WO2006016331A1

WO2006016331A1 - Method and apparatus for limiting p2p communication interference

Info

Publication number: WO2006016331A1
Application number: PCT/IB2005/052594
Authority: WO
Inventors: Li Sun; Dan Shang
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2004-08-10
Filing date: 2005-08-03
Publication date: 2006-02-16
Also published as: CN1735224A; JP2008510344A; EP1779601A1; TW200707972A

Abstract

A method for limiting P2P communication interference, steps to be executed by the communication network system comprising: setting P2P communication parameters according to the property of the communication network, the P2P communication parameters for limiting the interference caused by a UE while performing P2P communication with other UEs and sending the P2P communication parameters to the UE in the communication network; steps to be executed by the UE comprising: receiving the P2P communication parameters, and performing P2P probing procedure with another UE using the P2P communication parameters, to get a suitable transmission power; performing P2P communication with the another UE using the suitable transmission power according to the P2P communication parameters.

Description

METHOD AND APPARATUS FOR LIMITING P2P COMMUNICATION

INTERFERENCE

FIELD OF THE INVENTION The present invention relates generally to P2P communication, and more particularly, to a method and apparatus for limiting P2P communication interference.

BACKGROUND OF THE INVENTION

In conventional cellular mobile communication systems, only through the relaying of base stations can a UE (user equipment) communicate with another UE. Fig.1 illustrates this conventional communication mode used in a TD-SCDMA system, in which UEl and

UE2 exchange information through UTRAN consisting of at least a base station transceiver (Node B) and a RNC (radio network controller). This conventional communication mode is also called as UP-BS-DOWN mode. However, in some cases where two UEs camping in a cell are very close to each other, it can be a more reasonable way for them to communicate directly, and this is the so-called peer-to-peer communication, abbreviated as

P2P. P2P communication is typically applied in TDD radio systems where the same carrier frequency is adopted in both uplink and downlink. TD-SCDMA system will be taken as an example below to describe two P2P communication modes.

Fig.2 shows a P2P communication mode. As shown in Fig.2, P2P direct links can be established as represented by the solid line to transfer traffic data between UEl and UE2, whereas UTRAN monitors direct links through control links as represented by the dashed line between UTRAN and UEs. This P2P communication mode monitored by the base station is called as online P2P communication mode. Without the relaying of base stations, online P2P communication can save up to 50% radio resource, and UTRAN still keeps control of the P2P communication meanwhile. Descriptions as how to realize online P2P communication are disclosed in the patent applications filed by KONINKLIJKE PHILIPS ELECTRONICS N. V. on March 7, 2003, Application Serial No. 03119892.9 and 03119894.5, and incorporated herein as reference.

Based on the above online P2P communication mode, a new communication mode can be further built for the UEs to carry out P2P communication in a self-organizing way without support of base stations, and this is called as offline P2P communication mode. Fig.3 shows the offline P2P communication mode. As shown m the figure, before starting offline P2P communication, UEl and UE2 first register offline P2P communication service at UTRAN in conventional communication mode and obtain the P2P communication identity of their peer. The detailed procedure as how the UE obtains the P2P communication identity, is described in the patent application filed by KONINKLIJKE PHILIPS ELECTRONICS N.V. along with the present application, with Attorney's

Docket No. CN040033, and is incorporated herein as reference. Then, the two UEs establish P2P communication independently according to the P2P communication identity of their peer obtained during the registration procedure, without monitor and support of UTRAN. Finally, UEl and UE2 return to idle mode in conventional communication after the P2P communication is completed.

Compared with online P2P communication, signaling cost can be saved in offline P2P communication, and P2P communication link can be established even when the UEs are outside the coverage of wireless networks, such as ocean, mountain, battlefield and etc. Furthermore, this offline P2P communication mode can also be applied in the case where two UEs are very close to each other in a cell. At this time, no control link exists between

UTRAN and UEs, so users can use offline P2P communication service much cheaper than conventional communication as long as the transmission power of UEl and UE2 decreases so low as to be ignored by the network system.

