FR2866186A1 - Parameter server for mobile terminal, has storage unit storing co-relation between wireless reception parameters along channels between mobile terminals and base stations, and data localizing terminals within network - Google Patents

Abstract

The server has a transmission control protocol/Internet protocol (TCP/IP) interface and two applications communicating with a radio network controller (12) and a storage unit. The storage unit stores co-relation between wireless reception parameters observed along propagation channels between mobile terminals (14, 14a, 14b) and base stations (13), and data localizing the mobile terminals within a cell of a cellular network. Independent claims are also included for the following: (A) a process for acquiring parameters in a cellular mobile telephone network (B) a mobile radio communication terminal including a measuring unit and a transmission unit (C) a process for controlling resources communicated between a mobile terminal and an infrastructure of cellular radio network (D) a controller for a cellular network controller.

Description

RADIO DATA SERVER AND LOCATION,

  AND ITS APPLICATIONS IN A CELLULAR RADIO NETWORK

  The present invention relates to the field of digital radiocommunications. It finds particular application in spread spectrum cellular networks using code division multiple access (CDMA) methods, for example in third generation networks of the UMTS type ("Universal Mobile Telecommunication"). System ").

  Spectrum spreading techniques have the particularity of enabling multiple propagation paths to be taken into account between the transmitter and the receiver, which provides an appreciable gain in reception diversity. The receiver generally determines a propagation profile that includes one or more propagation paths associated with a respective reception energy. The determined profile is used to perform a coherent demodulation of the received radio signal. This is especially done in the receiver called "rake".

  Cellular networks employ various kinds of radio resource management (RRM) procedures to oversee communications between base stations and mobile terminals. For this, radio parameter measurements (field levels, signal-to-noise ratio, estimated quality of the received signal, etc.) taken by the terminals and / or the base stations are collected and RRM algorithms are executed. to better adjust, with the aid of the measured parameters, certain characteristics of the allocated communication channel or channels.

  There are many families of RRM procedures commonly used: transmit power control, handover control, active set management, and multi-cell downlink power distribution control in macrodiversity, channel code management. in a CDMA system, channel reconfiguration, link adaptation (channel coding, modulation), etc. The increasing sophistication of cellular systems, including third-generation systems, is driving the development of a wide variety of RRM procedures that significantly improve the performance of these systems.

  In W003 / 005753, it was shown that the propagation profile in a multipath context was a very relevant measure to be taken into account in various RRM procedures. This profile makes it possible not to confine oneself to examining the energies or global qualities of reception on the different propagation channels. By having information on the energy distributions in the propagation profiles, the control organ can better appreciate, for example, the need to add or remove cells in the active set assigned to a terminal in macrodiversity. or the need to increase or decrease the transmit power of the base stations of the cells of the active set.

  In W003 / 085856, it is proposed to refer to the control body information on the temporal variability of the energy level received on the channel between the mobile terminal and the base station, which can take the form of the variance of this parameter. energy level. This variance is related to the multipath diversity provided by the propagation profile, so that RRM procedures can also take advantage of this parameter.

  In UMTS systems, the RRM procedures are performed under the supervision of a Radio Network Controller (RNC) which retrieves the measurements made by the terminals using the Radio Resource Control (RRC) protocol described in Technical Specification TS 25.331, "RRC Protocol Specification", version 4.1.0 released in June 2001 by the 3GPP (3rd Generation Partnership Project), and those performed by base stations using NBAP ("Node B Application Protocol") "described in the technical specification 3G TS 25.433, version 4.1.0," UTRAN lub Interface NBAP Signaling ", published in June 2001 by the 3GPP).

  The RRC and NBAP protocols incorporate measurement reporting functions. The RNC indicates to the terminal and / or the base station which parameters it needs to receive the measurements for the RRM procedures it applies, and these measurements are reported in standardized messages. The standard thus provides a toolbox whose complexity is relatively large given the diversity of RRM procedures that can be applied and their implementations. The support of this toolbox is generally required at the terminals and base stations so that the operator can choose the RRM procedures that he deems interesting for his network. The result is a certain complexity of the equipment, even though only a small part of the possibilities offered will in practice be used. This explains the reluctance encountered for the inclusion of new parameters among those whose terminals or base stations may have to go up the measurements.

  For example, the data describing the propagation profile or the temporal variability of the energy level received are not currently part of the parameters provided for in the standard, despite the interest they present.

  In general, it is desirable to be able to enrich the RRM procedures available to the operator without necessarily having to rely on the messaging mechanisms of the standard.

  One of the aims of the present invention is to meet this need.

  The invention thus proposes a parameter server for a cellular radio network, comprising means of communication with at least one operational member of the network and means for storing an association between radio reception parameters, observed according to propagation channels. between at least one mobile terminal and a base station serving a cell, and location data of the mobile terminals within the cell.

  Systems under development are increasingly incorporating terminal location functions. The server according to the invention advantageously takes advantage of the fact that certain radio parameters are strongly correlated with the location of the terminals in the cells. This server stores a map of one or more of these parameters. It may be consulted by the radio network controller or another operational body of the network infrastructure, having previously obtained information on the location of a terminal, to get an idea of the value of such a parameter for this terminal and take it into account in one or more RRM procedures.

  This type of consultation makes it possible to take into account the radio parameter without its measurement having been specifically requested from the terminal or the base station concerned.

