CN101778396A - Method for detecting cognitive user in opportunity spectrum sharing system - Google Patents

Abstract

The invention discloses a method for detecting a cognitive user in an opportunity spectrum sharing system, which relates to a design method for detecting a master user and sending data information frame length by the cognitive user (secondary user) in a system based on an opportunity spectrum access (OSA) technique in a cognitive network. The method comprises the following steps of: firstly, analyzing the testing frequency based the signal interference noise ratio of the secondary user; and secondly, defining the frame length of data transmission of the secondary user based on the testing frequency and the spectral optimization. A control channel is needed to be added in a single-channel multi-user scene, the selection and the scheduling of users are performed first, and then a method for detecting a single user is implemented. The basic thought of the method that the occupation condition of an authorized channel by the master user and the influence on the signal interference noise ratio (SINR) of the secondary user by the master user are analyzed, and thus the detection frequency and the transmission frame length of the secondary user are designed, and an optimizing and compromising scheme is found between the throughput of the secondary user and the collision probability with the master user.

Description

The detection method of cognitive user in opportunity spectrum sharing system

Technical field

The present invention relates generally to the method for designing that based on cognitive user (inferior user) in opportunistic spectrum access (OSA) technological system main user is detected and sends the data message frame length in a kind of cognition network.The basic thought of this method is to analyze main user influence to inferior subscriber signal interference-to-noise ratio (SINR) is appearred in the occupancy of authorization channel and main user, and design time user with this and detect frequency and transmission frame length, inferior user throughput and and main user's collision probability between find and optimize and the scheme of compromise.

Background technology

Opportunistic spectrum access (OSA) technology is meant and need not cooperation between the primary and secondary user that inferior user acts according to circumstances and uses main user's frequency spectrum resource.Main user need not to know time user's existence, brings extra expense can for main user.Inferior user at first intercepts local frequency spectrum, searching idle channel before access; If there is idle channel, just inferior user inserts; If temporarily do not have, just inferior user waits for that main user discharges channel; In inferior telex network process, in case main user need take the channel that time user is using, inferior user this channel of rapid release at the appointed time uses for main user.Therefore, in the OSA system, inferior user need detect in time to main user, and inferior user's detection time, the frame length that detects frequency and inferior user data transmission all have fundamental influence to inferior user's transmission quality itself and to main user's interference and transmission quality.

If detection time is long, frequency is high, the detection probability height of cognitive nodes is just can protect authorized user better.Simultaneously, this can bring time user to transmit the increase of interruption frequency, and the throughput of inferior user service data transmission reduces, and brings time delay thus.Therefore, for inferior user, hope has a rational transmission time and detection frequency, makes time user that as far as possible more chances of transmitting data continuously can be arranged, and transmits more business datum, and try one's best minimizing and main user's collision.

Same problem is present in single user's single channel applied environment and the multi-user competes the single channel environment, and the basic thought of the design under the different scenes is consistent, but needs to carry out necessary scheduling and coordination between the multi-user.

Summary of the invention

Technical problem: the purpose of this invention is to provide the detection method of a kind of cognitive user in opportunity spectrum sharing system, this method is based on cognitive user (inferior user) in opportunistic spectrum access (OSA) technological system main user to be detected and sends the method for designing of data message frame length in the cognition network, this method addresses the above problem and/or shortcoming, and the detection method that time user takes into account the increase throughput, reduces interference and conflict in a kind of cognition network is provided.

Technical scheme: the detection method of cognitive user of the present invention in opportunity spectrum sharing system is based on above consideration, solution is in wireless cognition network, between inferior user or inferior user, main user is detected the design of frequency and time user's transmission frame length, reach time user throughput and and main user's collision probability between optimization and compromise.

