FR2942578A1 - Frame i.e. data frame, receiving method for e.g. home cinema type wireless audio and video distribution network, involves testing communication configuration between transmitting and receiving nodes during period of time - Google Patents

Abstract

The method involves estimating synchronization information of reception of data frames transmitted by a transmitting node. A receiving node is configured for receiving one of the frames from the estimated synchronization information. A communication configuration between the transmitting and receiving nodes is tested during a period of time corresponding to execution of synchronization operation. The period of time is added with available time to carry out communication configuration test between the nodes. Independent claims are also included for the following: (1) a computer programmable product downloadable from a communication network and/or recorded on a medium readable by a computer or executed by a processor, comprising a program code instructions for implementing a method for receiving frames with preamble in a communication network (2) a computer readable storage medium for storing a computer program comprising a set of instructions executed by a computer for implementing a method for receiving frames with preamble in a communication network (3) a receiving node of the frame with preamble in a communication network.

Description

Method of receiving frames with preamble, computer program product, storage means and corresponding node. FIELD OF THE INVENTION The field of the invention is that of communication systems, and more particularly millimeter radio wave communication systems, such as, for example, the wireless home network WPAN (Wireless Personal Area Network). , in English) using the 60GHz radio band. More specifically, the invention relates to a technique for receiving frames with a preamble in a wireless communication network implementing a time division multiplexing (TDM) transmission. 2. TECHNOLOGICAL BACKGROUND Wireless home video and audio applications are now more and more numerous and require higher and higher data rates, of the order of a few Gigabits per second, and high quality. more and more service. Millimeter WPAN type home networks are particularly well suited for this type of application. Indeed, the authorized band around a carrier frequency of 60 GHz offers a large bandwidth allowing the transport of a large amount of data. The radio range of such systems is also limited to about ten meters, favoring the spatial and temporal reuse of frequencies. The physical properties of the carrier frequency band around 60 GHz and the regulatory power limit of the transmitting devices (or nodes) currently limit the communications to a maximum of about ten meters.

In practice, these characteristics require that, to ensure a good level of radio communication quality and to obtain a sufficient radio range without having to transmit to unauthorized powers, the nodes of a wireless home network have configured antennas. in a directive (or selective) manner with a significant positive gain.

More particularly, this type of antennas, called smart antennas, makes it possible to reach the distances required by audio and video applications within home networks. An intelligent antenna consists of a network of radiating elements distributed in a matrix manner on a given support. This network allows the implementation of a technique of shaping antenna beams (technique called beamforming in English). According to this technique, each radiating element of the antenna is electronically controlled in phase and power (or gain) to obtain a beam transmitting and / or receiving directional and more or less narrow. The use of this type of antennas, when receiving a radio signal, makes it possible to increase the sensitivity of the antenna in reception in a desired direction and to reduce the sensitivity of this antenna for zones of interference. or strongly noisy.

The use of this type of antenna, when transmitting a radio signal, makes it possible to increase the power of the radio signal in a desired direction. In mesh-type communication networks (called MESH Network in English), when a node transmits a radio signal (transmission mode of operation), its intelligent antenna is set to transmit a broad-beam beam (radiation angle wide antenna), in order to reach a maximum number of receiver nodes. When a node receives a radio signal (reception mode of operation), its intelligent antenna is set to receive data at a narrow and steerable antenna angle, in order to increase the gain of the antenna and to direct it to the node transmitting the radio signal.

In receive operation mode, each receiving node points its receive antenna at an orientation angle suitable for receiving data from the transmitting node. At each new transmitting node, each receiving node must orient its receiving antenna according to a new orientation angle adapted to the position of the new transmitter node in the network.

The search for an optimum antenna orientation angle is a recurring technical problem in directionally configured antenna communication networks. In the case of a network where the exact positions of the devices are not reliably known, it is often necessary to perform an exhaustive scan of the antenna coverage area in reception, in order to select, an angle of Antenna orientation in optimal reception for a considered communication. The implementation of such an antenna scan is all the more necessary in WPAN home communication systems. Indeed, because of the short wavelengths used (millimeter waves), such communication systems have a high sensitivity to interference and masking phenomena. The disadvantage of such a method lies in the fact that it can not be implemented during a communication. Indeed, such a method forces the receiving nodes of the network to orient their receiving antenna and to scan in directions other than that which is necessary for the reception of useful data transmitted by a given sending node, which causes a loss of data. useful during this period of time.

The Time Division Multiple Access (TDMA) protocol is a multiplexing mode for transmitting multiple signals on a single communication channel. It is a time division multiplexing whose principle is based on a division of the time domain into access sequences (more commonly called TDM network cycles), each access sequence being divided into a plurality of time or time intervals. speech slots (called time slots in English), which are successively assigned to the different nodes of the network. Each node of the network can therefore in turn transmit data on the same radio communication channel, the other nodes then being either in an operating mode for receiving data, or in another mode of operation that does not disturb the communication channel. radio, such as in standby mode. A difficulty encountered in the implementation of wireless communication networks is to be able to perform synchronization operations by a receiving node. Indeed, a receiving node must be able to recover the synchronization signals it needs to interpret the data it receives.

Several synchronization methods have been developed in this direction. One of them is particularly well suited for high frequency bands and offers data rates of the order of a few tens or hundreds of megabits per second. The principle of this synchronization method is based on the insertion, into a header of data frames to be transmitted, of the predefined and known symbols of the receiving node. This method is already used, for example, in the IEEE 802.11a and Hiperlan 2 standards of the ETSI (European Telecommunications Standards Institute). It is also a potential synchronization method for the receiver nodes of Millimeter WPAN type communication networks that are being standardized (Wireless HD, IEEE 802.15.3c, ECMA). The data gathered at the beginning of a physical frame transmitted on the communication medium form a preamble (or header), commonly called a burst preamble in the ETSI Hiperlan2 standard, or PLCP preamble in the IEEE802.l standard and the project of ECMA standard TC48 / 2008/144. The aforementioned standards define in particular the content of the preamble necessary for the perfect synchronization of the receiving nodes. The structure of each of the receiving nodes according to these standards is suggested by the format of the transmitted frame, but this one is absolutely not defined. Indeed, the implementation of these receiver nodes remains free and various solutions exist. Various publications have also been used to develop these standards, as well as some documents of the state of the art which suggest various solutions for implementing synchronization operations prior to demodulation of the symbols received by the receiving nodes. The document entitled OFDM Wireless LANs: A Theoretical and Practical Guide (John Terry and Juha Heiskala, SAMS Publishing, 2002) reveals, particularly in the second chapter (entitled Synchronization, pages 48 to 83), several methods of implementation of synchronization operations in time and frequency, according to a technique based on OFDM (Orthogonal Frequency Division Multiplexing), such a technique being particularly well suited to the transmission channels used by the WLAN standards (for Wireless Local Area Network) .

