CN101473552B - Multi-antenna transmission with small dynamic power range in OFDM system - Google Patents
Multi-antenna transmission with small dynamic power range in OFDM system Download PDFInfo
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- CN101473552B CN101473552B CN2007800232986A CN200780023298A CN101473552B CN 101473552 B CN101473552 B CN 101473552B CN 2007800232986 A CN2007800232986 A CN 2007800232986A CN 200780023298 A CN200780023298 A CN 200780023298A CN 101473552 B CN101473552 B CN 101473552B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/38—TPC being performed in particular situations
- H04W52/42—TPC being performed in particular situations in systems with time, space, frequency or polarisation diversity
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2614—Peak power aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2626—Arrangements specific to the transmitter only
Abstract
An improved method for reduction of transmit signal power dynamics in an Orthogonal Frequency Division Multiplex (OFDM) transmitter having at least two antennas is disclosed. According to the invention, the following steps are performed by the transmitter: partitioning an OFDM symbol of a signal to be transmitted into at least two partial OFDM symbols, the partitioning being controlled so as to keep down a power dynamics measure determined for each of the at least two partial OFDM symbols, where the power dynamics measure relates to samples of the signal for which a power of the signal exceeds a threshold power, the threshold power being larger than or equal to an average power for the signal, and transmitting each of the at least two partial OFDM symbols from one of the at least two antennas.
Description
Technical field
The present invention relates to a kind of method that in having the Orthodoxy Frequency Division Multiplex of two antennas (OFDM) transmitter, reduces transmit signal power dynamic change (dynamics) at least.
The present invention relates to a kind of transmitter with at least two antennas that in Orthodoxy Frequency Division Multiplex (OFDM), reduces the transmit signal power dynamic change simultaneously.
The present invention relates to a kind of relevant telecommunication system simultaneously.
Background technology
Many wireless standards have adopted Orthodoxy Frequency Division Multiplex (OFDM) technology.If the signal of launching in the ofdm system is not handled, the signal of this emission often has bigger signal dynamics to be changed.
Ofdm signal is multiplexing (multiplex) to modulated carrier wave.Specifically, each sample (sample) of ofdm signal is the weighted sum of similar distributed random variable, thereby when the quantity of OFDM subcarrier is very big, can form the distribution of amplitudes of a kind of similar Rayleigh.The end of this distribution demonstrates bigger signal peak, and in order to launch the signal that has than the large-signal peak value, the high power amplifier in the transmitter must be supported the dynamic change scope of non-constant width.Because this high power amplifier with dynamic change scope of non-constant width costs an arm and a leg, thus generally, launch this have than the cost of the signal of large-signal peak value greatly and energy utilization rate lower.
The method of dynamic change of reducing to transmit can reduce transmitter price and can energy savings.The dynamic change of signal has a plurality of different definition, and the most frequently used two kinds are defined as: long-term peak averaging value power ratio (RAPR) and short-term RAPR.Must consider the probability that the peak occurs during the measurement of in fact, being correlated with.
In order to alleviate the problems referred to above, discussed too high problem of PAPR standard and the technology that reduces PAPR in numerous publication and the patent.First kind solution has been sacrificed data rate (bandwidth) based on coding.Second type of solution handled (phase manipulation) based on scrambling or phase place, sacrificed a large amount of armed coding side-informations.The 3rd type of solution, promptly " tone keeps (tonereservation) " solution does not reduce peak power with carrier wave with the signal insertion.The 4th type of solution adopts " non-dijection clump (non-bijective constellations) ".
In addition, in the prior art,, realized reducing peak power through Signal Separation for non-ofdm signals.Particularly specifically, for so-called Chireix anti-phase (outphasing) amplifier, realized Signal Separation.In list of references [1]; Signal with high-peak power is divided into independent (partial) signal that two dynamic changes are 0dB (constant envelope) (two independent signals and for this has the signal that the peak causes power), and each independent signal is amplified by the power amplifier of self respectively.High-power signal phase adduction after amplifying is launched through an antenna.
