CN103647737A - Time-hopping multi-access achieving method for m-ary position phase shift keying (MPPSK) modulation - Google Patents

Abstract

The invention discloses a time-hopping multi-access achieving method for m-ary position phase shift keying (MPPSK) modulation. Multi-user communication of MPPSK modulation can be achieved through the time-hopping multi-access achieving method. A sending end divides symbol periods of MPPSK into a plurality of chips which are not overlapped with each other, every user selects one chip through a uniquely distributed time-hopping pattern, and phase jump occurs at some time slot; and a receiving end tracks and receives signals having passed through an impact filter by utilizing a time-hopping pattern the same as a target user. When the time-hopping patterns of two random users are in orthogonality, multiple users in MPPSK modulation do not conflict with each other, and sharing of an identical physical channel by a plurality of users becomes possible.

Description

Multiple access implementation method during the jumping of MPPSK modulation

Technical field

The present invention relates to the information modulation and demodulation in digital communication, relate in particular to a kind of method of utilizing Time-Hopping to realize MPPSK modulation multiple access communication, belong to the technical field of high-efficiency digital communication.

Background technology

Multiple access while 1, jumping

In wireless communication system, multiple access technique makes a plurality of users share same channel becomes possibility, and multiple access performance is related to user capacity and the efficiency of transmission of system, is an important indicator weighing wireless communication system.The pattern when transceiver that multiple access during jumping (THMA) specification requirement intercoms mutually adopts same jumping, pattern control impuls launch time when sender utilization is jumped, the probability that Avoids or reduces and other users bump at receiving terminal from the time, thereby guarantee the reliability of user-to-user information transmission, realize multiple access access.The signal that during jumping, multiple access forms has the sparse property of time domain, in conjunction with the minimum feature of MPPSK modulation signal duty ratio, can be when jumping multiple access technology for the multi-user communication of MPPSK modulation.

2, MPPSK modulation

Multielement positional phase shift keying (MPPSK:M-ary Position Phase Shift Keying) modulation (is shown in " multielement positional phase shift keying modulation and demodulation method ", patent of invention number: be ZL200710025202.1) a kind ofly can all carry out the two-dimensional modulation of keying to position and phase shift, mainly utilize the diverse location of information sequence offset of sinusoidal carrier wave in a code-element period to carry out phase shift keying.(see " unified orthogonal binary shifted key modulation and demodulation method ", the patent No.: ZL200710025203.6) compare, in identical code-element period, MPPSK modulation can be transmitted more information data with EBPSK.

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

$f_k\left(t\right)=\left\{\begin{array}{ccc}\sin {\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="0"\; label="c\; t"\; filenames="HDA0000442514730000012.png,HDA0000442514730000021.png"\; state="\{\{state\}\}">c</figure-callout>}}t& 0\&le;t<\mathrm{NT}& k=0\\ \left\{\begin{array}{ccc}\sin {\mathrm{\&omega;}}_{\mathrm{<figure-callout\; id="0"\; label="c\; t"\; filenames="HDA0000442514730000012.png,HDA0000442514730000021.png"\; state="\{\{state\}\}">c</figure-callout>}}t& 0\&le;t\&le;(k-1)\mathrm{KT}& \\ \sin ({\mathrm{\&omega;}}_{c}t+\mathrm{\&theta;})& (k-1)\mathrm{KT}<t<(k-r_g)\mathrm{KT},0<\mathrm{\&theta;}\&le;\mathrm{\&pi;}& 1\&le;k\&le;M-1\\ \sin {\mathrm{\&omega;}}_{c}t& (k-r_g)\mathrm{KT}\&le;t<\mathrm{NT}& \end{array}\right.& & \end{array}\right.---\left(1\right)$

Wherein, and k}={0,1 ..., the information sequence of M-1} for sending, ω _cfor carrier angular frequencies, T=2 π/ω _cfor carrier cycle, 0≤r _g< 1 is the symbol protection Separation control factor, and N is the carrier cycle quantity that symbol period is contained, and K represents the carrier cycle quantity that phase hit is lasting.By M, N, K and θ and r _gjointly formed " modulation parameter " that change signal bandwidth, efficiency of transmission and demodulation performance.As M=2 and r _g=0 o'clock, MPPSK was degenerated to EBPSK, therefore to a certain extent, can claim that MPPSK is the EBPSK of expansion, and coverage is wider, and uses more flexible.

