WO2012019349A1

WO2012019349A1 - Apparatus and method for reducing interference in a network

Info

Publication number: WO2012019349A1
Application number: PCT/CN2010/075925
Authority: WO
Inventors: Tao Peng; Qianxi Lu; Haiming Wang; Tao Chen
Original assignee: Nokia Corporation
Priority date: 2010-08-12
Filing date: 2010-08-12
Publication date: 2012-02-16

Abstract

The present invention proposes a scheme for reducing interference in a network, especially for a hybrid network. A method, comprising: grouping at least one apparatus of a first kind into one or more groups, wherein apparatuses of a same group have similar interference characteristic if resource allocated to respective apparatus of this group is used by an apparatus of a second kind; utilizing a resource allocation identifier to indicate resource usable by said group; transmitting assistant information of at least one group to an apparatus of a second kind, said assistant information indicating a mapping of a group and its corresponding resource allocation identifier; and wherein said assistant information can facilitate the apparatus receiving said assistant information to determine whether resource indicated by the received at least one resource allocation identifier is usable by the receiving apparatus for data transmission.

Description

APPARATUS AND METHOD FOR REDUCING INTERFERENCE IN A

NETWORK

Field of the Invention

The present invention relates to the field of communication, and more particularly to an apparatus and a method for reducing interference in a network, especially in a hybrid network.

Background of the Invention

It should be noted that this section introduces contents that may help facilitate a better understanding of the invention, but the statements thereof should not be considered as admissions about what is prior art or what is not prior art.

There are mainly two kinds of separate network scenario, one is cellular network and the other is ad-hoc network. In a cellular network, such as universal mobile telecommunications system (UMTS), code division multiple access (CDMA), Worldwide Interoperability for Microwave Access (Wimax), 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) or the like, data traffic usually goes through centralized controller, such as a base station (BS), Node B (NB), evolved NodeB (eNB) or the like, even if the communicating parties are close to each other. Operating in this centralized mode is also called as cellular mode in this disclosure. One main benefit of such centralized operation is easy resource control and interference control. However, a potential drawback is less efficient resource utilization. A double amount of resources may be needed for a transmission of a user equipment (UE) pair in a cellular mode. For example, a cellular UE may need to have a first radio resource allocated between this cellular UE and its serving base station and a second radio resource allocated between the base station and its partner cellular UE which this cellular UE is intending to communicate with. In comparison, a UE in an ad-hoc network can interoperate with another UE in a direct, device-to-device (D2D) mode instead, and thus may only need one radio resource between the UE and its partner UE.

Therefore, in order to improve system throughput, a hybrid scenario has been proposed. In such hybrid scenario, direct D2D network is integrated into a cellular network, e.g. LTE/LTE-A cellular network specified in 3GPP, or vice versa. In such hybrid mode, UEs can choose either cellular mode or direct D2D mode for transmissions of traffic. For example, a UE may operate in cellular mode if the other party is located far way and may operate in the D2D mode if its partner UE is sufficiently close by. The hybrid mode operation is being explored in newer generations of network technologies such as 3GPP Long-Term Evolution-Advance (LTE-A), WiMax network, etc. One example of D2D mode network is aforementioned ad-hoc network where one D2D UE may set up a direct connection with its partner UE, such as via a handshake and competition procedure. Other examples of such D2D mode network can be e.g., Wireless Local Area Network (WLAN), Bluetooth, ZigBee systems or the like. In hybrid mode, UEs are not only allowed to operate in D2D mode in addition to the traditional cellular mode but also may share the same resources as the cellular UEs. Specifically speaking, a control entity such as a 3G base station or similar device, e.g., NB and eNB may allocate the resource to cellular UEs in a dynamic way. A UE capable of working in D2D mode can reuse the allocated resource (which has been allocated to a cellular UE) no matter whether it is being used by a cellular UE or is in idle state.

However, a problem is that UEs in D2D mode will suffer interferences from cellular UE. An example has been shown in Fig.1 . Fig.1 illustrates an example wireless system 100. The wireless system 100 may include a base station (BS) and two UEs (UE1 and UE2) operating in cellular mode. Hereinafter, we call a UE working in cellular mode as a cellular UE. Here, cellular UE1 and UE2 are coupled to BS via a wireless link 101 and 102. UE3 and UE4 shown in Fig. 1 may operate in a D2D transmission mode. As aforementioned, UE3 and UE4 may share uplink resource with the UE1 and UE2 to communicate with each other in D2D mode, in other words, UEs 1 -4 may use the same uplink resource simultaneously or sequentially. In Fig.1 , due to proximity, cellular UE1 may generate more interference to the D2D transmission of UE3-UE4 than UE2. Therefore, if the pair UE3 and UE4 choose and reuse the resource allocated to UE2, a stronger interference from UE1 may be avoided. Thus it can be seen that an intelligent resource reuse selecting scheme can avoid interferences from cellular UEs for a D2D transmission.

