Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
  • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
  • H04B7/2603—Arrangements for wireless physical layer control
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B17/00—Monitoring; Testing
  • H04B17/30—Monitoring; Testing of propagation channels
  • H04B17/391—Modelling the propagation channel
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
  • H04B7/022—Site diversity; Macro-diversity
  • H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
  • H04B7/022—Site diversity; Macro-diversity
  • H04B7/026—Co-operative diversity, e.g. using fixed or mobile stations as relays
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
  • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
  • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
  • H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
  • H04B7/0842—Weighted combining
  • H04B7/0848—Joint weighting
  • H04B7/0857—Joint weighting using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
  • H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
  • H04L1/0618—Space-time coding
  • H04L1/0625—Transmitter arrangements
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
  • H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
  • H04L1/0618—Space-time coding
  • H04L1/0631—Receiver arrangements
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L7/00—Arrangements for synchronising receiver with transmitter
  • H04L7/0016—Arrangements for synchronising receiver with transmitter correction of synchronization errors
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W52/00—Power management, e.g. Transmission Power Control [TPC] or power classes
  • H04W52/02—Power saving arrangements
  • H04W52/0203—Power saving arrangements in the radio access network or backbone network of wireless communication networks
  • H04W52/0206—Power saving arrangements in the radio access network or backbone network of wireless communication networks in access points, e.g. base stations
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/14—Relay systems
  • H04B7/15—Active relay systems
  • H04B7/155—Ground-based stations
  • H04B7/15592—Adapting at the relay station communication parameters for supporting cooperative relaying, i.e. transmission of the same data via direct - and relayed path
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
  • H04W88/08—Access point devices
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
  • H04W88/08—Access point devices
  • H04W88/10—Access point devices adapted for operation in multiple networks, e.g. multi-mode access points
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
  • Y02D30/00—Reducing energy consumption in communication networks
  • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

• the present invention belongs to the field of digital telecommunications. More particularly, the present invention relates to an access network for terminals of a digital telecommunications system, said access network comprising base stations adapted to receive radiofrequency signals transmitted by said terminals, and possibly adapted to transmit data. radio frequency signals to the terminals.
• the digital telecommunications systems implement, for exchanging binary data, a predefined physical layer protocol whose purpose, in particular, is to convert said binary data into a radio frequency signal that can be transmitted in a band. frequency preset.
• a physical layer protocol generally provides a succession of predefined steps.
• the physical layer protocol provides, on the side of the terminal, steps applied to a binary data stream. These steps include a modulation step, during which the binary data are converted into symbols (for example BPSK, DBPSK, QPSK, 16QAM, etc.), and a step of translating into frequencies, so as to obtain a radio frequency signal. centered on a predefined center frequency.
• a modulation step during which the binary data are converted into symbols (for example BPSK, DBPSK, QPSK, 16QAM, etc.)
• a step of translating into frequencies so as to obtain a radio frequency signal. centered on a predefined center frequency.
• the physical layer protocol provides for applying to a radiofrequency signal received from the terminal a reverse processing of that applied in transmission.
• the radio frequency signal must be translated into frequencies so as to obtain a baseband signal (that is to say, centered on a substantially zero center frequency).
• This baseband signal is then demodulated to obtain binary data which, in the absence of errors, are equal to the binary data transmitted by the terminal.
• the same steps are applied, in the case of a bidirectional telecommunications system, for a transfer of binary data from a base station to a terminal.
• the physical layer protocol can provide many other steps, for example an error correction coding step, an interleaving step, a filtering step, and so on.
• such a physical layer protocol generally provides for the insertion of control data to facilitate the inverse physical layer processing.
• the tasks to be performed in reception are much more numerous than in transmission since it is generally necessary to detect whether a radiofrequency signal has been emitted, to estimate the start time of said radio frequency signal (time synchronization). and the center frequency of said radio frequency signal (frequency synchronization), estimating the propagation channel to compensate for its effects, etc.
