CN101783782A - Uplink multiple access technology capable of automatically adapting to channel characteristic variation - Google Patents
Uplink multiple access technology capable of automatically adapting to channel characteristic variation Download PDFInfo
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- CN101783782A CN101783782A CN201019087015A CN201019087015A CN101783782A CN 101783782 A CN101783782 A CN 101783782A CN 201019087015 A CN201019087015 A CN 201019087015A CN 201019087015 A CN201019087015 A CN 201019087015A CN 101783782 A CN101783782 A CN 101783782A
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Abstract
The invention belongs to an uplink multiple access technology capable of automatically adapting to channel characteristic variation in network access technologies. The invention comprises system initialization processing, which includes the following processes: a transmitting end: selecting a shaping filter matched with the characteristics of the current channel, quadrature amplitude modulating the send information, zero insertion processing, orthogonalization phase mapping, multi-carrier modulating, signal shaping and sending the signal; and a receiving end: processing the receiving signal, selecting the shaping filter matched with the characteristics of the channel, multi-carrier modulating, de-orthogonalization phase mapping, extracting valid data, isostatic compensating and storing the data. Because OQAM (technology) is introduced into OFDMA (technology) and the shaping filter with good time-frequency focusing characteristic is adopted to substitute for cyclic prefix, the invention has the characteristics of effectively improving the spectrum efficiency, system capacity and data transmission performance and resisting Doppler expansion, reducing the disturbance between users and distortion of the signal in the channel, better satisfying the requirement of high-speed mobile communications and the like.
Description
Technical field
The invention belongs to ofdm system (OFDM/OQAM based on staggered quadrature amplitude modulation, OrthogonalFrequency Division Multiplexing/Offset Quadrature Amplitude Modulation) multiple access inserts up technology, the uplink multiple access technology of the automatic adaptive channel characteristic variations of particularly a kind of energy is particularly useful for the uplink multi-address connecting system under spectral efficient requirement and the high velocity environment.
Background technology
OFDM access technology (OFDMA, Orthogonal Frequency Division MultipleAccess) is a kind of multiple access technique based on OFDM (OFDM, Orthogonal Frequency DivisionMultiplexing) system.Its core is to realize that by the method for giving each user's distribution portion available subcarrier the multi-user inserts.OFDMA does not need to adopt the protection frequency range to remove to distinguish different user, has improved spectrum efficiency; And, can be easy to overcome the intersymbol interference (ISI, Inter-Symbol Interference) that multipath channel causes by adding Cyclic Prefix (CP, Cyclic Prefix).In addition, OFDMA is except that independently using as multiple access technology, can also with existing multiple access technology, as time division multiple access (TDMA, Time Division MultipleAccess), frequency division multiple access (FDMA, Frequency Division Multiple Access) combination very flexibly such as has broad application prospects thereby make the OFDMA technology gather around.
Tradition is as follows based on the overall implementation procedure (flow process) of the orthogonal frequency division multiple access system (CP-OFDM, Cyclic Prefix-OrthogonalFrequency Division Multiple Access) of Cyclic Prefix:
Transmitting terminal (travelling carriage):
Step 1. signal source data bit through the coding, do quadrature amplitude modulation (QAM, Quadrature AmplitudeModulation), obtain complex data after, framing also adds pilot frequency sequence;
Step 2. is carried out the subcarrier mapping according to the resource allocation of system to this user, promptly in non-available subcarrier position, the Frame that step 1 obtains is done the zero insertion operation;
Step 3. is done anti-fast Fourier transform (IFFT, Inverse Fast FourierTransform) by the symbol after the step 2, finishes multi-carrier modulation;
When sending, step 4. will add sufficiently long CP, to overcome the ISI interference that multipath channel causes by the data after step 3 modulation;
Step 5. digital-to-analogue conversion, up-conversion transmit;
Receiving terminal (base station end),
Step 1. received signal, down-conversion, analog-to-digital conversion obtain base band complex symbol frame sequence;
Step 2. is removed the CP part in the OFDM symbol (present frame);
Step 3. is done fast Fourier transform (FFT, Fast Fourier Transform) by the symbol after the step 2, finishes the multicarrier demodulation;
Step 4. is carried out the subcarrier reflection and is penetrated according to the resource allocation of system to this user, promptly in by the symbol after the step 3, removes the data of non-available subcarrier position;
Step 5. is from by the symbol after the step 4, and amplitude-frequency and phase-frequency response by pilot frequency sequence extracts multipath channel utilize this channel information, is eliminated or is reduced the influence of multipath channel to ofdm signal by equalizer (as zero forcing equalization etc.);
Step 6. is carried out QAM demodulation and corresponding decoding by the symbol after the step 5, deposits data in.
