WO2014121459A1

WO2014121459A1 - A method and apparatus for cooperative spectrum sensing

Info

Publication number: WO2014121459A1
Application number: PCT/CN2013/071441
Authority: WO
Inventors: Jingyu FENG; Guangyue LU
Original assignee: Nokia China Investment Co Ltd; Nokia Inc
Current assignee: Nokia China Investment Co Ltd; Nokia Inc
Priority date: 2013-02-06
Filing date: 2013-02-06
Publication date: 2014-08-14
Anticipated expiration: 2015-08-06

Abstract

A method for cooperative spectrum sensing may comprise: obtaining a social tie value of a first user, in response to receiving from the first user a message querying sensing information, wherein the social tie value reflects a degree of sharing sensing information by the first user with one or more second users; and determining whether to provide the queried sensing information to the first user based at least in part on the social tie value.

Description

A METHOD AND APPARATUS FOR COOPERATIVE SPECTRUM SENSING

FIELD OF THE INVENTION

The present invention generally relates to Cognitive Radio Networks (CRN). More specifically, the invention relates to Cooperative Spectrum Sensing (CSS).

BACKGROUND

As the rapid growth of wireless communication technologies and the huge demand of the capacity for wireless applications, the frequency spectrum has become a scarce resource. However, a large portion of the assigned spectrum is not utilized efficiently. According to the Federal Communications Commission (FCC), temporal and geographical variations in the utilization of the assigned spectrum range from 15% to 85%. To solve the contradiction between the spectrum scarcity and the low spectrum utilization, CRNs have been proposed to make effective use of the frequency spectrum by opportunistically using the spectrum of the licensed users. The licensed users may be called as Primary Users (PUs) and the users of the CRNs may be called as Secondary Users (SUs).

CSS is one of the key technologies in the realization of CRNs, since it enables SUs to find the unused spectrum bands without causing harmful interference to PUs. The main idea of CSS is to enhance the sensing performance by exploiting spatial diversity via the observations of spatially located SUs. By cooperation, SUs can share their sensing information for the CSS system to make a combined decision with increased accuracy as comparing with the individual decisions. Thus it is desirable to investigate a scheme for enhancing the system performance of CSS with effective collaboration of SUs.

SUMMARY The present description introduces a Social Tie-based Incentive Scheme (STIS) for CSS, which is a useful mechanism to improve the sensing performance of CSS by enhancing collaboration in a CRN effectively and efficiently. With the proposed scheme, a user in a CSS environment may easily find sensing information sources and also be willing to share its sensing result with other users in the CRN. Therefore the user in the CRN can make a more accurate decision of spectrum sensing by combining respective decisions from more other users.

According to a first aspect of the present invention, there is provided a method comprising: obtaining a social tie value of a first user, in response to receiving from the first user a message querying sensing information, wherein the social tie value reflects a degree of sharing sensing information by the first user with one or more second users; and determining whether to provide the queried sensing information to the first user based at least in part on the social tie value.

According to a second aspect of the present invention, there is provided an apparatus comprising: at least one processor; and at least one memory comprising computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: obtain a social tie value of a first user, in response to receiving from the first user a message querying sensing information, wherein the social tie value reflects a degree of sharing sensing information by the first user with one or more second users; and determine whether to provide the queried sensing information to the first user based at least in part on the social tie value.

According to a third aspect of the present invention, there is provided a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising: code for obtaining a social tie value of a first user, in response to receiving from the first user a message querying sensing information, wherein the social tie value reflects a degree of sharing sensing information by the first user with one or more second users; and code for determining whether to provide the queried sensing information to the first user based at least in part on the social tie value.

According to a fourth aspect of the present invention, there is provided an apparatus comprising: obtaining means for obtaining a social tie value of a first user, in response to receiving from the first user a message querying sensing information, wherein the social tie value reflects a degree of sharing sensing information by the first user with one or more second users; and determining means for determining whether to provide the queried sensing information to the first user based at least in part on the social tie value.

In an exemplary embodiment, the determination as to whether to provide the queried sensing information to the first user based at least in part on the social tie value may comprise: providing the queried sensing information to the first user if the social tie value is larger than a predefined threshold value; and rejecting to provide the queried sensing information to the first user if the social tie value is less than the predefined threshold value.

According to a fifth aspect of the present invention, there is provided a method comprising: sending from a first user to one or more second users a message querying sensing information; and getting the queried sensing information from at least one of the one or more second users which determines to provide the queried sensing information to the first user based at least in part on a social tie value of the first user, wherein the social tie value reflects a degree of sharing sensing information by the first user with the one or more second users.

According to a sixth aspect of the present invention, there is provided an apparatus comprising: at least one processor; and at least one memory comprising computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: send from a first user to one or more second users a message querying sensing information; and get the queried sensing information from at least one of the one or more second users which determines to provide the queried sensing information to the first user based at least in part on a social tie value of the first user, wherein the social tie value reflects a degree of sharing sensing information by the first user with the one or more second users.

