CN103957565B - Resource allocation methods based on target SINR in distributed wireless networks - Google Patents

Abstract

A resource allocation method in a wireless distributed network. In the first step, users define their own target SINR according to their own communication requirements. Then the interference power in the wireless environment is detected and estimated, and the corresponding channel gain is obtained at the same time. With these quantities, we quantify the quality of the channel. The second step is to select the channel with the best channel condition according to the channel quality quantification result, and compare its channel quality with a predefined threshold to see whether the channel condition is suitable for transmission. If the channel condition is too bad, this data transmission is abandoned; otherwise, the optimal transmission power is calculated according to the closed-form solution of the optimal power, and data transmission is performed on the channel. The implementation complexity of the present invention is relatively low, and the interference in the network can be effectively controlled, and the QoS requirement of the user can be guaranteed more effectively under the condition of reducing the average transmission power of the user, and at the same time, better fairness can be achieved.

Description

Resource Allocation Method Based on Target SINR in Distributed Wireless Networks

technical field

The invention belongs to the field of wireless communication, and in particular relates to a target SINR-based resource allocation method in a distributed wireless network.

Background technique

The rapid development of wireless technologies makes distributed wireless networks a common networking method. In a distributed wireless network, the resource allocation mechanism will significantly affect the performance of the network. Due to the lack of control and guidance of the central node, it is difficult to obtain global information, and global optimization is often difficult to achieve. On the other hand, since each user only cares about the performance obtained in the network, users often tend to blindly increase their transmit power in order to obtain higher throughput and shorter delay, so as to better Guarantee your own service quality. Obviously, if all users blindly increase their own transmit power, the interference of the network will increase significantly, and eventually the performance of the entire network will become unacceptable. Therefore, guiding users to select channels and controlling transmit power through an efficient resource allocation mechanism can effectively suppress co-channel interference (Co-Channel Interference), guarantee users' QoS (Quality of Service) requirements, and improve network performance.

Common resource allocation methods are mostly designed based on optimization theory. These methods usually have relatively high complexity. Moreover, there are additional difficulties in implementing these algorithms in a distributed wireless network: the execution of these methods generally needs to obtain information about the operating status (transmission power, channel occupancy, etc.) of other users in the network, and in a distributed network, due to the lack of It is very difficult to accurately obtain this information with the assistance of the central node. In practice, in order to execute these algorithms, additional interaction mechanisms need to be designed, and resource allocation algorithms can be further executed on the basis of accurate and reliable network information.

To sum up, it is necessary to design an easy-to-deploy and efficient resource allocation method for distributed wireless networks.

Contents of the invention

The object of the present invention is to provide a target SINR-based resource allocation method in a distributed wireless network, which is simple, efficient, and easy to implement.

In order to achieve the above object, the technical solution adopted in the present invention comprises the following steps:

The first step is to initialize the system parameters of the current wireless frame. The initialization method is: each user defines its own target signal-to-interference-noise ratio (SINR) The weight coefficient θ _n of the cost corresponding to the user's deviation from the target SINR, the weight coefficient λ of the total cost of the user's deviation from the target SINR and the power paid; at the same time, the power of each user on each channel is initialized to zero; and Represents the collection of user pairs, n represents the nth user pair, and there are N user pairs in total;

The second step is to perform energy detection on the current wireless network environment, and obtain the channel gain of the user in the current wireless network and the interference power received by the user on each channel;

The third step is to quantify the channel quality according to the user's channel gain and interference power, and then the user selects the channel with the best channel condition as the transmission channel k ^* according to the quantization result;

In the fourth step, the index corresponding to the transmission channel and a predefined threshold To compare, if Then abandon the transmission of this data, end the current resource allocation, and return to step 1) to start the user resource allocation of the next wireless frame;

like Then use the initialized system parameters to determine the transmit power on the channel k ^* with the best channel conditions

If the transmit power on the transmission channel k ^* Greater than or equal to the user's maximum transmit power Then on the transmission channel k ^* with the user's maximum transmit power Carry out the transmission, complete the resource allocation of the user, and return to step 1) to start the user resource allocation of the next wireless frame; if the transmission power on the transmission channel k ^* Less than the user's maximum transmit power Then on the transmission channel k ^* with the transmission power on the transmission channel k ^* Perform transmission, complete user resource allocation, and return to step 1) to start user resource allocation for the next radio frame.

