Channel estimation for orthogonal preambles in a MIMO system

• US 20070076811A1
• Filed: 12/09/2005
• Published: 04/05/2007
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Aldana, Carlos, Trachewsky, Jason
• Granted Patent: US 7,693,228 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04L 25/0204 of multiple channels

Abstract

A general architecture scheme to perform channel estimation on orthogonal transmissions for any number of transmitting antennas present. Generally, the channel estimation is applicable for wireless communications in a MIMO system.

Claims

1. A method comprising:

separating data into multiple transmitting paths to transmit the data from one or more transmitting antennas by including an orthogonal preamble having training symbols, in which a number of training symbols sent by each transmitting antenna is determined by either a number of transmitting antennas or data streams utilized to send the data; and

transmitting the orthogonal preamble to allow a receiver to perform channel estimation by utilizing the training symbols.

2. The method of claim 1, wherein the preamble includes generating the training symbols to be sent in multiple time blocks, in which a number of time blocks to be sent is determined by the number of transmitting antennas or data streams.

3. The method of claim 2, wherein separating the data includes placing data into data channels, in which the data channels are categorized into indices to be sent in each time block and in which the preamble is also categorized into the data channels to be sent in multiple time blocks.

4. The method of claim 3, wherein separating the data includes placing the data into even and odd data channels for a transmitter having two transmitting antennas and wherein the preamble is sent in two time blocks from each antenna.

5. The method of claim 4, wherein transmitting the preamble includes sending even data channels from a first antenna and odd data channels from a second antenna during a first time period and sending odd data channels from the first antenna and even data channels from the second antenna during a second time period.

6. The method of claim 4, wherein transmitting the preamble includes sending a first training symbol having a coefficient value “

d”

from a first antenna and a second training symbol having a coefficient value “

−

b”

from a second antenna during a first time block; and

sending a third training symbol having a coefficient value “

−

c”

from the first antenna and a fourth training symbol having a coefficient value “

a”

from the second antenna during a second time block, where “

a”

, “

−

b”

, “

−

c” and

“

d”

are predetermined values.

7. The method of claim 6, wherein the coefficient values “

a” and

“

b”

have a value of 1/√

2 and “

−

b” and

“

−

c”

have a value of 0 for even data channels; and

wherein the coefficient values “

a” and

“

b”

have a value of 0 and “

−

b” and

“

−

c”

have a value of −

1/√

2 for odd data channels.

8. The method of claim 2, wherein separating the data includes placing data into multiple data channels and categorized into a number of indices, the number of indices corresponding to “

Q”

number of transmitting antennas being utilized and wherein the preamble is sent as symbols in “

Q”

time blocks from each transmitting antenna, and in which each transmitting antenna transmits set of indices, but at different time blocks.

9. The method of claim 8, wherein separating the data includes separating data into data channels categorized into three indices for a transmitter having three transmitting antennas and wherein transmitting the preamble includes sending a first training symbol having a coefficient value “

d”

from a first antenna, a second training symbol having a coefficient value “

−

b”

from a second antenna and a third training symbol having a coefficient “

g”

from a third antenna during a first time block;

sending a fourth training symbol having a coefficient value “

−

c”

from the first antenna, a fifth training symbol having a coefficient value “

a”

from the second antenna and a sixth training symbol having a coefficient “

h”

from the third antenna during a second time block; and

sending a seventh training symbol having a coefficient value “

e”

from the first antenna, an eighth training symbol having a coefficient value “

f”

from the second antenna and a ninth training symbol having a coefficient “

j”

from the third antenna during a third time block, where “

a”

, “

−

b”

, “

−

c”

, “

d”

, “

e”

, “

f”

, “

g”

, “

h” and

“

j”

are predetermined values.

10. A method comprising:

receiving data transmitted from one or more transmitting antennas that includes an orthogonal preamble having training symbols, in which a number of training symbols sent by each transmitting antenna is determined by either a number of transmitting antennas or data streams utilized to send the data; and

performing channel estimation by utilizing the training symbols.

