CN101479973B - A time division multiplexing method and system - Google Patents

Abstract

A time division multiplexing method and system, it uses multiple symbols to parallelly transmit data serials in time domain. The method includes the steps of: the transmitter generates the transmitting signal with multiple symbols overlapped in the time domain; the receiver detects the received signal in the time domain based on the data serial, according to the one-to-one relationship between the transmitting signal and the temporary waveform of the transmitting signal. Moreover, the present invention provides a time division multiplexing system according to the time division multiplexing method. The present invention also utilizes the overlap to generate a restrict relationship between codes, therefore it effectively improves the frequency spectrum efficiency. Meanwhile, in the random time-varying channel, it can improve the transmission reliability of the system if properly arranged; under the condition of the same signal-to-interference ratio threshold, the frequency spectrum efficiency is much higher than other techniques, such as the high dimensional modulation; and under the condition of the same frequency spectrum efficiency, the overall level of the system and the required signal-to-interference ratio threshold is much lower than other techniques, such as the high dimensional modulation.

Description

A kind of time division multiplexing method and system

Technical field

The present invention relates to digital communicating field, relate in particular to a kind of hyperfrequency spectrum efficiency, effective, reliable, practical, brand-new multiplex technique, specifically is a kind of time division multiplexing method and system.

Background technology

A plurality of International Standards Organization are all in the target of actively inquiring into future mobile communication system: International Telecommunication Union was imagined about 2010; Under high-speed mobile and abominable communication environments, should support peak rate up to 100Mbps; And move and good communication environments should be supported the peak rate of 1Gbps down at low speed, with the needs of realization global personal communication.But the frequency resource that can be used for mobile communication is but very limited, how under extremely limited frequency resource condition, to satisfy the demand of message volume explosive growth, with present technological means even learning concept, suitable difficulty is arranged all.This just requires must be from learning concept and new innovation and the breakthrough of technical realization, makes spectrum efficiency, capacity and the speed of radio communication that the raising of ten times and even hundred times arranged, so as to solving the contradiction of limited frequency spectrum resource and message volume explosive growth.

So-called spectrum efficiency is meant when given system bandwidth, and the maximum (peak value) that each space channel can be supported in the system rate of delivering a letter, its linear module are bps/hertz/antenna (bps/Hz/Antenna).

As everyone knows, the bandwidth of a non-spread spectrum communication system is decided by the length or the symbol rate of its transmission symbol that uses.If symbol lengths is Ts (second); Then its symbol rate is

(symbol/second); Shared system bandwidth is (conspicuous), and wherein α is the rolloff-factor (0＜α≤1) of system filter device.In order to improve the spectrum efficiency of system, people generally adopt the higher-dimension modulation system to claim polynary (many level) modulation system again, so that each symbol load more information bit.For example when binary phase shift keying (BPSK) that adopts the binary modulation mode or binary system amplitude-shift keying modulation signals such as (2ASK); Each symbol can bit of load; Its system spectral efficiency is

bps/conspicuous/antenna; At the four absolute mutually phase-shift keyings (QPSK) of using the quaternary modulation system instead, four phase relative phase shift keyings (DQPSK), π/4 QPSKs (π/4QPSK) or behind the quaternary amplitude-shift keying modulation signals such as (4ASK); Each symbol can load 2 bits; Its system spectral efficiency is doubled than binary modulation, reaches bps/conspicuous/antenna.In general, if adopt M=2 ^Q(M>=2) first modulation signal, each symbol can load Q=log ₂The M bit, the spectrum efficiency of system does

Bps/conspicuous/antenna.This result is by communication engineering circle personage general consistent think impassable " engineering theory circle ", but this " boundary " is apart from real theoretical circles (claiming celestial agricultural boundary again) log ₂(1+SIR) bps/and conspicuous/antenna also has far distance, and wherein SIR is the required thresholding wanted to interfering signal ratio of system, and spectrum efficiency is high more, and the two gap is big more.

The major defect that adopts higher-dimension to modulate the spectrum efficiency that improves system is: along with system spectral efficiency is increasing of signal level number; Requirement to the characteristic of channel, transceiver characteristic is more and more harsher; For example the linearity to channel just has high requirements, and level number M is more, and requirement is harsher.Not only require to have fabulous amplitude-amplitude (being Am-Am) linearity, and require to have fabulous amplitude-phase place (being Am-Pm) linearity; As everyone knows, the linearity of amplifier is good more, and its power efficiency is just low more.In order to guarantee the amplifier good linearty, must adopt complicated adaptive line compensation and technological means such as back-off significantly; In addition, many level modulation technology not only has harsh requirement to the nonlinear distortion degree of system, and the system linearity distortion factor is also had very strict requirement.Engineers and technicians know that actual channel is ever-changing, and its transfer function is difficult to consistent with the ideal characterisitics that the multidimensional modulation signal is expected; And any unfavorable system linear transfer function (amplitude-frequency response, phase-frequency response) all can be easy to cause system's " eye pattern " to merge, after eye pattern merges; Even have no in the system to disturb, the system linearity degree is good again, the signal of varying level also can't be distinguished at all; The rate of delivering a letter is high more, and the signal level number is many more, and " eye pattern " merges more easily.Therefore in the high-speed data communication system that adopts the higher-dimension modulation, all adopt complicated quick self-adapted channel equalization technique or technology such as corresponding signal process and design to avoid system's eye pattern to merge bar none.The problems referred to above are particularly serious in various random time-varying channels, like various radio communications, mobile communication, scatter communication, beyond-the-horizon communication, underwater sound communication, atmosphere optical communication, infrared communication etc.In these communication channels, the variation that the linear transmission function of channel all presents randomness with space, frequency, time, its pace of change is fast sometimes, and technology such as big frequent signaling channel equilibrium of amplitude or signal processing is at a loss as to what to do.Here it is why in the various communication systems that become when being applicable at random few people adopt the reason of the higher-dimension modulation technique of M >=4.But exactly to the communication in these channels, because the usable spectrum resource is very limited, people more pay attention to its spectrum efficiency, and higher requirement is arranged.

Information processing principle in the Back ground Information opinion is told us: any preliminary treatment to channel linearity transfer function

; The theory that will inevitably reduce system is potential channel capacity, should keep its nature.And equilibrium etc. are made pretreated technological means to channel transfer function, will inevitably reduce the latent capacity of channel greatly.Therefore, technology such as higher-dimension modulation is a kind of transmission technology of good spectral efficient anything but.

It is a kind of a plurality of technology that occupy the shared broad time remaining phase of signal codes of narrower time remaining phase that in digital communication, let that the so-called time is cut apart (hereinafter to be referred as the time-division) multiplexing (TDM:Time Division Multiplexing).Be illustrated in figure 1 as the sketch map of conventional time-division multiplex technology.

The time remaining phase of the signal code that respectively is re-used among Fig. 1 (being referred to as time slot width on the engineering) is respectively T1, T2, T3; T4 ..., on engineering, let them occupy identical time slot width usually; Δ T is minimum protection time slot, and the real protection time slot width should be well-to-do.Δ T should add the maximum time amount of jitter of system greater than width transit time of use demultiplexing gate circuit.This is modal time-division multiplex technology.What systems such as the existing overwhelming majority's multi-path digital broadcast system, multi-path digital communication adopted all is this technology.

It is to isolate fully each other in time that maximum characteristics when this technology is applied to digital communication are re-used between the signal code; Will never there be the phase mutual interference; Signal code to being re-used has no restriction, and can there be different widths the symbol duration (time slot width) of each signal, also can be applicable to different communication systems; As long as it is just passable that their time slot phase non-overlapping copies intersects, therefore use the most extensive.But it is this multiplexing, multiplexing own like water off a duck's back to the spectrum efficiency of improving system.

Time division multiplexing tdm generally is applicable to multi-path digital communication, must keep strict synchronized relation between the signal code that it requires to be re-used, and its essence is a kind of parallel transmission mode of a plurality of user data.In multi-path digital broadcasting, multi-path digital communication, obtained using widely at present.When in random time-varying channel, working; Because the cause of channel time diffusion (multipath broadening); The width of its each channel time slot must be wider than the maximum time diffusing capacity that the signal code width adds upper signal channel, otherwise will produce the phase mutual interference between each road signal code of adjacent time-slots.So, when random time-varying channel is worked, the narrowest time slot of TDM system will be subject to the maximum time diffusion of channel.In addition, the spectrum efficiency that the most important thing is the TDM system finally only is decided by the level number of modulation signal in its each time slot, improves its spectrum efficiency, is a quite task of difficulty especially in random time-varying channel.

The intersymbol that overlapping engineering circle is just turned pale at the mention of the tiger between the symbol (claiming intersymbol again) disturbs; Intersymbol interference appears in case people generally believe; Will produce engineering circle so-called " eye pattern merging " phenomenon; The error probability of system will sharply rise, and engineering circle adopts balanced way to eliminate intersymbol interference usually.Relevant prior art has:

Communication journal 1981 (1), author's Li Daoben, file name: the Sequence Detection in two steady time varying channels;

Beijing Post and Telecommunications College's journal 1987 (1), author's Li Daoben, file name: negate interference channel error rate performance is analyzed when homogeneous;

Electronic letters, vol 1991 (6), author's Li Daoben, file name: new error probability circle of symbol-interference channel;

Daoben?Li，Error?Bounds?for?Homogeneous?Random?Time-varying?Intersymbol?Interference?Channels，1988?Beijing?Int.Workshop?on?Inf.Theory，June，1988；

Daoben?Li.，Minimum?Error?Probability?for?Asynchronous?Multiple?Access?Uncorrelated?Facing?Intersymbol?Interference?Channels，1990IEEE?Symp.On?Inf.Theory，San?Diego，1990；

Science Press 2004, author's Li Daoben, file name: the statistics of signal detects and estimation theory;

Forney?G.D.，Lower?Bound?on?the?Error?Probability?in?the?Presence?of?Large?Intersymbol?Interference，IEEE?Trans.Comm.Feb.1972；

Forney?G.D.，Maximum?Likelihood?Sequence?Estimation?of?Digital?Sequence?in?the?Presence?of?Intersymbol?Interference，IEEE?Trans.Inf.Theory.May?1972；

Magee?F.R.，Proakis?J.G.，Adaptive?Maximum?Likelihood?Sequence?Estimation?for?Digital?Signaling?in?the?Presence?of?Intersymbol?Interference，IEEE?Trans.Inf.Theory.1973，IT-19，120-124；

Magee?F.R.，Proakis?J.G.，An?Estimation?of?Upper?Bound?on?Error?Probability?for?Maximum?Likelihood?Sequence?Estimation?for?Channels?Having?for?a?Finite-duration?Pulse?Response，IEEE?Trans.Inf.Theory.1973，IT-19，699-702；

Wyner?A.D.，Upper?Bound?on?the?Error?Probability?for?Detection?with?Unbounded?Intersymbol?Interference，BSTJ?Sept.1975；

Messerchmitt?D.G.，A?Geometric?Theory?of?Intersymbol?Interference.Part?II：Performance?of?the?Maximum?Likelihood?Detector，BSTJ?Nov.1973；

Seshadri?M.，Anderson?J.B.，Asymptotic?Error?Performance?of?Modulation?Codes?in?the?presence?of?severe?Intersymbol?Interference.IEEE?Trans.Inf.Theory，1974，IT-20，479-489；

Verdu?S.，Maximum?Likelihood?Sequence?Detection?for?Intersymbol?Interference?Channels：A?New?Upper?Bound?on?Error?Probability，IEEETrans.Inf.Theory，Jan.1987；

Above-mentioned list of references has proved that all using equilibrium is not best method of reseptance; And studied the optimum reception method when not using balanced i.e. " eye pattern merging "; Some people even also derived error probability circle of this optimum reception mode, but never the people proposed initiatively to utilize the coding bound that interference caused that occurs between the symbol to concern and improved system spectral efficiency.

