WO2013108114A1

WO2013108114A1 - Transmission power control mechanism for discovery signal transmission

Info

Publication number: WO2013108114A1
Application number: PCT/IB2013/000056
Authority: WO
Inventors: Samuli Heikki TURTINEN; Sami-Jukka Hakola; Anna Pantelidou; Juha Pekka KARJALAINEN; Timo Koskela; Matti Pikkarainen; Ville VARTIANINEN
Original assignee: Renesas Mobile Corporation
Priority date: 2012-01-18
Filing date: 2013-01-17
Publication date: 2013-07-25
Also published as: GB201200837D0; GB2498713A

Abstract

There is provided a mechanism usable for conducting a power control for a transmission of a discovery signal in a communication network, in particular for a D2D discovery signal. A network control element such as an eNB configures transmission power parameters usable for determining a transmission power to be set by a communication device such as a UE for transmitting a discovery signal for a specific communication mode such as a D2D communication mode. The configured transmission power parameters are sent by means of an information element such as a dedicated system information block. In the UE, the transmission power parameters are used to set the transmission power for transmitting the discovery signal in the specific communication mode. The discovery signal comprises a power information element indicating whether or not and possibly how the transmission power used for transmitting the discovery signal differs to a common transmission power reference value. A UE receiving the discovery signal for e.g. D2D communication mode comprising the power information element calculates a link quality and path loss on the basis of the actual transmission power of the received discovery signal and the information derived from the power information element.

Description

TRANSMISSION POWER CONTROL MECHANISM FOR DISCOVERY SIGNAL

TRANSMISSION

DESCRIPTION

BACKGROUND OF THE INVENTION

Field of the invention

The present invention relates to a mechanism usable for conducting a transmission power control for a transmission of a discovery signal for a specific communication mode. In particular, the present invention is related to apparatuses, methods and computer program products providing a mechanism by means of which the transmission power for a discovery signal for a specific communication mode, e.g. a D2D communication, can be controlled in a communication device such as a UE communicating also in a cellular communication mode.

Related background Art

Prior art which is related to this technical field can e.g. be found in technical specifications according to 3GPP TS 36.213 (e.g. version 10.3.0), TS 36.300 (e.g. version 10.5.0), and specifications related to signaling architecture.

The following meanings for the abbreviations used in this specification apply:

BS: base station

CA: carrier aggregation

D2D: device-to-device

DL: downlink

eNB: enhanced node B

ID: identification

LTE: Long Term Evolution LTE-A: LTE Advanced

M2M : machine-to-machine

MAC: medium access control

MME: mobility management entity

MTC: machine type communication

PHR: power headroom

PUCCH : physical uplink control channel

PUSCH : physical uplink shared channel

SRB: signalling radio bearer

TX: transmission

UCI: uplink control information

UE: user equipment

UL: uplink

SIBx: system information block x

SRB signaling radio bearer

VoIP voice over Internet protocol

In the last years, an increasing extension of communication networks, e.g. of wire based communication networks, such as the Integrated Services Digital Network (ISDN), DSL, or wireless communication networks, such as the cdma2000 (code division multiple access) system, cellular 3rd generation (3G) communication networks like the Universal Mobile Telecommunications System (UMTS), enhanced communication networks based e.g. on LTE, cellular 2nd generation (2G) communication networks like the Global System for Mobile communications (GSM), the General Packet Radio System (GPRS), the Enhanced Data Rates for Global Evolutions (EDGE), or other wireless communication system, such as the Wireless Local Area Network (WLAN), Bluetooth or Worldwide Interoperability for Microwave Access (WiMAX), took place all over the world. Various organizations, such as the 3rd Generation Partnership Project (3GPP), Telecoms & Internet converged Services & Protocols for Advanced Networks (TISPAN), the International Telecommunication Union (ITU), 3rd Generation Partnership Project 2 (3GPP2), Internet Engineering Task Force (IETF), the IEEE (Institute of Electrical and Electronics Engineers), the WiMAX Forum and the like are working on standards for telecommunication network and access environments. Recently, so-called "proximity-based" applications and services came into the focus of further developments in the field of telecommunications. The term proximity-based applications and services may be used, for example, in cases where two or more communication network devices (i.e. for example two or more users), which are close to each other, are interested in exchanging data, if possible, directly with each other.

For future cellular communication networks, a possible method for such proximity-based applications and services is the so-called device-to-device (D2D) communication functionality, which is also referred to as M2M communication, direct communication, peer-to-peer communication, adhoc communication etc..

D2D may offer a high communication speed, large capacity and a high quality of service which are important features to be achieved. Advantages achievable by the implementation of D2D communications in the cellular communication environment are, for example, an offloading of the cellular system, reduced battery consumption due to lower transmission power, an increased data rate, an improvement in local area coverage robustness to infrastructure failures and also an enablement of new services. This is possible while also providing access to licensed spectrum with a controlled interference environment to avoid the uncertainties of license exempt band. Due to this, D2D communication gains more and more attraction and interest.

However, in order to make a D2D discovery and communication applicable to communication networks, such as those based on 3GPP LTE or LTE-A systems, it is necessary to evolve a suitable platform in order to intercept the demand of proximity-based applications so that it is possible that devices, such as UEs or the like, can conduct discovery functions and hence establish a D2D communication with each other directly over the air, and potentially communicate directly. Hence, one important task is to provide mechanisms allowing configuration and control of e.g. radio level discovery functionality. This task is to be combined with the requirement to provide a certain level of control for the network operator side. For example, the discovery process needs also to be coupled with a system architecture and a security architecture that allow the 3GPP operators to retain control of the device behavior, for example to control who can emit discovery signals, when and where, what information these signals should carry, and what actions the corresponding devices should take once they discover each other.

Use cases and service requirements for D2D communication may comprise, for example, social applications (e.g. exchange of files, photos, text messages, etc., VoIP conversation, one-way streaming video, two-way video conference, etc.). local advertising, multiplayer gaming (where high resolution media (voice & video) can be exchanged interactively either with all participants or team members within a game environment, wherien control inputs are expected to be received by all game participants with an ability to maintain causality), network offloading (when an opportunistic proximity offload potential exists, one UE or communication device may initiate a transfer of the media flow from the macro network to a proximity communication session with another communication device so as to conserve macro network resources while maintaining the quality of user experience for the media session), smart meters (e.g. communication among low capability MTC devices, vehicular communication (safety and non-safety), general M2M communication among different communication devices/machines), public safety (both network controlled D2D and ad hoc D2D with partial or without network coverage).

Basically, two different forms for realizing a D2D communication connection are considered, wherein also forms between these two extremas are thinkable. One form is network controlled and the other form is a so-called ad hoc D2D. The former is likely to take place on licensed spectrum under tight operator and network control while the latter needs to be able to work autonomously without network coverage.

Furthermore, an important aspect for implementing D2D communication ability is that simultaneous cellular and D2D operations are possible wherein physical layer constraints are to be taken into account. However, in case of simultaneous cellular and D2D operations conducted by a communication device or UE, it is necessary to implement a suitable tranmission power control so as to ensure a minimum interference while at the same time a suitable connection quality is to be provided. In particular, situations where a total transmit power of a UE conducting simultaneously cellular and D2D operations may exceed a configured maximum allowed output power for the communication device are to be managed, e.g. in simultaneous cellular operations and D2D discovery operations.

SUMMARY OF THE INVENTION

Examples of embodiments of the invention provide an apparatus, method and computer program product by means of which a flexible transmission power control for a transmission of a discovery signal for a specific communication mode, such as a D2D communication mode, can be provided. In particular, examples of embodiment of the invention provide an apparatus, method and computer program product providing a transmission power control for discovery signal transmission when a communication device conducts both cellular and D2D operations.

This is achieved by the measures defined in the attached claims.

According to an example of an embodiment of the proposed solution, there is provided, for example, an apparatus comprising a transmission power parameter configuration processing portion adapted to configure transmission power parameters usable for determining a transmission power to be set by a communication device for transmitting a discovery signal for a specific communication mode in a predetermined communication area, and a parameter transmission portion configured to prepare and transmit an information element related to the specific communication mode in at least a part of the predetermined communication area, wherein the information element comprises the configured transmission power parameters. Furthermore, according to an example of an embodiment of the proposed solution, there is provided, for example, an apparatus comprising a transmission power parameter processing portion configured to receive and process an information element related to a specific communication mode in a predetermined communication area, wherein the information element comprises transmission power parameters usable for determining a transmission power to be set for transmitting a discovery signal for the specific communication mode in the predetermined communication area, and a transmission power setting portion configured to set the transmission power for transmitting the discovery signal in the specific communication mode on the basis of the processing result of the information element.