As described above, since UEs communicate through the relaying of UTRAN in conventional communication mode, UTRAN can limit the transmission power of UEs directly within a rational scope through control signaling. But for P2P communication mode, the direct link in P2P communication shares the same carrier frequency with the uplink and downlink of conventional communication, and possibly shares the same timeslot through CDMA multiplexing, so it's very likely that P2P communication may interfere with the normal communication of other UEs.

When a UE is in online P2P communication mode, although UTRAN can control the transmission power of the UE via control link, the period of the signaling for power control is generally long so as to save signaling cost, and thus, UTRAN usually can't adjust the transmission power of the UE in time to decrease the interference caused by P2P communication.

<^■- - -When two UEs in a cell adopt offline P2P communication mode, since there is no control link between the two UEs in offline P2P communication mode and UTRAN, the UEs are completely out of the control of UTRAN. In this case, if no limit is put upon the transmission power of the UEs, the offline P2P communication mode will cause more serious interference to UEs in conventional communication mode in the cell.

In addition, when UEs establish offline P2P communication outside the coverage of the communication network, the interference caused by UEs in offline P2P communication mode to UEs in conventional communication mode is no longer a main problem, but too high transmission power will produce unnecessary power consumption and is very likely to interfere with other ongoing offline P2P communications within the coverage area as well if no proper limit is put upon the transmission power of the UEs.

It is, therefore, necessary to put forward a new method for limiting P2P communication interference.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method for limiting P2P communication interference, with which the interference caused by P2P communication can be limited within a rational scope, to guarantee that other communicating UEs won't be affected.

A method is provided for limiting P2P communication interference to be executed in a communication network system in accordance with the present invention, comprising: setting P2P communication parameters according to the property of the communication network, the P2P communication parameters for limiting the interference caused by a UE in P2P communication to other UEs; transmitting the P2P communication parameters to the UE in the communication network so that the UE can carry out P2P communication with another UE using the P2P communication parameter.

A method is provided for limiting P2P communication interference to be executed in a UE in accordance with the present invention, comprising: receiving the P2P communication parameters sent by a communication network system, the P2P communication parameters for limiting the interference caused by the UE in P2P communication to other UEs; performing P2P probing procedure with another UE using the P2P communication parameters, to get a suitable transmission power; carrying out P2P communication with said another UE using said suitable transmission power according to the P2P communication parameters.

A communication network system in accordance with the present invention is provided, comprising: a setting unit, for setting P2P communication parameters according to the property of the communication network, the P2P communication parameters for limiting the interference caused by a UE in P2P communication to other UEs; a transmitting unit, for transmitting the P2P communication parameters to the UE in the communication network so that the UE can carry out P2P communication with another UE using the P2P communication parameters.

A UE in accordance with the present invention is provided, comprising: a receiving unit, for receiving the P2P communication parameters sent by a communication network system, the P2P communication parameters for limiting the interference caused by the UE in P2P communication to other UEs; a probing unit, for performing P2P probing procedure with another UE using the P2P communication parameters, to get a suitable transmission power; an adjusting unit, for adjusting the transmission power of the UE during P2P probing and P2P communication; a determining unit, for determining whether the transmission power adjusted through negotiation is eligible for the restriction terms of the P2P communication parameters; a P2P communicating unit, for carrying out P2P communication with said another UE using said transmission power eligible for the restriction terms of the P2P communication parameters.

Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed descriptions will be given below to the present invention in conjunction with specific embodiments and accompanying drawings, in which:

Fig.l is a diagram illustrating a TD-SCDMA system adopting conventional communication mode;

Fig.2 is a diagram illustrating a TD-SCDMA system adopting online P2P communication mode;

Fig.3 is a diagram illustrating a TD-SCDMA system adopting offline P2P communication mode; Fig.4 is the flowchart diagram illustrating the steps to be executed by a UTRAN to limit P2P communication interference in accordance with an embodiment of the present invention; Fig.5 is the flowchart diagram illustrating the steps to be executed by a UE performing offline P2P communication to limit P2P communication interference;

Fig.6 is a block diagram illustrating the configurations of the UE and network system for limiting P2P communication interference in accordance with an embodiment of the present invention.