More particularly, this document relates to the particular use of the preamble for the detection of data frames according to the IEEE 802.1 standard and the structure of this preamble. This one is composed of fields A, B and C, each one dedicated to the following operations of synchronization: - field A: automatic control of gain and coarse temporal synchronization; - field B; automatic gain control, fine time synchronization and estimation of the frequency error; - field C: transmission channel estimate. One of the main difficulties encountered when implementing a TDMA-based Millimeter WPAN communication network and directionally configured antennas is to be able to quickly and reliably determine antenna orientation angles. a transmitting node and a receiving node to ensure a continuous good quality of data communication between these nodes. The optimal pointing of an antenna in a given direction is generally difficult to maintain over time due to the short radio wavelengths used in these wireless communication systems. In fact, the slightest displacement of the nodes of the network or a variation of the pointing accuracy, due for example to a temperature drift or an aging of certain electronic components, can affect the quality of a radio communication. This problem is of particular concern in the case of certain transmissions, especially high-speed data streams (video applications for example), where the use of bandwidth to achieve optimal antenna pointing is undesirable. This problem is all the more worrying in the case where some receiver nodes use antennas configured in a directive manner whereas this was not planned during the implementation of the network (that is to say when development of the standard), in other words, in the case where no time slot given to the data frames has been provided for adjusting the pointing of these antennas. OBJECTIVES OF THE INVENTION The invention, in at least one embodiment, has the particular objective of overcoming these various disadvantages of the state of the art. More precisely, in at least one embodiment of the invention, one objective is to provide a technique for receiving frames with a preamble making it possible to test new communication configurations between two pieces of equipment, while ensuring the synchronization operations.

At least one embodiment of the invention also aims to provide such a technique for testing new communication configurations which does not require modification of the content of the frame and which ensures a constant communication of useful data. between the two equipments. A complementary objective of at least one embodiment of the invention is to provide such a technique for performing different types of testing of new configurations, in order to permanently ensure a good quality of data communication between these devices, and in particular: a readjustment of angular parameters of the receiving antenna; - a readjustment of the radio channel (frequency band) used by the equipment in communication. Another objective of at least one embodiment of the invention is to provide such a technique for minimizing energy consumption. Yet another object of at least one embodiment of the invention is to provide such a technique which is simple to implement and inexpensive. 4. DISCLOSURE OF THE INVENTION In a particular embodiment of the invention, there is provided a method of receiving at least one preamble frame in a communication network, the preamble being such that it corresponds to an interval time for at least one operation of synchronizing a reception, by a receiving node of the network, of at least one frame transmitted by a node transmitting the network. The receiving node performs steps of: - estimating at least one reception synchronization information for the reception of said given frame (s) transmitted (s) by the transmitting node; configuring the receiving node for receiving said at least one given frame from said at least one estimated synchronization information; testing at least one communication configuration between the sending node and the receiving node during a period of time intended for the execution of at least one synchronization operation, the result of which is estimated by the estimation step.

The general principle of the invention therefore consists in using all or part of a given time to a preamble of a given frame, initially intended to perform synchronization operations of a receiving node with a transmitting node of said given frame, to test new communication configurations between these nodes during the duration of the given frame. For example, this test of new configurations may make it possible to obtain additional synchronization information, which is not initially provided for in the time interval to which the preamble corresponds. In addition, this test of new configurations may make it possible to use systems with a short preamble, corresponding to a reduced time interval, enabling an alternating network (or frame) cycle to be carried out alternately. other, different synchronization operations. Thus, in this particular embodiment, the invention is based on a new and inventive approach of modifying the initial operation of a synchronization mode of the receiving node, using a mechanism for estimating information of synchronization, and to use the reception chain of the receiving node differently for a time usually intended to execute the synchronization operation for which the estimation has been applied released. Thus, by such optimization of the use of at least a portion of the preamble, additional time capital can be obtained to test communication configurations without disrupting the transfer of useful data between these nodes. As an illustrative example, the present invention is applicable to a wireless home communication system in which a receiving node, which needs to determine the information necessary to ensure good data communication quality, can modify the operation initial synchronization mode and use one or more time slots that are normally intended for the determination of synchronization parameters, to obtain additional time capital to test new communication configurations. More specifically, such a method may comprise the steps of: - storing a configuration adapted to receive said given frame; determining a start time of said available time; - testing, from the determined start time, at least one communication configuration for receiving data from the transmitting node; determining an end time of said available time; - Stop testing said at least one communication configuration from the determined end time and restore the stored configuration. According to an advantageous characteristic, the receiving node performs a step of: - adding, at a time available to perform at least one communication configuration test between the transmitting node and the receiving node during the reception of the preamble, said corresponding lapse of time at the execution of at least one synchronization operation whose result is estimated by the estimation step. It should be noted that it is more advantageous to release consecutive time intervals so as to limit the number of context changes (synchronization operation / communication configuration) and thus to benefit from more time to perform configuration tests. Communication. Thus, that the preamble corresponds to consecutive time intervals each allocated to perform a predefined reception synchronization operation, or that the preamble corresponds to a global time interval to perform a set of synchronization operations in predefined reception, a time can be released by estimating at least one synchronization information, in order to implement communication tests between the transmitter and receiver nodes. In the case where the preamble is such that it corresponds to a predefined sequence of sub-intervals of time each intended for a given synchronization operation, for each sub-time interval of a set comprising at least one sub-interval of time intended for the execution of at least one synchronization operation whose result is estimated by the estimation step, is added to said available time at least a part of said sub-time interval. This is the case, for example, of wireless communication networks of the IEEE 802.11a type.

Advantageously, the preamble corresponds to at least one period of time intended for a frame detection operation, said at least one reception synchronization information is an estimate of a reception instant of said at least one given frame estimated from a predetermined frame transmission sequence. The said added period of time corresponds to at least a part of the said period of time intended for the frame detection operation.

In this case, it is therefore the time interval associated with the preamble data initially provided for the frame detection that can be used to test communication configurations between the sending node and the receiving node during the given frame. According to an advantageous characteristic, the preamble corresponds to at least one time period for gain gain adjustment, said reception timing information is an estimate of an estimated receive gain value from frames previously transmitted by the receiver. transmitting node. The said added period of time corresponds to at least a part of the said period of time intended for the reception gain adjustment.

In this case, it is therefore the lapse of time (or possibly the sub-time interval) associated with the preamble data initially provided for the gain gain adjustment that can be used to test communication configurations between the node. transmitter and the receiving node during the given frame. Advantageously, the preamble corresponds to at least a period of time intended for reception frequency synchronization, said synchronization information is an estimate of a set of parameters corresponding to a reception frequency value estimated from transmitted frames. previously by said transmitting node. The said added period of time corresponds to at least a part of the said period of time intended for receiving frequency synchronization.

In this case, it is therefore the lapse of time (or possibly the sub-time interval) associated with the preamble data initially provided for the reception frequency synchronization that can be used to test communication configurations between the transmitting node. and the receiving node during the given frame. This feature is furthermore simple to implement.

According to one variant, the preamble corresponds to at least one period of time intended for frequency synchronization on reception, said reception synchronization information is an estimate of a first set of parameters corresponding to a reception frequency value, estimated at from a second set of parameters corresponding to a frequency value on reception of a third node and information representative of a third set of parameters corresponding to a frequency value on reception of the third node with respect to the transmitting node . The said added period of time corresponds to at least a part of the said period of time intended for receiving frequency synchronization. This variant embodiment makes it possible to use the lapse of time (or possibly the sub-time interval) associated with the preamble data initially provided for reception frequency synchronization, to test communication configurations between the sending node and the node. receiver during the given frame. This variant also makes it possible to determine synchronization information relating to the transmitting node while a first reception of data originating from this node has not yet been made.