This method comprises two parts: the one, detect frequency from inferior subscriber signal interference-to-noise ratio angle analysis; The 2nd, from detecting the frame length of frequency and frequency spectrum optimization viewpoint definition time user data transmission; In single channel multi-user scene, need to increase control channel, at first carry out user's selection and scheduling, implement the detection method of unique user again, be specially:

1). single channel list user scene

Step 1: inferior user detects main user in the time at i, judges whether to exist main user, if exist main user to continue the detection of next i time; If there is no then time user according to main user to channel take rule and the channel conditions of self calculates its frame length T;

Step 2: according to Mathematical Modeling and the probabilistic method of main user to channel occupancy, calculate the average time user of time user when bumping Signal Interference and Noise Ratio SINR with main user, and the average SINR of inferior user when not bumping with main user;

Step 3: calculate the average boundary that can reach maximum throughput when time user and main user do not bump according to the average SINR of inferior user when not bumping with main user;

Step 4:, obtain the optimum time user's frame length that obtains from the spectrum efficiency optimal angle according to optimization criterion;

Step 5: according to the average SINR of inferior user when bumping with main user, and the average SINR of inferior user when not bumping with main user, in conjunction with the second-order statistics of SINR, calculate the inferior user who obtains from the SINR statistical property and detect frequency;

Step 6: detect at optimum the user's frame length that obtains from the spectrum efficiency optimal angle with from the inferior user that the SINR statistical property obtains and to get minimum value between frequency and obtain final inferior user's frame length T; After calculating T, carry out transfer of data in the time at T-i; After the transfer of data of a frame is intact, judge whether time user's data has been transmitted, if transmitted, inferior user sends CTS message to authorization channel, withdraws from this authorization channel; If inferior user data has not transmitted, then repeat above detection and transmission course,

2). single channel multi-user scene

In single channel multi-user scene, the concrete implementation step of inferior user's detection method is:

Step 7: distribute time slot i by control channel, N time user who exists in the current system in time at i carries out joint-detection to authorization channel, and the result fed back to control channel, carry out data fusion and judge whether main user exists by control channel, if exist then proceed joint-detection in the next i time; If there is no, control channel is according to optimizing utility function

Select best access time user i, and send RTS/CTS message to i;

Step 8: selected inferior user carries out the detection step in single user's scene after receiving the message of control channel, and inferior user i calculates its frame length T according to main user to the channel conditions that takies rule and self of channel _i, and at T _iThe data of transmission time user i in the-i;

Step 9: when a frame data end of transmission, system judges whether all data of time user i have been transmitted, if transmitted, inferior user sends CTS message to control channel, withdraw from this authorization channel, control channel upgrades user's combination, and enters new round detection and transmission course; If inferior user data has not transmitted, then continue to repeat above the detection and transmission course.

Beneficial effect: experimental result proves, this scheme has realized that the effective collision between inferior user and main user suppresses, frequency spectrum share efficiently, and realized the fairness and the low probability conflict of competition between inferior user.And the not extra expense that increases the primary and secondary user of the scheme that the present invention proposes only need increase a control channel in multi-user's scene, realizes that cost and complexity are low.

Description of drawings

By below in conjunction with the accompanying drawing and the detailed description of carrying out, it is clearer that above and other objects of the present invention, characteristics and advantage will become, wherein;

Fig. 1 shows single CU authorization channel and detects the frame structure case of authorization channel.

Fig. 2 shows the frame structure case that the multi-user takies authorization channel and detects authorization channel.

Fig. 3 shows scheme flow chart among Fig. 1.

Fig. 4 shows scheme flow chart among Fig. 2.

Embodiment

Fig. 1 shows that single main CU authorization channel and single user detect authorization channel and in the frame structure case of authorization channel transmission data.With reference to Fig. 1, main user takies index of coincidence on-off discharge model to authorization channel.Main CU channel in this model, the average duration of promptly opening is β ₀Main user is busy channel not, and promptly the average duration of Guaning is β _i, main user is t by busy channel to discharging the used time of channel, its obeys index distribution.Suppose that time user's frame length is T, the t millisecond time is used for the detection to main subscriber channel before the transmission data.When detecting main user and not existing, transmit time user data in the time at T-i, in the transmission data procedures, main user can occur at any time, and the primary and secondary user data package can bump and made time user's data packet loss this moment.Frame length T has not only determined inferior user to transmit data length (inferior user throughput) but also has determined the frequency (collision probability) that inferior user detects main user.Fig. 2 shows single authorization channel multi-user's case.With reference to Fig. 2, also there is race problem between time user simultaneously in the same problem of determining frame length T that exists.

