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Full Duplex MAC

2014. 06. 16.

김재현

자료조사 : 천혜림, 김진기

Wireless Internet aNd Network Engineering Research Lab.

School of Electrical and Computer Engineering

Ajou University, Korea

차세대 무선랜 기술 워크샵

Contents

무선랜표준화동향

IEEE 802.11ax 표준화로드맵

MAC Challenges

Key Technology

제안된 Full Duplex MAC

향후연구이슈및관련연구

2



TGmAccumulated Maintenance

TGcBridge Operation

TGiSecurity System

TGtTesting & Comparison

WLAN (PHY&MAC)

IEEE 802.11

TGa5GHz OFDM

TGb2.4GHz CCK & DSSS

TGg2.4GHz OFDM/CCK/DSSS

TGnHigh Throughput: MIMO

TGacVHT at <6GHz

TGadVHT at 60GHz

TGaxHEW

TGeProtocol for QoS

TGrReal Time Constraints

TGwProtected Manage. Frames

TGzDirect Link Setup

TGaaVideo Transport Streams

TGaeQoS for Manage. Frames

TGdNew Regulatory Domain

TGhDFS/TPC for 5GHz

TGdJapanese 4.9/5GHz Band

TGpVehicular Environment

TGyUSA 3.65~3.7GHz Band

TGafTVWS Band

TGah< 1G Band (Smart GRID)

TGfInter-AP Protocol

TGkRadio Resource Measure

TGsMesh networking

TGuInterworking with External

TGvNetwork Management

TGaiFast Initial Authentication

VHT: Very High Throughput

HEW: High Efficiency WLAN


무선랜표준특징

4

802.11b 802.11a 802.11g 802.11n 802.11ac 802.11ax

Standard

Approved

Jul.

1999Jul. 1999 Jun. 2003 Oct. 2009 Jan. 2014 Mar. 2014 ~

Maximum Data

Rate11 Mbps 54 Mbps 54 Mbps 600 Mbps 4.8 Gbps -

ModulationDSSS or

CCKOFDM

DSSS / CCK

/ OFDM

DSSS / CCK

/ OFDM

OFDM,BPSK / QPSK /

256 QAM

-

RF Band 2.4 GHz 5 GHz 2.4 GHz 2.4 / 5 GHz 5 GHz 2.4 & 5GHz

Number of

Spatial Streams1 1 1 4 8 > 8

Channel Width 20 MHz 20 MHz 20 MHz 20, 40 MHz20, 40, 80,

160 MHz-

Features CDMA OFDM, 5GHz ComboMIMO, MAC

improvement,

MU-MIMO

CH. bonding

Full Duplex,

OFDMA

* CCK : Complementary Code Keying

* DSSS : Direct Sequence Spread Spectrum

* OFDM : Orthogonal Frequency Division Multiplexing


CSMA/CA

Carrier Sense Multiple Access with Collision Avoidance

5

RTS

DATA

ACK

전송지연

CTS

ACK

STA 2로부터 hidden terminal

TA 1으로부터 CTS받은후 NAV Set

DATA DATA

ACK

STA 2

STA 1

STA 3

STA 4

STA 5

DIF

S

DIF

SD

IFS

SIF

S

SIF

S

SIF

S

SIF

S

SIF

S

SIF

S

DIF

S

Random

backoff=2

Random

backoff=10Randombackoff=6

Randombackoff=8

Time

STA 2 패킷전송감지로전송시도지연 Backoff slot=2

RTS수신후 NAV Set

STA1STA2 STA5


New components in IEEE 802.11n

PHY Enhancements, applicable to both 2.4GHz and 5GHz

The new PHY supports OFDM modulation with additional coding

methods, preambles, multiple streams and beam-forming

Multiple Input Multiple Output (MIMO) Radio Technology With

Spatial Multiplexing

High throughput PHY – 40 MHz channels – Two adjacent 20 MHz

channels are combined to create a single 40 MHz channel.

MAC Enhancements

Two MAC aggregation methods are supported to efficiently pack

smaller packets into a single MPDU

Block Acknowledgement – A performance optimization in which an

IEEE 802.11 ACK frame need not follow every unicast frame and

combined acknowledgements may be sent at a later point in time.

6

RTS

CTS

A-MPDU

BACK


New components in IEEE 802.11ac

5GHz 대역사용

더넓은대역폭지원

필수 80 MHz, 선택사항 160 MHz 및 80+80 MHz bandwidth

Static/Dynamic Bandwidth Operation 등을 포함한 향상된 RTS/CTS

프로토콜 사용

더높은 modulation 지원

802.11ac에서선택사항으로 256QAM이 도입

더많은 spatial stream 지원

802.11n에서 4개까지 지원했지만 802.11ac에서는 8개까지 지원

Downlink MU-MIMO 지원

최대 4개의 station에 대한 동시 전송을 지원

7[1] 이재승, 정민 호, 이석규, “802.11ac 무선랜 기술,” 한국통신학회지 (정보와통신) 제30권 제6호, pp.13-19 2013. 5