However, upon a study by the inventors, some of the existing solutions operates in a non-efficient way, or neglect security and signaling overhead factors, or have poor compatibility with the current cellular UEs. Therefore, an improved scheme is required for reducing the interference in such hybrid network environment.

Summary

The invention proposes a method and corresponding apparatus and computer program products to solve or at least alleviate at least one of the existing problems.

According to one aspect of the invention, a method, comprising:

grouping at least one apparatus of a first kind into one or more groups, wherein apparatuses of a same group have similar interference characteristic if resource allocated to respective apparatus of this group is used by an apparatus of a second kind;

utilizing a resource allocation identifier to indicate resource usable by said group;

transmitting assistant information of at least one group to an apparatus of a second kind, said assistant information indicating a mapping of a group and its corresponding resource allocation identifier; and

wherein said assistant information can facilitate the apparatus receiving said assistant information to determine whether resource indicated by the received at least one resource allocation identifier is usable by the receiving apparatus for data transmission.

Wherein, interferences belong to a certain range may be considered as having a similar interference characteristic. According to yet another aspect of the invention, an apparatus, comprising

at least one processor; and

at least one memory including computer program code;

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

group at least one apparatus of a first kind into one or more groups, wherein apparatuses of a same group have similar interference characteristic if resource allocated to respective apparatus of this group is used by an apparatus of a second kind;

utilize a resource allocation identifier to indicate resource usable by said group;

transmit assistant information of at least one group to an apparatus of a second kind, said assistant information indicating a mapping of a group and its corresponding resource allocation identifier; and

According to yet another aspect of the invention, a method, comprising: receiving at an apparatus of a second kind assistant information, the assistant information indicating a mapping of a group and its corresponding resource allocation identifier;

determining interferences from at least one group when the resource indicated by the resource allocation identifier of this group is used by the apparatus of a second kind;

determining whether resource indicated by at least one of the received resource allocation identifiers is usable by the apparatus of the second kind for data transmission based on the determined interferences;

wherein the group comprising at least one apparatus of a first kind, the apparatuses of a same group have similar interference characteristic if resource allocated to respective apparatus of this group is used by the apparatus of the second kind. According to yet another aspect of the invention, an apparatus, comprising

at least one processor; and

at least one memory including 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 perform at least following:

receive at an apparatus of a second kind assistant information, the assistant information indicating a mapping of a group and its corresponding resource allocation identifier;

determine interferences from at least one group when the resource indicated by the resource allocation identifier of this group is used by the apparatus of a second kind;

determine whether resource indicated by at least one of the received resource allocation identifiers is usable by the apparatus of the second kind for data transmission based on the determined interferences;

wherein the group comprising at least one apparatus of a first kind, the apparatuses of a same group have similar interference characteristic if resource allocated to respective apparatus of this group is used by the apparatus of the second kind.

According to yet another aspect of the invention, an apparatus, comprising respective means for implementing steps of any one of the preceding method claims.

According to yet another aspect of the invention, a computer program product comprising computer-executable components with instructions for implementing method or apparatus according to any of the preceding solutions.

The program maybe embedded in a computer readable medium.

Upon the group-based solution of the invention, interference can be minimized or even avoided, or at least can be reduced to a certain degree.

It should be noted that all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [device, means etc]" are to be interpreted openly as referring to at least one instance of said device, means, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Brief Description of the Drawings

These and other features of the present invention will become apparent from the following description of the exemplary embodiments of the present invention with reference to the drawings, wherein:

Fig.1 shows an example network environment in which D2D transmission suffers interferences from cellular UEs;

Fig.2 is a flowchart illustrating a method performed at a BS according to one exemplary embodiment of the present invention;

Fig.3 is a flowchart illustrating a method performed at a D2D UE according to one exemplary embodiment of the present invention;

Fig.4 is a flowchart illustrating another method performed at a BS according to one exemplary embodiment of the present invention;

Figs. 5 a-c illustrating simplified function block diagram of an apparatus according to exemplary embodiments of the present invention;

Fig. 6 illustrating simplified function block diagram of an apparatus according to another exemplary embodiments of the present invention;

Fig. 7 illustrating an example of cellular area division according to one exemplary embodiment of the present invention;

Fig. 8 showing an example of cellular UE distribution within a serving cell according to one exemplary embodiment of the present invention;

Fig. 9 illustrating the signaling flow of cellular UE grouping according to one exemplary embodiment of the present invention;

Fig. 10 illustrating an indoor scenario with cellular UEs and D2D UEs according to one exemplary embodiment of the present invention.

Detailed Description of the Invention

In this disclosure, a scheme for reducing interferences has been proposed. As we mentioned in the background, a UE can choose either cellular mode or D2D mode for data transmission. Hereinafter, we call a UE intending to transmit data in D2D mode as a D2D UE. In the invention, cellular UEs are categorize into one or more groups, and a D2D UE can estimate possible interference caused by such group if this D2D UE selects the resource allocated to this group for data transmission. Then if the estimated interference is acceptable, the resource usable for this group can be used by this D2D UE when operating in D2D mode. Now we will illustrate exemplary embodiments of this invention with the figures.