At first, here Ding Yi term definition is as follows:

SINR: inferior user's Signal Interference and Noise Ratio

γ：SINR

β ₀: the average duration of main CU channel

β _i: main user discharges the average duration of channel

T: main user by busy channel to discharging the used time of channel

Tt: main user is by discharging channel to the used time of busy channel

I: inferior user is to main user's detection time

T: inferior user's frame length

I: i time user

T _i: the frame length of inferior user i

P ₀: main user is in the received power of inferior user's receiving terminal

P _s: inferior user is in the received power of inferior user's receiving terminal

N: system is number of users last time

N ₀: AWGN power

N _j: the SINR level passes through SINR thresholding γ _jLevel crossing rate

P (): probability density function

F (): exponential distribution function

B: the channel width of authorization channel

γ _c(T, τ, P _s, P ₀): time user's instantaneous SINR when bumping with main user

Time user's average SINR when bumping with main user

γ _Nc(T, τ, P _s, P ₀): time user's instantaneous SINR when not bumping with main user

Time user's average SINR when not bumping with main user

Time user can reach the on average lower bound of throughput when not bumping with main user

I user can reach the on average lower bound of throughput when not bumping with main user when optimum frame length

T ^*: the inferior user's that the optimization throughput obtains optimum frame length

T _i ^*: i time user's that the optimization throughput obtains optimum frame length

DF (P _s, P ₀): the inferior user's who obtains according to second-order statistics frame length

f _D: the maximum doppler frequency of fading channel

The average SINR of fading channel

RTS/CTS: request transmission/clear to send

The design that inferior user detected and sent the data message frame length is as follows:

1. single user's single channel scenario:

With reference to Fig. 1, in the time, when main user occurred, inferior user's SINR was expressed as at T

Because t obeys following exponential distribution

Average SINR when bumping at this moment, is expressed as

Similarly, in the time, when main user did not occur, inferior user's SINR was expressed as at T

Tt obeys following exponential distribution

$f\left(\mathrm{tt}\right)=\frac{1}{{\mathrm{\β}}_1}\exp (-\frac{\mathrm{tt}}{{\mathrm{\β}}_1})\mathrm{dt}$

Average SINR when not bumping at this moment, is expressed as

The corresponding time user of this SINR can reach one of throughput on average lower bound, promptly

Inferior user is in the wireless authorization channel, and its characteristic of channel is consistent with the fading channel characteristic, and under the fading channel condition, the second-order statistics of inferior user SINR comprises two important parameters of the level crossing rate and the average duration of fading.

Inferior user's frame length T is by following formula definition

T＝min(T ^*，DF(P _s，P ₀))

T ^*Obtain by following optimization

DF (P _s, P ₀) obtain by following formula

At this,

$N_j=\sqrt{\frac{2\mathrm{\π}{\mathrm{\γ}}_j}{\stackrel{\‾}{\mathrm{\γ}}}}{f}_D{e}^{-{\mathrm{\γ}}_j/\stackrel{\‾}{\mathrm{\γ}}}$

2. multi-user's single channel scenario

Each time user's frame length is definite consistent with single user's single channel scenario in multi-user's single channel scenario, and different is scheduling and the distribution that has increased MAC between inferior user, to avoid the collision between time user.For this reason, need a control channel.With reference to Fig. 2, participate in the individual time joint detection of users authorization channel of N of application authorization channel in time and testing result is sent to control channel at i, control channel obtains result that main user is detected by data fusion, if main user does not occur, according to the utility function of the maximization availability of frequency spectrum

$\underset{i}{\arg \max }{\left(\stackrel{\‾}{R_{\min }}\left(T_i^{*}\right)\right)}_i$

Select the best channel time user i that uses, and by send the RTS/CTS order to inferior user i.When the frame length end of transmission of inferior user i, above process repeats, and selects the use time user and the corresponding frame length of next frame.

Preferential embodiment of the present invention is here described below with reference to accompanying drawings.Because known function and structure make the present invention fuzzy in unnecessary details, therefore they are described no longer in the following description.