3, shock filter

In order to improve the availability of frequency spectrum, " 0 " code element of MPPSK modulation signal is very little with the difference of " non-zero " code element in time domain, and in demodulator for outstanding this difference, we are in patent of invention " for strengthening the impact filtering method of asymmetric binary modulating signal " (patent of invention number: ZL200910029875.3." impact filtering " that the application's book is related, source is all this, below no longer statement) in, a kind of special infinite impulse response (IIR) digital filter was once disclosed, can give prominence to the phase hit of MPPSK/EBPSK modulation signal.This filter, by the precipitous trap-selecting frequency characteristic in its passband center, can be converted into the phase hit of MPPSK/EBPSK modulation signal obvious and strong parasitic amplitude modulation and impact, and output signal-to-noise ratio is significantly improved.

Summary of the invention

While the object of the invention is jumping, multiple access technology is applied to MPPSK modulation, and multiple access implementation method when a kind of jumping of MPPSK modulation is provided can allow the multiple users share Same Physical channel of MPPSK system, realizes the multiple access communication of MPPSK modulation.

Technical scheme of the present invention is as follows:

Multiple access implementation method during the jumping of a kind of MPPSK modulation, it is characterized in that: transmitting terminal is modulated on the continuous sinusoidal carrier of time domain, each symbol period of M system MPPSK modulation is divided into the chip of identical and non-overlapping copies of the duration equal with number of users, each chip is divided into the time slot of identical and non-overlapping copies of M-1 duration, pattern and symbol to be sent during according to the jumping of the unique distribution of user, in respective symbol, in the cycle, select certain time slot generation phase hit of one of them chip, other parts except saltus step are all sinusoidal wave, obtain thus transmitting of symbol to be sent, receiving terminal is got envelope by reception signal after by shock filter, when during according to propagation delay time and identical jumping, pattern accurately navigates to decision region certain in symbol period and jumps on chip, and the envelope value of the time slot of the M-1 in chip is taken out as judgment variables, utilize judgment variables to detect transmitted symbol.

The further technical scheme of the present invention is: pattern quadrature during any two users' jumping, from the time, avoid bumping at receiving terminal with other transmitting terminals, and realize multiple access access.

Wherein, during jumping, pattern is controlled by a PN code sequence, supposes { t _npattern during for unique jumping of distributing to user n, tn is for meeting 0≤t _nthe integer value of≤Q-1, the number of chips that Q is symbol period.

Beneficial effect of the present invention:

Multiple access implementation method during the jumping of MPPSK of the present invention modulation, during by jumpings, multiple access technology combines with MPPSK modulation technique, can realize the multiple access communication that MPPSK modulates.The pattern when transceiver of intercommunication adopts same jumpings mutually, when sender utilization is jumped, pattern is controlled the time slot that saltus step occurs, pattern tracking reception during the receiver utilization jumping identical with targeted customer.Pattern quadrature during any two users' jumping, has avoided the collision occurring at receiving terminal with other users from the time, thereby has guaranteed the reliability of user-to-user information transmission, realizes multiple access access.The inventive method not only band efficiency is high, and has realized a plurality of users to share Same Physical channel and do not interfere with each other, and has improved power system capacity and efficiency of transmission.

Accompanying drawing explanation

The transmitter block diagram of modulation when Fig. 1 is MPPSK jumping.

The diagrammatic representation of modulation when Fig. 2 is MPPSK jumping.

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

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

The diagrammatic representation of input judgement when Fig. 5 is MPPSK jumping.

Fig. 6 is the diagrammatic representation of MPPSK two users signal while jumping.

Fig. 7 is the impact envelope diagram of MPPSK two users signal while jumping.

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

Embodiment

In order to better understand technological means of the present invention, and can be implemented according to the content of specification, below with preferred embodiment of the present invention and coordinate accompanying drawing to be elaborated to technical solution of the present invention.In the accompanying drawings:

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

Modulation when 1, MPPSK jumps

From the expression formula (1) of MPPSK, can find out, MPPSK modulation signal shows as the saltus step that has occurred the utmost point short time in a series of sine wave in time domain.MPPSK modulated process can be regarded as some change of waveform phase constantly in a succession of sine wave.While take θ=π, be example, can be expressed as-2sin of saltus step waveform ω _ct and sinusoidal signal sin ω _cthe stack of t.

