CN1217119A - Process for digital stepped phase modulation of a modulation carrier and system thereof - Google Patents
Process for digital stepped phase modulation of a modulation carrier and system thereof Download PDFInfo
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- CN1217119A CN1217119A CN 97194197 CN97194197A CN1217119A CN 1217119 A CN1217119 A CN 1217119A CN 97194197 CN97194197 CN 97194197 CN 97194197 A CN97194197 A CN 97194197A CN 1217119 A CN1217119 A CN 1217119A
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- phase
- phase place
- stepping
- modulated carrier
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/20—Modulator circuits; Transmitter circuits
- H04L27/2003—Modulator circuits; Transmitter circuits for continuous phase modulation
- H04L27/2007—Modulator circuits; Transmitter circuits for continuous phase modulation in which the phase change within each symbol period is constrained
- H04L27/2017—Modulator circuits; Transmitter circuits for continuous phase modulation in which the phase change within each symbol period is constrained in which the phase changes are non-linear, e.g. generalized and Gaussian minimum shift keying, tamed frequency modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/20—Modulator circuits; Transmitter circuits
- H04L27/2003—Modulator circuits; Transmitter circuits for continuous phase modulation
- H04L27/2007—Modulator circuits; Transmitter circuits for continuous phase modulation in which the phase change within each symbol period is constrained
- H04L27/2014—Modulator circuits; Transmitter circuits for continuous phase modulation in which the phase change within each symbol period is constrained in which the phase changes in a piecewise linear manner during each symbol period, e.g. minimum shift keying, fast frequency shift keying
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
- Transmitters (AREA)
Abstract
The invention concerns a process and a system for digital stepped-phase modulation of a modulation carrier, with which a discrete phase step at constant amplitude is carried out for each digital symbol of a signal to be transmitted. The stepped phases of the modulation carrier are dependent on both the symbol to be transmitted at the present time and on one or more of the symbols previously transmitted. The process and the system of the invention can be used, for instance, in broadcasting especially in mobile radio telephony.
Description
The present invention relates to a kind of method and system that realizes this method of modulating according to the digit phase stepping of claim 1 preamble.
The digital PSK signal modulation is disclosed, for example a digital PSK signal (PSK=phase-shift keying).In digital PSK signal (PSK), relate to a kind of method of modulated carrier, in this method, when the amplitude of modulated carrier and frequency kept constant, a definite phase place of modulated carrier was corresponding to each significant condition of a discrete signal.Transition from a phase place to another phase place can be a continuous or discontinuous variation.Disclose a kind of MSK modulation (minimum keying) in addition, this method is a particular form of CPFSK modulation (continuous phase frequency keying).When CPFSK modulated, it related to a kind of FSK (frequency shift keying) modulation that has the phase place continuous transition between frequency.
The MSK modulation is a CPFSK modulation with one 0.5 index of modulation, and above-mentioned coefficient draws a compensation between anti-interference and required frequency bandwidth when orthogonal signalling and minimum frequency shift.MSK modulation generally requires a satisfactory sometimes high-transmission bandwidth or draws a very little message transmission rate, and for example the variant of the modification by disclosed GMSK modulation (Gaussian minimum keying) usually can not use enough methods to improve this said method.
The GMSK modulation for example is applied in the mobile radio system.Such mobile radio system is at M.Mouly, M.-B Pautet " gsm system of mobile communication ", and 1992, disclosed gsm system in the 249-259 page or leaf especially.
Task of the present invention is to set up the digit phase stepping modulator approach of an improvement, this method is enough with respect to obvious reduced transmission bandwidth of disclosed the sort of modulation format, allows a message transmission rate that has improved or a signal to noise ratio that is enhanced is described.To set up the system of a realization in addition according to the inventive method.
According to the present invention, in a method, solve this task by feature at claim 1 declaratives according to claim 1 preorder.Explanation is according to the preferred and suitable other design of the inventive method in appended claims.
Explanation realizes a system according to the inventive method in claim 17.Following claim comprises that this system meets purpose design and operational feasibility in addition in emission and reciever.
According to three forms and a figure the method according to this invention and a system are described below by embodiment.
Table 1
Considering one in for example phase place stepping when 4 are worth symbols under the situation of the symbol of back,
Table 2
Phase place stepping in known MSK modulation and in a MSK who constitutes according to the present invention modulates,
Table 3
Have the minimum interval bit sequence and
Figure
Two phase place stepping curves on a position beat are for the comparison between the MSK of a known MSK system and a modification of work according to the present invention modulation.
