Method and apparatus for providing antenna diversity

• US 5,479,448 A
• Filed: 03/31/1992
• Issued: 12/26/1995
• Est. Priority Date: 03/31/1992
• Status: Expired due to Term

• Current Assignee: AT&T IPM Corp. (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Seshadri, Nambirajan
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): GHEBRETINSAE, TEMESGHEN
• Application Number:
  US07/860,830
• Time in Patent Office: 1,365 Days
• Field of Search: 375/38, 375/40, 375/67, 375/100, 371/68.1, 371/68.2, 343/729, 343/893, 455/60, 455/61, 455/66, 455/33.3, 455/59, 455/63, 370/29, 370/18, 370/50
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0604 with predefined switching scheme
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618

Abstract

A method and apparatus providing antenna diversity is disclosed. A set of bits of a digital signal are used to generate a codeword of N symbols. Codewords are provided according to a channel code having a minimum Hamming distance, d_min, where 2≦d_m ≦N. N signals representing N symbols of a codeword are transmitted with N different antennas. The N transmitted signals are received and isolated. A sequence of N received symbols is formed from the isolated symbols and compared with one or more valid codewords to associate the sequence with a codeword. A set of bits based on a codeword associated with the received sequence is generated.

Claims

1. A method of transmitting a digital signal with use of a plurality of N antennas, where N is an integer, the method comprising the steps of:

according to a channel code, generating a codeword of N symbols to reflect a set of bits of the digital signal, the channel code having a plurality of codewords and a minimum Hamming distance, d_min, where 2≦

d_min ≦

N, wherein each of one or more of said plurality of codewords comprises at least two different symbols; and

transmitting N signals with N different antennas, each signal representing one of the N symbols of a generated codeword.

2. The method of claim 1 wherein the step of transmitting N signals comprises the step of transmitting the N signals with a phase relationship between each distinct pair of symbols so as to provide a diversity benefit.

3. The method of claim 2 wherein the diversity benefit provided is d_min.

4. The method of claim 1 wherein the step of transmitting N signals comprises the step of forming in-phase and quadrature amplitude values based on a symbol.

5. The method of claim 4 wherein a transmitted signal is based on in-phase and quadrature amplitude values.

6. An apparatus for transmitting a digital signal with use of a plurality of N antennas, where N is an integer, the apparatus comprising:

a channel encoder for generating a codeword of N symbols according to a channel code, the codeword reflecting a set of bits of the digital signal, the channel code having a plurality of codewords and a minimum Hamming distance, d_min, where 2≦

d_min ≦

N, and wherein each of one or more of said plurality of codewords comprises at least two different symbols; and

means for transmitting N signals with N different antennas, each signal representing one of the N symbols of a generated codeword.

7. The apparatus of claim 6 wherein the means for transmitting N signals comprises means for transmitting the N signals with a phase relationship between each distinct pair of signals so as to provide a diversity benefit.

8. The apparatus of claim 7 wherein the diversity benefit provided is d_min.

9. The apparatus of claim 6 wherein the means for transmitting N signals comprises means for forming in-phase and quadrature amplitude values based on a symbol.

10. The apparatus of claim 9 wherein the means for transmitting further comprises a modulator for generating a modulated signal based on the in-phase and quadrature amplitude values.

11. The apparatus of claim 9 wherein a transmitted signal is based on in-phase and quadrature amplitude values.

12. A method of generating a set of bits of a digital signal, the method comprising the steps of:

receiving a plurality of N signals transmitted from N different antennas, where N is an integer, each signal representing one of N symbols of a codeword, the codeword based on a channel code having a plurality of codewords and a minimum Hamming distance, d_min, where 2≦

d_min ≦

N, and wherein each of one or more of said plurality of codewords comprises at least two different symbols;

based on the N received signals, forming N symbols of a received codeword sequence;

comparing the received codeword sequence with one or more valid codewords to associate the received sequence with a valid codeword; and

generating a set of bits based on the codeword associated with the received sequence.

13. A receiver for use in a communication system, the communication system including a transmitter comprising a plurality of N antennas, where N is an integer, the communication system communicating codewords of N symbols according to a channel code, the receiver comprising:

means for receiving signals transmitted by the N antennas, each signal representing one of N symbols of a codeword, the codeword based on a channel code having a plurality of codewords and a minimum Hamming distance, d_min, where 2≦

d_min ≦

N, and wherein each of one or more of said plurality of codewords comprises at least two different symbols;

means, coupled to the means for receiving, for isolating a signal transmitted by each antenna;

means, coupled to the means for isolating, for forming a sequence of N received signals based on the N isolated signals;

means, coupled to the means for forming, for comparing the sequence of N received with one or more valid codewords to associate the sequence with a valid codeword; and

means, coupled to the means for comparing, for generating a set of bits based on the codeword associated with the received sequence.