Motorola Corporation

Agere Systems Inc.

Darryn Lowe

Xiaojing Huang

Geetha Varuni Witana

Yunxin Li

Ricardo Gandia

In one embodiment, a transmitter converts digital input data into combined-OFDM signals and a receiver recovers data from the transmitted combined-OFDM signals. For transmission, digital data is mapped into data symbols using a commonly known modulation technique, such as QAM or DQPSK. The data symbols are subsequently divided into two or more groups according to a specified grouping pattern. Each group of data symbols is then converted into a separate OFDM subsymbol using IFFT processing. The OFDM subsymbols are then combined according to a specified combining pattern to create a combined-OFDM symbol. Combined-OFDM symbols are then prepared for transmission by affixing cyclic prefixes, converting the symbols to analog format, and performing spectral shaping of the analog signal. Upsampling may be employed to increase the signal bandwidth. In alternative embodiments, OFDM subsymbols may be combined using interleaving to create an interleaved-OFDM symbol.

Orthogonal frequency division multiplexing using subsymbol processing

In one embodiment, a demapper uses two hybrid-QPSK constellations to demap pairs of equalized data symbols recovered from 16-QAM, DCM OFDM symbols, wherein the equalized data symbols in a pair correspond to the same four-bit group. A first hybrid-QPSK constellation is generated by combining the real components of both 16-QAM mapping constellations onto one coordinate plane. The demapper generates a first set of two decision variables by combining the real components of each equalized data symbol in a pair to correspond to the first hybrid-QPSK coordinate plane. A log-likelihood ratio is then calculated for both decision variables in the set to determine likelihood estimates for the first and second bits of the four-bit group. This process is repeated for the imaginary components of each corresponding pair of equalized data symbols to generate likelihood estimates for the third and fourth bits of the four-bit group.

Demodulation of 16-QAM, DCM data symbols using two hybrid-QPSK constellations

A method and system for interactive channel equalization uses channel status information included in data packets. The system includes a first station adapted to transmit a first data packet including a channel status information segment over a radio communication channel as a first signal. A second station in the system includes a static pre-equalizer and an adaptive equalizer. The second station is adapted to receive the first signal and adaptively equalize the first signal using the adaptive equalizer and the channel status information to create a post hoc status estimate of the channel. The second station is further adapted to transmit a second data packet over the channel as a second signal, where the second signal is pre-equalized by the pre-equalizer using the post hoc status estimate of the channel. The method and system thus enable parameters of the channel equalization to be adjusted in real-time in response to varying channel conditions.

Method and system for interactive channel equalization

A method of avoiding deadlock during managing storage of items in a network () of heterogeneous storage devices (). The method firstly detects () a storage event. Detection is effected by the local storage device and then the method obtains input information () having parameter values related to the item and the heterogeneous storage devices (). The method then processes () the input information to determine a storage assignment, for storage of the item on one or more of the heterogeneous storage devices (). The assignment is based on item-device suitability determined from a combination of at least one item selection rule and rules preventing deadlock.

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Helensburgh, Australia

Darryn Lowe