CN101521650B - Binary phase-shift keying/orthogonal frequency division multiplexing system based on Haar wavelet transformation - Google Patents

Abstract

The invention relates to a wireless communication system, in particular to a binary phase-shift keying/orthogonal frequency division multiplexing system based on Haar wavelet transformation. To a certain extent, the invention overcomes the defects of the prior OFDM system which has a higher peak to average power ratio and is greatly influenced by frequency offset. The invention comprises a launching process: an input signal is converted by a first serial-parallel conversion module and input to a BPSK data modulator to be modulated; the modulated signal passes through a Haar wavelet forward transform module and is input to an IFFT converter; and the signal converted by the IFFT converter is input to the first parallel-serial conversion module, converted by the parallel-serial conversion module, inserted in a circulating prefix and launched by a channel. The invention also comprises a receiving process: the received signal is converted by a second serial-parallel conversion module and transferred to an FFT converter after being removed of the circulating prefix, transferred to a Haar wavelet inverse transform module after being converted by the FFT converter, and demodulated by a BPSK data demodulator, and the demodulated signal is input to a second parallel-serial conversion module and converted to obtain serial signal output.

Description

Binary phase-shift keying/orthogonal frequency division multiplexing system based on the Haar wavelet transformation

Technical field

The present invention relates to a kind of wireless communication system.

Background technology

OFDM (orthogonal frequency division multiplexi) is because advantages such as its frequency efficiency height, support high speed data transfer, the asymmetric wireless data service of support more and more are subjected to people's attention.OFDM has become the core technology of next generation wireless communication system (IEEE 802.11a, IEEE 802.11g).But owing to there are a plurality of orthogonal sub-carriers, and its output signal is the stack of a plurality of sub-channel signals, therefore compares with single-carrier system, mainly has following shortcoming: 1, have higher peak-to-average power ratio in the ofdm system.Compare with single-carrier system, because multicarrier modulation system output is the stack of a plurality of sub-channel signals, when therefore if the phase place of a plurality of signals is consistent, the instantaneous power of resulting superposed signal will be far longer than the average power of signal, causes occurring bigger peak-to-average power than (PAPR).Therefore, linearity to amplifier in the transmitter has just proposed very high requirement, if the dynamic range of amplifier can not satisfy the variation of signal, to bring distortion for signal, the frequency spectrum of superposed signal is changed, thereby cause the orthogonality between each sub-channel signal to be destroyed, produce the phase mutual interference, make system performance degradation.2, be subjected to the influence of frequency shift (FS) bigger.Because the frequency spectrum of subchannel covers mutually, this has just proposed strict requirement to the orthogonality between them, yet because there is time variation in wireless channel, the frequency shift (FS) of wireless signal can appear in transmission course, Doppler frequency shift for example, perhaps because the frequency departure that exists between transmitter carrier frequency and the receiver local oscillator, the capital makes that the orthogonality between the ofdm system subcarrier is destroyed, thereby cause the signal phase mutual interference (ICI) between subchannel, ofdm system is to the frequency departure sensitivity.

Summary of the invention

There is higher peak-to-average power ratio in the present invention, is subjected to the bigger shortcoming of influence of frequency shift (FS) in order to solve prior OFDM system, thereby proposes a kind of binary phase-shift keying/orthogonal frequency division multiplexing system based on the Haar wavelet transformation.

Binary phase-shift keying/orthogonal frequency division multiplexing system based on the Haar wavelet transformation, it comprises the insertion control module of the first serial/parallel modular converter, BPSK data modulator, IFFT converter, the first parallel/serial modular converter, Cyclic Prefix, removal control module, the second serial/parallel modular converter, FFT converter, BPSK data demodulator and the second parallel/serial modular converter of Cyclic Prefix, and it also comprises Haar small echo direct transform module and Haar inverse wavelet transform module;

The signal of input obtains parallel signal after the first serial/parallel modular converter conversion, described parallel signal inputs to the BPSK data modulator and modulates, signal after obtaining to modulate, signal after the described modulation inputs to Haar small echo direct transform module and carries out data decomposition, obtain decomposed data, described decomposed data inputs to the IFFT converter, after the conversion of IFFT converter, input to the first parallel/serial modular converter, after the first parallel/serial modular converter conversion, obtain serial signal, described serial signal inputs to the insertion control module of Cyclic Prefix and inserts Cyclic Prefix, and passes through channels transmit; The removal module that will input to Cyclic Prefix from the signal that channel receives is removed Cyclic Prefix, to remove then and obtain parallel signal after signal behind the Cyclic Prefix inputs to the second serial/parallel modular converter conversion, described parallel signal transfers to and transfers to Haar inverse wavelet transform module after the conversion of FFT converter and synthesize, data after obtaining to synthesize, data after described synthesizing input to the BPSK data demodulator and carry out demodulation, signal after the acquisition demodulation, the signal after the described demodulation input to the second parallel/serial modular converter and are converted to serial signal output.

