Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W76/00—Connection management
  • H04W76/10—Connection setup
  • H04W76/15—Setup of multiple wireless link connections
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/0001—Arrangements for dividing the transmission path
  • H04L5/0003—Two-dimensional division
  • H04L5/0005—Time-frequency
  • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/0001—Arrangements for dividing the transmission path
  • H04L5/0003—Two-dimensional division
  • H04L5/0005—Time-frequency
  • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT
  • H04L5/001—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT the frequencies being arranged in component carriers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/003—Arrangements for allocating sub-channels of the transmission path
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/003—Arrangements for allocating sub-channels of the transmission path
  • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/0091—Signaling for the administration of the divided path
  • H04L5/0094—Indication of how sub-channels of the path are allocated
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/04—Wireless resource allocation
  • H04W72/044—Wireless resource allocation based on the type of the allocated resource
  • H04W72/0453—Resources in frequency domain, e.g. a carrier in FDMA

Definitions

• the field of the invention is that of radiofrequency communications.
• the invention relates to the management of the frequency resources of equipment transmitting in a radiofrequency system, and more particularly a data packet transmission mechanism that can be used in this system.
• the invention finds particular applications in the management of frequency resources of equipment emitting in frequency bands around 2.4GHz or 5GHz, in which in particular equipment according to IEEE 802.11a, b, g, n or revised and future versions, also called Wifi standards.
• equipment here refers to an element belonging to a basic service set (BSS) formed by an access point (“access point”) and the stations associated with this point of service. access, that is to say the stations located in the coverage area of this access point.
• BSS basic service set
• the various Wi-Fi IEEE 802.1 standards la, b, g, n use transmission frequency channels which may be equal to a frequency band of 20MHz or 40MHz (40MHz being a concatenation of two radio frequency channels, or frequency bands, without overlap of 20MHz), or even a transmission on a frequency band of 80MHz by concatenating four contiguous or non-contiguous radio frequency channels of 20MHz, in a future version of the WiFi standard IEEE 802.1 In.
• overlapping Basic Service Set a radio frequency channel, or a frequency band, must be shared between the different sets of basic services (BSS).
• the CSMA-CA mechanism illustrated in FIG. 1, makes it possible to share access to a radio frequency channel according to a so-called contention principle: each equipment must listen for the channel to be free (that is to say, no signal is transmitted / received in this channel) for a variable duration, corresponding to an arbitrary interframe duration called AIFS (for "Arbitration InterFrame Space” in English) and a random waiting time (denoted B for "Backoff” in English) before transmitting data.
• AIFS for "Arbitration InterFrame Space" in English
• B random waiting time
• the access point decrements the "backoffs" of each packet waiting in the queues, as long as the channel is free.
• the listened channel is called primary channel, noted 1 in Figure 1 ("primary channel" in English).
• next generation equipment hereinafter referred to as “broadband” or “HT” equipment (for "High Throughput”)
• HT Next Throughput
• the equipment of old generation (able to implement the preceding norms), called thereafter equipment “legacy”, can not transmit on a band of frequency of 80MHz.
• the CSMA-CA mechanism allows each equipment, whether old or new generation, to "take control" of a channel, or a frequency band, to achieve a transmission at 20 MHz, 40 MHz or 80 MHz.
• a disadvantage of this technique of the prior art lies in the fact that, if an access point takes control of a channel to transmit to a station "legacy" limited for example on a frequency band of 20MHz (or to a "HT" station for a packet that does not need to use more than 20MHz), the remaining 60 MHz of the 80 MHz frequency band of the concatenated channel are not used. The spectral efficiency of the basic set of services is severely reduced.
• a current technique for transmitting over a frequency band greater than 20 MHz, in this case 40 MHz, allows a device (a station or an access point) wishing to transmit data packets on a frequency band of 40MHz to a single user, called destination equipment (respectively the access point or a station), to reserve the frequency band of 40MHz, but not however, it is not possible to transmit data packets on a 40MHz frequency band to several destination devices.
• the OEDMA multiple access technique makes it possible to transmit data packets to two destination devices over a frequency band of 80 MHz, using carriers that are separate from this frequency band for each of the destination devices and signaling to each of the recipient equipment which carriers are concerned.
• the destination equipment must therefore be compatible with this technique, in order to recognize the signaling enabling them to know which carriers are relevant to them.
