CN101061654A - Communication device, communication system and communication method - Google Patents
Communication device, communication system and communication method Download PDFInfo
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Abstract
To provide a laminated structure distributed constant RC element that can be configured compactly, and can exclude noise at a specific frequency appropriately, and to provide a filter and electronic equipment. The plurality of distributed constant RC elements 14A, 14B comprise a plurality of resistors 12A, 12B, terminal electrodes 18a-18d formed at the resistors 12A, 12B, and a distributed capacitance electrode 15 for forming distributed capacity. The resistors 12A, 12B of the plurality of distributed constant RC elements 14A, 14B are laminated and arranged in the thickness direction and are connected in series, and the terminal electrodes 18a, 18c are arranged opposingly between mutually different distributed constant RC elements 14A, 14B, thus forming capacity C0 between the terminal electrodes.
Description
Technical field
The present invention relates to a kind of communicator, communication system and communication means, relate in particular to the technology for self-adaptively transmitting in sub-carrier communication system, just a kind of at sub-carrier communication system, particularly carry out communicator, communication system and the communication means of adaptive modulation and coding in radio communication OFDM (OFDM) system.
Background technology
The OFDM technology is the mainstream technology that solves the high speed wireless data transmission at present.To be the high-speed data that will transmit transmit with the subcarrier of many quadratures the principle of OFDM technology, and the data rate on each subcarrier is relatively low.Compare with common Frequency Division Multiplexing system, there is the higher availability of frequency spectrum in the orthogonality of the OFDM sub-carriers system that makes.Among the OFDM whole signal bandwidth is divided into a plurality of very narrow sub-carrier band, owing to the bandwidth of each subcarrier bandwidth less than channel, thus the flat fading of making.Like this, compare with single-carrier system, it is many that the flat fading among the OFDM will realize easily.At present, the OFDM technology has been successfully applied among asymmetric user data loop (ADSL), digital video broadcasting (DVB) and wireless asynchronous transfer mode (WATM) system.
In order to improve the availability of frequency spectrum of wireless system, the high speed wireless data transmission requirement of fading channel adopts the transmission technology of self adaptation, high spectrum utilization.In fading channel, with regular coding chopping phase ratio, adaptive modulation and coding (AMC) technology can improve handling up of system and the error rate (BER) performance effectively.Here so-calledly handle up that what refer to is exactly the availability of frequency spectrum of system, just unit spectral bandwidth information transmitted amount in the unit interval.The basic ideas of AMC technology are according in current characteristic of channel adaptively modifying transmitted power, symbol transmission speed, constellation size, code efficiency and the encoding mechanism one or more, some information that pass when channel condition is good more, improve the availability of frequency spectrum, when bad channel conditions, pass some information less and guarantee certain reception BER requirement.
Before the AMC method in introducing OFDM, at first simply introduce the characteristic of channel in the OFDM transmission.
Figure 1 shows that the characteristic of channel example of OFDM.
Wherein, two transverse axis are represented on the time domain label of subcarrier on the OFDM symbol and frequency domain respectively, and the longitudinal axis is the channel gain on corresponding OFDM symbol and the subcarrier.Because time domain chromatic dispersion and the frequency domain chromatic dispersion of channel in transmission makes the channel of OFDM that fluctuation all be arranged on time domain and frequency domain.
The front is mentioned, and the thought of AMC is modulation and the coding parameter that sends according to current changes in channel characteristics.For OFDM, the self adaptation of this moment is the self adaptation on time domain and two territories of frequency domain.At present on adaptive structure, the AMC among the OFDM can be divided into based on the AMC of subcarrier with based on two kinds of the AMC of subband.So-called AMC based on subcarrier refers to each subcarrier and is minimum self adaptation unit, and each subcarrier of OFDM adopts different modulation and coded systems to transmit.Shortcoming based on the AMC of subcarrier is that implementation complexity is too high, also has the excessive problem of feedback overhead in addition.In general, the method based on subcarrier AMC is difficult to realize in real system.Among the OFDM another adaptive structure be at present relatively more commonly used be the subband AMC structure that adopts absolute coding, also be traditional sub-band adaptive method.
Figure 2 shows that traditional sub-band adaptive modulation and coding schematic diagram.
In this structure, all subcarriers on the OFDM frequency domain are divided into some subbands.So-called subband refers to the sub carrier group of being made up of the subcarrier of adjacent position on the frequency domain.Such as in Fig. 2, sub-band sum is N.Then, form a coded modulation piece by the same subband in adjacent some (among Fig. 2, this numerical value is M) OFDM symbol.In traditional sub-band adaptive of Fig. 2, each coded modulation piece carries out the estimation of coded modulation parameter according to the characteristic of channel separately and independently encodes.Grade in this coded modulation piece of numeral among Fig. 2 in each coded modulation piece under the coded modulation parameter.
