FR2789248A1 - Management of information transmission by radio includes selection from various carrier and modulation methods according to received signal quality - Google Patents

Abstract

The system includes selection from available services in response to detected quality of signal in speed and error rate. The procedure provides management of information transmitted by radio between a base station and at least one peripheral station, with communication by modulation of carriers with the information. The procedure uses a number of carriers and modulations offering different routes by which the information may be transmitted. A decision stage (G2) is incorporated in which the chosen route is selected in response to a required quality of service in terms of data error rate and data flow rate for a given information transmission. The number of carriers and the modulation applies varies according to the quality of service required.

Description

The present invention relates to a method and a device for managing

  transmission of information in a communication network comprising a base station and at least one peripheral station communicating therewith said information, in particular by transmission of several

  carriers modulated by the information.

  Document FR 2 660 131 discloses a method and a device for transmitting digital data over a communication channel based on an orthogonal frequency division multiplexing modulation technique, called OFDM (for Orthogonal Frequency Division).

  Multiplex ", in English terminology).

  This method assumes that digital data from different sources needs different levels of transmission error protection from one source to another,

type of information considered.

  The method proposes, for a data carrier group of an OFDM symbol, to select an appropriate type of modulation and coding efficiency according to the disturbances affecting the data channel.

  communication and the required level of protection.

  In the case, for example, where it is desired that data from two sources are transmitted simultaneously on a radio communication channel, the device proposed in this document allocates a group of carriers given to each of the sources and selects a type of modulation and a

  coding efficiencies appropriate for each of the groups.

  When this technique involves increasing the coding efficiency or decreasing the modulation level, for a data source, in order to enhance the protection against transmission errors, this will result in a decrease in the useful data transmission rate. on the communication channel. However, in certain applications of the real-time type, such as the transmission of video or audio data or data used for videoconferencing, it is essential to guarantee a data rate.

  constant, the rate of transmission error may vary.

  Another document, US 5,726,978, discloses a carrier allocation method applied to frequency multiplexing modulation.

Orthogonal (OFDM).

  When transmitting information between a base station and several peripheral stations in a network, this method recommends dynamically allocating transmissions between the base station and

  a peripheral station a group of carriers of an OFDM symbol.

  Based on the results of measurements of the noise level and the reception quality of the OFDM symbols transmitted over the communication channel, the base station decides to replace some of the carriers which, for example, give rise to data transmissions affected.

  an error rate too high, by other carriers less affected by noise.

  This method proposes above all to guarantee an error rate of

  low transmission between the base station and the peripheral stations.

  In view of the above, the Applicant has found that it would be interesting to find a method and an information transmission management device that can easily adapt to the different requests from communication stations in a network and requiring a quality of services determined, in terms of transmission error rate and rate to be transmitted, and allowing, for example, to satisfy requests for which the transmission error rate must be low and o, simultaneously,

  the useful data rate to be transmitted must remain substantially constant.

  The present invention aims to solve this problem and thus proposes a method for managing the transmission of information by radio between a so-called base station SB, SB 'and at least one so-called peripheral station SPi, SP', i = 1, .. , N, communicating information therewith by carrier transmission modulated by said information, said method comprising a step of allocating a number of carriers and a modulation to at least one radio communication channel assigned to the transmission of information between said base station and said at least one peripheral station, characterized in that said method comprises a step of determining a number of adapted carriers and modulation in response to a required quality of service, in terms of transmission error rate and transmission rate, for a given transmission of information between said base station and said at least one peripheral station, the number of carriers and the

  adapted modulation differing according to the qualities of services required.

  Thus, the invention makes it possible to guarantee for a given transmission of information over a radio communication channel, a quality of services in terms of the desired transmission error rate and transmission rate, by choosing an appropriate pair consisting of a number of

carriers and modulation.

  This is particularly important in type applications

  real time (video data transmission) or file transfer type.

  When a transmission of information on the communication channel requires a quality of services (in terms of transmission error rate and transmission rate) different from that allocated for the previous transmission of information, the invention provides to adapt for this transmission of information the number of carriers and the modulation guaranteeing this

new quality of services.

  It should be noted that the transmission error rate can be interpreted in different ways: it can thus for example correspond to a transmitted bit error rate or to the number of data frames.

video or audio transmitted.

  In the case of a transmission using a technique known as OFDM orthogonal frequency multiplex modulation, the transmission error rate may be, for example, the error rate on the

number of transmitted OFDM symbols.

  Advantageously, the qualities of services required are also expressed in terms of the threshold of the transmission error rate and the transmission rate variation acceptable for said transmission of information.

given.

  The decision to reconfigure the transmission parameters (number of carriers, modulation) is simplified because of the presence

  a transmission error rate threshold.

  On the other hand, accepting that the transmission rate can vary within a range instead of requiring a single value limits the number of possibilities for reconfiguring the transmission and transmission parameters.

  ability to terminate transmission in the event of failure to meet this criterion.

  According to one particular characteristic, the step of determining carriers and a modulation is performed during an information transmission between the base station and at least one peripheral station, which is of particular interest when the transmission conditions are met. real

  of the communication channel vary during the transmission of information

  same, for example due to a displacement of the peripheral station.

  It should be noted, however, that the determination step may

  also be performed between two transmissions of information.

  In addition, it is interesting to be able to perform this determination step both before a new transmission of information, to adapt to a new quality of services required, that in transmission, to ensure that this quality of services is well respected,

  even if the conditions of transmission vary.

  According to another particularly advantageous characteristic, the method comprises a step of receiving at least one measurement of the transmission error rate on the radio communication channel assigned to the transmission of information between the base station and at least one station. peripheral. This error rate is measured globally for the transmission between the base station and at least one peripheral station, and is subsequently taken into account for the step of determining a number of

  suitable carriers and modulation.

  It should be noted that the step of receiving at least one measurement of the transmission error rate can be carried out before or after the step of determining a number of carriers and a modulation adapted to a transmission rate.

quality of service required.

  According to a particular characteristic, after the step of receiving said at least one measurement, the method comprises a step of analyzing said at least one measurement of the transmission error rate and comparing the result of this analysis with the quality. of services required in terms of debit

  transmission and transmission error rate.

  According to one characteristic, the method comprises a step of determining a number of carriers and a modulation adapted according to the result of the measurement, if the result of this analysis does not respect

  the quality of services required for the said transmission.

  According to a particular characteristic, the method comprises a step of determining a number of carriers to be allocated which is different from that which has been previously allocated to said at least one communication channel between

  the base station and the peripheral station.

  The number of carriers determined to allocate to said at least one communication channel between the base station and the peripheral station may therefore be greater than that previously allocated to this communication channel, for example, to guarantee a quality of services requested in the case a

  application of the real-time type o the transmission rate must remain constant.

  According to another particular characteristic which can be combined with the particular characteristic mentioned above, the method also comprises a step of determining a modulation to be allocated to said at least one communication channel between the base station and the peripheral station which is different from the one previously allocated. Thus, in the case where the number of carriers determined is greater than that previously allocated to guarantee a quality of services requested (for example, in the case of an application of the real-time type where the transmission rate must remain constant, if, in addition, the communication channel is very noisy and if the requested quality of services requires a low transmission error rate, it is also possible to reconfigure the modulation in order to

make it more robust.

  The number of carriers determined to allocate to said at least one communication channel between the base station and the peripheral station may also be less than that previously allocated to this channel.

  communication in the case where the communication channel becomes less noisy.

  Thus, the carriers that are no longer used for this communication channel, because of the reconfiguration, can be assigned to another

  communication channel requiring an additional number of carriers.

  According to another particular characteristic which can be combined with the characteristic according to which the determined number of carriers is smaller than that previously allocated to the at least one communication channel between the base station and the peripheral station, the method also comprises a step of determining a modulation to allocate that is different from that

previously allocated.

  Thus, in the case where the number of reconfigured carriers is less than previously allocated, to guarantee a quality of services requested for this transmission, and o this quality of services also requires to guarantee a constant transmission rate, it is also possible to reconfigure the

  modulation to make it less robust.

  According to another advantageous characteristic, the method comprises, on the one hand, a step of determining a number of carriers to be allocated to a first communication channel between the base station and a first peripheral station which is greater than that which has has previously been allocated to this first communication channel and, secondly, a step of determining a number of carriers to be allocated to a second communication channel between the base station and a second peripheral station, which is less than that which has previously been allocated to this second communication channel, in response to qualities of service required respectively for the transmission of information on these communication channels, in terms of error rate of

  transmission and transmission rate.

