# US 2008/0187066 A1 · Detection method and apparatus for a multi-stream MIMO > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0187066 A1 - Document ID: US20080187066A1 - Status: Published application - Kind: A1 - Application number: 11/826,360 - Filed: 2007-07-13 - Published: 2008-08-07 - Earliest claimed: 2007-02-06 - Assignees: Nokia Corporation - Inventors: Haifeng Wang; Jorma Lilleberg; Wei Li; Ming Chen; Shixin Cheng - Web page: https://patentgrep.com/patent/US20080187066A1 ## CPC - H04L 1/0656: {Cyclotomic systems, e.g. Bell Labs Layered Space-Time [BLAST]} - H04L 1/0003: {by switching between different modulation schemes} - H04L 25/03216: {using the M-algorithm} - H04L 1/0009: {by adapting the channel coding (H04L1/1812 takes precedence)} - H04L 1/0026: {Transmission of channel quality indication} - H04L 5/0046: {Determination of the number of bits transmitted on different sub-channels} - H04L 25/0246: {with factorisation} - H04L 2025/03414: {Multicarrier} - H04L 2025/03426: {transmission using multiple-input and multiple-output channels} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract In a multiple-input multiple output (MIMO) system, high-rate data transmission is achieved by dividing the original data stream into several parallel data substreams, each of which is transmitted from a corresponding transmit antenna (spatial multiplexing) and received by multiple receive antennas. The number of spatial streams depends on the number of antennas. In a receiver, a search-tree based QR Decomposition-M (QRD-M) algorithm is used. According to the invention, multiple spatial signal streams received from a MIMO channel are pre-ordered based on modulation alphabets of said received spatial signal streams prior to performing a QRD-M detection. ## Claims ### Claim 1 A method, comprising: receiving multiple spatial signal streams from a multiple-input multiple output (MIMO) channel; and pre-ordering said multiple received spatial signal streams based on modulation alphabets of said received spatial signal streams prior to performing a QR Decomposition-M detection. ### Claim 2 (depends on 1) The method as claimed in claim 1, wherein said pre-ordering comprises: forming a signal vector from said received spatial signal streams; estimating a transmission channel matrix for said MIMO channel; and pre-ordering elements of said signal vector and elements of said transmission channel matrix based on said modulation alphabets of said received spatial signal streams prior to performing said QR Decomposition-M detection., ### Claim 3 (depends on 1) The method as claimed in claim 1, wherein said pre-ordering comprises: forming a signal vector from said received spatial signal streams; estimating a transmission channel matrix for said MIMO channel; and pre-ordering elements of said signal vector and elements of said transmission channel matrix into groups based on said modulation alphabets of said received spatial signal streams such that each of said group corresponds to different value of said modulation alphabets. ### Claim 4 (depends on 3) The method as claimed in claim 3, comprising: performing a further preordering within each group of said elements of said signal vector and said elements of said transmission channel matrix prior to performing said QR Decomposition-M detection. ### Claim 5 (depends on 4) The method as claimed in claim 4, wherein said further preordering comprises one of a H-norm ordering and a H-inverse ordering. ### Claim 6 (depends on 1) The method as claimed in claim 1, wherein said receiving comprises receiving 16QAM-modulated spatial signal streams having a modulation alphabet with value 16, and QPSK-modulated spatial signal streams having a modulation alphabet with value 4. ### Claim 7 (depends on 1) The method as claimed claim 1, wherein said receiving comprises receiving multiple spatial signal streams from an orthogonal frequency division multiplexing MIMO channel. ### Claim 8 (depends on 1) The method as claimed in claim 1, wherein said receiving comprises receiving multiple spatial signal streams from one of a transmit antenna array MIMO channel and a double transmit antenna array MIMO channel. ### Claim 9 (depends on 1) The method as claimed in claim 1, wherein said receiving comprises receiving multiple spatial signal streams with independently variable modulation schemes. ### Claim 10 (depends on 1) The method as claimed in claim 1, wherein said receiving comprises receiving multiple spatial signal streams which are rate controlled by a per-antenna rate control. ### Claim 11 A computer program embodied on a computer readable medium, the computer program comprising program code for controlling a processor to execute a method comprising: receiving multiple spatial signal streams from a multiple-input multiple