Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
휴대휴대 인터넷인터넷 ((WiBroWiBro) ) 기술기술
권동승권동승, , 여건민여건민, , 유병한유병한, , 박윤옥박윤옥, , 안지환안지환
이동통신연구단이동통신연구단
- 2 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단ContentsContents
IntroductionIntroductionMarket trend, internet service evolutionMarket trend, internet service evolutionService concept of Service concept of WiBroWiBro
Service and System requirementsService and System requirements
System ArchitectureSystem Architecture
Design Principles Design Principles
Key Features of Physical LayerKey Features of Physical Layer
Key Features of MAC LayerKey Features of MAC Layer
- 3 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Why WiBro? : Subscribers in KoreaWhy Why WiBroWiBro? : Subscribers in Korea? : Subscribers in Korea
Mobile phone/internet usersMobile phone/internet users High speed internet usersHigh speed internet users
Mobile phoneusers
MobileInternet
Unit : Million Users Unit :Million Users
23
27
16
29
3332
2931
24
15
20
25
30
35
1999 2000 2001 2002 2003
0.2
3.9
7.8
11.2
10.4
0
3
6
9
12
1999 2000 2001 2002 2003
Source : Ministry of Information & Communication (Nov, 2003)
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이동통신연구단이동통신연구단Why WiBro? : Internet service evolutionWhy Why WiBroWiBro? : ? : Internet service evolution
Typical Internet Services
High-speed Wireline Internet Services (Cable Modem / ADSL / VDSL)IP service in a home domain1 ~ 10Mbps(upgraded to 50Mbps)
Medium or Low Speed Wireless Internet Services (Cdma2000, WCDMA)
Cellular-based platform : originating/termination callPublic mobile service, but expensive 144/384 Kbps (1x, wcdma), 2.4/10Mbps (Ev-DO, HSDPA)
High-speed Wireless Internet Service(IEEE 802.11 series)IP service in a local or private areaMaximum 54Mbps
Demand on a High-speed Portable Internet ServiceHigh-speed data, Low-cost, Portable(Low-mobility) Service
Easy service connectivity.Wireline and wireless network convergence.Multimedia services.
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이동통신연구단이동통신연구단Why Why WiBroWiBro? : Definition? : Definition
Portable Internet Portable Internet Service(WiBroService(WiBro) is to ) is to provideaprovidea high data rate high data rate
wireless internet access with PSS(Personal Subscriber Stationwireless internet access with PSS(Personal Subscriber Station))
under the stationary or mobile environment, anytime and anywhunder the stationary or mobile environment, anytime and anywhere.ere.
DefinitionDefinition
『Portable Internet』was named as 『WiBro』. (End of April, 2004)
WiBro : Wireless BroadbandReferenceReference
WiBroWiBroWiBro
Low CostAnytime,Anywhere
MobilityHigh
Data Rate
- 6 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Why WiBro? : Korea market wants WiBroWhy Why WiBroWiBro? : Korea market wants ? : Korea market wants WiBroWiBro
Cable Modem, ADSL, VDSL
Telephone Line Modem,
PDSN, Router / ATM
Data
Voice
Wired Line Wireless
PSTN, ISDN
Key Phone, PABX
CDMA, WCDMA
TRS
WLAN(Private)
EVDoHSDPA
High
Low
Expensive moderatePrice
DataRate
WiBro(Public)
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이동통신연구단이동통신연구단Service and System RequirementsService and System Requirements
Service ClassesService ClassesRealReal--time service: time service: audio/video streaming, interactive game, ……….NonNon--realreal--time service: time service: FTP, Multimedia mail, chatting, e-commerce, …BestBest--effort Service: effort Service: Web browsing, e-mail….
RequirementsRequirementsCell types and service coverageCell types and service coverage
• Pico-cell (100 m) / Micro-cell (400 m) / Macro-cell (1km) in urban environment.
Mobility: Mobility: up to 60 km/hr.HandoffHandoff
• System shall support seamless IP-based service while users move from one cell to other.
