CN102655444A - Method and system for uplink two-user relay transmission - Google Patents
Method and system for uplink two-user relay transmission Download PDFInfo
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Abstract
The invention discloses a method for uplink two-user relay transmission, which comprises the following steps that: a base station is used for respectively processing two-user data which are received in the first time; when the two-user data which are processed are not completely correct, a relay station is notified to perform secondary communication; and the relay station performs soft network coding processing and soft modulation processing on the processed two-user data stored after the primary communication, and sends the processed data to the base station. The invention also provides a system for the uplink two-user relay transmission. According to the technical scheme provided by the invention, the transmission bandwidth in the relay transmission process can be saved, and the relay transmission performance is improved.
Description
Technical Field
The present invention relates to the field of mobile communications, and in particular, to a method and a system for uplink two-user relay transmission.
Background
The development of future wireless communication requires the realization of wide area continuous coverage, supporting higher rate transmission. As an emerging technology, the relay technology is considered as a better candidate scheme for improving system throughput or coverage area in an LTE-Advanced (Long term evolution Advanced) system, which opens up a wide prospect for application of the relay technology and also provides a new challenge for the wireless communication technology.
The network coding technology is a new technology, which was originally proposed in the wired network, but developed vigorously in the wireless communication technology in recent years, and the research of the network coding technology in the wireless network shows that it can greatly improve the transmission performance and transmission efficiency.
In the research on the application of network coding to the relay technology, the most important discussion is that two uplink users share one relay scenario, that is, the two users transmit signals to the base station and the relay station in a multiple access manner, if the base station does not completely and correctly receive the data of the two users, the relay station is required to transmit the same data again, and in order to improve the transmission efficiency, the transmission of the relay station may use the idea of network coding to perform network coding on the data frames of the two users, that is, after performing xor calculation on the information bits of the data frames of the two users, the relay station transmits the data frames subjected to network coding to the base station.
For such a scenario, besides a network coding mode adopting bit-level exclusive or calculation, some modifications, such as analog network coding, soft network coding, etc., are also studied to be performed on a network coding process; analog network coding refers to the network coding process which is not standard binary domain operation, but real number domain calculation, that is, the data of each user is multiplied by a scale factor and then added in the real number domain. The advantage of adopting analog network coding is that if the transmission channel is good and the scale factor is reasonably designed, two sequences can be recovered or the reliability of the two sequences can be calculated according to the value after network coding; in addition to the network coding value, the network coding of the conventional standard binary domain also needs to know one of the user values to calculate the other user value.
The traditional relay forward transmission technology includes the technologies of direct amplification forward transmission, decoding forward transmission and the like, the amplification forward transmission technology means that a relay station only amplifies received data and then forwards the data, the decoding forward transmission technology firstly decodes the data to recover the data and then modulates the data, and then forwards the modulated data, the amplification forward transmission technology is simple to realize, but the noise received in front is also amplified and forwards the data to a front end so as to influence the performance of a relay, the noise is partially inhibited after the decoding forward transmission technology is decoded, but if the decoded data has errors and is directly modulated and then forwards the data to the front end, the risk of amplifying the noise exists, a common solution is to judge the correctness of the decoded data by adding a check code, only the correct data is forwarded, so that the defect of noise amplification is avoided, but if a data frame received by the relay has errors, the forwarding cannot be continued and the data frame must be received again until correct, resulting in a reduction in the overall transmission efficiency. For this reason, a so-called soft network coding technique is proposed, that is, at the relay station, a soft network coding method is adopted for network coding. The soft network coding requires that the input value is the reliability of bits, and then the bit reliability after the XOR of the data frame information bits of two users is calculated according to the reliability, wherein the reliability is generally expressed by log-likelihood ratio and is an analog value, namely a real value. After the calculation is finished, the analog value is directly transmitted or quantized; the quantization is to change the real value into an integer value and not to change the integer value into a binary value, so as to avoid the amplification of noise caused by modulating after judging the bit reliability in the traditional method.
Disclosure of Invention
In view of the above, the present invention provides a method and a system for uplink two-user relay transmission, which can save transmission bandwidth during relay transmission and improve relay transmission performance.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
the invention provides an uplink two-user relay transmission method, which comprises the following steps:
the base station respectively processes the two user data received for the first time, and when the two processed user data are determined not to be all correct, the base station informs the relay station to carry out the second communication;
the relay station performs soft network coding processing and soft modulation processing on the two processed user data stored after the first communication, and sends the two processed user data to the base station.