According to a seventh aspect of the present invention, there is provided a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising: code for sending from a first user to one or more second users a message querying sensing information; and code for getting the queried sensing information from at least one of the one or more second users which determines to provide the queried sensing information to the first user based at least in part on a social tie value of the first user, wherein the social tie value reflects a degree of sharing sensing information by the first user with the one or more second users.

According to an eighth aspect of the present invention, there is provided an apparatus comprising: sending means for sending from a first user to one or more second users a message querying sensing information; and getting means for getting the queried sensing information from at least one of the one or more second users which determines to provide the queried sensing information to the first user based at least in part on a social tie value of the first user, wherein the social tie value reflects a degree of sharing sensing information by the first user with the one or more second users.

In an exemplary embodiment, the queried sensing information may be provided by the at least one of the one or more second users to the first user if the social tie value is larger than a predefined threshold value. In an exemplary embodiment, the social tie value may be regarded as larger than the predefined threshold value, if the first user is a user which queries sensing information for the first time.

According to exemplary embodiments, the social tie value of the first user may be related to at least one of the following parameters: a number of responses by the first user to queries for sensing information; a number of queries for sensing information by the first user; and a number of responses comprising correct sensing information by the first user to queries for sensing information. For example, the social tie value may be a normalized value.

In an exemplary embodiment, the social tie value of the first user maintained at a data manager may be updated based at least in part on first feedback information from the first user, and wherein the first feedback information comprises an indication that the first user queried sensing information. Alternatively or additionally, the social tie value of the first user maintained at a data manager may be updated based at least in part on second feedback information from a second user getting sensing information from the first user, and wherein the second feedback information comprises at least one of the following: an indication that the first user provided sensing information; and an indication as to whether the first user provided correct sensing information. For example, the data manager may be implemented in a centralized or distributed manner. In an exemplary embodiment, third feedback information may be generated at the first user for updating a social tie value of the at least one of the one or more second users, and wherein the third feedback information comprises at least one of the following: an indication that the at least one of the one or more second users provided sensing information; and an indication as to whether the at least one of the one or more second users provided correct sensing information.

In exemplary embodiments of the present invention, the provided methods, apparatuses, and computer program products can enable users in a CSS environment to cooperate with each other with more willingness and can achieve a better sensing performance of a CRN with less computation effort and reduced complexity of implementation. The proposed solution can resolve at least a problem of the ineffective collaboration in the CRN due to selfish SUs by inspiring the contribution of SUs in the CSS environment.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention itself, the preferable mode of use and further objectives are best understood by reference to the following detailed description of the embodiments when read in conjunction with the accompanying drawings, in which:

Fig.l is a flowchart illustrating a method for CSS, which may be performed at a cooperating SU with a corresponding apparatus in accordance with embodiments of the present invention;

Fig.2 is a flowchart illustrating a method for CSS, which may be performed at an initiator SU with a corresponding apparatus in accordance with embodiments of the present invention;

Fig.3 exemplarily shows an execution procedure of STIS in accordance with an embodiment of the present invention; and

Fig.4 is a simplified block diagram of various apparatuses which are suitable for use in practicing exemplary embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the present invention are described in detail with reference to the accompanying drawings. Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention.

When CSS technology is employed in CRNs, it confronts some technical problems. For example, the cognitive radio paradigm imposes human-like characteristics (such as learning, adaptation and cooperation) in wireless networks. From the social perspective, a SU would become selfish if no any incentive solutions. In addition, the self-organizing and distributed natures of distributed CRNs offer an ideal environment for selfish behaviors. Since CSS lacks an incentive scheme to inspire SUs, some selfish SUs may refuse to share their sensing results to save their energy or their transmission time, while still enjoying sensing results from others. The presence of selfish SUs may cause catastrophic damage to the performance of CSS, while the existing solutions can hardly inspire SUs for CSS in distributed CRNs.

To stimulate the selfish SUs to make contribution to the CSS system, recent efforts have been made to differential service-based approach in CSS using the game theory. In an approach, CSS may be modeled as an N-player horizontal infinite game and a Carrot-and-Stick strategy is proposed to use, which results in the mutual cooperation as the Nash equilibrium of the game. In another approach, the mixed strategy Nash equilibrium is proposed as a solution of the non-cooperative game among SUs for CSS. In still another approach, the interactive decision on frequency of selfish SUs is formulated as a non-cooperative game, and Nash Equilibrium corresponds to a desired frequency profile. Then, a distributed algorithm is proposed to lead the SUs to achieve a desired frequency selection outcome. However, these game theory frameworks are mostly related to the central networks and involve complex mathematically analysis and computation. In distributed CRNs, SUs generally have limited computation capability and thus a complex game theory is not a suitable solution.