11. The method of claim 10, wherein receiving the preamble includes receiving the training symbols in multiple time blocks, in which a number of time blocks is determined by the number of transmitting antennas or data streams used to transmit the data.

12. The method of claim 11, wherein receiving the preamble includes receiving training symbols in data channels that are frequency indexed as even and odd data channels, in which a first even training symbol and a first odd training symbol are received during a first time block, the first even and first odd training symbols transmitted from a first and second transmitting antennas respectively, and a second even training symbol and a second odd training symbol are received during a second time block, the second even and second odd training symbols transmitted from a second and first transmitting antennas respectively.

13. The method of claim 11, wherein receiving the preamble includes receiving training symbols in data channels that are frequency indexed as first set and second set of data channels, in which a first training symbol having a coefficient value “

d”

that was sent from a first transmitting antenna is received during a first time block, a second training symbol having a coefficient value “

−

b”

that was sent from a second transmitting antenna is received during the first time block, a third training symbol having a coefficient value “

−

c”

that was sent from the first transmitting antenna is received during a second time block, and a fourth training symbol having a coefficient value “

a”

that was sent from the second transmitting antenna is received during the second time block, where “

a”

, “

−

b”

, “

−

c” and

“

d”

are predetermined values.

14. The method of claim 13, wherein the coefficient values “

a” and

“

b”

have a value of 1/√

2 and “

−

b” and

“

−

c”

have a value of 0 for data channels that are frequency indexed as the first set; and

wherein the coefficient values “

a” and

“

b”

have a value of 0 and “

−

b” and

“

−

c”

have a value of −

1/√

2 for data channels that are frequency indexed as the second set.

15. The method of claim 13, wherein receiving the preamble includes receiving the preamble by multiple receiving antennas.

16. The method of claim 11, wherein receiving the preamble includes receiving training symbols in data channels that are frequency indexed as first set, second set and third set of data channels, in which a first training symbol having a coefficient value “

d”

that was sent from a first transmitting antenna, a second training symbol having a coefficient value “

−

b”

that was sent from a second transmitting antenna, and a third training symbol having a coefficient “

g”

that was sent from a third antenna are received during a first time block;

a fourth training symbol having a coefficient value “

−

c”

that was sent from the first transmitting antenna, a fifth training symbol having a coefficient value “

a”

that was sent from the second transmitting antenna and a sixth training symbol having a coefficient “

h”

that was sent from the third antenna are received during a second time block; and

a seventh training symbol having a coefficient value “

e”

that was sent from the first transmitting antenna, an eighth training symbol having a coefficient value “

f”

that was sent from the second transmitting antenna and a ninth training symbol having a coefficient “

j”

that was sent from the third transmitting antenna are received during a third time block, where “

a”

, “

−

b”

, “

−

c”

, “

d”

, “

e”

, “

f”

, “

g”

, “

h” and

“

j”

are predetermined values and where first second and third set of data channels are sent from each transmitting antenna at different time blocks and first, second and third set of data channels are sent in each time block.

17. The method of claim 16 wherein receiving the preamble includes receiving the preamble by multiple receiving antennas.

18. An apparatus comprising a receiver to receive data transmitted from one or more transmitting antennas that includes an orthogonal preamble having training symbols, in which a number of training symbols sent by each transmitting antenna is determined by either a number of transmitting antennas or data streams utilized to send the data, the receiver to perform channel estimation by utilizing the training symbols.

19. The apparatus of claim 18, wherein the receiver to receive the training symbols in multiple time blocks, in which a number of time blocks is determined by the number of transmitting antennas or data streams used to transmit the data.

20. The apparatus of claim 19, wherein the receiver to receive the training symbols in data channels that are frequency indexed as even and odd data channels, in which a first even training symbol and a first odd training symbol are received during a first time block, the first even and first odd training symbols transmitted from a first and second transmitting antennas respectively, and a second even training symbol and a second odd training symbol are received during a second time block, the second even and second odd training symbols transmitted from a second and first transmitting antennas respectively.