CN101167269A - Adaptive data multiplexing method in ofdma system and transmission/reception apparatus thereof - Google Patents

Abstract

A transmission/reception method and apparatus in an Orthogonal Frequency Division Multiplexing (OFDM)-based wireless communication system are provided, in which a data transmitter adaptively selects a multiplexing scheme according to a code rate of the transmission packet or an effective SNR of a wireless channel for a corresponding terminal, when transmitting a packet data channel. The adaptive multiplexing scheme is equal in concept to a scheme of adaptively implementing unitary precoding. The unitary precoded multiplexing includes Orthogonal Frequency code Domain Multiplexing (OFCDM), Fast Fourier Transform-Spread-OFDM (FFT-S-OFDM), Fast Frequency Hopping-OFDM (FFH-OFDM), and the like. The method and apparatus adaptively selects the multiplexing scheme and transmits/receives data using the selected multiplexing scheme, thereby improving reception performance of the packet data.

Description

Adaptive data multiplexing method in the orthogonal frequency division multiple access system and transmission/receiving system thereof

Technical field

The present invention relates generally to use the communication system of multiple access scheme.More specifically, the present invention relates to select best multiplexing scheme and use selected multiplexing scheme to send the transmission/method of reseptance and the device of data, to improve the receptivity of the data that in the system that uses based on the multiple access scheme transmission/reception data of OFDM (OFDM), send according to data transmission situation.

Background technology

Recently, in field of wireless communications systems, carry out the research about OFDM (OFDM) energetically, this to the high speed data transfer by wireless channel of great use.OFDM, a kind of scheme of using multicarrier to send data is that a class was changed to the circulation of serial incoming symbol parallel symbol and utilized the multi-carrier modulation of modulating each symbol such as a plurality of quadrature subcarriers of channel subcarrier before sending.

Fig. 1 is the block diagram that the structure of the transmitter that is used for general ofdm system is shown.

With reference to Fig. 1, the transmitter of general ofdm system comprises channel encoder 101, modulator 102, serial-to-parallel (S/P) transducer 103, contrary fast fourier transform (IFFT) unit 104, parallel-to-serial (P/S) transducer 105 and Cyclic Prefix (CP) inserter 106.

101 pairs of input information bit streams of channel encoder are carried out chnnel coding.Usually, use convolution coder, turbo encoder or low-density checksum (LDPC) encoder as channel encoder 101.

Quadriphase PSK (QPSK), 8 phase shift keyings (PSK) or 16 quadrature amplitude modulation (qam)s are carried out in the output of 102 pairs of channel encoders 101 of modulator.Though not shown among Fig. 1, those skilled in the art can add the rate-matched unit that is used to carry out repetition and perforation function obviously as can be known between parts 101 and 102.

It is the function of parallel signal that S/P transducer 103 has the conversion of signals that is used for from modulator 102 outputs.The output of the 104 pairs of S/P transducers 103 in IFFT unit is carried out IFFT and is calculated.

P/S transducer 105 is changed back serial signal with the output of IFFT unit 104.CP inserter 106 has the function that is used for to the output signal pended cyclic prefix (CP) of P/S transducer 105.

A kind of improved OFDM multiplexing scheme is arranged, and wherein transmitter is carried out hadamard (Hadamard) conversion to modulation symbol in frequency domain before sending.This scheme is commonly referred to multicarrier sign indicating number territory multiplexing (MC-CDM) or orthogonal frequency sign indicating number territory multiplexing (OFCDM).

Fig. 2 is the block diagram that the structure of general normalization precoding OFDM transmitter is shown.

With reference to Fig. 2, general normalization precoding OFDM transmitter comprises channel encoder 201, modulator 202, normalization precoder 203, S/P transducer 204, contrary fast fourier transform (IFFT) unit 205, P/S transducer 206 and CP inserter 207.

201 pairs of input information bit streams of channel encoder are carried out chnnel coding.Usually, use convolution coder, turbo encoder or LDPC encoder as channel encoder 201.

QPSK, 8PSK or 16QAM modulation are carried out in the output of 202 pairs of channel encoders 201 of modulator.Though not shown among Fig. 2, those skilled in the art can add the rate-matched unit that is used to carry out repetition and perforation function obviously as can be known between parts 201 and 202.

Normalization precoder 203 is common normalization precoders, describes the various examples of normalization precoding after a while with reference to Fig. 3 A to 3C.

S/P transducer 204 has the function that is used for the output signal from modulator 202 is converted to parallel signal.The output of the 205 pairs of S/P transducers 204 in IFFT unit is carried out IFFT and is calculated.

P/S transducer 206 is changed back serial signal with the output of IFFT unit 205.CP inserter 207 has the function that is used for to the additional CP of output signal of P/S transducer 206.

Fig. 3 A to 3C is the figure of a plurality of examples that the normalization precoder of Fig. 2 is shown.Fig. 3 A is the figure that the normalization precoder that wherein uses Hadamard transform is shown.

