阅读说明：本技术 一种基于瞬时信道状态信息估计的能量缓存传输协议 (Energy cache transmission protocol based on instantaneous channel state information estimation ) 是由 隋缘 于 2020-03-22 设计创作，主要内容包括：基于瞬时信道状态信息估计的能量缓存传输协议应用于移动互联网和物联网,以及适用于短距离通信的无线个人局域网,无线体域网。其特征：技术方案包括：设置“源-中继-目的”双跳中继系统模型、“源-中继-目的”双跳中继系统模型中信号传输格式、链路选择协议、实施流程。效果：具有更优的误码率性能,增加3dB-5dB的增益,同时也是更符合实际情况下的各种环境复杂的通信场景。(The energy cache transmission protocol based on the instantaneous channel state information estimation is applied to the mobile internet and the internet of things, and is suitable for a wireless personal area network and a wireless body area network of short-distance communication. The method is characterized in that: the technical scheme comprises the following steps: and setting a source-relay-destination double-hop relay system model, a signal transmission format in the source-relay-destination double-hop relay system model, a link selection protocol and an implementation process. The effect is as follows: the method has better error rate performance, increases the gain of 3dB-5dB, and is more suitable for various complex communication scenes in the environment under the actual condition.)

1. An energy buffer transmission protocol based on instantaneous channel state information estimation is characterized in that: the technical scheme of the invention comprises the following steps;

step 1: setting source-relay-destination double-hop relay system model

In the invention, a source-relay-destination double-hop relay system model is set, an energy buffer is equipped at a relay node for storing collected energy, one part of the collected energy is used for decoding information, and the other part of the collected energy is used for sending the rest information to a destination end;

a signal source (1) in the double-hop relay system model sends a signal (2) received by a relay node to a power divider (6) through a link (3) between the signal source and the relay node; a noise signal (5) between a signal source and a relay node in the double-hop relay system model is sent to a noise-passing path (4) and a link (3) between the signal source and the relay node to a power divider (6); a power splitter (6) splits the signal received by the relay node into two parts, wherein: a part of the signals (7) received by the energy collector is sent to the energy collector (11) with the energy storage (12) through a path (8) between the relay node and the energy collector; another part of the signals (9) received by the information receiver are sent to a signal receiver (13) with a data memory/data packet buffer (14) through a path (10) between the relay node and the information receiver; the receiving energy stored in the energy buffer area of the energy collector (11) decodes the information signal stored in the information buffer area of the signal receiver (13) to obtain a decoded information signal; the decoded information signal is transmitted to a destination node (17) through a link (15) from the relay terminal to the destination node; the noise signal (7) between the relay end and the destination node is transmitted to the destination node (17) through a noise path (16);

the relay terminal is composed of the power divider (6), a signal (7) received by the energy collector, a path (8) between the relay node and the energy collector, a signal (9) received by the information receiver, a path (10) between the relay node and the information receiver, the energy collector (11), an energy memory (12), a signal receiver (13) and a data memory/data packet buffer (14);

the signal (2) received by the relay node is a signal sent to the relay node from a signal source; a DCSK modulation signal sent by a representative source node;

the noise signal between the signal source and the relay node is Gaussian white noise;

the signal (7) received by the energy collector is converted into energy for transmitting the signal to the energy loss generated by the destination node;

the signal (9) received by the information receiver is temporarily stored in the signal receiver and waits for the signal sent to the destination node;

the signal receiver is used for storing the signal from the relay node;

the destination node (18) is a signal terminating receiving place;

step 2: signal transmission format in 'source-relay-destination' double-hop relay system model

The noise signal (5) between the signal source and the relay node is S->Noise of R link is selected by S->When R link is transmitting, Y_S(i) The DCSK modulated signal sent on behalf of the source node is transmitted to a relay node of a power divider (6) through a link (3) between the signal source and the relay node, and a signal format Y received at the relay node_R(i) Comprises the following steps:

