RU2291589C2 - METHOD FOR TRANSFERRING DATA IN WIRELESS LOCAL NETWORK IN ACCORDANCE TO IEEE 802.11b STANDARD - Google Patents

Abstract

FIELD: radio engineering, in particular, data transfer method in wireless local network, possible use, for example, in wireless local data transfer networks in accordance to standard IEEE 802.11b.

SUBSTANCE: prior to transmission of each data block, such data transfer mechanism is selected as well as optimal size of fragment for it and optimal transfer speed, which maximize capacity of network with consideration of signal-noise ratio in signal of transferring station and with consideration of current load on network.

EFFECT: increased capacity of wireless local network in acc to standard IEEE 802.11b.

19 cl, 5 dwg

Description

The invention relates to the field of radio engineering, in particular to a method for transmitting data in a wireless local area network, and can be used, for example, in wireless local area networks for data transmission according to the IEEE 802.11b standard.

The IEEE 802.11b standard is a widely used standard that describes a wireless local area network (see IEEE standard for Wireless LAN Medium Access Control and Physical Layer specifications, ANSI / IEEE Standard 802.11, 1999 [1]; IEEE standard for Wireless LAN Medium Access Control and Physical Layer specifications: higher-speed physical layer extension in the 2.4 GHz band, IEEE Standard 802.11b, 1999 [2]).

Consider some of the main features of the standard that are necessary for a better understanding of the claimed invention.

The physical layer of the IEEE 802.11b standard provides four transmission speeds: 1, 2, 5.5 and 11 Mb / s. The noise immunity characteristics of the physical layer of the IEEE 802.11b standard are completely determined by the dependences of the probability of bit error on the signal-to-noise ratio (SNR).

The data blocks arriving at the MAC level (MAC - medium access control) are divided into one or more fragments before transmission. A fragment of a data block cannot be more than 18432 bits. To transmit each fragment of the data block, a separate data packet is formed. The data packet (FIG. 1) consists of a MAC header, a fragment of a data block and a checksum and is transmitted at one of four transmission rates. Before each data packet at a transmission rate of 1 Mbit / s, a preamble and a physical layer header are transmitted, with a total duration of 192 μs.

The work of wireless local area networks according to the IEEE 802.11b standard is based on competitive access to the transmission medium. A station that has a data block for transmission must determine the current state of the transmission medium. If the station detects that the transmission medium is free for a time interval equal to the base interval between packets, then it starts transmitting data. If the station detects that the transmission medium is busy, then it must delay transmission until the transmission medium is found to be free for a time interval equal to the basic interval between packets. Thus, the station avoids collision when the transmission medium is busy.

The transmission of the data packet begins with the interval of competitive access (figure 2). The start of the concurrent access interval is the same for all stations having a data block for transmission. Each of them randomly selects the duration of their competitive access interval as a value of a random variable uniformly distributed within specified limits. Access to the transmission medium is obtained by the station that has chosen the interval of the shortest duration. She begins the transmission of her data packets, having previously waited for her interval of competitive access.

In the IEEE 802.11b standard, concurrent access interval is measured in slots. We will call the interval of the smallest duration (figure 2) the number of free slots between two consecutive transfers in the system.

If the interval of the shortest duration coincided with two or more stations, then they begin to transmit their data packets simultaneously. In this case, a collision occurs, i.e. overlay of their data packets in time. In a collision, most likely none of the data packets will be accepted.

For the transmission of any data packet, the IEEE 802.11b standard provides two mechanisms (options) for data transfer: the main data transfer mechanism and the data transfer mechanism with a preliminary transfer request.

When using the main data transfer mechanism, the following data transfer sequence is used (FIG. 3). A station that has won competitive access starts transmitting a data packet immediately after the end of its competitive access interval. If the data packet is successfully received at the receiving station, the receiving station transmits an acknowledgment at a time interval equal to the short interval between packets. In case of successful reception of acknowledgment at the transmitting station, the data packet was received successfully.

When using the data transfer mechanism with a preliminary transfer request, the following data transfer sequence is used (Fig. 4). A station that has won competitive access starts transmitting a transfer request at the end of its competitive access interval. If the transmission request is successfully received, the receiving station transmits the transmission permission at a time interval equal to the short interval between packets. In case of successful reception of a transmission permit, the transmitting station transmits a data packet at a time interval equal to the short interval between packets. If the data packet is successfully received at the receiving station, the receiving station transmits an acknowledgment at a time interval equal to the short interval between packets. In case of successful reception of acknowledgment at the transmitting station, the data packet was received successfully.

The probability of successful reception of a data packet depends on the probability of collision in the system, determined by the current number of active stations in the system (Giuseppe Bianchi, "IEEE 802.11 - saturation throughput analysis," IEEE Commun. Lett., Vol.2, no.12, pp.318- 320, December 1998 [3]; Giuseppe Bianchi, "Performance analysis of the IEEE 802.11 distributed coordination function," IEEE J. Select. Areas Commun., Vol. 18, no. 3, pp.535-547, March 2000 [4 ]; Giuseppe Bianchi and Ilenia Tinnirello, "Kalman filter estimation of the 5 number of competing terminals in an IEEE 802.11 network," Proc. IEEE Conf. Comput. Commun. (INFOCOM 2003), vol.22, no.1, pp. 844-852, March 2003 [5]), and from the probability of a bit error in the data packet determined by the signal-to-noise ratio (SNR) in the signal transmitting stations at the receiving station (Daji Qiao and Sunghyun Choi, "Goodput enhancement of IEEE 802.11 a Wireless LAN via link adaptation," Proc. IEEE Int. Conf. Comm. (ICC 2001), vol. 7, pp. 1995-2000, June 2001 [6]; Daji Qiao, Sunghyun Choi, and Kang G. Shin, "Goodput analysis and link adaptation for IEEE 802.11 a Wireless LANs," IEEE Trans. Mobile Comput., Vol. 1, no.4, pp. 278-292, Oct-Dec. 2002 [7]; Javier del Prado Pavon and Sunghyun Choi, "Link adaptation strategy for IEEE 802.11 WLAN via received signal strength measurement," Proc. IEEE Int. Conf. Commun. (ICC 2003), no.1, pp. 1108-1113, May 2003 [8]).

The probability of successful reception of a data packet determines the throughput of the IEEE 802.11b system. Another factor determining throughput is the overhead associated with the transmission of a data packet.