In digit phase stepping modulation according to the present invention, each symbol for the signal that will transmit is implemented in a discrete phase place stepping in the modulated carrier.The phase place stepping depends on current with the symbol that is transmitted with depend on symbols of one or transmission before several respectively in addition.
Before the pulse modulation of the reality that realizes modulated carrier, preferably in a filtering or a pulse shaping transition, carry out discrete steps.At this moment preferably use the Gauss or the sinusoidal form of pulse transition.At this moment the constant amplitude that keeps modulated carrier.
Except Gauss or sinusoidal form can also can also be selected the slope of a phase transitions according to a power function or existing formation.Can also select the transit time of all phase transitions in addition, make transit time constant.Can select the greatest gradient of phase transitions, make this slope keep constant.Depend on current phase place stepping, draw different transit times, however the temporary transient frequency of identical maximum.
Under simple scenario, symbol comprises the independent position that will transmit, has two or the position that more will transmit in contrast for senior modulation.At this moment the consideration degree of depth that is positioned at the back symbol in time can preferably be selected according to transmission conditions (disturbing channel condition) and transmission requirement (bandwidth, data rate) by different selections.As other design, the character position current in flows of data signals that depends on that the phase place stepping of realization can add is realized.Select by enforcement, can realize tangible improvement for known digit phase stepping modulator approach to the parameter of above explanation.Here be improvement or signal to noise ratio about the improvement of special interest by the bandwidth requirement that reduces modulated carrier.
This modulation can illustrate by the table of current phase place stepping and phase value and can realize, for an of signal symbol that is transmitted depended on the symbol that has in advance transmitted on the time and uses above-mentioned value.In table 1, under the situation of considering an above-mentioned symbol, the example of one 4 value symbol is described.In the situation about adopting in example, phase place stepping table 1 also comprises 16 values.In table 1, use S0 to S3 to represent symbol, the phase place stepping of using P0 to P15 to express possibility.
If will consider to surpass a symbol, the quantity of the phase place step value that so corresponding raising is possible in the back.Can select the phase place stepping arbitrarily in principle.But for the expected effect of realizing determining, only different phase place stepping seldom is essential or the phase place stepping may be followed simple regularity.
Modulate a particularly preferred embodiment of that constitute according to the present invention, a digital phase place stepped form of comparative descriptions below with known MSK.In known MSK modulation format, use two phase place stepping+90 (with-90 (, and it does not consider the symbol in the back.Independent phase place stepping is by lf, and promptly all transition from a phase state to another phase state are in the realization of a bit period internal linear.If use Gauss to filter the linear modulation that transition replaces the MSK modulation, same known GMSK modulation format is derived from this modulation.
In table 2, be arranged on phase place stepping and the phase place stepping in a MSK modulation format that constitutes according to the present invention in the known MSK modulation on the contrary based on digit phase stepping modulation under the situation of the position of considering a back, above-mentioned MSK modulation format is known as the MSK modulation that is modified below.The modulation of revising obviously reduces the bandwidth requirement of modulated carrier.
As fundamental difference, recognize at Fig. 2: from now on, except two disclosed existing phase place stepping+90 in disclosed MSK modulation (with-90 (, another one 0 (phase place stepping also is provided.
If current transmission was different with former directly emission position, so always use 0 (phase place stepping, i.e. presence bit sequence 0-1 or 1-0.If two continuous mutually positions are identical, promptly presence bit sequence 0-0 or 1-1 will use identical phase place stepping so as when known MSK modulation.
Between according to table 2 modulation relatively, exist following difference: not distinct in two kinds of modulation systems for pure 0 sequence or pure 1 sequence.When transmission 0-1 sequence, in known MSK modulation, realize a stable exchange of phase place stepping symbol in contrast.In the MSK of this represented modification modulation, record does not change phase place in contrast according in the modulator approach of the present invention.
This means for the frequency bandwidth expansion that the highest modulating frequency and the therefore expansion of modulated carrier in disclosed MSK modulator approach, occur, in the MSK modulation format of revising, especially effectively not to carrier modulation.In the MSK modulated applications of revising according to the present invention, therefore significant the reduction because modulation takies the bandwidth of frequency spectrum.
