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ALL-IP 4G NETWORK ARCHITECTURE FOREFFICIENT MOBILITY AND RESOURCE MANAGEMENTYOUNG-JUNE CHOI, UNIVERSITY OF MICHIGANKWANG BOK LEE AND SAEWOONG BAHK, SEOUL NATIONAL UNIVERSITY 2007 IEEE Wireless Communications
R96725043 吳家宜R96725011 蔡依珊R96725030 屠敔傑
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Outline
Introduction on 3G cellular network3G network architectureIntroductions on ALL-IP 4G cellular networkALL-IP 4G cellular network architecture
Pure ALL-IP 4G network Subnet-based 4G network
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What is 3G access network? (wikipedia)3G is the third generation of mobile phone standards and technology. 3G networks are wide area cellular telephone networks. It enable network operators to offer users a
1. Wider range 2. More advanced services 3. Achieving greater network capacity through improved spectral efficiency Ex: WCDMA, cdma2000
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4G introduction4G networks are expected to integrate any kind of wireless network with Ethernet based on all-IP, and become a packet-switching system.All-IP
Exploit IP to integrate circuit switching network and packet switching network into a uniform all-IP network.Every mobile device has a IP.
RevolutionOrthogonal frequency division multiplexing (OFDM) 降低雜訊,增加傳輸量 ( 如 802.11b 屬於傳統單純調變 2Mb/s 和 802.11g 54Mb/s)Multiple input multiple output (MIMO) antennas OFDM 是讓調變波形更複雜,以此來增加電波的資訊含量,而 MIMO 則是同時動用 1 組以上的天線,同時發送多組電波,以增加發送的電波數來增加資訊含量, MIMO 與 OFDM 相同,用 MIMO 技術做為下一個加速提升方案 (IEEE 802.11n)
EvolutionInterworking with existing systems.
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4G’s vision
Integrate any kind of wireless network with Ethernet based on all-IP, and become a packet-switching system.To support high mobility
Exploit hybrid multiple access techniques.
To support Data and voice trafficTo increase throughputIntegrated different Quality of Services
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Mobile IPSource : http://wnai.csie.ndhu.edu.tw/ITS/news/courseware.htm
Obtain CoA (Care-of Address)
Register CoA for IP updating
Home address
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Handoff
HandoffWhenever a mobile terminal moves into another cell, it requires handoff to another base station.
Handoff Latency3 phases of a handoff:• Scanning (most time-consuming)• Authentication• Re-association
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ALL-IP cellular network architecture
The pure all-IP 4G network (2003)The subnet-based 4G network
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Outline
Network architecture all-IP cellular networkNetwork architecture for efficient multiple access
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Network Architecture All-IP Cellular Network
Existing cellular networkbase station (BS)• fast power control• wireless scheduling
base station controller (BSC)mobile terminal (MT)
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4G Network
Mobile IP (MIP) addresses for handoff
• incur high overhead
hinders from performing smooth handoff
Use high frequency band and result in short cell residence time
latency is a challenging issuefast handoff scheme for address resolution delay
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Subnet-based NetworkSeparate the functionality of an AR
AR takes L3 protocolaccess point (AP) takes L2 protocol
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Subnet-based Network
A subnet consisting of an AR and several APsAn MT moving within the subnet performs L2 handoffAn MT moving into another AR area performs L3 handoff
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ComparisonPure all-IP network Subnet-based all-IP
network
Access network components
AR AP + AR
Operation type Decentralized Centralized
Handoff overhead
High Low
Handoff protocol
L3 L2 + L3
Cost Low High
Advantage Architecture is simple and cost-efficient for implementation
Efficient to resource management
Disadvantage Long handoff latencyHigh signaling
overhead
Architecture is inflexible
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ComparisonPure all-IP network Subnet-based all-IP
network
Access network components
AR AP + AR
Operation type Decentralized Centralized
Handoff overhead
High Low
Handoff protocol
L3 L2 + L3
Cost Low High
Advantage Architecture is simple and cost-efficient for implementation
Efficient to resource management
Disadvantage Long handoff latencyHigh signaling
overhead
Architecture is inflexible
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ComparisonPure all-IP network Subnet-based all-IP
network
Access network components
AR AP + AR
Operation type Decentralized Centralized
Handoff overhead
High Low
Handoff protocol
L3 L2 + L3
Cost Low High
Advantage Architecture is simple and cost-efficient for implementation
Efficient to resource management
Disadvantage Long handoff latencyHigh signaling
overhead
Architecture is inflexible
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Network Architecture for Efficient Multiple Access
Cells are categorized into:Macrocells deployed in rural Microcells deployed in urbanPicocells deployed in building
User are categorized into:High-mobility users (macrocells)Low-mobility users (microcells)
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Macrocells and MicrocellsMT can access macrocells and microcells
macrocells cover high speed MTmicrocells cover low speed MT
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OFDMA v.s. FH-OFDMA
If an MT can support dual modes, it can switch cells in a manner of using vertical handoff
OFDMA FH-OFDMACombination
OFDM and FDMA Frequency-hopping and OFDMA
Advantages Higher allocation granularity
High spectral efficiencySupport various data
rate by AMC
Exploit diversityHigh mobilityOvercome channel fading and
multi-user interference
Disadvantage
Limited to low mobility Difficult in supporting high data rates and AMC (adaptive modulation and coding)
Mobility Microcells for low mobility Macrocells for high mobilityTraffic type High rate data services Low rate data services
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OFDMA v.s. FH-OFDMA
If an MT can support dual modes, it can switch cells in a manner of using vertical handoff
OFDMA FH-OFDMACombination
OFDM and FDMA Frequency-hopping and OFDMA
Advantages Higher allocation granularity
High spectral efficiencySupport various data
rate by AMC
Exploit diversityHigh mobilityOvercome channel fading and
