CN114614927A - Nakagami fading complex channel simulation method - Google Patents

Abstract

The invention discloses a Nakagami fading complex channel simulation method, which comprises the following steps: s1: obtaining a time domain signal sequence of Gamma distribution with parameters of (m, omega/m) by calling a Gamma function, and squaring the sequence element by element to obtain an envelope r so that the envelope r follows the Nakagami-m distribution of the parameters of (m, omega); s2: the corresponding phase phi is obtained by a rejection method to generate uniform distribution

Generates a random number x obeying uniform distribution

Random number of

B is

Is at a maximum value of

Then, then

Otherwise, repeating the step; s3: combining envelopes r and

phase, establishing a corresponding complex channel of

Description

Nakagami fading complex channel simulation method

Technical Field

The invention relates to a simulation method, in particular to a Nakagami fading complex channel simulation method.

Background

The wireless fading channel modeling is to establish a mathematical model based on channel characteristic analysis and perform simulation similar to an actual channel in a laboratory environment. Compared with the traditional field actual measurement, the method can greatly reduce the difficulty and the cost of system test and is widely applied.

When the radio signal encounters an undulating terrain during its propagation, it causes absorption and penetration of energy and reflection, scattering and diffraction of radio waves, and the signal arriving at the mobile station antenna is not a single path but a composite of many reflected waves from many paths. Since the distance of the radio wave passing through each path is different, the arrival time of the reflected wave from each path is different, and the phase is different. Multiple signals of different phases are superimposed at the receiving end, sometimes with in-phase superimposition to enhance them, and sometimes with reverse superimposition to attenuate them. Therefore, the amplitude of the received signal will change sharply, i.e., fading is generated. Research has shown that the envelope of a wireless fading received signal generally follows a rayleigh distribution, a rice distribution, or a Nakagami-m distribution. The Nakagami-m distribution (Nakagami distribution for short) is more general, different fading conditions such as severe, moderate, slight and no fading can be described by changing the value of the fading factor m, and the actual measurement result shows that the distribution is closer to the actual situation than the distribution such as Rayleigh and Rice.

At present, the modeling and simulation aiming at the Nakagami fading channel which are common at home and abroad can be divided into three categories: a channel decomposition method, an inverse transform method, and a discard method. Although the channel decomposition method is simpler, the performance is poorer when m is not an integer multiple of 0.5; because the cumulative probability density function of Nakagami distribution has no inverse function, the inverse transformation method can only adopt polynomial approximation, and a large number of numerical value approximations are needed for different m values to obtain a coefficient table, which is very complex; the rejection method is a general method suitable for arbitrary fading distribution, and the difficulty is to find an efficient hat function. According to related reports, the efficiency of the hat function which is common at present is different from 60% to 65%.

Disclosure of Invention

The technical problem to be solved by the invention is that the verification result is simply compared with a theoretical value and a simulation value, and a correlation method for scientifically verifying the validity and the accuracy of the model is not mentioned, and the invention aims to provide a Nakagami fading complex channel simulation method and solve the problems.

The invention is realized by the following technical scheme:

a method for simulating a Nakagami fading complex channel, the method comprising the steps of:

s1: obtaining a time domain signal sequence of Gamma distribution with parameters of (m, omega/m) by calling a Gamma function, and squaring the sequence element by element to obtain an envelope r so that the envelope r follows the Nakagami-m distribution of the parameters of (m, omega);

s2: the corresponding phase phi is obtained by a rejection method to generate uniform distribution

Generates a random number x obeying uniform distribution

Random number of

B is

Is at a maximum value of

Then, then

Otherwise, repeating the step;

s3: binding envelope

And

phase, establishing a corresponding complex channel of

。

In wireless communication, a transmission signal is often influenced by occlusion, absorption, reflection, refraction and diffraction caused by various objects in the environment during the propagation process, and multiple path signal components are formed to reach a receiver. The signal components of different paths have different propagation delays, phases and amplitudes and are added with channel noise, and their superposition causes the composite signals to cancel or enhance each other, resulting in severe fading. Such fading can reduce the available power of the desired signal and increase the effects of interference, resulting in distortion, broadening, overlapping and distorting the received signal at the receiver, and even causing substantial errors in the demodulator output of the communication system, resulting in complete failure to communicate. Therefore, in order to improve the quality of wireless communication, intensive research and analysis on the transmission characteristics of wireless channels are required.