The antenna selection diversity of in list of references [2], describing is realized the emission classification through the selection to antenna.At each constantly, according to from mobile receiver,, select optimum antenna and transmit about the feedback of down channel state.Sky line options in the list of references [2] only is used for transmit diversity, and is irrelevant completely with power dynamics.
Other lists of references are for example mentioned in list of references [3] and [4], in order to realize classification, signal is divided into two parts possibly brings the side effect that reduces PAPR.But,, only when paying close attention to the advantage of dividing collection, just signal is separated according to the branch collection separation method shown in the list of references.Therefore, this because the positive PAPR effect that Signal Separation is brought is far from the best.
Especially, the positive PAPR effect that signal separating method is obtained in the list of references [3] draws according to following brass tacks: after signal constituted the OFDM symbol separately, the tone (tone) in each independent signal was less than the tone that separates in the front signal.Therefore, any is the method for two signals through the sky line options with Signal Separation, and no matter implementing this method cause is what, all may make the OFDM symbol in each independent signal have less tone, thereby reduces PAPR.But regardless of the frequency that peak value occurs, these methods all can reduce PAPR.In addition,, when the advantage of only considering to divide collection, just signal is separated, can not be directed against the signal power dynamic change, realize the optimization of separating according to the scheme in list of references [3] and [4].
Summary of the invention
In view of this, the embodiment of the invention has proposed a kind of OFDM transmitter with a plurality of antennas.In embodiments of the present invention, a plurality of representatives are at least two.
In addition, the embodiment of the invention provides a kind of method that reduces the signal power dynamic change that is superior to prior art.
When realizing above-mentioned purpose through method, in said method, transmitter is carried out following steps:
The OFDM symbol of signal to be transmitted is separated at least two independent OFDM symbols; Thereby said separation is controlled and makes the power dynamics measure of confirming for each symbol in said at least two independent OFDM symbols keep low level; Wherein said power dynamics measure is relevant with the sample of said signal; Said signal is the signal that power surpasses threshold power, and said threshold value is more than or equal to the average power of said signal; Wherein said separation comprises: the set of subcarriers that will be used to launch said signal separates into the subclass of at least two subcarriers; Give a symbol in said at least two independent OFDM symbols with each subset allocation of said at least two subset; Each symbol in said at least two the independent OFDM symbols of antenna emission from said at least two antennas.
The embodiment of the invention also provides a kind of device that in having the OFDM transmitter of two antennas, reduces the transmit signal power dynamic change at least, comprising:
The OFDM symbol of signal to be transmitted is separated into the module of at least two independent OFDM symbols; Thereby said separation is controlled and makes the power dynamics measure of confirming for each symbol in said at least two independent OFDM symbols keep low level; Wherein said power dynamics measure is relevant with the sample of said signal; Said signal is the signal that power surpasses threshold power, and said threshold value is more than or equal to the average power of said signal; Wherein said separation comprises: the set of subcarriers that will be used to launch said signal separates into the subclass of at least two subcarriers; Give a symbol in said at least two independent OFDM symbols with each subset allocation of said at least two subset; With, the module of each symbol in said at least two the independent OFDM symbols of antenna emission from said at least two antennas.
In embodiments of the present invention, comprise at least one above-mentioned transmitter in the telecommunication system.
Reduce in the method for signal power dynamic change the OFDM symbol to be separated in the present invention, thereby make each isolated sign all have lower signal power dynamic change.Each selection in the separation process is all made the signal power dynamic effects according to it.Therefore realized optimal separation to the signal power dynamic change.
In addition, the present invention has adopted the measured value that changes to signal dynamics, and this measured value is useful and can directly be used for the design of power amplifier, thus the optimization that reduces that further makes signal power dynamic change in the system.When estimating this measured value, only consideration estimates that above the value of the signal of a certain threshold value this threshold value is the same with long term average power at least high power level.
Simultaneously,, the invention provides transmit diversity, thereby make that active region throughput bigger and/or system potentially is bigger as positive side effect.