Overhead costs include:

- All time intervals in which the transmission medium is not occupied:

- The basic interval between packets

- Competitive access interval (number of free slots between two consecutive transfers in the system)

- Short packet spacing

- All service messages:

- Transfer Request

- Permission to transfer

- The confirmation

- All service information:

- MAC header

- Check sum

- Preamble

- The title of the physical layer.

Moreover, the larger the fragment size, the less the influence of overhead costs, but also the greater the likelihood of an error in the data packet.

To maximize throughput in the IEEE 802.11b system, each station can adaptively select the fragment size, transmission rate, and transmission mechanism before transmitting each data block.

In A.Kamerman and L. Monteban's publication, "WaveLAN-II: a high-performance wireless LAN for the unlicensed band," Bell Labs Technical J., pp. 118-133, summer 1997 [9] and described in [7] The next way to transfer data in an IEEE 802.11b system.

When transmitting a data block, a fragment size equal to the size of the data block is used.

When transmitting the first data block, any transmission rate is used.

The data block is transmitted.

If the data block is received correctly, then the next data block is transmitted.

If the data block is received incorrectly, then transmit it again.

If two consecutive attempts to transmit a data block were unsuccessful, then the next more noise-resistant transmission rate is chosen as the next transmission rate.

If ten consecutive transmission attempts were successful, then the next less interfering transmission rate is selected as the next transmission rate.

The obvious advantage of this method of data transfer in the IEEE 802.11b system is the simplicity of its implementation.

The disadvantage of this transmission method is that the system throughput achieved when using it is significantly lower than the maximum achievable, as shown in [7]. The closest in technical essence to the solution of the claimed method is the solution described in [6] and [7].

According to the description of the prototype, the method of transmitting data in a wireless LAN according to the IEEE 802.11b standard, including at least one transmitting station and one receiving station, is as follows:

- form at the transmitting station a database of the dependence of network bandwidth on the signal-to-noise ratio, transmission speed and fragment size of the data block,

- before transmitting the data block, evaluate at the transmitting station the current value of the signal-to-noise ratio in the signal of the transmitting station,

- for the resulting estimate of the signal-to-noise ratio, such a value of the fragment size and transmission rate is selected that corresponds to the maximum value of the network bandwidth in the database,

- to transfer all fragments of the data block, use the selected fragment size,

- when transmitting fragments of a data block, the selected transmission rate is used until a new estimate of the signal-to-noise ratio is obtained in the signal of the transmitting station, after which a new transmission rate is selected, which is used when transmitting fragments of the data block.

Moreover, after receiving a new estimate of the signal-to-noise ratio in the signal of the transmitting station, a new transmission rate is selected that corresponds to the maximum value of the network bandwidth in the database for the selected fragment size.

The known method has the following significant disadvantages.

The prototype method does not take into account the current network load (the number of active stations). At the same time, the network bandwidth and, accordingly, the optimal values of the fragment size and transmission speed significantly depend on the current network load. Since the prototype method does not take this effect into account, it loses significantly to the claimed method in terms of network bandwidth.

Also, the prototype method does not provide an adaptive choice of data transfer mode. However, with an increase in network load, the likelihood of a station collision increases. Under these conditions, the data transfer mechanism with a preliminary transfer request significantly exceeds the main data transfer mechanism in terms of network bandwidth. Since the prototype method does not take this effect into account, it loses significantly to the claimed method in terms of network bandwidth.

The problem to which the claimed method is directed is to increase the throughput of a wireless local area network according to the IEEE 802.11b standard.

The problem is solved by the claimed method of data transmission in a wireless local area network according to the IEEE 802.11b standard, which includes at least one transmitting station and one receiving station, which consists in the following:

At the transmitting station, the average number of free slots between two consecutive transmissions in the network is periodically evaluated.

The number of active stations in the network is estimated using an estimate of the average number of free slots between two consecutive transmissions in the network.

Using an estimate of the number of active stations in the network, the probability of a station collision and the average number of stations in a collision are estimated.

Transmit from the transmitting station to the receiving station L data blocks, where L is greater than or equal to 1, using the main data transmission mechanism, the most noise-resistant transmission rate and such a fragment size that is the same for all L data blocks so that one data block contains 2 or more fragments, and the first two fragments of each data block were the same size.

Confirmations are received at the transmitting station for those fragments of L data blocks that were received without error at the receiving station.

At the transmitting station, the signal-to-noise ratio in the signal of the receiving station is estimated from the received acknowledgments.

Estimated at the transmitting station, the signal-to-noise ratio in the signal of the transmitting station, using information about the number of confirmations received after the transmission of L data blocks.

Before transmitting the data block, the optimal fragment size, the optimal transmission speed and the corresponding network bandwidth value for the main data transmission mechanism are determined using the obtained signal-to-noise ratio estimate and the probability of station collision probability and the average number of stations in the collision.

The optimal fragment size, the optimal transmission rate, and the corresponding network bandwidth value for the data transmission mechanism with a preliminary transmission request are determined using the obtained signal-to-noise ratio estimate and the probability of station collision probability and the average number of stations in the collision.

Choose the main data transmission mechanism with the optimal fragment size and the optimal transmission rate for the data block to be transmitted if the network bandwidth value for the main data transmission mechanism is greater than the network bandwidth value for the data transmission mechanism with a preliminary transfer request;

A data transmission mechanism with a preliminary transfer request with the corresponding optimal fragment size and optimal transmission speed is selected for transmission of the data block if the network bandwidth value for the data transfer mechanism with the preliminary transfer request is greater than the network bandwidth value for the main data transmission mechanism.

To transfer all fragments of the data block, the selected data transmission mechanism and the corresponding optimal fragment size are used.

When transmitting fragments of a data block, the selected optimal transmission rate is used until a new estimate of the average number of free slots between two consecutive transmissions in the network or a new estimate of the signal-to-noise ratio in the signal of the transmitting station is obtained, after which a new optimal transmission rate is selected, which is used when transmitting fragments of the block data.

Periodically, the transmitting station is updated with an estimate of the signal-to-noise ratio in the signal of the transmitting station using information on the number of confirmations received after the transmission of M data blocks transmitted using the same data transmission mechanism, the same transmission rate, and the same fragment size.