IEEE 802.11ax 표준화로드맵

목표

Improving spectrum efficiency and area throughput

Improving real world performance in indoor and outdoor

deployments

in the presence of interfering sources, dense heterogeneous networks

in moderate to heavy user loaded APs

8[2] Status of IEEE 802.11 HEW Study Group, http://www.ieee802.org/11/Reports/hew_update.htm

<IEEE 802.11ax 표준화 로드맵>

2013 2014 2015 2016 2017 2018

2013.03 2014.03 2017.07 2018.03

HEW

Initial SB(Sponsor Ballot)

표준화

High Efficiency WLAN Study Group (HEW SG)

<SG Document>- PAR (Project Authorization Request)- CSD (Criteria for Standards Development)

HEW SG 및 802.11ax

IEEE 802.11ax

[3] 조한규, LG전자 차세대 통신 연구소 “HIGH EFFICIENCY WLAN – 802.11AX ,” 제3회 WLAN 최신기술 워크숍, 4월, 2014년

MAC Challenges: Dense WLAN (1/3)

Dense WLAN environment

9[4] M.Y. Park, Intel Corporation, IEEE 11-13/0505r0, “MAC Efficiency Analysis for HEW SG,” May 2013

AP

STA

<Dense STAs> <Dense AP & STAs>

MAC Challenges: Dense WLAN (1/3)


10* 2014년 6월 11일 아주대학교 원천관 3층 측정

<2.4 GHz : 18 APs> <5 GHz : only 2 APs>

Performance anomaly & backward compatibility

CSMA/CA 기반으로 모든 station이 채널을 사용할 확률이 같음

전송속도가 느린 Legacy device가 가장 오랫동안 채널 사용

2013년 6월 일본의 Shinagawa St. 측정 결과 50%가 802.11b 패킷

전체 네트워크 성능 저하

Solution

Time limitation for low rate frames improve aggregate throughput in a BSS

More chance for AP to Tx

11

10sec

2sec

1sec

STA-A

STA-B

STA-C

LegacyDevice

STA-A802.11a

STA-B802.11ac

STA-C802.11ax

[5] A. Kishida, M. Iwabuchi, Y. Inoue, Y. Asai, Y, Takatori, T. Shintaku, T. Sakata and A. Yamada, NTT & NTT DOCOMO, IEEE 11-13/0801r1,

“Issues of Low-Rate Transmission,” July 2013

[7] K. Yunoki and Y. Misawa, KD야, IEEE 11-13/1349r0, “Access Control Enhancement,” November 2013

[6] K. Yunoki and Y. Misawa, KDDI, IEEE 11-13/1073r1, “Access Control Enhancement,” September 2013

MAC Challenges: 성능/호환성 (2/3)

MAC Challenges: Wider Bandwidth (3/3)

Wider bandwidth

2.4GHz 대역과 5GHz 대역 활용

새롭게 활용할 대역

12

1 5 9 13

2.4GHz 2.4835GHz 5.15GHz

5.35GHz5.47GHz 5.825GHz

144

140

136

132

128

124

120

11

611

2108

104

100

165

161

157

153

149

64

60

56

52

48

44

40

36IEEE channel #

20 MHz

40 MHz

80 MHz

160 MHz

UNII-1 UNII-2 UNII-2 UNII-3

5250

MHz

5350

MHz

5470

MHz

5725

MHz

NEW

96

92

88

84

80

76

72

68

169

173

177

181

5825

MHz

5925

MHz

NEW

Currently available channels New channels : 현재 활주로유도 radar등에서사용

[8] Y. Seok, J. Kim, G. Park, S. Kim, H. Cho, W. Lee, J. Chun, J. Choi, and D. Lim, LG Electronics, IEEE 11-13/0539r0, “Efficient Frequency

Spectrum Utilization,” May 2013

국내사용불가

Wider bandwidth 활용

Wider bandwidth(channel bonding) 사용시 문제점

Bandwidth를 모두 활용하지 못함

13[9] S. Kim, G. Park, J. Kim, K. Ryu and H. Cho, LG Electronics, IEEE 11-13/1058r0, “Efficient Wider Bandwidth Operation,” September 2013

MAC Challenges: Wider Bandwidth (3/3)

DATAACK

InterferenceSecondary40

Primary

Secondary20

이 interference로 Secondary 40 사용 불가

사용불가

ACKAIFS+BO

PIFS

20MHz 20MHz 20MHz 20MHz 20MHz 20MHz 20MHz 20MHz

Secondary40primary secondary

Secondary80

40MHz

80MHz

160MHz

Key Technology : Massive MIMO

Massive MIMO

A system that uses antenna array with dozens of antennas, which

could simultaneously serve tens of terminals in the same time-fre

quency resource

Advantages

Increased capacity

Improved energy efficiency

Reduced interference

14[10] Z. Wen, B. Li, Z. Luo, D. Chen, S. Wang and W. Xu, BUPT & CATR, IEEE 802.11-13/1046r2, “Discussion on Massive MIMO for HEW,”

