Method and apparatus for wide bandwidth mixed-mode wireless communications

• US 7,912,024 B2
• Filed: 09/03/2009
• Issued: 03/22/2011
• Est. Priority Date: 07/27/2004
• Status: Active Grant

• Current Assignee: Bell Northern Research, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Trachewsky, Jason Alexander
• Primary Examiner(s): Appiah, Charles N
• Assistant Examiner(s): Vu, Michael T
• Application Number:
  US12/553,281
• Publication Number:
  US 20100014498A1
• Time in Patent Office: 565 Days
• Field of Search: 370/338, 370/334, 370/208, 370/468, 370/349, 370/465, 455/104, 455/450, 455/422.1, 455/562.1
• US Class Current: 370/338
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04B 7/12 Frequency diversity
• CPC Class Codes: H04L 27/01 Equalisers baseband equalizers at the transmitter end H04L25/03343; in analogue transmission systems H04B3/04, H04B7/005
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 27/2618 Reduction thereof using auxiliary subcarriers
• CPC Class Codes: H04L 27/2634 Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

A network device for implementing high-rate greenfield transmission in a mixed mode frame structure. The network device is configured to transmit a mixed mode frame on two adjacent channels. The mixed mode frame comprises at least two backward compatible portions of a first frequency and a greenfield portion of a second frequency.

Claims

1. An access point that implements high-rate greenfield transmission in a mixed mode frame structure and that supports wireless MIMO communications, the access point being configured to:

wirelessly transmit at least a mixed mode frame on a first channel and a second channel, wherein the mixed mode frame comprises at least two backward compatible portions of a first frequency and a greenfield portion of a second frequency, wherein the first channel comprises channel 4n+k, wherein the second channel comprises channel 4(n+1)+k, wherein n is an integer greater than one that represents a number of transmit antennas of the access point, and wherein k is an integer from zero to three.

2. The access point according to claim 1, wherein the first channel and the second channel are 20 MHz channels that can be received independently by 20 MHz wireless legacy communication devices.

3. The access point according to claim 1, wherein the wireless legacy communication devices support 802.11a communications or 802.11g communications.

4. The access point according to claim 1, wherein duplicate copies of a 20 MHz backward compatible portion is wirelessly transmitted on each of the first channel and the second channel.

5. The access point according to claim 1, wherein each of the two backward compatible portions is a 20 MHz backward compatible portion and the greenfield portion is a 40 MHz greenfield portion that includes preamble information and data.

6. The access point according to claim 1, wherein k is equal to zero for frequencies less than 5745 MHz, wherein k is equal to zero for frequencies greater than 5825 MHz, wherein k is equal to one for frequencies greater than or equal to 5745 MHz and less than or equal to 5805 MHz.

7. The access point according to claim 1, comprising a signal generating circuit that generates data for sub-carriers on the first channel and the second channel, wherein the sub-carriers for the two backward compatible portions are centered on 20 MHz channel boundaries and the sub-carriers for the greenfield portion are double the number of sub-carriers used in the backward compatible portions.

8. The access point according to claim 7, wherein different information is wirelessly transmitted on upper and lower blocks of the sub-carriers used by the greenfield portion.

9. The access point according to claim 1, wherein power increases by less than 0.65 dB at a transition from the backward compatible portions to the greenfield portion on a flat channel.

10. The access point according to claim 1, wherein the greenfield portion on the first channel and the second channel is separated by 9.0625 MHz and a zero sub-carrier is removed or skipped.

11. The access point according to claim 1, wherein the network device is configured to support an orthogonal frequency division multiplexing encoding scheme.

12. The access point according to claim 1, wherein the at least two backward compatible portions comprise information that indicates how long to stay off the channel for the transmission of the greenfield portion.

13. The access point according to claim 1, wherein the access point provides a mixed mode 40 MHz frame structure for a greenfield 40 MHz transmission.

14. The access point according to claim 13, wherein the mixed mode 40 MHz frame structure can be used for 5 GHz communications and 2.4 GHz communications.

15. The access point according to claim 1, wherein the access point provides medium access control mechanisms that instruct wireless legacy communication devices to stay off the first channel and the second channel during the transmission of the greenfield portion.

16. The access point according to claim 1, wherein the greenfield portion is protected from channel collision by a physical layer protection scheme.

17. The access point according to claim 16, wherein the wireless legacy communication devices are instructed to stay off the first channel and the second channel during the transmission of the greenfield portion even if a medium access control mechanism is missed by the wireless legacy communication devices, wherein the medium access control mechanism instructs the wireless legacy communication devices to stay off the first channel and the second channel during the transmission of the green field portion.

18. A wireless communication device that transmits a greenfield transmission in a mixed mode frame structure and that supports wireless MIMO communications, the wireless communication device comprising:

a first generator that generates a plurality of backward compatible portions of a first frequency and provides a length and rate combination such that wireless legacy devices will stay off a channel for a length of a greenfield transmission;

a second generator that generates a greenfield portion of a second frequency, passes a dummy length and a dummy rate to the generator for a backward compatible portion and instructs the first generator to provide the length and rate combination to ensure backward compatibility with the wireless legacy devices, wherein outputs from the first generator and the second generator are multiplexed into symbol mappers that correspond to a number of transmit antennas of the access point; and

processing modules that process a mixed mode frame to be wirelessly transmitted on a first channel and a second channel, wherein the first channel and the second channel can be wirelessly received independently by the wireless legacy devices, wherein the mixed mode frame comprises at least two backward compatible portions of a first frequency and a greenfield portion of a second frequency.

19. The wireless communication device according to claim 18, wherein each of the symbol mappers generates symbols from coded bits for each sub-carrier of an orthogonal frequency division multiplexing sequence.

20. The wireless communication device according to claim 18, wherein the processing modules comprise Inverse Fast Fourier transforms, digital filters and digital to analog converters.

21. The wireless communication device according to claim 20, wherein each of the Inverse Fast Fourier transforms comprises a 128 point Inverse fast Fourier transform.

22. The wireless communication device according to claim 18, wherein the access point supports an orthogonal frequency division multiplexing encoding scheme.

23. The wireless communication device according to claim 18, wherein the wireless communication device is an access point or a base station.

24. The wireless communication device according to claim 18, wherein the wireless communication device is a laptop computer, a personal digital assistant host or a cellular telephone.

25. The wireless communication device according to claim 18, wherein wireless legacy devices support 802.11a communications or 802.11g communications.

26. In an access point or a base station that supports wireless MIMO communications, a method for transmitting a greenfield transmission in a mixed mode frame structure, the method comprising:

generating a plurality of backward compatible portions of a first frequency;

generating a greenfield portion of a second frequency;

passing a dummy length and a dummy rate to a generator for a backward compatible portion and instructing a generator for a backward compatible portion to provide a length and rate combination;

providing the length and rate combination such that wireless legacy devices will stay off a channel for a length of a greenfield transmission;

multiplexing the plurality of backward compatible portions and the greenfield portion into symbol mappers, a number of the symbol mappers corresponding to a number of transmit antennas of the access point or the base station; and

wirelessly transmitting a mixed mode frame on two adjacent channels that can be received independently by wireless legacy stations, wherein the mixed mode frame comprises at least two backward compatible portions of a first frequency and a greenfield portion of a second frequency.

27. The method according to claim 26, wherein the access point or the base station supports an orthogonal frequency division multiplexing encoding scheme.

28. The method according to claim 27, wherein the wireless legacy stations support 802.11a communications or 802.11g communications.