Methods for spatial multiplexing of wireless two-way channels

• US 7,817,641 B1
• Filed: 10/17/2006
• Issued: 10/19/2010
• Est. Priority Date: 10/20/2005
• Status: Active Grant

• Current Assignee: Amir Keyvan Khandani
• Original Assignee: Amir Keyvan Khandani
• Inventors: Khandani, Amir Keyvan
• Primary Examiner(s): Trost, IV; William
• Assistant Examiner(s): JAIN, RAJ K
• Application Number:
  US11/581,427
• Time in Patent Office: 1,463 Days
• Field of Search: None
• US Class Current: 370/395.4
• CPC Class Codes: H04B 7/0682 using phase diversity (e.g. phase sweeping)
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04B 7/084 Equal gain combining, only phase adjustments antenna beam scanning or forming by phase or amplitude control H01Q3/26, e.g. phased arrays
• CPC Class Codes: H04B 7/0871 using different reception schemes, at least one of them being a diversity reception scheme
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports

Abstract

Conventional two-way wireless communication nodes require separate channels to receive or transmit. The two channels are usually multiplexed in time and/or frequency. A system which can support both links (transmit and receive) at the same time is referenced as a as a full duplex system. Systems and methods are described to create the two links simultaneously, overlapping in frequency and in time domains, while avoiding the hardware complexity and/or lack of flexibility inherent to conventional systems, by reducing the amount of self interference between transmitter and receiver sections. The self interference may be reduced by using at least one of antenna design techniques comprising antenna selection and signal processing techniques to maximize the signal-to-interference plus noise ratio.

Claims

1. A transceiver unit, comprising:

a transmitter,

a receiver; and

a plurality of antennas, at least one of the plurality of antennas defining at least one transmit antenna and at least one of the plurality of antennas defining at least one separate receive antenna to enable simultaneous transmitting and receiving, overlapping in time and frequency, for a two-way communication with another communication device, the plurality of antennas configured and/or controlled using at least one of antenna design techniques comprising antenna selection and signal processing techniques to reduce self-interference between the at least one transmit antenna and the at least one separate receive antenna to maximize the signal-to-interference noise ratio, such that an amount of the signal-to-interference noise ratio at the at least one separate receive antenna is measured and maximized through at least one technique selected from;

antenna design technique, comprising at least one of;

shape/dimension, layout, orientation, placement of feed network, antenna selection, and antenna beam-forming;

adaptive signal processing technique comprising interference cancellation, to process a block of data to exploit the non-causality to improve the performance of the interference canceller; and

adaptive signal processing technique comprising combined demodulation, channel decoding and interference cancellation using an iterative decoding/demapping procedure to process a block of data to exploit non-causality to improve the performance of the interference cancellation; and

wherein each transmit or receive antenna is split into multiple antennas each with a phase shift selected for reducing the amount of the self-interference;

wherein the transmit and receive antennas comprise patch antennas placed on a same surface of one or more multi-layer printed circuit boards (PCBs) of the unit and wherein the unit further comprises respective feed networks for the transmit and receive antennas placed partially on the same surface as the patch antennas, partially on intermediate layers and partially on the other surface of the PCB for reducing the amount of self-interference;

wherein said PCB layers are isolated through grounded planes of conducting material to reduce self-interference where such planes have holes to pass the respective feed networks across the layers of the PCB;

wherein the layers of the PCB are made of one or more selected dielectric materials having one or more thicknesses for reducing the amount of self-interference; and

wherein band gap material is used in the PCBs for reducing the amount of self-interference;

and further wherein the transceiver unit comprises;

a. a PCB comprising multiple layers of said dielectric material and band gap material sandwiching grounded planes of conductor material, said PCB defining connections between the layers for the conductor, said PCB comprising opposite top and bottom surfaces;

b. two patch antennas defining transmit antennas having a 180 degree phase shift difference located on one of the opposite surfaces of the PCB;

c. one patch antenna defining a receive antenna located on the same one opposite surface of the PCB in the middle of the two transmit antennas at the physical location of a transmit null;

d. a transmit feed network located on the other of the opposite surfaces of the PCB or on a different layer of the PCB from said patch antennas;

e. circuitry for the receive antenna, comprising low noise amplifiers (LNAs), located on the same one surface at the physical location of a local transmit null; and

f. circuitry for the transmit antennas, comprising power amplifiers, located on the other of the opposite surfaces of the PCB.

2. The transceiver unit of claim 1 wherein two such PCBs are connected back to back to provide coverage on both sides.

3. The transceiver unit of claim 1 wherein the roles of the transmit and receive antennas are exchanged.

4. The transceiver unit of claim 1 comprising a plurality of full duplex transceiver antennas each defined in accordance with elements a) to f) and wherein the respective PCBs are located at an angle and orientation with respect to each other for reducing the amount of self-interference and wherein the angles are adjustable to optimize performance.

5. The transceiver unit of claim 1 surrounded by moveable or fixed walls comprising material selected to either absorb or reflect electromagnetic energy to reduce self-inference and/or shape the radiation transmit and/or receive pattern(s) to maximize the signal-to-interference noise ratio.

6. The transceiver unit of claim 1 wherein the transceiver unit is configured for communicating with at least one other similar unit such that a complex gain of the transmit or receive antenna(s) of the transceiver unit is selected to provide a full duplex transceiver and wherein the transceiver unit is further configured in accordance with techniques for the use of multiple antenna systems comprising one of spatial multiplexing or space-time coding.

7. The transceiver unit of claim 6 configured to perform a relaying operation such that simultaneous links between the transceiver unit and two others provide a TR₁TR₂TR3 connection and wherein LHRH specifies information flow from the LH to the RH.

8. The transceiver unit of claim 7 configured to perform a multi-hop relaying operation among a plurality of others, wherein (1) an OFDM signalling scheme is used and where the total delay introduced by the multi-hop relaying and wave propagation is within the tolerable delay specified by an employed cyclic prefix to guarantee addition of the relayed signals at the intermediate relay nodes and at the final destination, and (2) a CDMA signalling with RAKE receiver at the relay nodes and at the final destination is used and where the delay introduced by the multi-hop relaying and wave propagation is such that the RAKE receivers can function in a desired manner.