Lucent Technologies Inc.

Alcatel-lucent USA Inc.

Alcatel Lucent

Agere Systems Guardian Corp.

Laurence Eugene Mailaender

Howard C Huang

Sivarama Krishnan Venkatesan

Erik E Anderlind

Giovanni Vannucci

Harish Viswanathan

Richard Dennis Gitlin

Francis Dominique

Michael J Gans

Reinaldo A Valenzuela

Yu S Yeh

Constantinos B Papadias

Jack Salz

Magnus Sandell

Francis Joseph Mullany

Reza Mardani

Graeme Kenneth Woodward

Michael James Gans

Yu-Shuan Yeh

Constantinos Basil Papadias

In an embodiment of the method, at least one signal-to-interference-and-noise ratio (SINR) for each antenna configuration in a set of transmission antenna configurations is determined based on an estimated channel characteristic. At least one received signal characteristic is determined for each antenna configuration in the set of antenna configurations based on the determined signal-to-interference-and-noise ratios. One of the antenna configurations in the set of antenna configurations is selected based on the determined received signal characteristics.

Method of determining at least one transmit mode parameter for a multiple-input multiple-output system

A receiver device for use in a wireless communication system () includes a rake receiver () and an equalizer receiver (). A controller () selects one of the rake receiver () or the equalizer receiver () for processing a received signal. In some situations, the rake receiver () will provide better performance. In other situations, the equalizer receiver () will provide better performance. One embodiment includes a plurality of equalizers (A,B). One of the equalizers processes a data packet from a received signal while another one of the equalizers trains for processing a signal from a subsequent scheduled user. Another example embodiment includes controlling an equalizer length based on a delay span or another selected channel metric.

Receiver techniques for wireless communication

Communications facilitate locating a mobile station () using the radio frequency spectrum typically used for cellular communications. A first locating signal is communicated between a base station transceiver () and a mobile station () and includes information regarding the location of the signal source. A plurality of second locating signals are communicated between a corresponding plurality of ranging beacon devices () and a mobile station () and each includes information regarding the location of the ranging beacon devices (). The first and second signals allow for determining the location of the mobile station (). In a disclosed example, the first and second signals are simultaneously transmitted by the base station () and the plurality of ranging beacon devices (), respectively.

Facilitating mobile station location using a ground-based cellular network

The method of receiver processing of CDMA signals in a CDMA system includes first converting a received signal in the time domain to a received signal in the frequency domain, and equalizing the received signal in the frequency domain using a set of frequency domain weights. The equalized received signal in the frequency domain is converted to an equalized received signal in the time domain. The set of frequency domain weights are adaptively adjusted at a symbol rate of the received signal in the time domain based on an error signal produced from the received signal in the frequency domain and a frequency domain representation of a known pilot signal of the CDMA system.

Method of receiver processing of CDMA signals in a CDMA system

In a MIMO system the bit error rate floor caused by time dispersion is reduced by employing a joint minimum mean square error (MMSE) equalizer for all of the respective transmit antenna&#x2014;receive antenna pairings that are possible in the MIMO system. The resulting joint equalization compensates not only for the impact of the channel on the transmit antenna&#x2014;receive antenna pairings but also for the interference of the other transmit antennas on any given receive antenna. The joint equalization outperforms simply replicating the prior art minimum mean square error (MMSE) equalizer for each transmit antenna&#x2014;receive antenna pairings.

Signal detection by a receiver in a multiple antenna time-dispersive system

Generally, a method and apparatus are provided for computing a matrix inverse square root of a given positive-definite Hermitian matrix, K. The disclosed technique for computing an inverse square root of a matrix may be implemented, for example, by the noise whitener of a MIMO receiver. Conventional noise whitening algorithms whiten a non-white vector, X, by applying a matrix, Q, to X, such that the resulting vector, Y, equal to Q&#xb7;X, is a white vector. Thus, the noise whitening algorithms attempt to identify a matrix, Q, that when multiplied by the non-white vector, will convert the vector to a white vector. The disclosed iterative algorithm determines the matrix, Q, given the covariance matrix, K. The disclosed matrix inverse square root determination process initially establishes an initial matrix, Q, by multiplying an identity matrix by a scalar value and then continues to iterate and compute another value of the matrix, Q, until a convergence threshold is satisfied. The disclosed iterative algorithm only requires multiplication and addition operations and allows incremental updates when the covariance matrix, K, changes.

Method and apparatus for determining an inverse square root of a given positive-definite hermitian matrix

A receiver, system, and method for performing equalization. The receiver includes a multi-channel chip equalizer for receiving a plurality of receive baseband signals and restoring chip pulse shapes of a plurality of transmit baseband signals transmitted by a plurality of transmit antenna to produce a plurality of equalized output streams and a correlator for correlating the plurality of equalized output streams with a correlation signal to reduce gradient noise in the plurality of equalized output streams. The method of equalizing includes receiving a plurality of receive baseband signals and restoring chip pulse shapes of a plurality of transmit baseband signals transmitted by a plurality of transmit antenna to produce a plurality of equalized output streams and correlating the plurality of equalized output streams with a correlation signal to reduce gradient noise in the plurality of equalized output streams.

