CN103647737B - The time hopping modulation implementation method of MPPSK modulation - Google Patents

Abstract

The time hopping modulation implementation method that the open a kind of multielement positional phase shift keying (MPPSK) of the present invention is modulated, may be used for realizing the multi-user communication of MPPSK modulation.The symbol period of MPPSK is divided into the chip of several non-overlapping copies by transmitting terminal, and each user, by pattern during the jumping of unique distribution, selects a chip certain time slot generation phase hit wherein；Pattern when receiving terminal utilizes the jumping identical with targeted customer, receives by the signal trace after shock filter.During the jumping of any two user, pattern is orthogonal, then will not clash between the multi-user of MPPSK modulation so that multiple users share Same Physical channel and are possibly realized.

Description

The time hopping modulation implementation method of MPPSK modulation

Technical field

The present invention relates to the modulates information in digital communication and demodulation, particularly relate to one and utilize Time-Hopping to realize The method of MPPSK modulation multiple access communication, belongs to the technical field of high-efficiency digital information transmission.

Background technology

1, time hopping modulation

In a wireless communication system, multiple access technique makes multiple user share same channel to be possibly realized, many Location property relationship, to the user capacity of system and efficiency of transmission, is the important finger weighing wireless communication system Mark.Time hopping modulation (THMA) technology requires pattern when the transceiver being in communication with each other uses same jumping, sender Utilize pattern when jumping to control pulse launch time, avoid or reduce occurring at receiving terminal with other users from the time The probability of collision, thus ensure the reliability that user-to-user information transmits, it is achieved multiple access accesses.Time hopping modulation shape It is openness that the signal become has time domain, in conjunction with the feature that MPPSK modulated signal dutycycle is minimum, can will jump Time multiple access technology for MPPSK modulation multi-user communication.

2, MPPSK modulation

Multielement positional phase shift keying (MPPSK:M-ary Position Phase Shift Keying) modulation (see " multielement positional phase shift keying modulation and demodulation method ", patent of invention number: ZL200710025202.1) it is one Plant the two-dimensional modulation that position and phase shift all can be carried out keying, mainly utilize information sequence in a code-element period The diverse location of sinusoidal carrier is carried out phase-shift keying (PSK).With EBPSK (see " unified orthogonal binary shifted key Modulation and demodulation method ", the patent No.: ZL200710025203.6) compare, in identical code-element period, MPPSK modulation can transmit more information data.

In a code-element period, the expression formula of MPPSK modulation is:

$f_k\left(t\right)=\left\{\begin{array}{ccc}\sin {\mathrm{\&omega;}}_{c}t& 0\&le;t<\mathrm{NT}& k=0\\ \left\{\begin{array}{ccc}\sin {\mathrm{\&omega;}}_{c}t& 0\&le;t\&le;(k-1)\mathrm{KT}& \\ \sin ({\mathrm{\&omega;}}_{c}t+\mathrm{\&theta;})& (k-1)\mathrm{KT}<t<(k-r_g)\mathrm{KT},0<\mathrm{\&theta;}\&le;\mathrm{\&pi;}& 1\&le;k\&le;M-1\\ \sin {\mathrm{\&omega;}}_{c}t& (k-r_g)\mathrm{KT}\&le;t<\mathrm{NT}& \end{array}\right.& & \end{array}\right.---\left(1\right)$

Wherein, and k}={0,1 ..., M-1} is the information sequence sent, ω_cFor carrier angular frequencies, T=2 π/ω_cFor Carrier cycle, 0≤r_g＜ 1 protects the Separation control factor for symbol, and N is the carrier wave contained by a symbol period Amount of cycles, K represents the carrier cycle quantity that phase hit is lasting.By M, N, K and θ and r_gCommon structure Change signal bandwidth, efficiency of transmission and " modulation parameter " of demodulation performance are become.As M=2 and r_gWhen=0, MPPSK is degenerated to EBPSK, the most to a certain extent, can MPPSK be called the EBPSK extended, Coverage is wider, and uses more flexible.

