CN112787733A - Bidirectional relay scheme self-adaptive selection method, system, storage medium and terminal - Google Patents
Bidirectional relay scheme self-adaptive selection method, system, storage medium and terminal Download PDFInfo
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Abstract
The invention provides a method, a system, a storage medium and a terminal for self-adaptive selection of a bidirectional relay scheme, which comprise the following steps: comparing the receiving signal-to-noise ratio of the near-end equipment with a signal-to-noise ratio threshold value; when the receiving signal-to-noise ratio of the near-end equipment is smaller than a signal-to-noise ratio threshold value, selecting a first bidirectional relay scheme, enabling the far-end equipment and the near-end equipment to transmit communication signals by adopting an orthogonal multiple access technology in an uplink, and enabling the relay to distribute the communication signals by adopting a network coding technology in a downlink; and when the receiving signal-to-noise ratio of the near-end equipment is not less than the signal-to-noise ratio threshold value, selecting a second bidirectional relay scheme, enabling the far-end equipment and the near-end equipment to transmit communication signals by adopting a non-orthogonal multiple access technology in an uplink, and enabling the relay to distribute the communication signals by adopting a network coding technology in a downlink. The self-adaptive selection method, the self-adaptive selection system, the storage medium and the terminal of the bidirectional relay scheme can realize the optimal performance of the system by switching the bidirectional relay scheme.
Description
Technical Field
The present invention relates to the field of wireless communications technologies, and in particular, to a method, a system, a storage medium, and a terminal for adaptive selection of a bidirectional relay scheme.
Background
The bidirectional relay is a very classic network topology structure in a communication system, and can effectively expand the coverage of a wireless network and resist the influence of multipath fading through the cooperation between terminal equipment and the relay. In a conventional bi-directional relay scheme, Orthogonal Multiple Access (OMA) technology is used for uplink data transmission. However, with the explosive increase of the number of user terminals and the demand of data traffic, higher requirements are put on the spectrum efficiency and the transmission rate in the next generation wireless network. Non-Orthogonal Multiple Access (NOMA) technology is therefore receiving great attention in both academic and industrial areas. Compared with the orthogonal multiple access technology, the non-orthogonal multiple access system allows the devices to use the same time-frequency resource for transmission, and the specific method is that a Superposition Coding (SC) technology is adopted at a transmitter, so that signal data of a plurality of terminal devices with different channel states are superposed. The receiver may use a Successive Interference Cancellation (SIC) algorithm to sequentially detect signal data of different terminal devices. Therefore, the non-orthogonal multiple access technique is superior to the conventional orthogonal multiple access technique in performance such as spectrum efficiency and system capacity, and has become one of the key candidate techniques in the next generation mobile communication system.
On the other hand, Network Coding (NC) is a breakthrough technology in the field of communications, and changes the traditional relay communication mode of store-and-forward. Compared with the downlink orthogonal multiple access technology, the network coding introduces the coding and decoding operation of the information flow at the relay node of the network, and then sends the signals in a downlink mode in a multicast mode, so that the bandwidth utilization rate and the network throughput are effectively improved. And moreover, due to lossless information compression gain caused by exclusive-or (XOR) operation, the network coding technology can effectively balance network load and increase network robustness. Therefore, the network coding technique has a significantly superior suppression of error propagation compared to non-orthogonal multiple access techniques.
Therefore, if the advantages of the non-orthogonal multiple access technique and the network coding technique can be combined, the performance of the next generation bidirectional relay scheme (i.e., the NOMA-NC bidirectional relay scheme) will be further enhanced. However, the biggest challenge faced by non-orthogonal multiple access techniques is the error propagation effect caused by inter-user interference at low signal-to-noise ratios. The performance of the NOMA-NC two-way relay scheme may not necessarily be better than the conventional two-way relay scheme. Therefore, how to flexibly select a bidirectional relay scheme so as to enable the performance of the bidirectional relay system to reach the optimal current state is an urgent problem to be solved at present.