September 2013

<Massive MIMO>

16 RF chains

Key Technology : Full Duplex

Full Duplex

On the same time and frequency resource

Up to 2x throughput improvement

Referred as Simultaneous Transmit and Receive (STR)

15[11] R. Taori, W. Kuo, K. Josiam, H. Shao, H. Kang and S. Chang, Samsung Research America & Samsung Electronics, IEEE 11-13/1122r1,

“Considerations for In-Band Simultaneous Transmit and Receive (STR) feature in HEW,” Sept. 2013

OO

O

O

<Full Duplex>

OX

OX

<Half Duplex>

Key Technology : OFDMA

OFDMA

Alleviating high dense condition by

Concurrent channel access from multiple users

Increase flexibility of channel utilization

Compatibility with other enhancing technologies, e.g. frequency

reuse

16[12] J. Choi, W. lee, J. Chun, D. Lim and H. Cho, LG Electronics, IEEE 11-13/1382r0, “Discussion on OFDMA in HEW,” November 2013

<OFDM vs OFDMA>

OFDMA = OFDM + FDMA

Time domain

Fre

quency

dom

ain

User 1 User 2 User 3

Time domain

Fre

quency

dom

ain

User 1

User 2 User 3

OFDM allocates users in time

domain only

OFDMA allocates users in time

and frequency domain only

제안된 Full Duplex MAC (1/8)

ContraFlow (Microsoft UK: 2009, UIUC,USC,2011)

Problem

Contention resolution

• In fig. asymmetric dual links, since B is already transmitting, existing carrier-

sense collision avoidance does not work any more, and node A has no way

of knowing if node D has also tried to transmit to B

Efficiency

• A classical CSMA/CA algorithm will give equal access priority to all nodes,

hence there is a substantial probability that a non-efficient dual link will be

scheduled and the spatial reuse will be low

Fairness

• In fig. 3-link network, link 2 (C,D) will have a smaller transmission probability

than the other links because of the DCF

17[13] N. Singh, D. Gunawardena, A. Proutiere, B. Radunović, H. V. Balan and P. Key, “Efficient and Fair MAC for Wireless Networks with

Self-interference Cancellation,” in Proc. WiOpt 2011, May 2011

Sender #1

A

Receiver #2

B

Receiver #1

A

B C

D

Sender #1

Receiver #1 Receiver #2

<Symmetric dual link><Asymmetric dual links>

B

A

D

C

F

E

<3-link network with fairness issues>


ContraFlow

Dual links access control

Primary transmission and second transmission

• Only the primary receiver is allowed to initiate the secondary transmission

Packet and ACK transmissions on dual-links

• Order of ACKs

» Primary receiver sends ACK when FD transmission is finished

» After primary receiver sending ACK, secondary receiver sends it’s ACK as

soon as it senses the channel idle

• The primary sender and receiver transmit a busy tone during the first MAC

ACK and before the end of the primary transmission

18

PACKET TX TO C

PACKET TX TO B

DIFS

Node A

Node B

2 1 0

B/TONE

t=0 tend

time

Node C

ACK1

PACKET RCD FROM A ACK2

ACK2

PACKET RCD FROM B ACK1

SIGNAL RX FROM B ACK1 time

Node A

Node B

PACKET TX TO B

PCK TX TO C ACK1B TONE

PACKET RX FROM A

<Successful dual link transmissions> <A short packet is protected with a busy tone>

A

B C

D

Sender #1

Receiver #1 Receiver #2


ContraFlow

Dual links access control

Second receiver selection

• To limit secondary collisions

• By the weighted list SA, where the

weight of each possible secondary

receiver, represents the proportion of

successfully secondary transmissions in

the past using dual-link

Distributed scheduler

The algorithm increases the transmission probability of links that are

not served, which will improve fairness( similar to Proportional Fair)

Node 𝑛 access probability P𝑛 𝑡 = max𝑙∈𝑂𝑛

p𝑙 𝑡 𝐿𝑙[𝑡]

p𝑙 𝑡 + 1 = p𝑙 𝑡 + 𝜖 × (𝐼 p𝑙 𝑡 − 𝐷 p𝑙 𝑡 , 𝑆𝑙 𝑡 )

19

A B

C

E

D

SA weight

A 1.00

C 0.00

D 0.90

E 0.80

𝐷 p𝑙 𝑡 , 𝑆𝑙 𝑡 ↑, p𝑙 𝑡 + 1 ↓, P𝑛 𝑡 ↓

: received service ↑, pressure indicator ↓, access probability↓

<An example a weighted list of secondary receivers at node B>

* 𝑂𝑛 : a set of out-going links

* p𝑙 𝑡 : pressure indicator

* 𝐿𝑙[𝑡] : Packet transmission duration

(in slots) at the HoL in the link 𝑙 buffer

* 𝐼 p𝑙 𝑡 , 𝐷 p𝑙 𝑡 , 𝑆𝑙 𝑡 : pressure

indicator upper bound


ContraFlow

Performance (Simulation based)

ContraFlow has a higher total throughput, up to 30% to 50% over the

plain DCF, but also over the DCF+IC

20


Real-time full duplex MAC (Stanford, UT Austin, OSU) using

WARP(Wireless Open-Access Research Platform from Rice Univ.)

