CN101969309A - MAP modulating and coding method of FFH communication system coded by Turbo and modulated by BFSK - Google Patents

Abstract

The invention discloses an MAP modulating and coding method of an FFH communication system coded by Turbo and modulated by BFSK, belonging to the filed of wireless communication. The transmitting-end information source data is transmitted to a channel after being coded by the Turbo, modulated by the BFSK and modulated by the FH; and maximum posterior probability coding is carried out on a receiving end receiving signal after intermediate frequency filtering and frequency domain soft demodulating are carried on the receiving end receiving signal, namely MAP coding. The invention provides an MAP demodulating and coding method by adopting a BFSK incoherent demodulating system, and respectively gives out concrete component coding process in two types aiming at the condition that whether the receiving end knows CSI information or not. In the invention, the system, such as the common fast frequency hopping system adopting the BFSK modulation is enabled to adopt a Turbo code as the channel coding scheme; and compared with the original convolutional code, the coding method provided by the invention has greater coding gain at the condition of relative complexity.

Description

The MAP demodulation coding method of the FFH communication system of a kind of Turbo coding and BFSK modulation

Technical field

The invention belongs to wireless communication technology field, relate to and adopt binary orthogonal frequency shift keying (Binary Frequency Shift Keying, BFSK) fast frequency-hopped (Fast Frequency Hopping, the FFH communication system), a kind of joint demodulation interpretation method in the FFH communication system especially.

Background technology

For at the widely used incoherent BFSK signal of fast frequency-hopped communication system (Fast Frequency Hopping Communication System), mainly contain two kinds of demodulation methods of time domain non-coherent demodulation and frequency domain non-coherent demodulation.Two kinds of demodulation method performance unanimities, but the incoherent soft demodulation of frequency domain has the simple advantage of algorithm, more commonly used in the FFH of reality system.

Turbo code, (Parallel Concatenated Convolution Code, PCCC), it combines convolution code and random interleaver dexterously, has realized the thought of random coded to claim Parallel Concatenated Convolutional Code again.The iterative decoding of several times makes Turbo code have very strong error correcting capability, so that approaches maximum-likelihood decoding.Analog result shows that Turbo code has the performance of approaching the Shannon limit under certain condition.In view of its excellent performance, Turbo code is confirmed as one of channel coding schemes of 3-G (Generation Three mobile communication system) (IMT-2000), and three representative standards of 3GPP all with Turbo code as its channel coding schemes.

In existing FFH system, coding method commonly used has Reed-Solomon (RS) coding, convolutional encoding etc.And in common civilian system, Turbo code is widely used because of its good performance.When under AWGN (Additive WhiteGaussian Noise) channel, adopting the BPSK non-coherent demodulation, code efficiency be 1/2 and the suitable condition of code length under, be 10 in the error rate ^-5The place, the Turbo code that adopts MAP (maximum a posteriori, maximum a posteriori probability) decoding is than the nearly coding gain near 1dB of convolution code that adopts Viterbi decoding.

The MAP decoding algorithm has adopted the structure of feedback decoding, has realized soft input/soft output (soft input, soft output, SISO), the recursion iterative decoding makes the coding and decoding process realize pseudorandom permutation, and simplified the maximum-likelihood decoding algorithm, make its performance approach the Shannon limit.Yet, in iterative decoding process, relate to the calculating of channel transition probability (channel transitionprobability), therefore, decoding algorithm is relevant with concrete modulation-demo-demodulation method and channel model.In existing technical literature, only about phase shift keying (Phase Shift Keying, PSK), (Quadracture AmplitudeModulation QAM) waits the relevant argumentation and the derivation of the MAP decoding algorithm of modulation-demo-demodulation method to quadrature amplitude modulation.In the FFH/BFSK system that adopts the Turbo coding, when adopting non-coherent demodulation, how to carry out correct MAP decoding, becoming one has problem to be solved.

Summary of the invention

The invention provides the MAP demodulation coding method of the FFH communication system of a kind of Turbo coding and BFSK modulation,, realize the bigger coding gain of convolution code commonly used to realize correctly carrying out Turbo decoding in the FFH system.