Fig.2 is a flowchart illustrating a method performed at a BS according to one exemplary embodiment of the present invention. At step 201 , a BS groups respective cellular UE into a group. Here, cellular UEs in a same group have similar interference characteristic if resource allocated to respective cellular UE of this group is reused. At step 202, BS utilizes a resource allocation identifier to indicate resource usable each of said group. At step 203, BS transmits assistant information of at least one group to a D2D UE, said assistant information indicating a mapping of a group and its corresponding resource allocation identifier. Here, the assistant information can facilitate a D2D UE receiving the assistant information to determine whether the resource indicated by the received at least one resource allocation identifier is appropriate for traffic transmission of a D2D UE.

As for the grouping performed at step 201 , it mainly considers the interference characteristic. Preferably, in a mixed D2D and cellular modes network environment, such interference characteristic can be roughly estimated according to the location/position of a cellular UE, or it can be determined based on an interference measurement on the cellular UE, or combination of the two. Preferably, the rough position information of respective group and/or the interference measurement can be comprised into the assistant information and be further provided to a receiving D2D UE. It should be noted that so-called interference characteristic refers to the amount or degree of interference brought to a D2D UE if the resource allocated to this cellular UE is reused by the D2D UE. In other words, a data transmission by a cellular UE may be a normal traffic transmission from the cellular UE point of view, while for a D2D UE who is using or is intending to use the same resource with this cellular UE, such normal data transmission may bring interference. After the above grouping operation, each cellular UE will belong to a unique group, i.e., a n-to-1 mapping between cellular UEs and the corresponding one or more groups, wherein n ^ 1 . An example grouping is illustrated in the following table 1 .

Group ID Cellular UE ID

Group_1 CeUE1

Group_2 CeUE2

Group_3 None

Group_4 CeUE3,4

Table 1 An exemplary grouping of cellular UEs

At step 202, a person skilled in the art knows that for a cellular network, the resources allocated to each cellular UE can be obtained in advance in any appropriate form such as (ResourceJD, CellularUEJD) in which ResourceJD denotes the specific resources allocated to the cellular UE in any known manners, such as obtain it by decoding the received Physical Downlink Control Channel (PDCCH) message using Cell Radio Network Temporary Identifier (C-RNTI) in 3GPP LTE system. Then a resource allocation identifier can be used to indicate resource usable by all the cellular UEs of this group, thus the assistant information can be acquired. As aforementioned, such assistant information may indicate a mapping of a group and its corresponding resource allocation identifier. For example, such mapping may be in the form of (ResourceJD, GroupJD) or any other appropriate or possible forms. An example of such mapping is illustrated in the following table 2. In Table 2, an example format of the mapping is shown, where all the PRBs (Physical Resource Blocks) allocated to cellular UEs of the same group is indicated. Group ID Resource ID

Group_1 PRB1 -PRB3

Group_2 PRB4-PRB5

Group_3 PRB6

Table 2 An exemplary mapping of a group and its corresponding resources

Preferably, the BS may broadcast the assistant information at step 203. After that, the assistance information can be used by a receiving D2D UE to determine whether to use the resource of this group for data transmission.

Preferably, it may be beneficial if we consider in-band emission of cellular transmission. Specifically, because of the in-band emission, some resource may be not reusable (i.e., used by a D2D device for D2D transmission) due to the harmful interference on adjacent frequency. Thus, it may more beneficial for local D2D reusing, if the cellular UEs which are closed to each other geographically are assigned with resources in a centralized manner than distributed manner. By the distributed resource scheduling manner, more resources would become unavailable for a D2D UE locating in a relatively short distance.

Upon the group-based assistant information, a D2D UE can determine the possible interferences caused by respective group to determine appropriate resources for D2D mode communication. Such process is shown in Fig. 3. Now we will refer to Fig. 3 for the following discussion. At step 301 , a D2D UE acquires the assistant information from a control entity of a network, such as BS, NB or the like. Then at step 302, a D2D UE can determine interferences from at least one group when the resource indicated by the resource allocation identifier of this group is reusing by this D2D UE. At step 303, a D2D UE determines whether the resource indicated by the received at least one resource allocation identifier is usable for data transmission the based on the determined interferences.

During step 302, a D2D UE can use any feasible means to perform the determination. For example, a D2D UE can measure received interference on the corresponding resources usable by each UE group. The cellular UE interferences may be measured in the form of one or more of the following parameters: a received signal power, a noise to signal ratio, a path loss measure, and the like. In fact, the measurement of interference can be performed by any known or new measurements proposed in the future in the field. In this regard, for example, after measuring the interference on resources usable by one or more groups, assuming that the group-based assistant information shown in table 2 is used, the receiving D2D UE measures the interference from Group_1 on PRB1 , 2, 3. Then different calculation method can be applied here, e.g.,

Interference from Group_1 = 1/3 ^* (Interference received on PRB1 + Interference received on PRB2 + Interference received on PRB3); or

Interference from Group_1 = min (Interference received on PRB1 + Interference received on PRB2 + Interference received on PRB3)

Here, it should be noted that the calculation method and the principle reflected thereof is not limited to the above two illustrated forms. A person skilled in the art can easily understand that any other feasible calculation methods can be utilized here to estimate the interferences. For example, a maximum value can also be used as a cautious approach. Alternatively, a D2D UE can also request a BS sending the assistant information for such interference information. In this regard, the serving BS can give a relatively rough estimation of the interference of respective group. For example, interferences can be denoted as several different levels indicating the interference degree. Then a BS can provide a D2D UE with its determined interference level of a respective group to this D2D UE. Any way, a person skilled in the art can understands that any feasible methods can be utilized so long as desired interference information can be obtained.