• There is therefore a need for a new technique allowing optimal use of an available frequency band for transmitting data packets to different recipient equipment, whether old or new generation, so as to optimize efficiency.
• the invention proposes a new solution that does not have all of these disadvantages of the prior art, in the form of a method for transmitting data packets in a communication network using a plurality of radio frequency channels, at least two of the radiofrequency channels being concatenated to form a concatenated channel.
• such a method comprises:
• the invention is based on a new and inventive approach to the management of the frequency resources assigned to at least one equipment, in a communication network using a plurality of radio frequency channels, at least two of which are concatenated, or aggregated, to form a concatenated channel.
• a concatenated channel is composed of four radio frequency channels of 20 MHz, thus allowing transmission over 80 MHz.
• these destination devices correspond to stations associated with an access point, in a set of basic services (BSS) as described above in relation to the prior art.
• BSS basic services
• a first step of acquiring and reserving a first frequency band, composed of at least one radiofrequency channel of the concatenated channel, is used to transmit data packets to a first recipient equipment.
• This first destination equipment is for example a "legacy" station, capable of transmitting and receiving 20 MHz data packets, or a "HT" station, capable of transmitting and receiving data packets on 20, 40 or 60 MHz.
• this first step of acquiring and reserving a first frequency band implements the CSMA-CA mechanism, already described above in relation with the prior art and detailed further.
• an access point attempts to access a 20 MHz frequency band, corresponding to a radio frequency channel of a concatenated channel of 80 MHz, and then reserves this frequency band, when it is free, for transmit data packets to a legacy station, or to transmit data packets that do not require a larger frequency band, to an associated "HT" station.
• an access point attempts to access and reserve a first 40 MHz frequency band, then formed by two radiofrequency channels of the concatenated 80 MHz channel, to transmit data packets to a "HT" station. "Capable of transmitting and receiving on a frequency band of 40 MHz.
• a second acquisition and reservation step consists in reserving a second frequency band formed of the radio frequency channels of the concatenated channel that are not reserved during the first step, for the transmission of the data packets to a second destination device.
• an access point reserves a first 20 MHz frequency band (corresponding to a radio frequency channel) for transmitting data packets to a first destination device, for example a "legacy" station
• the access point tries to access also a second frequency band of 60 MHz, corresponding to the other three radiofrequency channels not yet reserved, then the reserve, when it is free, to transmit data packets to a second destination equipment, for example an "HT" station.
• an access point reserves a first frequency band of 40 MHz, then formed by two radiofrequency channels of the concatenated channel of 80 MHz, to transmit data packets to a station "HT"
• the point d access is also trying to access a second frequency band of 40 MHz, corresponding to the two other radiofrequency channels not yet reserved, then reserves this second frequency band, when it is free, to transmit data packets to a second "HT" station.
• These first and second frequency bands are then used to simultaneously transmit the data packets to the first and second destination equipment respectively, thus optimizing the concatenated channel occupancy.
• the first and second destination equipment can correspond to one and the same equipment.
• the method comprises at least one step of selecting a data packet from among the data packets to be transmitted to at least one second destination device, and the transmitting step transmits the selected packet on the second frequency band.
• an access point since an access point may be requested by a plurality of associated stations, it may have a plurality of packets to be transmitted to a plurality of destination equipment, these packets being stored in one or more queues before being processed by the access point.
• the second frequency band reserved by the access point consisting of non-reserved radio frequency channels in the first acquisition and reservation step may have different characteristics. , depending on the first frequency band reserved. For example, it can allow transmission on 60, 40 or 20 MHz, depending on the size of the first reserved frequency band.
• the method according to this embodiment of the invention therefore provides for selecting, among the data packets in the access point queue, the one or those that will be transmitted on the second reserved frequency band when the second stage of acquisition and reservation.
• the access point chooses the packet or packets to be transmitted on the second frequency band so as to optimize its use.
• the selection step comprises a first substep of selecting a set of at least one data packet among the data packets to be transmitted to at least a second destination device, taking into account the transmission duration of the packets and the ability of the second recipient equipment to receive data packets on the second frequency band.
• the access point chooses, among the data packets waiting for transmission, a set of packets destined for a destination device capable of implementing the invention, that is to say capable of transmitting and receive data packets on the second reserved frequency band. Indeed, among the pending packets, those to a "legacy” station can not be chosen, the "legacy” station not being able to receive on the second frequency band reserved.
