Method and apparatus for extracting large-scale features in propagation channels via non-orthogonal pilot signal designs

A non-transitory computer readable storage medium that stores instructions, which when executed on a base station, causes the base station to perform a method comprising:

• receiving transmissions of uplink pilot signals made in each slot, by a number of UEs, over the radio resource elements in slots that are allocated for uplink pilot transmission, wherein the number of UEs in the vicinity of at least one base station exceeds the number of radio resource elements that have been allocated for uplink pilot transmission in the slot;
• estimating large-scale radio-channel propagation strengths of a plurality of nearby UEs to a base station;
• estimating radio-propagation channel coefficients between each base-station antenna and each UE in a subset of UEs in the plurality of nearby UEs that have the large-scale radio-channel propagation strengths to the base station that are stronger than those UEs in the plurality of nearby UEs not part of the subset, the subset of UEs including in-cell UEs and one or more nearby out-of-cell UEs;
• and
• transmitting data to the in-cell UEs via multi-user beamforming, including the data suppressing interference to the one or more nearby out-of-cell UEs that are part of the plurality of nearby UEs based on the radio-propagation channel coefficients estimates.

A base station comprising:

• a plurality of antennas operable to receive transmissions of uplink pilot signals made in each slot, by a number of UEs, over the radio resource elements in slots that are allocated for uplink pilot transmission, wherein the number of UEs in the vicinity of at least one base station exceeds the number of radio resource elements that have been allocated for uplink pilot transmission in the slot;
• transmitter and receiver logic coupled to the plurality of antennas;
• a processor coupled to the transmitter and receiver logic and operable to
• estimate large-scale radio-channel propagation strengths of a plurality of nearby UEs to a base station,
• estimate radio-propagation channel coefficients between each base-station antenna and each UE in a subset of UEs in the plurality of nearby UEs that have the large-scale radio-channel propagation strengths to the base station that are stronger than those UEs in the plurality of nearby UEs not part of the subset, the subset of UEs including in-cell UEs and one or more nearby out-of-cell UEs, and
• transmit data to the in-cell UEs via multi-user beamforming, including the data suppressing interference to the one or more nearby out-of-cell UEs that are part of the plurality of nearby UEs based on the radio-propagation channel coefficients estimates.

A wireless communication system comprising:

• a base station in a cell;
• and
• a plurality of UEs, a first group of the plurality of UEs being in cell with respect to the base station and a second group of the plurality of UEs being out-of-cell with respect to the base station,
• wherein the base station is operable to:
• detect pilots transmitted by nearby out-of-cell UEs, learn channels of the nearby out-of-cell UEs, and suppress interference to one or more of the nearby out-of-cell UEs, wherein the base station comprises:
• a plurality of antennas operable to receive transmissions of uplink pilot signals made in each slot, by a number of UEs, over the radio resource elements in slots that are allocated for uplink pilot transmission, wherein the number of UEs in the vicinity of at least one base station exceeds the number of radio resource elements that have been allocated for uplink pilot transmission in the slot;
• transmitter and receiver logic coupled to the plurality of antennas;
• and
• a processor coupled to the transmitter and receiver logic and operable to:
• estimate large-scale channel gains of a plurality of nearby UEs to the base station,
• estimate channels of a subset of UEs in the plurality of nearby UEs that have the large-scale channel gains that are stronger than those UEs in the plurality of nearby UEs not part of the subset, the subset of UEs including in-cell UEs and one or more nearby out-of-cell UEs and
• transmit data to the in-cell UEs via multi-user beamforming, including the data suppressing interference to the one or more nearby out-of-cell UEs that are part of the plurality of nearby UEs based on the channels estimates.