In addition, the system model of the NOMA-NC bidirectional relay is improved on the basis of the original traditional bidirectional relay, and has the potential of further improving the optimal performance of the conventional bidirectional relay system. In order to be able to exploit this potential fully, flexible signal data transmission methods also need to be designed. The principle of the non-orthogonal multiple access technology is to pair two users with sufficiently large channel state difference, so as to reduce the interference between users as much as possible by regarding the signal of the far-end user as the noise when the receiving end decodes the signal of the near-end user, thereby obtaining the gains of spectral efficiency and throughput. Then, considering the adaptive modulation and coding technique of the actual wireless communication system, different modulation schemes need to be allocated to two NOMA devices having a large difference in channel state to ensure maximization of the channel utilization rate. Due to the frame structure mechanism of the wireless communication system, information sequences sent by two NOMA devices in the bidirectional relay need to meet the requirement of the same sequence length to realize information transmission in the same resource. That is, for uplink non-orthogonal multiple access transmission in NOMA-NC two-way relay, it should be ensured that the symbol sequences transmitted by the two devices maintain the same length. Therefore, for two devices with different modulation schemes, different transmission bit sequences need to be designed for the two devices, so that the sequence lengths of the two bit sequences modulated into the two symbol sequences are kept consistent. However, at the relay node, the relay needs to perform exclusive OR (XOR) operation on the bit sequences transmitted by the two devices, and this operation requires that the bit sequences of the two devices have the same length, thereby causing the problem of mismatch between the lengths of the uplink and downlink information sequences. The transmission methods for solving the problem currently include a Bit-match (Bit-match) method and a Symbol-match (Symbol-match) method. Therefore, how to formulate a flexible signal transmission method in the NOMA-NC bidirectional relay scheme and guarantee the performance of the far-end equipment and the near-end equipment is a problem to be solved urgently at present.
Disclosure of Invention
In view of the foregoing drawbacks of the prior art, an object of the present invention is to provide a method, a system, a storage medium, and a terminal for adaptively selecting a bidirectional relay scheme, which can freely switch the bidirectional relay scheme according to different application scenario requirements, so as to achieve the optimal performance of the system.
In order to achieve the above objects and other related objects, the present invention provides a method for adaptively selecting a bidirectional relay scheme, which is applied to a bidirectional relay system, where the bidirectional relay system includes a far-end device, a near-end device, and a relay; the self-adaptive selection method of the bidirectional relay scheme comprises the following steps: comparing the received signal-to-noise ratio of the near-end equipment with a signal-to-noise ratio threshold value; when the receiving signal-to-noise ratio of the near-end equipment is smaller than a signal-to-noise ratio threshold value, selecting the first bidirectional relay scheme, enabling the far-end equipment and the near-end equipment to transmit communication signals by adopting an orthogonal multiple access technology in an uplink, and enabling the relay to distribute the communication signals by adopting a network coding technology in a downlink; in the first bidirectional relay scheme, the far-end device and the near-end device send frequency domain signal streams on different time-frequency resources; when the receiving signal-to-noise ratio of the near-end equipment is not smaller than the signal-to-noise ratio threshold value, selecting the second bidirectional relay scheme, enabling the far-end equipment and the near-end equipment to adopt a non-orthogonal multiple access technology to send communication signals in an uplink, and enabling the relay to adopt a network coding technology to distribute the communication signals in a downlink; and in the second bidirectional relay scheme, the far-end equipment and the near-end equipment adopt a bit matching transmission method or a symbol matching transmission method to transmit frequency domain signal streams on the same time frequency resource.
In an embodiment of the present invention, the received signal-to-noise ratio of the near-end device is calculated by dividing the product of the channel mode value and the transmission power of the near-end device by the additive noise; the snr threshold is a received snr of the near-end device when system throughputs of the first and second bi-directional relay schemes are the same in a gaussian channel.
In an embodiment of the present invention, when the second bidirectional relay scheme is selected, when a channel state value of a transmission channel of the far-end device is smaller than a state threshold value, the far-end device and the near-end device use a bit matching transmission method; and when the channel state value of the transmission channel of the far-end equipment is not less than the state threshold value, the far-end equipment and the near-end equipment adopt a symbol matching transmission method.
In an embodiment of the present invention, the channel state value of the remote device is a channel module value of the remote device, and the state threshold value is a channel state value corresponding to the target block error rate reached by the remote device in the gaussian channel.
In an embodiment of the present invention, when the bit matching transmission method is adopted, the far-end device and the near-end device are enabled to transmit the transmission bit sequences with the same length, and after the two transmission bit sequences are modulated into the symbol sequences, zero padding is performed on the symbol sequences with smaller length, so that the lengths of the two symbol sequences are equal; after the two decoded bit sequences are detected and decoded at the relay, the relay performs exclusive-or operation on the two decoded bit sequences to combine the two decoded bit sequences into one decoded bit sequence, and modulates the decoded bit sequence into a symbol sequence to perform signal transmission at a downlink.
In an embodiment of the present invention, when the symbol matching transmission method is adopted, the far-end device and the near-end device are enabled to transmit the transmission bit sequences with different lengths, it is ensured that the lengths can be aligned after the two transmission bit sequences are modulated into the symbol sequences, and then signal superposition is directly performed to complete non-orthogonal transmission; after detecting and decoding two decoding bit sequences at the relay, the relay makes zero padding on the decoding bit sequence with smaller length to make the two decoding bit sequences have equal length, and makes exclusive-or operation on the two decoding bit sequences with equal length to combine into a bit sequence, and then modulates the bit sequence into a symbol sequence to send signals at downlink.