With reference to Fig. 3 A, described normalization precoder comprises symbolic solution multiplexer (DEMUX) 311, Walsh (Walsh) function capping unit 312 and Walsh summer 313.

Symbol DEMUX 311 will be converted to parallel signal from the serial signal that the modulator 202 of Fig. 2 is exported.Walsh function capping unit 312 is carried out and is utilized the walsh code with predetermined length each modulation symbol from symbol DEMUX 311 outputs to be carried out the processing of Walsh covering or spread spectrum.Walsh summer 313 is carried out the processing with the output of walsh function capping unit 312 output of each walsh function spread spectrum (that is, by) summation.

Fig. 3 B is the figure that the normalization precoder that wherein uses fast Fourier transform (FFT) is shown.

With reference to Fig. 3 B, described normalization precoder comprises symbol DEMUX 321, FFT unit 322 and P/S transducer 323.

Symbol DEMUX 321 will be converted to parallel signal from the serial signal that the modulator 202 of Fig. 2 is exported.The FFT conversion is carried out in the output of the 322 couples of symbol DEMUX 321 in FFT unit.P/S transducer 323 will be converted to serial signal by 322 parallel signals of exporting from the FFT unit.

Fig. 3 C is the figure that the normalization precoder that wherein uses fast frequency-hopped (FFH) is shown.

With reference to Fig. 3 C, described normalization precoder comprises symbol DEMUX 331, FFH linear processor 332 and P/S transducer 333.

Symbol DEMUX 331 will be converted to parallel signal from the serial signal that the modulator 202 of Fig. 2 is exported.The FFH linear transformation is carried out in the output of 332 couples of symbol DEMUX 331 of FFH linear processor.FFH is the technology of the different subcarrier of each OFDM sampling mapping.P/S transducer 333 will be converted to serial signal from the parallel signal of FFH linear processor 332 outputs.

In aforesaid traditional normalization precoding OFDM multiplexing scheme, the hadamard precoding OFDM scheme of Fig. 3 A will be called orthogonal frequency code division multiplexing (OFCDM) scheme, and the FFT precoding OFDM of Fig. 3 B will be called FFT spread spectrum OFDM (FFT-S-OFDM) scheme.In addition, the FFH precoding OFDM scheme of Fig. 3 C will be called fast frequency-hopped-OFDM (FFH-OFDM) scheme.

Fig. 4 is the figure of brief description of the notion of the general FFH that introduces among Fig. 3 C.

With reference to Fig. 4, will be at the FFT size of M=4, an OFDM symbol time by more existing frequency hopping and FFH technical descriptioon FFH technology.

In Fig. 4, reference numerals 401 expressions are used for the 4-OFDM sampling time is carried out the multi-carrier modulation device of existing every symbol frequency hopping.Reference numerals 405 to 408 expression FFH multi-carrier modulation devices.

In the existing frequency hopping shown in Fig. 4 left side, to the 4-OFDM sampling time, the input data are identical, and in each sampling time output signal exported one by one.Because it is mapping fixed joint carrier wave in the existing frequency hopping 1-OFDM symbol time, so identical by the piece of reference numerals 401 to 404 expressions for the 4-OFDM sampling time.

Yet, in the FFH technology shown in Fig. 4 the right, utilize the M:M change over switch to change mapping between subchannel data and the actual subcarrier in each sampling time.The subcarrier that first subchannel of being represented by reference numerals 405 is mapped to is mapped with order [1 42 3], the subcarrier that second subchannel of being represented by reference numerals 406 is mapped to is mapped with order [4 31 2], mapped by the subcarrier that the 3rd subchannel of reference numerals 407 expression is mapped to order [2 13 4], and by the fourth officer channel Mapping of reference numerals 408 expressions to subcarrier mapped with order [3 24 1].This mapping pattern is called the frequency hopping style of each subchannel.

As mentioned above, compare with normalization precoding OFDM technology, the OFDM technology demonstrates higher performance at low encoding rate.Yet, to compare with the OFDM technology, normalization precoding OFDM technology demonstrates higher performance at very high encoding rate (such as, 4/5 encoding rate).No matter these characteristics, common mobile communication system is non-to be used OFDM and normalization precoding OFDM technology with a good grace one of them is used for packet data transport channel.

Thereby, need improved adaptive data multiplexing method and transmission/receiving system in a kind of OFDMA system that use OFDM and normalization precoding OFDM technology.

Summary of the invention

An aspect of one exemplary embodiment of the present invention is to overcome the above problems at least and/or shortcoming and following advantage is provided at least.Thereby, an aspect of one exemplary embodiment of the present invention provides a kind of transmission/method of reseptance and device, its according to environment self-adaption utilize the two of OFDM and normalization precoding OFDM technology rather than only one of them, to improve the receptivity in the transmission/receiving block data in based on the wireless communication system of OFDM.

An aspect according to one exemplary embodiment of the present invention, adaptive data multiplexing sending method in the base station of a kind of OFDM (OFDMA) system is provided, terminal is carried out packet communication in the described OFDMA system in the covering of base station, the base station sends grouped data to terminal, and this method comprises: collection is used for the information that dispatching office needs; Use collected information and executing scheduling; The encoding rate and the predetermined threshold that will send to the data of selected terminal compare; Select suitable multiplexing scheme according to comparative result; And use selected multiplexing scheme to send grouped data.