In general, the pairing coded modulation parameter of each coded modulation parameter grade is just reserved when initial in system.Show relation between grade, coding parameter and the modulation parameter such as table 1 as one of them example.But the present invention is not limited to table 1.
| Grade | Coding | Modulation parameter | |
| 0 | Do not pass | Do not pass | |
| 1 | 1/2Turbo | BPSK | |
| 2 | 1/2Turbo | QPSK | |
| 3 | 3/4Turbo | QPSK | |
| 4 | 2/3Turbo | |
|
| 5 | 3/4Turbo | |
|
| 6 | 2/3Turbo | 64QAM |
Next, provided the realization block diagram that adopts traditional sub-band adaptive method among the OFDM among Fig. 3.
Fig. 3 A and Fig. 3 B are depicted as the block diagram of the OFDM-AMC system that traditional OFDM combines with AMC.
When supposing to communicate between the communicator (receiving terminal) of the communicator (transmitting terminal) of Fig. 3 A and Fig. 3 B, typical example is base station end (AP) for Fig. 3 A, and Fig. 3 B is portable terminal (UE).Suppose transmission employing AMC mechanism simultaneously from Fig. 3 A to Fig. 3 B.
Transmitting terminal at Fig. 3 A; want the information transmitted bit at first to pass through adaptive modulation and coding unit 301; the serial modulation symbol of output is more respectively by serial/parallel conversion (S/P) device 302; anti-fast fourier transform (IFFT) device 303 transforms to time domain with frequency domain symbol; insert protection at interval behind parallel/serial conversion (P/S) device 304 again, this finishes unit 305 at interval by inserting protection.Afterwards, send by antenna 306.After the receiving terminal of Fig. 3 B receives the transmission signal of transmitting terminal by reception antenna 316; at first remove the protection interval that transmitting terminal adds; this finishes unit 315 at interval by removing protection; pass through serial/parallel conversion (S/P) device 314 more respectively; fast Fourier transform (FFT) device 313 transforms to frequency domain with time-domain symbol; pass through parallel/serial conversion (P/S) device 312 then and carry out parallel/serial conversion process, after adaptive demodulation and decoding unit 311 outputs obtain receiving data.
Adaptive Transmission from the transmitting terminal of Fig. 3 A to the receiving terminal of Fig. 3 B is mainly reflected in the adaptive modulation and coding unit 301 the transmitting terminal, and adaptive demodulation in the receiving terminal and decoding unit 311.The front is mentioned, and the implication of adaptive modulation and coding is the parameter of regulating modulation and coding adaptively at transmitting terminal according to the current characteristic of channel, and separates mediation decoding in receiving terminal employing and transmitting terminal corresponding parameter.In General System, adaptive modulation and coding unit 311 required auto-adaptive parameters come from the feedback of receiving terminal.Before each data block sends, receiving terminal all at first by channel estimating unit 319 estimate current from transmitting terminal to the receiving terminal channel transmitted, obtain the characteristic of channel on each subcarrier among the OFDM.Then, receiving terminal is determined modulation and the coding parameter that current transmitting terminal is adopted on each subband when sending data according to these characteristics of channel by subband AMC selection of parameter unit 318 in OFDM.Adaptive modulation and coding parameter on each subband of subband AMC selection of parameter unit 318 gained has two purposes:
The modulation when (1) sending data on each subband of OFDM and the purposes of coding parameter as current transmitting terminal.The subband AMC selection of parameter unit 318 of receiving terminal is after choosing the modulation and coding parameter that obtains on each subband of OFDM, parameter transmitting element 320 → receiving terminal antenna 316 → transmitting terminal antenna 306 → initiator parameters by receiving terminal receives and extraction unit 307 such feedback paths, and these parameters are sent it back transmitting terminal.Transmitting terminal is controlled by 308 pairs of adaptive modulation and coding unit 301 of AMC control unit after extraction obtains these parameters.
The purposes of the parameter that is adopted when (2) separating mediation decoding as receiving terminal.In AMC transmission, receiving terminal must according to corresponding to modulation of transmitting terminal and coding parameter, separate and be in harmonious proportion decoding and just can obtain correct information bit receiving data.Therefore, subband AMC selection of parameter unit 318 also needs to give adaptive demodulation and decoding unit 317 with it after obtaining the AMC parameter, and is temporary by adaptive demodulation and decoding unit 317, as the control of receiving terminal to adaptive demodulation and decoding unit 311.
In order to describe the method that adopts subband AMC among traditional OFDM more clearly, among Fig. 4 A and Fig. 4 B module 321 of the module among Fig. 3 A 309 and Fig. 3 B has been carried out refinement.
Fig. 4 A and Fig. 4 B are depicted as the traditional sub-band adaptive modulation and the implementation structure of coding.