Correspondingly, the invention provides a two-way relay scheme self-adaptive selection system, which is applied to a two-way relay system, wherein the two-way relay system comprises a far-end device, a near-end device and a relay;
the bidirectional relay scheme self-adaptive selection system comprises a comparison module, a first selection module and a second selection module;
the comparison module is used for comparing the receiving signal-to-noise ratio of the near-end equipment with a signal-to-noise ratio threshold value;
the first selection module is configured to select the first bidirectional relay scheme when a received signal-to-noise ratio of the near-end device is smaller than a signal-to-noise ratio threshold value, so that the far-end device and the near-end device transmit a communication signal by using an orthogonal multiple access technology in an uplink, and the relay distributes the communication signal by using a network coding technology in a downlink; in the first bidirectional relay scheme, the far-end device and the near-end device send frequency domain signal streams on different time-frequency resources;
the second selection module is configured to select the second bidirectional relay scheme when the received signal-to-noise ratio of the near-end device is not less than the signal-to-noise ratio threshold value, so that the far-end device and the near-end device transmit a communication signal in an uplink by using a non-orthogonal multiple access technology, and the relay distributes the communication signal in a downlink by using a network coding technology; and in the second bidirectional relay scheme, the far-end equipment and the near-end equipment adopt a bit matching transmission method or a symbol matching transmission method to transmit frequency domain signal streams on the same time frequency resource.
The present invention provides a storage medium having stored thereon a computer program, characterized in that the program, when executed by a processor, implements the above-described bidirectional relay scheme adaptive selection method.
The invention provides a bidirectional relay scheme self-adaptive selection terminal, which comprises: a processor and a memory;
the memory is used for storing a computer program;
the processor is configured to execute the computer program stored in the memory, so as to enable the terminal to execute the above-mentioned bidirectional relay scheme adaptive selection method.
Finally, the invention provides a bidirectional relay scheme self-adaptive selection system, which comprises the bidirectional relay scheme self-adaptive selection terminal and a bidirectional relay system;
the bidirectional relay system comprises a far-end device, a near-end device and a relay, and is used for executing an adaptive bidirectional relay scheme under the control of the bidirectional relay scheme adaptive selection terminal.
As described above, the bidirectional relay scheme adaptive selection method, system, storage medium, and terminal of the present invention have the following beneficial effects:
(1) the bidirectional relay scheme adaptive to the application scene can be selected based on the preset selection standard, so that the correct transmission probability maximization of the transmission communication signals of the whole bidirectional relay system, the far-end equipment and the near-end equipment is realized, and the throughput of the system and the equipment end is improved;
(2) the method has good compatibility with a bidirectional relay scheme in the prior art, and can be directly applied to the existing bidirectional relay system, so that the system throughput performance is improved;
(3) the method can ensure that the bidirectional relay system can achieve excellent system performance under any signal-to-noise ratio condition, and has good adaptability to next-generation bidirectional relay communication.
(4) The self-adaptive switching of the bit matching method and the symbol matching method has excellent flexibility, and the gain of the far-end equipment and the gain of the near-end equipment in the bidirectional relay system can be dynamically switched, so that the communication rate of the far-end equipment can be ensured under a poor channel environment, and the fairness of users can be improved; and the performance of the bidirectional relay system can be maximized by improving the communication rate of the near-end equipment under a better channel environment.
Drawings
FIG. 1 is a flow chart illustrating a method for adaptive selection of a bi-directional relay scheme in accordance with an embodiment of the present invention;
FIG. 2 is a diagram illustrating an uplink scenario of a conventional bi-directional relay scheme in one embodiment;
FIG. 3 is a diagram illustrating a downlink scenario in one embodiment for a conventional bidirectional relay scheme and a NOMA-NC bidirectional relay scheme;
FIG. 4 is a diagram illustrating an uplink scenario in one embodiment of a NOMA-NC bi-directional relay scheme;
FIG. 5 is a schematic diagram illustrating an implementation of a Bit-match transmission method in an embodiment;
FIG. 6 is a schematic diagram of an implementation of the Symbol-match transmission method in an embodiment;
FIG. 7 is a schematic diagram of an adaptive selection system for bi-directional relay scheme in one embodiment of the invention;
fig. 8 is a diagram illustrating adaptive terminal selection for a bi-directional relay scheme according to an embodiment of the present invention;
fig. 9 is a schematic diagram of the adaptive selection system for bi-directional relay scheme according to another embodiment of the present invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
The adaptive selection method, the adaptive selection system, the storage medium and the terminal of the bidirectional relay scheme can adaptively select the adaptive bidirectional relay scheme according to different application scene requirements, and the maximization of the system performance is ensured. The bidirectional relay system comprises a far-end device, a near-end device and a relay. The remote equipment is far away from the relay, and the channel state is poor; the near-end equipment is closer to the relay, and the channel state is better.
