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Steering diversity for an ofdm-based multi-antenna communication system

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US20080273617A1
US20080273617A1 US12176306 US17630608A US2008273617A1 US 20080273617 A1 US20080273617 A1 US 20080273617A1 US 12176306 US12176306 US 12176306 US 17630608 A US17630608 A US 17630608A US 2008273617 A1 US2008273617 A1 US 2008273617A1
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antenna
transmit
subbands
symbol
ofdm
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US12176306
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Stein A. Lundby
Steven J. Howard
Jay Rodney Walton
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Qualcomm Inc
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Qualcomm Inc
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/26Systems using multi-frequency codes
    • H04L27/2601Multicarrier modulation systems
    • H04L27/2602Signal structure

Abstract

A transmitting entity uses different steering vectors for different subbands to achieve steering diversity. Each steering vector defines or forms a beam for an associated subband. Any steering vector may be used for steering diversity. The steering vectors may be defined such that the beams vary in a continuous instead of abrupt manner across the subbands. This may be achieved by applying continuously changing phase shifts across the subbands for each transmit antenna. As an example, the phase shifts may change in a linear manner across the subbands for each transmit antenna, and each antenna may be associated with a different phase slope. The application of linearly changing phase shifts to modulation symbols in the frequency domain may be achieved by either delaying or circularly shifting the corresponding time-domain samples.

Description

    CLAIM OF PRIORITY
  • [0001]
    This application is a continuation of, and claims the benefit of priority from, U.S. patent application Ser. No. 11/066,771, filed Feb. 24, 2005 and entitled “Steering Diversity for an OFDM-Based Multi-Antenna Communication System,” which claims the benefit of priority from U.S. Provisional Patent Application Ser. No. 60/569,103, filed May 7, 2004 and entitled “Steering Diversity for an OFDM-Based Multi-Antenna Communication System,” both of which are assigned to the assignee hereof and are fully incorporated herein by reference for all purposes.
  • FIELD
  • [0002]
    The present invention relates generally to communication, and more specifically to data transmission in a multi-antenna communication system that utilizes orthogonal frequency division multiplexing (OFDM).
  • BACKGROUND
  • [0003]
    OFDM is a multi-carrier modulation technique that effectively partitions the overall system bandwidth into multiple (K) orthogonal subbands, which are also referred to as tones, subcarriers, bins, and frequency channels. With OFDM, each subband is associated with a respective subcarrier that may be modulated with data. OFDM is widely used in various wireless communication systems, such as those that implement the well-known IEEE 802.11a and 802.11g standards. IEEE 802.11a and 802.11g generally cover single-input single-output (SISO) operation whereby a transmitting device employs a single antenna for data transmission and a receiving device normally employs a single antenna for data reception.
  • [0004]
    A multi-antenna communication system may support communication for both single-antenna devices and multi-antenna devices. In this system, a multi-antenna device may utilize its multiple antennas for data transmission to a single-antenna device. The multi-antenna device and the single-antenna device may implement any one of a number of conventional transmit diversity schemes in order to obtain transmit diversity and improve performance for the data transmission. One such transmit diversity scheme is described by S. M. Alamouti in a paper entitled “A Simple Transmit Diversity Technique for Wireless Communications,” IEEE Journal on Selected Areas in Communications, Vol. 16, No. 8, October 1998, pp. 1451-1458. For the Alamouti scheme, the transmitting device transmits each pair of modulation symbols from two antennas in two symbol periods, and the receiving device combines two received symbols obtained in the two symbol periods to recover the pair of modulation symbols sent by the transmitting device. The Alamouti scheme as well as most other conventional transmit diversity schemes require the receiving device to perform special processing, which may be different from scheme to scheme, in order to recover the transmitted data and obtain the benefits of transmit diversity.
  • [0005]
    A “legacy” single-antenna device may be designed for SISO operation only, as described below. This is normally the case if the wireless device is designed for the IEEE 802.11a or 802.11g standard. Such a legacy single-antenna device would not be able to perform the special processing required by most conventional transmit diversity schemes. Nevertheless, it is still highly desirable for a multi-antenna device to transmit data to the legacy single-antenna device in a manner such that greater reliability and/or improved performance can be achieved.
  • [0006]
    There is therefore a need in the art for techniques to achieve transmit diversity in an OFDM-based system, especially for legacy single-antenna devices.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • [0007]
    FIG. 1 shows a multi-antenna system with an access point and user terminals.
  • [0008]
    FIG. 2 shows a block diagram of a multi-antenna transmitting entity, a single-antenna receiving entity, and a multi-antenna receiving entity.
  • [0009]
    FIG. 3 shows an OFDM waveform in the frequency domain.
  • [0010]
    FIG. 4 shows a block diagram of an OFDM modulator.
  • [0011]
    FIG. 5 shows a model for transmission with steering diversity for one subband.
  • [0012]
    FIG. 6 shows a transmit (TX) spatial processor and an OFDM modulator.
  • [0013]
    FIG. 7 shows plots of linear phase shifts across subbands for four antennas.
  • [0014]
    FIGS. 8A and 8B show two embodiments for achieving linear phase shifts using different delays for time-domain samples.
  • [0015]
    FIG. 8C shows transmissions from T transmit antennas for the embodiments shown in FIGS. 8A and 8B.
  • [0016]
    FIG. 9A shows an embodiment for achieving linear phase shifts using circular shifts for time-domain samples.
  • [0017]
    FIG. 9B shows transmissions from T transmit antennas for the embodiment shown in FIG. 9A.
  • DETAILED DESCRIPTION
  • [0018]
    The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.
  • [0019]
    FIG. 1 shows a multi-antenna system 100 with an access point (AP) 110 and user terminals (UTs) 120. An access point is generally a fixed station that communicates with the user terminals and may also be referred to as a base station or some other terminology. A user terminal may be fixed or mobile and may also be referred to as a mobile station, a wireless device, a user equipment (UE), or some other terminology. For a centralized architecture, a system controller 130 couples to the access points and provides coordination and control for these access points.
  • [0020]
    Access point 110 is equipped with multiple antennas for data transmission and reception. Each user terminal 120 may be equipped with a single antenna or multiple antennas for data transmission and reception. A user terminal may communicate with the access point, in which case the roles of access point and user terminal are established. A user terminal may also communicate peer-to-peer with another user terminal. In the following description, a transmitting entity is equipped with multiple (T) transmit antennas, and a receiving entity may be equipped with a single antenna or multiple (R) antennas. A multiple-input single-output (MISO) transmission exists when the receiving entity is equipped with a single antenna, and a multiple-input multiple-output (MIMO) transmission exists when the receiving entity is equipped with multiple antennas.
  • [0021]
    FIG. 2 shows a block diagram of a multi-antenna transmitting entity 210, a single-antenna receiving entity 250 x, and a multi-antenna receiving entity 250 y in system 100. Transmitting entity 210 may be an access point or a multi-antenna user terminal. Each receiving entity 250 may also be an access point or a user terminal.
  • [0022]
    At transmitting entity 210, a transmit (TX) data processor 212 processes (e.g., encodes, interleaves, and symbol maps) traffic/packet data and generates data symbols. As used herein, a “data symbol” is a modulation symbol for data, a “pilot symbol” is a modulation symbol for pilot (which is data that is known a priori by both the transmitting and receiving entities), a “transmit symbol” is a symbol to be sent from a transmit antenna, and a “received symbol” is a symbol obtained from a receive antenna. A TX spatial processor 220 receives and demultiplexes pilot and data symbols onto the proper subbands, performs spatial processing as appropriate, and provides T streams of transmit symbols for the T transmit antennas. An OFDM modulator (Mod) 230 performs OFDM modulation on the T transmit symbol streams and provides T streams of samples to T transmitter units (TMTR) 232 a through 232 t. Each transmitter unit 232 processes (e.g., converts to analog, amplifies, filters, and frequency upconverts) its transmit symbol stream and generates a modulated signal. Transmitter units 232 a through 232 t provide T modulated signals for transmission from T antennas 234 a through 234 t, respectively.
  • [0023]
    At single-antenna receiving entity 250 x, an antenna 252 x receives the T transmitted signals and provides a received signal to a receiver unit (RCVR) 254 x. Receiver unit 254 x performs processing that is complementary to the processing performed by transmitter units 232 and provides a stream of samples. An OFDM demodulator (Demod) 260 x performs OFDM demodulation on the sample stream to obtain received data and pilot symbols, provides the received data symbols to a detector 270 x, and provides the received pilot symbols to a channel estimator 284 x within a controller 280 x. Channel estimator 284 x derives channel estimates for the effective SISO channels between transmitting entity 210 and receiving entity 250 x for subbands used for data transmission. Detector 270 x performs detection on the received data symbols for each subband based on the effective SISO channel estimate for that subband and provides a stream of detected symbols for all subbands. A receive (RX) data processor 272 x then processes (e.g., symbol demaps, deinterleaves, and decodes) the detected symbol stream and provides decoded data.
  • [0024]
    At multi-antenna receiving entity 250 y, R antennas 252 a through 252 r receive the T transmitted signals, and each antenna 252 provides a received signal to a respective receiver unit 254. Each receiver unit 254 processes a respective received signal and provides a sample stream to an associated OFDM demodulator 260. Each OFDM demodulator 260 performs OFDM demodulation on its sample stream to obtain received data and pilot symbols, provides the received data symbols to an RX spatial processor 270 y, and provides the received pilot symbols to a channel estimator 284 y within a controller 280 y. Channel estimator 284 y derives channel estimates for the actual or effective MIMO channels between transmitting entity 210 and receiving entity 250 y for subbands used for data transmission. Controller 280 y derives spatial filter matrices based on the MIMO channel estimates. RX spatial processor 270 y performs receiver spatial processing (or spatial matched filtering) on the received data symbols for each subband with the spatial filter matrix derived for that subband and provides detected symbols for the subband. An RX data processor 272 y then processes the detected symbols for all subbands and provides decoded data.
  • [0025]
    Controllers 240, 280 x, and 280 y control the operation of the processing units at transmitting entity 210 and receiving entities 250 x and 250 y, respectively. Memory units 242, 282 x, and 282 y store data and/or program code used by controllers 240, 280 x, and 280 y, respectively.
  • [0026]
    FIG. 3 shows an OFDM waveform in the frequency domain. OFDM provides K total subbands, and the subcarrier for each subband may be individually modulated with data. Of the K total subbands, ND subbands may be used for data transmission, NP subbands may be used for pilot transmission, and the remaining NG subbands may be unused and serve as guard subbands, where K=ND+NP+NG. For example, 802.11a utilizes an OFDM structure that has 64 total subbands, of which 48 subbands are used for data transmission, 4 subbands are used for pilot transmission, and 12 subbands are unused. In general, system 100 may utilize any OFDM structure with any number of data, pilot, guard, and total subbands. For simplicity, the following description assumes that all K subbands are usable for data and pilot transmission.
