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HRPD Handoff Between ANHRPD Handoff Between ANHRPD Handoff Between ANHRPD Handoff Between AN
ZTE中兴通讯
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topic
i• overview• Handoff theory• Handoff message• EVDO handoffEVDO handoff• Handoff Procedure
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Overview
Handoff☞ The Act of transferring signaling and data communication continuously with an access terminal that moves from a subcell to another subcell
Handoff Typeyp☞ Soft/Softer Handoff : A handoff is characterized by communications between subcells on the same CDMA Frequency Assignment before termination of connection q y gwith an old subcell- Soft Handoff : A Soft Handoff may happen when the access terminal moves to another subcell under the different ANTS, ANC and PCF (Inter ANTS, Inter ANC, Inter PCF)
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Overview
Handoff Type- Softer Handoff : A Softer Handoff may happen when the access terminal moves to another subcell under the same ANTS (Intra ANTS)Hard Handoff : A handoff is characterized by a temporary disconnection of the Traffic Path. Hard Handoff occurs when the CDMA Frequency Assignment changes.Idle Handoff : The act of transferring a subcell to another for
C Cmonitoring the Control Channel, when the access terminal moves in the Idle Stae
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Overview
Handoff example
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Overview
Handoff type
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topic
i• overview• Handoff theory• Handoff message• EVDO handoffEVDO handoff• Handoff Procedure
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Handoff theory
Handoff theory sketch map
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topic
i• overview• Handoff theory• Handoff message• EVDO handoffEVDO handoff• Handoff Procedure
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Handoff message
RouteUpdate messageAT send RouteUpdate message to inform AN the current location of AT, and provide the wireless environment estimate, AT use RouteUpdate message ask AN to add or drop some pilot
TrafficChannelAssignment AN use TrafficChannelAssignment message manage the AT active set.
TrafficChannelComplete AT send TrafficChannelComplete message as the acknowledgement of AN TrafficChannelAssignmentacknowledgement of AN TrafficChannelAssignment message
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Handoff message
NeighborList messageNeighborList message , it is used update the AT Neighbor List
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topic
i• overview• Handoff theory• Handoff message• EVDO handoffEVDO handoff• Handoff Procedure
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EVDO handoff
Forward virtual Handoff At EVDO system, all AT maintenance an active pilot set. At any time, only one sector of one AN transmit traffic data to AT.This service sector is select by AT according to every sector forward channel quality. It use DRC cover select the service secor.Every pilot have one DRC cover (it is an 8bit walsh code),
f C CAT will use one of DRC cover modulate its DRC channel when AT want to receive traffic data from the sector. When AT use one of DRC cover, it can not use another DRC l l l h DRCDRC value on next slot, only can use the same DRC cover or Null cover.
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EVDO handoff
Forward virtual Handoff EVDO forward link do not support soft handoff, so it can improve the system forward throughput. If it use soft handoff, at the handoff process, at least two sector transmit the same data to the AT, it will waste some system throughput.At the handoff process, it will bring in some delay.
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EVDO handoff
Forward virtual Handoff
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EVDO handoff
Forward virtual Handoff
APAPAP1AP1
APAP
AP3AP3
APAP
AP2AP2Server before t1
Server before t1
Server ft t
Server ft t
Forward Link Data from current server
AP4AP4 after t1after t1
Pilot/MAC on FWD linkPilot/DRC/ACK/RRI/DSC/AuxPilot/Traffic
on REV Link(AP’s in AT’s active set)
Forward Link Data from AP2 following server change
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EVDO handoff
Reverse soft handoff and softer handoffSame as CDMA2000 1x systemIt will reduce the reverse link throughput because it increase its control channel.
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EVDO handoff
Hard handoffAt EVDO system, AN send a TrafficChannelAssignment message to AT, the carriers information is included in this message. AN use this message direct AT handoff from one carriers to another carriers.After receive the message, AT will disconnect current traffic channel and try to connect to new carrier.
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EVDO handoff
Idle handoffWhen AT stay at idle state, AT continue search current CDMA carrier’s pilot channel strength, when AT detect one of the NeighborSet pilot strength is 3dB greater than the ActiveSet pilot strength, and the time last at least 1 second, it will add this pilot to ActiveSetit will add this pilot to ActiveSet.
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topic
i• overview• Handoff theory• Handoff message• EVDO handoffEVDO handoff• Handoff Procedure
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Handoff Procedure
Softer Handoff Procedure – AddAccess terminal initiates the Softer Handoff procedure when the access terminal moves from alpha sector to beta sector in a ANTS and the beta sector pilot strength is greater than PilotAdd
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Handoff Procedure
Softer Handoff Procedure - DropAccess terminal initiates the Softer Handoff procedure when the access terminal goes off alpha sector and so alpha sector pilot strength is less than PilotDrop and expired PilotDropTimer.
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Handoff Procedure
Softer Handoff Procedure – Swap
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Handoff Procedure
Soft Handoff Procedure – AddAccess terminal initiates the Soft Handoff procedure when the access terminal moves from ANTS#1 to ANTS#2 and the ANTS#2 pilot strength is greater than PilotAdd
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Handoff Procedure
Soft Handoff Procedure – DropAccess terminal initiates the Soft Handoff procedure when the access terminal goes off ANTS#2 coverage and so ANTS#2 pilot strength is less than PilotDrop and expired PilotDropTimer.
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