A data transmission method and device based on imperfect channel and cache assistance

Abstract

The application relates to the technical field of wireless communication, and discloses a data transmission method and device based on an imperfect channel and cache assistance. The method transmits a pilot sequence before data transmission to perform channel estimation on a cache assistance system constructed under an imperfect channel, to obtain channel state information and channel estimation error data, and to obtain energy state information and cache state information at a source node and a relay node; according to the obtained information, a first optimal transmission power corresponding to a first link and a second optimal transmission power corresponding to a second link are calculated by using a Lyapunov optimization framework; the optimal transmission power with the maximum throughput and the minimum Lyapunov drift of the current time slot is determined as the transmission power of the current time slot, and the link corresponding to the transmission power of the current time slot is determined as the transmission link of the current time slot to perform data transmission. The application can fully utilize channel resources, maintain the stability of a queue, and improve the throughput performance and robustness of a system.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a data transmission method and apparatus based on imperfect channels and buffer assistance. Background Technology

[0002] In communication scenarios, transmission quality is significantly affected by long transmission distances and fading. To improve transmission quality, three-node networks consisting of relay nodes between the source and destination nodes are widely used. Currently, most research on buffer-assisted relay networks is conducted under perfect channel conditions. However, in practical applications, perfect channel state information is unavailable due to channel estimation errors. Therefore, how to model imperfect channels and propose robust buffer-assisted transmission methods and devices to reduce performance losses caused by channel estimation errors has become a major challenge that needs to be addressed.

[0003] The main modeling approach for statistical channel models of imperfect channels currently assumes that the channel estimation error is a complex Gaussian variable with zero mean and constant variance. However, using this modeling method, at low signal-to-noise ratios (SNR), the throughput performance under imperfect channel conditions is relatively similar to that under perfect channel conditions, resulting in minimal performance loss under imperfect conditions. At high SNR, however, the throughput performance under imperfect conditions differs significantly from that under perfect conditions, leading to substantial performance loss under imperfect conditions. Therefore, the throughput performance loss varies considerably under different SNR conditions, resulting in weak robustness.

[0004] Currently, there are two main transmission scheduling methods for three-node communication systems based on a single relay: a fixed transmission method without buffer assistance and a fixed transmission method with buffer assistance. However, neither the fixed transmission method without buffer assistance nor the fixed transmission method with buffer assistance makes full use of channel resources, using a fixed transmission power, which easily leads to waste of channel resources, and its robustness is weak under imperfect channel conditions. Summary of the Invention

[0005] This invention provides a data transmission method and apparatus based on imperfect channels and buffer assistance, which can make full use of channel resources, improve system throughput performance, and enhance system robustness.

[0006] To address the aforementioned technical problems, this invention provides a data transmission method based on imperfect channels and buffer assistance, comprising:

[0007] Channel estimation is performed on a preset buffering auxiliary system to obtain the first channel state information and first channel estimation error data of the first link, as well as the second channel state information and second channel estimation error data of the second link; wherein, the buffering auxiliary system is constructed based on an imperfect channel and includes a source node, a relay node and a destination node; the first link is the transmission path from the source node to the relay node; the second link is the transmission path from the relay node to the destination node;

[0008] In the current time slot, first energy state information is obtained from the source node, and second energy state information and cache state information are obtained from the relay node;

[0009] The acquired first channel state information, first channel estimation error data, second channel state information, second channel estimation error data, first energy state information, second energy state information, and buffer state information are sent to the preset decision node.

[0010] Using the Lyapunov optimization framework, the first optimal transmission power for the first link and the second optimal transmission power for the second link are calculated at the decision node, respectively.

[0011] Calculate the throughput and Lyapunov drift of the current time slot corresponding to the first and second optimal transmission powers, respectively.

[0012] The optimal transmission power that maximizes throughput and minimizes Lyapunov drift in the current time slot is determined as the transmission power of the current time slot, and the link corresponding to the transmission power of the current time slot is determined as the transmission link of the current time slot.

[0013] Data transmission is performed based on the transmission power and transmission link of the current time slot.

[0014] This invention transmits a pilot sequence before data transmission to perform channel estimation on a buffer-assisted system built under imperfect channels, obtaining channel state information and channel estimation error data. Energy state information and buffer state information are obtained at the source node and relay node. Based on the obtained information, the first optimal transmission power corresponding to the first link and the second optimal transmission power corresponding to the second link are calculated using the Lyapunov optimization framework. The optimal transmission power with the maximum throughput and the minimum Lyapunov drift in the current time slot is determined as the transmission power of the current time slot, and the link corresponding to the transmission power of the current time slot is determined as the transmission link of the current time slot. Data transmission is then performed, thereby maximizing throughput under imperfect channels while maintaining queue stability.

[0015] Furthermore, the cache-assisted system is built based on an imperfect channel and includes a source node, a relay node, and a destination node, specifically:

[0016] An imperfect channel is constructed based on a statistical channel model using maximum likelihood estimation.

[0017] Building a cache-assisted system under imperfect channels;

[0018] The cache assistance system includes source nodes, relay nodes, and destination nodes;

[0019] The relay node uses a half-duplex decoding and forwarding method and has a caching function.

[0020] This invention introduces a statistical channel model based on maximum likelihood estimation to construct an imperfect channel, and builds a buffer-assisted system under the imperfect channel. This can accurately characterize the channel estimation error under different signal-to-noise ratios, and make the throughput performance under imperfect channel conditions have the same trend as the throughput performance under perfect channel conditions.

[0021] Furthermore, the channel estimation for the preset cache auxiliary system specifically includes:

[0022] Obtain the first test pilot sequence and the second test pilot sequence;

[0023] The first test pilot sequence is transmitted from the source node of the buffer auxiliary system to the relay node, and the second test pilot sequence is transmitted from the relay node of the buffer auxiliary system to the destination node to complete the channel estimation.