In the above method, before the base station respectively processes the first two received user data, the method further includes:
when the first communication is carried out, the two user terminals process the user data respectively and send the processed user data to the relay station and the base station.
In the above method, the two user terminals respectively process the user data, and send the processed user data to the relay station and the base station is:
the two user terminals respectively process own user data according to a conventional baseband signal processing process, perform radio frequency end signal sending processing on the processed user data to obtain radio frequency signals, and send the radio frequency signals obtained after the user data processing to the relay station and the base station through radio waves; the conventional baseband signal processing process is as follows: adding frame quality check sequence, channel coding, modulation, transmission processing, and/or conventional baseband signal processing to the pilot insertion, transmission processing.
In the above method, after the base station respectively processes the two user data received for the first time, the method further includes:
and when the processed two user data are all correct, the base station receives the user data of the next frame.
In the above method, the method further comprises:
and the base station performs soft demodulation processing and soft network decoding processing on the two user data received for the second time, and performs iterative decoding according to the two user data received for the two times after processing.
In the above method, the processing, by the base station, of the two user data received for the first time respectively includes:
the base station carries out base station radio frequency end receiving processing and baseband signal processing on the received radio frequency signals sent by the two user terminals to obtain bit reliability information of the two user terminals, the buffer stores the bit reliability information, and the base station judges whether the bit reliability information is all correct according to a frame quality check sequence added in user data; the baseband signal processing is receiving processing, soft demodulation, soft decoding, and/or the baseband signal processing is receiving processing and channel estimation processing.
In the above method, the relay station performs soft network coding and soft modulation on the two processed user data stored after the first communication, and sends the two processed user data to the base station:
after receiving the signaling fed back by the base station, the relay station performs soft network coding processing on the processed user data of the two user terminals stored in the buffer after the first communication, inputs the user data into the soft modulator for soft modulation, and finally inputs the soft modulation value obtained after the soft modulation into the radio frequency end, and the radio frequency end generates a radio frequency signal and sends the radio frequency signal to the base station.
In the above-mentioned method, the first step of the method,
the soft network coding is that the network coding module carries out network coding according to the input bit reliability information, namely the processed two user terminals, and the output bit reliability information is also output;
the soft modulation is that the soft modulator obtains the average value of modulation symbols according to the input bit reliability information, and the average value of the modulation symbols is used as the output of the soft modulator.
In the above method, the base station performs soft demodulation processing and soft network decoding processing on the two user data received for the second time, and performs iterative decoding according to the two user data received twice after processing as follows:
in the second communication, the base station receives the radio frequency signal sent by the relay station, the radio frequency signal is processed by a conventional received signal and then is transmitted to the soft demodulator for soft demodulation processing to obtain bit reliability information, the soft network decoder is used for soft network decoding processing according to the bit reliability information, and the output is the bit reliability information of two user terminals; and then, carrying out iterative decoding by using the bit reliability information of the two user terminals received in the first communication, and after 3 or 4 times of iterative decoding, carrying out hard judgment according to the bit reliability information of each user terminal to obtain an actual bit value.
In the above-mentioned method, the first step of the method,
the iterative decoding is to realize mutual utilization of information between a soft network decoder and a channel decoder of two user terminals in an iterative mode;
the hard judgment is to judge the actual bit value according to the bit reliability information, and the judging method is to judge the actual bit value to be 0 if the log likelihood ratio of the bit reliability information is greater than zero, otherwise, the actual bit value is 1.
The invention also provides an uplink two-user relay transmission system, which comprises: a base station, a relay station; wherein,
the base station is used for respectively processing the two user data received for the first time, and informing the relay station to carry out the second communication when the processed two user data are determined not to be all correct;
and the relay station is used for carrying out soft network coding processing and soft modulation processing on the two processed user data stored after the first communication and sending the two processed user data to the base station.
In the above-mentioned system, the first and second sensors are arranged in a single circuit,
the system further comprises: at least two user terminals, which are used for processing user data when carrying out first communication and sending the processed user data to the relay station and the base station;
the base station is further used for receiving the user data of the next frame when the processed two user data are all correct;
and the base station is also used for performing soft demodulation processing and soft network decoding processing on the two user data received for the second time, and performing iterative decoding according to the two user data received twice after processing.