  Thus, the step of determining a different number of carriers may result from a compromise between two communication channels, depending on the quality of services required for the transmission of information on each of them, insofar as the two communication channels do not simultaneously require a higher number of carriers than the one

previously performed.

  Advantageously, the transmission by modulated carriers uses a

  OFDM orthogonal frequency multiplexing modulation technique.

  This technique has a spectral efficiency expressed in bits per Hertz which

  is superior to other modulation techniques.

  Moreover, this technique is an effective way to combat the effects of multiple propagation and fainting (called

  "fadding" in Anglosaxon terminology).

  This technique allows to distribute the fading effects

  frequency-selective transmission channel over a number of sub-

  which have constant fading corresponding to the

  carrier frequencies of the OFDM multiplex.

  According to another aspect, the invention relates to a method of transmitting information on a radio communication channel comprising steps of assigning a number of carriers and a modulation to said information for the transmission thereof on said radio communication channel and transmission of said information in the form of carriers modulated by said information, characterized in that said method comprises a step of reconfiguration of the number of carriers and the modulation allocated to the information according to a quality of services required, in terms of transmission error rate and transmission rate for a given information transmission, the number of carriers and modulation reconfigured

  differing according to the qualities of services required.

  The step of reconfiguring the number of carriers and the modulation allocated to a given transmission of information is carried out

  to adapt to the quality of services required.

  According to yet another aspect, the invention relates to a method for receiving information from a radio communication channel, comprising a step of receiving said information transmitted in the form of carriers modulated by said information and a step of selecting the carriers. and modulation allocated to said information, characterized in that it comprises a step of reconfiguration of the number of carriers and the modulation to be selected according to a quality of services required, in terms of transmission error rate and transmission rate for a given information transmission, the number of carriers and the modulation reconfigured

  differing according to the qualities of services required.

  According to one particular characteristic, the method according to the invention comprises a step of producing at least one measurement of the transmission error rate on the radio communication channel allocated to the transmission.

information considered.

  Advantageously, the result of this measurement provides information on the real conditions of the transmission in progress and thus makes it possible to reconfigure the number of carriers and the modulation assigned to this transmission in the case where the quality of services requested is not

respected.

  It is therefore possible to constantly monitor the actual conditions of the transmission in progress and consequently to adapt the number of carriers and the modulation. Correlatively to the management method, the invention relates to a radio information transmission management device between a so-called base station SB and at least one so-called peripheral station SP1, i = 1, ..., N, communicating information with it by transmission of carriers modulated by said information, said device comprising means for allocating a number of carriers and a modulation to at least one radio communication channel assigned to the transmission of information between said station base station and said at least one peripheral station, characterized in that said device comprises means for determining a number of carriers and a modulation adapted in response to required qualities of services, in terms of error rate of transmission and transmission rate for a given information transmission between said base station and said at least one peripheral station, the number of carriers and the adapted modulation differing according to the qualities of services required Thus, in response to a quality of services requested, either by a peripheral station or by the base station itself, the transmission management device according to the invention determines the number of carriers and the modulation that it is necessary to allocate to a transmission of information

  given to guarantee this quality of services.

  Correlatively to the transmission method, the invention also relates to an information transmission device on a radio communication channel, comprising means for assigning a number of carriers and a modulation to said information for the transmission of data. these on said radio communication channel, and means for transmitting said information in the form of carriers modulated by said information, characterized in that said device comprises means for reconfiguring the number of carriers and the modulation allocated to the information depending on a quality of service required, in terms of transmission error rate and transmission rate for a given information transmission, the number of carriers and modulation reconfigured differ according to the quality of services required. Correlatively to the reception method, the invention relates to a device for receiving information from a radio communication channel, comprising means for receiving said information transmitted in the form of carriers modulated by said information and selection means. carriers and modulation allocated to said information, characterized in that said device comprises means for reconfiguring the number of carriers and the modulation to be selected according to a quality of services required, in terms of transmission error rate and transmission rate for a given information transmission, the number of carriers and modulation reconfigured differing according to the quality of services required. The subject of the invention is also a base station able to communicate by radio information with at least one peripheral station, characterized in that said base station comprises a device for managing radio information transmissions such that

briefly outlined above.

  According to a particular characteristic, the base station comprises a transmitting device and a receiving device such as briefly exposed

upper.

  It should be noted that the management system may include the

  transmission device and the receiving device mentioned above.

  The invention relates to a peripheral station able to communicate by radio information with a so-called base station, characterized in that said peripheral station comprises a transmission device and a device for

  radio reception as briefly described above.

  The invention also relates to a network comprising a

  base and at least one peripheral station as expressed above.

  The base station and the peripheral stations may comprise a computer, a printer, a server, a fax machine, a scanner, a digital camera, a digital camera, a television, a video recorder or a decoder (called "set top box" in Anglosaxon terminology). The invention also provides a means for storing information that can be read by a computer or a processor containing instructions of a computer program, characterized in that it allows the implementation of

  least one of the management, transmission and reception processes described

above.

  The invention is further directed to a computer-readable information storage means or a processor containing data from the implementation of at least one of the transmission management, transmission and transmission methods.

  and reception as briefly outlined above.

  The advantages and characteristics specific to the transmission and reception processes, to the management, transmission and reception devices, to the base station, to the peripheral stations and to the network, and to the means for storing information being the same as those described above

  concerning the management method according to the invention, they are not recalled here.

  Other features and advantages of the invention will appear at

  course of the following description given only as an example

  illustrative and not limiting, and with reference to the accompanying drawings in which: - Figure 1 is a general view of a network according to the invention comprising a base station SB and a plurality of peripheral stations SPi; FIG. 2 is a schematic view of a peripheral station SP1 according to a first embodiment of the invention; FIG. 3 is a schematic view of a base station SB according to a first embodiment of the invention; FIG. 4 is a detailed schematic view of the transmission block 40 shown in FIG. 2; FIG. 5 is a detailed schematic view of the carrier modulation circuit 82 shown in FIG. 4; FIG. 6 is a representation of the binary data 00, 01, 11, in the Fresnel plane; FIG. 7 is a detailed schematic view of the carrier allocation circuit 84 shown in FIG. 4; Figure 8 is a detailed schematic view of the receiving block 72 shown in Figure 2; Fig. 9 is a detailed schematic view of the carrier selection circuit 126 shown in Fig. 8; FIG. 10 is a detailed schematic view of the carrier demodulation circuit 128 shown in FIG. 8; FIG. 11 is a schematic view showing the base station SB and the peripheral station SP1 according to the invention; FIG. 12 is an algorithm representing the various steps of the information transmission method according to the invention; FIG. 13 is an algorithm representing the various steps of the information transmission management method according to the invention; FIG. 14 is an algorithm representing the different steps of the information reception method according to the invention; FIG. 15 is a schematic view of a peripheral station SP'1 according to a second embodiment of the invention; FIG. 16 is a schematic view of a base station SB 'according to a second embodiment of the invention; and - Figure 17 is a schematic representation of an OFDM symbol. In the example below, we will use a decomposable matrix following the Cooley-Tuckey algorithm, which allows a presentation

  easily understandable reasoning.

  As a preliminary to the description of the invention, we recall here

  some elements relating to the conventional method of calculating the transform of

  Discrete Fourier, with examples in base 4.

  A discrete Fourier transform can be represented by the multiplication of a complex vector U by a matrix, which corresponds to obtaining a series of linear combinations of the components of the vector.

initial complex.

  If we have W = exp (-j27t / n), with n the number of components of the complex vector of the discrete Fourier Transform (also denoted TFD), j the root of -1, then the operation of TFD can be represented by the equation: Xo I ... xo Xl IW W2 ... wriT-l

X2 W 1 I W2- 4 .. W (X2

  Xn - I l o <-)? (it ...) W (n-I) (> i - Q I) A 1-i We define in a general way the so-called Fourier matrix of order n by the matrix

1 I 1 ...

  ............. DTD: wM = - I V W: (,, -,) ... W ("i-I ') -

  1 [1 W "'l 2" -' W'-X-I The inverse Fourier transform is obtained by replacing W with

W '= exp (j2i / n).