When thus, MPPSK jumps, the modulation of multiple access can operate on a series of sine wave.The principle that realizes of MPPSK time-hopping systems transmitter (is established θ=π) as shown in Figure 1, at a symbol period T _s=NT is in second, the b=log that user n is to be sent ₂m position message is loaded in M system symbol buffer.We are shown k the symbol table of this b position _n, and k _n∈ 0,1 ..., M-1}.M system symbol k _ntemporarily be stored in buffer, wait for the arrival of own sending time slots.For each the M system symbol in Fig. 1, transmitter produces a time domain pulse P[t-(i-1) T _s], wherein i represents code element sequence number, i=1, and 2,3, P (t) is defined in [0, T _j) upper, and be normalized to

t wherein _j=(1-r _g) KT, be the saltus step duration of MPPSK modulation.{ t in Fig. 1 _npattern, wherein t when distributing to PN (Pseudo-Noise, the pseudo noise) code of user n and jump _nfor meeting 0≤t _nthe integer value of≤Q-1, the number of chips that Q is each symbol period; The PN code sequence that when PN code is jumped, pattern is produced by PN code generator is controlled.Each symbol period is divided into Q chip, and each chip duration is Tc second, and during jumping, pattern has increased a time shift that depends on PN code to the time domain pulse in each M system symbol, and this time shift is a discrete time value t _nt _c, meet 0≤t _nt _c≤ (Q-1) T _c.According to this time shift, can obtain signal pulse P[t-(i-1) T _s-t _nt _c].

In MPPSK time-hopping systems, each chip duration is further divided into M-1 time slot, and each slot length is T _h=KT second.During jumping, pattern has been determined the chip that saltus step occurs, and M system symbol k _ndetermined the time slot that in this chip, saltus step occurs.As shown in fig. 1, be divided into two kinds of situations, if k _n=0, by pulse zero setting; If k _n≠ 0, by pulse daley (k _n-1) T _hsecond, produce a time domain pulse P[t-(i-1) T _s-t _nt _c-(k _n-1) T _h].Afterwards, resulting pulse diagonal frequencies is ω _cwaveform-2sin ω _ct modulates, then with sinusoidal wave sin ω _ct is superimposed.I M system symbol of user n transmits and can be expressed as

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

(i-1) T wherein _s≤ t < iT _s.Can find out, formula (2) has identical spatial structure with formula (1),, when transmitting symbol 0, only has sinusoidal wave sin ω in symbol period _ct; While launching non-zero symbol, only at very short become-sin of period introskip ω _ct, other period is all sinusoidal wave sin ω _ct, when MPPSK jumping is described, modulation has kept the modulation signature of MPPSK.Different from general MPPSK modulation, pattern when modulation has added jumping when MPPSK jumps, saltus step position depends on pattern while jumping, and the position of same M system symbol saltus step in symbol period can be different.

When MPPSK jumps, modulation realizes principle and can further illustrate by the example shown in Fig. 2.In this example, suppose M=8, each chip lengths T _cinterior timeslot number is M-1=7, and the number of chips of each symbol period is Q=4.Suppose to send 6 M system symbols corresponding to 6 symbol periods, symbol sebolic addressing to be sent is { k _n}={ 5,2,0,7,4,3}, when it is jumped, pattern is t _n=2,0,3,1}, and during jumping pattern circulate in time and extend to 2,0,3,1,2,0,3,1,2,0 ....

Therefore,, according to formula (2), the set that can release saltus step time slot is in upper/lower positions:

[0T _s+2T _c+4T _h,0T _s+2T _c+5T _h)，[1T _s+0T _c+1T _h,1T _s+0T _c+2T _h)

In the 3rd symbol period, there will not be saltus step, [3T _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 shown in Figure 2, saltus step time slot represents with black thick stick accordingly, and saltus step occurs in saltus step time slot, and other period except saltus step is all sinusoidal wave sin ω _ct, wherein the 3rd symbol is 0, there will not be saltus step in symbol period.