In the first step, according to the user's current transmit power Obtain the SINR actually achieved by the user The SINR actually achieved by the user target SINR For comparison, if the actual signal-to-interference-noise ratio achieved by the user Greater than or equal to the target SINR then maintain the user's current transmit power Perform transmission, complete resource allocation, and then return to step 1) to start user resource allocation for the next frame; if the actual SINR achieved by the user less than the target SINR Then turn to the second step; where k is the kth channel, and is a set of channels, including K channels in total.

In the third step, the method for quantifying each channel quality according to the channel gain of the user and the interference power received by the user on each channel is:

in, is the index corresponding to the channel, is the user’s detected interference power on channel k, N ₀ is the noise power in the wireless network system, is the channel gain of the nth user pair from the originating end to the corresponding receiving end;

The method for the user to select the channel k ^* with the best channel condition according to the quantization result is: select the index corresponding to the channel The smallest channel is taken as the transmission channel k ^* .

The predefined threshold Obtained as follows:

The method to determine the transmit power on the channel k ^* with the best channel condition is

Compared with prior art, the beneficial effect of the present invention is:

The present invention uses the method of non-cooperative game to model the distributed network, and each user can independently allocate resources according to the external environment information obtained by itself without external guidance and intervention to achieve the purpose of no central control, and the realization is complicated. The accuracy is relatively low; and it can determine whether to transmit and determine the optimal transmission power by judging the actual channel conditions, avoiding the situation where nodes in the distributed network blindly increase their own transmission power, and ensuring that the network is under different interference conditions. All have good performance. Moreover, the present invention does not require cooperation between nodes, is easy to implement, and effectively controls co-channel interference, thereby improving network performance and user experience. In addition, the resource allocation in the present invention is guided by the user's own target signal-to-interference-to-noise ratio, which can well control the interference in the network and ensure the actual QoS requirements of the user to the greatest extent under the condition of reducing the average transmission power of the user. . At the same time, the transmission power is selected according to the actual channel conditions, which effectively controls the co-channel interference in the network and achieves higher spectral efficiency with lower power.

Description of drawings

Fig. 1 is the implementation process of the present invention;

Fig. 2 is the curve of the probability that the user system guarantees the target SINR of the user in the wireless network as the number of users changes;

Fig. 3 is the curve that the user's average transmission power changes with the number of users in the wireless network;

Fig. 4 is the curve that user fairness index changes with the number of users in the wireless network;

Fig. 5 is the curve that the system throughput changes with the number of users in the wireless network;

In Fig. 2-5, a is the scheme of the present invention, b is the scheme of target SINR tracking, c is the scheme of opportunistic power control, and d is the scheme of resource allocation based on power pricing.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Referring to Fig. 1, the present invention is based on non-cooperative game modeling, and establishes a resource allocation method for a wireless distributed network. Under this method, all users must perform the resource allocation of the present invention until the resource allocation of all users reach a steady state.

The basic network scenario of the wireless network applicable to the resource allocation method based on the target SINR in the distributed wireless network proposed by the present invention is assumed as follows:

In a wireless environment, with N user pairs, is its number, Represents the set of user pairs; similarly, there are K non-overlapping channels, numbered as is a collection of channels, and the bandwidth of each channel is B ₀ . Indicates the transmit power of the nth user on the kth channel. Obviously, if If it is non-zero, it means that it uses the kth channel, otherwise it does not use this channel, and each user has its own maximum transmit power At the same time, the channel gain It describes the channel gain of the nth user pair from the sending end to the corresponding receiving end, and this value can be obtained by measuring the power of the pilot signal during the communication process of the user pair. Similarly, Describes the channel gain of the interfering signal from the transmitter of the m-th user pair to the receiver of the n-th user pair. The noise power in the wireless network system is denoted as N ₀ . Each user in the wireless network sets a target SINR according to its own communication needs. Under this SINR condition, its energy ratio satisfies its own communication needs well. do The SINR actually obtained by the user is denoted as At the same time, the weighted sum of the power paid by the user and the square of the difference between the achieved SINR and the target is defined as the weight coefficient of the price paid by the user, which is denoted as θ _n . On the other hand, the weighted sum of the rate and the cost is defined as the user The weight coefficient of utility is denoted as λ.