• a selection is then implemented as a function of the transmission duration of the packets present in the queue (s), and the second frequency band reserved.
• the first selection sub-step selects packets having a transmission duration less than the transmission duration of the packets to be transmitted to the first destination equipment.
• the transmission of the packets being simultaneous on the first and second frequency bands
• the packets transmitted on the second frequency band must not be longer to transmit than those transmitted on the first frequency band, the transmission times packets being calculated taking into account the respective characteristics of the first and second frequency bands.
• At least two packets of the set are aggregated to form a single packet.
• the method according to the invention allows aggregating packets present in the queue (s), to the second destination equipment, for example according to a known technique defined in the IEEE 802.11 ⁇ standard.
• the selection step comprises a second substep of selecting a packet of data in the set, delivering the selected packet, the second substep of selection taking into account at least one of the criteria belonging to the group comprising:
• an optimization criterion is a priority criterion that is understood in terms of the data type of the packet, or the class of service to which the packet in question belongs. For example, a "Best Effort" (ie, no particular priority), or “Background” (ie, last deal) package is less of a priority than a packet of "Voice” type, requiring real-time transmission, or a "Video” type packet, requiring high quality transmission.
• These classes of service are, for example, indicated in the "Qos control / TE" field of the MAC header ⁇ 7.1.3.5 of the 802.11e standard.
• Another optimization criterion may take into account the transmission duration of the packet, relative to a predetermined transmission rate, for determining a penalty factor associated with a packet, representing an estimated occupation of the channel for the transmission of this packet.
• a criterion may consist in choosing the package that would penalize the other recipient equipment the most, if it were transmitted in a "conventional" manner, for example using only a 20 MHz frequency band.
• the method comprises a step of generating at least one preamble specific to the selected packet, the preamble or preambles comprising at least one simultaneous transmission indicator on the first and second frequency bands. and the sending step emits the specific preamble or preambles, before the selected packet, on the second frequency band.
• This embodiment of the invention corresponds to a transmission to a "legacy” station on the first frequency band, and a transmission to a "HT" station, able to implement the invention, on the second frequency band. .
• This embodiment makes it possible to signal to the second recipient equipment, via one or more preambles, the simultaneous transmission on the first and second frequency bands, so that it can decode the packets intended for it, that is to say ie those issued on the second frequency band.
• this or these preambles are only transmitted on the second frequency band, so as not to modify the transmission to a first recipient equipment "legacy" on the first frequency band .
• the method comprises a step of generating at least one preamble specific to the data packets destined for the first recipient equipment, the specific preamble or preambles comprising at least one simultaneous transmission indicator on the first and second frequency bands and the transmitting step transmits the specific preamble or preambles, before the packets, on the first frequency band.
• This embodiment corresponds to a transmission to a first "HT" station, able to implement the invention, on the first frequency band, and a transmission to a second "HT” station, able to implement the invention, on the second frequency band.
• This embodiment makes it possible to signal to the first recipient equipment, via one or more preambles, the simultaneous transmission on the first and second frequency bands, so that it can decode the packets intended for it, that is to say ie those issued on the first frequency band.
• the second destination equipment here the second "HT" station capable of implementing the invention, is also informed of the simultaneous transmission, so that it can decode the packets intended for it, that is, ie those issued on the second frequency band.
• the preambles are specific to the packets to be transmitted respectively to the first and second "HT" stations, able to implement the invention.
• the specific preamble further comprises at least one indicator belonging to the group comprising:
• the specific preamble or preambles, issued to inform of a simultaneous transmission stations "HT" capable of implementing the invention and recipients of data packets transmitted on the first and / or the second frequency bands also include indicators to better define this simultaneous emission.
• an indicator indicates that the simultaneous transmission is implemented on channel 2 of the concatenated channel, knowing that the radio frequency channel used to form the first frequency band for transmission to a "legacy" station is denoted channel 1.
• an indicator indicates that channels 2 to 4 of the concatenated channel forming the second frequency band are used for transmission to a "HT" station implementing the invention.
• an indicator indicates an identifier of a recipient equipment "HT", so that it can be informed packages intended for it, etc..
• the first and second acquisition and reservation steps implement:
• PIFS a transmission equipment
• the first acquisition and reservation step implements the known mechanism for accessing the CSMA-CA channel, already described in relation with the prior art, and consisting of listening a channel called a primary channel, for a variable duration, corresponding to an arbitrary interframe duration called AIFS (for "Arbitration InterFrame Space” in English) and a random waiting time (denoted B for "Backoff” in English), before transmitting Datas.