Moreover, to obtain an estimate of the average number of free slots between two consecutive transmissions in the network at the transmitting station, carry out K, where K is greater than or equal to 1, consecutive measurements of the number of free slots between two consecutive transmissions in the network, average K consecutive measurements of the number of free slots between two sequential transfers in the network, getting the first estimate of the average number of free slots between two consecutive transfers in the network, each subsequent estimate with ednego number of available slots between two successive transmissions in the network are obtained by averaging with each new measurement of the (K-1) previous measurements.

, где s - оценка среднего количества свободных слотов между двумя последовательными передачами в сети, с₁=const - постоянная величина, равная 1.55, с₂=const - постоянная величина, равная 0.9, и c₃=const - постоянная величина, равная 6.949.If the number of stations N ₀ registered in the network is known at the transmitting station, then the number of active stations in the network N is estimated by the formula

, where s is the estimate of the average number of free slots between two consecutive transfers in the network, with ₁ = const is a constant value equal to 1.55, with ₂ = const is a constant value equal to 0.9, and c ₃ = const is a constant value equal to 6.949.

, где s - оценка среднего количества свободных слотов между двумя последовательными передачами в сети, с₁=const - постоянная величина, равная 1.55, с₂=const - постоянная величина, равная 0.9, и c₃=const - постоянная величина, равная 6.949.If the number of stations registered in the network is not known at the transmitting station, then the number of active stations in the network N is estimated by the formula

, where s is the estimate of the average number of free slots between two consecutive transfers in the network, with ₁ = const is a constant value equal to 1.55, with ₂ = const is a constant value equal to 0.9, and c ₃ = const is a constant value equal to 6.949.

где N - оценка количества активных станций в сети, с₄=const - постоянная величина, равная 0.114, и с₅=const - постоянная величина, равная 1.11.The probability of collision of station P is estimated by the formula

where N is an estimate of the number of active stations in the network, with ₄ = const is a constant value equal to 0.114, and with ₅ = const is a constant value equal to 1.11.

где N - оценка количества активных станций в сети, c₆=const - постоянная величина, равная 0.0263, и с₇=const - постоянная величина, равная 1.744.The average number of stations in collision J is estimated by the formula

where N is an estimate of the number of active stations in the network, c ₆ = const is a constant value equal to 0.0263, and with ₇ = const is a constant value equal to 1.744.

To obtain an estimate of the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, count the number L _{ACK, 2} acknowledgments of the second fragments transmitted after receiving the first fragments without error, while transmitting L data blocks, evaluate the signal-to-noise ratio in the signal of the transmitting station z, using the second fragments of L transmitted data blocks, according to the formula

, β₁=const=11 и γ₁=const=ln(10)/10,Where

, β ₁ = const = 11 and γ ₁ = const = ln (10) / 10,

z ₀ - assessment of the signal-to-noise ratio in the signal of the receiving station,

x - fragment size, x _ACK - confirmation size.

To obtain an estimate of the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, count the number L _{ACK, 1} confirmations of the reception of the first fragments when transmitting L data blocks, estimate the signal-to-noise ratio in the signal of the transmitting station z using the first fragments L of the transmitted data blocks, the formula

β₁=const=11 и γ₁=const=ln(10)/10,Where

β ₁ = const = 11 and γ ₁ = const = ln (10) / 10,

z ₀ - assessment of the signal-to-noise ratio in the signal of the receiving station,

P is the estimate of the probability of collision of the station, x is the fragment size,

x _ACK - confirmation size.

To obtain an estimate of the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, evaluate the signal-to-noise ratio in the signal of the transmitting station z using the first fragments L of transmitted data blocks, estimate the signal-to-noise ratio in the signal of the transmitting station z using the second fragments L of transmitted blocks data, average the signal-to-noise ratio estimates obtained using the first and second fragments L of the transmitted data blocks.

For the main data transmission mechanism, the optimal fragment size and the optimal transmission speed are understood to mean such a combination of values of the fragment size and transmission speed that maximizes network throughput when using the main data transmission mechanism.

For a data transfer mechanism with a preliminary transfer request, the optimal fragment size and the optimal transmission rate are understood to mean such a combination of fragment size and transmission rate that maximizes network throughput when using a data transfer mechanism with a preliminary transfer request.

по формуле

где b_V=τ_V/t_V, τ_V=c₈·s+c₉+c₁₀·t_V, c₈=const - постоянная величина, равная 20, c₉=const - постоянная величина, равная 444, и с₁₀=const - постоянная величина, равная 336, s - оценка среднего количества свободных слотов между двумя последовательными передачами в сети, t_V=1/V, α_z,V=0.5·exp(-β_V·exp(γ_V·z)), константы β_V и γ_V разные для разных значений скорости передачи V, для скорости передачи V=1 Мб/с β₁=const=11 и γ₁=const=ln(10)/10, для скорости передачи V=2 Мб/с β₂=const=4.44 и γ₂=const=0.195, для скорости передачи V=5.5 Мб/с B_5.5=const=3.13 и γ_5.5=const=0.212, для скорости передачи V=11 Мб/с β₁₁=const=1.29 и γ₁₁=const=0.231, z - оценка отношения сигнал-шум в сигнале передающей станции; определения для каждой из четырех скоростей передачи V величины

по формулеFor the main data transmission mechanism, the optimal fragment size, the optimal transmission rate and the corresponding network throughput value are determined by determining for each of the four transmission speeds V values

according to the formula

where b _V = τ _V / t _V , τ _V = c ₈ · s + c ₉ + c ₁₀ · t _V , c ₈ = const is a constant value equal to 20, c ₉ = const is a constant value equal to 444, and with ₁₀ = const is a constant value equal to 336, s is an estimate of the average number of free slots between two consecutive transfers in the network, t _V = 1 / V, α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transfer rate V, for the transfer rate V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer rate V = 5.5 Mb / s B _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transfer speed V = 11 Mb / with β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, z - estimation of the signal-to-noise ratio in the signal of the transmitting station; determining for each of the four transmission rates V values

according to the formula

where x _max is the size of the data block,

round {} - operation of rounding to the nearest integer,

по формуле

где

P - оценка вероятности коллизии станции, J - оценка среднего количества станций в коллизии; определения оптимальной скорости передачи V^(Basic-opt) по формуле

определения оптимального размера фрагмента

равным размеру фрагмента

при V=V^(Basic-opt); определения значения пропускной способности сети W^(Basic-opt), соответствующего оптимальному размеру фрагмента

и оптимальной скорости передачи V^(Basic-opt), равным значению пропускной способности сети

при

и V=V^(Basic-opt).ceil {} - operation of rounding up; determining for each of the four transmission speeds V network throughput values

according to the formula

Where

P is the estimate of the probability of a collision of a station, J is an estimate of the average number of stations in a collision; determining the optimal transmission speed V ^(Basic-opt) by the formula

determining the optimal fragment size

equal to fragment size

at V = V ^(Basic-opt) ; determining the value of network bandwidth W ^(Basic-opt) corresponding to the optimal fragment size

and optimal transmission speed V ^(Basic-opt) equal to the value of network bandwidth

at

and ^{V = V (Basic-opt)} .