In order to estimate the reduction of this spectral bandwidth to a modulated signals, consider the highest effective modulating frequency in both cases below.In known MSK modulation, this situation along with half bit frequency and triangle along with (45 (and a maximal phase potential difference occur.In the MSK modulation of revising according to the present invention, when the 0-0-1-1-bit sequence, there is the highest modulating frequency.Therefore the highest modulating frequency only is 1/4th of a bit frequency.The same position of maximum phase difference (45 (.Modulation uses a trapezoidal modulation signal to realize in addition, and the remarkable less harmonic wave of this modulation signal is the triangle signal of the MSK modulation of relatively introducing as one.
One also causes significantly reducing the modulation bandwidth needs according to modulation of the present invention.In the MSK modulation that is modified according to the present invention, the direction in the phase place changes the modulation stepping realization by having constant phase by always.Therefore this coding illustrates a filtration in advance to a certain degree of modulation signal.Because the GMSK modulation draws from known MSK modulation by a gaussian filtering, so this enforcement also is suitable for a GSMK modulation of revising according to the present invention naturally, the GMSK modulation is for example used in GSM (global system for mobile communications) mobile radio system.
In the example that from figure, illustrates, pass through the phase place stepping curve of a position beat curve representation from two, for the identical signal that will transmit, the MSK modulation of recognizing the phase modulated of the centre that known MSK modulation (referring to curve described above among the figure) draws and revising according to the present invention (referring to the middle curve that illustrates among the figure) is similar.Yet difference is in the MSK that is modified modulation to occur slowly that direction changes with comparing in known MSK modulation.This means that with known MSK chopping phase ratio, high-frequency modulating part is significantly reduced in the MSK modulation of revising according to the present invention.At two in the drawings in the adjustment curves of explanation, after other Gauss filters, draw an obvious level and smooth curve of effective phase place of a modulated carrier than the situation of GMSK modulation, wherein reflected the frequency bandwidth requirement that has reduced.
Insert the characteristic that weaken of MSK modulation that the 3rd phase place stepping can not cause being modified according to the present invention, although three feasible end-state of phase place may occur and therefore by an euclidean explanation of dwindling about disturbing.In practice, always must between two states, distinguish because will never occur from+90 (to-90 (and direct conversion or opposite transition.
Interconnect continuous phase place stepping mutually in logic by modulating rule in addition.Therefore may judge and the independent judgement of error recovery, i.e. modulation hereto, Trellis-decoding than one separately the position decoding draw a characteristic that significantly improves.
For known MSK modulation and the MSK modulation that is modified according to the present invention, in table 3, has minimum arduous sequence according to Trellis-decoding explanation.The sequence length of the MSK modulation of revising according to the present invention is Duoed one than the sequence length of known MSK modulation.If mistake, so according to table 3 in both cases it as adjacent doubling wrong appearance the in being.
When effectively detecting the recipient, should consider that also modulation is regular.General basis position judgement separately will draw a bit error probability that is enhanced.According to " maximum Likelihood "-detection, therefore yet modulator approach according to the present invention allows a reduction of proposing of the spectral bandwidth required value of a signal, and reduces the bandwidth of a transmission channel or improve and improve data rate under the identical situation of transmission channel bandwidth.
Only because simplified illustration in proportion, more than select the MSK modulation as an example.The GMSK that is suitable for of ratio all fours modulates, and resembles it and for example is used in the GSM mobile radio system.Because mobile radio system in fact always is limited on frequency, so an effective modulation obtains a remarkable meaning.Therefore because the additional frequency of GMSK is filtered, and GMSK modulation ratio MSK modulation obtains an obvious bigger meaning, they only can reasonably be used, if propose suitable requirement for frequency efficiency.
Realization according to phase place stepping modulator approach of the present invention in a system can be similar at present known system's realization in emission side.Therefore the phase place that is fit to or the curve of two quadrature components are that I component and Q component are placed in the table.The address of these tables comes out to constitute by the position of present transmission and the counter total that uses a use to double a beat job.Therefore determine the accurate curve of phase place.Master phase generally derives from present phase place stepping and therefore addition.
A quite simple situation of a MSK more than explanation, that revise according to the present invention or a digital phase modulation of GMSK modulation explanation is because actively consider the position of a back.The length that this generally can resemble the bandwidth needs of the reduction frequency of pointing out in the example and improve minmal sequence by means of the phase place stepping modulator approach according to the present invention.Use according to the present invention phase place stepping modulator approach in mobile radio system as being particularly preferred in the GSM mobile radio system.
