Download - Modul2 EVDO Operation
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Modul-2Modul-2
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Outline
EVDO Network Structure
EVDO Channel Structure
EVDO Key Technology
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BTS Operation
PILOT Channel
PAGING Channel
SYNC Channel
TRAFFIC Channel
TRAFFIC Channel
CDMA20001x Forward Channel
Maximum Power
Tx Power
1xEV-DO Forward Channel
Maximum Power
Tx Power
Co
ntrolChannel
Co
ntrolChannel
DATA
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Rev. A Improvements
Introduction to Signalling 4
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Rev. A Improvements
Introduction to Signalling 5
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1X EV-DO Network Structure
Glosary
AT : Access Terminal
PDSN : Packet Data Serving Node
AAA : Authentication, Authorization,
Acounting
Glosary
AT : Access Terminal
PDSN : Packet Data Serving Node
AAA : Authentication, Authorization,
Acounting
AN : Access Network
HA : Home Agent
PCF : Packet data Control Function
RADIUS :Remote Authentication Dial-In User
Service
AN : Access Network
HA : Home Agent
PCF : Packet data Control Function
RADIUS :Remote Authentication Dial-In User
Service
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Centralized StructureCentralized Structure
Network Implementation
Leverage Current Investment Sharing the same RF with 95/1X
Insert new EVDO channel cards and software upgrade
Flexible Network Configuration
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EVDO Rev. A Channel
StructurePILOT
TRAFFIC
CONTROL
Reverse Activity Channel
Reverse Power Control
DRC lock
Medium Access
Control
FORWARD CHANNEL
Access
Network
(AN)
ARQ *
* Rev A Only
REVERSE CHANNEL
PILOT
Access
DATA
Traffic
PILOT
DATA
ACK
MAC
Reverse Rate Indicator
Data Rate Control
Access
Terminal
(AT)
AUX PILOT*
Data Source Control*
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Forward Channel Features
The Forward Channel (AN to AT) provides the
connections between AN and each AT.
The Forward Channel has following features:
The data rate is in a range of38.4 kbit/s~3.1 Mbps
Always at full power transmission, no power control;
Selecting the best service area according to the
measurement of C/I in Forward Channel and working
at the highest data rate;
The subscribers in a certain service area will share an
unique data service channel in a way ofTDM.
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Forward Channel Structure
Pilot: common channel for allusers to lock on the specificfrequency
Forward MAC channel :
RA : to dynamically control theworkload ofReverse Channel
RP
C : for power control of AT DRC lock : If AN cant receivethe DRC signals from AT, theDRC channel will stop the AT.
ARQ : to retransmit packeterror
Control: to send broadcasting
common configurationparameters page, signaling,channel assignment, schedule
Traffic: to send data
PILOT
TRAFFIC
CONTROL
Reverse Activity Channel
Reverse Power Control
DRC lock
Medium Access
Control
FORWARD CHANNEL
Access
Network
(AN)
ARQ *
* Rev A Only
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Basic Operation of Forward Link All sectors transmit forward
pilot bursts simultaneously Each AT estimates C/I ofactive pilots, predicts C/I andbest rate to request forforward link service
Each slot, the AT reports therequested rate and sector for
transmission via the DRCchannel
The AN schedulestransmission of preamble anddata sequentially to each AT,based on DRC contents
AT monitors preamble anddecodes data after preambleis detected
Reverse power control andother MAC information areconstantly sent over theforward channel
PILOT
TRAFFIC
CONTROL
Reverse Activity Channel
Reverse Power Control
DRC lock
Medium Access
Control
FORWARD CHANNEL
Access
Network
(AN)
ARQ
*
* Rev A Only
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FL Frame Structure
ZTE-STTELKOM Training Center Page -
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EV-DO Rev A. FL Data Rates
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Time Division Multiplexed in FL
In 1xEV-DO, the whole
forward link is used as
a shared Fat Pipe,
TDMed by all users. The subscribers share
the channel according
to the resource
allocation algorithmssuch as Round Robin
and maximizing
throughput.
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Reverse Channel Features
The reverse channels provide connections
between AT and AN.
The reverse channels have the followingfeatures:
Data rates is up to 1.8 Mbps;
Soft switch;
Dynamic power control;
Workload of reverse channels is adjusted by
rate control.
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Reverse Channel Structure Reverse Access Channels to
initiate calls or respond to AN pagingmessages at data rate of 9.6 kbps Reverse Pilot Channels
Data Channels
Auxiliary Pilot
Reverse Traffic Channels
P
ilot coherent demodulation
MAC,
DRC to give instructions to AN,including the requested data rate offorward traffic channels and theservice areas selected by forwardchannels.
