Impact on Service Quality by Coexisting Wireless Technology

(Interference modeling method & Performance evaluation using OPNET)

2012. 7. 31.김재현

Wireless Internet aNd Network Engineering Research Lab. School of Electrical and Computer Engineering

Ajou University, Korea

Technical Consultant @Samsung Electronics

연구실소개

구성원

• 지도교수: 김재현

• 박사과정 8명, 석사과정 2명, 인턴 2명

지도교수 주요약력

• 1993~1996, 한양대학교 전자계산학과 공학박사

• 1996~1998, UCLA 전기과 Post-Doctoral Fellow• 1998~2003, Bell Labs, Lucent, NJ. Member of Technical Staff• 2003~현재 아주대학교 전자공학부 정교수

주요연구분야

• IEEE 802.11(15/16/20) MAC Protocol and QoS Research • Wireless Cross-Layer System Design (App. to PHY)• Network Performance Modeling and Analysis (Queuing and OPNET)

연구 실적

저널 학회 총계

해외 19 76 95국내 48 85 133총계 67 161 228

논문상

49

13

특허

72431

2

Outline

Performance Degradation by Coexisting Technology Time Scale Evaluation Frequency Scale Evaluation Interference Modeling

OPNET wireless transmission overview OPNET radio modules OPNET pipeline stages

Indoor network simulation in OPNET Reformation points External signal measurement tool

SITL (System-In-The-Loop) & WINNER Lab Works

3

Performance Degradation by Coexisting Technology

4

Introduction

Many devices applied to different wireless technology are coexisted in Home networkWLAN, Bluetooth, and Zigbee device based on IEEE 802.11, IEEE

802.15.1, and IEEE 802.15.4, respectively

These devices use 2.4GHz ISM band Each device is not only a victim,

but also an interferer Uplink and Downlink can

be asymmetry To evaluate the performance,

we need to analyze the interference by each wireless devices

5

Time Scale Evaluation

To evaluate the interference, we first model collision time Collision time : overlapped time by each devices

Need to understand MAC Frame Structure to model the collision time Frame duration, Channel access mechanism, Hopping pattern, Coding

scheme

6

NACK Busy detected by CCAWLAN

Bluetooth

ZigbeePacket loss

Reduce channel efficiency

Time Scale Evaluation: MAC Frame Structure(1)

IEEE 802.15.1 (Bluetooth) Essential characteristics Frequency Hopping for per slot duration Can be used multiple slot (odd number of slots) TDMA GFSK(Gaussian Frequency Shift Keying)

7

s

s

참고문헌 : Institute of Electrical and Electronics Engineers. IEEE Std 802.15.1-2005, Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Wireless Personal Area Networks (WPANs), 14 Jun. 2005.

Time Scale Evaluation:MAC Frame Structure(2)

IEEE 802.15.4 (Zigbee) Essential characteristics CSMA/CA TDMA O-QPSK(Offset-Quadrature Phase Shift Keying)

8

15ms * 2n where 0 n 14

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Slot

Battery life extension

Contention Access Period Contention Free Period

GTS 3 GTS 2 GTS 1

참고문헌 : Institute of Electrical and Electronics Engineers. IEEE Std 802.15.4-2006, Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low-Rate Wireless Personal Area Networks (WPANs), 8 September 2006.


IEEE 802.11 (WiFi) Essential characteristics CSMA/CA

• Carrier sense : Physical – CCA(Clear Channel Assess), Virtual – RTS/CTS CC(Convolutional Coding) & LDPC(Low Density Parity Check) QAM(Quadrature Amplitude Modulation)

Basic channel access mechanism: DCF(Distributed Coordinated Function)

9

DIFS Contention Window

Slot time

Busy Medium

Defer Access

Backoff-Window Next Frame

Backoff slot reduced when channel is idle

SIFS

PIFSDIFSSense channel during DIFS

참고문헌 : Institute of Electrical and Electronics Engineers. IEEE Std 802.11-2007, Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, 12 Jun. 2007.


IEEE 802.11e TXOP(Transmission Opportunity) limit Two different channel access mechanism : EDCA(Enhanced Distributed

Channel Access) & HCCA(HCF Controlled Channel Access)

IEEE 802.11n Frame Aggregation

• A-MSDU• A-MPDU

Block ACK

10

ACK RTS

CTS

SIFS SIFS

PIFSAIFS[AC]=DIFS

SIFS

AIFS[AC]

AIFS[AC]

high priority AC

medium priority AC

low priority AC

defer access Contention Windows (counted in slots, 9us)

count down as long as medium is idle, Back off when medium gets bust again

CW=rand[1,CWi+1]