  The radio reception parameter taken into consideration in the server 10 may notably comprise: data dependent on the energy distribution in a propagation profile including at least one propagation path between the mobile terminal and the base station, associated with an energy respective reception according to said path; or - data representative of a temporal variability of an energy level received on a propagation channel between the mobile terminal and the base station.

  Another aspect of the present invention relates to a method of acquiring parameters in a cellular radio access network, comprising the steps of: measuring a radio reception parameter according to propagation channels between at least one mobile terminal and a base station serving a cell; and storing, in a parameter server accessible from at least one operational member of the network, an association between the measured radio reception parameters and location data of the mobile terminals within the cell.

  Preferably, the radio reception parameter is measured by the terminal on the propagation channel and addressed to the parameter server in an application message transmitted on the radio by the terminal. The use of application messages makes it possible to overcome the constraints of the standard. Even a minority of terminals capable of locating will be able to provide the information necessary for the acquisition of the parameters by the server. It suffices to provide these terminals with an application software that notes their location and the parameter of interest (generally determined by the lower layers of the terminal) and sends the parameter location pair to the server.

  Another aspect of the present invention relates to a mobile radio communication terminal, comprising means for measuring at least one radio reception parameter dependent on radio propagation conditions observed in the reception of signals from a base station. serving a cell of a cellular radio access network, location means, and means for transmitting, to a parameter server accessible from at least one operational member of the network, an application message indicating the radio reception parameter measured in relation to a location of the terminal in the cell.

  The invention is also directed to applications of the parameter server presented above.

  In particular, there is provided a method of controlling radio resources allocated to a communication between a mobile terminal and a cellular radio network infrastructure, and a radio network controller for carrying out this method. The infrastructure includes at least the radio network controller, a parameter server accessible from the radio network controller, and base stations serving respective cells. The parameter server stores for at least one cell an association between radio reception parameters, observed according to propagation channels between at least one mobile terminal and the base station serving said cell, and location data within the cell. . The method for controlling radio resources according to the invention comprises the following steps executed at the radio network controller: obtaining location data from a mobile terminal in a cell; - consult the parameter server using the location data obtained to retrieve a value indication of the radio parameter associated with said location data; and - using said radio parameter value indication in the supervision of a terminal communication via the base station serving the cell.

  On the other hand, it may happen that the radio parameter whose server stores a map is measured and made available in the network for a given terminal. In this case, the parameter server can be consulted to refine the information available on the location of the terminal. Ambiguities resulting from other methods used to locate the terminal can thus be removed.

  Another aspect of the present invention thus relates to a method for locating mobile terminals in a cellular radio communication network whose infrastructure comprises at least one terminal location center, a parameter server accessible from the location center, and base stations serving respective cells. The parameter server stores for at least one cell an association between radio reception parameters, observed according to propagation channels between at least one mobile terminal and the base station serving said cell, and location data within the cell. . The locating method according to the invention comprises the following steps: obtaining a measurement of a radio reception parameter according to a propagation channel between at least one mobile terminal located in a cell and the base station serving said cell; consult the parameter server using the measured reception parameter to retrieve location data within the cell; and collecting, at the location center, terminal location data including the retrieved location data.

  Other features and advantages of the present invention will appear in the following description of nonlimiting exemplary embodiments, with reference to the appended drawings, in which: FIG. 1 is a diagram of a UMTS network adapted to the implementation implementation of the invention; FIG. 2 is a diagram showing the layered organization of protocols used on the UMTS radio interface; FIG. 3 is a block diagram of the transmitting part of a radio transceiver of a UMTS base station; FIG. 4 is a block diagram of the transmitting part of a UMTS mobile terminal; FIG. 5 is a block diagram of a receiver of a UMTS station; FIG. 6 is a block diagram of a RNC of the UMTS network; and FIGS. 7 and 8 are block diagrams respectively of a mobile terminal and a parameter server according to the invention.

  The invention is described below in its application to a UMTS network, of which Figure 1 shows the architecture.

  The switches of the mobile service 10, belonging to a core network (CN, "Core Network"), are connected on the one hand to one or more fixed networks 11 and on the other hand, by means of a so-called interface read, to control equipment 12, or RNC ("Radio Network Controller"). Each RNC 12 is connected to one or more base stations 9 by means of an interface called tub. The base stations 9, distributed over the coverage territory of the network, are able to communicate by radio with the mobile terminals 14, 14a, 14b called UE ("User Equipment"). The base stations 9, also called "node B", can each serve one or more cells by means of respective transceivers 13. Some RNCs 12 can further communicate with each other by means of an interface called lur. RNCs and base stations form an access network called UTRAN ("UMTS Terrestrial Radio Access Network").

  The UTRAN comprises elements of layers 1 and 2 of the ISO model to provide the required links on the radio interface (called Uu), and a layer 15A of radio resource control (RRC) belonging to layer 3, as well as that it is described in the technical specification 3G TS 25.301, "Radio Interface Protocol", version 3.4.0 published in March 2000 by the 3GPP. Seen from the upper layers, UTRAN acts simply as a bridge between the EU and CN.

  Figure 2 shows the RRC stages 15A, 15B and the lower layer stages which belong to the UTRAN and a UE. On each side, the layer 2 is subdivided into a radio link control stage (RLC) 16A, 16B and a Medium Access Control (MAC) stage 17A, 17B. ). The layer 1 comprises a coding and multiplexing stage 18A, 18B. A radio stage 19A, 19B ensures the transmission of the radio signals from the symbol trains supplied by the stage 18A, 18B, and the reception of the signals in the other direction.