Moreover, according to an example of an embodiment of the proposed solution, there is provided, for example, an apparatus comprising a transmission power difference determination portion configured to determine whether a transmission power set for transmitting a discovery signal for a specific communication mode is different to a common transmission power reference value, a discovery signal generating portion configured to generate a discovery signal, and a discovery signal transmitting portion configured to transmit the discovery signal for the specific communication mode with the set transmission power, wherein the discovery signal comprises a power information element indicating whether or not the set transmission power used for transmitting the discovery signal differs to the common transmission power reference value.

In addition, according to an example of an embodiment of the proposed solution, there is provided, for example, an apparatus comprising a discovery signal receiving portion configured to receive a discovery signal for a specific communication mode with a transmission power, wherein the discovery signal comprises a power information element indicating whether or not the transmission power used for transmitting the discovery signal differs to a common transmission power reference value, and a channel estimation processing portion configured to calculate a link quality and path loss on the basis of the actual transmission power of the received discovery signal and information derived from the power information element. Furthermore, according to an example of an embodiment of the proposed solution, there is provided, for example, a method comprising configuring transmission power parameters usable for determining a transmission power to be set by a communication device for transmitting a discovery signal for a specific communication mode in a predetermined communication area, and preparing and transmitting an information element related to the specific communication mode in at least a part of the predetermined communication area, wherein the information element comprises the configured transmission power parameters.

Moreover, according to an example of an embodiment of the proposed solution, there is provided, for example, a method receiving and processing an information element related to a specific communication mode in a predetermined communication area, wherein the information element comprises transmission power parameters usable for determining a transmission power to be set for transmitting a discovery signal for the specific communication mode in the predetermined communication area, and setting the transmission power for transmitting the discovery signal in the specific communication mode on the basis of the processing result of the information element.

In addition, according to an example of an embodiment of the proposed solution, there is provided, for example, a method comprising determining whether a transmission power being set for transmitting a discovery signal for a specific communication mode is different to a common transmission power reference value, generating a discovery signal, and transmitting the discovery signal for the specific communication mode with the set transmission power, wherein the discovery signal comprises a power information element indicating whether or not the set transmission power used for transmitting the discovery signal differs to the common transmission power reference value.

Furthermore, according to an example of an embodiment of the proposed solution, there is provided, for example, a method comprising receiving a discovery signal for a specific communication mode with a transmission power, wherein the discovery signal comprises a power information element indicating whether or not the transmission power used for transmitting the discovery signal differs to a common transmission power reference value, and calculating a link quality and path loss on the basis of the actual transmission power of the received discovery signal and information derived from the power information element.

Moreover, according to an example of an embodiment of the proposed solution, there is provided, for example, a method comprising executing a scaling procedure for scaling a transmission power for a communication device conducting simultaneously a discovery signal transmission for a specific communication mode and an uplink transmission in a cellular communication mode, and determining whether a total transmission power for the simultaneous discovery signal transmission for the specific communication mode and the uplink transmission in a cellular communication mode exceeds a predefined maximum threshold, wherein in case the determining results that the total transmission power exceeds the predefined maximum threshold, the method further comprises scaling down the transmission power used for the discovery signal transmission for the specific communication mode, rechecking whether the total transmission power exceeds the predefined maximum threshold, and in case the rechecking results that the total transmission power exceeds the predefined maximum threshold, scaling down the transmission power for the uplink transmission in the cellular communication mode.

In addition, according to examples of the proposed solution, there is provided, for example, a computer program product for a computer, comprising software code portions for performing the steps of the above defined methods, when said product is run on the computer. The computer program product may comprise a computer-readable medium on which said software code portions are stored. Furthermore, the computer program product may be directly loadable into the internal memory of the computer and/or transmittable via a network by means of at least one of upload, download and push procedures.

By virtue of the proposed solutions, it is possible to provide a flexible transmission power control in particular in cases where a communication device conducts both cellular and D2D operations and a total transnnission power exceeds a maximum allowable threshold, or the like. Specifically, examples of embodiments of the invention provide mechanisms for a flexible signaling of power management related data between the involved entities. Furthermore, a hierarchical power control can be established in discovery area for D2D communication so as to ensure that signaling having a higher priority is not interfered by e.g. discovery signal transmission for D2D communication mode. In addition, at a communication device receiving a discovery signal, it is possible to conduct an improved and more efficient channel estimation processing since it is possible to consider power reductions which may be only temporary, or the like.

The above and still further objects, features and advantages of the invention will become more apparent upon referring to the description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a diagram illustrating a communication network structure in which examples of embodiments of the invention are applicable.

Fig. 2 shows a diagram illustrating an structure of a part of a discovery signal frame structure according to examples of embodiments of the invention.

Fig. 3 shows flow chart illustrating a procedure conducted by a communication network control element according to an example of an embodiment of the invention.

Fig. 4 shows a flow chart illustrating a procedure conducted by a communication element according to an example of an embodiment of the invention. Fig. 5 shows a flow chart illustrating a procedure conducted by a communication element according to an example of an embodiment of the invention.

Fig. 6 shows a flow chart illustrating a procedure conducted by a communication element according to an example of an embodiment of the invention.

Fig. 7 shows a block circuit diagram of a communication network control element including processing portions conducting functions according to examples of embodiments of the invention.

Fig. 8 shows a block circuit diagram of a communication element including processing portions conducting functions according to examples of embodiments of the invention.

Fig. 9 shows a block circuit diagram of a communication element including processing portions conducting functions according to examples of embodiments of the invention.

Fig. 10 shows a flow chart illustrating a power scaling procedure according to an example of an embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

In the following, examples and embodiments of the present invention are described with reference to the drawings. For illustrating the present invention, the examples and embodiments will be described in connection with a cellular communication network based on a 3GPP LTE or LTE-A system. However, it is to be noted that the present invention is not limited to an application using such types of communication system, but is also applicable in other types of communication systems and the like. A basic system architecture of a communication network where examples of embodiments of the invention are applicable may comprise a commonly known architecture of one or more communication systems comprising a wired or wireless access network subsystem and a core network. Such an architecture may comprise one or more access network control elements, radio access network elements, access service network gateways or base transceiver stations, such as a base station (BS) or eNB, which control a coverage area also referred to as a cell and with which a communication element or device such as a UE or another device having a similar function, such as a modem chipset, a chip, a module etc., which can also be part of a UE or attached as a separate element to a UE, or the like, is capable to communicate via one or more channels for transmitting several types of data. Furthermore, core network elements such as gateway network elements, policy and charging control network elements, mobility management entities and the like may be comprised.

The general functions and interconnections of the described elements, which also depend on the actual network type, are known to those skilled in the art and described in corresponding specifications, so that a detailed description thereof is omitted herein. However, it is to be noted that several additional network elements and signaling links may be employed for a communication to or from a communication element like a UE or a communication network control element like an eNB, besides those described in detail herein below.

Furthermore, the described network elements, such as communication elements like UEs or communication network control elements like BSs, eNBs, MME and the like, as well as corresponding functions as described herein may be implemented by software, e.g. by a computer program product for a computer, and/or by hardware. In any case, for executing their respective functions, correspondingly used devices, nodes or network elements may comprise several means and components (not shown) which are required for control, processing and communication/signaling functionality. Such means may comprise, for example, one or more processor units including one or more processing portions for executing instructions, programs and for processing data, memory means for storing instructions, programs and data, for serving as a work area of the processor or processing portion and the like (e.g. ROM, RAM, EEPROM, and the like), input means for inputting data and instructions by software (e.g. floppy disc, CD-ROM, EEPROM, and the like), user interface means for providing monitor and manipulation possibilities to a user (e.g. a screen, a keyboard and the like), interface means for establishing links and/or connections under the control of the processor unit or portion (e.g. wired and wireless interface means, an antenna, etc.) and the like. It is to be noted that in the present specification processing portions should not be only considered to represent physical portions of one or more processors, but may also be considered as a logical division of the referred processing tasks performed by one or more processors.

With regard to Fig. 1, a diagram illustrating a general configuration of a communication network where operations in a cellular communication mode and a specific communication mode, such as a D2D communication mode or the like can be simultaneously conducted by a communication element such as a UE is shown. It is to be noted that the structure indicated in Fig. 1 shows only those devices, network elements and parts which are useful for understanding principles underlying the examples of embodiments of the invention. As also known by those skilled in the art there may be several other network elements or devices involved in a connection between the communication elements (UEs) and the network which are omitted here for the sake of simplicity.

In Fig. 1, reference sign 10 denotes a communication network control element such as an eNB or BS which controls a cell 1 as a communication area. It is to be noted that there may be several cells (such as cell 2) in the communication network which are controlled, for example, by an own communication network control element like an eNB, which belong together with the cell 1 to an overlaying communication area indicated a discovery area where, for example, the same rules for a specific communication mode such as a D2D communication mode apply.