It is worth noting that most SUs in CSS are rational and strategic users. For those SUs, only getting returns from CSS will they share their sensing information to others. However, most of the existing CSS schemes assume all the SUs in a CRN are willing to collaborate. In fact, some selfish SUs may refuse to provide the sensing results to save their energy or transmission time, while still enjoying the sensing results from others. Such kind of selfish behaviors may seriously degrade the performance of a CSS system. Concretely, some selfish SUs may be reluctant in the cooperation that they cannot directly beneficial from. As a consequence, the existence of selfish users makes a well designed CSS system useless. Therefore, how to efficiently and effectively resolve the selfishness problem for CRNs has become a very challenging issue to achieve a better performance of CSS.

From the social perspective, a user is willing to help others with whom he/she has social tie (such as friends, coworkers, roommates and etc.), because he/she got help from them in the past or would probably get help from them in the future. Conversely, the selfish users who do not help others would not get any help. This kind of user demand may be treated as a design metric to measure social tie and inspire selfish SUs. In view of this analysis, the exemplary embodiments of the invention propose a Social Tie-based Incentive Scheme (also called as STIS) to resolve the selfishness problem for CSS.

In an exemplary embodiment, the social tie used in the STIS strategy means that a SU has helped other SUs before, which is a design idea from the social perspective to suppress selfish behaviors. Once a SU has provided sensing information to other SUs, he/she would get a good evaluation of the social tie which may be used to judge whether the SU is selfish or not. If a SU does not help others, he/she would not get a good evaluation of the social tie. With the evaluation of the social tie, the SU can request other SUs to provide sensing information to him/her. In an area of CSS, a SU may play two roles, the role of initiator SU enjoying sensing information and the role of cooperating SU providing sensing information. For a specific SU, "other SUs" may refer to the SUs who want to enjoy sensing information from the specific SU when this SU plays the role of cooperating SU. Or else, "other SUs" may refer to the SUs who provide sensing information to the specific SU when this SU plays the role of initiator SU.

Fig.l is a flowchart illustrating a method for CSS, which may be performed at a cooperating SU with a corresponding apparatus in accordance with embodiments of the present invention. In the illustrated embodiment, the corresponding apparatus at which the method illustrated in Fig.l may be implemented can be any type of user equipment comprising portable terminals, radio terminal, wireless devices, smart phones, laptop computers, handsets, mobile stations/units/devices, multimedia tablets, Internet nodes, communicators, Personal Digital Assistants (PDAs), or any combination thereof. In a CSS environment, a first user as an initiator SU may try to use a PU's spectrum band and ask its cooperating SUs (which also may be called as second users here) to sense whether the PU's spectrum is free or in using. In response to receiving from the first user a message querying sensing information, the respective cooperating SU may obtain a social tie value of the first user, as shown in block 102. According to exemplary embodiments, the social tie value of the first user may reflect a degree of sharing sensing information by the first user with one or more second users. The usage of the STIS is to stimulate cooperation among selfish SUs. Hence, the social tie value can reflect a degree of contribution that a user provides sensing information to others. For instance, a SU may be reluctant to report his/her sensing information to those who have not helped other SUs. Therefore, the social tie may be treated as a design metric to stimulate cooperative sensing.

In an exemplary embodiment, the social tie value of the first user may be related to at least one of the following parameters: a number of responses by the first user to queries for sensing information, a number of queries for sensing information by the first user, and a number of responses comprising correct sensing information by the first user to queries for sensing information. For example, the social tie value of a SU may indicate how much the SU helps other SUs. The more contribution, the more payoff the SU can get. If the SU often helps other SUs by providing sensing information to the others, he/she may get a higher social tie value. Alternatively or additionally, it is possible that a SU may maintain a good social tie value by providing sensing information to others in several CSS exchanges, and after then the SU just enjoys sensing information from other SUs rather than contribution. Thus, a factor which is inversely proportional to the social tie value may be introduced, and if the SU often consumes sensing information rather than contribution, he/she may get a lower social tie value. Alternatively or additionally, it is also possible that a SU may maintain a good social tie value by providing false sensing information. Therefore, a penalizing parameter (such as the number of reporting correct sensing information by a SU, or a ratio of the number of reporting correct sensing information and the total number of providing sensing information by a SU) may be required to suppress this fraudulent behavior.

For example, the total number of "helping" of a SU may be denoted as r, which represents the number of responses by the SU to queries for sensing information from other SUs. If the number of responses comprising correct sensing information by the SU to queries for sensing information from other SUs is denoted as r^c, then a ratio of r^c to r may be defined as a penalizing factor σ. On the other hand, the total number of "helped" of the SU may be denoted as q, which represents the number of queries for sensing information by the SU. In accordance with exemplary embodiments, these parameters or factors may be used alone or in combination to evaluate a social tie value of the SU. From the view of cooperative sensing, a social tie value for a SU may be defined based at least in part on one or more of r, q, r^c and σ. For example, assuming there are n SUs in a CRN employing CSS, take z^'-th SU (where 1 < i < n and / is an integer), SU , as an example. Let r_t denote the number of responses performed by SU and q_t denote the number of queries performed by SU . A general evaluation metric which combines these two parameters into a social tie value of SU/ (denoted by si) may be defined in equation (1).