  There are different ways to adapt the protocol architecture according to Figure 2 to the hardware architecture of the UTRAN according to Figure 1, and in general different organizations can be adopted depending on the types of channels (see section 11.2 of the specification). technical 3G TS 25. 401, "UTRAN Overall Description", version 3.1.0 published in January 2000 by the 3GPP). The stages RRC, RLC and MAC are in the RNC 12. The layer 1 is for example in the node B 9. Part of this layer can however be in the RNC 12.

  When multiple RNCs are involved in a communication with a UE, there is usually a serving RNC called SRNC ("Serving RNC"), where Layer 2 (RLC and MAC) modules are located, and at least one RNC relay called DRNC ("Drift RNC") which is connected to a base station 9 with which the UE is in radio link. Appropriate protocols provide the exchanges between these RNCs on the interface lur, for example ATM ("Asynchronous Transfer Mode") and AAL2 ("ATM Adaptation Layer No. 2"). These same protocols can also be used on the interface lub for the exchanges between a node B and its RNC.

  Layers 1 and 2 are each controlled by the RRC sublayer, the characteristics of which are described in the above-mentioned technical specification TS 25. 331. The RRC stage 15A, 15B supervises the radio interface. It further processes streams to be transmitted to the remote station according to a "control plane", as opposed to the "user plane" which corresponds to the processing of user data from layer 3.

  UMTS uses the CDMA technique of spread spectrum, that is to say that the transmitted symbols are multiplied by spreading codes consisting of samples called "chips" whose rate (3.84 Mchipls in the case of UMTS) is greater than that of transmitted symbols. The spreading codes o distinguish different physical channels (PhCH) which are superimposed on the same transmission resource constituted by a carrier frequency. The auto- and cross-correlation properties of the spreading codes allow the receiver to separate the PhCHs and extract the symbols intended for it.

  For the UMTS in FDD ("Frequency Division Duplex") mode on the downlink, a scrambling code is allocated to each transceiver 13 of each base station 9, and different physical channels used by this transceiver are distinguished by mutually orthogonal channelization codes. The transceiver 13 may also use several mutually orthogonal scrambling codes, one of them being a primary scrambling code. On the uplink, the transceiver 13 uses the scrambling code to separate the emitter UEs, and possibly the channel code to separate the physical channels from the same UE. For each PhCH, the overall spreading code is the product of the channel code and the scrambling code. The spreading factor (equal to the ratio between the chip rate and the symbol rate) is a power of 2 between 4 and 512. This factor is chosen according to the symbol rate to be transmitted on the PhCH.

  The different physical channels are organized in frames of 10 ms which succeed one another on the carrier frequency used. Each frame is subdivided into 15 timeslots of 666 s. Each slice may carry the overlapping contributions of one or more physical channels, including common channels and dedicated DPCH ("Dedicated -10-Physical Channel") channels.

  On the downlink, one of the common channels is a pilot channel called CPICH (Common Pilot Channel). This channel carries a pilot signal, or beacon signal, formed from a predetermined symbol sequence (see technical specification 3G TS 25.211, "Physical Channels and Mapping of Transport Channels to Physical Channels (FDD)", version 3.3.0 published in June 2000 by the 3GPP). This signal is emitted by the transceiver 13 on the primary scrambling code of the cell, with a determined channel code.

  FIG. 3 schematically illustrates the transmission part of a fixed transceiver 13 of a UMTS base station, serving a cell by means of a scrambling code cscr. The layer 1 can multiplex several transport channels (TrCH) coming from the MAC sublayer on one or more PhCHs. The module 18A receives the descendant TrCH data streams from the RNC and applies to them the coding and multiplexing operations required to form the data portion (DPDCH) of the DPCHs to be transmitted. These coding and multiplexing functions are described in detail in the technical specification 3G TS 25.212, "Multiplexing and channel coding (FDD)", version 3.3.0 published in June 2000 by 3GPP.

  This DPDCH data portion is multiplexed in time, within each time slot of 666 ms with a control portion (DPCCH) having control information and predetermined pilot symbols, as shown schematically in Figure 3 by the multiplexers 20 which form the binary flows of DPCHs. On each channel, a serial / parallel converter 21 forms a complex digital signal whose real part is constituted by the bits of even rank of the stream and the imaginary part by the bits of odd rank. The module 22 applies to these complex signals their respective channel codes cch, which are allocated by a control unit 23. The module 24 weights the resulting signals in accordance with the respective transmission powers of the physical channels, determined by a process of power control.

  The complex signals of the various channels are then summed by the adder 25 before being multiplied by the scrambling code cscr of the cell by means of the module 26. The adder 25 also receives the contribution of the CPICH, which is not multiplied by a channel code since the CPICH channel code is constant and equal to 1 (3G TS 25.213 technical specification, "Spreading and modulation (FDD)", version 3.2.0 released in March 2000 by 3GPP). The complex baseband signal s delivered by the module 26 is subjected to a shaping filter and converted into analog before modulating the carrier frequency in QPSK ("Quadrature Phase Shift Keying"), and to be amplified and emitted by the base station.

  The different transmission resources of the transceiver 13 are allocated to the channels by the unit 23 under the control of the RRC stage 15A located in the RNC. The corresponding control messages are transmitted using the transceiver control protocol (NBAP).