• AIFS for "Arbitration InterFrame Space" in English
• B random waiting time
• the second acquisition and reservation step implements a simplified mechanism for listening to the other channels forming the concatenated channel, during a period noted PIFS, shorter than the period AIFS, and whose end coincides with the end of AIFS.
• the simultaneous transmission can begin on the first and second frequency bands reserved.
• the access point only has to send packets on the primary channel, to a "legacy" station for example, it listens to the other channels of the concatenated channel, called secondary channel, tertiary and quaternary, in the case of a concatenated channel of 80 MHz and is therefore informed of the occupation of these channels, at the same time as the occupation of the . primary channel.
• the method comprises a step of receiving, on at least one of the radiofrequency channels comprising the first frequency band, denoted primary channel, acknowledgments associated with the packets transmitted simultaneously on the first and second frequency bands.
• the access point receives, on the primary channel, acknowledgments for receiving packets transmitted simultaneously on the first and second frequency bands, from the destination equipment of these packets.
• the acknowledgments are received on the primary channel by the access point, making it easier to manage acknowledgments for all the packets transmitted simultaneously.
• Another aspect of the invention relates to equipment for transmitting data packets in a communication network using a plurality of radio frequency channels, wherein at least two of the radio frequency channels are concatenated to form a concatenated channel.
• such transmission equipment comprises:
• Such transmission equipment is particularly suitable for implementing the transmission method described above. This is for example an access point or a Wifi station.
• This transmission equipment may of course include the various characteristics relating to the transmission method according to the invention. Thus, the characteristics and advantages of this transmission equipment are the same as those of the transmission method, and are not detailed further.
• the invention also relates to a method for receiving data packets in a communication network using a plurality of radiofrequency channels, wherein at least two of the radiofrequency channels are concatenated to form a concatenated channel.
• such a reception method comprises: a step of receiving data packets transmitted simultaneously on a first and a second frequency band, the first frequency band being formed of at least one of the radiofrequency channels of the concatenated channel and the second frequency band being formed of the other radio frequency channels the concatenated canal;
• the reception method according to the invention is based on a novel and inventive approach to the decoding of data packets, when these packets are transmitted simultaneously on two frequency bands, making it possible to decode only the data packets transmitted on one or the other of these frequency bands, according to a signal transmitted on one or the other of these frequency bands.
• This signaling informs a destination equipment of the frequency band that is intended for it, and on which the equipment then decodes the data packets.
• the reception method according to the invention when implemented in a "HT" station, it receives the data transmitted simultaneously on the two frequency bands and only decodes the data intended for it, for example those issued on the second frequency band reserved.
• the "HT" station is informed of the destination of the data by specific signaling, received before the data packets, on this second frequency band.
• the data packets transmitted on the first frequency band are destined for a "legacy” station, no specific signaling is transmitted on the first frequency band, and the "legacay" station is not informed of simultaneous transmission of packets on a second frequency band to another equipment.
• the reception method comprises a step of receiving at least one specific preamble transmitted on the first and / or second frequency band (s), and the decoding step is implemented either on the transmitted packets on the first frequency band, ie on the packets transmitted on the second frequency band, as a function of at least one simultaneous emission indicator present in the specific preamble or preambles.
• the data packets transmitted on each of the reserved frequency bands are preceded by a specific preamble, so as to inform the destination equipment of the frequency band intended for them.
• the destination equipment only decodes the packets intended for them.
• the reception method comprises a step of transmitting, on one of the radio frequency channels comprising the first frequency band, denoted primary channel, an acknowledgment of reception of a packet transmitted on the second Band frequency, the step of transmitting an acknowledgment being implemented after detecting a reception acknowledgment of a transmitted packet simultaneously on the first frequency band.
• the receiving equipment transmitted packets on the second frequency band transmits an acknowledgment of receipt of these packets on the primary channel to the access point.
• the transmission of this acknowledgment by the destination equipment is implemented after detection of the transmission of the acknowledgment corresponding to the reception of the transmitted packets simultaneously on the first frequency band.
• the access point first receives the acknowledgment of reception of the packets transmitted on the first frequency band, then the acknowledgment of reception of the packets transmitted on the second frequency band, whatever the size of the packets. transmitted on the second frequency band.
