KR101669195B1 - Method of Opportunistic Feedback for Cooperative Spectrum Sensing in Cognitive Radio Network - Google Patents

Method of Opportunistic Feedback for Cooperative Spectrum Sensing in Cognitive Radio Network Download PDF

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KR101669195B1
KR101669195B1 KR1020150068606A KR20150068606A KR101669195B1 KR 101669195 B1 KR101669195 B1 KR 101669195B1 KR 1020150068606 A KR1020150068606 A KR 1020150068606A KR 20150068606 A KR20150068606 A KR 20150068606A KR 101669195 B1 KR101669195 B1 KR 101669195B1
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feedback
contention
users
channel
energy
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소재우
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서강대학교 산학협력단
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/02—Resource partitioning among network components, e.g. reuse partitioning
    • H04W16/10—Dynamic resource partitioning
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0808—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA]

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Abstract

The present invention relates to a feedback transmission method for cooperative spectrum sensing in a cognitive radio network. According to the present invention, a feedback transmission method for cooperative spectrum sensing in a cognitive radio network includes the steps of: (a) sensing energy to detect a primary user by K secondary users for sensing the cooperative spectrum in the cognitive radio network; and (b) transmitting feedback information for the sensed energy to a fusion center through a contention-based feedback channel by a portion of the secondary users. The number of the contention-based feedback channels is smaller than the K. According to the present invention, the secondary user can improve a channel use efficiency in the cognitive radio network.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a feedback transmission method for cooperative spectrum sensing in a cognitive radio network,

The present invention relates to an efficient feedback transmission method for cooperative spectrum sensing in a cognitive radio network.

The cognitive radio technology is a technique for increasing the use efficiency of frequency resources by enabling a secondary user to use a frequency channel when a primary user who is permitted to use the frequency does not use the frequency channel.

To do this, the next-level user finds an empty channel that is not used by the senior user and uses it within a range that does not cause interference. For this purpose, the next-level user needs to quickly and accurately detect which channel has the highest priority user. For this purpose, the next-generation user mainly uses an energy detection method for sensing the channel.

Cooperative Spectrum Sensing (CSS), which detects the existence of a senior user by sensing a plurality of users in the energy detection scheme, is emerging as a powerful method. The reason why a large number of users are participating in sensing is that if only one subordinate user performs sensing under an uncertain radio environment such as multipath fading or shadowing, it may not be possible to accurately detect the existence of a senior user. It is vulnerable.

The cooperative spectrum sensing method feeds back the result of sensing by each of the plurality of subordinate users to the fusion center, and the fusion center finally judges the presence of a senior user in the channel by using the feedback information. The spatial diversity gain in the wireless channel can be obtained by using the feedback information received from the plurality of rank order users.

This cooperative spectrum sensing scheme has a problem in that the overhead for feedback transmission increases linearly as the number of the users who are next to each other increases. In order to solve such an overhead problem, the next order user inputs feedback information to 1 bit (or 2 bits) like a method of feeding back the sensed result to 1 when the sensed energy value exceeds a certain threshold value, There is a disadvantage in that the performance of detecting a senior user is deteriorated.

Therefore, a feedback transmission method that can reduce the overhead for feedback information transmission while maintaining excellent detection performance for the senior user is required through cooperative spectrum sensing in an environment where a large number of users are involved.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a method and apparatus for preventing excessive overhead for feedback transmission even when a large number of next- The present invention provides a feedback transmission method that enables a user to perform a feedback transmission.

In order to accomplish the objects of the present invention as described above and achieve the characteristic effects of the present invention described below, the characteristic structure of the present invention is as follows.

According to an embodiment of the present invention, an efficient feedback transmission method for cooperative spectrum sensing in a cognitive radio network is provided in which K subordinate users for sensing coherent spectrum in a cognitive radio network ) step; And (b) transmitting feedback information regarding the sensed energy to a fusion center through a contention-based feedback channel. In this case, the number of the contention-based feedback channels is a constant smaller than K.

According to another embodiment of the present invention, an efficient feedback transmission method for cooperative spectrum sensing in a cognitive radio network is disclosed in which a K subordinate users for sensing cooperative spectral sensing in a cognitive radio network ) step; (B) transmitting feedback information about sensed energy information to a fusion center through a contention-based feedback channel; And (c) transmitting the feedback information regarding the sensed energy information to the fusion center through a contention-based feedback channel. Wherein the sum of the number of contention-based feedback channels and the number of contention-based pad back channels is a constant smaller than K.

According to the present invention, in performing cooperative spectrum sensing in a cognitive radio network, overhead caused by feedback transmission can be reduced while preventing deterioration in detection performance in detecting a senior user.

FIG. 1 is a diagram illustrating a structure of a feedback channel (reporting channel) according to an embodiment of the present invention.
2 is a diagram illustrating a structure of a feedback channel according to another embodiment of the present invention.
3 is a diagram illustrating a process of performing feedback transmission using a contention-based common feedback channel according to an embodiment of the present invention.
4 is a graph showing channel utilization efficiency according to a feedback transmission scheme.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

FIG. 1 is a diagram illustrating a structure of a feedback channel (reporting channel) according to an embodiment of the present invention.