According to a preferred feature, it comprises a step of putting at least one receive module of the receiving node into sleep for at least part of said available time but not used to test communication configurations between the source node and the transmitting node. The time made available (or released), by the application of at least one of the above characteristics, but not used, can be used to put the receiver node to sleep so that it reduces its energy consumption. Advantageously, said at least one communication configuration test belongs to the group comprising: - signal measurements received during a scanning of angles of an antenna receiving the receiving node; - Signal measurements received during a reception frequency scan of the receiving node. - Received signal measurements by changing the shape of a sensitivity beam of an antenna receiving the receiving node. This list is not exhaustive. Thus, the extra time capital obtained can be used to adjust the antenna angles of the receiving node, without disturbing the current communication. This additional time capital can also be used to perform a frequency scan of other radio communication channels to know their status and possibly prepare a change of the communication channel for the current communication. Advantageously, the receiving node performs the following steps: - configuring the receiving node, for receiving the next frame transmitted by said sending node, from parameters obtained by the execution of at least one said communication configuration test ; - Perform, when receiving said next frame, the synchronization operations to which the preamble of said next frame is intended. Thus, when the reception configuration test of the receiving node, or of the communication configuration between the transmitting node and the receiving node makes it possible to adjust, or more generally to modify, receiving parameters of the receiving node, the synchronization operations to which The preamble is intended to be executed again in order to obtain synchronization information in accordance with the adjustment made following the configuration test. For example, if the configuration test leads to a modification of the sensitivity beam of an antenna receiving the receiving node (which is the equivalent in reception of the beam of radiation for an antenna configured in transmission), then new parameters of receive synchronization must be obtained, such as gain for example, to improve the reception quality of the receiving node. In another embodiment, the invention relates to a computer program product downloadable from a communication network and / or recorded on a computer readable medium and / or executable by a processor. This computer program product includes program code instructions for carrying out the aforesaid method (in any one of its various embodiments), when said program is run on a computer.

In another embodiment, the invention relates to a computer readable storage means, possibly totally or partially removable, storing a computer program comprising a set of instructions executable by a computer to implement the aforementioned method (in any of its different embodiments). In another embodiment, the invention relates to a receiver node of at least one frame with a preamble in a communication network, the preamble being such that it corresponds to a time slot intended for at least one synchronization operation. receiving, by said receiving node of the network, at least one frame transmitted by a transmitter node of the network. Said receiving node comprises: means for estimating at least one reception synchronization information for reception of said given frame (s) transmitted by the sending node; first means for configuring said receiving node for receiving said at least one given frame from said at least one estimated synchronization information; means for testing at least one communication configuration between the transmitting node and the receiving node during a period of time intended for the execution of at least one synchronization operation the result of which is estimated by the step d 'estimate. According to an advantageous characteristic, the receiving node comprises adding means, at a time available for carrying out at least one communication configuration test between the transmitting node and the receiving node during the reception of the preamble, said lapse of time corresponding to the performing at least one synchronization operation whose result is estimated by the estimation step. In the case where the preamble is such that it corresponds to a predefined sequence of sub-time intervals each intended for a given synchronization operation, for each sub-time interval of a set comprising at least one sub-time interval for the execution of at least one synchronization operation whose result is estimated by the estimation step, is added to said available time at least a part of said sub-time interval.

Advantageously, the preamble corresponds to at least one period of time intended for a frame detection operation, said at least one reception synchronization information is an estimate of a reception instant of said at least one given frame estimated from a predetermined frame transmission sequence. The added time interval corresponds to at least a portion of said time interval for the frame detection operation.

According to an advantageous characteristic, the preamble corresponds to at least one time period for gain gain adjustment, said reception timing information is an estimate of an estimated receive gain value from frames previously transmitted by the receiver. transmitting node. The said added period of time corresponds to at least a part of the said period of time intended for the reception gain adjustment. Advantageously, the preamble corresponds to at least a period of time intended for reception frequency synchronization, said synchronization information is an estimate of a set of parameters corresponding to a reception frequency value estimated from transmitted frames. previously by said transmitting node. The said added period of time corresponds to at least a part of the said period of time intended for receiving frequency synchronization. According to one variant, the preamble corresponds to at least one period of time intended for frequency synchronization on reception, said reception synchronization information is an estimate of a first set of parameters corresponding to a reception frequency value, estimated at from a second set of parameters corresponding to a frequency value on reception of a third node and information representative of a third set of parameters corresponding to a frequency value on reception of the third node with respect to the transmitting node . The said added period of time corresponds to at least a part of the said period of time intended for receiving frequency synchronization. Advantageously, the receiving node comprises: second configuration means for receiving the next frame transmitted by said sending node, from parameters obtained by the execution of at least one said communication configuration test; Means for executing, when receiving said next frame, synchronization operations to which the preamble of said next frame is intended. 5. LIST OF FIGURES Other characteristics and advantages of the invention will appear on reading the following description, given by way of indicative and nonlimiting example, and the appended drawings, in which: FIG. 1 schematically shows a example of a communication network in which is implemented the reception method according to a particular embodiment according to the invention; FIG. 2 illustrates an example of a synchronous physical layer using time division multiplexing (TDM); - Figure 3 shows the schematic structure of a communication device implementing the reception method according to a particular embodiment according to the invention; FIG. 4a illustrates an exemplary mode of operation of a transmitting antenna; FIG. 4b illustrates an example of an operating mode of a receiving antenna; FIG. 5 represents the structure of a super data frame transmitted within a communication network; FIG. 6 shows an example of application of the principle of the invention over two successive transmission cycles, according to a particular embodiment; FIG. 7a shows an example of use of a preamble according to a mode of processing super frames of the first type, according to one particular embodiment of the invention; FIG. 7b shows an example of use of a preamble according to a mode of processing super frames of the second type, according to a particular embodiment of the invention; FIG. 8 represents a flowchart of an algorithm for determining a superframe processing mode according to a particular embodiment of the invention; FIG. 9a represents a communication diagram in which a method for determining the frequency error is implemented according to an alternative embodiment of the invention; FIG. 9b shows an example of application of the method for determining the frequency error over two successive transmission cycles, according to an alternative embodiment of the invention; FIG. 10 represents, in the form of a functional block diagram, the structure of a reception device implementing the reception method according to a particular embodiment in accordance with the invention; FIG. 11A generically represents a flowchart of an algorithm for implementing the reception method according to a particular embodiment of the invention; - Figure 1 lb shows a detailed flow chart of an algorithm for implementing the method of the invention, according to a particular embodiment of the invention. 6. DETAILED DESCRIPTION In all the figures of this document, the elements and identical steps are designated by the same numerical reference. In the remainder of this document, the problem that exists in the context of synchronous mesh-type TDM communication networks is described below. The invention is of course not limited to this particular application framework and can be applied to any other type of communication network using a protocol, for example of the TDMA type, with regular presence of a preamble in data frame head and whose transmission time intervals of at least one transmitter device of the network are known from at least one receiving device. FIG. 1 shows schematically an example of a wireless communication network 100 in which the reception method according to a particular embodiment in accordance with the invention is implemented. More particularly, the communication network 100 of FIG. 1 illustrates a wireless video and audio (home theater type 5.1) distribution network using the millimeter waves around the 60GHz frequency band. The network 100 comprises a source node 110 (denoted WSC for Wireless Source Controller in English) including wireless communication equipment, as well as a plurality of transmitting and receiving nodes 140, 150, 160 and 170 (denoted WAS for Wireless Active Speaker), each node being able to behave alternately as a sending node and a receiving node and having only one antenna for transmitting and receiving radio data signals. In addition, some nodes can play the role of relay node, that is to say that they retransmit on the network data they have previously received from another node. The nodes of the network 100 are all interconnected by links (or paths) of radio communication 130 millimeter wave. It is considered that the topology of the network 100, that is to say the relative spatial position of the nodes of the network (at least the orientation angles of the antennas necessary for the establishment of communications nodes between them), is known to each of the nodes 110, 140, 150, 160 and 170 of the network 100 and allows the operation of the mesh network. It should be noted that the particular embodiment described below is given by way of illustrative example. It is clear that many other embodiments of the invention can be envisaged, without departing from the scope of the invention. To transmit a stream of data relating to an audio stream, a video stream or a combination of both, a protocol such as that described by the IEEE 802.15.3 standard can, for example, be implemented. In addition to the fact that it allows very high data rates (in its IEEE 802.15.3c version), because of data transmission in the 57-64 GHz frequency band, this protocol offers the possibility, at each node of the network , to benefit from access time to the guaranteed shared wireless communication medium by using time division multiplexing, also called TDM (for Time Division Multiplexing in English), providing a division of the time domain into a plurality of recurring time intervals, of fixed length, also hereinafter called TDM cycle. Such multiplexing allows certain parameters, such as transmission latency or the bandwidth allocated to each transmission, to remain invariant. In addition, in this carrier frequency band, attenuation of the radio signal in the air is important. In practice, this requires that, to ensure a good level of quality of radio communication (very high speed data transmission) and to obtain a sufficient radio range (about ten meters), the nodes of the network have antennas configured so directive (or selective) with a significant positive gain. FIG. 2 illustrates an exemplary synchronous physical layer using time division multiplexing (TDM). Typically, the time is divided into TDM cycles 200 and the physical medium shared over time so that each of the nodes of the communication network is allocated a talk time 220 (or time slot) per TDM cycle 200 to transmit his data 230.