The deficiency of CP-OFDMA system maximum is:
In the one .CP-OFDMA system, when step 4 sends, need add CP, disturb to eliminate multipath; Accordingly, in receiving step 2, then need to remove CP.Therefore exist: the one, CP can only be used as reducing of static channel ISI or eliminate, for then not effect of the influence of disturbing (ICI, Inter-Carrier Interference) between subcarrier; The 2nd, the adding of CP has strengthened the overhead of system, has reduced the availability of frequency spectrum;
In its two .CP-OFDMA system, after forwarding step 4, directly data are sent into reflector (promptly making the rectangular window molding filtration), this drawback has two: one,, rectangular window time-frequency focus characteristics is far away from expansion Gaussian function (EGF, Extended Gaussian Function) window type such as, thereby make the CP-OFDMA system comparatively responsive for ICI; The 2nd,, all adopt fixing formed filter for all users, all running time-frequency resource lattice points, do not handle flexibly, thereby overall performance is relatively poor at the different situations of channel.
2, based on the ofdm system of staggered quadrature amplitude modulation:
In the existing communication technology, OFDM (OFDM/OQAM based on staggered quadrature amplitude modulation, Orthogonal Frequency Division Multiplexing/Offset Quadrature AmplitudeModulation) technology is compared, conventional orthogonal frequency division multiplexing (CP-OFDM based on Cyclic Prefix, Cyclic Prefix-Orthogonal Frequency Division Multiplexing) technology, have higher spectrum efficiency, better time-frequency focus characteristics, and good effect is all arranged to a certain extent for the influence that overcomes ISI and ICI, the latter particularly becomes OFDM/OQAM with respect to one of main advantage of CP-OFDM.These characteristics make OFDM/OQAM become one of main candidate scheme of following mobile multimedia communication.The transmission signal of OFDM/OQAM system is real-valued, takes from the real part and the imaginary part of complex symbol to be passed, because with respect to traditional ofdm system, OFDM/OQAM only satisfies strict orthogonality condition in real number field; And for the selection of formed filter, optional usefulness has good time-frequency and focuses on (TFL, Time Frequency Localization) formed filter of characteristic, as isotropism orthogonal transform function formed filter (IOTA, Isotropic Orthogonal TransformAlgorithm), this is the major reason that OFDM/OQAM has above-mentioned advantage.The structure of tradition OFDM/OQAM system form and signal processing flow as shown in Figure 4, its flow process is as follows:
Transmitting terminal (travelling carriage)
Step 1. signal source data bit through coding, carry out quadrature amplitude modulation (QAM, Quadrature AmplitudeModulation), obtain complex data after, framing, and add pilot frequency sequence;
Step 2. by step 1 to data carry out the orthogonalization phase mapping;
Step 3. is carried out anti-fast Fourier transform (IFFT, Inverse Fast FourierTransform) by the symbol of step 2, finishes multi-carrier modulation;
The data that step 4. is obtained by step 3 are handled (IOTA, IsotropicOrthogonal Transform Algorithm) by the isotropism orthogonal transform, and the signal moulding is finished in moulding (or other fixed window types) filtering;
Step 5. digital-to-analogue (D/A) conversion, up-conversion transmit;
Receiving terminal (base station)
Step 1. received signal, down-conversion, analog-to-digital conversion obtain base band complex symbol frame sequence;
Step 2. is done matched filtering by isotropism orthogonal transformation algorithm function (IOTA, Isotropic Orthogonal TransformAlgorithm) matched filtering (or other fixed window types) module;
Step 3. is carried out fast Fourier transform (FFT, Fast FourierTransform) by the symbol after the step 2, finishes the multicarrier demodulation;
Step 4. is gone the orthogonalization phase mapping by the symbol after the step 3;
Step 5. is from by the symbol after the step 4, and amplitude-frequency and phase-frequency response by pilot frequency sequence extracts multipath channel utilize this channel information, is eliminated or is reduced the influence of multipath channel to the OFDM/OQAM signal by equalizer (as zero forcing equalization etc.);
Step 6. is carried out QAM demodulation and corresponding decoding by the symbol after the step 5, deposits data in.