Transmitting terminal at Fig. 3 A, adaptive modulation and coding unit 301 comprises adaptive coding unit 401, interleave unit 402 and Adaptive Modulation unit 403, the data of adaptive modulation and coding unit 301 outputs also are sent to IFFT device 303 behind (S/P) converter 302 through string.The AMC control unit 308 of transmitting terminal is controlled adaptive modulation and coding unit 301 according to parameter among Fig. 3 A receives each subband that obtains with extraction unit 307 from feedback channel modulation and coding parameter.In traditional sub-band adaptive, each subband among the OFDM is carried out independently coded modulation, that is to say that each subband all has the modulation and the coding parameter of a cover oneself.AMC control unit 308 is controlled adaptive modulation and coding unit 301 by the coding parameter C and the modulation parameter M of each subband of obtaining.Simultaneously, AMC control unit 308 can also obtain information transmitted bit number in each subband according to coding parameter C and modulation parameter M, thereby produces corresponding interleaver matrix ∏, and the interleave unit in the adaptive modulation and coding unit 301 402 is controlled.Transmitting terminal obtains the data flow 404 of serial after AMC, it has comprised subband 1,2 in order ... the data that send in the N, its modulation and coded system are respectively (C
1, M
1), (C
2, M
2) ..., (C
N, M
N).Afterwards, send in the respective sub-bands being mapped among the OFDM successively behind these data serial to parallel conversion.
Transmitting terminal sends the feedback that the required AMC parameter of each data block all comes from receiving terminal, also just says, and before transmitting terminal sends each data block, must be that the data block that transmitting terminal sent is chosen the AMC parameter at first all by receiving terminal.The process that receiving terminal is chosen parameter is such: at first carry out channel estimating by the signal that receives, channel estimating can have several different methods, comprises method based on pilot tone, blind Channel Estimation or the like.Afterwards, channel estimating unit 319 is given subband AMC selection of parameter unit 318 with the characteristic of channel on each subcarrier of OFDM that obtains.At first in view of the above the performance of each subband among the OFDM is analyzed in the subband AMC selection of parameter unit 318, in alternative AMC parameter sets, chosen proper A MC parameter again for each subband.The AMC parameter that obtains thus sends it back transmitting terminal by feedback channel on the one hand, is used for the adaptive modulation and coding operation of transmitting terminal reality when sending, and is used for the adaptive demodulation and the encoded control unit 409 of this receiving terminal on the other hand.For the consideration on the time delay, also need a parameter storage unit 410 simultaneously, be used to store current these parameters that obtain.The Adaptive Modulation of receiving terminal and decoding unit 311 have comprised adaptive demodulation unit 408, deinterleaving unit 407 and adaptive decoding unit 406.
Compare with the subcarrier self adaptation, this existing adaptive approach based on the subband absolute coding shown in Fig. 3 A to Fig. 4 B can reduce adaptive implementation complexity effectively, can also effectively reduce the feedback overhead of system simultaneously.Yet this method still has certain shortcoming: do not effectively utilize the diversity ability between each subband.
Diversity is a kind of important method of improving wireless transmission quality.So-called diversity, put it briefly, be exactly that transmitting terminal utilizes a certain resource to increase information redundance and makes independently distortion or the decay as far as possible of redundant mutually information experience as far as possible, thereby and merge the technology that its information obtains certain system performance gain in the receiving terminal comprehensive utilization.In brief, be exactly to utilize a plurality of passages to transmit simultaneously, can compensate by other passages in the loss of a channel performance of receiving terminal.
Patent application of the present invention is adopted in traditional OFDM adaptive modulation and coding on the basis of absolute coding method of subband, has increased subband is combined into subband group by certain method, each subband group is carried out the method for combined coding again.This method seems with traditional AMC thought and runs in the opposite direction, because traditional AMC method requires independently to choose parameter and encode for each subband.But, introduced the diversity of intersubband in this method, thereby can obtain bigger coding gain.In addition, the method that provides according to us is carried out choosing of subband group internal modulation coding parameter again, compares the loss that can't bring throughput of transmissions with conventional method.Both in conjunction with, adopt the method for this patent application will help to improve the performance of Adaptive Transmission among the OFDM.
Summary of the invention
The problem that invention will solve
The objective of the invention is to, a kind of communicator, communication system and communication means are provided, wherein, at first all subbands on the sub-carrier communication system frequency domain are become some subband group according to certain principle combinations, and then choose modulation and the coding parameter that adopts when each subband group carried out combined coding, compare with traditional sub-band adaptive method thus, can improve the system spectrum utilance, especially the availability of frequency spectrum under rapid fading and the channel estimation errors can reduce the self adaptation implementation complexity and reduce feedback overhead simultaneously.
The scheme of dealing with problems
The structure of communicator of the present invention comprises: channel estimating unit, each subband is carried out channel estimating; The parameter determining unit based on the result of described channel estimating, is determined modulation parameter and coding parameter to each subband group that is formed by a plurality of subbands; The parameter information transmitting element sends to communication object with parameter information, and described parameter information is the described modulation parameter determined by described parameter determining unit and the information of described coding parameter; Receiving element, reception comprises the received signal of data, described data are for by described modulation parameter and the described coding parameter of communication object by the parameter information that uses described parameter information transmitting element and sent, come each described subband group is modulated and encoded and the data that obtain; And data obtain the unit, the received signal that described receiving element is received, described modulation parameter and described coding parameter that use is determined by described parameter determining unit are separated mediation decoding to each described subband group, and obtain to be contained in the described data of described received signal.
