Kabushiki Kaisha Toshiba

Bae Systems, Inc.

Steve Carl Jamieson Parker

Darren McNamara

Magnus Stig Torsten Sandell

Justin Coon

Phillip Langley Salter

MIMO UWB Communications apparatus is configured to send out a channel estimation sequence comprising a plurality of sequentially transmitted symbols in accordance with a first band hopping sequence, sent from one antenna of the apparatus, while another antenna is transmitting another sequence of channel estimation symbols in accordance with another, complementary band hopping sequence. A legacy device will be capable of synchronizing with the channel estimation symbols sent in accordance with the first band hopping sequence, while a MIMO receiver will be able to determine channel estimates for all MIMO channels on the basis of the combined channel estimation transmissions.

Wireless communications apparatus

The present invention relates to estimating and correcting for frequency offset errors in wireless receivers, and is particularly but not exclusively related to MIMO WLAN applications. The present invention provides an improved method of tracking receiver frequency offsets in a receiver for MIMO systems. These receiver based frequency offset components are caused by errors or inaccuracies in various receiver sub-systems such as phase lock loops or carrier frequency oscillator error, and sampling clock rate errors. The frequency offsets due to each of a number of receiver sub-systems are estimated by monitoring frequency offsets on a number of channels or subcarriers (such as OFDM pilot channels) on different frequencies. These channel frequency offsets are preferably estimated by detecting the phase rotation between adjacent pilot symbols on each respective channel. They are then weighted according to a quality parameter of the estimates, which corresponds to their accuracy. An example of a quality parameter is the effective SNR of the respective channels, or preferably the error variance of the phase rotation. In an embodiment the quality parameter is or is proportional to &#x2225;Hx&#x2225;. The weighted channel frequency offsets are then used to determine one or more receiver sub-system frequency offset components. For example a least squares line fit analysis can be performed.

Frequency offset tracking

The invention provides a system for implementing a high capacity MIMO system with high throughput which will ensure an eigenmode rich channel largely irrespective of the environment. In conventional MIMO systems, the environment can substantially reduce the theoretically achievable throughput if there is little angular diversity. The system includes a scattering structure for scattering beams emitted by an antenna array to provide good angular diversity at the receiver and hence good throughput in all environments. In addition, the scattering structure is controllable to allow its properties and hence the eigenmodes generated to be varied to maximise the efficiency of the system.

Method and apparatus for increasing the number of strong eigenmodes in a multiple-input multiple-output (MIMO) radio channel

The signal to noise ratio in non-destructive testing or evaluation of a sample (,) by in phase stepped optical inspection systems such as the optical shearography system using a shearing interferometer involves production of correlated speckle images successively stepped in phase by illuminating with coherent radiation a sample in an unstressed state, illuminating the sample with coherent radiation, stressing it incrementally at predetermined stress increments, and generating and capturing correlated speckle images successively stepped in phase of the incrementally stressed sample at the predetermined stress increments, using the phase stepped speckle images of the unstressed and incrementally stressed sample to calculate the phase before and after stressing and differencing the images to extract the incremental phase change, inspecting the magnitude and sign of each incremental phase change and if the phase difference between successive measurements increases by more than &pgr; subtracting 2 &pgr; from the measurement value or if the phase difference between successive measurements decreases by more than &pgr; adding 2 &pgr; to the measurement value, and calculating the phase at each point in each speckle image by summing the nearest neighbour phase differences in the image that are weighted by the square of their respective modulations, where the modulation is a measure of intensity variation with phase variation and normalising the result of this calculation by dividing by the sum of the modulations.

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Bristol, United Kingdom

Steve Carl Jamieson Parker