MACProce-ssing

F1

F2

F3

MAC headerF1F2F3

MACProce-ssing

F1

F2

F3

MAC headerF1

F2

F3

MAC header

MAC header

A-MSDU A-MPDU

참고문헌 : 1. IEEE Std 802.11e, Wireless LAN Medium Access Control(MAC) and Physical Layer Specifications:Amendment 8: Medium Access Control(MAC) Quality of Service Enhancements, 2005.2. IEEE P802.11n/D3.00, Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Amendment 4: Enhancements for Higher Throughput

Collision Time Modeling

겹치는시간만큼간섭을발생시킴 Frame duration IEEE 802.15.4(15msec) > IEEE 802.11(3msec under 20MHz) > IEEE 802.15.1(0.625*(2n-1) msec)

Example of collision time IEEE 802.11 under IEEE 802.15.4 Interference

PER can be derived from the BER and

11

0W W

W ZC

Z Z Z W

W Z W Z

L x x LL x U

Tx U U x U LL U L x T

1 1b

CTbPER P

bCT

/bC C bT T T

: Bit duration of the IEEE 802.11b

참고 문헌 : S. Y. Shin, H. S. Park, S. H. Choi, and W. H. Kwon, “Packet Error Rate Analysis of ZigBee Under WLAN and Bluetooth Interferences,” IEEE Trans. On Wireless Communication, vol. 6, no. 8, Aug. 2007

OPNET Modeling

Collision time may be implemented in Stage 8 of OPNET Pipeline stage

Current OPNET Only including Free-space path-loss model

Need to model the channel model of indoor environment Shadow fading Fast fading Indoor channel characteristics

12

Frequency Scale Evaluation

Interference can occur by adjacent channel device, as well as co-channel devices The performance can be more affected by SIR(Signal to Interference

Ratio) than SNR(Signal to Noise Ratio)

13참고문헌 : Texas Instruments, “The Effects of Adjacent Channel Rejection and Adjacent

Channel Interference on 802.11 WLAN Performance,” White Paper, Nov. 2003

Interference Pattern

RF emission pattern is regulated by FCC

Adjacent channel interference

14

Frequency Allocation

동일한주파수를사용하는경우뿐만아니라인접한주파수를사용하는경우에도간섭을발생시킬수있음

IEEE 802.15.4

IEEE 802.11

IEEE 802.15.1 Frequency Hopping

15

In-band Interference

Out-band Interference

Frequency Allocation

IEEE 802.15.4 vs. IEEE 802.11 Full Overlap(20MHz) In-band Interference

IEEE 802.11(13ch) vs. IEEE 802.15.4(23,24,25,26ch) Partial Overlap Out-band Interference

IEEE 802.11(7ch) vs. IEEE 802.15.4(16, 21ch)

IEEE 802.15.1 vs. IEEE 802.11 Difficult to modeling due to FH

Occur both In-band interference and out-band interference

Collision

16

/I S offsetf

/ /

2

10 2

0

sin10log

0

I S offset I S S offset

offset c offsetS offset

f f dB

c f T G fJ f

G

참고 문헌: Ivan Howitt, “WLAN and WPAN Coexistence in UL Band,” IEEE Trans. On Veh. Techn., vol. 50, no . 4, Jul, 2001

OPNET Modeling

In-band interference Implemented in OPNET

Out-band interference Hard to implement in OPNET Out-band interference is varied to frequency offset Link level simulation according to frequency offset using MATLAB Add interference in PHY layer, not pipeline stage, to link level simulation

results

17

Interference Reduction Mechanism

IEEE 802.15.1 Frequency Hopping Power control

IEEE 802.11 Adjacent channel rejection Super-het receiver Dynamic Frequency Selection (IEEE 802.11ac) Dynamic Bandwidth Channel Access (IEEE 802.11n/ac)

IEEE 802.15.4 Channel scan before network formsMesh networking and path sharing Network layer frequency agility

18


Bluetooth and WLAN 1. Bluetooth power control

2. Super-het receiver

19


Dynamic Frequency Selection in IEEE 802.11ac Detect the presence of a radar system (DFS required channels) If the level of the radar is above a certain threshold, move to another

channel.

