Pilot transmission schemes for wireless multi-carrier communication systems
First Claim
1. A method of transmitting a pilot on a downlink in a wireless multi-carrier communication system, comprising:
- generating pilot symbols for transmission on a first set of subbands, wherein the first set of subbands is used for pilot transmission by a first transmitting entity and is disjoint from a second set of subbands used for pilot transmission by a second transmitting entity;
processing the pilot symbols to obtain a pilot signal having the pilot symbols included in the first set of subbands; and
transmitting the pilot signal from the first transmitting entity.
1 Assignment
0 Petitions
Accused Products
Abstract
Pilot transmission schemes suitable for use in wireless multi-carrier (e.g., OFDM) communication systems. These pilot transmission schemes may utilize frequency, time, or both frequency and time orthogonality to achieve orthogonality among the pilots transmitted by multiple base stations on the downlink. Frequency orthogonality is achieved by transmitting pilots on disjoint sets of subbands. Time orthogonality is achieved by transmitting pilots using different orthogonal codes (e.g., Walsh codes). The pilots may also be scrambled with different scrambling codes, which are used to randomize pilot interference and to enable identification of the transmitters of these pilots. Pilot interference cancellation may be performed to improve performance since subbands used for data transmission by one transmitter may also be used for pilot transmission by another transmitter. Pilot interference is estimated and then subtracted from received symbols to obtain pilot-canceled symbols having improved quality.
-
Citations
63 Claims
-
1. A method of transmitting a pilot on a downlink in a wireless multi-carrier communication system, comprising:
-
generating pilot symbols for transmission on a first set of subbands, wherein the first set of subbands is used for pilot transmission by a first transmitting entity and is disjoint from a second set of subbands used for pilot transmission by a second transmitting entity;
processing the pilot symbols to obtain a pilot signal having the pilot symbols included in the first set of subbands; and
transmitting the pilot signal from the first transmitting entity. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. An apparatus in a wireless multi-carrier communication system, comprising:
-
means for generating pilot symbols for transmission on a first set of subbands, wherein the first set of subbands is used for pilot transmission by a first transmitting entity and is disjoint from a second set of subbands used for pilot transmission by a second transmitting entity;
means for processing the pilot symbols to obtain a pilot signal having the pilot symbols included in the first set of subbands; and
means for transmitting the pilot signal from the first transmitting entity. - View Dependent Claims (9, 10)
-
-
11. A base station in a wireless multi-carrier communication system, comprising:
-
at least one pilot processor operative to receive and process pilot symbols designated for transmission on a first set of subbands, wherein the first set of subbands is used for pilot transmission by the base station and is disjoint from a second set of subbands used for pilot transmission by another base station in the system;
a transform unit operative to derive time-domain samples having the covered pilot symbols included in the first set of subbands; and
a transmitter unit operative to process the time-domain samples to obtain a pilot signal for transmission on a downlink.
-
-
12. A computer-readable medium for transmitting a pilot on a downlink in a wireless multi-carrier communication system, the computer-readable medium comprising instructions which, when executed by a processor, cause said processor to perform the steps of:
-
generating pilot symbols for transmission from a first transmitting entity on a first set of subbands that is disjoint from a second set of subbands used for pilot transmission by a second transmitting entity; and
processing the pilot symbols to obtain time-domain samples having the pilot symbols included in the first set of subbands.
-
-
13. A method of processing pilots received via a downlink in a wireless multi-carrier communication system, comprising:
-
receiving a first pilot signal on a first set of subbands from a first transmitting entity, wherein the first set of subbands is used for pilot transmission by the first transmitting entity and is disjoint from a second set of subbands used for pilot transmission by a second transmitting entity; and
processing the first pilot signal to obtain a pilot estimate for each of the subbands in the first set. - View Dependent Claims (14, 15, 16, 17, 18)
-
-
19. An apparatus in a wireless multi-carrier communication system, comprising:
-
means for receiving a first pilot signal on a first set of subbands from a first transmitting entity, wherein the first set of subbands is used for pilot transmission by the first transmitting entity and is disjoint from a second set of subbands used for pilot transmission by a second transmitting entity; and
means for processing the first pilot signal to obtain a pilot estimate for each of the subbands in the first set. - View Dependent Claims (20, 21)
-
-
22. A terminal in a wireless multi-carrier communication system, comprising:
-
a receiver unit operative to process a pilot signal received on a first set of subbands, wherein the first set of subbands is used for pilot transmission by a first transmitting entity and is disjoint from a second set of subbands used for pilot transmission by a second transmitting entity; and
at least one pilot processor operative to process the pilot signal to obtain a pilot estimate for each of the subbands in the first set.
-
-
23. A computer-readable medium for processing pilots received via a downlink in a wireless multi-carrier communication system, the computer-readable medium comprising instructions which, when executed by a processor, cause said processor to perform the steps of:
-
receiving a first pilot signal on a first set of subbands from a first transmitting entity, wherein the first set of subbands is used for pilot transmission by the first transmitting entity and is disjoint from a second set of subbands used for pilot transmission by a second transmitting entity; and
processing the first pilot signal to obtain a pilot estimate for each of the subbands in the first set.
