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HUAWEI TECHNOLOGIES CO., LTD. All rights reserved
www.huawei.com
cdma2000 1xEV-DO Procedure Flow
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Chapter 1 Why to use 1xEV-DO?Chapter 1 Why to use 1xEV-DO?
Chapter 2 Network StructureChapter 2 Network Structure
Chapter 3 Channel StructureChapter 3 Channel Structure
Chapter 4 Forward LinkChapter 4 Forward Link
Chapter 5 Reverse LinkChapter 5 Reverse Link
Chapter 6 Overhead MessageChapter 6 Overhead Message
Chapter 7 Access ProcedureChapter 7 Access Procedure
Chapter 8 SHO & VSHOChapter 8 SHO & VSHO
Chapter 9 EVDO Procedure FlowChapter 9 EVDO Procedure Flow
Chapter 10 Air Link ParametersChapter 10 Air Link Parameters
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Session Establishment
UATI assignment & configuration
negotiation
access authentication
location update
connection setup
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Session Establishment(2)
a. The AT and the AN initiate HRPD session establishment. A session is
established where protocols and protocol configurations are negotiated,
stored and used for communications between the AT and the AN.
b-c. The AT and the AN initiate Point-to-Point Protocol (PPP) and LCP
negotiations for access authentication.
d. The AN generates a random challenge and sends it to the AT in a
CHAP Challenge message. AT sends the CHAP response message to
AN.
e-f. AN sends an Access-Request message on the A12 interface to the
AN-AAA. The AN-AAA looks up a password based on the User-name
attribute in the Access-Request message and if the access authentication
passes, the AN-AAA sends an Access-Accept message on the A12
interface.
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Session Establishment(3)
g. The AN returns an indication of CHAP access authentication
success to the AT.
h. AN updates the ANID in the AT using the Location Update
procedure. The AN may also retrieve the PANID from the AT if
necessary.
i-m. The service connection of air interface and A8/A10 interface
are established.
n. The PPP link is established between AT and PDSN.
o. Now, connection is established, the user data packets can be
sent on the PPP link between AT and PDSN.
Following, we are going to talk about the detail of every step.
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Unicast Access Terminal Identifier
24 bit104 bit
UATI 104 (Subnet) UATI 24
Color Code
8 bit
UATI 32
ATI Type
ATI Type Description
ATI Length (bits)
'00'Broadcast ATI
(BATI)0
‘01’Multicast ATI
(MATI)32
‘10’Unicast
ATI(UATI)32
'11'Random ATI
(RATI)32
RATI is used between AN and AT before UATI is assigned. BATI is used when AN broadcasts message on CC channel. After UATI assignment, UATI is used to identify AT on air interface. When subnet changed, AT should send UATIRequest for updating UATI. It
is similar to registration based on registration zone in 1x.
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UATI Assignment
1. After AT acquired a network, it will send
UATIRequest with RATI for
UatiAssignment.
2. AN uses ESN for distinguishing AT. So,
AN sends HardwareIDRequest to enquery
ESN (Electronic Serial Number) of AT.
3. After getting ESN from
HardwareIDResponse, AN assigns an
UATI and sends it to AT. Including
UATIColorCode and UATI024.
4. AT responses it with UatiComplete.
AT
UatiRequest
HardwareIDRequest
HardwareIDResponse
AN
UatiAssignment
UatiComplete
UATI = UATIColorCode | UATI024
After UATI assignment, AT will use UATI to communicate with AN.
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Configuration Negotiation
AN and AT may consult with each other on some air interface parameters.
We called this consulting procedure as configuration negotiation. Before negotiation, AN and AT communicate with default values.
After coming to agreement on a parameter, AN and AT will use the negotiated
value.
If AN and AT can not get consensus, they will use default value.
RF parameters needed to be negotiated for DO rev0:PilotIncrementSearchWindowActiveSearchWindowNeighborSearchWindowRemaining
PilotAddPilotComparePilotDropPilotDropTimerDynamicThresholdsSoftSlopeAddInterceptDropInterceptNeighborMaxAge
ProbeSequenceMaxProbeBackoffProbeSequenceBackoff
DataOffsetNomDataOffset9k6DataOffset19k2DataOffset38k4DataOffset76k8DataOffset153k6RPCStep
Transition009k6_019k2Transition019k2_038k4Transition038k4_076k8Transition076k8_153k6Transition019k2_009k6Transition038k4_019k2Transition076k8_038k4Transition153k6_076k8
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Configuration Negotiation FlowAT AN
The sender uses the ConfigurationRequest message to provide an acceptable attribute value list of each attribute. The sender should list the acceptable attribute values of each attribute in the order of descended priority.