① formula (I), P_SRepresenting the transmission power of the transmitting end; x_S(i) Representing the chaotic signal received by the relay node, h_sr(i) Represents S->The channel fading coefficient of the R link;

the S- > R is the transmission from the node S to the node R;

the relay receives the signal and then performs power division, the received signal is divided into two parts, one part is converted into collected energy, and the other part is stored in the information receiver to wait for signal transmission. The collected energy and part of the signal are temporarily stored in their corresponding energy receiver and information receiver, respectively. Wherein, one part of the collected energy is used for recovering the received signal, and the other part of the collected energy is used as the destination node of the signal receiver (13) for sending corresponding information when the transmission power waits for the channel quality to be good; at the destination node, the received signal Y_D(i) Comprises the following steps:

② formula (h)_rd(i) Represents R->Channel fading coefficient of D link, n_d(i) Is subject to independent complex Gaussian white noise, P_EHWork collected from received signals for relaysThe ratio, expressed as follows:

P_EH＝κ(1-g)P_S|h_rs|²......③

③, wherein κ is the energy conversion efficiency factor of the energy collector, whose value range is 0 & ltκ & lt 1, and g represents the power division ratio;

r- > D is the transmission from the node R to the node D;

after the relay is subjected to power division, the energy in the energy collector (11) and the information stored in the signal receiver (13) are in a one-to-one correspondence relationship, namely when the relay sends the demodulation signal to a destination node, the power consumed by the sending signal is collected from the signal; the principle of first-in first-out is adopted in the information transmission process, namely, the signals stored in the buffer area are firstly sent to the destination end, and the signals are sent in sequence according to the transmission mode. Then, in the energy receiver (11) we receive the signal format Y_E(i) Comprises the following steps:

a modulated signal Y received by the information receiver 13_I(i) Is composed of

In equation ⑤, since the RF signal at the relay is converted to a baseband signal, a mean of 0 and a variance of 0 are generatedComplex white gaussian noise n_I(i) In that respect In the whole information transmission process, a decode-and-forward (DF) mode is adopted, namely, a source node firstly modulates a transmission signal, a relay node receives the signal and then converts a part of the signal into energy, then decodes the information, and then when the relay node needs to transmit the information to a target node, the relay node remodulates the signal and then transmits the information to the target nodeTo the destination end, this is the whole process of the whole decoding forwarding. It should be noted that, when sending the modulation signal to the destination node, it is necessary to first determine whether the transmission link state from the current relay node to the destination node is suitable for transmitting the signal, and when determining that the instantaneous signal-to-noise ratio of the second transmission link is greater than the instantaneous signal-to-noise ratio of the first transmission link, decoding the information signal can be started so as to perform the next transmission;

and step 3: link selection protocol

It is proposed that the link selection protocol can be divided into two cases:

case 1: after channel estimation, if the link condition of S- > R is better, information transmission is carried out according to two states of a cache region;

if the current data memory/data packet buffer (14) is in a non-full state, selecting an S- > R link for transmission, and increasing one data packet by the data volume of the buffer;

if the data memory/packet buffer (14) is full with current data information, no link selection is performed but the next time slot is awaited;

the channel estimation is that firstly, the traditional pilot frequency insertion is carried out, and then the channel information is obtained by the least square method, which is called least square channel estimation for short;

case 2: after channel estimation, if the quality of the R- > D link is better, information transmission is carried out according to the state of the buffer area;

if the current data memory/packet buffer (14) has no data information, then no link selection is made, but rather a wait for the next time slot;

if the current data memory/data packet buffer (14) is in a non-empty state, selecting an R- > D link for transmission, and reducing the data volume of the buffer by one data packet;

and 4, step 4: flow of implementation

201. Respectively acquiring the channel quality of a first transmission link from a source node to a relay node and the channel quality of a second transmission link from a destination node to the relay node;

the source node is a signal source (1) node;

the relay node is a relay node in the power divider (6);

the first transmission link is from a signal source (1) to a relay node in a power divider (6) and then to an energy receiver (11);

the second transmission link is a relay node from the signal source (1) to the power divider (6) and then to the signal receiver (13);

the channel quality of said transmission link is determined by the instantaneous signal-to-noise ratio of the channel;