The base station respectively processes the two user data received for the first time, and informs the relay station to carry out the second communication when the two processed user data are determined not to be all correct; the relay station carries out soft network coding processing and soft modulation processing on the two processed user data stored after the first communication and sends the two processed user data to the base station, and because hard judgment and modulation are not carried out in the first communication, the introduction of noise caused by bit misjudgment caused by hard judgment in the traditional method is avoided; in addition, when the user data is incorrect, the retransmission of the user data is not carried out, but the second communication is carried out continuously, so that the bandwidth waste caused by the retransmission is avoided, and compared with the traditional method, the method has the advantages of low introduced noise and high transmission efficiency; because the invention adopts the soft modulation technology, compared with the direct transmission log-likelihood ratio, the invention has the advantage of flexible relation and is suitable for various modulation technologies.
Drawings
Fig. 1 is a schematic flow chart of a method for implementing uplink two-user relay transmission according to the present invention;
FIG. 2 is a schematic diagram of a first communication and a second communication of the present invention;
fig. 3 is a schematic diagram of a constellation mapping scheme according to 16-QAM according to an input bit value in the present invention;
fig. 4 is a schematic structural diagram of an uplink two-user relay transmission system implemented by the present invention.
Detailed Description
The basic idea of the invention is: the base station respectively processes the two user data received for the first time, and when the two processed user data are determined not to be all correct, the base station informs the relay station to carry out the second communication; the relay station performs soft network coding processing and soft modulation processing on the two processed user data stored after the first communication, and sends the two processed user data to the base station.
The invention is further described in detail below with reference to the drawings and the specific embodiments.
The present invention provides a method for uplink two-user relay transmission, fig. 1 is a schematic flow chart of a method for implementing uplink two-user relay transmission according to the present invention, and as shown in fig. 1, the method includes the following steps:
step 101, when carrying out first communication, two user terminals respectively process user data and send the processed user data to a relay station and a base station;
specifically, the two user terminals respectively process their own user data according to a conventional baseband signal processing process, and perform radio frequency end signal sending processing on the processed user data to obtain a radio frequency signal; fig. 2 is a schematic diagram of the first communication and the second communication according to the present invention, and as shown in fig. 2, when the first communication is performed, two user terminals finally transmit radio frequency signals obtained by processing user data to the relay station and the base station through radio waves;
the user data is divided into two parts, wherein the conventional baseband signal processing process of one part of the user data sequentially comprises adding a frame quality inspection sequence, channel coding, modulation, Single Carrier Frequency Division Multiple Access (SC-FDMA) transmission processing or Orthogonal Frequency Division Multiplexing (OFDM) transmission processing and the like; the conventional baseband signal processing process of the other part of user data is pilot insertion, SC-FDMA transmission processing or OFDM transmission processing, that is, a part of user data needs to be utilized separately for transmitting known data for the base station or the relay station to perform channel estimation;
the adding of the frame quality check sequence refers to inserting a sequence for checking the correctness of the user data into the user data, for example, the check sequence may be a Cyclic Redundancy Check (CRC) sequence, and a CRC module may be used to insert the CRC sequence into the user data; the channel coding means that a channel coding module of a user terminal performs special processing on user data, so that the processed data has error correction capability, and the user data subjected to the channel coding is an input bit value, for example, the channel coding may be a Low Density Parity Check Code (LDPC) or a turbo Code; the Modulation refers to a process of mapping a Modulation symbol in a constellation diagram pre-stored in a user terminal according to an input bit value obtained after channel coding, for example, the Modulation may be high-order Quadrature Amplitude Modulation (QAM), fig. 3 is a schematic diagram of a mapping manner according to an input bit value according to a constellation diagram of 16-QAM in the present invention, as shown in fig. 3, a Modulation symbol may be found from a constellation diagram of 16-QAM according to a mapping manner of a 16-QAM constellation diagram for every 4 input bit values; the pilot insertion means that a pilot processing module is used to insert part of known data into user data, so that a receiving end (base station and/or relay station) of the user data can perform channel estimation according to the inserted known data; the SC-FDMA transmission processing means that modulation symbols belonging to broadband signals are changed into orthogonal narrowband signals by utilizing inverse Fourier transform, and the orthogonal narrowband signals are used for resisting the influence caused by multipath fading and frequency division multiple access; the radio frequency end signal transmission processing refers to frequency conversion and amplification processing of a baseband signal to obtain a radio frequency signal for transmission, wherein the baseband signal is the user data which is finally subjected to SC-FDMA transmission processing or OFDM transmission processing.