The receiver uses the ConfigurationResponse message to provide the accepted attribute value list of each attribute. These accepted attribute values are selected from the acceptable attribute value list.
When all configuration negotiations are complete, the sender sends the ConfigurationComplete message.
The sender uses the ConfigurationRequest message to provide an acceptable attribute value list of each attribute. The sender should list the acceptable attribute values of each attribute in the order of descended priority.
The receiver uses the ConfigurationResponse message to provide the accepted attribute value list of each attribute. These accepted attribute values are selected from the acceptable attribute value list.
When all configuration negotiations are complete, the sender sends the ConfigurationComplete message.
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Access Authentication
1. Setup connection between AN and AT
(i.e. traffic channel of air interface). Refer
to AN Originated Connection Setup.
2. The AT and the AN initiate PPP and LCP
negotiations for access authentication.
Refer to IETF: RFC 1661, Point-to-Point
Protocol.
3. The AN generates a random challenge
and sends it to the AT in a CHAP
Challenge message.
4. The AT answers it with CHAP response
message which carries access user
name and encrypted password.
AT AN AN-AAA
Connection Setup
LCP Configure-Request
LCP Configure-Ack
CHAP Challenge
CHAP Response
A12 Access Request
A12 Access Accept/ A12 Access reject
CHAP(authorization result)
Connection Close
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Access Authentication (2)
5. When the AN receives the CHAP response message from the AT, it sends an
Access-Request message on the A12 interface to the AN-AAA. Which carries:
access user name (Network Access Identifier),
CHAP-Password,
IP address of AN,
CHAP-Challenge = challenge value issued by AN,
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Access Authentication (3)
6. The AN-AAA looks up a password based on the User-name attribute in the
Access-Request message. If the access authentication passes, the AN-AAA
assigns an IMSI and sends an A12 Access-Accept message back to AN.
7. If the access authentication fails, the AN-AAA sends an Access-Reject message
on the A12 interface.
IMSI = 250092040002807
8. The AN returns an
indication of CHAP
access authentication
success or failure to
the AT.
9. IMSI is used between
AN and PDSN and
PDSN-AAA.
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Case – two ATs with same access user name (Nigeria)
Access user name is written in AT’s memory. If there is an access user
name written into two ATs. That is two ATs get the same access user
name.
AN-AAA assigns IMSI according to access user name for every AT. So,
the two ATs will get same IMSI.
AN uses ESN to distinguish the ATs, and setup two traffic channel for
these two ATs. But PCF and PDSN use IMSI to distinguish ATs and setup
only one link.
So, both of the two ATs can not transmit packets to internet.
AP1
AP2
AN PCF PDSN
INTERNET
AT
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Location Update
The AN uses LocationRequest to query
the AT of its Location information.
The AT sends the LocationNotification
message to AN either in response to the
LocationRequest message or in an
unsolicited manner.
If the subnet changed, the AN May send a
LocationAssignment message to update
the Location information.
If the AT receives a LocationAssignment
message, it shall send a
LocationComplete message.
AT
LocationRequest
LocationNotification
AN
LocationAssignment
LocationComplete
LocationValue Length
SID 15
NID 16
PACKET_ZONE_ID 8
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AT Originated Connection Setup
Detail:
① AT requests AN to
setup connection.
② AN acknowledges
reception of CR. AT
stops probe when rx
this Ack.
③ establish A8 & A10.
the forward packets
between and are ③ ⑦buffered at PCF.
④ AN prepares terrestrial
and air link resource
for TCH.
⑤ AN send TCA to AT.
AT AN PCF PDSN
ConnectionRequest(RouteUpdate Message)
TrafficChannelAssignment
TrafficChannelComplete
A9 Setup A8
A9 Connect A8
ACAck
RTCAck
Pilot+DRC
A11 registration request (lifttime ≠0)
A11 registration reply(accept)
A11 registration request (accounting)
A11 registration reply
A9 Update A8
A9 Update A8 Ack
PPP link negotiation and establishment ⑨
④
①
②
③
⑤
⑥
⑦
⑧
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AT Originated Connection Setup (2)
⑥ when AN acquire the
reverse pilot channel
and decode DRC
channel, it sends
RTCAck to AT. Now
both forward and
reverse links are
ready.
⑦ AN tells PCF that PCF
can send downlink
packets now.
⑧ and PCF sends
accounting information
to PDSN.
⑨ PPP link is etablished
between AT andPDSN. PPP parameters are negotiated and IP address is allocated.
⑩ now the user’s service data can be transmitted on the link.