Another aspect according to one exemplary embodiment of the present invention, adaptive data multiplexing sending method in the base station of a kind of OFDM (OFDMA) system is provided, terminal is carried out packet communication in the described OFDMA system in the covering of base station, the base station sends grouped data to terminal, and this method comprises: collection is used for the information that dispatching office needs; Use collected information and executing scheduling; Obtain the corresponding effective signal-to-noise ratio (SNR) of transmission grouping with selected terminal at normalization precoding OFDM (OFDM) and OFDM; Effective SNR of normalization precoding OFDM and effective SNR of OFDM are compared; Select to be fit to the multiplexing scheme of selected terminal according to comparative result; And use selected multiplexing scheme to send grouped data.

Another aspect according to one exemplary embodiment of the present invention, adaptive data multiplexing method of reseptance in the terminal of a kind of OFDM (OFDMA) system is provided, terminal is carried out packet communication in the described OFDMA system in the covering of base station, the base station sends grouped data to terminal, and this method comprises: the grouped data that determines whether to receive described terminal; If received the grouped data of described terminal, then search for the employed multiplexing scheme of grouped data of described terminal; And use the multiplexing scheme demultiplexing grouped data search.

Another aspect according to one exemplary embodiment of the present invention, the base station apparatus of a kind of OFDM (OFDMA) system is provided, terminal is carried out packet communication in the described OFDMA system in the covering of base station, the base station sends grouped data by adaptive data multiplexing to terminal, this device comprises: the normalization converter unit is used in frequency domain the modulation symbol that will send being carried out the normalization conversion; Switch unit is used to switch to described normalization converter unit; And controller, be used for determining whether to switch described switch unit according to multiplexing scheme.

Another aspect according to one exemplary embodiment of the present invention, the terminal installation of a kind of OFDM (OFDMA) system is provided, terminal is carried out packet communication in the described OFDMA system in the covering of base station, the base station sends grouped data by adaptive data multiplexing to terminal, this device comprises: contrary normalization converter unit is used in frequency domain the modulation symbol that receives being carried out contrary normalization conversion; And controller, be used for determining whether to enable described contrary normalization converter unit according to multiplexing scheme.

According to another aspect of one exemplary embodiment of the present invention, a kind of OFDM (OFDMA) system is provided, wherein terminal is carried out packet communication in the covering of base station; The base station sends grouped data by adaptive data multiplexing to terminal, collection is used for the information that dispatching office needs, use collected information and executing scheduling, the encoding rate and the predetermined threshold that will send to the data of selected terminal compare, select suitable multiplexing scheme according to comparative result, and use selected multiplexing scheme to send grouped data; And terminal determines whether to receive its grouped data, if received its grouped data, then searches for the employed multiplexing scheme of grouped data of himself, and uses the multiplexing scheme demultiplexing grouped data that searches.

According to another aspect of one exemplary embodiment of the present invention, a kind of OFDM (OFDMA) system is provided, wherein terminal is carried out packet communication in the covering of base station; The base station sends grouped data by adaptive data multiplexing to terminal, collection is used for the information that dispatching office needs, use collected information and executing scheduling, obtain the corresponding effective signal-to-noise ratio (SNR) of transmission grouping with selected terminal at normalization precoding OFDM (OFDM) and OFDM, effective SNR of normalization precoding OFDM and effective SNR of OFDM are compared, select to be fit to the multiplexing scheme of selected terminal according to comparative result, and use selected multiplexing scheme to send grouped data; And terminal determines whether to receive its grouped data, if received its grouped data, then searches for the employed multiplexing scheme of grouped data of himself, and uses the multiplexing scheme demultiplexing grouped data that searches.

By disclose the detailed description of one exemplary embodiment of the present invention below in conjunction with accompanying drawing, other purpose of the present invention, advantage and notable feature will become apparent those skilled in the art.

Description of drawings

By the detailed description below in conjunction with accompanying drawing, above and other purpose, feature and the advantage of some one exemplary embodiment of the present invention will become more apparent, wherein:

Fig. 1 is the block diagram that the structure of the transmitter that is used for general ofdm system is shown;

Fig. 2 is the block diagram that the structure of general normalization precoding OFDM transmitter is shown;

Fig. 3 A is the figure that the normalization precoder that wherein uses Hadamard transform is shown;

Fig. 3 B is the figure that the normalization precoder that wherein uses fast Fourier transform (FFT) is shown;

Fig. 3 C is the figure that the normalization precoder that wherein uses fast frequency-hopped (FFH) is shown;

Fig. 4 is the figure of brief description of the notion of the general FFH that introduces among Fig. 3 C;

Fig. 5 illustrates the OFDM of encoding rate=1/4 for transmission block and the figure of the performance comparison result between the OFCDM;

Fig. 6 illustrates the OFDM of encoding rate=1/2 for transmission block and the figure of the performance comparison result between the OFCDM;

