# US 2013/0155912 A1 · Multiple-Input Multiple-Output Wireless Communications with Full Duplex Radios > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0155912 A1 - Document ID: US20130155912A1 - Status: Published application - Kind: A1 - Application number: 13/588,466 - Filed: 2012-08-17 - Published: 2013-06-20 - Earliest claimed: 2011-09-05 - Assignees: NEC Laboratories America, Inc. - Inventors: Mohammad A. Khojastepour; Sanaz Barghi; Karthikeyan Sundaresan; Sampath Rangarajan - Web page: https://patentgrep.com/patent/US20130155912A1 ## CPC - H04W 72/21: in the uplink direction of a wireless link, i.e. towards the network - H04B 7/063: {Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection} - H04B 7/0691: {using subgroups of transmit antennas} - H04B 7/0874: {using subgroups of receive antennas} - H04L 5/0025: {Spatial division following the spatial signature of the channel} - H04L 5/0037: {Inter-user or inter-terminal allocation} - H04L 5/0062: {Avoidance of ingress interference, e.g. ham radio channels} - H04L 5/14: Two-way operation using the same type of signal, i.e. duplex - H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal - H04B 7/0802: {using antenna selection (H04B7/0868 takes precedence; antenna beam directivity switching H01Q3/24)} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract An apparatus used in a full duplex multiple-input multiple-output (MIMO) wireless communications system is disclosed. In an aspect, the apparatus includes a plurality of antennas, each of which is connected to a combination of at least a TX (transmit) RF (radio frequency) chain and an RX (receive) RF chain. The plurality of antennas are split into one or more transmit antennas and one or more receive antennas, and the apparatus communicates with another apparatus. Other apparatuses and some methods for wireless communications also are disclosed. ## Claims ### Claim 1 An apparatus used in a full duplex multiple-input multiple-output (MIMO) wireless communications system, the apparatus comprising: a plurality of antennas, each of which is connected to a combination of at least a TX (transmit) RF (radio frequency) chain and an RX (receive) RF chain, wherein the plurality of antennas are split into one or more transmit antennas and one or more receive antennas, and wherein the apparatus communicates with another apparatus. ### Claim 2 (depends on 1) The apparatus as in claim 1, wherein the antenna splitting is based on a channel condition. ### Claim 3 (depends on 1) The apparatus as in claim 1, wherein the antenna splitting is performed so that capacity gain is increased. ### Claim 4 (depends on 3) The apparatus as in claim 3, wherein the capacity gain is given by the following formula: ɛ  { G FD } ≈ { ( M - M 1 ) + ( N - N 1 ) 0.5  ( M + N ) = 2 - 2  N 1 + M 1 N + M ρ  << 1 min  ( N 1 , M - M 1 ) + min  ( N - N 1 , M 1 ) min  ( N , M ) ρ >> 1 where GFD is the capacity gain, ε{ } is an expectation operator or statistical average, ρ represents an average SNR (signal to noise ratio), M and N are the numbers of antennas at the apparatus and said another apparatus, respectively, and M1 and N1 are the numbers of transmit antennas at the apparatus and said another apparatus, respectively. ### Claim 5 (depends on 1) The apparatus as in claim 1, wherein, in case that an SNR (signal to noise ratio) is less than a predetermined value, N1 and M1 are set to one, where M1 and N1 are the numbers of transmit antennas at the apparatus and said another apparatus, respectively. ### Claim 6 (depends on 1) The apparatus as in claim 1, wherein, in case that an SNR (signal to noise ratio) is more than a predetermined value, M1 is set to M/2 (when M is even) or M/2±1/2 (when M is odd) and N1 is set to N/2 (when N is even) or N/2±1/2 (when N is odd), where M and N are the numbers of antennas at the apparatus and said another apparatus, respectively, and M1 and N1 are the numbers of transmit antennas at the apparatus and said another apparatus, respectively. ### Claim 7 (depends on 1) The apparatus as in claim 1, wherein, in case that an SNR (signal to noise ratio) is more than a predetermined value, M1 is set to a value so that the following in equation is satisfied: M>+N1>N, where M and N are the numbers of antennas at the apparatus and said another apparatus, respectively, and M1 and N1 are the numbers of transmit antennas at the apparatus and said another apparatus, respectively. ### Claim 8 A method implemented in a base station used in a full duplex multiple-input multiple-output (MIMO) wireless communications system, the method comprising: dividing a set of OFDM (Orthogonal Frequency Division Multiplexing) tones into a first group for uplink and a second group for downlink; scheduling a first user equipment in a first group and a second user equipment in the second group; receiving, from the second user equipment, information about interference on an OFDM tones in the first group; and scheduling one or more downlink users in the first group according to the information. ### Claim 9 (depends on 8) The method as in claim 8, wherein the information comprises a report on a free channel signal in case that the interference is below a threshold. ### Claim 10 (depends on 9) The method as in claim 9, wherein the threshold is fixed or set by the base station or the first user equipment. ### Claim 11 (depends on 8) The method as in claim 8, wherein the information feedback is initiated by the base station or by the first user equipment. ### Claim 12 A method implemented in a base station used in a full duplex multiple-input multiple-output (MIMO) wireless communications system, the method comprising: dividing a set of OFDM (Orthogonal Frequency Division Multiplexing) tones into a first group for uplink and a second group for downlink; scheduling a first user equipment in a first group and a second user equipment in the second group; measuring downlink enhancement; and allocating one or more OFDM tones in the second group to uplink according to the downlink enhancement. ### Claim 13 (depends on 12) The method as in claim 12, wherein the downlink enhancement is measured in terms of at least one of throughput, quality of service, and a system utility measure. ### Claim 14 (depends on 12) The method as in claim 12, wherein the downlink enhancement is measured over one or more superframes, each of which comprises a group of frames. ### Claim 15 A method implemented in a base station used in a full duplex multiple-input multiple-output (MIMO) wireless communications system, the method comprising: scheduling one or more user equipment in an OFDM (Orthogonal Frequency Division Multiplexing) tone used for full duplex communications, according to a prior schedule and an achieved rate. ### Claim 16 (depends on 15) The method as in claim 15, wherein the achieved rate comprises a weighted sum rate. ### Claim 17 (depends on 16) The method as in claim 16, wherein a weight for the weighted sum rate changes in time according to at least one of operation of the full duplex MIMO wireless communications system and a channel condition. ### Claim 18 (depends on 16) The method as in claim 16, wherein the weighted sum rate can be expressed as the following expression: max  ∑ i = 1 n   1 Ra i  ( t )  R i  ( t ) ,  where Ra i  ( t + 1 ) = ( 1 - 1 T c )  Ra i  ( t ) + 1 T c  R i  ( t ) , Rai is an average rate for link i, Tc is an averaging window size, and Ri(t) is a rate associated with link i in time-slot t.