Detailed technology scheme of the present invention is as follows:

The MAP demodulation coding method of the FFH communication system of a kind of Turbo coding and BFSK modulation as shown in Figure 2, may further comprise the steps:

Step 1:, establish that frame data are U=(u in the digitlization binary source data that need to send at transmitting terminal ₁, u ₂..., u _k... u _N), wherein k=1,2 ..., N, N is a frame sign, information source data u _kThrough after Turbo coding and the BFSK modulation, produce Frequency Hopping Signal successively by the FH modulator

F _hBe current t frequency hopping frequency constantly.Launch through antenna at last.

Step 2: establish and send signal through the frequency selectivity slow fading channel, received signal is B (t) * s (t)+n (t),

Wherein, A is the amplitude of transmitting terminal complex signal, and B (t) is multiple Gaussian random process, f _i(i=0,1) is two modulation frequency f of BFSK modulation ₀, f ₁The primary reception signal obtains intermediate-freuqncy signal after separating jumping

Step 3: to the intermediate-freuqncy signal of step 2 gained

Carry out the soft demodulation of frequency domain, obtain soft demodulation output information Z.Concrete grammar as shown in Figure 3, and is first with intermediate-freuqncy signal

Be divided into two-way, the one tunnel is f through centre frequency ₀Bandpass filtering and | FFT| ²Obtain power signal s after the conversion ₀, another road is f through centre frequency ₁Bandpass filtering and | FFT| ²Obtain power signal s after the conversion ₁Then with two power signal s ₀And s ₁Subtract each other, obtain the soft demodulation output information of frequency domain Z, and Z=(z ₁, z ₂... z _k..., z _N), k=1,2 ..., N.

Step 4: the soft demodulation output information of the frequency domain Z to step 3 gained carries out maximum posteriori decoding, i.e. MAP decoding.If with transmitting terminal information source Frame u _kCorresponding soft demodulation output information z _kIn,

Be channel information, Be check information 1,

Be check information 2, wherein k=1,2 ..., N, N is a frame sign, concrete decode procedure as shown in Figure 4:

Step 4-1: with channel information

With check information 1

Import the first component decoder; Simultaneously to channel information

Carry out with transmitting terminal Turbo cataloged procedure in identical interleaving treatment, with channel information

Through with transmitting terminal Turbo cataloged procedure in information and check information 2 after the identical interleaving treatment

Input second component decoder.

Step 4-2: complete zero the initialization prior information 1 in N position is set, and with the prior information 1 input first component decoder.

Step 4-3: adopt the first component decoder, associating prior information 1, channel information With check information 1

Carry out component decoding, obtain external information 1; Then to external information 1 carry out with transmitting terminal Turbo cataloged procedure in identical interleaving treatment, obtain prior information 2, and with prior information 2 input second component decoders.

Step 4-4: adopt the second component decoder, associating prior information 2, channel information

Through with transmitting terminal Turbo cataloged procedure in information and check information 2 after the identical interleaving treatment

Carry out component decoding, obtain external information 2 and channel information

Corresponding MAP soft decoding information.

Step 4-5: judge first or the second component decoder whether the iterations that soft demodulation output information Z carries out component decoding is reached default iterations, if do not reach, the external information that then step 4-4 obtained 2 through with transmitting terminal Turbo cataloged procedure in the information of corresponding deinterleaving after handling as new prior information 1, and return step 4-3; If reach, execution in step 4-6 then.

Step 4-6: with step 4-4 gained channel information

Corresponding MAP soft decoding information carries out deinterleaving, judgement, obtains final decode results.

Wherein, identical with component decode procedure described in the step 4-4 at step 4-3, if channel information CSI (channel stateinformation) is known, then concrete component decode procedure may further comprise the steps:

Steps A: condition log-likelihood value and the condition log-likelihood ratio of the soft demodulation output information of the frequency domain Z of calculation procedure 3 gained.