As shown in fig. 1, in an embodiment, the adaptive selection method for a bidirectional relay scheme of the present invention is applied to a bidirectional relay system, and specifically includes the following steps:
and step S1, comparing the received signal-to-noise ratio of the near-end equipment with a signal-to-noise ratio threshold value.
Specifically, when bidirectional relaying is required, a bidirectional relaying scheme needs to be selected first. The two-way relay scheme in the present invention includes the following two:
one, conventional two-way relay scheme, i.e. the first two-way relay scheme
The first bidirectional relay scheme specifically includes the following steps:
a) and according to the configuration information, the far-end equipment a and the near-end equipment b send frequency domain signal streams on different time frequency resources.
As shown in fig. 2, in the uplink of the conventional bidirectional relay scheme, the relay received signal is represented as
Wherein p isaIs the transmit power, p, of the remote device abIs the transmit power of the near end device b, haIs the channel state value, h, of the remote device abIs the channel state value of the near-end device b, and the symbol sequences transmitted by the far-end device a and the near-end device b are respectively used as saAnd sbIs represented by the transmitted bit sequence x of the far-end device a and the near-end device b, respectivelyaAnd xbBy channel codingCode and signal modulation. n isaAnd nbRespectively representing the additive white noise at the a end of the far-end equipment and the b end of the near-end equipment.
b) The relay decodes the received signal to decode the bit sequences of the far-end device a and the near-end device b respectively.
The detection signal of the terminal device can be expressed as:
wherein
Is the detection signal of the terminal device i at the relay point, where i ∈ { a, b }. GiIs the equalization coefficient of terminal device i. The relay respectively obtains the decoding bit sequences of the far-end equipment a and the near-end equipment b by carrying out signal demodulation and channel decoding on the detection signal
And
c) relaying decoded bit sequences for far-end device a and near-end device b
And
an XOR encoding operation is performed and the network encoded signal is transmitted in a multicast form on the downlink.
Two paths of data are relayed
And
performing XOR operation to make it become a path of data, which is called network coding bit sequence and can be expressed as:
the relay then modulates the network coded bit sequence X into a network coded signal S' and transmits it in a multicast fashion, as shown in fig. 3. The signal received by the terminal device may be represented as:
wherein p'aAnd p'bThe transmission power of the far-end device a and the near-end device b in the downlink are respectively.
d) The far-end equipment a and the near-end equipment b respectively decode the network coding signals transmitted by the relay at the respective receiving ends and transmit the network coding signals with the own transmission bit sequence xaAnd xbAnd performing XOR operation to obtain the sending information data of the other party.
For the remote device a, the detection signal at the receiving end can be expressed as
Wherein
Is the detection signal of the a end of the remote device. A decoded bit sequence obtained by signal demodulation and channel decoding is
For terminal b, the detection signal of its receiving end can be expressed as
Wherein
Is a detection signal at the b end of the near-end equipment. A decoded bit sequence obtained by signal demodulation and channel decoding is
Finally, the far-end device a and the near-end device b perform XOR operation on the respective transmission bit sequence and the detected bit sequence, that is:
the far-end equipment a and the near-end equipment b finally receive the transmitted information data of the opposite side
And
thus, the two-way relay communication process of the far-end device a and the near-end device b is smoothly completed.
Two, NOMA-NC two-way relay scheme, i.e., the second two-way relay scheme.
The second bidirectional relay scheme specifically includes the following steps:
A) the remote equipment a and the near-end equipment b select any one transmission method of Bit-match or Symbol-match for transmission, and according to the configuration parameters, the remote equipment a and the near-end equipment b send frequency domain signal streams on the same time frequency resource.
As shown in FIG. 4, in the uplink of the NOMA-NC bi-directional relay scheme, the relay received signal is represented as
Wherein p isaIs the transmit power, p, of the remote device abIs the transmit power of the near end device b, haIs the channel state, h, of the remote device abIs the channel state of the near-end device b, and the symbol sequences transmitted by the far-end device a and the near-end device b are respectively used as saAnd sbTo represent saAnd sbTransmitting bit sequences x by a far-end device a and a near-end device b, respectivelyaAnd xbBy channel coding and signal modulation. n represents additive white noise. Such asIf the Bit-match transmission method is adopted, the near-end device b needs to perform 0 complementing operation on the transmitted symbol sequence, so that the length of the symbol sequence is equal to that of the terminal device a, as shown in fig. 5.
B) The relay performs SIC decoding processing on the received signal, and sequentially acquires the decoding bit sequences of the near-end device b and the terminal device a.
