CN107070508A - The adaptive retransmission method of signal to noise ratio in cooperative communication network system - Google Patents
The adaptive retransmission method of signal to noise ratio in cooperative communication network system Download PDFInfo
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- 238000004891 communication Methods 0.000 title claims abstract description 26
- 230000003044 adaptive effect Effects 0.000 title claims abstract description 13
- 230000008054 signal transmission Effects 0.000 claims abstract description 8
- 238000001514 detection method Methods 0.000 claims abstract description 6
- 238000007476 Maximum Likelihood Methods 0.000 claims description 5
- 238000004458 analytical method Methods 0.000 claims description 3
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/022—Site diversity; Macro-diversity
- H04B7/026—Co-operative diversity, e.g. using fixed or mobile stations as relays
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
- H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
- H04B7/0842—Weighted combining
- H04B7/0848—Joint weighting
- H04B7/0854—Joint weighting using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
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Abstract
The present invention relates to the adaptive retransmission method of signal to noise ratio in a kind of cooperative communication network system.According to real-Time Signal Transfer environment and channel condition, Soft Inform ation is obtained from the signal received using the adaptive method of estimation of signal to noise ratio；Transmit power is normalized via node, and sends the Soft Inform ation to receiving node；Receiving node detects the signal that the via node is sent using spherical detection algorithm.The present invention had both overcome the defect of amplification forwarding and decoding forwarding, and linear processing techniques is made full use of again, reduces algorithm complex when signal is obtained on via node, improves the real-time and efficiency of signal transmission.
Description
Technical Field
The invention relates to the field of traffic communication, in particular to a signal-to-noise ratio self-adaptive forwarding method in a cooperative communication network system.
Background
In a cooperative communication network, one of the key technologies is a signal transmission and forwarding technology. Two conventional cooperative forwarding methods are amplify-and-forward and decode-and-forward. The amplify-and-forward is a cooperative protocol which is the simplest to implement, and the relay node simply amplifies and forwards the received signal from the source node, and in the amplify-and-forward process, the noise contained in the received signal is also amplified. The decoding and forwarding are complex, and noise is removed on the relay node and then the relay node forwards the decoded data, so that the noise amplification effect is overcome. However, the disadvantages of the decode-and-forward method are: once the relay node decodes the error, the error signal is forwarded to the destination node.
In the existing patent document CN105490721A (title of the invention: an estimation forwarding method for full-duplex traffic cooperative communication network, publication date: 2016.04.13), it is proposed that a relay node acquires estimation soft information of a transmission signal by using an Unconstrained minimum mean square error algorithm. The method mainly aims at a full-duplex cooperative communication network, and can solve the defects of amplification forwarding and decoding forwarding, but the implementation of the method needs channel state information of two sending communication links in the known full-duplex network (or channel information is obtained through channel estimation), so the calculation method is complex, and in the case of unknown channel state information, performance loss is possibly caused by channel estimation errors.
Disclosure of Invention
In order to solve the above problems in the prior art, the invention provides a signal-to-noise ratio adaptive forwarding method in a cooperative communication network system, which not only overcomes the defects of amplification forwarding and decoding forwarding, but also reduces the algorithm complexity when a relay node acquires a signal, and improves the real-time performance and efficiency of signal transmission.
The invention provides a signal-to-noise ratio self-adaptive forwarding method in a cooperative communication network system, which comprises the following steps:
the relay node obtains soft information (soft information) from the received signal by adopting a signal-to-noise ratio self-adaptive estimation method according to a real-time signal transmission environment and a channel condition.
Preferably, the method for estimating using signal-to-noise ratio adaptation obtains soft information from a received signal, specifically:
wherein,in order to be soft information, the user can select the information,for signals acquired using linear minimum mean square error estimation,for signals obtained by maximum likelihood estimation, ωoptFor the optimal value of the adaptive parameter, it is obtained by mathematical analysis:
where E represents the mathematical expectation, ω is the adaptive parameter, and x is the signal sent by the sending node.