Because Z=(z ₁, z ₂... z _k..., z _N), be exactly to calculate z respectively so calculate condition log-likelihood value and the condition log-likelihood ratio of the soft demodulation output information of frequency domain Z _k(k=1,2 ..., N) condition log-likelihood value Λ (z _k| 0), Λ (z _k| 1) and condition log-likelihood ratio L (z _k); Wherein:

$\mathrm{\Λ}\left(z_k\right|0)=-\frac{h_0{A}^2}{{4\mathrm{\σ}}_{\mathrm{\ω}}^2}+\frac{z_k}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}+{\ln Q}_1(\sqrt{h_0\frac{A^2}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}},\sqrt{\left|\frac{{4z}_k}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}\right|})\·u\left(z_k\right)---\left(1\right)$

$\mathrm{\Λ}\left(z_k\right|1)=-\frac{h_1{A}^2}{{4\mathrm{\σ}}_{\mathrm{\ω}}^2}-\frac{z_k}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}+{\ln Q}_1(\sqrt{h_1\frac{A^2}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}},\sqrt{\left|\frac{{4z}_k}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}\right|})\·u\left({-z}_k\right)---\left(2\right)$

In above-mentioned three formulas, h ₀, h ₁Be illustrated respectively in the sampling time, received signal is respectively at f ₀, f ₁The power fading factor at place, A ²Expression sends the ideal power of signal,

Represent the noise average power in a baseband modulation frequency at interval, u () represents step function, Q ₁() expression single order horse khoum (Marcum) function.

Step B: Branch Computed transition probability γ _k(e) and whole soft decoding information L (u _k):

Wherein:

$M_{s,i}={\ln Q}_1(\sqrt{h_{k,i}^s\frac{A^2}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}},\sqrt{\left|\frac{{4z}_k^s}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}\right|})\·u(y_k^s\·x_k^s),$ i＝0，1；

$M_{p,i}={\ln Q}_1(\sqrt{\frac{g\left(x_k^p\right)}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}},\sqrt{\left|\frac{{4z}_k^p}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}\right|})\·u(y_k^p\·x_k^p),$ i＝0，1；

$x_k^s=1-{2\·u}_k;$

Represent that k channel information is at frequency f _i+ F _hThe power fading factor at place,

Represent that k check information is at frequency f _i+ F _hThe power fading factor at place, i=0,1;

Expression information source data u _kChannel information behind the Turbo coding,

Expression information source data u _kCheck information behind the Turbo coding,

Represent soft demodulation output information z _kIn channel information,

Represent soft demodulation output information z _kIn check information.

$L\left(u_k\right)=\mathrm{\Λ}\left(z_k^s\right|u_k)+{\mathrm{\Λ}}_a\left(u_k\right)+{\mathrm{\Λ}}_e\left(u_k\right)---\left(5\right)$

(5) formula equal sign the right is first

The expression channel information

Corresponding MAP soft decoding information, second Λ _a(u _k) the expression prior information, the 3rd Λ _e(u _k) be the external information that produces.

Step C: extract external information ${\mathrm{\Λ}}_e\left(u_k\right)=L\left(u_k\right)-\mathrm{\Λ}\left(z_k^s\right|u_k)-{\mathrm{\Λ}}_a\left(u_k\right).$

If channel information CSI (channel state information) is unknown, then concrete component decode procedure may further comprise the steps:

Step D: condition log-likelihood value and the condition log-likelihood ratio of the soft demodulation output information of the frequency domain Z of calculation procedure 3 gained.

Because Z=(z ₁, z ₂... z _k..., z _N), be exactly to calculate z respectively so calculate condition log-likelihood value and the condition log-likelihood ratio of the soft demodulation output information of frequency domain Z _k(k=1,2 ..., N) condition log-likelihood value Λ (z _k| 0), Λ (z _k| 1) and condition log-likelihood ratio L (z _k); Wherein:

Step e: Branch Computed transition probability γ _k(e) and whole soft decoding information L (u _k):

Wherein:

$g\left(x\right)=\left\{\begin{array}{cc}{h}_{k,0}^p\·A^2,& x>0,\\ h_{k,1}^p\·A^2,& x\≤0;\end{array}\right.$

$L\left(u_k\right)=\mathrm{\Λ}\left(z_k^s\right|u_k)+{\mathrm{\Λ}}_a\left(u_k\right)+{\mathrm{\Λ}}_e\left(u_k\right)---\left(6\right)$

(5) formula equal sign the right is first

The expression channel information

Corresponding MAP soft decoding information, second Λ _a(u _k) the expression prior information, the 3rd Λ _e(u _k) be the external information that produces.