Summary of the invention

Though provided by the present invention also is a kind of time-division multiplex technology, its purpose is not for multi-path digital communication, and only is in order to improve the spectrum efficiency of system.For multiplex techniques such as conventional time division multiplexing tdm, conventional frequency division multiplexing FDM, orthogonal frequency division multiplex OFDMs, the multiplexing spectrum efficiency of system that can't improve itself, and the present invention leans on the multiplexing spectrum efficiency that increases substantially system.Not only do not need mutual isolation between its each symbol, and can have very strong overlappedly, therefore be referred to as overlapping time division multiplexing (Overlapped Time Division Multiplexing).But is-symbol overlaps not to be regarded as the phase mutual interference among the present invention but to be utilized energetically and forms a kind of new coding bound relation, and overlapping many more, encoding constraint length is long more, and coding gain is high more, and spectrum efficiency is also high more.Under same threshold wanted to interfering signal ratio condition, its available spectrum efficiency will be far above prior aries such as higher-dimension modulation; Otherwise when equal spectrum efficiency, its required thresholding wanted to interfering signal ratio is more much lower than technology such as higher-dimension modulation, and particularly its thresholding wanted to interfering signal ratio improves more in random time-varying channel.This is because the signal code in each time slot of the present invention can be a broadband signal, allows to appear the selectivity decline, so itself can have stronger anti-fading ability.Never the people proposed initiatively to utilize the coding bound that interference caused that occurs between the symbol to concern and improved system spectral efficiency.

One object of the present invention is to provide a kind of time division multiplexing method, through the multiplexing spectrum efficiency of system that makes raising is significantly arranged; And make the required number of levels that can distinguish of system not present the relation of exponential increase with the raising of system spectral efficiency, and just present the relation that algebraically increases, thus reduce requirement greatly to the system linear degree; Described overlapping time, division multiplexing did not have any specific (special) requirements to the transfer function of system etc., thereby avoided in system, using complicated technology such as adaptive channel equalizer; With other compared with techniques, in same spectrum efficiency, equal condition of work following overlapping time of division multiplexing has lower thresholding wanted to interfering signal ratio, thereby practices thrift transmitting power or increase service radius; Make it to the shape, bandwidth etc. of multiplexing signal spectrum do not do any specific (special) requirements; When in random time-varying channel, working especially; Owing to can adopt the signal spectrum that is re-used (rate of delivering a letter that comprises the raising system) of broad; This moment, the change at random of channel can produce the implied diversity effect automatically, improved the transmission reliability of system.The signal spectrum that is re-used is wide more, and diversity gain is high more, and transmission reliability is also high more.

Another object of the present invention is to provide a kind of time division multiplexing system, have significantly through the multiplexing spectrum efficiency that makes system and improve; And make the required number of levels that can distinguish of system not present the relation of exponential increase with the raising of system spectral efficiency, and just present the relation that algebraically increases, thus reduce requirement greatly to the system linear degree; Described overlapping time, division multiplexing did not have any specific (special) requirements to the transfer function of system etc., thereby avoided in system, using complicated technology such as adaptive channel equalizer; With other compared with techniques, in same spectrum efficiency, equal condition of work following overlapping time of division multiplexing has lower thresholding wanted to interfering signal ratio, thereby practices thrift transmitting power or increase service radius; Make it to the shape, bandwidth etc. of multiplexing signal spectrum do not do any specific (special) requirements; When in random time-varying channel, working especially; Owing to can adopt the signal spectrum that is re-used (rate of delivering a letter that comprises the raising system) of broad; This moment, the change at random of channel can produce the implied diversity effect automatically, improved the transmission reliability of system.The signal spectrum that is re-used is wide more, and diversity gain is high more, and transmission reliability is also high more.

The invention provides a kind of time division multiplexing method, utilize a plurality of symbols in time-domain parallel transmission data sequence, this method may further comprise the steps: transmitting terminal forms overlapped the transmitting on time-domain of a plurality of symbols; Receiving terminal carries out detecting by data sequence in the time-domain to received signal according to the one-to-one relationship between transmission data sequence and the transmission data sequence time waveform.

Transmitting terminal forms overlapped the transmitting on time-domain of a plurality of symbols according to design parameter.

Determine described design parameter according to given in advance channel parameter and system parameters.Said design parameter comprises that basic modulation level counts M, basic symbol length

Symbol lengths T _s, mark space Δ T _s, the overlapping tuple K of symbol and frame length T.

The overlapping tuple K of said symbol, mark space Δ T _sAnd symbol lengths T _sBetween satisfy following relation: (K-1) Δ T _s＜T _s≤K Δ T _s

Said symbol lengths

wherein

is a basic symbol length, and Δ is the maximum time diffusing capacity of channel.

Said basic symbol length

wherein Δ is the maximum time diffusing capacity of channel.

Said basic symbol length

is equal to or less than the maximum time diffusing capacity Δ of channel.

Described mark space Δ T _sLess than the coherence time of channel

Frame size

where

is the channel coherence time.

Through reducing mark space Δ T _sIncrease the overlapping tuple K of symbol.

Said channel parameters include the maximum time spread of the channel or channel volume Δ coherence bandwidth

and the maximum frequency of the channel diffusion capacity

or channel coherence time

Described system parameters comprises system bandwidth B, to the requirement and the linearity of spectrum efficiency.

Through increasing system bandwidth B, or utilize and interweave and Methods for Coding, or the raising system rate of delivering a letter, or the method for spread signal frequency spectrum improves the latent frequency diversity tuple of system.

Described transmitting terminal forms overlapped the transmitting on time-domain of a plurality of symbols and may further comprise the steps: the phase wiggles and the orthogonal waveforms that form l=0 road modulation signal envelope waveform with digital form; Described phase wiggles and orthogonal waveforms behind time shift, are formed the homophase envelope waveform and the quadrature envelope waveform of other each modulation signal; With the homophase envelope waveform of said each modulation signal and quadrature envelope waveform in-phase data signal and orthogonal data signal multiplication with each corresponding symbol, obtain each modulation signal through the filtered modulation signal waveform of data-modulated; With described each modulation signal waveform addition, formation transmits.

Described receiving terminal carries out detecting by data sequence in the time-domain to received signal and may further comprise the steps: the reception signal in each frame is formed the receiving digital signals sequence according to the one-to-one relationship between transmission data sequence and the transmission data sequence time waveform; Described receiving digital signals sequence implementation sequence is detected, to obtain the judgement that is modulated at the modulating data on whole symbols in the said frame length.

Saidly reception signal in each frame is formed the receiving digital signals sequence may further comprise the steps: it is synchronous to form symbol time at receiving terminal to received signal; According to sampling theorem, the reception signal in each frame is carried out digitized processing.

Described digitized processing is carried out at intermediate frequency, or carries out in base band.

Described Sequence Detection is a Maximum likelihood sequence detection when each sequence equiprobability, when each sequence unequal probability, is the maximum a posteriori probability Sequence Detection.

Described described receiving digital signals sequence implementation sequence is detected may further comprise the steps: the plural convolutional encoding model of making overlapping time division multiplex system; List whole states of overlapping time division multiplex system; Make the trellis structure of overlapping time division multiplex system, and list the coding output of each branch road; For each stable state is prepared two memories; In said trellis structure, search out the path with receiving digital signals sequence minimum Eustachian distance or weighting minimum Eustachian distance, the corresponding data sequence in this path is conclusive judgement output.

Described plural convolutional encoding model of making overlapping time division multiplex system may further comprise the steps: actual channel is measured, found out the valuation that receives complex envelope in the distinct symbols time interval; Utilize the valuation of described reception complex envelope to form the tap coefficient in the overlapping time division multiplex system channel model.

Described actual channel is measured, found out the valuation that receives complex envelope in the distinct symbols time interval and use special pilot signal measurement; Or utilize the information of having adjudicated through the mode of received signal computing is calculated valuation; Or get above the two combination; Or find the solution valuation with blind estimating method.

Whole states of said overlapping time division multiplex system comprise initial condition, preceding transition state, stable state, back transition state and end-state.

The described surviving path memory of preparing in two memories for each stable state is used to store the surviving path that arrives said state; Euclidean distance memory or weighted euclidean distance memory are used to store the surviving path of the said state of arrival and the Euclidean distance or the weighted euclidean distance of receiving digital signals sequence.

Described transition state can be used the memory of arbitrary stable state.

The described path that in said trellis structure, searches out with receiving digital signals sequence minimum Eustachian distance or weighting minimum Eustachian distance may further comprise the steps: step 1, the path Euclidean distance that makes start node (l=0) state or weights Euclidean distance are zero; Step 2, calculate l (l=1 ..., L-K+1) all the state S in the individual node calculate its all branch road code signal and branch road Euclidean distance or weighted euclidean distance receiving digital signals of each bar from last state transitions to said state S; Step 3, branch road Euclidean distance or branch road weighted euclidean distance and they that will arrive this state to each state S set out separately the path Euclidean distance or the addition of weights Euclidean distance of state form new one or more paths Euclidean distance or weights Euclidean distance; If a plurality of described path Euclidean distances or weights Euclidean distance are arranged; Then from wherein selecting reckling; As path Euclidean distance or the weights Euclidean distance of l node state S, upgrade and deposit in Euclidean distance memory or the weighted euclidean distance memory of said state S.Step 4, at node l, each state S is found out its path Euclidean distance or the pairing surviving path of weights Euclidean distance, upgrade the surviving path memory deposit this state S in; Step 5, next node is repeated above-mentioned steps one to step 4, until the L+K-2 node, this moment, surviving path was only remaining one, and then the pairing data sequence of this surviving path is conclusive judgement output.

In calculating, check the surviving path memory of each state at any time, in case in the path of finding to keep identical initial part is arranged, then that this is identical initial part is as judgement output.

Still not judgement is then adjudicated by force when described surviving path memory is filled with, and promptly exports the initial bit that minimum range is arranged as judgement.

Still the majority logic judgement is then carried out in not judgement when described surviving path memory is filled with, and promptly exports the majority in each surviving path initial bit as judgement.

Described path Euclidean distance memory or weights Euclidean distance memory are only stored relative distance; Even path Euclidean distance or weights Euclidean distance minimum or the maximum are zero distance; The path Euclidean distance memory of other each state or weights Euclidean distance memory are only stored relative Euclidean distance or relative weighted euclidean distance, and said relative Euclidean distance or relative weighted euclidean distance are meant the difference with said path Euclidean distance or weights Euclidean distance minimum or the maximum.