Though this type of OFDM/OQAM system has the advantages that can select flexibly formed filter, but owing to do not utilize the channel information of downlink feedback, for a fixed receive-transmit system, in forwarding step 4 and receiving step 2, promptly can only adopt the selected formed filter and the filter that matches at transmitting terminal and receiving terminal, and can not be again be adjusted to mode filter automatically at the characteristic of channel, thereby the fluctuation of overall performance is big, poor stability; In addition, the OFDM/OQAM system is a single user system, can not be directly used in multiple access system.
Summary of the invention
The objective of the invention is on basis of background technology, the uplink multiple access technology of a kind of automatic adaptive channel characteristic variations of research and design, effectively improve spectrum efficiency, power system capacity and data transmission performance and resist multispectral ability of reining in expansion, reduce interference and the distortion of signal in channel between the user, to reach the purposes such as requirement that better satisfy high-speed mobile communications.
Solution of the present invention is to introduce staggered orthogonal amplitude modulation technique (OQAM) in OFDM access technology (OFDMA), adopt the good formed filter of time-frequency focus characteristics to substitute Cyclic Prefix simultaneously, and utilize the different user of downlink feedback and the channel information between the receiving terminal (base station), automatically be adjusted to the variation of mode filter with the adaptive channel characteristic, improve spectrum efficiency, power system capacity and data transmission performance and resist multispectral ability of reining in expansion, reduce interference and the distortion of signal in channel between the user; Thereby realize its purpose.Therefore, the inventive method comprises:
System initialization process: at first in the register of transmitting terminal (travelling carriage) and receiving terminal (base station), storing identical formed filter sequence, and making the corresponding different characteristic of channel of different formed filters, and setting up corresponding rule at transmitting-receiving two-end;
Its flow process is as follows:
A. transmitting terminal (travelling carriage):
A
1. select the formed filter with current characteristic of channel coupling: transmitting terminal sends enabled instruction, receiving terminal (base station) sends according to its instruction and contains the packet of pilot frequency sequence to transmitting terminal (travelling carriage), after transmitting terminal (travelling carriage) is received the information of its transmission, by wherein pilot frequency information is analyzed the current characteristic of channel and assesses current time channel ISI and the ICI annoyance level, from the formed filter sequence, select the formed filter that is complementary with this characteristic of channel then;
A
2. transmission information is carried out quadrature amplitude modulation: with signal source Bit data coding, carry out quadrature amplitude modulation (QAM, Quadrature Amplitude Modulation), obtain complex data after, framing, and add pilot frequency sequence;
A
3. zero insertion is handled: to steps A
2The Frame that obtains carries out zero insertion to be handled;
A
4. orthogonalization phase mapping: to steps A
3The data that obtain are carried out the orthogonalization phase mapping;
A
5. multi-carrier modulation: to steps A
4Data after the processing are finished multi-carrier modulation after (IFFT, InverseFast Fourier Transform) handled in anti-fast Fourier transform;
A
6. signal moulding: through steps A