Step F: extract external information ${\mathrm{\Λ}}_e\left(u_k\right)=L\left(u_k\right)-\mathrm{\Λ}\left(z_k^s\right|u_k)-{\mathrm{\Λ}}_a\left(u_k\right).$

The invention provides the MAP demodulation coding method of the FFH communication system of a kind of Turbo coding and BFSK modulation, its main innovation is by the derivation to the conditional probability density function of the soft demodulation of BFSK output, and in conjunction with existing MAP decoding algorithm at modulation systems such as QAM, PSK, take into full account the characteristics of MAP decoding as iterative decoding, the MAP demodulation coding method of suitable employing BFSK non-coherent demodulation system has been proposed, and, divide two kinds and provided concrete component decode procedure respectively at receiving terminal known CSI information whether.The invention enables and adopt system's (such as common quick frequency hopping system) of BFSK modulation can adopt Turbo code as its channel coding schemes, compare with original convolution code, under the suitable situation of complexity, the interpretation method that adopts this patent to propose has bigger coding gain.Simultaneously, the MAP decoding algorithm during the unknown CSI of receiving terminal is suitable for requiring less, redundancy to require less system to algorithm complex; And the MAP decoding algorithm during the known CSI of receiving terminal is suitable for allowing bigger algorithm complex and redundancy, but the system that performance is had higher requirements, thereby the system that makes can select interpretation method as the case may be flexibly.

Description of drawings

Fig. 1 is the system configuration schematic diagram of the FFH system of the traditional convolutional encoding of employing, BFSK modulation.

The MAP demodulation coding method structural representation of the FFH communication system that Turbo coding that Fig. 2 proposes for the present invention and BFSK modulate.

The structural representation of incoherent soft demodulation in the MAP demodulation coding method of the FFH communication system that Turbo coding that Fig. 3 proposes for the present invention and BFSK modulate.

The structural representation of MAP demodulation coding process in the MAP demodulation coding method of the FFH communication system that Turbo coding that Fig. 4 proposes for the present invention and BFSK modulate.

Embodiment

The MAP demodulation coding method of the FFH communication system of a kind of Turbo coding and BFSK modulation as shown in Figure 2, may further comprise the steps:

Step 1:, establish that frame data are U=(u in the digitlization binary source data that need to send at transmitting terminal ₁, u ₂..., u _k... u _N), wherein k=1,2 ..., N, N is a frame sign, information source data u _kThrough after Turbo coding and the BFSK modulation, produce Frequency Hopping Signal successively by the FH modulator

F _hBe current t frequency hopping frequency constantly.Launch through antenna at last.

Step 2: establish and send signal through the frequency selectivity slow fading channel, received signal is B (t) * s (t)+n (t), Wherein, A is the amplitude of transmitting terminal complex signal, and B (t) is multiple Gaussian random process, f _i(i=0,1) is two modulation frequency f of BFSK modulation ₀, f ₁The primary reception signal obtains intermediate-freuqncy signal after separating jumping

Step 3: to the intermediate-freuqncy signal of step 2 gained

Carry out the soft demodulation of frequency domain, obtain soft demodulation output information Z.Concrete grammar as shown in Figure 3, and is first with intermediate-freuqncy signal

Be divided into two-way, the one tunnel is f through centre frequency ₀Bandpass filtering and | FFT| ²Obtain power signal s after the conversion ₀, another road is f through centre frequency ₁Bandpass filtering and | FFT| ²Obtain power signal s after the conversion ₁Then with two power signal s ₀And s ₁Subtract each other, obtain the soft demodulation output information of frequency domain Z, and Z=(z ₁, z ₂... z _k..., z _N), k=1,2 ..., N.

Step 4: the soft demodulation output information of the frequency domain Z to step 3 gained carries out maximum posteriori decoding, i.e. MAP decoding.If with transmitting terminal information source Frame u _kCorresponding soft demodulation output information z _kIn,

Be channel information, Be check information 1,

Be check information 2, wherein k=1,2 ..., N, N is a frame sign, concrete decode procedure as shown in Figure 4:

Step 4-1: with channel information

With check information 1

Import the first component decoder; Simultaneously to channel information Carry out with transmitting terminal Turbo cataloged procedure in identical interleaving treatment, with channel information

Through with transmitting terminal Turbo cataloged procedure in information and check information 2 after the identical interleaving treatment Input second component decoder.

