METHOD FOR CHANNEL ESTIMATION IN A POINT-TO-POINT COMMUNICATION NETWORK.

• US 20090010238A1
• Filed: 07/05/2007
• Published: 01/08/2009
• Est. Priority Date: 07/05/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: DesignArt Networks Limited (Qualcomm, Inc.)
• Inventors: BARAK, Oz, TOUBOUL, Assaf, WOLF, Guy
• Granted Patent: US 8,605,687 B2
• Time in Patent Office: Days
• US Class Current: 370/342
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26134 Pilot insertion in the transmitter chain, e.g. pilot overlapping with data, insertion in time or frequency domain
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal

Abstract

A method of using pilot signals in a wireless communication network including encoding pilot signals, and transmitting the encoded pilot signals over an in-band backhaul link between two nodes in the network. Preferably, the pilot signals are encoded with a CDMA codeword associated with a link. The pilot signals can be decoded to permit estimation of a channel and interference attributable to each link.

Claims

1. A method of using pilot signals in a wireless communication network comprising:

encoding pilot signals; and

transmitting said encoded pilot signals over an in-band backhaul link between two nodes in the network.

2. The method according to claim 1, wherein said step of encoding includes encoding pilot signals with a CDMA codeword associated with a link.

3. The method according to claim 1, further comprising decoding encoded pilot signals associated with at least one link in said network, and estimating channel noise attributable to each of said at least one link.

4. The method according to claim 1, wherein said step of estimating includes calculating a channel Ĥ

by

5. The method according to claim 1, further comprising:

dividing, in a transmitter, a frame of OFDMA symbols into tiles, each tile including a group of time and frequency slices,

mapping CDMA-encoded pilot signals onto a selected number of such slots in each tile,

mapping data signals onto remaining OFDMA slots in each tile,

decoding the pilot signals received in a receiver; and

using the decoded pilot signals to estimate channel response over a link.

6. A method for estimating a channel of a selected in-band backhaul link in a wireless communication network including a plurality of in-band backhaul links, the method comprising:

allocating one of a family of CDMA codewords to each of said in-band backhaul links to identify said link;

encoding a pilot transmission using said codeword;

transmitting said encoded pilot transmission over the channel of the selected in-band link;

receiving and decoding said encoded pilot transmission;

estimating said channel using said pilot transmission and said decoded received pilot transmission.

7. The method of claim 6, wherein said step of decoding includes decoding said received pilot value using a CDMA codeword assigned to the selected link.

8. The method of claim 6, wherein said step of decoding includes decoding said received pilot value using a CDMA codeword assigned to a link other than the selected link, so as to estimate interference of said other link on the selected link during concurrent transmission.

9. The method of claim 6, wherein said steps of receiving and estimating are performed in a link other than said selected link.

10. The method according to claim 6, wherein said step of estimating includes calculating the channel Ĥ

by

11. The method according to claim 6, further comprising:

dividing, in a transmitter, a frame of OFDMA symbols into tiles, each tile including a group of time and frequency slices;

mapping CDMA-encoded pilot signals onto a selected number of such slots in each tile;

mapping data signals onto remaining OFDMA slots in each tile;

decoding the pilot signals received in a receiver; and

estimating said channel over a link using said decoded pilot signals.

12. A method for channel estimation in a wireless communication network, having point-to-point backhaul over a channel between a first and second node forming a link, the method comprising:

assigning at least one pilot value to said link;

assigning a codeword from a family of CDMA codes to said link;

encoding said pilot value in a transmitter of said first node using said assigned codeword;

transmitting said encoded pilot value;

decoding said transmitted pilot value in a receiver of said second node using said assigned codeword; and

estimating the channel of said link by utilizing said pilot value, said codeword and said decoded pilot signal.

What about the interference estimation??

13. The method according to claim 12, wherein said step of assigning includes assigning more than one codeword from said family of CDMA codes to said link.

14. The method according to claim 12, wherein the network is a mobile wireless network selected from WiMAX, 3GPP-LTE, WiFi and IEEE 208.20.

15. Apparatus for utilizing pilot signals in a wireless communication network, the apparatus comprising:

an encoder for encoding pilot signals; and

a transceiver for transmitting said encoded pilot signals over an in-band backhaul link between two nodes in the network.

16. The apparatus according to claim 15, wherein said encoder includes an encoder for encoding pilot signals by a CDMA codeword selected from a family of CDMA codes to identify an associated link.

17. The apparatus according to claim 16, further comprising:

a decoder for decoding encoded pilot signals associated with at least one link in said network; and

a processor for estimating channel noise attributable to each of said at least one link.

18. Apparatus for channel estimation comprising:

a symbol builder in a transmitter, the symbol builder including;

a multiplexer for multiplexing a codeword from a family of CDMA codes with a pilot value assigned to a link; and

a tile physical mapper for mapping data symbols with said multiplexed coded pilot value onto an OFDMA frame.

19. The apparatus according to claim 18, further comprising a channel estimator in a receiver including:

a multiplexer for multiplexing a selected codeword from a family of CDMA codes with a pilot value assigned to a link to provide a decoding value;

a multiplier for multiplying a received signal by said decoding value; and

an accumulator for calculating a cross correlation product over a plurality of pilot signals so as to provide a channel estimation value.

20. The apparatus according to claim 18, further comprising a pilot value generator for generating said pilot value.

21. The apparatus according to claim 18, further comprising a codeword generator for generating said selected codeword.

22. The apparatus according to claim 19, further comprising a pilot value generator coupled to said multiplexer for generating said pilot value.

23. The apparatus according to claim 19, further comprising a codeword generator coupled to said multiplexer for generating said selected codeword.

24. Apparatus for channel estimation for a wireless network including a plurality of nodes coupled for wireless communication in virtual clusters of nodes, each cluster including a feeder node coupled to a core network, a wireless link being formed between each pair of adjacent nodes, each node including at least one transceiver providing mobile access communication and in-band backhaul communication over the link;

a modem coupled to each transceiver; and

a plurality of antennas mounted in the node, one coupled to each transceiver, the antennas being able to provide multiple concurrent transmissions over multiple antennas;

a controller in each node adapted and configured for control and coordination of the transceivers and associated modems, the apparatus comprising;

elements in a transmitter for dividing a frame of OFDMA symbols into tiles, each tile including a group of time and frequency slices,

a tile mapper for mapping CDMA-encoded pilot signals onto a selected number of such slots in each tile, and for mapping data signals onto the remaining slots in each tile,

a decoder in said transceiver for decoding pilot signals received in said transceiver; and

an accumulator for using said decoded pilot signals to estimate a channel over a link.

25. The apparatus according to claim 24, further comprising means for providing said channel estimation to a feeder node, and causing the feeder node to adjust backhaul link parameters of links in its cluster.

26. The apparatus according to claim 24, wherein said network is a mobile wireless network selected from WiMAX, 3GPP-LTE, WiFi and IEEE 208.20.