20

DFS required

DFS required


Dynamic Bandwidth Channel Access Use secondary channels, if secondary channels are available Different CCA(Clear Channel Assessment) sensitivity -82dBm for primary channel (802.11ac) -62dBm for secondary channel (802.11ac)

21

Station 2 (11a/n)

Station 3 (11a/n)

Station 1 (11ac)

참고문헌: Minyoung Park; , "IEEE 802.11ac: Dynamic Bandwidth Channel Access," Communications (ICC), 2011 IEEE International Conference on , vol., no., pp.1-5, 5-9 June 2011


ZigBeeMesh networking and path sharing

Network layer frequency agility Included in the ZigBee PRO stack specification Interference detected by the Zig-Bee Coordinatorthe network manager may

direct the network to leave the current operating channel and move to another, clearer one

22

관련결과물

Interference by other technology device can be modeled to PBNJ(Partial Band Noise Jammer)

전 대역(Wss) 중 일부 대역에 재밍이 존재하는 경우 재밍 분포 비율

Satellite Communication System 위성통신 시스템 구조

• FH-SS, 변복조 방식, 채널코딩, 채널모델

성능평가• 재밍 환경(PBNJ, WPBJ)에서 변복조 방식(M-ary FSK, SDPSK, GMSK), 채널코

딩(Convolution coding)에 따른 위성통신 시스템에 관한 BER 성능분석

23

SSW

JW

JN

[Noise jammer frequency distribution]

/J ssW W

참고 문헌 : 1. K. C. Go, W. C. Park, K. K. Kim and J. H. Kim, "Bit Error Rate Performance of SFH-Modulation Scheme System under Jamming," in Proc. IGNSS 2011, Sydney, Australia, 15-17. Nov. 2011.2. 박우철, 고광춘, 김재현, 김기근 "위성통신시스템의 BER 성능 분석을 활용한 항재밍 기법," 한국통신학회논문지, 35권 10호, 2010년 10월.3. 박우철, 고광춘, 김재현, 김기근 "Jamming 환경에서 SFH 변조 방식에 따른 위성 통신 시스템의 BER 성능분석," 한국전자파학회논문지, 21권 10호, pp. 1161-1168, 2010년 10월.

관련결과물

System Structure

Channel coding: Convolution codeModulation: SFH/NC-MFSK, SFH/SDPSK, SFH/GMSK무선 채널 모델: 재밍 분포에 의한 신호 감쇄 고려

24

Information source

ChannelCoding

Modulation XMT

Information sink

Channel Decoding

Demodulation

RCV

AWGN channel

Jamming

PN sequence Generator

Frequency Synthesizer

PN sequence Generator

Frequency Synthesizer

관련결과물

재밍모델 The fractional ratio: Jammer power spectral density : In the WPBJ scenario, bit error probability is maximized in

SFH/NC-MFSK BER under PBNJ

BER of SFH/NC-MFSK under WPBJ

25

/J SSW W

/J SSN J W

Jb NE /

1 2 1

1 (( )/ )/( 1)

1

2 12 112 1 1

K

b J

KKl lK E N l

b Kl

P ell

where K=log2(M) (Number of bits per symbol)

*

2 , / 2/1, / 2

b Jb J

b J

E NE N

E N

1

( / 2 )

, / 2/

1 , / 22

b J

b Jb J

bE N

b J

e E NE NP

e E N

* 1, // ( / ), /

b J

b J b J

E NE N E N

1 2 1

1 (( ) / ) / ( 1)

1

2 12 11 , /2 1 1

/ ( / ), /

K

b J

KKl lK E N l

b JKlb

b J b J

e E NP ll

E N E N

SFH/NC-BFSK SFH/NC-MFSK(M > 2)

관련결과물

Convolution coded 시뮬레이션파라미터 SFH/MFSK under PBNJ

SFH/SDPSK under PBNJ

SFH/GMSK under PBNJ

26

관련결과물

성능분석결과 Collision ratio에 따른 성능 분석 가능채널 모델 적용 가능정확한 coding gain 분석 가능 BER table을 이용하여 PER 계산 가능

27<BFSK> <SDPSK> <GMSK>

관련결과물

Bluetooth vs. WiFi Prof. Ivan Howitt of University of Wisconsin-Milwaukee Propose the analytic interference model of WiFi by Bluetooth Effective Interference Area

28

22 / 10

210

/

2 10 log, exp

10 logI S

eff s s

I S BT AP

n eA d d

n e

dB

참고 문헌: 1. Ivan Howitt, “WLAN and WPAN Coexistence in UL Band,” IEEE Trans. On Veh. Techn., vol. 50, no . 4, Jul, 20012. Ivan Howitt, “Bluetooth Performance in the Presence of 802.11b WLAN,” IEEE Trans. On Veh. Techn., vol. 51, no. 6, Nov. 20023. Ivan Howitt, et. al. “Empirical Study for IEEE 802.11 and Bluetooth Interoperability,” in Proc VTC Spring 2001

관련결과물

Adjacent channel interference model according to frequency offset

Derive collision probability according to bluetooth load,activity, density

29

/ /802.11

/ 0offset C BT C b

offset I S BT

AP S offset

f f f

f

J f

관련결과물

Danfoss(Z-Wave Alliance)

30참고문헌 : Z-Wave Alliance. WLAN Interference to IEEE 802.15.4. White Paper. March 2007.

