Cellular/satellite communications system with improved frequency re-use

• US 5,619,503 A
• Filed: 01/11/1994
• Issued: 04/08/1997
• Est. Priority Date: 01/11/1994
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Dent, Paul W.
• Primary Examiner(s): Hsu, Alpus H.
• Assistant Examiner(s): NGO, RICKY QUOC
• Application Number:
  US08/179,953
• Time in Patent Office: 1,183 Days
• Field of Search: 370/95.1, 370/95.3, 370/100.1, 370/104.1, 375/216, 375/219, 375/295, 375/296, 375/316, 455/49.1, 455/50.1, 455/53.1, 455/54.1, 455/63, 455/296, 455/12.1, 455/13.1, 455/22, 455/20, 379/57, 379/58, 379/59, 379/63
• US Class Current: 370/330
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 1/288 Satellite antennas
• CPC Class Codes: H01Q 21/08 the units being spaced along or adjacent to a rectilinear path waveguide fed H01Q21/0037
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H01Q 25/00 Antennas or antenna systems providing at least two radiating patterns arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00
• CPC Class Codes: H01Q 25/007 using two or more primary active elements in the focal region of a focusing device for operation on different wavebands H01Q5/22
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04B 7/0851 using training sequences or error signal minimizing error signal H04B7/0854
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays
• CPC Class Codes: H04B 7/18532 Arrangements for managing transmission, i.e. for transporting data or a signalling message
• CPC Class Codes: H04B 7/18567 Arrangements for providing additional services to the basic mobile satellite telephony service
• CPC Class Codes: H04B 7/2041 Spot beam multiple access
• CPC Class Codes: H04B 7/2046 SS-TDMA, TDMA satellite switching
• CPC Class Codes: H04L 1/007 Unequal error protection for format H04L1/0078; for codes per se H03M13/35
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/021 Estimation of channel covariance
• CPC Class Codes: H04L 25/03203 Trellis search techniques
• CPC Class Codes: H04L 25/0328 with interference cancellation circuitry adaptations for interference cancellation within a sequence estimator H04L25/03305; interference related aspects of direct sequence spread spectrum H04B1/7097; interference related aspects of frequency hopping spread spectrum H04B1/715; see also H04B1/10
• CPC Class Codes: H04L 25/03299 : with noise-whitening circuitry
• CPC Class Codes: H04L 25/03331 : Arrangements for the joint estimation of multiple sequences
• CPC Class Codes: H04W 16/02 : Resource partitioning among network components, e.g. reuse partitioning
• CPC Class Codes: H04W 16/14 : Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 74/08 : Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 84/025 : with acknowledge back capability
• CPC Class Codes: H04W 84/042 : Public Land Mobile systems, e.g. cellular systems
• CPC Class Codes: H04W 84/06 : Airborne or Satellite Networks space-based or airborne stations H04B7/185

Abstract

The invention relates to a radio communication system and method for minimizing co-channel interference. The system and method employ a matrix processor to separate signals received from, or transmitted to, a plurality of mobile units. The coefficients of the matrix are chosen to minimize interference between channels, and are adjusted periodically to account for changes in the mobile units using the system. The system and methods are applicable to, for example, landmobile communication, satellite communications system and hybrids thereof. In one embodiment, the system rotates the allocation of Digital Voice Color Codes and sector radiation patterns in opposite directions to maintain the same color code in the same absolute direction.

Claims

1. A transmitting apparatus for transmitting a plurality of signals to a plurality of receivers using the same radio frequency channel, comprising:

channel processing means for converting each of said signals to a numerical sample stream representative of a modulated radio wave;

matrix processing means for forming numerical combinations of said numerical sample streams using a set of matrix coefficients;

conversion means for converting said numerical combinations to corresponding analog modulated radio signals on a designated frequency and amplifying said modulated radio signals to a transmit power level;

antenna means, coupled to said conversion means, for transmitting said modulated radio signals; and

control means for selecting or adjusting said matrix coefficients for use by said matrix processing means such that each of said receivers receives an intended one of said plurality of signals with reduced interterence from remaining, unintended signals.