по формулеFor a data transmission mechanism with a preliminary transfer request, the optimal fragment size, the optimal transmission rate and the corresponding network throughput value are determined by determining for each of the four transmission speeds V values

according to the formula

c₁₁=const - постоянная величина, равная 20, с₁₂=const - постоянная величина, равная 444, с₁₃=const - постоянная величина, равная 272, с₁₂=const - постоянная величина, равная 404, и с₁₅=const -постоянная величина, равная 336, s - оценка среднего количества свободных слотов между двумя последовательными передачами в сети, t_V=1/V, α_z,V=0.5·ехр(-β_V·ехр(γ_V·z)), константы β_V и γ_V разные для разных значений скорости передачи V, для скорости передачи V=1 Мб/с β₁=const=11 и γ₁=const=ln(10)/10, для скорости передачи V=2 Мб/с β₂=const=4.44 и γ₂=const=0,195, для скорости передачи V=5.5 Мб/с β_5.5=const=3.13 и γ_5.5 = const=0.212, для скорости передачи V=11 Мб/с β₁₁=const=1.29 и γ₁₁=const=0.231, z - оценка отношения сигнал-шум в сигнале передающей станции, Р - оценка вероятности коллизии станции, J - оценка среднего количества станций в коллизии; определения для каждой из четырех скоростей передачи V величины

по формулеWhere

c ₁₁ = const is a constant value equal to 20, with ₁₂ = const is a constant value equal to 444, with ₁₃ = const is a constant value equal to 272, with ₁₂ = const is a constant value equal to 404, and with ₁₅ = const - a constant value equal to 336, s is an estimate of the average number of free slots between two consecutive transfers in the network, t _V = 1 / V, α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), constants β _V and γ _{V are} different for different values of the transfer rate V, for the transfer rate V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer speed V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0,195, for the transmission rate V = 5.5 Mb / s _5.5 β = const = 3.13 and _5.5 γ = const = 0,212, A transmission rate V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, z - estimate signal to noise ratio in the signal transmitting station, P - probability estimate station collision, J - estimate of the average number of stations in the collision ; determining for each of the four transmission rates V values

according to the formula

where x _max is the size of the data block,

по формулеround {} - operation of rounding to the nearest integer, ceil {} - operation of rounding up; determining for each of the four transmission speeds V network throughput values

according to the formula

определения оптимальной скорости передачи V^{(RTS-CTS-opt)} по формуле

определения оптимального размера фрагмента

равным размеру фрагмента

при V=V^{(RTS-CTS-opt)}; определения значения пропускной способности сети W^{(RTS-CTS-opt)}, соответствующего оптимальному размеру фрагмента

и оптимальной скорости передачи V^{(RTS-CTS-opt)}, равным значению пропускной способности сети

при

и V=V^{(RTS-CTS-opt)}.Where

determining an optimum transmission rate V ^{(RTS-CTS-opt)} by the formula

determining the optimal fragment size

equal to fragment size

at V = V ^{(RTS-CTS-opt)} ; determine the value of network bandwidth W ^{(RTS-CTS-opt)} corresponding to the optimal fragment size

and optimal transmission speed V ^{(RTS-CTS-opt)} equal to the value of network bandwidth

at

and V = V ^{(RTS-CTS-opt)} .

где

размер фрагмента x равен полученному ранее оптимальному размеру фрагмента для основного механизма передачи данных

t_V=1/V, α_z,V=0.5·exp(-β_V·ехр(γ_V·z)), константы β_V и γ_V разные для разных значений скорости передачи V, для скорости передачи V=1 Мб/с β₁=const=11 и γ₁=const=ln(l0)/10, для скорости передачи V=2 Мб/с β₂=const=4.44 и γ₂=const=0.195, для скорости передачи V=5.5 Мб/с β_5.5=const=3.13 и γ_5.5=const=0.212, для скорости передачи V=11 Мб/с β₁₁=const=1.29 и γ₁₁=const=0.231, τ_V=c₈·s+c₉+c₁₀·t_V, c₈=const - постоянная величина, равная 20, с₉=const - постоянная величина, равная 444, и с₁₀=const - постоянная величина, равная 336, s - последняя оценка среднего количества свободных слотов между двумя последовательными передачами в сети, z - последняя оценка отношения сигнал-шум, Р - последняя оценка вероятности коллизии станции, J - последняя оценка среднего количества станций в коллизии.The new optimal transmission rate for the main data transfer mechanism is determined by the formula

Where

fragment size x is equal to the previously obtained optimal fragment size for the main data transfer mechanism

t _V = 1 / V, α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transmission speed V, for the transmission speed V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (l0) / 10, for the transmission speed V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transmission speed V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transmission speed V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, τ _V = c ₈ · s + c ₉ + c ₁₀ · t _V , c ₈ = const is a constant value equal to 20, with ₉ = const is a constant value equal to 444, and with ₁₀ = const is a constant value equal to 336, s is the last estimate of the average number of free slots between two consecutive transmissions in the network, z - the last estimate of the signal-to-noise ratio, P is the last estimate of the probability of collision of a station, J is the last estimate of the average number of stations in a collision.