Fig. 7 illustrates the OFDM of encoding rate=4/5 for transmission block and the figure of the performance comparison result between the OFCDM;

Fig. 8 and 9 is the figure based on the method in the wireless communication system of OFDM that illustrate according to one exemplary embodiment of the present invention, wherein transmitter is selected multiplexing scheme based on predetermined criterion at every turn adaptively when sending Packet Data Channel, and uses selected multiplexing scheme to send grouping;

Figure 10 is the figure based on the structure of the transmitter of the self adaptation multiplexing method of Fig. 8 or 9 that illustrates according to one exemplary embodiment of the present invention;

Figure 11 is the figure that illustrates according to the method for one exemplary embodiment of the present invention, and wherein receiver uses the self adaptation multiplexing method that proposes to receive grouping; And

Figure 12 is the figure that illustrates according to the structure of the receiver of one exemplary embodiment of the present invention.

Embodiment

The entity such as detailed structure and parts that defines in the specification provides and is used to help the complete understanding embodiments of the invention.Thereby those of ordinary skills will be appreciated that, can carry out various changes and modification to the embodiments described herein and do not deviate from scope and spirit of the present invention.Equally, for knowing and for purpose of brevity, having omitted the explanation of known function and structure.

The term of broad sense " normalization precoding OFDM " comprises that OFCDM, FFT-S-OFDM and FFH-OFDM's is whole.Though Fig. 5 to 7 shows is comparing data between OFDM and the OFCDM, and OFCDM, FFT-S-OFDM and FFH-OFDM all have identical characteristic.Thereby, Fig. 5 to 7 can be regarded as the emulated data between OFDM and the normalization precoding OFDM.

(that is, OFDM and normalization precoding OFDM) relative performance is not constant to aforementioned two kinds of technology, but can change according to several factors.Key factor in these several factors can comprise the encoding rate of data transmission block and the frequency selectivity of channel.Thereby, with reference to Fig. 5 to 7, will performance comparison result between OFDM and the OFCDM be described with regard to encoding rate and selectivity of channel frequency now.

Fig. 5 is the figure that the performance comparison result between the OFDM of encoding rate=1/4 for transmission block and the OFCDM (among Fig. 5 to 7 note do ' MC CDM ') is shown.Among Fig. 5 to 7, gain paths such as ' EG ' expression, and ' UEG ' expression does not wait gain path.In the curve chart, X-axis is represented potential energy/overall noise (Eb/Nt), and Y-axis is represented packet-error-rate (PER).

Among Fig. 5, OFDM is better than OFCDM (MC CDM) in encoding rate=1/4 place's performance of transmission block.Equally, the performance difference level changes according to the variation in the frequency selectivity (that is the variation in the number of paths).

Fig. 6 illustrates the OFDM of encoding rate=1/2 for transmission block and the figure of the performance comparison result between the OFCDM.

Among Fig. 6, OFDM is better than OFCDM (MC CDM) in encoding rate=1/2 place's performance of transmission block.Equally, the performance difference level changes according to the variation in the frequency selectivity (that is the variation in the number of paths).

Fig. 7 illustrates the OFDM of encoding rate=4/5 for transmission block and the figure of the performance comparison result between the OFCDM.

Among Fig. 7, OFDM is better than OFCDM in encoding rate=4/5 place's performance of transmission block.Equally, the performance difference level changes according to the variation in the frequency selectivity (that is the variation in the number of paths).

Fig. 8 and 9 is the figure based on the method in the wireless communication system of OFDM that illustrate according to one exemplary embodiment of the present invention, wherein transmitter is selected multiplexing scheme based on predetermined criterion at every turn adaptively when sending Packet Data Channel, and uses selected multiplexing scheme to send grouping.

In other words, Fig. 8 and 9 is the methods that send forward data from the base station to terminal that illustrate according to one exemplary embodiment of the present invention.According to the base station select adaptively multiplexing scheme based on criterion, described forward data sending method can be divided into the method for Fig. 8 and 9.Below the method for Fig. 8 will be described at first.

With reference to Fig. 8, in step 801, the scheduler of packet sender is collected and is used for the information that dispatching office needs.The information that being used for dispatching office needs can comprise the amount of service quality (QoS) grade, each user's the current channel condition of each user's communications business and each user's current transmission communication service usually.

In step 802, the scheduler of packet sender is operation dispatching after collection is used for information that dispatching office needs.In scheduling process, scheduler is determined the user's that it will send with a data rate in the corresponding time grouped data.User for selecting can select one or more user according to system status.Specified data speed means that how long determine will be to send many lot of data.In this process, general mobile communication system is determined modulating rule (for example, QPSK, 8PSK, 16QAM or the like) and encoding rate with each individual consumer's data rate.

