Sanyo Electric Co., Ltd.

Hera Wireless S.a.

Ntt Data Sanyo System Corporation

Ntt Data Sanyo Systems Corporation

Nobuo Higashida

Seigo Nakao

Yasuhiro Tanaka

A storage unit stores a preamble signal defined in a legacy system and a preamble signal defined in a MIMO system. A monitoring unit in a transmitting apparatus monitors the existence of any communication apparatus which is not compatible with the MIMO system but accepts the legacy system. A channel characteristics acquiring unit derives the characteristics of a radio channel between the transmitting apparatus and a receiving apparatus. A selector selects a packet format based on a monitoring result obtained by the monitoring unit. The selector also selects where to place LTS, based on the characteristics of wireless channel derived by the channel characteristics acquiring unit.

Method and apparatus for transmitting signals

Method and apparatus for transmitting signals, and method and apparatus for receiving the signals

Method and apparatus for transmitting signals for multiple input multiple output wireless communication system

A frequency offset correcting unit estimates frequency offsets in a preamble period, corrects digital received signals by the estimated initial frequency and further corrects them by residual frequency signals. A receiving weight vector computing unit computes receiving weight vector signals by using LMS algorithm. Based on the error vectors or receiving weight vector signals derived by LMS algorithm, the frequency offsets contained in corrected received signals are also estimated and are outputted as the residual frequency signals. A multiplier weights the corrected received signals with the receiving weight vector signals. An adder sums up outputs of the multiplier so as to output a synthesized signal.

Frequency offset estimating method and frequency offset correcting apparatus utilizing said method

An A-D conversion unit performs analog-to-digital conversions on baseband signals. A correlation processing unit carries out a correlation processing. A power computing unit computes the power of correlation values. An inter-signal condition determining unit compares a relationship between the peak of a main signal and the peak of sub-signals to a first condition, and excludes, from combining diversity, baseband signals corresponding to the sub-signals if the relationship does not satisfy the first condition. An intra-signal condition determining unitcompares the main signals and sub-signals to a second condition, respectively, and excludes signals from combining diversity if the signals do not satisfy the second condition. A timing adjusting unit adjusts the timing of sub-signals so that the timing thereof comes close to the timing of the main signal. A shift unit shifts the timing of sampled signals corresponding to the sub-signals.

Timing-adjusting method and apparatus, and diversity receiving method and apparatus

A measuring unit selects as a representative signal a signal whose received power is the largest among digital received signals in a training signal period, and regards the remaining signals as signals to be processed. Based on a representative notifying signal, a classification unit rearranges the orders of digital received signals after the end of a training signal period. In a synthesizing unit, a multiplier weights the digital received signals with receiving weight vector signals so as to generate multiplication signals which will be summed up in an adder. A receiving weight vector signal computing unit computes receiving weight vector signals by using an adaptive algorithm, over the training signal period of time. After the end of a training signal period, the receiving weight vector signals are updated based on the multiplication signals.

Receiving method and receiving apparatus

An antenna selector selects one antenna during an interval of control signal. A receiving weight vector computing unit computes receiving weight vectors. During an interval of data signal, a multiplier in a signal processing unit weights digital received signals with the receiving weight vectors so as to output composite signals. During an interval of control signal, a switch selects an output signal from the antenna selector as an output signal from a signal processing unit whereas during the interval of data signal it selects the composite signal. A carrier control unit outputs carrier recovered by a carrier recovery unit. A multiplier in a modem unit multiplies signal-processing-output-unit signals by signals from the carrier control unit.

Growing community of inventors

Moriguchi, Japan

Nobuo Higashida