Pilot transmission schemes for wireless multi-carrier communication systems

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, and wherein each pair of adjacent subbands in the first set encompasses a frequency span that is less than or equal to a coherence bandwidth of a wireless channel in the system;
• 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.

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, and wherein each pair of adjacent subbands in the first set encompasses a frequency span that is less than or equal to a coherence bandwidth of a wireless channel 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.

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;
• processing the covered pilot symbols with a scrambling code to obtain scrambled pilot symbols, and wherein the scrambled pilot symbols are further processed to obtain the pilot signal, wherein the first code includes chips, and wherein each chip of the scrambling code is applied to pilot symbols;
• and
• transmitting the pilot signal from the first transmitting entity.

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;
• means for processing the covered pilot symbols with a scrambling code to obtain scrambled pilot symbols, and wherein the scrambled pilot symbols are further processed to obtain the pilot signal, wherein the first code includes chips, and wherein each chip of the scrambling code is applied to pilot svmbols;
• and
• means for transmitting the pilot signal from the first transmitting entity.

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, the covered pilot symbols are processed with a scrambling code to obtain scrambled pilot symbols, and wherein the scrambled pilot symbols are further processed to obtain the pilot signal, wherein the first code includes chips, and wherein each chip of the scrambling code is applied to pilot symbol;
• 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.

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 with a scrambling code to obtain scrambled pilot symbols, and wherein the scrambled pilot symbols are further processed to obtain the pilot signal, wherein the first code includes chips, and wherein each chip of the scrambling code is applied to pilot symbols.

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.

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.

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.

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.

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.