In addition, as for the interferences, many possible factors can be considered, such as distance, long-term pathloss, buildings which cause penetration loss and shadow fading, or the like. For example, different pathloss modeling influenced by specific scenarios such as urban, suburban, outdoor or indoor. Therefore, in some scenarios, interference predicted by location information maybe not enough, and measurement operation maybe necessary. Any way, a person skilled in the art will understand that any factors can be considered when grouping cellular UEs in order to meet specific requirements. At step 303, according to the determined interferences, a D2D UE may determine whether the cellular resources allocated to some groups (such as groups 1 -3 shown in table 2) can be used for D2D communication, in other words, appropriate resources for data transmission can be found. A D2D UE can use a threshold value to facilitate to make such determination, i.e., if the determined interference from Group x is less than a threshold value, then it means Group_x is usable. Here said threshold value can be pre-defined and configurable to denote the cellular interference that can be accepted by D2D UEs. Here, the D2D UE can make such determination for an instantaneous D2D data transmission. Thus if a D2D UE just intends to find an appropriate resource for the current D2D communication, it may stop such analysis once it determines that the interference of one group is acceptable and its resource can be used by this D2D UE for urgent transmission. In other words, it is not necessary for a D2D UE to determines interferences and further determine whether the resource thereof is usable for all the groups, thus steps 302 and 303 may be performed on part of the groups.

Alternatively, such determination made in step 303 can be kept and used for subsequent or later D2D data transmission. Basically, a D2D UE can autonomously choose to perform steps 302 and 303 on how many groups. In addition, if the results are planned to be used later, the results can be kept as a table as shown in the following:

Table 3 Result of on the resource using decision

Based on the kept table 3, a D2D UE can autonomously choose to use the usable resources allocated to cellular UEs of a group.

The above illustrates methods performed at the BS side and the D2D UE side. In the following, another embodiment of the invention is described in which most of the operations of this disclosure is performed at the BS side.

Referring to Fig. 4 in which another method performed at a BS according to one exemplary embodiment of the present invention is shown. In Fig. 4, steps 401 and 402 perform the same operation with steps 201 and 202 of Fig. 2, thus repeated explanations are omitted here for simplicity. With respect to step 405, it is similar with step 203 shown in Fig. 2, the difference is that the content of the assistant information is different. With respect to Fig. 4, at step 403, a BS receives a message from a D2D UE. The message is a query about which resource indicated by the at least one resource allocation identifier is usable for this D2D UE. At step 404, a BS determines interferences from at least one group when the resource indicated by the resource allocation identifier of this group is used by this D2D UE.

As for step 404, a BS can just determine the interferences in a similar way as we discussed in conjunction with step 302 shown in Fig. 3. Then the assistant information transmitted in step 405 may further comprise the interference determined in step 404. Alternatively, a BS can determine whether the resource indicated by a resource allocation identifier of a group is usable by this D2D UE for a D2D data transmission (as discussed in conjunction with step 303 shown in Fig. 3). In this case, the assistant information transmitted in step 405 may further comprise the results of such determination. Alternatively, a BS may even select usable resources for this D2D UE directly. In this case, the assistant information just needs to comprise resource allocation identifiers indicating some or all the usable resources.

In fact, it can be seen that the operations in Fig. 4 are similar with the corresponding ones shown in Fig. 2 or 3, the difference is that some operations are placed on a BS instead of D2D UEs. In some network environments where D2D UEs are the traditionally UEs and operators are not intending to place much new changes to D2D UEs, alternatives shown in Fig. 4 maybe beneficial.

It should be noted that for a better and easy understanding, several tables are illustrated. However, the implementation of the invention is not limited to specific tables. On contrary, it should be understand that necessary information can be maintained in any appropriate form.

Although several exemplary methods have been illustrated, a person skilled in the art can easily understand that the sequence thereof are not unchangeable. Other alternative embodiments of those methods designed in different sequences of steps can also be used without departing from the scope of this disclosure. In addition, the steps showed thereof can be further combined or split.

Although the above embodiments are discussed in a hybrid network environment mixing cellular mode and D2D mode, a person skilled in the art can conceive that the spirit of this invention can also be used to an environment in which two kinds of apparatus can sharing resources and interference existing in such resource sharing. In addition, the transmission modes of such two kinds apparatus can be the same or different. Therefore, the invention should not be considered as limited to the environment illustrated in those mentioned embodiments. Instead, the invention should be broadly understood and applied without departing from the spirit thereof.