Preferably, theFor signals obtained by linear minimum mean square error estimation, in particularThe estimation method comprises the following steps:
r＝G1x+n1，
wherein G is1For transmitting node to relay node channel state information, σ2Is noise variance, I represents an identity matrix, H represents a conjugate transpose, r is a signal received by the relay node, n is1Is the channel noise of the transmitting node to the relay node.
Preferably, theFor signals obtained by adopting a maximum likelihood estimation method, the specific estimation method comprises the following steps:
wherein,a set of all possible elements of a symbol is modulated for a signal.
Preferably, the relay node performs normalization processing on the transmission power and transmits the soft information to the receiving node.
Preferably, the receiving node detects the signal sent by the relay node by using a sphere detection algorithm.
Preferably, the cooperative communication network system is a single antenna system and/or a multi-antenna system.
Preferably, in the traffic cooperative communication network system, the relay node is a vehicle-mounted terminal and/or a roadside base station having a cooperative communication function.
According to the real-time signal transmission environment and channel conditions, soft information is obtained from received signals by adopting a signal-to-noise ratio self-adaptive estimation method on a relay node; the relay node performs normalization processing on the sending power and sends the soft information to a receiving node; and the receiving node adopts a sphere detection algorithm to detect the signal sent by the relay node. The invention overcomes the defects of amplification forwarding and decoding forwarding, fully utilizes the linear processing technology, reduces the algorithm complexity when the relay node acquires the signal, and improves the real-time performance and the efficiency of signal transmission.
Drawings
Fig. 1 is a schematic diagram of one-time forwarding in traffic cooperative communication in the present embodiment;
fig. 2 is a schematic diagram of two times of forwarding in traffic cooperative communication in this embodiment.
Detailed Description
Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and are not intended to limit the scope of the present invention.
The invention provides a signal-to-noise ratio self-adaptive forwarding method in a cooperative communication network system, which comprises the following steps: the relay node obtains soft information from the received signal by adopting a signal-to-noise ratio self-adaptive estimation method according to a real-time signal transmission environment and a channel condition.
The invention is suitable for a cooperative communication network system, comprising: single antenna and multiple antenna systems. In a cooperative communication network, a signal processing technology on a relay node is very critical, and especially for an environment where vehicles move fast in an internet of vehicles, the reliability of the relay node for forwarding signals directly influences the transmission quality of signals between vehicles and roads. In addition, the time-varying property and the Doppler frequency shift of the traffic channel are serious, so that the signal is seriously influenced by interference and channel fading, and the importance of the relay node signal processing and forwarding method in the traffic cooperative communication network is more highlighted.
The respective disadvantages of the traditional amplifying forwarding method and the traditional decoding forwarding method are comprehensively considered, the signal-to-noise ratio self-adaptive forwarding method provided by the invention can obtain the system performance superior to the two forwarding methods, and the switching is not needed. The relay node receives the information from the sending node, performs signal-to-noise ratio adaptive soft information calculation on the information, and then adjusts the sending power coefficient to forward the information to the destination vehicle node.
In this embodiment, a traffic cooperative communication network system is taken as an example to describe the signal-to-noise ratio adaptive forwarding method. As shown in fig. 1, all the vehicle-mounted terminals and the roadside base stations have a cooperative communication function and can be used as relay nodes. Suppose a signal is sent by a sending node VsSend out through a relay node V1After forwarding, the received node VdReceiving, which comprises the following specific steps:
step S1, transmitting node VsSending out a signal x;
step S2, relay node V1Receiving a signal, wherein the received signal is shown in formula (1):
r＝G1x+n1(1)
wherein G is1For a transmitting node VsTo the relay node V1Channel state information of, n1For a transmitting node VsTo the relay node V1The channel noise of (2);
step S3, at relay node V1In the method, soft information is obtained by adopting a signal-to-noise ratio self-adaptive estimation methodAs shown in equation (2):
wherein, omega is an adaptive parameter,for a signal obtained by using the linear minimum mean square error estimation method, as shown in equation (3):
wherein σ2For noise variance, I denotes identity matrix, H denotes conjugate transpose;
for the signal obtained by the maximum likelihood estimation method, as shown in equation (4):
wherein,modulating a set of all possible elements of a symbol for a signal;
for the adaptive parameter ω, the optimal value ω is obtained by mathematical analysis shown in formula (5)opt：
Wherein E represents a mathematical expectation;
therefore, the soft information finally estimatedAs shown in equation (6):
step S4, relay node V1Normalizing the transmission power and transmitting to a receiving node VdSending the soft information;
step S5, receiving node VdReceiving a signal, wherein the received signal is shown in formula (7):
wherein G is2For relay node to receiving node channel state information, n2Channel noise from the relay node to the receiving node;
and step S6, the receiving node acquires a final signal by adopting a spherical detection algorithm, so that the detection complexity is effectively reduced.