After determining scheduling, determine to be used to send the multiplexing scheme of the grouped data of selected user in to 805 in step 803.The core that step 803 can be regarded as one exemplary embodiment of the present invention to the operation in 805.In step 803, packet sender is determined as the result of scheduling and definite encoding rate that is used for grouped data is higher than or be lower than predetermined threshold T_r.According to encoding rate select the reason of multiplexing scheme to be because the performance of OFDM and normalization precoding OFDM to the encoding rate sensitivity, shown in the simulation result of Fig. 5 and 7.Thereby some one exemplary embodiment of the present invention is selected multiplexing scheme based on the threshold value of predetermined encoding rate in packet sender.

If determine that in step 803 encoding rate is not higher than T_r, then packet sender determines that OFDM is as multiplexing scheme in step 804.On the other hand, packet sender determines that normalization precoding OFDM is as multiplexing scheme in step 805.After this, in operation 806, packet sender sends grouped data according to the multiplexing scheme of determining in to 805 in step 803.

Fig. 9 illustrates the figure that comes to determine adaptively the process of multiplexing scheme according to the use of one exemplary embodiment of the present invention another criterion different with Fig. 8.

With reference to Fig. 9, in step 901, the scheduler of packet sender is collected and is used for the information that dispatching office needs.The information that being used for dispatching office needs can comprise the amount of QoS grade, each user's the current channel condition of each user's communications business and each user's current transmission communication service usually.

In step 902, the scheduler of packet sender is operation dispatching after collection is used for information that dispatching office needs.In scheduling process, scheduler is determined the user's that it will send with a data rate in the corresponding time grouped data.User for selecting can select at least one user according to system status.Specified data speed means that how long determine will be to send many lot of data.In this process, general mobile communication system is determined modulating rule (for example, QPSK, 8PSK, 16QAM or the like), encoding rate and each individual consumer's data rate.

After determining scheduling, determine to be used to send the multiplexing scheme of the grouped data of selected user in to 906 in step 903.Can regard step 903 to the operation in 906 as core of the present invention.Be used for determining adaptively that according to another of one exemplary embodiment of the present invention criterion of multiplexing scheme comprises effective signal to noise ratio (snr).Also promptly, the method for proposition is determining aspect effective SNR of the current channel of selected user that OFDM is higher than or is lower than normalization precoding OFDM, and then selects to have the multiplexing scheme of higher effective SNR.

Effective SNR of OFDM will remember and make SNR _Eff_ OFDM, and effective SNR of normalization precoding OFDM will remember and make SNR _Eff_ Unitary.Usually, can in each terminal, measure each user's wireless channel, so described terminal can be known SNR _Eff_ OFDM and SNR _Eff_ Unitary.Thereby, know SNR in order to allow the base station _Eff_ OFDM and SNR _Eff_ Unitary has a kind of possible method, and wherein each terminal is with SNR _Eff_ OFDM and SNR _EffThe two feeds back to the base station _ Unitary.Also have the method for another possibility, wherein each terminal is with SNR _Eff_ OFDM and SNR _EffOne of them feeds back to the base station with the information about its first-selected multiplexing scheme _ Unitary.

The base station obtains the SNR of each terminal in step 903 and the said method _Eff_ OFDM and SNR _EffThe process correspondence of _ Unitary.To be used to calculate SNR as the example introduction below _Eff_ OFDM and SNR _EffThe conventional method of _ Unitary.

${\mathrm{SNR}}_{\mathrm{eff}}\_\mathrm{Unitary}=\frac{{\mathrm{\&lambda;}}_{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="S2006800144675E00061.png"\; state="\{\{state\}\}">T</figure-callout>}}^2}{{\mathrm{N\&lambda;}}_T-.{\mathrm{\&lambda;}}_{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="S2006800144675E00061.png"\; state="\{\{state\}\}">T</figure-callout>}}^2},$

Wherein ${\mathrm{\&lambda;}}_T=\underset{k=1}{\overset{N}{\mathrm{\&Sigma;}}}{\mathrm{\&lambda;}}_k=\underset{k=1}{\overset{N}{\mathrm{\&Sigma;}}}\frac{{\mathrm{\&gamma;}}_0\&CenterDot;{\left|g_k\right|}^2}{{\mathrm{\&gamma;}}_0\&CenterDot;{|g_k|}^2+1}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(1\right)$

And γ ₀| g _k| ²SNR equation (1) expression of=the k subcarrier is used to obtain SNR _EffThe conventional method of _ Unitary.

SNR _eff_OFDM＝C ^-1(R _sum)，

Wherein $R_{\mathrm{sum}}=\frac{1}{N_{\mathrm{data}}}\underset{n,k}{\mathrm{\&Sigma;}}C\left(\mathrm{SNR}\right[k\left]\right)\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right)$

Equation (2) expression is used to obtain SNR _EffThe conventional method of _ OFDM.In the equation (2), N _DataRepresent to be used in the OFDM symbol to send the quantity of the subcarrier of data, SNR[k] represent the SNR of each subcarrier, C (SNR[k]) expression AWGN capacity formula, and C ^-1(R _Sum) inverse function of expression C (SNR[k]).