The detection of signal when 2, MPPSK jumps

When MPPSK jumps, signal and common MPPSK modulation signal do not have any essential distinction in time domain, thereby still can detect judgement by shock filter.This shock filter consists of a pair of conjugation zero point and at least two pairs of conjugate poles, and its signal carrier frequency is higher than zero frequency but lower than all pole frequencies, and the close degree of zero frequency and pole frequency at least reaches 10 of signal carrier frequency ^-3magnitude, this filter impacts for the carrier phase saltus step of MPPSK modulation signal being converted into parasitic amplitude modulation.As shown in Figure 3, when MPPSK jumps, signal is by after shock filter, and phase hit is converted into amplitude overshoot, after the absolute value of impact filtering output is got envelope, can give prominence to modulation intelligence.

Different, pattern when signal need be by the jumping identical with transmitter when detecting MPPSK and jumping, the chip that phase hit is occurred positions, thereby obtains this user's sequence of symhols.Based on shock filter, while jumping for detection of MPPSK, the receiver block diagram of signal as shown in Figure 4.Supposing that receiver has been realized receives the synchronous of signal, therefore can obtain propagation delay time τ _naccurate estimation.In addition, suppose in receiver that local PN generator has produced a copy of pattern while jumping, pattern during with jumping identical in transmitter.According to propagation delay time τ _n, in i symbol, pulse generator is that i symbol produces a time domain pulse P[t-(i-1) T _s-τ _n]; Pattern value t when pattern generator output is jumped accordingly during jumping _n, time domain pulse daley t _nt _csecond, become P[t-(i-1) T _s-t _nt _c-τ _n].Then 0T is passed through respectively in this pulse _h, 1T _h..., (M-2) T _hafter postponing, multiply each other with the envelope that receives the impact filtering output absolute value of signal r (t), obtain 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 while jumping _n, when decision region is accurately navigated to certain in symbol period and jumps on chip, and using the envelope value taking-up of M-1 time slot in this chip as judgment variables.Due to after shock filter, the envelope value at phase hit place is greater than other position, as long as therefore suitable thresholding is set, utilizes a resulting M-1 judgment variables, just can detect transmitted M system symbol.Do not having under the condition of noise jamming, { judgment variables that 5,2,0,7,4,3} is corresponding can be expressed as shown in Fig. 5, wherein A to send symbol with 68 systems _ntfor decision threshold, sending symbol is 0 o'clock, and resulting judgment variables is all less than threshold value; Sending symbol is not 0 o'clock, and the judgment variables that the transmission symbol of only take is sequence number is greater than threshold value.

In there is the actual scene of noise jamming, we just choose maximum one and detect judgement from these judgment variables.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, this symbol is 0; If this maximum is greater than decision threshold, the sequence number of judgment variables corresponding to maximum is exactly the value of symbol of output.

3, the multiple access during jumping of MPPSK modulation

When MPPSK jumps in multiple access communication, each user is pattern dynamic assignment time slot during by distinctive jumping, and while supposing any two users' jumping, pattern has orthogonality, so can receiving terminal during by unique jumping pattern distinguish a plurality of users.

Take 4 users as example, each symbol period T _sbe divided into 4 chips, during jumping, pattern is according to dividing timing shown in table 1, and multi-user interference can be avoided, and MPPSK multiple access communication can not clash.

When table 1 is jumped, pattern distributes

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

When MPPSK jumps, multiple access principle can further be understood by following legend.Signal when Fig. 6 has provided in 6 continuous symbols the jumping that two users send.Except public parameter M=8, outside Q=4, during user 1 jumping, pattern is t ₁=2,0,3,1}, and pattern is t during user 2 jumping ₂={ 0,3,1,2}; The 8 system symbols that user 1 sends are k ₁=5,2,0,7,4,3, that user 2 sends is k ₂=3,2,7,5,4,6.The saltus step time slot of black thick stick representative of consumer 1, the saltus step time slot of slash representative of consumer 2, as can see from Figure 6, and two users of pattern while having adopted quadrature to jump, even if send identical symbol in the prosign cycle, saltus step time slot can not bump yet.

Suppose to adopt synchronous transmission, i.e. propagation delay time τ ₁=τ ₂=... if wish demodulation nth user's signal, pattern { t when receiver need to utilize nth user's jumping _n, according to the reception block diagram shown in Fig. 4, detect.