Described Sequence Detection is a Maximum likelihood sequence detection.

The present invention also provides a kind of time division multiplexing system, and said system comprises transmitter and receiver; Wherein transmitter comprises: overlapping time division multiplexing modulating unit is used to form overlapped the transmitting on time-domain of a plurality of symbols; Transmitter unit is used for said transmitting is transmitted into receiver; Receiver comprises: receiving element is used to receive the signal that said transmitter unit is launched; The Sequence Detection unit is used for carrying out to received signal detecting by data sequence in the time-domain.

Described overlapping time division multiplexing modulating unit comprises: digital waveform generator is used for phase wiggles and orthogonal waveforms with first modulation signal envelope waveform of digital form formation; Shift register, the phase wiggles and the orthogonal waveforms of first modulation signal envelope waveform that is used for digital waveform generator is produced carry out time shift, with homophase envelope waveform and the quadrature envelope waveform that produces other each modulation signal; Serial-parallel converter is used for the data sequence of serial input is converted into the parallel in-phase data signal and the orthogonal data signal of corresponding each modulation signal; Multiplier; The homophase envelope waveform and the quadrature envelope waveform that are used for the modulation signal that each in-phase data signal of said serial-parallel converter output and orthogonal data signal is corresponding with each multiply each other, with obtain each modulation signal through the filtered modulation signal waveform of data-modulated; Adder, be used for each modulation signal of multiplier output through the filtered modulation waveform addition of data-modulated, transmit with formation.

Said transmitter can also comprise spectrum-spreading unit, is used for increasing in case of necessity overall system bandwidth.

Said transmitter can also comprise interleave unit and coding unit, is used for improving in case of necessity the latent frequency diversity or the latent time diversity tuple of system, to improve the transmission reliability of system.

Said receiver also comprises pretreatment unit, is used to form synchronous receiving digital signals sequence complete in each frame.

Said pretreatment unit comprises: lock unit, and it is synchronous to be used in receiver, forming symbol time to received signal; Pilot cell is used for channel parameter is measured; The digitized processing unit is used for the reception signal in each frame is carried out digitized processing.

Described Sequence Detection unit comprises: the analytic unit memory, and be used to make the plural convolutional encoding model and the trellis structure of overlapping time division multiplex system, and list whole states of overlapping time division multiplex system, and storage; Comparator is used for the trellis structure according to the analytic unit memory, searches out the path with receiving digital signals minimum Eustachian distance or weighting minimum Eustachian distance; The surviving path memory of stable state S; Be used to store Euclidean distance memory or the weighted euclidean distance memory of the surviving path stable state S that arrives said stable state S, be used to store the surviving path of the said stable state S of arrival and the Euclidean distance or the weighted euclidean distance of receiving digital signals sequence; Wherein, stable state S is any in said whole stable state.

Each state has a surviving path memory and Euclidean distance memory or weighted euclidean distance memory, and transition state can be used the memory of arbitrary stable state.

Described surviving path memory length be 4 * K (4K) to 5 * K (5K), wherein K is overlapping tuple.

Described surviving path memory length is shorter or longer than 5K than 4K, and wherein, K is overlapping tuple.

Described Euclidean distance memory or weighted euclidean distance memory are only stored relative distance.

Beneficial effect of the present invention is; Provide a kind of novel time division multiplexing that utilizes to increase substantially the brand-new learning concept and the correlation technique of system spectral efficiency; It need not do any preliminary treatment to the transfer function of channel; Not only can not reduce channel capacity, the actual capacity that can make system on the contrary is the channel capacity of approximation theory more.With in short, the invention provides one and increase substantially the communication system spectrum efficiency, effective, reliable, practical, brand-new time-division multiplex technology.

Description of drawings

Fig. 1 is conventional time division multiplexing sketch map;

Fig. 2 is overlapping time division multiplexing principle sketch map;

Fig. 3 is overlapping time-multiplexed ordinary circumstance sketch map;

Fig. 4 receives signal schematic representation in the overlapping time division multiplex system of K=3;

Fig. 5 for overlapping time division multiplex system the time become plural convolutional encoding model;

Fig. 6 is the tap coefficient in the shift register channel model in the overlapping time division multiplex system;

Fig. 7 is the tree graph of the input-output relation of the overlapping time division multiplex system of K=3;

Fig. 8 is node state transfer relationship figure;

Fig. 9 A is that the trellis structure (Trellis) of K=3 is schemed preceding half section;

Fig. 9 B is trellis structure (Trellis) the figure second half section of K=3;

The state diagram of overlapping time division multiplex system when Figure 10 is K=3;

Figure 11 is the testing process of Maximum likelihood sequence detection (MLSD) algorithm;

Figure 12 is overlapping time division multiplex system transmitter block diagram;

Figure 13 is a time division multiplex system block diagram of the present invention;

Figure 14 is the block diagram of the overlapping time division multiplexing modulating unit of transmitter of the present invention;

Figure 15 is another design frame chart of transmitter of the present invention;

Figure 16 is the pretreatment unit block diagram of receiver of the present invention;

Figure 17 is the Sequence Detection unit block diagram of receiver of the present invention.

Embodiment

To be described with reference to the accompanying drawings basic principle of the present invention, mathematical description, Maximum likelihood sequence (MLSD) detection below (because the maximum a posteriori probability detection only is that the sequence of different prior probabilities is implemented different weightings; Do not have essential distinction with MLSD, repeat no more) and embodiment.

Basic principle of the present invention at first is described.

For the sake of simplicity, in discussion subsequently, do not comprise space channel.Each signal code that well-known traditional Time Division Multiplexing requires to be re-used is isolated in time-domain fully each other, makes to have no between them to disturb, and each signal that is re-used can use any communication and modulation system independently.

Obviously; If make the signal code that is re-used in time-domain, present mutual covering and overlapping; Just can further improve the spectrum efficiency of system, but people generally believe that this will cause the adjacent serious phase mutual interference of generation between the signal code that is re-used; As shown in Figure 2, there are three symbols in time-domain, to overlap among the figure.Because symbol overlapped, any symbol is wherein carried out the serious interference that demodulation all will receive other adjacent-symbols by conventional method, it is absolutely not therefore carrying out right demodulation by conventional method.But scrutinize Fig. 2 again, suppose that the symbol intervals of three be re-used signal A, B, C among the figure is T _sSecond, the interval between them, promptly the time shift amount does relatively

Second, that is to say that the symbol of these three signals overlaps fully.For the sake of simplicity, suppose that the shape of three signal A that are re-used, B, C symbol is in full accord, phase characteristic is zero entirely, and modulation system all adopts the positive counter modulation of binary, and symbol lengths is T _sSecond, each road modulation signal bandwidth is B ₀Conspicuous, the bandwidth after their stacks also is B ₀Conspicuous, but the symbol time duration elongatedly do

, three signals are synchronous fully.Because their symbol overlaps, and all will receive the interference of adjacent other symbols, by conventional method, right demodulation is absolutely not.But the present invention does not handle each symbol not isolatedly, but with the unified consideration of these three symbols, at this moment situation is just different fully, because at certain 5T _sIn/3 time periods, the data that symbol A, B, C three are transmitted are nothing but one of eight kinds of situation shown in the table 1:

Table 1

And corresponding reception signal is respectively eight kinds of D, E, F, G, H, I, J, K among Fig. 2 when disregarding noise, and its data and waveform are one to one fully.Equally, for any other overlapping tuple, can check, on mathematics, also can prove fully simultaneously, its data combination (sequence) also necessarily has one-to-one relationship with waveform.In the ordinary course of things, if the symbol intervals of each road signal that is re-used is T _sSecond, T here _sShould take into account the All Time broadening factor (like system's timing wander, multipath broadening etc.) in the system, when making overlapping time division multiplexing, the time shift amount is that each mark space is Δ T each other _sSecond, and satisfy

(K-1)ΔT _s＜T _s≤KΔT _s；K＝1，2，...

Promptly have K adjacent-symbol together overlapped, that each symbol transmitted all is M=2 ^QMetamessage, the i.e. equal load Q=log of each symbol ₂The information of M bit, if L this overlapped symbol arranged in the system, it finally is 2 that the data that then transmitted possibly make up ^QL=M ^LKind, also have 2 one to one with it ^QL=M ^LPlant time waveform.Therefore to belong to any waveform just passable as long as find out the data combination that is transmitted at receiving terminal.Though intersymbol time-interleaving has destroyed the waveform of single data symbol itself; Destroy the one-to-one relationship between single data symbol and its time waveform, but do not destroyed the one-to-one relationship between data symbol sequence and its time waveform.The most important theories basis of institute of the present invention foundation that Here it is.Certainly work as M ^LWhen very big, the complexity that how to reduce system is exactly a very important practical problem.The present invention will provide the algorithm of an optimum to address the above problem, and its complexity only is decided by M ^KRather than M ^L

Be illustrated in figure 3 as ordinary circumstance.For the sake of simplicity, the spectrum width of setting each signal code that is re-used is B ₀Conspicuous; Symbol intervals is T _sSecond; Modulation level is counted M=2 ^Q, i.e. each symbol load Q bit; As comparing, when not adopting overlapping time division multiplexing, its bit rate is: Q/T _sBps; Spectrum efficiency is:

Bps/conspicuous.The bandwidth of system still is B after adopting L overlapping symbol ₀Conspicuous, but total symbol lengths but becomes T _s+ (L-1) Δ T _sSecond, L symbol is total to load LQ bit, so always deliver a letter being increased to simultaneously

Bps, so its spectrum efficiency is:

And,

Can find out, overlapped total symbolic number L＞＞K, when promptly L is enough big, the spectrum efficiency of system will improve K (symbolic number that overlaps simultaneously) times, K is big more, the spectrum efficiency of system is also high more.We find the increase along with the symbolic number K that overlaps simultaneously, the proportional raising of the spectrum efficiency of system, but the level number of system do not resemble and is index law the higher-dimension modulation technique and increases, and increases and just be the algebraically rule.For example, work as Q=1, when promptly each subcarrier adopted binary modulation, the level number of the heavy symbol overlapping system of K was K+1, only is linear growth with K, works as Q=2, and promptly each subcarrier adopts M=2 ²During=4 yuan of modulation, the level number of the heavy symbol overlapping system of K homophase I channel is K+1, and the level number of quadrature Q channel also is K+1, and the overall level number of system is (K+1) ², also just being square-law with K increases.Obviously when differentiable level number one timing of channel, adopt the spectrum efficiency of overlapping time division multiplex system will be higher than higher-dimension (many level) transmission system.For example if it can adopt the 64QAM modulation under high-speed mobile condition to certain wireless communication system; Its level number M=64; The level number of homophase I and quadrature Q channel is

and the overlapping tuple K=7 of the overlapping time-division system of QPSK of same I, Q channel level number is arranged; But its each symbol load 14 bits; And the every symbol of 64QAM system load 6 bits only; Its spectrum efficiency has only overlapping time-division system

in general; If original system can be supported the M-QAM modulation; Then under the same level number; Adopt the overlapping tuple

of the overlapping time-division system of QPSK modulation, its spectrum efficiency than M-QAM modulating system exceeds

doubly.