output channel; and pre-ordering said multiple received spatial signal streams based on modulation alphabets of said received spatial signal streams prior to performing a QR Decomposition-M detection. ### Claim 12 A computer program embodied on a computer readable medium, the computer program comprising: a component configured to receive multiple spatial signal streams from a multiple-input multiple output channel; and a component configured pre-order said multiple received spatial signal streams based on modulation alphabets of said received spatial signal streams prior to performing a QR Decomposition-M detection. ### Claim 13 An apparatus, comprising: a receiver unit configured to receive multiple spatial signal streams from a multiple-input multiple output (MIMO) channel; and a signal processing unit configured to pre-order said multiple received spatial signal streams based on modulation alphabets of said received spatial signal streams prior to performing a QR Decomposition-M detection. ### Claim 14 (depends on 13) The apparatus as claimed in claim 13, wherein said signal processing unit is configured to pre-order elements of a signal vector formed from said received spatial signal streams, and elements of an estimated transmission channel matrix of said MIMO channel, based on said modulation alphabets of said received spatial signal streams prior to performing said QR Decomposition-M detection. ### Claim 15 (depends on 13) An apparatus as claimed in claim 13, wherein said signal processing unit is configured to pre-order elements of a signal vector formed from said received spatial signal streams, and elements of an estimated transmission channel matrix of said MIMO channel, into groups based on said modulation alphabets of said received spatial signal streams such that each of said group corresponds to different value of said modulation alphabets. ### Claim 16 (depends on 15) The apparatus as claimed in claim 15, wherein said signal processing unit is configured to perform a further preordering within each group of said elements of said signal vector and said elements of said transmission channel matrix prior to performing said QR Decomposition-M detection. ### Claim 17 (depends on 16) The apparatus as claimed in claim 16, wherein, wherein said signal processing unit is configured to perform said further pre-ordering using one of a H-norm ordering and a H-inverse ordering. ### Claim 18 (depends on 13) The apparatus as claimed in claim 13, wherein said receiver unit is a receiver unit configured to receive 16QAM-modulated spatial signal streams having a modulation alphabet with value 16, and QPSK-modulated spatial signal streams having a modulation alphabet with value 4. ### Claim 19 (depends on 13) The apparatus as claimed in claim 13, wherein said receiver unit is configured to receive multiple spatial signal streams from an orthogonal frequency division multiplexing (OFDM) MIMO channel. ### Claim 20 (depends on 13) The apparatus as claimed in claim 13, wherein said receiver unit is a receiver unit configured to receive multiple spatial signal streams from one of a transmit antenna array) MIMO channel and a double transmit antenna array MIMO channel. ### Claim 21 (depends on 13) The apparatus as claimed in claim 13, wherein said receiver unit is a receiver unit configured to receive multiple spatial signal streams with independently variable modulation schemes. ### Claim 22 (depends on 13) The apparatus as claimed in claim 13, wherein said receiver unit is a receiver unit configured to receive multiple spatial signal streams which are rate controlled by a per-antenna rate control. ### Claim 23 (depends on 13) The apparatus as claimed in claim 13, wherein at said receiver unit and said signal processing unit are implemented in hardware, firmware, software, or combinations thereof. ### Claim 24 (depends on 13) The apparatus as claimed in claim 13, wherein said apparatus is implemented in a wireless base station. ### Claim 25 A wireless mobile terminal comprising: an apparatus comprising a receiver unit configured to receive multiple spatial signal streams from a multiple-input multiple output (MIMO) channel and a signal processing unit configured to pre-order said multiple received spatial signal streams based on modulation alphabets of said received spatial signal streams prior to performing a QR Decomposition-M detection. ### Claim 26 A wireless base transceiver comprising: an apparatus comprising a receiver unit configured to receive multiple spatial signal streams from a multiple-input multiple output (MIMO) channel and a signal processing unit configured to pre-order said multiple received spatial signal streams based on modulation alphabets of said received spatial signal streams prior to performing a QR Decomposition-M detection.