When a node transmits data 230 in its talk time 220, all other nodes can listen to it using their directionally configured antennas with a positive gain. Each speech time 220 can carry zero, one or more data blocks of a data stream, depending on the flow rate of this data stream, and more generally, depending on the data actually to be transmitted.

Thus, each of these data blocks also corresponds to a time transmission interval. It can be noted that among the blocks of data, clean or relayed, there are blocks of control data, allowing the transmission and the relay of control messages. Each data block can itself be divided into a plurality of packets or symbols. The relay nodes of the communication network also retransmit data blocks (so-called relay blocks) to third nodes of the network so that at the end of the cycle 200 (or a predetermined number of cycles 200), the data blocks received in the different time slots 220 represent different copies of the original data block. This is called Network Mesh Relay.

The transmission mode used for each time interval 220 is performed in a quasi-omnidirectional antenna configuration (wide radiation angle). The receive mode used for each time slot 220 is in an antenna directive pattern (reception angle, or sensitivity, narrow). The schematic structure of a communication device 300 implementing the reception method, according to a particular embodiment according to the invention, is now presented with reference to FIG. More specifically, the communication device 300 can be integrated in the source node 110 or each of the sending nodes or receiving nodes (140, 150, 160, 170), or in any relay node of the communication network 100. The communication device 300 comprises: - Random Access Memory (RAM) 302 functioning as main memory; a calculation block 301 (noted c for micro-controller in English) or a CPU (for Control Process Unit in English) whose capacity can be extended by an optional RAM connected to an expansion port (not shown on FIG. Figure 3). The CPU 301 is capable of executing instructions when the communication device 300 is turned on from the ROM 303. After the power is turned on, the CPU 301 is able to execute the RAM 302 relating to a computer program, once these instructions loaded from the ROM 303 or external memory (not shown in Figure 3). Such a computer program, if executed by the CPU 301, causes the execution of some or all of the steps of the algorithms described below in connection with FIGS. 8, 11a and 1a. lb; a block 310 (denoted RF-FE for RF Front-End in English) responsible for adapting the signal at the output of a baseband block 305 (noted BB for Base-Band in English) before being transmitted by the Via an antenna 304. For example, the adaptation can be performed by frequency translation and power amplification processes. Conversely, the block 310 also allows the adaptation of a signal received by the antenna 304 before its transmission to the baseband block 305. The baseband block 305 is responsible for modulating and demodulating the digital data exchanged with the baseband 305. block 310. The block 305 includes a synchronization module 308 (denoted RS for Reception Synchronization), activated when the communication device 300 is in data reception mode; an input / output interface block (denoted I / O If for Input / Output Interface in English) 306 connected to a communication network 307. FIG. 4a illustrates an example of a mode of operation of a transmission antenna 400 In the particular embodiment shown in FIG. 1, that is to say in the communication network 100, the transmission antennas 400 are configured at a wide radiation angle 410 (for example greater than 90 °) for to reach the maximum number of nodes within the network. This makes it possible to increase the probability that the data will be received by nodes of the network (which can then relay this data so that all the nodes of the network can eventually receive this data). In this case, it is called a quasi-omnidirectional transmission antenna configuration.

FIG. 4b illustrates an example of a mode of operation of a reception antenna 500. In the particular embodiment presented in FIG. 1, that is to say in the communication network 100, the reception antennas 500 (Which may correspond to the antennas 400 in the case where the same antenna is used in transmission and reception) are always configured (that is to say whatever the mode of transmission implemented) at a narrow reception angle 520. In this case, we speak of reception antenna directive configuration. Each receiving node of the network then implements an antenna directivity technique (called beamforming in English). Indeed, according to this technique, the use of a narrow reception angle 520 makes it possible to increase the power of the radio signal at the input of the receiver node, thus making it possible to increase the transmission distance, or at an equal distance. , to increase the signal-to-noise ratio (SNR). The quality in terms of radio signal reception is thus improved and the transmission channel error rate reduced.

The orientation of the main directional lobe 520 of the receiving antenna 500 is represented by an orientation angle (3530). This angle (3 is selected from a set of antenna orientation angles belonging to the sensitivity of the antenna 500 configured almost omnidirectionally.In other words, the angle of orientation 13 can take any angle value between 0 degrees and 180 degrees.One angle of orientation, in the case of an agile (or intelligent) antenna, an angle for which the configuration parameters of the agile antenna matrix are such that the radiation (in transmission) or the sensitivity (in reception) of the antenna is accentuated in this direction with respect to the other directions Figure 5 illustrates the structure of a super frame 500 of data transmitted within a communication network 100.

