umts rrc question

[noselasd at fiane.dyndns.org]

On 06/10/2013 06:33 PM, ☎ wrote:
> Hi all.
>
> I've problem reading umts standard etsi ts 125.331 - for example 10.2.11 DOWNLINK
> DIRECT TRANSFER does not specify length of "message type" or "rrc transaction id", it
> only references 10.3.3.36 which do not specify length as well - only "Integer
> (0..3)". Where do I look up the actual bit lengths?
>
> As far as I recall in gsm spec it was given right away.
>
> I've tried to read asn in wireshark/asn1/rrc but got myself only same "Integer
> (0..3)" and attempt to read generated code makes my brain reboot.
>
> I've tried to compile it with erlc and use parsers as is but hit "function not
> exported" - I don't know enough erlang yet to fix this.

The protocol is specified in ASN.1. However ASN.1 can be encoded in 
different ways.
RRC is encoded using unaligned PER , so refer to X.691 and other 
relevant ASN.1 specs.