The relay firstly decodes the detection signal of the near-end device b with better channel state, namely
Wherein
Is the detection signal of the near-end device b at the relay point, GbIs the equalization coefficient of the near-end device b; then the relay point subtracts the detection signal of the near-end device b from the received signal, and continues to detect the signal of the far-end device a to obtain
Wherein
Is the detection signal of the remote device a at the relay point, GaIs the equalization coefficient of the remote device a; finally, the relay respectively obtains the decoding bit sequences of the terminal equipment a and the terminal equipment b through signal demodulation and channel decoding
And
C) relaying decoded bit sequences for far-end device a and near-end device b
And
an XOR encoding operation is performed and the network encoded signal is transmitted in a multicast form on the downlink.
Relay station
And
an XOR operation is performed to make it become a path of data, which is said to be a network coded bit sequence, and can be expressed as:
if the Symbol-match transmission method is adopted by the NOMA-NC two-way relay system, the decoded bit sequence of the far-end device a needs to be padded with zero before encoding, so that the decoded bit sequence of the far-end device a and the decoded bit sequence of the near-end device b can perform a complete XOR operation, as shown in fig. 6.
The relay then modulates the network coded bit sequence X into a network coded signal S' and transmits it in a multicast fashion, as shown in fig. 3. The signals received by the remote device a and the remote device b can be expressed as:
wherein p'aAnd p'bThe transmission power of the remote device a and the remote device b in the downlink are respectively.
D) The remote device a and the remote device b decode the network coding signal transmitted by the relay at the respective receiving ends respectively, and then the network coding signal and the transmission bit sequence x of the remote device a and the remote device b are transmittedaAnd xbAnd performing XOR operation to obtain the sending information data of the other party.
For terminal a, the detection signal of its receiving end can be expressed as
Wherein
Is the detection signal of the a end of the remote device. A decoded bit sequence obtained by signal demodulation and channel decoding is
For terminal b, the detection signal of its receiving end can be expressed as
Wherein
Is a detection signal at the b end of the near-end equipment. A decoded bit sequence obtained by signal demodulation and channel decoding is
Finally, the far-end device a and the near-end device b transmit their respective bit sequences xaAnd xbAnd performing XOR operation with the detected bit sequence, namely:
the far-end device a and the near-end device b finally receive the transmission information data of the other party
And
thus, the two-way relay communication process of the far-end device a and the near-end device b is smoothly completed.
Preferably, under the NOMA-NC bidirectional relay scheme, the near-end device b has a better channel state, and adopts a higher-order modulation mode Quadrature Phase Shift Keying (QPSK) modulation; the channel state of the remote device a is poor, and Binary Phase Shift Keying (BPSK) modulation is adopted in a lower-order modulation mode. The far-end equipment a and the near-end equipment b adopt a Turbo channel coding technology to code information bits, the code rate is 1/3, and adopt an OFDM technology to send frequency domain signal streams. The uplink parameter configuration of the conventional bidirectional relay scheme is the same as described above.
In an embodiment of the present invention, the received signal-to-noise ratio of the near-end device is calculated by dividing the product of the channel mode value and the transmission power of the near-end device by the additive noise; the snr threshold is a received snr of the near-end device when system throughputs of the first and second bi-directional relay schemes are the same in a gaussian channel. Therefore, it is determined which bi-directional relay scheme to select by comparing the received signal-to-noise ratio of the near-end device with the signal-to-noise ratio threshold.
Step S2, when the received signal-to-noise ratio of the near-end device is smaller than the signal-to-noise ratio threshold, selecting the first bidirectional relay scheme, so that the far-end device and the near-end device transmit the communication signal by using the orthogonal multiple access technology in the uplink, and the relay distributes the communication signal by using the network coding technology in the downlink; in the first bidirectional relay scheme, the far-end device and the near-end device transmit frequency domain signal streams on different time frequency resources.
Specifically, when the received signal-to-noise ratio of the near-end device is smaller than a signal-to-noise ratio threshold value, the far-end device and the near-end device are caused to communicate by using a first bidirectional relay scheme. Wherein, under the first bidirectional relay scheme, the far-end device and the near-end device transmit communication signals by adopting an orthogonal multiple access technology in an uplink, and the relay distributes the communication signals by adopting a network coding technology in a downlink.
Step S3, when the received signal-to-noise ratio of the near-end device is not less than the signal-to-noise ratio threshold, selecting the second bidirectional relay scheme, so that the far-end device and the near-end device transmit communication signals in an uplink by using a non-orthogonal multiple access technology, and the relay distributes the communication signals in a downlink by using a network coding technology; and in the second bidirectional relay scheme, the far-end equipment and the near-end equipment adopt a bit matching transmission method or a symbol matching transmission method to transmit frequency domain signal streams on the same time frequency resource.