As shown in FIG. 2, the signal is transmitted from the transmitting node VsAfter the emission, the water passes through R in sequence1And V1The forwarding of the two relay nodes is finally received by a receiving node VdReceived, the specific steps are similar to the above steps S1 to S6, but the forwarding is repeated once more:
at a transmitting node VsAfter sending out the signal, the relay node R receives the signal firstly1At R1Acquiring soft information by adopting a signal-to-noise ratio self-adaptive estimation method, then normalizing the transmission power and transmitting the normalized transmission power outwards; next to it, the relay node V1Receiving a signal at V1Acquiring soft information by adopting a signal-to-noise ratio self-adaptive estimation method, then normalizing the transmission power and transmitting the normalized transmission power outwards; finally, the receiving node VdA signal is received.
Similarly, when the distance between the sending node and the receiving node is long, the receiving node may receive the message after multiple times of forwarding. All relay nodes can adopt the signal-to-noise ratio self-adaptive forwarding method.
Those of skill in the art will appreciate that the method steps of the examples described in connection with the embodiments disclosed herein may be embodied in electronic hardware, computer software, or combinations of both, and that the components and steps of the examples have been described above generally in terms of their functionality in order to clearly illustrate the interchangeability of electronic hardware and software. Whether such functionality is implemented as electronic hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.
Claims (8)
1. A signal-to-noise ratio adaptive forwarding method in a cooperative communication network system is characterized by comprising the following steps:
the relay node obtains soft information from the received signal by adopting a signal-to-noise ratio self-adaptive estimation method according to a real-time signal transmission environment and a channel condition.
2. The method according to claim 1, wherein the estimation method using snr adaptation obtains soft information from the received signal, specifically:
<mrow> <mover> <mi>x</mi> <mo>^</mo> </mover> <mo>=</mo> <msub> <mi>&omega;</mi> <mrow> <mi>o</mi> <mi>p</mi> <mi>t</mi> </mrow> </msub> <msub> <mover> <mi>x</mi> <mo>^</mo> </mover> <mrow> <mi>L</mi> <mi>M</mi> <mi>M</mi> <mi>S</mi> <mi>E</mi> </mrow> </msub> <mo>+</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <msub> <mi>&omega;</mi> <mrow> <mi>o</mi> <mi>p</mi> <mi>t</mi> </mrow> </msub> <mo>)</mo> </mrow> <msub> <mover> <mi>x</mi> <mo>^</mo> </mover> <mrow> <mi>M</mi> <mi>L</mi> </mrow> </msub> <mo>,</mo> </mrow>
wherein,in order to be soft information, the user can select the information,for signals acquired using linear minimum mean square error estimation,for signals obtained by maximum likelihood estimation, ωoptFor the optimal value of the adaptive parameter, it is obtained by mathematical analysis:
<mrow> <msub> <mi>&omega;</mi> <mrow> <mi>o</mi> <mi>p</mi> <mi>t</mi> </mrow> </msub> <mo>=</mo> <mi>arg</mi> <munder> <mi>min</mi> <mrow> <mi>&omega;</mi> <mo>&Element;</mo> <mrow> <mo>(</mo> <mn>0</mn> <mo>,</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </munder> <mi>E</mi> <mo>{</mo> <mo>|</mo> <mo>|</mo> <mover> <mi>x</mi> <mo>^</mo> </mover> <mo>-</mo> <mi>x</mi> <mo>|</mo> <msup> <mo>|</mo> <mn>2</mn> </msup> <mo>}</mo> <mo>,</mo> </mrow>
where E represents the mathematical expectation, ω is the adaptive parameter, and x is the signal sent by the sending node.