3, shock filter

In order to improve the availability of frequency spectrum, " 0 " code element of MPPSK modulated signal and " non-zero " code element are in time domain On difference the least, and in order to highlight this difference in demodulator, we in patent of invention " for strengthening not The impact filtering method of symmetrical binary modulating signal " (patent of invention number: ZL200910029875.3.The application " impact filtering " involved by book, source is all this, the most no longer statement) in, once disclosed a kind of special Different infinite-duration impulse response (IIR) digital filter, can highlight the phase of MPPSK/EBPSK modulated signal Position saltus step.This wave filter passes through trap-selecting frequency characteristic that its bandpass center is precipitous, can be by MPPSK/EBPSK The phase hit of modulated signal is converted into obvious and strong parastic modulation impact, and output signal-to-noise ratio is significantly carried Rise.

Summary of the invention

It is an object of the invention to time hopping modulation technology is applied to MPPSK modulation, it is provided that a kind of MPPSK adjusts The time hopping modulation implementation method of system, can allow the multiple users share Same Physical channel of MPPSK system, it is achieved The multiple access communication of MPPSK modulation.

Technical scheme is as follows:

A kind of time hopping modulation implementation method of MPPSK modulation, it is characterised in that: transmitting terminal is at time domain continuous print Being modulated on sinusoidal carrier, each symbol period of M system MPPSK modulation is divided into and number of users The equal persistent period is identical and the chip of non-overlapping copies, and each chip is divided into M-1 persistent period phase With and the time slot of non-overlapping copies, pattern and symbol to be sent during the jumping uniquely distributed according to user, at corresponding symbol Selecting certain time slot generation phase hit of one of them chip in number cycle, the other parts in addition to saltus step are all Sine wave, thus obtains the transmitting signal of symbol to be sent；Receiving terminal will receive signal by after shock filter Take envelope, according to pattern when propagation delay time and identical jumping, decision region is accurately positioned in symbol period On certain time-hopping code sheet, and the envelope value of M-1 time slot in chip is taken out as judgment variables, utilize Judgment variables detects transmitted symbol.

The further technical scheme of the present invention is: during the jumping of any two user, pattern is orthogonal, avoids from the time Collide at receiving terminal with other transmitting terminals, it is achieved multiple access accesses.

Wherein, during jumping, pattern is controlled by a PN code sequence, it is assumed that { t_nWhen being to be assigned exclusively to the jumping of user n Pattern, then tn is for meeting 0≤t_nThe integer value of≤Q-1, Q is the number of chips of symbol period.

Beneficial effects of the present invention:

The time hopping modulation implementation method of MPPSK of the present invention modulation, modulates time hopping modulation technology with MPPSK Technology combines, it is possible to realize the multiple access communication of MPPSK modulation.The transceiver being in communication with each other uses same Pattern during jumping, sender utilizes pattern when jumping to control the time slot that saltus step occurs, and receiver utilizes and targeted customer's phase With jumping time pattern follow the tracks of receive.During the jumping of any two user, pattern is orthogonal, avoids with other from the time The collision that user occurs at receiving terminal, thus ensure the reliability that user-to-user information transmits, it is achieved multiple access accesses. The inventive method not only band efficiency is high, and achieves multiple user and share Same Physical channel and the most mutual Interference, improves power system capacity and efficiency of transmission.

Accompanying drawing explanation

Fig. 1 is the transmitter block diagram of MPPSK Time-hopping Modulation.

Fig. 2 is that the figure of MPPSK Time-hopping Modulation represents.

The impact filtering output of signal when Fig. 3 is MPPSK jumping.

The receiver block diagram of signal when Fig. 4 is MPPSK jumping.

When Fig. 5 is MPPSK jumping, the figure of signal detection judgement represents.

Fig. 6 be MPPSK two users when jumping the figure of signal represent.

Fig. 7 is MPPSK two users impact envelope diagrams of signal when jumping.

Fig. 8 is the ber curve comparison diagram of the embodiment of the present invention.

Detailed description of the invention

In order to better understand the technological means of the present invention, and can be practiced according to the content of description, Below with presently preferred embodiments of the present invention and coordinate accompanying drawing that technical solution of the present invention is described in detail.At accompanying drawing In:

Below with reference to the accompanying drawings and in conjunction with the embodiments, the present invention is described in detail.

1, MPPSK Time-hopping Modulation

From the expression formula (1) of MPPSK it can be seen that MPPSK modulated signal shows as a succession of on time domain Sine wave in occur in that the saltus step of very short time.Can MPPSK modulated process regard as to a succession of just The change of some moment waveform phase in string ripple.As a example by when θ=π, saltus step waveform can be expressed as -2sinω_cT and sinusoidal signal sin ω_cThe superposition of t.