  Figure 4 schematically illustrates the transmission part of an UE. It is assumed here that this UE transmits on a single physical channel. The module 27 ensures the coding and possibly the multiplexing of the TrCH corresponding to a physical channel. This forms a real signal (DPDCH) which will be transmitted on a channel I. At the same time, control information as well as pilot symbols are assembled by a module 28 to form a real signal (DPCCH) which will be transmitted on a Q channel. digital signals of channels I and Q form the real and imaginary parts of a complex signal whose transmission power is adjusted by a module 29. The resulting signal is modulated by the spreading code of the channel constituted by a scrambling code cscr, as represented by the multiplier 30. The complex baseband signal thus obtained is filtered, converted to analog, and the carrier frequency QPSK modulated.

  Figure 5 is a block diagram of a CDMA receiver that can be in the UE for the downlink, or in the B node for the uplink. This receiver comprises a radio stage 31 which performs the required analog processing on the radio signal picked up by an antenna 32. The radio stage 31 delivers a complex analog signal whose real and imaginary parts are digitized by the analog-digital converters 33 on respective processing channels I and Q. On each channel, a filter 34 adapted to pulse shaping by the transmitter produces a digital signal at the rate of chips spreading codes.

  These digital signals are subjected to a suitable filter bank 35. These filters are adapted to the spreading codes and channels to be considered. These spreading codes ci (products of a scrambling code and o of a possible channel code) are supplied to the adapted filters 35 by a control module 40 which notably manages the allocation of the resources of the receiver. On the Node B side, the control module 40 is supervised by the RRC stage 15A of the RNC through the NBAP protocol. On the EU side, the control module 40 is supervised by the RRC stage 15B.

  For N physical channels (spreading codes) taken into account, the adapted filters 35 deliver N real signals on the I channel and N real signals on the Q channel, which are supplied to a module 36 for separating the data and the signals drivers. For the downlinks, the separation consists in extracting the portions of the time slots containing the complex pilot signals transmitted by the node B to provide them to the channel analysis module 37, the corresponding data being addressed to the fingers 38 of the rake receiver. In the case of uplinks, the separation effected by the module 36 consists in extracting the real pilot signals from the channel Q relative to each channel to supply them to the analysis module 37.

  For each physical channel, denoted by an integer index i, the analysis module 37 identifies a number of propagation paths, denoted by an index j, on the basis of the portion of the output signal of the matched filter corresponding to the symbols pilots, which is a sampling of the impulse response of the channel.

  There are different ways to represent the propagation paths for the rake receiver. One method consists in searching for the maxima of the impulse response of the sampled channel at the output of the adapted filter 35, averaged over a period of the order of one hundred milliseconds. Each propagation path is then represented by a delay tij corresponding to one of the maxima, of instantaneous amplitude ai J. In this case, the processing carried out in each finger 38 of the rake receiver, allocated to the path j of the channel i, consists of to sample the signal received on the channel i with the delay ti j and to multiply the result by with *. The selected paths are those for which the reception energies are the largest, the reception energy following a path of a channel i being equal to the average of ai, i 2 In another possible representation (see WO01 / 41382 ), each propagation path of a channel i is represented by an eigenvector of the autocorrelation matrix of the impulse response vector provided by the matched filter 35. In the processing carried out in the finger 38 of the rake receiver, the sampling with the delay is then replaced by the scalar product of the filter output vector adapted by the eigenvector seen. To estimate the eigenvectors, the analysis module 37 carries out a diagonalization of the autocorrelation matrix, which also provides the associated eigenvalues Xi j. The eigenvalue ai, equal to the expectation of ai j 2, represents the energy of reception of the signal on the path j of the channel i.

  The combination module 39 of the rake receiver receives the contributions from the fingers 38 and, for each channel i, calculates the sum of the respective contributions of the paths retained j, indicated by the control module 40. The result is the local estimation of the symbols of information transmitted on channel i.

  In the case of a UE receiving down signals in macro-diversity mode, that is to say from several transceivers 13 using different spreading codes, the module 39 can also add the contributions of the corresponding propagation channels. in order to obtain the gain in diversity. The resulting combined estimates are then subjected to the decoding and demultiplexing stage (not shown in FIG. 5). In the case of a base station 9 receiving on several transmitters-

  Receivers 13 of the uplink signals from the same mobile terminal in macrodiversity mode, the local estimates delivered by the respective combination modules 39 of these transceivers 13 are also combined to obtain the diversity gain.

  In the case of a rising macrodiversity between several base stations 9 receiving signals coming from the same mobile terminal, the local estimates delivered by the respective combination modules 39 of the transceivers 13 are subjected to the decoding stage and for demultiplexing (not shown in FIG. 5) to obtain the estimated symbols of the concerned TrCH (s). These symbols are transmitted to the SRNC via the interface lub (lur) in which they are combined to obtain the diversity gain.

  The corresponding combination module of the RNC 12 is designated by the reference 50 in FIG. 6. This module retrieves the TrCH symbols from the different base stations on the interface lub and / or lur 51 and supplies them with the MAC stage 17A. after combination. In the downstream direction, this module 50 belonging to the physical layer is responsible for broadcasting the streams of TrCH from the MAC stage 17A to the base stations concerned.

  Fig. 6 further schematically illustrates an instance 52 of the NBAP protocol executed at RNC 12 for controlling a remote base station. The dialogue between the RRC stage 15A of the RNC and that 15B of a UE is carried out by means of a "RRC connection" managed as described in section 8.1 of the aforementioned technical specification 3G TS 25.331.