  • [0027]
    FIG. 4 shows a block diagram of OFDM modulator 230 at transmitting entity 210. The data to be transmitted (or information bits) is typically first encoded to generate code bits, which are then interleaved. The interleaved bits are then grouped into B-bit binary values, where B≧1. Each B-bit value is then mapped to a specific modulation symbol based on a modulation scheme selected for use (e.g., M-PSK or M-QAM, where M=2B). Each modulation symbol is a complex value in a signal constellation for the selected modulation scheme. In each OFDM symbol period, one modulation symbol may be transmitted on each subband. (A signal value of zero, which is also called a zero symbol, is usually provided for each unused subband.) An inverse discrete Fourier transform (IDFT) unit 432 receives K modulation symbols for the K subbands in each OFDM symbol period, transforms the K modulation symbols to the time domain with a K-point IDFT, and provides a “transformed” symbol that contains K time-domain samples. Each sample is a complex-value to be transmitted in one sample period. A parallel-to-serial (P/S) converter 434 serializes the K samples for each transformed symbol. A cyclic prefix generator 436 then repeats a portion (or C samples) of each transformed symbol to form an OFDM symbol that contains K+C samples. The cyclic prefix is used to combat inter-symbol interference (ISI) caused by frequency selective fading, which is a frequency response that varies across the overall system bandwidth. An OFDM symbol period (which is also referred to herein as simply a “symbol period”) is the duration of one OFDM symbol and is equal to K+C sample periods.
  • [0028]
    In system 100, a MISO channel exists between a multi-antenna transmitting entity and a single-antenna receiving entity. For an OFDM-based system, the MISO channel formed by the T antennas at the transmitting entity and the single antenna at the receiving entity may be characterized by a set of K channel response row vectors, each of dimension 1×T, which may be expressed as:
  • [0000]

    h (k)=[h 0(k)h 1(k) . . . h T−1(k)], for k=0, . . . , K−1,  Eq (1)
  • [0000]
    where k is an index for subband and hi(k), for i=0, . . . , T−1, denotes the coupling or complex gain between transmit antenna i and the single receive antenna for subband k. For simplicity, the MISO channel response h(k) is shown as a function of only subband k and not time.
  • [0029]
    If the transmitting entity has an accurate estimate of the MISO channel response, then it may perform spatial processing to direct a data transmission toward the receiving entity. However, if the transmitting entity does not have an accurate estimate of the wireless channel, then the T transmissions from the T antennas cannot be intelligently adjusted based on the wireless channel.
  • [0030]
    When an accurate channel estimate is not available, the transmitting entity may transmit data from its T antennas to the single-antenna receiving entity using steering diversity to achieve transmit diversity, greater reliability, and/or improved performance. With steering diversity, the transmitting entity performs spatial processing such that the data transmission observes different effective channels across the subbands used for data transmission. Consequently, performance is not dictated by a bad channel realization. The spatial processing for steering diversity is also such that the single-antenna receiving entity can perform the normal processing for SISO operation (and does not need to do any other special processing for transmit diversity) in order to recover the data transmission and enjoy the benefits of transmit diversity. For clarity, the following description is generally for one OFDM symbol, and the index for time is omitted.
  • [0031]
    FIG. 5 shows a model for transmission with steering diversity for one subband k from multi-antenna transmitting entity 210 to single-antenna receiving entity 250 x. A modulation symbol s(k) to be sent on subband k is spatially processed with T complex weights (or scalar values) v0(k) through vT−1(k) to obtain T transmit symbols for subband k, which are then processed and sent from the T transmit antennas. The T transmit symbols for subband k observe channel responses of h0(k) through hT−1(k).
  • [0032]
    The transmitting entity performs spatial processing for each subband k for steering diversity, as follows:
  • [0000]

    x (k)= v (ks(k), for k=0, . . . , K−1,  Eq(2)
  • [0000]
    where s(k) is a modulation symbol to be sent on subband k;
      • v(k)=[v0(k)v1(k) . . . vT−1(k)]T is a T×1 steering vector for subband k;
      • x(k)=[x0(k)x1(k) . . . xT−1(k)]T is a T×1 vector with T transmit symbols to be sent from the T transmit antennas on subband k; and
      • T” denotes a transpose.
        In general, the modulation symbol s(k) may be any real or complex value (e.g., a signal value of zero) and does not need to be from a signal constellation.
  • [0036]
    The received symbols at the receiving entity for each subband k may be expressed as:
  • [0000]
    r ( k ) = h _ ( k ) · x _ ( k ) + n ( k ) , = h _ ( k ) · v _ ( k ) · s ( k ) + n ( k ) , = h eff ( k ) · s ( k ) + n ( k ) , for k = 0 , , K - 1 , Eq ( 3 )
  • [0000]
    where r(k) is a received symbol for subband k;
      • heff(k) is an effective SISO channel response for subband k, which is heff(k)=h(k)·v(k); and
      • n(k) is the noise for subband k.
  • [0039]
    As shown in equation (3), the spatial processing by the transmitting entity for steering diversity results in the modulation symbol s(k) for each subband k observing the effective SISO channel response heff(k), which includes the actual MISO channel response h(k) and the steering vector v(k) for that subband. The receiving entity can estimate the effective SISO channel response heff(k), for example, based on pilot symbols received from the transmitting entity. The receiving entity can then perform detection or matched filtering on the received symbol r(k) for each subband k with the effective SISO channel response estimate ĥeff(k) for that subband to obtain a detected symbol ŝ(k), which is an estimate of the modulation symbol s(k) transmitted on the subband.
  • [0040]
    The receiving entity may perform matched filtering as follows:
  • [0000]
    s ^ ( k ) = h ^ eff * ( k ) · r ( k ) h ^ eff ( k ) 2 = s ( k ) + n ( k ) , Eq ( 4 )
  • [0000]
    where “*” denotes a conjugate and n′(k) is the noise after the matched filtering. The detection operation in equation (4) is the same as would be performed by the receiving entity for a SISO transmission. However, the effective SISO channel response estimate, ĥeff(k), is used for detection instead of a SISO channel response estimate, ĥ(k).
  • [0041]
    For steering diversity, the receiving entity does not need to know whether a single antenna or multiple antennas are used for data transmission and also does not need to know the steering vector used for each subband. The receiving entity can nevertheless enjoy the benefits of transmit diversity if different steering vectors are used across the subbands and different effective SISO channels are formed for these subbands. A data transmission sent across multiple subbands would then observe an ensemble of different effective SISO channels across the subbands used for data transmission.
  • [0042]
    FIG. 6 shows a block diagram of a TX spatial processor 220 a and an OFDM modulator 230 a, which are an embodiment of TX spatial processor 220 and OFDM modulator 230, respectively, in FIG. 2. TX spatial processor 220 a receives K modulation symbols (or generically, input symbols) s(0) through s(K−1) for the K subbands for each OFDM symbol period. Within TX spatial processor 220 a, a different set of K multipliers 620 multiplies the K modulation symbols with a set of K weights vi(0) through vi(K−1)) for each transmit antenna i and provides K weighted symbols for that antenna. The modulation symbol s(k) for each subband k is transmitted from all T antennas and is multiplied with T weights v0(k) through vT−1(k) for the T transmit antennas for that subband. TX spatial processor 220 a provides T sets of K weighted symbols for the T transmit antennas.
  • [0043]
    Within OFDM modulator 230 a, the set of K weighted symbols for each transmit antenna i is transformed to the time-domain by a respective IDFT unit 632 to obtain a transformed symbol for that antenna. The K time-domain samples for the transformed symbol for each transmit antenna i are serialized by a respective P/S converter 634 and further appended with a cyclic prefix by a cyclic prefix generator 636 to generate an OFDM symbol for that antenna. The OFDM symbol for each transmit antenna i is then conditioned by transmitter unit 232 for that antenna and transmitted via the antenna.
  • [0044]
    For steering diversity, the transmitting entity uses different steering vectors for different subbands, with each steering vector defining or forming a beam for the associated subband. In general, it is desirable to use as many different steering vectors as possible across the subbands to achieve greater transmit diversity. For example, a different steering vector may be used for each of the K subbands, and the set of K steering vectors used for the K subbands may be denoted as {v(k)}. For each subband, the steering vector may be the same over time or may change, e.g., from symbol period to symbol period.
  • [0045]
    In general, any steering vector may be used for each of the K subbands for steering diversity. However, to ensure that performance is not degraded for single-antenna devices that are not aware of the steering diversity being performed and further rely on some correlation across the subbands, the steering vectors may be defined such that the beams vary in a continuous instead of abrupt manner across the subbands. This may be achieved by applying continuously changing phase shifts across the subbands for each transmit antenna. As an example, the phase shifts may change in a linear manner across the subbands for each transmit antenna, and each antenna may be associated with a different phase slope, as described below. The application of linearly changing phase shifts to modulation symbols in the frequency domain may be achieved by temporally modifying (e.g., either delaying or circularly shifting) the corresponding time-domain samples. If different steering vectors are used for different subbands, then the modulation symbols for these subbands are beamed in different directions by the array of N transmit antennas. If encoded data is spread over multiple subbands with different steering, then decoding performance will likely improve due to the increased diversity.
  • [0046]
    If the steering vectors for adjacent subbands generate beams in very different directions, then the effective SISO channel response heff(k) would also vary widely among the adjacent subbands. Some receiving entities may not be aware of steering diversity being performed, such as legacy single-antenna devices in an IEEE 802.11a system. These receiving entities may assume that the channel response varies slowly across the subbands and may perform channel estimation in a manner to simplify the receiver design. For example, these receiving entities may estimate the channel response for a subset of the K total subbands and use interpolation or some other techniques to derive estimates of the channel response for the other subbands. The use of abruptly changing steering vectors (e.g., pseudo-random steering vectors) may severely degrade the performance of these receiving entities.
  • [0047]
    To provide transmit diversity and avoid degrading the performance of legacy receiving entities, the steering vectors may be selected such that (1) different beams are used for different subbands and (2) the beams for adjacent subbands have smooth instead of abrupt transitions. The weights to use for the K subbands of the T transmit antennas may be expressed as:
  • [0000]
    V _ = [ v _ ( 0 ) v _ ( 1 ) v _ ( K - 1 ) ] = [ v 0 ( 0 ) v 0 ( 1 ) v 0 ( K - 1 ) v 1 ( 0 ) v 1 ( 1 ) v 1 ( K - 1 ) v T - 1 ( 0 ) v T - 1 ( 1 ) v T - 1 ( K - 1 ) ] , Eq ( 5 )
  • [0000]
    where V is a T×K matrix of weights for the K subbands of the T transmit antennas.
  • [0048]
    In an embodiment, the weights in the matrix V are defined as follows:
  • [0000]
    v i ( k ) = B ( i ) · j 2 π · i · k K , for i = 0 , , T - 1 and k = 0 , , K - 1 , Eq ( 6 )
  • [0000]
    where B(i) is a complex gain for transmit antenna i;
      • vi(k) is the weight for subband k of transmit antenna i; and
      • j is the imaginary value defined by j=√{square root over (−1)}.
  • [0051]
    The magnitude of the complex gain for each transmit antenna may be set to one, or ∥B(i)∥=1.0 for i=0, . . . , T−1. The weights shown in equation (6) correspond to a progressive phase shift for each subband and antenna. These weights effectively form a slightly different beam for each subband for a linear array of T equally spaced antennas.
  • [0052]
    In a specific embodiment, the weights are defined as follows:
  • [0000]
    v i ( k ) = - j π · i · j 2 π · i · k K = j 2 π i K · ( k - K 2 ) , Eq ( 7 )
  • [0000]
    for i=0, . . . , T−1 and k=0, . . . , K−1. The embodiment shown in equation (7) uses B(i)=e−jπ·i for equation (6). This results in a different phase shift being applied to each antenna.