Thus, the modulation of MPPSK time hopping modulation can operate on a series of sine wave.When MPPSK jumps The principle that realizes of system transmitter (sets θ=π) as shown in Figure 1, at a symbol period T_sIn=NT the second, use The b=log that family n is to be sent₂M position message is loaded in M hex notation buffer.We are this b position Symbol table is shown as k_n, and k_n∈{0,1,…,M-1}.M hex notation k_nIt is stored temporarily in buffer, etc. Treat the arrival of oneself sending time slots.For each M hex notation in Fig. 1, transmitter produces a time domain Pulse P [t-(i-1) T_s], wherein i represents code element sequence number, i=1,2,3 ...；P (t) is defined on [0, T_jOn), and And be normalized toWherein T_j=(1-r_g) KT, for MPPSK modulation saltus step time Long.{ t in Fig. 1_nFor distributing to pattern when PN (Pseudo-Noise, the pseudo noise) code of user n is jumped, Wherein t_nFor meeting 0≤t_nThe integer value of≤Q-1, Q is the number of chips of each symbol period；Figure when PN code is jumped The PN code sequence that case is produced by PN code generator controls.Each symbol period is divided into Q chip, each code The sheet persistent period is the Tc second, and during jumping, pattern adds a dependence to the time domain impulse in each M hex notation In the time shift of PN code, this time shift is discrete time value t_nT_c, meet 0≤t_nT_c≤(Q-1)T_c.Root Signal pulse P [t-(i-1) T is can get according to this time shift_s-t_nT_c]。

In MPPSK time-hopping systems, each chip duration is further divided into M-1 time slot, each Slot length is T_h=KT the second.During jumping, pattern determines the chip that saltus step occurs, and M hex notation k_nReally Determine the time slot that in this chip, saltus step occurs.As shown in fig. 1, it is divided into two kinds of situations, if k_n=0, then will Pulse zero setting；If k_n≠ 0, then by pulse daley (k_n-1)T_hSecond, produce a time domain impulse P[t-(i-1)T_s-t_nT_c-(k_n-1)T_h].Afterwards, obtained pulse diagonal frequencies is ω_cWaveform -2sinω_cT is modulated, then with sinusoidal wave sin ω_cT is superimposed.Then user n i-th M hex notation Launch signal can be expressed as

$S_n\left(t\right)=\left\{\begin{array}{c}\sin {\mathrm{\&omega;}}_{c}t\\ P[t-(i-1)T_s-t_n{T}_c-(k_n-1)T_n]\&times;(-2\sin {\mathrm{\&omega;}}_{c}t)+\sin {\mathrm{\&omega;}}_{c}t\end{array}\right.----\left(2\right)$

Wherein (i-1) T_s≤ t ＜ iT_s.It can be seen that formula (2) and formula (1) have identical spatial structure, i.e. work as transmitting During symbol 0, the most sinusoidal wave sin ω in symbol period_ct；When launching non-zero symbol, only within the shortest period Saltus step is-sin ω_cT, other period is all sinusoidal wave sin ω_cT, illustrates that MPPSK Time-hopping Modulation maintains The modulation signature of MPPSK.Unlike general MPPSK modulation, MPPSK Time-hopping Modulation adds Pattern during jumping, pattern when jump position depends on jumping, same M hex notation saltus step in symbol period Position can be different.

The realizing principle and can be further illustrated by the example shown in Fig. 2 of MPPSK Time-hopping Modulation.At this In example, it is assumed that M=8, each chip lengths T_cInterior timeslot number is M-1=7, each symbol period Number of chips is Q=4.Assume to send 6 M hex notation, symbol sequence to be sent corresponding to 6 symbol periods It is classified as { k_n}={ 5,2,0,7,4,3}, when it is jumped, pattern is t_n={ 2,0,3,1}, during jumping, pattern circulates in time and prolongs Stretch for 2,0,3,1,2,0,3,1,2,0 ... }.

Therefore, according to formula (2), the set of hop slot can be released and be in following position:

[0T_s+2T_c+4T_h,0T_s+2T_c+5T_h), [1T_s+0T_c+1T_h,1T_s+0T_c+2T_h)

Saltus step is not had, [3T in 3rd symbol period_s+1T_c+6T_h,3T_s+1T_c+7T_h)

[4T_s+2T_c+3T_h,4T_s+2T_c+4T_h), [5T_s+0T_c+2T_h,5T_s+0T_c+3T_h)

As in figure 2 it is shown, corresponding hop slot represents with black thick stick, saltus step occurs in hop slot, except saltus step Other outer period is all sinusoidal wave sin ω_cT, wherein the 3rd symbol is 0, does not haves jumping in symbol period Become.