102, the base station respectively processes the received two user data, judges whether the processed two user data are all correct or not, if not, executes step 103, and if yes, executes step 105;
specifically, the base station performs base station radio frequency end receiving processing and baseband signal processing on received radio frequency signals sent by two user terminals, thereby completing the processing process of conventionally receiving wireless signals, obtaining bit reliability information of the two user terminals, the buffer stores the bit reliability information, the base station judges whether the bit reliability information is all correct according to a frame quality check sequence added in user data, if all correct, step 105 is executed, and if at least one bit reliability information is incorrect, step 103 is executed;
the baseband signal processing comprises receiving processing, soft demodulation and soft decoding, and/or the baseband signal processing comprises receiving processing and channel estimation processing; the base station radio frequency end receiving processing refers to frequency conversion and amplification processing of radio frequency signals received from a user terminal; the receiving processing means that an SC-FDMA module or an OFDM module converts orthogonal narrow-band signals obtained after receiving processing into broadband signals by utilizing Fourier transform, and separates two user data so as to process the received user data respectively; the soft demodulation demodulator acquires a modulation symbol according to a received and processed radio frequency signal, and obtains bit reliability information corresponding to the modulation symbol by using the modulation symbol according to a corresponding relation between the pre-stored modulation symbol and the bit reliability information; the soft decoding means that the decoder performs an error correction process on the user data subjected to the encoding processing according to the bit reliability information input to the decoder, and outputs the corrected bit reliability information; the channel estimation processing refers to that a channel estimation module estimates channel characteristics according to the receiving condition of the inserted pilot frequency;
the method for the base station to judge whether the corrected bit reliability information is all correct according to the frame quality check sequence added in the user data is as follows: the CRC module of the base station checks the correctness of the processed user data of the two user terminals, i.e., the corrected bit reliability information, by using the frame quality check sequence inserted into the received user data, and the check method may be a cyclic redundancy check sequence check method.
Here, the procedure of receiving and processing the received user data of the user terminal by the relay station is the same as that of the base station, and the processing is ended after the bit reliability information obtained after the soft decoding processing is stored in the buffer, and the judgment is not performed any more.
103, the base station informs the relay station to perform the second communication, and the relay station performs soft network coding processing and soft modulation processing on the two processed user data stored after the first communication and sends the two processed user data to the base station;
specifically, the base station sends the signaling to the relay station through a downlink channel, so as to notify the relay station to perform the second communication, and then the base station enters a receiving state of the second communication; the downlink channel refers to a communication channel transmitted from the base station to the user terminal or the relay station;
after receiving the signaling fed back by the base station, the relay station performs soft network coding processing on the processed user data, i.e. bit reliability information, of the two user terminals stored in the buffer after the first communication, then inputs the user data into the soft modulator for soft modulation, and finally inputs the soft modulation value obtained after the soft modulation into the radio frequency end for generating a radio frequency signal, as shown in fig. 2, the relay station sends the radio frequency signal to the base station;
the soft network coding means that the network coding module carries out network coding according to the input bit reliability information, and the output bit reliability information is also the bit reliability information; the soft network coding is realized by performing the following calculation according to the log-likelihood ratio of the decoding output of the dual-purpose terminal: 1) adding the log-likelihood ratios of the two user terminals; 2) taking an index taking e as a base for the calculation result in the step 1) and adding 1; 3) respectively taking an index taking e as a base for the log-likelihood ratio of each user terminal and adding the results; 4) dividing the results of 2) and 3); 5) taking the logarithm taking e as the base for the result of 4); for example, the soft network coding process may utilize the formula:
wherein, L (U)1) And L (U)2) Respectively representing the decoded log-likelihood ratios of the user terminal 1 and the user terminal 2 received in the first communication of the relay station, and L (Z) is the log-likelihood ratio of the dual-purpose terminal after soft network coding; e is a constant equal to about 2.718;