Figs. 5 a-c illustrate simplified function block diagram of an apparatus according to exemplary embodiments of the present invention. Apparatus shown in Figs. 5 a-c can perform the methods of Figs. 2-4 respectively. Specifically speaking, apparatuses illustrated in Figs. 5 a and c can be embodied in a BS while apparatus illustrated in Fig. 5 b can be embodied in a D2D UE. Obviously, respective block shown in Figs. 5 a-c is used for performing respective steps in corresponding methods have already been explained in detail. Therefore, further and repeated explanations are omitted here.

Fig. 6 illustrate simplified function block diagram of an apparatus according to another exemplary embodiments of the present invention. Similarly, apparatus shown in Fig. 6 can perform the methods of Figs. 2-4 respectively. The difference thereof from Figs. 5a-c is that the apparatus in Fig. 6 is designed as comprising an interface unit and interference reducing unit. The interface unit in Fig. 6 is used for communicating with other apparatuses. The interference reducing unit is used for performing methods shown in Figs. 2 and 4 when such apparatus is embodied in a BS, and performing method shown in Fig. 3 when such apparatus is embodied in a D2D UE. For an existing BS or D2D UE, it may such interference reducing unit as one of its components to help reduce the interferences caused when cellular resources are shared between a cellular UE and D2D UE.

Although Figs. 5 and 6 illustrate examples of an apparatus according to embodiments of the invention, various changes may be made to the apparatuses without departing from the spirit of the invention. For example, some functions of a specific means or unit may be performed by other means or unit or vice versa. In addition, additional hardware or software modules may be added to perform portion of functions of any of the means or unit of the apparatuses thereof. Furthermore, a person skilled in the art can readily understand that the operations of the invention can be implemented as software, hardware, firmware, or the combination thereof. Therefore, any apparatus with at least the ability of implementing the invention can be deployed on the existing nodes or entities in networks, in order for implementing the invention. In addition, it should be noted that the proposed apparatus can be a separate entity, or embodied into other existing device, apparatus, or functional blocks. Of course, the above functions of respective apparatus will not exclude other functions being embodied in the apparatus. Thus the apparatus may have other capabilities or functions.

In the following, some more specific examples are provided for a better understanding of the grouping operation. Now, we illustrate an example in which position is considered as the interference characteristic of a cellular UE. In this exemplary embodiment, the serving area of each BS is divided into several regions first, and then cellular UEs will be categorized into different regions (also called groups) based on their position information. Basically, for a cellular system, the serving area of each BS is determined in the stage of network planning. As electronic maps and satellite maps are generally available, the geographical information needed for cellular area division can be easily acquired. Thus the area of each cell can be further divided into multiple regions. An example of such area division is shown in Fig. 7.

Fig. 7 illustrates an example of cellular area division. In this example, the division comprising two region types: indoor and outdoor. Compared with outdoor area, normally the indoor area (area covered by buildings) is relatively divided in a rough way. This is because for GPS-based position technologies, the indoor positioning error is usually larger than outdoor scenario where better GPS reception could be expected. Such division tasks could be completed in advance, and it would not be changed except geographical changes, e.g., buildings are destroyed or constructed. In this case, as geographical changes generally happen with a very low frequency, thus only a minor modification task is required. Preferably, the divided region scale can take into account of the positioning error. After such cellular area division in which the covered area of a serving cell has been divided into different regions, the cellular UEs can be categorized into different groups based on the division with the help of positioning information. Now we will discuss the cellular UE grouping.

Fig. 8 shows an example of cellular UE distribution within a serving cell. First, the serving BS acquires the location information of active cellular UEs. Second, BS categorizes them into different groups according to the cellular area division results, i.e., which cellular region they belong to. Fig. 9 illustrates the signaling flow of cellular UE grouping. Specifically, BS collects the location information from for example a Location Services (LCS) architecture in the core network (wherein E-SMLC refers to Enhanced Serving Mobile Location Center), and make the grouping operation according to the area division result in the step above. Then the results of grouping can be maintained for example in the form as shown in table 1 .

The trigger of such grouping operation maybe in time-trigger or event-trigger manner. Preferably, such grouping operation is for active cellular UEs. For cellular UEs with low mobility, the update cellular UE group ID could be done with a rather low frequency. For cellular UEs which are moving with a high speed (usually outdoor and can be easily judged from frequent position change), the positioning information message may cause large signaling overhead and the occupied resource is rather difficult for a D2D UE reusing. Thus, such moving cellular UEs can be categorized into a special group, such as Mobility_Group. In this case, resources of such special group would never be shared by D2D UEs, or only be shared by indoor D2D UEs which may far away from those moving cellular UEs.

In general, existing assisted-GPS (usually additional information capable of assisting the mobile GPS measurements such as visible GPS satellites, reference time and Doppler or the like is available) measurements can achieve an accuracy of 10 meters outdoors and a few tens of meters indoors. Compared with the cellular network size, this positioning information is accurate enough to support the location-based grouping operation, even for the indoor scenario as a rough estimation, or for the environment where the buildings are not so high (the height difference between indoor cellular UEs generally can be ignored).