[0024] Further, the acquisition of the first channel state information and first channel estimation error data of the first link, and the second channel state information and second channel estimation error data of the second link, specifically includes:

[0025] The first channel estimation error data includes the variance of the first channel estimation error; the second channel estimation error data includes the variance of the second channel estimation error.

[0026] The methods for obtaining the variance of the first channel estimation error and the variance of the second channel estimation error are as follows:

[0027] The number of pilots and the transmit power of the first test pilot sequence and the second test pilot sequence are obtained respectively;

[0028] Obtain the additive white Gaussian noise power of the relay node and the additive white Gaussian noise power of the destination node, respectively;

[0029] The variance of the first channel estimation error is obtained by dividing the additive white Gaussian noise power of the relay node by the product of the number of pilots and the transmit power of the first test pilot sequence.

[0030] The variance of the second channel estimation error is obtained by dividing the additive white Gaussian noise power of the target node by the product of the number of pilots and the transmit power of the second test pilot sequence.

[0031] This invention can obtain channel state information and channel estimation error data when performing channel estimation. The impact of imperfect channels is caused by channel estimation errors. Therefore, the selection of transmission power and link needs to be calculated using the variance of channel estimation error. The variance of channel estimation error is linked with the number of pilots and the signal-to-noise ratio to select the optimal transmission power and link in order to improve the throughput when transmitting data.

[0032] Furthermore, the step of using the Lyapunov optimization framework to calculate the first optimal transmission power corresponding to the first link and the second optimal transmission power corresponding to the second link at the decision node specifically involves:

[0033] Obtain the ratio of the test data sequence to the test transmission sequence;

[0034] Based on the buffer state information, the first energy state information, the second energy state information, the first channel state information, the second channel state information, the variance of the first channel estimation error, and the variance of the second channel estimation error, the first formula and the second formula are solved respectively to obtain the first optimal transmission power and the second optimal transmission power.

[0035] Specifically, the first formula is:

[0036]

[0037]

[0038] Among them, P s Q(t) is the first transmission power; Q(t) is the buffer state information; h'(t) is the first channel state information; It is the variance of the first channel estimation error; β is the additive white Gaussian noise power of the relay node; β is the proportion coefficient of the test data sequence to the test transmission sequence; E s (t) represents the first energy state information; t is the maximum transmit power of the source node; T is the current time slot; B is the duration of the current time slot; V is the channel bandwidth of the buffer auxiliary system; μ1 is a preset constant; and μ1 is a preset non-negative constant.

[0039] The second formula is specifically as follows:

[0040]

[0041]

[0042] Among them, P r (t) represents the second transmission power; Q(t) represents the buffer state information; g'(t) represents the second channel state information; It is the variance of the second channel estimation error; β is the additive white Gaussian noise power at the destination node; β is the proportion coefficient of the test data sequence to the test transmission sequence; E r (t) represents the second energy state information; t is the maximum transmit power of the relay node; t is the current time slot; T is the duration of the current time slot; B is the channel bandwidth of the buffer auxiliary system; V is a preset constant; μ2 is a preset non-negative constant.

[0043] This invention utilizes the Lyapunov optimization framework to set up two optimization problems. Using channel state information and channel estimation error data obtained through channel estimation, as well as energy state information and buffer state information obtained from the source node and relay node, the first optimal transmission power and the second optimal transmission power are calculated. The μ1, μ2 and V set in the formula are constants that are preset according to the actual situation, which can balance the relationship between queue stability and throughput maximization and improve the accuracy of the calculation.

[0044] Furthermore, the preset decision node specifically refers to:

[0045] The decision node is determined from the reserve nodes according to the transmission requirements; wherein, the reserve nodes include the source node, relay node and destination node of the cache auxiliary system.

[0046] Furthermore, the step of obtaining first energy state information from the source node, second energy state information and cache state information from the relay node in the current time slot further includes:

[0047] In the next time slot of the current time slot, the first energy state information, the second energy state information, and the cache state information are updated;

[0048] In the next time slot following the current time slot, the specific formula for updating the first energy state information is as follows:

[0049]

[0050] In the next time slot after the current time slot, the specific formula for updating the second energy state information is as follows:

[0051]

[0052] In the next time slot after the current time slot, the specific formula for updating the cache state information is as follows:

[0053] Q(t+1)=max{Q(t)―b(t),0}+a(t)

[0054] Where β is the proportion of the test data sequence to the test transmission sequence; T is the duration of the current time slot; E s (t+1) is the first energy state information of the next time slot after the current time slot; E s (t) represents the first energy state information of the current time slot; m1(t) represents the first link; P s (t) is the first optimal transmission power; It is the long-term average transmit power of the source node; E r (t+1) is the second energy state information of the next time slot after the current time slot; E r (t) represents the second energy state information of the current time slot; m2(t) represents the second link; P r (t) is the second optimal transmission power; Q(t+1) is the long-term average transmit power of the destination node; Q(t+1) is the buffer status information of the next time slot of the current time slot; Q(t) is the buffer status information of the current time slot; b(t) is the throughput of the relay node forwarding; a(t) is the throughput of the relay node receiving.

[0055] Furthermore, after determining the optimal transmission power that maximizes throughput and minimizes Lyapunov drift in the current time slot as the transmission power of the current time slot, and determining the link corresponding to the transmission power of the current time slot as the transmission link of the current time slot, the method further includes:

[0056] A notification instruction is generated based on the transmission power of the current time slot and the transmission link of the current time slot;

[0057] Using the decision node, the notification instruction is sent to all nodes of the caching assistance system except the decision node.

[0058] This invention provides a data transmission method based on imperfect channels and buffer assistance. Before data transmission, a pilot sequence is transmitted to perform channel estimation on a buffer-assisted system built under imperfect channels, obtaining channel state information and channel estimation error data. Energy state information and buffer state information are obtained at the source node and relay node. Based on the obtained information, the first optimal transmission power corresponding to the first link and the second optimal transmission power corresponding to the second link are calculated using the Lyapunov optimization framework. The optimal transmission power with the maximum throughput and the minimum Lyapunov drift in the current time slot is determined as the transmission power of the current time slot, and the link corresponding to the transmission power of the current time slot is determined as the transmission link of the current time slot. Data transmission is then performed. This invention can make full use of channel resources and improve the throughput performance and robustness of the system while maintaining queue stability.