In an embodiment of the present invention, the set of subcarriers that is used to launch this signal is at least two subsets of subcarriers by alternate analysis, and each subclass in these subclass is assigned to an independent OFDM symbol then.Alternate analysis in the present embodiment comprises: at first generate the subclass of several subcarriers, wherein the quantity of subclass is given the allocation of carriers first time in the set of subcarriers subclass of a generation corresponding to the quantity of used antenna.Then, each unallocated subcarrier of subcarrier collection is distributed to the subclass of a generation successively, all be assigned with up to all subcarriers.Wherein, all distribution are all made based on power dynamics measure.
In embodiments of the present invention, adopted the alternate analysis of another kind of formation subsets of subcarriers.According to this alternate analysis, to each subcarrier, at first generate a sub-set, each subcarrier is assigned to a different sub-set in the generating subset in the set of subcarriers.Then, generating subset merges in twos, till the merging number of subsets is corresponding to used antenna number.
Above-mentioned alternate analysis all has following advantage: the ofdm signal of emission has good power dynamics properties, and transmitter has lower complexity.
Power dynamics measure is calculated according to following mode in embodiments of the present invention: to each independent OFDM symbol, will surpass the relevant item addition of sample of the signal of threshold power with power.
Power dynamics measure is calculated according to following mode in embodiments of the present invention: from independent OFDM symbolic look-up maximum power value, a consideration of power surpasses the performance number of threshold power in this process.
Above-mentioned power dynamics measure computational methods have following advantage: be easy to realize and can provide useful measured value, thereby can carry out the accurate separation of ten minutes.Can adjust this threshold value, so that meet the requirement of particular transmitter.
In embodiments of the present invention, used predetermined subbands of subcarriers.Subband substitutes subcarrier and is assigned to subclass then, and subclass is assigned to independent OFDM symbol afterwards.Its advantage is: owing to predetermined subband is widely used in many ofdm systems, thereby make that such scheme is a kind of low complex degree solution that can in most of ofdm systems, realize.
Below in conjunction with preferred embodiment of the present invention and accompanying drawing, embodiment and the advantage thereof that reduces power dynamics described.
Description of drawings
In order more fully to understand the embodiment of the invention and advantage thereof, can combine accompanying drawing with reference to following explanation, the same tag in the accompanying drawing is represented identical part:
Fig. 1 is the sketch map of transmitter among the present invention;
Fig. 2 is the flow chart of alternate analysis algorithm among the present invention;
Fig. 3 is the flow chart of alternate analysis algorithm among the present invention;
Fig. 4 is alternate analysis algorithm simulating result's among the present invention sketch map.
Embodiment
The ofdm signal of emission comprises a series of OFDM symbols.According to the embodiment of the invention; To each OFDM symbol; Transmitter separates into two or more independent OFDM symbols (itself and for this OFDM symbol) with this OFDM symbol, and each the OFDM symbol from above-mentioned two or more the independent OFDM symbols of different antennae emission.
In embodiments of the present invention, the OFDM symbol is separated, thereby make each isolated sign have the low signal power dynamic change.Thereby, in the present invention, carried out helping " intelligence " separation of signal power dynamic change.And in the solution of list of references [3] and [4] description, be merely and realized dividing the collection optimization and separating.
Special, in the present invention, the indexed set of all subcarriers in the OFDM symbol (index set) is separated by a plurality of subclass, afterwards, and a symbol associating in the independent OFDM symbol of each subclass and appointment (constituting).Thereby each independent OFDM symbol itself is exactly an OFDM symbol.To each the OFDM symbol in the ofdm signal, carry out the selection that subclass is separated respectively.Thereby realize separating to the optimization of signal power dynamic change.
Simultaneously, the invention solves the big problem of signal power dynamic change, utilized with existing solution in the measured value of measured value various signals dynamic change of use, thereby further improved signal power dynamic change problem.