Communication system of the present invention be comprise with modulate and encode after the base station apparatus that sends of data and the communication system that receives the communication terminal of described data, described communication terminal comprises: channel estimating unit, each subband is carried out channel estimating; The parameter determining unit based on the result of described channel estimating, is determined modulation parameter and coding parameter to each subband group that is formed by a plurality of subbands; The parameter information transmitting element sends to described base station apparatus with parameter information, and described parameter information is the described modulation parameter determined by described parameter determining unit and the information of described coding parameter; Receiving element receives the received signal comprise data, and described data are for by the parameter of described base station apparatus by the parameter information that uses described parameter information transmitting element and sent, comes each described subband group is modulated and encoded and the data that obtain; And data extracting unit, the received signal that described receiving element is received, use the described modulation parameter and the described coding parameter of described parameter information, each described subband group is separated mediation decoding, and extraction is contained in the described data of described received signal, described base station apparatus comprises: the adaptive modulation and coding unit, and modulate and encode according to the described modulation parameter of the described parameter information that sends by described transmitting element and coding parameter; And data transmission unit, will by described adaptive modulation and coding unit modulate and encode after data send.
Communication means of the present invention may further comprise the steps: each subband is carried out channel estimating; Based on the result of described channel estimating, each subband group that is formed by a plurality of subbands is determined modulation parameter and coding parameter; Communication terminal sends parameter information, and described parameter information is the information of determined described modulation parameter and described coding parameter; Base station apparatus receives the described parameter information that described communication terminal sends; According to the described modulation parameter and the described coding parameter of the described parameter information that is received, data are modulated and encoded; Described base station apparatus send modulate and encode after data; Communication terminal receives the received signal that comprises described data that is sent by described base station apparatus; And the described received signal to being received, use the described modulation parameter and the described coding parameter of described parameter information, each described subband group is separated be in harmonious proportion decoding, and extract the described data that are contained in described received signal.
Description of drawings
Figure 1 shows that the characteristic of channel example of OFDM;
Figure 2 shows that the adaptive modulation and coding schematic diagram of prior art;
Fig. 3 A is depicted as the block diagram of sending end structure of the OFDM-AMC system of prior art;
Fig. 3 B is depicted as the block diagram of receiving terminal structure of the OFDM-AMC system of prior art;
Fig. 4 A is depicted as the schematic diagram of the module that comprises the adaptive modulation and coding unit of the transmitting terminal of prior art;
Fig. 4 B is depicted as the schematic diagram of the module that comprises adaptive demodulation and decoding unit of the receiving terminal of prior art;
Fig. 5 A is depicted as the schematic diagram according to the sending end structure of the OFDM-AMC system of the embodiment of the invention;
Fig. 5 B is depicted as the schematic diagram according to the receiving terminal structure of the OFDM-AMC system of the embodiment of the invention;
Fig. 6 A is depicted as the schematic diagram according to the module that comprises the adaptive modulation and coding unit of the transmitting terminal of the embodiment of the invention;
Fig. 6 B is depicted as the schematic diagram according to the module that comprises adaptive demodulation and decoding unit of the receiving terminal of the embodiment of the invention;
Fig. 7 shows the figure according to the adaptive modulation and coding method of the embodiment of the invention;
Fig. 8 is the schematic diagram of the example of subband group according to an embodiment of the invention;
Fig. 9 is the schematic diagram of the example of subband group according to an embodiment of the invention;
Figure 10 is the schematic diagram of the example of subband group according to an embodiment of the invention;
Figure 11 shows the schematic diagram according to the performance comparison result of the adaptive modulation and coding of the embodiment of the invention and traditional adaptive modulation and coding;
Figure 12 shows the schematic diagram according to the performance comparison result of the adaptive modulation and coding of the embodiment of the invention and traditional adaptive modulation and coding.
Embodiment
Below in conjunction with accompanying drawing the specific embodiment of the present invention is described.In order clearly to describe the present invention, the present invention has adopted ofdm system to be described as example.The method of adaptive modulation and coding of the present invention is suitable for other any sub-carrier communication systems that utilizes subcarrier to communicate equally.
The present invention adopts in traditional OFDM adaptive modulation and coding on the basis of the absolute coding method of subband, by subband is combined into subband group by certain way, each subband group is carried out the technology of combined coding again.And this invention gives the variety of way with the synthetic subband group of subband group, and the modulation of adopting during combined coding in the subband group and the mode of choosing of coding parameter.After a while with described.
Fig. 5 A and Fig. 5 B are depicted as the OFDM-AMC system configuration that is used to realize the inventive method.
In order to make description of the invention more clear, give identical label and omit its detailed description to the structure well known in the prior art shown in the 4B for Fig. 1, and only described difference with the prior art structure of the present invention.