[0059] Accordingly, the present invention provides a data transmission device based on imperfect channels and buffer assistance, comprising: a channel estimation module, an acquisition module, a transmission module, a first calculation module, a second calculation module, a determination module, and a data transmission module;

[0060] The channel estimation module is used to perform channel estimation on the preset buffering auxiliary system, and to obtain the first channel state information and first channel estimation error data of the first link, as well as the second channel state information and second channel estimation error data of the second link; wherein, the buffering auxiliary system is constructed based on an imperfect channel and includes a source node, a relay node and a destination node; the first link is the transmission path from the source node to the relay node; the second link is the transmission path from the relay node to the destination node;

[0061] The acquisition module is used to acquire first energy state information from the source node, and second energy state information and cache state information from the relay node in the current time slot.

[0062] The sending module is used to send the acquired first channel state information, first channel estimation error data, second channel state information, second channel estimation error data, first energy state information, second energy state information, and buffer state information to a preset decision node;

[0063] The first calculation module is used to calculate the first optimal transmission power corresponding to the first link and the second optimal transmission power corresponding to the second link at the decision node using the Lyapunov optimization framework.

[0064] The second calculation module is used to calculate the throughput corresponding to the first optimal transmission power and the second optimal transmission power, and the Lyapunov drift of the current time slot, respectively.

[0065] The determining module is used to determine the optimal transmission power with the maximum throughput and the minimum Lyapunov drift of the current time slot as the transmission power of the current time slot, and to determine the link corresponding to the transmission power of the current time slot as the transmission link of the current time slot.

[0066] The data transmission module is used to transmit data according to the transmission power of the current time slot and the transmission link of the current time slot.

[0067] Furthermore, the first calculation module includes: a ratio acquisition unit and a calculation unit;

[0068] The ratio acquisition unit is used to acquire the ratio coefficient of the test data sequence to the test transmission sequence;

[0069] The calculation unit is used to solve the first formula and the second formula respectively to obtain the first optimal transmission power and the second optimal transmission power based on the buffer state information, the first energy state information, the second energy state information, the first channel state information, the second channel state information, the variance of the first channel estimation error and the variance of the second channel estimation error.

[0070] Specifically, the first formula is:

[0071]

[0072]

[0073] Among them, P s Q(t) is the first transmission power; Q(t) is the buffer state information; h'(t) is the first channel state information; It is the variance of the first channel estimation error; β is the additive white Gaussian noise power of the relay node; β is the proportion coefficient of the test data sequence to the test transmission sequence; E s (t) represents the first energy state information; t is the maximum transmit power of the source node; T is the current time slot; B is the duration of the current time slot; V is the channel bandwidth of the buffer auxiliary system; μ1 is a preset constant; and μ1 is a preset non-negative constant.

[0074] The second formula is specifically as follows:

[0075]

[0076]

[0077] Among them, P r (t) represents the second transmission power; Q(t) represents the buffer state information; g'(t) represents the second channel state information; It is the variance of the second channel estimation error; β is the additive white Gaussian noise power at the destination node; β is the proportion coefficient of the test data sequence to the test transmission sequence; E r (t) represents the second energy state information; t is the maximum transmit power of the relay node; t is the current time slot; T is the duration of the current time slot; B is the channel bandwidth of the buffer auxiliary system; V is a preset constant; μ2 is a preset non-negative constant.

[0078] This invention provides a data transmission device based on imperfect channels and buffer assistance. Based on the organic combination of modules, it can make full use of channel resources, improve the throughput performance of the system, and enhance the robustness of the system. Attached Figure Description

[0079] Figure 1 A flowchart illustrating an embodiment of the data transmission method based on imperfect channels and buffer assistance provided by the present invention;

[0080] Figure 2 A schematic diagram of the caching auxiliary system provided by the present invention;

[0081] Figure 3 A flowchart illustrating another embodiment of the data transmission method based on imperfect channels and buffer assistance provided by the present invention;

[0082] Figure 4 This is a schematic diagram of an embodiment of the data transmission device based on imperfect channels and buffer assistance provided by the present invention. Detailed Implementation

[0083] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0084] Example 1

[0085] See Figure 1 This is a flowchart illustrating an embodiment of the data transmission method based on imperfect channels and buffer assistance provided by the present invention. The method includes steps 101 to 107, each of which is detailed below:

[0086] Step 101: Perform channel estimation on the preset buffering auxiliary system, and obtain the first channel state information and first channel estimation error data of the first link, as well as the second channel state information and second channel estimation error data of the second link; wherein, the buffering auxiliary system is constructed based on an imperfect channel and includes a source node, a relay node and a destination node; the first link is the transmission path from the source node to the relay node; the second link is the transmission path from the relay node to the destination node.

[0087] Furthermore, in the first embodiment of the present invention, the cache-assisted system is constructed based on an imperfect channel and includes a source node, a relay node, and a destination node, specifically:

[0088] An imperfect channel is constructed based on a statistical channel model using maximum likelihood estimation.

[0089] Building a cache-assisted system under imperfect channels;

[0090] The cache assistance system includes source nodes, relay nodes, and destination nodes;

[0091] The relay node uses a half-duplex decoding and forwarding method and has a caching function.

[0092] In the first embodiment of the present invention, see Figure 2 This diagram illustrates a buffer-assisted system provided by the present invention. The invention introduces a statistical channel model based on maximum likelihood estimation to construct an imperfect channel, which can accurately characterize the channel estimation error under different signal-to-noise ratios and ensure that the throughput performance under imperfect channel conditions follows a similar trend to that under perfect channel conditions. The buffer-assisted system, constructed under imperfect channel conditions, includes a source node, a buffered half-duplex decoding-forwarding relay node, and a destination node. Each node is equipped with a single antenna. Due to severe path loss and shadow fading, there is no direct link between the source and destination nodes; therefore, a relay node is needed to assist in data forwarding.