The elMB 10 is connected to core network elements, such as an MME 40, which in turn may be connected to other access network systems or cells, for example a cell 3 controlled by a communication network control element 50 such as an eNB 3. As indicated in Fig. 1, the cell 3 may be configured such that it does not belong to the overlaying communication area (discovery area) to which e.g . cells 1 and 2 belong .

Within cell 1, two UEs, i .e. UE A 20 and UE B 30 are located which are both capable to communicate via cellular transmission and D2D communication mode. For the cellular transmission, UL and DL signaling is exchanged between each UE and the eNB 20. On the other hand, in a D2D communication mode, especially in a D2D discovery signal transmission phase (upon which a setup phase for a D2D communication connection may follow), the signaling is exchanged between the UEs 20 and 30, wherein resources on licensed and unlicensed spectrum may be used.

Usually, as one example for a transmission power scaling procedure executed for transmission power control of e.g. UE A 20, a procedure as described below may be conducted .

For example, for transmission power scaling of PUSCH, the following is considered.

If the total transmit power of the UE A 20 would exceed a value P_CMAX (i) , which is the linear value of the UE total configured maximum output power PCMAX ^{in a} subframe /, the UE conducts a scaling procedure for scaling the transmission power for PUSCH .P for the serving cell c in a subframe / such that the condition Σ ^W( .c (0≤ ( (0 ( ) ^{' " " ( 1 )}

c

is satisfied, where _PUCCH( '^{s tne} 'i^near value of the transmission power of PUCCH in subframe (-T»U_CCH( )/ ¾J_SCH_,c( is the linear value of _PUSCHc(z) , P_CMAX(i) is the linear value of the UE total configured maximum output power P_CMAX andw() is a scaling factor of »_USCH,c( f^or serving cell c where

0 < w(i)≤ l .

In case there is no PUCCH transmission in subframe /^', then _PUCCH(/) = O .

If the UE A 20 has a PUSCH transmission with UCI on serving cell j and PUSCH without UCI in any of the remaining serving cells, and the total transmit power of the UE would exceed P_CMAX{i) , the UE scales puscH_,c( for the serving cells without UCI in subframe / such that the condition

∑W( - JSCH,.( ≤( MAX( - USCHJ ^')) - W c≠j is satisfied where fpuscH, ^1') is the PUSCH transmit power for the cell with UCI andw()is a scaling factor of puscH_)C( for serving cell c without UCI. In this case, no power scaling is applied to ¾_JSCH_,;( unless

∑w( " puSCH_,C( = 0 ... (3)

c≠j and the total transmit power of the UE still would exceed P_CMAX(i) .

It is to be noted that w(/) values are the same across serving cells when H'()>O, but for certain serving cells w() may be zero. If the UE has simultaneous PUCCH and PUSCH transmission with UCI on serving cell j and PUSCH transmission without UCI in any of the remaining serving cells, and the total transmit power of the UE would exceed P_CMAX (i) , the UE obtains _PUSCH , ( according to

and

Σ H ^■ AuSCH.c (0≤ (AMAX (0 - AuCCH (0 ~ AuSCH ( ) ^■ · · ( 5 )

c*j

When the UE A 20 conducts not only cellular (UL) transmission, as assumed in the above power scaling procedure, but conducts also D2D discovery signaling, there is consequently a further factor to be considered in the determination of the total transmission power of the UE A 20, i.e. the transmission power to be used for sending the D2D discovery signal .

In the following, examples of embodiments of the invention providing a flexible transmission power control mechanism in particular in cases where a communication device like UE A 20 shown in Fig. 1 conducts both cellular and D2D operations and a total transmission power may exceed a maximum allowable threshold, or the like are described . For illustrative purposes, a communication network structure as shown in Fig . 1 is assumed as an implementation example.

According to one example of an embodiment of the invention, the communication network control element, such as the eNB 10, configures transmission power related parameters (referred to hereinafter as transmission power parameters) which are usable by a communication element, such as UE A 20, for determining the transmission power required for a respective D2D discovery signal transmissions in its cell (i.e. cell 1). According to examples of embodiments of the invention, the communication area (discovery area, cells) to which also cell 1 and cell 2 (amonsts possibly other cells) belong, wherein a discovery area (communication area) according to examples of embodiments of the invention may comprise also only a part of a cell, is configured to support one or more discovery signal classes which may be classified according to different transmission power parameters, for example short, intermediate and long range discovery signal classes, wherein the transmission power parameters configured by the eNB 10 may be selected according to one of these discovery signal classes.

According to examples of embodiments of the invention, when the transmission power parameters are configured, the eNB 10 may use a specific information element for transporting these parameters to the UE(s) in question. This information element may be, for example, a separate SIBx message defined for D2D communications, or the like (i.e.,„x" may be any integer assigned for a suitable SIB, such as a SIB dedicated to D2D communication purposes, or the like). The information element, such as the SIBx message, may be transmitted to UEs located in the cell 1 by means of broadcasting transmission, wherein according to further examples also other transmitting schemes are possible, for example a transmission only to dedicated communication elements, or the like.

According to further examples of embodiments of the invention, a set of common reference parameters for transmission power determination are defined among the cells (cells 1 and 2) belonging to the same D2D discovery area. According to one example, the common reference parameters may be defined by a certain network entity, e.g. by a core network element like the MME 40. According to a further example, the common reference parameters are configured according to the most power limited cell, so as to mitigate for example inter-cell interference caused for neighboring cells not supporting D2D discovery function, such as cell 3. However, it is to be noted that a configuration of common reference parameters is not limited to these examples, but there are further possibilities to configure them.

In case the parameters configured by the eNB 10 for transmission power deviate from the common reference parameters in a certain cell, e.g. cell 1, the serving eNB 40 indicates a corresponding offset value utilized under its cell for D2D discovery transmissions. The offset value may be indicated via multiples of set step values, e.g., 1 dB step, 2 dB step, 3 dB step, ... etc.

According to a further example of an embodiment of the invention, for indicating that a transmission power set for the transmission of the discovery signal is different (i.e. reduced), a D2D discovery signal comprises a power information element, e.g. in the form of a power management bit (indicated in Fig. 2 as described below). By means of this power information element, according to examples of embodiments of the invention, a communication device such as UE A 20 which transmits a D2D discovery signal is able to indicate (e.g. via the power management bit) that its transmission power differs from a value corresponding to the common reference parameters. It is to be noted that the common reference parameters may be also received from the eNB 10.

According to further examples of embodiments of the invention, the power information element may be a field of plural bits. That is, a D2D discovery signal comprises a field of multiple bits which are used to convey information related to the used transmission power. For example, as also indicated in Fig. 2 described below, an n-bit information field is included in the discovery signal frame structure which is usable, for example, to transmit the offset value in the said D2D discovery signal. In other words, by transmitting the offset value indicating the difference to a value corresponding to the common reference parameters, it is possible to indicate to a receiver how much the transmission power of the corresponding D2D discovery signal differs from the common reference value.

According to still further examples of embodiments of the invention, the UE A 20 which intends to transmit a D2D discovery signal related transmissions checks, after allocating transmission power of an available power budget to transmissions of other radio bearers which may have a higher priority, e.g. SRB (Signaling Radio Bearer) whether a power headroom PHR falls under a certain threshold. The PHR may be, for example, calculated in the UE A 20 as a difference between a maximum UE transmission power and the nominal PUSCH transmission power in a subframe. If the check results that the PHR is lower than the predetermined threshold, the UE A 20 may defer its discovery signal transmission, i.e. already at MAC level.

According to another example of embodiments of the invention, the communication network control element like the elMB 10 may indicate in the discovery related parameters which may be broadcasted in the cell 1, for example, information indicating an allowed power reduction amount or value due to required power scaling, for instance in simultaneous cellular and D2D discovery signal transmissions (e.g. on different carriers on intra-/inter- band CA transmission) to still allow discovery signal transmission.

According to still further examples of embodiments of the invention, in case the cell (such as cell 1) has a neighboring cell (such as cell 3) which does not belong to the discovery area, e.g. since cell 3 does not support the specific communication mode (D2D communication mode), the eNB 10 controlling cell 1 (i.e. the communication network control element controlling the cell belonging to the discovery area) determines a parameter set indicating parameters to be used in its cell to calculate possible power reduction considering the neighboring cell (which does not belong to the discovery area). These parameters of the paremeter set include, for example, the cell ID of the victim cell (i.e. cell 3) and values and factors to be used with path loss measurement towards that victim cell to derive the transmission power reduction for the discovery transmission.