Beneficial effect: the data after the Haar of utilization wavelet transformation of the present invention is modulated the BPSK data modulator are compressed, the subcarrier of the actual transmission of system is 1/2 of a prior OFDM system, therefore compare the prior OFDM system peak-to-average power ratio 3dB that descended, thereby overcome the defective that there is higher peak-to-average power ratio in existing ofdm system; System of the present invention error-resilient performance gains than the maximum 3dB that improve of prior OFDM system; And system of the present invention has only transmitted the subcarrier of half, therefore is subjected to the influence of frequency shift (FS) less with respect to prior OFDM system.

Description of drawings

Fig. 1 is the structural representation of system of the present invention; Fig. 2 is the symbolic number of system of the present invention and the graph of a relation of the actual sub-carrier number that uses (wherein abscissa is the symbolic number of system of the present invention input, and ordinate is the sub-carrier number of actual use); Fig. 3 is that (wherein abscissa is a signal to noise ratio with existing ofdm system performance comparison figure under the white Gaussian noise channel in system of the present invention, ordinate is the error rate, curve 47 does not detect error-resilient performance curve when not using subcarrier for the receiving terminal of system of the present invention, curve 48 is the error-resilient performance curve of existing ofdm system, and curve 49 is that system receiving terminal of the present invention correctly detects the error-resilient performance curve when not using subcarrier); Fig. 4 is that (wherein abscissa is a signal to noise ratio with prior OFDM system performance comparison figure under frequency selective fading channels in system of the present invention, ordinate is the error rate, curve 50 does not detect error-resilient performance curve when not using subcarrier for the receiving terminal of system of the present invention, curve 51 is the error-resilient performance curve of existing ofdm system, and curve 52 correctly detects error-resilient performance curve when not using subcarrier for the receiving terminal of system of the present invention).

Embodiment

Embodiment one: this embodiment is described in conjunction with Fig. 1, binary phase-shift keying/orthogonal frequency division multiplexing system based on the Haar wavelet transformation, it comprises the insertion control module 6 of the first serial/parallel modular converter 1, BPSK data modulator 2, IFFT converter 4, the first parallel/serial modular converter 5, Cyclic Prefix, removal control module 8, the second serial/parallel modular converter 9, FFT converter 10, BPSK data demodulator 12 and the second parallel/serial modular converter 13 of Cyclic Prefix, and it also comprises Haar small echo direct transform module 3 and Haar inverse wavelet transform module 11;

The signal of input obtains parallel signal after first serial/parallel modular converter 1 conversion, described parallel signal inputs to BPSK data modulator 2 and modulates, signal after obtaining to modulate, signal after the described modulation inputs to Haar small echo direct transform module 3 and carries out data decomposition, obtain decomposed data, described decomposed data inputs to IFFT converter 4, after 4 conversion of IFFT converter, input to the first parallel/serial modular converter 5, after first parallel/serial modular converter 5 conversions, obtain serial signal, described serial signal inputs to the insertion control module 6 of Cyclic Prefix and inserts Cyclic Prefix, and passes through channels transmit;

The removal module 8 that will input to Cyclic Prefix from the signal that channel receives is removed Cyclic Prefix, to remove then and obtain parallel signal after signal behind the Cyclic Prefix inputs to second serial/parallel modular converter 9 conversions, described parallel signal transfers to and transfers to Haar inverse wavelet transform module 11 after 10 conversion of FFT converter and synthesize, data after obtaining to synthesize, data after described synthesizing input to BPSK data demodulator 12 and carry out demodulation, signal after the acquisition demodulation, the signal after the described demodulation input to the second parallel/serial modular converter 13 and are converted to serial signal output.

Operation principle: the present invention utilizes the Haar wavelet transformation, and the output signal of BPSK digital modulator (this signal span be { 1 ,-1}, and be capable 1 row of N, N is a sub-carrier number) is carried out data decomposition; The decomposed data span is Wherein 0 number is

Individual.Decomposed data is sent into the IFFT converter, because the subcarrier of 0 signal correspondence do not send, so the actual carrier number that sends is

Individual, the average power of establishing the OFDM emission is

Signal peak is A _OFDMThe average power of system of the present invention emission is

System signal peak value of the present invention is A _DWT/OFDMIf the transmitting power of two kinds of systems is identical, then have following formula to set up:

${\stackrel{\‾}{P}}_{\mathrm{DWT}/\mathrm{OFDM}}={\stackrel{\‾}{P}}_{\mathrm{OFDM}}$

Because system of the present invention has only transmitted

Individual subcarrier, and the amplitude on each subcarrier is OFDM's

Doubly, so have:

$\frac{A_{\mathrm{DWT}/\mathrm{OFDM}}}{A_{\mathrm{OFDM}}}\text{=}\frac{\sqrt{2}\×\frac{N}{2}}{N}=\frac{\sqrt{2}}{2};$

${\left(\frac{A_{\mathrm{DWT}/\mathrm{OFDM}}}{A_{\mathrm{OFDM}}}\right)}^2=\frac{1}{2};$

The peak power that is system of the present invention is for having ofdm system now

So the peak-to-average power of system of the present invention than (PAPR) with respect to the prior OFDM system 10log that descended ₁₀2=3dB, thus overcome the defective of higher peak-to-average power ratio of existing of prior OFDM system.Because system of the present invention has only transmitted the subcarrier of half, therefore system of the present invention is subjected to the influence of frequency shift (FS) less with respect to prior OFDM system.