When the communication network 100 is operational, a super frame 500 is transmitted regularly and successively in time at each synchronous transmission cycle (TDM). During a TDM cycle, each node of the network transmits a data frame 510 in a predefined sequence. In the case of the communication network 100 of FIG. 1, a super frame 500 consists of five successive data frames 510, each of the frames 510 being transmitted by one of the nodes 110, 170, 140, 150 and 160. More specifically, each data frame 510 comprises the following data fields: a first field 511 (commonly called a preamble) placed in the frame header, carrying the data enabling the receiving node to perform reception synchronization operations; frames of data transmitted by sending nodes; a second field 512 comprising a sequence of symbols (Si) constituting the useful data to be transmitted. More specifically, the preamble 511 itself consists of the following subfields: a first subfield comprising a sequence of ten identical symbols 516, commonly called short symbols (or Short Symbols); a second subfield comprising a data stream 515 for protecting long symbols 517; A third subfield comprising two symbols 517, commonly called long symbols (or Long Symbols). The short symbols 516 are intended for certain synchronization operations, and more particularly for the coarse time synchronization (or frame detection), the gain control (noted AGC in the figure for Automatic Gain Control) and the coarse correction of the frequency error (or offset) or (noted CFO for Coarse Frequency Offset). The part of the preamble comprising the data stream 515 and the long symbols 517 is intended for synchronization operations of the fine time synchronization type, fine correction of the frequency error (or offset) (denoted FFO for Fine Frequency Offset), estimation of the transmission channel. By way of purely illustrative example, for an IEEE 802.11a type network, the time interval corresponding to the short symbols 516 is 8 microseconds and the time interval corresponding to the data sequence 515 and the long symbols 517 is 8 microseconds. FIG. 6 shows an example of application of the principle of the invention over two successive transmission cycles, according to a particular embodiment. In this figure appear the communication mode of the node 160 of the network 100, as well as the value of each of the synchronization parameters (or synchronization data) of this node affected by the implementation of the present invention for the first two super frames issued. A first line 610 successively indicates the communication modes of the node 160 for each super frame, namely: in receive mode when a radio data signal is sent by the source node 110 (WSC); in receiving mode when transmitting a radio data signal by node 170 (WAS1); in reception mode when a radio data signal is transmitted by the node 140 (WAS2); - in transmission mode; - in reception mode when transmitting a radio data signal by the node 170 (WAS4). A second line 620 indicates the mode of operation of an automatic gain control module (AGC module) of the node 160. During the super frame 0, no synchronization information having previously been stored, the AGC module is in normal operation. The values relating to the gain control parameter (denoted G3C (for Gain WAS3-WSC, that is to say the gain applied to the node WAS3 when it receives from the node WSC), G31 (for Gain WAS3-WAS1), G32 (for GAS WAS3-WAS2), G34 (for Gain WAS3-WAS4 are then determined, for each frame 510, from the data contained in the short symbols 516 of preamble 511. These gain control values are then used to control the receive gain of the data signals for each frame 510 received from the super-frame 0 and thus ensure good reception of these signals.These values are also stored in a table for later use in one or more future frames. During the super frame 1, the gain control values are extracted, for each frame 510, from the table stored during the super frame 0 and reused to estimate the gain to be applied to the frames 510 of the super frame 1, and ensure thus a good reception of these signals. A third line 630 indicates the operating mode of a frame detection module of the node 160. In the super frame 0, no synchronization information having previously been stored, the frame detection module is in operating mode. normal. Frame start times are determined (denoted FD for frame detection), for each frame 510, from the data contained in the short symbols 516 of preamble 511. The duration of a super frame and the sequence of the frames in a super frame frame being a priori known, it is then possible to estimate (with the clock drift close) the start time of each frame 510 (denoted tsofl, tsof2, tsof3 and tsof4) of the super frame 1. To do this the value corresponding to the beginning of each frame 510 of the super frame 0 is added to the nominal duration of a super frame period.

For example, a counter can be triggered from the detection of the start of a given frame of the super-frame 0, the beginning of said given frame of the super-frame 1 starting when the value of this counter is equal to the duration of the period of a super frame. A fourth line 640 indicates the operating mode of a module for rough correction of the frequency error (module CFO) of the node 160. During the super-frame 0, no synchronization information having previously been stored, the module CFO is in normal operating mode. The values relating to the coarse correction parameter of the frequency error (denoted CFO 3C (for CFO WAS3-WSC, that is to say the coarse frequency correction applied to the node WAS3 when it receives from the node WSC), CFO 31 (for CFO WAS3-WAS1), CFO 32 (for CFO WAS3-WAS2) and CFO 34 (for CFO WAS3-WAS4 are then determined, for each frame 510, from the data contained in the short symbols 516 of the preamble 511 These values are used to apply a coarse frequency error correction on the data signals for each frame 510 received from the super-frame 0 and thus to ensure good reception of these signals. the transmission frequency and the frequency of reception of the radio wave, the frequency synthesizers of the transmitter and the receiver not being (in the particular embodiment described here) exactly at 60GHz, but can be shifted a few tens of ppm (parts per million). These values are also stored in a table for later use in one or more future frames. During the super frame 1, the coarse correction values of the frequency error are extracted, for each frame 510, from the table stored in the super frame 0 and reused to estimate the correction to be applied to the frames 510 of the frame. super frame 1, and thus ensure good reception of these signals. It therefore appears, in the light of this description, that there are two modes of superframe processing, a first mode in which synchronization data are determined from the frames, and more particularly from the preamble of the frames in the frame. particular embodiment described herein, of a current super frame (referred to as a first type of processing mode), a second mode in which the synchronization data is estimated from the synchronization data obtained during a super previous frame (we are talking about a second type of treatment).

It should be noted that the switchover from one processing mode of the first type to a processing mode of the second type, for all or part of the synchronization operations allowing the reception of a data frame, can be carried out in a predetermined manner at from the knowledge of the communication network implemented, namely: the characteristics of the nodes of this network (component drifts in time, in frequency, ...), the requirements in terms of testing communication configurations. In a particular embodiment, the switching from a treatment mode of the first type to a treatment mode of the second type is implemented periodically. According to a first alternative embodiment, it is possible to implement a first type of processing mode during the duration of a superframe and a second type of processing mode during the duration of (N-1) superframes, N corresponding to a number of super frames which can be defined according to the stability of the network equipment. A second alternative embodiment, not described here but easily achievable by the person skilled in the art, consists in using, for the second type of processing mode, synchronization data estimated not only from the synchronization data of the frames. a previous superframe, but from a combination of the synchronization data (averaging for example) frames of several previous superframes. We now present, in connection with FIG. 7a, an example of use of a preamble according to a mode of super-frame processing of the first type, according to a particular embodiment of the invention. More particularly, it illustrates the use of a preamble in the case where the synchronization data is determined from the frames of a current super frame, to perform communication configuration tests for a given number (N-1). consecutive super frames. In this case, the first seven short symbols 516 of preamble 511 are used to perform frame detection and gain control. The last three short symbols 516 are used to perform the rough correction of the frequency error, the data stream 515 and the two long symbols 517 of the preamble 511 are used for the fine time synchronization, the fine correction of the error of frequency and estimation of the transmission channel. An example of use of a preamble according to a method of processing super frames of the second type, according to a particular embodiment of the invention, is now presented in relation with FIG. 7b. It particularly illustrates the use of a preamble in the case where the synchronization data is estimated from the frame synchronization data of a previous super frame, to perform communication configuration tests for a given number (N -1) consecutive super frames. In this case, the frame start time is estimated from a previously stored frame start and the addition of a multiple of the duration of the period of a super frame (denoted TSF for Time Super Frame ), this multiple corresponding to the number of superframes passed from the superframe which has been the subject of the first type of treatment mode. The gain control and frequency error correction values are also estimated from the previously stored timing data. In this way, the time slots initially dedicated to the aforementioned synchronization operations (i.e. frame detection, gain control, and coarse frequency error correction) can then be used to perform communication configuration tests between the receiving node 160 and the transmitting node of the current frame, using antenna configuration parameters of the receiving node 160 other than those normally used to perform the communication of the data of the current frame between these nodes.

These communication configuration tests make it possible, for example, to optimize the antenna pointing of the receiving node, or to know the transmission state of other transmission channels, or to optimize the parameterization of the beam (including, in the case of using an agile antenna, several complementary lobes) sensitivity of the antenna in reception of the receiving node.

If these time intervals are not used to perform communication configuration tests, it is possible to suspend some modules of the receiving node, in order to limit its power consumption. The remaining portion of the preamble (corresponding to data stream 515 and long symbols 517 of preamble 511) is used, analogously to FIG. 7a, for fine time synchronization, fine correction of frequency error, and estimation of the transmission channel. FIG. 8 represents a flowchart of a superframe processing type determination algorithm, according to a particular embodiment of the invention. More specifically, FIG. 8 illustrates the particular case where the three time slots normally dedicated to frame detection, gain control and coarse correction of the frequency error are used to perform communication configuration tests. during a number of (N-1) super consecutive frames, the synchronization data being estimated from the frames of a super frame on N super frames. In this particular embodiment, the set of synchronization data is thus systematically updated during the frames of a super frame all the N superframes. During an initialization step 800, a time counter is initialized to zero (t = 0), a parameter representative of the duration of the period of a super frame (denoted TSF), a parameter representative of the number of frames in a super frame (denoted FNmax), a parameter representative of the number of superframe updating cycles (denoted N) and a table of antenna orientation angles (a, FN) are loaded by a microprocessor, such as for example, the microprocessor 1040 of FIG.