In the above general evaluation metric, it is possible that the SU may maintain a higher social tie value by providing false sensing information. Assuming that r_z ^c is the number of responses comprising correct sensing information by SU/, a penalizing parameter σ_ζ· defined in equation (2) for SU/ may be used to modify the general evaluation metric.

For example, the social tie value of SU/ may be modified as:

For n SUs in the CRN, the social tie values of respective SUs can be evaluated using any one of equations (l)-(3), or any other suitable combination of r, q, r^c and any other suitable parameters. Consequently, a social tie vector S can be obtained, which may be expressed as equation (4).

According to an exemplary embodiment, the social tie values in S may be normalized in a specified manner, considering that some SUs may be assigned arbitrarily high social tie values (much more than 1), and arbitrarily low local social tie (much less than 1) may be assigned to other SUs, which brings difficulty in comparing them. In an exemplary embodiment, for SU;^', its normalized social tie value s may be expressed as follows:

For example, to ensure that all social tie values are between 0 and 1, the social tie values are normalized with max(5') because it can inspire SUs to close up to a SU with the best behavior. If selfish SUs do not contribute sensing information to others, they may get a normalized social tie value less than those of other SUs.

In block 104, the cooperating SU can determine whether to provide the queried sensing information to the first user based at least in part on the social tie value. According to an exemplary embodiment, in determining whether to provide the queried sensing information to the first user based at least in part on the social tie value, the cooperating SU may provide the queried sensing information to the first user if the social tie value is larger than a predefined threshold value, or reject to provide the queried sensing information to the first user if the social tie value is less than the predefined threshold value. In an exemplary embodiment, according to the normalized social tie values, the predefined threshold value δ may be set to a moderate value, such as 0.5. The predefined threshold value may be used to identify a selfish SU. For example, if s > S, SUi may be regarded as a non-selfish SU, and other SUs may share sensing information with SU;^'. If s < δ , SU; may be regarded as a selfish SU, and other SUs may not share sensing information with SU;^'. In an exemplary embodiment, the proposed social incentive scheme may give the newcomers one chance. If the first user is a user which queries sensing information for the first time, the social tie value of the first user may be regarded as larger than the predefined threshold value. For example, if s = 0 and q_t=\, SUz may be referred to as a newcomer. In this case, the cooperators would share their sensing information to SUz. Afterwards, if SUz would like to get sensing information from others again, he/she has to help others.

According to exemplary embodiments, the social tie value of the first user may be maintained at a data manager and updated based at least in part on first feedback information from the first user. For example, the first feedback information may comprise an indication that the first user queried sensing information. With the first feedback information, the number of queries for sensing information by the first user may be increased by 1. Additionally or alternatively, the social tie value of the first user may be updated based at least in part on second feedback information from a second user getting sensing information from the first user. For example, the second feedback information may comprise at least one of the following: an indication that the first user provided sensing information, and an indication as to whether the first user provided correct sensing information. With the second feedback information, the number of responses by the first user to queries for sensing information may be increased by 1. Optionally, the number of responses comprising correct sensing information by the first user to queries for sensing information may be increased or unchanged according to the indication as to whether the first user provided correct sensing information. Considering the organization and structure of the CRN employing CSS, the data manager may be implemented in a centralized or distributed manner. Accordingly, the social tie values of SUs may be stored or maintained in a central data manager or a plurality of distributed data managers.

The described method can inspire SUs to share their sensing information only to SUs who have helped other SUs, and such willingness varies with the strength of their social tie. Thus the proposed STIS can enhance collaboration of SUs in a CRN and improve the system performance of CSS in terms of suppressing selfish SUs.

Fig.2 is a flowchart illustrating a method for CSS, which may be performed at an initiator SU with a corresponding apparatus in accordance with embodiments of the present invention. In the illustrated embodiment, the corresponding apparatus at which the method illustrated in Fig.2 may be implemented can be any type of user equipment comprising portable terminals, radio terminal, wireless devices, smart phones, laptop computers, handsets, mobile stations/units/de vices, multimedia tablets, Internet nodes, communicators, PDAs, or any combination thereof. Corresponding to the method illustrated in Fig.l, in block 202, a message querying sensing information may be sent from a first user (as an initiator SU) to one or more second users. As cooperating SUs of the first user, the one or more second users may respectively perform method as described in Fig.l with their respective apparatuses. For example, at least one of the one or more second users may determine to provide the queried sensing information to the first user, if a social tie value of the first user is larger than a predefined threshold value. In case of the first user being a user which queries sensing information for the first time, the social tie value of the first user may be regarded as larger than the predefined threshold value.

