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| | |-+  Encoding/Decoding of Picture msgs,ringtones in CDMA
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Author Topic: Encoding/Decoding of Picture msgs,ringtones in CDMA  (Read 720 times)
Satya71
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« on: October 16, 2006, 07:02:16 UTC »

whats the difference in Encoding/Decoding of picturemsgs / ringtones when compared to ordinary text messages incase of SMSC supporting CDMA
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shad
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« Reply #1 on: October 16, 2006, 17:19:38 UTC »

Hi Satya

Good question! I wish I knew the answer  Smiley

One way is to use the GSM EMS encoding, called WEMT in CDMA. Below is a sample of a short message sent including a sound. The Teleservice ID (not shown) is set to WEMT (4101). The HEADER_IND field is set to 1, indicating the presence of the GSM User Data Header (as defined in 3GPP TS 23.040 section 9.2.3.24). Although the trace program says "Bytes" for the User Data, they are actually 7-bit fields.

Code:
                  PARAMETER_ID  Bearer Data 
                   PARAMETER_LEN  27 
                   Bearer Data
                     
                     SUBPARAMETER_ID  Message Identifier 
                     SUBPARAM_LEN  3 
                     Message Identifier
                       MESSAGE_TYPE  Submit 
                       MESSAGE_ID  162 
                       HEADER_IND  1
                     SUBPARAMETER_ID  User Data 
                     SUBPARAM_LEN  14 
                     User Data
                       MSG_ENCODING  9 
                       NUM_FIELDS  13 
                       
                       Byte  4 
                       Byte  64 
                       Byte  0 
                       Byte  48 
                       Byte  16 
                       Byte  4 
                       Byte  2 
                       Byte  11 
                       Byte  1 
                       Byte  0 
                       Byte  32 
                       Byte  24 
                       Byte  0 
                     SUBPARAMETER_ID  Priority Indicator 
                     SUBPARAM_LEN  1 
                     Priority Indicator
                       PRIORITY  Normal 
                     SUBPARAMETER_ID  Reply Option 
                     SUBPARAM_LEN  1 
                     Reply Option
                       USER_ACK_REQ  0 
                       DAK_REQ  1 
                       READ_ACK_REQ  0 

The User Data header is encoded in octets as follows:
Code:
09 Length of User Data Header
00 Information Element Identifier: "Concatenated short messages, 8-bit reference number"
03 Length of Information Element
02 Concatenated short message reference number
01 Maximum number of short messages in the concatenated short message
01 Sequence number of the current short message
0B Information Element Identifier: "Predefined Sound"
02 Length of Information Element
01 Play sound after 1st character
01 Sound #1 = "Chimes low"

The remaining 11 bits of the User Data should be made up of 4 bits padding to align the (octet-encoded) User Data Header with a septet boundary, followed by 7-bits for the 1-character text in the message. Unfortunately I can't decode the actual text itself - it doesn't seem to be using the GSM default aphabet, and repeating the same character in the message doesn't repeat the same sequence of bits... Sad. Anyone who can help please let me know...

-shad
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Satya71
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« Reply #2 on: October 20, 2006, 09:35:13 UTC »

thanks for the info shad
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