It should be note that the above embodiment is just an exemplary case, and in other scenarios, a BS may categorize cellular UEs according to their position information directly without the above cellular area division. Simply speaking, any possible position-based grouping methods can be used in this invention.

If the accuracy of position information maintained by BS is not enough or even unavailable, an approach in which information on interference characteristic from a D2D UE is used may acts as a complementary scheme. Fig. 10 illustrates an indoor scenario with cellular UEs and D2D UEs. In Fig. 10, D2DJJE1 ,2 and CeUE1 , 2,3,4 are located in a building with multiple floors. As the positioning technology of BS is not accurate enough to know the accurate location information and interference characteristic thereof, we designs D2D UE to report interference characteristic instead or as a complementary of the non-accurate position information obtained by a BS. D2D UEs are required by cellular BS to provide information on interference characteristic of cellular UEs and report the results to cellular BS.

Firstly, BS denotes the CeUE1 ,2,3,4 in this building as Group_A. Secondly, BS requires D2D_UE1 ,2 to measure the interference on resources allocated to Group_A. In this step, the cellular BS only notify the D2D UE1 ,2 to measure the specific resource set, i.e., the resources allocated to CeUE1 ,2,3,4. As aforementioned, D2D_UE1 ,2 could know the resources allocated to Group_A in advance, and start such measurement during uplink transmission by the cellular UEs of Group_A. Thirdly, the D2D_UE1 ,2 report the measurement result to BS, such as on a determined channel.

The following table 4 gives an example format of the report sent by D2DJJE1 , wherein the four PRBs are allocated to CeUE1 ,2,3,4. In table 4, the value of l_1 ,2,3,4 could be binary (interfering or not, i.e., Y or N) or quantified value with more value (High, Middle and Low and etc.).

Resource ID Interference Level

PRB_1 U =Y

PRB_2 l_2=N

PRB_3 l_3=N

PRB_4 l_4=N

Table 4 An example format of D2D interference measurement report In one example, in the requst from cellular BS, only the allocated resources is provided to D2D UEs for measurement and no C-RNTI information of cellular UEs is required in this scheme.

In a preferred embodiment, in order to reduce the signaling overhead,

D2D UEs can only report the interfering resources, e.g., the row of PRB_2,3,4 in Table 4 can be removed. Besides, to reduce the channel uncertainty caused by fast-fading, D2D UEs could measure and report for multiple times, or implement an averaging interference characteristic to reduce the report overhead. However, during such multiple times operation, this requires the mapping of allocated PRB and the cellular UE keep fixed, or changed following a pre-defined rule known by D2D UEs.

Upon the received information from D2D UE, cellular BS may analyze the received information and group the cellular UEs. Under the example report content above in table 4, after receiving the report from D2D_UE1 ,2, the cellular BS can obtain the following interference relationship according to the allocated resource information (CeUE1 is on PRB1 , CeUE2 is on PRB2,...).

Table 5 Interference relationship between cellular and D2D UEs Similarly, interference level is denoted by positive value, e.g., 1 for Y and

0 for N in this example, and the interference relationship of each cellular UE with all D2D UEs is denoted by a vector, e.g., (1 ,0) for CeUE1 and (0,0) for

CeUE2. Then the work is to find a grouping scheme, for which the vectors difference within each group is small enough. A lot of existing researches have been done in this field. Here we given a simple example of a grouping algorithm:

Define cellular UE set as CU={1 ,2,..K}, and the interference vector for each cellular UE as V(k). The distance between different vectors can be any form of vector norm, i.e., ||V(j)-V(k)||, and mean vector of Group_i={1 ,2,...,Ki}, i.e., A_i, is defined as (V(1 )+V(2)+...+V(Ki))/Ki. The decentralization degree of Group_i={1 ,2,...,Ki}, i.e., D_i, is defined as ||(V(1 )-A_i||+ ||V(2)-A_i||+...+ ||

V(Kj)-A i I |)/Ki. If the maximum number of groups is restricted to be G, and the a pre-defined threshold to quantify the decentralization of vectors as J, then

Step 1 : Initialize g=2

Step 2: While kg

Step 2a: Pick up one pair of cellular UEs which has the least distance between them, add them into Group_i and then reduce them from CU. If the left UEs are less than g-i, only a single UE is added into Group_i. Step 2b: i=i+1 , and return to Step 2;

Step 3: For each cellular UE k remains in CU, add it into the Group_i which causes least ||V(k)-A_i||, and update A_i and CU after that. Repeat this step till CU is empty;

Step 4: If the sum of D_i for all i is less than J, stop the algorithm.

Else, if g<G, g=g+1 and return to Step 2. Else, stop the algorithm.

Then cellular UEs are refined. For example, comparing to the original grouping scheme in table 1 , the refined result is shown as follows.