The frame structure in the perceived wireless network can be divided into a sensing period 10, a reporting period 20, and a data transmission period 30.

In the sensing period 10, each successive user senses the energy of the channel. The magnitudes of the energy values sensed by the secondary users are typically different. Even if a senior user is present, the second-order user can effectively sense the effect due to multipath fading or the shading effect in the shadow region of radio waves.

In the reporting period 20, the next-ranked user feeds information on the energy value obtained by sensing the channel to the fusion center. Since the overhead for feedback transmission can be linearly increased when the number of the next-highest users increases, all subordinate users perform feedback transmission through a contention-based dedicated channel, . In other words, the overhead can be reduced by reducing the number of next-generation users participating in the feedback.

2 is a diagram illustrating a structure of a feedback channel according to another embodiment of the present invention.

The frame structure in this embodiment is divided into a sensing period 10, a reporting period 40, and a data transmission period 30, as in FIG. The reporting period 40 comprises a contention-based common feedback channel 41 and a contention-based dedicated channel 42. That is, a channel for feedback transmission is dedicated for some subordinate users, and the remaining subordinate users perform feedback transmission through a common feedback channel based on a contention.

3 is a diagram illustrating a process of performing feedback transmission using a contention-based common feedback channel according to an embodiment of the present invention.

The next-highest-level user senses the channel during the sensing period, and determines whether the energy value Yk detected in the channel exceeds a predetermined threshold value? (S10). The next-highest user whose energy value does not exceed the threshold does not send feedback. If the threshold is large, the number of next-generation users participating in the feedback can be reduced, and if the threshold is small, the number of next-generation users participating in the feedback can be reduced. This threshold may be set high as the number of next-generation users participating in the perceived wireless network increases and may be used to reduce the overhead associated with feedback transmission. During the sensing period, the next user who detects the energy level above the threshold transmits the feedback transmission to the fusion center through competition. The feedback transmission process is as follows.

First, the current feedback channel number (i) of the contention-based common pad back channel is set to 1 (S20) and a random function is executed.

The output value rand of the random function is compared with a specific value p in step S30 and if the output value rand of the random function is smaller than the specific value p, And waits for an opportunity to transmit feedback (S60).

If the output value rand of the random function is larger than the specific value p, the sensing information is transmitted in the current feedback channel (S40). Then, it is determined whether the current feedback channel number is the last channel of the contention-based common feedback channel (S50).

If the current feedback channel is the last channel, the feedback transmission is terminated, but if not, the next pad back channel waits for an opportunity to transmit feedback (S60).

The mathematical performance analysis of feedback transmission according to Cooperative Spectrum Sensing with Opportunistic Feedback (OF-CSS) employing opportunistic feedback is as follows.

First, regardless of the number of next-highest users (K), the number of feedback channels is

Figure 112015047089592-pat00001
And
Figure 112015047089592-pat00002
Is less than K. In the case of having the frame structure according to Fig. 2
Figure 112015047089592-pat00003
Can be expressed as,
Figure 112015047089592-pat00004
Means the number of contention based common feedback channels,
Figure 112015047089592-pat00005
Quot; means the number of contention-free dedicated feedback channels.

Figure 112015047089592-pat00006
The user of the next order can transmit the feedback signal without collision through the dedicated feedback channel,
Figure 112015047089592-pat00007
Sub-users
Figure 112015047089592-pat00008
The feedback information is transmitted competingly using the feedback channels. At this time, K-
Figure 112015047089592-pat00009
The users of the next order are selected from the first feedback channel according to the probability p using the random function
Figure 112015047089592-pat00010
Th feedback channel to the fusion center when the energy value observed is greater than the threshold value eta. At this time, the values of p and eta are periodically broadcast by the fusion center, and need not be transmitted every frame. H. Li, Q. Guo, and D. Huang, "Throughput analysis of opportunistic feedback for downlink multiuser diversity with capture effect" IEEE Commun. Lett., Vol. 16, no. 1, pp. 44-46, Jan. 2012 (hereinafter, referred to as reference 1). When the Fusion Center receives k signals on the feedback channel, it can correctly decode the i-th signal if the received power of the i-th signal is greater than the sum of the interference of other signals. Such a previous capture probability (p c ) is obtained when k transmitted signals are transmitted under Rayleigh fading channels after some computation according to reference 1
Figure 112015047089592-pat00011
. Of course, the Fusion Center can count the number of decoded correctly by checking the error detection code in the received feedback message.

A total of M feedback signals are received at the fusion center, and the sensing information of the m-th feedback signal is

Figure 112015047089592-pat00012
, The false alarm probability is given by Equation (1). &Quot; (1) "

[Equation 1]

Figure 112015047089592-pat00013

here

Figure 112015047089592-pat00014
Wow
Figure 112015047089592-pat00015
Is the j-th weight and sensing information, respectively, and P D is the detection probability.

( K - b d ) of the subordinate users,

Figure 112015047089592-pat00016
The probability of sensing a higher priority user signal is given by Equation (2).

&Quot; (2) "

Figure 112015047089592-pat00017

here

Figure 112015047089592-pat00018
Is the Bernoulli probability.