  The RRC protocol procedures include measurement procedures described in Section 8.4 of Technical Specification 3G TS 25.331, which are used in particular to update the active set for macrodiversity UEs (or SHOs) as well as adjustment of the transmit powers of the transceivers of the active set. The measurements desired by the RNC are requested from the UEs in "MEASUREMENT CONTROL" messages, in which the reporting modes are also indicated, for example with a specified periodicity or in response to certain events. The measurements specified by the RNC are then carried out by the UE which goes up on the RRC connection in "MEASUREMENT REPORT" messages (see sections 10.2.17 and 10.2.19 of the technical specification 3G TS 25.331). These messages "MEASUREMENT CONTROL" and "MEASUREMENT REPORT" are relayed transparently by the transceivers 13 of the base stations.

  Several non-standard algorithms may be used by the SRNC to determine the transceivers 13 of the active set. In some cases, these active set determination algorithms may take into account uplink measurements, performed by the base station transceivers 13 and reassembled in accordance with the NBAP procedures described in sections 8.3.8 to 8.3.11. the technical specification 3G TS 25.433 mentioned above. The RNC indicates to node B the measurements it needs in a "DEDICATED MEASUREMENT MEASUREMENT REQUEST" message, and the Node B goes back to them in a "DEDICATED MEASUREMENT REPORT" message (see sections 9.1.52 and 9.1.55 of technical specification 3G TS 25.433).

  The modifications of the active set are notified to the UE (receiver control module 40) by means of the RRC SHO active set update procedures described in section 8.3.4 of the specification. 3G TS 25.331 (message "ACTIVE SET UPDATE" in section 10.2.1).

  These changes also result in the sending of RNC signaling to base stations 9 through the NBAP protocol establishment, addition, reconfiguration and deletion procedures described in Section 8 of the Specification. technical 3G TS 25.433.

  The measurements taken into consideration by the RNC to control the radio links in SHO include power measurements made on the pilot signals or channels, obtained by a measurement module 41 shown in FIG. 5. Various measures that must be able to be performed mobile terminals and base stations are listed in the technical specification 3G TS 25.215, "Physical layer Measurements (FDD)", version 3. 3.0 published in June 2000 by 3GPP. The measurements obtained by the module 41 are transmitted to the RNC via the control module 40 and the RRC connection (UE measurement) or the NBAP protocol (measurement of the B node).

  For a given channel i, the sum of the eigenvalues j, determined by the analysis module 37 for the p propagation paths taken into consideration (1 jsp), represents the overall energy received on the channel, reduced to the duration of 'a symbol. This energy is called RSCP in the standard ("Received Signal Code Power"). The analysis module 37 also determines for each channel i the residual power of the noise after taking into account the p paths. This residual power is called ISCP in the standard ("Interference Signal Code Power"). The quantity (RSCP / ISCP) x (SF / 2) represents the signal-to-interferer ratio (SIR) for a downlink channel, where SF denotes the spreading factor of the channel. The SIR is equal to (RSCP / ISCP) xSF for a rising channel.

  In practice, a quantity of RSCP type is estimated in the physical layer of the receiver (module 37) over a period d1 of the order of one hundred milliseconds, and the estimated value is sent back to the RRC layer (or NBAP) if a corresponding parameter is required by the RNC. In general, it is required with an upper averaging period d2, for example of the order of half a second. The values reported by the physical layer are thus averaged between them by the module 41 to determine the measurement to be provided to the RNC. The two estimation periods d1, d2 are adjustable.

  The SIR, evaluated on the pilot symbols transmitted on a dedicated channel, is a measure that the RNC can request from the UE or the node B, and it can possibly take it into account in the management of the active set.

  The radio receiver is further capable of measuring the received power in the signal bandwidth around a UMTS carrier. This power, measured by a module 42 upstream of the adapted filters 35, is indicated by the quantity called RSSI ("Received Signal Strength Indicator").

  The UEs in communication monitor in parallel the energies received on the CPICH channels of cells belonging to a monitored set MS ("monitored set") comprising the active set and a number of neighboring cells. These energy measurements are generally reported to the RNC in the "MEASUREMENT REPORT" messages. The quantities raised can be the absolute energies (CPICH_RSCP) or normalized with respect to the energy of the received signal (CPICH_Ec / N0 = CPICH_RSCP / RSSI). Since the network signals to the UEs the transmission powers of the B nodes on the CPICH channels, denoted by CPICH_Tx_Power, the UE can also calculate the signal attenuation ("pathloss") on the propagation channel from each node B of the monitored unit (PL = CPICH Tx Power / CPICH RSCP). The standard provides that the RNC may request the EU to report this mitigation parameter (3G TS 25.331, sections 10.3.7.38 and 14.1.1).

  To allow finer consideration of the propagation characteristics by the active set determination and power control algorithms for this active set, it is advantageous for the RNC to have an indication of diversity-related radio reception parameters. in multipath B node propagation channels UE.

