Question

How ASN.1 Decoder indicate the presence or absence of an optional field in RRC message? for example in SystemInformationBlockType1 how we figured out if p-Max is presence or not?

Answer 1

first while decoding you should start by checking any optional element is in the type according to 3gpp,if the optional element is present,first bit represents the inclusion or exclusion of optional element,if optional element is included it will be defined by representing with 1,if excluded it will br represented by 0,first all optional elements inclusion or exclusion information will be defined after that the mandatory elements information will be given if no optional element is present according to 3gpp in the data type,then first bit represents the first element