Authentication and SecurityAuthentication and SecurityQoSQoS (Quality of Service)(Quality of Service)ChargingChargingInterworkingInterworking with other network systemswith other network systems
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이동통신연구단이동통신연구단Service and System RequirementsService and System Requirements
Access Network Requirements & ParametersAccess Network Requirements & ParametersFrequency reuse factorFrequency reuse factor: FRF = 1Spectral efficiency (bps/Hz/cell):Spectral efficiency (bps/Hz/cell):
• Maximum spectral efficiency : Downlink = 6, Uplink = 2• Average spectral efficiency : Downlink = 2, Uplink = 1
Transmission data rateTransmission data rate• Minimum transmission data rate per user:
Downlink = 512 kbps, Uplink = 128 kbps• Maximum transmission data rate per user:
Downlink = 3 Mbps, Uplink = 1 MbpsHandoff requirementsHandoff requirements
• Inter-sector handoff: < 150 msec• Inter-cell handoff: < 150 msec
Average throughput (bps/Hz/cell)Average throughput (bps/Hz/cell)• Downlink = 2, Uplink = 1
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이동통신연구단이동통신연구단System ArchitectureSystem Architecture
System architecture of HPi
HA
HPi-AP
HPi-AT HPi-AT
Uh
Mobile IP
PAR
FA
AAA
PAR : Packet Access RouterNMS: Network Management System
NMS(O&M)
Public IP Network
HPi-AP
PAR
W-LAN
HPi-AT
W-LAN AP
Service provider’sIP Network
Uh
Ah Ah
Ih
Ph
Ih
Interface Reference PointUh : AP-ATAh : AP-PARPh : PAR-PARIh : PAR-INTERNET
Inter AP HandoverInter PAR Handover
Seamless handover
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이동통신연구단이동통신연구단System ArchitectureSystem Architecture
Service SpecificConvergence Sublayer
(CS)
MAC Common Part Sublayer(MAC CPS)
Privacy Sublayer
Physical Layer(PHY)
PHY SAP
MAC SAP
CS SAP
MAC
PHY
Service Specific Convergence Sublayer (CS)Transformation or mapping of external network dataReceived through the CS SAP into MAC SDUs received by the MAC CPS through the MAC SAP.This includes classifying external network SDUs and associating them to the proper MAC service flow and CID. Payload header suppression. The internal format of the CS payload is unique to the CSThe MAC CPS is not required to understand the format of or parse any information from the CS payload.
The MAC CPSCore MAC functionality of system access, Bandwidth allocationConnection establishmentConnection maintenanceClassified to particular MAC connections.Quality of Service (QoS)Scheduling of data over the PHY.
Privacy SublayerProviding authenticationSecure key exchangeEncryption.
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이동통신연구단이동통신연구단Design PrinciplesDesign Principles
Freq reuse factor “1” deploymentOFDMA scheme
• Multiple user signals are multiplexed by unit of subchannel in the same OFDM symbols
• Provide high granularityDiversity subchannelization based on R-S sequence
• Each cell has different R-S sequence offset.• Guarantee the number of hit is below the specific number so that the inter-
cell interference is averaged• The subchannels changing every slot give the frequency diversity effect
equivalent to frequency hopping.Low coding rate
• Provide robustness to inter-cell interference
Synchronized operationThe FA’s of the one operator and the FA’s of different operators are synchronized so that the DL and UL make no interference to each other.
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이동통신연구단이동통신연구단Design PrinciplesDesign Principles
Flexibly provide fast band selection and full diversity schemes in a single framework
Classify users according to channel characteristics• Band selection users and diversity users