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AN Originated Connection Setup
◎ in dormant, A10 and PPP link is maintained. Air link and A8 were torn down.
① packets from PDSN arrived at PCF. PCF send A9 BS service request to ask AN re-active the traffic link.
② AN page the AT by sending paging message on CC.
④ A10 already exist, it is not necessary to build it again.
AT AN PCF PDSN
ConnectionRequest(RouteUpdate Message)
TrafficChannelAssignment
TrafficChannelComplete
A9 Setup A8
A9 Connect A8
ACAck
RTCAck
Pilot+DRC
A11 registration request (accounting)
A11 registration reply
A9 Update A8
A9 Update A8 Ack
Dormant, PPP link is maintained ◎
④
①
②
⑤
⑥
⑦
⑧
paging
packet data arrivedA9 BS service request
A9 BS service response
③
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Connection Release (by AT or AN)
If the AT receives a
ConnectionClose message, it
shall send a ConnectionClose
message to AN.
If AN receives a
ConnectionClose message, it
shall consider the connection
closed. It is not necessary to
send ConnectionClose to AT.
A9 release-A8 carries release
cause “Packet call going
dormant”.
A11 registration request is not
for release A10 but for carrying
accounting information.
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Connection Release (Initiated by PDSN)
Connection Releasing Initiated by PDSN will tear down A10 and PPP link
together with air traffic channel and A8 link.
lifetime =0 means to release the A10 link
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Session Release
If AT receives sessionClose message, it will send sessionClose to AN.
If AN receives sessionClose message, it is not necessary to send sessionClose to AT.
with A8 connection
without A8 connection
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Soft Handoff
Correct neighbor list and GPS clock is essential important for
SHO.PN1 = 4 PN2 = 172
MS can’t see PN2 until find it in remainder set
Neighbor list:
PN1, 340
PN2, 64
PN3, 128
PN4, 72
PN1 = 4 PN2 = 172, but BTS send PN=174 caused by wrong clock.
MS can’t see PN2 even in remainder pilot set. PN2 becomes an island.
Neighbor list:
PN1, 340
PN2, 172
PN3, 64
PN4, 128
PN5, 72 SHO depends on AT reporting RouteUpdate
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(DRCCover = 2)
(DRCCover = 2)
(last packet number)
(to clear the remainder packets in BTS buffer)
Virtual Soft Handoff
1. DRCCover = 1, BTS1 is the serving sector. BSC sends packets to BTS1 and BTS1
sends packets to AT.
2. When AT moves to BTS2, DRCCover change to 2, i.e. BTS becomes serving sector.
3. BTS2 requests BSC
to send packets to it,
while BTS1 requests
BSC to stop sending
packets, and tells
BSC the last packet
number it sent.
4. So, BSC turns to
BTS2, and BTS2
begin to send traffic
data to AT.
5. BTS1 clear its buffer
for handoff back
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Case – imbalance of forward and reverse link (Romania)
In soft handoff, a branch maybe has best forward link but not best
reverse link. Maybe caused by high site, different tx power, reverse
interference. For example: forward link of AP1 is better than AP2, but reverse link of
AP2 is better.
1. Only AP1 in the active set. C/I of AP1 is 3dB, its reverse link is not good, but
power control can increase the AT’s power. DRC channel is OK!
2. When AP2 added, it will indicate AT to decrease its power. And AP1 can lock
DRC channel. The serving sector will switch to AP2.
AP1 AP2
DRC ok!
AT
AP1
AT
DRC ok!
Tx = 10dBm
C/I = 3dBAP1 can
not lock DRC
Tx = 0dBm
C/I = 3dBC/I = 0dB
DRC = 921.6kbps DRC = 614.4kbps
try best to avoid
this situation
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Keep Alive
AN will check periodically (default
period is 54/3 hours, MOD DOGCNP)
whether AT is alive or not. If not, the
session will be closed. In idle (with session without
connection), AN and AT use keepalive
message to shake hand with each
other. In connection state, AN will send TCA
to check AT alive or not.
connection established
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Hybrid Access Terminal
Hybrid AT Rulers: A HAT supports operation on both IS-2000(1x) and IS-856(EVDO)
network. With only one antenna/transceiver, it operates in a time-multiplexed
fashion referred to hybrid mode. If acquired 1x network only: In idle or dormant data session on 1x, HAT
periodically attempt to acquire EVDO. If acquired EVDO network only, In idle or dormant data session on EVDO
system, HAT periodically attempt to acquire 1x. If acquired both networks, In idle on both IS-856 and IS-2000 systems,
dormant data session should be on EVDO system. A HAT performs 1x idle state slotted operation regardless of whether the
hybrid access terminal is idle, dormant, or active on EVDO network. For handoff between 1x and EVDO network, the IMSI registered in AN-
AAA should be same as IMSI registered in HLR.
