阅读说明：本技术 一种基于功率方差比较的多频带频谱感知方法 (Multi-band frequency spectrum sensing method based on power variance comparison ) 是由 徐佳烽 金明 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种基于功率方差比较的多频带频谱感知方法,其计算每个频带的接收信号的功率；对所有频带的接收信号的功率从大到小进行排序；令一个变量在2到频带的总数量范围内取值,计算使得功率方差比较公式取得最大值时该变量的取值；判定排序后的所有功率中以该变量的取值为序号开始的所有功率对应的频带没有被其它无线通信业务占用,而其余功率对应的频带被其它无线通信业务占用；优点是其能够同时对所有频带实现频谱感知判决,且无需设置判决门限。(The invention discloses a multiband frequency spectrum sensing method based on power variance comparison, which calculates the power of a received signal of each frequency band; sequencing the power of the received signals of all frequency bands from large to small; making a variable take a value in the range from 2 to the total number of frequency bands, and calculating the value of the variable when the power variance comparison formula obtains the maximum value; judging that the frequency bands corresponding to all the powers starting with the value of the variable as the serial number in all the sequenced powers are not occupied by other wireless communication services, and the frequency bands corresponding to the rest powers are occupied by other wireless communication services; the method has the advantages that the method can realize spectrum sensing judgment on all frequency bands simultaneously, and does not need to set judgment thresholds.)

1. A multiband frequency spectrum sensing method based on power variance comparison is characterized by comprising the following steps:

the method comprises the following steps: in the cognitive radio system, setting the total number of frequency bands to be N; then, the power of the received signal of each frequency band is calculated, and the power of the received signal of the nth frequency band is recorded as p_n(ii) a Wherein N and N are positive integers, N is more than 1, the initial value of N is 1, and N is more than or equal to 1 and less than or equal to N;

step two: sorting the power of the received signals of the N frequency bands from large to small when the different frequency bands are differentThe order of these powers is arbitrarily arranged when the powers of the received signals of (1) are the same, and the set of the powers of the received signals of the N frequency bands after sorting is expressed as Ω,wherein the content of the first and second substances,

step three: let k represent a positive integer, k is calculated in the range of 2 to N so that the power variance is compared with the formulaThe value of k when the maximum value is obtained is recorded as k_max(ii) a Wherein k is more than or equal to 2 and less than or equal to N, k_max∈[2,N]，Are all the power variance, and the power variance,

step four: the decision of spectrum sensing is made for all frequency bands simultaneously, i.e. the 1 st power in Ω is determinedTo k < th > of_max-1 powerRespective corresponding frequency bandOccupied by other wireless communication services, and determining the k-th in omega_maxSpecific power

Technical Field

The invention relates to a spectrum sensing technology in a cognitive radio system, in particular to a multiband spectrum sensing method based on power variance comparison.

Background

With the rapid growth of wireless communication services, the demand of people for spectrum resources is continuously increased, and the phenomenon of spectrum resource shortage becomes more and more serious. On one hand, the rapid development of wireless communication services and the continuous emergence of various systems, protocols and networks make more devices need to use radio spectrum; on the other hand, the spectrum of the authorized user under the fixed allocation strategy of the spectrum resources is exclusively used, so that the spectrum resources cannot be effectively utilized. Therefore, the fixed allocation strategy of the spectrum resources is one of the main reasons for the spectrum resource shortage phenomenon. The cognitive radio technology can effectively improve the utilization rate of frequency spectrum resources, and is one of the main schemes for realizing dynamic allocation of the frequency spectrum resources. The spectrum sensing is an important component in the cognitive radio technology, which can effectively prevent the interference of the wireless communication service adopting the cognitive radio technology to other wireless communication services in the same frequency band, and the performance of the spectrum sensing is directly related to the quality of the wireless communication service.

In practical application, a cognitive user adopting a cognitive radio technology needs to perform spectrum sensing on a plurality of frequency bands, so that the plurality of cognitive users can access an idle frequency band, and meanwhile, part of the cognitive users realize long-time information transmission through frequency band switching. There are two main categories of existing multi-band spectrum sensing schemes. The first is a sequential spectrum sensing scheme, that is, a cognitive user can only sense spectrum for one frequency band at a time, and this scheme has a disadvantage that it takes a long time to perform multi-band spectrum sensing when the number of frequency bands is large. The second category is a parallel spectrum sensing scheme, that is, spectrum sensing is realized in all frequency bands at the same time, and such a scheme has the disadvantage that a decision threshold needs to be set according to noise power, and uncertainty of the noise power makes it difficult to effectively set the decision threshold.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a multiband frequency spectrum sensing method based on power variance comparison, which can realize frequency spectrum sensing judgment on all frequency bands simultaneously and does not need to set judgment thresholds.

