Cellular packet data arrangement

A method of handling packet data communications with a plurality of mobile data terminals in a cellular packet data arrangement comprising a packet data interface unit having a distributed processing architecture including a network interface unit (NIU) for interfacing with a packet data network, a plurality of link interface units (LIUs) each for interfacing with a plurality of channels for communicating data packets with mobile data terminals via respective radio transceivers, and a bus system interconnecting the NIU and the LIUs, comprising the steps of:

• storing in the NIU an individual identifier (TEI) for each mobile data terminal having communications handled by an LIU with an indication of the LIU handling communications for that TEI;
• in each LIU, storing the TEl of each mobile data terminal having communications handled by that LIU with an indication of the channel for those communications, and storing protocol data relating to the communications for that TEI;
• in response to an LIU receiving communications on a new channel from a mobile data terminal having a TEI stored in the LIU with an indication of a different channel, changing the indication of the channel for the communications for that TEI to the new channel;
• and
• in response to a first LIU receiving communications from a mobile data terminal having a TEI which is not stored in the first LIU, determining whether the TEI is stored in the NIU with an indication of another, second, LIU and, if so:
• storing the TEI in the first LIU with an indication of the channel of the first LIU on which the communications from the mobile terminal are received;
• transferring the protocol data for the TEI from the second LIU to the first LIU, the transferred protocol data being stored in the first LIU in association with the TEI;
• and
• deleting the stored TEI of the mobile terminal from the second LIU.

An interface unit for a cellular packet data arrangement, the interface unit having a distributed processing architecture including a network interface unit (NIU) for interfacing with a packet data network, a plurality of link interface units (LIUs) each for interfacing with a plurality of channels for communicating data packets with mobile data terminals via respective radio transceivers, and a bus system interconnecting the NIU and the LIUs, wherein:

• each LIU includes a first table for storing an individual identifier (TEI) for each of a plurality of mobile data terminals having packet data communications handled by the LIU, and an indication of the channel on which such communications are communicated, and a second table for storing protocol data for the data packet communications for the TEI;
• the NIU includes a table for storing the TEI of each mobile data terminal having communications handled by any of the LIUs, with an indication of the LIU handling the communications for that TEI;
• and
• the NIU is responsive to a first LIU receiving communications from a mobile data terminal having a TEI which is not stored in the first LIU to determine from its table whether a second LIU has stored protocol data for that TEI, and if so to transfer the stored protocol data from the second LIU to the first LIU.