  Such a parameter Q may especially correspond to data depending on the energy distribution in the propagation profile (see WO03 / 005753). The analysis module 37 of the receiver calculates the eigenvalues Xi = E ai, which are summed over the path index j to obtain the RSCP of the estimated channel i over the duration d1: rscp1 = D, i j. It therefore has information on the energy distribution in the propagation profile relating to channel i. The Q data taken into account are averaged over the durations d1 and d2, and they represent, for example: the p values Xi j, in absolute form (Xi j, homogeneous to CPICH_RSCP) or normalized (1.1ii = Xi / RSSI homogeneous at CPICH_Ec / NO); the relative values of the detected paths with respect to the main path whose energy Xi max is maximum, ie pi, j = / Xi max; the values Xi j, i j or pi j which exceed a predefined threshold; how many paths j give rise to a reception energy Xi j, or pi j greater than a predefined threshold; the delays t1 j of the different paths j; etc. The radio reception parameter Q may also correspond to data depending on the temporal variability of the energy level received (see W003 / 085856). The analysis module 37 of the receiver has instantaneous values of the complex amplitudes ai j corresponding to the successive pilot symbols, and therefore instantaneous energies ri = E is the estimated mathematical expectation over the duration d1. The module 37 can also estimate one or more moments of order n of the temporal distribution of the energies ri, given by mi (n) = E (rin E (ri) n). In a simple realization, this estimate is limited to the moment of order n = 2, that is to say to the variance: mi (2) = E (ri2) rscp 2.

  But the feedback of such parameter measurements to the RNC, which imposes some design constraints on the terminals or even on the base stations, is not necessarily supported by the standard.

  To overcome this limitation, it is proposed to equip the network with a parameter server 60 (FIG. 1) storing, for at least some of the cells, a cartography of the radio reception parameter Q that the operator considers relevant but that the mechanisms of the standard does not allow it to obtain explicitly for terminals in communication.

  The location services are provided in the UMTS system shown in Figure 1. These services are described in particular in the technical specification TS 25.305, version 5.7.0, ("User Equipment (UE) positioning in Universal Terrestrial Radio"). Access Network (UTRAN); Stage 2 "), published in September 2003 by 3GPP.

  The UTRAN operates with a Mobile Location Center (SMLC) which can either be integrated with the radio subsystem or be independent equipment. In the latter case, the SMLC is called SAS ("Stand-Alone SMLC"). A SAS 61 connected to the RNC 12 via a PCAP interface is thus represented in FIG. 1. The PCAP interface is described in the technical specification TS 25.453, version 6.2.0, "UTRAN lupc interface Positioning Calculation; Application Part (PCAP) signaling ", published in September 2003 by the 3GPP.

  The SRNC 12 is responsible for implementing the procedure for locating an UE 14b with which it maintains an RRC connection, at the request of a client that may be internal or external to the radiocommunication system to which the UE 14b is attached. The SAS 61 is used as a location calculation server, when the RNC 12 does not perform the calculation itself.

  In a third-generation system, several localization methods are available. For example, a first method is based on a cell ID or Cell ID. The UE is thus located by the knowledge of the identity of the node B with which it is connected, the position or the coverage area of the node B being known. If the UE is not connected to any BTS, that is to say if it is not in active mode, the network can probe it for example by paging, so that it is attached to a node B. This cell identification can be supplemented by other measures such as Round Trip Time (RTT) measurements that give an approximation of the round trip delay between the UE and its B node with which it is link.

  A second location method is called OTDOA-IPDL-20 ("Observed Time Difference Of Arrival Idle Period DownLink"). Measurements of reception time differences are made by the UE from several B nodes. If these B nodes are not synchronized, the Real Time Difference (RTD) offset between their emissions by means of an equipment called LMU ("Location Measurement Unit"). The LMU can either be integrated in a node B, or be an independent equipment whose position is well identified. These different measurements are sent back to the RNC or the SMLC, which can then estimate a positioning of the mobile terminal by subtracting RTD from OTD. Each Node B can additionally introduce silence periods (IPDL) optionally, so as to improve the listening quality of neighboring B nodes by the EU, and to avoid the glare phenomenon of the UE by a node B near which it receives a signal with a high level of field. The OTDOA measurements are then improved when IPDL is used, to the detriment of the quality of the communications in progress which can thus be interrupted during the periods of silence of certain nodes B. A third method of localization, called UTOA ("Uplink Time Of Arrival") "), is based on signal arrival time measurements from the mobile terminal made by the base stations.

  A fourth method of localization, finally, is based on the GPS positioning system ("Global Positioning System"). The position of the mobile terminal is then estimated by the SMLC according to the GPS system.

  In a typical embodiment of the invention, at least some of the UEs equipped with GPS receivers are provided with an application 65 which, as illustrated in FIG. 7, is capable of performing the following operations: obtaining the GPS receiver 66 the position geographical x, y of the EU; obtain from the measurement module 41 of the radio transceiver 67, the receiving part of which can be in accordance with FIG. 5, the relevant radio reception parameter Q (set of eigenvalues Xi j, variance m1 (2), etc. ) after averaging; and - constructing an application message transmitted to the parameter server 60 via the radio transceiver 67 and including the location pairs x, y / parameter Q. Such an application 65 may have been downloaded by the operator into terminals equipped with GPS receivers. It may also have been installed from the outset in terminals that the operator has given to some of its subscribers. The terminals thus equipped, or acquisition terminals, as and when they move in the cells where the operator organizes the radio parameter map, transmit to the server 60 the radio parameter location pairs from which the server performs an analysis. statistical correlations of the radio parameter with the location of the terminals in the cell. The results of this analysis are associations between location areas in the cells and values or ranges of radio parameter values.

  In practice, the parameter server 60 may be collocated with the RNC or hosted in an external device accessible by the RRM functions of the concerned RNC (s).