Compare with the traditional OFDM-AMC structure shown in Fig. 3 B with Fig. 3 A, use following some difference that has of OFDM-AMC of the present invention system:
(1) comprised in the module 505 among Fig. 5 B, be that the AMC parameter of subband group is chosen as the subband group AMC selection of parameter unit 504 of selection of parameter unit, and the subband AMC selection of parameter unit 318 that is comprised in the module 321 among Fig. 3 B is AMC parameters of choosing each subband.This is because to carry out the unit of sub-band adaptive modulation and coding in traditional OFDM-AMC system be subband, and in OFDM-AMC of the present invention system, the unit that carries out adaptive modulation and coding is a subband group.In the present invention, all subbands on the OFDM frequency domain are combined into some subband group by combination pattern, again each subband group are carried out adaptive modulation and coding.And in OFDM-AMC of the present invention system, in Fig. 5 B parameter transmitting element 320 → receiving terminal antenna 316 → transmitting terminal antenna 306 → initiator parameters receive with extraction unit 307 such based on feedback link in what transmit is the AMC parameter about subband group as parameter information, rather than as the AMC parameter about subband among the OFDM-AMC of Fig. 3, described parameter information is the information about modulation parameter and coding parameter.
(2) self adaptation sending controling unit 501 has been replaced AMC control unit 308 among Fig. 3 A in the transmitting terminal.In the technology of the present invention, transmitting terminal carries out adaptive modulation and coding to subband group among the OFDM, and subband group is combined according to combination pattern by each subband among the OFDM.Therefore, self adaptation sending controling unit 501 need be controlled the AMC of subband group in the adaptive modulation and coding unit 301 on the one hand, on the other hand, also require serial/parallel conversion (S/P) device 302 after the adaptive modulation and coding is controlled, it is next in the corresponding subband to make that the interior information bit that sends of each subband group can be mapped to after coding and modulation among the OFDM, to transmit.
(3) the adaptive reception control unit 503 in the receiving terminal has been replaced adaptive demodulation and the control unit 317 among Fig. 3 B.Adaptive reception control unit 503 need be controlled the adaptive de mediation decoding unit 311 that obtains the unit as data on the one hand, on the other hand, also adaptive demodulation and parallel serial conversion (P/S) device 312 before the decoding are controlled, the receiving symbol in the same subband group is merged together to separate to be in harmonious proportion deciphers.
Module 502 and the module 505 among Fig. 5 B of Fig. 5 A can be refined as Fig. 6 A and Fig. 6 B.
Fig. 6 A and Fig. 6 B are depicted as the schematic diagram that the present invention proposes the implementation structure of method.
At transmitting terminal, be with the difference of traditional sub-band adaptive among Fig. 4 A: the unit of adaptive modulation and coding is subband group but not subband, the output 603 of adaptive modulation and coding unit 301 has at this moment comprised subband group 1 in order, 2, the data that send in the K, its modulation and coded system are respectively (C
1, M
1), (C
2, M
2) ..., (C
K, M
K), wherein K is the subband group sum of dividing in the OFDM.In addition, transmitting terminal is except operation is controlled to AMC, also need according to the combination pattern that is stored in the subband in the combination pattern memory cell 601, serial/parallel conversion in serial/parallel conversion (S/P) device 302 is controlled, transmitted in the corresponding subband thereby the information bit that sends in each subband group can be mapped among the OFDM after coding and modulation.
At receiving terminal, be with the difference of traditional sub-band adaptive among Fig. 4 B: the unit of adaptive demodulation and decoding is subband group but not subband.In addition, receiving terminal is except controlling adaptive de mediation decoded operation, also need according to the combination pattern that is stored in the subband in the combination pattern memory cell 605, parallel/serial conversion in parallel/serial conversion (P/S) device 312 is controlled, thereby the receiving symbol in the same subband group of OFDM is merged together to separate is in harmonious proportion decoding.In addition, it is also different with Fig. 4 B to be shown in subband group AMC selection of parameter unit 504 as Fig. 6 B.Choose on the parameter basis that obtains each subband of OFDM in selection of parameter unit 411 among Fig. 6 B, also will choose the auto-adaptive parameter of each subband group of OFDM by the selection of parameter unit 606 of subband group again according to the combination pattern that is stored in the combination pattern memory cell 607.
Fig. 7 shows and is used to realize according to the adaptive coding of the embodiment of the invention and the process chart of modulator approach.Particularly, the implementation procedure of the technology of the present invention is as follows:
The first step is brought in the adaptive modulation and coding parameter in each subband group among definite transmitting terminal OFDM by reception, and it is fed back to transmitting terminal.This process comprises receiving terminal channel estimating (step 901), each sub-band adaptive selection of parameter (step 902) of OFDM, each subband group adaptive parameter selection (step 903) of OFDM, and parameter feedback (step 921).
(1) channel estimating of step 901 can adopt existing conventional method, such as the channel estimating based on pilot tone, blind Channel Estimation or the like.
(2) each sub-band adaptive selection of parameter of the OFDM of step 902 refers to consideration under the situation of each traditional subband absolute coding, the modulating-coding parameter that is adopted when each subband carries out Adaptive Transmission among the OFDM.Owing to be absolute coding, so the parameter in each subband is according to the difference of its characteristic of channel and difference.
In this step operation, at first need to determine alternative auto-adaptive parameter set, such as the parameter sets in table 1 and the table 2.Then, choose suitable modulation and coding parameter for it, determine corresponding transmission information bit number simultaneously according to the characteristic of channel in current each subband.Here, the existing method of choosing parameter according to the characteristic of channel has a variety of, as method based on the subband lowest signal-to-noise, and based on the method for sub-band averaging signal to noise ratio, based on the method for capacity, based on the method for average signal-to-noise ratio in conjunction with other statistical properties, or the like.In this exemplifying embodiment, we are that example is made brief description with the method based on average signal-to-noise ratio.