Throughout the drawing figures, like reference numerals will be understood to refer to like parts and components.

DETAILED DESCRIPTION OF THE INVENTION According to the method for limiting P2P communication interference as provided in the present invention, the communication network system can set a group of P2P communication parameters based on the property and current operation status of the communication network, and broadcast the P2P communication parameters via BCCH (Broadcast Control Channel) to each UE in the cell. Upon receipt of the P2P communication parameters, a UE can select the corresponding P2P communication parameters such as P2P probing power and P2P communication power according to its location, to control the transmission power during P2P link probing procedure and that during P2P communication procedure, thus to decrease the interference caused by P2P communication effectively. TD-SCDMA system will be taken as an example below to describe the method for limiting P2P communication interference as provided in the present invention, in conjunction with accompanying drawings.

Fig.4 shows the steps to be executed by UTRAN to limit P2P communication interference in accordance with an embodiment of the present invention. As shown in Fig.4, first, UTRAN sets a group of P2P communication parameters

(step SI lO). Setting of the P2P communication parameters mainly involves the contents of the P2P communication parameters and the value of each P2P communication parameter. 1. About the contents of the P2P communication parameters The contents of the P2P communication parameters can be set according to the UE 's location within the communication network and the P2P communication mode possibly adopted. For example, when the UE is in a cell covered by the communication network, both offline and online communication modes can be employed. Since no control link exists between a UE in offline communication mode and UTRAN and thus UTRAN can't control the UE' s transmission power through control signaling, it's preferred to set the UE's transmission power to two P2P communication parameters of the maximum online P2P communication power and the maximum offline P2P communication power. If offline P2P communication mode is employed, the UE should select stricter P2P communication parameters accordingly, to avoid that the P2P signals transmitted by the UE produce interference to other communicating UEs in the cell. Generally speaking, the value of the allowable maximum offline P2P communication power is below that of the maximum online P2P communication power.

As another example, when the UE is outside the coverage of the communication network, since the interference caused by the offline P2P communication between the UE and another UE to other communicating UEs within the cell is no longer a main problem at this time, the value of the maximum offline P2P communication power used by the UE can be higher than that used by the UE in the cell. Accordingly, the above maximum offline P2P communication power can further be classified into the maximum offline P2P communication power within the coverage of the communication network and that outside the coverage of the communication network, so that the UE can select from relatively broader P2P communication parameters so as to expand the radio range for P2P communication when it's outside the coverage of the communication network.

As to the transmission power to be used for P2P link probing, it can be set according to the UE's location in the communication network and the P2P communication mode possibly employed, with reference to the above way. Furthermore, the P2P communication parameters can further include indication information representing whether the UE is allowed to use P2P communication service and the common radio resource for use in offline P2P communication, such as offline P2P communication frequency and the default offline P2P communication identity. 2. About the value of P2P communication parameters The value of P2P communication parameters can be set according to the property and current operation status of the communication network (step Sl 10).

Wherein, the property of the communication network relates but not limited to the network property indicated by the communication network composed of cells within a coverage area (or namely, the area of the cells) and that indicated by the traffic load carried by the communication network. The operator of the communication network can make and adjust the resource management strategy according to the property of the communication network. For example, the property of the communication network varies depending on the cells with different coverage range (or with different radius), which is fully demonstrated by the fact that the UEs in P2P communication mode produce different P2P communication interference to other communicating UEs in the communication network, and thus, for cells with different coverage areas, the P2P communication parameters can be set to the corresponding values.