According to further examples of embodiments of the invention, the communication element sending the D2D discovery signal, i.e. UE A 20, includes into the discovery signal information regarding whether the required transmission power reduction is persisting or temporary, for example by adding a reduction type information element into the discovery signal frame structure (as indicated in Fig. 2 described below). This reduction type information element is to indicate to a receiver of the discovery signal (e.g. UE B 30) to consider in a channel estimation or the like the indicated transmission power reduction in different manners, i.e to possibly carry out a feasible path loss and link quality estimation for the transmitter (UE A 20) in question with different assumptions. For example, in case the discovery signal indicates that the transmitter (UE A 20) conducts only a temporary power reduction, the receiver (i.e. UE B 30) takes this into account e.g. by considering a compensation of the reduced power for the calculated path loss by the given reduction value that is also conveyed in the discovery signal. On the other hand, in case the power reduction is indicated to be persistant, such a compensation may be not considered. By means of this, a more accurate estimation regarding link quality and path loss for a D2D communication can be made which is useful in particular in a possible D2D communication setup phase, or the like.

According to examples of embodiments of the invention, a power scaling procedure which is based, for example, on a power scaling algorithm as indicated above is modified in such a manner that a communication element which has to operate simultaneously in a specific communication mode, such as a D2D communication mode for transmitting a discovery signal, as in a cellular communication mode, such as for cellular uplink transmission(s), when it is determined that the total transmission power necessary for the transmissions in both communication modes under current settings would exceed a defined maximum value for an allowed transmission power, first a scaling-down of the transmission power for the communication in the specific communication mode, i.e. for transmitting the D2D discovery signal, is executed, e.g. on the basis of parameters received from the elMB. Then, in case the total transmission power still exceeds the defined maximum value for the transmission power, the scaling-down according to the specified rules for the power scaling as described above are conducted. This procedure may be executed, for example, in case the signals have been already generated and the scaling is done at physical layer.

Fig. 10 shows a flow chart illustrating a corresponding power scaling procedure according to an example of an embodiment of the invention.

In step S200, a scaling procedure for scaling a transmission power for a communication device (e.g. UE A 20) which conducts simultaneously a discovery signal transmission for a specific communication mode (e.g. D2D) and an UL transmission in a cellular communication mode. In step S210, it is determined whether the total transmission power for the simultaneous discovery signal transmission for the specific communication mode (D2D) and the UL transmission in the cellular communication mode exceeds a predefined maximum threshold.

In case the determination result in step S210 is negative, the transmissions in both communication modes (i.e. D2D and cellular, for example) can be conducted according to settings (step S215).

Otherwise, in case the determination in step S210 is affirmative, i.e. the total transmission power exceeds the predefined maximum threshold, the method proceeds to step S230 where a scaling-down of the transmission power used for the discovery signal transmission for the specific communication mode is executed. In other words, it is tried first to decrease the total transmission power by reducing the portion of the discovery signal transmission.

After step S230, in step S40, it is again checked whether the total transmission power exceeds the predefined maximum threshold.

If the reduction in step S230 was sufficient, the determination in step S240 is negative, and similar to step S215, the transmissions are executed with the now set transmission powers in step S245.

Otherwise, in case the rechecking results that the total transmission power still exceeds the predefined maximum threshold, step S250 is executed where a scaling-down of the transmission power used for the UL uplink transmission in the cellular communication mode is conducted, e.g. in accordance with common power scaling algorithms.

According to examples of embodiments of the invention as described above, it is possible to provide a flexible transmission power control in particular in cases where a communication device like the UE A 20 operates in both cellular and D2D communication modes and a resulting total transmission power exceeds a predefined maximum value. Furthermore, a flexible signaling of power management related data (transmission power parameters, information elements comprised in the discovery signal, etc.) is provided. In addition, since signaling having a higher priority, such as SRB related transmissions, can be sent without being affected by a D2D discovery signal transmission, a hierarchical power control can be established in a discovery area. Moreover, since temporary and persisting character of a power reduction can be signaled to a receiving communication element (e.g. UE B 30), an improved and more efficient channel estimation processing is possible.

Fig. 2 shows a diagram illustrating an implementation example of the proposed information fields (i.e. the power information element, the reduction type information element, etc.) in a discovery signal which may be transmitted by a communication element such as UE A 20.

As shown in Fig. 2, the discovery signal frame structure comprises, amongst others, a first field indicated as„TX power indication". In this TX power indication field, the transmission power information element described above may be conveyed.

That is, according to examples of embodiments of the invention, the TX power indication field is a one-bit field wherein one value (e.g.„1") indicates that the used transmission power is in accordance with a commonly set transmission power, i.e. according to a common transmission power reference value which is to be used in the cell in question (e.g. cell 1) for discovery signal transmissions.

On the other hand, in case the one-bit field has the other value (e.g.„0"), this indicates that that the used transmission power is not in accordance with the commonly set transmission power, i.e. that it is lower (reduced) compared to the common transmission power reference value which should be used in the cell in question (e.g. cell 1) for discovery signal transmissions.

Alternatively or additionally, according to examples of embodiments of the invention, the TX power indication field is a n-bit field (n>l) wherein the combination of bits indicated in this field inform about how much the used transmission power is different (lower) than the commonly set transmission power, i.e. compared to a common transmission power reference value, for a discovery signal transmission in the cell in question (e.g. cell 1). It is to be noted that the combination of bits indicated in this field may also indicate a value of 0 dB, which informs about the fact that there is no difference to the reference value.

Furthermore, the discovery signal frame structure may comprise a second field indicated as„TX power reduction type bit". In this second TX power indication field, the reduction type information element described above may be conveyed.

That is, according to examples of embodiments of the invention, the TX power reduction type field may be a one-bit field wherein one value (e.g. „1") indicates that the transmission power reduction for discovery signal transmissions as indicated e.g. in the first field „TX power indication" is temporary, i.e. that the reason why the transmission power for discovery signal transmissions is reduced is temporary. On the other hand, in case the TX power reduction type field indicates the other value (e.g. „0"), this indicates that the transmission power reduction for discovery signal transmissions as indicated e.g. in the first field„TX power indication" is not temporary but permanent or persistant, i.e. that the reason why the transmission power for discovery signal transmissions is reduced is permanently present.

Fig. 3 shows a flow chart illustrating a procedure conducted by a communication network control element, such as an eIMB 10 as shown in Fig. 1, according to an example of an embodiment of the invention.

In step S10, transmission power parameters usable for determining a transmission power to be set by a communication device for transmitting a discovery signal for a specific communication mode in a predetermined communication area, i.e. for determining a transmission power used for a D2D discovery signal transmission. It is to be noted that the predetermined communication area may be, for example, a cell defined for a cellular communication network and controlled by the communication network control element (e.g. cell 1 controlled by eNB 10), a discovery area related to the specific communication mode and comprising one or more cells of a cellular communication network (e.g. cells 1 and 2), or a part of the discovery area.

Furthermore, the configuration of the transmission power parameters in step S10 may comprise, for example, a determination of a deviation from a common parameter set and of a corresponding offset value, an allowed power reduction value, a parameter set related to a neighboring cell not belonging to the discovery area, and the like.

In step S20, an information element related to the specific communication mode such as a SIBx for D2D communication is prepared and transmitted into at least a part of the predetermined communication area, for example by broadcasting or dedicated transmission, wherein the information element comprises the configured transmission power parameters of step S10.

Fig. 4 shows a flow chart illustrating a procedure conducted by a communication element, such as a UE A 20 as shown in Fig. 1, according to an example of an embodiment of the invention.

In step S30, the UE A 20 receives an information element related to a specific communication mode in a predetermined communication area, such as a SIBx message related to D2D communication as transmitted by the eNB 10 in step 20 of Fig. 3, wherein the information element comprises transmission power parameters.

In step S40, the UE A 20 processes the transmission power parameters comprised in the information element for determining the transmission power to be set for transmitting the discovery signal for the specific communication mode (D2D) in the predetermined communication area. In this connection, parameters being related to a deviation from a common parameter set and a corresponding offset value, an allowed power reduction value, a parameter set related to a neighboring cell not belonging to the discovery area, and the like may be considered.

Then, in step S50, the transmission power for sending a (D2D) discovery signal is set in accordance with the processing result according to step S40.

Fig. 5 shows a flow chart illustrating a procedure conducted by a communication element, such as a UE A 20 as shown in Fig. 1, according to an example of an embodiment of the invention. It is to be noted that the procedure according to Fig. 5 may be conducted on the basis of a procedure according to Fig. 4, i.e. on the basis of parameters received in step S30 and processed in step S40, for example.

In step S60, the UE A 20 determines a transmission power value being set for a transmission of a discovery signal, e.g. a D2D discovery signal, which setting may be done, for example, on the basis of power transmission parameters to be used for determining the transmission power. For example, the transmission power may be set according to steps S40 and S50 of Fig. 4.

In step S70, it is determined whether the transmission power being set for transmitting the discovery signal is different to a common transmission power reference value. The common transmission power reference value may be derived, for example, from common parameters being received from the network, e.g. the eNB 10. Alternatively, the determination may be based on an indication of a deviation/offset being provided in parameters received from the eNB 10.