[0093] Furthermore, in the first embodiment of the present invention, channel estimation is performed on the preset cache auxiliary system, specifically as follows:

[0094] Obtain the first test pilot sequence and the second test pilot sequence;

[0095] The first test pilot sequence is transmitted from the source node of the buffer auxiliary system to the relay node, and the second test pilot sequence is transmitted from the relay node of the buffer auxiliary system to the destination node to complete the channel estimation.

[0096] In the first embodiment of the present invention, before transmitting data in each time slot, a pilot sequence needs to be transmitted first for channel estimation. The pilot sequence is a signal known to both the transmitting end and the receiving end. The first test pilot sequence and the second test pilot sequence can be two identical pilot sequences or two different pilot sequences. The difference can be manifested in different transmission power or different number of pilots.

[0097] Channel estimation using pilot sequences is a simple and easy-to-implement method.

[0098] Further, in the first embodiment of the present invention, obtaining the first channel state information and the first channel estimation error data of the first link, and the second channel state information and the second channel estimation error data of the second link, specifically involves:

[0099] The first channel estimation error data includes the variance of the first channel estimation error; the second channel estimation error data includes the variance of the second channel estimation error.

[0100] The methods for obtaining the variance of the first channel estimation error and the variance of the second channel estimation error are as follows:

[0101] The number of pilots and the transmit power of the first test pilot sequence and the second test pilot sequence are obtained respectively;

[0102] Obtain the additive white Gaussian noise power of the relay node and the additive white Gaussian noise power of the destination node, respectively;

[0103] The variance of the first channel estimation error is obtained by dividing the additive white Gaussian noise power of the relay node by the product of the number of pilots and the transmit power of the first test pilot sequence.

[0104] The variance of the second channel estimation error is obtained by dividing the additive white Gaussian noise power of the target node by the product of the number of pilots and the transmit power of the second test pilot sequence.

[0105] In the first embodiment of the present invention, after channel estimation, channel state information and channel estimation error data can be obtained. The impact of imperfect channel is caused by channel estimation error. Therefore, the selection of transmission power and link needs to be calculated using the variance of channel estimation error. The variance of channel estimation error is linked with the number of pilots and signal-to-noise ratio to select the optimal transmission power and link in order to improve the throughput when transmitting data.

[0106] In the first embodiment of the present invention, see Figure 2 The statistical channel model of the cache-assisted system can be expressed as:

[0107] h(t)=h'(t)+e h (t)

[0108] g(t)=g'(t)+e g (t)

[0109] Where h'(t) is the first channel state information; e h (t) represents the first channel estimation error; g'(t) represents the second channel state information; e g (t) represents the second channel estimation error.

[0110] The formula for calculating the variance of the first channel estimation error is:

[0111]

[0112] The formula for calculating the variance of the first channel estimation error is:

[0113]

[0114] in, It is the variance of the first channel estimation error; It is the additive white Gaussian noise power of the relay node; Nt1 N is the number of pilots in the first test pilot sequence; t1 This is the first test pilot sequence transmit power; It is the variance of the second channel estimation error; N is the additive white Gaussian noise power at the target node; t2 It is the number of pilots in the second test pilot sequence; P t2 The second test pilot sequence transmit power.

[0115] Step 102: In the current time slot, obtain the first energy state information from the source node, and obtain the second energy state information and cache state information from the relay node.

[0116] Furthermore, in the first embodiment of the present invention, obtaining first energy state information from the source node, and obtaining second energy state information and buffer state information from the relay node in the current time slot, further includes:

[0117] In the next time slot of the current time slot, the first energy state information, the second energy state information, and the cache state information are updated;

[0118] In the next time slot following the current time slot, the specific formula for updating the first energy state information is as follows:

[0119]

[0120] In the next time slot after the current time slot, the specific formula for updating the second energy state information is as follows:

[0121]

[0122] In the next time slot after the current time slot, the specific formula for updating the cache state information is as follows:

[0123] Q(t+1)=max{Q(t)―b(t),0}+a(t)

[0124] Where β is the proportion of the test data sequence to the test transmission sequence; T is the duration of the current time slot; E s (t+1) is the first energy state information of the next time slot after the current time slot; E s (t) represents the first energy state information of the current time slot; m1(t) represents the first link; P s (t) is the first optimal transmission power; It is the long-term average transmit power of the source node; E r (t+1) is the second energy state information of the next time slot after the current time slot; E r (t) represents the second energy state information of the current time slot; m2(t) represents the second link; P r(t) is the second optimal transmission power; Q(t+1) is the long-term average transmit power of the destination node; Q(t+1) is the buffer status information of the next time slot of the current time slot; Q(t) is the buffer status information of the current time slot; b(t) is the throughput of the relay node forwarding; a(t) is the throughput of the relay node receiving.

[0125] Step 103: Send the acquired first channel state information, first channel estimation error data, second channel state information, second channel estimation error data, first energy state information, second energy state information, and buffer state information to the preset decision node.

[0126] Furthermore, in the first embodiment of the present invention, the preset decision node is specifically:

[0127] The decision node is determined from the reserve nodes according to the transmission requirements; wherein, the reserve nodes include the source node, relay node and destination node of the cache auxiliary system.

[0128] Further, in the first embodiment of the present invention, after determining the optimal transmission power with the highest throughput and the lowest Lyapunov drift of the current time slot as the transmission power of the current time slot, and determining the link corresponding to the transmission power of the current time slot as the transmission link of the current time slot, the method further includes:

[0129] A notification instruction is generated based on the transmission power of the current time slot and the transmission link of the current time slot;

[0130] Using the decision node, the notification instruction is sent to all nodes of the caching assistance system except the decision node.