관련결과물

Residential Tests Individual house Lost packets were due to propagation issues

Laboratory Tests Various WiFi traffic patterns Assess the impact on Zigbee of varing

parameters Although ZigBee packets are delivered

successfully, they can experiencean increased latency due to a higher number of retransmissions

31

Test platform sequence diagram

Duty cycle Packet loss(20mW)

Packet loss(30mW)

Packet loss(50mW)

10% 0 0 0

20% 0 0 0

40% 0 4 9

참고문헌 : Schneider Electric, “ZigBee – WiFi Coexistence,” White Paper and Test Report

관련결과물

Zigbee vs. WiFi Schneider Electric

32

Schneider Daintree Danfoss Ember Freescale UCE Lorrach

Conclusion • Impact on packet deliverydepending on distance and frequency offset

• Impact on latency but not on packet loss

• 802.11g better

• Impact on packet delivery depending on distance and frequency

• Impact on latency but not on packet loss

• 802.11g better

• Impact on packet delivery depending on distance and frequency offset

• Impact on packet delivery depending on distance and frequency offset

Recommendations

• Distance Wifi-Zigbee >2m

• Frequencyoffset>30MHz

• No-works well in all cases

• Use 802.11g rather than b

• Distance WiFi-Zigbee >1m

• Frequency offset > 22MHz

• Maximizefrequency offset

• Use 802.11g rather than b

• Frequency offset >25MHz

• Frequency offset > 10MHz

ZigBee Chipset TI OC2420 ? Multiple vendors Ember EM2420, EM250 Frescale MC1319x TI OC2420

ZigBee Stack PHY, PHY+MAC PHY+MAC, APS Retry PHY+MAC PHY+MAC, NWK Retry PHY+MAC PHY+MAC

ZigBee Power 0 dBm ? 0 dBm, 3 dBm, 10dBm 0-4 dBm 0 dBm 0 dBm

WiFi Hardware Acksys ? ? Atheros, Broadcom ? DrayTek, Agere

WiFi Mode IEEE 802.11b IEEE 802.11b/g IEEE 802.11b IEEE 802.11b/g IEEE 802.11b IEEE 802.11b

WiFi Power Level 20 dBm ? 20 dBm 14-18 dBm 15 dBm 20 dBm

WiFi Traffic FTP FTP, Audo streaming UDP with 20-80 duty cycle FTP, Audo streaming UDP with 10-90 duty cycle FTP

Communication Modes

LOS, Single-hop LOS, Single-hop NLOS, Single-hop LOS, Single-hop, Multi-hop LOS, Single-hop LOS, Single-hop

ZigBee Channel All 18 17,20,24 17 11, 16, 21, 26 18

WiFi Channel 7 6 6 6 All 6

Frequency Offset 2MHz 3MHz 2MHz, 13MHz, 33MHz 2 MHz 12MHz 3MHz

Distance 0.5-4m 5cm 0.5, 1, 5, 14, 22m Multiples 30cm 1.5m

관련결과물

Wireless Coexistence between IEEE 802.11- and IEEE 802.15.4-Based Networks: A Survey

33참고문헌 : D. Yang, Y. Xu, and M. Gidlund, “Wireless coexistence between IEEE 802.11 and IEEE 802.15.4-based networks: A survey,” Int. J. Distrib. Sensor Netw., vol. 2011, 2011, Art. no. 912152.

Scenario Reference Environment Conclusions

Bad case: 802.11 interferes with 802.15.4

[9] (1) Channel offset 3MHz(2) 802.11 with highest utilization rate(3) Transmit power is about 30 times(4) Interference distance is 1.5m

(1) Packet error rate is more than 90%(2) There is interference even using

nonoverlapping channels

Bad case: 802.15.4 interferes with 802.11

[10] (1) Channel offset 2MHz, CCA1(2) Duty cycle of 802.15.4 is 15.36%(3) 802.11/15.4 power is 15/0dBm(4) Interference distance is short

(1) Throughput loss can be up to 30%. For even larger IEEE 802.15.4 duty cycles, the loss goes up to 60%

Difference between uplinkand downlink

[11] (1) Interference distance is 1m(2) Place the interferer near the source

(1) Zigbee interference has stronger effect on the IEEE 802.11 uplink than the downlink

Difference between sender and receiver

[12] (1) Channel offset 2MHz(2) CCA1 with threshold -76dBm(3) Interference distance < 2m

(1) When the IEEE 802.11 source is located far away from the IEEE 802.15.4, interference comes out as channel errors

(2) When the IEEE 802.11 source is located closely to the IEEE 802.15.4, interference comes out as the CSMA/CA mechanism

OPNET Wireless Transmission OverviewReferences

− “Modeling Custom Wireless Effects—Introduction”, OPNETWORK 2011− OPNET modeler product documentation

