CN103826232B - Recognize the adaptive optimization method and system of bilateral relay network - Google Patents

Abstract

The present invention proposes an adaptive optimization method for a cognitive two-way relay network, including: setting the interference temperature of the primary user node and the interruption probability threshold value of the secondary user node; Channel state information; calculate the outage probability of the cognitive two-way relay network through the preset outage probability rapid assessment method; compare the outage probability and the outage probability threshold value; if the outage probability is less than the outage probability threshold value, pass the cognitive two-way relay The network transmits data, otherwise the transmission rate of the cognitive two-way relay network is adjusted to reduce the outage probability of the cognitive two-way relay network. The adaptive optimization method for the cognitive two-way relay network according to the embodiment of the present invention can effectively guarantee the data transmission reliability of the cognitive two-way relay network. The invention also proposes an adaptive optimization system for cognitive two-way relay network.

Description

Cognitive two-way relay network adaptive optimization method and system

technical field

The invention relates to the technical field of design communication, in particular to an adaptive optimization method and system for a cognitive two-way relay network.

Background technique

Cognitive radio is one of the key technologies for future wireless networks. Through spectrum sharing, cognitive radio can greatly improve spectrum efficiency, which is an effective measure to alleviate the shortage of spectrum resources. A coexistence spectrum sharing system, under the premise of ensuring the quality of service (QoS) of the primary user, no matter whether the spectrum is Occupied by the primary user, the secondary users can access the authorized network. However, since the transmission power of the secondary user is strictly limited, it is difficult to guarantee the transmission quality of the secondary user. How to improve the performance of sub-users has become a research hotspot.

Relay technology can effectively expand signal coverage and improve transmission quality, and is one of the key technologies of the fourth generation (4G) wireless communication. Compared with the traditional one-way relay, the two-way relay technology can further improve the spectrum efficiency. Therefore, combining two-way relay technology with cognitive radio becomes a reliable means to improve the performance of secondary users.

Cognitive two-way relay networks are expected to emerge in future wireless communication standards. The cognitive two-way relay network mainly improves the utilization efficiency of spectrum resources through spectrum sharing, and at the same time introduces two-way relay technology to improve the communication quality of secondary users. The introduction of two-way relay technology brings two benefits: 1. Compared with traditional one-way relay, it can further improve spectrum efficiency; 2. It can guarantee the transmission quality of secondary users. However, there are still few methods for optimizing the performance of cognitive bidirectional relay networks, which is a problem that needs to be solved.

Contents of the invention

The present invention aims to solve at least one of the above-mentioned technical problems.

Therefore, the object of the present invention is to propose an adaptive optimization method for a cognitive two-way relay network, which can effectively ensure the data transmission reliability of the cognitive two-way relay network.

The invention also proposes an adaptive optimization system for cognitive two-way relay network.

In order to achieve the above object, the embodiment of the first aspect of the present invention provides an adaptive optimization method for a cognitive two-way relay network, the cognitive two-way relay network includes a plurality of nodes, and the plurality of nodes includes at least a A user node, a secondary user node and a relay station node, the method includes the following steps: setting the interference temperature of the primary user node and the interruption probability threshold value of the secondary user node; estimating and obtaining the cognitive two-way relay network The channel state information of each node in the network; by using the channel state information of each node to calculate the outage probability of the cognitive two-way relay network through the preset outage probability rapid evaluation method; compare the outage probability with the outage probability gate limit; and if the outage probability is less than the outage probability threshold, transmit data through the cognitive two-way relay network, otherwise adjust the transmission rate of the cognitive two-way relay network to reduce the cognitive Outage probability for a two-way relay network.

According to the method of the embodiment of the present invention, it can be compared with the transmission quality requirements preset by the network. If the estimated interruption probability exceeds the design requirements of the network, the interruption probability of the system can be reduced by adjusting the transmission rate of the secondary user in real time. Ensure the reliability of network transmission.

In addition, the adaptive optimization method for a cognitive two-way relay network according to the above-mentioned embodiments of the present invention may also have the following additional technical features:

In some examples, the calculation of the outage probability of the cognitive two-way relay network by using the channel state information of each node by using the preset outage probability rapid assessment method specifically includes: the preset number of time slots The outage probability is evaluated; the outage probability of the cognitive two-way relay network is calculated according to the evaluation result of the outage probability of the preset number of time slots.

In some examples, the preset number is three.