  The manager of the parameter server 60 knows a list of terminal identifiers provided with the application 65, which typically are very small in the fleet of terminals in circulation. When the RNC detects an RRC connection with such a terminal in a given cell, it alerts the server 60, which can then send the terminal an application request to return the radio parameter location pair. The request is executed by the application 65 of the terminal.

  In some cases, the receiver of the terminal is able to estimate its speed of movement v (see W002 / 41539). It is then advantageous for the application 65 to receive this measurement v from the receiver 67 and to return the application message including the radio parameter location pair only if the estimated speed v is below a certain threshold. This threshold can be chosen by the server 60 and indicated in its request. This filtering of the measurements as a function of the speed improves the reliability of the analysis made by the server 60.

  To control the radio resources available to a UE in communication, the RNC which maintains its RRC connection can enrich with the server 60 the information obtained in the measurement reports from the UE or from one or more nodes B if he has obtained, in a known manner (possibly with the help of SAS 61), location data of the UE. For this, the RNC queries the server 60 by indicating the cell concerned and providing the location data obtained. The server 60 responds by returning the value or range of values of the associated radio parameter. This indication is then exploitable by various RRM procedures, for example as explained in W003 / 005753 or W003 / 085856.

  FIG. 8 shows a possible structure of the parameter server 60. This communicates with the RNCs and / or with the UEs via a Transmission Control Protocol / Internet Protocol (TCP / IP) interface 70. network infrastructure being conventionally based on the IP protocol. The server hosted a first application 71 cooperating with RNCs and UEs for the acquisition and processing of couples location radio parameter. The results of the statistical analysis are recorded in a database 73. A second interrogation application 72 processes the requests, in particular from the RNC 12, to consult the database 73 and return the values of the radio parameter corresponding to the location data presented in the queries.

  In the foregoing description, it is the UE which determines its own position by means of its GPS receiver 66. Another possible embodiment consists in recovering the location data of the UE by means of the localization means of which it is provided. the network. The server 60 indicates for example to the RNC 12 the zone or zones of a cell where measurements of the Q parameters would be desirable in order to enrich its database 73. When the RNC detects for an active UE whose location data, for example, example obtained by the SAS 61, indicate that it is in such a zone, it sends the request application message, or it warns the server 60 that it can send such a message. It is then sufficient for the application message returned by the UE to provide the requested radio reception parameter.

  In some cases, the base station is able to estimate the traveling speed v of the UE based on radio measurements. As disclosed in WO02 / 41539, the speed information thus obtained can be communicated to the RNC by the base station. If the RNC / SMLC has also located the UE, it is advantageous for it to refrain from triggering the application request if the estimated speed exceeds a threshold specified by the server 60.

  In another variant, the parameter server 60 requests the RNC 12 to broadcast in a cell a message containing data defining one or more location zones within the cell, for example an area in which the server does not have not yet a reliable association between the location and the parameter Q, or has an old association deserving to be updated.

  The application 65 installed in an acquisition UE is alerted when its receiver detects the broadcast of this message. The application 65 checks whether the location x, y provided by the GPS receiver falls in the indicated zone, and the application message is returned to the server 60 only if the verification is positive, that is to say if the UE is located in the indicated area. In this case, it is not always mandatory for the application message to contain the GPS position x, y since the server 60 can implicitly deduce the location on the scale of the indicated area by receiving a response to the request. .

  The optimization using the server 60 of an RRM procedure, such as for example the management of the active set, has been described above in the case where the measures taken into account are downward measurements made by the terminals 14, 14a, 14b. Note that the measurements in question may also, in whole or in part, consist of rising measurements made by the base stations 13, the reception profile and the variance can be measured in one direction or the other on the channel of propagation.

  Insofar as the server 60 stores the associations between the location of the terminals and the corresponding propagation profiles or variances, it is conceivable to make it available to a location center (SMLC) hosted by RNC 12 or by a SAS 61 in the goal of refining the location of a terminal.

  Naturally, this supposes that the network has been able to obtain a measurement of the value of the radio parameter Q specific to the terminal whose location is sought. This measurement is for example obtained by the RNC as described in WO03 / 005753 or WO03 / 085856 from the UE or the node B. It is possible that it is a rising measurement even if the measurements used to make up the server database 60 are top-down measures, and vice versa.

  Having obtained the value thus measured, the RNC incorporating the SMLC function sends the server 60 a request for location data of the UE inside the cell with which it is in communication. This query identifies the cell and includes the value of the Q parameter measured for that cell. The server 60 consults its database 73 to identify the zone or areas of the cell where the mobile terminal is most likely given the indicated Q value. The response returned to the SMLC by the server 60 includes the location data that identifies this (these) area (s).

  The data retrieved in this way will generally not be sufficient to locate the terminal exactly. But they can supplement the measurements obtained by other means (RTT measurements, OTDOA-IPDL, ...) in order to remove ambiguities or more generally to refine the localization.