34

OPNET Wireless Transmission

Wireless Transmission Component Transmitter Module Execute transmission action

according to its definedconfiguration

Packet Represents a group of bits

transmitted wirelessly It has frequency and time

allocation information Receiver Module Executes reception actions

according to its definedconfiguration

35

OPNET Radio Module

Radio Modules in a Node Model

36

OPNET Transmitter/Receiver

Transmitter/Receiver Attributes Channels Data rate Packet format Bandwidth Min frequency Spreading code Power Bit capacity (Tx only) Packet capacity (Tx only)

Modulation Associate the

modulation table Pipeline stages Different sets

for Tx and Rx37

OPNET Radio Pipeline

Radio Pipeline Model Attributes “Pipeline” used to denote sequence of calculations Each stage performs a different calculation Each stage consist of “C” of “C++” procedures

You can create new models or modify existed models

38

TDAs

Transmission Data Attributes (TDAs) Scope Special packet storage areas

• Part of every packet Carry numerical values

• Integer, Object ID, floating point, or pointer Carry information about transmission

• Distance, Start/End of Tx/Rx time, BW, Channel index, Code for spreading… Initialized by kernel at start of transmission Readable during a packet’s life Writable only in pipeline

Purpose Convey link information

• From kernel to pipeline stage• From pipeline stage to kernel• Between pipeline stages

39

OPNET Pipeline Stages

Radio Pipeline Stages (Transmitter Side)

40


Radio Pipeline Stages (Receiver Side)

41


Stage 0: Receiver Group Purpose This provides a model acceleration technique

• Reduce computation to the minimum required set Filter out ineligible receiver channels

• Simulation runtime improvements Possible uses

• Disjoint frequency bands• Excessive physical separation• Antenna nulls

Invocation Once at start of simulation, or Programmatically with kernel procedures

Arguments Transmitter and receiver channel object IDs

Requirements Return value of OPC_TRUE or OPC_FALSE

Results Defines destination channel set for each transmitting channel

• By Distance, Pathloss threshold, Channel match criteria...

42


Stage 1: Transmission Delay Purpose Computes time required to transmit packet

Invocation First dynamic stage Start of packet transmission Single invocation for all destination channels

Argument Packet pointer

Requirements Sets TX_DELAY TDA

Results Kernel schedules end-of-transmission event Signals start of transmission of next packet in transmitter queue

43


Stage 2: Closure Purpose Determines whether signal can reach destination

• Based on ray-tracing line-of-sight model• Check terrain modeling module (TMM)

Allows dynamic enabling/disabling of links Invocation Once for each destination channel Called immediately after stage 1– no intervening events


Requirements Sets PROP_CLOSURE TDA

Results If occlusion (obstruction) occurs, no further stages are called for the packet

44


Stage 3: Channel Match Purpose Classifies the transmission Typically based on frequency, bandwidth, data

rate, spreading code, modulation, etc. Invocation Once for each destination channel satisfying

stage 2 Called immediately after stage 2 – no

intervening events Argument Packet pointer

Requirements Sets MATCH_STATUS TDA

Results Valid, noise, or ignore If ignore, no further stages are called for the

packet

45

Ignore

Noise

Valid


Stage 4: Transmitter Antenna Gain Purpose Computes transmitter antenna gain in the

direction of the receiver Invocation Once for each destination channel satisfying

stages 2 and 3 Called immediately after stage 3 – no


Requirements Sets TX_GAIN TDA

Results Typically used by stage 7 for received power

computation46


Stage 5: Propagation Delay Purpose Calculates signal propagation time from

transmitter to receiver Usually dependent on distance and propagation

velocity Invocation Once for each destination channel Called immediately after stage 4 – no intervening

events Argument Packet pointer

Requirements Sets START_PROPDEL and END_PROPDEL TDAs

Results Kernel schedules

• Start of reception event• End of reception event

47


Stage 6: Receiver Antenna Gain Purpose Computes receiver antenna gain in the

direction of the transmitter Invocation Once for each destination channel First stage after start of reception event


Requirements Sets RX_GAIN TDA

Results Typically used by stage 7 for receiver power

computation

48


Stage 7: Received Power Purpose

Computes signal power level at receiver Typically based on transmitter power and

frequency, distance, and antenna gains Computed only for valid and noise packets

Results Kernel uses value to record receiver power

channel statistic Signal Lock

First valid packet arrival at destination channel• Signal lock obtained

Subsequent valid packet arrivals• Match status changed to noise

First valid packet completes arrival• Signal lock released

WLAN Detect Jammer packet

49


Stage 8: Interference Noise Purpose Accounts for concurrent transmissions Computes the effect of interference noise on valid packets