2, the detection of signal when MPPSK jumps

When MPPSK jumps, signal and common MPPSK modulated signal do not have any essential distinction in time domain, because of And still can carry out detection judgement by shock filter.This shock filter is by a pair conjugation zero point and at least Two pairs of conjugate poles are constituted, and its signal carrier frequency is higher than zero frequency but less than all pole frequencies, and zero frequency With the close degree of pole frequency, at least up to the 10 of signal carrier frequency^-3Magnitude, this wave filter is for by MPPSK Carrier phase saltus step in modulated signal is converted into parastic modulation impact.As it is shown on figure 3, signal when MPPSK jumps After shock filter, phase hit is converted into amplitude and crosses punching, after the absolute value of impact filtering output takes envelope Modulation intelligence can be highlighted.

Except for the difference that, when detection MPPSK jumps, signal need to be by pattern during identical with transmitter jumping, to phase place The chip that saltus step occurs positions, thus obtains the sequence of symhols of this user.Based on shock filter, it is used for When detection MPPSK jumps, the receiver block diagram of signal is as shown in Figure 4.Assume that receiver has been carried out receiving signal Synchronization, therefore can obtain propagation delay time τ_nAccurate estimation.In addition, it is assumed that local PN occurs in receiver Device creates pattern copy when jumping, pattern during i.e. identical with transmitter jumping.According to propagation delay time τ_n, In i-th symbol, pulse generator is that i-th symbol produces time domain impulse P [t-(i-1) T_s-τ_n]； Pattern value t during pattern generator output corresponding jumping during jumping_n, time domain impulse postpones t_nT_cSecond, become P[t-(i-1)T_s-t_nT_c-τ_n].Then this pulse is respectively through 0T_h,1T_h,…,(M-2)T_hAfter delay with connect The envelope of the impact filtering output absolute value of collection of letters r (t) is multiplied, and obtains M-1 judgment variables, i.e. A_n1,A_n2,…,A_n(M-1)。

Said process is equivalent to according to propagation delay time τ_nAnd pattern value t when jumping_n, decision region is accurately positioned On certain time-hopping code sheet in symbol period, and the envelope value of M-1 time slot in this chip is taken out as sentencing Certainly variable.Owing to, after shock filter, the envelope value at phase hit is greater than other position, therefore only Suitable thresholding is set, M-1 judgment variables obtained by utilization, it is possible to detect transmitted M Hex notation.Under conditions of not having noise jamming, { 5,2,0,7,4,3} is corresponding to send symbol with 68 systems Judgment variables can be expressed as shown in Fig. 5, wherein A_ntFor decision threshold, when transmission symbol is 0, gained To judgment variables be both less than threshold value；When transmission symbol is not 0, only to send the symbol judgement as sequence number Variable is more than threshold value.

In the actual scene that there is noise jamming, we just choose maximum one from these judgment variables and enter Row detection judgement.Concrete judgement mode is: first obtain M-1 judgment variables A_n1,A_n2,…,A_n(M-1)In Maximum, if this maximum is less than decision threshold, then this symbol is 0；If this maximum is more than decision threshold, Then the sequence number of the judgment variables that maximum is corresponding is exactly the value of symbol of output.

3, the time hopping modulation of MPPSK modulation

In MPPSK time hopping modulation communicates, each user dynamically distributes time slot by pattern during distinctive jumping, When assuming the jumping of any two user, pattern has orthogonality, then can scheme when receiving terminal is by unique jumping Case distinguishes multiple users.

As a example by 4 users, each symbol period T_sBeing divided into 4 chips, during jumping, pattern is according to shown in table 1 When being allocated, multi-user interference can be avoided, and MPPSK multiple access communication will not clash.

Pattern distribution when table 1 is jumped

User	Pattern during jumping
		U1	2031
U2	0312
		U3	1203
U4	3120

MPPSK time hopping modulation principle can be understood further by following legend.Fig. 6 gives 6 The signal during jumping that in individual continuous symbol, two users send.Except public parameter M=8, outside Q=4, use During the jumping at family 1, pattern is t₁=2,0,3,1}, and during the jumping of user 2, pattern is t₂={ 0,3,1,2}；User 1 8 hex notation sent are k₁=5,2,0,7,4,3, user 2 send for k₂=3,2,7,5,4,6.Black thick stick represents The hop slot of user 1, slash represents the hop slot of user 2, it will be seen from figure 6 that just have employed Handing over two users of pattern when jumping, even if sending identical symbol in the same symbol cycle, hop slot also will not Collide.