[0131] In the first embodiment of the present invention, all acquired data will be transmitted to the decision node. The decision node can be one of the source node, relay node and destination node. Based on the collected information, the decision node can use the Lyapunov optimization framework to determine the power allocation scheme and adaptive mode selection scheme of the source node and relay node. After determining the data transmission scheme, the scheme can be notified to all nodes except the decision node in order to achieve the goal of maximizing throughput under imperfect channel conditions.

[0132] Step 104: Using the Lyapunov optimization framework, calculate the first optimal transmission power for the first link and the second optimal transmission power for the second link at the decision node.

[0133] Furthermore, in the first embodiment of the present invention, the Lyapunov optimization framework is used to calculate the first optimal transmission power corresponding to the first link and the second optimal transmission power corresponding to the second link at the decision node, specifically as follows:

[0134] Obtain the ratio of the test data sequence to the test transmission sequence;

[0135] Based on the buffer state information, the first energy state information, the second energy state information, the first channel state information, the second channel state information, the variance of the first channel estimation error, and the variance of the second channel estimation error, the first formula and the second formula are solved respectively to obtain the first optimal transmission power and the second optimal transmission power.

[0136] Specifically, the first formula is:

[0137]

[0138]

[0139] Among them, P s Q(t) is the first transmission power; Q(t) is the buffer state information; h'(t) is the first channel state information; It is the variance of the first channel estimation error; β is the additive white Gaussian noise power of the relay node; β is the proportion coefficient of the test data sequence to the test transmission sequence; E s (t) represents the first energy state information; t is the maximum transmit power of the source node; T is the current time slot; B is the duration of the current time slot; V is the channel bandwidth of the buffer auxiliary system; μ1 is a preset constant; and μ1 is a preset non-negative constant.

[0140] The second formula is specifically as follows:

[0141]

[0142]

[0143] Among them, P r (t) represents the second transmission power; Q(t) represents the buffer state information; g'(t) represents the second channel state information; It is the variance of the second channel estimation error; β is the additive white Gaussian noise power at the destination node; β is the proportion coefficient of the test data sequence to the test transmission sequence; E r (t) represents the second energy state information; t is the maximum transmit power of the relay node; t is the current time slot; T is the duration of the current time slot; B is the channel bandwidth of the buffer auxiliary system; V is a preset constant; μ2 is a preset non-negative constant.

[0144] In the first embodiment of the present invention, two optimization problems are set using the Lyapunov optimization framework. By using the channel state information and channel estimation error data obtained through channel estimation, as well as the energy state information and buffer state information obtained from the source node and relay node, the first optimal transmission power and the second optimal transmission power corresponding to the two optimization problems can be calculated. The μ1, μ2 and V set in the formula are constants set in advance according to the actual situation, which can balance the relationship between queue stability and throughput maximization and improve the accuracy of calculation.

[0145] Step 105: Calculate the throughput and Lyapunov drift of the current time slot corresponding to the first optimal transmission power and the second optimal transmission power, respectively.

[0146] Step 106: Determine the optimal transmission power that has the highest throughput and the lowest Lyapunov drift in the current time slot as the transmission power of the current time slot, and determine the link corresponding to the transmission power of the current time slot as the transmission link of the current time slot.

[0147] Step 107: Perform data transmission based on the transmission power of the current time slot and the transmission link of the current time slot.

[0148] In the first embodiment of the present invention, given the current queue state, the expected changes in the relay's buffered data queue, the relay's energy queue, and the source's energy queue within a time slot can be reflected in the Lyapunov drift. Therefore, to maximize throughput while maintaining queue stability under imperfect channel conditions, the transmission power of the current time slot must consider not only the throughput but also the Lyapunov drift. After obtaining the first optimal transmission power corresponding to the first link and the second optimal transmission power corresponding to the second link, the optimal transmission power with the highest throughput and lowest Lyapunov drift for the current time slot is determined as the transmission power of the current time slot, and the link corresponding to the transmission power of the current time slot is determined as the transmission link for the current time slot. After selecting the transmission power and transmission link for the current time slot, data transmission is performed, which can achieve the goal of maximizing throughput under imperfect channel conditions while maintaining queue stability.

[0149] As an example of the first embodiment of the present invention, see Figure 3This is a flowchart illustrating another embodiment of the data transmission method based on imperfect channels and buffer assistance provided by the present invention. An imperfect channel is constructed based on a statistical channel model using maximum likelihood estimation. Then, a three-node communication system with buffer assistance and a single relay is constructed under the imperfect channel to form a system model. Channel state information and channel estimation error data are obtained through channel estimation. Energy state information and buffer state information are obtained at the source node and relay node. According to a predefined power allocation scheme, these data are used to obtain two optimal transmit powers at the source node and relay node in the system using optimization decomposition and convex optimization methods. Then, according to a predefined mode selection scheme, the throughput under the two optimal transmit powers and the Lyapunov drift of the current time slot are compared to select the optimal transmission power and optimal transmission link for the current time slot to form the optimal transmission scheme. Finally, data transmission is performed based on the optimal transmission scheme, achieving the goal of maximizing throughput under imperfect channels.

[0150] In summary, the first embodiment of this invention provides a data transmission method based on imperfect channels and buffer assistance. Before data transmission, a pilot sequence is transmitted to perform channel estimation on the buffer-assisted system constructed under imperfect channels, obtaining channel state information and channel estimation error data. Energy state information and buffer state information are obtained at the source node and relay node. Based on the obtained information, the first optimal transmission power corresponding to the first link and the second optimal transmission power corresponding to the second link are calculated using the Lyapunov optimization framework. The optimal transmission power with the maximum throughput and the minimum Lyapunov drift in the current time slot is determined as the transmission power of the current time slot, and the link corresponding to the transmission power of the current time slot is determined as the transmission link of the current time slot. Data transmission is then performed. This invention can fully utilize channel resources and improve the throughput performance and robustness of the system while maintaining queue stability.