• the reverse processing to be performed in reception are very numerous and require significant computing power. This is all the more critical for base stations that can simultaneously receive binary data from multiple terminals.
• the base stations perform other operations, relating to the processing of protocol layers that use the services of the physical layer (eg MAC, TCP / IP, etc.).
• the present invention aims to remedy all or part of the limitations of the solutions of the prior art, in particular those set out above, by proposing a solution that makes it possible to reduce the computing power required for the base stations of a computer. access network of a digital telecommunications system.
• the present invention also aims to provide such a solution that allows, in some cases, to improve the performance of the access network of the telecommunications system.
• the invention relates to an access network for terminals of a digital telecommunications system, said access network comprising base stations adapted to receive radio frequency signals transmitted by said terminals, each terminal comprising a physical layer processing module adapted to form a radio frequency signal from binary data in accordance with a predefined physical layer protocol; .
• a physical layer inverse process for extracting binary data from a radiofrequency signal formed in accordance with the physical layer protocol is distributed between said partial station and a processing server (32) separate from said partial station.
• a physical layer inverse processing module decomposes, for said partial station, into a first inverse processing module, integrated in said partial station and adapted to form intermediate data from a radio frequency signal received from a terminal, and a second inverse processing module, integrated in the processing server, and adapted to extract binary data from said intermediate data.
• the access network may comprise one or more of the following characteristics, taken separately or in any technically possible combination.
• the access network comprises at least one other inverse processing module, integrated in the processing server or in another partial station separate from said processing server, said at least one other processing module inverse is also associated with the second processing module of the processing server.
• each first inverse processing module is configured to include, in the intermediate data, data, estimated by said first inverse processing module, relating to one or more characteristics of the radiofrequency signal from which said intermediate data are formed, called "signal identification data", and the second processing processing inverse module is configured to identify, by comparison, signal identification data included in intermediate data received from first inverse processing modules. different, the data intermediates corresponding to radiofrequency signals received from the same terminal.
• the second inverse processing module of the processing server is configured to perform a combination of intermediate data, received from different first inverse processing modules, corresponding to radio frequency signals received from the same terminal.
• the second inverse processing module of the processing server is configured to perform a selection of intermediate data among intermediate data, received from different first inverse processing modules, corresponding to radio frequency signals received from the same terminal.
• the invention relates to a method of digital telecommunications between a terminal and an access network, comprising a step of forming, by the terminal, a radio frequency signal from binary data in accordance with a predefined protocol of physical layer, and a step of extraction, by the access network and applying a physical layer inverse processing, of binary data from the radio frequency signal received from the terminal.
• the physical layer inverse processing is distributed between said partial station and a processing server separate from said partial station, the step for extracting binary data comprising the steps of:
• the telecommunications method may comprise one or more of the following characteristics, taken separately or in any combination technically possible.
• the radiofrequency signal transmitted by the terminal being received by at least two first inverse processing modules of separate base stations forming intermediate data, said first two inverse processing modules being connected to the same second inverse processing module, the extraction step by said second inverse processing module comprises the identification of the intermediate data formed by different base stations which correspond to radio frequency signals received from the same terminal.
• the step of extraction by said second inverse processing module comprises the combination of the intermediate data identified as corresponding to radio frequency signals received from the same terminal.
• the extraction step by said second inverse processing module comprises the selection of intermediate data among the intermediate data identified as corresponding to radio frequency signals received from the same terminal.
• the forming step includes inserting, in the intermediate data, a parameter representative of a signal-to-noise ratio of the radiofrequency signal, and in that the combination or the selection of intermediate data formed by different base stations is performed according to said parameters included in said intermediate data.
• the training step comprises the insertion, in the intermediate data, of a specific identification code of the base station having formed said intermediate data.
• the training step comprises the insertion, in the intermediate data, of data, estimated by the first inverse processing module, relating to one or more characteristics of the radio frequency signal from which said data intermediaries are formed, called "signal identification data".
