Method and system for compromise greenfield preambles for 802.11n

• US 20060182017A1
• Filed: 06/09/2005
• Published: 08/17/2006
• Est. Priority Date: 02/16/2005
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Braodcom Corporation
• Inventors: Hansen, Christopher J., Trachewsky, Jason A., Moorti, Rajendra T.
• Granted Patent: US 8,737,189 B2
• Time in Patent Office: Days
• US Class Current: 370/208
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/028 Spatial transmit diversity using a single antenna at the transmitter
• CPC Class Codes: H04B 7/0404 the mobile station comprising multiple antennas, e.g. to provide uplink diversity
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0486 taking channel rank into account
• CPC Class Codes: H04B 7/0495 using overlapping sectors in the same base station to implement MIMO for antennas
• 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: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 25/03929 with layer mapping, e.g. codeword-to layer design for space-time coding H04L1/0618
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 5/0026 Division using four or more dimensions
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 67/147 Signalling methods or messages providing extensions to protocols defined by standardisation
• CPC Class Codes: H04L 69/161 Implementation details of TCP/IP or UDP/IP stack architecture; Specification of modified or new header fields
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers
• CPC Class Codes: H04W 52/0225 : using monitoring of external events, e.g. the presence of a signal
• CPC Class Codes: H04W 52/52 : using AGC [Automatic Gain Control] circuits or amplifiers
• CPC Class Codes: H04W 84/12 : WLAN [Wireless Local Area Networks]
• CPC Class Codes: Y02D 30/70 : in wireless communication networks

Abstract

Aspects of the invention described herein may enable a greenfield access mode in IEEE 802.11n WLAN systems in comparison to an alternative approach that may not provide greenfield access. The utilization of greenfield access may reduce the portion of time required to transmit data due to overhead comprising preamble fields and header fields. This may enable higher data throughput rates to be achieved. This may further enable more robust transmission of data by enabling comparable data rates to be maintained while reducing the coding rate of encoded transmitted data. The reduction of the coding rate may enable comparable data rates to be maintained for transmission via RF channels characterized by lower SNR while still achieving desired target levels of packet error rates. In another aspect of the invention, mixed mode access may be achieved while reducing the portion of time required for transmitting data due to overhead.

Claims

1. A method for communicating information in a multiple input multiple output (MIMO) communications systems, the method comprising:

generating a protocol data unit (PDU) for a current spatial stream comprising a current plurality of long training sequence fields;

appending a signal field subsequent to a last of said current plurality of long training sequence fields;

generating a PDU for a subsequent spatial stream comprising a subsequent plurality of long training sequence fields wherein one of said subsequent plurality of long training sequence fields is orthonormal to a corresponding one of said current plurality of long training sequence fields; and

appending a subsequent signal field subsequent to a last of said subsequent plurality of long training sequence fields.

2. The method according to claim 1, further comprising transmitting 2 orthogonal frequency division multiplexing (OFDM) symbols during a first long training sequence field of said current plurality of long training sequence fields.

3. The method according to claim 2, further comprising generating said 2 OFDM symbols based on long training sequences that are approximately identical.

4. The method according to claim 2, further comprising transmitting 1 OFDM symbol during a long training sequence field that is subsequent to said first long training sequence field.

5. The method according to claim 1, further comprising transmitting 2 OFDM symbols during said signal field.

6. The method according to claim 1, further comprising, for a first spatial stream, transmitting a first long training sequence field, and a second long training field via said current spatial stream, in a system utilizing 2 transmitted spatial streams, wherein said first long training sequence field, and said second long training sequence field utilizes a long training sequence based on IEEE 802.11a.

7. The method according to claim 1, further comprising, for a second spatial stream, transmitting a first long training sequence field, and a second long training field via said current spatial stream, in a system utilizing 2 transmitted spatial streams, wherein said first long training sequence field, and said second long training sequence field utilizes a phase shifted long training sequence based on IEEE 802.11a.

8. The method according to claim 1, further comprising, for a first spatial stream, transmitting a first long training sequence field, a second long training sequence field, and a third long training field via said current spatial stream, in a system utilizing 3 transmitted spatial streams, wherein said first long training sequence field, said second long training sequence field, and said third long training sequence field utilizes a multiplicatively scaled long training sequence based on IEEE 802.11a.

9. The method according to claim 8, further comprising transmitting a first long training sequence field, a second long training sequence field, and a third long training field via a subsequent to said first spatial stream, in a system utilizing 3 transmitted spatial streams, wherein said first long training sequence field, said second long training sequence field, and said third long training sequence field utilizes a multiplicatively scaled and phase shifted long training sequence based on IEEE 802.11a.

10. The method according to claim 1, further comprising, for a first spatial stream, transmitting a first long training sequence field via said current spatial stream, in a system utilizing 4 transmitted spatial streams, wherein said first long training sequence field utilizes a multiplicatively scaled long training sequence based on IEEE 802.11a.