2. A transmitting apparatus for transmitting a plurality of signals to a plurality of receivers using the same radio frequency channel, comprising:

channel processing means for converting each of said signals to a numerical sample stream representative of a modulated radio wave;

matrix processing means for forming numerical combinations of said numerical sample streams using a set of matrix coefficients;

conversion means for converting said numerical combinations to corresponding analog modulated radio signals on a designated frequency and amplifying said modulated radio signals to a transmit power level;

antenna means, coupled to said conversion means, for transmitting said modulated radio signals;

control means for selecting or adjusting said matrix coefficients for use by said matrix processing means to maximize at a worst case receiver a received signal level of an intended one of said plurality of signals relative to a received interference level of the remaining, unintended signals.

3. A receiving apparatus for receiving a plurality of signals transmitted from a plurality of transmitters using the same radio frequency channel and producing a plurality of output signals, comprising:

multiple-element antenna means for receiving said transmitted signals and producing a received signal from each antenna element of said multiple-element antenna;

multi-channel radio-frequency processing means for filtering, amplifying and converting each of said received signals from respective antenna elements into a corresponding numerical sample stream;

numerical matrix processing means for combining said numerical sample streams using a set of matrix coefficients to produce a plurality of separated signals;

channel processing means for processing each of said separated signals to produce said output signals; and

control means for selecting or adjusting said matrix coefficients for use by said matrix processing means such that each of said output signals corresponds to an intended one of said transmitted signals with reduced interference from the remaining, unintended transmitted signals.

4. A receiving apparatus for receiving a plurality of signals from a plurality of transmitters using the same radio frequency channel and producing a plurality of output signals, comprising:

multiple-element antenna means for receiving said transmitted signals and producing a received signal from each antenna element of said multiple-element antenna;

multi-channel radio-frequency processing means for filtering, amplifying and converting each of said received signals from respective antenna elements into a corresponding numerical sample stream;

numerical matrix processing means for combining said numerical sample streams using a set of matrix coefficients to produce a plurality of separated signals;

channel processing means for processing each of said separated signals to produce said output signals; and

control means for selecting or adjusting said matrix coefficients for use by said numerical matrix processing means to maximize agreement between each of said output signals and a respectively intended one of said transmitted signals.

5. A transmitting apparatus for transmitting a plurality of signals to a corresponding plurality of receivers using a plurality of radio channels, comprising:

grouping means for grouping selected ones of said signals into subsets for transmission using a same radio channel for each member of a subset and different radio channels for different subsets;

channel processing means for processing said signals into numerical signals representative of modulated radio signals;

matrix processing means, for each of said subsets, for forming numerical combinations of said signals belonging to the same subset using a set of matrix coefficients for each subset;

conversion means, for each subset, for converting said numerical combinations into corresponding analog modulated radio signals on the radio channel designated for each subset;

a plurality of combining means for combining one of said analog modulated signals from each subset to form an antenna element drive signal and amplifying said antenna element drive signal to a transmit power level;

multiple-element antenna means, wherein each of said antenna elements is coupled to a respective one of said combining means, for transmitting said antenna element drive signals; and

control means for controlling said grouping means and said matrix coefficients such that each of said receivers receives an intended signal at a desired signal strength with reduced interference from the remaining, unintended signals.

6. The transmitting apparatus of claim 5, wherein said control means is also for minimizing a sum of said transmit power levels.

7. A receiving apparatus for receiving a plurality of signals from a corresponding plurality of transmitters using a plurality of radio channel'"'"'s frequencies and producing a plurality of output signals, comprising:

multiple-element antenna means for receiving said plurality of transmitted signals and producing a composite received signal from each antenna element of said multiple-element antenna means;

multi-channel radio frequency processing means for filtering, amplifying, splitting and converting each of said composite received signals into a numerical sample streams, each numerical sample stream corresponding to a portion of a respective composite signal received on a corresponding radio frequency channel;

numerical matrix processing means for producing numerical combinations of said numerical sample streams corresponding to a same radio channel frequency using a set of matrix coefficients associated with each channel frequency;

channel processing means for processing said numerical combinations to produce said plurality of output signals; and

control means for controlling said matrix coefficients such that said output signals each correspond to an intended one of said transmitted signals with reduced interference from the remaining, unintended signals.