After having introduced basic principle, carrying out overlapping time-multiplexed mathematical description below.

Being without loss of generality, supposing that information source is that equiprobability is memoryless, is T after its symbol duration channel transmission _sSecond, the message of being transmitted is transmitted in time-domain with parallel mode, total L the overlapped symbol of every frame in the system, and each symbol is all occupied B behind modulated filter and channel broadening ₀Conspicuous bandwidth, for the sake of simplicity, suppose the modulation system and the filter complex envelope characteristic of each symbol in full accord, at basic symbol width T _sThere is K symbol overlapped in second.

The complex data sequence that it is transmitted is:

$\tilde{u}=[{\tilde{u}}_0,{\tilde{u}}_1,....,{\tilde{u}}_n,....,{\tilde{u}}_{L-1}];$

In the formula:

l=0; 1; 2 ..., L-1;

I _l, Q _lBe at t ∈ [lT _s, (l+1) T _s], the data message level symbol that promptly its homophase I and quadrature Q channel are transmitted in l symbol time interval.

Its complex envelope that sends signal (is not promptly remembered complex carrier signal frequency expj2 π f _oT) be:

$\sqrt{{2\mathrm{<figure-callout\; id="0"\; label="E"\; filenames="HPA00000676274500012.png,HPA00000676274500051.png"\; state="\{\{state\}\}">E</figure-callout>}}_0}\underset{l=0}{\overset{L-1}{\mathrm{\&Sigma;}}}{\tilde{u}}_l\widetilde{a_0}(t-\mathrm{l\&Delta;}{T}_s)---\left(3\right)$

In the formula: ${\tilde{a}}_0\left(t\right)=0,$ $t\&NotElement;[0,T_s];$

${\&Integral;}_0^{T_s}{\left|{\tilde{a}}_0\left(t\right)\right|}^2\mathrm{dt}=1;$

Be that complex modulated signal envelope, its complex frequency spectrum are sent in normalization Bandwidth be B ₀

$\tilde{A}\left(f\right)=0,f\&NotElement;(-{\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="HPA00000676274500012.png,HPA00000676274500051.png"\; state="\{\{state\}\}">B</figure-callout>}}_0/2,{\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="HPA00000676274500012.png,HPA00000676274500051.png"\; state="\{\{state\}\}">B</figure-callout>}}_0/2);$

f ₀Be carrier frequency: f ₀＞B ₀/ 2, while f ₀T _s＞＞1 or be positive integer;

Δ T _sBe relative time shift amount (intersymbol is at interval), it satisfies:

(K-1)ΔT _s＜T _s≤KΔT _s；

Symbol duration T _sIn should comprise the time explanation factor of channel;

E ₀Be every symbol transmit signal energy.

And the occupied bandwidth of system still is B ₀But, frame length, promptly overlapping total symbol lengths really is:

T＝T _s+(L-1)ΔT _s

L+K-1 rather than L Δ T are arranged in frame length T _s

We will handle together the influence that is caused by channel time diffusion (multipath broadening) in the present invention, suppose that the symbol duration after the diffusion of channel time is Ts second, and then multiple connection is collected mail and number is:

$\tilde{V}\left(t\right)=\frac{1}{2}\sqrt{2E_s}\underset{l=0}{\overset{L-1}{\mathrm{\&Sigma;}}}\widetilde{u_l}\widetilde{a_l}(t-\mathrm{l\&Delta;}{T}_s)+\tilde{n}\left(t\right)=\tilde{s}\left(t\right)+\tilde{n}\left(t\right)---\left(4\right)$

In the formula:

Be the complex envelope of white Gauss noise, its power spectral density is N ₀Watt/conspicuous;

E _sBe the receiving symbol energy, E _s=α E ₀, α is a fading channel;

Duration be [l Δ T _s, l Δ T _s+ T _s], promptly

${\tilde{a}}_l(t-\mathrm{l\&Delta;}{T}_s)=0,$ $t\&NotElement;(\mathrm{l\&Delta;}{T}_s,\mathrm{l\&Delta;}{T}_s+T_s);$

Be illustrated in figure 4 as in the overlapping time division multiplex system of K=3 and receive signal schematic representation.

Because channel possibly be a random time-varying channel; So for different l; The complex envelope that receives signal maybe be different, so represent this possibility with subscript l here.If channel becomes when being nonrandom, though perhaps be that the slowly variation that becomes at random the time causes at a frame length T and can think that with interior the characteristic of channel is constant basically, then subscript l all can omit in these cases.But generally speaking, the complex envelope of reception signal is not necessarily consistent with the complex envelope that sends signal.Can find out, owing to symbol-interference only appears in the adjacent K symbol, generally speaking, except initial and final (K-1) individual Δ T _sIn addition, other any moment being received signal all is stacks of K symbol.Particularly at t ∈ [l Δ T _s, (l+1) Δ T _s], l=0,1 ...., multiple connection during L-K+1 is collected mail and number is:

t∈[lΔT _s，(l+1)ΔT _s] (5)

Wherein:

● l (t)=● (t) * [u (t-l Δ T _s)-u (t-(l+1) Δ T _s)] l=0,1,2 ..., L+K-1; Wherein, ● be meant that other meet the letter of this formula expression formula.

${\tilde{S}}_l\left(t\right)=\frac{1}{2}\sqrt{2E_s}\underset{k=0}{\overset{\mathrm{Min}(l,K-1)}{\mathrm{\&Sigma;}}}{\tilde{u}}_{l-k}{\tilde{a}}_{l-k,k}\left(t\right);---\left(6\right)$

Wherein:

${\tilde{a}}_{l-k,k}\left(t\right)={\tilde{a}}_{l-k}(t+(l-k)T_s)\&times;[u(t-\mathrm{k\&Delta;}{T}_s)-u(t-(k+1)\mathrm{\&Delta;}{T}_s)]$

l＝0，1，2，...，L-K+1；k＝0，1，...，K-1；(7)

$u\left(t\right)=\left\{\begin{array}{cc}1& t>0\\ \frac{1}{2}& t=0\\ 0& t<0\end{array}\right.---\left(8\right)$

U (t) is the time-domain unit step function.

Before the span of l was different from here, it had gone out K-1 than L is big, and this is because in the frame length T of system, Δ T _sNumber go out K-1 than L is big, but should be noted that when l＞L-1

Simultaneously

Be illustrated in figure 5 as overlapping time division multiplex system the time become plural convolutional encoding model.

Remaining problem is used Maximum likelihood sequence detection MLSD algorithm provided by the present invention exactly, finds the solution in t ∈ [0, T] T=(L+K-1) Δ T _s, promptly in a frame time, make following formula minimal data sequence u in T:

$\underset{u}{\mathrm{Min}}{\&Integral;}_T{\left|\right|\tilde{v}\left(t\right)-\tilde{s}\left(t\right)\left|\right|}^2\mathrm{dt}---\left(9\right)$

In the formula: || ● || ²The expression ● square mould.

(9) physical meaning of formula be t ∈ [0, (L-1) Δ T _s+ T _s] promptly in a frame time length, seek most probable data sequence U, make its time corresponding waveform

With the reception signal waveform

Near (Euclidean distance minimum), we will introduce best Sequence Detection MLSD algorithm specially in the back the most, and we will be subsequently provide other quick accurate optimal algorithm with the form of other patent.

Then; Analyze the tap coefficient in the shift register channel model of overlapping time division multiplex system: well-known; In random time-varying channel; The impulse Response Function of channel

along with observing time t difference and present change at random, the shape of complex envelope behind time shift that therefore receives signal generally is vicissitudinous (Fig. 6).At t ∈ (l Δ T _s, (l+1) Δ T _s) in the value signal of each channel tap coefficient see shown in Figure 6ly, particularly be longer than symbol lengths, promptly when the coherence time of channel

The time, these tap coefficients will tighten and be some sample values (numerical value), and this situation can bring great convenience to practical applications.

Explain again that then the tree graph of overlapping time division multiplex system representes:

The tree graph of overlapping time division multiplex system representes it is the mode that a kind of very vivid overlapping time division multiplex system input-output of expression concerns.Fig. 7 be exactly the Q=1 of a K=3 be the input-output graph of a relation of the overlapping time division multiplex system of binary, we represent input bit u with branch upwards among the figure _n=1, downward branch is then represented input bit u _n=-1, corresponding codes output then is illustrated in the top of each branch.Among the figure thick line path representation list entries be u=[1 ,-1 ,-1,1 ... ] ^T, corresponding plural convolutional encoding output waveform then does

....Scrutinize this figure, we can find that between input and the output sequence be one to one fully.There is not certain list entries corresponding extremely with two or more output sequences, on the contrary also true.So one-to-one relationship between the input and output sequence in the overlapping not time to rupture of the symbol territory.So if in time-domain, detect just the error probability that can not appearance can not subtract again by sequence, traditional certainly just must have been abandoned by quilt by the symbol detection mode.If the length of sequence is fixedly the time, for example its length is L, then Q is tieed up binary source, and possible sequence sum will be 2 ^QL=M ^LSo our problem will be summed up as 2 ^QL=M ^LUnit's problem of signal detection.Because each sequence equiprobability of supposition occurs usually in communication; Therefore should adopt the Maximum Likelihood Detection criterion; When each sequence unequal probability occurs, should adopt maximum posteriori criterion (promptly the big sequence of probability of occurrence multiply by bigger weighting, otherwise then smaller).So, seem the optimum signal of overlapping time division multiplex system to detect problem and solved, the way it goes theoretically, has any problem but implement.Because L is bigger usually, so direct utilization maximum likelihood or maximum posteriori criterion will be very complicated.People are when the list entries equiprobability fortunately; Decoding algorithm to convolution code; After deliberation decades; And overlapping time division multiplex system also can be counted as a plural convolution coder; Many decoding algorithms of therefore relevant convolution code are for example said Fano algorithm and various storehouse (Stack) algorithm and the bcjr algorithm of in tree graph, searching for best (being the maximum likelihood function value) path, can use for reference the detection that is applied to signal in the overlapping time division multiplex system basically through after putting into the melting pot.Because these algorithms are not real best maximum likelihood algorithm, can only be referred to as the maximum likelihood algorithm that is as the criterion, the present invention does not just plan to have introduced.Below we will introduce another kind of algorithm---Maximum likelihood sequence algorithm (MLSD).This is to use for reference Viterbi (Viterbi) algorithm of convolution code and the real maximum likelihood algorithm that comes, need introduce the Trellis figure and state (State) figure of overlapping time division multiplex system earlier for this reason.