• This mechanism thus allows an acknowledgment management independent of the frequency bands and the size of the packets transmitted on these frequency bands.
• the invention also relates to a recipient equipment for receiving data packets in a communication network using a plurality of radio frequency channels, at least two of the radiofrequency channels being concatenated to form a concatenated channel.
• such recipient equipment, or station comprises:
• the means for receiving data packets transmitted simultaneously on a first and a second frequency band the first frequency band being formed of at least one of the radiofrequency channels of the concatenated channel and the second frequency band being formed of the radiofrequency channels of the non-reserved concatenated channel;
• Such equipment is particularly adapted to implement the reception method described above.
• This is for example a station of a set of basic services, in the case of wireless transmission.
• This equipment can of course include the various characteristics relating to the reception method according to the invention. Thus, the features and benefits of this equipment are the same as those of the receiving method, and are not detailed further.
• Another aspect of the invention relates to a multicarrier signal transmitted in a communication network using a plurality of radiofrequency channels, wherein at least two of the radio frequency channels are concatenated to form a concatenated channel.
• such a signal carries data to a first destination equipment on carriers belonging to a first frequency band and data to a second destination equipment on carriers belonging to a second frequency band.
• the first frequency band being formed of at least one of the radiofrequency channels of the concatenated channel and the second frequency band consisting of other radiofrequency channels of the concat channel.
• such a signal carries at least one simultaneous emission indicator on the first and second frequency bands.
• Such a signal can be generated by the transmission method described above.
• the invention also relates to a computer program comprising instructions. for carrying out a transmission method or reception method as previously described when this program is executed by a processor.
• Figure 2 shows the main steps of the transmission method according to one embodiment of the invention
• Figures 3a and 3b show an example of the channel access mechanism according to one embodiment of the invention.
• FIGS. 4a and 4b describe two signaling examples according to embodiments of the invention.
• FIG. 5 illustrates an example of a simplified structure of an access point according to one embodiment of the invention
• FIG. 6 presents the main steps of the reception method according to one embodiment of the invention.
• FIGS. 7a and 7b describe two examples of acknowledgment mechanism according to embodiments of the invention.
• FIG. 8 illustrates an example of a simplified structure of a recipient equipment according to one embodiment of the invention.
• the general principle of the invention is based on the simultaneous transmission of data packets, destined for two recipient equipments, on two frequency bands, each formed of at least one radiofrequency channel of a concatenated channel, thus enabling optimize the concatenated channel occupancy.
• a concatenated channel is a channel corresponding to the concatenation of several radio frequency channels, used for multi-channel transmission.
• the transmission method comprises a first step 21 of acquiring and reserving a first frequency band, denoted FBI, for the transmission of data packets to a first destination equipment.
• This first frequency band is composed of at least one radiofrequency channel of a concatenated channel.
• the radiofrequency channels of the non-reserved concatenated channel are reserved in the first step, that is to say not included in the FBI frequency band for transmitting data packets to at least a second destination equipment.
• a third TX transmission step 23 consists in sending simultaneously on the first frequency band FBI and the second frequency band FB2 data packets destined to the first and second destination devices respectively.
• all of the radiofrequency channels forming the concatenated channel are used to simultaneously transmit data packets to two or more recipient devices.
• the principle of the invention is based on the simultaneous reception of packets on the first and second frequency bands and on the decoding of the packets on one or the other of these two frequency bands as a function of a signaling received on one and / or the other of the frequency bands.
• the left side represents queues and packets stored waiting for transmission by the access point
• the right side represents the packets being transmitted.
• the packages shown with stripes on the left side are those that have been selected for the transmission shown on the right side.
• FIG. 3a it is considered that the first packet in the access point queue must be transmitted over a frequency band of 20 MHz to a "legacy" station.
• a second frequency band, composed of the channel 2 is used for the transmission of other packets to a destination equipment "HT". Acquisition and reservation are effected, according to this embodiment of the invention, by listening to the channel 2 for a duration called "PIFS", ending at the same time as the listening time ("AIFS + B") of the channel 1, as already described above.
• the access point is informed if the primary channel 1 and secondary channel 2 are free or busy, even if the next packet to be transmitted is destined for a "Iegacy" station and therefore to be transmitted only on the primary channel 1 (20MHz).