  • [0053]
    FIG. 7 shows plots of the phase shifts for each transmit antenna for a case with T=4. The center of the K subbands is typically considered to be at zero frequency, as shown in FIG. 3. The weights generated based on equation (7) may be interpreted as creating a linear phase shift across the K subbands. Each transmit antenna i, for i=0, . . . , T−1, is associated with a phase slope of 2π·i/K. The phase shift for each subband k, for k=0, . . . , K−1, for each transmit antenna i is given as 2π·i·(k−K/2)/K. The use of B(i)=e−jπ·i result in subband k=K/2 observing a phase shift of zero.
  • [0054]
    The weights derived based on equation (7) may be viewed as a linear filter having a discrete frequency response of Gi(k′), which may be expressed as:
  • [0000]
    G i ( k ) = v i ( k + K / 2 ) = j 2 π i · k K , Eq ( 8 )
  • [0000]
    for i=0, . . . , T−1 and k′=(−K/2), . . . , (K/2−1). The subband index k is for a subband numbering scheme that places the zero frequency at subband Ncenter=K/2, as shown in FIG. 3. The subband index k′ is a shifted version of the subband index k by K/2, or k′=k−K/2. This results in subband zero being at zero frequency for the new subband numbering scheme with the index k′. Ncenter may be equal to some other value instead of K/2 if the index k is defined in some other manner (e.g., k=1, . . . , K) or if K is an odd number.
  • [0055]
    A discrete time-domain impulse response gi(n) for the linear filter may be obtained by performing a K-point IDFT on the discrete frequency response Gi(k′). The impulse response gi(n) may be expressed as:
  • [0000]
    g i ( n ) = 1 K · k = - K / 2 K / 2 - 1 G i ( k ) · j2π n · k K , = 1 K · k = - K / 2 K / 2 - 1 j 2 π i · k K · j 2 π n · k K , = 1 K · k = - K / 2 K / 2 - 1 j 2 π k K ( i + n ) , = { 1 for n = - i 0 otherwise Eq ( 9 )
  • [0000]
    where n is an index for sample period and has a range of n=0, . . . , K−1. Equation (9) indicates that the impulse response gi(n) for transmit antenna i has a single unit-value tap at a delay of i sample periods and is zero at all other delays.
  • [0056]
    The spatial processing with the weights defined as shown in equation (7) may be performed by multiplying the K modulation symbols for each transmit antenna i with the K weights vi(0) through vi(K−1) for that antenna and then performing a K-point IDFT on the K weighted symbols. Equivalently, the spatial processing with these weights may be achieved by (1) performing a K-point IDFT on the K modulation symbols to obtain K time-domain samples, and (2) performing a circular convolution of the K time-domain samples with the impulse response gi(n), which has a single unit-value tap at a delay of i sample periods.
  • [0057]
    FIG. 8A shows a block diagram of a TX spatial processor 220 b and an OFDM modulator 230 b, which are another embodiment of TX spatial processor 220 and OFDM modulator 230, respectively, in FIG. 2. OFDM modulator 220 b receives K modulation symbols s(0) through s(K−1) for the K subbands for each OFDM symbol period. Within OFDM modulator 230 b, an IDFT unit 832 performs a K-point IDFT on the K modulation symbols and provides K time-domain samples. A P/S converter 834 serializes the K time-domain samples. A cyclic prefix generator 836 then appends a C-sample cyclic prefix and provides an OFDM symbol containing K+C samples to TX spatial processor 220 b. TX spatial processor 220 b includes T digital delay units 822 a through 822 t for the T transmit antennas. Each delay unit 822 receives and delays the OFDM symbol from OFDM demodulator 230 b by a different amount determined by the associated transmit antenna. In particular, delay unit 822 a for transmit antenna 234 a delays the OFDM symbol by zero sample period, delay unit 822 b for transmit antenna 234 b delays the OFDM symbol by one sample period, and so on, and delay unit 822 t for transmit antenna 234 t delays the OFDM symbol by T−1 sample periods. The subsequent processing by transmitter units 232 is as described above.
  • [0058]
    FIG. 8B shows a block diagram of OFDM modulator 230 b and a TX spatial processor 220 c, which is yet another embodiment of TX spatial processor 220 in FIG. 2. OFDM modulator 220 b performs OFDM modulation on K modulation symbols for each OFDM symbol period as described above for FIG. 8A. Transmitter unit 232 then receives and conditions the OFDM symbol for each symbol period to generate a modulated signal. TX spatial processor 220 c provides time delay in the analog domain. TX spatial processor 220 c includes T analog delay units 824 a through 824 t for the T transmit antennas. Each delay unit 824 receives and delays the modulated signal by a different amount determined by the associated transmit antenna. In particular, delay unit 824 a for the first transmit antenna 234 a delays the modulated signal by zero seconds, delay unit 824 b for the second transmit antenna 234 b delays the modulated signal by one sample period (or Tsam seconds), and so on, and delay unit 824 t for the T-th transmit antenna 234 t delays the modulated signal by (T−1) sample periods (or (T−1)·Tsam seconds). A sample period is equal to Tsam=1/(BW·(K+C)), where BW is the overall bandwidth of the system in Hertz.
  • [0059]
    FIG. 8C shows a timing diagram for the T transmissions from the T transmit antennas for the embodiments shown in FIGS. 8A and 8B. The same OFDM symbol is transmitted from each of the T transmit antennas. However, the OFDM symbol sent from each transmit antenna is delayed by a different amount. The T delayed and non-delayed OFDM symbols for the T antennas may be viewed as T different versions of the same OFDM symbol.
  • [0060]
    For the embodiments shown in equations (7) through (9) and FIGS. 8A through 8C, the delays for the T transmit antennas are in integer numbers of sample periods. Phase slopes that result in non-integer delays for the T transmit antennas (or B(i)=e−jπi/L, where L>1) may also be implemented. For example, the time-domain samples from OFDM modulator 230 b in FIG. 8A may be up-sampled to a higher rate (e.g., with a period of Tupsam=Tsam/L), and the higher rate samples may be delayed by digital delay units 822 by integer numbers of the higher rate sample period (Tupsam). Alternatively, analog delay units 824 in FIG. 8B may provide delays in integer numbers of Tupsam (instead of Tsam).
  • [0061]
    When the number of transmit antennas is less than the cyclic prefix length (or T<C), the cyclic prefix appended to each OFDM symbol makes a linear delay by digital delay units 822 or analog delay units 824 appears like a circular rotation for the circular convolution with the time-domain impulse response gi(n). The weights as defined in equation (7) may thus be implemented by a time delay of i sample periods for each transmit antenna i, as shown in FIGS. 8A through 8C. However, as shown in FIG. 8C, the OFDM symbol is transmitted from the T transmit antennas at different delays, which reduces the effectiveness of the cyclic prefix to protect against multipath delay.
  • [0062]
    The IDFT of K weighted symbols (which are obtained by multiplying K modulation symbols with the phase slope shown in equation (7)) provides a time-domain sample sequence that is equal to a circular shift of the K time-domain samples from the IDFT of the K (original unweighted) modulation symbols. The spatial processing may thus be performed by circularly shifting these K time-domain samples.
  • [0063]
    FIG. 9A shows a block diagram of an OFDM modulator 230 d and a TX spatial processor 220 d, which are yet another embodiment of OFDM modulator 230 and TX spatial processor 220, respectively, in FIG. 2. Within OFDM modulator 230 d, an IDFT unit 932 performs a K-point IDFT on the K modulation symbols and provides K time-domain samples, and a P/S converter 934 serializes the K time-domain samples. TX spatial processor 220 d includes T circular shift units 922 a through 922 t for the T transmit antennas. Each unit 922 receives the K time-domain samples from P/S converter 934, performs a circular shift of the K time-domain samples by i samples for transmit antenna i, and provides a circular-shifted transformed symbol containing K samples. In particular, unit 922 a performs a circular shift by 0 sample for transmit antenna 234 a, unit 922 b performs a circular shift by 1 sample for transmit antenna 234 b, and so on, and unit 922 t performs a circular shift by (T−1) samples for transmit antenna 234 t. T cyclic prefix generators 936 a through 936 t receive the circular-shifted transformed symbols from units 922 a through 922 t, respectively. Each cyclic prefix generator 936 appends a C-sample cyclic prefix to its circular-shifted transformed symbol and provides an OFDM symbol containing (K+C) samples. The subsequent processing by transmitter units 232 a through 232 t is as described above.
  • [0064]
    FIG. 9B shows a timing diagram for the T transmissions from the T transmit antennas for the embodiment shown in FIG. 9A. A different version of the OFDM symbol is generated for each of the T transmit antennas by circularly shifting a different amount. However, the T different versions of the OFDM symbol are sent from the T transmit antennas at the same time.
  • [0065]
    The embodiments shown in FIGS. 8A, 8B, and 9A illustrate some of the ways in which spatial processing for steering diversity may be performed. In general, the spatial processing for steering diversity may be performed in various manners and at various locations within the transmitting entity. For example, the spatial processing may be performed in the time-domain or the frequency-domain, using digital circuitry or analog circuitry, prior to or after the OFDM modulation, and so on.
  • [0066]
    Equations (6) and (7) represent a function that provides linearly changing phase shifts across the K subbands for each transmit antenna. The application of linearly changing phase shifts to modulation symbols in the frequency domain may be achieved by either delaying or circularly shifting the corresponding time-domain samples, as described above. In general, the phase shifts across the K subbands for each transmit antenna may be changed in a continuous manner using any function so that the beams are varied in a continuous instead of abrupt manner across the subbands. A linear function of phase shifts is just one example of a continuous function. The continuous change ensures that the performance for single-antenna devices that rely on some amounts of correlation across the subbands (e.g., to simplify channel estimation) is not degraded.
  • [0067]
    In the description above, steering diversity is achieved for a transmission of one modulation symbol on each subband in each symbol period. Multiple (S) modulation symbols may also be sent via the T transmit antennas on one subband in one symbol period to a multi-antenna receiving entity with R receive antennas using steering diversity, where S≦min {T, R}
  • [0068]
    The steering diversity techniques described herein may be used for various wireless systems. These techniques may also be used for the downlink (or forward link) as well as the uplink (or reverse link). Steering diversity may be performed by any entity equipped with multiple antennas.
  • [0069]
    Steering diversity may be used in various manners. For example, a transmitting entity (e.g., an access point or a user terminal) may use steering diversity to transmit to a receiving entity (e.g., another access point or user terminal) when accurate information about the wireless channel is not available. Accurate channel information may not be available due to various reasons such as, for example, a feedback channel that is corrupted, a system that is poorly calibrated, the channel conditions changing too rapidly for the transmitting entity to use/adjust beam steering on time, and so on. The rapidly changing channel conditions may be due to, for example, the transmitting and/or receiving entity moving at a high velocity.
  • [0070]
    Steering diversity may also be used for various applications in a wireless system. In one application, broadcast channels in the system may be transmitted using steering diversity as described above. The use of steering diversity allows wireless devices in the system to possibly receive the broadcast channels with improved reliability, thereby increasing the range of the broadcast channels. In another application, a paging channel is transmitted using steering diversity. Again, improved reliability and greater coverage may be achieved for the paging channel via the use of steering diversity. In yet another application, an 802.11a access point uses steering diversity to improve the performance of user terminals under its coverage area.