Then, the Trellis figure that overlapping time division multiplex system is described again representes with state diagram:

Though tree graph can vividly describe the relation between input and the output very much, this figure at first is bad picture, and particularly along with the increase of L, it will be index expands, and is not easy to use very much, and therefore is necessary it simplification.Let us returns Fig. 7 again, after examining, can find, this tree graph just becomes repetition after the 3rd, because every branch that gives off from the node that is labeled as a all has same output, this conclusion is to node b, and c, d are correct too.They are nothing more than being following several kinds of possibility (see figure 8)s.As can be seen from the figure can only transfer to (through input+1) node a and (through input-1) node b from node a, b can only arrive (input+1) c and (input-1) d simultaneously, and c can only arrive (input+1) a and (input-1) b, and d can only arrive (input+1) c and (input-1) d.The reason that produces this phenomenon is very simple, because have only the individual symbol of adjacent K (is 3 specific to this example) just can form the phase mutual interference.So when the K bit data was input to channel, the 1st bit data had the earliest shifted out a rightmost shift unit.Therefore the output of channel only is decided by the input of preceding K-1 data except depending on the input of data now.In general, for M=2 ^Q, i.e. Q dimension binary data input, as long as preceding K-1 Q dimension binary data is identical, their corresponding output is just identical.Therefore among Fig. 7 (Q=1) behind the 3rd branch road, the node of every a of being labeled as just may be incorporated in together, same b, each node of c and d also may be incorporated in together, has so just formed a folding tree graph---Trellis schemes.Translator of Chinese has the people to be referred to as hedge figure or trellis structure (seeing Fig. 9 A and Fig. 9 B).Among the figure our regulation be input as+1 branch road representes with solid line, be input as-1 branch road and be represented by dotted lines.This is that downward branch has been imported for-1 because we can not stipulate simply that again branch upwards is+1 input after folding.

Scheme the repetitive structure on time shaft if get rid of Trellis, we can obtain a figure-state diagram (State Diagram) of further simplifying, and are shown in figure 10, for the sake of simplicity, draw the final back that reaches to transition state among the figure.State in the state diagram is to determine according to each node among the Trellis figure, and promptly each state is to be determined by the preceding K-1 position Q dimension binary data bit of remembering at channel.Therefore be the overlapping time division multiplex system of K to memory (constraint) length, its stable state number is 2 when binary is imported ^K-1Individual, when the input of Q dimension binary, be 2 ^{Q (K-1)}=M ^K-1Individual.Initial in addition, final, preceding in addition transition state and back transition state, initial in this example and end-state is (0,0); Preceding transition state is (0 ,-1) and (0,1) totally two; Back transition state is (1,0), and (1,0) also totally two.State transitions relation initial and transition state is very simple; As long as attention is initial and end-state must be complete zero dummy status; And in preceding transition state, the former data that are stored in the channel contain just has Q dimension binary in odd, the new data+or-data; So they can only be come by a state transitions, and can to other 2 ^Q=M state transitions; For the back transition state, opposite with preceding transition state, former be stored in the channel be Q dimension binary+or-data, just odd in the new input, therefore, they all can be by 2 ^Q=M state transitions come, but can only be to a state transitions.Please note: in this example, Q=1, K=3, we are writing state a (1; 1), b (1 ,-1), c (1; 1), the relation of each information bit is arranged by routine from left to right during d (1 ,-1), and for example state b (1;-1) bit 1 is to get into channel the earliest in, but the bit that gets into channel in the Q=1 channel model of Fig. 6 the earliest but exists in shift unit of rightmost, and its time relation is from right to left.This point please the reader must not be obscured.

We can find out that overlapping time division multiplex system is a finite state machine, and its oriented state diagram can be described the input/output relation of channel fully.Because preceding K-1 the Q dimension binary information bit that each STA representation is stored by channel, i.e. (K-1) Q information bit, the transfer branch road between state is then represented the information bit that import now.K=3 for example; The data bit of the binary channel input of Q=1 does ... ,-1,1; 1 ..., then be in state diagram to a state transitions from the c state; Because of c=(1,1), import one 1 again after; Originally existed-1 in shift unit of rightmost to shift out channel, and 1 entering channel of new input, state transitions is to a=(1; 1), the output of channel then does ..., it is indicated on

on the transfer branch road from c to a.

In general memory (constraint) length is that the Q of K ties up the binary input channel and has 2 ^{Q (K-1)}=M ^K-1Kind of stable state, each stable state can to other 2 ^QIndividual state transitions, also can from other 2 ^QIndividual stable state shifts.In Trellis figure above-mentioned conclusion then report for: memory span is that the Q dimension binary input channel of K has 2 ^{Q (K-1)}=M ^K-1Plant different nodes, under stable case, each node outwards sends 2 ^Q=M branch road has 2 again simultaneously ^Q=M branch road is incorporated in this node.

Trellis figure is very useful when research Maximum likelihood sequence MLSD algorithm.

After having introduced overlapping time-multiplexed mathematical description, introduce Maximum likelihood sequence detection below, i.e. the MLSD algorithm.

Maximum likelihood sequence decoding algorithm in the convolution code can come the signal of overlapping time division multiplex system is detected through transforming to transplant.Below we still are that example is specifically introduced the MLSD algorithm with the binary signal.We know for length is the Q dimension binary list entries of L, and its possible output sequence (possible path in Trellis or the state diagram) number is 2 ^QL=M ^L,, directly use Maximum Likelihood Detection and will become very complicated because L is very big usually.The essence of MLSD algorithm is maximum likelihood algorithm, but its complexity only is exponential increase with the memory span K-1 of channel, rather than is exponential increase with L.We suppose that the noise of channel is a white noise for this reason; And the input data sequence that in the white noise channel, has the maximum likelihood function value should be in tree graph or Trellis figure with receive signal the pairing list entries in path of minimum Eustachian distance arranged; Promptly select best

, make and satisfy

In the formula: T all receives signal time;

But because each path periodically merges, we there is no need to calculate the likelihood function or the Euclidean distance of entire path length fully in Trellis figure.Because when the path merges, those paths that before merging, have relatively large Euclidean distance can be removed fully.T=3 Δ T among Fig. 9 for example _sThe time have two paths to overlap for the first time at node a place, they are respectively:

(corresponding list entries is 1; 1,1)

(corresponding list entries is-1 to reach

; 1,1).

We calculate this two paths respectively and receive the Euclidean distance between signal, stay a relative smaller of distance, and we are referred to as surviving path (Survivor Path), and another distance relatively large person then remove.Therefore we write down the surviving path that arrives it earlier to node a; For example say

and also have two paths to overlap for the first time to node b equally with the Euclidean distance

that receives between signal; They are respectively: (corresponding list entries is 1; 1;-1) (corresponding list entries is-1 to reach

; 1 ,-1).We select one and receive the path that relative minimum range is arranged between signal; And write down this surviving path; For example say

and and the Euclidean distance

that receives between signal node c and d are also done same processing; The result sees Figure 11; Wherein, * path and do not draw the path representation path that is eliminated.Surviving path among the figure all is relative minimum distance path.So we have obtained arrival node a, b, c, the relative optimal path of d and corresponding Euclidean distance:

${r_{a_1}}^{\&prime;}{u}_{a_1}=\left(\mathrm{1,1,1}\right)$

${r_{{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="HPA00000676274500012.png,HPA00000676274500021.png"\; state="\{\{state\}\}">b</figure-callout>}}_1}}^{\&prime;}{u}_{b_1}=(\mathrm{1,1},-1)$

${r_{{\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="HPA00000676274500012.png,HPA00000676274500021.png"\; state="\{\{state\}\}">c</figure-callout>}}_1}}^{\&prime;}{u}_{c_1}=(-1,-1,1)$

${r_{{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="HPA00000676274500012.png,HPA00000676274500021.png"\; state="\{\{state\}\}">d</figure-callout>}}_1}}^{\&prime;}{\mathrm{<figure-callout\; id="1"\; label="u\; d"\; filenames="HPA00000676274500012.png,HPA00000676274500021.png"\; state="\{\{state\}\}">u</figure-callout>}}_{d_{}}=(1,-1,-1)$

At the also bad work of our any judgement of this stage.At t=4 Δ T _sThe time, we calculate equally respectively and arrive different paths of each node and the Euclidean distance that receives between signal, and the path of selection with relative minimum range.For example to node a, at t=4 Δ T _sThe time arrive a the path in original Trellis figure, have four, promptly 1,1,1,1; 1 ,-1,1,1;-1,1,1,1;-1 ,-1,1,1.But in the calculating of phase I, first three branch road of second and the 3rd paths is eliminated, so we can only make one's options in first and the 4th liang of paths.Need calculate them for this reason respectively and receive the Euclidean distance between signal.Notice that we need not calculate the Euclidean distance of entire path now, because noise is a white noise, we only need to calculate at t=3 Δ T _sThe time node a to t=4 Δ T _sThe time a between branch road and receive the Euclidean distance between signal, add It is the Euclidean distance between article one path and reception signal.Equally, we only need to calculate at t=3 Δ T _sThe time node c to t=4 Δ T _sThe time node a between branch road and the Euclidean distance that receives between signal add

It is the Euclidean distance between the 4th paths and reception signal.Between this two paths; We eliminate the relatively large person of distance, and write down less relatively path of distance and Euclidean distance and certain

thereof and just can from memory, dispose with .We also carry out same processing to node b, c and d.So continue; At each the stage l that calculates, to l (l=0,1; 2; ..., L-K+1) nodes in stage separately the state of representative (be Trellis figure in l each node in the stage) we only keep one with the less relatively path of reception signal Euclidean distance, and write down this path Euclidean distance and pairing path.

Figure 11 is a sketch map of this testing process, please notes in our example, at the five-stage that calculates, i.e. t=7 Δ T _sThe time, each surviving path (being relative optimal path) is respectively:

at this moment the initial part in best relatively path is-1 entirely;-1,1.Therefore we can enter a judgement:

$\begin{array}{ccc}{\hat{u}}_0=-1,& {\hat{u}}_1=-1,& {\hat{u}}_2=1.\end{array}$

Because the initial part of all relative optimal paths all is them, they are optimal path just naturally.

If each surviving path does not have common initial part, then calculate and to continue, till they have had common part.Therefore the judgement of MLSD algorithm is at random; It might not adjudicate output for a long time, and judgement output also is not necessarily by symbol, possibly once have only a judgement output; A plurality of judgement outputs also might once be arranged, but maximum judgement time-delay is length L+K-1 of Trellis figure.This is because for L symbol arranged, the system that an adjacent K symbol is overlapped is because its Trellis schemes the longest L+K-1 that has only; And its end-state is complete zero (0; 0 ...., 0); Final each paths must merge, so the time-delay of Maximum likelihood sequence detection MLSD algorithm is at most the L+K-1 step.

Because this characteristics of MLSD algorithm, we can produce following two queries very naturally:

First, because the MLSD algorithm is to have common initial part that judgement output is just arranged with each surviving path, promptly judgement will be through the time-delay of one section randomness.Is when L → ∞, the judgement time-delay much for the probability of ∞ so?

Second, MLSD algorithm require each state that two memories are arranged, an Euclidean distance (Euclidean Distance) that is used to store the relative optimal path of this state of arrival, a relative optimal path that is used to store this state of arrival.Should the capacity of this memory select much so?

For first problem, the inventor is verified for the system of L → ∞, and its judgement time-delay is zero for the probability of ∞, the document that sees reference (Li Daoben, the statistics detection and the estimation theory of signal, Science Press, 2004).