For diversity users• Utilize multiple dimensions of diversity to enhance statistical reliability• Wideband frequency diversity and temporal diversity
For band selection users• Maximize multi-user scheduling gain at each frequency band by utilizing
channel selectivity of each user
Robust to channel and interference fluctuationHybrid-ARQ at uplink and downlink
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이동통신연구단이동통신연구단Design PrinciplesDesign Principles
Support the mobility of 60km/h2.35 GHz, 60 km/h → Doppler freq (fd) = 130.56 Hz
Coherence time (1/fd) = 7.66 ms• DL pilot subcarrier rotation period: 345.6 us < {0.1* Coherence time}• UL pilot subcarrier insertion period: 345.6 us < {0.1* Coherence time}
H-ARQ with short-length frame maintains the link quality
Fast access and hand-off timeShort frame length: 5msSeparate ranging time slot guarantees low latency
Flexible DL/UL Time AllocationSupportable DL/UL throughput ratio of 1:1 ~ 10:1
• DL:UL symbol ratio - 12:24(0.5:1), 18:18(1:1), 24:12(2:1), 30:6(5:1)• Apply the spectral efficiency of DL 2 bps/Hz/cell and UL 1 bps/Hz/cell
– DL/UL throughput ratio of 12:24 (12*2): (24*1) = 1:1
- 14 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features for Physical LayerKey Features for Physical Layer
Multiple Access/Duplexing: OFDMA/TDDBandwidth: 10MHz with 1k-FFT Frame length: 5 msecCell differentiation with different PN sequencesFlexible subchannelization for band selection and diversity
Full diversity subchannel by multiple symbol groupingFast AMC (adaptive modulation and coding) subchannel based on uplink CQI (channel quality indicator)Pilot tone based downlink and uplink
Modulation level: QPSK(DL/UL), 16QAM(DL/UL), 64QAM(DL only)More efficient channel coding: convolutional turbo codeH-ARQ in the downlink and uplink Separate control channel in uplink
Dedicated Ranging / Ack / CQI channel time slot
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이동통신연구단이동통신연구단
ValueSystem Bandwidth 10 MHz
Sampling frequency 10 MHz
Tone spacing 9.765625 kHz
TDD frame length 5 ms
TTG+RTG 161.6 µs
Signal bandwidth 8.447 MHz
Number of used tones 864 out of 1,024
Number of data tones 768
Basic OFDMA symbol time 102.4 µs
OFDMA symbol time 115.2 µs
Number of symbols in a frame 42
Number of pilot tones 96
Ratio of cyclic prefix time to the basic OFDM symbol time 1/8
Cyclic prefix time 12.8 µs
Key Features for Physical Layer
OFDM System parameters
- 16 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features for Physical LayerKey Features for Physical Layer5 msec frame length : 42 OFDM symbols
Flexible downlink and uplink time slot partitioning
Μ
Λ
Μ ΛΛ
Λ
Λ
Λ
Λ
Λ
Λ
Λ
Band 0
Band 1
Band 2
Band 3
Band B-2
Band B-1
Slot SlotTTG
Downlink Uplink
5 ms
RTG
Preamble Uplink Control Symbols
Safety Channel
Group Bin Tile Bin
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이동통신연구단이동통신연구단Downlink PHY Frame StructureDownlink PHY Frame Structure
0 1 212 13 1424 25 2636 37 380 1 212 13 140 1 2
0 1 20 1 212 13 1424 25 26
Μ
Λ
Μ
ΛBand b-1
Band b
Band b+1
Preamble
Μ Μ
D D Λ
Λ
Λ
Λ11233547112311
11112335
Λ
D D A A A A
3 4 515 16 1727 28 2939 40 413 4 515 16 173 4 5
3 4 53 4 515 16 1727 28 29
A A ASymbol
Bin for AMC Subchannel
Bin for Safety Subchannel
Subcarrier for Diversity Subchannel
Safety Channel
Downlink Frame structure
- 18 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Uplink PHY Frame StructureUplink PHY Frame Structure
Λ
Λ
Λ
Λ
Band 0
Band 1
Band 2
Band 3
Band B-2
Band B-1
Slot
Uplink Control Symbols
Safety Channel
Tile Bin
Tile
BinPilot
Subcarrier