  • [0071]
    The steering diversity techniques described herein may be implemented by various means. For example, these techniques may be implemented in hardware, software, or a combination thereof. For a hardware implementation, the processing units used to perform spatial processing for steering diversity may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof.
  • [0072]
    For a software implementation, the steering diversity techniques may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory unit (e.g., memory unit 242 in FIG. 2) and executed by a processor (e.g., controller 240). The memory unit may be implemented within the processor or external to the processor, in which case it can be communicatively coupled to the processor via various means as is known in the art.
  • [0073]
    The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (18)

1. A method of transmitting data in a wireless communication system, comprising:
obtaining input symbols to be transmitted on a plurality of frequency subbands of a plurality of antennas;
modifying an input symbol for each frequency subband of each antenna with a phase shift selected for the frequency subband and the respective antenna to generate a phase-shifted symbol for the frequency subband and the respective antenna; and
processing phase-shifted symbols for the plurality of frequency subbands of each antenna to obtain a sequence of samples for the respective antenna.
2. The method of claim 1, further comprising:
applying linearly varying phase shifts across the plurality of frequency subbands for each antenna.
3. The method of claim 1, further comprising:
applying a different phase slope across the plurality of frequency subbands for each antenna.
4. The method of claim 1, further comprising:
applying continuously varying phase shifts across the plurality of frequency subbands for each antenna.
5. The method of claim 4, further comprising:
determining the continuously varying phase shifts across the frequency subbands for each antenna based on a function selected for the respective antenna.
6. The method of claim 1, wherein the processing the phase-shifted symbols comprises
performing orthogonal frequency division multiplexing (OFDM) modulation on the phase-shifted symbols for the plurality of frequency subbands of each antenna to obtain the sequence of samples for the respective antenna.
7. An apparatus in a wireless communication system, comprising:
a spatial processor to obtain input symbols to be transmitted on a plurality of frequency subbands of a plurality of antennas and to modify an input symbol for each frequency subband of each antenna with a phase shift selected for the frequency subband and the respective antenna to generate a phase-shifted symbol for the frequency subband and the respective antenna; and
a modulator to process phase-shifted symbols for the plurality of frequency subbands of each antenna to obtain a sequence of samples for the respective antenna.
8. The apparatus of claim 7, wherein the spatial processor applies linearly varying phase shifts across the plurality of frequency subbands for each antenna.
9. The apparatus of claim 7, wherein the spatial processor applies a different phase slope across the plurality of frequency subbands for each antenna.
10. The apparatus of claim 7, wherein the spatial processor applies continuously varying phase shifts across the plurality of frequency subbands for each antenna.
11. An apparatus in a wireless communication system, comprising:
means for obtaining input symbols to be transmitted on a plurality of frequency subbands of a plurality of antennas;
means for modifying an input symbol for each frequency subband of each antenna with a phase shift selected for the frequency subband and the respective antenna to generate a phase-shifted symbol for the frequency subband and the respective antenna; and
means for processing phase-shifted symbols for the plurality of frequency subbands of each antenna to obtain a sequence of samples for the respective antenna.
12. The apparatus of claim 11, further comprising:
means for applying linearly varying phase shifts across the plurality of frequency subbands for each antenna.
13. The apparatus of claim 11, further comprising:
means for applying a different phase slope across the plurality of frequency subbands for each antenna.
14. The apparatus of claim 11, further comprising:
means for applying continuously varying phase shifts across the plurality of frequency subbands for each antenna.
15. A computer-program apparatus for processing data in a wireless communication system comprising a computer readable medium having instructions stored thereon, the instructions being executable by one or more processors and the instructions comprising:
instructions for processing data to obtain an input sequence of time-domain samples;
instructions for obtaining input symbols to be transmitted on a plurality of frequency subbands of a plurality of antennas;
instructions for modifying an input symbol for each frequency subband of each antenna with a phase shift selected for the frequency subband and the respective antenna to generate a phase-shifted symbol for the frequency subband and the respective antenna; and
instructions for processing phase-shifted symbols for the plurality of frequency subbands of each antenna to obtain a sequence of samples for the respective antenna.
16. The computer-program apparatus of claim 15, further comprising:
instructions for applying linearly varying phase shifts across the plurality of frequency subbands for each antenna.
17. The computer-program apparatus of claim 15, further comprising:
instructions for applying a different phase slope across the plurality of frequency subbands for each antenna.
18. The computer-program apparatus of claim 15, further comprising:
instructions for applying continuously varying phase shifts across the plurality of frequency subbands for each antenna.
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Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050180312A1 (en) * 2004-02-18 2005-08-18 Walton J. R. Transmit diversity and spatial spreading for an OFDM-based multi-antenna communication system
US20050249174A1 (en) * 2004-05-07 2005-11-10 Qualcomm Incorporated Steering diversity for an OFDM-based multi-antenna communication system
US20070009059A1 (en) * 2004-06-30 2007-01-11 Wallace Mark S Efficient computation of spatial filter matrices for steering transmit diversity in a MIMO communication system
US20070206686A1 (en) * 2006-01-05 2007-09-06 Vook Frederick W Method and apparatus for performing cyclic-shift diversity with beamforming
US20110105063A1 (en) * 2008-06-25 2011-05-05 Takashi Yamamoto Radio communication device and signal transmission method in mimo radio communication
US20110143807A1 (en) * 2009-12-14 2011-06-16 Blue Wonder Communications Gmbh Method and apparatus for data communication in lte cellular networks
US7978778B2 (en) 2004-09-03 2011-07-12 Qualcomm, Incorporated Receiver structures for spatial spreading with space-time or space-frequency transmit diversity
US7978649B2 (en) 2004-07-15 2011-07-12 Qualcomm, Incorporated Unified MIMO transmission and reception
US8169889B2 (en) 2004-02-18 2012-05-01 Qualcomm Incorporated Transmit diversity and spatial spreading for an OFDM-based multi-antenna communication system
US8204149B2 (en) 2003-12-17 2012-06-19 Qualcomm Incorporated Spatial spreading in a multi-antenna communication system
US8290089B2 (en) 2006-05-22 2012-10-16 Qualcomm Incorporated Derivation and feedback of transmit steering matrix
US8325844B2 (en) 2004-01-13 2012-12-04 Qualcomm Incorporated Data transmission with spatial spreading in a MIMO communication system
US8543070B2 (en) 2006-04-24 2013-09-24 Qualcomm Incorporated Reduced complexity beam-steered MIMO OFDM system
US20140286384A1 (en) * 2013-03-19 2014-09-25 Fundació Centre Tecnològic De Telecomunicacions De Catalunya Method for equalizing filterbank multicarrier (fbmc)modulations
US8909174B2 (en) 2004-05-07 2014-12-09 Qualcomm Incorporated Continuous beamforming for a MIMO-OFDM system

Families Citing this family (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006029362A1 (en) * 2004-09-09 2006-03-16 Agere Systems Inc. Method and apparatus for communicating orthogonal pilot tones in a multiple antenna communication system
US7366250B2 (en) * 2004-09-09 2008-04-29 Agere Systems Inc. Method and apparatus for improved efficiency in an extended multiple antenna communication system
JP4569929B2 (en) * 2005-01-17 2010-10-27 シャープ株式会社 Communication device
US7738356B2 (en) * 2005-06-28 2010-06-15 Broadcom Corporation Multiple stream cyclic-shifted delay transmitter
US8165537B2 (en) 2005-12-26 2012-04-24 Sharp Kabushiki Kaisha Wireless transmitter and wireless transmission method
KR20070083048A (en) * 2006-02-20 2007-08-23 삼성전자주식회사 Apparatus and method for transmitting signal in wireless communication system
CN101056133B (en) * 2006-03-15 2011-09-14 华为技术有限公司 Multi-antenna transmission diversity method and device of orthogonal frequency division multiplexing system
WO2007104203A1 (en) * 2006-03-15 2007-09-20 Huawei Technologies Co., Ltd. Multi-antenna transmitting method in orthogonal frequency division multiplexing system and an apparatus thereof
KR101241895B1 (en) * 2006-04-10 2013-03-11 엘지전자 주식회사 method for repetitive transmission using a plurality of carrier
EP2030393B1 (en) * 2006-05-26 2018-01-24 LG Electronics Inc. Signal generation using phase-shift based pre-coding
JP5025022B2 (en) * 2006-07-20 2012-09-12 シャープ株式会社 Multicarrier signal receiving apparatus and a multicarrier signal receiving method
JP5006001B2 (en) 2006-08-22 2012-08-22 株式会社エヌ・ティ・ティ・ドコモ Downlink mimo transmission control method and a base station apparatus
DE102006047978A1 (en) * 2006-10-10 2008-04-17 Siemens Ag A method of operating a radio communication system that uses OFDM, and radio communication system, transmitting station and receiving station
US8374271B2 (en) * 2007-01-08 2013-02-12 Cisco Technology, Inc. Method and system for resizing a MIMO channel
KR20090030200A (en) 2007-09-19 2009-03-24 엘지전자 주식회사 Data transmitting and receiving method using phase shift based precoding and transceiver supporting the same
US8126076B2 (en) * 2007-02-27 2012-02-28 Motorola Mobility, Inc. Method and apparatus for transmission within a multi-carrier communication system
US8218496B2 (en) * 2007-10-26 2012-07-10 Texas Instruments Incorporated Random access cyclic prefix dimensioning in wireless networks
WO2009149561A1 (en) * 2008-06-12 2009-12-17 Nortel Networks Limited Systems and methods for sc-fdma transmission diversity
US8526529B2 (en) * 2008-08-05 2013-09-03 Lg Electronics Inc. Radio access method for reduced PAPR
