METHOD TO ATTACH A MOBILES STATION TO A SECOND GENERATION PACKET NETWORK SHARED BETWEEN DIFFERENT OPERATORS

摘要

The attach of a mobile station (MS) to the packet service provided in a 2nd generation PLMN shared between different network operators is performed through the following steps: a) the MS transmits a request to the radio access network (RAN) to have a packet data channel (PDCH) assigned; b) the RAN assigns to the MS a PDCH and resources for transmitting in uplink; c) the MS provides a temporary identity information element (TLLI), being the mobile station not yet registered to the serving network, a random TLLI is assembled by including three concatenated string of bits: a first heading one stating to the decoder that the logical value of remaining bits are completely random, a second one including the PLMNID code (MCC, MNC), and a third one with all random bits; d) the MS transmits to the core network (CN) a request message to be attached to the packet service, this message contains the TLLI assembled at the previous step; e) the RAN intercepts the attach request message and routes it towards that CN node whose PLMNID corresponds to the one read from the random TLLI included in the intercepted message; f) the target CN node receives the attach request message and decodes the TLLI as being completely random, thus it requests the MS to provide a valid identity.