Specifically, when the received signal-to-noise ratio of the near-end device is not less than the signal-to-noise ratio threshold value, the far-end device and the near-end device are caused to communicate by using a second bidirectional relay scheme, that is, a NOMA-NC bidirectional relay scheme is used. Wherein, under the NOMA-NC two-way relay scheme, the relay distributes communication signals on the downlink by adopting a network coding technology.
Under the NOMA-NC bidirectional relay scheme, a bit matching transmission method or a symbol matching transmission method may be employed. Wherein the selection of the transmission method is determined by a channel state value of a transmission channel of the remote device. In an embodiment of the present invention, when a channel state value of a transmission channel of the far-end device is smaller than a state threshold value, the far-end device and the near-end device use a bit matching transmission method; and when the channel state value of the transmission channel of the far-end equipment is not less than the state threshold value, the far-end equipment and the near-end equipment adopt a symbol matching transmission method. The channel state value of the remote device adopts a channel module value of the remote device, and the state threshold value adopts a channel state value corresponding to the situation that the remote device reaches a target block error rate under a Gaussian channel.
In an embodiment of the present invention, when the bit matching transmission method is adopted, the far-end device and the near-end device are made to transmit the transmission bit sequences with the same length, so as to obtain a higher rate of the far-end device; modulating the two transmitted bit sequences into symbol sequences, and then performing zero filling on the symbol sequences with smaller lengths to ensure that the lengths of the two symbol sequences are equal; after the two decoded bit sequences are detected and decoded at the relay, the relay performs exclusive-or operation on the two decoded bit sequences to combine the two decoded bit sequences into one decoded bit sequence, and modulates the decoded bit sequence into a symbol sequence to perform signal transmission at a downlink. As in the embodiment shown in figure 5 of the drawings,
and
the transmit bits of the far-end device a and the near-end device b respectively,
and
the transmit symbols for far end device a and near end device b respectively,
and
the decoding bits of the far-end device a and the near-end device b are respectively, and M and N are the number of the transmission bits and the transmission symbols of the terminal device respectively.
In an embodiment of the present invention, when the symbol matching transmission method is adopted, the far-end device and the near-end device are enabled to transmit the transmission bit sequences with different lengths, it is ensured that the lengths can be aligned after the two transmission bit sequences are modulated into the symbol sequences, and then signal superposition is directly performed to complete non-orthogonal transmission; after detecting and decoding two decoding bit sequences at the relay, the relay makes zero padding on the decoding bit sequence with smaller length to make the two decoding bit sequences have equal length, and makes exclusive-or operation on the two decoding bit sequences with equal length to combine into a bit sequence, and then modulates the bit sequence into a symbol sequence to send signals at downlink. In the embodiment shown in fig. 6, the lengths of the modulated symbol sequences are made to be consistent by the inconsistency of the lengths of the transmitted bit sequences of the two terminal devices, and the lengths of the bit sequences of the two devices are kept consistent by the zero padding operation of the bit sequence of the low-order modulation device at the relay node, so as to meet the transmission requirement of the downlink network coding.
As shown in fig. 7, in an embodiment, the adaptive selection system of the bidirectional relay scheme of the present invention is applied to a bidirectional relay system, which includes a far-end device, a near-end device and a relay.
The adaptive selection system for the bidirectional relay scheme comprises a comparison module 71, a first selection module 72 and a second selection module 73.
The comparing module 71 is configured to compare the received signal-to-noise ratio of the near-end device with a signal-to-noise ratio threshold value.
The first selecting module 72 is connected to the comparing module 71, and configured to select the first bidirectional relay scheme when the received signal-to-noise ratio of the near-end device is smaller than a signal-to-noise ratio threshold value, so that the far-end device and the near-end device transmit a communication signal by using an orthogonal multiple access technology in an uplink, and the relay distributes the communication signal by using a network coding technology in a downlink; in the first bidirectional relay scheme, the far-end device and the near-end device transmit frequency domain signal streams on different time frequency resources.
The second selecting module 73 is connected to the comparing module 71, and configured to select the second bidirectional relay scheme when the received signal-to-noise ratio of the near-end device is not less than the signal-to-noise ratio threshold, so that the far-end device and the near-end device transmit a communication signal in an uplink by using a non-orthogonal multiple access technology, and the relay distributes the communication signal in a downlink by using a network coding technology; and in the second bidirectional relay scheme, the far-end equipment and the near-end equipment adopt a bit matching transmission method or a symbol matching transmission method to transmit frequency domain signal streams on the same time frequency resource.
The structures and principles of the comparing module 71, the first selecting module 72, and the second selecting module 73 correspond to the steps in the adaptive selection method for the bidirectional relay scheme one to one, and therefore are not described herein again.