• FIGS. 1a, 1b and 1c exemplary embodiments of a digital telecommunications system according to the invention
• FIG. 2 a diagram illustrating the main steps of a digital telecommunications method according to the invention
• FIG. 3 a diagram illustrating an example of physical layer inverse processing operations
• FIG. 4 a diagram illustrating the main steps of a preferred embodiment of a digital telecommunications method according to the invention.
• Figure 1a schematically shows an example of a digital telecommunications system 10 according to the invention.
• the digital telecommunications system 10 comprises terminals 20, as well as an access network 30 comprising base stations adapted to exchange radio frequency signals with the terminals 20.
• the terminals 20 access a core 40 via the network of said access network 30.
• terminal means any object adapted to communicate with an access network 30 of a digital telecommunications system 10.
• a terminal 20 may be fixed or mobile, and may for example be in the form of a mobile phone, a laptop, a sensor of a telemetry system, etc.
• the invention is described in the case where binary data must be transmitted by a terminal 20 to the access network 30. It should however be noted that the invention is also applicable in the case where binary data must be transmitted in the opposite direction, that is to say they must be transmitted by the access network 30 to a terminal 20.
• Each terminal 20 includes a physical layer processing module adapted to form a radio frequency signal from binary data in accordance with a predefined physical layer protocol.
• the access network 30 performs, in accordance with said predefined physical layer protocol, the inverse processing, in order to extract the binary data transmitted by a terminal 20 as a function of radiofrequency signals received from a base station of the access network 30. .
• the inverse processing is distributed between said partial station 31 and a processing server 32 of the access network 30, said processing server being distinct from said partial station.
• processing server 32 may be remote from the partial station 31, said processing server 32 and the partial station then being located in different geographical areas, for example in different buildings, for example separated by a few hundred meters or more.
• the partial station 31 comprises a first inverse processing module 310 which performs a first part of the physical layer inverse processing operations.
• the first inverse processing module 310 therefore forms intermediate data from a radiofrequency signal received from a terminal 20, said intermediate data being different from the binary data to be extracted.
• the processing server 32 includes a second inverse processing module 320, which performs a second part of the physical layer inverse processing operations.
• the second inverse processing module 320 consequently extracts the binary data from the intermediate data received from the first inverse processing module 310.
• the binary data extracted by the second inverse processing module 320 are, in the absence of errors, equal. to the binary data transmitted by the terminal 20. It is thus understood that the intermediate data correspond to data obtained, during the inverse physical layer processing, between the radio frequency signal and the binary data.
• the intermediate data are therefore different from both the radio frequency signal and the binary data, in that:
• the intermediate data are obtained from the radiofrequency signal by applying a first part of the physical layer inverse processing operations
• the binary data are obtained from the intermediate data by applying a second and last part of the physical layer inverse processing operations.
• the partial station 31 and the processing server 32 each comprise transfer means 33 which transfer the intermediate data from said partial station 31 to said processing server 32.
• Any type of adapted transfer means 33 can be implemented. and it is understood that the choice of a particular type of transfer means 33 is only a variant of implementation of the invention.
• said transfer means 33 may comprise wireless or wired or mixed wireless / wired communication means.
• all the base stations are partial stations 31 connected to the same processing server 32, so that the second inverse processing module 320 of the processing server 32 is used by several stations. partial 31.
• the physical layer inverse processing operations subsequent to those performed by the first inverse processing modules 310 of the different partial stations are all centralized at the level of the second inverse processing module 320 of the processing server 32.
• FIG. 1b shows a second example of a telecommunications system 10 comprising both partial stations 31 connected to a processing server 32, and at least one base station, called "complete station" 34, adapted to perform all the operations reverse physical layer processing.
• the complete station 34 is directly connected to the core network 40.
• FIG. 1c represents a variant of FIG. 1b, in which the processing server 32 is a complete station 34, that is to say comprising both a first inverse processing module 310 and a second processing module inverse 320, of which said second inverse processing module 320 is also used by partial stations 31.
• each partial station 31 is connected to one of the processing servers 32. , or to several processing servers 32 for purposes of redundancy (in the event of a failure of a processing server 32).