In the prior art, usually with the measured value of PAPR measured value as the signal power dynamic change.Being defined as of PAPR measured value: the power of single worst case ofdm signal sample is divided by the average power of signal.Occur because this worst case sample is few usually, the practical value of this definition is very little.For example, in having the BPSK modulating system of 128 sub-set, worst case sample just appears one time in every 2^127 OFDM symbol, and promptly sample rate is 10KHz, and millions of Nian Caihui occur once.Therefore, for the Amplifier Design personnel, for the optimal optimization of the power amplifier in the OFDM reflector, it is used in reality, the use of PAPR measured value is little.Because it line options is very " stupid (Dumb) ", as list of references [3] and [4] are done, use the PAPR measured value during Signal Separation, under the situation for " non-separation ", there is not actual advantage.This point is with describing in detail in the specification below.
Different with prior art is, used among the present invention a kind of with actual relevant measured value, for example, the chance of appearance in time greater than 0.1% power measurement values.To the signal dynamics change measure of the regular power (long term average power to signal is standardized) of x percentage, particularly useful for Designing power amplifier.Surpass x%, the measured value that will have the detail specifications power level in time when transmitting.In fact, work as x=0.1, common baseband OFDM signal has the 0.1 percentile regularization power of 9.6dB usually.
When this measured value of estimation, can consider to surpass all signal values of a certain threshold value, this threshold value is identical with long term average power at least power level.Through using above-mentioned practical especially measured value to describe the signal power dynamic change, can have bigger improved separation from the angle of signal power dynamic change.
In addition, as a positive effect, the present invention has realized the transmit diversity in the fading channel environment through the transmission at least two independent wireless channels.The separation of above-mentioned enhancing and divide the collection effect can increase potential coverage and/or improve the throughput of system.
Fig. 1 shows when adopting two transmitting antennas, presses the simplified structure of the OFDM transmitter of work of the present invention.According to shown in Figure 1, an ofdm signal s (t) is divided into two independent ofdm signal s1 (t) and s2 (t).Respectively these two independent ofdm signal s1 (t) and s2 (t) are amplified then and launch.
The separation process that signal s (t) is separated into signal s1 (t) and s2 (t) will be detailed hereinafter.
According to the present invention; When the OFDM transmitter that use has many antennas is launched; Can reduce the transmit signal power dynamic change in the signal through following intelligent process: the OFDM symbol is separated into independent OFDM symbol, launch this independent OFDM symbol independently through many antennas of transmitter then.The intelligence of this program is embodied in: through separating the independent OFDM symbol that obtains, estimate its actual related power dynamics measure to each, thus the power dynamics of the signal that accurate control obtains.To this power dynamics measure, signal power is surpassed certain value, promptly the sample of the signal of threshold value is gathered and is assessed.In order to meet the requirement of particular transmitter, can adjust this threshold value.
When concrete the realization, when transmitting antenna need be launched the signal that comprises the OFDM symbol,, at first set of subcarriers is separated into the subclass of at least two subcarriers in order to separate the OFDM symbol.The quantity of the transmitting antenna that wherein, uses according to transmitter is confirmed the quantity of subclass.Afterwards, each subclass of at least two subset at first with at least two independent OFDM symbols in an independent OFDM symbol carry out related, again with many antennas in a different antennas carry out related.
Can use multiple mode, the set of subcarriers of carrying the OFDM symbol separated into the subclass of at least two subcarriers.Wherein a kind of mode comprises: to the separate mode of each possible set of subcarriers, estimation is selected to make used power dynamics measure have the separate mode of optimal value as the result's of this separate mode power dynamics then.
Above-mentioned separate mode possibly be the exhaustive search of carrying out for the optimal separation of searching the OFDM symbol, and its result is very accurate, but this separate mode calculation of complex of while.
Can assess the separate mode of variable number, that is to say, can assess P possible separate mode, wherein P can be any number that is less than or equal to all possible separate mode.
Iterative algorithm can be used to separate the set of subcarriers of carrying the OFDM symbol.Specify two examples of iterative algorithm among the present invention below.At first provide two examples of the dynamic criterion of power, iterative algorithm uses the different step in two kinds of algorithms of the dynamic criterion assessment of power.
According to the present invention, the generation of isolated sign in the transmitter, promptly, relevant with the signal power dynamics measure that matches to the separation of the set of subcarrier index.With undefined criterion is two kinds of possible signal power dynamics measure that match.