It should be noted that the division of the modules of the above apparatus is only a logical division, and the actual implementation may be wholly or partially integrated into one physical entity, or may be physically separated. And the modules can be realized in a form that all software is called by the processing element, or in a form that all the modules are realized in a form that all the modules are called by the processing element, or in a form that part of the modules are called by the hardware. For example: the x module can be a separately established processing element, and can also be integrated in a certain chip of the device. In addition, the x-module may be stored in the memory of the apparatus in the form of program codes, and may be called by a certain processing element of the apparatus to execute the functions of the x-module. Other modules are implemented similarly. All or part of the modules can be integrated together or can be independently realized. The processing element described herein may be an integrated circuit having signal processing capabilities. In implementation, each step of the above method or each module above may be implemented by an integrated logic circuit of hardware in a processor element or an instruction in the form of software. These above modules may be one or more integrated circuits configured to implement the above methods, such as: one or more Application Specific Integrated Circuits (ASICs), one or more microprocessors (DSPs), one or more Field Programmable Gate Arrays (FPGAs), and the like. When a module is implemented in the form of a Processing element scheduler code, the Processing element may be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of calling program code. These modules may be integrated together and implemented in the form of a System-on-a-chip (SOC).
The storage medium of the present invention has stored thereon a computer program which, when executed by a processor, implements the above-described method for optimal dynamic power allocation based on uplink NOMA. Preferably, the storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic disk, U-disk, memory card, or optical disk.
As shown in fig. 8, in an embodiment, the adaptive selection terminal of the bidirectional relay scheme of the present invention includes: a processor 81 and a memory 82.
The memory 82 is used to store computer programs.
The memory 82 includes: various media that can store program codes, such as ROM, RAM, magnetic disk, U-disk, memory card, or optical disk.
The processor 81 is connected to the memory 82, and is configured to execute a computer program stored in the memory 82, so that the bidirectional relay scheme adaptive selection terminal performs the above optimal dynamic power allocation method based on uplink NOMA.
Preferably, the Processor 1 may be a general-purpose Processor, including a Central Processing Unit (CPU), a Network Processor (NP), and the like; the Integrated Circuit may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, or discrete hardware components.
As shown in fig. 9, in an embodiment, the bidirectional relay scheme adaptive selection system of the present invention includes the bidirectional relay scheme adaptive selection terminal 91 and the bidirectional relay system 92.
The bidirectional relay system 92 includes a far-end device, a near-end device, and a relay, and is configured to execute an adaptive bidirectional relay scheme under the control of the bidirectional relay scheme adaptive selection terminal 91.
In summary, the bidirectional relay scheme adaptive selection method, system, storage medium and terminal of the present invention can select a bidirectional relay scheme adapted to an application scenario based on a preset selection criterion, so as to maximize the correct transmission probability of the transmission communication signals of the entire bidirectional relay system, the far-end device and the near-end device, thereby improving the throughput of the system and the device end; the method has good compatibility with a bidirectional relay scheme in the prior art, and can be directly applied to the existing bidirectional relay system, so that the system throughput performance is improved; the system can achieve excellent system performance under any signal-to-noise ratio condition, and has good adaptability to next-generation bidirectional relay communication; the self-adaptive switching of the bit matching method and the symbol matching method has excellent flexibility, and the gain of the far-end equipment and the gain of the near-end equipment in the bidirectional relay system can be dynamically switched, so that the communication rate of the far-end equipment can be ensured under a poor channel environment, and the fairness of users can be improved; and the performance of the bidirectional relay system can be maximized by improving the communication rate of the near-end equipment under a better channel environment. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. A bidirectional relay scheme self-adaptive selection method is applied to a bidirectional relay system, wherein the bidirectional relay system comprises a far-end device, a near-end device and a relay; the method is characterized in that:
the self-adaptive selection method of the bidirectional relay scheme comprises the following steps:
comparing the received signal-to-noise ratio of the near-end equipment with a signal-to-noise ratio threshold value;
when the receiving signal-to-noise ratio of the near-end equipment is smaller than a signal-to-noise ratio threshold value, selecting the first bidirectional relay scheme, enabling the far-end equipment and the near-end equipment to transmit communication signals by adopting an orthogonal multiple access technology in an uplink, and enabling the relay to distribute the communication signals by adopting a network coding technology in a downlink; in the first bidirectional relay scheme, the far-end device and the near-end device send frequency domain signal streams on different time-frequency resources;
when the receiving signal-to-noise ratio of the near-end equipment is not smaller than the signal-to-noise ratio threshold value, selecting the second bidirectional relay scheme, enabling the far-end equipment and the near-end equipment to adopt a non-orthogonal multiple access technology to send communication signals in an uplink, and enabling the relay to adopt a network coding technology to distribute the communication signals in a downlink; and in the second bidirectional relay scheme, the far-end equipment and the near-end equipment adopt a bit matching transmission method or a symbol matching transmission method to transmit frequency domain signal streams on the same time frequency resource.