In block 204, the first user can get the queried sensing information from at least one of the one or more second users which determines to provide the queried sensing information to the first user based at least in part on a social tie value of the first user. As illustrated in connection with Fig.l, the social tie value of the first user can reflect a degree of sharing sensing information by the first user with the one or more second users, and may be a normalized value. The social tie values of an initiator SU and its cooperating SUs may be updated based at least in part on feedback information from the initiator SU, after the CSS exchange between the initiator SU and its cooperating SUs. For example, first feedback information comprising an indication that the first user queried sensing information may be obtained from the first user as the initiator SU. Second feedback information which comprises an indication that the first user provided sensing information and/or an indication as to whether the first user provided correct sensing information, may be obtained from a second user getting sensing information from the first user.

Since the at least one of the one or more second users provided spectrum sensing information to the first user, a social tie value of the respective second user may be updated correspondingly. In accordance with exemplary embodiments, third feedback information may be generated at the first user for updating the social tie value of the at least one of the one or more second users. For example, the third feedback information may comprise at least one of the following: an indication that the at least one of the one or more second users provided sensing information; and an indication as to whether the at least one of the one or more second users provided correct sensing information.

By considering social tie, the proposed STIS strategy can affect SUs' behaviors. When applying STIS strategy, a SU in a CSS system may be reluctant to report sensing information to those who have not helped other SUs. The evaluation of a SU's social tie may be related to its contribution to others. Moreover, the proposed STIS needs less computation without complex mathematically analysis.

Fig.3 exemplarily shows an execution procedure of STIS in accordance with an embodiment of the present invention. In an area of CSS, a SU may play two roles, the role of initiator SU enjoying sensing information and the role of cooperating SU providing sensing information to other SUs. Besides, one or more data managers may be used to maintain social tie values for these SUs. As shown in Fig.3, when an initiator SU tries to use one PU's spectrum band, the initiator SU may send a query message to ask its cooperating SUs to sense whether the PU's spectrum is free or in using. In response to receiving this query message, the cooperating SUs may obtain a social tie value of the initiator SU from a corresponding data manager, for example, by broadcasting a poll message to the initiator SU's data manager X.

Upon receiving a reply message from the data manager, the cooperating SUs may check whether the social tie value of the initiator SU outweighs the predefined threshold value δ, and determine whether to provide the initiator SU with sensing information or reject the initiator SU. Without loss of generality, assuming SU; is the initiator SU and the predefined threshold value δ is set as 0.5. If s > 0.5 , then SU; is regarded as a non- selfish SU and the cooperating SUs may respectively provide sensing information to SU;^', and vice verse. For the case of a newcomer SU; (for example, s' =0 and pl), the cooperating SUs may share their sensing information with SU;^', regardless of the actual social tie value of SU;^'. Afterwards, if SU; would like to get helps from others again, he/she may have to help others.

After the above described CSS exchange procedure, the initiator SU may generate feedback information for updating social tie values of the respective cooperating SUs which provided sensing information to the initiator SU. For example, the initiator SU may send a respective feedback message to a data manager Y of the corresponding cooperating SU which provided sensing information to the initiator SU. The corresponding cooperating SU's social tie value may be updated at the data manager Y with the received feedback information. Similarly, the respective social tie values of other cooperating SUs which provided sensing information to the initiator SU may also be updated with respective feedback information. According to exemplary embodiments, if SU; provides sensing information to other SUs, the value of r_t may be updated by adding 1, and if SU; requests sensing information from other SUs, the value of q_t may be updated by adding 1. Optionally, if the sensing information from SU; agrees with the PU's actual behavior, the value of r may be updated by adding 1 ; otherwise, the value of r may be unchanged. It will be realized that the data manager X of the initiator SU and the data manager Y of the cooperating SU illustrated in Fig.3 may be the same data manager (such as a central database) or different data managers (such as several distributed databases for respective SUs).

The various blocks shown in Figs.1-2 and the various message flows illustrated in Fig.3 may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function(s). The schematic flow chart diagrams described above are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of specific embodiments of the presented method. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated method. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown. The described approach in accordance with exemplary embodiments can improve the sensing performance of a CSS system effectively and efficiently by enhancing collaboration in a CRN with help of the proposed STIS strategy. For example, a SU in the CSS system applying the STIS strategy may easily find sources providing sensing information and also be willing to share its sensing result with other SUs in the CRN, since their social tie values may be a key factor inspiring the contribution of SUs. Specifically, if a selfish

SU reject to provide sensing information, its social tie value may decrease with the increase of its query amount, and if a selfish SU refuses to contribute its sensing results after its social tie value is greater than the predefined threshold value, the