Safety Subchannel
Μ Μ Μ
Uplink Frame structure
- 19 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features for Physical LayerKey Features for Physical Layer
Downlink Preamble structure
• First OFDM symbols in downlink• Implicit time domain repetition (Three per OFDM symbol)
Objects• Frame timing acquisition
– Searching for maximum auto-correlation between repeating patterns in time domain
• Frequency offset estimation– Average phase rotation between sample pairs from repeating patterns
• Cell search– Cross-correlations in frequency domain– Differential demodulation to compensate frequency selective fading– Best cell search by comparing the cross-correlation magnitudes
• Symbol timing estimation– Average slope of phase rotation over all nonzero subcarriers
- 20 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features for Physical LayerKey Features for Physical Layer
Band AMC Mode in Uplink and Downlink
Fast CQI report for bands from user terminals are providedPower headroom report from user terminals for uplink band selection are providedPacket scheduler in AP• Select users per band according
to channel quality at bands and scheduling criteria
• Decide appropriate modulation level and code rate for users
Downlink Band Selection
- 21 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features for Physical LayerKey Features for Physical Layer
Full Diversity ModeAverage CQI report for all bands from user terminals are providedSelect appropriate modulation level and code rate in averaged C/I sense
Tones for user-A
Tones for user-B
Tones for user-C
time
freq
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이동통신연구단이동통신연구단Key Features for Physical Layer
RangingObject:
• UL Synchronization• Coarse UL power control
How to transmit• BPSK with a 144 bits long sequence in frequency domain
– 1 ranging subchannel corresponds to 8 UL diversity subchannels
• Users are allowed to collide on ranging subchannels– Contention based random access with randomly selected code and ranging subchannel
• Time Domain structure Initial & HO ranging Periodic & BR ranging
- 23 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features for Physical Layer
4 ranging modes are defined• Initial ranging• Hand off (HO) ranging• Periodic ranging• Bandwidth request (BR) ranging• Enhanced fast HO ranging: User terminal estimates delay difference between serving
cell and target cell using preamblesRanging modes are differentiated by code and time slot
• Initialization of PN code generator depends on cell ID• Distinct code sets for each ranging mode• Initial ranging and HO ranging time slot are allocated to the first two OFDMA symbol
periods in the up-link frame• Periodic ranging and BR ranging time slot are allocated to the OFDMA symbol period
immediately following
- 24 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features for Physical LayerKey Features for Physical Layer
CTC is baselineCTC (Convolutional Turbo Code) for message and traffic
• Rate 1/3 mother code for H-ARQ (Incremental redundancy)• Effective code rate: 1/12 ~ 5/6 with QPSK, 16QAM, 64QAM
– Repetition and puncturing from mother code• Large information block size up to 4800 bits
– Provides interleaving gain
Block codes for short control informationCQI/ACK : Non-binary block coding
Coded symbol scramblingFixed PN Generator with Cell ID based maskingInter-cell interference from the same frequency bin can be randomized at the encoder output
- 25 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features for Physical Layer