  If n is a power of 4, this transform can be divided into four groups of four multiplications of a vector by a matrix according to the following form (according to the Cooley-Tuckey algorithm):

W'ex --- 2 -----

  Xo + k n 14 XO Xl x2 X3 Xl + k, '/ 4 X4 X5 X6 X7 11 X2 + k' 4 = aDoT x8 + bkD IX97 + ckD2T x io + dkD3T xIi

  . .......... DTD: XKi 14 - I + k 'n t4 X4 (1 14-1) X - 3 X - 2 Xn-

  for k = 1, 2, 3; with the coefficients ak, bk, ck, dk equal to the coefficients of the matrix ao bo co do [1 i I i b bl cl di -j -1 of Fourier of dimension 4, that is to say a2 b2 C2 d2 = 1 a3 b3 c3 d3 I j -1 -j T is the Fourier matrix of dimension n / 4 and Do, Dl, D2, D3 are diagonal matrices consisting of elements Wt with 0 <I <n / 4 -1, depending on the form:

  Di = wi I, and Do being an identity matrix.

  ...... DTD: O oow (n1 / 4-1) i Therefore, if the components of a complex vector to be transmitted (associated with the data of a sequence of data representative of physical quantities) are taken in a alphabet {1 + j, 1-j, -1-j, -1 + j}, there is no multiplication during the transmission of complex symbols by the so-called OFDM method in the operations to be performed, and only additions or

  sign changes, which simplifies the implementation of such a method.

  As represented in FIG. 1 and designated by the general reference denoted 10, a network according to the invention consists of a station called base station SB and several peripheral stations SP ,, with i = 1 to N. These peripheral stations SP, are distant from the base station SB, each connected by radio with it and likely to move

compared to the latter.

  The base station SB communicates, with the peripheral station SP, by means of the upstream radio link 12 and the downlink radio link 14, with the peripheral station SP2 by means of the upstream radio link 16 and the downlink radio link 18 and with the peripheral station SP, by means of the uplink radio link 1 N and the downlink radio link 2N. The transmissions 12, 14, 16, 18, ..., I1N and 2N are done via radio interfaces installed in each station and channels of

  communication allocated to these transmissions.

  The block diagram of FIG. 2 represents a more detailed view of a first embodiment of a peripheral station, for example of the

  SP station ", which comprises a data source 20 and a device 22.

  In general, the device 22 is a transmission device and

  receiving information according to the invention.

  This information is intended to be transmitted over a radio communication channel, in the form of carriers modulated by said information. The data source 20 is for example a digital camera, a computer, a printer, a server, a fax machine, a scanner, a digital camera, a digital camera, a television, a

VCR or a decoder.

  This transmission and reception device 22 comprises a data processing unit 24 comprising a computing unit 26 denoted UC, a temporary data storage means 28 (RAM memory), a permanent storage means 30 (ROM memory), a bus interface 32 and a bus 34

  which connects the data source 20 to said interface.

  The transmission and reception device 22 comprises a bus 36 serving the computing unit 26, the storage means 28 and 30 and an interface

modem 38.

  The transmitting and receiving device 22 further comprises an information transmission block 40 and an information receiving block 42, and

  a radio module 44 to which said blocks 40 and 42 are connected.

  The radio module 44 is equipped with a radio antenna 46. The radio module and the antenna constitute, on the one hand, with the transmission unit 40 of the transmission means and, on the other hand, with the block of reception 42 of the information receiving means. For its part, the base station SB comprises, as represented in FIG. 3, a data source 50 and a transmission and reception device

  52 according to a first embodiment of the invention.

  This information transmission and reception device 52 comprises a data processing unit 54 comprising a computing unit 56 denoted UC, a means for temporarily storing the data 58 (RAM memory), a permanent storage means 60 (memory ROM), a bus interface 62 and

  a bus 64 which connects the data source 50 to said interface.

  The transmission / reception device 52 also comprises a bus 66 serving the computing unit 56, the storage means 58 and 60 and an interface

modem 68.

  The transmitting / receiving device 52 further comprises an information transmission block 70 and an information receiving block 72, as well as a radio module 76 to which said blocks 70 and 72 are connected. The radio module and the antenna form, on the one hand, with the transmission block 70 of the transmitting means and, on the other hand, with the reception block 72 of the information receiving means. The data source 50 is, for example, a digital camera, a computer, a printer, a server, a fax machine, a scanner, a digital camera or a digital camera, a television, a

VCR or a decoder.

  The transmit and receive blocks 70 and 70 are respectively identical to the transmit block 40 and the receive block 42 of the station

SP device, from Figure 2.

  We will now describe in more detail the emission blocks 40 and

  receiving 72 with reference to Figures 4 to 10.

  The information transmission block 40 shown in FIG. 4 comprises an encoder 80 and means for assigning to said information a number of carriers and a modulation. These carrier allocation and modulation means consist, in part, of a carrier modulation circuit 82 and, in part, of a carrier allocation circuit 84. This transmission block 40 comprises moreover, means 86 for reconfiguring the number of carriers and the modulation allocated to the

information to be transmitted.

  These means 86 consist, in part, of a circuit 88 for reconfiguring the number of carriers and, in part, a circuit 90 for reconfiguring the modulation. The implementation and conditions of

  reconfiguration are explained later.

  The transmission block 40 also comprises a circuit implementing a fast inverse Fourier transform (IFFT) 92 and a frequency multiplexer

(MUX) 94.

  When the transmission block 40 is in operation, a set of successive information J, coming from the data source 20, are

  stored in RAM 28 (fig.2).

  This information can be processed in the unit UC 26, and for example undergo a compression operation or addition of a code of

cyclic redundancy.

  The information in the RAM 28 that has possibly been processed is first divided into data sequences S,

for example of the binary type.

  Each sequence S is sent to the modem interface 38, then to the transmission block 40 where the binary data streams, represented by the reference 102 in FIG. 4, are first coded in the circuit 80 and represented by the reference 104, and then are injected into the carrier modulation circuit 82, also called the mapping circuit.

Anglo-Saxon terminology).

  In this circuit, the data streams 104 are then grouped in R bits according to the modulation chosen, and then transformed into complex numbers, according to a

  encoding alphabet otherwise stored.

  The set of n complex numbers form a complex vector U identified by the reference denoted 106 in FIG. 4 and which is then delivered to

circuit 84.

  In the example described here, R is for example equal to two.

  As shown in FIG. 5, the modulation circuit 82 more particularly comprises a block 98 for serial / parallel conversion of the

incoming data.

  This block delivers as output blocks of bits intended for a correspondence block denoted 100. The correspondence block 100 comprises tables containing stored complex numbers and corresponds to a block of R

  bits to a given complex number according to the selected modulation.

  The complex vectors U resulting from the circuit 82 are for example represented in the Fresnel plane in I and Q coordinates as indicated in FIG. 6, according to a QPSK type mapping signal with phase modulation.

  quaternary ("Quaternary Phase Shift Keying" in Anglosaxon terminology).

  The binary data pairs 00, 01, 11 and 10 shown in FIG. 6 are respectively associated with the complex numbers 1 + j, -1 + j, -1-j, 1-j, which are called MAQ symbols, for Modulation of Amplitude in Quadrature (denoted "QAM" in Anglo-Saxon terminology for "Quadrature Amplitude Modulation") and which are represented by the reference

106 in Figure 4.

  It should be noted that the modulation applied in the circuit 82 may take different forms: BPSK ("Binary Phase Shift Keying"), QPSK, 8PSK, 16QAM, 32QAM, 64QAM ...

  depending on the choice that is applied.

  In general, the size and the number n of complex numbers from the circuit 82 depend on the modulation (type of modulation and level) and the number of allocated carriers. Such an attribution will be described

  in more detail in the rest of the presentation.

  Returning to the example described with reference to FIG. 4, during a transmission, the complex numbers forming a complex vector 106 are transferred into the carrier allocation circuit 84 which is represented more

detail in Figure 7.

  Thus, in this figure, the carrier allocation circuit 84 somewhat functions as a switch and matches a complex number to a selected input of the circuit 92 which performs a Fourier transform.

fast reverse (IFFT).

  Different complex numbers are therefore assigned to entries e ,, i = 0 ,. ., n determined from the circuit 92 as a function of the information of the number of selected carriers for the transmission of information and the numbers of the inputs of the circuit 92 corresponding to the selected carriers, information

  which are determined elsewhere, as will be seen later.

  Thus, at the input of the circuit (IFFT) 92, a complex vector V is obtained in which each component represented by the reference 108 in FIG.

  corresponds to a selected carrier, modulated by a complex number.

  This circuit performs the multiplication of each complex vector V by the Fourier matrix M mentioned at the beginning of the presentation to obtain the transformed vector Y. This transformed vector Y consists of n complex numbers

  represented by reference 110 in FIG. 4.