In some examples, the cognitive two-way relay network is a cognitive two-way relay network using a time-division broadcast transmission mode.

In some examples, the secondary user node is divided into three equal time slots when used for data transmission, and uses a time-division broadcast mode for data transmission, and the relay station node uses a decoding and forwarding mode when used for data transmission.

An embodiment of the second aspect of the present invention is an adaptive optimization system for a cognitive two-way relay network. The cognitive two-way relay network includes a plurality of nodes, and the plurality of nodes includes at least a primary user node, a secondary user node, and a The relay station node, the system includes: a setting module, used to set the interference temperature of the primary user node and the outage probability threshold value of the secondary user node; an estimation module, used to estimate and obtain the cognitive bidirectional The channel state information of each node in the relay network; the outage probability calculation module is used to calculate the outage probability of the cognitive two-way relay network by using the channel state information of each node through a preset outage probability rapid assessment method; and comparing A module for comparing the outage probability with the outage probability threshold; a transmission control module for controlling the cognitive two-way relay network to transmit data when the outage probability is less than the outage probability threshold , otherwise adjust the transmission rate of the cognitive two-way relay network to reduce the outage probability of the cognitive two-way relay network.

According to the system of the embodiment of the present invention, it can be compared with the transmission quality requirements preset by the network. If the estimated interruption probability exceeds the design requirements of the network, the interruption probability of the system can be reduced by adjusting the transmission rate of the secondary user in real time. Ensure the reliability of network transmission.

In addition, the adaptive optimization system for a cognitive two-way relay network according to the above-mentioned embodiments of the present invention may also have the following additional technical features

In some examples, the outage probability calculation module is configured to: evaluate the outage probability of a preset number of time slots, and calculate the outage probability according to the evaluation results of the preset number of time slots. Cognitive Outage Probability in Bidirectional Relay Networks.

In some examples, the preset number is three.

In some examples, the cognitive two-way relay network is a cognitive two-way relay network using a time-division broadcast transmission mode.

In some examples, the secondary user node is divided into three equal time slots when used for data transmission, and uses a time-division broadcast mode for data transmission, and the relay station node uses a decoding and forwarding mode when used for data transmission.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 is a flowchart of a cognitive two-way relay network adaptive optimization method according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of data transmission of a cognitive two-way relay network in a cognitive two-way relay network adaptive optimization method according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of the simulation results of the rapid evaluation of the outage probability of the cognitive two-way relay network adaptive optimization method according to an embodiment of the present invention; and

Fig. 4 is a structural block diagram of a cognitive two-way relay network adaptive optimization system according to an embodiment of the present invention.

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", " The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner" and "outer" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and Simplified descriptions, rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus should not be construed as limiting the invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and should not be understood as indicating or implying relative importance.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

These and other aspects of embodiments of the invention will become apparent with reference to the following description and drawings. In these descriptions and drawings, some specific implementations of the embodiments of the present invention are specifically disclosed to represent some ways of implementing the principles of the embodiments of the present invention, but it should be understood that the scope of the embodiments of the present invention is not limited by this limit. On the contrary, the embodiments of the present invention include all changes, modifications and equivalents coming within the spirit and scope of the appended claims.

The method and system for adaptive optimization of a cognitive two-way relay network according to embodiments of the present invention will be described below with reference to the accompanying drawings.

Fig. 1 is a flow chart of a method for adaptive optimization of a cognitive two-way relay network according to an embodiment of the present invention. Among them, as shown in Figure 2, the cognitive two-way relay network includes multiple nodes, and the multiple nodes at least include primary user node C (referred to as primary user), secondary user nodes A and B (referred to as secondary user), and relay station node T ( Referred to as the relay station). As shown in FIG. 1, the cognitive two-way relay network adaptive optimization method according to an embodiment of the present invention includes the following steps:

Step S101: Setting the interference temperature of the primary user node and the outage probability threshold value of the secondary user node;

Step S102: Estimate and obtain the channel state information of each node in the cognitive two-way relay network.

Step S103: Calculate the outage probability of the cognitive two-way relay network by using the channel state information of each node through a preset outage probability rapid assessment method.

Specifically, the outage probability of the cognitive two-way relay network is calculated by using the channel state information of each node through a preset outage probability rapid assessment method, specifically including:

S31: Evaluate the outage probability of a preset number of time slots. Wherein, the preset number is 3.

