Abstract: The present invention provides a unique access control scheme for assigning a plurality of time slots in a fair manner among subscriber units using a single time slot in a frame and subscriber units using multiple time slots in a frame in a communication system.

Abstract: Collision avoidance is maximized by placing collision avoidance scheduling in a central access manager. The central access manager coordinates downlink transmissions of a base site with the uplink transmissions by subscriber units, virtually avoiding collisions of the two types of transmissions. The subscriber units utilize a waiting period prior to transmission of packets to permit the central access manager to maintain the scheduling.

Abstract: The present invention provides a method and system of statistical estimation of uplink traffic using a retry count. A unique spread factor is used for spreading retransmission evenly among backlogged subscriber units, thereby providing dynamic control of the retransmission spread based on the estimated uplink traffic.

Abstract: The method reduces transmission delay by using a selective-repeat automatic repeat request, ARQ, error detection scheme in a packet-switched data communication system. The invention provides a method for a subscriber unit to transmit acknowledgment information using a contention-free channel access scheme in addition to providing for a base site control unit to interrupt a packet currently being transmitted in order to retransmit segments of the packet when the segments have errors.

Abstract: Radio frequency based cellular telecommunication systems often require both subscriber units and communication units of a fixed network communication system to maintain secret data which may be used to verify authenticity as well as provide encrypting variables for message encryption processes. An efficient real-time authentication method and apparatus are provided which use a single message to provide authentication and communication link setup information. Further, an authentication method and apparatus are provided which uses instant-specific information such as a time of day, radio frequency carrier frequency, a time slot number, a radio port number, access manager identifier, a radio port control unit identifier, or a base site controller identifier to enhance the reliability of the authentication process.

Abstract: Data transmission with bit synchronism over an unreliable channel is accomplished by assigning a unique number to each data byte transmitted in a data packet. From this unique number, each data bit may be identified at the packet receiver. When a data packet is missing or uncorrected, the missing data bits are identified and a fill data bit is supplied to the data sink at the time each missing data bit would have been supplied.

Abstract: A method and apparatus for providing cryptographic protection of a data stream are described in accordance with the Open Systems Interconnection (OSI) model for a communication system. This cryptographic protection is accomplished on the transmitting side by assigning a packet sequence number to a packet derived from a data stream received from a network layer. Subsequently, a transmit overflow sequence number is updated as a function of the packet sequence number. Then, prior to communicating the packet and the packet sequence number on a physical layer, the packet is encrypted as a function of the packet sequence number and the transmit overflow sequence number. On the receiving side, the packet sequence number is extracted from the physical layer. In addition, a receive overflow sequence number is updated as a function of the packet sequence number. Finally, the encrypted packet is decrypted as a function of the packet sequence number and the receive overflow sequence number.

Abstract: A radiotelephone data transfer apparatus connects peripheral devices external to the radiotelephone and other user information inputting devices, such as a handset for a cellular mobile radiotelephone, to the radiotelephone's central processor and speech processor. The data bus apparatus generates frame formats in which the information is sent over the data bus. The frame formats are further subdivided into time slots, the time intervals in which individual messages are sent. The data transfer apparatus is configured so that messages sent to the cellular radiotelephone's speech processor are not flow controlled, while messages sent to the radiotelephone's central processor are flow controlled. Further, the radiotelephone's central processor controls operation of peripheral devices attached to the radiotelephone.