As another example, for a cell built in the heart of a commercial region, the property of the communication network varies a lot compared with one built in a sparsely populated suburb. For a cell in the heart of the commercial region, generally there is more call traffic, so the network operator can disable P2P communication within the cell in the resource management strategy and set the value of P2P communication parameters accordingly so that users in conventional communication can avoid being interfered from P2P communication, or set relatively stricter P2P communication parameters in the resource management strategy so that only a few users can use P2P communication and set the values of the corresponding P2P communication parameters such as P2P transmission power to be lower, to mitigate the P2P communication interference to users in conventional communication as much as possible. For cells built in sparsely-populated suburb, the setting of the corresponding P2P communication parameters can be broader or several groups of P2P communication parameters can be set according to factors like the communication range, communication environment and etc, to expand the radio range for P2P communication.

Furthermore, UTRAN can set the values of P2P communication parameters according to the current operation status of the communication network detected, for example, whether the communication network is currently busy or idle and the periods for different traffic, to expand the radio range for P2P communication, and decrease the impact of P2P communication upon other communicating UEs.

After setting the P2P communication parameters according to the property and operation status of the communication network, UTRAN broadcasts the P2P communication parameters to each UE in the cell periodically via BCCH (step S120). To adapt to the change of the resource management strategy and operation status of the communication network so as to modify the corresponding P2P communication parameters in time, UTRAN detects periodically or in real time whether the resource management strategy and operation status of the communication network changed after sending the P2P communication parameters (step S 130). According to the detection result,

UTRAN determines whether to reset the P2P communication parameters (step S 140). When detecting that the resource management strategy and the operation status changed, the corresponding P2P communication parameters will be reset (step S 150).

Fig.5 illustrates the steps of an embodiment of the present invention, in which a UE adopting offline P2P communication mode within the coverage of the communication network selects P2P communication parameters according to its location, establishes and maintains offline P2P communication based on the selected P2P communication parameters after reading via BCCH the above P2P communication parameters sent from UTRAN. Suppose that the UE has registered offline P2P communication service at UTRAN and acquired the P2P communication identity of its peer. Detailed descriptions to the method of registering offline P2P communication service and acquiring P2P communication identity, are disclosed in the patent applications filed by KONINKLIJKE PHILIPS ELECTRONICS N. V along with this application, Attorney's Docket No. CN040033 and CN040032, which are incorporated herein as reference.

As shown in Fig.5, first of all, the UE reads the P2P system parameters via BCCH (step S210). According to its current location (in or outside the communication network) and the P2P communication mode to be employed (online or offline P2P communication), the UE selects the corresponding P2P communication parameters from the received P2P communication parameters (step S220).

It's assumed that the UE is in the cell and attempts to adopt offline P2P communication mode and obtains the P2P communication parameters at least including the maximum offline P2P probing power and the maximum offline P2P communication power within the network coverage, then the UE sets the maximum offline P2P probing power as the initial transmission power for offline P2P communication link probing (step S230), and starts link probing for offline P2P communication (step S240).

During link probing procedure, the UE negotiates with its peer to adjust the transmission power (step S50), and determines whether the transmission power adjusted through negotiation is above the maximum offline P2P probing power, to get a suitable transmission power for use in P2P communication (step S260).

If the transmission power adjusted through negotiation is higher than the maximum offline P2P probing power, it indicates that the link probing for offline P2P communication fails, then the UE can re-select the corresponding P2P communication parameters to switch to link probing for online P2P communication or conventional communication mode (step

S280).

If the transmission power adjusted through negotiation is not higher than the maximum offline P2P probing power, it indicates that the link probing for offline P2P communication succeeds, then the UE starts offline P2P communication using the transmission power adjusted through negotiation (step S270).

During offline P2P communication, the UE constantly adjusts its transmission power according to the change of the distance to its communication peer and the change of the communication environment (step S290). Every time the transmission power is adjusted, the UE determines whether the adjusted transmission power is higher than the maximum offline P2P communication power (step S300).

If the adjusted transmission power is higher than the maximum offline P2P communication power, the offline P2P communication will be terminated and the UE will switch to link probing for online P2P communication or conventional communication mode (step S310).

If the adjusted transmission power is not higher than the maximum offline P2P communication power, the UE maintains offline P2P communication using the adjusted transmission power (step S320).