Assume to use synchronous transfer, i.e. propagation delay time τ₁=τ₂=..., if wishing the signal of demodulation nth user, Pattern { t when then receiver needs the jumping utilizing nth user_n, examine according to the reception block diagram shown in Fig. 4 Survey.

Simulate the envelope waveform after U1, U2 two users' time hopping modulation signal passes through shock filter, such as Fig. 7 institute Show.For the ease of investigating the judgment variables superposition situation in time domain of two users, simulate two users in the lump and divide Not by envelope waveform after shock filter.It can be seen that in the case of when two users jump, pattern is orthogonal, Respective impact envelope will not be overlapping, and obtained judgment variables will not be interfered.

4, embodiment

As a example by two users, simulate MPPSK time hopping modulation user 1 and the bit error rate of user 2 respectively, and With numbers non-jumping time the MPPSK bit error rate contrast, investigate use time hopping modulation modulation The error performance of MPPSK signal.The common modulation parameter of two users is carrier frequency f_c=ω_c/ 2 π=10MHz, M=8, K=2, N=56, Q=4, θ=π, r_g=0, during the jumping of user 1, pattern is t₁=2,0,3,1}, During the jumping of user 2, pattern is t₂=0,3,1,2}, additive white Gaussian noise (AWGN) channel.Simulation result is such as Shown in Fig. 8.

It can be seen that two use can normally demodulate per family, when bit error rate performance and non-jumping, 8PPSK is close.Say In the case of during bright jumping, pattern is orthogonal, the MPPSK signal after Time-hopping Modulation does not lose error performance, Thus multicast can be realized, multiple users share Same Physical channel without interfering, and demonstrate this The feasibility of invention and effectiveness.

The schematic description and description of the present invention is used for explaining the present invention, and be not intended that the present invention is improper Limit.For a person skilled in the art, the present invention can have various modifications and variations.All in the present invention Spirit and principle within, any modification, equivalent substitution and improvement etc. made, should be included in the present invention's Within protection domain.

Claims (4)

1. The time hopping modulation implementation method of 1.MPPSK modulation, it is characterised in that: transmitting terminal is enterprising at time domain continuous print sinusoidal carrier Row modulation, it is identical and mutually the most not that each symbol period of M system MPPSK modulation is divided into the persistent period equal with number of users Overlapping chip, each chip is divided into that M-1 persistent period be identical and the time slot of non-overlapping copies, uniquely distributes according to user Jumping time pattern and symbol to be sent, the respective symbol cycle selects certain time slot generation phase hit of one of them chip, Other parts in addition to saltus step are all sinusoidal wave, thus obtain the transmitting signal of symbol to be sent；Reception signal is passed through by receiving terminal Take envelope after shock filter, according to pattern when propagation delay time and identical jumping, decision region is accurately positioned in symbol period Certain time-hopping code sheet on, and the envelope value of M-1 time slot in chip is taken out as judgment variables, utilizes judgment variables to examine Measure transmitted symbol.
2. The time hopping modulation implementation method of MPPSK modulation the most according to claim 1, it is characterised in that: any two user Jumping time pattern orthogonal, avoid colliding at receiving terminal with other transmitting terminals from the time, it is achieved multiple access access.
3. The time hopping modulation implementation method of MPPSK the most according to claim 1 or claim 2 modulation, it is characterised in that: pattern during jumping Controlled by a PN code sequence, it is assumed that { t_nPattern, then t when being to be assigned exclusively to the jumping of user n_nFor meeting 0≤t_n≤ Q-1's Integer value, Q is the number of chips of symbol period.
4. The time hopping modulation implementation method of MPPSK the most according to claim 1 or claim 2 modulation, it is characterised in that: described impact Wave filter is made up of a pair conjugation zero point and at least two pairs of conjugate poles, and its signal carrier frequency is higher than zero frequency but less than all limits Frequency, and zero frequency and the close degree of pole frequency, at least up to the 10 of signal carrier frequency^-3Magnitude, this wave filter is used for will Carrier phase saltus step in MPPSK modulated signal is converted into parastic modulation impact.