  The complex numbers 110 generated at the output of the circuit (IFFT) 92 are then multiplexed by the circuit (MUX) 94 to create a signal 112 comprising all the multiplexed carriers, each carrier carrying the data contained in a number of the group of numbers The signal 112 thus forms what is called an OFDM symbol. This signal is then modulated by a radio carrier at a not shown modulator, included in the radio module 44 of Figure 2, for its transposed band transmission on the radio communication channel considered. We will now describe in more detail the reception block 72 of the

  base station SB with reference to Figures 8 to 10.

  The reception block 72 comprises a frequency demultiplexer (DEMUX) 122, a Fast Fourier Transform (FFT) circuit 124, carrier selection and modulation means allocated to the information transmitted over the radio communication channel. These selection means consist, in part, of a carrier selection circuit 126

  and, in part, a carrier demodulation circuit 128 (FIG. 8).

  The reception block 72 also comprises means for

  reconfiguration of the number of carriers and the modulation to be selected.

  These reconfiguration means consist, in part, of a circuit 130 for reconfiguring the number of carriers to be selected and, in part? a circuit 132 for reconfiguring the modulation to be selected. The

  implementation and the reconfiguration conditions are explained later.

  The reception block 72 further comprises a decoder 134 of the coded data and measurement means 136 of the transmission error rate.

  on the radio communication channel considered.

  The reconfiguration means 130, 132 and the measuring means

  136 form a block 138 called the receiver control block.

  When the reception block 72 is in operation, the radio signal is received from the radio communication channel by the antenna 46 and is for example

  filtered in the radio module 44 of Figure 2.

  The filtered signal undergoes an automatic gain control thereby reducing the amplitude of said signal to a predetermined level, which is acceptable so that the

  reception block 72 can operate.

  The signal is thus amplified because of the strong attenuations that it could

  during transmission on the communication channel.

  The power of the amplified signal is then measured and compared to a reference power. If the amplified and measured power does not correspond to this reference power, the gain of the amplifier is adjusted by

  circuits not shown but which are known to those skilled in the art.

  The signal is demodulated in the radio module 44 by the radio carrier

  used during modulation on the transmission of the signal.

  The signal represented by the reference 140 in FIG. 8 is then transmitted to the reception block 72, demultiplexed at the demultiplexer (DEMUX) 122, in order to obtain a group of samples 142 of the signal containing the group of carriers modulated by the complex numbers and forming a

Y 'complex column vector.

  A Fast Fourier Transform (FFT) is then applied by the (FFT) circuit 124 to the samples 142 to obtain the signals 144 containing the symbol modulated carriers. The calculation of the direct fast Fourier transform consists in multiplying the matrix M ', inverse of the matrix M mentioned above, by the vector Y' to obtain a vector consisting of n

  complex numbers each modulating a carrier.

  It should be noted that matrices M and M 'verify the relation MM' =

  Id, where Id denotes the identity matrix.

  When the matrix M corresponds to an inverse Fourier transform, the matrix M 'corresponds to a direct Fourier transform, but it

  Note, however, that the order of the matrices can be reversed.

  According to a variant not shown, the matrices M and M 'verifying the

  relation MM '= Id are matrices of Hadamard.

  The different outputs of the circuit (FFT) 124 are connected to different inputs of the carrier selection circuit 126 (FIG. 9). This circuit 126 selects, among the different circuit outputs (FFT) 124, the carriers that have been used for the transmission of complex numbers or new carriers more suited to the transmission of information considered, and provides, as output, said numbers. complex 146 in parallel. These complex numbers form the approximate complex vector Z. The selection circuit 126 acts as a sort of switch. Each of the n complex numbers corresponds to a point in the plane

  Fresnel which is shown in Figure 6.

The signals 146 consisting of the complex numbers are then supplied to the demodulation circuit 128 to generate the encoded digital data sequence 148. As shown in FIG. 10, the demodulation circuit 128 more particularly comprises a correspondence block 150 which comprises tables containing binary data grouped in blocks of bits with a

  block size corresponding to the modulation (type and level) chosen.

  Thus, this block 150 receives, as input, complex numbers 146, for example 1 + j, -1 + j, -1 -j, 1 -j, and makes them respectively correspond to the pairs of binary data 00, 01, 11 and 10 (FIG. 6) since the QPSK modulation has

  was chosen, as we saw above, during the broadcast.

  In order to obtain this correspondence, it is planned to make a decision step as to the position in the Fresnel plane of the points of said complex approximated vector Z with respect to the points of the coding alphabet used during transmission, and which are those forming the complex vector U, associated with

  information that may have been issued.

  The decision step is performed according to a criterion that takes into account the minimum value of the Euclidean distance between each point obtained for the approximate vector Z and those corresponding to the vector U. When the Euclidean distance calculated between one of the points obtained for the approximate vector Z and one of the points of the alphabet is minimal, we

  deduce that the point that may have emitted is that of the alphabet.

  The decision step can also be performed according to a decision of maximum likelihood on a set of symbols, by the use of a Hamming distance or a Euclidean distance and a

Viterbi algorithm.

  Thus, the complex numbers are each associated with a point of the coding alphabet used on transmission and provide the data sequences

binaries that have been transmitted.

  The reconfiguration means 132 can modify the modulation

  applied as will be seen later.

  The pairs of binary data identified by the reference 152 in FIG. 10 are sent in parallel to a block 154 which performs the parallel / serial conversion of said data and delivers to the decoder 134 the data 148. The reconfiguration means 132 also act on the block conversion 154 by providing the number R mentioned above and following

  which the binary data is grouped.

  The sequences S of data coming from the decoder 134 of FIG. 8 are then stored in the RAM memory 28 of FIG.

the CPU unit 26.

  It should be noted that the transmission of symbol modulated carriers, which has been described here, relates to a transmission of symbols by

  a modulation technique known as OFDM.

  However, other types of symbol-modulated carrier transmission may also be suitable, such as, for example, a radio transmission technique known as AMDF for Frequency Division Multiple Access (denoted "FDMA" in Anglosaxon terminology for "). Frequency Division Multiple Access ") or a spreading technique of

spectrum by frequency hopping.

  FIG. 11 represents the peripheral station SP, and the base station SB communicating information to each other by means of the link

  ascending 12 and descending link 14.

  The peripheral station SP is in all respects identical to that shown in FIG. 2. The base station SB contains all the elements indicated in FIG. 3, but their arrangement has been somewhat modified to

  reveal new elements.

  The reference 52 of the device for transmitting and receiving information has disappeared to reveal the reference 170 which corresponds to a radio information transmission management device between the base station and the

  peripheral station SP, according to the invention.

  This transmission management device 170 includes the transmission and reception device 52 of FIG. 3, but this device has not been reproduced.

not to complicate the scheme.

  This transmission management device 170 comprises, as shown in FIG. 11, and inserted between the transmission blocks 70 and the reception blocks.

  72, a transmission management block noted 172.

  When the peripheral station SP1 wishes to communicate information to the base station SB on the radio channel in question, it first sends a request specifying a quality of service desired for the

  forwarding of information.

  This desired quality of service specifies the desired transmission error rate and transmission rate for the transmission.

  information considered between the base station and the peripheral station.

  The transmission management device 170 comprises, on the one hand, means for receiving this request which consist of the antenna 78, the radio module 76 and the reception block 72 and, on the other hand, a block of 172. This transmission management device 170 also comprises means for receiving at least one measurement of the transmission error rate for a given transmission of information, a measure which has been

  performed by the means denoted 136 in FIG. 8.

  The management block 172 comprises means, denoted 174, for determining a number of adapted carriers and modulation in response to the quality of services required, in terms of transmission error rate and transmission rate, for a given information transmission. It should be noted that this number of carriers and this modulation vary according to different qualities of services required on the same channel of

  radio communication and for different transmissions of information.

  These determination means 174 communicate bidirectionally, as shown in FIG. 11 by two arrows, with the

receiving block 72.

  The means 174 determine the number of carriers and the modulation adapted to a service quality request, with a view to their allocation to the channel.

  of radio communication assigned to the transmission of information considered.

  These determination means 174 communicate with the transmission block 70 to transmit to the peripheral station SP1 the parameters of

  which is the number of carriers and the modulation.

  These transmission parameters are also transmitted to the block of

  receiving 72 of the base station SB.

  The management block 172 furthermore comprises means 176 for, on the one hand, analyzing the measurement of the transmission error rate that has been received by the measurement means 136 of the reception block 72 and transmitted to said block 176, and on the other hand, to compare the result of this analysis with the quality of services required, in terms of transmission rate and error rate of

desired transmission.