According to the present invention, this criterion is only calculated the sample of corresponding power value above certain threshold value T, specifically, when the estimation criterion, only considers to have shape such as Ω
iThe sample of signal of sample index, wherein
Ω
i=k ∈ 0,1 ... N-1}where|s
i(k) |
2＞T} (equation 1)
Wherein, N is the sample number in the OFDM symbol, s
i(k) sample of i independent OFDM symbol of expression.
Can adopt multiple mode to define this criterion.Provide two examples below.
Criterion can be defined as:
Wherein, for example, the representative value of α is 0,1 or 2.If α=0, the quantity that surpasses the sample of threshold value is minimized, if α=2, the energy that surpasses in the sample of threshold value is minimized.To each independent OFDM symbol s
i(k), this criterion is all additions relevant with the sample of independent OFDM symbol, wherein, the power of the signal of sample that should independent OFDM symbol surpassed threshold value T.
Criterion also can be defined as:
This criterion is from each independent OFDM symbol s
i(k) find out maximum power value in, wherein, only consider that signal power surpasses the pairing performance number of signal of threshold value T.
According to general knowledge as well known to those skilled in the art, can also adopt other to be used for the criterion of signal power dynamic change.
Make the criterion of using between the independent OFDM symbol, i.e. equation 2 or 3, minimized separate mode is the optimal separation mode of OFDM symbol.
As stated, can select the mode of separating, test all possible separate mode, confirm the criterion value of every kind of separate mode and select optimum value wherein through exhaustive search.So, though separation is very accurate, calculate also very complicated.
The selection that can adopt the suboptimum algorithm to separate.This type suboptimum algorithm relates to iterative algorithm, and with respect to above-mentioned exhaustive search mode, its accuracy reduces to some extent, but computation complexity is far below exhaustive search.
According to the embodiment of the invention, in separation process, can adopt iteration function based on following algorithm.In this algorithm, give specific stand-alone antenna through distributing a subcarrier in time, progressively set up independent symbols, this algorithm is the harm minimum that equation 2 or 3 causes to used criterion.
Fig. 2 shows the flow chart of this algorithm, comprises following logic step:
1. allocation of carriers is to first subclass of M subset for the first time, and wherein, M is the quantity of used transmitting antenna;
2. give particular subset with next sub-carrier allocation, thereby make the added value of used criterion minimum;
3., turn to step 2 if all subcarriers all are not assigned with;
4. stop.
Thereby, according to this algorithm, generate the subclass of a plurality of subcarriers, wherein the quantity of the corresponding used antenna of the quantity of subclass.Then, each subcarrier that is not assigned with in the set of subcarriers is assigned to the sub-set in the subclass that has generated successively.
Through carrying out above-mentioned distribution, making used criterion is that equation 2 or 3 minimizes.That is to say; Can be with sub-carrier allocation to each subclass that has generated; The above-mentioned possible method of salary distribution all can produce the increment of a power dynamics measure; Increment to this power dynamics measure is assessed, and selects to make the minimum method of salary distribution of increment of power dynamics measure.In other words, through above-mentioned distribution, launch ofdm signal power dynamics minimize.
In the present embodiment, use the alternate analysis algorithm that the OFDM symbol is separated into independent OFDM symbol, say that from the angle of available power dynamic change above-mentioned separation is best.
According to the embodiment of the invention, can be used to separation process based on the iteration function of following algorithm.In this algorithm, through the subsets of subcarriers that has generated being divided into groups, progressively construct the corresponding independent signal of OFDM symbol separately with many, so, be the harm minimum of equation 2 or 3 to used criterion.Fig. 3 shows the flow chart of this algorithm, comprising following logic step:
1. generate N subcarrier subset of indices, comprise a subcarrier in each subclass, wherein N is the subcarrier quantity in the OFDM symbol.
2. two sub-set are merged into a sub-set, thereby make the added value of used criterion minimum;
3. if the quantity of subclass turns to step 2 greater than the quantity of antenna;
4. stop.