Step 4-2: complete zero the initialization prior information 1 in N position is set, and with the prior information 1 input first component decoder.

Step 4-3: adopt the first component decoder, associating prior information 1, channel information

With check information 1

Carry out component decoding, obtain external information 1; Then to external information 1 carry out with transmitting terminal Turbo cataloged procedure in identical interleaving treatment, obtain prior information 2, and with prior information 2 input second component decoders.

Step 4-4: adopt the second component decoder, associating prior information 2, channel information

Through with transmitting terminal Turbo cataloged procedure in information and check information 2 after the identical interleaving treatment

Carry out component decoding, obtain external information 2 and channel information Corresponding MAP soft decoding information.

Step 4-5: judge first or the second component decoder whether the iterations that soft demodulation output information Z carries out component decoding is reached default iterations, if do not reach, the external information that then step 4-4 obtained 2 through with transmitting terminal Turbo cataloged procedure in the information of corresponding deinterleaving after handling as new prior information 1, and return step 4-3; If reach, execution in step 4-6 then.

Step 4-6: with step 4-4 gained channel information

Corresponding MAP soft decoding information carries out deinterleaving, judgement, obtains final decode results.

Wherein, identical with component decode procedure described in the step 4-4 at step 4-3, if channel information CSI (channel stateinformation) is known, then concrete component decode procedure may further comprise the steps:

Steps A: condition log-likelihood value and the condition log-likelihood ratio of the soft demodulation output information of the frequency domain Z of calculation procedure 3 gained.

Because Z=(z ₁, z ₂... z _k..., z _N), be exactly to calculate z respectively so calculate condition log-likelihood value and the condition log-likelihood ratio of the soft demodulation output information of frequency domain Z _k(k=1,2 ..., N) condition log-likelihood value Λ (z _k| 0), Λ (z _k| 1) and condition log-likelihood ratio L (z _k); Wherein:

$\mathrm{\Λ}\left(z_k\right|0)=-\frac{h_0{A}^2}{{4\mathrm{\σ}}_{\mathrm{\ω}}^2}+\frac{z_k}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}+{\ln Q}_1(\sqrt{h_0\frac{A^2}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}},\sqrt{\left|\frac{{4z}_k}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}\right|})\·u\left(z_k\right)---\left(1\right)$

$\mathrm{\Λ}\left(z_k\right|1)=-\frac{h_1{A}^2}{{4\mathrm{\σ}}_{\mathrm{\ω}}^2}-\frac{z_k}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}+{\ln Q}_1(\sqrt{h_1\frac{A^2}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}},\sqrt{\left|\frac{{4z}_k}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}\right|})\·u\left({-z}_k\right)---\left(2\right)$

In above-mentioned three formulas, h ₀, h ₁Be illustrated respectively in the sampling time, received signal is respectively at f ₀, f ₁The power fading factor at place, A ²Expression sends the ideal power of signal,

Represent the noise average power in a baseband modulation frequency at interval, u () represents step function, Q ₁() expression single order horse khoum (Marcum) function.

Step B: Branch Computed transition probability γ _k(e) and whole soft decoding information L (u _k):

Wherein:

$M_{s,i}={\ln Q}_1(\sqrt{h_{k,i}^s\frac{A^2}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}},\sqrt{\left|\frac{{4z}_k^s}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}\right|})\·u(y_k^s\·x_k^s),$ i＝0，1；

$M_{p,i}={\ln Q}_1(\sqrt{\frac{g\left(x_k^p\right)}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}},\sqrt{\left|\frac{{4z}_k^p}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}\right|})\·u(y_k^p\·x_k^p),$ i＝0，1；

$x_k^s=1-{2\·u}_k;$

Represent that k channel information is at frequency f _i+ F _hThe power fading factor at place,

Represent that k check information is at frequency f _i+ F _hThe power fading factor at place, i=0,1; Expression information source data u _kChannel information behind the Turbo coding, Expression information source data u _kCheck information behind the Turbo coding,

Represent soft demodulation output information z _kIn channel information,

Represent soft demodulation output information z _kIn check information.