  The result of this comparison is transmitted to the means of

determination 174.

  It should be noted that means 174 for determining the number of carriers and the modulation adapted to an information transmission are implemented before the transmission of information in question occurs. However, as will be seen later, these determination means can also be implemented during transmission.

information itself.

  More specifically, the quality of services required for a given transmission of information is expressed in terms of acceptable transmission error rate threshold and transmission rate variation threshold.

  for said information transmission.

  Thus, for transmission of information, which is similar to the transmission of files, the transmission rate can vary to a large extent while the acceptable error rate should be as low as possible and

do not vary.

  On the other hand, for applications of the real-time type, the transmission rate must be as constant as possible whereas the error rate

can vary.

  The invention provides for adapting to each quality of services required which, as we have just seen, can be very different from one transmission of information to another, a given couple consisting of a number of carriers and

modulation.

  The methods of transmitting, transmitting and receiving according to the invention will now be described with reference to the

  respective algorithms of Figures 12 to 14.

  As represented in FIG. 12, the transmission method according to the invention comprises a step denoted E1 during which the peripheral station SP transmits to the base station SB a request for

  transmission with which a quality of service is associated.

  This quality of service specifies the transmission rate and the acceptable transmission error rate for the given information transmission

  between the peripheral station SP1 and the base station SB.

  As we have just seen, the quality of services also specifies the threshold of the transmission error rate and the variation of the transmission rate.

  acceptable for the transmission of information considered.

  As shown in FIG. 13, the method for managing radio transmissions between the peripheral station SP1 and the base station SB, according to the invention, comprises a step denoted G, during which the transmission management device 170 of FIG. the base station SB receives from the peripheral station SP1 the request for transmission as well as the demand for the quality

associated services.

  The transmission management device 170 determines, thanks to the means 174, the transmission parameters (number of carriers and modulation) adapted to the quality of services required, in terms of transmission error rate and transmission rate for the transmission. information considered. This step of determining the parameters of the transmission is

  performed, during the step denoted G2 of the management method according to the invention.

  When this determination step is performed, the transmission parameters, namely the number of carriers and the modulation, which are allocated to the transmission considered, are transmitted (step G3) by the management block 172, on the one hand, to receiving block 72 and secondly, to the transmission block 70 in

  view of the transmission of these parameters to the peripheral station SP1.

  According to step R1 of the reception method according to the invention, whose algorithm is shown in FIG. 14, the reception block 72

  receives the transmission parameters thus determined.

  Returning to FIG. 8 which details the reception block 72 of the base station, it can be seen that the parameters of the transmission which have been determined are directed towards the two blocks 130 and 132. The number of carriers which has been allocated to the communication station considered, given the quality of services required, is transmitted to the means 130 for reconfiguring the number of

carriers.

  The modulation adapted to the transmission considered, taking into account the quality of service required for it, is transmitted to the means 132 of

reconfiguration of the modulation.

  Consider, for example, that the Fourier transform operation performed in block 124 (FIG. 8) outputs 1512 points and considers that the transmission management device and, more precisely, the determination means 174, a indicate that, given the quality of service required, it is necessary to have 501 carriers and, secondly,

  identify the 501 useful outputs of the FFT circuit 124.

  Thus, in the example under consideration, out of the 1512 exit points of the circuit 124, only 501 have a significant value and the means 130 perform a reconfiguration of the number of carriers by selecting the 501 useful outputs.

of circuit 124.

  Likewise, the information concerning the modulation adapted to the transmission under consideration enables the means 132 to reconfigure the modulation applied to the future complex symbols 146, on the one hand, by selecting the adapted correspondence table and, on the other hand, by acting on the series 154 parallel conversion block by supplying the block with the number

  R according to which the binary data must be grouped.

  When the reception block 72 of the base station has been reconfigured according to these transmission parameters, according to the step R2 of the reception method according to the invention, said reception block transmits a

  reconfiguration confirmation message at the management block 172.

  On the side of the peripheral station SP ", the transmission parameters transmitted on the downlink denoted by 14 in FIG. 11 are distributed, on the one hand, to the reception block 42, on the other hand, to the transmission block

  via the modem interface 38.

  As shown in FIG. 4, the transmission parameters are intended, on the one hand, for the means of reconfiguration 90 of the modulation to be assigned to the transmission of information, and on the other hand by means of the means of configuring 88 of the number of carriers. to be attributed to the transmission of information. Depending on the modulation parameters received (modulation type and level), the reconfiguration means 90 act on the parallel serial conversion block 98 by providing it with the number R according to which the binary data must be grouped and select in the block 100 the table of

  match adapted to the modulation considered.

  According to the transmission parameters received from the management device 172, namely the number of carriers and the number of the carriers to be considered, the reconfiguration means 88 match the complex symbols 106 (FIG. 7) to the numbers of the inputs e, i = 0 to n, of circuit 92

  (IFFT) that have been provided by the management arrangement 170.

  The reconfiguration means 88 somehow switch the complex symbols 106 on the inputs corresponding to the carriers

appropriate circuit 92 (IFFT).

  When the transmission block 40 of the peripheral station SP1 receives the transmission parameters determined by the management device 170 of the base station SB, according to the step E2 of the transmission method according to the invention, and when the step of reconfiguration according to these parameters has taken place (step E3), the peripheral station SP1 sends a confirmation message of

  reconfiguration to the management device 170.

  The transmission management method according to the invention comprises a step G4 of receiving confirmation messages of reconfiguration in

  from the reception block 72 and the peripheral station SP ,.

  According to step G5 of the same method, the transmission management device according to the invention sends an authorization message.

  of the transmission to the reception block 72 and the peripheral station SP ,.

  According to step E4 of the method, the algorithm of which is represented in FIG. 12, the transmission block 40 of the station SP1 receives the

  transmission authorization message from the management device 170.

  The peripheral station SP1 proceeds then to the emission

  information according to the adapted transmission parameters (step E5).

  In the case where the transmission of information between the SP1 station and the

  SB station terminates, then step G6 is followed by step G7 (Figure 13).

  In the opposite case, the means 136 represented in FIG. 8 measure the error rate of the current information transmission and transmit the result of this measurement to the block 176 represented in FIG. 11 (step R4 of FIG. 14). . According to step G., block 176 receives this measurement of

error rate.

  In accordance with step G9, block 176 analyzes the measurement of the error rate of the current information transmission and compares the result of this analysis with the quality of services required, in terms of bit rate.

  transmission and transmission error rate.

  If the result of this analysis does not respect the quality of services required for the transmission of information considered, then the parameters of

  transmission must be modified again.

  In this case, step G, 0 is followed by steps G2 to G5 previously described. The transmission management device according to the invention, noted, therefore determines new transmission parameters (number of carriers and modulation) and transmits them to the reception block 72 and to the station

SP device ,.

  The peripheral station SP receives from the transmission management device a message for reconfiguring the parameters of the transmission in progress (step E6). In this case, the steps E3 to E5 of the transmission process are

again realized.

  In parallel, the reception block 72 receives the message reconfiguring the parameters of the transmission in progress (step R5) and the

  previously described steps R2 to R4 are performed again.

  Since it is determined that the parameters of the current transmission must not be modified (step Gl0) then the step R5 is followed by the step R6 (FIG. 14) during which a test is carried out for

  to know if the reception block 72 receives a transmission end.

  If the transmission is not complete, then the steps previously

  described R3 and R4 are realized again.

  As a result, on the side of the transmission management method according to the invention, the step Gl0 is followed by the steps G8 and G9, which are also carried out on the basis of a new measurement of the transmission error rate.

  performed by the reception block 72.

  This measurement of the error rate of the transmission in progress and the corresponding adaptation of the number of carriers and the modulation in order to satisfy the criteria of the requested quality of service are realized in

  permanence during the transmission of information considered.

  Returning to FIG. 12, when no message for reconfiguring the parameters of the transmission in progress is received from the management device, then step E6 is followed by step E7 in which a test is performed for to know if the transmission block 40 of the peripheral station SP requests a transmission end. If an end of transmission is not requested, then step E7 is

followed by steps Es and E6.

  On the other hand, if the transmission block requests an end of transmission, then the step E7 is followed by the step E8 during which the peripheral station SP transmits an end-of-transmission message by means of the ascending radio link. to the transmission management device according to the invention 170. The reception block 72 also receives the end of message message.

  transmission and step R6 is followed by step R7 terminating the transmission.

  Step G6 performs a test on the end of transmission and is followed in

  this case of step G7 terminating said transmission.