STIS strategy can lower its social tie value. Further, by utilizing a penalizing parameter, the STIS strategy can suppress some SUs boosting their social tie values through providing false sensing information. Since the selfish behaviors can be suppressed effectively, a user in the CRN can make a more accurate decision of spectrum sensing by combining respective decisions from more other users. Fig.4 is a simplified block diagram of various apparatuses which are suitable for use in practicing exemplary embodiments of the present invention. In Fig.4, the apparatus 400 (such as radio device, mobile phone, wireless terminal, portable device, user equipment, PDA, multimedia tablet, and etc.) may be adapted for communicating with another apparatus (not shown) directly or through a network node such as base station, Node B, evolved Node B (eNB), control center, access point (AP) and/or the like. In an exemplary embodiment, the apparatus 400 may comprise at least one processor (such as a data processor (DP) 400A shown in Fig.4), and at least one memory (such as a memory (MEM) 400B shown in Fig.4) comprising computer program code (such as a program (PROG) 400C shown in Fig.4). The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus 400 to perform operations and/or functions described in combination with Figs.1-3. In an exemplary embodiment, the apparatus 400 may optionally comprise a suitable transceiver 400D for communicating with another apparatus, a network node, a server, a database and so on. For example, the transceiver 400D may be an integrated component for transmitting and/or receiving signals and messages. Alternatively, the transceiver 400D may comprise separate components to support transmitting and receiving signals/messages, respectively. The DP 400A may be used for processing these signals and messages. The PROG 400C is assumed to comprise program instructions that, when executed by the DP 400A, enable the apparatus to operate in accordance with the exemplary embodiments, as discussed above. That is, the exemplary embodiments of the present invention may be implemented at least in part by computer software executable by the DP 400A of the apparatus 400, or by hardware, or by a combination of software and hardware. The MEM 400B may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The DP 400 A may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multi-core processor architectures, as non-limiting examples.

Alternatively or additionally, the apparatus 400 may comprise various means, modules and/or components for implementing functions of the foregoing steps and methods in Figs.1-3. In an exemplary embodiment, the apparatus 400 of a cooperating SU may comprise: obtaining means for obtaining a social tie value of a first user (such as an initiator SU in Fig.3), in response to receiving from the first user a message querying sensing information, wherein the social tie value reflects a degree of sharing sensing information by the first user with one or more second users (such as cooperating SUs in Fig.3); and determining means for determining whether to provide the queried sensing information to the first user based at least in part on the social tie value. In another exemplary embodiment, the apparatus 400 of an initiator SU (also may be called as a first user) may comprise: sending means for sending from a first user to one or more second users (such as cooperating SUs in Fig.3) a message querying sensing information; and getting means for getting the queried sensing information from at least one of the one or more second users which determines to provide the queried sensing information to the first user based at least in part on a social tie value of the first user, wherein the social tie value reflects a degree of sharing sensing information by the first user with the one or more second users. Optionally, the apparatus 400 of the initiator SU may further comprise generating means for generating feedback information which may be used to update a social tie value of the at least one of the one or more second users. Alternatively or additionally, the apparatus 400 may comprise one or more integrated and/or separated modules/means/applications for implementing the specified functions as described with respect to Figs.1-3. Many of the functional units described herein have been labeled as modules or means, in order to more particularly emphasize their implementation independence. For example, a module/means may be implemented as a hardware circuit or in programmable hardware devices. Modules/means may also be implemented in software for execution by various types of processors. Nevertheless, the executables of the modules/means need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the modules/means and achieve the stated purpose for the modules/means. Furthermore, modules/means may also be implemented as a combination of software and one or more hardware devices. For instance, a module/means may be embodied in the combination of software executable codes stored on a memory device. In a further example, a module/means may be the combination of a processor that operates on a set of operational data. Still further, a module/means may be implemented in the combination of electronic signals communicated via transmission circuitry.

In general, the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the exemplary embodiments of this invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

It will be appreciated that at least some aspects of the exemplary embodiments of the inventions may be embodied in computer-executable instructions, such as in one or more program modules, executed by one or more computers or other devices. Generally, program modules comprise routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer executable instructions may be stored on a computer readable medium such as a hard disk, optical disk, removable storage media, solid state memory, random access memory (RAM), and so on. As will be realized by one of skilled in the art, the functionality of the program modules may be combined or distributed as desired in various embodiments. In addition, the functionality may be embodied in whole or in part in firmware or hardware equivalents such as integrated circuits, field programmable gate arrays (FPGA), and the like.

Although specific embodiments of the invention have been disclosed, those having ordinary skill in the art will understand that changes can be made to the specific embodiments without departing from the spirit and scope of the invention. The scope of the invention is not to be restricted therefore to the specific embodiments, and it is intended that the appended claims cover any and all such applications, modifications, and embodiments within the scope of the present invention.

Claims

CLAIMS What is claimed is:

1. A method, comprising:

obtaining a social tie value of a first user, in response to receiving from the first user a message querying sensing information, wherein the social tie value reflects a degree of sharing sensing information by the first user with one or more second users; and

determining whether to provide the queried sensing information to the first user based at least in part on the social tie value.

2. The method according to claim 1, wherein said determining whether to provide the queried sensing information to the first user based at least in part on the social tie value comprises:

providing the queried sensing information to the first user if the social tie value is larger than a predefined threshold value; and

rejecting to provide the queried sensing information to the first user if the social tie value is less than the predefined threshold value.