Wireless channel modeling refers to establishing a mathematical model to analyze the characteristics of a channel and simulate the actual conditions of the channel. Compared with the traditional field actual measurement, the method can be widely applied due to the fact that the test workload and difficulty can be greatly reduced, and the cost can be saved.

For the simulation of the flat fading channel, a Clarke model based on scattering waves is often adopted, and the model indicates that in a channel environment with uniform scattering and no direct path, the signal envelope conforms to Rayleigh distribution; in a channel environment with a direct path, the signal envelope conforms to a rice distribution. However, the description of the model on the fast fading in the long-distance channel is quite rough, the phenomenon is firstly observed by Nakagami, and the density function based on the variable parameter gamma distribution is established to fit the obtained experimental data to obtain the approximate distribution. For the simulation method of the Nakagami channel, Brute force method, inverse transformation method and truncation method are commonly used at present.

Further, b in the step S2 is

Is at a maximum value of

Maximum value of

(ii) a If it is

Maximum value

。

Further, in the actual simulation, at

Approach to 0 time

Get it

And (4) inputting simulation values to realize actual simulation.

Further, the air conditioner is provided with a fan,

taking a value within a function, wherein

(ii) a The requirements are met,

i.e. gamma distribution.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. the invention discloses a Nakagami fading complex channel simulation method, which generates a Nakagami-m complex channel by calling a Gamma function to obtain a parameter, quickly generates a random number obeying Nakagami-m distribution by using a simple algorithm, thereby knowing that phase information of the Nakagami-m distribution is related to a fading parameter m value, and then according to an envelope

And

phase, establishing corresponding complex channel.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not used as limitations of the present invention.

Examples

The invention relates to a Nakagami fading complex channel simulation method, which comprises the following steps:

s1: obtaining a time domain signal sequence of Gamma distribution with the parameter of (m, omega/m) by calling a Gamma function, and squaring the sequence element by element to obtain an envelope

So as to envelop

A Nakagami-m distribution obeying the parameters (m, Ω);

s2: corresponding phase

By obtaining with a discardment method, a uniform distribution of obedience is generated

Generates a random number x obeying uniform distribution

Random number of

B is the maximum value of

If, if

Then, then

Otherwise, repeating the step;

s3: binding envelope

And with

Phase, establishing a corresponding complex channel of

。

In the step S2, b is

Is at a maximum value of

Maximum value

(ii) a If it is

Maximum value

。

In the actual simulation, at

Approach to 0 time

Get it

And (4) inputting simulation values to realize actual simulation.

Taking a value within a function, wherein

(ii) a The requirements are met,

i.e. gamma distribution.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (4)

1. A Nakagami fading complex channel simulation method is characterized by comprising the following steps:

s1: obtaining a time domain signal sequence of Gamma distribution with the parameter of (m, omega/m) by calling a Gamma function, and squaring the sequence element by element to obtain an envelope r so that the envelope r follows the Nakagami-m distribution of the parameter (m, omega);

s2: the corresponding phase phi is obtained by a rejection method to generate uniform distribution

Generates a random number x obeying uniform distribution

Random number of

B is

Is at a maximum value of

Then, then

Otherwise, repeating the step;

s3: binding envelope

And

phase, establishing a corresponding complex channel of

。

2. The method as claimed in claim 1, wherein b in step S2 is

Is at a maximum value of

Maximum value

(ii) a If it is

Maximum value

。

3. The method as claimed in claim 2, wherein the simulation is performed in real time at

Approach to 0 time

Taking out

And (4) inputting simulation values to realize actual simulation.

4. The method of claim 2, wherein the Nakagami fading complex channel simulation method,

taking a value within a function, wherein

(ii) a Satisfy the requirement of

I.e. gamma distribution.