Problem

The primary and secondary packets may have different lengths and

relying solely on data packets does not completely protect from hidden

terminals

Full duplex packet exchange

If a node receives a primary transmission and does not have a

corresponding secondary packet to send, it sends the busytone

immediately after decoding the header of the primary packet

21[14] M. Jain, J. I. Choi, T. Kim, D. Bharadia, S. Seth, K. Srinivasan, P. Levis, S. Katti and P. Sinha, “Practical, real-time, full duplex wireless,”

in Proc. MobiCom 2011, Sept. 2011

<Performance limited by Implementation issues >

Throughput (Mbps) Fairness

(JFI)Up Down

Half Duplex 5.18 2.36 0.845

Full Duplex 5.97 4.99 0.977

Primary TX

Secondary TX

Hidden Terminals Suppressed

Node 1 Access Point

Hdr Primary TXNode 1 ACK

Hdr Secondary TX Busytone ACKAP

Node 2

Carrier Free

Carrier Busy

Simultaneous ACKs

Hidden Terminal Suppression

<Full duplex packet exchange>

<Full duplex with hidden terminals>


MAC Protocol for Full Duplex Wireless and Directional

Antennas (Sophia Univ. Japan)

Problem

Since CSMA/CA is designed or half duplex wireless, a node’s data

transmission is prohibited when the node detects carrier

In the situation where data traffic is one-way in a line-type multihop

network, ACKs incur collisions

Data collisions hardly occur in the situation where data traffic is one-

way in a line-type network

22[15] K. Miura and M. Bandai, “Node Architecture and MAC Protocol for Full Duplex Wireless and Directional Antennas,” in Proc.

PIMRC 2012, Sept. 2012

S 1 2 D

DATA DATA DATA

<Full Duplex transmission with directional antennas>


MAC Protocol for Full Duplex Wireless and Directional Antennas

Proposed MAC protocol

Modifying condition for data transmission

• Allows to transmit data if the node detects carrier and the destination MAC

address of the detected data is the node itself

No ACK frame

• Removes ACKs from the conventional CSMA/CA without RTS/CTS to avoid frame

collisions

No contention window

• Contention window is not necessary for the proposed MAC protocol in a one-way

linetype network

23<Operation of proposed MAC protocol>

S

Time

DATA DATA

DATA

DATA

DATA

DATA

1

2

3


MAC Protocol for Full Duplex Wireless and Directional Antennas

Performance (using NS-3)

24

<Sample operations>

S 1 2 D

S 1 2 D

S 1 2 D

S 1 2 D

S 1 2 D

(i)

(ii)

(iii)

(i)

(ii)

S 1 2 D

S 1 2 D

(i)

(ii)

S 1 2 D

Directional transmission

Omni-directional transmission

(a) Conv[Half, Omni] (b) Conv[Full, Omni]

(c) Conv[Half, Direc] (d) Prop[Full, Direc]

<Performance : 114% Improve >


AC-MAC/DCW (Sophia Univ. Japan)

Problem

When uplink and downlink are asymmetric, the opportunity for full-

duplex operation decreases, which incurs throughput degradation

= > Balancing the transmission queue length at client nodes and AP for

various situations of uplink and downlink traffic is necessary

AP-Client initiated MAC with Dynamic CWs (AC-MAC/DCW)

Contention window size of AP is dynamically changed according to the

transmission queue length at AP to balance uplink and downlink traffic

In AP, two values of CW are defined: CWsmall and CWlarge

1) When AP completes a data frame transmission, the AP checks the number

of data frames in its transmission queue

2) If the queue length is shorter than a threshold Th, CWlarge is adopted for

prioritizing client nodes’ transmissions. AP randomly selects its backoff time in

[0, CWlarge] : Small size of packet to send -> Low Priority

3) Otherwise, CWsmall is adopted for prioritizing AP’s transmission. AP

randomly selects its backoff time is in [0, CWsmall]

25[16] S, Oashi and M. Bandai, “Performance of Medium Access Control Protocols for Full-Duplex Wireless LAN,” APSITT 2012,

November 2012

AC-MAC/DCW

Performance(by simulation 1AP, 4 STAs, no hidden terminal)

AC-MAC/DCW can achieve higher downlink throughput in a small Rup

AC-MAC/ DCW keeps almost the same downlink throughput as the

conventional MAC protocol in a large Rup

AC-MAC/DCW can obtain these improvement of downlink throughput

without degrading uplink throughput

Limitation: AP and all the STAs have same data rate

26


<Aggregated downlink throughput (Rdn = 3Mbps) > <Aggregated uplink throughput (Rdn = 3Mbps) >