In step S80, a discovery signal is generated wherein the discovery signal comprises a power information element indicating whether or not the set transmission power used for transmitting the discovery signal differs to the common transmission power reference value. For example, a one-bit field and/or a n-bit field as described in connection with Fig. 2 is introduced in the discovery signal frame structure. Also a reduction type information field as indicated in Fig. 2 may be included. In step S90, the thus generated discovery signal may be transmitted by using the set transmission power. In this context, it is to be noted that step S90 may be omitted in case it is determined that the PHR is below a predetermined threshold, as described above.

Fig. 6 shows a flow chart illustrating a procedure conducted by a communication element, such as a UE B 30 as shown in Fig. 1, according to an example of an embodiment of the invention. In other words, the procedure according to Fig. 6 is related to a receiving communication element which receives for example a D2D discovery signal transmitted from another communication element, such as UE A 20, in the discovery area. It is to be noted that a UE may be configured to execute functions of both communication elements, i.e. as a sending communication device and a receiving communication device.

According to Fig. 6, in step SlOO, the UE B 30 receives a discovery signal for a specific communication mode (D2D) with a transmission power which can be measured by the receiving UE. The discovery signal is one being generated according to step S80 of Fig. 5 and comprises the power information element indicating whether or not the transmission power used for transmitting the discovery signal differs to a common transmission power reference value.

In step SI 10, the power information element is processed, for example on the basis of information being related to the common transmission power reference value, which may be derived, for example, from common parameters being received from the network, e.g. the eNB 10. In this processing, it is determined, for example, whether or not the transmission power used for transmitting the discovery signal differs to the common transmission power reference value, or whether a power reduction is persisting or temporary (based on a reduction type information field as indicated in Fig. 2).

In step S120, a channel estimation is executed wherein a link quality and path loss is calculated not only on the basis of the actual transmission power of the received discovery signal but also on information derived from the processing of the power information element in step S110.

In Fig. 7, a block circuit diagram illustrating a circuitry indicating a configuration of a communication network control element, such as an eNB 10, is shown, which is configured to implement the processing for controlling transmission power of discovery signal transmission in a specific communication mode such as a D2D communication as described in connection with the examples of embodiments of the invention. That is, a circuitry is shown which comprises at least one processor and at least one memory including computer program code the at least one memory and the computer program code being configured to, with the at least one processor, cause the eNB to perform functions described below. It is to be noted that the communication network control element or eNB 10 shown in Fig. 7 may comprise several further elements or functions besides those described herein below, which are omitted herein for the sake of simplicity as they are not essential for understanding the invention. Furthermore, even though reference is made to an eNB, the communication network element may be also another device having a similar function, such as a modem chipset, a chip, a module etc., which can also be part of a control element or BS or attached as a separate element to a BS, or the like.

The communication network control element or eNB 10 may comprise a processing function or processor 11, such as a CPU or the like, which executes instructions given by programs or the like related to the control signal transmission control. The processor 11 may comprise one or more processing portions dedicated to specific processing as described below, or the processing may be run in a single processor. Portions for executing such specific processing may be also provided as discrete elements or within one or more further processors or processing portions, such as in one physical processor like a CPU or in several physical entities, for example. Reference sign 12 denote transceiver or input/output (I/O) unit connected to the processor 11. The I/O unit 12 may be used for communicating with a communication element like a UE and a core network element like an MME 40. The I/O unit 12 may be a combined unit comprising communication equipment towards several network elements, or may comprise a distributed structure with a plurality of different interfaces for different network elements. Reference sign 13 denotes a memory usable, for example, for storing data and programs to be executed by the processor 11 and/or as a working storage of the processor 11.

The processor 11 is configured to execute processing related to the above described mechanism for configuring resources and transmitting control information related to a D2D communication function. In particular, the processor 11 comprises a sub-portion 111 as a processing portion which is usable for configuring transmission power parameters. The portion 111 may be configured to perform processing according to step S10 according to Fig. 3, for example. Furthermore, the processor 11 comprises a sub-portion 112 usable as a portion for determining parameters providing information concerning a relation to common parameters, like a deviation amount etc.. In addition, the processor 11 comprises a sub-portion 113 as a processing portion which is usable for preparing and transmitting an information element such as a SIBx message including the transmission power parameters. The portion 113 may be configured to perform processing according to step S20 according to Fig. 3, for example.

In Fig. 8, a block circuit diagram illustrating a circuitry indicating a configuration of a communication element, such as of the UE A 20 shown in Fig. 1, is shown, which is configured to implement the processing for controlling the transmission power for transmitting a (D2D) discovery signal as described in connection with the examples of embodiments of the invention. That is, a circuitry is shown which comprises at least one processor and at least one memory including computer program code the at least one memory and the computer program code being configured to, with the at least one processor, cause the UE A 20 to perform functions described below. It is to be noted that the communication element or UE A 20 shown in Fig. 8 may comprise several further elements or functions besides those described herein below, which are omitted herein for the sake of simplicity as they are not essential for understanding the invention. Furthermore, even though reference is made to a UE, the communication element may be also another device having a similar function, such as a modem chipset, a chip, a module etc., which can also be part of a UE or attached as a separate element to a UE, or the like.

The communication element or UE A 20 may comprise a processing function or processor 21, such as a CPU or the like, which executes instructions given by programs or the like related to the control signal transmission control. The processor 21 may comprise one or more processing portions dedicated to specific processing as described below, or the processing may be run in a single processor. Portions for executing such specific processing may be also provided as discrete elements or within one or more further processors or processing portions, such as in one physical processor like a CPU or in several physical entities, for example. Reference sign 22 denotes transceiver or input/output (I/O) units connected to the processor 21. The I/O units 22 may be used for communicating with elements of the access network, such as a communication network control element like an eNB, and for communicating in a specific communication mode like D2D. The I/O units 22 may be a combined unit comprising communication equipment towards several of the network element in question, or may comprise a distributed structure with a plurality of different interfaces for each network element in question. Reference sign 23 denotes a memory usable, for example, for storing data and programs to be executed by the processor 21 and/or as a working storage of the processor 21.

The processor 21 is configured to execute processing related to the above described mechanism for controlling the transmission power, for example. In particular, the processor 21 comprises a sub-portion 211 as a processing portion which is usable for receiving and processing an information element such as a SIBx which comprises transmission power parameters. The portion 211 may be configured to perform processing according to step S30 according to Fig. 4, for example. Furthermore, the processor 21 comprises a sub-portion 212 as a processing portion which is usable as a portion for processing the transmission power parameters received in with the information element. The portion 212 may be configured to perform a processing according to step S40 according to Fig. 4, for example. Moreover, the processor 21 comprises a sub-portion 213 as a processing portion which is usable as a portion for setting a transmission power for discovery signal transmissions. The portion 213 may be configured to perform processing according to step S50 according to Fig. 4, for example. In addition, the processor 21 may comprise a sub-portion 214 as a processing portion which is usable as a portion for determining a difference to a common transmission power reference value and for generating data used as a power information element and a reduction type information element (if applicable). The portion 214 may be configured to perform a processing according to steps S60, S70 and S80 according to Fig. 5, for example. Moreover, the processor 21 may comprise a sub-portion 215 as a processing portion which is usable as a portion for generating and transmitting a discovery signal comprising a power information element and a reduction type information element. The portion 215 may be configured to perform processing according to steps S80 and S90 according to Fig. 5, for example.

In Fig. 9, a block circuit diagram illustrating a circuitry indicating a configuration of a communication element, such as of the UE B 30 shown in Fig. 1, is shown, as described in connection with the examples of embodiments of the invention. That is, a circuitry is shown which comprises at least one processor and at least one memory including computer program code the at least one memory and the computer program code being configured to, with the at least one processor, cause the UE B30 to perform functions described below. It is to be noted that the communication element or UE B 30 shown in Fig. 8 may comprise several further elements or functions besides those described herein below, which are omitted herein for the sake of simplicity as they are not essential for understanding the invention. Furthermore, even though reference is made to a UE, the communication element may be also another device having a similar function, such as a modem chipset, a chip, a module etc., which can also be part of a UE or attached as a separate element to a UE, or the like. In addition, it is to be noted that a UE may comprise elements according to both Figs. 8 and 9, i.e. may function as both sending and receiving communication element with regard to the discovery signal transmission.

The communication element or UE B 30 may comprise a processing function or processor 31, such as a CPU or the like, which executes instructions given by programs or the like related to the control signal transmission control. The processor 31 may comprise one or more processing portions dedicated to specific processing as described below, or the processing may be run in a single processor. Portions for executing such specific processing may be also provided as discrete elements or within one or more further processors or processing portions, such as in one physical processor like a CPU or in several physical entities, for example. Reference sign 32 denotes transceiver or input/output (I/O) units connected to the processor 31. The I/O units 32 may be used for communicating with elements of the access network, such as a communication network control element like an eNB, and for communicating in a specific communication mode like D2D. The I/O units 32 may be a combined unit comprising communication equipment towards several of the network element in question, or may comprise a distributed structure with a plurality of different interfaces for each network element in question. Reference sign 33 denotes a memory usable, for example, for storing data and programs to be executed by the processor 31 and/or as a working storage of the processor 31.