5Data after the modulation treatment are according to steps A
1Select current formed filter, finish the signal moulding;
A
7. send signal: to steps A
6The forming data of gained is sent to receiving terminal with this signal after carrying out digital-to-analogue (D/A) conversion and upconversion process;
B. receiving terminal (base station):
B
1. processing to received signal: after receiving the signal of transmitting terminal, at first carry out down-conversion and analog-to-digital conversion (A/D) and handle, obtain sequence of data frames;
B
2. select the formed filter with current characteristic of channel coupling: receiving terminal (base station) is according to step B
1The sequence of data frames of gained by pilot frequency information wherein being analyzed the characteristic of current channel and being assessed current time channel ISI and the ICI annoyance level, is selected the formed filter that is complementary with this characteristic of channel then from the formed filter sequence;
B
3. multicarrier demodulation: to through step B
1Sequence of data frames after the processing is done fast Fourier transform and is handled (FFT, Fast Fourier Transform), finishes the multicarrier demodulation;
B
4. go the orthogonalization phase mapping: to step B
3Frame after the demodulation goes the orthogonalization phase mapping to handle;
B
5. extracted valid data: to step B
4The processing of zero-suppressing of the data of gained is with extracted valid data;
B
6. isostatic compensation: to step B
5The valid data of gained, integrating step B
2The characteristic of channel of gained is carried out isostatic compensation and is handled, and eliminates or reduces the influence of multipath channel to systematic function;
B
7. storage data: to step B
6Data after carrying out isostatic compensation and handling, carry out QAM demodulation and corresponding decoding processing after, the storage data.
Above-mentioned formed filter comprises expansion serial formed filter of Gaussian function (EGF) or nonopiate series of functions formed filter.Describedly carry out isostatic compensation and handle, its used equalizer is zero forcing equalization device or non-linear class equalizer.
The present invention is owing to introduced staggered orthogonal amplitude modulation technique (OQAM) in OFDM access technology (OFDMA), adopt the good formed filter of time-frequency focus characteristics to substitute Cyclic Prefix simultaneously, particularly utilize the different user of downlink feedback and the channel information between the receiving terminal (base station), the formed filter that automatic selection and its characteristic of channel are complementary is with the variation of adaptive channel characteristic; Can effectively improve spectrum efficiency, power system capacity and data transmission performance and resist multispectral ability of reining in expansion thereby have, reduce interference and the distortion of signal in channel between the user, can better satisfy the characteristics such as requirement of high-speed mobile communications.
Description of drawings
Fig. 1 is the inventive method schematic flow sheet (block diagram);
Fig. 2 is a specific embodiment of the invention up link transmitting terminal schematic diagram;
Fig. 3 is a specific embodiment of the invention up link receiving terminal schematic diagram.
Fig. 4 is ofdm system (OFDM/OQAM) schematic diagram based on staggered quadrature amplitude modulation.
Embodiment
It is example that this embodiment adopts following system condition: OFDMA/OQAM system subcarrier number is 1024, totally 32 users, and the active user uses the 0th to the 31st subcarrier, and moulding window filter range of choice is an EGF sequence of function formed filter.