-
-
24. A method of transmitting a pilot in a wireless multi-carrier communication system, comprising:
-
generating pilot symbols for transmission on a first set of subbands used for pilot transmission by a first transmitting entity;
processing the pilot symbols with a first code to obtain covered pilot symbols, wherein the first code is orthogonal to a second code used for pilot transmission by a second transmitting entity;
processing the covered pilot symbols to obtain a pilot signal having the pilot symbols included in the first set of subbands; and
transmitting the pilot signal from the first transmitting entity. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
-
-
41. An apparatus in a wireless multi-carrier communication system, comprising:
-
means for generating pilot symbols for transmission on a set of subbands used for pilot transmission by a first transmitting entity;
means for processing the pilot symbols with a first code to obtain covered pilot symbols, wherein the first code is orthogonal to a second code used for pilot transmission by a second transmitting entity;
means for processing the covered pilot symbols to obtain a pilot signal having the pilot symbols included in the set of subbands; and
means for transmitting the pilot signal from the first transmitting entity. - View Dependent Claims (42)
-
-
43. A base station in a wireless multi-carrier communication system, comprising:
-
at least one pilot processor operative to receive and process pilot symbols with a first code to obtain covered pilot symbols, wherein the pilot symbols are designated for transmission on a set of subbands used for pilot transmission by the base station, and wherein the first code is orthogonal to a second code used for pilot transmission by another base station in the system;
a transform unit operative to derive time-domain samples having the covered pilot symbols included in the set of subbands; and
a transmitter unit operative to process the time-domain samples to obtain a pilot signal for transmission over a wireless link.
-
-
44. A computer-readable medium for transmitting a pilot in a wireless multi-carrier communication system, the computer-readable medium comprising instructions which, when executed by a processor, cause said processor to perform the steps of:
-
generating pilot symbols for transmission on a first set of subbands used for pilot transmission by a first transmitting entity;
processing the pilot symbols with a first code to obtain covered pilot symbols, wherein the first code is orthogonal to a second code used for pilot transmission by a second transmitting entity; and
processing the covered pilot symbols to obtain a pilot signal having the pilot symbols included in the first set of subbands.
-
-
45. A method of processing pilots received via a wireless link in a wireless multi-carrier communication system, comprising:
-
receiving a first pilot signal on a first set of subbands used for pilot transmission by a first transmitting entity;
processing the first pilot signal with a first code to obtain decovered symbols for the first transmitting entity, wherein the first code is used for pilot transmission by the first transmitting entity and is orthogonal to a second code used for pilot transmission by a second transmitting entity; and
processing the decovered symbols for the first transmitting entity to obtain a pilot estimate for each of the subbands in the first set. - View Dependent Claims (46, 47, 48, 49, 50)
-
-
51. An apparatus in a wireless multi-carrier communication system, comprising:
-
means for receiving a pilot signal on a set of subbands used for pilot transmission by a first transmitting entity;
means for processing the pilot signal with a first code to obtain decovered symbols, wherein the first code is used for pilot transmission by the first transmitting entity and is orthogonal to a second code used for pilot transmission by a second transmitting entity; and
means for processing the decovered symbols to obtain a pilot estimate for each of the subbands in the set.
-
-
52. A terminal in a wireless multi-carrier communication system, comprising:
-
a receiver unit operative to process a pilot signal received on a set of subbands used for pilot transmission by a first transmitting entity; and
at least one pilot processor operative to process the pilot signal with a first code to obtain decovered symbols and to process the decovered symbols to obtain a pilot estimate for each of the subbands in the set, wherein the first code is used for pilot transmission by the first transmitting entity and is orthogonal to a second code used for pilot transmission by a second transmitting entity.
-
-
53. A computer-readable medium for processing pilots received via a wireless link in a wireless multi-carrier communication system, the computer-readable medium comprising instructions which, when executed by a processor, cause said processor to perform the steps of:
-
receiving a first pilot signal on a first set of subbands used for pilot transmission by a first transmitting entity;
processing the first pilot signal with a first code to obtain decovered symbols for the first transmitting entity, wherein the first code is used for pilot transmission by the first transmitting entity and is orthogonal to a second code used for pilot transmission by a second transmitting entity; and
processing the decovered symbols for the first transmitting entity to obtain a pilot estimate for each of the subbands in the first set.
-
-
54. A method of canceling pilot interference at a receiver in a wireless multi-carrier communication system, comprising:
-
obtaining received symbols for a plurality of subbands, wherein the received symbols include desired symbols received from a first transmitting entity and pilot symbols received from a second transmitting entity;
deriving pilot symbol estimates for the second transmitting entity based on the received symbols, wherein the pilot symbol estimates are estimates of pilot symbols received on the plurality of subbands from the second transmitting entity; and
subtracting the pilot symbol estimates for the second transmitting entity from the received symbols to obtain pilot-canceled symbols. - View Dependent Claims (55, 56, 57, 58, 59, 60, 61)
-
-
62. An apparatus in a wireless multi-carrier communication system, comprising:
-
means for obtaining received symbols for a plurality of subbands, wherein the received symbols include desired symbols received from a first transmitting entity and pilot symbols received from a second transmitting entity;
means for deriving pilot symbol estimates for the second transmitting entity based on the received symbols, wherein the pilot symbol estimates are estimates of pilot symbols received on the plurality of subbands from the second transmitting entity; and
means for subtracting the pilot symbol estimates for the second transmitting entity from the received symbols to obtain pilot-canceled symbols.
-
-
63. A terminal in a wireless multi-carrier communication system, comprising:
-
at least one pilot interference estimator operative to process received symbols for a plurality of subbands to obtain pilot symbol estimates for the plurality of subbands, wherein the received symbols include desired symbols received from a first transmitting entity and pilot symbols received from a second transmitting entity, and wherein the pilot symbol estimates are estimates of pilot symbols received on the plurality of subbands from the second transmitting entity; and
a summer operative to subtract the pilot symbol estimates from the received symbols to obtain pilot-canceled symbols.
-
Specification