the soft modulation means that a soft modulator of 16-QAM obtains an average value of a modulation symbol according to input bit reliability information, and the average value of the modulation symbol is used as the output of the soft modulator; the soft modulation is realized by the following steps: 1) obtaining probability values of 0 and 1 according to the input bit reliability information, wherein the probability value of 0 is the value obtained by dividing the index taking e as the base of the input bit reliability information by 1 and adding the index taking e as the base of the input bit reliability information, and the probability value of 1 is the probability value obtained by subtracting 0 from 1; 2) obtaining the probability value of the corresponding modulation symbol according to the mapping relation between the bit and the modulation symbol, and multiplying the obtained probability values of all the bits; 3) calculating the average value of the modulation symbols according to the probability value of the modulation symbols and the value of the modulation symbols, namely multiplying the values of all the modulation symbols by the corresponding probability values and then adding the values, and finally taking the average value of the modulation symbols as the output of the soft modulator; for example, the probability value may be calculated using the following formula:
wherein, L (z)j) Is zjBit log likelihood ratio of P (z)j0) and P (z)j1) are each zjProbability values of 0 and 1;
the probability value of a modulation symbol can be calculated using the following formula:
wherein, P (y ═ s)i) For modulation symbols y as modulation symbols siThe value range of the probability value i is 0 to M-1;
the average value of the modulation symbols can be calculated using the following formula:
wherein E (y) is the output value of the soft modulator;
as shown in fig. 3, the modulation symbol received by the relay station is shown as point a in the figure, decoding is performed according to the received modulation symbol to obtain an upgraded log-likelihood ratio, then a modulation symbol is soft-demodulated according to the log-likelihood ratio, the modulation symbol is shown as point B in the figure, and then the modulation symbol after soft-demodulation is directly sent to a channel; generally, the upgraded modulation symbol is closer to the actually transmitted modulation symbol than the modulation symbol before decoding, which is equivalent to that the equivalent channel noise variance becomes smaller, that is, compared with the conventional direct forwarding scheme, the scheme only sends the very small noise variance in the first hop to the second hop, and compared with the conventional scheme which performs upgrading as well, because the modulation is not performed after hard judgment, and whether the decoded user data is correct or not is not determined, the defects that the wrong user data cannot be continuously forwarded, and the noise is amplified due to hard judgment are avoided.
104, the base station performs soft demodulation processing and soft network decoding processing on the two user data received for the second time, and performs iterative decoding according to the two user data received twice after processing;
specifically, in the second communication, the base station receives a radio frequency signal sent by the relay station, the radio frequency signal is processed by a conventional received signal and then is transmitted to the soft demodulator for soft demodulation to obtain bit reliability information, soft network decoding processing is performed by using a soft network decoder according to the bit reliability information, the output bit reliability information of the two user terminals is also output, then iterative decoding is performed by using the bit reliability information of the two user terminals received in the first communication, and after 3 or 4 iterative decoding, hard judgment is performed according to the bit reliability information of each user terminal to obtain an actual bit value;
the soft network decoding is similar to the soft network coding process, and only the bit reliability information of a user terminal in the soft network coding is converted into the bit reliability information output by soft demodulation; the iterative decoding means that mutual utilization of information is realized between a soft network decoder and channel decoders of two user terminals in an iterative manner, so that the decoding process of the overall performance is improved; the hard judgment refers to judging an actual bit value according to the bit reliability information, and the judging method is that if the log likelihood ratio of the bit reliability information is greater than zero, the actual bit value is 0, otherwise, the actual bit value is 1;
for example, as shown in fig. 4, the iterative decoding process first extracts the bit likelihood ratio L (U) of the user terminal 1 at the time of the first communication from the buffer1) Setting the soft network decoding output value of the user terminal 1 of the first iteration as 0, adding the two values, sending the sum to a channel decoder module of the user terminal 1 for decoding, subtracting the soft network decoding output value of the user terminal 1 from the log-likelihood ratio output by the decoder to obtain the external information generated by the user terminal 1, sending the external information to a soft network decoder of the user terminal 2 for decoding, wherein the decoding process is carried out according to the following formula:
wherein, L (U'1) L (z) is the log-likelihood ratio of the soft demodulation of the second communication base station for the extrinsic information generated by the user terminal 1.
And adding the log-likelihood ratio output by the soft network decoding of the user terminal 2 and the log-likelihood ratio obtained by the first communication of the user terminal 2 taken out from the buffer, sending the sum to a channel decoder of the user terminal 2 for decoding, and similarly, subtracting the soft network decoding value of the user terminal 2 from the output value of the decoder to be used as the input value of the soft network decoder of the user terminal 1, so that the soft network decoding of the user terminal 1 completes one round of iteration, and thus, continuous iteration is formed repeatedly.
