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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
무선랜표준화동향
무선랜표준화동향
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
무선랜표준화동향
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
무선랜표준화동향
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
무선랜표준화동향
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
무선랜표준화동향
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)
Dense WLAN environment
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>
제안된 Full Duplex MAC (1/8)
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
제안된 Full Duplex MAC (1/8)
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
제안된 Full Duplex MAC (1/8)
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
제안된 Full Duplex MAC (2/8)
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>
제안된 Full Duplex MAC (3/8)
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>
제안된 Full Duplex MAC (3/8)
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
제안된 Full Duplex MAC (3/8)
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 >
제안된 Full Duplex MAC (4/8)
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
제안된 Full Duplex MAC (4/8)
<Aggregated downlink throughput (Rdn = 3Mbps) > <Aggregated uplink throughput (Rdn = 3Mbps) >
제안된 Full Duplex MAC (5/8)
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
제안된 Full Duplex MAC (5/8)
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
Relay Full-Duplex MAC (RFD-MAC)
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
제안된 Full Duplex MAC (5/8)
data
ACKdatabusytone
X
Y
Send
Receive
Send
Receive data
ACK
ACK
ACK
data
offset
<RFD-MAC time sequence >
A
B
E
D
Primary Transmission AreaSecondary Transmission Area
C
F
<Collision>
P S
<No Collision>
A
B
E
D
Primary Transmission AreaSecondary Transmission Area
C
F
P
S
Relay Full-Duplex MAC (RFD-MAC)
Performance (by simulation)
PHY rate: 2Mbps, Radio range: 250m, Pk size:1500B, #of STA :100,
Network size :2000(m) X 2000 (m)
30
제안된 Full Duplex MAC (5/8)
제안된 Full Duplex MAC (6/8)
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
제안된 Full Duplex MAC (6/8)
Janus
State of Janus
33
<One round of Janus MAC packet exchanges>
제안된 Full Duplex MAC (6/8)
* 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
제안된 Full Duplex MAC (6/8)
<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
제안된 Full Duplex MAC (6/8)
제안된 Full Duplex MAC (7/8)
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)>
제안된 Full Duplex MAC (7/8)
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
A distributed full duplex MAC protocol
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
제안된 Full Duplex MAC (7/8)
A distributed full duplex MAC protocol
Two node FD Transmission
39
제안된 Full Duplex MAC (7/8)
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
A distributed full duplex MAC protocol
Destination based three node FD transmission
40
제안된 Full Duplex MAC (7/8)
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
A distributed full duplex MAC protocol
Source based three node FD transmission
41
제안된 Full Duplex MAC (7/8)
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
A distributed full duplex MAC protocol
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
제안된 Full Duplex MAC (7/8)
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
제안된 Full Duplex MAC (8/8)
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 >
제안된 Full Duplex MAC (8/8)
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>
제안된 Full Duplex MAC (8/8)
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)
제안된 Full Duplex MAC (8/8)
FD MAC
Performance
87% performance gain for FD over HD system
46
향후연구이슈및관련연구 (1/3)
차세대무선랜 MAC 연구이슈
Dense WLAN environment
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
향후연구이슈및관련연구 (2/3)
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
향후연구이슈및관련연구 (2/3)
다중경로패킷전송방법
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.
향후연구이슈및관련연구 (2/3)
다중경로패킷전송방법
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
향후연구이슈및관련연구 (3/3)
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.
향후연구이슈및관련연구 (3/3)
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
Q & A