• FIG. 2 represents the main steps of a digital telecommunications method 50 according to the invention.
• the digital telecommunications method 50 comprises a step 51 of forming, by a terminal 20, a radio frequency signal from binary data in accordance with the predefined physical layer protocol, and a step 52 of extraction, by the access network 30 of said binary data from the radiofrequency signal received from said terminal 20.
• the step 52 of extracting binary data comprises, according to the invention, the steps of:
• the transfer step 521 comprises a step 521a of transmission, by the partial station 31, of said intermediate data, and a step 521b of reception, by the processing server 32, of said intermediate data.
• FIG. 3 schematically represents a nonlimiting example of physical layer inverse processing operations adapted to the case where the terminals 20 are configured to transmit radio frequency signals in frequency sub-bands specific to a frequency band, called "multiplexing band".
• the physical layer inverse processing firstly comprises an analog processing step E1.
• the radio frequency signals received by at least one antenna in the multiplexing band are translated into frequencies so as to obtain an analog signal in the vicinity of an intermediate frequency.
• the physical layer inverse processing then comprises an analog / digital conversion step E2. During this step, the analog signal is converted to a digital signal by means of analog / digital converters.
• the inverse physical layer processing then comprises a step E3 transposition in the frequency domain, during which the digital signal is transposed from the time domain to the frequency domain, so as to obtain a frequency spectrum of the digital signal.
• Said transposition in the frequency domain is for example carried out by means of an FFT module ("Fast Fourier Transform").
• the inverse physical layer processing then comprises a detection step E4, during which, in the frequency spectrum of the digital signal, frequencies are sought for which peaks of energy are obtained which may correspond to the presence of a signal.
• a detection criterion is verified, for example when an energy peak is greater than a predefined threshold value, said energy peak is assumed to correspond to a radiofrequency signal transmitted by a terminal 20 , and the center frequency of this radio frequency signal is estimated.
• the inverse physical layer processing then comprises a step E5 of frequency translation during which the digital signal is reduced, as a function of the central frequency estimated at the detection step E4, around a substantially zero central frequency so to obtain a so-called "baseband" signal.
• the inverse physical layer treatment then comprises a step E6 demodulation, during which the symbol demodulation is performed.
• the baseband signal is formed by a series of symbols (for example BPSK, DBPSK, QPSK, 16QAM, etc.) which represent the binary data transmitted by the terminal 20.
• the conversion of this series of symbols into data binary is performed during the demodulation step E6.
• the binary data obtained after the demodulation step E6 are equal to the binary data transmitted by the terminal 20.
• filtering can be performed to reduce the power of radio frequency signals outside the multiplexing band.
• an Automatic Gain Control AGC
• the baseband signal can be filtered and downsampled to reduce the amount of information to be processed during the demodulation step E6.
• other operations can be performed, such as in particular an estimate of the propagation channel, an estimate of a frequency drift likely to affect the baseband signal, a channel decoding, etc.
• a first distribution example (separation line P1) consists in assigning the steps E1 for radiofrequency processing and E2 for analog / digital conversion to the first inverse processing module 310. and assigning all subsequent steps to the second inverse processing module 320.
• a second nonlimiting example of distribution (separation line P2) consists in assigning all the steps of the inverse processing to the first module inverse processing 310 with the exception of the demodulation step E6 which is assigned to the second inverse processing module 320.
• Such a distribution makes it possible to reduce the quantity of intermediate data to be transferred, in particular when the baseband signal is filtered and downsampled.
• the first inverse processing module 310 always performs at least one analog / digital conversion step, so that the intermediate data are digital data.
• the partial stations 31 require less computing power than complete stations 34.
• These partial stations 31 will be connected to one or more processing servers 32 which, although requiring a greater computing power, will be less numerous than the partial stations.
• the centralization of a part of the physical layer inverse processing operations will make it possible, in certain cases, to exploit, for the same terminal 20, the radio frequency signals received by partial stations. remote, and thus improve the quality of the propagation channel by introducing spatial diversity in reception.
