Method and system for digital signal transmission

• US 6,865,237 B1
• Filed: 09/29/2000
• Issued: 03/08/2005
• Est. Priority Date: 02/22/2000
• Status: Expired due to Term

• Current Assignee: CommWorks Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Boariu, Adrian, Tirkkonen, Olav, Hottinen, Ari
• Primary Examiner(s): Tran, Khai
• Application Number:
  US09/676,373
• Time in Patent Office: 1,621 Days
• Field of Search: 375/295, 375/267, 375/259, 375/285, 375/260, 370/203, 370/208, 370/464, 370/390, 708/514, 708/520
• US Class Current: 375/295
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/0618 Space-time coding

Abstract

The invention relates to a method and an arrangement for transmitting a digital signal consisting of symbols, which arrangement comprises a coder (308) for coding complex symbols to channel symbols in blocks having the length of a given K, means (312) for transmitting the channel symbols via several different channels and two or more antennas (314 to 318). The coder (308) is arranged to code the symbols using a code matrix, which can be expressed as a sum of 2K elements, in which each element is a product of a symbol or symbol complex conjugate to be transmitted and a N×N representation matrix of a complexified anti-commutator algebra, extended by a unit element, and in which each matrix is used at most once in the formation of the code matrix. A code matrix is also provided which is formed by matrices of a portion of the symbols placed on the diagonal of the code matrix and by matrices of a second portion of symbols along the anti-diagonal of the code matrix.

Claims

1. A method of transmitting a signal over a plurality of antennas comprising the steps of,

creating a family of structured matrix classes comprising complex elements;

selecting a structured matrix class of said family of structured matrix classes;

selecting a block of channel symbols;

selecting a code matrix comprising a plurality of rows and a plurality of columns from said structured matrix class to be applied to said plurality of antennas;

associating each of said columns of said plurality of columns of said code matrix to an antenna of said plurality of antennas;

associating a row of said plurality of rows of said code matrix to cover a time duration of said selected block of data symbols; and

transmitting using said associated antenna each said column of said code matrix over said corresponding time duration of said selected block of channel symbols.

2. A method of transmitting a signal consisting of K channel symbols, complex conjugates of the symbols, and negative complex conjugates of the symbols over a plurality of antennas comprising the steps of:

selecting a first portion of K/2 channel symbols;

creating a plurality of first matrices comprising the selected first portion of K/2 channel symbols, their complex conjugates, and their negative complex conjugates;

selecting a second portion of K/2 channel symbols;

creating a plurality of second matrices comprising the selected second portion of K/2 channel symbols, their complex conjugates, and their negative complex conjugates;

creating a code matrix having a diagonal and an anti-diagonal said code matrix comprising;

the plurality of said first matrices on the diagonal of said code matrix; and

the plurality of said second matrices on the anti-diagonal of said code matrix;

transmitting the channel symbols, their complex conjugates, and their negative complex conjugates via a plurality of antennas.

3. An arrangement for transmitting a signal consisting of symbols comprising:

a coder for coding complex symbols to channel symbols in blocks having the length of a given K; and

means for transmitting the channel symbols via several different channels and plurality of antennas;

wherein the coder is arranged to code the symbols by;

creating a family of structured matrix classes comprising complex elements;

selecting a structured matrix class of said family of structured matrix classes;

selecting a block of channel symbols;

selecting a code matrix comprising a plurality of rows and a plurality of columns from said structured matrix class to be applied to said plurality of antennas;

associating each of said columns of said plurality of columns of said code matrix to an antenna of said plurality of antennas;

associating a row of said plurality of rows of said code matrix to cover a time duration of said selected block of data symbols; and

selecting the channel symbols from the code matrix.

4. An arrangement for transmitting a signal consisting of symbols, complex conjugates of the symbols, and negative complex conjugates of the symbols over a plurality of antennas comprising:

a coder for coding complex symbols to channel symbols in blocks having the length of a given K; and

means for transmitting the channel symbols via several different channels and a plurality of antennas;

wherein the coder is arranged to code the symbols by;

selecting a first portion of K/2 channel symbols;

creating a plurality of first matrices comprising the selected first portion of K/2 channel symbols, their complex conjugates, and their negative complex conjugates;

selecting a second portion of K/2 channel symbols;

creating a plurality of second matrices comprising the selected second portion of K/2 channel symbols, their complex conjugates, and their negative complex conjugates;

creating a code matrix having a diagonal and an anti-diagonal, said code matrix comprising;

a plurality of said first matrices on the diagonal of said code matrix;

a plurality of said second matrices on the anil-diagonal of said code matrix; and

selecting the channel symbols from the code matrix.

5. In a communication system wherein a digital signal consisting of symbols coded to channel symbols in blocks of given length and transmitted via several different channels and two or more antennas, and wherein the coding is defined by a code matrix comprising an orthogonal block code, in that information is transmitted in redundant directions of the orthogonal block code such that a code rate is higher than what is allowed by orthogonality, the method comprising the steps of:

decoding the information transmitted in the redundant directions; and

decoding the information transmitted in other directions after the information transmitted in the redundant directions has been decoded.

6. The method of claim 5, wherein before the decoding, interference caused by the information transmitted in the redundant directions is suppressed from the information transmitted in other directions.

7. A receiver in a communication system comprising:

means for receiving channel symbols coded blocks of given length, wherein the coding is defined by a code matrix comprising an orthogonal block code, and wherein the channel symbols were transmitted via several different channels and two or more antennas including information in redundant directions of the orthogonal block code; and

means decoding the information transmitted in the redundant directions first and the information transmitted in other directions next.

8. The receiver of claim 7, further comprising means for suppressing the interference caused by the information transmitted in the redundant directions from the information transmitted in other directions, before the decoding is performed.