Invocation Only if packet collision occurs

Requirements Sets NOISE_ACCUM TDA Sets NUM_COLLS TDA

Arguments Packet pointers of arriving packet and packet already being received

Results Accumulates noise of interfering packets Noise from packet completing reception is subtracted by kernel Typically used in stage 10 for signal-to-noise ratio computations

50


Stage 8: Interference Noise Logical segmentation performed by kernel based packet’s overlap

determines changes in interference noise levels Frequency Time

SNR computation performed later by stage 10 for each segment Upon packet completion, kernel subtracts noise power of completing

packet

51


Stage 9: Background Noise Purpose Represents effects of all background noise

sources Typically includes

• Thermal or galactic noise• Emissions from nearby electronic devices• Other un-modeled radio transmissions

Invocation Called immediately after stage 8 – no


Requirements Sets BKGNOISE TDA

Results Typically used by stage 10 in signal-to-noise

computation

52


Stage 10: Signal-to-Noise Ratio Purpose Computes the current average SNR Typically based on received power and noise

Invocation (only for valid packets) Operates on valid packets – those in valid list Does not require collision for invocation “Start of packet segments”


Requirements Sets SNR TDA

Results Used by kernel to update receiver channel statistics Used by later stages

53


Stage 11: Bit Error Rate Purpose Derives the probability of bit errors Computed for each packet segment – constant SNR Value typically obtained from modulation curve

Invocation Operates on valid packets – those in valid list Does not require collision for invocation “End of packet segments”


Requirements Sets BER TDA

Results Used by the kernel to record BER statistic Typically used in stage 12 for allocating errors

54


Stage 12: Error Allocation Purpose Estimates bit errors for each packet segment

• Does not perform bit-by-bit error computations• Cannot retain bit-error location

Invocation Called immediately after stage 11 – no intervening

events Requirements Sets bit-error accumulation in NUM_ERRORS TDA Sets empirical bit error rate in ACTUAL_BER TDA


Results Kernel maintains a bit accumulator – NUM_ERRORS

TDA Kernel updates BER statistic – ACTUAL_BER TDA Typically used in stage 13 for error correction

55

0 2 4 6 8 100

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

kP

k

p=0.1p=0.2p=0.3p=0.9


Stage 13: Error Correction Purpose Determines acceptability of the entire arriving

packet• Obtains threshold from ECC_TRESH TDA

Invocation Once for each valid packet Called immediately after stage 12 – no intervening

events Requirements Sets PK_ACCEPT TDA


Results Rejected

• Destroyed by Kernel Accepted

• Forwarded on output stream

56

ECC threshold: acceptable error percentage of packet

Indoor Network Simulation in OPNET

57

Reformation points

“Interference Noise” 추가요소고려 Near-far effect Adjacent channel interference Need link level simulation results (ex. MATLAB)

“Bit error rate” modulation curve 추가필요 OPNET 제공 Modulation curve BPSK, QPSK, 16-QAM, 64-QAM

IEEE 802.11ac MCS index 256-QAM

새로운 TDA 정보필요송수신기의 실내외 위치 여부 정보 현재 TDA에는 구분할 수 있는 정보 없음

58

Reformation points

“Received Power” 채널모델변경필요 Indoor Channel model 필요 Pathloss, Shadowing, Multipath, Wall-loss… 통계적 실내환경 채널 모델 사용

• 가능한 채널 모델링» 건물 벽/층간 감쇠, 사무실내 통계적 Shadowing, Multipath

• 장점» 환경 변화에 따른 실시간 결과 도출 가능

• 단점» 실내 위치 및 구조물에 따른 Multi-path의 제한적인 반영

신호 측정 시뮬레이터 결과 활용• 신호측정 전문 시뮬레이터 사용. 예) VolcanoLab.• 가능한 채널 모델링

» 건물 벽/층간 감쇠, 실제 구조물에 의한 Shadowing, Multipath• 장점

» 실내 위치 및 구조물까지 고려된 비교적 정확한 신호측정가능• 단점

» 송수신기 위치 변화/노드수/트래픽양에 따른 다수의 Raw-data 필요

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External signal measurement tool

VolcanoLAB (SIRADEL Co.) Deterministic propagation models Support multiple technologies (GSM, CDMA, UMTS, WiMAX, LTE) Suitable to all environment from rural to dense urban & indoorMultiple paths modeling

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<Multipath modeling> <Indoor penetration> <Multi-floor Indoor>

(Outdoor) (1st Floor)

(13th Floor) (26th Floor)

참고문헌: SIRADEL, “Volcano Models in VolcanoLAB”, Dec. 2009

SITL(System-In-The-Loop) & WINNER Lab Works

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OPNET SITL (System In The Loop)