• FIG. 4 represents a preferred mode of implementation of a digital telecommunications method 50 according to the invention.
• the situation is not limited to the case where the radio frequency signal transmitted by the terminal 20 is received by two partial stations 31a and 31b.
• Each partial station 31a, 31b then executes step 520 of intermediate data formation from the radio frequency signal that said partial station 31a, 31b received, as well as step 521a of emission of step 521 intermediate data transfer.
• the processing server
• the training step 520 comprises inserting, into the intermediate data transferred to the processing server 32, an identification code specific to said partial station having formed said intermediate data.
• the processing server 32 can determine directly from received intermediate data which of said intermediate data are received from different partial stations 31a, 31b.
• the identification code can take any form allowing the processing server 32 to separate the intermediate data received from partial stations 31 a, 31 b different.
• the identification code of a partial station 31 corresponds to information on the position of said partial station 31a, 31b, such as the GPS coordinates ("Global Positioning System") of said partial station. .
• GPS coordinates GPS coordinates
• Such an identification code then enables the processing server 32 to determine which partial stations 31a, 31b are close and are therefore likely to receive radio-frequency signals transmitted by the same terminal 20.
• step 520 method of training includes inserting, into the intermediate data transferred to the processing server 32, data relating to one or more characteristics of the radio frequency signal from which said intermediate data is formed, called "signal identification data".
• the processing server 32 can directly determine from intermediate data received from different partial stations which of said intermediate data is likely to correspond to received radio frequency signals. a single terminal 20.
• radiofrequency signal may, however, allow or facilitate the identification, at the level of the processing server 32, of intermediate data that may correspond to radiofrequency signals transmitted by the same terminal 20.
• these characteristics of the radiofrequency signal will generally be no longer available in the intermediate data (for example the center frequency of the radio frequency signal is no longer available if the intermediate data correspond to a baseband signal).
• the insertion, in the intermediate data, of identification data corresponding to estimated characteristics of the radio frequency signal thus enables the processing server 32 to have information facilitating the identification of intermediate data corresponding to radio signals emitted by the same terminal 20. Without the insertion of identification data, this information could not usually be more be obtained by said processing server.
• the intermediate data forming step 520 may include estimating the center frequency of the received radio frequency signal and inserting that estimate as data of signal identification, in the intermediate data formed.
• the intermediate data whose estimated central frequencies will be substantially equal may be considered as likely to correspond to radiofrequency signals transmitted by the same terminal 20.
• the step 520 of intermediate data formation may comprise the estimation of the reception time of the radio frequency signal and insert this estimate, as signal identification data, in the intermediate data formed.
• the intermediate data whose estimated reception times will be substantially equal may be considered as likely to correspond to radiofrequency signals transmitted by the same terminal 20.
• step 520 of intermediate data formation may comprise the spreading code estimate used in the received radio frequency signal and insert this estimate, as signal identification data, into the formed intermediate data.
• the intermediate data whose estimated spreading codes will be equal may be considered as likely to correspond to radiofrequency signals transmitted by the same terminal 20.
• the processing server 32 able to separate the intermediate data received of different partial stations and, among these intermediate data, to identify which are likely to correspond to radio frequency signals received from the same terminal 20. Therefore, since the processing server 32 performs the final operations of the physical layer protocol, in particular the symbol demodulation, said processing server will be able to exploit the reception spatial diversity offered by the different partial stations 31 a , 31 b.
• the spatial diversity exploited by the invention is a "spatial macro-diversity" in the sense that the partial stations 31a, 31b (and consequently the reception antennas of said partial stations) are located in zones different geographical areas.
• said partial stations 31a, 31b may be spaced a few hundred meters or more apart, so that the propagation channels between a terminal 20 and each of said partial stations will generally be statistically independent.
• the spatial micro-diversity exploited by the telecommunications system 10 according to the invention is to be distinguished from the "spatial micro-diversity" exploited nowadays in certain digital telecommunications systems.