3. The method according to claim 2, wherein the social tie value is regarded as larger than the predefined threshold value, if the first user is a user which queries sensing information for the first time.

4. The method according to any one of claims 1 to 3, wherein the social tie value is related to at least one of the following parameters:

a number of responses by the first user to queries for sensing information;

a number of queries for sensing information by the first user; and a number of responses comprising correct sensing information by the first user to queries for sensing information.

5. The method according to any one of claims 1 to 4, wherein the social tie value maintained at a data manager is updated based at least in part on first feedback information from the first user, and wherein the first feedback information comprises an indication that the first user queried sensing information.

6. The method according to any one of claims 1 to 5, wherein the social tie value maintained at a data manager is updated based at least in part on second feedback information from a second user getting sensing information from the first user, and wherein the second feedback information comprises at least one of the following: an indication that the first user provided sensing information; and

an indication as to whether the first user provided correct sensing information.

7. The method according to claim 5 or 6, wherein the data manager is implemented in a centralized or distributed manner.

8. The method according to any one of claims 1 to 7, wherein the social tie value is a normalized value.

9. An apparatus, comprising:

at least one processor; and

at least one memory comprising computer program code,

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: obtain a social tie value of a first user, in response to receiving from the first user a message querying sensing information, wherein the social tie value reflects a degree of sharing sensing information by the first user with one or more second users; and determine whether to provide the queried sensing information to the first user based at least in part on the social tie value.

10. The apparatus according to claim 9, wherein the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to determine whether to provide the queried sensing information to the first user based at least in part on the social tie value comprises:

11. The apparatus according to claim 10, wherein the social tie value is regarded as larger than the predefined threshold value, if the first user is a user which queries sensing information for the first time.

12. The apparatus according to any one of claims 9 to 11, wherein the social tie value is related to at least one of the following parameters:

a number of responses by the first user to queries for sensing information;

a number of queries for sensing information by the first user; and

a number of responses comprising correct sensing information by the first user to queries for sensing information.

13. The apparatus according to any one of claims 9 to 12, wherein the social tie value maintained at a data manager is updated based at least in part on first feedback information from the first user, and wherein the first feedback information comprises an indication that the first user queried sensing information.

14. The apparatus according to any one of claims 9 to 13, wherein the social tie value maintained at a data manager is updated based at least in part on second feedback information from a second user getting sensing information from the first user, and wherein the second feedback information comprises at least one of the following:

an indication that the first user provided sensing information; and

15. The apparatus according to claim 13 or 14, wherein the data manager is implemented in a centralized or distributed manner.

16. The apparatus according to any one of claims 9 to 15, wherein the social tie value is a normalized value.

17. A computer program product comprising a computer readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising:

code for obtaining a social tie value of a first user, in response to receiving from the first user a message querying sensing information, wherein the social tie value reflects a degree of sharing sensing information by the first user with one or more second users; and

code for determining whether to provide the queried sensing information to the first user based at least in part on the social tie value.

The computer program product according to claim 17, wherein code for determining whether to provide the queried sensing information to the first user based at least in part on the social tie value comprises:

code for providing the queried sensing information to the first user if the social tie value is larger than a predefined threshold value; and

code for rejecting to provide the queried sensing information to the first user if the social tie value is less than the predefined threshold value.

19. The computer program product according to claim 18, wherein the social tie value is regarded as larger than the predefined threshold value, if the first user is a user which queries sensing information for the first time.

20. The computer program product according to any one of claims 17 to 19, wherein the social tie value is related to at least one of the following parameters:

a number of responses by the first user to queries for sensing information;

a number of queries for sensing information by the first user; and

21. The computer program product according to any one of claims 17 to 20, wherein the social tie value maintained at a data manager is updated based at least in part on first feedback information from the first user, and wherein the first feedback information comprises an indication that the first user queried sensing information.

22. The computer program product according to any one of claims 17 to 21, wherein the social tie value maintained at a data manager is updated based at least in part on second feedback information from a second user getting sensing information from the first user, and wherein the second feedback information comprises at least one of the following: an indication that the first user provided sensing information; and

23. The computer program product according to any one of claims 17 to 22, wherein the social tie value is a normalized value.

24. An apparatus, comprising:

obtaining means for obtaining a social tie value of a first user, in response to receiving from the first user a message querying sensing information, wherein the social tie value reflects a degree of sharing sensing information by the first user with one or more second users; and

determining means for determining whether to provide the queried sensing information to the first user based at least in part on the social tie value.

25. A method, comprising:

sending from a first user to one or more second users a message querying sensing information; and

getting the queried sensing information from at least one of the one or more second users which determines to provide the queried sensing information to the first user based at least in part on a social tie value of the first user, wherein the social tie value reflects a degree of sharing sensing information by the first user with the one or more second users.