구성 OPNET 시뮬레이터 본체, 송신 단말, 수신 단말

동작 송신 단말의 실시간 트래픽 전송시뮬레이터 네트워크 통과수신 단말

의 실시간 트래픽 재생

효과 실제 응용프로그램의 트래픽으로 시뮬레이터 네트워크 성능평가 가능

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공공안전망에적합한이동성관리및 QoS 보장방안연구- 삼성전자

연구목표공공 안전 망에서 이동성 관리 및 정책기반 QoS 보장 방안 연구공공 안전 망에서 이동성 관리 및 정책기반 QoS 보장 성능평가 통합 시

뮬레이터 개발

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• MeR (Mesh Router)- MN 무선 통신 인터페이스 (WiBro)- MR 무선 통신 인터페이스 (미정)- MeR 무선 통신 인터페이스 (미정)

• MR (Mobile Router)- MN 무선 통신 인터페이스 (WiBro)- MR 무선 통신 인터페이스 (미정)- MeR 무선 통신 인터페이스 (미정)

•MN (Mobile Node)- MR, MeR 무선 통신 인터페이스(WiBro)

• 공공 안전 망 고려사항- 백본링크 단절 시 연결성- MN/MR의 이동성

+ 통신환경의 잦은 변화+ 망 토폴로지 변화

공공안전망성능평가시뮬레이터개발- 삼성전자

MN MR MeR

WiBro interface

WiBro interface

Backhaul Backhaul Backhaul

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공공안전망을위한 WiBro interface / Backhaul module개발

공공안전망성능평가시뮬레이터개발- 삼성전자 셀경계지역에서의 VoIP Service에대해서패킷손실이 QoS에심각한영향을미침 ARQ with ertPS (ARQ_BLOCKLIFE_TIME 0.06): Non ARQ with UGS에비해 MOS 2 향상 QoS 향상에관한 trade off: 재전송패킷에의한자원소모 (Mission-Critical 트래픽: ARQ with ertPS)

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3.6

라인접속장비용큐잉알고리즘개발-삼성탈레스

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End-to-End QoS Architecture End-to-End Service

종단간 QoS 보장 (최종 목적) IP QoS

백본망 및 라우터와 라인접속장비(Router Control Unit, RCU) 간 QoS 보장

Inter-RCU QoS RCU간 QoS 보장 (핵심연구목표)

라인접속장비용큐잉알고리즘개발-삼성탈레스

제안하는 ABM의성능분석:G.729A(1)

MOS (Mean Opinion Score)기존 버퍼관리 기술 MOS 3.0을 기준으로 할 경우 VoIP capacity는 약 9.2Mbps(600 VoIP)

제안하는 ABM 기술 MOS 3.0을 기준으로 VoIP capacity는 약 10.8Mbps(720 VoIP)

67400 450 500 550 600 650 700 750 800

0.5

1

1.5

2

2.5

3

3.5

4MOS vs Number of users(G.729A)

number of users

MO

S

Tail DropHead DropProposed

Good

Bad

Increased capacity

≒ 6Mbps ≒ 8.3Mbps ≒ 9.2Mbps≒ 10.8Mbps

사용자중심이동성제공기술-한국방송통신전파진흥원

사용자 QoE 기반링크관리기술 다중세션을이용한서비스/이동성

제공기술연구

망구조 서로 다른 MME에 연결된 LTE 기지국 WiFi가 이종망으로 존재

시나리오 사용자 단말은 WiFi 우선 연결로 설정 이동할 WiFi는 hotspot지역으로 Cell

load가 많아 새로운 단말 접속시Access delay 증가

결과 단말이 이동으로 접속하는 망에 따라

서비스 품질이 다르게 나타남 WiFi 접속시 서비스 끊김 LTE로 이동시 서비스 재게

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LTE

WiFi

LTE

사용자중심이동성제공기술-한국방송통신전파진흥원 이종망간핸드오버성능평가 환경설정 LTE 사용중 WiFi가 감지되면 WiFi로 서비스 경로 변경 SCM(service continuity manager) 미사용시 WiFi 신호 기준으로 경로 선택 수행

결과 SCM 사용시 QoE 를 기준으로 핸드오버 수행

• 이종망간 이동으로 빠른 QoE 회복

SCM 미사용시 신호 기준으로 핸드오버 수행• 핸드오버를 지원하지 않는 망 사용시 세션 끊긴 후 새로운 망 연결

ConnectedLTE eNB

ConnectedWiFi AP

MOS

<SCM 미사용> <SCM 사용>

사용자중심이동성제공기술-한국방송통신전파진흥원

무선랜간섭영향성능평가 RSSI 기반 AP 선택 시 간섭으로 인해 성능 열화예측된 SINR 기반 AP 선택 시 성능 개선

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위성통신네트워크시뮬레이션- 정보통신산업진흥원

항재밍기법성능분성

시뮬레이션시나리오 총 5개의 노드가 위성을 이용하여 데이

터 수신중 4개 : OPNET 내부

• FTP이용 파일 전송

1개 : 외부 연결을 이용한 시험• Ping• 동영상 전송

파일 서버 위치 : 경기도 남부 외부 연결 서버 위치 : 경북지역 네트워크 지연 : 50ms 유선-위성 네트워크 연결점 : 대전지역 위성 : 동경 113도(현 무궁화 5호 위치)