Method based on average signal-to-noise ratio is such: at first determine every kind of signal-noise ratio threshold value (as shown in table 2) that the modulating-coding parameter is required by theory analysis or method of emulation, handling capacity wherein also is the availability of frequency spectrum of various coded modulation parameter correspondences, equals the product that code efficiency and each symbol comprise bit number on its numerical value.Then, concerning each subband, calculate the average signal-to-noise ratio on its inner subcarrier.At last, choose threshold value for this subband and be lower than this average signal-to-noise ratio, and the highest modulation of handling capacity and coding parameter are as modulation in this subband and coding parameter.Table 2 shows the relation between coding parameter, modulation parameter, signal-noise ratio threshold and the handling capacity of each grade.Such as, average signal-to-noise ratio is 0,2,4,6 in the subband, under 8 the situation, presses the parameter shown in the table 2, the modulation of the choosing grade corresponding with coding parameter is respectively 1,1, and 2,3,4.Accordingly, the information bit that distributes in this subband also just decided (equal on its numerical value in this subband total number of sub-carriers and choice of modulation coding parameter the product of corresponding handling capacity).
| Grade | Coding parameter | Modulation parameter | Signal-noise ratio threshold (dB) | Handling capacity (bps/Hz) |
| 0 | Do not pass | Do not pass | -∞ | 0 |
| 1 | 1/2Turbo | BPSK | -0.4 | 0.5 |
| 2 | 1/2Turbo | QPSK | 2.2 | 1 |
| 3 | 3/4Turbo | QPSK | 5.2 | 1.5 |
| 4 | 2/3Turbo | 8PSK | 7.6 | 2 |
| 5 | 3/4Turbo | 16QAM | 10.9 | 3 |
| 6 | 2/3Turbo | 64QAM | 14.5 | 4 |
(3) each subband group adaptive parameter selection of the OFDM of step 903 is independently modulated each subband of OFDM in traditional adaptive approach and is encoded.And in the method for the present patent application, the unit of Adaptive Transmission is subband group but not subband.Therefore, at first according to certain combined method (perhaps combination pattern), with synthetic several subband groups of all subband group of OFDM frequency domain.The method of combination can be: the method for the method of adjacent sub-bands combination, subband combination at interval, the method for all subband combinations and the method that makes up by other rules.The method of adjacent sub-bands combination, the method that just is chosen at a plurality of subbands adjacent on the frequency axis is the method with the synthetic subband group of plurality of adjacent subband group on the position, referring to Fig. 8.Fig. 8 is the adjacent sub-bands combination examples.In addition, subband group has the combination pattern of subband, subband be in the subcarrier-modulated symbol of given number, the subcarrier of the equal number of adjacent position is formed on the frequency domain.
Among Fig. 8, with time domain same position among the OFDM, the subband of the N on the frequency domain is combined into several subband groups, wherein, the synthetic subband group of the subband group that frequency domain position is adjacent, promptly the subband under the identical hatching pattern belongs to a subband group together among the figure.
In addition, the method for subband combination just is arranged in the method for choosing a plurality of subbands in the subband on the frequency axis with predetermined interval at interval, for choosing the method that some subbands at interval are combined into a subband group, referring to Fig. 9.Fig. 9 is an interval subband combination examples.
Among Fig. 9, the subband of choosing on the OFDM frequency domain is at interval merged into same subband group, and promptly the subband under the identical hatching pattern belongs to a subband group together among the figure.
In addition, whole methods of subbands combination is just chosen the method for all subbands, for all subbands of frequency domain are merged into a subband group, referring to Figure 10 to each predetermined time domain.Figure 10 is whole subband combination examples.
Among Figure 10, with time domain same position among the OFDM, the whole N on the frequency domain sub-tape merges are a subband group.
In addition, in the method that makes up by other rules, after the information bit of the modulation of each subband and coding parameter, distribution was decided in subband group, the information bit and the combined coding parameter of distributing in the subband group can be definite like this: at first sue for peace the information bit that distributes in each subband as the information bit that distributes in the whole subband group (1); (2) choose the modulation system that modulation levels maximum in each subband adopts as unified modulation in this subband group then, and then determine code efficiency by information bit that distributes in the subband group and modulation system.
This process example is as follows: suppose that a subband group comprises A, and B, C, four subbands of D, the sub-carrier number that comprises in each subband is 512, each subband corresponding codes and modulation parameter grade are respectively: 0,1,2,3.Then can get: A, B, C, the information bit that distributes in each subband group of D is respectively: for A is 512*0=0, is 512*0.5=256 for B, is 512*1=512 for C, is 512*1.5=768 for D.Thus, total information bit is 0+256+512+768=1536 in this subband group.Afterwards, choose A, B, C, modulation levels (here, the modulation levels of subband D correspondence is the highest) 8PSK the highest in each subband group of D is as modulation parameter unified in the whole subband group.Accordingly, the code efficiency that Unified coding is adopted in this subband group is 1536/ (512*3*4)=1/4.