- 25 -

Claims (23)

  A parameter server for a cellular radio network, comprising means (70-72) for communicating with at least one operational member of the network (12, 61) and means (73) for storing an association between parameters of radio reception, observed according to propagation channels between at least one mobile terminal (14, 14a, 14b) and a base station (13) serving a cell, and location data of the mobile terminals within the cell.   2. Server according to claim 1, comprising means (71) for acquiring receiving parameter location pairs in application messages from mobile terminals (14, 14a, 14b).   A server according to any one of the preceding claims, wherein said radio reception parameter comprises data dependent on the energy distribution in a propagation profile including at least one propagation path between the mobile terminal (14, 14a, 14b). and the base station (13) associated with a respective reception energy along said path.   A server according to any one of the preceding claims, wherein said radio reception parameter comprises data representative of a time variability of an energy level received on a propagation channel between the mobile terminal (14, 14a, 14b) and the base station (13).   Method for acquiring parameters in a cellular radio access network, comprising the following steps: measuring a radio reception parameter according to propagation channels between at least one mobile terminal (14, 14a, 14b) and a station base (13) serving a cell; and - storing, in a parameter server (60) accessible from at least one operational member of the network (12, 61), an association between the measured radio reception parameters and the location data of the mobile terminals within the network. the cell.   The method according to claim 5, wherein the radio reception parameter is measured by the terminal (14, 14a, 14b) on the propagation channel and addressed to the parameter server (60) in an application message transmitted on the radio by the terminal.   The method of claim 6, wherein the application message further contains terminal location data (14, 14a, 14b).   The method of claim 6 or 7, wherein the application message is returned by the terminal (14, 14a, 14b) in response to a request from the parameter server (60).   The method of claim 8, wherein the request of the parameter server (60) is broadcast in the cell and includes data defining at least one area of the cell, and the application message is returned by at least one terminal (14). , 14a, 14b) located in said area.   The method according to any one of claims 5 to 9, wherein said radio reception parameter comprises data dependent on the energy distribution in a propagation profile including at least one propagation path between the mobile terminal (14, 14a, 14b) and the base station (13) associated with a respective reception energy along said path.   The method according to any one of claims 5 to 10, wherein said radio reception parameter comprises data representative of a time variability of an energy level received on a propagation channel between the mobile terminal (14, 14a, 14b) and the base station (13).   - 27 - 12. A mobile radio communication terminal, comprising means (41) for measuring at least one radio reception parameter depending on radio propagation conditions observed in the reception of signals coming from a base station (13) serving a cell a cellular radio access network, location means (66), and transmission means (65), to a parameter server (60) accessible from at least one operational member of the network (12, 61), an application message indicating the radio reception parameter measured in relation to a location of the terminal in the cell.   The terminal of claim 12, wherein the application message further contains terminal location data obtained by the location means (66).   Terminal according to claim 12 or 13, wherein the transmission means (65) are adapted to return the application message in response to a request from the parameter server (60).   Terminal according to claim 14, wherein the request of the parameter server (60) comprises data defining at least one zone of the cell, and the transmission means (65) are adapted to return the application message when the means of location (66) indicates that the terminal is located in said area.   Terminal according to any one of claims 12 to 15, wherein said radio reception parameter comprises data dependent on the energy distribution in a propagation profile including at least one propagation path from the base station (13), associated with a respective reception energy along said path.   Terminal according to any one of claims 12 to 16, wherein said radio reception parameter comprises data representing a temporal variability of an energy level received on a propagation channel between the mobile terminal and the base station. (13).   - 28 - 18. A method for controlling radio resources assigned to a communication between a mobile terminal (14, 14a, 14b) and a cellular radio network infrastructure, the infrastructure comprising at least one radio network controller (12), a parameter server (60) accessible from the radio network controller, and base stations (13) serving respective cells, the parameter server storing for at least one cell an association between radio reception parameters, observed according to propagation channels between at least one mobile terminal and the base station serving said cell, and location data within the cell, the method comprising the following steps performed at the radio network controller: obtaining location data of a mobile terminal in a cell; consulting the parameter server using the location data obtained to retrieve a value indication of the radio parameter associated with said location data; and using said radio parameter value indication in the supervision of a terminal communication through the base station serving the cell.   The method of claim 18, wherein a moving speed estimate (v) of the mobile terminal (14, 14a, 14b) is obtained, and said steps are performed provided that the estimated speed is less than a threshold.   The method of claim 19, wherein the moving speed (v) of the mobile terminal (14, 14a, 14b) is estimated in the mobile terminal based on radio signals received from said at least one base station.   The method of claim 19, wherein the moving speed (v) of the mobile terminal (14, 14a, 14b) is estimated in the base station based on radio signals received from the mobile terminal.   - 29 - A cellular radio network controller, comprising means for interfacing with base stations (13) serving respective cells, and means for communicating with a parameter server (60) storing for at least one cell an association between radio reception parameters, observed according to propagation channels between at least one mobile terminal (14, 14a, 14b) and the base station serving said cell, and location data within the cell, the radio network controller comprising means for obtaining location data of a mobile terminal in a cell; means for accessing the parameter server using the location data obtained to retrieve a value indication of the radio parameter associated with said location data; and communications supervision means adapted to use said radio parameter value indication in the supervision of terminal communication through the base station serving the cell.   23. A method of locating mobile terminals (14, 14a, 14b) in a cellular radio communication network, the network having an infrastructure comprising at least one terminal location center (61), a parameter server (60) accessible from the location center, and base stations (13) serving respective cells, the parameter server storing for at least one cell an association between radio reception parameters, observed according to propagation channels between at least one mobile terminal and the base station serving said cell, and location data within the cell, the method comprising the steps of: - obtaining a measurement of a radio reception parameter along a propagation channel between at least one mobile terminal located in a cell and the base station serving said cell; - 30 - - consult the parameter server using the measured reception parameter to retrieve location data within the cell; and collect, at the location center, terminal location data including the retrieved location data.