Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
  • H04W52/04—TPC
  • H04W52/18—TPC being performed according to specific parameters
  • H04W52/24—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters
  • H04W52/245—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters taking into account received signal strength
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
  • H04W4/80—Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
  • H04W52/04—TPC
  • H04W52/30—TPC using constraints in the total amount of available transmission power
  • H04W52/36—TPC using constraints in the total amount of available transmission power with a discrete range or set of values, e.g. step size, ramping or offsets
  • H04W52/362—Aspects of the step size
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
  • H04W52/04—TPC
  • H04W52/30—TPC using constraints in the total amount of available transmission power
  • H04W52/36—TPC using constraints in the total amount of available transmission power with a discrete range or set of values, e.g. step size, ramping or offsets
  • H04W52/367—Power values between minimum and maximum limits, e.g. dynamic range
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W76/00—Connection management
  • H04W76/10—Connection setup

Definitions

• the present invention relates to the field of telecommunications. Within this field, the invention relates more particularly to WiFi networks and home or public gateways having an access point to a WiFi network and WiFi terminals.
• a WiFi network uses in particular wireless transmission technology based on the IEEE 802.11 radio network standard and its developments commonly referred to as WiFi (for "Wireless Fidelity").
• WiFi for "Wireless Fidelity”
• the latest developments in the IEEE 802.11 standard are moving towards increasing the density of WiFi terminals and access points in a small area. Such a context requires adequate mechanisms to serve customers fairly with a limited spectral resource.
• the WiFi spectrum is split into twelve channels, only three of which are totally disjointed.
• a function of a gateway is to provide the interface between the client terminal and a broadband network, most often fixed, for example ADSL type for a private gateway.
• the gateway comprises at least one WiFi access point to the broadband network.
• a gateway also provides modem and router functions.
• the access point is set to one of the different WiFi channels of the band in question (2.4GHz, 5GHz, etc.).
• Each station, access point or client terminal that has information to be transmitted contributes to the access to the channel during the contention phases.
• the station listens to the channel during this contention phase. If no signal is detected during a preset and station-specific backoff delay, the station may start transmitting on the channel at the end of its time countdown.
• This mechanism is based on the CCA function "clear channel assesment" which, on each station, indicates whether the channel is busy or free.
• the CCA threshold corresponds to a power threshold. If the signal received is greater than this threshold, the channel is busy, otherwise the channel is free.
• These thresholds are set by the 802.11 standard. There are currently two types of threshold, one type for the detection of energy only and a type for WiFi signal detection (lower by 20dB thanks to PLCP preamble detection in physical layer).
• the IEEE 802.11 standard has set these CCA thresholds to be as low as possible to fully protect current transmissions. These CCA thresholds always have a negative value expressed in dBm.
• the 802.11 standard defines the Transmit Power Control (TPC) and Clear Channel Assesment Control (CCAC) mechanisms, also called DSCs illustrated in FIG. 1.
• TPC Transmit Power Control
• CCAC Clear Channel Assesment Control
• the adaptation of the transmission power or TPC consists in reducing the transmission power of all the AP stations and access points in a given area. As a result, the protection area of each station is reduced and the interference level CCI ("Co Channel Inteference") between same channels of different cells decreases. Therefore, this allows simultaneous transmissions into adjacent cells of a cell using the same WiFi channel.
• CCI Co Channel Inteference
• the TPC mechanism is conventionally used in cellular networks that operate according to a centralized organization.
• a base station synchronously and sequentially serves the client terminals.
• This mechanism works very well but it only benefits neighboring stations from those that implement the TPC mechanism. For a station to benefit from the TPC mechanism, it is sufficient for the neighboring stations to implement.
• This mechanism is compatible with the WiFi standard and can be used by WiFi stations. However, since it only benefits neighboring stations from those that implement the TPC mechanism, the stations do not implement.
• the TPC mechanism is not aggressive enough since the one that does not implement the solution is favored.
• the second mechanism or CCAC is to raise the CCA threshold for all APs and APs in a given area. The protection zone is also reduced by this mechanism.
• This mechanism is more suitable than the TPC mechanism for a WiFi context since it generates the same effects as illustrated by FIGS. 2a and 2b which represent the flow as a function of time. But this CCAC mechanism favors stations that implement the mechanism.