US8619544B2 (en) 2008-09-23 2013-12-31 Qualcomm Incorporated Apparatus and method for facilitating transmit diversity for communications
CN101616360B (en) * 2009-07-24 2012-05-09 中兴通讯股份有限公司 Method and system for sending positioning reference signal
KR101079549B1 (en) 2009-08-06 2011-11-02 고려대학교 산학협력단 multi-antenna system using adaptive beamforming
CN101697535A (en) 2009-10-29 2010-04-21 中兴通讯股份有限公司 Positioning reference signal sending method, data sending method and data receiving method
JP5623248B2 (en) * 2010-09-10 2014-11-12 パナソニックインテレクチュアル プロパティ コーポレーション オブアメリカPanasonic Intellectual Property Corporation of America Transmission method, transmission apparatus, a reception method and a receiver
US8971210B1 (en) * 2011-05-23 2015-03-03 Redpine Signals, Inc. Reconfigurable multi-stream processor for multiple-input multiple-output (MIMO) wireless networks
KR20130068868A (en) 2011-12-16 2013-06-26 삼성전자주식회사 Apparatus and method for transmmiting signal in a wireless communication system
EP2957081A1 (en) * 2013-02-12 2015-12-23 Nokia Solutions and Networks Oy Zero insertion for isi free ofdm reception

Citations (85)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5668837A (en) * 1993-10-14 1997-09-16 Ericsson Inc. Dual-mode radio receiver for receiving narrowband and wideband signals
US5757845A (en) * 1994-02-10 1998-05-26 Ntt Mobile Communications Network Adaptive spread spectrum receiver
US6118758A (en) * 1996-08-22 2000-09-12 Tellabs Operations, Inc. Multi-point OFDM/DMT digital communications system including remote service unit with improved transmitter architecture
US6175743B1 (en) * 1998-05-01 2001-01-16 Ericsson Inc. System and method for delivery of short message service messages to a restricted group of subscribers
US6198775B1 (en) * 1998-04-28 2001-03-06 Ericsson Inc. Transmit diversity method, systems, and terminals using scramble coding
US6218985B1 (en) * 1999-04-15 2001-04-17 The United States Of America As Represented By The Secretary Of The Navy Array synthesis method
US6298035B1 (en) * 1999-12-21 2001-10-02 Nokia Networks Oy Estimation of two propagation channels in OFDM
US20020009125A1 (en) * 2000-06-12 2002-01-24 Shi Zhen Liang High bandwidth efficient spread spectrum modulation using chirp waveform
US6351499B1 (en) * 1999-12-15 2002-02-26 Iospan Wireless, Inc. Method and wireless systems using multiple antennas and adaptive control for maximizing a communication parameter
US20020091943A1 (en) * 2000-12-15 2002-07-11 International Business Machines Corporation Methods, systems, signals and media for encouraging users of computer readable content to register
US20020102940A1 (en) * 2000-11-20 2002-08-01 Ralf Bohnke Adaptive subcarrier loading
US20020114269A1 (en) * 2000-10-03 2002-08-22 Onggosanusi Eko Nugroho Channel aware optimal space-time signaling for wireless communication over wideband multipath channels
US6441786B1 (en) * 2001-07-20 2002-08-27 Motorola, Inc. Adaptive antenna array and method for control thereof
US20020127978A1 (en) * 2001-01-30 2002-09-12 Koninklijke Philips Electronics N.V. Radio communication system
US6452981B1 (en) * 1996-08-29 2002-09-17 Cisco Systems, Inc Spatio-temporal processing for interference handling
US6473467B1 (en) * 2000-03-22 2002-10-29 Qualcomm Incorporated Method and apparatus for measuring reporting channel state information in a high efficiency, high performance communications system
US20030011274A1 (en) * 2001-07-13 2003-01-16 Moteurs Leroy-Somer Discoid machine
US20030016637A1 (en) * 2001-05-25 2003-01-23 Khayrallah Ali S. Time interval based channel estimation with transmit diversity
US6542556B1 (en) * 2000-03-31 2003-04-01 Nokia Mobile Phones Ltd. Space-time code for multiple antenna transmission
US20030076908A1 (en) * 2001-08-24 2003-04-24 Huang Howard C. Signal detection by a receiver in a multiple antenna time-dispersive system
US20030108117A1 (en) * 2001-12-07 2003-06-12 Ketchum John W. Time-domain transmit and receive processing with channel eigen-mode decompositon for MIMO systems
US20030112745A1 (en) * 2001-12-17 2003-06-19 Xiangyang Zhuang Method and system of operating a coded OFDM communication system
US20030123567A1 (en) * 2001-12-27 2003-07-03 Haruhiko Shigemasa Transmitter apparatus and communication system employing the same
US20030123565A1 (en) * 2001-12-12 2003-07-03 Ntt Docomo, Inc. Radio communication method and apparatus
US20030128658A1 (en) * 2002-01-08 2003-07-10 Walton Jay Rod Resource allocation for MIMO-OFDM communication systems
US20030161282A1 (en) * 2002-02-26 2003-08-28 Irina Medvedev Multiple-input, multiple-output (MIMO) systems with multiple transmission modes
US6618454B1 (en) * 1998-02-06 2003-09-09 At&T Corp. Diversity coded OFDM for high data-rate communication
US20030181211A1 (en) * 2002-03-19 2003-09-25 Javad Razavilar Method and apparatus for dynamic channel selection in wireless modems
US20040002364A1 (en) * 2002-05-27 2004-01-01 Olav Trikkonen Transmitting and receiving methods
US6678263B1 (en) * 1998-09-18 2004-01-13 Hughes Electronics Corporation Method and constructions for space-time codes for PSK constellations for spatial diversity in multiple-element antenna systems
US20040022183A1 (en) * 2002-08-01 2004-02-05 Li Kuo Hui System and method for transmitting data in a multiple-branch transmitter-diversity orthogonal frequency-division multiplexing (OFDM) system
US20040042439A1 (en) * 2002-08-27 2004-03-04 Menon Murali Paravath Beam-steering and beam-forming for wideband MIMO/MISO systems
US20040052315A1 (en) * 2000-10-03 2004-03-18 Jorn Thielecke Multi strata system
US6711528B2 (en) * 2002-04-22 2004-03-23 Harris Corporation Blind source separation utilizing a spatial fourth order cumulant matrix pencil
US20040066773A1 (en) * 2002-10-01 2004-04-08 Atheros Communications, Inc. Decision feedback channel estimation and pilot tracking for OFDM systems
US20040082356A1 (en) * 2002-10-25 2004-04-29 Walton J. Rodney MIMO WLAN system
US20040081263A1 (en) * 2002-10-24 2004-04-29 Lee King F. Method and apparatus for receiving diversity transmissions
US20040085939A1 (en) * 2002-10-25 2004-05-06 Wallace Mark S. Channel calibration for a time division duplexed communication system
US20040086027A1 (en) * 2002-10-31 2004-05-06 Shattil Steve J. Orthogonal superposition coding for direct-sequence communications
US20040102157A1 (en) * 2002-11-27 2004-05-27 Lewis Michael E. Wireless LAN with distributed access points for space management
US6763073B2 (en) * 1998-04-15 2004-07-13 Lucent Technologies Inc. Wireless communications system having a space-time architecture employing multi-element antennas at both the transmitter and receiver
US20040139137A1 (en) * 2003-01-10 2004-07-15 Mailaender Laurence Eugene Method and apparatus for determining an inverse square root of a given positive-definite hermitian matrix
US20040136349A1 (en) * 2002-10-25 2004-07-15 Walton J. Rodney MIMO system with multiple spatial multiplexing modes
US20040157645A1 (en) * 2003-02-12 2004-08-12 Smith Adrian David System and method of operation an array antenna in a distributed wireless communication network
US20040165675A1 (en) * 2003-02-20 2004-08-26 Nec Corporation Iterative soft interference cancellation and filtering for spectrally efficient high-speed transmission in MIMO systems
US6842487B1 (en) * 2000-09-22 2005-01-11 Telefonaktiebolaget Lm Ericsson (Publ) Cyclic delay diversity for mitigating intersymbol interference in OFDM systems
US6847306B2 (en) * 2002-05-17 2005-01-25 Keyvan T. Diba Emergency traffic signal attachment
US20050017511A1 (en) * 2003-07-22 2005-01-27 Stephen Dalton Gravity air motion concept
US20050026570A1 (en) * 2003-08-02 2005-02-03 Samsung Electronics Co., Ltd. TDMA transceiver including Cartesian feedback loop circuit
US20050149320A1 (en) * 2003-12-24 2005-07-07 Matti Kajala Method for generating noise references for generalized sidelobe canceling
US20050175115A1 (en) * 2003-12-17 2005-08-11 Qualcomm Incorporated Spatial spreading in a multi-antenna communication system
US20050180312A1 (en) * 2004-02-18 2005-08-18 Walton J. R. Transmit diversity and spatial spreading for an OFDM-based multi-antenna communication system
US20050195733A1 (en) * 2004-02-18 2005-09-08 Walton J. R. Transmit diversity and spatial spreading for an OFDM-based multi-antenna communication system
US20060013250A1 (en) * 2004-07-15 2006-01-19 Howard Steven J Unified MIMO transmission and reception
US6999472B2 (en) * 2001-05-30 2006-02-14 Nokia Mobile Phones Limited Apparatus, and associated method, for space-time encoding, and decoding, data at a selected code rate
US20060050770A1 (en) * 2004-09-03 2006-03-09 Qualcomm Incorporated Receiver structures for spatial spreading with space-time or space-frequency transmit diversity
US20060067421A1 (en) * 2004-09-03 2006-03-30 Qualcomm Incorporated Spatial spreading with space-time and space-frequency transmit diversity schemes for a wireless communication system
US7031669B2 (en) * 2002-09-10 2006-04-18 Cognio, Inc. Techniques for correcting for phase and amplitude offsets in a MIMO radio device
US7061969B2 (en) * 1997-02-24 2006-06-13 Cingular Wireless Ii, Llc Vertical adaptive antenna array for a discrete multitone spread spectrum communication system
US7065156B1 (en) * 2000-08-31 2006-06-20 Nokia Mobile Phones Ltd. Hopped delay diversity for multiple antenna transmission
US7079870B2 (en) * 2003-06-09 2006-07-18 Ipr Licensing, Inc. Compensation techniques for group delay effects in transmit beamforming radio communication
US7092737B2 (en) * 2002-07-31 2006-08-15 Mitsubishi Electric Research Laboratories, Inc. MIMO systems with rate feedback and space time transmit diversity
US7095987B2 (en) * 2001-11-15 2006-08-22 Texas Instruments Incorporated Method and apparatus for received uplinked-signal based adaptive downlink diversity within a communication system
US7099678B2 (en) * 2003-04-10 2006-08-29 Ipr Licensing, Inc. System and method for transmit weight computation for vector beamforming radio communication
US7099698B2 (en) * 2002-11-04 2006-08-29 Vivato, Inc. Complementary beamforming methods and apparatuses
US7110350B2 (en) * 2003-06-18 2006-09-19 University Of Florida Research Foundation, Inc. Wireless LAN compatible multi-input multi-output system
US20070009059A1 (en) * 2004-06-30 2007-01-11 Wallace Mark S Efficient computation of spatial filter matrices for steering transmit diversity in a MIMO communication system
US7190734B2 (en) * 2001-05-25 2007-03-13 Regents Of The University Of Minnesota Space-time coded transmissions within a wireless communication network
US7206354B2 (en) * 2004-02-19 2007-04-17 Qualcomm Incorporated Calibration of downlink and uplink channel responses in a wireless MIMO communication system