${\mathrm{SNR}}_{\mathrm{eff}}=-\mathrm{\&beta;}\ln \left(\frac{1}{N_u}\underset{k=1}{\overset{N_u}{\mathrm{\&Sigma;}}}{e}^{-\frac{{\mathrm{\&gamma;}}_k}{\mathrm{\&beta;}}}\right)\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(3\right)$

Equation (3) expression is used to obtain SNR _EffThe another kind of conventional method of _ OFDM.In the equation (3), β is a constant, N _uThe sum of vice carrier wave, and γ _kThe SNR of vice carrier wave #k.In step 904, packet sender obtains SNR _Eff_ OFDM and SNR _Eff_ Unitary also compares SNR _Eff_ OFDM and SNR _EffThe level of _ Unitary.

If in step 904, determine SNR _Eff_ Unitary is higher than SNR _Eff_ OFDM, then packet sender selects normalization precoding OFDM as multiplexing scheme in step 906.Otherwise packet sender selects OFDM as multiplexing scheme in step 905.After this, in step 907, packet sender sends grouped data according to selected multiplexing scheme.

Figure 10 is the figure based on the structure of the transmitter of the self adaptation multiplexing method of Fig. 8 or 9 that illustrates according to one exemplary embodiment of the present invention.

With reference to Figure 10, described transmitter based on the self adaptation multiplexing method comprises channel encoder 1001, modulator 1002, normalization converter unit 1003, switch unit 1004, controller 1005, S/P transducer 1006, IFFT unit 1007, P/S transducer 1008 and CP inserter 1009.

1001 pairs of input information bit streams of channel encoder are carried out chnnel coding.Usually, use convolution coder, turbo encoder or LDPC encoder as channel encoder 1001.QPSK, 8PSK or 16QAM modulation are carried out in the output of 1002 pairs of channel encoders 1001 of modulator.Though not shown among Figure 10, those skilled in the art can add the rate-matched unit that is used to carry out repetition and perforation function obviously as can be known between parts 1001 and 1002.

Switch unit 1004 is carried out switching under the control of controller 1005, with use OFDM and normalization precoding OFDM one of them as multiplexing scheme.Controller 1005 is controlled switch unit 1004 in the process of Fig. 8 or 9.If switch unit 1004 switches to normalization converter unit 1003 under the control of controller 1005, then enable the normalization precoder.Also promptly, utilize OFCDM, the FFT-S-OFDM or the FFH-OFDM that describe with reference to Fig. 2 to send data.

Normalization converter unit 1003 is equal to any the normalization precoder shown in Fig. 3 A to 3C in structure and operation.If switch unit 1004 switches to S/P transducer 1006 under the control of controller 1005, then transmitter is not enabled normalization converter unit 1003.

S/P transducer 1006 has the function that is used for serial input signals is converted to parallel signal.The output of the 1007 pairs of S/P transducers 1006 in IFFT unit is carried out IFFT and is calculated.P/S transducer 1008 is converted to serial signal with the also line output of IFFT unit 1007.CP inserter 1009 has the function that is used for to the additional CP of output signal of P/S transducer 1008.

Though among Figure 10 and not shown, according to the intended size of the output of S/P transducer 1006, the size of the matrix corresponding with normalization converter unit 1003 is variable.In addition, because the size variable of described matrix can use a plurality of normalization precoders.Yet transmitter is not to comprise a plurality of normalization precoders, can utilize a normalization precoder to carry out the calculating that iterates yet.

For example, if the output of S/P transducer 1006 is of a size of 16 (quantity that means the subcarrier of distributing to transmitter is 16), mean that then the input of S/P transducer 1006 is of a size of 16.Wherein, can use the pre-encoder matrix (or the pre-encoder matrix that utilizes a size-4 is done four calculating) of the pre-encoder matrix of a size-16, the pre-encoder matrix of two sizes-8 (or the pre-encoder matrix that utilizes a size-8 is done twice calculating), four sizes-4 or the pre-encoder matrix (or the pre-encoder matrix that utilizes a size-2 is done eight calculating) of eight sizes-2 to be used for normalization converter unit 1003.

Simultaneously, some one exemplary embodiment of the present invention is not must be confined to forward send.The method that proposes can be applied to reverse transmission equally, that is, and and from the data transmission of terminal to base station.Yet, in most systems, because the operating main body of scheduling is the base station, so after with the direct operation dispatching of the mode of Fig. 8 or 9, terminal receives from the base station and is used for the oppositely schedule information of transmission, rather than uses described self adaptation multiplexing method.After this, send time of the permission of data at transmitter, transmitter is selected multiplexing scheme in slightly different mode adaptively according to criterion same as described above.

Figure 11 is the figure that illustrates according to the method for one exemplary embodiment of the present invention, and wherein receiver uses the self adaptation multiplexing method that proposes to receive grouping.

Though send the method for describing Figure 11 with reference to the grouping of the forward from the base station to the terminal, described method can be applied to reverse packet equally and send.

With reference to Figure 11, in step 1101, terminal determines whether to have received the grouping of himself continuously.Corresponding operating in operation in the step 1101 and the common block data system is equal to.Also promptly, in this process, terminal monitors along the packet data control channel of direction transmission continuously and determines whether any grouping of distributing to this terminal oneself.