• Sub-block symbol separation, interleaving and grouping for H-ARQ support (IR scheme).
A
B
CTC Interleaver
switch
2
1Constituent
Encoder
C1
C2
CTC Encoder Interleaver
Interleaving
Symbol Selection
SymbolSelection
A'
B'
ZPuncturing
Uplink Puncturing
Subblock
AB
Subblock
Interleaver
Subblock
Subblock
Interleaver
Subblock
Subblock
Interleaver
Subblock
Subblock
Interleaver
Subblock
Subblock
Interleaver
1Y 2Y 1W 2W
H-ARQ Supportable Coding
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이동통신연구단이동통신연구단Key Features for Physical LayerKey Features for Physical Layer
Incremental Redundancy based H-ARQ for uplink and downlinkTo mitigate the effect of channel and interference fluctuation
• Overcome adaptation error of AMC in fading channelTo render performance improvement due to SNR gain and time diversity achieved by combing sub-packets
• Transmit different redundancy version for different sub-packet• H-ARQ provides flexibility to adapt the sub-packet transmission rate
according to the most recent channel quality feedbackMaximum number of sub-packet retransmission depends on service classes
Control for H-ARQPhysical Layer CRCSub-Packet IDARQ-Channel IDARQ-ID Sequence NumberUL-ACK/NAK ChannelDL-ACK/NAK in MAP
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이동통신연구단이동통신연구단Key Features for Physical LayerKey Features for Physical Layer
Uplink Control Channels-CQI, ACK, etcUL control channels
• Fast feedback on PHY link• Allocated to users, like a dedicated channel• CQI channel and ACK channel
CQI channel• DL CINR feedback
– for AMC and RRA operation– in Diversity or AMC modes
• MIMO antenna weight feedback– for Adaptive beamforming
• MIMO mode feedback – for MIMO mode and subcarrier permutation selection
ACK channel• ACK/NACK feedback for HARQ operation
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
주요 기능
Resource Allocation
Packet Transmission Control
Connection Management
MAC Management
Idle Mode Operation
Handover
Security
Sleep Mode Operation
MBS (Multicast/Broadcast Service)
HARQ Supporting
Ranging Supporting
Bandwidth Request
- 29 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Resource Allocation (1)DL 서브프레임 선두에서 AT에 대한 DL/UL 자원할당 정보를 표시하는 MAP 운용
DL-MAP 및 UL-MAP은 각각 하향링크 채널정보 및 상향링크 채널정보를 포함
DL은 OFDMA/TDM 방식, UL은 OFDMA/TDMA 방식으로 전송
- 30 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Resource Allocation (2)MAP 사용법 및 전용 피드백 채널
Transmission InformationChannel
Downlink Frame Uplink FrameTx. Period
Every Frame
Every Frame
Every Frame
Traffic Burst Traffic/Messages Traffic/Messages -Diversity
Band AMCSafety Channel
ACKCH H-ARQ Ack - Implicit
Periodic
Remarks
FCH Frame Control Header
-
General MAP pointing
General MAP General MAP information
Channel Quality
Compact MAP pointing
Ranging Codes
Compact MAP (HARQ based)
User data burst allocation
MAP AMC support
CQICH If allocated
Ranging CH Uplink synchronization
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Resource Allocation (3)MAP 구성정보
• CID (Connection ID)• DIUC/UIUC (Downlink/Uplink Interval Usage Code)• OFDMA Symbol/Subchannel Offset
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Connection Management기능 및 특징
• Connection 용도 및 특징에 따른 Connection ID (CID) 관리
• CID 종류 및 용도
종류 용도 비고
Broadcast CID 방송 정보 전송
Initial Ranging CID RNG-REQ/RSP 메시지 전송 -
Basic CID 지연 민감한 메시지 전송 DL/UL 동일
Primary Management CID 상대적으로 지연 덜 민감한 메시지 전송 DL/UL 동일
Secondary Management CID IP Management 패킷 전송 DL/UL 동일
Transport CID 트래픽 데이터 전송 -
Multicast Polling CID Multicast Polling 그룹에 속한 AT가 Polling을 통한 자원할당 요청 시 사용
-
패딩 정보 전송
-
Padding CID -
- 33 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Packet Transmission Control (1)Packet Classification