202. judging whether the first transmission link is larger than the instantaneous signal-to-noise ratio of the second transmission link and the data buffer area is in a non-full state, if so, executing a step 203;

the first transmission link data buffer is a data buffer in the energy receiver (11);

the second transmission link data buffer is a data buffer in the signal receiver (13);

the judgment of whether the data cache area is in a non-full state is to determine whether a space for receiving new information of the relay node exists;

judging whether the first transmission link is larger than the instantaneous signal-to-noise ratio of the second transmission link or not and the data buffer area is in a non-full state, and determining whether the source node is suitable for sending information to the relay node or not in the current transmission environment;

203. a relay node in a power divider (6) receives a modulation signal sent by a source node;

the modulation signal is a DCSK modulation signal (2) sent by a signal source (1) and a Gaussian white noise signal between the signal source and a relay node;

204. performing power division on the modulation signal in a power division mode to obtain received energy and an information signal;

205. storing the received energy and information signals in an energy buffer area in the energy collector (11) and an information buffer area in the signal receiver (13) respectively;

206. acquiring instantaneous signal-to-noise ratios of the first transmission link and the second transmission link in real time;

207. judging that the instantaneous signal-to-noise ratio of the second transmission link is greater than that of the first transmission link, if so, executing a step 208; if not, execute 206;

208. decoding the information signal stored in the information buffer area of the signal receiver (13) by using the received energy stored in the energy buffer area of the energy collector (11) to obtain a decoded information signal;

209. and the decoded information signal is transmitted to the destination node (17) by utilizing the residual energy obtained by decoding the received energy stored in the energy buffer area of the energy collector (11).

Technical Field

The invention belongs to the technical field of communication, and particularly relates to an energy cache transmission protocol based on instantaneous channel state information estimation. The method is applied to the mobile Internet and the Internet of things, and is suitable for the wireless personal area network and the wireless body area network of short-distance communication.

Background

The cooperative communication is a communication technology which can effectively improve diversity gain, enlarge coverage area and improve the communication quality of edge users in wireless communication. Each relay node in the network may cooperate with each other for information transmission using the broadcast nature of wireless communication. The traditional cooperative communication is based on time division multiple access, and in a sending time slot, a source node sends information to a relay node, and the relay node receives the information; in the receiving time slot, the relay node transmits the received signal to the destination node, and the destination node receives the signal. The transmission mode cannot fully exert the advantages of the relay node, because the receiving and sending processes at the relay are continuous, any transmission link is interrupted, and information cannot be successfully transmitted. To further improve the system, buffer assisted relay systems have been proposed, which are based on the principle of adding a buffer at the relay node for storing the received data information, so that the relay does not have to forward the received signal immediately after it has received it. This also provides the possibility for the wireless energy-carrying transmission technique proposed herein for link selection based on instantaneous channel state information.

In 2013, Toufiqul Islam, Robert Schober et al proposed a cooperative diversity scheme based on buffer assisted relaying, and proposed a novel link selection protocol by using a combination of bit interleaved coded modulation and orthogonal frequency division multiplexing. ("conversion and delay analysis of buffer-aid BICM-OFDM relay," IEEETranss. Wireless Commun., vol.12, No.11, pp.5506-5519, Nov.2013.).

Table 1: conventional link selection scheme

Link selection protocol for Toufiqul Islam, Robert Schober et al channel model for the entire system:

assuming that the S → R link is selected for transmission at time slot t, the R signal received from S on the k sub-carrier can be modeled as

Wherein, P_SRepresenting the transmission power per subcarrier at the source node, N_SR[k]Is a mean value of N₀Complex additive white gaussian noise.K-th representing time tS-for each subcarrier > channel gain for the R link.

To decode the bits sent by S, R computes the BICM bit metric for the ith bit in the symbol tag as:

wherein the content of the first and second substances,similarly, if link R- > D is selected for transmission at slot q > t, then the k-th subcarrier received by destination node D from relay node R may be represented as follows:

wherein, P_RRepresenting the average transmission power per subcarrier, N, at the relay node R_RD[k]Is a mean value of N₀Complex white gaussian noise, andrepresenting the frequency response of the R- > D channel.

