Radio communication apparatus and method

Abstract

Time range spreaders (102-1 to 102-N) are used to spread, along the time axis, data that have been parallel converted by an S / P section (101). A rearranging unit (103) is used to shift the spread chip stepwise in the upward or downward direction of the carrier frequency to rearrange them along the frequency axis. In this way, a piece of data is divided along the frequency and time axes and arranged in a two-dimensional manner.

Description

technical field [0001] The present invention relates to a wireless communication device and a wireless communication method used in a digital communication system, in particular to multi-carrier modulation methods such as OFDM (Orthogonal Frequency Division Multipexing: Orthogonal Frequency Division Multiplexing) modulation methods and CDMA (Code Division Multiple Access: A wireless communication device and a wireless communication method that perform wireless communication by combining code division multiple access) methods. Background technique [0002] In recent years, in wireless communication, especially mobile communication, various kinds of information such as images and data are targeted for transmission in addition to voice. It can be expected that the demand for transmission of various contents will increase in the future, so the necessity for highly reliable and high-speed transmission will further increase. However, in the case of high-s...

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Problems solved by technology

[0013] However, in the time domain extension method, if one focuses on a certain digital symbol, then since the expanded chips become time-sequentially arranged in the same frequency ( figure 2 and image 3 ), so the path diversity effect of multipath separation can be obtained, but the frequency diversity effect cannot be obtained

[0014] Therefore, when the transmission power control corresponding to the radio channel condition is incomplete, the transmission characteristic is severely deteriorated.

In addition, even when the transmission power control is fully performed, the transmission power is increased based on this control, but there are problems such as increased battery consumption of the mobile station device, increased amplifier size, and increased interference with other cells.

[0015] In the frequency domain extension method, if one focuses on a certain digital symbol, since a plurality of extended chips are arranged in different subcarriers at the same time ( Figure 4 and Figure 5 ), so the frequency diversity effect can be obtained, but the path separation cannot be performed and the path diversity effect cannot be obtained

[0016] Therefore, multipath distortion cannot be reduced since RAKE combining is not possible

In the case of code-division-multiplexing signals of multiple users in each subcarrier, even if orthogonal codes are used in spreading processing, the orthogonality cannot be maintained due to the influence of multipath distortion, so the code-division multiplexing number is limited

In addition, the influence of a shift in signal cutting timing at the time of Fourier transform increases

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