The new optimal transmission rate for the data transfer mechanism with a preliminary transfer request is determined by the formula

Where

t_V=1/V, α_z,V=0.5·exp(-β_V·exp(γ_V·z)), константы β_V и γ_V разные для разных значений скорости передачи V, для скорости передачи V=1 Мб/с β₁=const=11 и γ₁=const=ln(10)/10, для скорости передачи V=2 Мб/с β₂=const=4.44 и γ₂=const=0.195, для скорости передачи V=5.5 Мб/с β_5.5=const=3.13 и γ_5.5=const=0.212, для скорости передачи V=11 Мб/с β₁₁=const=1.29 и γ₁₁=const=0.231,

c₁₁=const - постоянная величина, равная 20, с₁₂=const - постоянная величина, равная 444, с₁₃=const - постоянная величина, равная 272, с₁₄=const - постоянная величина, равная 404, и с₁₅=const - постоянная величина, равная 336, s - последняя оценка среднего количества свободных слотов между двумя последовательными передачами в сети, z - последняя оценка отношения сигнал-шум, Р - последняя оценка вероятности коллизии станции, J - последняя оценка среднего количества станций в коллизии.fragment size x is equal to the previously obtained optimal fragment size for the data transfer mechanism with a preliminary transfer request

t _V = 1 / V, α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transmission speed V, for the transmission speed V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer speed V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transmission speed V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231,

c ₁₁ = const is a constant value equal to 20, with ₁₂ = const is a constant value equal to 444, with ₁₃ = const is a constant value equal to 272, with ₁₄ = const is a constant value equal to 404, and with ₁₅ = const - a constant value equal to 336, s is the last estimate of the average number of free slots between two sequential transmissions in the network, z is the last estimate of the signal-to-noise ratio, P is the last estimate of the probability of collision of a station, J is the last estimate of the average number of stations in a collision.

, оценивают отношение сигнал-шум в сигнале передающей станции z, используя вторые фрагменты М переданных блоков данных по формулеTo clarify the estimates of the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, consider the number of M ACKs _{, 2} confirmations of receipt of the second fragments transmitted after the first fragments were received without error when transmitting M data blocks, if each of the M data blocks contains more than one fragment, transmitted using the same data transmission mechanism, the same transmission speed V ^(opt) and the same fragment size

, estimate the signal-to-noise ratio in the signal of the transmitting station z, using the second fragments M of the transmitted data blocks according to the formula

- размер фрагмента, x_ACK - размер подтверждения.where α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transfer rate V, for the transfer rate V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer speed V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transmission rate V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, V = V ^(opt) , z ₀ is the estimate of the signal-to-noise ratio in receiving station signal

- fragment size, x _ACK - confirmation size.

To clarify at the transmitting station the estimates of the signal-to-noise ratio in the signal of the transmitting station, consider the number of M ACKs _{, 1} confirmations of the first fragments when transmitting M data blocks transmitted using the same data transmission mechanism, the same transmission rate and one and of the same fragment size, the signal-to-noise ratio in the signal of the transmitting station z is estimated using the first fragments M of the transmitted data blocks, according to the formula

where α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transfer rate V, for the transfer rate V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer speed V = 5.5 Mb / s V _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transmission speed V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, V = V ^(opt) , z ₀ is the signal-to-signal ratio estimate noise in the signal of the receiving station, P - estimate of the probability of collision of the station, x - fragment size, x _ACK confirmation size.

To clarify the estimate of the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, an updated estimate of the signal-to-noise ratio in the signal of the transmitting station z is obtained using the first fragments M of the transmitted data blocks; an updated estimate of the signal-to-noise ratio in the signal of the transmitting station z is obtained using the second the fragments M of the transmitted data blocks average the updated estimates of the signal-to-noise ratio obtained using the first and second fragments M of the transmitted data blocks.

To further refine the estimates of the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, an updated estimate of the signal-to-noise ratio in the signal of the transmitting station is averaged with one or more previous estimates of the signal-to-noise ratio in the signal of the transmitting station.

The invention of the proposed method is as follows.

At the transmitting station, the average number of free slots between two consecutive transmissions in the network is periodically evaluated.

The number of active stations in the network is estimated using an estimate of the average number of free slots between two consecutive transmissions in the network.

Using an estimate of the number of active stations in the network, the probability of a station collision and the average number of stations in a collision are estimated.

This sequence of actions in the prototype method is missing. At the same time, it is necessary to obtain the characteristics of the current wireless LAN load according to the IEEE 802.11b standard, which will then be used to select the data transfer mode, fragment size, and transmission rate that maximize network throughput taking into account the signal-to-noise ratio in the signal transmitting stations and taking into account the current network load.

Transmit from the transmitting station to the receiving station L data blocks, where L is greater than or equal to one, using the basic data transmission mechanism, the most noise-resistant transmission rate and such a fragment size that is the same for all L data blocks so that one data block contains two or more fragments, and the first two fragments of each data block were the same size.

Confirmations are received at the transmitting station for those fragments of L data blocks that were received without error at the receiving station.

At the transmitting station, the signal-to-noise ratio in the signal of the receiving station is estimated from the received acknowledgments.

Estimated at the transmitting station, the signal-to-noise ratio in the signal of the transmitting station, using information about the number of confirmations received after the transmission of L data blocks.

This sequence of actions in the prototype method is missing. Instead, in the prototype method, the signal-to-noise ratio in the signal of the transmitting station is estimated by the signal-to-noise ratio in the signal of the receiving station. Such an approach is permissible only when the transmitting and receiving stations transmit with the same power.

The claimed method does not make the assumption that the transmitting and receiving stations transmit with the same power. Instead, in the inventive method, the signal-to-noise ratio in the signal of the transmitting station at the transmitting station is estimated using information about the number of confirmations received after the transmission of L data blocks, i.e. using the probability estimate of the correct reception obtained by the transmission of L data blocks.

Before transmitting the data block, the optimal fragment size, the optimal transmission speed and the corresponding network throughput value for the main data transmission mechanism are determined using the obtained estimate of the signal-to-noise ratio in the signal of the transmitting station and the probability of the collision of the station and the average number of stations in the collision.

The optimal fragment size, the optimal transmission rate, and the corresponding network bandwidth value for the data transmission mechanism with a preliminary transmission request are determined using the obtained signal-to-noise ratio estimate and the probability of station collision probability and the average number of stations in the collision.

The main data transmission mechanism with the corresponding optimal fragment size and optimal transmission speed is selected for transmission of the data block if the network bandwidth value for the main data transmission mechanism is greater than the network bandwidth value for the data transmission mechanism with a preliminary transfer request.

A data transmission mechanism with a preliminary transfer request with the corresponding optimal fragment size and optimal transmission speed is selected for transmission of the data block if the network bandwidth value for the data transfer mechanism with the preliminary transfer request is greater than the network bandwidth value for the main data transmission mechanism.

This sequence of actions in the prototype method is missing. Instead, in the prototype method, the fragment size and transmission rate are selected that maximize the network bandwidth obtained taking into account only the signal-to-noise ratio in the signal of the transmitting station. Since the current network load has a significant effect on network bandwidth, the values obtained in the prototype method for the fragment size and transmission speed do not maximize the real network bandwidth.