Relay Full-Duplex MAC (RFD-MAC)(Shizuoka, Sophia Univ. Japan

Problem

In order to make maximum use of both bidirectional full-duplexing and

relay full-duplexing, the MAC protocol must properly select a secondary

transmission node

A collision between a primary transmission and a secondary transmission

• Whenever a destination node of a primary transmission node is located within

the transmission range of a secondary transmission node, a collision occurs at

the destination node

27[17] K. Tamaki, A. Raptino, Y. Sugiyama, M. Bandai, S. Saruwatari and T. Watanabe, “Full Duplex Media Access Control for Wireless Multi-

hop Networks,” in Proc. VTC Spring 2013, June 2013

AP A

A B C D

<Bidirectional full-duplexing>

<Relay full-duplexing><Collision between a primary transmission

and a secondary transmission>

P

R

R

S

Primary Transmission AreaSecondary Transmission Area

interferer

interferer


Relay Full-Duplex MAC (RFD-MAC)

Protocol

Whenever a node overhears a transmission from its surrounding nodes,

the node records the 1-bit information into a surrounding node table

When a node starts the primary transmission, the node also selects the

secondary transmission node and attaches the address of the secondary

transmission node

The secondary transmission node, which received the header of the

primary transmission, starts a secondary transmission

28

* Primary transmission node : Address 3, More Data

* Secondary transmission node : More Data

* Address 3 : the designated secondary transmission node address

* More Data : the source node of the frame has a successive frame

- 1 : have successive frame

- 0 : have no successive frame

<IEEE 802.11 header>

Frame Control

Duration/ID

Address 1

Address 2

Address 3

Sequence Control

Address 4

2 bytes 2 bytes 6 bytes 6 bytes 6 bytes 2 bytes 6 bytes

Protocol Version

Type SubtypeToDS

FromDS

More Fragments

Retry

2 bits 2 bits 4 bits 1 bit 1 bit 1 bit 1 bit

Power Mgt.

More Data

WEP Order

1 bit 1 bit 1 bit 1 bit


Selection of a secondary transmission

Whenever the destination node of a primary

transmission is located within the transmission

range of a secondary transmission, a collision

occurs at the destination node

Policy : Same flow and the least hop

Priority of the secondary node selection

1) The next-hop node that has a frame

2) The previous-hop node that has a frame

3) The previous-hop node that does not have a frame

4) The next-hop node that does not have a frame

29


data

ACKdatabusytone

X

Y

Send

Receive

Send

Receive data

ACK

ACK

ACK

data

offset

<RFD-MAC time sequence >

A

B

E

D


C

F

<Collision>

P S

<No Collision>

A

B

E

D


C

F

P

S


Performance (by simulation)

PHY rate: 2Mbps, Radio range: 250m, Pk size:1500B, #of STA :100,

Network size :2000(m) X 2000 (m)

30



Janus (Stanford Univ.): end and new start

Problem

How to schedule simultaneous transmission so throughput is

maximized

In AP-centric asymmetric case, the packets originating at node 1

might corrupt the packets that node 2 is receiving

Provide fairness

31

symmetric AP-centric asymmetric[18] J. Y. Kim, O. Mashayekhi, H. Qu, M. Kazadiieva, P. Levis, “Janus: A Novel MAC Protocol for Full Duplex Radio,” CSTR 2013-02 7/23/13 2013

[19] P. Levis, Stanford University, IEEE 11-13/1421r1 “STR Radios and STR Media Access,” November 2013

AP

Node 1 Node 2

AP

Node 1 Node 2

Interference

Janus : (SIR + Data rate (AMC) + FD Scheduler )

AP-based centralized full-duplex MAC protocol

Identify all FD opportunities

Schedule packet exchange to maximize throughput

Provide fairness

Finding FD pair given data rate ->NP-complete-> heuristic method

Main Janus components

AP information collector

• The length of the transmission that nodes intend to send to the AP

• The Interference level one node experiences when another node (including itself)

is transmitting at the same time

Full duplex scheduler

• Determine which packets will be transmitted concurrently and at what data rate

Acknowledgement packets

• postpones all acknowledgments until after all packet exchanges have terminated

32


Janus

State of Janus

33

<One round of Janus MAC packet exchanges>


* RRI (Reply to Request Information) packet contains two sets of data,

- the lengths of all packets the node wants to transmit

- information about the interference the node experiences from its neighboring nodes

Data size + Interference

Janus

Scheduling algorithm

Load Controller Unit (LCU): how long each node can send for

Rate-Timing Allocator (RTA): the order and data rates at each node

34


<an example of the scheduling algorithm>

<Parameter setting example>

Rin Rhalf

Rate(Mbps) 6 6

RO1←I1 RO1←I2 RO3←I2 RO3←I2

Rate(Mbps) 6 4 4 3

I1 I2 O1 O3

Queue Length (Bytes) 800 900 1000 1200

Incoming I1 I2

Outgoing O1 O3

I1 I2

O1 O3

I1

O1 (6Mbps)

I2

O3

+I1

O3 (4Mbps)

I2

O1

+

I1 I2

O3

+

O1 (4Mbps)

I1

O3 (3Mbps)

-

O1 (4Mbps)

I2

I1

O1 (4Mbps)

I2

O3 (6Mbps)