A. single channel list user scene

With reference to Fig. 3, the concrete implementation step of time user's detection scheme is in single channel list user scene:

In step 310, inferior user detects main user in the time at i.In step 312, judge whether to have main user, if having main user then return step 310; If there is no then time user carries out transfer of data at the T-i that calculates in the time.After the transfer of data of a frame is intact, judge in step 316 whether all data of time user have been transmitted, enter step 318 if transmitted, inferior user sends CTS message to authorization channel, withdraws from this authorization channel.If inferior user data has not transmitted, then enter step 310, repeat above the detection and transmission course.

B. single channel multi-user scene

With reference to Fig. 4, the concrete implementation step of time user's detection scheme is in single channel multi-user scene: in step 410, distribute time slot i by control channel, N time user who exists in the current system in time at i carries out joint-detection to authorization channel, and the result fed back to control channel, carry out data fusion and judge in step 412 whether main user exists by control channel.If exist then return step 410; If there is no, in step 414, control channel is according to utility function

Select best access time user i, and send RTS/CTS message to i.After receiving message, inferior user i is according to the corresponding frame length T of state computation of oneself _i, and in Ti-i the data of transmission time user i.Whether all data of judging time user i in step 418 have been transmitted, and enter step 420 if transmitted, and inferior user sends CTS message to control channel, withdraws from this authorization channel, and control channel upgrades user's combination in step 422, and reenters step 410.If inferior user data has not transmitted, then enter step 410, repeat above the detection and transmission course.

Claims (1)

1. the detection method of a cognitive user in opportunity spectrum sharing system is characterized in that this method comprises two parts: the one, detect frequency from inferior subscriber signal interference-to-noise ratio angle analysis; The 2nd, from detecting the frame length of frequency and frequency spectrum optimization viewpoint definition time user data transmission; In single channel multi-user scene, need to increase control channel, at first carry out user's selection and scheduling, implement the detection method of unique user again, be specially:

1). single channel list user scene

Step 1: inferior user detects main user in the time at ι, judges whether to exist main user, if exist main user to continue the detection of next ι time; If there is no then time user according to main user to channel take rule and the channel conditions of self calculates its frame length T;

Step 2: according to Mathematical Modeling and the probabilistic method of main user to channel occupancy, calculate the average time user of time user when bumping Signal Interference and Noise Ratio SINR with main user, and the average SINR of inferior user when not bumping with main user;

Step 3: calculate the average boundary that can reach maximum throughput when time user and main user do not bump according to the average SINR of inferior user when not bumping with main user;

Step 4:, obtain the optimum time user's frame length that obtains from the spectrum efficiency optimal angle according to optimization criterion;

Step 5: according to the average SINR of inferior user when bumping with main user, and the average SINR of inferior user when not bumping with main user, in conjunction with the second-order statistics of SINR, calculate the inferior user who obtains from the SINR statistical property and detect frequency;

Step 6: detect at optimum the user's frame length that obtains from the spectrum efficiency optimal angle with from the inferior user that the SINR statistical property obtains and to get minimum value between frequency and obtain final inferior user's frame length T; After calculating T, in the T-ι time, carry out transfer of data; After the transfer of data of a frame is intact, judge whether time user's data has been transmitted, if transmitted, inferior user sends CTS message to authorization channel, withdraws from this authorization channel; If inferior user data has not transmitted, then repeat above detection and transmission course,

2). single channel multi-user scene

In single channel multi-user scene, the concrete implementation step of inferior user's detection method is:

Step 7: distribute time slot ι by control channel, N time user who exists in the current system in time at ι carries out joint-detection to authorization channel, and the result fed back to control channel, carry out data fusion and judge whether main user exists by control channel, if exist then proceed joint-detection in the next ι time; If there is no, control channel is according to optimizing utility function

Select best access time user i, and send RTS/CTS message to i;

Step 8: selected inferior user is after receiving the message of control channel, carry out the detection step in single user's scene, inferior user i calculates its frame length Ti according to main user to the channel conditions that takies rule and self of channel, and in Ti-ι the data of transmission time user i;

Step 9: when a frame data end of transmission, system judges whether all data of time user i have been transmitted, if transmitted, inferior user sends CTS message to control channel, withdraw from this authorization channel, control channel upgrades user's combination, and enters new round detection and transmission course; If inferior user data has not transmitted, then continue to repeat above the detection and transmission course.

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