• the channel 1 When the channel 1 is free, it is used for the transmission of this packet to a "HT" station, and, according to the invention, a second frequency band, composed of the channel 2, is used for the transmission of other packets to another "HT” station. Acquisition and reservation are performed, according to this embodiment of the invention, listening to the channel 2 for a duration called "PIFS", ending at the same time as the listening time ("AIFS + B") of channel 1, as already described above.
• the access point is informed if the primary channel 1 and secondary 2 are free or busy, even if the next packet to be transmitted to a station "HT" requires only 20 MHz.
• a packet destined for a first "HT” station denoted “HT1 20 MHz” is transmitted on the channel 1, simultaneously with the emission of a packet destined for a second "HT” station, denoted “HT2 20 MHz”, on the channel 2.
• the transmission method provides for selecting the packet or packets that can be transmitted on the second frequency band, destination of a "HT" station.
• the second frequency band reserved and in particular its width, that is to say the number of radio frequency channels which form it (for example two or three 20 MHz channels of a concatenated channel formed through four 20 MHz radio frequency channels)
• some packets waiting in the access point queues are more or less appropriate to be transmitted on this second frequency band.
• the mechanism for selecting a packet to be transmitted on the second frequency band, simultaneously with the transmission of a packet on the first frequency band consists first of all in selecting a set of packets intended for "HT" stations. , thus “eliminating” the packets destined for "legacy” stations, which stations can not implement the invention, and consequently can not receive packets on the second frequency band reserved according to the invention.
• this transmission duration T is calculated by taking into account the characteristics of the second frequency band (20 MHz in the examples of FIGS. 3a and 3b).
• the set of packets comprises only packets of transmission duration T which is much smaller than that of the packet transmitted on the first frequency band
• it is possible to implement a packet aggregation for example using aggregation techniques defined in the IEEE 802.11 ⁇ standard, so as to "fabricate" an aggregated packet whose transmission duration is close to that of the packet transmitted on the first frequency band, while remaining lower.
• This selection criterion based on the transmission duration makes it possible to optimize the use of the concatenated channel's radio frequency channels.
• a single packet must be chosen to be effectively transmitted on the second frequency band simultaneously with the packet transmitted on the first frequency band.
• Another selection is therefore implemented, applying at least one selection criterion a criterion taking into account the data type of the packet, or the class of service to which the packet belongs. For example, a package of the type "Best Effort", or “Background”, is less of a priority than a "Voice” type packet, requiring a real-time transmission, or a "Video” type packet, requiring a high quality transmission.
• These classes of service are for example reported in the Cham "Qos control / TE ) " of the MAC header ⁇ 7.1.3.5 of the 802.11e standard.
• Such a criterion is especially chosen when one wants to privilege the quality of service compared to the flow.
• a criterion taking into account the duration of transmission of the packet, relative to a predetermined transmission rate (for example a transmission over 20 MHz with a particular modulation), making it possible to determine a penalty factor associated with a packet, representing an estimated occupation of the channel for the transmission of this packet.
• a criterion may consist in choosing the package that would penalize the other recipient equipment the most, if it were transmitted in a "conventional" manner, for example using only a 20 MHz frequency band.
• Fpl ⁇ Pi for a packet Pi, corresponding to the total time of occupation of the channel by the packet, noted T (Pi).
• This time T ⁇ Pi) is calculated taking into account the frequency band conventionally used (for example 20 or 40 MHz according to the packets) and the transmission rates envisaged by the access point for transmitting this packet Pi, as well as the transmission of the physical layer headers of the communication network (the latter being organized into a plurality of communication layers comprising a data link layer, called MAC layer, delivering data packets to a physical layer, called PHY layer ) and acknowledgments of receipt of the packets.
• MAC layer data link layer
• PHY layer physical layer
• a criterion corresponding to a combination of the two preceding criteria that is to say taking into account both the priority of the packet and its total time of occupation of the channel, noted T (Pi).
• a penalty factor Fp2 (Pi) corresponding to an average of the temporal occupation T (Pi) and the priority of the packets.
• the temporal occupation T (Pi) is calculated taking into account the frequency band conventionally used (for example 20 or 40 MHz depending on the packets) and the transmission rates envisaged by the access point for transmitting this packet Pi, as well as transmission of headers of the physical layer of the communication network and acknowledgments of receipt of the packets.
• Such a criterion is particularly chosen when one wants to privilege an intermediate approach between the quality of service and the flow.
