Motorola Corporation

Karl Anthony Reardon

Thomas Wayne Lockhart

Farzan Mamaghani

Bud Fraser

David Dixon

Geoffrey Richard Scotton

William H Kilner

Nazira Chatur

Richard Mosher

A communication system in which a user device (,) generates authentication information (,) unique to the user device and provides a data packet (,) including this authentication information to an infrastructure part which is a gateway (,) or a host (,). The packet also contains a host identifier (,) or time dependent information (,). This is used at the gateway (,) or the host (,) to authenticate the packet.

Authentication in a packet data system

An internal network (,) is protected from being overloaded by an excessive number of data packets that originate from a source in an external network (,). In a preferred embodiment, data packet gate (,) receives each incoming data packet and determines whether it came from a trusted source. If it was not from a trusted source, and the number of data packets received recently from the same source exceeds a threshold, then data packets from that source are rejected. Preferably, when incoming data packets from all non-trusted sources exceed another threshold, additional data packets from all non-trusted sources are rejected.

Method for protecting a network from data packet overload

A communications unit (10) with a packet subdivider operable on a data packet (200) and an error detecting code generator. An acknowledgement message (NAK) is generated including error detecting code corresponding to packet portions (210-204) from the packet subdivider, thereby requesting retransmission of packet portions. At an originating unit (100) an error detection code is computed for each portion. The computed second error detection code for each sub-portion is compared with the received first error detection code for that portion. Portions for which corresponding error detection codes do not match are identified as bad portions and are retransmitted (220).

Communications unit and method of communicating having efficient packet

In a data communications system, including an infrastructure arranged to communicate over a data channel with a plurality of data terminals, a method of detecting data decryption errors in a data packet includes receiving an encrypted data packet (213); decrypting the encrypted data packet to provide a decrypted data packet; and comparing a reference value to a portion of the decrypted data packet to determine when a predetermined relationship is satisfied (221).

Methods of detecting decryption errors

In a data communications system operating on a registered data channel and including an infrastructure 100 and a subscriber terminal 115, a method of making a channel exit decision at the subscriber terminal includes: sampling 201 the registered data channel for a time period, preferably a signal time period and a data time each of which may be an adaptable time period to obtain a plurality of quality values, preferably signal values and data quality values; comparing 203, 213 each of the plurality of quality values to a threshold; and initiating 225 an exit procedure, preferably including a quick scan for a possible data channel, when a first number of the plurality of quality values obtained during the time period does not satisfy the threshold.

Method of making a channel exit decision in a communication system

In a data communication system (100) including infrastructure (101) arranged to communicate with a plurality of terminals (103) over a channel (109), a method of adaptable channel access practiced at a terminal (103) including determining an access priority value (303), responsive thereto ascertaining when the channel is available (305), and then executing a channel access attempt (307). The access priority value is determined with information received by the terminal or information available to the terminal.

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Surrey, Canada

Karl Anthony Reardon