In the procedure of establishing and maintaining offline P2P communication, the UE reads periodically the P2P communication parameters sent via BCCH (step S330), and judges whether the received P2P communication parameters are same as the currently employed P2P communication parameters (step S340).

If the received P2P communication parameters changed, the received P2P communication parameters will be used to update the previous P2P communication parameters (step S35O). In the ongoing offline P2P communication, the UE adjusts transmission power using the updated P2P communication parameters (step S360).

When the offline P2P communication comes to an end (step S370), the UE returns to idle mode in conventional communication (step S380). Descriptions are given above to the procedure in which a UE in the network coverage establishes and maintains offline P2P communication according to the P2P communication parameters. If the above UE in the cell selects to adopt online P2P communication mode and the P2P communication parameters acquired by the UE include the maximum online P2P probing power and the maximum online P2P communication power, the UE can enter online P2P communication through a link probing procedure for online P2P communication according to the P2P communication parameters, which is similar to the above steps. Different from offline P2P communication mode, there is control link between the UE and UTRAN, so the UE in online P2P communication mode can adjust the values of its P2P communication parameters through negotiating with UTRAN. For example, if the communication network is idle currently, the UE may possibly obtain a transmission power higher than the above maximum online P2P communication power through negotiation and perform P2P communication with the transmission power so that the radio range for P2P communication can be further expanded without effecting communications of other users.

If the UE attempts to perform offline P2P communication outside the coverage of the communication network after registering offline P2P communication service, it can enter offline P2P communication through link probing procedure for offline P2P communication according to the P2P communication parameters obtained from the communication network system via BCCH when the UE is in the network coverage or the P2P communication parameters recorded beforehand in the SIM card for example (it's assumed that the P2P communication parameters include one or more groups of the maximum offline P2P probing power and the maximum offline P2P communication power outside the network coverage).

As to the above method for limiting P2P communication interference as provided in the present invention, it can be implemented in software or hardware, or in combination of both.

Fig.6 illustrates the configurations of the network system and UE for limiting P2P communication interference according to an embodiment of the present invention, wherein the components same as those in conventional network system and UE are not given herein. As Fig.6 shows, first, setting unit 110 in the network system UTRAN 100 sets the P2P communication parameters according to the property of the communication network, such as the resource management strategy of the communication network and the communication network coverage. The setting unit 110 can also set the P2P communication parameters according to the current operation status of the communication network detected by the detecting unit 150. Then, sending unit 130 sends the P2P communication parameters to UEl in the communication network so that UEl can perform P2P communication with another UE according to the P2P communication parameters.

Wherein, the P2P communication parameters also involve contents and values, which is similar to that described in the above method for limiting P2P communication interference. The contents of the P2P communication parameters relate to the UE 's location in the communication network and the P2P communication mode possibly adopted, and the values of the P2P communication parameters relate to the property and current operation status of the communication network. In addition, the P2P communication parameters at least include the maximum offline P2P probing power and the maximum offline P2P communication power in the communication network coverage.

After receiving unit 10 receives the P2P communication parameters sent by UTRAN, selecting unit 20 in UEl selects the corresponding P2P communication parameters from the received P2P communication parameters according to the UE' s location and the P2P communication mode to be adopted. Afterwards, probing unit 42 in P2P link probing/communicating unit 40 sets the maximum offline P2P probing power included in the P2P communication parameters as the initial transmission power, to perform offline P2P probing. In the offline P2P probing procedure, adjusting unit 34 in determining/adjusting unit 30 negotiates with its communication peer to adjust the transmission power. Determining unit 32 determines whether the transmission power adjusted through negotiation is higher than the maximum offline P2P probing power. If the transmission power adjusted through negotiation is not higher than the maximum offline P2P probing power, P2P communicating unit 44 in P2P link probing/communicating unit 40 performs P2P communication with the communication peer, using the transmission power adjusted through negotiation. During offline P2P communication procedure, UEl constantly adjusts its transmission power via adjusting unit 34 according to the change of the distance to its communication peer and the change of the communication environment, and determines whether the transmission power adjusted through negotiation is higher than said maximum offline P2P communication power. If the transmission power adjusted through negotiation is not higher than the maximum offline P2P communication power, P2P communicating unit 44 continues to perform offline P2P communication using the adjusted transmission power. While in online P2P communication mode, a UE can perform link probing procedure to determine the transmission power for online P2P communication and control the transmission power for online P2P communication during P2P communication, according to the P2P communication parameters in online P2P communication mode, by adopting the method and apparatus similar to those in the above offline P2P communication mode. BENEFICIAL USE OF THE INVENTION

