# US 10,873,361 B2 · Communication system and methods using multiple-in-multiple-out (MIMO) antennas within unitary braid divisional multiplexing (UBDM)

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- Number: US 10,873,361 B2
- Document ID: US10873361B2
- Status: Granted
- Kind: B2
- Application number: 16/416,144
- Filed: 2019-05-17
- Published: 2020-11-19
- Granted: 2020-12-22
- Earliest claimed: 2019-05-17
- Assignees: Rampart Communications, Inc.
- Applicants: Rampart Communications Inc.
- Inventors: Matthew Brandon Robinson
- Web page: https://patentgrep.com/patent/US10873361B2

## CPC

- H04B 1/709: Correlator structure
- H04B 1/66: for reducing bandwidth of signals; for improving efficiency of transmission (H04B1/68 takes precedence)
- H04B 1/7097: Interference-related aspects
- H04B 7/0413: MIMO systems
- H04B 7/0452: Multi-user MIMO systems
- H04J 11/0023: {Interference mitigation or co-ordination (direct sequence spread spectrum [DSSS] systems H04B1/7097; frequency hopping H04B1/713; allocation criteria for ingress interference avoidance H04L5/0062; frequency allocation criteria for requirements on out-of-channel emissions H04L5/0066; arrangements for removing intersymbol interference or baseband equalisers H04L25/03006; peak power aspects in multicarrier modulation H04L27/2614; power management H04W52/00; traffic scheduling H04W72/54, H04W72/541)}
- H04J 13/0077: {Multicode, e.g. multiple codes assigned to one user}
- H04B: TRANSMISSION
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)

## Abstract

A method includes generating, via a processor, multiple initial vectors, each including N elements. A code map is applied to each of the initial vectors, to produce an associated spreading code vector. Each of the spreading code vectors includes M elements, where M≥N. Using the spreading code vectors, spread signals are produced based on a complex baseband signals. The spread signals are stored in a memory operably coupled to the processor. The first and second spread signals are split into respective sets of spread signals, each uniquely associated with one of multiple transmit antennas. The first and second sets of spread signals are transmitted to respective signal receivers for detection of associated complex baseband signals based on the associated spreading code vectors.

## Claims

### Claim 1

A method of performing unitary braid divisional multiplexing (UBDM) with a plurality of multiple-in-multiple-out (MIMO) antennas, the method comprising:
generating, via at least one processor, a plurality of initial vectors, each initial vector from the plurality of initial vectors including N elements, N being a positive integer;
applying, via the at least one processor, a code map to each initial vector from the plurality of initial vectors to produce an associated spreading code vector of a plurality of spreading code vectors, each spreading code vector from the plurality of spreading code vectors including M elements, M having a value of at least N, the code map defined such that an inner product of: (1) a first spreading code vector from the plurality of spreading code vectors, based on a first initial vector from the plurality of initial vectors; and (2) a second spreading code vector from the plurality of spreading code vectors, based on a second initial vector from the plurality of initial vectors, is equal to a product of (i) an inner product of the first initial vector and the second initial vector, and (ii) a positive constant;
producing, using the first spreading code vector, a first spread signal based on a first complex baseband signal;
producing, using the second spreading code vector, a second spread signal based on a second complex baseband signal;
storing at least one of the first spread signal or the second spread signal in a memory operably coupled to the processor;
splitting the first spread signal into a first plurality of spread signals, each spread signal from the first plurality of spread signals being uniquely associated with a MIMO antenna from the plurality of MIMO antennas;
splitting the second spread signal into a second plurality of spread signals, each spread signal from the second plurality of spread signals being uniquely associated with a MIMO antenna from the plurality of MIMO antennas;
transmitting the first plurality of spread signals, via a communications channel and the plurality of MIMO antennas, to a first signal receiver that is configured to detect the first complex baseband signal based on the first spreading code vector; and
transmitting the second plurality of spread signals, via the communications channel and the plurality of MIMO antennas, to a second signal receiver that is configured to detect the second complex baseband signal based on the second spreading code vector.