• the data destined for the "legacy” station is placed on the sub-carriers corresponding to the primary channel 1 and the data intended for the "HT" station on the sub-carriers corresponding to the secondary channel 2, as illustrated in Figure 4a.
• Preambles specific to the "HT" station denoted HT-S, HT-STF and HT-LTFs
• HT-S Preambles specific to the "HT" station
• HT-STF Preambles specific to the "HT" station
• HT-LTF Preambles specific to the "HT" station
• L-STF Preambles specific to the "HT” station
• L-LTF Preambles specific to the "HT-S, HT-STF and HT-LTFs
• these preambles notably comprise a "simultaneous transmission" field in the HT-S signaling that a simultaneous transmission is active. In this way, the "HT" station receiving the data on the second frequency band is informed of the simultaneous transmission.
• a field in the HT-SIM also signals the order of the simultaneous transmission, that is to say that the simultaneous transmission is implemented on the channel 2, knowing that the radiofrequency channel used to form the first frequency band for transmission to a station "legacy Is noted channel 1.
• a field in the HT-SIM makes it possible to signal the channels used by the simultaneous transmission, for example the channel 2 (if the concatenated channel comprises only two radio frequency channels) or the channels 2 to 4 (if the channel concatenated comprises four radiofrequency channels forming the second frequency band are used for transmission to a station "HT" implementing the invention.
• FFT dual size Fourier transform
• the same preambles as on the secondary channel according to the technique similar to the "duplicate mode" described above.
• the field in the HT-SIM also makes it possible to signal an identifier of a recipient device "HT", so that it can be informed of the packets intended for it.
• This identifier is for example the "AID” (of the English “Association Identify ”) of the station or a hash function between Y" AID “and the” BSSID "(Basic Service Set Identifier).
• an additional field noted for example "destination”, indicating the identifier of the destination station.
• the same preambles as on the secondary channel according to a technique similar to the duplication technique of the 802.11 ⁇ standard, called "duplicate mode", making it possible to duplicate the signal transmitted on the primary channel in the secondary channel by using a dual-size FFT and copying the data transmitted on the sub-carriers corresponding to the primary channel to the sub-carriers corresponding to the secondary channel;
• the same preambles as on the secondary channel according to the technique similar to the "duplicate mode" described above.
• the identifier of the destination station is signaled in the preambles, it is informed upon receipt of these preambles that the packets transmitted on the second frequency band are intended for it, and can therefore from that moment decode only the packets transmitted on this second frequency band.
• the identifier of the destination station when the identifier of the destination station is not signaled in the preambles, it must decode both the data transmitted on the first frequency band and those transmitted on the second frequency band, because the Destination information is only present at the level of the MAC layer and therefore accessible only after decoding of the PHY layer.
• the data destined for the first station "HT1" are placed on the sub-carriers corresponding to the primary channel 1 and the data destined for the second station "HT2" on the sub-carriers corresponding to the secondary channel 2, as illustrated in Figure 4b.
• Preambles specific to the first "HT1" station denoted HT-SM, HT-STF and HT-LTFs
• HT-SM Preambles specific to the first "HT1" station
• HT-STF Preambles specific to the first "HT1" station
• HT-LTFs Preambles specific to the first "HT1" station
• L-STF the "legacy” signaling preambles
• preambles specific to the second station "H.T2" denoted HT-SM, HT-STF and HT-LTFs, are emitted on the primary channel, after remission of the signaling preambles "legacy".
• the identifier of the destination station of the transmission HT2
• the emission of preambles specific to the station "HT1" with in the HT-SM the field corresponding to the primary channel set to 1, the field corresponding to the secondary channel set to 1 and the fields corresponding to the tertiary channels and quaternary set to 0, the field “simultaneous transmission” set to 1, and the field “destination” set to "HT1";
• the tertiary channel 3 the emission of preambles specific to the station "HT2" with in the HT-SM the field corresponding to the primary and secondary channels set to 0 and the fields corresponding to the tertiary and quaternary channels set to 1, the "simultaneous transmission” field set to 1, and the "destination” field set to "HT2"; on the quaternary canal 4: a duplication of the preambles of the tertiary canal. Once these preambles have been transmitted, the actual data is transmitted on the reserved frequency bands.
• FIG. 5 illustrates an example of a simplified structure of an access point according to one embodiment of the invention, for example for a simultaneous transmission of PI and P2 packets of data respectively on a primary channel 1 destined for an first destination equipment and on a secondary channel 2 to a second destination equipment.