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HAT Acquire Network
HAT first acquires 1x, then EVDO.
When acquiring 1x, accessing 1x,
or active in 1x, HAT does not
monitor EVDO.
When accessing EVDO, HAT
does not monitor 1x.
In 1x sleep state,
HAT monitor
EVDO.
In EVDO sleep
state, HAT
monitor 1x.
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HAT Monitor 1x & DO in Dormant or Idle
In idle, hybrid AT monitors both 1x and DO network in slot mode. To ensure that mobile-terminated 1x services can be supported whenever
an 1x network is available, a hybrid AT performs 1x idle state slotted
operation regardless of whether the hybrid AT is idle, dormant, or active
on an EVDO network. In 1x active state, AT will not monitor EVDO network.
5.12s2.56s
1x monitoring slots
DO monitoring slots
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Case - HAT Monitor 1x Paging Channel In EVDO Active
This is a CAIT picture of EVDO from Romania network. In active state of EVDO, AT went to 1x paging channel every 2.56s. Every
time AT send DRC = null to prevent AN from sending packets.
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1x -> DO Dormant Handoff with HRPD Session Already
Hybrid AT moves from 1x only area to EVDO covered area. It prefers EVDO
for data service.
Location
Notification carries
the packet zone id,
which will be send
to PDSN. A9 setup A8
carries DRS=0, so,
PCF will setup A10
but not setup A8.
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1x -> DO Dormant Handoff without HRPD Session
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DO -> 1x Dormant Handoff
If hybrid AT in DO dormant lose the air link, it will handoff to 1x network. In 1x
dormant, it still search DO network periodically. But, after re-active in 1x, it will lock on 1x continuously.
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Case – why the EVDO only get 70kbps? (Nigeria)
The average rate in 1x network is 50-70kbps.
When Hybrid AT moves from 1x+DO area to 1x only area, it will dormant
handoff from EVDO to 1x network. Its data speed should be much less
than EVDO. But user does not know the fact and complain it.
AT dialing software or phone screen should give some indication to user.
1x + DO
only 1x
AT
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Terminated Voice Call in DO Active State
In DO active state,
hybrid AT still
monitor 1x network
in slot mode.
When AT received
page. It just turns to
1x network without
notifying AN.
Source AN lost air
link, and release
traffic link to
dormant.
Target BSS setup
voice call for AT.
5s
3s
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An Example of Hybrid AT
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Inter-AN Dormant Handoff
UATIRequest carries
the UATI of source
AN.
The first 8 bits of UATI
is the color code of
source AN. So target
AN can find source
AN to request old
session information.
Target AN copy the
old session
configurations and
store them. It is not
necessary to
negotiated again.
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User Signaling Flow Tracing at Local Maintenance Terminal
If you want to trace A12, A13, ESN must be input.
For other interface, IMSI is necessary.
If you want to trace A12, A13, ESN must be input.
For other interface, IMSI is necessary.
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User Signaling Flow Tracing at Local Maintenance Terminal (2)
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Case – some bottlenecks reducing the speed
Abis: in general, 3 sectors of BTS share the bandwidth of Abis. If Abis bandwidth is
not enough, it will limit the download and upload speed directly. A10: in general, A10 bandwidth is enough. But sometimes, it also become a
bottleneck. Landswitch: the active Landswitch of Boise ever fault, some packets sent to it got
lost. It reduce the data speed greatly. After we switch it to backup Landswitch, it
restored. If there are any packets lost at territory link, they will be re-transmitted by TCP. It
will be very harmful to data speed. It is more than air interface, because there is
RLP in the air interface to compensate packet error.
Internet
ftp server
PDSNAN/PCF
Abis
BTS
UmA10/A11
AT
Landswitch2
Landswitch1
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Chapter 1 Why to use 1xEV-DO?Chapter 1 Why to use 1xEV-DO?
Chapter 2 Network StructureChapter 2 Network Structure
Chapter 3 Channel StructureChapter 3 Channel Structure
Chapter 4 Forward LinkChapter 4 Forward Link
Chapter 5 Reverse LinkChapter 5 Reverse Link
Chapter 6 Overhead MessageChapter 6 Overhead Message
Chapter 7 Access ProcedureChapter 7 Access Procedure
Chapter 8 SHO & VSHOChapter 8 SHO & VSHO
Chapter 9 EVDO Procedure FlowChapter 9 EVDO Procedure Flow
Chapter 10 Air Link ParametersChapter 10 Air Link Parameters