System initialization process: at first in the register of transmitting terminal (travelling carriage) and receiving terminal (base station), store identical EGF sequence of function formed filter (spreading factor α=[0.1,0.2 ..., 0.9,1,1.1 ... 2.9,3]), and in the corresponding rule of transmitting-receiving two-end foundation;
Its flow process is as follows:
A. transmitting terminal (travelling carriage):
A
1. select the formed filter with current characteristic of channel coupling: transmitting terminal sends enabled instruction, receiving terminal (base station) sends according to its instruction and contains the packet of pilot frequency sequence to transmitting terminal (travelling carriage), after transmitting terminal (travelling carriage) is received the information of its transmission, by wherein pilot frequency information being analyzed the current characteristic of channel and assessing all square time delay expansion of current time channel and Doppler frequency-shift, select the formed filter that is complementary with this characteristic of channel according to following formula then
Wherein Δ τ and Δ ν are respectively all square time delay expansion and the Doppler frequency-shifts of current channel, ν
0And τ
0Represent the time interval of the subcarrier spacing and the formed filter of OFDMA/OQAM system respectively; For EGF function formed filter, can regulate ν by regulating spreading factor α
0And τ
0Thereby, reach the purpose of coupling.The formed filter that this place is selected is g (t);
A
2. transmission information is carried out quadrature amplitude modulation: with signal source Bit data coding, carry out quadrature amplitude modulation (4QAM, Quadrature Amplitude Modulation), obtain complex data after, framing, and add pilot frequency sequence (complete 1 sequence);
A
3. zero insertion is handled: to steps A
2The Frame that obtains carries out zero insertion to be handled, and replenishes 992 zero promptly for every frame data back;
A
4. orthogonalization phase mapping: to steps A
3The data that obtain multiply by j
M+nCarry out the orthogonalization phase mapping;
A
5. multi-carrier modulation: to steps A
4Data after the processing are finished multi-carrier modulation after (IFFT, Inverse Fast Fourier Transform) handled in 1024 anti-fast Fourier transform;
A
6. signal moulding: through steps A
5Data after the modulation treatment are according to steps A
1Select current formed filter g (t), finish the signal moulding;
A
7. send signal: to steps A
6After the forming data of gained carries out digital-to-analogue conversion and upconversion process, this signal is sent to receiving terminal;
B. receiving terminal (base station):
B
1. processing to received signal: after receiving the signal of transmitting terminal, at first carry out down-conversion and analog-to-digital conversion (A/D) and handle, obtain sequence of data frames;
B
2. select the formed filter with current characteristic of channel coupling: receiving terminal (base station) is according to step B
1The sequence of data frames of gained by pilot frequency information wherein being analyzed the characteristic of current channel and being assessed current time channel ISI and the ICI annoyance level, is selected the formed filter that is complementary with this characteristic of channel according to formula (1) then;
B
3. multicarrier demodulation: to through step B
1Sequence of data frames after the processing is made 1024 point quick Fourier conversion process (FFT, Fast Fourier Transform), finishes the multicarrier demodulation;
B
4. go the orthogonalization phase mapping: to step B
3Frame after the demodulation multiply by j
-(m+n)Go the orthogonalization phase mapping to handle;
B
5. extracted valid data: to step B
4The data extract the 0th of gained is removed last data at 992 to the 31st data;
B
6. isostatic compensation: to step B
5The valid data of gained, integrating step B
2The characteristic of channel of gained is utilized the zero forcing equalization compensation deals, with the influence of multipath channel to systematic function;
B
7. storage data: by step B
6After data, carry out QAM demodulation and corresponding decoding after, the storage data.