2. The adaptive selection method for a bi-directional relay scheme according to claim 1, wherein: the receiving signal-to-noise ratio of the near-end equipment is calculated by dividing the product of the channel mode value and the transmitting power of the near-end equipment by additive noise; the snr threshold is a received snr of the near-end device when system throughputs of the first and second bi-directional relay schemes are the same in a gaussian channel.
3. The adaptive selection method for a bi-directional relay scheme according to claim 1, wherein: when the second bidirectional relay scheme is selected, when the channel state value of the transmission channel of the far-end equipment is smaller than a state threshold value, the far-end equipment and the near-end equipment adopt a bit matching transmission method; and when the channel state value of the transmission channel of the far-end equipment is not less than the state threshold value, the far-end equipment and the near-end equipment adopt a symbol matching transmission method.
4. The adaptive selection method for a bi-directional relay scheme according to claim 3, wherein: the channel state value of the remote device adopts a channel module value of the remote device, and the state threshold value adopts a channel state value corresponding to the situation that the remote device reaches a target block error rate under a Gaussian channel.
5. The adaptive selection method for a bi-directional relay scheme according to claim 3, wherein: when the bit matching transmission method is adopted, the far-end equipment and the near-end equipment are enabled to send sending bit sequences with the same length, after the two sending bit sequences are modulated into symbol sequences, zero padding is carried out on the symbol sequences with smaller lengths, and the lengths of the two symbol sequences are enabled to be equal; after the two decoded bit sequences are detected and decoded at the relay, the relay performs exclusive-or operation on the two decoded bit sequences to combine the two decoded bit sequences into one decoded bit sequence, and modulates the decoded bit sequence into a symbol sequence to perform signal transmission at a downlink.
6. The adaptive selection method for a bi-directional relay scheme according to claim 1, wherein: when the symbol matching transmission method is adopted, the far-end equipment and the near-end equipment are enabled to send sending bit sequences with different lengths, the lengths can be aligned after the two sending bit sequences are modulated into symbol sequences, and the two sending bit sequences are modulated into the symbol sequences and then directly superposed with signals to complete non-orthogonal transmission; after detecting and decoding two decoding bit sequences at the relay, the relay makes zero padding on the decoding bit sequence with smaller length to make the two decoding bit sequences have equal length, and makes exclusive-or operation on the two decoding bit sequences with equal length to combine into a bit sequence, and then modulates the bit sequence into a symbol sequence to send signals at downlink.
7. A bidirectional relay scheme self-adaptive selection system is applied to a bidirectional relay system, and the bidirectional relay system comprises a far-end device, a near-end device and a relay; the method is characterized in that:
the bidirectional relay scheme self-adaptive selection system comprises a comparison module, a first selection module and a second selection module;
the comparison module is used for comparing the receiving signal-to-noise ratio of the near-end equipment with a signal-to-noise ratio threshold value;
the first selection module is configured to select the first bidirectional relay scheme when a received signal-to-noise ratio of the near-end device is smaller than a signal-to-noise ratio threshold value, so that the far-end device and the near-end device transmit a communication signal by using an orthogonal multiple access technology in an uplink, and the relay distributes the communication signal by using a network coding technology in a downlink; in the first bidirectional relay scheme, the far-end device and the near-end device send frequency domain signal streams on different time-frequency resources;
the second selection module is configured to select the second bidirectional relay scheme when the received signal-to-noise ratio of the near-end device is not less than the signal-to-noise ratio threshold value, so that the far-end device and the near-end device transmit a communication signal in an uplink by using a non-orthogonal multiple access technology, and the relay distributes the communication signal in a downlink by using a network coding technology; and in the second bidirectional relay scheme, the far-end equipment and the near-end equipment adopt a bit matching transmission method or a symbol matching transmission method to transmit frequency domain signal streams on the same time frequency resource.
8. A storage medium having stored thereon a computer program, characterized in that the program, when being executed by a processor, implements the bi-directional relay scheme adaptive selection method of any one of claims 1 to 6.
9. A bidirectional relay scheme adaptive selection terminal, comprising: a processor and a memory;
the memory is used for storing a computer program;
the processor is configured to execute the memory-stored computer program to cause the terminal to perform the bidirectional relay scheme adaptive selection method of any one of claims 1 to 6.
10. A two-way relay scheme adaptive selection system, characterized by: comprising the bidirectional relay scheme adaptive selection terminal and the bidirectional relay system of claim 9;
the bidirectional relay system comprises a far-end device, a near-end device and a relay, and is used for executing an adaptive bidirectional relay scheme under the control of the bidirectional relay scheme adaptive selection terminal.
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