  The peripheral communication station SP ', represented in FIG.

  relates to a second embodiment of the invention.

  In this figure, all the elements that remain unchanged in relation to

  those of Figure 2 are included and retain the same references.

  The peripheral station SP 'comprises a data source 20 and

  an information transmitting and receiving device 200.

  This transmission / reception device 200 comprises a data processing unit 202 which comprises a central unit denoted UC referenced 26, a bus interface 32 and a bus 34 which connects the data source 20 to said interface 32, the unit data processing device 202 also comprises a modem interface 38, a temporary data storage means (RAM memory) 204 and a permanent storage means (memory

ROM) noted 206.

  The transmission and reception device 200 also comprises an information transmission block 208 connected to a radio module 44 which is equipped with

an antenna 46.

  The transmission and reception device 200 also comprises a block

  receiver 210 connected to the radio module 44 and a modem interface 38.

  As shown in FIG. 15, the bus interface 32, the central unit 26, the modem interface 38 and the storage means 204 and 206 are all connected by a bus 36. In this embodiment, the functions of the transmission and reception methods according to the invention are carried out by means of computer programs respectively denoted by Progr E and Progr R. The program which makes it possible to implement the transmission method according to the invention is placed in a noted memory zone 206a storage means 206. The instructions of this computer program correspond

  in steps E1 to E8 of the algorithm shown in FIG.

  The program which makes it possible to implement the information reception method according to the invention is placed in a memory zone denoted 206b of the

storage medium 206.

  The instructions in this computer program correspond to the

  steps R1 to R7 of the algorithm shown in FIG.

  In this embodiment, the transmit and receive blocks 208 and 208 have the same elements as the transmit (FIG. 4) and receive (FIG. 8) blocks, with the exception of the respective blocks (FIG. 4) and 138

  (Figure 8) which are not included in said blocks 208 and 210.

  Indeed, the functionalities implemented in these blocks are now carried out by the respective computer programs ProgrE and ProgrR. The storage means 204 comprises several registers 204a to 204f which contain various variables used during the execution of the instructions.

  instructions of the previously mentioned computer programs.

  Thus, the register 204a contains a variable called number of carriers and noted NSP. The register 204b contains a variable called modulation and denoted Mod. The register 204c contains a variable called transmission error rate and denoted TE. The register 204d contains a variable called bandwidth (also corresponds to the transmission rate) and denoted BW. The 204th register contains a variable called quality of services and

noted QoS.

  The register 204f contains a variable called measure, denoted Mes, and which corresponds to the result of the measurement of the error rate of a transmission in

course, performed in block 210.

  The variables TE, BW and QoS are used during the step E1 of the computer program Progr E. The transmission parameters noted NSP and MoD are used during the steps E2, E3 and E6 of the computer program Progr E and during the steps R, and R2 of the Progr R. computer program. Fig. 16 illustrates a second embodiment of a basic communication station SB 'according to the invention. This station has a source

  50 and a transmission management device 212.

  This transmission management device 212 also provides the transmission and reception functions. The transmission management device 212 comprises a data processing unit 214 which comprises a central unit denoted UC and referenced 56, a bus interface 62 and a bus 64 which connects the data source 50 to said bus interface, an interface modem denoted 68, a means of temporary storage of data (RAM memory) noted

  220 and a permanent storage means (ROM memory) noted 222.

  A bus 66 connects the central unit 56, the bus interface 62, the interface

  modem 68 and the storage means 220 and 222.

  The transmission management device according to a second embodiment of the invention also comprises a transmission block 224 connected to

  a radio module 76 which is equipped with an antenna 78.

  The transmission block 224 is also connected to the modem interface 68.

  The transmission management device 212 also comprises a reception block 226 which is, on the one hand, connected to the radio module 76 and on the other hand

at the modem interface 68.

  In this embodiment, the functionalities of the transmission and reception management method according to the invention are realized by means of computer programs denoted by Progr G and Progr R. The permanent storage means 222 comprises two memory zones denoted 222a and 222b which respectively contain the programs Progr G and Progr R. The instructions of the program Progr G correspond to the steps G.

  Gl0 the algorithm shown in Figure 13.

  The Progr R program instructions correspond to steps R.

  to R7 of the algorithm shown in Figure 14.

  The temporary data storage means 220 comprises several registers denoted 220a to 220f each containing a different variable which is used during the execution of the various instructions of the

  previously mentioned computer programs.

  The variables noted NSP, Mod, TE, BW, QoS and Mes are the same as those described with reference to FIG. 15 and are therefore not further explained here. These variables are respectively contained in the

  registers 220a to 220f temporary data storage means 220.

  The variables TE, BW and QoS are used during the step G1 of the program Progr G. The variables noted NSP, Mod are used during the steps G2 and G3 of the program Progr G. The first variables cited TE, BW and QoS are also used in step G9 of this same program. The variable is

  used in steps G8 and Gg.

  The transmission parameters represented by the NSP and Mod variables are used during the step R1 of the computer program Progr R. The variable Mes is used during the step R4 of the computer program Progr R. It should be noted that the transmission blocks 224 and the reception blocks 226 of the base station SB 'are identical to the blocks 40 and 72 shown respectively in FIGS. 4 and 8, with the exception of the blocks 86 and 138 which do not

are not taken back.

  Indeed, the features provided by these blocks are now

  performed by computer programs.

  The permanent storage means also comprises a memory zone denoted 222c which contains a computer program Progr E of setting

  implementation of the emission method according to the invention.

  The instructions of this program correspond to the steps E1 to E8 represented on the algorithm of FIG. 12. The variables contained in the registers 220c, 220d, 220e are used during the step E1 of the program Progr E. The variables contained in FIG. the registers 220a and 220b are used during the steps E2, E3 and E6 of the computer program Progr E. According to a variant not shown, the functionalities of the transmit and receive blocks 224 and 226 of the base station SB 'are realized by one or more computer programs stored in memory areas of the

storage medium 222.

  In order to illustrate the possible choices of reconfiguration of the modulation and the number of carriers to guarantee a given quality of services, we will take as an example the parameters of the OFDM modulation which follow and which are: - number of carriers = 1512 or 6048 useful carriers, - 3 modulation levels: 4QAM, 16QAM, 64QAM, - 3 coding ratios: 1/2; 213; 314; 516; 7/8,

  - guard time: 1/4, 1/8, 1/16, 1/32 of the duration of the OFDM symbols.

  The encoding ratio is defined as the ratio between the number of useful information and the number of redundancy information added by the encoding to make the transmission of information more reliable. A coding ratio of 3/4 means that we have three useful information for information

redundancy.

  The guard time defines, in turn, the time interval separating

  two consecutive transmissions of OFDM symbols.

  By modifying all these parameters, different possible overall rates are obtained. Thus, if the coding ratio is fixed at 7/8 and the guard time at 1/32, the following overall rates are obtained as a function of the QAM modulation level used: - 4 QAM -> 10 , 56 Mbit / s (all carriers are used) - 16QAM - 21.11 Mbit / s (all carriers are used) - 64QAM - 31.67 Mbit / s (all carriers are used) Therefore, with 1512 carriers useful, if we want to assign to a transmission of information a useful bit rate of 3.5 Mbit / s, we have the following three solutions: Solution Payload Modulation Number of carriers 1 3,499 Mbit / s 4QAM 501 2 3,504 Mbit / s s 16QAM 251 3 3,497 Mbit / s 64QAM 167 with the payload, which is expressed as:

  payload = (overall rate / 1512) x number of allocated carriers.

  Solution 1 uses a very robust 4QAM modulation that can guarantee a transmission with a low error rate, but in return

  one third (501/1512) of carriers will be required.

  Solution 2 uses a less robust 16QAM modulation but does not

  requires only one sixth of the carriers.

  Solution 3 uses a ninth of the carriers with modulation

not robust.

  To guarantee the bit rate of 3.5 Mbit / s, the management device 170 or 212

  according to the invention therefore has the choice between these three solutions.

  Its choice is made according to the allowable error rate for the

transmission considered.

  This error rate is related to the quality of services required with the

request for transmission.

  One would think that solution 1 will always be the most

  interesting regardless of the quality of services requested.

  However, since the function of the management device according to the invention is to use radio resources as efficiently as possible, it would be detrimental in terms of managing radio resources to use solution 1 while the

  common transmission conditions allow you to choose the solution 3.