### Claim 2 (depends on 1)

The method of claim 1, wherein:
the transmitting the first plurality of spread signals includes transmitting the first plurality of spread signals to the first signal receiver that is configured to combine the first plurality of spread signals to produce the first spread signal and to detect the first complex baseband signal based on the first spreading code vector and the first spread signal; and
the transmitting the second plurality of spread signals includes transmitting the second plurality of spread signals to the second signal receiver that is configured to combine the second plurality of spread signals to produce the second spread signal and to detect the second complex baseband signal based on the second spreading code vector and the second spread signal.

### Claim 3 (depends on 1)

The method of claim 1, wherein:
a bandwidth of the first spread signal is greater than a bandwidth of each spread signal from the first plurality of spread signals; and
a bandwidth of the second spread signal is greater than a bandwidth of each spread signal from the second plurality of spread signals.

### Claim 4 (depends on 1)

The method of claim 1, wherein:
the transmitting the first plurality of spread signals includes transmitting the first plurality of spread signals to the first signal receiver having a plurality of MIMO antennas that is configured to receive the first plurality of spread signals; and
the transmitting the second plurality of spread signals includes transmitting the second plurality of spread signals to the second signal receiver having a plurality of MIMO antennas that is configured to receive the second plurality of spread signals.

### Claim 5 (depends on 1)

The method of claim 1, wherein:
the transmitting the first plurality of spread signals includes transmitting the first plurality of spread signals to the first signal receiver configured to receive the first plurality of spread signals by each MIMO antenna from a plurality of MIMO antennas of the first signal receiver; and
the transmitting the second plurality of spread signals includes transmitting the second plurality of spread signals to the second signal receiver configured to receive the second plurality of spread signals by each MIMO from a plurality of MIMO antennas of the second signal receiver.

### Claim 6 (depends on 1)

The method of claim 1, further comprising:
encoding, after splitting the first spread signal and before transmitting the first plurality of spread signals, the first plurality of spread signals with space-time block codes to produce a first plurality of encoded spread signals,
the transmitting the first plurality of spread signals including transmitting the first plurality of encoded spread signals; and
encoding, after splitting the second spread signal and before transmitting the second plurality of spread signals, the second plurality of spread signals with the space-time-block codes to produce a second plurality of encoded spread signals,
the transmitting the second plurality of spread signals including transmitting the second plurality of encoded spread signals.

### Claim 7 (depends on 6)

The method of claim 6, wherein the space-time block codes are Alamouti codes.

### Claim 8

A method of performing unitary braid divisional multiplexing (UBDM) with a plurality of multiple-in-multiple-out (MIMO) antennas, the method comprising:
generating, via at least one processor, a plurality of initial vectors, each initial vector from the plurality of initial vectors including N elements, N being a positive integer;
applying, via the at least one processor, a code map to each initial vector from the plurality of initial vectors to produce an associated spreading code vector of a plurality of spreading code vectors, each spreading code vector from the plurality of spreading code vectors including M elements, M being a positive integer having a value of at least N, the code map defined such that an inner product of: (1) a first spreading code vector from the plurality of spreading code vectors, based on a first initial vector from the plurality of initial vectors; and (2) a second spreading code vector from the plurality of spreading code vectors, based on a second initial vector from the plurality of initial vectors, is equal to a product of (i) an inner product of the first initial vector and the second initial vector, and (ii) a positive constant;
producing, using the first spreading code vector, a spread signal based on a complex baseband signal;
storing the spread signal in a memory operably coupled to the processor;
splitting the spread signal into a plurality of spread signals, each spread signal from the plurality of spread signals being uniquely associated with a MIMO antenna from the plurality of MIMO antennas; and
transmitting the plurality of spread signals, via a communications channel and the plurality of MIMO antennas, to a signal receiver that is configured to detect the first complex baseband signal based on the first spreading code vector.

### Claim 9 (depends on 8)

The method of claim 8, wherein the signal receiver includes a plurality of MIMO antennas that is configured to receive the plurality of spread signals.

### Claim 10 (depends on 8)

The method of claim 8, wherein the transmitting the plurality of spread signals includes transmitting the plurality of spread signals to the signal receiver configured to receive the plurality of spread signals by each MIMO antenna from a plurality of MIMO antennas of the signal receiver.