$L\left(u_k\right)=\mathrm{\Λ}\left(z_k^s\right|u_k)+{\mathrm{\Λ}}_a\left(u_k\right)+{\mathrm{\Λ}}_e\left(u_k\right)---\left(5\right)$

(5) formula equal sign the right is first

The expression channel information

Corresponding MAP soft decoding information, second Λ _a(u _k) the expression prior information, the 3rd Λ _e(u _k) be the external information that produces.

Step C: extract external information ${\mathrm{\Λ}}_e\left(u_k\right)=L\left(u_k\right)-\mathrm{\Λ}\left(z_k^s\right|u_k)-{\mathrm{\Λ}}_a\left(u_k\right).$

If channel information CSI (channel state information) is unknown, then concrete component decode procedure may further comprise the steps:

Step D: condition log-likelihood value and the condition log-likelihood ratio of the soft demodulation output information of the frequency domain Z of calculation procedure 3 gained.

Because Z=(z ₁, z ₂... z _k..., z _N), be exactly to calculate z respectively so calculate condition log-likelihood value and the condition log-likelihood ratio of the soft demodulation output information of frequency domain Z _k(k=1,2 ..., N) condition log-likelihood value Λ (z _k| 0), Λ (z _k| 1) and condition log-likelihood ratio L (z _k); Wherein:

Step e: Branch Computed transition probability γ _k(e) and whole soft decoding information L (u _k):

Wherein:

$g\left(x\right)=\left\{\begin{array}{cc}{h}_{k,0}^p\·A^2,& x>0,\\ h_{k,1}^p\·A^2,& x\≤0;\end{array}\right.$

$L\left(u_k\right)=\mathrm{\Λ}\left(z_k^s\right|u_k)+{\mathrm{\Λ}}_a\left(u_k\right)+{\mathrm{\Λ}}_e\left(u_k\right)---\left(6\right)$

(5) formula equal sign the right is first

The expression channel information

Corresponding MAP soft decoding information, second Λ _a(u _k) the expression prior information, the 3rd Λ _e(u _k) be the external information that produces.

Step F: extract external information ${\mathrm{\Λ}}_e\left(u_k\right)=L\left(u_k\right)-\mathrm{\Λ}\left(z_k^s\right|u_k)-{\mathrm{\Λ}}_a\left(u_k\right).$

The invention provides the MAP demodulation coding method of the FFH communication system of a kind of Turbo coding and BFSK modulation, its main innovation is by the derivation to the conditional probability density function of the soft demodulation of BFSK output, and in conjunction with existing MAP decoding algorithm at modulation systems such as QAM, PSK, take into full account the characteristics of MAP decoding as iterative decoding, the MAP demodulation coding method of suitable employing BFSK non-coherent demodulation system has been proposed, and, divide two kinds and provided concrete component decode procedure respectively at receiving terminal known CSI information whether.The invention enables and adopt system's (such as common quick frequency hopping system) of BFSK modulation can adopt Turbo code as its channel coding schemes, compare with original convolution code, under the suitable situation of complexity, the interpretation method that adopts this patent to propose has bigger coding gain.Simultaneously, the MAP decoding algorithm during the unknown CSI of receiving terminal is suitable for requiring less, redundancy to require less system to algorithm complex; And the MAP decoding algorithm during the known CSI of receiving terminal is suitable for allowing bigger algorithm complex and redundancy, but the system that performance is had higher requirements, thereby the system that makes can select interpretation method as the case may be flexibly.

