CD MA MO BILE PACKET DATA S ER VIC E S Mobile P ac ket da ta Ser vice St ate s There are three packet data service states: Active/Connected, Dormant, and Null/Inactive Active/Connected State: In this state, a physical traffic channel exists between the MS and the BS, and either side may send data. Dormant State: In this state, no physical traffic channel exists between the MS and the BS, but the PPP link between the MS and the PDSN is maintained. Null/Inactive State: In this state, there is no traffic channel between the MS and the BS and no PPP link between the MS and the PDSN. Figure 4.1: Block diagram of the packet data service transitions The mobile may cross Packet Zone boundaries while in the Dormant State. This is referred to as Dormant Handoff. The Dormant handoff procedures allow the A10 connections between the PCF and PDSN to be moved (or established) for the mobile when it enters a new packet zone. The mobile may re-enter Active state (e.g., if the user has data to send) at any time. This transition is referred to as Re-Activation from Dormant, and is not related to Dormant Handoff
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CD MA MO BILE PACKET DATA S ER VIC E S
Mobile P ac ket da ta Ser vice St ate s
There are three packet data service states: Active/Connected, Dormant, and
Null/Inactive
Active/Connected State: In this state, a physical traffic channel exists between
the MS and the BS, and either side may send data.
Dormant State: In this state, no physical traffic channel exists between the
MS and the BS, but the PPP link between the MS and the PDSN is maintained.
Null/Inactive State: In this state, there is no traffic channel between the MS and
the BS and no PPP link between the MS and the PDSN.
Figure 4.1: Block diagram of the packet data service transitions
The mobile may cross Packet Zone boundaries while in the Dormant State. This is
referred to as Dormant Handoff. The Dormant handoff procedures allow the A10
connections between the PCF and PDSN to be moved (or established) for the
mobile when it enters a new packet zone. The mobile may re-enter Active state
(e.g., if the user has data to send) at any time. This transition is referred to as
Re-Activation from Dormant, and is not related to Dormant Handoff (i.e., Re-
Activation from Dormant is not related to a mobility event). Packet data is typically
transmitted over the air on dedicated traffic channels. Mechanisms also exist for
transmitting data over the common channels. Short Data Burst (SDB) is a part of
the 3G Packet Data feature that enables small amounts of data to be transmitted
over the common channels. Common Channel Packet Data is a mode of 3G Packet
Data where all data is transmitted using Short Data Bursts. A1 and A8
connections are maintained during the Active / Connected State and released
during transition to Dormant or
Null/Inactive State. The A10 connection is maintained during the Active/Connected
and the Dormant State.
Figure 4.2: Schematic diagram of the packet data service states
As shown in figure 4.2 above, a mobile in the Null state will need to setup traffic
channel on the Um, Abis, A8 and A10 interface to get to the Active state. Similarly, a
mobile in the Active state will need to release traffic channels on the Um, Abis
and A8 interface to get to the Dormant state. Furthermore a mobile in the
Dormantstate will need to release the traffic channel on the remaining A10
interface to get to the Null state again
Call f lo w C DMA2000 – 1x ( da ta )
The main difference between the CDMAOne and CDMA2000 call flow is that, in
CDMA2000 the mobile initiates the decision as to whether the session will be a
packet data session, voice session, or concurrent (meaning voice and data). After
the decision has been made, the mobile sends an origination message on the
access channel that includes an indication that this is a voice or packet data
session.
In this section we will be dealing with Packet data call flow
Figure 4.3: CDMA2000 voice/data call flow
Co nsid erin g the P a cket s witc h cor e netw or k d om ain
Call scenarios CDMA2000 – 1x (data) – aExample: A mobile accessing a web server.
Figure 4.4: CDMA2000 data call flow diagram - (a)
The mobile initiates the decision as to whether the session will be a packet data session, voice
session, or concurrent (meaning voice and data).
After the decision has been made, the mobile sends an origination
message that includes an indication that this is a voice data session.
The RAN informs the MSC, and the MSC performs an authentication
procedure similar to the circuit switched authentication process.
Finally, the BSC and BTS allocate radio resources and establish a low data rate
dedicated channel. In contrast to the radio channel used for voice calls, this low
rate data channel uses the Radio Link Protocol (RLP) to provide better error
performance.
The next step is to allocate resources in the new packet switched core network
domain.
Call scenarios CDMA2000 – 1x (data) - (b)
Figure 4.5: CDMA2000 data call flow diagram - (b)
The next step in establishing the packet data session is to allocate resources on
the Radio – Packet (R-P) interface.
Once resources have been established, the mobile communicates with the
PDSN over the allocated channels in order to set up a Point-to-Point Protocol
(PPP) connection.
During this process, the packet switched core network, specifically the PDSN,
assigns an Internet Protocol (IP) address to the mobile station.
Call scenarios CDMA2000 – 1x (data) - (c)
Figure 4.6: CDMA2000 data call flow diagram - (c)
Before completing the PPP connection, there is another level of authentication.
Authentication has already been performed from a wireless access perspective,
now it will be performed based on the Internet service.
The PDSN talks to the AAA server using the Remote Access Dial-In
User Service (RADIUS) protocol to authenticate the user. Authorization to
access the requested service is based on the subscriber profile stored in the
AAA. If authorization is successful, the mobile is granted access to the IP
network.
AT Origina tes 1x EV - DO Session -Successful A uthentica tion
Figure 4.7: AT Originates 1xEV-DO Session -Successful Authentication diagram
Figure 4.8: Continuation of figure 4.7
A: The AT sends a UATI-Request message to request that a Unicast Access Terminal
Identifier (UATI) be assigned to it by the AN.
B: The AN sends a UATI-Assignment message to assign a UATI to the AT.
C: The AT sends a UATI-Complete message to notify the AN that it has received the
UATI-Assignment message.
D: If no session exists between the AT and AN, a session is established where
protocols and protocol configurations are negotiated, stored and used for
communications between the AT and the AN.
E: The AT indicates that it is ready to exchange data on the access stream (e.g.,
the flow control protocol for the default packet application bound to the AN is in
the open state).
F: The AT and the AN initiate Point-to-Point Protocol (PPP) and Link Control Protocol
(LCP) negotiations for access authentication.
G: The AN generates a random challenge and sends it to the AT in a Challenge