A METHOD AND APPARATUS FOR THE PAPR REDUCTION OF THE OFDM SYSTEM BY THE CORRELATION OF INFORMATION DATA

摘要

An object of the present invention is to lower the correlation of the input information data, an orthogonal frequency division multiplexing (correlation reduction OFDM (orthogonal frequency division multiplexing): hereinafter referred to as "CR-OFDM") invented a system, several in the conventional OFDM system high peak power to average power ratio (peak-to-average power ratio: hereinafter referred to as "PAPR") represented by the sub-carriers by lowering the data transmission to enable more efficient data transmission. In addition, the present invention is to solve the disadvantages of the required performance of the additional information transmitted by using the increase and the additional channel of the system complexity and the computational complexity may appear at PTS (partial transmit sequence) and SLM (selective mapping) method or DSI (dummy sequence insertion) techniques It is intended.; CR-OFDM system proposed in the present invention is basically self-correlation of the information data to be input help to see that there is a close relationship between the PAPR with the signal after the IFFT (inverse fast Fourier transform) transform, self-correlation of the input information data also by lowering the lowering the PAPR of the output signal. An OFDM system when the self-correlation is '0', the signal is input as in the complementary sequences reduces the PAPR of the output signal greatly, the high self-correlation signal, and in particular [1, 1,. . . , 1, 1], [-1, -1. . . , -1, -1, 1, -1. . . , 1, -1] or [-1, 1,. . . , -1, After 1] and the correlation maximum of the signal between the input contacting portions Sequence type PAPR of the output signal will have a maximum value. It is as an example danjeokin showing the close relationship between the autocorrelation help output signal of the input information data PAPR, therefore lowering the correlation of the input information data soon lower the PAPR of the output signal. It proposed two methods in the present study as a way to reduce this correlation, and to the Method1 and Method2, respectively la.; As for the first method proposed Method1 is a method which lowers the correlation between the minimum unit of part of the parallel input sequence of data sequence, that the vicinity of the sequence consisting of 2 bit. To this Method1 is 3 bit divided by the input data and the input to each sub-block, each sub-block is an insert new dummy bit obtained by joham data of the inputted 3 bit by its correlation is '0', 4 and it outputs the bit data. By inputting the output derived from each sub-block as the data sequence into the IFFT IFFT input stage can not be the signal having the maximum absolute correlation. This method gave only because the correlation between the portions of the minimum unit in which the input data sequence a sequence diagram lowering method, it is difficult to expect much of a PAPR reduction effect. However, information data to the inserted dummy bit is not used for data decompression at the receiving end reduce the standing, PAPR do not require a separate side information channel, the system entirety using only one IFFT by the system complexity also not significantly increased It has the advantage that it can be.; Two Method2 As a second example, a lot of correlation than that by dividing the input data sequence to obtain the effect of reducing by half the parent sequence undergoes the same process as the previous Method1, sub-sequence is the upper sequence information a dummy bit is inserted for the proposed method the data and the logical combination is inserted into a dummy bit. These methods are to lower the correlation between the partial sequence of the smallest unit in which the input data sequence as well as the correlation between the partial sequence of up unit also gives also lowered. It can be expected better PAPR reduction because any more than Method1 also given consideration to the relationship, it is also difficult to expect a correlation only considering the results so large PAPR Reduction for only two kinds of units. But like Method1, without the need for a separate additional information channel, it has the advantage that the entire system using only one IFFT by without the system complexity also been greatly increased, to reduce the PAPR.; After a method using a correlation of input information data proposed in the present study, although PAPR reduction performance is not very large, but will be seen, a large increase in system complexity and complexity traditional PAPR reduction techniques have with the additional information (side information) transmission it can complement the various disadvantages can be called a more efficient data transfer is possible and the system will be able to expect a larger PAPR reduction performance by considering more self-correlation of the input data.