Claims (3)

1. the MAP demodulation coding method of Turbo coding and the BFSK FFH communication system of modulating may further comprise the steps:

Step 1:, establish that frame data are U=(u in the digitlization binary source data that need to send at transmitting terminal ₁, u ₂..., u _k... u _N), wherein k=1,2 ..., N, N is a frame sign, information source data u _kThrough after Turbo coding and the BFSK modulation, produce Frequency Hopping Signal successively by the FH modulator

F _hBe current t frequency hopping frequency constantly; Launch through antenna at last;

Step 2: establish and send signal through the frequency selectivity slow fading channel, received signal is B (t) * s (t)+n (t), Wherein, A is the amplitude of transmitting terminal complex signal, and B (t) is multiple Gaussian random process, f _i(i=0,1) is two modulation frequency f of BFSK modulation ₀, f ₁The primary reception signal obtains intermediate-freuqncy signal after separating jumping

Step 3: to the intermediate-freuqncy signal of step 2 gained

Carry out the soft demodulation of frequency domain, obtain soft demodulation output information Z.Concrete grammar is, earlier with intermediate-freuqncy signal

Be divided into two-way, the one tunnel is f through centre frequency ₀Bandpass filtering and | FFT| ²Obtain power signal s after the conversion ₀, another road is f through centre frequency ₁Bandpass filtering and | FFT| ²Obtain power signal s after the conversion ₁Then with two power signal s ₀And s ₁Subtract each other, obtain the soft demodulation output information of frequency domain Z, and Z=(z ₁, z ₂... z _k..., z _N), k=1,2 ..., N;

Step 4: the soft demodulation output information of the frequency domain Z to step 3 gained carries out maximum posteriori decoding, i.e. MAP decoding; If with transmitting terminal information source Frame u _kCorresponding soft demodulation output information z _kIn,

Be channel information,

Be check information 1, Be check information 2, wherein k=1,2 ..., N, N is a frame sign, concrete decode procedure is:

Step 4-1: with channel information With check information 1

Import the first component decoder; Simultaneously to channel information Carry out with transmitting terminal Turbo cataloged procedure in identical interleaving treatment, with channel information

Through with transmitting terminal Turbo cataloged procedure in information and check information 2 after the identical interleaving treatment

Input second component decoder;

Step 4-2: complete zero the initialization prior information 1 in N position is set, and with the prior information 1 input first component decoder;

Step 4-3: adopt the first component decoder, associating prior information 1, channel information With check information 1

Carry out component decoding, obtain external information 1; Then to external information 1 carry out with transmitting terminal Turbo cataloged procedure in identical interleaving treatment, obtain prior information 2, and with prior information 2 input second component decoders;

Step 4-4: adopt the second component decoder, associating prior information 2, channel information

Through with transmitting terminal Turbo cataloged procedure in information and check information 2 after the identical interleaving treatment

Carry out component decoding, obtain external information 2 and channel information

Corresponding MAP soft decoding information;

Step 4-5: judge first or the second component decoder whether the iterations that soft demodulation output information Z carries out component decoding is reached default iterations, if do not reach, the external information that then step 4-4 obtained 2 through with transmitting terminal Turbo cataloged procedure in the information of corresponding deinterleaving after handling as new prior information 1, and return step 4-3; If reach, execution in step 4-6 then;

Step 4-6: with step 4-4 gained channel information

Corresponding MAP soft decoding information carries out deinterleaving, judgement, obtains final decode results.

2. the MAP demodulation coding method of the FFH communication system of Turbo coding according to claim 1 and BFSK modulation, it is characterized in that, step 4-3 is identical with component decode procedure described in the step 4-4, if channel information CSI is known, then concrete component decode procedure may further comprise the steps:

Steps A: condition log-likelihood value and the condition log-likelihood ratio of the soft demodulation output information of the frequency domain Z of calculation procedure 3 gained;

Because Z=(z ₁, z ₂... z _k..., z _N), be exactly to calculate z respectively so calculate condition log-likelihood value and the condition log-likelihood ratio of the soft demodulation output information of frequency domain Z _k(k=1,2 ..., N) condition log-likelihood value Λ (z _k| 0), Λ (z _k| 1) and condition log-likelihood ratio L (z _k); Wherein:

$\mathrm{\Λ}\left(z_k\right|0)=-\frac{h_0{A}^2}{{4\mathrm{\σ}}_{\mathrm{\ω}}^2}+\frac{z_k}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}+{\ln Q}_1(\sqrt{h_0\frac{A^2}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}},\sqrt{\left|\frac{{4z}_k}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}\right|})\·u\left(z_k\right)---\left(1\right)$