In the inventive method, a combination of the optimal fragment size and the optimal transmission speed, as well as the corresponding value of the network bandwidth, is selected separately for the main data transfer mechanism and for the data transfer mechanism with a preliminary transfer request. Then, additionally choose a data transfer mechanism corresponding to the maximum network bandwidth, as well as the corresponding values of the optimal fragment size and optimal transmission speed.

To transfer all fragments of the data block, the selected data transmission mechanism and the corresponding optimal fragment size are used.

In the prototype method, the selected fragment size is also used to transfer all fragments of the data block, since this is a requirement of the IEEE 802.11b standard. However, the difference between this operation of the proposed method and the prototype method is that it additionally uses the selected data transfer mechanism to transfer all fragments of the data block.

When transmitting fragments of a data block, the selected optimal transmission rate is used until a new estimate of the average number of free slots between two consecutive transmissions in the network or a new estimate of the signal-to-noise ratio in the signal of the transmitting station is obtained, after which a new optimal transmission rate is selected, which is used when transmitting fragments of the block data.

The difference between this operation of the proposed method from the prototype method is as follows. The prototype method does not take into account the current network load. Therefore, it provides for the selection of a new transmission rate only upon receipt of a new estimate of the signal-to-noise ratio in the signal of the transmitting station. The inventive method additionally provides for the selection of a new optimal transmission speed upon receipt of a new estimate of the average number of free slots between two consecutive transmissions in the network (this characteristic determines the current network load).

Also, when choosing a new transmission speed, the prototype method takes into account only the signal-to-noise ratio in the signal of the transmitting station. The inventive method when choosing a new transmission speed additionally takes into account the current network load.

Periodically, the transmitting station is updated with an estimate of the signal-to-noise ratio in the signal of the transmitting station using information on the number of confirmations received after the transmission of M data blocks transmitted using the same data transmission mechanism, the same transmission rate, and the same fragment size.

This operation is absent in the prototype method. At the same time, it is necessary, since the signal-to-noise ratio in the signal of the transmitting station can change in time and its estimate must be clarified.

Thus, the claimed sequence of features of a method for transmitting data in a wireless local area network according to the IEEE 802.11b standard, in contrast to the known technical solutions, allows to obtain a new technical effect, namely, to maximize the throughput of the wireless local area network according to the IEEE 802.11b standard.

The description of the invention is illustrated by examples and drawings.

Figure 1 illustrates a data packet.

Figure 2 shows an example of a data packet transmission.

Figure 3 illustrates the basic data transmission mechanism.

4 illustrates a data transmission mechanism with a preliminary transfer request.

Figure 5 shows the structural diagram of a device that implements the inventive method.

Consider the operation of the proposed method for transmitting data in a wireless local area network according to the IEEE 802.11b standard.

Consider some of the main features of the standard that are necessary for a better understanding of the claimed invention.

The physical layer of the IEEE 802.11b standard provides four transmission speeds: 1, 2, 5.5 and 11 Mb / s. The noise immunity characteristics of the physical layer of the IEEE 802.11b standard are completely determined by the dependences of the probability of bit error on the signal-to-noise ratio (SNR).

The data blocks arriving at the MAC level (MAC - medium access control) are divided into one or more fragments before transmission. A fragment of a data block cannot be more than 18432 bits. To transmit each fragment of the data block, a separate data packet is formed. The data packet (FIG. 1) consists of a MAC header, a fragment of a data block and a checksum and is transmitted at one of four transmission rates. Before each data packet at a transmission rate of 1 Mbit / s, a preamble and a physical layer header are transmitted, with a total duration of 192 μs.

The work of wireless local area networks according to the IEEE 802.11b standard is based on competitive access to the transmission medium. A station that has a data block for transmission must determine the current state of the transmission medium. If the station detects that the transmission medium is free for a time interval equal to the base interval between packets, then it starts transmitting data. If the station detects that the transmission medium is busy, then it must delay transmission until the transmission medium is found to be free for a time interval equal to the basic interval between packets. Thus, the station avoids collision when the transmission medium is busy.

The transmission of the data packet begins with the interval of competitive access (figure 2). The start of the concurrent access interval is the same for all stations having a data block for transmission. Each of them randomly selects the duration of their competitive access interval as a value of a random variable uniformly distributed within specified limits. Access to the transmission medium is obtained by the station that has chosen the interval of the shortest duration. She begins the transmission of her data packets, having previously waited for her interval of competitive access.

In the IEEE 802.11b standard, concurrent access interval is measured in slots. We will call the interval of the smallest duration (figure 2) the number of free slots between two consecutive transfers in the system.

If the interval of the shortest duration coincided with two or more stations, then they begin to transmit their data packets simultaneously. In this case, a collision occurs (overlapping their data packets in time). In a collision, most likely none of the data packets will be accepted.

For the transmission of any data packet, the IEEE 802.11b standard provides two mechanisms (options) for data transfer: the main data transfer mechanism and the data transfer mechanism with a preliminary transfer request.

When using the main data transfer mechanism, the following data transfer sequence is used (FIG. 3). A station that has won competitive access starts transmitting a data packet immediately after the end of its competitive access interval. If the data packet is successfully received at the receiving station, the receiving station transmits an acknowledgment at a time interval equal to the short interval between packets. In case of successful reception of acknowledgment at the transmitting station, the data packet was received successfully.

When using the data transfer mechanism with a preliminary transfer request, the following data transfer sequence is used (Fig. 4). A station that has won competitive access starts transmitting a transfer request at the end of its competitive access interval. If the transmission request is successfully received, the receiving station transmits the transmission permission at a time interval equal to the short interval between packets. In case of successful reception of a transmission permit, the transmitting station transmits a data packet at a time interval equal to the short interval between packets. If the data packet is successfully received at the receiving station, the receiving station transmits an acknowledgment at a time interval equal to the short interval between packets. In case of successful reception of acknowledgment at the transmitting station, the data packet was received successfully.

The probability of successful reception of a data packet depends on the probability of collision in the system, determined by the current number of active stations in the system (see [3], [4] and [5]), and on the probability of a bit error in the data packet, determined by the signal-to-noise ratio ( SNR) in the signal of the transmitting station at the receiving station (see [6], [7] and [8]).