Claims (3)
1. the uplink multiple access technology of an automatic adaptive channel characteristic variations comprises:
System initialization process: at first in the register of transmitting terminal and receiving terminal, storing identical formed filter sequence, and making the corresponding different characteristic of channel of different formed filters, and setting up corresponding rule at transmitting-receiving two-end;
Its flow process is as follows:
A. transmitting terminal:
A
1. select the formed filter with current characteristic of channel coupling: transmitting terminal sends enabled instruction, receiving terminal (base station) sends according to its instruction and contains the packet of pilot frequency sequence to transmitting terminal, after transmitting terminal is received the information of its transmission, by wherein pilot frequency information is analyzed the current characteristic of channel and assesses current time channel ISI and the ICI annoyance level, from the formed filter sequence, select the formed filter that is complementary with this characteristic of channel then;
A
2. transmission information is carried out quadrature amplitude modulation: with signal source Bit data coding, carry out quadrature amplitude modulation, obtain complex data after, framing, and add pilot frequency sequence;
A
3. zero insertion is handled: to steps A
2The Frame that obtains carries out zero insertion to be handled;
A
4. orthogonalization phase mapping: to steps A
3The data that obtain are carried out the orthogonalization phase mapping;
A
5. multi-carrier modulation: to steps A
4Data after the processing are finished multi-carrier modulation after anti-fast Fourier transform is handled;
A
6. signal moulding: through steps A
5Data after the modulation treatment are according to steps A
1Select current formed filter, finish the signal moulding;
A
7. send signal: to steps A
6After the forming data of gained carries out digital-to-analogue conversion and upconversion process, this signal is sent to receiving terminal;
B. receiving terminal:
B
1. processing to received signal: after receiving the signal of transmitting terminal, at first carry out down-conversion and analog-to-digital conversion process, obtain sequence of data frames;
B
2. select the formed filter with current characteristic of channel coupling: receiving terminal is according to step B
1The sequence of data frames of gained by pilot frequency information wherein being analyzed the characteristic of current channel and being assessed current time channel ISI and the ICI annoyance level, is selected the formed filter that is complementary with this characteristic of channel then from the formed filter sequence;
B
3. multicarrier demodulation: to through step B
1Sequence of data frames after the processing is done fast Fourier transform and is handled, and finishes the multicarrier demodulation;
B
4. go the orthogonalization phase mapping: to step B
3Frame after the demodulation goes the orthogonalization phase mapping to handle;
B
5. extracted valid data: to step B
4The processing of zero-suppressing of the data of gained is with extracted valid data;
B
6. isostatic compensation: to step B
5The valid data of gained, integrating step B
2The characteristic of channel of gained is carried out isostatic compensation and is handled, and eliminates or reduces the influence of multipath channel to systematic function;
B
7. storage data: to step B
6Data after carrying out isostatic compensation and handling, carry out QAM demodulation and corresponding decoding processing after, the storage data.
2. by the uplink multiple access technology of the described automatic adaptive channel characteristic variations of claim 1, it is characterized in that described formed filter comprises expansion Gaussian function series formed filter or nonopiate series of functions formed filter.
3. by the uplink multiple access technology of the described automatic adaptive channel characteristic variations of claim 1, it is characterized in that described carry out isostatic compensation handle in used equalizer be zero forcing equalization device or non-linear class equalizer.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102611663A (en) * | 2011-01-20 | 2012-07-25 | 上海贝尔股份有限公司 | Communication method, equipment and system based on downlink channel adaptability |
| CN107733830A (en) * | 2016-08-12 | 2018-02-23 | 中兴通讯股份有限公司 | Method, apparatus and system caused by a kind of multi-carrier signal |
| CN113411275A (en) * | 2021-05-17 | 2021-09-17 | 山东浪潮通软信息科技有限公司 | FTN/OQAM system design method and device |
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| KR102291859B1 (en) | 2014-09-04 | 2021-08-20 | 삼성전자 주식회사 | Method and apparatus for feedback of multi carrier signal transmission and reception in wireless communication system |
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| CN101356757B (en) * | 2006-01-10 | 2012-09-05 | 松下电器产业株式会社 | Multicarrier modulation scheme as well as transmission apparatus and reception apparatus using the scheme |
| CN101521642B (en) * | 2009-04-01 | 2012-06-27 | 电子科技大学 | Pilot frequency sequence structure in OFDM/OQAM system and method for channel estimation |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102611663A (en) * | 2011-01-20 | 2012-07-25 | 上海贝尔股份有限公司 | Communication method, equipment and system based on downlink channel adaptability |
| CN102611663B (en) * | 2011-01-20 | 2016-06-29 | 上海贝尔股份有限公司 | Based on method, equipment and system that down channel self adaptation communicates |
| CN107733830A (en) * | 2016-08-12 | 2018-02-23 | 中兴通讯股份有限公司 | Method, apparatus and system caused by a kind of multi-carrier signal |
| CN113411275A (en) * | 2021-05-17 | 2021-09-17 | 山东浪潮通软信息科技有限公司 | FTN/OQAM system design method and device |
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