The basic idea of the present invention is that resource allocation is performed in each wireless frame as follows, and the allocation is performed in an iterative manner until convergence. In each resource allocation, a user pair uses at most one channel for transmission. It is assumed that resource allocation is performed when the current radio frame time is t. Each user independently performs the following steps:

The first step is to initialize the system parameters of the current wireless frame. The user determines the target SINR and the weighting coefficient according to the target according to the user's communication needs, and further performs energy detection on the current wireless environment to obtain the current wireless frame. Interfering power and channel gain in the environment. The second step is to select a channel and determine the transmit power according to its own communication goals and obtained channel conditions.

The first step is to initialize the system parameters of the current wireless frame:

Each user defines its own target SINR The weight coefficient θ _n of the cost corresponding to the user's deviation from the target SINR and the weight coefficient λ of the total cost of the user's deviation from the target SINR and the power paid, based on which the utility function of the user is determined defined as in, is the rate achieved by the user, is the SINR actually achieved by the user. In fact, according to the utility function, the following optimization objective is established

The above optimization problem is a joint optimization problem of channel selection and power allocation. However, for the sake of operability, it is implemented sequentially, that is, channel selection is performed first, and then power is determined. It can be proved that under the defined conditions of the given utility function, the results obtained by such sequential operations are also optimal.

Based on this, a set of constants are calculated, which are and c ₃ =8θ _n λ ₀ , for the convenience of subsequent calculations, and at the same time initialize the user's power on each channel to zero.

If the transmit power on the current channel has met the target SINR requirement, stay on the current channel and keep the current transmit power for transmission, and the resource allocation ends; otherwise, enter the second step. Specifically, the method for judging that the transmit power on the current channel has met the target SINR requirement is:

According to the user's current transmit power Obtain the SINR actually achieved by the user The SINR actually achieved by the user target SINR For comparison, if the actual signal-to-interference-noise ratio achieved by the user Greater than or equal to the target SINR Then the transmission power on the current channel has met the target SINR requirement, and then return to step 1) to start the user resource allocation of the next frame; if the actual SINR achieved by the user less than the target SINR Then the transmit power on the current channel cannot meet the target SINR requirement.

The second step is to perform energy detection on the current wireless network environment to obtain the channel gain of the user in the current wireless network and the interference power received by the user on each channel; the interference power can be obtained by performing energy detection on the channel The channel gain can be calculated by measuring the received power of the pilot signal;

in, is the transmission power of the mth user on the kth channel;

In the third step, the quality of each channel is quantified according to the channel gain of the user and the interference power received by the user on each channel, and then the user selects the channel k ^* with the best channel condition according to the quality quantization result, the specific method is as follows:

First, use the channel gain of the user and the interference power of the user on the channel to calculate the quantitative index of the channel quality. The calculation formula is as follows

in, is the index corresponding to the channel, is the user’s detected interference power on channel k, N ₀ is the noise power in the wireless network system, is the channel gain of the nth user pair from the originating end to the corresponding receiving end.

Secondly, the quantization process is performed on all channels, and the user selects the channel with the best channel condition as the transmission channel k ^* according to the quantization result, that is, selects the corresponding index in each channel The smallest channel is used as the transmission channel k ^* , then

In the fourth step, the index corresponding to the transmission channel k ^* and a predefined threshold To compare, if It means that the current transmission channel k ^* cannot meet the transmission requirements, so the data transmission is abandoned, that is, the transmission power is set to zero, End the current resource allocation, return to step 1) start the user resource allocation of the next radio frame; wherein, It is used to examine whether the channel condition is within an acceptable range.

like Then it shows that the channel condition of the current transmission channel k ^* is acceptable, and the transmission power on the transmission channel k ^* is determined by using the initialized system parameters The determination formula is as follows:

At the same time, the maximum power limit of the user's current wireless frame should also be investigated. If the transmission power on the transmission channel k ^* Greater than or equal to the user's maximum transmit power Then on the transmission channel k ^* with the user's maximum transmit power Carry out the transmission, complete the resource allocation of the user, and return to step 1) to start the user resource allocation of the next wireless frame; if the transmission power on the transmission channel k ^* Less than the user's maximum transmit power Then on the transmission channel k ^* with the transmission power on the transmission channel k ^* Perform transmission, complete user resource allocation, and return to step 1) to start user resource allocation for the next radio frame.

In order to prove that the method obtained by the present invention is indeed feasible and effective, the comparison between the resource allocation scheme proposed by the present invention and the traditional method is given through simulation.

Curves a-d in Fig. 2 compare the situation of user target SINR guarantee under related schemes. Compared with other traditional methods, the solution of the present invention can significantly increase the probability of meeting the user's target SINR. Since in actual scenarios, the target SINR largely reflects the user's service quality, it can be said that the solution of the present invention will provide users with better and more reliable service quality.