The probability of successful reception of a data packet determines the throughput of the IEEE 802.11b system. Another factor determining throughput is the overhead associated with the transmission of a data packet.

Overhead costs include:

- All time intervals in which the transmission medium is not occupied:

- The basic interval between packets

- Competitive access interval (number of free slots between two consecutive transfers in the system)

- Short packet spacing

- All service messages:

- Transfer Request

- Permission to transfer

- The confirmation

- All service information:

- MAC header

- Check sum

- Preamble

- The title of the physical layer.

Moreover, the larger the fragment size, the less the influence of overhead costs, but also the greater the likelihood of an error in the data packet.

To maximize throughput in the IEEE 802.11b system, each station can adaptively select the fragment size, transmission rate, and transmission mechanism before transmitting each data block.

Consider a wireless local area network data transmission according to the IEEE 802.11b standard, which includes at least one transmitting station and one receiving station. In general, there will be more than two stations on the network.

The inventive method is carried out on a device whose structural diagram is made in Fig.5.

The device for transmitting data in a wireless local area network according to the IEEE 802.11b standard (Fig. 5) comprises a receiver 1, a control unit 2, a data unit storage unit 3, a fragmentation unit 4, a fragment storage unit 5 of the data unit and a transmitter 6, while the input of the receiver 1 is the first input of a data transmission device in a wireless local area network according to IEEE 802.11b, the first, second and third outputs of the receiver 1 are connected, respectively, to the first, second and fourth inputs of the control unit 2, the first and third outputs of which are connected, respectively, to the first the second and third inputs of the transmitter 6, the second output of the control unit 2 is connected to the first input of the fragmentation unit 4, the fourth output of the control unit 2 is connected to the second input of the data unit fragment storage unit 5, the input of the data unit storage unit 3 is the second input of the wireless data transmission device LAN according to IEEE 802.11b standard, the first output of the data block storage unit 3 is connected to the third input of the control unit 2, the second output of the data unit storage unit 3 is connected to the second input of the fragmentation unit 4, the output of which connected to the first input of the fragment storage unit 5 of the data block, the output of which is connected to the second input of the transmitter 6, the output of which is the output of the data transmission device in the wireless LAN according to the IEEE 802.11b standard.

The data block storage unit 3 is, for example, a data block queue. The node 5 for storing fragments of a data block is, for example, a queue of fragments of a data block.

Receiver 1, control unit 2, data unit storage unit 3, fragmentation unit 4, data unit fragment storage unit 5 and transmitter 6 can be performed on a digital signal processor (DSP) or on a specialized microcircuit (such an embodiment of the station IEEE 802.11b is now widely marketed).

The inventive method of transmitting data in a wireless LAN according to the IEEE 802.11b standard provides for three parallel processes:

- periodic assessment of the characteristics of the current network load,

- periodically evaluating the signal-to-noise ratio in the signal of the transmitting station,

- transmission of data blocks and fragments of the data block from the transmitting station to the receiving station with a preliminary selection of the data transfer mechanism, fragment size and transmission speed.

The current estimate of the signal-to-noise ratio obtained at the receiving station and the estimates of the characteristics of the current network load received at the transmitting station are used at the transmitting station to select the data transmission mechanism, fragment size and transmission speed.

Consider each of these three processes.

The characteristics of the current network load according to the IEEE 802.11b standard are:

- the average number of free slots between two consecutive transfers in the network,

- the number of active stations in the network,

- probability of a station collision,

- average number of stations in collision.

The periodic process of assessing the characteristics of the current network load is as follows.

The transmitting station estimates the average number of free slots between two consecutive transmissions in the network.

To obtain at the transmitting station estimates of the average number of free slots between two consecutive transmissions in the network, for example, the following sequence of actions is carried out.

In the receiver 1 carry out K, where K is greater than or equal to 1, consecutive measurements of the number of free slots between two consecutive transmissions in the network and transmit them from the second output of the receiver 1 to the second input of the control unit 2. These measurements are made using the IEEE 802.11b standard mechanism for physically monitoring the occupancy of a transmission medium.

In the control unit 2, averaged K consecutive measurements of the number of free slots between two consecutive transfers in the network, obtaining the first estimate of the average number of free slots between two consecutive transfers in the network.

Each subsequent estimate of the average number of free slots between two sequential transmissions in the network is obtained in the control unit 2, averaging each new measurement with (K-1) previous measurements.

In the control unit 2, the number of active stations in the network is estimated using an estimate of the average number of free slots between two consecutive transmissions in the network.

, где s - оценка среднего количества свободных слотов между двумя последовательными передачами в сети, с₁=const - постоянная величина, равная 1.55, c₂=const - постоянная величина, равная 0.9, и c₃=const - постоянная величина, равная 6.949.If the number of stations N ₀ registered in the network is known at the transmitting station, then the number of active stations in the network N is estimated, for example, by the formula

, where s is the estimate of the average number of free slots between two consecutive transfers in the network, with ₁ = const is a constant value equal to 1.55, c ₂ = const is a constant value equal to 0.9, and c ₃ = const is a constant value equal to 6.949.

, где s - оценка среднего количества свободных слотов между двумя последовательными передачами в сети, с₁=const - постоянная величина, равная 1.55, c₂=const - постоянная величина, равная 0.9, и c₃=const - постоянная величина, равная 6.949.If the number of stations registered in the network is not known at the transmitting station, then the number of active stations in the network N is estimated, for example, by the formula

, where s is the estimate of the average number of free slots between two consecutive transfers in the network, with ₁ = const is a constant value equal to 1.55, c ₂ = const is a constant value equal to 0.9, and c ₃ = const is a constant value equal to 6.949.

In control unit 2, the probability of a station collision and the average number of stations in a collision are estimated.

где N - оценка количества активных станций в сети, с₄=const - постоянная величина, равная 0.114, и с₅=const - постоянная величина, равная 1.11.The probability of collision of station P is estimated, for example, by the formula

where N is an estimate of the number of active stations in the network, with ₄ = const is a constant value equal to 0.114, and with ₅ = const is a constant value equal to 1.11.

где N - оценка количества активных станций в сети, с₆=const - постоянная величина, равная 0.0263, и c₇=const - постоянная величина, равная 1.744.The average number of stations in collision J is estimated, for example, by the formula

where N is an estimate of the number of active stations in the network, with ₆ = const is a constant value equal to 0.0263, and c ₇ = const is a constant value equal to 1.744.