Group ID Cellular UE ID

Group_A1 CeUE1

Group_A2 CeUE2,3

Group_A3 CeUE3,4

Table 6 Results of a refined grouping

It should be note that the above two examplary grouping method could be implemented individually or jointly, preferably taking into account of position information error and backward compatibility such as with R'8 LTE UEs. In addition, a person skilled in the art understands that any factors can be taken into account when perform the grouping operation. Moreover, in addition to position methods in LTE (such as control plane LCS architecture for Evolved Packet System (EPS)), any possible locating technique (maybe existing ones or known in the future) can be utilized in the above position-based grouping.

Basically speaking, such grouping operation proposed in the invention may simplify an indexing for cellular UEs. As grouping cellular UEs according to their position information gives a rough estimation to the interference characteristic, position-based grouping method may reduce complexity with slight performance loss and therefore get a higher efficiency. As for interference-based grouping method, it may achieve a better performance but the method itself is a high complexity. In addition to those mentioned grouping criterions, any other feasible/applicable grouping methods can be applied to certain application environments without departing from the spirit of the invention, such as random grouping operation. For D2D UEs, upon the solutions in the invention, selecting the appropriate resources for D2D data transmission can reduce or minimize or even avoid the interference from cellular UEs.

In should be noted that 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 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. Also, those means and/or steps may be implemented as a separate one or can be combined with any others or it can be split into several means, modules, steps according to their functionality.

The present invention can be realized in hardware, software, firmware or a combination thereof. It is applicable for the present invention to be implemented as a computer program product, which comprises all the features enabling the implementation of the methods and devices or modules described herein, and when being loaded into a computer system or a processing device, is able to carry out these methods or constitute the functional means/modules in the apparatuses or devices according to embodiments of the present invention. In addition, said program products can be embodied in computer readable medium. For example, a program of the computer program product can be loaded into/embodied in a memory of the processing device.

Although the above description has discussed specific embodiments of the invention, those skilled in the art can 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, combinations and embodiments within the scope of the present invention.

Claims

1 . A method, comprising:

2. The method according to claim 1 , wherein the apparatus of the first kind and the second kind locate in a hybrid network; preferably, the hybrid network comprises cellular network and at least one of the following networks: ad-hoc, Wireless Local Area Network (WLAN), Bluetooth, ZigBee, wherein the apparatus of the first kind transmits traffic in cellular mode and the apparatus of the second kind transmits traffic in device-to-device mode; and/or, the cellular UEs which are closed to each other geographically are assigned with resources in a centralized manner.

3. The method according to any one of claims 1 to 2, wherein the interference characteristic is roughly estimated according to the location of the apparatus of the first kind and/or determined according to an interference measurement on the apparatus of the first kind; and/or, the interference can be measured according to one or more of the following parameters: a received signal power, a noise to signal ratio, a path loss measure.

4. The method according to claim 3, wherein the assistant information further comprising location information and/or information on the interference measurement of at least one group.

5. The method according to any one of claims 1 to 4, wherein during the grouping, requesting at least one apparatus of the second kind for position information of an apparatus of the first kind and/or interference measurement on the resource allocated to the apparatus of the first kind.

6. The method according to any one of claims 1 to 5, wherein before said transmitting, the method further comprising:

upon receiving a message from an apparatus of the second kind querying which resource allocated to the apparatus of the first kind is usable, determining interferences from at least one group when the resource indicated by the resource allocation identifier of this group is used by the apparatus sending the message; and

in the transmitting step, transmitting the assistant information to the apparatus sending the message, wherein the assistant information further comprising the determined corresponding interference of at least one group.

7. The method according to any one of claims 1 to 5, wherein before said transmitting, the method further comprising:

deciding whether resource usable by this group can be used by the apparatus sending the message based on the determined interferences; and in the transmitting step, transmitting the assistant information to the apparatus sending the message, wherein assistant information further comprising information indicating whether the resource indicated by a resource allocation identifier of a group is usable for the apparatus sending the message.

8. The method according to any one of claims 1 to 5, wherein before said transmitting, the method further comprising:

selecting at least one group whose usable resource can be used by the apparatus sending the message based on the determined interferences; and in the transmitting step, transmitting the assistant information to the apparatus sending the message, wherein assistant information comprising a mapping of the selected group and its corresponding resource allocation identifier.

9. The method according to any one of claims 1 -8, wherein the method is carried out in Worldwide Interoperability for Microwave Access (Wimax) network, Long-Term Evolution (LTE) network, Long-Term Evolution-Advance (LTE-A) network, 3G network, Beyond 3G(B3G) network.

10. An apparatus, comprising

at least one processor; and

at least one memory including computer program code;

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

11 . The apparatus according to claim 10, wherein the apparatus of the first kind and the second kind locate in a hybrid network; preferably, the hybrid network comprises cellular network and at least one of the following networks: ad-hoc, Wireless Local Area Network (WLAN), Bluetooth, ZigBee, wherein the apparatus of the first kind transmits traffic in cellular mode and the apparatus of the second kind transmits traffic in device-to-device mode; and/or, the cellular UEs which are closed to each other geographically are assigned with resources in a centralized manner.