[0151] Example 2

[0152] See Figure 4 This is a schematic diagram of an embodiment of the data transmission device based on imperfect channels and buffer assistance provided by the present invention. The device includes a channel estimation module 201, an acquisition module 202, a transmission module 203, a first calculation module 204, a second calculation module 205, a determination module 206, and a data transmission module 207.

[0153] The channel estimation module 201 is used to perform channel estimation on a preset buffering auxiliary system, and to obtain the first channel state information and first channel estimation error data of the first link, as well as the second channel state information and second channel estimation error data of the second link; wherein, the buffering auxiliary system is constructed based on an imperfect channel and includes a source node, a relay node and a destination node; the first link is the transmission path from the source node to the relay node; the second link is the transmission path from the relay node to the destination node;

[0154] The acquisition module 202 is used to acquire first energy state information from the source node, and second energy state information and cache state information from the relay node in the current time slot.

[0155] The sending module 203 is used to send the acquired first channel state information, first channel estimation error data, second channel state information, second channel estimation error data, first energy state information, second energy state information, and buffer state information to a preset decision node;

[0156] The first calculation module 204 is used to calculate the first optimal transmission power corresponding to the first link and the second optimal transmission power corresponding to the second link at the decision node using the Lyapunov optimization framework.

[0157] The second calculation module 205 is used to calculate the throughput corresponding to the first optimal transmission power and the second optimal transmission power, and the Lyapunov drift of the current time slot, respectively.

[0158] The determination module 206 is used to determine the optimal transmission power with the maximum throughput and the minimum Lyapunov drift of the current time slot as the transmission power of the current time slot, and to determine the link corresponding to the transmission power of the current time slot as the transmission link of the current time slot.

[0159] The data transmission module 207 is used to transmit data according to the transmission power of the current time slot and the transmission link of the current time slot.

[0160] Furthermore, in the second embodiment of the present invention, the caching assistance system is constructed based on an imperfect channel and includes a source node, a relay node, and a destination node, specifically:

[0161] An imperfect channel is constructed based on a statistical channel model using maximum likelihood estimation.

[0162] Building a cache-assisted system under imperfect channels;

[0163] The cache assistance system includes source nodes, relay nodes, and destination nodes;

[0164] The relay node uses a half-duplex decoding and forwarding method and has a caching function.

[0165] Furthermore, in the second embodiment of the present invention, the channel estimation module 201 includes a sequence acquisition unit and a transmission unit;

[0166] The sequence acquisition unit is used to acquire the first test pilot sequence and the second test pilot sequence;

[0167] The transmission unit is used to transmit the first test pilot sequence from the source node of the buffer auxiliary system to the relay node, and to transmit the second test pilot sequence from the relay node of the buffer auxiliary system to the destination node, thereby completing channel estimation.

[0168] Furthermore, in the second embodiment of the present invention, obtaining the first channel state information and the first channel estimation error data of the first link, and the second channel state information and the second channel estimation error data of the second link, specifically involves:

[0169] The first channel estimation error data includes the variance of the first channel estimation error; the second channel estimation error data includes the variance of the second channel estimation error.

[0170] The methods for obtaining the variance of the first channel estimation error and the variance of the second channel estimation error are as follows:

[0171] The number of pilots and the transmit power of the first test pilot sequence and the second test pilot sequence are obtained respectively;

[0172] Obtain the additive white Gaussian noise power of the relay node and the additive white Gaussian noise power of the destination node, respectively;

[0173] The variance of the first channel estimation error is obtained by dividing the additive white Gaussian noise power of the relay node by the product of the number of pilots and the transmit power of the first test pilot sequence.

[0174] The variance of the second channel estimation error is obtained by dividing the additive white Gaussian noise power of the target node by the product of the number of pilots and the transmit power of the second test pilot sequence.

[0175] Furthermore, in the second embodiment of the present invention, the first calculation module 204 includes: a ratio acquisition unit and a calculation unit;

[0176] The ratio acquisition unit is used to obtain the ratio coefficient of the test data sequence to the test transmission sequence;

[0177] The calculation unit is used to solve the first formula and the second formula respectively to obtain the first optimal transmission power and the second optimal transmission power based on the buffer state information, the first energy state information, the second energy state information, the first channel state information, the second channel state information, the variance of the first channel estimation error and the variance of the second channel estimation error.

[0178] Specifically, the first formula is:

[0179]

[0180]

[0181] Among them, P s Q(t) is the first transmission power; Q(t) is the buffer state information; h'(t) is the first channel state information; It is the variance of the first channel estimation error; β is the additive white Gaussian noise power of the relay node; β is the proportion coefficient of the test data sequence to the test transmission sequence; E s (t) represents the first energy state information; t is the maximum transmit power of the source node; T is the current time slot; B is the duration of the current time slot; V is the channel bandwidth of the buffer auxiliary system; μ1 is a preset constant; and μ1 is a preset non-negative constant.

[0182] The second formula is specifically as follows:

[0183]

[0184]

[0185] Among them, P r (t) represents the second transmission power; Q(t) represents the buffer state information; g'(t) represents the second channel state information; It is the variance of the second channel estimation error; β is the additive white Gaussian noise power at the destination node; β is the proportion coefficient of the test data sequence to the test transmission sequence; E r (t) represents the second energy state information; t is the maximum transmit power of the relay node; T is the current time slot; B is the duration of the current time slot; V is the channel bandwidth of the buffer-assisted system; V is a preset constant; μ2 is a preset non-negative constant.

[0186] Furthermore, in the second embodiment of the present invention, the preset decision node is specifically:

[0187] The decision node is determined from the reserve nodes according to the transmission requirements; wherein, the reserve nodes include the source node, relay node and destination node of the cache auxiliary system.