As can be seen from the link selection scheme, case 1 and case 2 do not select links according to link quality when the buffer is empty and full, which may result in mandatory transmission, and this method has a disadvantage of reducing the error rate performance of the system. Meanwhile, the technology assumes that the channel state is known and no channel estimation is performed, which is not suitable for an actual communication scenario.

Disclosure of Invention

The purpose of the invention is as follows: an energy buffer transmission protocol based on instantaneous channel state information estimation carries out link selection through channel estimation, and achieves the purposes of effectively improving the error rate performance of a system and better conforming to a real communication application environment.

Drawings

Fig. 1 is a schematic diagram of an energy buffer transmission protocol system model based on instantaneous channel state information estimation according to the present invention.

FIG. 2 is a flow chart of an energy buffer transmission protocol based on instantaneous channel state information estimation

In FIG. 1, 1-the signal source; 2-signals received by the relay node (signals sent from the signal source to the relay node); 3-a link between the signal source and the relay node; 4-path of noise; 5-noise signal (white gaussian noise) between signal source and relay node; a 6-power splitter (SWIPT: splitting the signal received by the relay node into two parts, one part being forwarded to the energy collector and the other part being forwarded to the information receiver); 7-the signal received by the energy harvester (this part of the signal will be converted into energy for the energy loss generated by the signal transmission to the destination node); 8-path between relay node and energy collector; 9-signal received by the information receiver (this part of signal will be temporarily stored in the signal receiver and wait for being sent to the destination node); 10-path between relay node and information receiver; 11-an energy harvester (for storing the signal from the relay node and converting the signal into energy); 12-energy storage (i.e. battery); 13-signal receiver (for storing signals from relay nodes); 14-data memory/packet buffer; 15-link of relay end to destination node; 16-a noise path; 17-noise signal between relay end to destination node; 18-destination node (signal terminating destination).

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The embodiment of the application provides an energy cache transmission protocol based on instantaneous channel state information estimation, which is used for solving the technical problem of high transmission error rate in the existing wireless energy-carrying communication system.

It should be noted that Wireless energy Transfer technology (SWIPT) is a novel Wireless communication type, and is different from the traditional Wireless communication that only transmits Information, and the Wireless energy Transfer technology can also provide energy to the Wireless terminal while transmitting Information, and the technology converts a part of received signals into energy, and the Wireless energy can be stored in the battery of the Wireless terminal through a series of conversion, and the captured energy can be used for energy consumption of a normal Information interaction circuit and energy consumption of an energy capture circuit of the Wireless terminal. Therefore, the inconvenience brought by the traditional wired or battery power supply is replaced, the volume and the cost of the terminal are reduced, and the method is particularly suitable for the application of terminal nodes and human body local area networks which need to be distributed in a large scale.

However, when the existing wireless energy-carrying transmission is performed, a part of signals are converted into energy for information transmission, and noise interference in the transmission process is added, so that the technical problem that the error rate of messages received by a target node is high is finally caused.

In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to fig. 1 and 2 of the embodiments of the present invention, and it is apparent that the embodiments described below are only a part of the embodiments of the present invention, but not all of the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

A first embodiment of the present application provides an energy buffer transmission protocol based on instantaneous channel state information estimation, including:

step 1: setting source-relay-destination double-hop relay system model

The invention sets a 'source-relay-destination' double-hop relay system model, and at a relay node, an energy buffer is equipped for storing collected energy, one part of the collected energy is used for decoding information, and the other part of the collected energy is used for sending the rest information to a destination terminal.

A signal source 1 in a double-hop relay system model sends a signal 2 received by a relay node to a power divider 6 through a link 3 between the signal source and the relay node; a noise signal 5 between a signal source and a relay node in the double-hop relay system model sends a path 4 which has noise and a link 3 between the signal source and the relay node to a power divider 6; the power splitter 6 splits the signal received by the relay node into two parts, wherein: a part of the signals 7 received by the energy collector is sent to an energy collector 11 with an energy storage 12 through a path 8 between the relay node and the energy collector; another part of the signals 9 received by the information receiver are sent to a signal receiver 13 with a data memory/data packet buffer 14 through a path 10 between the relay node and the information receiver; the energy collector 11 decodes the information signal stored in the information buffer of the signal receiver 13 by the received energy stored in the energy buffer to obtain a decoded information signal; the decoded information signal is transmitted to a destination node 17 through a link 15 from the relay terminal to the destination node; the noise signal 7 between the relay end and the destination node is transmitted to the destination node 17 through a noise path 16;