• the improvement of the use of the spectral resource in a context of densification must also take into account the presence of so-called legacy station. These stations are from previous generation that is to say compatible from an earlier version of the WiFi standard to the version normalizing the used mechanism considered.
• legacy stations do not reduce the bit rates of stations implementing CCA control, nor reduce spectrum reuse.
• the total throughput is therefore very high as illustrated in FIG. 3b, which represents the flow as a function of time for a mixture of legacy stations and stations implementing CCA control.
• these legacy stations often find themselves in situation of lack ("starvation"): they do not manage to reach the channel being largely disadvantaged. There is therefore a problem of equity between the stations implementing the CCAC and the stations that do not implement.
• the present invention is placed in a context of dense occupation by stations
• the present invention provides a method for determining thresholds to improve spectrum reuse while ensuring equal channel access between stations whether they are of the same generation or different generations.
• the method of using threshold values of WiFi signals comprises the step of:
• a WiFi transceiver pair consists of two stations that communicate via an ad hoc network or consists of an access point and a client terminal associated with it and which communicates with this access point.
• the joint use therefore relates to the communication channel between the transmitter and the receiver. Either the use is joint between the two stations, the transmitter decreases its transmitted power by a first value and the receiver decreases its reception sensitivity by a second value. Either the decrease of the transmitted power of a first value and the decrease of reception sensitivity of a second value are used jointly by the same station, the transmitter or the receiver.
• CCA reception sensitivity threshold
• the decrease of the transmission power together with the increase of the CCA threshold by one of the stations of the couple thus offers more chance of access to the channel to the legacy stations of the given area considered that always transmit with maximum power.
• the method thus makes it possible to restore equity between the stations. Joint use therefore makes it possible to increase the spatial re-use of the spectrum.
• the given area is defined by a transmitter-receiver pair, by several access points and their associated stations or by one or more sets of basic services (in English BSS for "basic service set").
• a set of basic services (BSS) is formed by an access point and the stations associated with this access point, that is, say the stations located in the WiFi cell or coverage area of this access point. These stations are client terminals.
• client terminal means any device capable of communicating with a WiFi access point, such as a laptop, a device of the PDA ("Personal Digital Assistant") type, a Smart Phone, etc.
• PDA Personal Digital Assistant
• the method is such that the WiFi station transceiver pair belongs to a zone determined by a number of access points determining as many basic service sets (BSS) as there are points of access. access.
• the method is such that the first value is linked to the second value by a multiplicative coefficient.
• the method is such that the transceiver pair of WiFi stations is formed of an access point and a client terminal associated with this access point.
• the method is such that the first transmitted power reduction value is determined by the client terminal and used by the access point and the second increase value of the reception sensitivity threshold is used by the client terminal.
• the method is such that the first transmitted power reduction value is determined by the access point and used by the client terminal to reduce its transmission power and the second threshold increase value.
• reception sensitivity is used by the client terminal.
• the method is such that the access point defines a basic service set, the access point transmits a request to the stations of the basic service set to use the first service set. Emitted power reduction value determined by the access point.
• the method is such that the first transmitted power reduction value and the second increase value of the reception sensitivity threshold determined by the client terminal are used by this client terminal.
• the method furthermore comprising the step consisting in determining, by one of the WiFi stations of the transceiver pair, a remaining margin of occupation of a WiFi communication channel of the torque based on a power received in this connection. channel, the determined value being equal to the remaining margin.
• the remaining margin is the sum in dB of the CCA change from the normalized threshold and the change in transmit power from the normalized one.
• the method is such that the transmitter is an access point and the station is a client terminal, the power received in the channel is calculated from the power of the Beacon beacon transmitted by the point. to which the station is associated.
• the method is such that when the station is a client terminal, the power received in the channel is calculated from the transmission of data by the access point of the transceiver pair. According to a particular embodiment, the method is such that when the station is an access point, the power received in the channel is calculated from the transmission of data from the client terminal of the transceiver pair.
• the invention relates to a WiFi station of a basic service package.
• the WiFi station includes:
• Figure 1 illustrates the TPC and CCAC mechanisms.
• Figure 2a shows the flow as a function of time for different modes of transmission without or with implementation of a TPC.
• Figure 3a shows the flow versus time for different modes of transmission without or with implementation of a TPC for a mix of legacy stations and stations implementing the TPC.