Here, will estimate the A of gained, B, C, separately transmission information bit number summation back is as information transmitted bit number in the subband group in four subbands of D.In the practical operation, can also do a ranking operation to this numerical value.Such as, consider channel variation than very fast, the estimated channel characteristic error can be bigger, then to A, B, C, one 0.9 weighting is done in transmission information bit number summation back in four subbands of D, that is: total information bit is (0+256+512+768) * 0.9=1536*0.9 ≈ 1382 in the subband group.
(4) parameter of step 921 feedback after receiving terminal obtains the auto-adaptive parameter of each subband group of OFDM, sends it back transmitting terminal with it by feedback channel, is used for transmitting terminal and carries out actual operation by this parameter.
In second step, the auto-adaptive parameter in each subband group of OFDM that transmitting terminal feeds back to according to receiving terminal is the information bit waiting for transmission that each subband group is distributed respective number, and by relevant parameter to carrying out combined coding and modulation (step 911) in each subband group.Such as by situation about supposing previously, to by A, B, C, the subband group that four subbands of D are formed adopts the modulation and the coding of associating, and its modulation and coding parameter are respectively 8PSK and 1/4Turbo sign indicating number.Next, the allocation of symbols after will modulating according to the subband combination pattern again sends (step 912) in the respective sub-bands in the OFDM.Specifically comprise the serial/parallel conversion of serial/parallel converter 302, the anti-fast fourier transform of IFFT device 303, the parallel/serial conversion of parallel/serial converter 304, and insert and protect the protection of unit 305 at interval to insert at interval.
The 3rd step; at receiving terminal; at first through removing the protection protection removal at interval of unit 315 at interval; the serial/parallel conversion of serial/parallel converter 314; the fast fourier transform of FFT device 313; the parallel/serial conversion of parallel/serial converter 312; to receive data extract in each subband group of OFDM come out (step 904) by controlling parallel/serial converter 312 according to the subband combination pattern simultaneously; then; again according to the auto-adaptive parameter in each subband group of gained in the first step; each subband group is carried out adaptive de mediation decoding, and the initial data (step 905) that is finally sent.
The present invention makes up and combined coding each subband among the OFDM, effectively utilized the diversity ability of intersubband, thereby improved the system spectrum utilance effectively, especially the availability of frequency spectrum under rapid fading and the channel estimation errors reduces self adaptation implementation complexity and feedback overhead simultaneously.
Figure 11 shows under different delay of feedback, the figure of the inventive method and conventional method performance comparison result.
Figure 12 shows under the different channels evaluated error, the schematic diagram of the inventive method and conventional method performance comparison result.
Wherein, the ofdm system signal bandwidth that emulation is adopted is 10MHz, and total number of sub-carriers is 1024, is divided into 16 subbands, and each subband is crossed over 8 OFDM symbols on time domain.Many tops of component recursive system convolution (RSC) formula of Turbo code is (13,11)
Oct, 4 iteration, maximum a posteriori probability (MAP) algorithm are adopted in decoding.System adopts ARQ.The channel model that adopts in the emulation is vehicle-mounted channel model A M.1225.In the specific implementation, adopt all methods of combination of subband, single subband adopts the method for parameter estimation based on average signal-to-noise ratio.F among Figure 11 and Figure 12
dτ and MSE represent the product of maximum doppler frequency and feedback delay respectively, and channel estimation errors.Traditional method is referring to Fig. 2.From the result of Figure 11 and Figure 12 as seen, no matter be (f in ideal conditions
dτ=0, no MSE), or (there is f in rapid fading
dτ) or under the situation of channel estimation errors (having MSE), compare with conventional method, the method that the present invention proposes all has certain performance gain.In addition, all merge into 1 subband group with 16 subbands this moment, and feedback overhead reduces to original 1/16.
Although below show the present invention in conjunction with the preferred embodiments of the present invention, those skilled in the art will appreciate that under the situation that does not break away from the spirit and scope of the present invention, can carry out various modifications, replacement and change to the present invention.Therefore, the present invention should not limited by the foregoing description.
Claims (12)
1, a kind of communicator comprises:
Channel estimating unit is carried out channel estimating to each subband;
The parameter determining unit based on the result of described channel estimating, is determined modulation parameter and coding parameter to each subband group that is formed by a plurality of subbands;
The parameter information transmitting element sends to communication object with parameter information, and described parameter information is the described modulation parameter determined by described parameter determining unit and the information of described coding parameter;
Receiving element, reception comprises the received signal of data, described data are for by described modulation parameter and the described coding parameter of communication object by the parameter information that uses described parameter information transmitting element and sent, come each described subband group is modulated and encoded and the data that obtain; And
Data obtain the unit, the received signal that described receiving element is received, described modulation parameter and described coding parameter that use is determined by described parameter determining unit are separated mediation decoding to each described subband group, and obtain to be contained in the described data of described received signal.