Step 0

Step 1

Step 2

Step 3

Step 4

Result

Unscheduled Scheduled Candidate

Tfull-duplex △Tcompletion

Janus

Performance

35

<Throughput>

90% gain

150% gain



A distributed full duplex MAC protocol (Polytech: USA, Sabanci:

Turkey )

Problem

In cases 2 and 3, which requires three nodes for FD transmission, an

inter-node interference exists

36[20] S. Goyal, P. Liu, O. Gurbuz, E. Erkip and S. Panwar, “A Distributed MAC Protocol for Full Duplex Radio,” in Proc. Asilomar 2013,

November 2013

PT/SR PR/ST

PT PR/ST

SR

PT/SR PR

ST

PT PR

<Case 1. two node FD transmission>

<Case 2. destination based three node FD transmission>

<Case 3. source based three node FD transmission><Case 4. HD transmission>

A distributed full duplex MAC protocol

New signal/notification

Full duplex acknowledgment (FDA)

• What kind of FD transmission

Transmission Flag

• Prevents a node’s neighbors to start any new transmission to a node

• 1 : new transmission can be started

• 0 : new transmission cannot be started

37

<Different values of FD acknowledgement (FDA)>


Value Description

0 Receiver has packets for the transmitter

1 Receiver has packets for a different node (not the transmitter)

2 No FD from receiver at all

3 Transmission is not allowed


Signal to interference ratio (SIR)

Only secondary transmission which do not affect the primary

transmission is allowed

SIR > 𝛾𝑡ℎ, a secondary receiver sends an FDA reply with value ‘2’ to a

secondary sender and this node continues its transmission to a node

SIR < 𝛾𝑡ℎ, a secondary receiver sends an FDA reply with value ‘3’ to a

secondary sender and this node stops its transmission to a node

38



Two node FD Transmission

39


Node A

Node B

PLCP Header

ACKMAC

HeaderDIFS R.B.O DATA and FCS DIFSR.B.O…...

SIFS

SIFS

TF bit

PLCP Header

MAC Header

DATA and FCS ACK

SIFS

R.B.O : Random backoff

Node B replies '0'

TF bit is set to '0' Busy Tone

FDA

Node A

Node B


Destination based three node FD transmission

40


Node A

Node B

PLCP Header

MAC HeaderDIFS R.B.O

DATA and FCS DIFS

R.B.O…...SIFS

TF bit

PLCP Header

MAC Header

DATA and FCS ACK

FDA

Node B replies '1'

TF bit is set to '0'

Node CNode C replies '2'

SIFS

SIFS

SIFS

Contd..DATA and FCS

ACK

SIFS

FDA

TF bit

Node A

Node B

Node C


Source based three node FD transmission

41


Node A

Node B

PLCP Header

MAC HeaderDIFS R.B.O DIFS

R.B.O…...SIFS

ACK

Node B replies '2'

TF bit is set to '0'

Node D

SIFS

DATA and FCS Contd...

ACK

SIFS

FDA

TF bit

Node E

Node F

SIFS

PLCP Header

MAC Header

DATA and FCS

DATA and FCS to node B

Reply : Busy tone on the selected subcarrier

Request : Busy tone on the chosen subcarrier

Node F does not satisfy the minimum SIR requirement at B

Node A

Node B

Node E

Node D

Node F

Interference


Performance

42

* Case 1: two node FD transmission

* Case 2: both three node FD transmissions and

HD transmissions

* Reasons for lower gain of case 2

(1) extra overhead in the three node FD

transmission design

(2) different data rates for the uplink and downlink

links in three node FD transmission


FD@70 FD@80 FD@90

Case 1 67% 85% 88%

Case 2 32% 38% 39%

<FD throughout gain over the HD system>

<Throughput>

* FD@x means the FD node is capable of

canceling self-interference by x dB


FD MAC (Rice Univ., & AT&T , WARP based + OPNET simul.)

Problem

43[21] M. Duarte, A. Sabharwal, V. Aggarwal, R. Jana, K.K. Ramakrishnan, C.W. Rice and N. K. Shankaranarayanan “Design and

Characterization of a Full-Duplex Multiantenna System for WiFi Networks,” IEEE Transactions on Vehicular Technology, vol. 63, no. 3,

pp. 1160-1177, March 2014

RTS

DATA B

DATA A

CTS

ACK

ACK

CTS

RTS DATA A

DATA B ACK

ACK

CTS

NAV (CTS)

DIFS

SIFS SIFS SIFS

SIFSNode A (FD)

Node B (FD)

Node C (FD)

Node D (HD)

CTS NAV (CTS)

EIFS

DIFS

DIFS

DIFS

erroneous packets

Node B (FD)

Node A (FD)

Node C (FD)

Node D (HD)

< Fairness problem>

Transmit/Receive

Wait ACKTransmit

ACK

Receive ACK

Transmit/Receive finished

RTS

DATA B

DATA A

CTS

RTS DATA A

DATA BCTS

DIFS

SIFS SIFS

Node A (FD)

Node B (FD)

Waiting ACK for DATA A

Waiting ACK for DATA B

Timeout

Timeout

< ACK timeout problem>

Node B (FD)

Node A (FD)

?