In a step 802, a Super Frame Number (SFN) super frame counter is initialized to 0, then in a step 804, a frame number FN is also initialized to 0. The node 160, in a step 806, point its antenna in a given direction by an angle a of the angle table (a, FN) before seeking to detect the beginning of the current frame, in a step 808. The value of the time counter (noted tsof (FN)) corresponding to the start time of the frame FN is stored in this same step.

The node 160 then goes to a step 810 in which it determines the value of the gain control parameter (denoted by G (FN)) to be applied to the data of the current frame and applies this gain. During a step 812, the value of this parameter G (FN) is memorized.

The node proceeds to a step 814 in which it determines the value of the coarse correction parameter of the frequency error (denoted CFO (FN)) to be applied to the data of the current frame and performs this correction. During a step 816, the value of this parameter CFO (FN) is memorized. The first synchronization steps (ie those which are performed only one superframe on N superframes starting from the first) being performed, the node 160 performs, accurately, a detection of the beginning of frame, in a step 818. It then determines the value of the fine correction parameter of the frequency error to be applied in a step 820 and performs this correction. It then determines, in a step 822, whether compensation of the radio transmission channel must be undertaken and performs this compensation before demodulating the data of the current frame in a step 824. Once the current frame is demodulated, the node 160 increments, in a step 826, the value of the frame counter (FN) of 1. It then checks, in a step 828, if this frame is the last incoming frame of the super frame by making a comparison with the parameter FNmax. If this frame is not the last frame of the superframe, node 160 returns to step 806 in which it begins processing a new frame of the superframe. If this frame is the last frame of the super frame, the node 160 increments the value of the superframe counter (SFN) in a step 830 before proceeding to the next step 832. In this step 832, the node 160 performs a test on the value SFN to determine if this super frame must undergo a first type or second type treatment, according to the principle explained above in relation to FIG. 6. To do this, the value SFN is compared with the zero value modulo (N), with N the parameter representative of the number of superframe update TDM cycles (corresponding to N super frames transmitted on the network).

If the result of the test is positive, the frame undergoes a treatment of the first type and the node 160 then returns to step 804. If the result of the test is negative, the frame undergoes a second type of processing and the node 160 goes into a step 850 in which it estimates the start time of the frame FN according to the following formula: t = tsof (FN) + SFN * TSF, with the instant tsof (FN) of the super frame 0, the value of the counter SFN super frame, the duration of a period of super TSF frame. In the particular case illustrated here, it is the time slot reserved for the synchronization operations corresponding to the ten short symbols 516 of the preamble 511 which is used to test new communication configurations. At the output of step 850, the node 160 checks, in a step 852, whether the value t of the time counter is within the time interval thus made available (or released) for testing new communication configurations. In other words, the node 160 checks whether the value t of the time counter is between the value tsof (FN) + SFN * TSF (corresponding to the beginning of the frame FN) and tsof (FN) + SFN * TSF + lOTss (corresponding at the end of the sequence of short symbols), where Tss is the duration of a short symbol. If the value t of the time counter is within the time interval dedicated to the communication configuration tests, the node 160 can then test new communication configurations. It therefore goes to a step 860 in which it performs power measurements (of the RSSI type, for example, for the Received Signal Strength Indicator) by orienting its reception antenna in directions other than that provided for, for example according to an orientation angle a, for receiving the data of the current frame.

If the value of the time counter is not (or no longer) within the time interval dedicated to the communication configuration tests, the node 160 prepares to enter data processing mode of the current frame . For this, it goes into a step 854 during which it directs its receiving antenna at an angle of orientation given in the table (a, FN). Then, in a step 856, the node 160 applies the previously stored gain value (G (N)) to the current frame and, in a step 858, it applies the correction value of the previously stored frequency error (CFO (NOT)). The first synchronization operations (equivalent to the steps 806, 808, 810, 814) having been applied to the frame, the node 160 then proceeds to the steps 818, 820, 822 detailed above, in which the frame undergoes the complementary synchronization operations. , before demodulating the data in step 824. Next, the set of algorithm described above is again implemented for each remaining frame of the super frame. FIG. 9a shows a communication scheme in which a method for determining the frequency error is implemented according to an alternative embodiment of the invention. This method is based on the fact that a node (node 160 (WAS3) can determine its frequency error with respect to a given node (source node 110 (WSC)) from the knowledge of the frequency error FO1C ( for Frequency Offset WASl-WSC, i.e. the frequency correction applied to the node WAS1 when it receives from the node WSC) between this given node and a third node (node 170 (WAS1)) and the estimate its frequency error FO31 (for Frequency Offset WAS3-WAS1) with this third node, it is therefore necessary that the configuration of the communication system allows communication between these three nodes and that the third node is able to communicate the value of the third node. frequency error FO1C measured when receiving data from the source node Figure 9b shows an example of applying the method of determining the frequency error over two successive transmission cycles according to a mode of transmission. variant embodiment The first line 910 indicates the communication mode of the node 160 (WAS3) within the network 100 which is identical to that described above in relation with FIG. 6. The second line 920 indicates the mode of operation of the CFO module of node 170 (WAS1). In the super frame 0, the CFO module is in normal mode and the node 170 (WAS1) determines the values of the frequency error correction parameter, for each frame, from the data contained in the short symbols 516 of the preamble 511. When receiving the frame transmitted by the node 110 (WSC), the node 170 (WAS1) therefore determines the value of this parameter CFO 1C, applies this correction to the data frame before demodulating the data, then , stores this value CFO 1C in a table. During the next frame, which is that dedicated to the transmission of data by the node 170 (WAS1), the latter re-transmits, in a quasi-omnidirectional antenna configuration, the value of this parameter CFO 1C in a field of predetermined data. The third line 930 indicates the mode of operation of the module CFO of the node WAS3. During the super frame 0, no synchronization information having previously been stored, the CFO module is in normal mode and the values of the control parameter CFO are determined, for each frame, from the data contained in the short symbols. 516 of preamble 511. These values (including CFO 31) are respectively used to apply the coarse frequency correction to the signals of each successive frame in reception and thus ensure the good reception of the signals. When it is the turn of the node WAS1 to transmit, the node 160 (WAS3) receives the value of the parameter CFO 1C sent by the node 170 (WAS 1) in a predetermined data field and stores it in a table to be used during the super frame 1.

During the super frame 1, the CFO module of the node 160 (WAS3) can therefore estimate the value of the parameter CFO to be applied to the current frame by adding the value of the received parameter CFO 1C and the value of the estimated parameter CFO 31 during the super frame 0, and thus be able to use the time normally intended for the rough correction of the frequency error during the transmission of the preamble of the frame transmitted by the node WAS1 170. Now, in relation with FIG. , in the form of a functional block diagram, a receiver device 1000 implementing the reception method according to a particular embodiment according to the invention. Here is meant by receiving device, the part of the receiving device processing the data received from the physical layer before transmitting it to the upper communication layer.