US7236478B2 (en) * 2001-07-20 2007-06-26 Huawei Technologies Co., Ltd. Method and apparatus for down-link feedback multiple antenna transmission in wireless communication system
US7324429B2 (en) * 2002-10-25 2008-01-29 Qualcomm, Incorporated Multi-mode terminal in a wireless MIMO system
US7327798B2 (en) * 2001-10-19 2008-02-05 Lg Electronics Inc. Method and apparatus for transmitting/receiving signals in multiple-input multiple-output communication system provided with plurality of antenna elements
US20080031372A1 (en) * 2003-12-17 2008-02-07 Qualcomm Incorporated Broadcast transmission with spatial spreading in a multi-antenna communication system
US7336746B2 (en) * 2004-12-09 2008-02-26 Qualcomm Incorporated Data transmission with spatial spreading in a MIMO communication system
US7356073B2 (en) * 2003-09-10 2008-04-08 Nokia Corporation Method and apparatus providing an advanced MIMO receiver that includes a signal-plus-residual-interference (SPRI) detector
US20080095121A1 (en) * 2002-05-14 2008-04-24 Shattil Steve J Carrier interferometry networks
US7385617B2 (en) * 2003-05-07 2008-06-10 Illinois Institute Of Technology Methods for multi-user broadband wireless channel estimation
US7522673B2 (en) * 2002-04-22 2009-04-21 Regents Of The University Of Minnesota Space-time coding using estimated channel information
US7529177B2 (en) * 2002-08-28 2009-05-05 Agere Systems Inc. Dithering scheme using multiple antennas for OFDM systems
US7555053B2 (en) * 2004-04-14 2009-06-30 Broadcom Corporation Long training sequence for MIMO WLAN systems
US7583747B1 (en) * 2004-03-31 2009-09-01 University Of Alberta Method of systematic construction of space-time constellations, system and method of transmitting space-time constellations
US7593317B2 (en) * 2002-08-01 2009-09-22 Panasonic Corporation Radio base station apparatus
US7653142B2 (en) * 2002-10-25 2010-01-26 Qualcomm Incorporated Channel estimation and spatial processing for TDD MIMO systems
US7742546B2 (en) * 2003-10-08 2010-06-22 Qualcomm Incorporated Receiver spatial processing for eigenmode transmission in a MIMO system
US20100169396A1 (en) * 2004-11-15 2010-07-01 Qualcomm Incorporated Efficient computation for eigenvalue decomposition and singular value decomposition of matrices

Family Cites Families (92)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4337376A (en) 1979-12-31 1982-06-29 Broadcom, Incorporated Communications system and network
JP3325890B2 (en) 1990-12-07 2002-09-17 クゥアルコム・インコーポレイテッド Cdma microcellular telephone system and distributed antenna system
DE4101629C3 (en) 1991-01-21 2003-06-26 Fuba Automotive Gmbh Antenna diversity system comprising at least two antennas for the mobile reception of meter and decimeter waves
DE69331567T2 (en) 1992-05-25 2002-10-10 Alcatel Sa A method for minimizing the IF estimated Bitfehlerratefunktion in a digital space / angle diversity radio receiver
RU2103768C1 (en) * 1992-10-16 1998-01-27 Дадочкин Сергей Васильевич Method of correction of amplitude-phase characteristics of primary channels of flat digital array
US5604921A (en) 1995-07-07 1997-02-18 Nokia Mobile Phones Ltd. Radiotelephone user interface for broadcast short message service
US6134215A (en) 1996-04-02 2000-10-17 Qualcomm Incorpoated Using orthogonal waveforms to enable multiple transmitters to share a single CDM channel
US6408016B1 (en) 1997-02-24 2002-06-18 At&T Wireless Services, Inc. Adaptive weight update method and system for a discrete multitone spread spectrum communications system
US6058105A (en) 1997-09-26 2000-05-02 Lucent Technologies Inc. Multiple antenna communication system and method thereof
US6061023A (en) 1997-11-03 2000-05-09 Motorola, Inc. Method and apparatus for producing wide null antenna patterns
US6314147B1 (en) 1997-11-04 2001-11-06 The Board Of Trustees Of The Leland Stanford Junior University Two-stage CCI/ISI reduction with space-time processing in TDMA cellular networks
JP3718337B2 (en) 1998-01-08 2005-11-24 株式会社東芝 Adaptive variable directional antenna
WO2000014921A1 (en) 1998-09-04 2000-03-16 At & T Corp. Combined channel coding and space-block coding in a multi-antenna arrangement
US6363121B1 (en) 1998-12-07 2002-03-26 Lucent Technologies Inc. Wireless transmission method for antenna arrays using unitary space-time signals
GB9828216D0 (en) 1998-12-21 1999-02-17 Northern Telecom Ltd A downlink beamforming approach for frequency division duplex cellular systems
GB9901491D0 (en) * 1999-01-22 1999-03-17 Univ Bristol Receiver
WO2000049730A1 (en) 1999-02-16 2000-08-24 Mitsubishi Denki Kabushiki Kaisha Radio communication system, transmitter and receiver
US6788681B1 (en) * 1999-03-16 2004-09-07 Nortel Networks Limited Virtual private networks and methods for their operation
DE60028592D1 (en) 1999-10-19 2006-07-20 Interdigital Tech Corp Receiver for multiuser detection of CDMA-signals
US6788661B1 (en) 1999-11-12 2004-09-07 Nikia Networks Oy Adaptive beam-time coding method and apparatus
US6804307B1 (en) 2000-01-27 2004-10-12 Telefonaktiebolaget Lm Ericsson (Publ) Method and apparatus for efficient transmit diversity using complex space-time block codes
US6816555B2 (en) * 2000-02-18 2004-11-09 Sony Corporation Signal component demultiplexing apparatus, filter apparatus, receiving apparatus, communication apparatus, and communication method
KR100719785B1 (en) * 2000-05-09 2007-05-21 루센트 테크놀러지스 인크 Orthogonal Frequency Division Multiplexing Transmit Diversity System For Frequency-Selective Fading Channels
JP2001358692A (en) 2000-06-14 2001-12-26 Nec Corp Orthogonal frequency-division multiplex modulating and demodulating circuit
US6486828B1 (en) 2000-07-26 2002-11-26 Western Multiplex Adaptive array antenna nulling
US6985434B2 (en) 2000-09-01 2006-01-10 Nortel Networks Limited Adaptive time diversity and spatial diversity for OFDM
US6956897B1 (en) 2000-09-27 2005-10-18 Northwestern University Reduced rank adaptive filter
EP1398645A1 (en) 2000-12-12 2004-03-17 Matsushita Electric Industrial Co., Ltd. Radio-wave arrival-direction estimating apparatus and directional variable transceiver
JP3576099B2 (en) 2000-12-22 2004-10-13 株式会社東芝 Receiver using a smart antenna, receiving method and the beam forming circuit using smart antennas
US7050510B2 (en) 2000-12-29 2006-05-23 Lucent Technologies Inc. Open-loop diversity technique for systems employing four transmitter antennas
US6801790B2 (en) 2001-01-17 2004-10-05 Lucent Technologies Inc. Structure for multiple antenna configurations
EP1241824A1 (en) 2001-03-14 2002-09-18 TELEFONAKTIEBOLAGET LM ERICSSON (publ) Multiplexing method in a multicarrier transmit diversity system
US6496535B2 (en) * 2001-03-23 2002-12-17 Navini Networks, Inc. Method and system for effective channel estimation in a telecommunication system
GB0108381D0 (en) 2001-04-04 2001-05-23 Koninl Philips Electronics Nv Radio communication system
US6982946B2 (en) 2001-04-05 2006-01-03 Telefonaktiebolaget Lm Ericsson (Publ) Partly orthogonal multiple code trees
US7929631B2 (en) 2001-04-23 2011-04-19 Texas Instruments Incorporated Multiple space time transmit diversity communication system with selected complex conjugate inputs
US6859747B2 (en) 2001-04-26 2005-02-22 Siemens Energy & Automation, Inc. Method and apparatus for self-calibrating a motion control system
US7173981B1 (en) 2001-04-27 2007-02-06 The Directv Group, Inc. Dual layer signal processing in a layered modulation digital signal system
KR20020086167A (en) * 2001-05-11 2002-11-18 삼성전자 주식회사 Apparatus for modulating/demodulating channel using multiple transmission antenna diversity in orthogonal frequency division multiplexing system
US6785341B2 (en) 2001-05-11 2004-08-31 Qualcomm Incorporated Method and apparatus for processing data in a multiple-input multiple-output (MIMO) communication system utilizing channel state information
US20020193146A1 (en) 2001-06-06 2002-12-19 Mark Wallace Method and apparatus for antenna diversity in a wireless communication system
EP1283614A1 (en) 2001-08-10 2003-02-12 TELEFONAKTIEBOLAGET L M ERICSSON (publ) Channel estimation in a multicarrier transmit diversity system
US7149254B2 (en) 2001-09-06 2006-12-12 Intel Corporation Transmit signal preprocessing based on transmit antennae correlations for multiple antennae systems
US7248559B2 (en) 2001-10-17 2007-07-24 Nortel Networks Limited Scattered pilot pattern and channel estimation method for MIMO-OFDM systems
WO2003056742A1 (en) 2002-01-04 2003-07-10 Nokia Corporation High rate transmit diversity transmission and reception
EP1469686B1 (en) 2002-01-18 2013-05-29 Fujitsu Limited Method and apparatus for controlling feedback in closed loop transmission diversity
US7197084B2 (en) 2002-03-27 2007-03-27 Qualcomm Incorporated Precoding for a multipath channel in a MIMO system
US6847805B2 (en) 2002-03-29 2005-01-25 Lucent Technologies Inc. Method for closed-loop subspace transmission and reception in a two transmit N-receive antenna system
US6741587B2 (en) 2002-04-02 2004-05-25 Nokia Corporation Inter-frequency measurements with MIMO terminals
US6801580B2 (en) 2002-04-09 2004-10-05 Qualcomm, Incorporated Ordered successive interference cancellation receiver processing for multipath channels
KR100896682B1 (en) 2002-04-09 2003-10-17 삼성전자주식회사 Mobile communication apparatus and method having transmitting/receiving multiantenna
KR100511292B1 (en) 2002-04-30 2005-08-31 엘지전자 주식회사 Update method for beamforming weight vector of rake receiver and receiving apparatus using beamforming weight vector
EP1359684A1 (en) 2002-04-30 2003-11-05 Motorola Energy Systems Inc. Wireless transmission using an adaptive transmit antenna array
US6810506B1 (en) 2002-05-20 2004-10-26 Synopsys, Inc. Methodology for stitching reduced-order models of interconnects together
US7327800B2 (en) 2002-05-24 2008-02-05 Vecima Networks Inc. System and method for data detection in wireless communication systems
FI20021013A0 (en) 2002-05-29 2002-05-29 Nokia Corp A data transmission method and system
KR100548311B1 (en) 2002-06-07 2006-02-02 엘지전자 주식회사 Transmission diversity apparatus and method for mobile communication system
JP2004023416A (en) 2002-06-17 2004-01-22 Matsushita Electric Ind Co Ltd Directivity forming apparatus and method therefor
US7613248B2 (en) 2002-06-24 2009-11-03 Qualcomm Incorporated Signal processing with channel eigenmode decomposition and channel inversion for MIMO systems
US7095709B2 (en) 2002-06-24 2006-08-22 Qualcomm, Incorporated Diversity transmission modes for MIMO OFDM communication systems
US7301924B1 (en) 2002-07-15 2007-11-27 Cisco Technology, Inc. Media access control for MIMO wireless network
JP3677492B2 (en) 2002-07-31 2005-08-03 松下電器産業株式会社 Multicarrier transmitting apparatus and multicarrier transmitting method