the power divider 6, the signal 7 received by the energy collector, the path 8 between the relay node and the energy collector, the signal 9 received by the information receiver, the path 10 between the relay node and the information receiver, the energy collector 11, the energy memory 12, the signal receiver 13 and the data memory/data packet buffer 14 form a relay end;

the signal 2 received by the relay node is a signal sent to the relay node from a signal source; a DCSK modulation signal sent by a representative source node;

the noise signal between the signal source and the relay node is Gaussian white noise;

the signal 7 received by the energy collector is converted into energy for transmitting the signal to the energy loss generated by the destination node;

the signal 9 received by the information receiver is temporarily stored in the signal receiver and waits for the signal sent to the destination node;

the signal receiver is used for storing the signal from the relay node;

the destination node 18 is a signal terminating destination;

step 2: signal transmission format in 'source-relay-destination' double-hop relay system model

Said signalThe noise signal 5 between the source and the relay node is the noise of the S- > R link, then when the S- > R link is selected for transmission, Y is_S(i) The DCSK modulation signal sent on behalf of the source node is transmitted to a relay node of a power divider 6 through a link 3 between the signal source and the relay node, and a signal format Y received at the relay node_R(i) Comprises the following steps:

① formula (I), P_SRepresenting the transmission power of the transmitting end; x_S(i) Representing the chaotic signal received by the relay node, h_sr(i) Representing the channel fading coefficient of the S- > R link;

the S- > R is the transmission from the node S to the node R;

the relay receives the signal and then performs power division, the received signal is divided into two parts, one part is converted into collected energy, and the other part is stored in the information receiver to wait for signal transmission. The collected energy and part of the signal are temporarily stored in their corresponding energy receiver and information receiver, respectively. Wherein, one part of the collected energy is used for recovering the received signal, and the other part is used as the destination node of the signal receiver 13 for sending corresponding information when the transmission power waits for the channel quality to be good; at the destination node, the received signal Y_D(i) Comprises the following steps:

② formula (h)_rd(i) Representing the channel fading coefficient, n, of an R- > D link_d(i) Is subject to independent complex Gaussian white noise, P_EHFor the power collected from the received signal at the relay, the expression is as follows:

P_EH＝κ(1-g)P_S|h_sr|²......③

③, wherein κ is the energy conversion efficiency factor of the energy collector, whose value range is 0 & ltκ & lt 1, and g represents the power division ratio;

r- > D is the transmission from the node R to the node D;

after the relay performs power division, the energy in the energy collector 11 and the information stored in the signal receiver 13 are in a one-to-one correspondence relationship, that is, when the relay sends the demodulation signal to the destination node, the power consumed by the sending signal is collected from the signal; the principle of first-in first-out is adopted in the information transmission process, namely, the signals stored in the buffer area are firstly sent to the destination end, and the signals are sent in sequence according to the transmission mode. Then in the energy receiver 11 we receive the signal format Y_E(i) Comprises the following steps:

modulated signal Y received by information receiver 13_I(i) Is composed of

In equation ⑤, since the RF signal at the relay is converted to a baseband signal, a mean of 0 and a variance of 0 are generatedComplex white gaussian noise n_I(i) In that respect In the whole information transmission process, a decode-and-forward (DF) mode is adopted, that is, a source node modulates a transmission signal first, a relay node receives the signal and converts a part of the signal into energy, then decodes the information, and then when the relay node needs to transmit the information to a destination node, the relay remodulates the signal and transmits the signal to the destination node, which is the whole process of decoding and forwarding. It should be noted that, when sending the modulation signal to the destination node, it is necessary to first determine whether the transmission link state from the current relay node to the destination node is suitable for transmitting the signal, and when determining that the instantaneous signal-to-noise ratio of the second transmission link is greater than the instantaneous signal-to-noise ratio of the first transmission link, then the instantaneous signal-to-noise ratio of the second transmission link is determined to be greater than the instantaneous signal-toDecoding of the information signal can begin for further transmission.