8. A transmitting apparatus for transmitting a plurality of signals to a corresponding plurality of receivers by dividing a transmission time on a same radio frequency channel into a plurality of timeslots, comprising:

grouping means for grouping selected ones of said signals into subsets for transmission in a same designated timeslot on said radio channel, whereby signals in a same subset use a same timeslot and signals in different subsets use different timeslots;

channel processing means for processing said signals for transmission in their designated timeslots;

multiplexing means for multiplexing one signal from each subset into its respective timeslot to form Time Division Multiplex signals;

matrix processing means for producing numerical combinations of said Time Division multiplex signals using a different set of matrix coefficients for each timeslot;

a plurality of conversion means for converting said numerical combinations to corresponding modulated analog radio signals on said radio channel and amplifying them to a transmit power level;

multiple-element antenna means, wherein each of said antenna elements is coupled respectively to one of said conversion means, for transmitting said analog radio signals; and

control means for controlling said grouping means and said matrix coefficients such that each of said plurality of receivers receives an intended signal at a desired signal strength with reduced interference from the remaining, unintended signals.

9. The transmitting apparatus of claim 8, wherein said control means is also for minimizing a sum of said transmit power levels.

10. A receiving apparatus for receiving a plurality of signals from a corresponding plurality of transmitters on a same radio channel frequency using a plurality of timeslots in a Time Division multiple Access (TDMA) frame period and producing a plurality of output signals, comprising:

multiple-element antenna means for receiving said plurality of transmitted signals and producing a composite received signal from each element;

multi-channel radio frequency processing means for filtering, amplifying, and converting each of said composite received signals into a corresponding numerical sample stream;

numerical matrix processing means for producing numerical combinations of said numerical samples streams using a different set of matrix coefficients for each of said TDMA timeslots;

demultiplexing means to divide each of said numerical combinations into said plurality of timeslots to produce decimated signal streams;

channel processing means for processing said decimated signal streams to produce said plurality of output signals; and

control means for controlling said matrix coefficients such that said output signals each correspond to an intended one of said transmitted signals with reduced interference from the remaining, unintended signals.

11. An apparatus for minimizing co-channel interference in radiocommunication systems, comprising:

transceiver means for receiving or transmitting signals;

signal processing means for converting each of said signals into a numerical sample stream;

matrix processing means for producing numerical combinations of said numerical sample streams using a set of matrix coefficients, and

control means for selecting or adjusting said matrix coefficients for use by said matrix processing means to minimize co-channel interference between each of said signals.

12. the apparatus of claim 11, wherein said matrix processing means further comprises:

matrix multiplication means for multiplying an inverse of a matrix having said matrix coefficients with a matrix having coefficients related to sampled beams.

13. The apparatus of claim 12, wherein said matrix processing means further comprises:

means for inverting a matrix having said matrix coefficients every sample period.

14. The apparatus of claim 12, wherein said matrix processing means further comprises:

means for inverting a matrix having said matrix coefficients when a new call is connected.

15. The apparatus of claim 11, wherein said control means further comprises:

means for preventing a matrix having said matrix coefficients from becoming numerically ill-conditioned.

16. The apparatus of claim 15, wherein said preventing means further comprises:

means for changing a radio channel of a mobile unit when at least two mobile units approach a common location.

17. A method of allocating a communications channel for transmitting one of a plurality of signals to one of a corresponding plurality of receivers using a plurality of transmitter-antenna element combinations, including:

estimating at least one coefficient relating to phase and amplitude of propagation of said one of a plurality of signals from each of said transmitter-antenna element combinations to said one receiver;

processing said at least one coefficient in conjunction with coefficients associated with groups of other of said plurality of receivers that use the same communications channel within their respective groups, each group employing a different communications channel, in order to determine a figure of merit for each group;

allocating to said one of a plurality of signals the communications channel used by the group producing the highest figure of merit in the processing step.

