Orange

France Telecom

Intel Mobile Communications Gmbh

Virata Corporation

Dirk Slock

Julie Yuan-Wu

Mustapha Amara

Debajyoti Pal

Francesco Negro

Irfan Ghauri

A multi-stream transmission method and device are provided for transmitting N data streams allocated to K different users. The method is implemented by a transmitter for a multi-user MIMO system having Ntransmit antennas and receive antennas associated with K receivers respectively associated with the K users. The method includes: performing a succession of two different iterative algorithms for calculating K precoding matrices of a linear precoder and K decoding matrices of a receiver, the receiver being of the normalized MF type with a Frobenius norm for the first algorithm, and the second iterative algorithm being initialized by a value output by the first iterative algorithm; and before each calculation of precoding matrices, calculating weights for weighting all of the streams.

Double-iterative method of transmitting multiple streams per user in a multi-user MIMO system, and a corresponding transmitter, computer program product, and data medium

A method and apparatus for simultaneously transmitting K data streams allocated respectively to K different users. The method is implemented by a transmitter for a multi-user MIMO system having Ntransmit antennas and receive antennas associated with K receivers, each associated with a respective user. The method includes, per data stream, at least: jointly calculating a linear pre-coder and a receiver adapted for a multi-user MIMO system using two different iterative algorithms in succession, wherein the second iterative algorithm is initialized with the output value from the first iterative algorithm.

Method of transmitting a signal for a multi-user MIMO system, and corresponding transmitter, computer program product, and data medium

A method, system, and apparatus is provided for interference calibration. A second mobile terminal may be configured to send timing information to a network interface in an uplink channel of a second communication system. The network interface may be configured to communicate with a first mobile terminal in a downlink channel in a first communication system; estimate the uplink channel using the timing information to form a channel estimation; and adjust the downlink channel to the first mobile terminal using the channel estimation.

Macro-femto inter-cell interference mitigation

The present invention, generally speaking, accelerates convergence of a fast RLS adaptation algorithm by, following processing of a burst of data, performing postprocessing to remove the effects of prewindowing, fictitious data initialization, or both. This postprocessing is part of a burst mode adaptation strategy in which data (signals) get processed in chunks (bursts). Such a burst mode processing approach is applicable whenever the continuous adaptation of the filter is not possible (algorithmic complexity too high to run in real time) or not required (optimal filter setting varies only slowly with time). Postprocessing consists of a series of &ldquo;downdating&rdquo; operations (as opposed to updating) that in effect advance the beginning point of the data window. The beginning point is advanced beyond fictitious data used for initialization and beyond a prewindowing region. In other variations, downdating is applied to data within a prewindowing region only. The forgetting factor of conventional algorithms can be eliminated entirely. Performance equivalent to that of GWC RLS algorithms is achieved at substantially lower computational cost. In particular, a postprocessing Fast Kalman Algorithm in effect transforms an initialized/prewindowed least squares estimate into a Covariance Window least squares estimate. Various further refinements are possible. Initialization may be cancelled completely or only partially. For example, in order to reduce the dynamic range of algorithmic quantities, it may be advantageous to, in a subsequent initialization, add an increment to a forward error energy quantity calculated during a previous burst. Postprocessing may then be performed to cancel only the added increment. Also, to reduce the usual large startup error transient, the desired response data can be modified in a way that dampens the error transient. The modified desired response data are saved for use in later postprocessing. Furthermore, to allow for more rapid adaptation without the use of an exponential forgetting factor, a weighting factor less than one may be applied to the forward error energy quantity during initialization from one burst to the next. This allows for the most efficient use of data but limited adaptation within a burst, but more rapid adaptation from one burst to the next.

Growing community of inventors

Vallauris, France

Dirk Slock