Legacy compatible spatial multiplexing systems and methods

• US 20050281241A1
• Filed: 06/22/2005
• Published: 12/22/2005
• Est. Priority Date: 06/22/2004
• Status: Active Grant

• Current Assignee: Intellectual Ventures I LLC (Intellectual Ventures LLC)
• Original Assignee: Xocyst Transfer AG LLC (Intellectual Ventures LLC)
• Inventors: Webster, Mark A., Seals, Michael J.
• Granted Patent: US 7,643,453 B2
• Time in Patent Office: Days
• US Class Current: 370/343
• CPC Class Codes: H04B 7/066 Combined feedback for a number of channels, e.g. over several subcarriers like in orthogonal frequency division multiplexing [OFDM]
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements

Abstract

Embodiments of legacy compatible spatial multiplexing systems and methods are disclosed. One method embodiment, among others, comprises receiving long training symbols and cyclic shifted long training symbols corresponding to legacy preamble portions of packets corresponding to first and second transmit signals, receiving long training symbols and inverted cyclic shifted long training symbols corresponding to spatial multiplexing portions of packets corresponding to first and second transmit signals, and combining the symbols corresponding to the first and second transmit antennas to estimate the respective channels.

Claims

1. A packet generation method, comprising:

inserting a long training symbol into a first portion of a first packet preamble corresponding to a first packet to be transmitted from a first transmit antenna;

reusing the long training symbol in a second portion of the first packet;

inserting a cyclic shifted long training symbol in a first portion of a second packet preamble corresponding to a second packet to be transmitted from a second transmit antenna; and

reusing the cyclically shifted long training symbol in inverted form in a second portion of the second packet.

2. The method of claim 1, further comprising transmitting the first and second packet.

3. The method of claim 1, wherein reusing the cyclically shifted long training symbol in inverted form comprises inverting the cyclically shifted long training symbol corresponding to the second packet.

4. The method of claim 1, wherein the first portion corresponds to a legacy preamble and the second portion corresponds to a spatial multiplexing portion.

5. A packet reception method, comprising:

receiving long training symbols and cyclic shifted long training symbols corresponding to legacy preamble portions of packets corresponding to first and second transmit signals;

receiving long training symbols and inverted cyclic shifted long training symbols corresponding to spatial multiplexing portions of packets corresponding to first and second transmit signals; and

combining the symbols corresponding to the first and second transmit antennas to estimate the respective channels.

6. The method of claim 5, wherein combining comprises Walsh transforming.

7. The method of claim 5, wherein combining further comprises dividing the symbols by a value corresponding to a long training symbol to obtain a channel estimate.

8. The method of claim 5, wherein combining further comprises dividing the symbols by a value corresponding to a cyclic shifted long training symbol to obtain a cyclic shifted channel estimate.

9. A packet generation system, comprising:

a first logic configured to insert a long training symbol into a first portion of a first packet preamble corresponding to a first packet to be transmitted from a first transmit antenna and reusing the long training symbol in a second portion of the first packet; and

a second logic configured to insert a cyclic shifted long training symbol in a first portion of a second packet preamble corresponding to a second packet to be transmitted from a second transmit antenna and reuse the cyclically shifted long training symbol in inverted form in a second portion of the second packet.

10. The system of claim 9, further comprising transmit logic configured to transmit the first and second packet.

11. The system of claim 9, wherein the second logic is further configured to invert the cyclically shifted long training symbol corresponding to the second packet.

12. The system of claim 9, wherein the first portion corresponds to a legacy preamble and the second portion corresponds to a spatial multiplexing portion.

13. The system of claim 9, wherein the first and second logic is comprised of one of hardware, software, or a combination of hardware and software.

14. A packet reception system, comprising:

a logic configured to receive long training symbols and cyclic shifted long training symbols corresponding to legacy preamble portions of packets corresponding to first and second transmit signals, receive long training symbols and inverted cyclic shifted long training symbols corresponding to spatial multiplexing portions of packets corresponding to first and second transmit signals, and combine the symbols corresponding to the first and second transmit antennas to estimate the respective channels.

15. The system of claim 14, wherein the logic is configured to compute a Walsh transform algorithm.

16. The system of claim 14, wherein the logic is comprised of one of hardware, software, or a combination of hardware and software.

17. The system of claim 14, wherein the logic is configured to divide the symbols by a value corresponding to a long training symbol to obtain a channel estimate.

18. The system of claim 14, wherein the logic is configured to divide the symbols by a value corresponding to a cyclic shifted long training symbol to obtain a cyclic shifted channel estimate.

19. A communication system, comprising:

means for inserting a long training symbol into a first portion of a first packet preamble corresponding to a first packet to be transmitted from a first transmit antenna;

means for reusing the long training symbol in a second portion of the first packet;

means for inserting a cyclic shifted long training symbol in a first portion of a second packet preamble corresponding to a second packet to be transmitted from a second transmit antenna; and

means for reusing the cyclically shifted long training symbol in inverted form in a second portion of the second packet.

20. The system of claim 19, further comprising:

means for receiving the first packet and the second packet; and

means for combining symbols corresponding to the first and second transmit antennas to estimate respective channels.

21. A packet generation method, comprising:

sending a first packet from a antenna, the first packet having a preamble portion and a data portion; and

sending a second packet from a second antenna, the second packet having a cyclic-shifted preamble portion and a cyclic-shifted data portion.

22. A packet generation system, comprising:

logic configured to send a first packet from a antenna, the first packet having a preamble portion and a data portion and send a second packet from a second antenna, the second packet having a cyclic-shifted preamble portion and a cyclic-shifted data portion.

23. A packet reception method, comprising:

receiving a first packet from a first antenna, the first packet having a preamble portion and a data portion; and

receiving a second packet from a second antenna, the second packet having a cyclic-shifted preamble portion and a cyclic-shifted data portion.

24. The method of claim 23, further comprising computing a cyclic shifted channel estimate corresponding to the second antenna.

25. A packet reception system, comprising:

logic configured to receive a first packet from a first antenna, the first packet having a preamble portion and a data portion and receive a second packet from a second antenna, the second packet having a cyclic-shifted preamble portion and a cyclic-shifted data portion.

26. The system of claim 25, wherein the logic is configured to compute a cyclic shifted channel estimate corresponding to the second antenna.