12. The apparatus according to any one of claims 10 tol l , wherein the interference characteristic is roughly estimated according to the location of the apparatus of the first kind and/or determined according to an interference measurement on the apparatus of the first kind; and/or, the interference can be measured according to one or more of the following parameters: a received signal power, a noise to signal ratio, a path loss measure.

13. The apparatus according to claim 12, wherein the assistant information further comprising location information and/or information on the interference measurement of at least one group.

14. The apparatus according to any one of claims 10 to13, wherein during the group operation, request at least one apparatus of the second kind for position information of an apparatus of the first kind and/or interference measurement on the resource allocated to the apparatus of the first kind.

15. The apparatus according to any one of claims 10 to14, wherein before said transmitting, further performs:

upon receiving a message from an apparatus of the second kind querying which resource allocated to the apparatus of the first kind is usable, determine interferences from at least one group when the resource indicated by the resource allocation identifier of this group is used by the apparatus sending the message; and

in the transmit operation, transmit the assistant information to the apparatus sending the message, wherein the assistant information further comprising the determined corresponding interference of at least one group.

1 6. The apparatus according to any one of claims 10 to14, wherein before said transmit operation, further performs:

decide whether resource usable by this group can be used by the apparatus sending the message based on the determined interferences; and in the transmit operation step, transmit the assistant information to the apparatus sending the message, wherein assistant information further comprising information indicating whether the resource indicated by a resource allocation identifier of a group is usable for the apparatus sending the message.

17. The apparatus according to any one of claims 10 to14, wherein before said transmit operation, further performs:

select at least one group whose usable resource can be used by the apparatus sending the message based on the determined interferences; and in the transmit operation step, transmit the assistant information to the apparatus sending the message, wherein assistant information comprising a mapping of the selected group and its corresponding resource allocation identifier.

18. The apparatus according to any one of claims 10 to17, wherein the method is carried out in Worldwide Interoperability for Microwave Access (Wimax) network, Long-Term Evolution (LTE) network, Long-Term Evolution- Advance (LTE-A) network, 3G network, Beyond 3G (B3G) network.

19. A method, comprising:

receiving at an apparatus of a second kind assistant information, the assistant information indicating a mapping of a group and its corresponding resource allocation identifier;

determining whether resource indicated by at least one of the received resource allocation identifier is usable by the apparatus of the second kind for data transmission based on the determined interferences;

20. The method according to claim 19, wherein the apparatus of the first kind and the second kind locate in a hybrid network; preferably, the hybrid network comprises cellular network and at least one of the following networks: ad-hoc, Wireless Local Area Network (WLAN), Bluetooth, ZigBee, wherein the apparatus of the first kind transmits traffic in cellular mode and the apparatus of the second kind transmits traffic in device-to-device mode; and/or, the cellular UEs which are closed to each other geographically are assigned with resources in a centralized manner.

21 . The method according to any one of claims 19 to 20, wherein the assistant information further comprising: location information and/or information on the interference measurement of at least one group.

22. The method according to any one of claims 19-21 , wherein in the determining step, the apparatus of the second kind can request said interferences from an apparatus providing said assistant information, or can measure received interference on a corresponding resources usable by a group.

23. The method according to any one of claims 19-22, wherein the method is carried out in Wireless Local Area Network (Wimax) network, Long-Term Evolution (LTE) network, Long-Term Evolution-Advance (LTE-A) network, 3G network, Beyond 3G (B3G) network.

24. An apparatus, comprising

at least one processor; and

at least one memory including computer program code;

determine whether resource indicated by at least one of the received resource allocation identifier is usable by the apparatus of the second kind for data transmission based on the determined interferences;

25. The apparatus according to claim 24, wherein the apparatus of the first kind and the second kind locate in a hybrid network; preferably, the hybrid network comprises cellular network and at least one of the following networks: ad-hoc, Wireless Local Area Network (WLAN), Bluetooth, ZigBee, wherein the apparatus of the first kind transmits traffic in cellular mode and the apparatus of the second kind transmits traffic in device-to-device mode; and/or, the cellular UEs which are closed to each other geographically are assigned with resources in a centralized manner.

26. The apparatus according to any one of claims 24 to 25, wherein the assistant information further comprising: location information and/or information on the interference measurement of at least one group.

27. The apparatus according to any one of claims 24 to 26, wherein in the first determine operation, the apparatus of the second kind can request said interferences from an apparatus providing said assistant information, or can measure received interference on a corresponding resources usable by a group.

28. The apparatus according to any one of claims 24 to 27, wherein the apparatus locates in Worldwide Interoperability for Microwave Access (Wimax) network, Long-Term Evolution (LTE) network, Long-Term Evolution-Advance (LTE-A) network, 3G network, Beyond 3G (B3G) network.

29. An apparatus, comprising respective means for implementing steps of any one of the preceding method claims.

30. A computer program product comprising computer-executable components with instructions for implementing method or apparatus according to any of claims 1 -29.

31 . A computer program product according to claim 30, wherein the program is embedded in a computer readable medium.