18. A method of allocating a communications channel according to claim 17 in which said figure of merit for a group is related to the total transmitter power of said transmitter-antenna element combinations if said signal is allocated the same communications channel as said group.

19. The method of claim 17 in which said communications channel is one of a number of timeslots of a time-division-multiplex transmission frame each timeslot being used by one of said groups of receivers.

20. The method of claim 17 in which said communications channel is one of a number of radio frequency channels used by one of said groups of receivers.

21. The method of claim 17 in which said communications channel is one of a number of combinations of radio frequency channel and TDM timeslot each combination being used by one of said groups of receivers.

22. A method of communication between a base station having a sectorized directional antenna and a plurality of mobile stations using TDMA, governed by a TDMA frame rate, comprising the steps of:

rotating sector radiation patterns produced by said antenna synchronously with the TDMA frame rate in a first direction; and

rotating the allocation of Digital Voice Color codes to sectors in in a second direction at the same TDMA frame rate, said second direction being the reverse of said first direction, to produce a constant color code in a given absolute direction.

23. A method according to claim 22 in which said antenna pattern rotation is accomplished by physically spinning the antenna.

24. A method according to claim 22 in which said antenna pattern rotation is accomplished electronically by means of phased array antenna signal processing.

25. An apparatus for minimizing co-channel interference in a radiocommunication system, comprising:

a transceiver for receiving or transmitting signals;

a signal processor for converting each of said signals into a numerical sample stream;

a matrix processor for producing numerical combinations of said numerical sample streams using a set of matrix coefficients; and

a controller for selecting or adjusting said matrix coefficients to minimize co-channel interference between each of said signals.

26. A transmitting apparatus for transmitting a plurality of signals to a corresponding plurality of receivers using a plurality of radio frequency channels and by dividing the transmission time on each radio frequency channel into a plurality of timeslots, comprising:

grouping means for grouping selected ones of said signals into subsets for transmission in a same timeslot and frequency channel whereby signals in a same subset use a same timeslot and frequency and signals in different subsets use different frequencies or timeslots;

channel processing means for processing said signal transmissions in their designated timeslots and on their designated frequencies;

multiplexing means for multiplexing one signal from each subset using the same frequency into its respective timeslot to form a plurality of Time Division Multiplex signals for transmission on each of said frequency channels;

matrix processing means, associated with each radio frequency channel, for producing numerical combinations of said Time Division Multiplex signals using a different set of matrix coefficients for each timeslot and frequency channel;

conversion means, associated with each radio frequency channel, for converting said numerical combinations to corresponding modulated analog radio signals;

a plurality of combining means for combining one of said analog radio signals from each frequency channel and amplifying the combined signal to a transmit power level;

multiple-element antenna means comprising multiple antenna elements, wherein each of said antenna elements is coupled to a respective one of said combining means, to transmit said amplified, combined signals; and

control means for controlling said grouping means and for selecting or adjusting said matrix coefficients for use by said matrix processing means such that each of said receivers receives an intended signal at a desired signal strength with reduced interference from the remaining, unintended signals.

27. The transmitting apparatus of claim 26 wherein said control means is also for minimizing a sum of transmit power levels of said multiple-element antenna means.

28. A receiving apparatus for receiving a plurality of signals from a corresponding plurality of transmitters using a plurality of timeslots in a Time Division Multiple Access frame period and a plurality of radio channel frequencies and producing a plurality of output signals, comprising:

multiple-element antenna means for receiving said plurality of transmitted signals and producing a composite received signal from each element;

multi-channel radio frequency processing means for filtering, amplifying, splitting and converting each of said composite received signals into a number of numerical sample streams corresponding to said plurality of radio channel frequencies;

numerical matrix processing means for producing numerical combinations of said numerical samples streams associated with a same radio channel using sets of matrix coefficients associated with each timeslot and frequency combination;

demultiplexing means for dividing each of said numerical combinations into said plurality of timeslots to produce decimated signal streams;

channel processing means for processing said decimated signal streams to produce said plurality of output signals; and

control means for selecting or adjusting said matrix coefficients for use by said numerical matrix processing means such that said output signals each correspond to an intended one of said transmitted signals with reduced interference from the remaining, unintended signals.