• the spatial micro-diversity consists in equipping the same base station with several collocated reception antennas. It is understood that because said receiving antennas are collocated, it is difficult to strongly distance them, so that the propagation channels between a terminal and each of the receiving antennas of the same base station will generally be correlated.
• the processing server 32 preferably performs a combination of intermediate data received from different partial stations 31a, 31b and identified as corresponding to radio frequency signals received from the same terminal 20.
• This combination can be carried out according to any known combination method in the field of the exploitation of spatial micro-diversity in reception. For example, this combination can be performed so as to maximize the signal-to-noise ratio, such a combination being known as Maximum Ratio Combining (MRC).
• MRC Maximum Ratio Combining
• the processing server 32 performs a selection of intermediate data among the intermediate data received from partial stations 31a, 31b different and identified as corresponding to radio frequency signals received from the same terminal 20.
• This selection can be made following any known method of selection in the field of the exploitation of spatial micro-diversity in reception. For example it is possible to select the intermediate data which have the best signal-to-noise ratio.
• the training step 520 preferably comprises the insertion, in the intermediate data transferred to the processing server 32, of at least one parameter representative of a report. signal on noise of the radiofrequency signal.
• the processing server 32 then performs the combination or the selection of the intermediate data received according to said parameters included in said intermediate data.
• the parameter inserted in the intermediate data corresponds to an estimation of the signal-to-noise ratio, to an estimate of the propagation channel, to an estimation of the reception power, to the gain applied following the automatic gain control (AGC), etc.
• AGC automatic gain control
• the formatting of the intermediate data of the partial stations 31a, 31b is carried out according to a predefined physical intra-layer communication protocol.
• the intermediate data formed from a radio frequency signal can be organized into several messages transmitted on a transfer channel between a partial station 31a, 31b and the processing server 32.
• the messages transmitted can take the following form.
• a first message of initialization of the transfer channel is possibly emitted by the partial station 31 a, 31 b, with a format of the type [Id Fi SNR], in which:
• - Id is the identification code of said partial station
• - Fi the initial center frequency of the radiofrequency signal
• - SNR is the signal-to-noise ratio of the radiofrequency signal.
• the partial station 31a, 31b transmits a message with a format of the type [Id Tn Fi Fcn n Xn Yn], in which:
• n is the index of the symbol transmitted in this message
• Tn is the moment of reception of the symbol of index n
• Fcn is the central frequency of the radio frequency signal at time Tn
• - Xn and Yn are the coordinates of the index symbol n in the complex plane (constellation).
• the insertion of the current central frequency Fcn is advantageous especially in the case where the frequency drift of the radio frequency signals emitted by a terminal 20 is important. This will occur in particular in narrow-band telecommunications systems, for example of the order of a few Hertz to a few hundred Hertz, in which the terminals 20 are equipped with inexpensive frequency synthesis means, whose frequency drift may be greater to the bandwidth of said system.
• the insertion of the initial central frequency Fi in each message allows the processing server 32 to identify consecutive messages as corresponding to the same radio frequency signal. Indeed, the initial center frequency Fi is invariant, while the center frequency Fcn can vary from one message to another if the frequency drift is important.
• the transfer of the intermediate data to the processing server 32 can be effected by means of different communication protocols for which the partial stations 31 a, 31 b and the processing server 32 are assigned specific addresses.
• the intermediate data are encapsulated in IP (Internet Protocol) datagrams, and the processing server 32 distinguishes the intermediate data received from different partial stations 31 a, 31 b as a function of the IP addresses of said partial stations.
• IP Internet Protocol
• the processing server 32 may use an identifier of the terminal 20 inserted in the upper protocol layers (MAC addresses, IP, etc.).
• the distribution of the physical layer inverse processing operations between a partial station and a processing server makes it possible to have less complex partial stations.
• the centralization of certain physical layer inverse processing operations (in particular symbol demodulation) at said processing server makes it possible to improve the performance of the digital telecommunications system by exploiting a spatial macro-diversity offered by partial stations. located in different geographical areas.

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