Thereby, according to this algorithm, having generated a plurality of subsets of subcarriers, the number of subsets that wherein generates is corresponding to the number of sub-carriers in the set of subcarriers.Each subcarrier in the set of subcarriers is assigned to the different subclass in the subclass of generation successively then.Thereby, the subclass quantity that after this exists with originally in set of subcarriers subcarrier quantity identical, comprise a subcarrier in each subclass.Then, these subclass combine in twos, and order travels through all subclass, thereby after carrying out above-mentioned union operation, the quantity of subclass is original 1/2nd.
Carrying out above-mentioned distribution, to make used criterion be that equation 2 or 3 minimizes.That is to say; One sub-set can merge with each subclass that can merge; Above-mentioned possible merging mode all can produce the increment of a power dynamics measure; Increment to power dynamics measure is assessed, and selects to make the minimum subclass of power dynamics measure increment to merge.Thereby, carry out above-mentioned merging make launch ofdm signal power dynamics minimize.
Then, repeat above-mentioned union operation, the number of subsets after merging is all assessed the increment of power dynamics in each union operation with till used antenna number is corresponding.
Therefore, use the alternate analysis algorithm in the present embodiment, the OFDM symbol is separated into independent OFDM symbol, say that from the angle of available power dynamic change above-mentioned separation is best.
Use above-mentioned two kinds of iterative algorithms that separate the OFDM symbol, make the ofdm signal of emission have good power dynamics properties and lower complexity.
In addition, according to the embodiment of the invention, the set that is used to launch the subcarrier of said signal can comprise the subband that is provided with in advance.For example, these subbands can comprise a plurality of adjacent subcarriers.But as known in those skilled in the art, these subbands also can be made up of other modes.According to present embodiment, at first that each subband is related with a sub-set when OFDM symbol is separated into independent OFDM, then that subclass is related with independent OFDM symbol, and further make each subclass related with the different antennae in the antenna.
Because select the fixing subband that is provided with in advance only, the above embodiment of the present invention has restricted when selecting the separate mode of ofdm signal.Compare with can freely selecting the embodiment of the invention of subcarrier, the performance of the foregoing description slightly reduces.But the advantage of present embodiment is: it is the solution of a low complex degree, can simplify separation process in the transmitter.Because the subband that is provided with in advance is widely used in ofdm system, so present embodiment also can be used for most ofdm systems.
Fig. 4 illustrates the simulation result of the complementary cumulative distribution (complementarycumulative distribution) in the present invention and the existing solution, and wherein complementary cumulative distribution is a transmitting power and the function of the ratio of average power.In other words, the x axle is represented the ratio of used transmitting power and average power, and the y axle is represented the probability that a certain particular value will be exceeded on the x axle.Complementary cumulative distribution pair amplifier design is very important.
Solid line among Fig. 4 is represented the simulation result of two transmitters, and first transmitter has only an antenna, and second transmitter has two antennas.Wherein having two Signal Separation that antennamitter carried out, is not best from the angle of power dynamics, and the transmitter that typically has two antennas is shown in list of references [3] and [4].As shown in the figure, use the method for an antenna and the method as broad as long on performance (their curve overlaps) of two antennas of the middle use of list of references [3] in the prior art.This is because the Signal Separation of carrying out in the list of references [3] is best from the angle divided by collection; But not best from the angle of power dynamics; Thereby; From the angle of power dynamics, the Signal Separation mode that adopts in the list of references [3] does not provide gain in the dependent probability district.
Dotted line among Fig. 4 is represented the simulation result of three transmitters among the present invention.In emulation, three transmitters of this among the present invention have two antennas.To two different value α=0 (0 mould side (norm)) of α in the equation 2 and α=2 (2 mould side), simultaneously equation 3 (maximum norm side) is carried out emulation.Visible by figure, in low value on the x axle (before about 5dB) part, the dotted line of the expression embodiment of the invention overlaps with the solid line of expression prior art solution.Relevant value is promptly normally used and design to high value part on the x axle with power amplifier, dotted line separates with solid line, and this just means that the power dynamics gain of the embodiment of the invention is higher than the power dynamic gain of prior art solution.
