# US 10,374,856 B2 · Pilot design for OFDM systems with four transmit antennas > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,374,856 B2 - Document ID: US10374856B2 - Status: Granted - Kind: B2 - Application number: 15/674,785 - Filed: 2017-08-11 - Published: 2018-02-08 - Granted: 2019-08-06 - Earliest claimed: 2004-03-15 - Assignees: Apple Inc. - Applicants: Apple Inc. - Inventors: Jianglei Ma; Ming Jia; Wen Tong; Peiying Zhu; Claude Royer - Web page: https://patentgrep.com/patent/US10374856B2 ## CPC - H04L 27/261: {Details of reference signals} - H04B 7/06: at the transmitting station - H04B 7/0615: {of weighted versions of same signal} - H04B 7/0684: {using different training sequences per antenna} - H04L 5/0026: {Division using four or more dimensions, e.g. beam steering or quasi-co-location [QCL]} - H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)} - H04L 25/0204: {of multiple channels} - H04L 25/0226: {sounding signals per se} - H04L 25/0234: {by non-linear interpolation} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04B: TRANSMISSION ## Abstract Pilot, preamble and midamble patterns are provided that are particularly suited for four transmit antenna OFDM systems. Pilots are inserted in a scattered manner for each of the four antennas, either uncoded, space-time coded in pairs, space-time frequency coded in pairs, or space-time-frequency coded. ## Claims ### Claim 1 A method of transmitting including using four transmit antennas, comprising: for each antenna of the four transmit antennas; generating a respective sequence of OFDM (Orthogonal Frequency Division Multiplexing) symbols, each OFDM symbol having a plurality of sub-carriers carrying data symbols or pilot symbols, wherein: the pilot symbols are arranged in groups, each group of pilot symbols including a pilot symbol pair for each of the four transmit antennas, and a first group of pilot symbols are inserted into the OFDM symbols such that the pilot symbols for a first two of the antennas are arranged in a first pilot symbol pair, wherein the first pilot symbol pair is positioned on sub-carrier locations adjacent in frequency, the pilot symbols for a second two of the antennas are arranged in a second pilot symbol pair, wherein the second pilot symbol pair is positioned on sub-carrier locations adjacent in frequency, and the pilot symbol pair for the first two of the antennas are adjacent in time to the pilot symbol pairs of the second two of the antennas; and transmitting the sequence of OFDM symbols. ### Claim 2 (depends on 1) The method of claim 1, wherein the pilot symbols for the first two of the antennas are separated in time by at least one data symbol from the pilot symbols for the second two of the antennas. ### Claim 3 (depends on 1) The method of claim 1, wherein the pilot symbols for the first two of the antennas are separated in frequency by at least one data symbol from the pilot symbols of the second two of the antennas. ### Claim 4 (depends on 3) The method of claim 3, wherein the pilot symbols for the first two of the antennas occupy the same frequency as the pilot symbols for the second two of the antennas. ### Claim 5 (depends on 1) The method of claim 1, wherein the pilot symbols for the first two of the antennas are separated in frequency by a first predetermined number of data symbols from the pilot symbols of the second two of the antennas and the pilot symbols of the second two of the antennas are separated in frequency by a second predetermined number of data symbols from a next group of pilot symbols for the first two of the antennas. ### Claim 6 (depends on 1) The method of claim 1, wherein the pilot symbols for the first two of the antennas are adjacent in time from a next group of pilot symbols for the second two of the antennas. ### Claim 7 (depends on 1) The method of claim 1, wherein the pilot symbols for the second two of the antennas are adjacent in time from a next group of pilot symbols for the first two of the antennas. ### Claim 8 A mobile station, comprising: four transmit antennas; and a transmitter that, for each of the four transmit antennas; generates a respective sequence of OFDM (Orthogonal Frequency Division Multiplexing) symbols, each OFDM symbol having a plurality of sub-carriers carrying data symbols or pilot symbols, wherein: the pilot symbols are arranged in groups, each group of pilot symbols including a pilot symbol pair for each of the four transmit antennas, and a first group of pilot symbols are inserted into the OFDM symbols such that the pilot symbols for a first two of the antennas are arranged in a first pilot