For radio system, particularly senior modulation according to principle of the invention work, wherein two or more constitute a symbol of a transmission signals on carrier wave, so that transmission signals that can two-forty.
In order to realize a mobile radio system, the other design of system according to the invention is being used than being suggestion will be transmitted under the situation of 1/2 convolutional encoding data rate as 16kbit/s and for the data rate of mobile radio system so-called " half rate " passage suggestion 8kbit/s for so-called " full rate " passage.In this relation, improve " limited length " of convolutional encoding with respect to the gsm system suggestion of present employing.
Phase place stepping modulation that constitutes according to the present invention and illustrated other design allow to use 14.4 and the transfer of data of 16kbit/s speed, this with respect to present in GSM the speed of maximum accessible 9.6kbit/s, significantly improve.Can use 8kbit/s to realize a preferable quality basically for voice transfer on " half rate " passage, than the 6.6kbit/s that uses the part protection in the present GSM mobile radio system.
Therefore the last-mentioned fact has special meaning, because have bigger needs for the speech coding of the frame time of data rate with 8kbit/s that adopts " half rate " and 10ms, can double the active block capacity by it.In addition, make in this way speech coding reduce the time-delay of the about 90ms that in gsm system, occurs at present.
Claims (27)
1. the method for a modulated carrier is modulated in the digit phase stepping, wherein for each numerical chracter that will transmit of a signal, when keeping constant amplitude, realize a discrete phase place stepping, it is characterized in that the phase step progress that will carry out of modulated carrier is advanced to depend on respectively the current symbol that will transmit and depended on one or several symbols that transmit before this.
2. according to the method for claim 1, it is characterized in that in discrete phase stepping transition, stepping is filtered or shaping pulse to discrete phase before realizing modulated carrier being carried out the phase modulated of reality.
3. according to the method for claim 2, it is characterized in that the Gauss on the phase transitions of modulated carrier or the filtered version of sinusoidal form.
4. according to the method for claim 2, it is characterized in that according to the filtered version on the phase transitions of the modulated carrier of power function.
5. according to the method for claim 2, it is characterized in that lf form on the phase transitions of modulated carrier.
6. according to any method in the claim 2 to 5, it is characterized in that selecting a definite slope of the phase transitions of modulated carrier.
7. according to any method in the claim 2 to 5, be constant the transit time that it is characterized in that all phase transitions of modulated carrier.
8. according to any method in the claim 2 to 5, the greatest gradient that it is characterized in that the phase transitions of modulated carrier is constant.
9. according to any method in the above claim, it is characterized in that to select the consideration degree of depth of transmission symbol in advance.
10. according to any method in the above claim, it is characterized in that the additional position that depends on current sign in a data flow of phase place stepping.
11. according to any method in the above claim, it is characterized in that considering modulated carrier reduction bandwidth requirement select phase place stepping and transition parameter.
12., it is characterized in that the signal to noise ratio of considering improvement selects phase place stepping and transition parameter according to any method in the claim 1 to 10.
13. according to any method in the above claim, it is characterized in that current phase place stepping and phase value being described that they depend on the symbol that has transmitted and are used to the symbol that will be transmitted in the mode of table.
14. according to any method in the above claim, in the symbol that comprises (0 or 1) and in the application under the situation of the position of only considering present bit and this direct neighbor, when constituting the phase place stepping, if when it is characterized in that the position different (=bit sequence 0-1 or 1-0) of the each current position that will transmit and direct transmission before this, always be to use 0 ° (the phase place stepping, when if the each current position that will transmit and the position of directly transmitting before this have logic state 0 (=bit sequence 0-0), always be to use-90 ° (the phase place stepping, if the each current position that will transmit and when directly the position of transmission has logic state (=bit sequence 1-1) before this, always be to use+90 ° (phase place stepping (MSK that revised modulates).
15. according to any method in the claim 1 to 13, when constituting the phase place stepping, in the symbol that comprises (0 or 1) and in the application under the situation of the position of only considering present bit and this direct neighbor, if when it is characterized in that the position different (=bit sequence 0-1 or 1-0) of the each current position that will transmit and direct transmission before this, always be to use 0 ° (the phase place stepping, when if the each current position that will transmit and the position of directly transmitting before this have logic state 0 (=bit sequence 0-0), always be to use+90 ° (the phase place stepping, if the each current position that will transmit and when directly the position of transmission has logic state (=bit sequence 1-1) before this, always be to use-90 ° (phase place stepping (MSK that revised modulates).