The technical scheme adopted by the invention for solving the technical problems is as follows: a multiband frequency spectrum sensing method based on power variance comparison is characterized by comprising the following steps:

the method comprises the following steps: in the cognitive radio system, setting the total number of frequency bands to be N; then, the power of the received signal of each frequency band is calculated, and the power of the received signal of the nth frequency band is recorded as p_n(ii) a Wherein N and N are positive integers, N is more than 1, the initial value of N is 1, and N is more than or equal to 1 and less than or equal to N;

step two: sorting the power of the received signals of N frequency bands from large to small, when the different frequency bands are receivedWhen the power of the signal is the same, the order of these powers is arbitrarily arranged, and the set of the power of the received signal of the N frequency bands after sorting is expressed as Ω,

wherein the content of the first and second substances,

the corresponding 1 st power, 2 nd power, jth power and nth power in the expression omega,

j is a positive integer, the initial value of j is 1, and j is more than or equal to 1 and less than or equal to N;

step three: let k represent a positive integer, k is calculated in the range of 2 to N so that the power variance is compared with the formula

The value of k when the maximum value is obtained is recorded as k_max(ii) a Wherein k is more than or equal to 2 and less than or equal to N, k_max∈[2,N]，

Are all the power variance, and the power variance,

step four: the decision of spectrum sensing is made for all frequency bands simultaneously, i.e. the 1 st power in Ω is determined

To k < th > of_max-1 powerThe frequency bands corresponding to the two are occupied by other wireless communication services, and the k-th frequency band in the omega is judged_maxSpecific power

To the Nth power

The respective corresponding frequency bands are not occupied by other wireless communication services.

Compared with the prior art, the invention has the advantages that:

1) the method of the invention firstly sorts the power of the received signals of all frequency bands from large to small, then finds out a sequence number of the power of the sorted received signals through a power variance comparison formula, judges the frequency band corresponding to the power of the received signals before the sequence number as occupied by other wireless communication services, and judges other frequency bands as not occupied by other wireless communication services; therefore, the judgment of the spectrum sensing can be simultaneously carried out on all frequency bands, and the problem of long time consumption for completing the multi-band spectrum sensing by a sequential spectrum sensing scheme is solved.

2) When the method of the invention utilizes a power variance comparison formula, the spectrum sensing is realized by comparing the power variance of the received signals without setting a decision threshold, thereby solving the problem that the decision threshold is difficult to be effectively set by a parallel spectrum sensing scheme.

Drawings

FIG. 1 is a block diagram of an overall implementation of the method of the present invention;

fig. 2 is a graph illustrating the detection probability and the false alarm probability of the method according to the present invention according to the variation of the snr under the condition that the total number of frequency bands is 100, and 30 frequency bands are occupied by other wireless communication services, and the snrs of the received signals of the frequency bands occupied by other wireless communication services are all equal.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

The general implementation block diagram of the multiband spectrum sensing method based on power variance comparison provided by the invention is shown in fig. 1, and the method comprises the following steps:

the method comprises the following steps: in a cognitive radio system, an apparatusThe total number of the fixed frequency bands is N; then, the power of the received signal of each frequency band is calculated by adopting the prior art, and the power of the received signal of the nth frequency band is recorded as p_n(ii) a Where N and N are both positive integers, N > 1, where N is 100 in this embodiment, and N is an initial value of 1, and N is not less than 1 and not more than N.

Step two: the powers of the received signals of the N frequency bands are sorted from large to small, the power orders are randomly arranged when the powers of the received signals of different frequency bands are the same, the set of the power configuration of the sorted received signals of the N frequency bands is represented as omega,

wherein the content of the first and second substances,

the corresponding 1 st power, 2 nd power, jth power and nth power in the expression omega,

j is a positive integer, the initial value of j is 1, and j is more than or equal to 1 and less than or equal to N.

Step three: let k represent a positive integer, k is calculated in the range of 2 to N so that the power variance is compared with the formulaThe value of k when the maximum value is obtained is recorded as k_max(ii) a Wherein k is more than or equal to 2 and less than or equal to N, k_max∈[2,N]，Are all the power variance, and the power variance,

step four: the decision of spectrum sensing is made for all frequency bands simultaneously, i.e. the 1 st power in Ω is determined

To k < th > of_max-1 power

The frequency bands corresponding to the two are occupied by other wireless communication services, and the k-th frequency band in the omega is judged_maxSpecific power

To the Nth power

The respective corresponding frequency bands are not occupied by other wireless communication services.

The feasibility of the method of the invention is further illustrated by computer simulation.

Assuming that the total number of frequency bands is N-100, the power of the received signal of each frequency band is calculated by sampling 50 samples. 30 of the 100 frequency bands are set to be occupied by other wireless communication services, and the signal-to-noise ratios of the received signals of the frequency bands occupied by the other wireless communication services are all equal. Fig. 2 shows a plot of detection probability versus false alarm probability as a function of signal-to-noise ratio for the method of the present invention. As can be seen from FIG. 2, when the SNR is not less than-2 dB, the false alarm probability of the method of the present invention is close to 0, and the detection probability is greater than 0.9; when the signal-to-noise ratio is not less than 4dB, the false alarm probability of the method is close to 0, and the detection probability is close to 1.