DE60223367T2 (en) 2002-09-05 2008-02-14 Mitsubishi Electric Information Technology Centre Europe B.V. A method for transmitting from a base station of a MC-CDMA telecommunication system to a plurality of users
US7280625B2 (en) 2002-12-11 2007-10-09 Qualcomm Incorporated Derivation of eigenvectors for spatial processing in MIMO communication systems
US7024166B2 (en) 2002-12-18 2006-04-04 Qualcomm, Incorporated Transmission diversity systems
US7130580B2 (en) 2003-03-20 2006-10-31 Lucent Technologies Inc. Method of compensating for correlation between multiple antennas
US7327795B2 (en) 2003-03-31 2008-02-05 Vecima Networks Inc. System and method for wireless communication systems
KR100575993B1 (en) 2003-08-07 2006-05-02 삼성전자주식회사 Method and apparatus for scheduling multi-user in wireless communication system using multiple transmit/receive antenna
US7065144B2 (en) 2003-08-27 2006-06-20 Qualcomm Incorporated Frequency-independent spatial processing for wideband MISO and MIMO systems
DE60318754T2 (en) * 2003-09-15 2009-02-12 Ntt Docomo Inc. Multicarrier system with transmit diversity
EP1573936B1 (en) * 2003-09-30 2006-07-26 NTT DoCoMo, Inc. Apparatus and method for cyclic delay diversity
US7298805B2 (en) 2003-11-21 2007-11-20 Qualcomm Incorporated Multi-antenna transmission for spatial division multiple access
US7194042B2 (en) 2004-01-13 2007-03-20 Qualcomm Incorporated Data transmission with spatial spreading in a mimo communication system
DE602004014984D1 (en) * 2004-02-19 2008-08-21 Ntt Docomo Inc Apparatus and method for estimating an effective channel, and apparatus and method for providing pilot sequences
EP1716680B1 (en) * 2004-02-19 2008-08-27 NTT DoCoMo INC. Channel estimator and method for estimating a channel transfer function and apparatus and method for providing pilot sequences
EP1726111A4 (en) 2004-03-15 2012-07-04 Nortel Networks Ltd Pilot design for ofdm systems with four transmit antennas
US7447268B2 (en) * 2004-03-31 2008-11-04 Intel Corporation OFDM system with per subcarrier phase rotation
US20050238111A1 (en) 2004-04-09 2005-10-27 Wallace Mark S Spatial processing with steering matrices for pseudo-random transmit steering in a multi-antenna communication system
US8285226B2 (en) 2004-05-07 2012-10-09 Qualcomm Incorporated Steering diversity for an OFDM-based multi-antenna communication system
US7564814B2 (en) 2004-05-07 2009-07-21 Qualcomm, Incorporated Transmission mode and rate selection for a wireless communication system
US8923785B2 (en) 2004-05-07 2014-12-30 Qualcomm Incorporated Continuous beamforming for a MIMO-OFDM system
US20050267925A1 (en) 2004-05-28 2005-12-01 Clue Vladimir I Methods and apparatus for transforming amplitude-frequency signal characteristics and interpolating analytical functions using circulant matrices
US8619907B2 (en) 2004-06-10 2013-12-31 Agere Systems, LLC Method and apparatus for preamble training in a multiple antenna communication system
US7539253B2 (en) 2004-09-10 2009-05-26 Intel Corporation Interpolation in channel state feedback
US7289770B2 (en) 2004-09-28 2007-10-30 Intel Corporation Compact feedback for closed loop MIMO
US7656842B2 (en) 2004-09-30 2010-02-02 Motorola, Inc. Method and apparatus for MIMO transmission optimized for successive cancellation receivers
US7895254B2 (en) 2004-11-15 2011-02-22 Qualcomm Incorporated Eigenvalue decomposition and singular value decomposition of matrices using Jacobi rotation
KR20090115822A (en) 2004-11-15 2009-11-06 콸콤 인코포레이티드 Eigenvalue decomposition and singular value decomposition of matrices using jacobi rotation
US20060285531A1 (en) 2005-06-16 2006-12-21 Howard Steven J Efficient filter weight computation for a MIMO system
US7548730B2 (en) 2006-03-16 2009-06-16 Intel Corporation Systems and methods for improving performance of multiple spatial communication channels
US8543070B2 (en) 2006-04-24 2013-09-24 Qualcomm Incorporated Reduced complexity beam-steered MIMO OFDM system
US7787554B1 (en) 2006-05-02 2010-08-31 Marvell International Ltd. Beamforming to a subset of receive antennas in a wireless MIMO communication system

Patent Citations (99)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5668837A (en) * 1993-10-14 1997-09-16 Ericsson Inc. Dual-mode radio receiver for receiving narrowband and wideband signals
US5757845A (en) * 1994-02-10 1998-05-26 Ntt Mobile Communications Network Adaptive spread spectrum receiver
US6118758A (en) * 1996-08-22 2000-09-12 Tellabs Operations, Inc. Multi-point OFDM/DMT digital communications system including remote service unit with improved transmitter architecture
US6452981B1 (en) * 1996-08-29 2002-09-17 Cisco Systems, Inc Spatio-temporal processing for interference handling
US7061969B2 (en) * 1997-02-24 2006-06-13 Cingular Wireless Ii, Llc Vertical adaptive antenna array for a discrete multitone spread spectrum communication system
US6618454B1 (en) * 1998-02-06 2003-09-09 At&T Corp. Diversity coded OFDM for high data-rate communication
US6763073B2 (en) * 1998-04-15 2004-07-13 Lucent Technologies Inc. Wireless communications system having a space-time architecture employing multi-element antennas at both the transmitter and receiver
US6198775B1 (en) * 1998-04-28 2001-03-06 Ericsson Inc. Transmit diversity method, systems, and terminals using scramble coding
US6175743B1 (en) * 1998-05-01 2001-01-16 Ericsson Inc. System and method for delivery of short message service messages to a restricted group of subscribers
US6678263B1 (en) * 1998-09-18 2004-01-13 Hughes Electronics Corporation Method and constructions for space-time codes for PSK constellations for spatial diversity in multiple-element antenna systems
US7324482B2 (en) * 1998-09-18 2008-01-29 The Directv Group, Inc. Method and constructions for space-time codes for PSK constellations for spatial diversity in multiple-element antenna systems
US6218985B1 (en) * 1999-04-15 2001-04-17 The United States Of America As Represented By The Secretary Of The Navy Array synthesis method
US6351499B1 (en) * 1999-12-15 2002-02-26 Iospan Wireless, Inc. Method and wireless systems using multiple antennas and adaptive control for maximizing a communication parameter
US6298035B1 (en) * 1999-12-21 2001-10-02 Nokia Networks Oy Estimation of two propagation channels in OFDM
US6473467B1 (en) * 2000-03-22 2002-10-29 Qualcomm Incorporated Method and apparatus for measuring reporting channel state information in a high efficiency, high performance communications system
US6542556B1 (en) * 2000-03-31 2003-04-01 Nokia Mobile Phones Ltd. Space-time code for multiple antenna transmission
US20020009125A1 (en) * 2000-06-12 2002-01-24 Shi Zhen Liang High bandwidth efficient spread spectrum modulation using chirp waveform
US7065156B1 (en) * 2000-08-31 2006-06-20 Nokia Mobile Phones Ltd. Hopped delay diversity for multiple antenna transmission
US6842487B1 (en) * 2000-09-22 2005-01-11 Telefonaktiebolaget Lm Ericsson (Publ) Cyclic delay diversity for mitigating intersymbol interference in OFDM systems
US20040052315A1 (en) * 2000-10-03 2004-03-18 Jorn Thielecke Multi strata system
US20020114269A1 (en) * 2000-10-03 2002-08-22 Onggosanusi Eko Nugroho Channel aware optimal space-time signaling for wireless communication over wideband multipath channels
US20020102940A1 (en) * 2000-11-20 2002-08-01 Ralf Bohnke Adaptive subcarrier loading
US20020091943A1 (en) * 2000-12-15 2002-07-11 International Business Machines Corporation Methods, systems, signals and media for encouraging users of computer readable content to register
US20020127978A1 (en) * 2001-01-30 2002-09-12 Koninklijke Philips Electronics N.V. Radio communication system
US7190734B2 (en) * 2001-05-25 2007-03-13 Regents Of The University Of Minnesota Space-time coded transmissions within a wireless communication network
US6711124B2 (en) * 2001-05-25 2004-03-23 Ericsson Inc. Time interval based channel estimation with transmit diversity
US20030016637A1 (en) * 2001-05-25 2003-01-23 Khayrallah Ali S. Time interval based channel estimation with transmit diversity
US6999472B2 (en) * 2001-05-30 2006-02-14 Nokia Mobile Phones Limited Apparatus, and associated method, for space-time encoding, and decoding, data at a selected code rate
US20030011274A1 (en) * 2001-07-13 2003-01-16 Moteurs Leroy-Somer Discoid machine
US7236478B2 (en) * 2001-07-20 2007-06-26 Huawei Technologies Co., Ltd. Method and apparatus for down-link feedback multiple antenna transmission in wireless communication system
US6441786B1 (en) * 2001-07-20 2002-08-27 Motorola, Inc. Adaptive antenna array and method for control thereof
US20030076908A1 (en) * 2001-08-24 2003-04-24 Huang Howard C. Signal detection by a receiver in a multiple antenna time-dispersive system
US7359466B2 (en) * 2001-08-24 2008-04-15 Lucent Technologies Inc. Signal detection by a receiver in a multiple antenna time-dispersive system
US7327798B2 (en) * 2001-10-19 2008-02-05 Lg Electronics Inc. Method and apparatus for transmitting/receiving signals in multiple-input multiple-output communication system provided with plurality of antenna elements
US7095987B2 (en) * 2001-11-15 2006-08-22 Texas Instruments Incorporated Method and apparatus for received uplinked-signal based adaptive downlink diversity within a communication system
US20030108117A1 (en) * 2001-12-07 2003-06-12 Ketchum John W. Time-domain transmit and receive processing with channel eigen-mode decompositon for MIMO systems
US20030123565A1 (en) * 2001-12-12 2003-07-03 Ntt Docomo, Inc. Radio communication method and apparatus
US7227906B2 (en) * 2001-12-12 2007-06-05 Ntt Docomo, Inc. Radio communication method and apparatus for multiplex transmission of plural signals in the same frequency band
US20030112745A1 (en) * 2001-12-17 2003-06-19 Xiangyang Zhuang Method and system of operating a coded OFDM communication system
US20030123567A1 (en) * 2001-12-27 2003-07-03 Haruhiko Shigemasa Transmitter apparatus and communication system employing the same
US20030128658A1 (en) * 2002-01-08 2003-07-10 Walton Jay Rod Resource allocation for MIMO-OFDM communication systems
US20030161282A1 (en) * 2002-02-26 2003-08-28 Irina Medvedev Multiple-input, multiple-output (MIMO) systems with multiple transmission modes
US6862271B2 (en) * 2002-02-26 2005-03-01 Qualcomm Incorporated Multiple-input, multiple-output (MIMO) systems with multiple transmission modes
US20030181211A1 (en) * 2002-03-19 2003-09-25 Javad Razavilar Method and apparatus for dynamic channel selection in wireless modems
US7522673B2 (en) * 2002-04-22 2009-04-21 Regents Of The University Of Minnesota Space-time coding using estimated channel information
US6711528B2 (en) * 2002-04-22 2004-03-23 Harris Corporation Blind source separation utilizing a spatial fourth order cumulant matrix pencil
US20080095121A1 (en) * 2002-05-14 2008-04-24 Shattil Steve J Carrier interferometry networks