16., it is characterized in that the recipient according to surveying the judgement of wrongheaded independent position by the logical operation of modulating the mutual continuous phase place stepping that regularity provides and proofreading and correct according to any method in the above claim.
17. realize system according to claim 1, it is characterized in that in emission side, in order to modulate a modulated carrier, a phase place stepping modulator is provided, this modulator adopts discrete phase place stepping for the numerical chracter of each signal that will transmit when amplitude keeps constant, wherein these phase places not only depend on the current symbol that will transmit but also depend on one or several are directly at its preceding transmission symbol.
18., it is characterized in that in phase place stepping modulator that in the transition of discrete phase stepping, stepping is filtered or shaping pulse to discrete phase according to the system of claim 17, before the phase modulated that realizes modulated carrier reality.
19. according to any system in claim 17 and 18, it is characterized in that in emission side, in table, put into the process of phase place stepping or two quadrature components (I-and Q component), it is characterized in that the output of the counter that method that position and usefulness by emission up to now double a beat illustrates constitutes the address of this form, therefore therefrom determine the accurate process of a phase place, and it is characterized in that deriving master phase and addition from present phase place stepping.
20., it is characterized in that providing a detecting devices, in this equipment the recipient according to any system in the claim 17 to 19, in order to survey symbol, based on " maximum-Likelihood "-detection, replenish separately and judge, also consider the regularity of predetermined modulation.
21., it is characterized in that manufacturing and designing as mobile radio system according to any system in the claim 17 to 20.
22. according to the system of claim 21 as GSM or be similar to the GSM mobile radio system and manufacture and design.
23. according to any system in the claim 18 to 22, it is characterized in that next manufacturing and designing Gauss, sine, linearity or a close function and filter, perhaps when shaping pulse, select a definite slope of modulated carrier phase transitions.
24. according to the system of claim 23, the greatest gradient of phase transitions that it is characterized in that selecting modulated carrier is as constant.
25. according to any system in the claim 18 to 24, it is characterized in that when the recipient surveys, according to judging and proofread and correct in the independent position of the logical operation identification error by modulating the mutual continuous phase place stepping that regularity provides.
26. according to any system in the claim 18 to 25, it is characterized in that for so-called " full rate " passage, under the condition of the convolutional encoding of using 1/2 speed, provide the data rate of 16kbit/s, for so-called " half rate " passage, provide the data rate of 8kbit/s.
27. according to any system in the claim 18 to 26, it is characterized in that mobile radio system, improve so-called " limited length " of convolutional encoding in advance with respect to GSM.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE1996117141 DE19617141C1 (en) | 1996-04-29 | 1996-04-29 | Process for digital phase step modulation and system for carrying out the process |
| DE19617141.5 | 1996-04-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1217119A true CN1217119A (en) | 1999-05-19 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 97194197 Pending CN1217119A (en) | 1996-04-29 | 1997-04-29 | Process for digital stepped phase modulation of a modulation carrier and system thereof |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JP2000511009A (en) |
| CN (1) | CN1217119A (en) |
| DE (1) | DE19617141C1 (en) |
| WO (1) | WO1997041671A2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI104773B (en) * | 1998-04-17 | 2000-03-31 | Nokia Networks Oy | Method and arrangement for signal modulation |
| FI980911A (en) | 1998-04-24 | 1999-10-25 | Nokia Networks Oy | resonator |
| FR2961988B1 (en) | 2010-06-25 | 2012-07-27 | Commissariat Energie Atomique | METHOD FOR PHASE MODULATION OF A CARRIER SIGNAL FROM A TRANSMITTER TO A CONTACTLESS TRANSPONDER AND DEVICE FOR IMPLEMENTING THE SAME |
-
1996
- 1996-04-29 DE DE1996117141 patent/DE19617141C1/en not_active Expired - Fee Related
-
1997
- 1997-04-29 JP JP09538462A patent/JP2000511009A/en active Pending
- 1997-04-29 WO PCT/DE1997/000875 patent/WO1997041671A2/en active Application Filing
- 1997-04-29 CN CN 97194197 patent/CN1217119A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JP2000511009A (en) | 2000-08-22 |
| DE19617141C1 (en) | 1997-11-20 |
| WO1997041671A3 (en) | 1998-02-05 |
| WO1997041671A2 (en) | 1997-11-06 |
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