결과 재밍 시 서비스 끊김 항 재밍 기법 도입시 끊김없는 통신 가

능

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Real-time Jamming Control Panel(External program made by WINNER LAB)

<위성네트워크>

Tx

Rx

Jammer

SatelliteSystem

Conclusion

Performance Degradation by Coexisting Technology In time domain/ frequency domain Need indoor interference modeling

Indoor network simulation OPNET pipeline stages are suitable for dynamic traffic simulation But, Need some reformations of OPNET pipeline stages Indoor channel model Interference model Modulation curve model

External signal simulation tool can be implemented VolcanoLAB Support more detailed signal measurement result However, Does not support dynamic network environment

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참고문헌

[1] IEEE Std 802.15.1-2005, Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Wireless Personal Area Networks (WPANs), 14 Jun. 2005.[2] IEEE Std 802.15.4-2006, Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low-Rate Wireless Personal Area Networks (WPANs), 8 September 2006.[3] IEEE Std 802.11-2007, Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, 12 Jun. 2007[4] IEEE Std 802.11e, Wireless LAN Medium Access Control(MAC) and Physical Layer Specifications: Amendment 8: Medium Access Control(MAC) Quality of Service Enhancements, 2005.[5] IEEE P802.11n/D3.00, Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Amendment 4: Enhancements for Higher Throughput[6] S. Y. Shin, H. S. Park, S. H. Choi, and W. H. Kwon, “Packet Error Rate Analysis of ZigBee Under WLAN and Bluetooth Interferences,” IEEE Trans. On Wireless Communication, vol. 6, no. 8, Aug. 2007[7] Texas Instruments, “The Effects of Adjacent Channel Rejection and Adjacent Channel Interference on 802.11 WLAN Performance,” White Paper, Nov. 2003[8]Minyoung Park; , "IEEE 802.11ac: Dynamic Bandwidth Channel Access," Communications (ICC), 2011 IEEE International Conference on , vol., no., pp.1-5, 5-9 June 2011[9] K. C. Go, W. C. Park, K. K. Kim and J. H. Kim, "Bit Error Rate Performance of SFH-Modulation Scheme System under Jamming," in Proc. IGNSS 2011, Sydney, Australia, 15-17. Nov. 2011.[10] 박우철, 고광춘, 김재현, 김기근 "위성통신시스템의 BER 성능 분석을 활용한 항재밍 기법," 한국통신학회논문지, 35권10호, 2010년 10월.[11] 박우철, 고광춘, 김재현, 김기근 "Jamming 환경에서 SFH 변조 방식에 따른 위성 통신 시스템의 BER 성능 분석," 한국전자파학회논문지, 21권 10호, pp. 1161-1168, 2010년 10월.[12] Ivan Howitt, “WLAN and WPAN Coexistence in UL Band,” IEEE Trans. On Veh. Techn., vol. 50, no . 4, Jul, 2001[13] Ivan Howitt, “Bluetooth Performance in the Presence of 802.11b WLAN,” IEEE Trans. On Veh. Techn., vol. 51, no. 6, Nov. 2002[14] Ivan Howitt, et. al. “Empirical Study for IEEE 802.11 and Bluetooth Interoperability,” in Proc VTC Spring 2001[15] Schneider Electric, “ZigBee – WiFi Coexistence,” White Paper and Test Report[16] S. Y. Shin, H. S. Park, S. H. Choi, and W. H. Kwon, “Packet Error Rate Analysis of ZigBee Under WLAN and Bluetooth Interferences,” IEEE Trans. On Wireless Communication, vol. 6, no. 8, Aug. 2007[17] D. Yang, Y. Xu, andM. Gidlund, “Wireless coexistence between IEEE 802.11 and IEEE 802.15.4-based networks: A survey,” Int. J. Distrib. Sensor Netw., vol. 2011, 2011, Art. no. 912152[18]“Modeling Custom Wireless Effects—Introduction”, OPNETWORK 2011[19] OPNET product documentation[20] SIRADEL, “Volcano Models in VolcanoLAB”, Dec. 2009

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Thank you !

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Q & A

impact on service quality by coexisting wireless...

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