For in second problem first, i.e. path Euclidean distance memory, generally speaking because the existence of noise, no matter any paths, always it is increasing apart from receiving signal distance, from this point see this memory as if capacity should for ∞.But because of our the interested just relative distance between them, so we can make its maximum (or minimum) apart from being zero after each calculating, promptly all deduct this maximum (or minimum) distance to the distance of each surviving path.So, what we stored will be the relative value of distance, and its capacity is exactly limited naturally.As for second, i.e. surviving path memory is got 5K or 4K is just passable according to the general length of experimental result, can ignore basically because surviving path is longer than the probability of 5K.In case if these memories are filled with and adjudicate and can adjudicate by force when also not carrying out, promptly export the initial bit that minimum range is arranged as judgement this moment.Sometimes also available majority logic judgement is promptly exported the majority in each surviving path initial bit as judgement.The very simple but somewhat inferior properties of the equipment that adopts the latter is in first kind of mode, but because the probability of judgement is very little by force, the performance loss that is caused thus also is very little.

From the above mentioned, we find different with other any communication technologys, should handle in time-domain the input of overlapping time division multiplex system, and the most handy digital form are handled problems.This just requires the receiver of this system to disperse at first to received signal and digitized processing.What is interesting is that very the overlapping people of symbol generally believe that meeting produces serious phase mutual interference; The inventor finds that symbol is overlapping and not only can not produce interference, and it is a kind of utilizable coding bound relation on the contrary, and symbol is overlapping serious more; Coding bound is long more, and coding gain is high more on the contrary.Certain this coding is a kind of encoding relation that nature forms, and is not necessarily the forced coding restriction relation.The inventor believes firmly that the symbol overlapping multiplexing cooperates goes up the encoding relation that suitable coding makes it to form optimum, can further improve systematic function.

The inventor has proved theoretically and has passed through great amount of calculation machine simulating, verifying: in random time-varying channel, for mark-hold bandwidth width B ₀, the mark-hold length T _s, we can be with reducing mark space Δ T _sIncrease overlapping tuple K, at this moment the inventor finds because system bandwidth is constant, the then spectrum efficiency of system proportional increase along with the increase of K, but the transmission reliability of system (being order of diversity) will remain unchanged basically; But if the total bandwidth B of simultaneously proportional increase system (for example spread spectrum and CDMA mode realize can be earlier to superpose filtering then or other by rectangle or broadband symbol); Then the spectrum efficiency of system will remain unchanged basically; And performance is really become better and better, and transmission reliability is increasingly high, and this moment is when K → ∞; Random time-varying channel will be transformed into the best perseverance of channel performance participation property white gaussian channel, i.e. awgn channel gradually.Therefore in random time-varying channel, as long as the system linearity degree is secure with transmitting power, the way that we just can the overlapping tuple K of the relieved increase of usefulness audaciously improves the spectrum efficiency or the transmission reliability of system, or the two is taken into account.Certainly the complexity of system handles also can increase thereupon.

Below, will with embodiment 1 and embodiment 2 overlapping time-division multiplexing method and overlapping time division multiplex system be described respectively respectively.

Embodiment 1

The performing step of time-division multiplexing method of the present invention is described through present embodiment below.

Step 1: according to given channel parameter, system parameters determines the most basic some design parameters:

1) channel parameter: mainly contain the maximum time diffusing capacity Δ (second) of channel or the coherence bandwidth of channel

(conspicuous); The peak frequency diffusing capacity of channel ; The coherence time of (conspicuous) or channel

; (second);

2) system parameters: mainly contain system bandwidth B (conspicuous); Requirement to spectrum efficiency; The linearity etc.;

3) design parameter: mainly contain:

A) basic modulation level is counted M=2 ^Q, wherein Q is the information bit of every modulation symbol institute load.

Because under same spectrum efficiency, system complexity and M have nothing to do, can suitably select as the case may be, because system complexity is decided by the stable state number, promptly 2 ^{Q (K-1)}=M ^K-1Can know according to (1) formula and (2) formula, preset time bandwidth product B ₀T _sThe time, the stable state base originally is decided by spectrum efficiency.

B) basic symbol length

(second) (symbol lengths ), basic spectrum modulation signal

Width B ₀(conspicuous);

In order to reduce system complexity; So the status number of system will be constant basically in random time-varying channel, be convenient to Project Realization can to let

;

If only be concerned about the transmission reliability of system; And the variation or the complexity of system mode number are indifferent to, can let

to compare mutually even less than Δ with Δ;

B ₀Select bigger, T _sSelect longlyer, in random time-varying channel, can automatically produce the implied diversity gain, improve systematic function.Wherein:

Latent frequency diversity tuple

Latent time diversity tuple

The total diversity tuple of system

is the two long-pending (the branch collection also should be multiplied by space diversity tuple

if having living space).

Wherein

expression minimum positive integer.

C) relative symbol shift amount (mark space) Δ T _sOr the overlapping tuple K of symbol:

Less Δ T _sThereby bigger K can improve the spectrum efficiency of system, but system complexity and allow all corresponding increase of level number will decide according to actual conditions and needs, and its fundamental relation is following:

(K-1)ΔT _s＜T _s≤KΔT _s

Wherein: T _sIn except the basic symbol width

Maximum time propagation Δ (multipath broadening) the equal time expansion factor that also should comprise system outward.

At Δ T _sMuch smaller than the coherence time of channel

The time, the displacement tap coefficient in the overlapping time-division system channel model

To be punctured into some sample values (numerical value), on the contrary the displacement tap coefficient in the overlapping time-division system channel model To be some time waveforms.

D) system symbol sum L (or frame length T):

Because the frame length T=T of system _s+ (L-1) Δ T _s, then

When concrete system design; Preferably let coherence time

that frame length is shorter than channel promptly

this be owing to so can think constant basically with the interior characteristic of channel at total frame length T, be convenient to system engineering and realize and arrange pilot signal.

When giving fixed system and channel parameter, design parameter B ₀, Δ T _s, K, L, T _sAnd factor such as overall system bandwidth B is that mutual restriction is closely connected together, should select repeatedly and carries out optimal design according to actual conditions.

The spectrum efficiency η of system is:

$\mathrm{\&eta;}=\frac{\mathrm{LQ}}{B_0{T}_s+B_0(L-1)\mathrm{\&Delta;}{T}_s}$

Give regularly less Δ T at T and K _sThereby less T _s, will cause bigger L, higher η;

Too small B ₀Naturally the latent frequency diversity tuple that can cause system Descend.But as long as overall system bandwidth B enough wide (can realize the total bandwidth B than broad through modes such as spread spectrum, CDMA or multicarriers) just there is no need to take into account it when design.Because we still can be through the latent frequency diversity tuple that interweaves, technological means such as coding improves system; Because of system is sayed; Its implied diversity tuple be decided by

rather than

just the latter understand nature and form, and the former need pass through additional technological means and just can obtain.

Step 2: according to the given characteristic of channel, system parameters and design parameter design overlapping time-multiplexed emission system.

Because multi-transceiver technologies such as overlapping time-division multiplex technology and OFDM are the same also to be a parallel Synthronous data transmission system, different just its demodulation complete different with detection mode.That yes is essentially identical to its its transmitter architecture of each symbol and conventional digital communication transmitter.

Figure 12 is exactly the sketch map of an overlapping time division multiplexing (not containing straight expansion or CDMA) system transmitter.For spread spectrum or cdma system, can add the spread spectrum arithmetic section.Its l (l=0,1,2 ..., L-1) in the symbol time interval, the complex envelope of computing that transmitter is realized (not containing the spread spectrum computing) is:

$\sqrt{2{\mathrm{<figure-callout\; id="0"\; label="E"\; filenames="HPA00000676274500012.png,HPA00000676274500051.png"\; state="\{\{state\}\}">E</figure-callout>}}_0}\underset{l=0}{\overset{L-1}{\mathrm{\&Sigma;}}}{\tilde{u}}_l\tilde{a}(t-\mathrm{l\&Delta;}{T}_s),$ t∈[0，T] (10)

In the formula: E ₀Be every symbol emitted energy;

is normalization complex modulated signal envelope, and it satisfies:

$\tilde{a}\left(t\right)=0,$ $t\&NotElement;[0,T_s]$

${\&Integral;}_0^{T_s}{\left|{\tilde{a}}_0\left(t\right)\right|}^2\mathrm{dt}=1;$

is l (l=0; 1; ..., the complex data that L-1) individual symbol transmitted.

In the formula: this modulation signal of complex radical Frequency spectrum do

Its bandwidth is B ₀Conspicuous, promptly

$\tilde{A}\left(f\right)=0,$ $f\&NotElement;[-\frac{{\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="HPA00000676274500012.png,HPA00000676274500051.png"\; state="\{\{state\}\}">B</figure-callout>}}_0}{2},\frac{{\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="HPA00000676274500012.png,HPA00000676274500051.png"\; state="\{\{state\}\}">B</figure-callout>}}_0}{2}]$

Basic point among the figure is to form l=0 road complex modulated signal envelope waveform with digital form earlier

Homophase a _c(t) with quadrature a _s(t) waveform; They will obtain l=1 behind shift register; 2 ..., the homophase of other each road modulation signal of L-1 and quadrature envelope waveform; With the homophase envelope waveform of said each modulation signal and quadrature envelope waveform in-phase data signal and orthogonal data signal multiplication with each corresponding symbol, obtain each modulation signal through the filtered modulation signal waveform of data-modulated; With described each modulation signal waveform addition, formation transmits.This has just guaranteed the consistency of each road complex envelope.

Step 3: it is synchronous in receiver, to form symbol time; Under synchronous condition; handles to the reception signal in each frame, and its basic step is following:

According to sampling theorem, select suitable sampling frequency, carry out digitized processing to received signal, form the time-domain Serial No. that receives signal.Digitized processing can also can be carried out in base band at intermediate frequency, is decided in its sole discretion by the designer fully.If the designer is ready to adopt non-numeric analog form to handle problems, can certainly removes digitized processing from and directly analog signal is handled.

Step 4: actual channel is measured, found out the valuation that receives complex envelope

in the distinct symbols time interval.

Valuation to

can be used any method; For example utilize special " pilot signal " to measure; Or utilize the information of having adjudicated through the mode of received signal computing is calculated its valuation; Perhaps get the combination of the two, even can find the solution its valuation with blind estimating method.

Step Five: Using Step four found

TDM systems overlap to form a valuation channel model tap coefficients

Step 6: the basic modulation level according to system adopted is counted M=2 ^Q, overlapping tuple K lists whole states of system; State comprises initial and end-state, preceding transition state, back transition state and stable state, totally five types.So-called state S is stored in the pairing Q dimension of modulating data binary data in the time domain shift register channel model (+or-) or 0 data, wherein:

Initial and respectively one of end-state, they all are

(they are meant that all Q dimension data are 0 state);

Stable state has 2 ^{Q (K-1)}=M ^K-1Individual, they are respectively:

(they are meant that all Q dimension data all are states of binary (+or-) data).

Preceding transition state all has M+M with the back transition state ²+ M ³+ ...+M ^K-2Individual.

Transition state is meant that the individual Q dimension data in front some (but being less than K-2) is zero state before so-called.