With reference to the detailed descriptions to the embodiment of the present invention in conjunction with accompanying drawings, it can be seen that in the method and apparatus for limiting P2P communication interference as provided in the present invention, UTRAN sets and updates the P2P communication parameters according to the property and current operation status of the communication network so that a UE in the communication network can adjust the value of its transmission power for example according to the P2P communication parameters while in P2P communication mode, especially in offline P2P communication mode, to limit the radio range for P2P communication, thus to effectively decrease the interference of the P2P communication to other communicating UEs in the communication network.

Further, for the offline P2P communication outside the communication network established by the UE, using the P2P communication parameters to limit the offline P2P communication can save the UE from unnecessary power consumption, and decrease the P2P communication interference caused to other users in offline P2P communication. Although TD-SCDMA system is taken as an example to describe the method and apparatus for limiting P2P communication interference as provided in the present invention, it is obvious to those skilled in the art that the method and apparatus can also be applied in other P2P-enabled wireless communication systems.

It is to be understood by those skilled in the art that the proposed method and apparatus for limiting P2P communication interference as disclosed, in this invention can be made of various modifications without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

CLAIMS:

1. A method for limiting P2P communication interference to be executed in a communication network system, comprising: (a) setting P2P communication parameters according to property of the communication network, the P2P communication parameters for limiting the interference caused by a UE while performing P2P communication with other UEs;

(b) sending the P2P communication parameters to the UE in the communication network so that the UE can conduct P2P communication with another UE according to the P2P communication parameters. . .. . _.

2. The method for limiting P2P communication interference according to claim 1, wherein the property of the communication network at least includes one of a resource management strategies of the communication network and the coverage of the communication network.

3. The method for limiting P2P communication interference according to claim 1 or 2, wherein step (a) further comprises: detecting operation status of the communication network; setting the P2P communication parameters according to the operation status of the communication network.

4. The method for limiting P2P communication interference according to claim 3, wherein the P2P communication parameters at least include the maximum offline P2P probing power and the maximum offline P2P communication power in the coverage of the communication network.

5. The method for limiting P2P communication interference according to claim 4, wherein the P2P communication parameters are sent to the UE via BCCH (Broadcast Control Channel) at the step (b).

6. The method for limiting P2P communication interference according to claim 2, further comprising: detecting whether the resource management strategy of the communication network changed; resetting the corresponding P2P communication parameters if change occurred.

7. The method for limiting P2P communication interference according to claim 3, further comprising: detecting whether the operation status of the communication network changed; resetting the corresponding P2P communication parameters if change occurred.

8. A method for limiting P2P communication interference to be executed in a UE, comprising:

(a) receiving P2P communication parameters sent from a communication network system, the P2P communication parameters for limiting the interference caused by the UE while performing P2P communication with other UEs; (b) performing P2P probing procedure with another UE using the P2P communication parameters, to determine a suitable transmission power;

(c) performing P2P communication with the another UE using the suitable transmission power according to the P2P communication parameters.

9. The method for limiting P2P communication interference according to claim 8, wherein step (b) comprises: selecting corresponding P2P communication parameters from the received P2P communication parameters according to location of the UE and a P2P communication mode to be adopted; performing P2P probing procedure with another UE using the selected P2P communication parameters.

10. The method for limiting P2P communication interference according to claim 9, wherein the P2P communication parameters at least include the maximum offline P2P probing power and the maximum offline P2P communication power in the coverage of the communication network.