US6847306B2 (en) * 2002-05-17 2005-01-25 Keyvan T. Diba Emergency traffic signal attachment
US20040002364A1 (en) * 2002-05-27 2004-01-01 Olav Trikkonen Transmitting and receiving methods
US7092737B2 (en) * 2002-07-31 2006-08-15 Mitsubishi Electric Research Laboratories, Inc. MIMO systems with rate feedback and space time transmit diversity
US7593317B2 (en) * 2002-08-01 2009-09-22 Panasonic Corporation Radio base station apparatus
US20040022183A1 (en) * 2002-08-01 2004-02-05 Li Kuo Hui System and method for transmitting data in a multiple-branch transmitter-diversity orthogonal frequency-division multiplexing (OFDM) system
US7394754B2 (en) * 2002-08-01 2008-07-01 Mediatek Inc. System and method for transmitting data in a multiple-branch transmitter-diversity orthogonal frequency-division multiplexing (OFDM) system
US20040042439A1 (en) * 2002-08-27 2004-03-04 Menon Murali Paravath Beam-steering and beam-forming for wideband MIMO/MISO systems
US6940917B2 (en) * 2002-08-27 2005-09-06 Qualcomm, Incorporated Beam-steering and beam-forming for wideband MIMO/MISO systems
US7529177B2 (en) * 2002-08-28 2009-05-05 Agere Systems Inc. Dithering scheme using multiple antennas for OFDM systems
US7031669B2 (en) * 2002-09-10 2006-04-18 Cognio, Inc. Techniques for correcting for phase and amplitude offsets in a MIMO radio device
US20040066773A1 (en) * 2002-10-01 2004-04-08 Atheros Communications, Inc. Decision feedback channel estimation and pilot tracking for OFDM systems
US20040081263A1 (en) * 2002-10-24 2004-04-29 Lee King F. Method and apparatus for receiving diversity transmissions
US20040085939A1 (en) * 2002-10-25 2004-05-06 Wallace Mark S. Channel calibration for a time division duplexed communication system
US20040136349A1 (en) * 2002-10-25 2004-07-15 Walton J. Rodney MIMO system with multiple spatial multiplexing modes
US7653142B2 (en) * 2002-10-25 2010-01-26 Qualcomm Incorporated Channel estimation and spatial processing for TDD MIMO systems
US20040082356A1 (en) * 2002-10-25 2004-04-29 Walton J. Rodney MIMO WLAN system
US7324429B2 (en) * 2002-10-25 2008-01-29 Qualcomm, Incorporated Multi-mode terminal in a wireless MIMO system
US7317750B2 (en) * 2002-10-31 2008-01-08 Lot 41 Acquisition Foundation, Llc Orthogonal superposition coding for direct-sequence communications
US20040086027A1 (en) * 2002-10-31 2004-05-06 Shattil Steve J. Orthogonal superposition coding for direct-sequence communications
US7099698B2 (en) * 2002-11-04 2006-08-29 Vivato, Inc. Complementary beamforming methods and apparatuses
US20040102157A1 (en) * 2002-11-27 2004-05-27 Lewis Michael E. Wireless LAN with distributed access points for space management
US7200631B2 (en) * 2003-01-10 2007-04-03 Lucent Technologies Inc. Method and apparatus for determining an inverse square root of a given positive-definite hermitian matrix
US20040139137A1 (en) * 2003-01-10 2004-07-15 Mailaender Laurence Eugene Method and apparatus for determining an inverse square root of a given positive-definite hermitian matrix
US20040157645A1 (en) * 2003-02-12 2004-08-12 Smith Adrian David System and method of operation an array antenna in a distributed wireless communication network
US20040165675A1 (en) * 2003-02-20 2004-08-26 Nec Corporation Iterative soft interference cancellation and filtering for spectrally efficient high-speed transmission in MIMO systems
US7099678B2 (en) * 2003-04-10 2006-08-29 Ipr Licensing, Inc. System and method for transmit weight computation for vector beamforming radio communication
US7385617B2 (en) * 2003-05-07 2008-06-10 Illinois Institute Of Technology Methods for multi-user broadband wireless channel estimation
US7079870B2 (en) * 2003-06-09 2006-07-18 Ipr Licensing, Inc. Compensation techniques for group delay effects in transmit beamforming radio communication
US7110350B2 (en) * 2003-06-18 2006-09-19 University Of Florida Research Foundation, Inc. Wireless LAN compatible multi-input multi-output system
US20050017511A1 (en) * 2003-07-22 2005-01-27 Stephen Dalton Gravity air motion concept
US20050026570A1 (en) * 2003-08-02 2005-02-03 Samsung Electronics Co., Ltd. TDMA transceiver including Cartesian feedback loop circuit
US7356073B2 (en) * 2003-09-10 2008-04-08 Nokia Corporation Method and apparatus providing an advanced MIMO receiver that includes a signal-plus-residual-interference (SPRI) detector
US7742546B2 (en) * 2003-10-08 2010-06-22 Qualcomm Incorporated Receiver spatial processing for eigenmode transmission in a MIMO system
US20080031374A1 (en) * 2003-12-17 2008-02-07 Qualcomm Incorporated Broadcast transmission with spatial spreading in a multi-antenna communication system
US20050175115A1 (en) * 2003-12-17 2005-08-11 Qualcomm Incorporated Spatial spreading in a multi-antenna communication system
US20080031372A1 (en) * 2003-12-17 2008-02-07 Qualcomm Incorporated Broadcast transmission with spatial spreading in a multi-antenna communication system
US20050149320A1 (en) * 2003-12-24 2005-07-07 Matti Kajala Method for generating noise references for generalized sidelobe canceling
US20110142097A1 (en) * 2004-01-13 2011-06-16 Qualcomm Incorporated Data transmission with spatial spreading in a mimo communication system
US20050180312A1 (en) * 2004-02-18 2005-08-18 Walton J. R. Transmit diversity and spatial spreading for an OFDM-based multi-antenna communication system
US20120213181A1 (en) * 2004-02-18 2012-08-23 Walton J Rodney Transmit diversity and spatial spreading for an ofdm-based multi-antenna communication system
US20050195733A1 (en) * 2004-02-18 2005-09-08 Walton J. R. Transmit diversity and spatial spreading for an OFDM-based multi-antenna communication system
US7206354B2 (en) * 2004-02-19 2007-04-17 Qualcomm Incorporated Calibration of downlink and uplink channel responses in a wireless MIMO communication system
US7583747B1 (en) * 2004-03-31 2009-09-01 University Of Alberta Method of systematic construction of space-time constellations, system and method of transmitting space-time constellations
US7555053B2 (en) * 2004-04-14 2009-06-30 Broadcom Corporation Long training sequence for MIMO WLAN systems
US20070009059A1 (en) * 2004-06-30 2007-01-11 Wallace Mark S Efficient computation of spatial filter matrices for steering transmit diversity in a MIMO communication system
US20100074301A1 (en) * 2004-07-15 2010-03-25 Qualcomm Incorporated Unified mimo transmission and reception
US20060013250A1 (en) * 2004-07-15 2006-01-19 Howard Steven J Unified MIMO transmission and reception
US20060067421A1 (en) * 2004-09-03 2006-03-30 Qualcomm Incorporated Spatial spreading with space-time and space-frequency transmit diversity schemes for a wireless communication system
US20060050770A1 (en) * 2004-09-03 2006-03-09 Qualcomm Incorporated Receiver structures for spatial spreading with space-time or space-frequency transmit diversity
US20100169396A1 (en) * 2004-11-15 2010-07-01 Qualcomm Incorporated Efficient computation for eigenvalue decomposition and singular value decomposition of matrices
US20080095282A1 (en) * 2004-12-09 2008-04-24 Qualcomm Incorporated Data transmission with spatial spreading in a mimo communication system
US7336746B2 (en) * 2004-12-09 2008-02-26 Qualcomm Incorporated Data transmission with spatial spreading in a MIMO communication system

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8903016B2 (en) 2003-12-17 2014-12-02 Qualcomm Incorporated Spatial spreading in a multi-antenna communication system
US9787375B2 (en) 2003-12-17 2017-10-10 Qualcomm Incorporated Spatial spreading in a multi-antenna communication system
US8204149B2 (en) 2003-12-17 2012-06-19 Qualcomm Incorporated Spatial spreading in a multi-antenna communication system
US8325844B2 (en) 2004-01-13 2012-12-04 Qualcomm Incorporated Data transmission with spatial spreading in a MIMO communication system
US8169889B2 (en) 2004-02-18 2012-05-01 Qualcomm Incorporated Transmit diversity and spatial spreading for an OFDM-based multi-antenna communication system
US8520498B2 (en) 2004-02-18 2013-08-27 Qualcomm Incorporated Transmit diversity and spatial spreading for an OFDM-based multi-antenna communication system
US20050180312A1 (en) * 2004-02-18 2005-08-18 Walton J. R. Transmit diversity and spatial spreading for an OFDM-based multi-antenna communication system
US20050249174A1 (en) * 2004-05-07 2005-11-10 Qualcomm Incorporated Steering diversity for an OFDM-based multi-antenna communication system
US8923785B2 (en) 2004-05-07 2014-12-30 Qualcomm Incorporated Continuous beamforming for a MIMO-OFDM system
US8285226B2 (en) 2004-05-07 2012-10-09 Qualcomm Incorporated Steering diversity for an OFDM-based multi-antenna communication system
US8909174B2 (en) 2004-05-07 2014-12-09 Qualcomm Incorporated Continuous beamforming for a MIMO-OFDM system
US7991065B2 (en) 2004-06-30 2011-08-02 Qualcomm, Incorporated Efficient computation of spatial filter matrices for steering transmit diversity in a MIMO communication system
US20070009059A1 (en) * 2004-06-30 2007-01-11 Wallace Mark S Efficient computation of spatial filter matrices for steering transmit diversity in a MIMO communication system
US7978649B2 (en) 2004-07-15 2011-07-12 Qualcomm, Incorporated Unified MIMO transmission and reception
US8767701B2 (en) 2004-07-15 2014-07-01 Qualcomm Incorporated Unified MIMO transmission and reception
US7978778B2 (en) 2004-09-03 2011-07-12 Qualcomm, Incorporated Receiver structures for spatial spreading with space-time or space-frequency transmit diversity
US20070206686A1 (en) * 2006-01-05 2007-09-06 Vook Frederick W Method and apparatus for performing cyclic-shift diversity with beamforming
US8543070B2 (en) 2006-04-24 2013-09-24 Qualcomm Incorporated Reduced complexity beam-steered MIMO OFDM system
US8824583B2 (en) 2006-04-24 2014-09-02 Qualcomm Incorporated Reduced complexity beam-steered MIMO OFDM system
US8290089B2 (en) 2006-05-22 2012-10-16 Qualcomm Incorporated Derivation and feedback of transmit steering matrix
US20110105063A1 (en) * 2008-06-25 2011-05-05 Takashi Yamamoto Radio communication device and signal transmission method in mimo radio communication
US20110143807A1 (en) * 2009-12-14 2011-06-16 Blue Wonder Communications Gmbh Method and apparatus for data communication in lte cellular networks
US8744374B2 (en) * 2009-12-14 2014-06-03 Intel Mobile Communications Technology Dresden GmbH Method and apparatus for data communication in LTE cellular networks
US20140286384A1 (en) * 2013-03-19 2014-09-25 Fundació Centre Tecnològic De Telecomunicacions De Catalunya Method for equalizing filterbank multicarrier (fbmc)modulations
US8929495B2 (en) * 2013-03-19 2015-01-06 Fundacio Centre Technologic de Telecomunicacions de Catalunya Method for equalizing filterbank multicarrier (FBMC) modulations

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