System and method for transmit diversity base upon transmission channel delay spread

• US 7,336,719 B2
• Filed: 11/28/2001
• Issued: 02/26/2008
• Est. Priority Date: 11/28/2001
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Talwar, Shilpa, Gore, Dhananjay, Sandhu, Sumeet, Paulraj, Arogyaswami J.
• Primary Examiner(s): Kumar; Pankaj
• Application Number:
  US09/999,438
• Publication Number:
  US 20030099304A1
• Time in Patent Office: 2,281 Days
• Field of Search: 375/130, 375/140, 375/146, 375/147, 375/148, 375/259, 375/260, 375/267, 455/562.1, 455/561, 455/550.1, 455/73, 370/208, 370/203
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04L 1/0656 Cyclotomic systems, e.g. Bell Labs Layered Space-Time [BLAST]

Abstract

The present invention provides a diversity transmission system. The diversity transmission system includes a method and system of diversity transmission through a wireless channel formed between multiple transmission antennae of a transceiver and a subscriber unit. The method includes forming a stream of symbols from an incoming data stream. A plurality of the symbols are selected forming a data vector. A maximum delay spread through the wireless channel is determined. The maximum delay spread is generally determined as a multiple of a sample time spacing between elements of the data vector. A plurality of diversity vectors are generated based upon the data vector and the maximum delay spread, each diversity vector includes a plurality of elements. Corresponding elements of the diversity vectors are simultaneously transmitted, each diversity vector transmitted from at least one corresponding antenna of a plurality of spatially separate antennae. This embodiment can further include repeatedly simultaneously transmitting corresponding elements of the diversity vectors until all elements of the diversity vectors have been transmitted, each diversity vector transmitted from at least one corresponding antenna of a plurality of spatially separate antennae.

Claims

1. A method of diversity transmission through a wireless channel formed between multiple transmission antennae of a transceiver and a subscriber unit comprising:

forming a stream of symbols from an incoming data stream;

selecting a plurality of the symbols to form a data vector;

determining a maximum delay spread through the wireless channel;

generating a plurality of diversity vectors based upon the data vector and the determined maximum delay spread, each diversity vector comprising a plurality of elements, and wherein a diversity vector is generated by shifting elements within the data vector by an amount that corresponds with a multiple of the determined delay spread; and

simultaneously transmitting corresponding elements of the diversity vectors, each diversity vector transmitted from at least one corresponding antenna of a plurality of spatially separate antennae.

2. The method of diversity transmission of claim 1, wherein the maximum delay spread is determined as a multiple of a sample time spacing between elements of the data vector.

3. The method of diversity transmission of claim 1, wherein the multiple of the maximum delay spread may be a fraction.

4. The method of diversity transmission of claim 1, wherein generating a plurality of diversity vectors based upon the data vector and the maximum delay spread comprises:

generating each diversity vector by shifting elements within the data vector by an amount that corresponds with a multiple of a delay greater than the maximum delay spread.

5. The method of diversity transmission of claim 1, wherein generating a plurality of diversity vectors based upon the data vector and the maximum delay spread comprises:

generating an Mth diversity vector by shifting elements within the data vector by (M−

1)*L, where L is the maximum delay spread normalized by a sample time spacing between elements of the data vector.

6. The method of diversity transmission of claim 4, wherein the Mth diversity vector is transmitted from an Mth transmission antenna.

7. The method of diversity transmission of claim 4, wherein the diversity vectors are formed from the data vector by circularly shifting the elements of the data vector.

8. The method of diversity transmission of claim 7, wherein a cyclic prefix is appended to each of the diversity vectors.

9. The method of diversity transmission of claim 1, further comprising:

repeatedly simultaneously transmitting corresponding elements of the diversity vectors until all elements of the diversity vectors have been transmitted, each diversity vector transmitted from at least one corresponding antenna of a plurality of spatially separate antenna.

10. The method of diversity transmission of claim 1, wherein simultaneously transmitting corresponding elements of the diversity vectors comprises simultaneously transmitting all the elements of the diversity vectors, each element transmitted within a corresponding frequency slot.

11. The method of diversity transmission of claim 10, wherein each frequency slot comprises at least one multiple carrier signal.

12. The method of diversity transmission of claim 11, wherein the multiple carrier signals are orthogonal frequency division mutiplexed (OFDM) signals.

13. The method of diversity transmission of claim 1, further comprising setting a number M_t of transmission antennae.

14. The method of diversity transmission of claim 1, wherein the plurality of selected inputs symbols includes at least M_t*L symbols, where L is the maximum delay spread normalized by a sample time spacing between elements of the data vector, and the transmitter comprises M_t spatially separate transmit antennae.

15. The method of diversity transmission of claim 14, wherein the plurality of selected input symbols is a power of two.

16. The method of diversity transmission of claim 1, wherein the spatially separate antennae are co-located at a single base transceiver station.

17. The method of diversity transmission of claim 1, wherein the spatially separate antennae are located at a plurality of base transceiver stations.

18. The method of diversity transmission of claim 7, wherein generating a plurality of diversity vectors by circularly rotating the transmit vector comprises;

shifting transmit vector elements within transmit vector to form each diversity vector.

19. The method of diversity transmission of claim 7, wherein generating a plurality of diversity vectors by circularly rotating the transmit vector comprises;

reversing the order of the elements within the transmit vector; and

shifting the transmit vector elements within the reversed transmit vector to form each diversity vector.

20. The method of diversity transmission of claim 1, wherein a number of diversity vectors formed is equal to a number M_t of transmit vector elements.

21. The method of diversity transmission of claim 1, wherein a number of diversity vectors formed is less than a number M_t of transmit vector elements.

22. The method of diversity transmission of claim 1, wherein the maximum delay spread is determined by characterizing the wireless channel.

23. The method of diversity transmission of claim 1, wherein the maximum delay spread is determined by the subscriber unit receiving and characterizing transmitted signals and feeding the maximum delay spread back to the transceiver.

24. The method of diversity transmission of claim 1, wherein the maximum delay spread is determined by the transceiver receiving and characterizing signals received from the subscriber unit.

25. A diversity transmitter for providing transmission through a wireless channel formed between multiple transmission antennae of a transceiver and a subscriber unit, the diversity transmitter comprising:

an encoder that receives and encodes a bit stream;

a mapper that maps the encoded bit stream into symbols;

a block former for selecting blocks of the symbols;

means for determining a maximum delay spread through the wireless channel;

means for generating a plurality of diversity vectors based upon the data vector and the maximum delay spread, each diversity vector comprising a plurality of elements, and wherein a diversity vector is generated by shifting elements within the data vector by an amount that corresponds with a multiple of the determined delay spread wherein the multiple; and

a plurality of transmit antenna for transmitting the diversity vectors.

26. The diversity transmitter of claim 25, wherein corresponding elements of the transmit vectors are simultaneously transmitted.

27. The diversity transmitter of claim 25, wherein all elements of the transmit vectors are simultaneously transmitted within a corresponding frequency slot.

28. A diversity transmitter comprising:

an encoder to receive and selectively encode a bit stream;

a mapper, responsive to the encoder, to map the encoded bit stream into symbols;

a block former, responsive to the mapper, to select blocks of the symbols;

a delay spread generator, to determine a maximum delay spread through the wireless channel; and

a vector generator, responsive to the delay spread generator and the block former, to generate a plurality of diversity vectors based, at least in part, upon a data vector comprising one or more of the symbol blocks and an indication of the maximum delay spread by shifting elements within the data vector by an amount that corresponds with some multiple of the maximum delay spread for selective transmission through one or more of a plurality of spatially separate antenna(e).