It should be noted that this functional block diagram is similar to that of a conventional Orthogonal Frequency Division Multiplexing (OFDM) receiver device and that those skilled in the art are aware of the main data processing modules thereof. However, some processing performed by the microprocessor 1040 (noted p) in this particular embodiment is within the scope of the present invention. Indeed, certain processes implemented by the microprocessor 1040 allow the execution of part or all of the steps of the algorithm described above in relation to FIG. 8, and therefore the launching of the communication configuration tests. .

The baseband signal coming from the RF FE block (for FE Front End in English) first passes through an Automatic Gain Control (AGC) block 1002 which is responsible for determining the value of the gain control parameter (GC). and amplifying the received data signal accordingly. The amplified data signal is digitized by an ADC (Analog to Digital Converter) block 1004 or analog-to-digital converter, and then transmitted to the coarse time synchronization block 1016 which performs frame start detection and determines the time counter value. (FOBT). The digitized data signal is also transmitted to a coarse error correction block 1006, which is responsible for determining the value of the coarse correction parameter of the frequency error (CFO) and correspondingly correcting the signal. of data according to this parameter. The data signal coming from the block 1006 is then processed by a fine frequency error correction block 1008 which is responsible for determining the value of the fine correction parameter of the frequency error and correspondingly correcting the error signal. data according to this parameter.

The corrected data signal from block 1008 is then processed by a fine timing block 1010 which is responsible for accurately determining the start of frame data. The data signal thus processed is then transmitted to a block 1012 FFT (Fast Fourier Transform), which is responsible for transposing it in the frequency domain, and a channel estimation block 1018 which is responsible for measuring the disturbances made. by the radio transmission channel and transmitting them to a channel equalization block 1014, the latter using the measured parameters to process the data signal from block 1012. The data signal from block 1014 can then be demodulated by a block 1020 of the demodulator type. The data from the block 1020 are then successively transmitted to a block 1022 of deinterleaver type, a block 1024 of the decoder type FEC (for Forward Error Correction) and a block 1026 descrambler type, the output of the block 1026 constituting the output of the data of the receiving node. It is important to note that the particular characteristic of this receiver device 1000 is that the microprocessor 1040 has access to the synchronization parameters tsof, AGC, CFO and that it can force the blocks 1002, 1006, 1016 to use synchronization parameters previously. stored rather than parameters determined by these blocks from the data received during the transmission of frame preambles. Since the microprocessor 1040 is also the master of the control of the radio antennas, it can execute the algorithm described in FIG. 8 and orient the antennas in a predetermined direction corresponding to the sequence of frames to receive the data coming from a node transmitting the network or orient them in other directions to perform communication configuration tests. To perform these tests, the microprocessor 1040 receives information representative of the power of the received RF signal (signal RSSI, for Received Signal Strength Indicator). It should be noted that this signal is given as an example but any other signal for evaluating communication configurations can be used. FIG. 11a represents a general flowchart of an algorithm for implementing the reception method according to a particular embodiment of the invention. It should be noted that, throughout the description described so far, the present invention is described according to a particular embodiment in which an estimate is made consecutively for all the synchronization operations during the same preamble. This embodiment makes it possible to obtain a capital of additional time equal to a set of contiguous time slots, which makes it possible to avoid a switchover between the first mode of processing (determination) and the second method of processing (estimation). during the same preamble. A waste of time can thus be avoided.

The present invention is of course not limited to this particular embodiment. An alternative embodiment may in particular consist in taking into account, for the second processing mode (estimation), only a part of the synchronization operations. Thus, a capital of overtime equal to a set of non-contiguous time slots can be obtained. In this case, it is possible to define different periods for updating the estimated value according to the synchronization operations. In a step 1100, all the variables (number of the frame (FN), number of the current super-frame (SFN), elapsed time (t), result of the application of the algorithm for determining the processing mode of the Figure 8) are initialized. In a step 1105, the node 160 checks whether the frame detection operation is to be done on the incoming frame or from a stored value. In case of positive verification, it goes to a step 1115 in which it performs the frame detection and stores the value of the start of frame. This value will be used later to estimate the frame start time, when the node 160 determines that it should not do frame detection. In the case of a negative check, the node 160 proceeds to a step 1110 where it performs an estimate of the frame start time from a previously stored frame start information. It then goes to a step 1111 where it performs a configuration of its reception chain based on the estimate made. It then goes to a step 1120 in which it adds the time interval corresponding to the data of the preamble initially dedicated to the frame detection to a set of time slots dedicated to the communication configuration test. At the output of steps 1115 and 1120, node 160 goes to step 1125 where it checks whether the gain control operation is to be done on the incoming frame or from a stored gain control value. In case of positive verification, it goes into a step 1135 in which it performs the determination of the gain control signal, applies this gain on the data signal and stores the value of this gain control signal. This value will be used (alone or in combination with other information) to estimate the gain to be applied to one or more future frames when the node has determined that it should not do gain control over the current frame. In the case of negative verification, the node 160 goes to step 1130 where it performs the estimation of the gain control signal (for example, by repeating the signal value of the previous super-frame or by averaging the stored values at least 2 previous superframes). It then goes to a step 1131 where it performs a configuration of its reception chain based on the estimate made. It then goes to a step 1140 where it adds the time interval corresponding to the data of the preamble initially dedicated to the determination of the gain control signal to a set of time slots dedicated to the test of communication configurations. At the output of steps 1135 and 1140, node 160 goes to step 1145 where it checks whether the frequency error correction operation is to be done on the incoming frame or from a stored value. In the case of positive verification, it goes to a step 1155 in which it carries out the determination of the correction signal of the frequency error, makes this correction and stores the value of this signal. This value will be used (alone or in combination with other information) to estimate the frequency error correction signal to be applied to future frames when the node has determined that it should not make a correction of the frequency error on the current frame. In the case of negative verification, the node 160 proceeds to a step 1150 where it performs the estimation of the frequency error correction signal (for example, by repeating the signal value of the previous super-frame or averaging stored values of the at least 2 previous superframes). It then goes to a step 1151 where it performs a configuration of its reception chain based on the estimate made. It then goes to step 1160 where it adds the time interval corresponding to the data of the preamble initially dedicated to the estimation of the correction signal of the frequency error to a set of time intervals dedicated to the configuration test. Communication. At the output of steps 1155 and 1160, the node 160 proceeds to a step 1165 where it performs the complementary synchronization operations (steps 818, 820, 822 of FIG. 8) and the demodulation of the data. It then returns to step 1100 to process the next frame of the current super frame. It should be noted that the decisions taken in steps 1105, 1125, 1145 depend on the numbers of the frame (FN) and the current super frame (SFN) and the result of the application of the mode determination algorithm. 8. In fact, as a function of the choice made for each of the synchronization operations (frame detection, gain determination, determination of the frequency error) in determining mode from the current frame (processing mode of first type) or in estimated mode from previous super frames (second type of processing mode), there will be different types of frames. It should also be noted that, after performing a reception configuration test of the receiving node, or a communication configuration between the transmitting node and the receiving node (making it possible to adjust, or more generally modify, reception parameters of the receiving node, receiving node), the synchronization operations for which the preamble is intended can be performed again, upon reception of the next frame transmitted by the sending node, so as to obtain synchronization information in accordance with the adjustment performed following the configuration test. For example, if the configuration test leads to a modification of the sensitivity beam of an antenna receiving the receiving node, then new reception timing parameters can be obtained, such as gain for example, to improve the reception receiving quality of the receiving node.

FIG. 11b represents a detailed flowchart of an implementation algorithm of the invention in a particular embodiment of the invention. In time, the receiving node 160 can follow two different modes of operation. A test is therefore continuously performed to find out whether the value of the time counter (t) is within one of the time intervals dedicated to the communication configuration tests.