Curves a-d in Figure 3 compare the average transmit power of users under related schemes. It can be seen from FIG. 2 that the solution of the present invention requires lower transmit power than other solutions on the premise of better guaranteeing the target SINR of the user. Therefore, the scheme of the present invention is a very efficient power control scheme.

Curves a-d in Figure 4 compare the fairness of user rates in the network under related schemes. In a distributed network environment, ensuring fairness helps prevent some selfish users from causing serious interference to other users in order to maximize their own speed, thereby improving the user experience of the entire network. From the simulation results, the solution of the present invention provides significantly better network fairness than the traditional solution.

Curves a-d in Figure 5 compare the throughput of the entire network under related schemes. Combining the results of Figures 2-4, the solution of the present invention provides users with more effective service quality assurance and fairness through a more efficient resource allocation method, and at the same time, the solution of the present invention can achieve better system throughput .

Claims (3)

1. the resource allocation method based on target SINR in the distributed wireless network, it is characterized in that, comprising the following steps: The first step is to initialize the system parameters of the current wireless frame. The initialization method is: each user defines its own target signal-to-interference-noise ratio (SINR) The weight coefficient θ _n of the cost corresponding to the user's deviation from the target SINR, the weight coefficient λ of the total cost of the user's deviation from the target SINR and the power paid; at the same time, the power of each user on each channel is initialized to zero; and Represents the collection of user pairs, n represents the nth user pair, and there are N user pairs in total; The second step is to perform energy detection on the current wireless network environment, and obtain the channel gain of the user in the current wireless network and the interference power received by the user on each channel; The third step is to quantify the channel quality according to the user's channel gain and interference power, and then the user selects the channel with the best channel condition as the transmission channel k ^* according to the quantization result; The method of quantifying the quality of each channel according to the channel gain of the user and the interference power received by the user on each channel is: <mrow><msubsup><mi>&amp;beta;</mi><mi>n</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mi>mo></mrow></msubsup><mo>=</mo><mfrac><mrow><msubsup><mi>I</mi><mi>n</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup><mo>+</mo><msub><mi>N</mi><mn>0</mn></msub></mrow><msubsup><mi>g</mi><mrow><mi>n</mi><mi>n</mi></mrow><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup></mfrac></mrow> in, is the index corresponding to the channel, is the user’s detected interference power on channel k, N ₀ is the noise power in the wireless network system, is the channel gain of the nth user pair from the originating end to the corresponding receiving end; The method for the user to select the channel k ^* with the best channel condition according to the quantization result is: select the corresponding index in each channel The smallest channel is used as the transmission channel k ^* ; In the fourth step, the index corresponding to the transmission channel and a predefined threshold To compare, if Then abandon the transmission of this data, end the current resource allocation, and return to step 1) to start the user resource allocation of the next wireless frame; like Then use the initialized system parameters to determine the transmit power on the channel k ^* with the best channel conditions The method to determine the transmit power on the channel k ^* with the best channel condition is The bandwidth of each channel is B ₀ ; if the transmission power on the transmission channel k ^* Greater than or equal to the user's maximum transmit power Then on the transmission channel k ^* with the user's maximum transmit power Carry out the transmission, complete the resource allocation of the user, and return to step 1) to start the user resource allocation of the next wireless frame; if the transmission power on the transmission channel k ^* Less than the user's maximum transmit power Then on the transmission channel k ^* with the transmission power on the transmission channel k ^* Perform transmission, complete user resource allocation, and return to step 1) to start user resource allocation for the next radio frame. 2. The resource allocation method based on the target SINR in the distributed wireless network according to claim 1, characterized in that: in the first step, according to the user's current transmit power Obtain the SINR actually achieved by the user The SINR actually achieved by the user target SINR For comparison, if the actual signal-to-interference-noise ratio achieved by the user Greater than or equal to the target SINR then maintain the user's current transmit power Perform transmission, complete resource allocation, and then return to step 1) to start user resource allocation for the next frame; if the actual SINR achieved by the user less than the target SINR Then turn to the second step; where k is the kth channel, and is a set of channels, including K channels in total. 3. the resource allocation method based on target SINR in the distributed wireless network according to claim 1, is characterized in that, described predefined threshold Obtained as follows: The bandwidth of each channel is B ₀ .