  It is easily understood that if the solution 3 is chosen for all the peripheral stations SPi communicating with the base station SB, it will be possible to have simultaneously nine transmissions with each a bit rate of 3.5 Mbits / s, while the Solution 1 would only allow three transmissions. When the radio resources of a network become limited, the management device 170 or 172 according to the invention will have to make compromises between the transmission parameters determined for a given transmission of information and what it can actually offer. These compromises

  depend on the qualities of services required.

For example:

  - quality of service A defines a fluctuation of the required payload

  +/- 20% and a bit error rate threshold transmitted of 10%.

  A quality of service B defines a fluctuation of the required throughput of

  +/- 5% and bit error rate threshold transmitted from 10-5.

  A quality of service C defines a fluctuation of the required payload of

  +/- 30% and a transmitted bit error rate threshold of 10-.

  A quality of service D defines a fluctuation of the required throughput of

  +/- 1% and bit error rate threshold transmitted from 10-8.

  Suppose now, for example, that the peripheral stations SP, and SP2 of Figure 1 have required the same bit rate and the same error rate threshold and are arranged at different distances from the station.

SB base.

  For example, the peripheral station SP, is closer to the station

basic as the SP2 station.

  The transmission of information between SP and SB can then use

  a weak modulation (ex: 64 QAM) and a reduced number of carriers.

  On the other hand, the transmission of information between SP2 and SB, because of the distance which separates them, will have, on the one hand, to use a very robust modulation (4QAM) to obtain a rate of error equivalent to that of the transmission between SP, and SB and, on the other hand, require a number of carriers

  very much higher than that assigned to said transmission between SP, and SB.

  If the management device according to the invention can not allocate the sufficient number of carriers, the rate of transmission of information between

SP2 and SB will be decreased.

  If this bit rate falls below the minimum bit rate tolerated by the quality of services requested by the station SP2, the management device will have to reduce the number of carriers allocated to the transmission of information between SP and SB in order to

  to satisfy the transmission between SP2 and SB.

  This example shows the important role played by the

  management in the optimal management of the radio resources of a network.

  In another example, the peripheral stations SP, and SP2 of FIG. 1 do not require the same quality of services, the quality of services required by SP1 requiring a number of carriers much greater than that of

requested by SP2.

  In such a case, the compromise established by the management device according to the invention is simple since the carriers not used for the transmission of information between SP2 and SB are assigned to the transmission of information.

between SP1 and SB.

  It should also be noted that in addition to the service qualities required for transmissions of information between the peripheral stations SP ,, i = 1, ..., N, and the base station SB, priorities can be assigned to these transmissions of information depending for example on the nature of the

  information to be transmitted and the applications envisaged.

* According to this possibility, if one of the transmissions of information between a peripheral station, for example SP1 and the base station SB is assigned a higher priority to the transmissions between the other peripheral stations and the base station SB, and if this same transmission requires, because of its required quality of services, a higher number of carriers than previously allocated, then, whatever the quality of services required for the other transmissions, the necessary number of carriers will be taken

  on one or more of these other transmissions.

  It may also be provided that the number of carriers required to transmit the highest priority information is taken from the

  transmission of information of the lowest priority.

  By way of example, FIG. 17 represents an ODFM symbol of 1512 carriers distributed over three information transmissions between SP ", SP2, SP3 and SB. The transmission between SP1 and SB is carried out with a bit rate of 3.5

  Mbits / s for a carrier number of 167 and 64QAM modulation.

  The transmission between SP2 and SB is performed with a bitrate of

  3.5 Mbit / s for a carrier number of 501 and 4QAM modulation.

  Transmission between SP3 and SB is performed with a bit rate of

  500 Kbps for a carrier count of 72 and 4QAM modulation.

  Thus, of the 1512 carriers, 772 are not used for the three transmissions of information considered but may be affected later if the required qualities and / or conditions of transmission on

  the communication channels are modified.

Claims (64)

