Basic Call Processing - Typical Packet Call                  Home : www.sharetechnote.com

 

 

Big Picture First

 

Depending on which level you are working on in UE development/Test procedure, the amount of knowledge you need to know would be different. But I think there are a couple of big pictures that may help almost anybody working in full protocol stack.

 

First big picture I would like to introduce is the channel mapping as shown below. Just try to pick any RRC messages and try to follow the arrow for the message. If you read those pages about MAC and RLC, it will remind you of a lot of detailed information.

 

<< Overall Sequence and Layer Mapping >>

 

Following is a sequence diagram showing not only the message but also basic configurations of each layer. More detailed description of each layer in the context of full protocol stack will be explained in "Full Stack" section.

 

Just read through this sequence whenever you have time until you can duplicate the sequence without looking into this again. This can be a good framework for your study and good guide for troubleshooting.

 

Step

Direction

Channel

Message

1

UE <---- NW

BCCH -> BCH,

No MAC Header, RLC TM, No PDCP

MIB

2

UE <---- NW

BCCH -> DL SCH,

No MAC Header, RLC TM, No PDCP

SIBs

3

UE ----> NW

PRACH -> RACH,

No MAC Header, No RLC, No PDCP

PRACH Preamble

4

UE <---- NW

RACH -> DL SCH,

No MAC Header, No RLC, No PDCP

RACH Response

5

UE ----> NW

UL SCH -> UL CCCH

MAC Header, No RLC, No PDCP

RRC Connection Request

6

UE <---- NW

DL CCCH -> DL SCH

MAC Header, No RLC, No PDCP

RRC Connection Setup

7

UE ----> NW

UL SCH -> UL DCCH

MAC Header, RLC AM, PDCP

RRC : RRC Connection Setup Complete +

NAS : Attach Request (ESM:PDN Connectivity Request)

8

UE <---- NW

DL DCCH -> DL SCH

MAC Header, RLC AM, PDCP

RRC : dlInformationTransfer

EMM : Authentication Request

9

UE ----> NW

UL SCH -> UL DCCH

MAC Header, RLC AM, PDCP

RRC : ulInformationTransfer

EMM : Authentication Response

10

UE <---- NW

DL DCCH -> DL SCH

MAC Header, RLC AM, PDCP

RRC : dlInformationTransfer

EMM : Security Mode Command

11

UE ----> NW

UL SCH -> UL DCCH

MAC Header, RLC AM, PDCP

RRC : ulInformationTransfer

EMM : Security Mode Complete

12

UE <---- NW

DL DCCH -> DL SCH

MAC Header, RLC AM, PDCP

RRC : Security Mode Command

13

UE ----> NW

UL SCH -> UL DCCH

MAC Header, RLC AM, PDCP

RRC : Security Mode Complete

14

UE <---- NW

DL DCCH -> DL SCH

MAC Header, RLC AM, PDCP

RRC : RRC Connection Reconfiguration

EMM : Attach Accept

ESM : Activate Default EPS Bearer Context Request

15

UE ----> NW

UL SCH -> UL DCCH

MAC Header, RLC AM, PDCP

RRC : RRC Connection Reconfiguration Complete

16

UE ----> NW

UL SCH -> UL DCCH

MAC Header, RLC AM, PDCP

RRC : ulDirectTransfer

EMM : Attach Complete

ESM : Activate Default EPS Bearer Context Accept

17

UE <---- NW

DL DCCH -> DL SCH

MAC Header, RLC AM, PDCP

RRC : RRC Connection Release

 

 

<< Downlink Channel Map >>

 

The diagram you saw above a kind of message flow(event diagram) in time sequence. The diagram shown below is not a time based, but it shows the channel mapping (or data flow across the full protocol stack). Pick one of the message from the diagram shown above and try to find right route for this digram and see how much details you can add.

For example, if you picked the message "RRC Connection Setup", the start point would be "RRC Message msg4".

 

 

Following is a tabular presentation of DL Channel Map. (LCID and TrCH Number would be different depending on the network or Network Simulator)

 

RB

Lo CH

PDCP

RLC

Lo CH

LCID

MAC Hdr

HARQ

RNTI

Tr CH

 

PCCH

 

TM

PCCH

N/A

NONE

NONE

NONE

PCH

 

BCCH 0

 

TM

BCCH 0

N/A

NONE

NONE

NONE

BCH 0

 

BCCH 1

 

TM

BCCH 1

N/A

NONE

Broadcast

SI RNTI

DL SCH 0

 

RA_RES

 

TM

RA_RES

N/A

NONE

NONE

RA RNTI

DL SCH 1

SRB0

DL CCCH

USED

TM

DL CCCH

0

NONE

NORMAL

T-CRNTI

DL SCH 1

SRB1

DL DCCH 0

USED

AM

DL DCCH 0

1

NORMAL

NORMAL

CRNTI

DL SCH 1

SRB2

DL DCCH 1

USED

AM

DL DCCH 0

2

NORMAL

NORMAL

CRNTI

DL SCH 1

DRB 0

DL DTCH0

USED

 UM/AM

DL DTCH0

3

NORMAL

NORMAL

CRNTI

DL SCH 1

DRB 1

DL DTCH1

USED

 UM/AM

DL DTCH1

4

NORMAL

NORMAL

CRNTI

DL SCH 1

DRB 2

DL DTCH2

USED

 UM/AM

DL DTCH2

5

NORMAL

NORMAL

CRNTI

DL SCH 1

 

 

<< Uplink Channel Map >>

 

Following is a tabular presentation of DL Channel Map. (LCID and TrCH Number would be different depending on the network or Network Simulator)

 

RB

Lo CH

PDCP

RLC

Lo CH

LCID

MAC Hdr

HARQ

RNTI

Tr CH

 