[0188] Furthermore, in the second embodiment of the present invention, obtaining first energy state information from the source node, and obtaining second energy state information and buffer state information from the relay node in the current time slot, further includes:

[0189] In the next time slot of the current time slot, the first energy state information, the second energy state information, and the cache state information are updated;

[0190] In the next time slot following the current time slot, the specific formula for updating the first energy state information is as follows:

[0191]

[0192] In the next time slot after the current time slot, the specific formula for updating the second energy state information is as follows:

[0193]

[0194] In the next time slot after the current time slot, the specific formula for updating the cache state information is as follows:

[0195] Q(t+1)=max{Q(t)―b(t),0}+a(t)

[0196] Where β is the proportion of the test data sequence to the test transmission sequence; T is the duration of the current time slot; E s (t+1) is the first energy state information of the next time slot after the current time slot; E s (t) represents the first energy state information of the current time slot; m1(t) represents the first link; P s (t) is the first optimal transmission power; It is the long-term average transmit power of the source node; E r (t+1) is the second energy state information of the next time slot after the current time slot; E r (t) represents the second energy state information of the current time slot; m2(t) represents the second link; P r (t) is the second optimal transmission power; Q(t+1) is the long-term average transmit power of the destination node; Q(t+1) is the buffer status information of the next time slot of the current time slot; Q(t) is the buffer status information of the current time slot; b(t) is the throughput of the relay node forwarding; a(t) is the throughput of the relay node receiving.

[0197] Furthermore, in the second embodiment of the present invention, after determining the optimal transmission power with the highest throughput and the lowest Lyapunov drift of the current time slot as the transmission power of the current time slot, and determining the link corresponding to the transmission power of the current time slot as the transmission link of the current time slot, the method further includes:

[0198] A notification instruction is generated based on the transmission power of the current time slot and the transmission link of the current time slot;

[0199] Using the decision node, the notification instruction is sent to all nodes of the caching assistance system except the decision node.

[0200] In summary, the second embodiment of the present invention provides a data transmission device based on imperfect channels and buffer assistance. Based on the organic integration of modules, a pilot sequence is transmitted before data transmission to perform channel estimation on the buffer-assisted system constructed under imperfect channels, obtaining channel state information and channel estimation error data. Energy state information and buffer state information are obtained at the source node and relay node. Based on the obtained information, the first optimal transmission power corresponding to the first link and the second optimal transmission power corresponding to the second link are calculated using the Lyapunov optimization framework. The optimal transmission power with the highest throughput and the smallest Lyapunov drift in the current time slot is determined as the transmission power of the current time slot, and the link corresponding to the transmission power of the current time slot is determined as the transmission link of the current time slot for data transmission. The present invention can fully utilize channel resources and improve the throughput performance and robustness of the system while maintaining queue stability.

[0201] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A data transmission method based on imperfect channels and buffer assistance, characterized in that, include: Channel estimation is performed on a preset buffering auxiliary system to obtain the first channel state information and first channel estimation error data of the first link, as well as the second channel state information and second channel estimation error data of the second link; wherein, the buffering auxiliary system is constructed based on an imperfect channel and includes a source node, a relay node and a destination node; the first link is the transmission path from the source node to the relay node; the second link is the transmission path from the relay node to the destination node; In the current time slot, first energy state information is obtained from the source node, and second energy state information and cache state information are obtained from the relay node; The acquired first channel state information, first channel estimation error data, second channel state information, second channel estimation error data, first energy state information, second energy state information, and buffer state information are sent to the preset decision node. Using the Lyapunov optimization framework, the first optimal transmission power for the first link and the second optimal transmission power for the second link are calculated at the decision node, respectively. Calculate the throughput and Lyapunov drift of the current time slot corresponding to the first and second optimal transmission powers, respectively. The optimal transmission power that maximizes throughput and minimizes Lyapunov drift in the current time slot is determined as the transmission power of the current time slot, and the link corresponding to the transmission power of the current time slot is determined as the transmission link of the current time slot. Data transmission is performed based on the transmission power and transmission link of the current time slot; Specifically, the Lyapunov optimization framework is used to calculate the first optimal transmission power for the first link and the second optimal transmission power for the second link at the decision node, respectively: Obtain the ratio of the test data sequence to the test transmission sequence; Based on the buffer state information, the first energy state information, the second energy state information, the first channel state information, the second channel state information, the variance of the first channel estimation error, and the variance of the second channel estimation error, the first formula and the second formula are solved respectively to obtain the first optimal transmission power and the second optimal transmission power. Specifically, the first formula is: in, It is the first transmission power; It is cached state information; It is the first channel state information; It is the variance of the first channel estimation error; β is the additive white Gaussian noise power of the relay node; β is the ratio coefficient of the test data sequence to the test transmission sequence. It is the first energy state information; t is the maximum transmit power of the source node; T is the current time slot; B is the duration of the current time slot; V is the channel bandwidth of the buffer auxiliary system; and V is a preset constant. It is a pre-defined nonnegative constant; Specifically, the second formula is as follows: in, It is the second transmission power; It is cached state information; It is the second channel state information; It is the variance of the second channel estimation error; β is the additive white Gaussian noise power at the destination node; β is the ratio coefficient of the test data sequence to the test transmission sequence. It is the second energy state information; t is the maximum transmit power of the relay node; T is the current time slot; B is the duration of the current time slot; V is the channel bandwidth of the buffer auxiliary system; and V is a preset constant. It is a pre-defined non-negative constant.

2. The data transmission method based on imperfect channels and buffer assistance according to claim 1, characterized in that, The cache assistance system is built on an imperfect channel and includes a source node, a relay node, and a destination node, specifically: An imperfect channel is constructed based on a statistical channel model using maximum likelihood estimation. Building a cache-assisted system under imperfect channels; The cache assistance system includes source nodes, relay nodes, and destination nodes; The relay node uses a half-duplex decoding and forwarding method and has a caching function.

3. The data transmission method based on imperfect channels and buffer assistance according to claim 1, characterized in that, The channel estimation for the preset cache auxiliary system specifically includes: Obtain the first test pilot sequence and the second test pilot sequence; The first test pilot sequence is transmitted from the source node of the buffer auxiliary system to the relay node, and the second test pilot sequence is transmitted from the relay node of the buffer auxiliary system to the destination node to complete the channel estimation.