Emulation U1, when U2 two users jump, multi-address signal is by the envelope waveform after shock filter, as shown in Figure 7.Stack situation for the ease of the judgment variables of investigating two users in time domain, in the lump emulation two users respectively by the envelope waveform after shock filter.Can find out, when two users jump, pattern quadrature in the situation that, impact envelope separately can be not overlapping, and resulting judgment variables can not be interfered.

4, embodiment

Take two users as example, respectively emulation MPPSK multiple access user 1 and user's 2 while jumping the error rate, and the MPPSK error rate contrasts during with non-jumpings of numbers, investigates the error performance that adopts the MPPSK signal that while jumping, multiple access is modulated.Two users' common modulation parameter is carrier frequency f _c=ω _c/ 2 π=10MHz, M=8, K=2, N=56, Q=4, θ=π, r _g=0, during user 1 jumping, pattern is t ₁={ 2,0,3,1}, during user 2 jumping, pattern is t ₂={ 0,3,1,2}, additive white Gaussian noise (AWGN) channel.Simulation result as shown in Figure 8.

Can find out, two use normally demodulation per family, when bit error rate performance and non-jumping, 8PPSK is close.Illustrate in the situation of pattern quadrature while jumping, the MPPSK signal during through jumping after modulation does not lose error performance, thereby can realize multicast, and a plurality of users share Same Physical channel and can not cause interference, have verified feasibility of the present invention and validity.

Schematic description and description of the present invention is used for explaining the present invention, does not form inappropriate limitation of the present invention.For a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (5)

1. Multiple access implementation method during the jumping of 1.MPPSK modulation, it is characterized in that: transmitting terminal is modulated on the continuous sinusoidal carrier of time domain, each symbol period of M system MPPSK modulation is divided into the chip of identical and non-overlapping copies of the duration equal with number of users, each chip is divided into the time slot of identical and non-overlapping copies of M-1 duration, pattern and symbol to be sent during according to the jumping of the unique distribution of user, in respective symbol, in the cycle, select certain time slot generation phase hit of one of them chip, other parts except saltus step are all sinusoidal wave, obtain thus transmitting of symbol to be sent, receiving terminal is got envelope by reception signal after by shock filter, when during according to propagation delay time and identical jumping, pattern accurately navigates to decision region certain in symbol period and jumps on chip, and the envelope value of the time slot of the M-1 in chip is taken out as judgment variables, utilize judgment variables to detect transmitted symbol.
2. 2. multiple access implementation method during the jumping of MPPSK modulation according to claim 1, is characterized in that: pattern quadrature during any two users' jumping, from the time, avoid bumping at receiving terminal with other transmitting terminals, and realize multiple access access.
3. 3. during according to the jumping of MPPSK modulation described in claim 1 or 2, multiple access implementation method, is characterized in that: during jumping, pattern is controlled by a PN code sequence, supposes { t _npattern during for unique jumping of distributing to user n, tn is for meeting 0≤t _nthe integer value of≤Q-1, the number of chips that Q is symbol period.
4. 4. multiple access implementation method during the jumping of MPPSK according to claim 1 and 2 modulation, is characterized in that: transmitting of i M system symbol of user n is expressed as:

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

   Wherein, ω _cfor sinusoidal carrier angular frequency, { k _nexpression user n symbol sebolic addressing to be sent, P[t-(i-1) T _s] represent that transmitter is the time domain pulse that i M system symbol produces, T _sfor symbol period, { t _npattern during for unique jumping of distributing to user n, t _nfor meeting 0≤t _nthe integer value of≤Q-1, the number of chips that Q is symbol period, T _cfor each chip duration, T _hfor the duration of each time slot.
5. 5. multiple access implementation method during according to the jumping of MPPSK modulation described in claim 1 or 2, it is characterized in that: described shock filter consists of a pair of conjugation zero point and at least two pairs of conjugate poles, its signal carrier frequency is higher than zero frequency but lower than all pole frequencies, and the close degree of zero frequency and pole frequency at least reaches 10 of signal carrier frequency ^-3magnitude, this filter impacts for the carrier phase saltus step of MPPSK modulation signal being converted into parasitic amplitude modulation.

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