### Claim 11 (depends on 8)

The method of claim 8, further comprising encoding, after splitting the spread signal and before transmitting the plurality of spread signals, the plurality of spread signals with space-time block codes to produce a first plurality of encoded spread signals.

### Claim 12 (depends on 11)

The method of claim 11, wherein the space-time block codes are Alamouti codes.

### Claim 13 (depends on 8)

The method of claim 8, wherein the transmitting the plurality of spread signals includes transmitting encoded spread signals.

### Claim 14

An apparatus comprising:
a plurality of antennas;
at least one processor configured to:
generate a plurality of initial vectors, each initial vector from the plurality of initial vectors including N elements, N being a positive integer;
apply a code map to each initial vector from the plurality of initial vectors to produce an associated spreading code vector including at least M elements, M being a positive integer having a value of at least N, the code map defined such that an inner product of: (1) a first spreading code vector from the plurality of spreading code vectors, based on a first initial vector from the plurality of initial vectors; and (2) a second spreading code vector from the plurality of spreading code vectors, based on a second initial vector from the plurality of initial vectors, is equal to a product of (i) an inner product of the first initial vector and the second initial vector, and (ii) a positive constant;
produce a first spread signal based on a first complex baseband signal; and
produce a second spread signal based on a second complex baseband signal; and
a splitter coupled to the code generator and the plurality of antennas, the splitter configured to:
split the first spread signal into a first plurality of spread signals, each spread signal from the first plurality of spread signals being uniquely associated with an antenna from the plurality of antennas;
split the second spread signal into a second plurality of spread signals, each spread signal from the second plurality of spread signals being uniquely associated with an antenna from the plurality of antennas;
the plurality of antennas configured to transmit the first spread signal to a first signal receiver, and to transmit the second spread signal to a second signal receiver different from the first signal receiver, such that each of the first signal receiver and the second signal receiver, upon receiving the first spread signal and the second spread signal detects the first complex baseband signal and the second complex baseband signal, respectively.

### Claim 15 (depends on 14)

The apparatus of claim 14, wherein:
the plurality of antennas is configured to transmit the first plurality of spread signals to the first signal receiver that is configured to combine the first plurality of spread signals to produce the first spread signal and to detect the first complex baseband signal based on the first spreading code vector and the first spread signal; and
the plurality of antennas is configured to transmit the second plurality of spread signals to the second signal receiver that is configured to combine the second plurality of spread signals to produce the second spread signal and to detect the second complex baseband signal based on the second spreading code vector and the second spread signal.

### Claim 16 (depends on 14)

The apparatus of claim 14, wherein:
a bandwidth of the first spread signal is greater than a bandwidth of each spread signal from the first plurality of spread signals; and
a bandwidth of the second spread signal is greater than a bandwidth of each spread signal from the second plurality of spread signals.

### Claim 17 (depends on 14)

The apparatus of claim 14, wherein:
the plurality of antennas is configured to transmit the first plurality of spread signals to the first signal receiver having a plurality of antennas that is configured to receive the first plurality of spread signals; and
the plurality of antennas is configured to transmit the second plurality of spread signals to the second signal receiver having a plurality of antennas that is configured to receive the second plurality of spread signals.

### Claim 18 (depends on 14)

The apparatus of claim 14, wherein:
the plurality of antennas is configured to transmit the first plurality of spread signals to the first signal receiver that receives the first plurality of spread signals by each antenna from a plurality of antennas of the first signal receiver; and
the plurality of antennas is configured to transmit the second plurality of spread signals to the second signal receiver that receives the second plurality of spread signals by each antenna from a plurality of antennas of the second signal receiver.

### Claim 19 (depends on 14)

The apparatus of claim 14, further comprising:
an encoder coupled to the code generator and the splitter, the encoder configured to encode the first plurality of spread signals with space-time block codes to produce a first plurality of encoded spread signals, the plurality of antennas configured to transmit the first plurality of encoded spread signals,
the encoder configured to encode the second plurality of spread signals with the space-time-block codes to produce a second plurality of encoded spread signals, the plurality of antennas configured to transmit the second plurality of encoded spread signals.

### Claim 20 (depends on 19)

The apparatus of claim 19, wherein the space-time block codes are Alamouti codes.