• the generation of data and preambles is independent between the two primary channels 1 and 2.
• the means for generating data and preambles 51 for the packet PI transmitted on the primary channel are distinct from the means for generating the data and preambles 52 for the P2 packet sent on the secondary channel.
• the physical layer transmission means 53 are partially shared, as illustrated in FIG. 5, in particular as regards the binary to symbol coding, the OFDM modulation.
• the transmission means 53 can also be completely independent.
• Such an access point also comprises means for acquiring and reserving the frequency bands, implemented before the generation means 1 and 52.
• a first reception step 61 the data packets transmitted simultaneously on the frequency bands FBI and FB2 are received, and in particular signaling information enabling the destination equipment implementing the reception method according to this mode. realization of knowing on which frequency band are sent the packets intended for it.
• the signaling information is processed, and the packets PI received on the frequency band FBI or the packets P2 received on the frequency band FB2 are decoded, during a step 631 or 632 of decoding, depending on the signal received.
• decoding steps 631 and 632 are implemented on one or the other of the frequency bands FBI or FB2.
• the signaling indicates an identifier of the recipient device
• the latter is then informed of the packets intended for it and can decode the packets on the frequency band which concerns it, by not treating the packets received on the other frequency band.
• the signaling indicates that a simultaneous transmission is active, without identifying the destination equipment concerned, each device must implement decoding at the MAC layer to know which packets are intended for it.
• This particular situation of the invention has particularities related to the fact that the duration of transmission of the packets on each of the two frequency bands is not necessarily the same and that the transmission characteristics (modulation, coding, ... ) can be different and therefore the acknowledgments of reception of the packets, emitted by each of the destination stations, can also be of different sizes.
• the invention therefore provides a specific mechanism for managing the reception acknowledgments of the packets transmitted by each of the destination stations, making it possible to transmit, on the primary channel only, the acknowledgments of reception of the packets transmitted on the two frequency bands, such as illustrated in Figures 7a and 7b.
• the reception acknowledgments are sent on the primary channel in a predetermined order corresponding to the ascending order of the channels in the concatenated channel. For example, the reception acknowledgment of packets on the primary channel is transmitted first, then that of the packets received on the secondary channel, and so on for the tertiary and quaternary channels in the case of a concatenated channel of 80 MHz .
• the "HT" station receiving packets on the second frequency band listens to the primary channel as soon as the second frequency band is released, at the end of the transmission of a packet, in order to detecting the end of the transmission of the acknowledgment of reception of the packet on the primary channel.
• This detection is based for example on the short interframe, denoted SFIS, for "Short inter Frame Spacing" in English.
• the "HT" station can then transmit the acknowledgment corresponding to the reception of the packet on the second frequency band.
• FIG. 7b illustrates more particularly the case where the transmission duration of the packet transmitted on the second frequency band is less than that of the packet transmitted on the primary channel.
• the second frequency band is released at the end of transmission, without the need for the transmission of stuffing packets to match the transmission time of the packet on the second frequency band with that of the packet transmitted on the second frequency band. first frequency band.
• FIG. 8 illustrates an example of a simplified structure of a destination equipment according to one embodiment of the invention, for example for receiving data packets sent simultaneously on a primary channel 1 to a first destination equipment and on a secondary channel 2 to a second destination equipment.
• a recipient equipment embodying the invention for example a "HT" station, to which packets are transmitted on the secondary channel 2.
• a "HT" station to which packets are transmitted on the secondary channel 2.
• LTF as well as channel estimation means 82 are shared between the two channels 1 and 2.
• separate means 831 and 832 for processing the L-GIS signaling information are implemented for each of the channels I and 2. Indeed, as already described above, preambles specific to the "HT" station are transmitted on the EB2 frequency band, while “legacy” preambles are transmitted on the FBI frequency band (if the packets transmitted on this frequency band are destined for a "legacy” station).
• the means implemented for the reception of the packets on each of the two frequency bands thus, that the decoding means, are distinct.
• separate data detection means 841 and 842 are implemented for decoding purposes.
• the data received on the secondary channel are stored in a buffer, for subsequent processing.
• a destination equipment is directly designed to receive data transmitted according to the invention, in which case the signaling information is not necessary.

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• 2011
  • 2011-03-04 WO PCT/FR2011/050455 patent/WO2011110778A1/fr active Application Filing
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