26. The method according to claim 25, wherein the queried sensing information is provided by the at least one of the one or more second users to the first user if the social tie value is larger than a predefined threshold value.

The method according to claim 26, wherein the social tie value is regarded larger than the predefined threshold value, if the first user is a user which queries sensing information for the first time.

28. The method according to any one of claims 25 to 27, wherein the social tie value is related to at least one of the following parameters:

a number of responses by the first user to queries for sensing information;

a number of queries for sensing information by the first user; and

29. The method according to any one of claims 25 to 28, wherein the social tie value maintained at a data manager is updated based at least in part on first feedback information from the first user, and wherein the first feedback information comprises an indication that the first user queried sensing information.

30. The method according to any one of claims 25 to 29, wherein the social tie value maintained at a data manager is updated based at least in part on second feedback information from a second user getting sensing information from the first user, and wherein the second feedback information comprises at least one of the following: an indication that the first user provided sensing information; and

31. The method according to any one of claims 25 to 30, further comprising generating third feedback information for updating a social tie value of the at least one of the one or more second users, and wherein the third feedback information comprises at least one of the following:

an indication that the at least one of the one or more second users provided sensing information; and an indication as to whether the at least one of the one or more second users provided correct sensing information.

32. The method according to any one of claims 25 to 31, wherein the social tie value is a normalized value.

33. An apparatus, comprising:

at least one processor; and

at least one memory comprising computer program code,

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to:

send from a first user to one or more second users a message querying sensing information; and

get the queried sensing information from at least one of the one or more second users which determines to provide the queried sensing information to the first user based at least in part on a social tie value of the first user, wherein the social tie value reflects a degree of sharing sensing information by the first user with the one or more second users.

34. The apparatus according to claim 33, wherein the queried sensing information is provided by the at least one of the one or more second users to the first user if the social tie value is larger than a predefined threshold value.

35. The apparatus according to claim 34, wherein the social tie value is regarded as larger than the predefined threshold value, if the first user is a user which queries sensing information for the first time.

The apparatus according to any one of claims 33 to 35, wherein the social tie value is related to at least one of the following parameters:

a number of responses by the first user to queries for sensing information;

a number of queries for sensing information by the first user; and

37. The apparatus according to any one of claims 33 to 36, wherein the social tie value maintained at a data manager is updated based at least in part on first feedback information from the first user, and wherein the first feedback information comprises an indication that the first user queried sensing information.

38. The apparatus according to any one of claims 33 to 37, wherein the social tie value maintained at a data manager is updated based at least in part on second feedback information from a second user getting sensing information from the first user, and wherein the second feedback information comprises at least one of the following:

an indication that the first user provided sensing information; and

39. The apparatus according to any one of claims 33 to 38, wherein the at least one memory and the computer program code is configured to, with the at least one processor, cause the apparatus further to generate third feedback information for updating a social tie value of the at least one of the one or more second users, and wherein the third feedback information comprises at least one of the following:

an indication that the at least one of the one or more second users provided sensing information; and

an indication as to whether the at least one of the one or more second users provided correct sensing information.

40. The apparatus according to any one of claims 33 to 39, wherein the social tie value is a normalized value.

41. A computer program product comprising a computer readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising:

code for sending from a first user to one or more second users a message querying sensing information; and

code for getting the queried sensing information from at least one of the one or more second users which determines to provide the queried sensing information to the first user based at least in part on a social tie value of the first user, wherein the social tie value reflects a degree of sharing sensing information by the first user with the one or more second users.

42. The computer program product according to claim 41, wherein the queried sensing information is provided by the at least one of the one or more second users to the first user if the social tie value is larger than a predefined threshold value.

43. The computer program product according to claim 42, wherein the social tie value is regarded as larger than the predefined threshold value, if the first user is a user which queries sensing information for the first time.

44. The computer program product according to any one of claims 41 to 43, wherein the social tie value is related to at least one of the following parameters:

a number of responses by the first user to queries for sensing information;

45. The computer program product according to any one of claims 41 to 44, wherein the social tie value maintained at a data manager is updated based at least in part on first feedback information from the first user, and wherein the first feedback information comprises an indication that the first user queried sensing information.

46. The computer program product according to any one of claims 41 to 45, wherein the social tie value maintained at a data manager is updated based at least in part on second feedback information from a second user getting sensing information from the first user, and wherein the second feedback information comprises at least one of the following:

an indication that the first user provided sensing information; and

47. The computer program product according to any one of claims 41 to 46, wherein the computer program code further comprises code for generating third feedback information for updating a social tie value of the at least one of the one or more second users, and wherein the third feedback information comprises at least one of the following:

48. An apparatus, comprising: sending means for sending from a first user to one or more second users a message querying sensing information; and

getting means for getting the queried sensing information from at least one of the one or more second users which determines to provide the queried sensing information to the first user based at least in part on a social tie value of the first user, wherein the social tie value reflects a degree of sharing sensing information by the first user with the one or more second users.