In step 105, the base station receives user data of the next frame.
To implement the above method, the present invention further provides an uplink two-user relay transmission system, fig. 4 is a schematic structural diagram of the uplink two-user relay transmission system implemented by the present invention, and as shown in fig. 4, the system includes: base station 41, relay station 42; wherein,
the base station 41 is configured to process the two pieces of user data received for the first time, and notify the relay station 42 to perform the second communication when it is determined that the two pieces of user data processed are not all correct;
the relay station 42 is configured to perform soft network coding processing and soft modulation processing on the two processed user data stored after the first communication, and send the two processed user data to the base station 41.
The system further comprises: at least two user terminals 43, configured to process user data during first communication, and send the processed user data to the relay station 41 and the base station 42;
the base station 41 is further configured to receive user data of a next frame when it is determined that all of the processed two user data are correct;
the base station 41 is further configured to perform soft demodulation processing and soft network decoding processing on the two user data received for the second time, and perform iterative decoding according to the two user data received twice after processing.
The two user terminals 43 process the user data respectively, and send the processed user data to the relay station 41 and the base station 42: the two user terminals respectively process own user data according to a conventional baseband signal processing process, perform radio frequency end signal sending processing on the processed user data to obtain radio frequency signals, and send the radio frequency signals obtained after the user data processing to the relay station and the base station through radio waves; the conventional baseband signal processing process is as follows: adding frame quality check sequence, channel coding, modulation, transmission processing, and/or conventional baseband signal processing to the pilot insertion, transmission processing.
The base station 41 respectively processes the two user data received for the first time as follows: the base station carries out base station radio frequency end receiving processing and baseband signal processing on the received radio frequency signals sent by the two user terminals to obtain bit reliability information of the two user terminals, the buffer stores the bit reliability information, and the base station judges whether the bit reliability information is all correct according to a frame quality check sequence added in user data; the baseband signal processing is receiving processing, soft demodulation, soft decoding, and/or the baseband signal processing is receiving processing and channel estimation processing.
The relay station 42 performs soft network coding processing and soft modulation processing on the two processed user data stored after the first communication, and sends the two processed user data to the base station 41: after receiving the signaling fed back by the base station, the relay station performs soft network coding processing on the processed user data of the two user terminals stored in the buffer after the first communication, inputs the user data into the soft modulator for soft modulation, and finally inputs the soft modulation value obtained after the soft modulation into the radio frequency end, and the radio frequency end generates a radio frequency signal and sends the radio frequency signal to the base station.
The soft network coding is that the network coding module carries out network coding according to the input bit reliability information, namely the processed two user terminals, and the output bit reliability information is also output; the soft modulation is that the soft modulator obtains the average value of modulation symbols according to the input bit reliability information, and the average value of the modulation symbols is used as the output of the soft modulator.
The base station 41 performs soft demodulation processing and soft network decoding processing on the two user data received for the second time, and performs iterative decoding according to the two user data received twice after processing, as follows: in the second communication, the base station receives the radio frequency signal sent by the relay station, the radio frequency signal is processed by a conventional received signal and then is transmitted to the soft demodulator for soft demodulation processing to obtain bit reliability information, the soft network decoder is used for soft network decoding processing according to the bit reliability information, and the output is the bit reliability information of two user terminals; and then, carrying out iterative decoding by using the bit reliability information of the two user terminals received in the first communication, and after 3 or 4 times of iterative decoding, carrying out hard judgment according to the bit reliability information of each user terminal to obtain an actual bit value.
The iterative decoding is to realize mutual utilization of information between a soft network decoder and a channel decoder of two user terminals in an iterative mode; the hard judgment is to judge the actual bit value according to the bit reliability information, and the judging method is to judge the actual bit value to be 0 if the log likelihood ratio of the bit reliability information is greater than zero, otherwise, the actual bit value is 1.
The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, and any modifications, equivalents, improvements, etc. that are within the spirit and principle of the present invention should be included in the present invention.
Claims (12)
1. An uplink two-user relay transmission method is characterized by comprising the following steps:
the base station respectively processes the two user data received for the first time, and when the two processed user data are determined not to be all correct, the base station informs the relay station to carry out the second communication;
the relay station performs soft network coding processing and soft modulation processing on the two processed user data stored after the first communication, and sends the two processed user data to the base station.