S32: Calculate and obtain the outage probability of the cognitive two-way relay network according to the evaluation results of the outage probabilities of the preset number of time slots.

Step S104: Compare the outage probability with the outage probability threshold.

Step S105: If the outage probability is less than the outage probability threshold, transmit data through the cognitive two-way relay network.

Step S106: If the outage probability is not less than the outage probability threshold, adjust the transmission rate of the cognitive two-way relay network to reduce the outage probability of the cognitive two-way relay network.

In an embodiment of the present invention, the cognitive two-way relay network is a cognitive two-way relay network using a time-division broadcast transmission mode.

In one embodiment of the present invention, the secondary user node is divided into three equal time slots when used in the data transmission process, and uses the time-division broadcast mode for data transmission. When the relay station node is used in the data transmission process, it uses decoding and forwarding model.

Specifically, each node in the cognitive two-way relay network mentioned in the cognitive two-way relay network adaptive optimization method of the embodiment of the present invention includes but is not limited to: primary user (ie primary user node), secondary user (ie secondary user nodes) and relay stations (i.e. relay station nodes). As a specific example, as shown in FIG. 2 , it includes one primary user C, two secondary users (that is, secondary user A and secondary user B) and one relay station T.

The basic idea of the self-adaptive optimization method for the cognitive two-way relay network in the embodiment of the present invention is: first, an interference temperature is preset at the main user end, each node can obtain channel state information, and the relay station adopts a decoding and forwarding (DF) method. The secondary user adopts time division broadcasting (TDBC) mode, and in the transmission process of three equal time slots, the channels are all Rayleigh fading channels. The accurate outage probability is obtained through the preset outage probability evaluation method in the embodiment of the present invention, and on this basis, the transmission rate of information is adjusted in real time, the outage probability is reduced, and the network performance is improved.

For example, assuming that each node is configured with a single antenna, in the cognitive two-way relay network, according to the TDBC protocol, the transmission process is divided into three equal time slots. As shown in Figure 2, C represents the primary user, A and B represent two secondary users, and T represents the relay station. In the example, terminal C presets an interference temperature I _th , and A, B, and T must meet the interference limit for the primary user during transmission. That is, the maximum transmission power of A, B and T is with

In the first two time slots of the transmission process, A and B send signals respectively, and the received signal at the relay station T can be expressed as:

Where x _A and x _B are the sending signals of A and B respectively, h _ij ((i,j)∈{(A,T),(B,T),(A,C),(B,C),( T, A), (T, B), (T, C)}), n _T1 and n _T2 are the Gaussian white noise of the first two time slot channels respectively.

In the third time slot of the transmission process, T re-encodes the previously successfully decoded signal, and then broadcasts it. The received signals at terminals A and B are

Among them, l∈{A,B}, x _T are the transmitted signals of T, and n _l3 is the Gaussian white noise at the receiving end.

According to the definition of outage probability, when the channel capacity I is less than the transmission rate R, it is considered that an outage occurs. Extending the definition, in a cognitive two-way relay network, as long as any time slot is interrupted, the network is considered to be interrupted. So the outage probability can be expressed as

where I _ij and R _ij , (i,j)∈{(A,T),(B,T),(T,A),(T,B)}, are the channel between node i and node j respectively capacity and transfer rate.

Since the channels of the three time slots are independent of each other, the outage probability of the cognitive bidirectional network can be derived by calculating the probability that no outage occurs in each of the three time slots.

In the first step, the probability that no outage occurs in the first time slot, Pr(I _AT ≥ R _AT ). Under the Rayleigh channel condition, the channel gain | _hAT | ² obeys the Rayleigh distribution, According to previous research results, the probability of no interruption in time slot 1 can be obtained.

in (i,j)∈{(A,T),(B,T),(T,A),(T,B)}.

In the second step, the probability that no outage occurs in the second time slot, Pr(I _BT ≥ R _BT ). The derivation process is similar to that of time slot 1, and the same method can be used.

The third step is the probability that no interruption occurs in the third time slot, Pr(I _TA ≥ R _TA , I _TB ≥ R _TB ). Since the relay needs to meet the interference constraint on the primary user during broadcasting to A and B, the two are not independently distributed, and the joint probability of the two must be obtained. According to the previous research results, we can get:

in and Z=|h _TC | ² . On this basis, the joint probability of (X ₁ ,X ₂ ) can be derived.