• IP Header에 의한 CID 매핑 기능
Packet Convergence• IP Header 압축
• Packet Suppression 및 Compression 제공– IP Header Masking 기능
– IETF ROHC 기능(옵션)
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Generic MAC Header
Bandwidth Request Header
Packet Transmission Control (2)MAC Header Format
• Generic MAC Header– 트래픽 데이터 및 MAC Management
Message 전송 (DL/UL)• Bandwidth Request Header
– 자원 할당 요청 용 (UL)• Fragmentation Sub-header
– MAC CPS SDU 분할 전송 용 (DL/UL)• Packing Sub-header
– MAC CPS SDU 연접 전송 용 (DL/UL)• Grant Management Sub-header
– Piggybacking 자원 할당 요청 용 (UL)
전송 방식
• Fragmentation– SDU를 분할하여 해당 분할을 하나의 PDU
로 전송
• Packing– 여러 SDU를 연접하여 하나의 PDU로 전송
• Piggybacking– Sub-header를 사용하여 하나의 PDU에
Piggybacking 하여 전송
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Packet Transmission Control (3)ARQ
• 다양한 ACK 피드백 방식
– Cumulative ACK– Selective ACK– Cumulative-Selective ACK– Sequential ACK
• 타이머 기반의 재전송 메커니즘
– ARQ Block Lifetime– ARQ Retry Lifetime– Tx/Rx Window Purge Time
• 전용 피드백 채널 운용
– Dedicated ACK Channel – Dedicated CQI Channel
• Flow Control 기능
– SDU Discard– Tx/Rx Window Change
Not-sent OutstandingTransmit Waiting-for-
retransmission
Done
ARQ_RETRY_TIMEOUTor NACK
Retransmit
Discarded
ARQ
_BLO
CK_LIF
ETIM
E
ARQ
_BLO
CK_LIF
ETIM
E
ACKA
CK
ACK
ARQ 메커니즘
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
MAC Management운용 방식
• MAC Management를 위한 메시지 정의
• 메시지에 대응되는 CID 매핑
• Generic MAC Header로 전송
메시지 종류
기능 관련 메시지 비고
Cell Sync. DCD, UCD, RNG-REQ/RSP
Resource Allocation DL-MAP, UL-MAP -
Registration REG-REQ/RSP, DREG-REQ/CMD -
Authorization PKM-REQ/RSP -
Connection Management DSx-REQ/RSP/ACK/RVD DSA, DSC, DSD
ARQ ARQ-Feedback/Discard/Reset -
AAS Service AAS-FBCK-REQ/RSP, AAS-BEAM-SLT/REQ/RSP -
AT Capability Negotiation SBC-REQ/RSP -
Burst Profile Change DBPC-REQ/RSP -
Channel Measurement REP-REQ/RSP
NBR-ADV, HO-REQ/RSP, SCN-REQ/RSP/REPORT
-
Handover -
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Idle Mode (1)개념
• AT가 여러 AP에 의해서 관장되는 영역을 돌아다니면서 특정한 AP에 등록되지 않고도 주기적으로 DL Broadcast 메시지를 받을 수 있도록 하기 위한 것
• Idle Mode에 있는 AT는 Handover 또는 Normal Operation에 따르는 Active Requirement를 지키지 않아도 됨
• 특정 구간에서만 AT 자신이 호출되었는지를 체크하면서 Power Saving 운용을 할 수 있음
AT 상태
• 모든 Active Connection 단절
• Serving AT에게 모든 Management CID 및 IP Address 반환
• Connection 설정 절차 없이 MBS 서비스 받을 수 있음
Idle Mode 진입 절차
• AP가 DREG-CMD 전송(unsolicited)• AT가 DREG_REQ 전송 후 AP가 AP가 DREG-CMD 전송
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Idle Mode (2)기능 및 단계
• Idle Mode Initiation• Cell Selection• Broadcast Paging Message Time Synchronization• Paging Unavaible Interval • Paging Listening Interval• Paging Interval• Broadcast Paging Message• Paging Availability Mode Termination
Paging Unavailble Interval
Scanning & Sync
Paging Interval
Paging Listening Interval
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Handover (1)주요 특징 및 기능
• Neighbor AP Advertisement 방송정보 송신
• Scanning 절차– AT에 의해서 Target AP로 타당한지를 결정하기 위해서 Neighbor AP를 탐색하
는 절차
• Soft HO (SHO) 및 Fast BS Selection (FBSS) 지원– Anchor BS/Active BS 개념 도입
– Fast Anchor BS Selection Feedback Channel 사용
• AT-initiated & AP-initiated HO 지원
• HO Drop Situation 복구 기능 지원
HO 관련 MAC Management message• NBR-ADV• SCN-REQ/RSP/REPORT• HO-REQ/RSP• RNG-REQ/RSP• SBC-REQ/RSP• PKM-REQ/RSP• REG-REQ/RSP
- 40 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Handover (2)Scanning & HO Initiation
AP-initiated HOAT-initiated HO
- 41 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Handover (3)HO Process
AP 1 AP 2
AT AT
4. Cell Reselection
Inter-Sector HO (AT-initiated) Inter-AP HO (AT-initiated)