The probability of successfully transmitting the transmitted packet to the fusion center when the n-order users transmit the feedback signal through the contention-based common feedback channel is expressed by Equation (3).

&Quot; (3) "

Figure 112015047089592-pat00019

Where p is the probability for accessing the feedback channel (using a random function), and Pc (k) is the capture probability for successfully decoding one signal.

At this time,

Figure 112015047089592-pat00020
The probability of successfully receiving the m feedback signals through the feedback channels is given by Equation (4).

&Quot; (4) "

Figure 112015047089592-pat00021

here

Figure 112015047089592-pat00022
,
Figure 112015047089592-pat00023
,
Figure 112015047089592-pat00024
to be.

Finally, the probability of false alarms at the Fusion Center is calculated as shown in Equation (5).

&Quot; (5) "

Figure 112015047089592-pat00025

The channel utilization efficiency of the subordinate user using the probability of false alarms derived from the above equation and the number of limited feedback channels can be calculated as shown in Equation (6).

&Quot; (6) "

Figure 112015047089592-pat00026

here,

Figure 112015047089592-pat00027
Ws is the amount of resources used for sensing, and wt is the amount of resources used by the next-level user to transmit data.

4 shows channel utilization efficiency of the subordinate user when using the feedback scheme according to the present invention.

In the case of conventional cooperative spectrum sensing (Conventional CSS), as the number K of the next-ranked users (SUs) increases, the channel utilization efficiency increases and then decreases over a certain limit. This is due to the overhead due to feedback transmission.

In the case of opportunistic feedback-based collaborative spectrum sensing (OF-CSS), channel utilization efficiency continues to increase as the number of next-generation users increases. However, as shown in FIG. 4, the efficiency is inferior to the conventional CSS in the initial stage. OF-CSS means that the Fusion Center does not use a capture effect or a dedicated feedback channel.

The efficiency of the opportunistic feedback scheme (OF-CSS / CD) using the dedicated feedback channel depends on the number of dedicated feedback channels and whether the threshold value η th is optimized. When the number of subscribers increases, the channel utilization efficiency increases as the threshold value increases. However, it can be seen that there is an inefficient characteristic when the number of subscribers decreases.

That is, it can be seen that the efficiency is high when the number of the next-highest users is increased when only the feedback based on the contention-based common feedback channel as shown in FIG. 1 is used. As shown in FIG. 2, The channel utilization efficiency may be varied depending on whether or not the dedicated contention-based dedicated feedback channel is optimized, but it is more efficient than the case of using only the contention-based common feedback channel.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Therefore, the spirit of the present invention should not be construed as being limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, I will say.

Claims (6)

An efficient feedback transmission method for cooperative spectrum sensing in a cognitive wireless network,
(A) for K consecutive users to sense energy for the detection of senior users for cooperative spectrum sensing in a cognitive wireless network; And
And (b) transmitting feedback information about the sensed energy to a fusion center through a contention-based feedback channel,
Wherein the number of the contention-based feedback channels is a constant smaller than the K. The method according to claim 1,
Wherein the magnitude of energy sensed by the users transmitting feedback information to the fusion center among the subordinate users exceeds a predetermined threshold value (?). 3. The method of claim 2,
Wherein the users transmitting the feedback information have a value calculated by a random function in a contention-based feedback channel that exceeds a predetermined threshold value. An efficient feedback transmission method for cooperative spectrum sensing in a cognitive wireless network,
(A) for K consecutive users to sense energy for the detection of senior users for cooperative spectrum sensing in a cognitive wireless network;
(B) transmitting feedback information about sensed energy information to a fusion center through a contention-based feedback channel; And
(C) transmitting the feedback information about the sensed energy information to the fusion center through a contention-based feedback channel
Lt; / RTI >
Wherein the sum of the number of contention-based feedback channels and the number of contention-based pad back channels is a constant smaller than K. 5. The method of claim 4, wherein a magnitude of energy sensed by users transmitting feedback information to a fusion center through a contention-based feedback channel among the subordinate users exceeds a predetermined threshold value. A recording medium on which computer program codes for executing the method of any one of claims 1 to 5 are recorded.
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KR20220051767A (en) * 2020-10-19 2022-04-26 주식회사 엘지유플러스 Method for wireless resource scheduling in wireless communication system

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US20100226312A1 (en) 2009-03-04 2010-09-09 Samsung Electronics Co., Ltd. Apparatus and method for transmitting coexistence beacon protocol packet in cognitive radio wireless communication system

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US20100226312A1 (en) 2009-03-04 2010-09-09 Samsung Electronics Co., Ltd. Apparatus and method for transmitting coexistence beacon protocol packet in cognitive radio wireless communication system

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Title
해양 인지 무선 네트워크에서 협력적 센싱 기법의 성능 평가

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KR20220051767A (en) * 2020-10-19 2022-04-26 주식회사 엘지유플러스 Method for wireless resource scheduling in wireless communication system
KR102471617B1 (en) 2020-10-19 2022-11-28 주식회사 엘지유플러스 Method for wireless resource scheduling in wireless communication system

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