So-called back transition state is meant that back some (but being less than K-2) individual Q dimension data is zero state.

Initial condition is only with to 2 ^QTransition state shifts before individual, if K=2, then directly to 2 ^QIndividual stable state shifts;

End-state can only be from the front 2 ^QIndividual back transition state shifts comes, if K=2, then directly from 2 ^QIndividual stable state shifts and comes;

The forward transition state can only be from the front state (initial condition or preceding transition state) shift and come, but can be rearwards 2 ^QIndividual state (preceding transition state or stable state) shifts; When the forward transition state only is present in node l among the Trellis figure＜K-1.

The back can be from the front 2 to transition state ^QIndividual state (preceding transition state or stable state) shifts and comes, but a state (back transition state or final transition state) shifts rearwards.When the back only is present in node l among the Trellis figure＞L-1 to transition state.

Owing to always have a new Q dimension binary or 0 yuan of new data to get into channel model at every turn, 0 yuan of K-1 Q dimension in front or two senior statesman's data are left channel model simultaneously, and Q dimension binary data has 2 ^QKind the combination, and Q tie up 0 metadata have only one maybe, so the aforesaid state transfer relationship is just arranged.

Transition state is the peculiar state of overlapping time division multiplexing, and this is the difference with general convolution code or the pairing finite state machine of Trellis sign indicating number.

Step 7: according to the state transitions relation, the state diagram of the system of drawing, Trellis figure or tree graph.And by state transitions relation respectively by (4) to (6) formula calculate respectively shift branch road coding output

promptly:

${\tilde{S}}_{l,s,m}\left(t\right)=\frac{1}{2}\sqrt{2E_s}\underset{k=0}{\overset{\mathrm{Min}(l,K-1)}{\mathrm{\&Sigma;}}}{\tilde{u}}_{l-k}{\tilde{a}}_{l-k,k}\left(t\right)---\left(11\right)$

Wherein: l ∈ (0; 1; 2 ..., L-K+1) l symbol of expression input; But behind l＞L-1,

S representes to shift the state that branch road is arrived at the l node;

M representes to arrive the path of this state, for preceding transition state m=1; Other state m=2 ^Q=M;

Because Trellis figure just finishes behind the L-K+1 node, so l might be greater than L-1 in (4) formula, but when arriving the L-K+1 node, Trellis schemes must shrink in final all-zero state.Step 8: each stable state S is prepared two memories, and one of them storage arrives the surviving path U of this state S _{S, l}=[u _{S, 0}, u _{S, 1}..., u _{S, l}], l=0,1 ..., L+K-1, wherein u _{S, l}Be Q dimension binary data; Another then stores this surviving path U _{S, l}Pairing coding is exported before the l node and is received burst

Between path Euclidean distance d _{S, l}, (l=0,1,2 ..., L-K+1).

Can temporarily use the memory of arbitrary stable state for transition state.Because stable state has 2 ^{Q (K-1)}=M ^K-1Kind, therefore every kind of memory all needs M ^K-1Individual, need 2M altogether ^K-1Individual memory.Step 9: in Trellis figure, implement Maximum likelihood sequence detection MLSD, its substep is following:

1 ') to make the path Euclidean distance of start node state (l=0) be d _0,0=0;

2 ') to the l node (l=1 ..., all the state S in L-K+1) calculate its whole m (m=1 or 2 ^Q=M) bar from last state transitions so far state the branch road code signal with receive the burst

Between branch road Euclidean distance d _{S, m}(l, l+1).

$d_{S,m}(l,l+1)\stackrel{\mathrm{\&Delta;}}{=}{\&Integral;}_{\mathrm{l\&Delta;}{T}_s}^{(l+1)\mathrm{\&Delta;}{T}_s}{|{\tilde{V}}_{n,l}\left(t\right)-{\tilde{S}}_{l,S,m}\left(t\right)|}^2\mathrm{df}---\left(12\right)$

3 ') will arrive the branch road Euclidean distance d of this state to every state S _{S, m}(l is l+1) with they set out separately path Euclidean distance d of state S ' _{S ', l-1}Addition forms m new path Euclidean distance, and therefrom selects reckling, as the path Euclidean distance d of l node state S _{S, l}, upgrade the path Euclidean distance memory that deposits this state S in.

4 ') node l (l=1,2 ..., L-K+1), each state S is found out the pairing surviving path U of its path Euclidean distance _{S, l}Renewal deposits the surviving path memory of this state S in.

To l+1 node iteron step 2 '), 3 '), 4 '), until the l=L+K-2 node.This moment, surviving path was inevitable only remaining one, and then the pairing data sequence of this surviving path is exactly that our needed conclusive judgement is exported.

5 ') when L is big; In order to use short surviving path memory; Its length can be decided to be 4K～5K, and can check the surviving path memory of each state this moment at any time in substep 4, in case find in the path that they keep identical initial part is arranged; Then that this is identical initial part is vacateed corresponding memory space simultaneously as judgement output.

6 ') for the capacity of the path Euclidean distance memory that reduces each state S; Avoid overflowing; After each step is accomplished, can make minimum (greatly) person of path Euclidean distance is zero distance, the Euclidean distance memory of other each state only store with its difference (plus or minus) be relative Euclidean distance.

Step 10: when the overlapping tuple K of symbol is excessive; Though step 9 has optimum performance; Be that it can find out and receive the path that signal has real minimum Eustachian distance, but, utilize step 9 will cause sequential detector too complicated for excessive K; Other rapid serial decoding algorithm that can consider to use for reference this moment in the convolutional encoding reduces the complexity of sequential detector, can be adapted to overlapping time division multiplex system but must they be put into the melting pot.But the reduction of any Sequence Detection complexity will be a cost with sacrificial system thresholding signal to noise ratio all.

Embodiment 2

Through present embodiment time division multiplex system of the present invention is described below.

Time division multiplexing provided by the invention system is shown in figure 13, comprises transmitter and receiver.Wherein, transmitter also comprises overlapping time division multiplexing modulating unit and transmitter unit; Receiver comprises receiving element, pretreatment unit and Sequence Detection unit.

In transmitter, input data sequence forms overlapped the transmitting on time-domain of a plurality of symbols through overlapping time division multiplexing modulating unit, by transmitter unit said transmitting is transmitted into receiver again; The receiving element of receiver receives the signal of transmitter unit emission; Form the receiving digital signals that suitable Sequence Detection unit detects through pretreatment unit; The Sequence Detection unit carries out detecting by data sequence in the time-domain to received signal, thus the output judgement.

Shown in figure 14 is the block diagram of the overlapping time division multiplexing modulating unit of transmitter of the present invention, and this overlapping time division multiplexing modulating unit comprises digital waveform generator, shift register, serial-parallel converter, multiplier and adder.

At first form the phase wiggles and the orthogonal waveforms of first modulation signal envelope waveform with digital form by digital waveform generator; Be shifted by the phase wiggles and the orthogonal waveforms of shift register again, with homophase envelope waveform and the quadrature envelope waveform that produces other each modulation signal first modulation signal envelope waveform of digital waveform generator generation; Then, serial-parallel converter converts the data sequence of serial input into the parallel in-phase data signal and the orthogonal data signal of corresponding each modulation signal; The homophase envelope waveform and the quadrature envelope waveform of the modulation signal that multiplier is then corresponding with each with each in-phase data signal of said serial to parallel conversion unit output and orthogonal data signal multiply each other, with obtain each modulation signal through the filtered modulation signal waveform of data-modulated; At last by adder with each modulation signal of multiplier output through the filtered modulation waveform addition of data-modulated, transmit with formation.

Like Figure 15 another design frame chart for transmitter of the present invention, be different with the transmitter among Figure 13, this transmitter also comprises interleave unit, coding unit and spectrum-spreading unit except comprising overlapping time division multiplexing modulating unit.

Wherein spectrum-spreading unit is used to increase overall system bandwidth, thereby the same with the effect of interleave unit and coding unit, thereby improves the latent frequency diversity tuple or the latent time diversity tuple of system.

Shown in figure 16, be the block diagram of the pretreatment unit of receiver of the present invention.This pretreatment unit is used for the auxiliary synchronous receiving digital signals sequence that forms in each frame, comprises synchronizer, channel estimator and digitized processing device.It is synchronous that wherein synchronizer forms symbol time to received signal in receiver; Then channel estimating unit is estimated channel parameter; The digitized processing device carries out digitized processing to the reception signal in each frame, is fit to the receiving digital signals sequence that the Sequence Detection unit carries out Sequence Detection thereby form.

Shown in figure 17 is the block diagram of the Sequence Detection unit of receiver of the present invention, and this Sequence Detection unit comprises analytic unit memory, comparator and a plurality of surviving path memory and Euclidean distance memory or weighted euclidean distance memory (not shown).In testing process, the analytic unit memory is made the plural convolutional encoding model and the trellis structure of overlapping time division multiplex system, and lists whole states of overlapping time division multiplex system, and storage; And comparator searches out the path with receiving digital signals minimum Eustachian distance or weighting minimum Eustachian distance according to the trellis structure in the analytic unit memory; Surviving path memory and Euclidean distance memory or weighted euclidean distance memory then are respectively applied for surviving path and the Euclidean distance or the weighted euclidean distance of storage comparator output.Wherein, described surviving path memory and Euclidean distance memory or weighted euclidean distance memory need respectively be prepared one for each stable state.Described surviving path memory length can be preferably 4K～5K.Described Euclidean distance memory or weighted euclidean distance memory are preferably only stores relative distance.

Above embodiment only is used to explain the present invention, but not is used to limit the present invention.

Claims (40)

1. a time division multiplexing method is characterized in that, utilizes a plurality of symbols in time-domain parallel transmission data sequence, and this method may further comprise the steps:

Transmitting terminal forms overlapped the transmitting on time-domain of a plurality of symbols;

Receiving terminal carries out detecting by data sequence in the time-domain to received signal according to the one-to-one relationship between transmission data sequence and the transmission data sequence time waveform;

Wherein, described transmitting terminal forms overlapped the transmitting on time-domain of a plurality of symbols and may further comprise the steps:

Form the phase wiggles and the orthogonal waveforms of l=0 road modulation signal envelope waveform with digital form;

Described phase wiggles and orthogonal waveforms behind time shift, are formed the homophase envelope waveform and the quadrature envelope waveform of other each modulation signal;

With the homophase envelope waveform of said each modulation signal and quadrature envelope waveform in-phase data signal and orthogonal data signal multiplication with each corresponding symbol, obtain each modulation signal through the filtered modulation signal waveform of data-modulated;

With described each modulation signal waveform addition, formation transmits.

2. time division multiplexing method according to claim 1 is characterized in that, transmitting terminal forms overlapped the transmitting on time-domain of a plurality of symbols according to design parameter.

3. time division multiplexing method according to claim 2 is characterized in that, determines described design parameter according to given in advance channel parameter and system parameters.

4. time division multiplexing method according to claim 3 is characterized in that, said design parameter comprises that basic modulation level counts M, basic symbol length Symbol lengths T _s, mark space Δ T _s, the overlapping tuple K of symbol and frame length T.