The processor 31 is configured to execute processing related to the above described mechanism for controlling the transmission power, for example. In particular, the processor 31 comprises a sub-portion 311 as a processing portion which is usable for receiving and processing a discovery signal in the specific communication mode, e.g. a D2D discovery signal. The portion 311 may be configured to perform processing according to step S100 according to Fig. 6, for example. Furthermore, the processor 31 comprises a sub- portion 312 as a processing portion which is usable as a portion for processing a power information element included in the discovery signal. The portion 312 may be configured to perform a processing according to step S110 according to Fig. 6, for example. Moreover, the processor 31 comprises a sub-portion 313 as a processing portion which is usable as a portion for processing a reduction type information element included in the discovery signal. In addition, the processor 31 may comprise a sub-portion 314 as a processing portion which is usable as a portion for calculating a channel estimation (link quality, path loss). The portion 314 may be configured to perform a processing according to step S120 according to Fig. 6, for example.

As described above, examples of embodiments of the invention are described to be implemented in UEs and eNBs. However, the invention is not limited to this. For example, examples of embodiments of the invention may be implemented in a wireless modem or the like.

According to further examples of embodiments of the invention, there is provided an apparatus comprising transmission power parameter configuration processing means for configuring transmission power parameters usable for determining a transmission power to be set by a communication device for transmitting a discovery signal for a specific communication mode in a predetermined communication area, and parameter transmission means for preparing and transmitting an information element related to the specific communication mode in at least a part of the predetermined communication area, wherein the information element comprises the configured transmission power parameters.

According to still further examples of embodiments of the invention, there is provided an apparatus comprising transmission power parameter processing means for receiving and processing an information element related to a specific communication mode in a predetermined communication area, wherein the information element comprises transmission power parameters usable for determining a transmission power to be set for transmitting a discovery signal for the specific communication mode in the predetermined communication area, and transmission power setting means for setting the transmission power for transmitting the discovery signal in the specific communication mode on the basis of the processing result of the information element.

According to further examples of embodiments of the invention, there is provided an apparatus comprising transmission power difference determination means for determining whether a transmission power set for transmitting a discovery signal for a specific communication mode is different to a common transmission power reference value, a discovery signal generating means for generating a discovery signal, and a discovery signal transmitting means for transmitting the discovery signal for the specific communication mode with the set transmission power, wherein the discovery signal comprises a power information element indicating whether or not the set transmission power used for transmitting the discovery signal differs to the common transmission power reference value.

According to still further examples of embodiments of the invention, there is provided an apparatus comprising discovery signal receiving means for receiving a discovery signal for a specific communication mode with a transmission power, wherein the discovery signal comprises a power information element indicating whether or not the transmission power used for transmitting the discovery signal differs to a common transmission power reference value, and channel estimation processing means for calculating a link quality and path loss on the basis of the actual transmission power of the received discovery signal and information derived from the power information element.

According to further examples of embodiments of the invention, there is provided 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 at least to perform a transmission power parameter configuration processing function for configuring transmission power parameters usable for determining a transmission power to be set by a communication device for transmitting a discovery signal for a specific communication mode in a predetermined communication area, and parameter transmission function for preparing and transmitting an information element related to the specific communication mode in at least a part of the predetermined communication area, wherein the information element comprises the configured transmission power parameters.

According to still further examples of embodiments of the invention, there is provided 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 at least to perform a transmission power parameter processing function for receiving and processing an information element related to a specific communication mode in a predetermined communication area, wherein the information element comprises transmission power parameters usable for determining a transmission power to be set for transmitting a discovery signal for the specific communication mode in the predetermined communication area, and a transmission power setting function for setting the transmission power for transmitting the discovery signal in the specific communication mode on the basis of the processing result of the information element.

According to further examples of embodiments of the invention, there is provided 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 at least to perform a transmission power difference determination function for determining whether a transmission power set for transmitting a discovery signal for a specific communication mode is different to a common transmission power reference value, a discovery signal generating function for generating a discovery signal, and a discovery signal transmitting function for transmitting the discovery signal for the specific communication mode with the set transmission power, wherein the discovery signal comprises a power information element indicating whether or not the set transmission power used for transmitting the discovery signal differs to the common transmission power reference value. According to still further examples of embodiments of the invention, there is provided 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 at least to perform a discovery signal receiving function for receiving a discovery signal for a specific communication mode with a transmission power, wherein the discovery signal comprises a power information element indicating whether or not the transmission power used for transmitting the discovery signal differs to a common transmission power reference value, and channel estimation processing function for calculating a link quality and path loss on the basis of the actual transmission power of the received discovery signal and information derived from the power information element.

For the purpose of the present invention as described herein above, it should be noted that

- an access technology via which signaling is transferred to and from a network element may be any technology by means of which a network element or sensor node can access another network element or node (e.g. via a base station or generally an access node). Any present or future technology, such as WLAN (Wireless Local Access Network), WiMAX (Worldwide Interoperability for Microwave Access), LTE, LTE-A, Bluetooth, Infrared, and the like may be used; although the above technologies are mostly wireless access technologies, e.g. in different radio spectra, access technology in the sense of the present invention implies also wired technologies, e.g. IP based access technologies like cable networks or fixed lines but also circuit switched access technologies; access technologies may be distinguishable in at least two categories or access domains such as packet switched and circuit switched, but the existence of more than two access domains does not impede the invention being applied thereto,

- usable communication networks and transmission nodes may be or comprise any device, apparatus, unit or means by which a station, entity or other user equipment may connect to and/or utilize services offered by the access network; such services include, among others, data and/or (audio-) visual communication, data download etc. ; - a user equipment or communication network element may be any device, apparatus, unit or means which is usable as a user communication device and by which a system user or subscriber may experience services from an access network, such as a mobile phone, a wireless mobile terminal, a personal digital assistant PDA, a smart phone, a personal computer (PC), a laptop computer, a desktop computer or a device having a corresponding functionality, such as a modem chipset, a chip, a module etc., which can also be part of a UE or attached as a separate element to a UE, or the like, wherein corresponding devices or terminals may be, for example, an LTE, an LTE-A, a TETRA (Terrestrial Trunked Radio), an UMTS, a GSM/EDGE etc. smart mobile terminal or the like;

- method steps likely to be implemented as software code portions and being run using a processor at a network element or terminal (as examples of devices, apparatuses and/or modules thereof, or as examples of entities including apparatuses and/or modules for it), are software code independent and can be specified using any known or future developed programming language as long as the functionality defined by the method steps is preserved;

- generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the invention in terms of the functionality implemented;

- method steps and/or devices, apparatuses, units or means likely to be implemented as hardware components at a terminal or network element, or any module(s) thereof, are hardware independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as a microprocessor or CPU (Central Processing Unit), MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL (Transistor-Transistor Logic), etc., using for example ASIC (Application Specific IC (Integrated Circuit)) components, FPGA (Field-programmable Gate Arrays) components, CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components; in addition, any method steps and/or devices, units or means likely to be implemented as software components may for example be based on any security architecture capable e.g. of authentication, authorization, keying and/or traffic protection; - devices, apparatuses, units or means can be implemented as individual devices, apparatuses, units or means, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device, apparatus, unit or means is preserved; for example, for executing operations and functions according to examples of embodiments of the invention, one or more processors may be used or shared in the processing, or one or more processing sections or processing portions may be used and shared in the processing, wherein one physical processor or more than one physical processor may be used for implementing one or more processing portions dedicated to specific processing as described,

- an apparatus may be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of an apparatus or module, instead of being hardware implemented, be implemented as software in a (software) module such as a computer program or a computer program product comprising executable software code portions for execution/being run on a processor;

- a device may be regarded as an apparatus or as an assembly of more than one apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing, for example.

Furthermore, as used in this application, the terms , device' or , circuitry' refers to all of the following : (a)hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) to combinations of circuits and software (and/or firmware), such as (as applicable) : (i) to a combination of processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. This definition of 'circuitry' applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in server, a cellular network device, or other network device

As described above, there is provided a mechanism usable for conducting a power control for a transmission of a discovery signal in a communication network, in particular for a D2D discovery signal. A network control element such as an eNB configures transmission power parameters usable for determining a transmission power to be set by a communication device such as a UE for transmitting a discovery signal for a specific communication mode such as a D2D communication mode. The configured transmission power parameters are sent by means of an information element such as a dedicated system information block. In the UE, the transmission power parameters are used to set the transmission power for transmitting the discovery signal in the specific communication mode. The discovery signal comprises a power information element indicating whether or not and possibly how the transmission power used for transmitting the discovery signal differs to a common transmission power reference value. A UE receiving the discovery signal for e.g. D2D communication mode comprising the power information element calculates a link quality and path loss on the basis of the actual transmission power of the received discovery signal and the information derived from the power information element.