$\mathrm{\Λ}\left(z_k\right|1)=-\frac{h_1{A}^2}{{4\mathrm{\σ}}_{\mathrm{\ω}}^2}-\frac{z_k}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}+{\ln Q}_1(\sqrt{h_1\frac{A^2}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}},\sqrt{\left|\frac{{4z}_k}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}\right|})\·u\left({-z}_k\right)---\left(2\right)$

In above-mentioned three formulas, h ₀, h ₁Be illustrated respectively in the sampling time, received signal is respectively at f ₀, f ₁The power fading factor at place, A ²Expression sends the ideal power of signal,

Represent the noise average power in a baseband modulation frequency at interval, u () represents step function, Q ₁() expression single order horse khoum function;

Step B: Branch Computed transition probability γ _k(e) and whole soft decoding information L (u _k):

Wherein:

$M_{s,i}={\ln Q}_1(\sqrt{h_{k,i}^s\frac{A^2}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}},\sqrt{\left|\frac{{4z}_k^s}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}\right|})\·u(y_k^s\·x_k^s),i=\mathrm{0,1};$

$M_{p,i}={\ln Q}_1(\sqrt{\frac{g\left(x_k^p\right)}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}},\sqrt{\left|\frac{{4z}_k^p}{{2\mathrm{\σ}}_{\mathrm{\ω}}^2}\right|})\·u(y_k^p\·x_k^p),i=\mathrm{0,1};$

$x_k^s=1-{2\·u}_k;$

Represent that k channel information is at frequency f _i+ F _hThe power fading factor at place,

Represent that k check information is at frequency f _i+ F _hThe power fading factor at place, i=0,1;

Expression information source data u _kChannel information behind the Turbo coding, Expression information source data u _kCheck information behind the Turbo coding,

Represent soft demodulation output information z _kIn channel information,

Represent soft demodulation output information z _kIn check information;

$L\left(u_k\right)=\mathrm{\Λ}\left(z_k^s\right|u_k)+{\mathrm{\Λ}}_a\left(u_k\right)+{\mathrm{\Λ}}_e\left(u_k\right)---\left(5\right)$

(5) formula equal sign the right is first

The expression channel information

Corresponding MAP soft decoding information, second Λ _a(u _k) the expression prior information, the 3rd Λ _e(u _k) be the external information that produces;

Step C: extract external information ${\mathrm{\Λ}}_e\left(u_k\right)=L\left(u_k\right)-\mathrm{\Λ}\left(z_k^s\right|u_k)-{\mathrm{\Λ}}_a\left(u_k\right).$

3. the MAP demodulation coding method of the FFH communication system of Turbo coding according to claim 1 and BFSK modulation, it is characterized in that, step 4-3 is identical with component decode procedure described in the step 4-4, if channel information CSI is unknown, then concrete component decode procedure may further comprise the steps:

Step D: condition log-likelihood value and the condition log-likelihood ratio of the soft demodulation output information of the frequency domain Z of calculation procedure 3 gained;

Because Z=(z ₁, z ₂... z _k..., z _N), be exactly to calculate z respectively so calculate condition log-likelihood value and the condition log-likelihood ratio of the soft demodulation output information of frequency domain Z _k(k=1,2 ..., N) condition log-likelihood value Λ (z _k| 0), Λ (z _k| 1) and condition log-likelihood ratio L (z _k); Wherein:

Step e: Branch Computed transition probability γ _k(e) and whole soft decoding information L (u _k):

Wherein:

$g\left(x\right)=\left\{\begin{array}{cc}{h}_{k,0}^p\·A^2,& x>0,\\ h_{k,1}^p\·A^2,& x\≤0;\end{array}\right.$

$L\left(u_k\right)=\mathrm{\Λ}\left(z_k^s\right|u_k)+{\mathrm{\Λ}}_a\left(u_k\right)+{\mathrm{\Λ}}_e\left(u_k\right)---\left(6\right)$

(5) formula equal sign the right is first

The expression channel information

Corresponding MAP soft decoding information, second Λ _a(u _k) the expression prior information, the 3rd Λ _e(u _k) be the external information that produces;

Step F: extract external information ${\mathrm{\Λ}}_e\left(u_k\right)=L\left(u_k\right)-\mathrm{\Λ}\left(z_k^s\right|u_k)-{\mathrm{\Λ}}_a\left(u_k\right).$

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