It may be that the time slots dedicated to these tests are not consecutive and then there will be several time intervals (for example, the expected time interval for the frame detection and the expected time interval for the estimation of the correction signal of the frequency error). This test is performed in a step 1180 of the present algorithm. If the result of the test is positive, the node 160 performs the communication configuration tests in a step 1185. If the test result is negative, the node 160 performs, in a step 1190, the synchronization or demodulation of the signal received. The test of step 1180 is in fact carried out continuously, in parallel with the operations of steps 1185 and 1190, these being interrupted as soon as the test result changes.

Claims (20)

REVENDICATIONS1. A method of receiving at least one preamble frame (511) in a communication network (100), the preamble (511) being such that it corresponds to a time slot for at least one synchronization operation of a receiving, by a receiving node of the network (100), at least one frame transmitted by a node transmitting the network (100), the method being characterized in that the receiving node performs steps of: - estimating (1110, 1130, 1150) at least one reception synchronization information for receiving said one or more given frames transmitted by the transmitting node; configuring (1111, 1131, 1151) the receiving node for receiving said at least one given frame from said at least one estimated synchronization information; testing (1185) at least one communication configuration between the transmitting node and the receiving node during a period of time intended for the execution of at least one synchronization operation the result of which is estimated by the estimation step . 2. Method according to claim 1, characterized in that the receiving node performs, following the step of configuring the receiver node, a step of: - adding (1120, 1140, 1160), at a time available for performing at least one communication configuration test between the transmitting node and the receiving node during the reception of the preamble, said lapse of time corresponding to the execution of at least one synchronization operation the result of which is estimated by the step estimation. 3. Method according to claim 2, the preamble (511) being such that it corresponds to a predefined sequence of sub-time intervals each intended for a given synchronization operation, characterized in that, for each sub-time interval of a set comprising at least one sub-time interval for executing at least one synchronization operation whose result is estimated by the estimation step, is added to said available time at least a part of said sub-interval of time. The method according to any one of claims 2 and 3, the preamble (511) corresponding to at least a period of time for a frame detection operation, characterized in that said at least one reception synchronization information is an estimate of a time of reception of said at least one given frame estimated from a predetermined frame transmission sequence, and in that said added period of time corresponds to at least a portion of said period of time for the transmission of frames; frame detection operation. The method according to any one of claims 2 to 4, the preamble (511) corresponding to at least one time period for gain gain adjustment, characterized in that said reception timing information is an estimate of an estimated receive gain value from frames previously transmitted by the transmitting node, and said added time period corresponds to at least a portion of said time period for receiving gain adjustment. 6. Method according to any one of claims 2 to 5, the preamble (511) corresponding to at least a period of time intended for reception frequency synchronization, characterized in that said reception synchronization information is an estimate of a set of parameters corresponding to a reception frequency value estimated from frames transmitted previously by said transmitting node, and in that said added period of time corresponds to at least a part of said period of time intended for frequency synchronization in reception. 7. Method according to any one of claims 2 to 6, the preamble (511) corresponding to at least a period of time intended for reception frequency synchronization, characterized in that said reception synchronization information is an estimate of a first set of parameters corresponding to a reception frequency value, estimated from a second set of parameters corresponding to a reception frequency value of a third node and information representative of a third set of parameters; parameters corresponding to a receive frequency value of the third node with respect to the transmitting node, and in that said added time period includes at least a portion of said time period for receiving frequency synchronization. 8. Method according to any one of claims 1 to 7, characterized in that it comprises a step of standby at least one receiving module of the receiving node for at least part of said available time but not used to test communication configurations between the source node and the transmitting node. 9. Method according to any one of claims 1 to 8, characterized in that said at least one communication configuration test belongs to the group comprising: - signal measurements received during a scanning of angles of an antenna; reception of the receiving node; - Signal measurements received during a reception frequency scan of the receiving node - Received signal measurements by changing the shape of a sensitivity beam of an antenna receiving the receiving node. 10. Method according to any one of claims 1 to 9, characterized in that the receiving node performs steps consisting in: - configuring the receiving node, for receiving the next frame transmitted by said sending node, from parameters obtained by performing at least one said communication configuration test; - Perform, when receiving said next frame, the synchronization operations to which the preamble of said next frame is intended. 11. Computer program product downloadable from a communication network and / or recorded on a computer readable medium and / or executable by a processor, characterized in that it comprises program code instructions for the implementation of the receiving method according to at least one of claims 1 to 10. Computer readable storage means, possibly totally or partially removable, storing a computer program comprising a set of instructions executable by a computer to implement the reception method according to at least one of claims 1 to 10. 13. Node receiving at least one frame with preamble (511) in a communication network (100), the preamble (511) being such that it corresponds to a time interval intended for at least one synchronization operation d a reception, by said receiving node of the network (100), of at least one frame transmitted by a node transmitting the network (100), said receiving node being characterized in that it comprises: - estimation means of at least one receive synchronization information for receiving said one or more given frames transmitted by the transmitting node; first means for configuring said receiving node for receiving said at least one given frame from said at least one estimated synchronization information; means for testing at least one communication configuration between the transmitting node and the receiving node during a period of time intended for the execution of at least one synchronization operation the result of which is estimated by the step d 'estimate. 14. Receiver node according to claim 13, characterized in that it comprises means for adding, at a time available for performing at least one communication configuration test between the transmitting node and the receiving node during the reception of the preamble. said period of time corresponding to the execution of at least one synchronization operation whose result is estimated by the estimation step. 15. Receiver node according to claim 14, the preamble (511) being such that it corresponds to a predefined sequence of sub-time slots each for a given synchronization operation, characterized in that for each sub-time interval a set comprising at least one sub-time interval for executing at least one synchronization operation whose result is estimated by the estimation step, is added to said available time at least a portion of said sub-time time interval. 10 15 16. Receiving node according to any one of claims 14 and 15, the preamble (511) corresponding to at least a period of time for a frame detection operation, characterized in that said at least one reception synchronization information is an estimate of a time of reception of said at least one given frame estimated from a predetermined frame transmission sequence, and in that said added time period corresponds to at least a portion of said time interval for the frame detection operation. A receiver node according to any one of claims 14 to 16, the preamble (511) corresponding to at least a time period for gain gain adjustment, characterized in that said reception timing information is an estimate. an estimated receive gain value from frames previously transmitted by the transmitting node, and in that said added time period corresponds to at least a portion of said period of time for receiving gain adjustment. 18. Receiving node according to any one of claims 14 to 17, the preamble (511) corresponding to at least a period of time intended for reception frequency synchronization, characterized in that said synchronization information is an estimate of a set of parameters corresponding to a reception frequency value estimated from frames previously transmitted by said transmitting node, and in that said added period of time corresponds to at least a part of said period of time intended for the frequency synchronization in reception. 19. Receiving node according to any one of claims 14 to 18, the preamble (511) corresponding to at least a period of time intended for reception frequency synchronization, characterized in that said reception synchronization information is an estimate. a first set of parameters corresponding to a reception frequency value, estimated from a second set of parameters corresponding to a reception frequency value of a third node and information representative of a third set parameters corresponding to a receive frequency value of the third node with respect to the transmitting node, and in that said added period of time corresponds to at least a portion of said time period for receiving frequency synchronization. 20. Receiving node according to any one of claims 13 to 19, characterized in that the receiving node comprises: - configuration means for receiving the next frame transmitted by said transmitting node, from parameters obtained by the performing at least one said communication configuration test; means for executing, when receiving said next frame, synchronization operations to which the preamble of said next frame is intended.