Multiple access system and method for multibeam digital radio systems

• US 7,110,462 B2
• Filed: 04/29/2005
• Issued: 09/19/2006
• Est. Priority Date: 06/01/1999
• Status: Expired due to Fees

• Current Assignee: Peter Monsen
• Original Assignee: Peter Monsen
• Inventors: Monsen, Peter
• Primary Examiner(s): VO, DON NGUYEN
• Application Number:
  US11/118,810
• Publication Number:
  US 20050220057A1
• Time in Patent Office: 508 Days
• Field of Search: 375/260, 375/267, 370/320, 370/329, 370/330, 370335-337, 370341-344, 455/422.1, 455/436, 455/447, 455450-455
• US Class Current: 375/260
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation

Abstract

A multiple-access digital radio communication system and method with communication links between user terminal transmitters and a central node with a receiver system including a multibeam antenna. User terminal transmitters assigned to one beam coverage region use multiple access channels that are mutually orthogonal for transmitting digital message information that is included in a data group. Assignments are random and are changed for successive data groups. The same multiple access channels are reused in adjacent and other beam coverage regions each with an independent random assignment algorithm. Error-correction coding and interleaving are used in the user transmitter and an adaptive processor is used in the receiver. A reference sequence unique to either each user or each beam coverage region is multiplexed into user data groups for transmission. At the receiver the adaptive processor such as an equalizer or sequence estimator is used to combine multiple antenna beam signals to produce a combined signal associated with each user. The combining in the adaptive processor reduces interference from user terminal transmitters associated with different beam coverage regions but with the same multiple access channel. Deinterleaving and error-correction decoding of the combined signal are used to protect against channel assignments with larege mutual interference levels. The communication system can reuse each orthogonal multiple access channel in all of the other beams, i.e., a reuse factor of unity for each multiple access channel.

Claims

1. A method of communicating digital data information from a plurality of user terminal transmitters located in a plurality of antenna beam coverage regions to a receiver with a multibeam antenna, wherein each user terminal transmitter is associated with a beam coverage region, comprising the steps of:

assigning with a random selection a plurality of multiple access channels that belong to a mutually orthogonal set to the plurality of user terminal transmitters within an antenna beam coverage region, and reusing the same multiple access channels with random assignments in adjacent beam coverage regions, and each multiple access channel is 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;

adding, at the user terminal transmitter, error-correction coding to the digital data information to provide coded information;

interleaving, at the user terminal transmitter, the coded information among a plurality of data groups;

inserting in time to each data group, at the user terminal transmitter, a reference signal associated with the beam coverage region of the user terminal transmitter to provide a multiplexed signal;

modulating, at the user terminal transmitter, the multiplexed signal with a multiple access waveform associated with the assigned multiple access channel to provide a multiple access signal;

transmitting, at the user terminal transmitter, the multiple access signal;

receiving, at the multibeam antenna of the receiver, the multiple access signals from the plurality of user terminal transmitters so as to provide a plurality of antenna beam signals;

combining, at the receiver, 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;

deinterleaving and decoding, at the receiver, the combined signal to recover the user terminal transmitter digital data information,

and wherein the assigning step further includes different selections for successive data groups.

2. The method of claim 1 wherein the combining step further includes:

generating a user-identifying replica of the reference signal associated with a user terminal transmitter.

3. The method of claim 2 wherein the combining step further includes:

subtracting the user-identifying replica from the combined signal to provide an error signal;

minimizing the mean square value of the error signal.

4. The method of claim 2 wherein the combining step further includes:

producing a plurality of user-identifying replicas;

correlating combinations of user-identifying replicas with antenna beam signals to provide a plurality of user/beam cross-channel values;

calculating the inner product of cross-channel values and antenna beam signals to provide a plurality of matched antenna beam signals,

converting cross-channel values into equalizer weights;

summing the product of equalizer weights and matched antenna beam signals, thereby producing the combined signal.

5. The method of claim 4 wherein the converting step further includes:

solving a set of simultaneous equations with a Cholskey decomposition.

6. 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 with a random selection a plurality of multiple access channels that belong to a mutually orthogonal set to a plurality of user terminal transmitters in a beam coverage region, and for reusing the same multiple access channels with random assignments in adjacent beam coverage regions, and each multiple access channel is 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 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, and wherein the assignment controller further includes means for changing the selection for successive data groups.

7. A communication system according to claim 6 wherein the summation means further includes:

means for generating a user-identifying replica of the reference signal associated with a user terminal transmitter.

8. A communication system according to claim 6 wherein the summation means further includes:

means for subtracting the user-identifying replica from the combined signal to provide an error signal, and

means for minimizing the mean square value of the error signal.

9. A communication system according to claim 6 wherein the summation means further includes:

means for producing a plurality of user-identifying replicas, and

means for correlating combinations of user-identifying replicas with antenna beam signals to provide a plurality of user/beam cross-channel values, and

means for calculating the inner product of cross-channel values and antenna beam signals to provide a plurality of matched antenna beam signals, and

conversion means for converting cross-channel values into equalizer weights, and

means for summing the product of equalizer weights and matched antenna beam signals, thereby producing the combined signal.

10. A communication system according to claim 9 wherein the conversion means further includes:

means for solving a set of simultaneous equations with a Cholskey decomposition.