Especially, be worth 10 on the Y axle
-3Corresponding to following situation: the probability that numerical value will be exceeded on the x axle is 0.1%, and this moment, the embodiment of the invention had the gain that is higher than the about 1.5dB of prior art solution.Be worth 10 on the Y axle
-4Corresponding to following situation: the probability that numerical value will be exceeded on the x axle is 0.01%, and this moment, the embodiment of the invention had the gain that is higher than the about 2.5dB of prior art solution.More than adopting two numerical value commonly used in the practice is that example is illustrated.Therefore, can find out significantly from Fig. 4 that from the angle of power dynamics, the power dynamics of separating based on the present invention is much better than the prior art solution.
Transmitter of the present invention is used for carrying out any step of the inventive method.Obvious, in above-mentioned step, relate to a kind of transmitter.
Reduce signal dynamics according to the present invention and change, can make amendment with reference to above-mentioned example embodiment by those skilled in the art.
List of references
H.Chireix, " High Power Outphasing Modulation ", November nineteen thirty-five, radio frequency engineering Shi Xiehui journal (Proceedings ofthe Institute ofRadio Engineers), o.11, the 23rd hurdle.
NEC Coorporation; " Mobile Radio Communication System withTransmitter Diversity "; European patent specification (European Patent Specification) EP741465, the applying date (Filing Date): 26/4/1996.
Samsung Electronics; " Apparatus and Method for sub-carrier allocation in aMIMO OFDM communication system "; European patent specification (European PatentSpecification) EP 1531594 A1, the applying date (Filing Date): 11/11/2004.
AT&T; " Assignment of subcarriers to an antenna array in a multicarriertransmitter "; European patent specification (European Patent Specification) EP 0831627 A2, the applying date (Filing Date): 16/9/1997.
Claims (16)
1. a method that in having the OFDM of two antennas (OFDM) transmitter, reduces the transmit signal power dynamic change at least is characterized in that, comprising:
The OFDM symbol of armed signal is separated at least two independent OFDM symbols; Thereby controlling said separation makes the power dynamics measure of confirming for each symbol in said at least two independent OFDM symbols keep low level; Wherein said power dynamics measure is relevant with the sample of said signal; Said signal is the signal that power surpasses threshold power, and said threshold value is more than or equal to the average power of said signal; Wherein said separation comprises: the set of subcarriers that will be used to launch said signal separates into the subclass of at least two subcarriers; Give a symbol in said at least two independent OFDM symbols with each subset allocation of said at least two subset;
Each symbol in said at least two the independent OFDM symbols of antenna emission from said at least two antennas.
2. the method for claim 1 is characterized in that, the subclass that the set of subcarriers that will be used to launch said signal separates at least two subcarriers comprises:
Generate the subclass of a plurality of subcarriers, the quantity of said subclass is corresponding to the quantity of used antenna,
Possibly separate according to the P that said set of subcarriers is separated into subsets of subcarriers; Said P the power dynamics measure that possibly separate assessed; And the corresponding separation of the minimum of selecting said dynamics measure, the wherein said quantity P that possibly separate is less than or equal to all possible separation quantity.
3. the method for claim 1 is characterized in that, the subclass that said set of subcarriers is separated at least two subcarriers is that iteration is carried out.
4. method as claimed in claim 3 is characterized in that, the separation that said iteration is carried out comprises:
Generate the subclass of several subcarriers, the quantity of said subclass is corresponding to the quantity of used antenna;
Give the sub-set in the said subclass that has generated with the allocation of carriers first time in the said set of subcarriers;
On the basis of considering said power dynamics measure,, distribute to each subclass in the said subclass that has generated successively with each subcarrier in the unallocated subcarrier in the said set of subcarriers.
5. method as claimed in claim 4 is characterized in that, the said unallocated subcarrier of said distribution comprises:
To each said unappropriated subcarrier, assess the increment of the said power dynamics measure that possible distribution causes, said possible distribution comprises gives each subclass in said a plurality of subclass that generated with said unappropriated sub-carrier allocation;
Selection makes the minimum subclass that has generated of increment of said power dynamics measure, said unallocated sub-carrier allocation is given the subclass that has generated of said selection.
