Multipath interference reduction on pilot estimation with legacy system interoperability

• US 7,590,169 B2
• Filed: 02/06/2006
• Issued: 09/15/2009
• Est. Priority Date: 02/07/2005
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gaal, Peter
• Primary Examiner(s): Bayard; Emmanuel
• Application Number:
  US11/349,388
• Publication Number:
  US 20060227857A1
• Time in Patent Office: 1,317 Days
• Field of Search: 375/148, 375/260, 375/219, 375/220, 375/222, 370208-210
• US Class Current: 375/220
• CPC Class Codes: H04L 2025/03522 Frequency domain
• CPC Class Codes: H04L 2025/03789 Codes therefore
• CPC Class Codes: H04L 25/03159 operating in the frequency domain H04L25/03165, H04L25/03178 take precedence

Abstract

System, base station and method for supporting frequency domain equalization for frequency domain equalization-capable mobile stations and supporting improved channel estimation for both time domain and frequency domain equalization-capable mobile stations on the forward link without the necessity of modifications to an air-interface specification of a legacy communication system. A first signal sequence is generated according to a first format and an offset vector is also generated. The first signal sequence and the offset vector are combined to form a second signal sequence according to a second format. The second signal sequence of said second format supports frequency domain equalization in one or more frequency domain-capable mobile stations. The second signal sequence maintains compatibility with one or more legacy mobile stations.

Claims

1. A method for maintaining interoperation of one or more legacy mobile stations operable according to a first format while supporting one or more frequency domain equalization-capable mobile stations operable according to a second format, comprising:

generating a first signal sequence according to a first format;

generating an offset vector; and

combining said first signal sequence with said offset vector to form a second signal sequence according to a second format, said second signal sequence of said second format supporting frequency domain equalization in one or more frequency domain-capable mobile stations, said second signal sequence maintaining compatibility with one or more legacy mobile stations.

2. The method of claim 1, further comprising setting a first m chips of every symbol in said first signal sequence to zero.

3. The method of claim 1, further comprising setting m equally spaced values in an FFT of the second format to a known value.

4. The method of claim 3, wherein the known value is √

{square root over (I_or/N)}, where N is the symbol length used in the frequency domain equalized mobile stations and I_or is the total transmit power of the base station sector.

5. The method of claim 1, wherein said generating an offset vector comprises creating a differential vector for summing with the first format, the differential vector having a cross-correlation with a pilot channel of a same magnitude but opposite phase as a cross correlation of said second signal sequence and the pilot channel.

6. The method of claim 1, further comprising transmitting said second signal sequence for operability of both said one or more legacy mobile stations and said second one or more frequency domain equalization-capable mobile stations.

7. A base station, comprising:

an encoder for encoding a plurality of message data bits into a plurality of code symbols;

a signal modifier configured to generate a first signal sequence according to a first format and generate an offset vector; and

a summer for combining said first signal sequence with said offset vector to form a second signal sequence according to a second format, said second signal sequence of said second format supporting frequency domain equalization in one or more frequency domain-capable mobile stations, said second signal sequence maintaining compatibility with one or more legacy mobile stations.

8. The base station of claim 7, wherein said signal modifier is further configured to set a first m chips of every symbol in said first signal sequence to zero.

9. The base station of claim 7, wherein said signal modifier is further configured to set m equally spaced values in an FFT of the second format to a known value.

10. The base station of claim 9, wherein the known value is √

{square root over (I_or/N)}, where N is the symbol length used in the frequency domain equalized mobile stations and I_or is the total transmit power of the base station sector.

11. The base station of claim 7, wherein said signal modifier is configured to generate said offset vector as a result of creating a differential vector for summing with the first format, the differential vector having a cross-correlation with a pilot channel of a same magnitude but opposite phase as a cross correlation of said second signal sequence and said pilot channel.

12. The base station of claim 7, further including a transmitter configured to transmit said second signal sequence for operability of both said one or more legacy mobile stations and said one or more frequency domain equalization-capable mobile stations.

13. A wireless communication system comprising:

a one or more non-frequency domain equalization-capable mobile stations configured to operate according to a first format;

a second one or more frequency domain equalization-capable mobile stations configured to operate according to a second format; and

a base station configured for maintaining interoperation of one or more non-frequency domain equalization-capable mobile stations operable according to a first format while supporting one or more frequency domain equalization-capable mobile stations operable according to a second format.

14. The wireless communication system of claim 13, wherein said base station comprises:

an encoder for encoding a plurality of message data bits into a plurality of code symbols;

a signal modifier configured to generate a first signal sequence according to a first format and generate an offset vector; and

a summer for combining said first signal sequence with said offset vector to form a second signal sequence according to a second format, said second signal sequence of said second format supporting frequency domain equalization in one or more frequency domain-capable mobile stations, said second signal sequence maintaining compatibility with one or more non-frequency domain-capable mobile stations.

15. The wireless communication system of claim 14, wherein said signal modifier is further configured to set a first m chips of every symbol in said first signal sequence to a known value.

16. The wireless communication system of claim 14, wherein said signal modifier is further configured to set m equally spaced values in an FFT of the second format to √

{square root over (I_or/N)}, where N is the symbol length used in the frequency domain equalized mobile stations and I_or is the total transmit power of the base station sector.

17. The wireless communication system of claim 14, wherein said signal modifier is configured to generate said offset vector as a result of creating a differential vector for summing with the first format, the differential vector having a cross-correlation with a pilot channel of a same magnitude but opposite phase as a cross correlation of said second signal sequence and said pilot channel.

18. The wireless communication system of claim 14, further including a transmitter configured to transmit said second signal sequence for operability of both said one or more legacy mobile stations and said one or more frequency domain equalization-capable mobile stations.

19. An apparatus for maintaining interoperation of one or more legacy mobile stations operable according to a first format while supporting one or more frequency domain-capable mobile stations operable according to a second format, comprising:

means for generating a first signal sequence according to a first format;

means for generating an offset vector; and

means for combining said first signal sequence with said offset vector to form a second signal sequence according to a second format, said second signal sequence of said second format supporting frequency domain equalization in one or more frequency domain-capable mobile stations, said second signal sequence maintaining compatibility with one or more legacy mobile stations.

20. The apparatus of claim 19, further comprising a means for setting a first m chips of every symbol in said first signal sequence to zero.

21. The apparatus of claim 19, further comprising a means for setting m equally spaced values in an FFT of the second format to √

{square root over (I_or/N)}, where N is the symbol length used in the frequency domain equalized mobile stations and I_or is the total transmit power of the base station sector.

22. The apparatus of claim 19, wherein said means for generating an offset vector comprises creating a differential vector for summing with the first format, the differential vector having a cross-correlation with a pilot channel of a same magnitude but opposite phase as a cross correlation of said second signal sequence and the pilot channel.

23. The apparatus of claim 19, further comprising means for transmitting said second signal sequence for operability of both said one or more legacy mobile stations and said second one or more frequency domain equalization-capable mobile stations.