  1. A method for managing the transmission of information by radio between a so-called base station SB, SB 'and at least one so-called peripheral station SPi, SP'j, i = 1, ..., N, communicating information with that by transmission of carriers modulated by said information, said method comprising a step of allocating (G3) a number of carriers and a modulation to at least one radio communication channel assigned to the transmission of information between said base station and said at least one peripheral station, characterized in that said method comprises a step of determining (G2) a number of adapted carriers and modulation in response to a quality of services required in terms of the rate of transmission and transmission rate error for a given information transmission between said base station and said at least one peripheral station, the number of adapted carriers and modulation differing according to the bedridden services required.   2. Method according to claim 1, characterized in that the required service qualities are also expressed in terms of the threshold of the transmission error rate and of the variation of the acceptable transmission rate.   for said given information transmission.   3. Method according to claim 1 or 2, characterized in that the step of determining (G2) carriers and a modulation is performed during a transmission of information between the base station and the at least one a peripheral station.   4. Method according to claim 1 or 2, characterized in that the step of determining (G2) carriers and a modulation is performed between two transmissions of information between the base station and the at least one a peripheral station.   5. Method according to one of claims 1 to 4, characterized in that   it comprises a step of receiving (G8) at least one measurement of the transmission error rate on the radio communication channel assigned to the transmission of information between the base station and the at least one peripheral station. 6. Method according to claim 5, characterized in that, after the step of receiving (G8) said at least one measurement, said method comprises a step (Gg) of analyzing said at least one measurement of the rate of transmission error and comparison of the result of this analysis with the quality of services required in terms of transmission rate and transmission error rate. 7. Method according to claim 6, characterized in that it comprises a step of determining (G2) a number of adapted carriers and modulation if the result of this analysis does not respect the quality of services. required for said transmission.   8. Method according to one of claims 1 to 7, characterized in that   it comprises a step of determining (G2) a number of carriers to be allocated which is different from that previously allocated to said at least one communication channel between the base station and the at least one peripheral station. 9. Method according to claim 8, characterized in that the number of carriers to be allocated to said at least one communication channel between the base station and the at least one peripheral station is greater than that   previously allocated to this communication channel.   10. Method according to claim 8, characterized in that the number of carriers to allocate to said at least one communication channel between the base station and the at least one peripheral station is less than that   previously allocated to this communication channel.   11. The method of claim 8, characterized in that it comprises, on the one hand, a step of determining (G2) a number of carriers to allocate to a first communication channel between the base station and a first peripheral station which is higher than the one previously allocated to this first communication channel and, secondly, a step of determining (G2) a number of carriers to be allocated to a second communication channel between the station of base and a second peripheral station which is lower than that previously allocated to this second communication channel, in response to qualities of services required respectively for the transmission of information on these communication channels in terms of error rate transmission and transmission rate.   12. Method according to one of claims 1 to 11, characterized in that   that said method also comprises a step of determining (G2) a modulation to be allocated to said at least one communication channel between the base station and the at least one peripheral station which is different from that previously allocated.   13. Method according to one of claims 1 to 12, characterized in that   that transmission by modulated carriers uses a modulation technique   by OFDM orthogonal frequency multiplexing.   14. A method of transmitting information on a radio communication channel comprising steps of assigning a number of carriers and a modulation to said information for transmission thereof on said radio communication channel and transmission (Es) of said information in the form of carriers modulated by said information, characterized in that said method comprises a step of reconfiguration (E3) of the number of carriers and the modulation allocated to the information according to a quality of services required in terms of transmission error rate and transmission rate for a given information transmission, the number of carriers and the   reconfigured modulation differing according to the quality of services required.   15. Method according to claim 14, characterized in that the required service qualities are also expressed in terms of the threshold of the transmission error rate and the transmission rate variation.   acceptable for said given information transmission.   Method according to claim 14 or 15, characterized in that the step of reconfiguring (E3) the number of carriers and the modulation is   performed during an information transmission.   17. Method according to claim 14 or 15, characterized in that the step of reconfiguring (E3) the number of carriers and the modulation is   performed between two transmissions of information.   18. Method according to one of claims 14 to 17, characterized in that   that, prior to the step of reconfiguring (E3) the number of carriers and the modulation, said method comprises a step of transmitting (E1) a request for allocation of a quality of services in terms of bit rate. transmission and transmission error rate for a given information transmission.   19. Method according to one of claims 14 to 18, characterized in that   that the number of reconfigured carriers is different from the number of carriers previously assigned.   20. The method of claim 19, characterized in that the number of reconfigured carriers is greater than the number of carriers previously assigned.   21. The method of claim 19, characterized in that the number of reconfigured carriers is less than the number of carriers previously assigned.   22. Method according to one of claims 14 to 21, characterized in that   that the reconfigured modulation is different from that previously assigned.   23. Method according to one of claims 14 to 22, characterized in that   that transmission by modulated carriers uses a modulation technique   by orthogonal frequency multiplexing.   24. A method of receiving information from a radio communication channel, comprising a step of receiving (R3) said information transmitted in the form of carriers modulated by said information and a step of selecting the carriers and the modulation allocated to said information, characterized in that it comprises a step of reconfiguration (R2) of the number of carriers and the modulation to be selected according to a quality of services required in terms of transmission error rate and transmission rate for a given transmission of information, the number of carriers and the modulation reconfigured differing according to qualities of services required.   25. The method as claimed in claim 24, characterized in that the required service qualities are also expressed in terms of the threshold of the transmission error rate and of the transmission rate variation.   acceptable for said given information transmission.   26. The method according to claim 24 or 25, characterized in that the step of reconfiguring (R2) the number of carriers and the modulation is   performed during an information transmission.   Method according to claim 24 or 25, characterized in that the step of reconfiguring (R2) the number of carriers and the modulation is   performed between two transmissions of information.   28. Method according to one of claims 24 to 27, characterized in that   said method comprises a step (R4) of performing at least one measurement of the transmission error rate on the radio communication channel assigned to the   transmission of information considered.   29. Method according to one of claims 24 to 28, characterized in that   that the number of reconfigured carriers is different from the number of carriers previously assigned.   30. The method as claimed in claim 29, characterized in that the number of reconfigured carriers is greater than the number of carriers. previously assigned.   31. The method of claim 29, characterized in that the number of reconfigured carriers is less than the number of carriers previously assigned.   32. Method according to one of claims 24 to 31, characterized in that   that the reconfigured modulation is different from that previously assigned.   33. Method according to one of claims 24 to 32, characterized in that   that transmission by modulated carriers uses a modulation technique   by orthogonal frequency multiplexing.   34. Device (170; 212) for managing radio information transmissions between a so-called base station SB and at least one so-called peripheral station SPi, i = 1,..., N, communicating information with it by transmission carriers modulated by said information, said device comprising means for allocating (174; 222a, G3) a number of carriers and modulating at least one radio communication channel assigned to the transmission of information between said base station and said at least one peripheral station, characterized in that said device comprises means for determining (174; 222a, G2) a number of adapted carriers and modulation in response to required qualities of service, in terms of transmission error rate and transmission rate, for a given information transmission between said base station and said at least one peripheral station, the number of carriers and the modulation adapted tees differing according to the qualities of services required.   Apparatus according to claim 34, characterized in that the required service qualities are also expressed in terms of the threshold of the transmission error rate and the transmission rate variation.   acceptable for said given information transmission.   36. Device according to claim 34 or 35, characterized in that it comprises receiving means (78, 76, 72, 222a, G8) of at least one   measurement of the transmission error rate.   37. Device according to claim 36, characterized in that it comprises means (176; 222a, Gg) for analyzing said at least one measurement of the transmission error rate and comparing the result of this analysis with the quality of services required in terms of transmission rate and rate transmission error.   38. Device according to one of claims 34 to 37, characterized in   said device comprises means for determining (174; 222a, G2) a number of carriers to be allocated which is different from that previously allocated to said at least one communication channel between the station   base and the at least one peripheral station.   39. Device according to claim 38, characterized in that the number of carriers to be allocated to said at least one communication channel between the base station and the at least one peripheral station is greater than that   previously allocated to this communication channel.   40. Device according to claim 38, characterized in that the number of carriers allocated to said at least one communication channel between the base station and the at least one peripheral station is less than that   previously allocated to this communication channel.   41. Device according to claim 40, characterized in that it comprises, on the one hand, means for determining (174; 222a, G2) a number of carriers to be allocated to a first communication channel between the station of base and a first peripheral station which is higher than that previously allocated to this first communication channel and, secondly, means for determining (174; 222a, G2) a number of carriers to be allocated to a second communication channel between the base station and a second peripheral station which is less than that previously allocated to this second communication channel, in response to qualities of service required respectively for the transmission of information on these channels of communication; communication in terms of transmission error rate and throughput rate of transmission.   42. Device according to one of claims 34 to 41, characterized in   it also comprises means for determining (174; 222a, G2) a modulation to be allocated to said at least one communication channel between the base station and the at least one peripheral station which is different from that previously allocated.   43. Device according to one of claims 34 to 42, characterized in   what the modulated carrier transmission uses a technique of   modulation by multiplexing orthogonal frequencies.   44. An information transmission device (22, 52, 200, 212) on a radio communication channel, comprising means for allocating (82, 84) a number of carriers and modulating said information for transmitting them onto said radio communication channel, and transmitting means (22, 40, 44, 46; 52, 70, 76, 78, 206a, 222c, E4) of said information in the form of modulated carriers by said information, characterized in that said device comprises reconfiguration means (86, 88, 90, 206a, 222c, E3) of the number of carriers and the modulation allocated to the information as a function of a quality of services required, in terms of transmission error rate, and transmission rate for a given information transmission, the number of carriers and the modulation   reconfigured according to the quality of services required.   45. Device according to claim 44, characterized in that the required service qualities are also expressed in terms of the threshold of the transmission error rate and the transmission rate variation.   acceptable for said given information transmission.   46. Device according to claim 44 or 45, characterized in that the number of carriers reconfigured is different from the number of carriers previously assigned.   47. Device according to claim 46, characterized in that the   number of reconfigured carriers is higher than previously allocated.   48. Device according to claim 46, characterized in that the   number of reconfigured carriers is less than previously allocated.   49. Device according to one of claims 44 to 48, characterized in   that the reconfigured modulation is different from the previously assigned one.   50. Device according to one of claims 44 to 49, characterized in   what the modulated carrier transmission uses a technique of   modulation by multiplexing orthogonal frequencies.   51. A device (22; 52) for receiving information from a radio communication channel, comprising receiving means (22, 42, 44, 46; 52, 72, 76, 78; 206b, 222b, R3). said information transmitted in the form of carriers modulated by said information and means (126, 128) for selecting the carriers and the modulation allocated to said information, characterized in that said device comprises reconfiguration means (138, 130, 132, 206b, 222b, R2) of the number of carriers and the modulation to be selected according to a quality of service required, in terms of transmission error rate and transmission rate, for a given transmission of information, the number of Reconfigured carriers and modulation   differing according to the qualities of services required.   52. Device according to claim 51, characterized in that the required service qualities are also expressed in terms of the threshold of the transmission error rate and the transmission rate variation.   acceptable for said given information transmission.   53. Device according to claim 51 or 52, characterized in that it comprises measuring means (72, 136; 206b, 222b, R4) of the transmission error rate on the radio communication channel assigned to the transmission of the transmission channel. information.   54. Device according to one of claims 51 to 53, characterized in   the number of carriers reconfigured is different from the one that was previously assigned.   55. Device according to claim 54, characterized in that the   number of reconfigured carriers is higher than previously assigned.   Device according to claim 54, characterized in that the   number of reconfigured carriers is lower than previously assigned.   57. Device according to one of claims 51 to 56, characterized in   that the reconfigured modulation is different from that previously assigned.   58. Device according to one of claims 51 to 57, characterized in   what the modulated carrier transmission uses a technique of   modulation by multiplexing orthogonal frequencies.   59. Base station SB, SB ', able to communicate by radio information with at least one peripheral station SP, SP'i, i = 1, ..., N, characterized in that said base station comprises a device Management   radio information transmissions (170) according to one of the claims 34 to 43.   60. Base station SB, SB 'according to claim 59, characterized in that said base station comprises a device for transmitting information.   (52) on a radio communication channel according to one of claims 44 to 50   and a device (52) for receiving this information transmitted according to one of the Claims 51 to 58.   61. Base station SB, SB ', according to claim 59 or 60, characterized in that it comprises a computer, a printer, a server, a fax machine, a scanner, a digital camera, a camera   digital, a television, a video recorder or a decoder.   62. Peripheral station SP1, SP'1, i = 1, ..., N, able to communicate by radio information with a so-called base station, characterized in that said peripheral station comprises a device for transmitting information (22)   on a radio communication channel according to one of claims 44 to 50 and   a device (22) for receiving this information transmitted according to one of the Claims 51 to 58.   63. Peripheral station SP ,, SP ',, i = 1, ..., N, according to claim 62, characterized in that it comprises a computer, a printer, a server, a fax machine, a scanner, a camera digital device   digital camera, television, video recorder or decoder.   64. Network (10) characterized in that it comprises a base station   SB, SB 'according to one of claims 59 to 61 and at least one station   device SPi, SP'i, i = 1, ..., N, according to one of claims 62 to 63.