4. The data transmission method based on imperfect channels and buffer assistance according to claim 1, characterized in that, The acquisition of the first channel state information and first channel estimation error data of the first link, and the second channel state information and second channel estimation error data of the second link, specifically includes: The first channel estimation error data includes the variance of the first channel estimation error; the second channel estimation error data includes the variance of the second channel estimation error. The methods for obtaining the variance of the first channel estimation error and the variance of the second channel estimation error are as follows: The number of pilots and the transmit power of the first test pilot sequence and the second test pilot sequence are obtained respectively; Obtain the additive white Gaussian noise power of the relay node and the additive white Gaussian noise power of the destination node, respectively; The variance of the first channel estimation error is obtained by dividing the additive white Gaussian noise power of the relay node by the product of the number of pilots and the transmit power of the first test pilot sequence. The variance of the second channel estimation error is obtained by dividing the additive white Gaussian noise power of the target node by the product of the number of pilots and the transmit power of the second test pilot sequence.

5. The data transmission method based on imperfect channels and buffer assistance according to claim 1, characterized in that, The preset decision node is specifically: The decision node is determined from the reserve nodes according to the transmission requirements; wherein, the reserve nodes include the source node, relay node and destination node of the cache auxiliary system.

6. The data transmission method based on imperfect channels and buffer assistance according to claim 1, characterized in that, The step of obtaining first energy state information from the source node, second energy state information and cache state information from the relay node in the current time slot further includes: In the next time slot of the current time slot, the first energy state information, the second energy state information, and the cache state information are updated; In the next time slot following the current time slot, the specific formula for updating the first energy state information is as follows: In the next time slot after the current time slot, the specific formula for updating the second energy state information is as follows: In the next time slot after the current time slot, the specific formula for updating the cache state information is as follows: Where β is the proportion of the test data sequence to the test transmission sequence; T is the duration of the current time slot; It is the first energy state information of the next time slot after the current time slot; It is the first energy state information of the current time slot; It is the first link; It is the first optimal transmission power; It is the long-term average transmit power of the source node; It is the second energy state information of the next time slot after the current time slot; It is the second energy state information of the current time slot; It is the second link; It is the second optimal transmission power; It is the long-term average transmit power of the target node; It is the cache status information for the next time slot of the current time slot; This is the cache status information for the current time slot; This refers to the throughput of relay nodes. This is the throughput received by the relay node.

7. The data transmission method based on imperfect channels and buffer assistance according to claim 1, characterized in that, After determining the optimal transmission power that maximizes throughput and minimizes Lyapunov drift in the current time slot as the transmission power of the current time slot, and determining the link corresponding to the transmission power of the current time slot as the transmission link of the current time slot, the method further includes: A notification instruction is generated based on the transmission power of the current time slot and the transmission link of the current time slot; Using the decision node, the notification instruction is sent to all nodes of the caching assistance system except the decision node.

8. A data transmission device based on imperfect channels and buffer assistance, characterized in that, include: The system includes a channel estimation module, an acquisition module, a transmission module, a first calculation module, a second calculation module, a determination module, and a data transmission module. The channel estimation module is used to perform channel estimation on the preset buffering auxiliary system, and to obtain the first channel state information and first channel estimation error data of the first link, as well as the second channel state information and second channel estimation error data of the second link; wherein, the buffering auxiliary system is constructed based on an imperfect channel and includes a source node, a relay node and a destination node; the first link is the transmission path from the source node to the relay node; the second link is the transmission path from the relay node to the destination node; The acquisition module is used to acquire first energy state information from the source node, and second energy state information and cache state information from the relay node in the current time slot. The sending module is used to send the acquired first channel state information, first channel estimation error data, second channel state information, second channel estimation error data, first energy state information, second energy state information, and buffer state information to a preset decision node; The first calculation module is used to calculate the first optimal transmission power corresponding to the first link and the second optimal transmission power corresponding to the second link at the decision node using the Lyapunov optimization framework. The second calculation module is used to calculate the throughput corresponding to the first optimal transmission power and the second optimal transmission power, and the Lyapunov drift of the current time slot, respectively. The determining module is used to determine the optimal transmission power with the maximum throughput and the minimum Lyapunov drift of the current time slot as the transmission power of the current time slot, and to determine the link corresponding to the transmission power of the current time slot as the transmission link of the current time slot. The data transmission module is used to transmit data according to the transmission power of the current time slot and the transmission link of the current time slot; The first calculation module includes: a ratio acquisition unit and a calculation unit; The ratio acquisition unit is used to acquire the ratio coefficient of the test data sequence to the test transmission sequence; The calculation unit is used to solve the first formula and the second formula respectively to obtain the first optimal transmission power and the second optimal transmission power based on the buffer state information, the first energy state information, the second energy state information, the first channel state information, the second channel state information, the variance of the first channel estimation error and the variance of the second channel estimation error. Specifically, the first formula is: in, It is the first transmission power; It is cached state information; It is the first channel state information; It is the variance of the first channel estimation error; β is the additive white Gaussian noise power of the relay node; β is the ratio coefficient of the test data sequence to the test transmission sequence. It is the first energy state information; t is the maximum transmit power of the source node; T is the current time slot; B is the duration of the current time slot; V is the channel bandwidth of the buffer auxiliary system; and V is a preset constant. It is a pre-defined nonnegative constant; Specifically, the second formula is as follows: in, It is the second transmission power; It is cached state information; It is the second channel state information; It is the variance of the second channel estimation error; β is the additive white Gaussian noise power at the destination node; β is the ratio coefficient of the test data sequence to the test transmission sequence. It is the second energy state information; t is the maximum transmit power of the relay node; T is the current time slot; B is the duration of the current time slot; V is the channel bandwidth of the buffer auxiliary system; and V is a preset constant. It is a pre-defined non-negative constant.

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