- 42 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Handover (4)Soft Handover (SHO)
• DL에서 둘 이상의 AP가 동시에 해당 AT로 동일한 MAC PDU를 전송
• UL에서 둘 이상의 AP가 해당 AT로부터 동시에 수신(demodulation/decoding) Fast Base Station Selection (FBSS)
• 링크 품질을 향상시키기 위하여 Selection Diversity와 Switching Mechanism을 활용하는 것
• AT는 주어진 프레임에서 특정한 AP(Anchor AP)와만 데이터를 주고 받음
• Anchor AP는 매 프레임 단위로 변경될 수도 있음
Anchor AP-Anchor AP는 MSS에 대한 자원을 할당하여야 하는 책임을 가지는 AP
-Basic CID, Primary Mgt CID, Secondary Mgt CID, & Transport CID 할당의
책임-AT는 항상 Anchor BS와 동기를 유지하여야 함
-Anchor BS하고만 Ranging을 수행하여야 함-AT는 DL 제어 정보(DL-MAP, UL-MAP, FCH, DL Broadcast message)를 수신하기위하여 Anchor AT를 모니터링 함
Active AP-FBSS/SHO 절차에만 적용-Active Set은 해당 AT에 대한 Active AP들의 목록을 포함-Active BS는 해당 AT의 MAC Information에 대한 정보(capability, security parameters, service flows)를 제공 받음-SHO 모드에서 AT는 모든 Active AP들과 데이터를 송수신
Anchor AP-Anchor AP는 MSS에 대한 자원을 할당하여야 하는 책임을 가지는 AP
-Basic CID, Primary Mgt CID, Secondary Mgt CID, & Transport CID 할당의
책임-AT는 항상 Anchor BS와 동기를 유지하여야 함
-Anchor BS하고만 Ranging을 수행하여야 함-AT는 DL 제어 정보(DL-MAP, UL-MAP, FCH, DL Broadcast message)를 수신하기위하여 Anchor AT를 모니터링 함
Active AP-FBSS/SHO 절차에만 적용-Active Set은 해당 AT에 대한 Active AP들의 목록을 포함-Active BS는 해당 AT의 MAC Information에 대한 정보(capability, security parameters, service flows)를 제공 받음-SHO 모드에서 AT는 모든 Active AP들과 데이터를 송수신
- 43 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Security (1)Authorization Policy Support
• RSA• EAP• Mutual/Unidirectional Authorization• OMAC/HMAC
PKM Version Support• PKM version1 (RSA-based PKM)• PKM version2 (EAP-based PKM)
RSA-based PKM 및 EAP-based PKM 비교
• Authorization 방식 및 AK key 분배 메시지가 다름
– RSA-based PKM의 경우 Authentication Information/Authorization Request/ Authorization Reply 메시지를 통하여 Authorization을 처리하고 AP에서 AK키 분배
– EAP-based PKM의 경우 EAP-Transfer 메시지를 통해 Authorization을 하고 AAA 서버에서 AK키를 관여하여 분배
• AK Key 분배 Attribute 동일
– AK Key, Sequence Number, Lifetime • TEK Key 요청 및 분배 처리 동일
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Security (2)절차
AT AP PARSBC-REQ (Authorization Policy Negotiation)
EAP-TLS User Authentication and AK Distribution base on EAP-TLS
PKM-RSP/key reply(TEK key, sequence number, IV)
PKM-REQ/EAP-transfer (EAP Payload) ADTcmd
(additional information, EAP Payload)
AAA
Diameter(EAP-TLS)
Diameter(EAP-TLS)
ADTcmd(additional information, EAP Payload)PKM-RSP/EAP-transfer
(EAP Payload)
PKM-REQ/key request
...
SBC-RSP
PKM-REQ/Authentication InformationRegacy PKM
PKM-REQ/Authorization Request
PKM-RSP/Authorization Reply
PKMv2-EAP
PKM-REQ/RSP Messages (for PKM v2)
-EAP Transfer message-EAP Keying message-Pre-Authentication message-Mutual-Authentication message
PKM-REQ/RSP Messages (for PKM v2)
-EAP Transfer message-EAP Keying message-Pre-Authentication message-Mutual-Authentication message
- 45 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
HARQ SupportingHARQ용 Compact MAP을 사용하여 해당 AT에 자원 할당
UL Burst #1
UL Burst #2
UL Burst #3
Compact MAP 1
Compact MAP 2
DL Burst #5
DL Burst #6
DL Burst#7
General M
AP
DL Burst #1
DL Burst #2
DL Burst #3
DL Burst #4
FCH
MAP IE
Basic CID, Nep/Nsch for AT #ABasic CID, Nep/Nsch for AT #B
Basic CID, Nep/Nsch for AT #D
Compact MAP 3
CQI CH
ACK CH
Ranging Subchannel
MAP IEMAP IE
MAP IE
Basic CID, Nep/Nsch for AT #C
MAP IE
: HARQ_Pointer_IE
- 46 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Ranging Supporting (1)Ranging 방식 비교
메시징 방식 CDMA 방식
Unicast-polling × Unicast-polling ×
Contention-based × Contention-based Ο2
Contention-based × Contention-based
Periodic RangingUnicast-polling ∆ Unicast-polling ×
Ο1
Initial Ranging