RRI
to indicate the data rate of inoperation reverse data channels
DSC to give advance notice of the ATs intent to switch cells
Data to transfer reverse data
ACK to confirm data packetsdelivery from AN. NAK bits will be
sent if demodulation failed
REVERSE CHANNEL
PILOT
Access
DATA
Traffic
PILOT
DATA
ACK
MAC
Reverse Rate Indicator
Data Rate Control
Access
Terminal
(AT)
AUX PILOT*
Data Source Control*
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Basic Operation ofReverse Link
When an AT has an air link,the reverse pilot aretransmitted constantly
Reverse link is powercontrolled to achieve reliableBER
Reverse data is transmittedwhen available at ratespecified in Reverse MACprotocol
RR
IR
everseR
ate Indicator issent over the MAC channel tohelp AN decode the reversedata channel
REVERSE CHANNEL
PILOT
Access
DATA
Traffic
PILOT
DATA
ACK
MAC
Reverse Rate Indicator
Data Rate Control
Access
Terminal
(AT)
AUX PILOT*
Data Source Control*
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EV-DO Rev A. RL Data Rates
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DSC Channel Example
DSC auxiliary virtual soft handoff: The DSC notifies theAN in advance
that the target cell of this handoff to shorten the handoff delay.
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RL Access Probe Structure
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RLTraffic Channel Sub-Frame Structure
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Reverse Traffic Pilot /RRI Channel
Pilot channel : enabling
coherent demodulation at AN.
RRI channel: reporting
reverse transmission rate. Mapped from RRI 3-bit
symbol, 7-bit RRI codeword is
multiplexed with pilot before
transmission.
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Reverse Traffic ACK Channel
Indicating whether a data packet on the forward
traffic channel has been received successfully.
0 = successful
1 = failed
The ACK channel bit is transmitted at 9.6kbps
By using ACK channel in RL, AN can early
terminate multi-slot packet transmission andincreased the actual throughput.
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Reverse Traffic DRC Channel
AT sends the request of the desired data
rate and best serving sector of the forward
channel to AN over the DRC channel.
DRCCover:indicating the demanded data
rate
DRCValue: selecting the best serving
sector.
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Reverse Rate Control
The AN controls the ATs reverse link data rate
using three techniques.
Reverse Rate Limit message used by the
AN to control the transmission rate on theReverse Link for one or more ATs.
Reverse Activity Bit used to specify that the
sectors Reverse Link is busy
Reverse Rate Transition Probability Vectors
AN configures each AT with two rate transition
vectors associated with not busy or busy
statuses.
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1XEVDO Key Technology
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Adaptive Modulation and Coding
0 1000 2000 3000 4000 5000 6000 7000 80005
0
5
10
15
slot index
FLC/I(dB)
0 1000 2000 3000 4000 5000 6000 7000 80000
500
1000
1500
2000
2500
slot index
RequestedRate(kbps)
1xEV-DO dynamically adjust FL data rate, modulation
scheme and coding rate using the feedback from AT
through DRC channel
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At any instance thereAt any instance there
is only one servingis only one serving
sector for a specificsector for a specific
ATAT
AP1AP1
AP4AP4
AP2AP2
AP3AP3
AP1AP1 AP2AP2
TimeTime
Serving APServing AP
t1t1
ServingAP changeServingAP change
Serverbefore t1
Serverbefore t1
Serverafter t1
Serverafter t1
current sector forward data rate
Pilot/MAC on FWD link
Pilot/DRC/ACK/Traffic on REV Link
(APs in ATs active set)
After handoff AP2 forward data rate
Fast Cell Site Selection and Handoff
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Serving Sector Selection
-15
-14
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
0 2 4 6 8 10 12 14
time, sec
SINR,
dB
Sector 0
Sector 1
Serving
Sector Index
Serving SectorSelection
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Ec/Io and C/I There are two main ways of expressing
signal quality in 1xEV-DO C/I is the ratio of serving sector power to
everything else C/I determines the forward data rate
mobiles measure C/I during the pilot burst
period, then from it decide what data rate to
request on the DRC
Ec/Io is the ratio of one sectors pilot
power to the total received power the mobile uses Ec/Io to choose which sectors
to request for its active set
Ec/Io and C/I are related, and one can be
calculated from the other
EVDO Ec/Io is close to 0 db near a
sector, and ranges down to -10 at a cells
edge
EVDO C/I can be above +10 db near a
sector, and -20 or lower at the edge
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Relationship of Ec/Io and C/I in 1xEV-DO
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End ofSection 2
1xEVDO Operations