RE: [Asn1] Does anyone make sense of CSN.1?

chao_zhao Mon, 17 Jul 2006 23:50:14 -0700

Hello Sethuraman,

Thanks a lot!

Perfect answer to my quesiton.

Chao

From: G Sethuraman [mailto:[EMAIL PROTECTED]
Sent: Tuesday, July 18, 2006 1:54 PM
To: [EMAIL PROTECTED]; [email protected]
Subject: Re: [Asn1] Does anyone make sense of CSN.1?

Hi,

The exact decoding of the input IE that you had mentioned will be something like this

0x48, 0x74, 0x7E - Input

0100 1000   - 0x48
0111 0100   - 0x74
0111 1110   - 0x7E

All values interpreted are in decimal

0100 1           - Channel Type - Value 9
                   0 1 T T T SDCCH/8 + SACCH/C8 or CBCH(SDCCH/8)
      000        - Timeslot Number - Value 0
011              - Training Sequence Code - Value 3
   1             - Message Escape - Implies direct encoding of hopping RF channel configuration
     0100
01               - MAIO - Value 17
11 1110        - HSN - Value 62

To answer your question about MSB and LSB, the CSN1 decoding is done from left to right as you write the bit level representation of the hex code.

For ex : 0x48 would be 0100 1000 in bit level. For Packet Channel Description, this would be interpreted as

0100 1 - Channel Type
000 - TN

Hope this helps.

Best Regards
Sethuraman G

-----------------------
[EMAIL PROTECTED]
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----- Original Message ----
From: [EMAIL PROTECTED]
To: [email protected]
Sent: Tuesday, July 18, 2006 10:57:06 AM
Subject: [Asn1] Does anyone make sense of CSN.1?

Hello,

Maybe this is not a good question to ASN.1 post.

I had a trouble to read some CSN.1 source from 3GPP spec. CSN.1 is new to me. Here is one sample code which is described by CSN.1 for Packet Channel Description of 3 octets length. I know each IE definition. But I don’t know where it start from and where to end from in bit level. I searched CSN from internet and didn’t get what I want. So I post it here for help.

For following sample, one set of hex code is given as {0x48, 0x74, 0x7E }. How can I interpret it in bit level? For example, where does the fist item <channel type : bit(5)>, which is one 5 bits long item, start from (LSB/MSB of which octet)?

Any of your help will be appreciated!

--Packet channel description CSN.1

< Packet Channel Description > ::=

< Channel type : bit (5) >

< TN : bit (3) >

< TSC : bit (3) >

{ 0

{ 0 < spare bit >

< ARFCN : bit (10) > -- non-hopping RF channel configuraion

| 1 < spare bit >

< MAIO : bit (6) > -- indirect encoding of hopping RF channel configuration

< MA_NUMBER_IND : bit >

{ 0 < spare bits : bit (2) >

| 1 < CHANGE_MARK_1 : bit (2) >

}

| 1

< MAIO : bit (6) > -- direct encoding of hopping RF channel configuration

< HSN : bit (6) >

};

--End of Packet channel description

Best regards

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RE: [Asn1] Does anyone make sense of CSN.1?

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