3. The method of claim 2, wherein the step of generating the second signal comprises generating a second signal based on the first signal and the second signalIn order to obtain signals by adopting a linear minimum mean square error estimation method, the specific estimation method comprises the following steps:
<mrow> <msub> <mover> <mi>x</mi> <mo>^</mo> </mover> <mrow> <mi>L</mi> <mi>M</mi> <mi>M</mi> <mi>S</mi> <mi>E</mi> </mrow> </msub> <mo>=</mo> <msup> <mrow> <mo>(</mo> <msubsup> <mi>G</mi> <mn>1</mn> <mi>H</mi> </msubsup> <msub> <mi>G</mi> <mn>1</mn> </msub> <mo>+</mo> <msup> <mi>&sigma;</mi> <mn>2</mn> </msup> <mi>I</mi> <mo>)</mo> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> <msubsup> <mi>G</mi> <mn>1</mn> <mi>H</mi> </msubsup> <mi>r</mi> <mo>,</mo> </mrow>
r＝G1x+n1，
wherein G is1For transmitting node to relay node channel state information, σ2Is noise variance, I represents an identity matrix, H represents a conjugate transpose, r is a signal received by the relay node, n is1Is the channel noise of the transmitting node to the relay node.
4. The method of claim 3, wherein the step of applying the coating comprises applying a coating to the substrateFor signals obtained by adopting a maximum likelihood estimation method, the specific estimation method comprises the following steps:
wherein,a set of all possible elements of a symbol is modulated for a signal.
5. The method of claim 4, wherein the relay node normalizes the transmit power and transmits the soft information to a receiving node.
6. The method of claim 5, wherein the receiving node employs a sphere detection algorithm to detect the signal from the relay node.
7. The method according to any of claims 1-6, wherein the cooperative communication network system is a single antenna system and/or a multi-antenna system.
8. The method according to any one of claims 1 to 6, wherein in the traffic cooperative communication network system, the relay node is a vehicle-mounted terminal and/or a road side base station with a cooperative communication function.
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|---|---|---|---|---|
| US20100195751A1 (en) * | 2009-02-05 | 2010-08-05 | Orlik Philip V | Method for Estimating Channels in Two-Hop MIMO AF Networks |
| CN204291405U (en) * | 2014-11-28 | 2015-04-22 | 东莞中国科学院云计算产业技术创新与育成中心 | A kind of low power consumption device realizing bus or train route communication |
| CN105490721A (en) * | 2015-10-30 | 2016-04-13 | 青岛智能产业技术研究院 | Estimate-forward method of full-duplex transportation cooperative-communication network |
| EP3101855A1 (en) * | 2014-02-26 | 2016-12-07 | Huawei Technologies Co., Ltd. | Signal processing method and base station |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100195751A1 (en) * | 2009-02-05 | 2010-08-05 | Orlik Philip V | Method for Estimating Channels in Two-Hop MIMO AF Networks |
| EP3101855A1 (en) * | 2014-02-26 | 2016-12-07 | Huawei Technologies Co., Ltd. | Signal processing method and base station |
| CN204291405U (en) * | 2014-11-28 | 2015-04-22 | 东莞中国科学院云计算产业技术创新与育成中心 | A kind of low power consumption device realizing bus or train route communication |
| CN105490721A (en) * | 2015-10-30 | 2016-04-13 | 青岛智能产业技术研究院 | Estimate-forward method of full-duplex transportation cooperative-communication network |
Non-Patent Citations (1)
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|---|
| S. HAN等: "《Soft-Output Extension of an SNR-adaptive Sphere Decoder for Coded MIMO Systems》", 《2012 25TH IEEE CCECE》 * |
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