• FIG. 4 represents the given area delimited by a determined number of AP access points.
• Figure 5 is a diagram of an embodiment of a method according to the invention.
• Figure 6 is a diagram of an embodiment of a method according to the invention.
• Figure 7 is a diagram of an embodiment of a method according to the invention.
• FIGS. 10a, 10b and 10c are distribution curves (CDF) of uplink (UL) and downlink (DL) flows originating from either legacy stations or stations which apply the method according to the invention, obtained by simulation.
• CDF distribution curves
• a WiFi access point includes various parameters including one that identifies a WiFi cell, this parameter is known to those skilled in the art under the abbreviation SSID (for "Service Set Identifier"). Each cell differs by its SSID and defines an access point in the sense of the invention.
• SSID Service Set Identifier
• an access point regularly broadcasts a radio beacon frame to manifest its presence, this frame is known to those skilled in the art under the abbreviation Beacon.
• This frame contains the SSID set for the access point.
• a station When a station wants to establish a communication via a WiFi access point, it must in a first step to discover such an access point. This discovery is made either by passive listening by scanning the radio band to detect the presence of Beacon and therefore a gateway with access point nearby, or by an active search by probing the channels of the radio band by the issuing an "probe request" frame.
• the station may subsequently issue an "probe request” request addressed to the detected access point by using the SSID of this access point to obtain additional information that is not broadcast in the "beacon" tag.
• the SSID access point responds with an "probe response" frame indicating the transmission capacities of the gateway, especially considering the number of users already connected to the gateway.
• the access point if it exists, responds with an "probe response" frame.
• the station and the access point In a second step, the station and the access point generally perform mutual identification.
• An association step is then necessary for the station to send data via the access point, typically to a remote recipient.
• the station When the station is a client terminal, preferably it is already associated with an access point before implementing the method according to the invention.
• the station forms a transceiver pair with the access point.
• the station is part of a BSS set associated with the access point. This set is part of the given area delimited by a determined number of access points AP. This zone is illustrated in FIG. 4. This determined number of access points is for example those present in an auditorium, a stadium, etc.
• the station calculates the remaining margin Delta_X of occupation of the WiFi channel, that is to say of the channel on which it is associated with the AP access point.
• the remaining margin is determined as the difference between the received power Rx_power by the station minus a predefined margin M.
• the received power is determined for example with respect to the Beacon frame received from the access point with which the station is associated.
• This predefined margin M is for example specified by the standard in the form of a standardized threshold CCA_norme or in the form of an adjustable parameter M (for example 20 dB).
• the transmitted power reduction of a delta_TPC value and the increase of the reception sensitivity threshold of a delta_CCA value are used jointly within the access point-station pair. This joint use respects the constraint that the sum of the two values delta_TPC and delta_CCA is bounded by the remaining margin.
• the value delta_CCA is equal to the value delta_TPC multiplied by a factor. According to a particular mode, this factor is equal to one.
• the station transmits with the reduced normalized power of delta_TPC. And during any reception, the station increases its sensitivity threshold of reception of the delta_CCA value with respect to a threshold level (CCA) of normalized reception sensitivity.
• CCA threshold level
• the station When the station is an access point, it can implement the method according to the invention in a manner similar to the station. This particular implementation is illustrated by the scheme of FIG. 6. The difference in implementation comes from the manner of determining the received power level.
• the access point determines the received power Rx_power for example with respect to a data frame or a control frame received from a station. Preferably when several stations are associated with the same access point, it selects the lowest received power between the various stations associated with it.
• the value delta_TPC determined by the client terminal station is used by the access point with which it is associated.
• the delta_CCA value determined by the client terminal station is used by this client terminal.
• the client terminal after determining the delta_TPC value, the client terminal sends a request to the access point for it to increase its transmission power of the delta_TPC value that it transmits to it.
• the latter adapts its transmitted power by using at each transmission the value delta_TPC of the receiving client terminal or it can select a value from the values of delta_TPC which are brought back to it from the associated client terminals. The selection may consist of retaining the smallest value.
• the client terminal of a set BSS determines the values delta_CCA and delta_TPC and requests the access point to reduce its transmission power of the latter delta_TPC via a control frame.