And step 3: link selection protocol

It is proposed that the link selection protocol can be divided into two cases as shown in table 2:

table 2: channel quality versus buffer variation

Wherein, X means link transmission interruption, N is the upper storage limit of the buffer (energy buffer and data buffer),_SRfor the instantaneous signal-to-noise ratio of the first transmission link,_RDis the instantaneous signal-to-noise ratio, S, of the second transmission link_iRepresenting the size of the data amount in the buffer of the ith time slot.

Case 1: after channel estimation, if the link condition is better when S- > R, information transmission is carried out according to two states of the buffer area;

if the current data memory/data packet buffer 14 is in a non-full state, selecting an S- > R link for transmission, and adding a data packet to the data volume of the buffer;

if the data memory/packet buffer 14 is full of current data information, no link selection is performed but the next time slot is awaited;

the channel estimation is that firstly, the traditional pilot frequency insertion is carried out, and then the channel information is obtained by the least square method, which is called least square channel estimation for short;

case 2: after channel estimation, if the quality of the R- > D link is better, information transmission is carried out according to the state of the buffer area;

if the current data memory/packet buffer 14 has no data information, then no link selection is performed, but rather a wait for the next time slot;

if the current data memory/data packet buffer 14 is in a non-empty state, selecting an R- > D link for transmission, and reducing the data volume of the buffer by one data packet;

and 4, step 4: flow of implementation

201. Respectively acquiring the channel quality of a first transmission link from a source node to a relay node and the channel quality of a second transmission link from a destination node to the relay node;

the source node is a signal source 1 node;

the relay node is a relay node in the power divider 6;

the first transmission link is from the signal source 1 to a relay node in the power divider 6 and then to the energy receiver 11;

the second transmission link is a relay node from the signal source 1 to the power divider 6 and then to the signal receiver 13;

the channel quality of said transmission link is determined by the instantaneous signal-to-noise ratio of the channel;

202. judging whether the first transmission link is larger than the instantaneous signal-to-noise ratio of the second transmission link and the data buffer area is in a non-full state, if so, executing a step 203;

the first transmission link data buffer is a data buffer in the energy receiver 11;

the second transmission link data buffer is a data buffer in the signal receiver 13;

the judgment of whether the data cache area is in a non-full state is to determine whether a space for receiving new information of the relay node exists;

judging whether the first transmission link is larger than the instantaneous signal-to-noise ratio of the second transmission link or not and the data buffer area is in a non-full state, and determining whether the source node is suitable for sending information to the relay node or not in the current transmission environment;

203. a relay node in the power divider 6 receives a modulation signal sent by a source node;

the modulation signal is a DCSK modulation signal 2 sent by a signal source 1 and a Gaussian white noise signal between the signal source and a relay node;

204. performing power division on the modulation signal in a power division mode to obtain received energy and an information signal;

205. storing the received energy and information signals in an energy buffer in the energy collector 11 and an information buffer in the signal receiver 13, respectively;

206. acquiring instantaneous signal-to-noise ratios of the first transmission link and the second transmission link in real time;

207. judging that the instantaneous signal-to-noise ratio of the second transmission link is greater than that of the first transmission link, if so, executing a step 208; if not, execute 206;

208. decoding the information signal stored in the information buffer of the signal receiver 13 by using the received energy stored in the energy buffer of the energy collector 11 to obtain a decoded information signal;

209. the decoded information signal is transmitted to the destination node 17 using the remaining energy obtained by decoding the received energy stored in the energy buffer of the energy scavenger 11.

The energy cache transmission protocol based on the instantaneous channel state information estimation has better error rate performance, 3.8dB gain is increased, and meanwhile, the energy cache transmission protocol is more suitable for various complex communication scenes in various environments under actual conditions.

As described above, the present invention has been described in detail, but it is obvious to those skilled in the art that many modifications are possible without substantially departing from the invention and the effects thereof. Therefore, such modifications are also all included in the scope of the present invention.