5. time division multiplexing method according to claim 4 is characterized in that, the overlapping tuple K of said symbol, mark space Δ T _sAnd symbol lengths T _sBetween satisfy following relation: (K-1) Δ T _s＜T _s≤K Δ T _s

6. according to claim 4 or 5 described time division multiplexing methods; It is characterized in that said symbol lengths

wherein Δ is the maximum time diffusing capacity of channel.

7. time division multiplexing method according to claim 4; It is characterized in that said basic symbol length

wherein Δ is the maximum time diffusing capacity of channel.

8. time division multiplexing method according to claim 4; It is characterized in that said basic symbol length

is equal to or less than the maximum time diffusing capacity Δ of channel.

9. time division multiplexing method according to claim 4 is characterized in that, described mark space Δ T _sLess than the coherence time of channel

10. time division multiplexing method according to claim 4; It is characterized in that frame length

wherein

is the coherence time of channel.

11. time division multiplexing method according to claim 4 is characterized in that, through reducing mark space Δ T _sIncrease the overlapping tuple K of symbol.

12. time division multiplexing method according to claim 3; It is characterized in that described channel parameter comprises the maximum time diffusing capacity Δ or coherence bandwidth

and the peak frequency diffusing capacity

of channel or coherence time of channel of channel of channel

13. time division multiplexing method according to claim 3 is characterized in that, described system parameters comprises system bandwidth B, to the requirement and the linearity of spectrum efficiency.

14. according to the described time division multiplexing method of arbitrary claim in the claim 1,2,3,4,5,7,8,9,10,11,12 or 13; It is characterized in that; Through increasing system bandwidth B; Or utilize and to interweave and Methods for Coding, or the raising system rate of delivering a letter, or the method for spread signal frequency spectrum improves the latent frequency diversity tuple of system.

15. time division multiplexing method according to claim 1; It is characterized in that; Described receiving terminal carries out detecting by data sequence in the time-domain to received signal and may further comprise the steps according to the one-to-one relationship between transmission data sequence and the transmission data sequence time waveform:

Reception signal in each frame is formed the receiving digital signals sequence;

Described receiving digital signals sequence implementation sequence is detected, to obtain the judgement that is modulated at the modulating data on whole symbols in the said frame length.

16. time division multiplexing method according to claim 15 is characterized in that, saidly reception signal in each frame is formed the receiving digital signals sequence may further comprise the steps:

It is synchronous to form symbol time at receiving terminal to received signal;

According to sampling theorem, the reception signal in each frame is carried out digitized processing.

17. time division multiplexing method according to claim 16 is characterized in that, described digitized processing is carried out at intermediate frequency, or carries out in base band.

18., it is characterized in that described Sequence Detection is a Maximum likelihood sequence detection according to claim 1 or 15 described time division multiplexing methods when each sequence equiprobability.

19. time division multiplexing method according to claim 15 is characterized in that, described described receiving digital signals sequence implementation sequence is detected may further comprise the steps:

Make the plural convolutional encoding model of division multiplexing system overlapping time;

List whole states of division multiplexing system overlapping time;

Make the trellis structure of division multiplexing system overlapping time, and list the coding output of each branch road;

For each stable state is prepared two memories;

In said trellis structure, search out the path that has minimum Eustachian distance or weighting minimum Eustachian distance with the receiving digital signals sequence, the corresponding data sequence in this path is conclusive judgement output.

20. time division multiplexing method according to claim 19 is characterized in that, described plural convolutional encoding model of making division multiplexing system overlapping time may further comprise the steps:

Actual channel is measured, found out the valuation that receives complex envelope in the distinct symbols time interval;

Utilize the valuation of described reception complex envelope to form the tap coefficient in division multiplexing system channel model overlapping time.

21. time division multiplexing method according to claim 20 is characterized in that, described actual channel is measured, and finds out the valuation that receives complex envelope in the distinct symbols time interval and uses special pilot signal measurement; Or utilize the information of having adjudicated through the mode of received signal computing is calculated valuation; Or get above the two combination; Or find the solution valuation with blind estimating method.

22. time division multiplexing method according to claim 19 is characterized in that, said overlapping time, whole states of division multiplexing system comprised initial condition, preceding transition state, stable state, back transition state and end-state.

23. time division multiplexing method according to claim 19 is characterized in that, the described surviving path memory of preparing in two memories for each stable state is used to store the surviving path that arrives said state; Euclidean distance memory or weighted euclidean distance memory are used to store the surviving path of the said state of arrival and the Euclidean distance or the weighted euclidean distance of receiving digital signals sequence.

24. time division multiplexing method according to claim 22 is characterized in that, described preceding transition state and described back transition state can be used the memory of arbitrary stable state.

25. time division multiplexing method according to claim 19 is characterized in that, the described path that has minimum Eustachian distance or a weighting minimum Eustachian distance with the receiving digital signals sequence that in said trellis structure, searches out may further comprise the steps:

Step 1, the path Euclidean distance that makes start node l=0 state or weights Euclidean distance are zero;

Step 2, l=1 node of calculating; L=2 node ..., all the state S in l=L-K+1 node; Calculate its all branch road code signal and branch road Euclidean distance or branch road weighted euclidean distance receiving digital signals of each bar from last state transitions to said state S; Wherein, L is overlapping total symbolic number, and K is overlapping tuple;

Step 3, branch road Euclidean distance or branch road weighted euclidean distance and they that will arrive this state to each state S set out separately the path Euclidean distance or the addition of weights Euclidean distance of state form new one or more paths Euclidean distance or weights Euclidean distance; If a plurality of described path Euclidean distances or weights Euclidean distance are arranged; Then from wherein selecting reckling; As path Euclidean distance or the weights Euclidean distance of l node state S, upgrade and deposit in Euclidean distance memory or the weighted euclidean distance memory of said state S;

Step 4, at node l, each state S is found out its path Euclidean distance or the pairing surviving path of weights Euclidean distance, upgrade the surviving path memory deposit this state S in;

Step 5, next node is repeated above-mentioned steps one to step 4, until the L+K-2 node, this moment, surviving path was only remaining one, and then the pairing data sequence of this surviving path is conclusive judgement output.

26. time division multiplexing method according to claim 25; It is characterized in that; In calculating, check the surviving path memory of each state at any time, in case in the path of finding to keep identical initial part is arranged, then that this is identical initial part is as judgement output.

27. time division multiplexing method according to claim 26 is characterized in that, still not judgement is then adjudicated by force when described surviving path memory is filled with, and promptly exports the initial bit that minimum range is arranged as judgement.

28. time division multiplexing method according to claim 26 is characterized in that, the majority logic judgement is then carried out in still not judgement when described surviving path memory is filled with, and promptly exports the majority in each surviving path initial bit as judgement.

29. time division multiplexing method according to claim 25; It is characterized in that; Described path Euclidean distance memory or weighted euclidean distance memory are only stored relative distance; Even path Euclidean distance or weighted euclidean distance minimum or the maximum are zero distance; The path Euclidean distance memory of other each state or weighted euclidean distance memory are only stored relative Euclidean distance or relative weighted euclidean distance, and said relative Euclidean distance or relative weighted euclidean distance are meant the difference with said path Euclidean distance or weights Euclidean distance minimum or the maximum.

30., it is characterized in that described Sequence Detection is the maximum a posteriori probability Sequence Detection according to claim 1 or 15 described time division multiplexing methods when each sequence unequal probability.

31. a time division multiplexing system is characterized in that said system comprises transmitter and receiver; Wherein transmitter comprises:

Overlapping time division multiplexing modulating unit is used to form overlapped the transmitting on time-domain of a plurality of symbols;

Transmitter unit is used for said transmitting is transmitted into receiver;

Receiver comprises:

Receiving element is used to receive the signal that said transmitter unit is launched;

The Sequence Detection unit is used for carrying out to received signal detecting by data sequence in the time-domain;

Wherein, described overlapping time division multiplexing modulating unit comprises:

Digital waveform generator is used for phase wiggles and orthogonal waveforms with first modulation signal envelope waveform of digital form formation;

Shift register, the phase wiggles and the orthogonal waveforms of first modulation signal envelope waveform that is used for digital waveform generator is produced are shifted, with homophase envelope waveform and the quadrature envelope waveform that produces other each modulation signal;

Serial-parallel converter is used for the data sequence of serial input is converted into the parallel in-phase data signal and the orthogonal data signal of corresponding each modulation signal;

Multiplier; The homophase envelope waveform and the quadrature envelope waveform that are used for the modulation signal that each in-phase data signal of said serial-parallel converter output and orthogonal data signal is corresponding with each multiply each other, with obtain each modulation signal through the filtered modulation signal waveform of data-modulated;

Adder, be used for each modulation signal of multiplier output through the filtered modulation waveform addition of data-modulated, transmit with formation.

32. time division multiplexing according to claim 31 system is characterized in that said transmitter also comprises spectrum-spreading unit, is used to increase overall system bandwidth.

33. time division multiplexing according to claim 31 system is characterized in that said transmitter also comprises interleave unit and coding unit, is used to improve the latent frequency or the latent time diversity tuple of system.

34. time division multiplexing according to claim 31 system is characterized in that said receiver also comprises pretreatment unit, is used for the auxiliary synchronous receiving digital signals sequence that forms in each frame.

35. time division multiplexing according to claim 34 system is characterized in that said pretreatment unit comprises:

Synchronizer, it is synchronous to be used in receiver, forming symbol time to received signal;

Channel estimator is used for channel parameter is estimated;

The digitized processing device is used for the reception signal in each frame is carried out digitized processing.

36. time division multiplexing according to claim 31 system is characterized in that described Sequence Detection unit comprises:

The analytic unit memory; Be used to make the plural convolutional encoding model and the trellis structure of division multiplexing system overlapping time; And list whole states of division multiplexing system overlapping time; And storage, wherein, described overlapping time, whole states of division multiplexing system comprised initial condition, preceding transition state, stable state, back transition state and end-state;

Comparator is used for the trellis structure according to the analyzing stored device, searches out the path that has minimum Eustachian distance or weighting minimum Eustachian distance with receiving digital signals;

The surviving path memory of stable state S is used to store the surviving path that arrives said stable state S;

The Euclidean distance memory of stable state S or weighted euclidean distance memory are used to store the surviving path of the said stable state S of arrival and the relative Euclidean distance or the relative weighted euclidean distance of receiving digital signals sequence;

Wherein, stable state S is any in said whole stable state.

37. time division multiplexing according to claim 36 system; It is characterized in that; Each state has a surviving path memory and Euclidean distance memory or weighted euclidean distance memory, and described transition state can be used the memory of arbitrary stable state with the back transition state.

38., it is characterized in that described surviving path memory length is 4 * K to 5 * K according to the described time division multiplexing of claim 37 system, wherein, K is overlapping tuple.

39., it is characterized in that described surviving path memory length is shorter or longer than 5 * K than 4 * K according to the described time division multiplexing of claim 37 system, wherein, K is overlapping tuple.

40., it is characterized in that described Euclidean distance memory or weighted euclidean distance memory are only stored relative distance according to the described time division multiplexing of claim 37 system.

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