RA_PRE

 

TM

RA_PRE

N/A

NONE

NONE

NONE

UL SCH 0

SRB0

UL CCCH

USED

TM

UL CCCH

0

NONE

NORMAL

T-CRNTI

UL SCH 0

SRB1

UL DCCH 0

USED

AM

UL DCCH 0

1

NORMAL

NORMAL

CRNTI

UL SCH 0

SRB2

UL DCCH 1

USED

AM

UL DCCH 0

2

NORMAL

NORMAL

CRNTI

UL SCH 0

DRB 0

UL DTCH0

USED

 UM/AM

UL DTCH0

3

NORMAL

NORMAL

CRNTI

UL SCH 0

DRB 1

UL DTCH1

USED

 UM/AM

UL DTCH1

4

NORMAL

NORMAL

CRNTI

UL SCH 0

DRB 2

UL DTCH2

USED

 UM/AM

UL DTCH2

5

NORMAL

NORMAL

CRNTI

UL SCH 0

 

 

Channel Mapping Table throughout Call Processing

 

This is only an example case and Mapping (especiall LoCH No) can vary depending on situations. The point is that it will be really helpful for your troubleshooting or test case creation if you create this kind of table for your case.

 

Message

RB

Lo CH

LoCH No

LCID

MIB

-

BCCH

0

-

SIB 1

-

BCCH

1

-

SIB 2

-

BCCH

1

-

RRC : PRACH Preamble

-

-

-

-

RRC : RACH Response

-

-

-

-

RRC : RRC Connection Request

SRB0

UL CCCH

0

0

RRC : RRC Connection Setup

SRB0

DL CCCH

0

0

RRC : RRC Connection Setup Complete + NAS : Attach Request + ESM : PDN Connectivity Request

SRB1

UL DCCH

0

1

RRC : DL Information Transfer + NAS : Authentication Request

SRB1

DL DCCH

0

1

RRC : UL Information Transfer + NAS : Authentication Response

SRB1

UL DCCH

0

1

RRC : DL Information Transfer + NAS : Security Mode Command

SRB1

DL DCCH

0

1

RRC : UL Information Transfer + NAS : Security Mode Complete

SRB1

UL DCCH

0

1

RRC : Security Mode Command

SRB1

DL DCCH

0

1

RRC : Security Mode Complete

SRB1

UL DCCH

0

1

RRC : RRC Connection Reconfiguration

SRB1

DL DCCH

0

1

RRC : RRC Connection Reconfiguration Complete

SRB1

UL DCCH

0

1

RRC : UL InformationTransfer + NAS : Attach Complete + NAS : Activate Default EPS Bearer 

SRB2

UL DCCH

1

2

RRC : UL Information Transfer + ESM : PDN Connectivity Request

SRB2

UL DCCH

1

2

 

Note : Refer to TS 36.331 - 9.1.1 Logical channel configurations

 

 

Cell Configuration and Channel Configuration during Call Processing

 

Config 1) Activate Cell Physicall Layer

1) MIB

Config 2)  Activate PHY, MAC, RLC for SIB Transmission (BCCH-DL DSCH)

2) SIB 1

3) SIB 2

Config 3) Configure PHY, MAC for PRACH Reception and RACH Response Transmission

4) RRC : PRACH Preamble

5) RRC : RACH Response

Config 3) Configure PHY, MAC, RLC for Msg3 (RRC Connection Request) Reception (UL-CCCH)

6) RRC : RRC Connection Request

Config 4) Configure MAC, RLC, PDCH for DL DCCH, UL DCCH

7) RRC : RRC Connection Setup

8) RRC : RRC Connection Setup Complete + NAS : Attach Request + ESM : PDN Connectivity Request

9) RRC : DL Information Transfer + NAS : Authentication Request

10) RRC : UL Information Transfer + NAS : Authentication Response

11) RRC : DL Information Transfer + NAS : Security Mode Command

12) RRC : UL Information Transfer + NAS : Security Mode Complete

Config 5) Configure PDCP for Integrity, Ciphering (We may disable Integiry/Ciphering for some test environment)

13) RRC : Security Mode Command

14) RRC : Security Mode Complete

15) RRC : RRC Connection Reconfiguration + NAS : Attach Accept + NAS : Activate Default EPS Bearer Context Req

Config 6) Configure MAC, RLC, PDCP for DL/UL DTCH+DCCH

16) RRC : RRC Connection Reconfiguration Complete + NAS : Attach Complete + NAS : Activate Default EPS Bearer Context Accept

17) RRC : RRC Connection Release

Config 7) Deactivate all the channels related to DCCH, DTCH

 

Config 8) Activate channels for PCCH

< MO or MT call > : In MT call, Paging should be sent.

Config 9) Configure PHY, MAC for PRACH Reception and RACH Response Transmission

18) RRC : PRACH Preamble

19) RRC : RACH Response

Config 10) Configure PHY, MAC, RLC for Msg3 (RRC Connection Request) Reception (UL-CCCH)

20) RRC : RRC Connection Request

Config 11) Configure MAC, RLC, PDCH for DL DCCH, UL DCCH

21) RRC : RRC Connection Setup

22) RRC : RRC Connection Setup Complete + NAS : Service Request

23) RRC : Security Mode Command

24) RRC : Security Mode Complete

25) RRC : RRC Connection Reconfiguration + NAS : Activate Dedicated EPS Bearer Context Request

Config 12) Configure MAC, RLC, PDCP for DL/UL DTCH+DCCH

26) RRC : RRC Connection Reconfiguration Complete + NAS : Activate Dedicated EPS Bearer Context Accept

27) RRC : RRC Connection Release