Transmitter diversity technique for wireless communications

• US 9,203,499 B2
• Filed: 06/30/2014
• Issued: 12/01/2015
• Est. Priority Date: 09/16/1997
• Status: Expired due to Fees

• Current Assignee: AT&T Wireless Services Incorporated (AT&T, Inc.)
• Original Assignee: AT&T Mobility II LLC (AT&T, Inc.)
• Inventors: Tarokh, Vahid, Alamouti, Siavash
• Primary Examiner(s): Corrielus, Jean B
• Application Number:
  US14/319,428
• Publication Number:
  US 20140314174A1
• Time in Patent Office: 519 Days
• Field of Search: 375/267, 375/316, 375/340, 375/347, 375/349
• US Class Current: 1/1
• CPC Class Codes: H04B 1/02 Transmitters
• CPC Class Codes: H04B 7/0613 using simultaneous transmission H04B7/0686 takes precedence
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0667 of delayed versions of same signal using space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04B 7/0845 per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch rake receivers as such H04B1/7115
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• CPC Class Codes: H04B 7/12 Frequency diversity
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/04 using frequency diversity
• CPC Class Codes: H04L 1/0606 Space-frequency coding
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 1/0625 Transmitter arrangements
• CPC Class Codes: H04L 1/0631 Receiver arrangements
• CPC Class Codes: H04L 1/0643 block codes
• CPC Class Codes: H04L 1/0668 : Orthogonal systems, e.g. using Alamouti codes
• CPC Class Codes: H04L 1/08 : by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 25/0202 : Channel estimation

Abstract

A simple block coding arrangement is created with symbols transmitted over a plurality of transmit channels, in connection with coding that comprises only simple arithmetic operations, such as negation and conjugation. The diversity created by the transmitter utilizes space diversity and either time or frequency diversity. Space diversity is effected by redundantly transmitting over a plurality of antennas, time diversity is effected by redundantly transmitting at different times, and frequency diversity is effected by redundantly transmitting at different frequencies: Illustratively, using two transmit antennas and a single receive antenna, one of the disclosed embodiments provides the same diversity gain as the maximal-ratio receiver combining (MRRC) scheme with one transmit antenna and two receive antennas. The principles of this invention are applicable to arrangements with more than two antennas, and an illustrative embodiment is disclosed using the same space block code with two transmit and two receive antennas.

Claims

1. A method of receiving a wireless communication from first and second space diverse antennas, the method comprising:

estimating channel characteristics of communication channels between said first and second space diverse antennas and a receiver and supplying said estimated channel characteristics to a combiner and a detector;

receiving at the receiver signals corresponding to a block of symbols that has been transmitted from said first and second space diverse antennas, the transmitted block of symbols including a first symbol, a second symbol, a complex conjugate of said first symbol, and a negative complex conjugate of the second symbol, wherein the first symbol and the complex conjugate of the first symbol are in respective signals received at different times and the second symbol and the negative complex conjugate of the second symbol are received in the respective signals at different times;

supplying the received signals to the combiner and outputting estimates of transmitted symbols to the detector; and

detecting in said detector the transmitted first and second symbols using said estimates and said estimated channel characteristics.

2. A receiver comprising:

a channel estimator to provide channel estimates between an antenna of the receiver and first and second space diverse transmitting antennas;

a combiner responsive to signals received by said antenna and to said channel estimates developed for at least two transmission paths over which said signals arrive at said antenna from said first and second space diverse transmitting antennas, said combiner for developing symbol estimates by combining said signals received by said antenna with said channel estimates via operations that include multiplications and conjugations; and

a detector coupled to receive said symbol estimates and to detect first and second transmitted symbols;

wherein said signals received by said antenna represent a block of symbols including said first and second transmitted symbols and a complex conjugate of the first transmitted symbol and a negative complex conjugate of the second transmitted symbol;

wherein the first symbol and the complex conjugate of the first symbol are received in respective signals received at different times and the second symbol and the negative complex conjugate of the second symbol are received in the respective signals received at different times.