• the access point acknowledges the request based on its capabilities. For its part, the access point can determine a delta_TPC value and require the client terminal to lower its transmission power of this delta_TPC value that it transmits to it via a control frame.
• the method is centrally conducted.
• the access points of the zone are connected to a controller and / or they exchange control frames with each other.
• a typical example of a centralized high-density network is that for example that equips an auditorium, a stadium.
• the access points APs located in the given area are controlled by a central entity (controller) which deals with any kind of configuration and administration of the managed network to which these APs belong.
• the controller can collect from its APs for example in an active manner ("probing") information concerning the status of the WiFi channels used by each AP.
• This deployment scenario is similar to a cellular deployment: the selection of a WiFi channel and the placement of APs are optimized to effectively serve a number of users.
• the AP controller has information on the optimal settings to use to achieve the maximum throughput per user.
• An algorithm for optimizing the threshold values can therefore be centralized or partially centralized at the level of the controller that communicates and configures the different APs.
• the controller communicates to the APs the optimal threshold values to be used at ⁇ and the optimal threshold values to be transmitted to the STA stations connected to it.
• the determination of the values of the thresholds is made according to one of the modes previously described.
• the controller or one of the access points can then determine optimal values for the thresholds by applying certain rules.
• One of the rules can be to set the second delta_CCA threshold value to a constant.
• the process takes place in a decentralized manner at the initiative of each station in the area.
• the determination of the values of the thresholds is made according to one of the modes previously described.
• a typical example of an uncontrolled high network Density is the one encountered in a university residence and made up of students' bridges.
• Such an STA station comprises a memory Mem_R comprising a buffer memory, a processing unit ⁇ _ ⁇ equipped for example with a microprocessor and driven by a computer program Pg_R implementing a method for determining threshold values of WiFi signals according to the invention.
• the code instructions of the computer program Pg_R are for example loaded into a RAM before being executed by the processor of the processing unit ⁇ P_R.
• the processing unit ⁇ P_R receives as input signals transmitted in a WiFi channel.
• the microprocessor of the processing unit ⁇ P_R implements a method for determining WiFi signal threshold values described above, according to the instructions of the computer program Pg_R.
• the station comprises a calculator for determining a remaining margin Delta_X occupancy of the WiFi channel based on a received power Rx_power in this channel and a means for jointly using a reduction of transmitted power of a first threshold value delta_TPC and an increase in the reception sensitivity threshold of a second delta_CCA threshold value, the sum of the two threshold values being limited by the remaining margin.
• These means are controlled by the microprocessor and are part of the processing unit ⁇ P_R.
• the steps of the method for determining threshold values of WiFi signals according to the invention are determined by the instructions of a program incorporated in an electronic circuit such as a chip itself which can be arranged in an electronic device such as a client terminal and / or access point.
• the method for determining threshold values of WiFi signals, according to the invention can equally well be implemented when this program (or its modules) is loaded into a computing device such as a processor or equivalent whose operation is then controlled by the execution of the program.
• the invention also applies to a computer program (or its various modules), including a computer program on or in an information carrier, adapted to implement the invention.
• This program can use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code such as in a partially compiled form, or in any other desirable form for implementing a method according to the invention.
• the information carrier may be any entity or device capable of storing the program.
• the medium may comprise storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording medium, for example a floppy disk or a disk. hard.
• the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question.
• the program may be translated into a transmissible form such as an electrical or optical signal, which may be routed via an electrical or optical cable, by radio or by other means.
• a transmissible form such as an electrical or optical signal
• the program according to the invention can be downloaded in particular on an Internet type network.
• FIGS. 10a, 10b and 10c show the curves obtained by the distribution simulations (CDF) of the uplink (UL) and downstream (DL) flows originating from either the legacy stations or the stations which apply the method according to FIG. invention.

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• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)

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• 2014
  • 2014-09-11 FR FR1458554A patent/FR3025966A1/fr not_active Withdrawn
• 2015
  • 2015-09-08 US US15/504,143 patent/US20180338233A1/en not_active Abandoned
  • 2015-09-08 CN CN201580048574.9A patent/CN106688285A/zh active Pending
  • 2015-09-08 EP EP15778358.0A patent/EP3192313A1/de not_active Withdrawn
  • 2015-09-08 WO PCT/FR2015/052382 patent/WO2016038295A1/fr active Application Filing

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