If definite grouping that has received this terminal self in step 1101, the then process of terminal execution receiving block data channel in step 1102.At this moment, terminal should be searched for grouping and be sent employed multiplexing scheme (OFDM and normalization precoding OFDM one of them).

For the operation of performing step 1102, two kinds of possible methods are arranged.In first kind of possible method, the base station provides the information of the employed multiplexing scheme of indication to terminal by packet data control channel.

In the another kind of possible method, pre-defined employed multiplexing scheme is centrally located in specific encoding rate between sender and recipient.One exemplary embodiment person, in a single day receiver has known encoding rate, just can determine that transmitter has used any multiplexing scheme when sending grouping.For example, pre-defined at the encoding rate place use OFDM of being less than or equal to 1/2, and use OFCDM at the encoding rate place that is higher than 1/2.

In step 1103, terminal will send to its Packet Data Channel demodulation according to the multiplexing scheme that obtains in step 1102.

Figure 12 is the figure that illustrates according to the structure of the receiver of one exemplary embodiment of the present invention.

With reference to Figure 12, described receiver comprises CP canceller 1201, S/P transducer 1202, fast Fourier transform (FFT) unit 1203, P/S transducer 1204, contrary normalization converter unit 1205, controller 1206, demodulator 1207 and channel decoder 1208.

CP canceller 1201 is deleted CP from the signal that receives.The conversion of signals that S/P transducer 1202 will be deleted the reception of CP is a parallel signal, and described parallel signal is outputed to FFT unit 1203.P/S transducer 1204 is converted to serial signal with the output of FFT unit 1203.Contrary normalization converter unit 1205 is the pieces that are used to carry out contrary normalization conversion.Contrary normalization converter unit 1205 determines to enable the still contrary normalization converter of forbidding under the control of controller 1206.To be input to demodulator 1207 against the output of normalization converter unit 1205, and the output of demodulator 1207 will be input to channel decoder 1208.Channel decoder 1208 obtains final information by the channel-decoding process.

Though it is also not shown among Figure 12, with Figure 10 in similarly in the method, according to the intended size of the output of P/S transducer 1204, the size of the matrix corresponding with contrary normalization converter unit 1205 is variable, because the size variable of described matrix can use a plurality of normalization precoders.Yet receiver is not to comprise a plurality of normalization precoders, can utilize a normalization precoder to carry out the calculating that iterates yet.For example, if the output of supposition P/S transducer 1204 is of a size of 16, then can use the pre-encoder matrix (or the pre-encoder matrix that utilizes a size-4 is done four calculating) of the pre-encoder matrix of a size-16, the pre-encoder matrix of two sizes-8 (or the pre-encoder matrix that utilizes a size-8 is done twice calculating), four sizes-4 or the pre-encoder matrix (or the pre-encoder matrix that utilizes a size-2 is done eight calculating) of eight sizes-2 to be used for contrary normalization converter unit 1205.

The self adaptation multiplexing method that proposes among the present invention also can use in the system that adopts mixed automatic retransmission request (HARQ).Usually, in the grouping process of transmitting in the system that adopts HARQ, under many situations, the encoding rate that is used for initialization is higher.Thereby if receiver uses OFDM to be used for HARQ based on normalization precoding OFDM during initialization according to the rule that proposes, then it can improve receptivity expeditiously.In addition, can by according to effectively SNR rather than the initialization of encoding rate adaptively modifying and the multiplexing scheme in sending again use and be used for definite multiplexing rule.

In order to simplify the HARQ operation, a kind of possible method is arranged, wherein in a single day in initialization, determined multiplexing scheme based on encoding rate or effective SNR, just can use the multiplexing scheme identical to be used for sending again with the scheme of in initialization, determining.As mentioned above, those skilled in the art obviously as can be known, the self adaptation multiplexing method that proposes in the one exemplary embodiment of the present invention can be used for HARQ, and even can use that two criterions (that is, encoding rate and effectively SNR) of the receptivity of the grouping that helps to improve transmission wherein select for other purpose one of determine multiplexing scheme.

From the above description as can be known, in the communication system of use based on the multiple access scheme of OFDM, some one exemplary embodiment of the present invention can use the self adaptation multiplexing method to improve the receptivity of the wireless packet data of transmission.

Though showed and described the present invention with reference to its some embodiment, but it will be appreciated by those skilled in the art that and to make various changes and not deviate from the spirit and scope of the present invention that limit by appended claims and equivalent thereof from form and details therein.

Claims (14)

1. the adaptive data multiplexing sending method in the base station of an OFDM (OFDMA) system, terminal is carried out packet communication in the described OFDMA system in the covering of base station, and the base station sends grouped data to terminal, this method comprises:

Collection is used for the information that dispatching office needs;

Use collected information and executing scheduling;

The encoding rate and the threshold value that will send to the data of selected terminal compare;

Select suitable multiplexing scheme according to comparative result; And

Use selected multiplexing scheme to send grouped data.

