# US 8,787,259 B2 · Method for efficient MU-MIMO transmission by joint assignments of transmission architecture, and interference alignment schemes using optimized user-code assignments and power-allocation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,259 B2 - Document ID: US8787259B2 - Status: Granted - Kind: B2 - Application number: 13/239,167 - Filed: 2011-09-21 - Published: 2012-03-22 - Granted: 2014-07-22 - Earliest claimed: 2010-09-22 - Assignees: Ntt Docomo, Inc. - Applicants: Haralabos Papadopoulos; Sean A. Ramprashad; Chenwei Wang - Inventors: Haralabos Papadopoulos; Sean A. Ramprashad; Chenwei Wang - Web page: https://patentgrep.com/patent/US8787259B2 ## CPC - H04B 7/0822: {according to predefined selection scheme} - H04B 7/024: Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems - H04B 7/0413: MIMO systems - H04B: TRANSMISSION ## Abstract A method, apparatus, and wireless communication system is disclosed herein for operating a BIA code structure in a system. In one embodiment, the wireless communication system comprises a plurality of receivers, wherein each receiver in the plurality having a multi-mode antenna with a single radio frequency (RF) chain that is operable in a plurality of antenna modes, and further wherein each receiver shifts between the plurality of antenna modes in a predetermined manner. The wireless communication system also includes a plurality of base stations in a cell topology to perform downlink transmissions to the plurality of receivers, each base station in the plurality of base stations having one or more transmitters having a transmit antenna and being operable to communicate with one or more of receivers in the plurality of receivers using a multi-user MIMO (MU-MIMO)-based blind interference alignment (BIA) scheme, wherein each active base station in the plurality of base stations operates an identical BIA code structure in a given transmission resource. ## Claims ### Claim 1 A wireless communication system comprising: a plurality of receivers, wherein each receiver in the plurality having a multi-mode antenna with a single radio frequency (RF) chain that is operable in a plurality of antenna modes, and further wherein each receiver shifts between the plurality of antenna modes in a predetermined manner; and a plurality of base stations in a cell topology to perform downlink transmissions to the plurality of receivers, each base station in the plurality of base stations having one or more transmitters having a transmit antenna and being operable to communicate with one or more of receivers in the plurality of receivers using a multi-user MIMO (MU-MIMO)-based blind interference alignment (BIA) scheme, wherein each active base station in the plurality of base stations operates an identical BIA code structure in a given transmission resource. ### Claim 2 (depends on 1) The wireless communication system defined in claim 1 wherein the given transmission resource comprises a frequency band. ### Claim 3 (depends on 1) The wireless communication system defined in claim 1 wherein the given transmission resource comprises a time slot. ### Claim 4 (depends on 1) The wireless communication system defined in claim 1 wherein base stations in the topology operate according to a power mask that specifies transmission power to be used by each of the base stations on each codeword on a transmission resource associated with a BIA code. ### Claim 5 (depends on 4) The wireless communication system defined in claim 4 wherein transmission power specified by the power mask varies as a function of a base station index for each code index value and each transmission. ### Claim 6 (depends on 1) The wireless communication system defined in claim 1 wherein each base station schedules users on a code index and location based on geographic user location. ### Claim 7 (depends on 1) The wireless communication system defined in claim 1 wherein each base station schedules users on a code index and location based on user large-scale signal to interference ratio values. ### Claim 8 (depends on 1) The wireless communication system defined in claim 1 wherein the plurality of base stations comprise a first group of base stations and a second group of base stations, and further wherein a first group of codewords are active for use by the first group of base stations and a second group of codewords are active for use by the second group of base stations. ### Claim 9 (depends on 1) The wireless communication system defined in claim 1 wherein the plurality of base stations employs code reuse that varies from one codeword to a next codeword. ### Claim 10 (depends on 1) The wireless communication system defined in claim 1 wherein the plurality of base stations comprise a first group of base stations and a second group of base stations, and further wherein on a first set of bands the first group of base stations serve a first set of user terminals in a first relative location with respect to its serving base station, the second group of base stations serve a second set of user terminals in a second relative location with respect to its serving base station and on a second set of bands the first group of base stations serve the first set of user terminals in second relative location with respect to its serving base station, the second group of base stations serve the second set of user terminals in the second relative location with respect to its serving base station. ### Claim 11 (depends on 1) The wireless communication system defined in claim 1 wherein base stations serve only a set of users having a same relative cell location across the topology using codes that vary as frequency bands vary. ### Claim 12 (depends on 9) The wireless communication system defined in claim 9 wherein only one antenna is active at each receiver in the plurality of receivers during a given time slot. ### Claim 13 A method for communicating in a wireless communication system having a plurality of receivers and a plurality of base stations, wherein each receiver in the plurality having a multi-mode antenna with a single radio frequency (RF) chain that is operable in a plurality of antenna modes, and further wherein each base station in the plurality of base stations has one or more transmitters having a transmit antenna and being operable to communicate with one or more of receivers in the plurality of receivers using a blind interference alignment (BIA) scheme, the method comprising: performing downlink transmission with the plurality of base stations to transmit wireless signals to the plurality of receivers using a blind interference alignment (BIA) scheme while the plurality of receivers shift between the plurality of antenna modes in a predetermined manner, including operating each active base station in the plurality of base stations with an identical BIA code structure in a given transmission resource. ### Claim 14 (depends on 13) The method defined in claim 13 wherein the given transmission resource comprises a frequency band. ### Claim 15 (depends on 13) The method defined in claim 13 wherein the given transmission resource comprises a time slot. ### Claim 16 (depends on 13) The method defined in claim 13 further comprising employing, by the plurality of base stations, code reuse that varies from one codeword to a next codeword. ### Claim 17 (depends on 13) The method defined in claim 13 further comprising using codes that vary as frequency bands vary when serving only a set of users having a same relative cell location across the topology. ### Claim 18 (depends on 13) The method defined in claim 13 further comprising operating base stations in the topology according to a power mask that specifies transmission power to be used by each of the base stations on each codeword on a transmission resource associated with a BIA code. ### Claim 19 (depends on 18) The method defined in claim 18 wherein transmission power specified by the power mask varies as a function of a base station index for each code index value and each transmission. ### Claim 20 (depends on 13) The method defined in claim 13 further comprising scheduling, by each base station, users on a code index and location based on geographic user location. ### Claim 21 (depends on 13) The method defined in claim 13 further comprising scheduling, by each base station, users on a code index and location based on user large scale signal to interference ratio values. ### Claim 22 A wireless communication system comprising: a plurality of receivers, wherein each receiver in the plurality having a multi-mode antenna with a single radio frequency (RF) chain that is operable in a plurality of antenna modes, and further wherein each receiver shifts between the plurality of antenna modes in a predetermined manner; and a plurality of base stations in a cell topology to perform downlink transmissions to the plurality of receivers, each base station in the plurality of base stations having one or more transmitters having a transmit antenna and being operable to communicate with one or more of receivers in the plurality of receivers using a multi-user MIMO (MU-MIMO)-based blind interference alignment (BIA) scheme, wherein each active cluster of base stations in a plurality of clusters of base stations operates an identical BIA code structure in a given transmission resource. ### Claim 23 (depends on 22) The wireless communication system defined in claim 22 wherein the plurality of clusters of base stations employs code reuse that varies from one codeword to a next codeword. ### Claim 24 (depends on 22) The wireless communication system defined in claim 22 wherein clusters of base stations serve only a set of users having a same relative cell location across the topology using codes that varies as frequency bands vary.