Although the present invention has been described herein before with reference to particular embodiments thereof, the present invention is not limited thereto and various modifications can be made thereto.

Claims

1. An apparatus for use in a communication network control element comprising

a transmission power parameter configuration processing portion adapted to configure transmission power parameters usable for determining a transmission power to be set by a communication device for transmitting a discovery signal for a specific communication mode in a predetermined communication area, and

a parameter transmission portion arranged to prepare and transmit an information element related to the specific communication mode in at least a part of the predetermined communication area, wherein the information element comprises the configured transmission power parameters.

2. The apparatus according to claim 1, wherein

the predetermined communication area is at least one of a cell defined for a cellular communication network, a discovery area related to the specific communication mode and comprising one or more cells of a cellular communication network, or a part of the discovery area related to the specific communication mode and comprising one or more cells of a cellular communication network.

3. The apparatus according to claim 1 or 2, wherein

the information element prepared by the parameter transmission portion is a system information block dedicated for the specific communication mode.

4. The apparatus according to any of claims 1 to 3, wherein the specific communication mode is a device-to-device communication mode.

5. The apparatus according to any of claims 1 to 4, further comprising

a deviation determining portion arranged to determine whether or not a deviation of the configured transmission power parameters to a set of common parameters defined for determining a transmission power exists, wherein in case the determination of the deviation determining portion is affirmative, the deviation determining portion is further arranged to determine an offset value corresponding to an amount of the determined deviation, and

the parameter transmission portion is further arranged to include in the information element the offset value.

6. The apparatus according to claim 5, wherein the set of common parameters is defined by at least one of

data provided from a control network element, in particular a mobility management entity of a communication network, and

data derived on the basis of parameters related to a communication area part having the highest transmission power limitation compared to the remaining parts of the communication area.

7. The apparatus according to any of claims 1 to 6, wherein

the transmission power parameter configuration processing portion is further adapted to determine as the transmission power parameters an allowed power reduction value related to a transmission power scaling procedure for allowing a transmission of a discovery signal in the specific communication mode,

wherein the parameter transmission portion is further arranged to include in the information element the allowed power reduction value.

8. The apparatus according to any of claims 1 to 7, wherein

the transmission power parameter configuration processing portion is further adapted to determine as the transmission power parameters a parameter set usable for calculating a power reduction of a transmission power of a discovery signal in the specific communication mode with regard to a neighboring communication area which does not belong to the predetermined communication area, wherein the parameter set comprises at least one of

- an identification of the neighboring communication area, and

- values and factors usable for determining a path loss value towards the neighboring communication area, wherein the parameter transmission portion is further arranged to include in the information element the parameter set.

9. The apparatus according to any of claims 1 to 8, where the apparatus is comprised in a communication network control element, in particular an enhanced node B, wherein the parameter transmission portion is arranged to transmit the information element into a cell controlled by the communication network control element, wherein the apparatus is arranged to be used in an LTE or LTE-A communication system.

10. An apparatus for use in a communication network element comprising a transmission power parameter processing portion arranged to receive and process an information element related to a specific communication mode in a predetermined communication area, wherein the information element comprises transmission power parameters usable for determining a transmission power to be set for transmitting a discovery signal for the specific communication mode in the predetermined communication area, and

a transmission power setting portion arranged to set the transmission power for transmitting the discovery signal in the specific communication mode on the basis of the processing result of the information element.

11. The apparatus according to claim 10, wherein

12. The apparatus according to claim 10 or 11, wherein

the information element received and processed by the transmission power parameter processing portion is a system information block dedicated for the specific communication mode.

13. The apparatus according to any of claims 10 to 12, wherein the specific communication mode is a device-to-device communication mode.

14. The apparatus according to any of claims 10 to 13, wherein

the transmission power parameter processing portion is further arranged to obtain an offset value included in the information element for determining an amount of a deviation of the transmission power parameters to be used for setting a transmission power to common parameters defined for determining a transmission power,

wherein the transmission power setting portion is further arranged to set the transmission power for transmitting the discovery signal in the specific communication mode on the basis of the offset value.

15. The apparatus according to claim 14, wherein the common parameters are defined by at least one of

16. The apparatus according to any of claims 10 to 15, wherein

the transmission power parameter processing portion is further arranged to obtain an allowed power reduction value related to a transmission power scaling procedure for allowing a transmission of a discovery signal in the specific communication mode,

wherein the transmission power setting portion is further arranged to set the transmission power for transmitting the discovery signal in the specific communication mode on the basis of the allowed power reduction value.

17. The apparatus according to any of claims 10 to 16, wherein

the transmission power parameter processing portion is further arranged to obtain a parameter set usable for calculating a power reduction of a transmission power of a discovery signal in the specific communication mode with regard to a neighboring communication area which does not belong to the predetermined communication area, wherein the parameter set comprises at least one of

- an identification of the neighboring communication area, and

- values and factors usable for determining a path loss value towards the neighboring communication area,

the apparatus further comprising a power reduction calculation portion for calculating a power reduction on the basis of the parameter set, wherein the transmission power setting portion is further arranged to set the transmission power for transmitting, the discovery signal in the specific communication mode on the basis of the calculated power reduction.

18. The apparatus according to any of claims 10 to 17, wherein the apparatus is comprised in a communication element, in particular a user equipment arranged to communicate in both a cellular communication mode and the specific communication mode, wherein the apparatus, is arranged to be used in an LTE or LTE-A communication system.

19. An apparatus for use in a communication network element comprising a transmission power difference determination portion arranged to determine whether a transmission power set for transmitting a discovery signal for a specific communication mode is different to a common transmission power reference value,

a discovery signal generating portion arranged to generate a discovery signal, and

a discovery signal transmitting portion arranged to transmit the discovery signal for the specific communication mode with the set transmission power,

wherein the discovery signal comprises a power information element indicating whether or not the set transmission power used for transmitting the discovery signal differs to the common transmission power reference value.

20. The apparatus according to claim 19, wherein the power information element in the discovery signal comprises at least of a one-bit field indicating either presence or absence of a difference between the set transmission power used for transmitting the discovery signal and the common transmission power reference value, or

a multiple-bit field indicating an offset value for defining an amount of difference between the set transmission power used for transmitting the discovery signal differs and the common transmission power reference value.

21. The apparatus according to claim 19 or 20, further comprising

a discovery signal prohibiting portion arranged to determine whether a power headroom value is lower than a predetermined threshold after allocation of transmission power to a transmission of a signal having a higher priority for transmission than the discovery signal transmission,

wherein in case the discovery signal prohibiting portion determines that the power headroom is lower than the threshold, the discovery signal prohibiting portion is further arranged to defer the transmission of the discovery signal by the discovery signal transmitting portion.

22. The apparatus according to any of claims 19 to 21, wherein the discovery signal further comprises a reduction type information element indicating whether a power reduction conducted at a transmission power of discovery signal is permanent or temporary.

23. The apparatus according to any of claims 19 to 22, wherein the apparatus further comprises an apparatus according to any of claims 10 to 18, wherein a value for the set transmission power and the power information element is derived from the information element received and processed by the transmission power parameter processing portion.

24. The apparatus according to any of claims 19 to 23, wherein the specific communication mode is a device-to-device communication mode.

25. The apparatus according to any of claims 19 to 24, wherein the apparatus is comprised in a communication element, in particular a user equipment arranged to communicate in both a cellular communication mode and the specific communication mode in a predetermined communication area comprising at least one of a cell defined for a cellular communication network, a discovery area related to the specific communication mode and comprising one or more cells of a cellular communication network, or a part of the discovery area related to the specific communication mode and comprising one or more cells of a cellular communication network, wherein the apparatus is arranged to be used in an LTE or LTE-A communication system.

26. An apparatus for use in a communication network element comprising a discovery signal receiving portion arranged to receive a discovery signal for a specific communication mode with a transmission power, wherein the discovery signal comprises a power information element indicating whether or not the transmission power used for transmitting the discovery signal differs to a common transmission power reference value, and

a channel estimation processing portion arranged to calculate a link quality and path loss on the basis of the actual transmission power of the received discovery signal and information derived from the power information element.

27. The apparatus according to claim 26, wherein the power information element in the discovery signal comprises at least of

a one-bit field indicating either presence or absence of a difference between the actual transmission power used for transmitting the discovery signal and the common transmission power reference value, or

a multiple-bit field indicating an offset value for defining an amount of difference between the actual transmission power used for transmitting the discovery signal differs and the common transmission power reference value.