How to initiate for second transmission

<Initiation for FD transmission >


FD MAC

Three modifications to legacy WiFi MAC

Discovery and transmission of FD packets

• The primary node sends a RTS and the node receiving the RTS then

discovers the FD transmit node id

• The secondary node transmit to the sender immediately after sending

the CTS whenever data are available

• If necessary, the secondary node further updates NAV based on the NAV

from RTS and the length of secondary packet

Management of ACKs

• Allows the nodes to send an ACK while waiting for ACK from the other

end

• The wait time for the reception of the ACK packet for both nodes involved in

the transmission is re-adjusted to the end of the NAV duration if necessary

44

Transmit/Receive

Transmit ACK

Wait ACK

Transmit/Receive finished

< Management of ACKs>


FD MAC

Three modifications to legacy WiFi MAC

Behavior of overhearing nodes

45

< All FD nodes >

RTS

DATA B

DATA A

CTS

ACK

ACK

CTS

RTS DATA A

DATA B ACK

ACK

CTS

NAV (CTS)

DIFS DIFS

DIFS

DIFS

SIFS SIFS SIFS

SIFSNode A (FD)

Node B (FD)

Node C (FD)

< Both FD and HD nodes >

erroneous packets

Node B (FD)

Node A (FD)

Node C (FD)

RTS

DATA B

DATA A

CTS

ACK

ACK

CTS

RTS DATA A

DATA B ACK

ACK

CTS

NAV (CTS)

DIFS EIFS

SIFS SIFS SIFS

SIFSNode A (FD)

Node B (FD)

Node C (FD)

EIFS

EIFS

Node D (HD)

CTS NAV (CTS)

EIFS

erroneous packets

Node B (FD)

Node A (FD)

Node C (FD)

Node D (HD)


FD MAC

Performance

87% performance gain for FD over HD system

46

향후연구이슈및관련연구 (1/3)

차세대무선랜 MAC 연구이슈


Contention 오버헤드, 스케줄링 오버헤드 등 MAC 오버헤드 감소

채널 자원 할당 및 간섭/충돌 회피 알고리즘

전송효율 극대화 위한 Massive MIMO Full-Duplex OFDMA 기반 스케줄링 알고리즘

Wider bandwidth

보다 넓은 주파수 대역폭을 활용하여 패킷 결합이득을 향상시킬 수 있는 OFDMA 기반 MAC 기술

이기종 unlicensed 대역 공존을 위한 전력제어, 호핑패턴 변화, 채널스킵핑 기술

47


다중경로패킷전송방법

상하향 패킷의 전송 경로 분리

상하향채널 비대칭성 존재

상하향 패킷 전송경로 분리에 따른 이득

• 상하향채널 각각의 최적채널 획득가능

• 상하향링크별 네트워크 로드분산 가능

영상서비스프레임별 전송경로분리

MPEG 코덱기반 영상에는 프레임별 중요도 존재

• I frame >> P frame > B frame

프래임별 전송경로 분리에 따른 이득

• 영상서비스 유지

• 정책에 따른 통신비용 절감P, B

frame

I frame

LTEWiFi

UE

Downlink packet

Uplink packet

LTE

LTE

UE

WiFi

48



다중경로 통신 Hybrid mode

R: required data rate

α: multiplexing factor, 0≤α≤1

β: diversity factor, 0≤β≤(1-α)

49[22] 김지수, 강신헌, 김재현 "다중경로 통신방식에 따른 성능분석," in Proc. 한국통신학회 동계종합학술발표회, 용평리조트, 2012년 02월.



Optimized β

PER 10-4~10-3: MTM provides the best performance

PER 10-3~4x10-2: The gain of DTM is larger than the gain of MTM

PER 10-2~1: The PER gain of DTM is not enough to make up packet error

Optimized throughput

HTM provides the best performance in all PER range

50<Optimized β > <Optimized throughput>

β


TDMA 환경에서 Network Coding을이용한스케줄링 XOR-based network coding

Pa broadcasts packet x1 to R and Sb in the 2nd slot;

Pb broadcasts packet y1 to R and Sa in the 3rd slot;

R broadcasts z1 (x1 ⊕ y1) to Sb and Sa in the 5th slot.

51

[ Timeslot allocation without NC (left) and with NC (right) ]

[23] J. R. Cha, J. K. Kim, and J. H. Kim "Novel Joint Network Coding and Scheduling Scheme in Distributed TDMA-based WMNs," in Proc.

MILCOM 2013, San Diego, USA, 18-20. Nov. 2013.


TDMA 환경에서 Network Coding을이용한스케줄링 ETE delay in a non-deterministic packet arrival case

52

<-1dBm of Tx power> <-2dBm of Tx power>

맺음말

53

차세대무선랜 MAC 연구 시작

Full Duplex MAC : 시작

Massive MIMO related MAC

OFDM vs. OFDMA

Wider Bandwidth :

Backward compatibility (CSMA vs. TDMA)

Centralized vs. Distributed

Network Architecture

Infrastructure or ad-hoc

Single or multi-hop

IEEE 802.11ax has just begun

Many new opportunities in MAC researches ?? !!!