Therefore, the probability that no outage occurs in slot 3 is:

Through the above three steps, a method for quickly evaluating the outage probability of the cognitive two-way relay network according to the embodiment of the present invention is obtained, which can be directly obtained by the following formula, without requiring the actual operation of the network for a period of time to obtain the Expect to be evaluated.

As shown in Figure 3, the comparison between the outage probability rapid evaluation method proposed by the present invention and the network example simulation data shows that the method proposed by the present invention is very consistent with the simulation data curve, and it can be proved that the method of the embodiment of the present invention has Relatively good applicability.

According to the method of the embodiment of the present invention, it can be compared with the transmission quality requirements preset by the network. If the estimated interruption probability exceeds the design requirements of the network, the interruption probability of the system can be reduced by adjusting the transmission rate of the secondary user in real time. Ensure the reliability of network transmission.

Fig. 4 is a structural block diagram of an adaptive optimization system for a cognitive two-way relay network according to an embodiment of the present invention. As shown in FIG. 4 , an adaptive optimization system 400 for a cognitive two-way relay network according to an embodiment of the present invention, wherein, as shown in FIG. 2 , the cognitive two-way relay network includes multiple nodes, and the multiple nodes include at least The primary user node, the secondary user node and the relay station node, the system 400 includes: a setting module 410 , an estimation module 420 , an interruption probability calculation module 430 , a comparison module 440 and a transmission control module 450 .

Wherein, the setting module 410 is used for setting the interference temperature of the primary user node and the outage probability threshold value of the secondary user node. The estimation module 420 is used for estimating and obtaining channel state information of each node in the cognitive two-way relay network. The outage probability calculation module 430 is configured to calculate the outage probability of the cognitive two-way relay network by using the channel state information of each node through a preset outage probability rapid assessment method. The comparison module 440 is used for comparing the outage probability with the outage probability threshold. The transmission control module 450 is configured to control the cognitive two-way relay network to transmit data when the outage probability is less than the outage probability threshold, otherwise adjust the transmission rate of the cognitive two-way relay network to reduce the outage probability of the cognitive two-way relay network.

In one embodiment of the present invention, the outage probability calculation module 430 is configured to: evaluate the outage probability of a preset number of time slots, and obtain the recognized The outage probability of bidirectional relay network is known. Further, the preset number is 3.

In some examples, the cognitive two-way relay network is a cognitive two-way relay network employing a time-division broadcast transmission mode. In addition, when the secondary user node is used in the data transmission process, it is divided into three equal time slots, and uses the time division broadcast mode for data transmission. When the relay station node is used in the data transmission process, it uses the decoding and forwarding mode.

It can be understood that the specific means adopted by the system of the embodiment of the present invention are similar to the specific means adopted by the method of the embodiment of the present invention. Therefore, the implementation process of the system of the embodiment of the present invention can refer to the detailed description of the method part. In order to reduce redundancy, details are not repeated here.

According to the system of the embodiment of the present invention, it can be compared with the transmission quality requirements preset by the network. If the estimated interruption probability exceeds the design requirements of the network, the interruption probability of the system can be reduced by adjusting the transmission rate of the secondary user in real time. Ensure the reliability of network transmission.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications, substitutions and modifications can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the invention is defined by the claims and their equivalents.

Claims (8)