Equalizer and method for performing equalization in a wireless communications system

In order to transmit variable length encoded data in low signal to noise ratio environments, a first data pattern is added to a beginning portion of encoded data to signify a beginning of the encoded data. Further, a second data pattern is added to end portion of the encoded data to signify and end of the encoded data. Additionally, since the encoded data may naturally include the second data pattern and thereby mistakenly indicate an end of the encoded data, the encoded data is first checked for such a pattern. If the pattern is found within the encoded data, a new pattern is substituted therefore. In order to counter errors, patterns similar to the first data pattern are also substituted with new patterns. As such, a variable length encoded data can be transmitted in a low signal to noise ratio environment, and can thereafter be easily decoded.

Method and apparatus for enabling transmission of variable length encoded data in a low signal to noise ratio environment

An apparatus and method for performing interference cancellation by dividing a signal for K users, where K>1, into N time segments, where N>1; successively canceling interference for each of the N segments to produce K user symbols, where the cancellation is performed for each of the N segments independent of any other segment; and combining the K user symbols into a stream of successive data bits.

Interference canceller

A system, a transceiver, and methods for code division multiple access (CDMA) communication. The system includes first and second code division multiple access transceivers. The first code division multiple access transceiver has a plurality antennas disposed to provide transmission via a plurality of paths and the second code division multiple access transceiver has a rake arrangement for processing a plurality of signals received at the rake arrangement with differing delays or other characteristics. A driving arrangement is provided for causing the first code division multiple access transceiver to use a relative few, e.g., one, of the plurality of antennas. When, however, an indication is obtained that an adequate number of resolvable signals are likely not received at the rake arrangement of the second transceiver, a circuit switches the driving arrangement to cause the first transceiver to use more of the plurality of antennas. In one implementation, the second transceiver sends a feedback signal indicating the number of useful signals being received and the first transceiver responds to the feedback signal by selecting and using a desirable number of transmit antennas. In an implementation suitable for a time-division duplexing (TDD) communication system, the first transceiver obtains the indication by inference from the fact that it is not receiving an adequate plurality of resolvable signals from the second transceiver. When the first transceiver obtains the indication, it drives the increased number of antennas either with respective delays or with different codes of the CDMA type.

Code division multiple access communication with enhanced multipath diversity

A CDMA communication system is disclosed offering a near continuum of data rates up to a maximum rate. The disclosed CDMA communication system increases the data rate variability, without disturbing the orthogonality between users. An increased number of data rates is obtained by time multiplexing the data rates achievable with conventional CDMA systems to provide additional data rates for various multimedia applications. If a user is assigned a specific orthogonal code sequence, such as a Walsh sequence, which permits a maximum data rate, nR, with conventional systems, the user can obtain additional desired data rates up to the maximum rate nR, by time multiplexing the specific orthogonal code set. Desired bit rates are achievable for applications requiring bit rates that are not an integer multiple of the rates provided by conventional techniques. A fundamental rate of R or &ldquo;fat pipe&rdquo; rates of powers-of-two multiples of the fundamental rate can be achieved in a conventional manner. A desired rate up to the maximum &ldquo;fat pipe&rdquo; rate is achieved by time multiplexing the codes w to achieve rates between R and nR, where w , denotes the first nth of the spread spectrum code w . The transmitter of the present invention achieves a rate conversion to match the appropriate codeword to the appropriate data rate, by employing buffering and reclocking of the data, with time multiplexing of the orthogonal Walsh codes corresponding to the available lower and upper rates. The rate conversion must be synchronized with the selection of the orthogonal Walsh code (corresponding to the lower and upper rates).

Method and apparatus for achieving data rate variability in orthogonal spread spectrum communication systems

Linear space-time multiuser detectors are described that combine array processing, rake detection, and multiuser detection and that satisfy a minimum mean-squared error criteria. Both embodiments can be implemented adaptively so as to account for unknown sources of interference. The adaptive implementation of the first embodiment of a linear space-time detector requires explicit estimates of the channel coefficients. On the other hand, the adaptive implementation of the second embodiment does not require these estimates since they can be adaptively obtained. Both of these detectors provide significant performance advantages over single-user space-time detectors and over multiuser detectors which do not account for CDMA interference from unknown sources.

Detectors for CDMA systems

A method and apparatus for increasing system capacity in a mixed-rate wireless communication are disclosed. Improvements are obtained using multiuser detection or antenna array processing techniques or both to explicitly cancel or attenuate only the high power users. Multiuser detection may be combined with antenna array processing to recover capacity appropriated by the high-power users. By mitigating the interference effects of only the high-powered users, the computational burden is manageable. An antenna array algorithm or a multiuser detection algorithm or both, are applied only to n high rate users (n<k total users). In an antenna array processing implementation, fewer antennas may be employed (one for each high-rate user). In a multiuser detection implementation, fewer cancellation stages may be employed (one for each high-rate user).

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Hoboken, NJ, United States of America

Laurence Eugene Mailaender