symbol pair, wherein the first pilot symbol pair is positioned on sub-carrier locations adjacent in frequency, the pilot symbols for a second two of the antennas are arranged in a second pilot symbol pair, wherein the second pilot symbol pair is positioned on sub-carrier locations adjacent in frequency, and the pilot symbol pair for the first two of the antennas are adjacent in time to the pilot symbol pairs of the second two of the antennas; and transmits the sequence of OFDM symbols. ### Claim 9 (depends on 8) The mobile station of claim 8, wherein the pilot symbols for the first two of the antennas are separated in time by at least one data symbol from the pilot symbols for the second two of the antennas. ### Claim 10 (depends on 8) The mobile station of claim 8, wherein the pilot symbols for the first two of the antennas are separated in frequency by at least one data symbol from the pilot symbols of the second two of the antennas. ### Claim 11 (depends on 10) The mobile station of claim 10, wherein the pilot symbols for the first two of the antennas occupy the same frequency as the pilot symbols for the second two of the antennas. ### Claim 12 (depends on 8) The mobile station of claim 8, wherein the pilot symbols for the first two of the antennas are separated in frequency by a first predetermined number of data symbols from the pilot symbols of the second two of the antennas and the pilot symbols of the second two of the antennas are separated in frequency by a second predetermined number of data symbols from a next group of pilot symbols for the first two of the antennas. ### Claim 13 (depends on 8) The mobile station of claim 8, wherein the pilot symbols for the first two of the antennas are adjacent in time from a next group of pilot symbols for the second two of the antennas. ### Claim 14 (depends on 8) The mobile station of claim 8, wherein the pilot symbols for the second two of the antennas are adjacent in time from a next group of pilot symbols for the first two of the antennas. ### Claim 15 An integrated circuit, comprising; for each antenna of four transmit antennas; circuitry to generate a respective sequence of OFDM (Orthogonal Frequency Division Multiplexing) symbols, each OFDM symbol having a plurality of sub-carriers carrying data symbols or pilot symbols, wherein: the pilot symbols are arranged in groups, each group of pilot symbols including a pilot symbol pair for each of the four transmit antennas, and a first group of pilot symbols are inserted into the OFDM symbols such that the pilot symbols for a first two of the antennas are arranged in a first pilot symbol pair, wherein the first pilot symbol pair is positioned on sub-carrier locations adjacent in frequency, the pilot symbols for a second two of the antennas are arranged in a second pilot symbol pair, wherein the second pilot symbol pair is positioned on sub-carrier locations adjacent in frequency, and the pilot symbol pair for the first two of the antennas are adjacent in time to the pilot symbol pairs of the second two of the antennas; and circuitry to transmit the sequence of OFDM symbols. ### Claim 16 (depends on 15) The integrated circuit of claim 15, wherein the pilot symbols for the first two of the antennas are separated in time by at least one data symbol from the pilot symbols for the second two of the antennas. ### Claim 17 (depends on 15) The integrated circuit of claim 15, wherein the pilot symbols for the first two of the antennas are separated in frequency by at least one data symbol from the pilot symbols of the second two of the antennas. ### Claim 18 (depends on 17) The integrated circuit of claim 17, wherein the pilot symbols for the first two of the antennas occupy the same frequency as the pilot symbols for the second two of the antennas. ### Claim 19 (depends on 15) The integrated circuit of claim 15, wherein the pilot symbols for the first two of the antennas are separated in frequency by a first predetermined number of data symbols from the pilot symbols of the second two of the antennas and the pilot symbols of the second two of the antennas are separated in frequency by a second predetermined number of data symbols from a next group of pilot symbols for the first two of the antennas. ### Claim 20 (depends on 15) The integrated circuit of claim 15, wherein; the pilot symbols for the first two of the antennas are adjacent in time from a next group of pilot symbols for the second two of the antennas; and the pilot symbols for the second two of the antennas are adjacent in time from a next group of pilot symbols for the first two of the antennas.