2. adaptive data multiplexing sending method as claimed in claim 1, wherein said multiplexing scheme comprises: the normalization precoding OFDM of selecting (OFDM), if the encoding rate of described data is lower than described threshold value; And OFDM, if the encoding rate of described data is higher than described threshold value.

3. the adaptive data multiplexing sending method in the base station of an OFDM (OFDMA) system, terminal is carried out packet communication in the described OFDMA system in the covering of base station, and the base station sends grouped data to terminal, this method comprises:

Collection is used for the information that dispatching office needs;

Use collected information and executing scheduling;

Obtain the corresponding effective signal-to-noise ratio (SNR) of transmission grouping with selected terminal at normalization precoding OFDM (OFDM) and OFDM;

Effective SNR of normalization precoding OFDM and effective SNR of OFDM are compared;

Select to be fit to the multiplexing scheme of selected terminal according to comparative result; And

Use selected multiplexing scheme to send grouped data.

4. adaptive data multiplexing sending method as claimed in claim 3, wherein said multiplexing scheme comprises: the normalization precoding OFDM that selects, if effective SNR of normalization precoding OFDM is higher than effective SNR of OFDM; And OFDM, if effective SNR of normalization precoding OFDM is lower than effective SNR of OFDM.

5. the adaptive data multiplexing method of reseptance in the terminal of an OFDM (OFDMA) system, terminal is carried out packet communication in the described OFDMA system in the covering of base station, and the base station sends grouped data to terminal, this method comprises:

Determine whether to receive the grouped data of terminal;

If received the grouped data of terminal, the employed multiplexing scheme of the grouped data of search terminal then; And

The multiplexing scheme demultiplexing grouped data that use searches.

6. adaptive data multiplexing method of reseptance as claimed in claim 5, wherein said multiplexing scheme comprise normalization precoding OFDM (OFDM) and OFDM at least one of them.

7. the base station apparatus of an OFDM (OFDMA) system, terminal is carried out packet communication in the described OFDMA system in the covering of base station, and the base station sends grouped data by adaptive data multiplexing to terminal, this device comprises:

The normalization converter unit is used in frequency domain the modulation symbol that will send being carried out the normalization conversion;

Switch unit is used to switch to described normalization converter unit; And

Controller is used for determining whether to switch described switch unit according to multiplexing scheme.

8. base station apparatus as claimed in claim 7, wherein said multiplexing scheme comprise normalization precoding OFDM (OFDM) and OFDM at least one of them.

9. the terminal installation of an OFDM (OFDMA) system, terminal is carried out packet communication in the described OFDMA system in the covering of base station, and the base station sends grouped data by adaptive data multiplexing to terminal, this device comprises:

Contrary normalization converter unit is used in frequency domain the modulation symbol that receives being carried out contrary normalization conversion; And

Controller is used for determining whether to enable described contrary normalization converter unit according to multiplexing scheme.

10. terminal installation as claimed in claim 9, wherein said multiplexing scheme comprise normalization precoding OFDM (OFDM) and OFDM at least one of them.

11. an OFDM (OFDMA) system comprises:

The base station, be used to collect the information that is used for the dispatching office need, use collected information and executing scheduling, the encoding rate and the threshold value that will send to the data of selected terminal compare, select suitable multiplexing scheme according to comparative result, and use selected multiplexing scheme to send grouped data; And

Terminal, be used in the covering of base station, carrying out packet communication, wherein said base station sends grouped data by adaptive data multiplexing to terminal, described terminal determines whether to receive its grouped data, if received its grouped data, then search for the employed multiplexing scheme of grouped data of himself, and use the described grouped data of multiplexing scheme demultiplexing that searches.

12. OFDMA as claimed in claim 11 system, wherein said multiplexing scheme comprise at least following one of them: the normalization precoding OFDM of selecting (OFDM), if the encoding rate of described data is lower than described threshold value; And OFDM, if the encoding rate of described data is higher than described threshold value.

13. an OFDM (OFDMA) system comprises:

The base station, be used to collect the information that is used for the dispatching office need, use collected information and executing scheduling, obtain the corresponding effective signal-to-noise ratio (SNR) of transmission grouping with selected terminal among normalization precoding OFDM (OFDM) and the OFDM each, effective SNR of normalization precoding OFDM and effective SNR of OFDM are compared, select to be fit to the multiplexing scheme of selected terminal according to comparative result, and use selected multiplexing scheme to send grouped data; And

Terminal, be used in the covering of base station, carrying out packet communication, wherein said base station sends grouped data by adaptive data multiplexing to terminal, described terminal determines whether to receive its grouped data, if received its grouped data, then search for the employed multiplexing scheme of grouped data of himself, and use the described grouped data of multiplexing scheme demultiplexing that searches.

14. OFDMA as claimed in claim 13 system, wherein said multiplexing scheme comprise at least following one of them: the normalization precoding OFDM that selects, if effective SNR of normalization precoding OFDM is higher than effective SNR of OFDM; And OFDM, if effective SNR of normalization precoding OFDM is lower than effective SNR of OFDM.

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