2. The method of claim 1, wherein before the base station processes the first two pieces of user data, the method further comprises:
when the first communication is carried out, the two user terminals process the user data respectively and send the processed user data to the relay station and the base station.
3. The method of claim 2, wherein the two user terminals each process user data and send the processed user data to the relay station and the base station is:
the two user terminals respectively process own user data according to a conventional baseband signal processing process, perform radio frequency end signal sending processing on the processed user data to obtain radio frequency signals, and send the radio frequency signals obtained after the user data processing to the relay station and the base station through radio waves; the conventional baseband signal processing process is as follows: adding frame quality check sequence, channel coding, modulation, transmission processing, and/or conventional baseband signal processing to the pilot insertion, transmission processing.
4. The method of claim 1, wherein after the base station processes the first two user data, the method further comprises:
and when the processed two user data are all correct, the base station receives the user data of the next frame.
5. The method of claim 1, further comprising:
and the base station performs soft demodulation processing and soft network decoding processing on the two user data received for the second time, and performs iterative decoding according to the two user data received for the two times after processing.
6. The method of claim 1, wherein the base station processes the first two user data received respectively as:
the base station carries out base station radio frequency end receiving processing and baseband signal processing on the received radio frequency signals sent by the two user terminals to obtain bit reliability information of the two user terminals, the buffer stores the bit reliability information, and the base station judges whether the bit reliability information is all correct according to a frame quality check sequence added in user data; the baseband signal processing is receiving processing, soft demodulation, soft decoding, and/or the baseband signal processing is receiving processing and channel estimation processing.
7. The method of claim 1, wherein the relay station performs soft network coding and soft modulation on the processed two user data stored after the first communication, and sends the two user data to the base station:
after receiving the signaling fed back by the base station, the relay station performs soft network coding processing on the processed user data of the two user terminals stored in the buffer after the first communication, inputs the user data into the soft modulator for soft modulation, and finally inputs the soft modulation value obtained after the soft modulation into the radio frequency end, and the radio frequency end generates a radio frequency signal and sends the radio frequency signal to the base station.
8. The method of claim 7,
the soft network coding is that the network coding module carries out network coding according to the input bit reliability information, namely the processed two user terminals, and the output bit reliability information is also output;
the soft modulation is that the soft modulator obtains the average value of modulation symbols according to the input bit reliability information, and the average value of the modulation symbols is used as the output of the soft modulator.
9. The method of claim 5, wherein the base station performs soft demodulation and soft network decoding on the second received two user data, and performs iterative decoding according to the two processed user data received twice as follows:
in the second communication, the base station receives the radio frequency signal sent by the relay station, the radio frequency signal is processed by a conventional received signal and then is transmitted to the soft demodulator for soft demodulation processing to obtain bit reliability information, the soft network decoder is used for soft network decoding processing according to the bit reliability information, and the output is the bit reliability information of two user terminals; and then, carrying out iterative decoding by using the bit reliability information of the two user terminals received in the first communication, and after 3 or 4 times of iterative decoding, carrying out hard judgment according to the bit reliability information of each user terminal to obtain an actual bit value.
10. The method of claim 9,
the iterative decoding is to realize mutual utilization of information between a soft network decoder and a channel decoder of two user terminals in an iterative mode;
the hard judgment is to judge the actual bit value according to the bit reliability information, and the judging method is to judge the actual bit value to be 0 if the log likelihood ratio of the bit reliability information is greater than zero, otherwise, the actual bit value is 1.
11. An uplink two-user relay transmission system, comprising: a base station, a relay station; wherein,
the base station is used for respectively processing the two user data received for the first time, and informing the relay station to carry out the second communication when the processed two user data are determined not to be all correct;
and the relay station is used for carrying out soft network coding processing and soft modulation processing on the two processed user data stored after the first communication and sending the two processed user data to the base station.
12. The system of claim 11,
the system further comprises: at least two user terminals, which are used for processing user data when carrying out first communication and sending the processed user data to the relay station and the base station;
the base station is further used for receiving the user data of the next frame when the processed two user data are all correct;
and the base station is also used for performing soft demodulation processing and soft network decoding processing on the two user data received for the second time, and performing iterative decoding according to the two user data received twice after processing.
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