×: 불가능, Ο: 가능(채택), ∆: 불가능하지는 않으나, 효율성 및 구현 측면에서 채택하지 않음Ο1: CDMA-based Ranging (status = success인 RNG-RSP 수신) 후,
CDMA_Allocation_IE에 할당된 UL 구간으로 RNG-REQ (with MAC Address) 메시지 전송
Ο2: CDMA-based Ranging 절차만 계속 (status = success가 될 때까지)
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Ranging Supporting (2)Initial Ranging 절차
AP
AT
1) DL Sync2) UL Burst 정보획득
AT
AP AP
AT
AP
AT
6) Backoff 7) Ranging Code 전송
AP
AT
UL-MAP
AP
AT
UL-MAP
RNG-REQ(MAC_Address)
8) Timing, Power, & Frequency Adjustment9) Random Subch, Symbol, Code 선택10) Ranging Code 전송
DCD/UCD/DL-MAP
3) UL-MAP Scan 4) Random Subch, Symbol, Code 선택5) Ranging Code 전송
RNG-REQ (Code)
RNG-RSP(Success)
AT
AP
AT
AP AP
AT
RNG-RSP(Management CIDs)
RNG-REQ (Code)
Binary-exponential
Random Backoff
11) RNG-RSP (Success) 수신mapped with transmitted Subch, Symbol, & Code
12) RNG-REQ message 전송with MAC Address
13) RNG-RSP (Management CIDs) 수신
Timer T3 Expire
RNG-REQ (Code)
RNG-RSP(Continue)
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Ranging Supporting (3)Periodic Ranging 절차
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Bandwidth Request (1)BW Request 제공 방식
제공 방식 기능 요청 방식
Unicast Polling UL-MAP 지정에 의해 특정 AT에 할당된 UL 자원상으로 BW Request Header 전송
Piggybacking동일한 CID에 대한 BW Request 할당 요청의 경우, UL 데이터전송을 위한 자원이 가용할 때, Grant Management Subheader를 추가하여 전송
Incremental
BW Stealing Data 전송용으로 할당된 자원을 AT의 판단에 따라 BW Request Header를 전송하기 위한 목적으로 전용하여 사용
Aggregate/ Incremental
BW Request용 CDMA Code를 Ranging Domain (UIUC = 11)에서 전송/성공 후, AP에 의하여 할당되는 UL-MAP의CDMA_Allocation_IE에 의하여 주어지는 UL 자원을 사용하여BW Request Header 전송
Aggregate/ Incremental
CDMA-based Request
Aggregate/ Incremental
CDMA-based Request는 Ranging (Random Access) 및 UL 자원 할당의 두 단계를 가진다.
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
Bandwidth Request (2)CDMA-based BW Request 절차
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
MBS (1)MBS
• 여러 개의 AP들에 의한 Synchronized Transmission을 통하여 별도의Network Entry 절차를 거치지 않고도 다수의 AP에 걸쳐 끊임없는Multicast/Broadcast Service 제공
MBS Zone • 하나의 MBS Service Flow에 대하여 CID 및 SA가 유효한 영역
• 하나의 AP는 여러 개의 MBS Zone에 대응 될 수 있음
MBS Security Association• MBS Group Security Association (MBS GSA)는 AP에서 제공
• MBS GSA 정보– Cryptographic Suite– Key Material
» MBS Authorization Key (MAK), » MBS Group Traffic Encryption Key (MGTEK)
– LifetimeMBS Traffic Encryption
• AES CTR Mode 사용
• PDU는 MBS Traffic Key (MTK)를 사용하여 Encryption함
• MTK는 MAK 및 MGTEK를 사용하여 생성
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
MBS (2)MBS MAC PDU Ciphertext Payload Format
MBS-MAP• AP는 해당 MBS Zone에서 서비스되는 MBS Connection들을 기술하기 위하여 MBS-
MAP message 전송
• MBS Burst 할당 정보 포함
CID Use• 특정한 영역에 있는 Dedicated Multicast CID들 사용
• 동일한 MBS_Zone에 속하는 AP들은 동일한 CID를 사용
• CID 할당은 MBS Content Server가 관리
Macro-diversity Gain:• MBS_Zone 내의 인접한 AP들에서 동일한 데이터 (PDU Header, Payload; 동일한
Channel Coding, Modulation 및 변조방식 사용)를 동일한 심볼구간 및 Carrier로 전송하여 Diversity Gain 획득
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이동통신연구단이동통신연구단Key Features of MAC LayerKey Features of MAC Layer
MBS (3)Register
• 특정 셀에 등록되지 않은 채로 Idle Mode 및 Sleep Mode에서 MBS service 유지 가능
SA Capability• MBS용 GSA (MBS-GSA)와 매핑
Data Encryption• Application Layer 및 MAC Layer에서의 Data Encryption 둘 다 지원
• MAC Encryption은 AES-CTR Mode 만 사용 가능
Power Saving Operation• MBS-MAP을 사용하여 MBS Burst들에 적용될 Physical Attributes 뿐만 아니
라 각각의 Connection에 대한 다음에 전송될 프레임 및 그 프레임에서의 위치에 대한 정보도 제공
• Scheduling을 통하여 Power Saving을 극대화 할 수 있음
- 54 - Broadband IT KoreaBroadband IT KoreaEETTRI RI ©© 20042004
이동통신연구단이동통신연구단
감사합니다감사합니다..
Thank You for Listening!!!Thank You for Listening!!!
FourthGeneration