multi-user interference
Disadvantage
Limited to low mobility Difficult in supporting high data rates and AMC (adaptive modulation and coding)
Mobility Microcells for low mobility Macrocells for high mobilityTraffic type High rate data services Low rate data services
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OFDMA v.s. FH-OFDMA
If an MT can support dual modes, it can switch cells in a manner of using vertical handoff
OFDMA FH-OFDMACombination
OFDM and FDMA Frequency-hopping and OFDMA
Advantages Higher allocation granularity
High spectral efficiencySupport various data
rate by AMC
Exploit diversityHigh mobilityOvercome channel fading and
multi-user interference
Disadvantage
Limited to low mobility Difficult in supporting high data rates and AMC (adaptive modulation and coding)
Mobility Microcells for low mobility Macrocells for high mobilityTraffic type High rate data services Low rate data services
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OFDMA v.s. FH-OFDMA
If an MT can support dual modes, it can switch cells in a manner of using vertical handoff
OFDMA FH-OFDMACombination
OFDM and FDMA Frequency-hopping and OFDMA
Advantages Higher allocation granularity
High spectral efficiencySupport various data
rate by AMC
Exploit diversityHigh mobilityOvercome channel fading and
multi-user interference
Disadvantage
Limited to low mobility Difficult in supporting high data rates and AMC (adaptive modulation and coding)
Mobility Microcells for low mobility Macrocells for high mobilityTraffic type High rate data services Low rate data services
26
OFDMA v.s. FH-OFDMA
If an MT can support dual modes, it can switch cells in a manner of using vertical handoff
OFDMA FH-OFDMACombination
OFDM and FDMA Frequency-hopping and OFDMA
Advantages Higher allocation granularity
High spectral efficiencySupport various data
rate by AMC
Exploit diversityHigh mobilityOvercome channel fading and
multi-user interference
Disadvantage
Limited to low mobility Difficult in supporting high data rates and AMC (adaptive modulation and coding)
Mobility Microcells for low mobility Macrocells for high mobilityTraffic type High rate data services Low rate data services
27
OFDMA v.s. FH-OFDMA
If an MT can support dual modes, it can switch cells in a manner of using vertical handoff
OFDMA FH-OFDMACombination
OFDM and FDMA Frequency-hopping and OFDMA
Advantages Higher allocation granularity
High spectral efficiencySupport various data
rate by AMC
Exploit diversityHigh mobilityOvercome channel fading and
multi-user interference
Disadvantage
Limited to low mobility Difficult in supporting high data rates and AMC (adaptive modulation and coding)
Mobility Microcells for low mobility Macrocells for high mobilityTraffic type High rate data services Low rate data services
28
OFDMA v.s. FH-OFDMA
If an MT can support dual modes, it can switch cells in a manner of using vertical handoff
OFDMA FH-OFDMACombination
OFDM and FDMA Frequency-hopping and OFDMA
Advantages Higher allocation granularity
High spectral efficiencySupport various data
rate by AMC
Exploit diversityHigh mobilityOvercome channel fading and
multi-user interference
Disadvantage
Limited to low mobility Difficult in supporting high data rates and AMC (adaptive modulation and coding)
Mobility Microcells for low mobility Macrocells for high mobilityTraffic type High rate data services Low rate data services e.g., voice
service
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OFDMA v.s. FH-OFDMA
If an MT can support dual modes, it can switch cells in a manner of using vertical handoff
OFDMA FH-OFDMACombination
OFDM and FDMA Frequency-hopping and OFDMA
Advantages Higher allocation granularity
High spectral efficiencySupport various data
rate by AMC
Exploit diversityHigh mobilityOvercome channel fading and
multi-user interference
Disadvantage
Limited to low mobility Difficult in supporting high data rates and AMC (adaptive modulation and coding)
Mobility Microcells for low mobility Macrocells for high mobilityTraffic type High rate data services Low rate data services e.g., voice
service
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QoS of wireless access networkIn general, a wireless access network becomes a bottleneck for providing end-to-end QoS.To support IP QoS, the Internet Engineering Task Force (IETF) recommends
integrated services (IntServ) differentiated services (DiffServ)
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IntServIntServ uses Resource Reservation Protocol (RSVP) to reserve bandwidth during the session setup.IntServ ensures strict QoS, but each router must implement RSVP and maintain per-flow state, which can cause difficulties in a large scale network.
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DiffServ
In DiffServ, the QoS level of a packet is indicated by the DS field of IP header, so that differential levels of service can be given to different aggregate flows at the entry points to the network.Since DiffServ is not so rigorous as IntServ, it is scalable in supporting QoS statistically.
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QoS of wireless access network (cont’d)
The importance of unified QoS management grows in 4G networks as QoS management for both access networks and IP networks becomes cumbersome in all-IP networks.
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QoS of wireless access network (cont’d)
3GPP (third generation partnership projects) define four traffic classes and their related parameters for QoS provisioning.However, direct translation is difficult since access networks have their own QoS attributes that require strict QoS provisioning within them.
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ITRAS
IP-Triggered Resource Allocation StrategyITRAS concerns the information about IntServ and DiffServ for the resource management of L1 and L2.
Cell type: microcell or macrocellMultiple access: OFDMA or FH-OFDMAMAC channel: dedicated or sharedPHY scheduling: priority or fairness
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ITRAS (cont’d)
For example, when an MT requests a real-time service, the corresponding AR can initiate IntServ and MAC reserves a dedicated channel.In contrast, when DiffServ is used for low mobility users, MAC can expolit either a dedicated or a shared channel.
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ITRAS (cont’d)
There are other issues to be considered
How an AR cooperate with its subordinate AP in performing ITRAS functions.Load balancing in macrocell and microcell.