References

[1] 이재 , 정민호, 이석규, “802.11ac 무선랜기술,” 한국통신학회지 (정보와통신) 제30권제6호, pp.13-19

2013. 5

[2] Status of IEEE 802.11 HEW Study Group, http://www.ieee802.org/11/Reports/hew_update.htm

[3] 조한규, LG전자차세대통신연구소 “HIGH EFFICIENCY WLAN – 802.11AX ,” 제3회 WLAN 최신기술워크숍, 4월, 2014년

[4] M.Y. Park, Intel Corporation, IEEE 11-13/0505r0, “MAC Efficiency Analysis for HEW SG,” May 2013

[5] A. Kishida, M. Iwabuchi, Y. Inoue, Y. Asai, Y, Takatori, T. Shintaku, T. Sakata and A. Yamada, NTT &

NTT DOCOMO, IEEE 11-13/0801r1, “Issues of Low-Rate Transmission,” July 2013

[6] K. Yunoki and Y. Misawa, KDDI, IEEE 11-13/1073r1, “Access Control Enhancement,” September 2013

[7] K. Yunoki and Y. Misawa, KD야, IEEE 11-13/1349r0, “Access Control Enhancement,” November 2013

[8] Y. Seok, J. Kim, G. Park, S. Kim, H. Cho, W. Lee, J. Chun, J. Choi, and D. Lim, LG Electronics, IEEE

11-13/0539r0, “Efficient Frequency Spectrum Utilization,” May 2013

[9] S. Kim, G. Park, J. Kim, K. Ryu and H. Cho, LG Electronics, IEEE 11-13/1058r0, “Efficient Wider

Bandwidth Operation,” September 2013

[10] Z. Wen, B. Li, Z. Luo, D. Chen, S. Wang and W. Xu, BUPT & CATR, IEEE 802.11-13/1046r2, “Discus

sion on Massive MIMO for HEW,” September 2013

[11] R. Taori, W. Kuo, K. Josiam, H. Shao, H. Kang and S. Chang, Samsung Research America &

Samsung Electronics, IEEE 11-13/1122r1, “Considerations for In-Band Simultaneous Transmit and

Receive (STR) feature in HEW,” Sept. 2013

[12] J. Choi, W. lee, J. Chun, D. Lim and H. Cho, LG Electronics, IEEE 11-13/1382r0, “Discussion on

OFDMA in HEW,” November 2013

[13] N. Singh, D. Gunawardena, A. Proutiere, B. Radunović, H. V. Balan and P. Key, “Efficient and Fair

MAC for Wireless Networks with Self-interference Cancellation,” in Proc. WiOpt 2011, May 2011

54

References

[14] M. Jain, J. I. Choi, T. Kim, D. Bharadia, S. Seth, K. Srinivasan, P. Levis, S. Katti and P. Sinha,

“Practical, real-time, full duplex wireless,” in Proc. MobiCom 2011, Sept. 2011

[15] K. Miura and M. Bandai, “Node Architecture and MAC Protocol for Full Duplex Wireless and

Directional Antennas,” in Proc. PIMRC 2012, Sept. 2012

[16] S, Oashi and M. Bandai, “Performance of Medium Access Control Protocols for Full-Duplex

Wireless LAN,” APSITT 2012, November 2012

[17] K. Tamaki, A. Raptino, Y. Sugiyama, M. Bandai, S. Saruwatari and T. Watanabe, “Full Duplex Media

Access Control for Wireless Multi-hop Networks,” in Proc. VTC Spring 2013, June 2013

[18] J. Y. Kim, O. Mashayekhi, H. Qu, M. Kazadiieva, P. Levis, “Janus: A Novel MAC Protocol for Full

Duplex Radio,” CSTR 2013-02 7/23/13 2013

[19] P. Levis, Stanford University, IEEE 11-13/1421r1 “STR Radios and STR Media Access,” November

2013

[20] S. Goyal, P. Liu, O. Gurbuz, E. Erkip and S. Panwar, “A Distributed MAC Protocol for Full Duplex

Radio,” in Proc. Asilomar 2013, November 2013

[21] M. Duarte, A. Sabharwal, V. Aggarwal, R. Jana, K.K. Ramakrishnan, C.W. Rice and N. K.

Shankaranarayanan “Design and Characterization of a Full-Duplex Multiantenna System for WiFi

Networks,” IEEE Transactions on Vehicular Technology, vol. 63, no. 3, pp. 1160-1177, March 2014

[22] 김지수, 강신헌, 김재현 "다중경로통신방식에따른성능분석," in Proc. 한국통신학회동계종합학술발표회,

용평리조트, 2012년 02월.

[23] J. R. Cha, J. K. Kim, and J. H. Kim "Novel Joint Network Coding and Scheduling Scheme in

Distributed TDMA-based WMNs," in Proc. MILCOM 2013, San Diego, USA, 18-20. Nov. 2013.

55

Thank you !

56

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