Multiple access system and method for multibeam digital radio systems

A communication system for communicating digital data information from a plurality of user terminal transmitters located in a plurality of antenna beam coverage regions to a multibeam antenna in a receiver at a central node, wherein each user terminal transmitter is associated with a beam coverage region, comprising:

• assignment controller, associated with the central node, for assigning a plurality of multiple access channels that belong to a mutually orthogonal set to the plurality of user terminal transmitters, each multiple access channel being associated with a reuse factor, which is defined by the number of user terminal transmitter assignments in different beam coverage regions divided by the total number of beam coverage regions, and at least one multiple access channel is reused in all beam coverage regions so that its reuse factor is unity;
• and
• user terminal transmitter, disposed at the user terminal, for transmitting digital data information in a multiple access signal to the receiver comprising:
• means for adding error-correction coding to the digital data information to provide coded information, and
• means for interleaving the coded information among a plurality of data groups, and
• means for inserting in time to each data group a reference signal associated with the beam coverage region of the user terminal transmitter to provide a multiplexed signal, and
• modulation means for modulating the multiplexed signal to a single radio-frequency axis with a multiple access waveform associated with the assigned multiple access channel to provide a multiple access signal;
• and
• receiver, disposed at the central node, for receiving at the multibeam antenna the multiple access signals from the plurality of user terminal transmitters so as to provide a plurality of antenna beam signals, comprising:
• summation means for combining the antenna beam signals to provide a combined signal associated with a user terminal transmitter, thereby reducing interference from user terminal transmitters assigned to different beam coverage regions, and
• means for deinterleaving and decoding the combined signal to recover the user terminal transmitter digital data information.

A method for receiving and processing digital information transmitted from a plurality of user terminals, located in plural beam coverage areas, at a central node have a receiver and an associated multibeam antenna that produces the plural beam coverage areas, and each user terminal transmits a user-identifying reference and digital data information that is error-corrected coded and interleaved in a single-axis modulated signal associated with a multiple access channel that belongs to a mutually orthogonal set to the receiver, comprising the steps of:

• assigning a multiple access channel to a first user terminal in a first beam coverage region and assigning the same multiple access channel to a second user terminal in a second beam coverage region and the user/beam cross-channel attenuation between the first and second user terminals is unrestricted;
• receiving, at the multibeam antenna, the single-axis modulated signals from the first and second user terminals so as to provide a plurality of antenna beam signals;
• generating a user-identifying replica of the reference signal associated with the first user terminal;
• processing the antenna beam signals and the user-identifying replica to provide a combined signal associated with the first user terminal, thereby reducing interference from the second user terminal;
• deinterleaving and decoding the combined signal to recover the first user terminal digital information.

A central node with a receiver including a multibeam antenna, which produces beam coverage areas in which a plurality of user terminals are located and each user terminal transmits a user-identifying reference and digital data information that is error-corrected coded and interleaved in a single-axis modulated signal associated with a multiple access channel that belongs to a mutually orthogonal set to the receiver, comprising:

• means for assigning a multiple access channel to a first user terminal in a first beam coverage region and assigning the same multiple access channel to a second user terminal in a second beam coverage region and the user/beam cross-channel attenuation between the first and second user terminals is unrestricted, and
• means for receiving, at the multibeam antenna, the single-axis modulated signals from the first and second user terminals so as to provide a plurality of antenna beam signals, and
• generating means for generating a user-identifying replica of the reference signal associated with the first user terminal, and
• processing means for processing the antenna beam signals and the user-identifying replica to provide a combined signal associated with the first user terminal, thereby reducing interference from the second user terminal, and
• means for deinterleaving and decoding the combined signal to recover the first user terminal digital information.