11. The method for limiting P2P communication interference according to claim 10, wherein the step (b) comprises: performing offline P2P probing procedure using the maximum offline P2P probing power; negotiating with the another UE to adjust transmission power in the offline P2P probing procedure; determining whether the transmission power adjusted through negotiation is higher than the maximum offline P2P probing power; performing offline P2P communication with the another UE using the transmission power adjusted through negotiation if the transmission power adjusted through negotiation is not higher than the maximum offline P2P probing power.

12. The method for limiting P2P communication interference according to claim 11, further comprising: switching to online P2P communication probing procedure or conventional communication mode if the transmission power adjusted through negotiation is higher than the maximum offline P2P probing power.

13. The method for limiting P2P communication interference according to claim 11, further comprising: adjusting transmission power for transmitting P2P signals during offline P2P communication procedure; determining whether the adjusted transmission power is higher than the maximum offline P2P communication power; performing offline P2P communication with another UE using the adjusted transmission power if the adjusted transmission power is not higher than the maximum offline P2P communication power.

14. The method for limiting P2P communication interference according to claim 13, further comprising: switching to one of online P2P communication probing procedure and conventional communication mode if the adjusted transmission power is higher than the maximum offline P2P communication power.

15. The method for limiting P2P communication interference according to claim 8, further comprising: determining whether the received P2P communication parameters are same as the currently used P2P communication parameters; updating the corresponding P2P communication parameters if the received P2P communication parameters changed.

16. A communication network system, comprising: a setting unit, for setting P2P communication parameters according to property of the communication network, the P2P communication parameters for limiting the interference caused by a UE while performing P2P communication with other UEs; a sending unit, for sending the P2P communication parameters to the UE in the communication network so that the UE can conduct P2P communication with another UE according to the P2P communication parameters.

17. The communication network system according to claim 16, wherein the property of the communication network at least includes one of resource management strategy of the communication network and the coverage of the communication network.

18. The communication network system according to claim 16 or 17, further comprising: a detecting unit, for detecting operation status of the communication network; wherein the setting unit sets the P2P communication parameters according to the operation status of the communication network.

19. A UE, comprising: a receiving unit, for receiving P2P communication parameters sent from a communication network system, the P2P communication parameters for limiting the interference caused by the UE while performing P2P communication with other UEs; a probing unit, for performing P2P probing procedure with another UE using the P2P communication parameters, to determine a suitable transmission power; a determining unit, for determining whether the suitable transmission power is eligible for terms of the P2P communication parameters; a P2P communicating unit, for performing P2P communication with another UE using the suitable transmission power eligible for restriction terms of the P2P communication parameters. ■

20. The UE according to claim 19, further comprising: an adjusting unit, for adjusting the transmission power of the UE in P2P probing and P2P communication.

21. The UE according to claim 20, further comprising: a selecting unit, for selecting corresponding P2P communication parameters from the received P2P communication parameters according to location of the UE and P2P communication mode to be adopted;

22. The UE according to claim 21, wherein the selected P2P communication parameters at least include the maximum offline P2P probing power and the maximum offline P2P communication power in the coverage of the communication network.

23. The UE according to claim 22, wherein: the probing unit sets the maximum offline P2P probing power as initial transmission power to perform offline P2P probing; the adjusting unit negotiates with another UE to adjust the transmission power during offline P2P communication procedure; the determining unit determines whether the transmission power adjusted through negotiation is higher than the maximum offline P2P probing power; the P2P communicating unit performs offline P2P communication with another UE using the transmission power adjusted through negotiation if the adjusting unit determines that the probing succeeds.

24. The UE according to claim 23, wherein: the adjusting unit adjusts the transmission power for transmitting P2P signals during offline P2P communication procedure; the determining unit determines whether the adjusted transmission power is higher than the maximum offline P2P communication power; the P2P communicating unit performs offline P2P communication with another UE using the adjusted transmission power if the determining unit determines that the adjusted transmission power is not higher than the maximum offline P2P communication power.