1. An adaptive optimization method for a cognitive two-way relay network, characterized in that the cognitive two-way relay network includes a plurality of nodes, and the plurality of nodes includes at least a primary user node, a secondary user node, and a relay station node , the method includes the following steps: Setting the interference temperature of the primary user node and the outage probability threshold value of the secondary user node; Estimating and obtaining channel state information of each node in the cognitive two-way relay network; calculating the outage probability of the cognitive two-way relay network by using the channel state information of each node according to a formula by using a preset outage probability rapid assessment method; comparing the outage probability with the outage probability threshold; transmitting data over the cognitive two-way relay network if the outage probability is less than the outage probability threshold; and If the outage probability is not less than the outage probability threshold value, adjusting the transmission rate of the cognitive two-way relay network to reduce the outage probability of the cognitive two-way relay network; The secondary user node is divided into three equal time slots when used in the data transmission process, and uses a time-division broadcast mode for data transmission, and the relay station node uses a decoding and forwarding mode when used in the data transmission process; Wherein, the formula is: in, is the transmission rate from secondary user A to relay station T, is the transmission rate from secondary user B to relay station T, is the transmission rate from relay station T to secondary user A, is the transmission rate from the relay station T to the secondary user B, I _th is the interference temperature of the primary user C, λ _AT is the coefficient of the Rayleigh distribution under the probability of no interruption from the secondary user A to the relay station T, and λ _BT is the transmission rate from the secondary user B to the relay station T is the coefficient of the Rayleigh distribution under the probability of no interruption, λ _TC is the coefficient of the Rayleigh distribution under the probability of no interruption from the relay station T to the primary user C, σ is a constant, λ _AC is the The coefficient of the Rayleigh distribution under the probability of interruption, λ _BC is the coefficient of the Rayleigh distribution under the probability of no interruption from the secondary user B to the primary user C, and λ _TA is the Rayleigh probability of no interruption from the relay station T to the secondary user A The coefficient of the distribution, λ _TB is the coefficient of the Rayleigh distribution under the probability that the relay station T to the secondary user B will not be interrupted. 2. The adaptive optimization method of cognitive two-way relay network according to claim 1, characterized in that, the fast assessment method of the preset outage probability uses the channel state information of each node to calculate the cognitive The outage probability of the two-way relay network, including: Evaluate the outage probability of a preset number of time slots; The outage probability of the cognitive two-way relay network is calculated according to the evaluation results of the outage probabilities of the preset number of time slots. 3. The adaptive optimization method for a cognitive two-way relay network according to claim 2, wherein the preset number is three. 4. The adaptive optimization method for a cognitive two-way relay network according to claim 1, wherein the cognitive two-way relay network is a cognitive two-way relay network using a time-division broadcast transmission mode. 5. An adaptive optimization system for a cognitive two-way relay network, characterized in that the cognitive two-way relay network includes a plurality of nodes, and the plurality of nodes includes at least a primary user node, a secondary user node, and a relay station node , the system includes: A setting module, configured to set the interference temperature of the primary user node and the outage probability threshold of the secondary user node; An estimation module, configured to estimate and obtain channel state information of each node in the cognitive two-way relay network; An outage probability calculation module, configured to calculate the outage probability of the cognitive two-way relay network by using the channel state information of each node according to the formula through a preset outage probability rapid assessment method; and A comparison module, configured to compare the outage probability with the outage probability threshold; a transmission control module, configured to control the cognitive two-way relay network to transmit data when the outage probability is less than the outage probability threshold; otherwise, adjust the transmission rate of the cognitive two-way relay network to reduce the Cognitive outage probability of two-way relay networks; The secondary user node is divided into three equal time slots when used in the data transmission process, and uses a time-division broadcast mode for data transmission, and the relay station node uses a decoding and forwarding mode when used in the data transmission process; Wherein, the formula is: in, is the transmission rate from secondary user A to relay station T, is the transmission rate from secondary user B to relay station T, is the transmission rate from relay station T to secondary user A, is the transmission rate from the relay station T to the secondary user B, I _th is the interference temperature of the primary user C, λ _AT is the coefficient of the Rayleigh distribution under the probability of no interruption from the secondary user A to the relay station T, and λ _BT is the transmission rate from the secondary user B to the relay station T is the coefficient of the Rayleigh distribution under the probability of no interruption, λ _TC is the coefficient of the Rayleigh distribution under the probability of no interruption from the relay station T to the primary user C, σ is a constant, λ _AC is the The coefficient of the Rayleigh distribution under the probability of interruption, λ _BC is the coefficient of the Rayleigh distribution under the probability of no interruption from the secondary user B to the primary user C, and λ _TA is the Rayleigh probability of no interruption from the relay station T to the secondary user A The coefficient of the distribution, λ _TB is the coefficient of the Rayleigh distribution under the probability that the relay station T to the secondary user B will not be interrupted. 6. The adaptive optimization system of the cognitive two-way relay network according to claim 5, wherein the outage probability calculation module is used for: evaluating the outage probability of a preset number of time slots, and according to The outage probability of the cognitive two-way relay network is obtained by calculating the outage probability evaluation results of the preset number of time slots. 7. The adaptive optimization system for a cognitive two-way relay network according to claim 6, wherein the preset number is three. 8 . The adaptive optimization system for a cognitive two-way relay network according to claim 5 , wherein the cognitive two-way relay network is a cognitive two-way relay network using a time-division broadcast transmission mode.