When receiving terminal correctly detected untapped subcarrier, receiving terminal can put 0 with untapped sub-carrier signal after FFT, thereby has removed

Interference signal on the individual subcarrier has improved 3dB with signal to noise ratio, so system of the present invention error-resilient performance can improve 3dB than prior OFDM system error-resilient performance maximum.

The data of BPSK digital modulation are through the Haar wavelet transformation, and it is 0 that the data after the conversion have half, because in OFDM, the columns certificate that the BPSK digital modulation produces is C (j+1)=[c _J+1,0c _J+1,1C _{J+1, N-1}], c wherein _{J+1, i}∈ 1 ,-1}.C (j+1) is carried out the Haar wavelet transformation to be got:

$\left[\begin{array}{c}{c}_{j,0}\\ c_{j,1}\\ \·\\ \·\\ \·\\ c_{j\·\frac{N}{2}-1}\\ ,0\\ d_{j,1}\\ \·\\ \·\\ \·\\ d_{j\·\frac{N}{2}-1}\end{array}\right]\left[\begin{array}{cccccccc}\frac{1}{\sqrt{2}}& \frac{1}{\sqrt{2}}& 0& 0& 0& \·\·\·& 0& 0\\ 0& 0& \frac{1}{\sqrt{2}}& \frac{1}{\sqrt{2}}& 0& \·\·\·& 0& 0\\ & & & \·& & & & \\ & & & \·& & & & \\ & & & \·& & & & \\ 0& 0& 0& 0& 0& \text{\·\·\·}& \frac{1}{\sqrt{2}}& \frac{1}{\sqrt{2}}\\ -\frac{1}{\sqrt{2}}& \frac{1}{\sqrt{2}}& 0& 0& 0& \·\·\·& 0& 0\\ 0& 0& -\frac{1}{\sqrt{2}}& \frac{1}{\sqrt{2}}& 0& \·\·\·& 0& 0\\ & & & \·& & & & \\ & & & \·& & & & \\ & & & \·& & & & \\ 0& 0& 0& 0& 0& 0& -\frac{1}{\sqrt{2}}& \frac{1}{\sqrt{2}}\end{array}\right]\·\left[\begin{array}{c}{c}_{j+\mathrm{1,0}}\\ c_{j+\mathrm{1,1}}\\ \·\\ \·\\ \·\\ \·\\ \·\\ \·\\ \·\\ \·\\ \·\\ c_{j+1,N-1}\end{array}\right]$

If c _{J, i}≠ 0

d _j，i＝0

If c _{J, i}=0

So after the Haar wavelet decomposition, In have

Individual data are 0, remaining Individual data value is

Be that system of the present invention only uses

Individual subcarrier is so the frequency resource utilance is 2 times of traditional ofdm system.

Claims (1)

1. based on the binary phase-shift keying/orthogonal frequency division multiplexing system of Haar wavelet transformation, it comprises the insertion control module (6) of the first serial/parallel modular converter (1), BPSK data modulator (2), IFFT converter (4), the first parallel/serial modular converter (5), Cyclic Prefix, removal control module (8), the second serial/parallel modular converter (9), FFT converter (10), BPSK data demodulator (12) and the second parallel/serial modular converter (13) of Cyclic Prefix, it is characterized in that: further comprising Haar small echo direct transform module (3) and Haar inverse wavelet transform module (11);

The signal of input obtains parallel signal after the conversion of the first serial/parallel modular converter (1), described parallel signal inputs to BPSK data modulator (2) and modulates, signal after obtaining to modulate, signal after the described modulation inputs to Haar small echo direct transform module (3) and carries out data decomposition, obtain decomposed data, described decomposed data inputs to IFFT converter (4), after IFFT converter (4) conversion, input to the first parallel/serial modular converter (5), after the conversion of the first parallel/serial modular converter (5), obtain serial signal, described serial signal inputs to the insertion control module (6) of Cyclic Prefix and inserts Cyclic Prefix, and passes through channels transmit;

The removal module (8) that will input to Cyclic Prefix from the signal that channel receives is removed Cyclic Prefix, to remove then and obtain parallel signal after signal behind the Cyclic Prefix inputs to the conversion of the second serial/parallel modular converter (9), described parallel signal transfers to and transfers to Haar inverse wavelet transform module (11) after FFT converter (10) conversion and synthesize, data after obtaining to synthesize, data after described synthesizing input to BPSK data demodulator (12) and carry out demodulation, signal after the acquisition demodulation, the signal after the described demodulation input to the second parallel/serial modular converter (13) and are converted to serial signal output.

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