Abstract: The apparatus (101, 110) and method for authentication is provided by generating R and encrypting it using a selected algorithm K as the key in a primary station, encrypting the verification key, V using R as the key and encrypting the result using K as the key, transmitting both pieces of information (VAR1 and VAR3) to the secondary station (110), using K to decrypt VAR1 and VAR3 to obtain R and eventually V which is encrypted using R in the secondary station (110)verifying authenticity of the primary station (101) if the decrypted V matches the secret key portion of V that is stored at the secondary station (110).

Abstract: The present invention provides a method (400, 500, 600, 700, 800, 900, 1000) and device (1100, 1200, 1300) for contention for channel access to single-slot subscriber units that are capable of transmitting and receiving data on one time slot per TDMA frame, allowing contention for channel access on any one of the available packet time slots and transmission on the time slot where contention is won. Thus, the present invention eliminates a requirement for a subscriber unit to be assigned to a particular time slot for contention, thereby eliminating the problem of performing load balancing on the time slots.

Abstract: A novel scheme efficiently indicates to a plurality of users which user has been granted access to a multi-access packet channel. Transmission and reception of a predetermined limited number of echo bits per timeslot reduces bandwidth usage, and over the duration of a packet, these bits are equivalent to a variable length random identification number which is used for identifying which user has been granted access.

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 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.