28. The apparatus according to any of claims 26 and 27, wherein the discovery signal further comprises a reduction type information element indicating whether a power reduction conducted at a transmission power of discovery signal is permanent or temporary, wherein in case the reduction type information element indicates a temporary power reduction the channel estimating processing portion is further arranged to consider a compensation of an indicated power reduction in the calculated link quality and path loss.

29. The apparatus according to any of claims 26 to 28, wherein the specific communication mode is a device-to-device communication mode.

30. The apparatus according to any of claims 26 to 29, wherein the apparatus is comprised in a communication element, in particular a user equipment arranged to communicate in both a cellular communication mode and the specific communication mode in a predetermined communication area comprising at least one of a cell defined for a cellular communication network, a discovery area related to the specific communication mode and comprising one or more cells of a cellular communication network, or a part of the discovery area related to the specific communication mode and comprising one or more cells of a cellular communication network, wherein the apparatus is arranged to be used in an LTE or LTE-A communication system.

31. A method for use in a communication network control element comprising

configuring transmission power parameters usable for determining a transmission power to be set by a communication device for transmitting a discovery signal for a specific communication mode in a predetermined communication area, and

preparing and determining to transmit an information element related to the specific communication mode in at least a part of the predetermined communication area, wherein the information element comprises the configured transmission power parameters.

32. The method according to claim 31, wherein

33. The method according to claim 31 or 32, wherein

the information element being prepared and determined to be transmitted is a system information block dedicated for the specific communication mode.

34. The method according to any of claims 31 to 33, wherein the specific communication mode is a device-to-device communication mode.

35. The method according to any of claims 31 to 34, further comprising

determining whether or not a deviation of the configured transmission power parameters to a set of common parameters defined for determining a transmission power exists,

wherein in case the determining is affirmative, the method further comprises determining an offset value corresponding to an amount of the determined deviation, and

including in the information element the offset value.

36. The method according to claim 35, wherein the set of common parameters is defined by at least one of

37. The method according to any of claims 31 to 36, further comprising

determining as the transmission power parameters an allowed power reduction value related to a transmission power scaling procedure for allowing a transmission of a discovery signal in the specific communication mode,

wherein the allowed power reduction value is included in the information element.

38. The method according to any of claims 31 to 37, further comprising determining as the transmission power parameters a parameter set usable for calculating a power reduction of a transmission power of a discovery signal in the specific communication mode with regard to a neighboring communication area which does not belong to the predetermined communication area, wherein the parameter set comprises at least one of

- an identification of the neighboring communication area, and

wherein the parameter set is included in the information element.

39. The method according to any of claims 31 to 39, where the method is implemented in a communication network control element, in particular an enhanced node B, wherein the information element is transmitted into a cell controlled by the communication network control element.

40. A method for use in a communication network element comprising

receiving and processing an information element related to a specific communication mode in a predetermined communication area, wherein the information element comprises transmission power parameters usable for determining a transmission power to be set for transmitting a discovery signal for the specific communication mode in the predetermined communication area, and

setting the transmission power for transmitting the discovery signal in the specific communication mode on the basis of the processing result of the information element.

41. The method according to claim 40, wherein

42. The method according to claim 40 or 41, wherein the information element being received and processed is a system information block dedicated for the specific communication mode.

43. The method according to any of claims 40 to 42, wherein the specific communication mode is a device-to-device communication mode.

44. The method according to any of claims 40 to 43, further comprising

obtaining an offset value included in the information element for determining an amount of a deviation of the transmission power parameters to be used for setting a transmission power to common parameters defined for determining a transmission power,

wherein the setting of the transmission power for transmitting the discovery signal in the specific communication mode is executed on the basis of the offset value.

45. The method according to claim 44, wherein the common parameters are defined by at least one of

46. The method according to any of claims 40 to 45, further comprising

obtaining an allowed power reduction value related to a transmission power scaling procedure for allowing a transmission of a discovery signal in the specific communication mode,

wherein the setting of the transmission power for transmitting the discovery signal in the specific communication mode is executed on the basis of the allowed power reduction value.

47. The method according to any of claims 40 to 46, further comprising

obtaining a parameter set usable for calculating a power reduction of a transmission power of a discovery signal in the specific communication mode with regard to a neighboring communication area which does not belong to the predetermined communication area, wherein the parameter set comprises at least one of

- an identification of the neighboring communication area, and

and

calculating a power reduction on the basis of the parameter set, wherein the setting of the transmission power for transmitting the discovery signal in the specific communication mode is executed on the basis of the calculated power reduction.

48. The method according to any of claims 40 to 47, wherein the method is implemented in a communication element, in particular a user equipment arranged to communicate in both a cellular communication mode and the specific communication mode.

49. A method for use in a communication network element comprising

determining whether a transmission power being set for transmitting a discovery signal for a specific communication mode is different to a common transmission power reference value,

generating a discovery signal, and

determining to transmit the discovery signal for the specific communication mode with the set transmission power,

50. The method according to claim 49, wherein the power information element in the discovery signal comprises at least of

a one-bit field indicating either presence or absence of a difference between the set transmission power used for transmitting the discovery signal and the common transmission power reference value, or

51. The method according to claim 49 or 50, further comprising

determining whether a power headroom value is lower than a predetermined threshold after allocation of transmission power to a transmission of a signal having a higher priority for transmission than the discovery signal transmission,

wherein in case it is determined that the power headroom is lower than the threshold, the method further comprises determining to defer the transmission of the discovery signal.

52. The method according to any of claims 48 to 51, wherein the discovery signal further comprises a reduction type information element indicating whether a power reduction conducted at a transmission power of discovery signal is permanent or temporary.

53. The method according to any of claims 49 to 52, wherein the method further comprises a method according to any of claims 30 to 38, wherein a value for the set transmission power and the power information element is derived from the information element being received and processed.

54. The method according to any of claims 49 to 53, wherein the specific communication mode is a device-to-device communication mode.

55. The method according to any of claims 49 to 54, wherein the method is implemented in a communication element, in particular a user equipment arranged to communicate in both a cellular communication mode and the specific communication mode in a predetermined communication area comprising at least one of a cell defined for a cellular communication network, a discovery area related to the specific communication mode and comprising one or more cells of a cellular communication network, or a part of the discovery area related to the specific communication mode and comprising one or more cells of a cellular communication network.

56. A method for use in a communication network element comprising receiving a discovery signal for a specific communication mode with a transmission power, wherein the discovery signal comprises a power information element indicating whether or not the transmission power used for transmitting the discovery signal differs to a common transmission power reference value, and

calculating a link quality and path loss on the basis of the actual transmission power of the received discovery signal and information derived from the power information element.

57. The method according to claim 56, wherein the power information element in the discovery signal comprises at least of

58. The method according to any of claims 56 and 57, wherein the discovery signal further comprises a reduction type information element indicating whether a power reduction conducted at a transmission power of discovery signal is permanent or temporary, wherein in case the reduction type information element indicates a temporary power reduction the method further comprises considering a compensation of an indicated power reduction in the calculation of the link quality and path loss.

59. The method according to any of claims 56 to 58, wherein the specific communication mode is a device-to-device communication mode.

60. The method according to any of claims 56 to 59, wherein the method is implemented in a communication element, in particular a user equipment arranged to communicate in both a cellular communication mode and the specific communication mode in a predetermined communication area comprising at least one of a cell defined for a cellular communication network, a discovery area related to the specific communication mode and comprising one or more cells of a cellular communication network, or a part of the discovery area related to the specific communication mode and comprising one or more cells of a cellular communication network.

61. A method for use in a communication network control element comprising

executing a scaling procedure for scaling a transmission power for a communication device conducting simultaneously a discovery signal transmission for a specific communication mode and an uplink transmission in a cellular communication mode, and

determining whether a total transmission power for the simultaneous discovery signal transmission for the specific communication mode and the uplink transmission in a cellular communication mode exceeds a predefined maximum threshold,

wherein in case the determining results that the total transmission power exceeds the predefined maximum threshold, the method further comprises

scaling down the transmission power used for the discovery signal transmission for the specific communication mode,

rechecking whether the total transmission power exceeds the predefined maximum threshold, and

in case the rechecking results that the total transmission power exceeds the predefined maximum threshold,

scaling down the transmission power for the uplink transmission in the cellular communication mode.

62. The method according to claim 61, wherein the specific communication mode is a device-to-device communication mode.

63. A computer program product for a computer, comprising software code portions for performing the steps of any of claims 31 to 39, 40 to 48, 49 to 55, 56 to 60, or 61 and 62, when said product is run on the computer.

64. The computer program product according to claim 63, further comprising a computer-readable medium on which said software code portions are stored.

65. The computer program product according to claim 64, wherein the computer program product is directly loadable into the internal memory of the computer and/or transmittable via a network by means of at least one of upload, download and push procedures.