6. method as claimed in claim 3 is characterized in that, said alternate analysis comprises:
Generate the subclass of several subcarriers, the number of subsets that is generated is corresponding to the number of sub-carriers in the said set of subcarriers;
Give the different subclass in the said generating subset with each sub-carrier allocation in the said set of subcarriers;
Considering successively another subclass in each subclass in the said generating subset and the said generating subset to be merged into the merging subclass on the basis of said power dynamics measure, up to the quantity of said merging subclass quantity corresponding to used antenna.
7. method as claimed in claim 6 is characterized in that, the said generating subset of said merging comprises:
To each said generating subset to be combined, said generating subset and another increment that possibly merge the said power dynamics measure that causes of generating subset are assessed;
Selection merges the minimum generating subset of said power dynamics measure increment.
8. the method for claim 1; It is characterized in that; Said set of subcarriers comprises at least one predefined subband; With said subclass is the unit, gives the sub-set in the said subclass with said at least one predefine allocation of subbands, makes at least one subclass of said at least two subset comprise at least one subband.
9. method as claimed in claim 8 is characterized in that, said allocated subbands comprises to subclass: to each relevant distribution, assess said power dynamics measure, and select to make the distribution of said power dynamics measure minimum.
10. the method for claim 1; It is characterized in that; The calculating of said power dynamics measure comprises: the item to relevant with the sample of each symbol in said at least two independent OFDM symbols is sued for peace, and said summation comprises that power surpasses the item relevant with the sample of each symbol in said at least two independent OFDM symbols of said threshold power.
11. method as claimed in claim 10 is characterized in that, the calculating of said power dynamics measure is undertaken by following formula:
Ω
i＝{k∈{0,1,…N-1}where|s
i(k)|
2>T}，
s
i(k) be i the sample of OFDM symbol separately,
N is a sample number in the OFDM symbol,
T is said threshold power,
α is the scalar design parameter.
12. the method for claim 1; It is characterized in that; The calculating of said power dynamics measure comprises: search maximum power value in each symbol from said at least two independent OFDM symbols, consideration of power surpasses the performance number of said at least two independent OFDM symbols of said threshold power.
13. method as claimed in claim 12 is characterized in that the calculating of said power dynamics measure is undertaken by following formula:
Ω
i＝{k∈{0,1,…N-1}where|s
i(k)|
2>T}，
s
i(k) be i the sample of OFDM symbol separately,
N is a sample number in the OFDM symbol,
T is said threshold power.
14. a device that in having the OFDM of two antennas (OFDM) transmitter, reduces the transmit signal power dynamic change at least is characterized in that, comprising:
The OFDM symbol of armed signal is separated into the module of at least two independent OFDM symbols; Thereby said separation is controlled and makes the power dynamics measure of confirming for each symbol in said at least two independent OFDM symbols keep low level; Wherein said power dynamics measure is relevant with the sample of said signal; Said signal is the signal that power surpasses threshold power, and said threshold value is more than or equal to the average power of said signal; Wherein said separation comprises: the set of subcarriers that will be used to launch said signal separates into the subclass of at least two subcarriers; Give a symbol in said at least two independent OFDM symbols with each subset allocation of said at least two subset;
The module of each symbol in said at least two the independent OFDM symbols of antenna emission from said at least two antennas.
15. device as claimed in claim 14 is characterized in that, said transmitter has two antennas.
16. device as claimed in claim 14 is characterized in that, said transmitter has more than two antennas.
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| PCT/CN2007/070042 WO2008141510A1 (en) | 2007-05-22 | 2007-05-22 | Multiple antenna transmission with small dynamical power range in ofdm systems |
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| FI20011238A0 (en) * | 2001-06-12 | 2001-06-12 | Nokia Corp | Method for limiting the signal and transmitter |
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| CN100499626C (en) * | 2005-08-23 | 2009-06-10 | 西安电子科技大学 | Block clipping method for resolving nonlinear distortion question in OFDM system |
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