11. The method according to claim 10, further comprising transmitting a subsequent to said first long training sequence field, via said first spatial stream, wherein said subsequent long training sequence field utilizes a long training sequence based on IEEE 802.11a.

12. The method according to claim 11, wherein a subsequent to said first spatial stream comprises a corresponding long training sequence to said first long training sequence field that utilizes said multiplicatively scaled long training sequence, and a plurality of long training sequence fields that utilize said long training sequence based on IEEE 802.11a.

13. The method according to claim 1, further comprising generating said corresponding one of said current plurality based on a discrete Fourier transform matrix.

14. A system for communicating information in a multiple input multiple output (MIMO) communications systems, the system comprising:

a transmitter that generates a protocol data unit (PDU) for a current spatial stream comprising a current plurality of long training sequence fields;

said transmitter appends a signal field subsequent to a last of said current plurality of long training sequence fields;

said transmitter generates a PDU for a subsequent spatial stream comprising a subsequent plurality of long training sequence fields wherein one of said subsequent plurality of long training sequence fields is orthonormal to a corresponding one of said current plurality of long training sequence fields; and

said transmitter appends a subsequent signal field subsequent to a last of said subsequent plurality of long training sequence fields.

15. The system according to claim 14, further comprising antenna front end circuitry that transmits 2 orthogonal frequency division multiplexing (OFDM) symbols during a first long training sequence field of said current plurality of long training sequence fields.

16. The system according to claim 15, further comprising inverse fast Fourier transform circuitry that generates said 2 OFDM symbols based on long training sequences that are approximately identical.

17. The system according to claim 15, wherein said antenna front end circuitry transmits 1 OFDM symbol during a long training sequence field that is subsequent to said first long training sequence field.

18. The system according to claim 14, further comprising antenna front end circuitry that transmits 2 OFDM symbols during said signal field.

19. The system according to claim 14, further comprising, for a first spatial stream, antenna front end circuitry that transmits a first long training sequence field, and a second long training field via said current spatial stream, in a system utilizing 2 transmitted spatial streams, wherein said first long training sequence field, and said second long training sequence field utilizes a long training sequence based on IEEE 802.11a.

20. The system according to claim 14, further comprising, for a second spatial stream, antenna front end circuitry that transmits a first long training sequence field, and a second long training field via said current spatial stream, in a system utilizing 2 transmitted spatial streams, wherein said first long training sequence field, and said second long training sequence field utilizes a phase shifted long training sequence based on IEEE 802.11a.

21. The system according to claim 14, further comprising, for a first spatial stream, antenna front end circuitry that transmits a first long training sequence field, a second long training sequence field, and a third long training field via said current spatial stream, in a system utilizing 3 transmitted spatial streams, wherein said first long training sequence field, said second long training sequence field, and said third long training sequence field utilizes a multiplicatively scaled long training sequence based on IEEE 802.11a.

22. The system according to claim 21, wherein said antenna front end circuitry transmits a first long training sequence field, a second long training sequence field, and a third long training field via a subsequent to said first spatial stream, in a system utilizing 3 transmitted spatial streams, wherein said first long training sequence field, said second long training sequence field, and said third long training sequence field utilizes a multiplicatively scaled and phase shifted long training sequence based on IEEE 802.11a.

23. The system according to claim 14, further comprising, for a first spatial stream, antenna front end circuitry that transmits a first long training sequence field via said current spatial stream, in a system utilizing 4 transmitted spatial streams, wherein said first long training sequence field utilizes a multiplicatively scaled long training sequence based on IEEE 802.11a.

24. The system according to claim 23, wherein said antenna front end circuitry transmits a subsequent to said first long training sequence field, via said first spatial stream, wherein said subsequent long training sequence field utilizes a long training sequence based on IEEE 802.11a.

25. The system according to claim 24, wherein a subsequent to said first spatial stream comprises a corresponding long training sequence to said first long training sequence field that utilizes said multiplicatively scaled long training sequence, and a plurality of long training sequence fields that utilize said long training sequence based on IEEE 802.11a.

26. The system according to claim 14, wherein said transmitter generates said corresponding one of said current plurality based on a discrete Fourier transform matrix.

27. A method for communicating information in a multiple input multiple output (MIMO) communications system, the method comprising:

constructing a mixed mode protocol data unit (PDU) comprising, a legacy short training sequence field comprising a time duration of approximately 8 microseconds;

appending a legacy long training sequence field comprising a time duration of approximately 8 microseconds, subsequent to said legacy short training sequence field;

appending a legacy signal field comprising a time duration of approximately 4 microseconds, subsequent to said legacy long training field;

appending a high throughput signal field comprising a time duration of approximately 8 microseconds, subsequent to said legacy signal field;

appending a high throughput short training sequence field comprising a time duration of approximately 3.2 microseconds, subsequent to said high throughput signal field; and

appending a plurality of long training sequence fields, comprising a time duration of approximately 4 microseconds, subsequent to said high throughput short training sequence field.