3GPP Opeartion and PDU formats

There are many variation of PDU formats specified by the various 3GPP Protocols. All supported 3GPP operations and data formats are described below:

GSM:
Supported PDU types:
 

                      0 1 2 3 4 5 6 7 
                     +-+-+-+-+-+-+-+-+
                     |               |
                     + IV (8/16byte) |
                     |               |          
                   +>+-+-+-+-+-+-+-+-+
                   | |               | 
                   | |               |
                   | |     Data      |               
                   | |               | 
                   | |               | 
                   | +-+-+-+-+-+-+-+-+
                   |
                   |-> Ciphering Unit
 
                   Figure 1.  Ciphering Unit of a GSM PDU.      
    
Ciphering algorithm: GSM A5/3, ECSD A5/3, GAE3, Kasumi-F8
Key Stream Generation:
  • Input to SA: 64-bit IV plus all zero payload
  • Output from SA: 64-bit IV plus key stream (228 bit for GSM A5/3, 696 bit for ECSD A5/3, varialbe length for GAE3)
Full Encryption/Decryption:
  • Input to SA: 64/128-bit IV plus payload
  • Output from SA: 64/128-bit IV plus encryped/decrypted paylaod
WCDMA:
Supported PDU types:
 
  
                      0 1 2 3 4 5 6 7 
                     +-+-+-+-+-+-+-+-+
                     |DC|  Seq Num   |
                     +-+-+-+-+-+-+-+-+
                     |Seq Num  |P| HE|                  
                   +>+-+-+-+-+-+-+-+-+
                   | | Length Ind. |E|          
                   | +-+-+-+-+-+-+-+-+
                   | |               | 
                   | |               |
                   | |     Data      |               
                   | |               | 
                   | |               | 
                   | +-+-+-+-+-+-+-+-+
                   | | PAD or piggy-backed STATUS PDU                
                   | +-+-+-+-+-+-+-+-+
                   |
                   |-> Ciphering Unit
 
 
                   Figure 2.  Ciphering Unit of a WCDMA AMD PDU.
 
 
                      0 1 2 3 4 5 6 7 
                     +-+-+-+-+-+-+-+-+
                     | Seq Num     |E|
                   +>+-+-+-+-+-+-+-+-+
                   | | Length Ind. |E|          
                   | +-+-+-+-+-+-+-+-+
                   | |               | 
                   | |               |
                   | |     Data      |               
                   | |               | 
                   | |               | 
                   | +-+-+-+-+-+-+-+-+
                   |
                   |-> Ciphering Unit
 
 
                   Figure 3.  Ciphering Unit of a WCDMA UMD PDU.
 
 
                      0 1 2 3 4 5 6 7 
                     +-+-+-+-+-+-+-+-+
                     |               |
                     |   Count-C     |
                     |   (4-byte)    |
                     |               |          
                   +>+-+-+-+-+-+-+-+-+
                   | |               | 
                   | |               |
                   | |     Data      |               
                   | |               | 
                   | |               | 
                   | +-+-+-+-+-+-+-+-+
                   |
                   |-> Ciphering Unit
 
                   Figure 4.  Ciphering Unit of a WCDMA TMD PDU.
    
Ciphering algorithm: Kasumi/F8,Snow 3G/F8, AES-CTR
From Air Traffic (Decryption) :
  • Input to SA:
    • PDU header plus payload for RLC AMD/UMD PDU
    • Payload with 32-bit Count-C in the CPPI header for TMD MAC PDU
  • Output from SA:
    • PDU header plus decrypted payload for RLC AMD/UMD PDU
    • Decrypted payload for TMD MAC PDU
To Air Traffic (Encryption) :
  • Input to SA:
    • PDU header plus payload for RLC AMD/UMD PDU
    • Payload for TMD MAC PDU
  • Output from SA:
    • PDU header plus encrypted payload for RLC AMD/UMD PDU
    • 32-bit Count-C plus encrypted payload for TMD MAC PDU
LTE:
Supported PDU types:
 
                      0 1 2 3 4 5 6 7 
                     +-+-+-+-+-+-+-+-+
                     |               |
                     |   Count-C     |
                     |   (4-byte)    |
                     |               |          
                   +>+-+-+-+-+-+-+-+-+
                   | |               | 
                   | |               |
                   | |     Data      |               
                   | |               | 
                   | |               | 
                   | +-+-+-+-+-+-+-+-+
                   |
                   |-> Ciphering Unit
 
                   Figure 5.  Ciphering Unit of a PDCP Data PDU.
 
 
                      0 1 2 3 4 5 6 7 
                     +-+-+-+-+-+-+-+-+ <+
                     |R R R| PDCP SN |  |
                   +>+-+-+-+-+-+-+-+-+  |
                   | |               |  |
                   | |               |  |
                   | |     Data      |  |             
                   | |               |  |
                   | |               |  |
                   | +-+-+-+-+-+-+-+-+  |-> Authentication Unit
                   | |   MAC-I       |
                   | |   (4 byte)    |
                   | +-+-+-+-+-+-+-+-+
                   | 
                   |-> Ciphering Unit
 
                   Figure 6.  PDCP Control Plane Data Uint for SRBs
    
Ciphering algorithm: Snow 3G/F8, AES-CTR Authentication algorithm: CMAC
From Air Traffic (Decryption and/or Authentication verification) :
  • Input to SA:
    • PDCP Data with 32-bit Count-C in the CPPI header for the Data Plane PDU
    • PDCP Header plus Data and MAC-I with 32-bit Count-C in the CPPI header for the Control Plane PDU
  • Output from SA: 32-bit Count-C plus decrypted PDCP PDU Data
    • PDCP Data for the Data Plane PDU
    • PDCP Header plus Data and MAC-I for the Control Plane PDU
To Air Traffic (Encryption and/or Authentication) :
  • Input to SA:
    • PDCP Data for the Data Plane PDU
    • PDCP Header plus Data and MAC-I with 32-bit Count-C in the CPPI header for the Control Plane PDU
  • Output from SA: 32-bit Count-C plus encrypted PDCP PDU Data
    • 32-bit Count-C plus PDCP Data for the Data Plane PDU
    • PDCP Header plus Data and MAC-I for the Control Plane PDU

Copyright 2014, Texas Instruments Incorporated