2, communicator according to claim 1 also comprises:
The pattern memory cell, storage in advance is used to choose the pattern of the subband that constitutes described subband group, wherein,
Described parameter determining unit is determined described modulation parameter and described coding parameter to each described subband group, and described subband group is formed by the subband of choosing based on the described pattern that is stored in described pattern memory cell.
3, communicator according to claim 2, wherein,
Described parameter determining unit is determined described modulation parameter and described coding parameter to each the described subband group that is made of described pattern, and described pattern is used to be chosen at a plurality of subbands adjacent on the frequency axis.
4, communicator according to claim 2, wherein,
Described parameter determining unit is determined described modulation parameter and described coding parameter to each the described subband group that is made of described pattern, and described pattern is used for choosing a plurality of subbands from the subband that is arranged on the frequency axis with predetermined interval.
5, communicator according to claim 2, wherein,
Described parameter determining unit is determined described modulation parameter and described coding parameter to each the described subband group that is made of described pattern, and described pattern is used for each predetermined time domain is chosen all subbands.
6, communicator according to claim 1, wherein,
Described parameter determining unit is obtained described modulation parameter to each subband in the described subband group, and will be defined as the described modulation parameter of described subband group in the highest described modulation parameter of being obtained of described modulation parameter middle grade.
7, communicator according to claim 1, wherein,
Described parameter determining unit is determined described coding parameter, is assigned to described subband group so that can distribute to the information bit of all subbands in the described subband group.
8, communicator according to claim 1, wherein,
Described parameter determining unit is determined described coding parameter, so that the result's that the summation of the information bit that can distribute to all subbands in the described subband group is weighted information bit is assigned to described subband group, described weighting is carried out each described subband group.
9, a kind of base station apparatus of the communication object as the described communicator of claim 1, this base station apparatus comprises:
The adaptive modulation and coding unit according to the described modulation parameter and the coding parameter of the described parameter information that is sent by described transmitting element, is modulated and is encoded data; And
Data transmission unit, will by described adaptive modulation and coding unit modulate and encode after data send.
10, a kind of communication system comprises: base station apparatus, and the data after will modulating and encode send; And communication terminal, receive described data,
Described communication terminal comprises:
Channel estimating unit is carried out channel estimating to each subband;
The parameter determining unit based on the result of described channel estimating, is determined modulation parameter and coding parameter to each subband group that is formed by a plurality of subbands;
The parameter information transmitting element sends to described base station apparatus with parameter information, and described parameter information is the described modulation parameter determined by described parameter determining unit and the information of described coding parameter;
Receiving element receives the received signal comprise data, and described data are for by the parameter of described base station apparatus by the parameter information that uses described parameter information transmitting element and sent, comes each described subband group is modulated and encoded and the data that obtain; And
Data extracting unit to the received signal that described receiving element receives, is used the described modulation parameter and the described coding parameter of described parameter information, and each described subband group is separated to be in harmonious proportion decipher, and extract the described data that are contained in described received signal,
Described base station apparatus comprises:
The adaptive modulation and coding unit is modulated and is encoded according to the described modulation parameter of the described parameter information that is sent by described transmitting element and coding parameter; And
Data transmission unit, will by described adaptive modulation and coding unit modulate and encode after data send.
11, a kind of communication means may further comprise the steps:
Each subband is carried out channel estimating;
Based on the result of described channel estimating, each subband group that is formed by a plurality of subbands is determined modulation parameter and coding parameter;
Communication terminal sends parameter information, and described parameter information is the information of determined described modulation parameter and described coding parameter;
Base station apparatus receives the described parameter information that described communication terminal sends;
According to the described modulation parameter and the described coding parameter of the described parameter information that is received, data are modulated and encoded;
Described base station apparatus send modulate and encode after data;
Communication terminal receives the received signal that comprises described data that is sent by described base station apparatus; And
To the described received signal that is received, use the described modulation parameter and the described coding parameter of described parameter information, each described subband group is separated to be in harmonious proportion decipher, and extract the described data that are contained in described received signal.
12, communication means according to claim 11 also comprises:
Storage in advance is used to choose the step of the pattern of the subband that constitutes described subband group, wherein,
Each described subband group is determined described modulation parameter and described coding parameter, and described subband group is formed by the subband of choosing based on the described pattern of being stored.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105191244A (en) * | 2014-04-16 | 2015-12-23 | 华为技术有限公司 | Bandwidth variable modulation method, apparatus and system |
| CN103297194B (en) * | 2007-03-07 | 2016-05-11 | 株式会社Ntt都科摩 | Orthogonal frequency-division multiplex singal receiver and method of reseptance |
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2005
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103297194B (en) * | 2007-03-07 | 2016-05-11 | 株式会社Ntt都科摩 | Orthogonal frequency-division multiplex singal receiver and method of reseptance |
| CN105191244A (en) * | 2014-04-16 | 2015-12-23 | 华为技术有限公司 | Bandwidth variable modulation method, apparatus and system |
| CN105191244B (en) * | 2014-04-16 | 2019-04-23 | 华为技术有限公司 | A kind of modulator approach of adaptive-bandwidth, device and system |
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