The process of estimating the average number of free slots between two consecutive transfers in the network is carried out periodically. As soon as a new estimate of the average number of free slots between two successive transmissions in the network appears, using it, an estimate is made of the number of active stations in the network, and with its use, an estimate is made of the probability of a station collision and an estimate of the average number of stations in a collision.

In this case, when choosing a data transfer mechanism, fragment size and / or transmission rate, current ones are used, i.e. the most recent ones are the estimates of the average number of free slots between two consecutive transmissions in the network, the estimates of the probability of a station collision, and the estimates of the average number of stations in a collision.

The periodic process of evaluating the signal-to-noise ratio in the signal of the transmitting station is as follows.

First, a preliminary estimate of the signal-to-noise ratio in the signal of the transmitting station is carried out, and then this estimate is periodically updated.

Transmit from the transmitting station to the receiving station L data blocks, where L is greater than or equal to one, using the main data transmission mechanism, the most noise-resistant transmission rate and such a fragment size that is the same for all L data blocks so that one data block contains two or more fragments, and the first two fragments of each data block were the same size.

The data blocks are fed to the input of the data block storage unit 3.

The sizes L of the data blocks are transmitted from the first output of the data block storage unit 3 to the third input of the control unit 2.

In control unit 2, a fragment size is selected for L data blocks such that one data block contains two or more fragments, and the first two fragments of each data block have the same size. This can be done, for example, by choosing the fragment size approximately equal to half the size of the data block, which among the L data blocks has a minimum size. The selected fragment size is transmitted from the second output of the control unit to the first input of the fragmentation unit.

Information about the main data transfer mode selected in the control unit 2 for transmitting L data blocks is received from the third output of the control unit 2 to the third input of the transmitter 6.

Information about the most noise-resistant transmission rate (1 Mb / s) selected in the control unit 2 for transmitting L data blocks comes from the first output of the control unit 2 to the first input of the transmitter 6.

From the second output of the data block storage unit 3, the next data block arrives at the second input of the fragmentation unit 4, after which it is excluded from the data block storage unit 3.

In block 4 fragmentation carry out fragmentation of the next block of data using information about the selected size of the fragment. The set of fragments of the data block comes from the output of the fragmentation block 4 to the first input of the node 5 for storing fragments of the data block.

The next fragment of the data block comes from the output of the node 5 for storing fragments of the data block to the second input of the transmitter 6.

In the transmitter 6, a data packet is formed from the incoming fragment of the data block, a preamble and a physical layer header are added to it, and a data packet is transmitted from the output of the transmitter 6 to the receiving station.

If the data packet was received at the receiving station without errors, then an acknowledgment is transmitted from the receiving station to the transmitting station. If the confirmation is received at the transmitting station without errors, then it arrives at the input of the receiver 1, from the third output of which it goes to the fourth input of the control unit 2, from the fourth output of which goes to the second input of the node 5 for storing fragments of the data block. Upon receipt of confirmation for a fragment, this fragment is excluded from the node 5 for storing fragments of the data block.

If the data packet is received at the receiving station with errors or the confirmation is received at the transmitting station with errors, then the fragment is not excluded from the node 5 for storing fragments of the data block and is transmitted again.

In the manner described above, confirmations are received at the transmitting station for all transmissions of all fragments L of data blocks that were received without error at the receiving station.

At the transmitting station in receiver 1, the signal-to-noise ratio in the signal of the receiving station is estimated from the received acknowledgments.

The signal-to-noise ratio in the signal of the receiving station is estimated at the transmitting station by any of the known methods. In this case, the signal-to-noise ratio is used as the ratio of the power of the useful signal chip to the noise power (the IEEE 802.11b standard uses signal transmission technology with spreading the signal spectrum by a pseudo-random sequence, therefore the term "useful signal chip" is generally used in such situations).

Estimates of the signal-to-noise ratio in the signal of the receiving station come from the first output of receiver 1 to the first input of control unit 2. In control unit 2, these estimates can be further averaged.

The signal to noise ratio in the signal of the transmitting station is estimated at the transmitting station in the control unit 2 using information on the number of confirmations received after the transmission of L data blocks.

To obtain an estimate of the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, for example, consider the number of L _{ACKs, 2} acknowledgments of the second fragments transmitted after receiving the first fragments without error, while transmitting L data blocks, evaluate the signal-to-noise ratio in the signal of the transmitting station z, using the second fragments L of the transmitted data blocks, according to the formula

β₁=const=11 и γ₁=const=ln(10)/10,Where

β ₁ = const = 11 and γ ₁ = const = ln (10) / 10,

z ₀ - assessment of the signal-to-noise ratio in the signal of the receiving station,

x is the size of the fragment, x _ACK is the size of the confirmation.

To obtain an estimate of the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, for example, count the number L _{ACK, 1} confirmations of the reception of the first fragments when transmitting L data blocks, estimate the signal-to-noise ratio in the signal of the transmitting station z using the first fragments of L transmitted blocks data according to the formula

β₁=const=11 и γ₁=const=ln(10)/10,Where

β ₁ = const = 11 and γ ₁ = const = ln (10) / 10,

z ₀ - assessment of the signal-to-noise ratio in the signal of the receiving station,

P is the estimate of the probability of collision of the station, x is the fragment size,

x _ACK - confirmation size.

To obtain an estimate of the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, for example, the signal-to-noise ratio in the signal of the transmitting station z is estimated using the first fragments L of transmitted data blocks, the signal-to-noise ratio in the signal of the transmitting station z is estimated using the second fragments L transmitted data blocks, average the signal-to-noise ratio estimates obtained using the first and second fragments of L transmitted data blocks.

The estimate of the signal-to-noise ratio in the signal of the transmitting station is periodically updated at the transmitting station in the control unit 2 using information on the number of confirmations received after the transmission of M data blocks transmitted using the same data transmission mechanism, the same transmission rate and the same fragment size.

That is, after a preliminary assessment of the signal-to-noise ratio in the signal of the transmitting station, this estimate is periodically updated. For this, sequences from M data blocks are used, where M is greater than or equal to one transmitted using the same data transmission mechanism, the same transmission speed and the same fragment size.

At the transmitting station in receiver 1, the signal-to-noise ratio in the signal of the receiving station is estimated from the received acknowledgments to those fragments M of data blocks that were received without errors at the receiving station.

Estimates of the signal-to-noise ratio in the signal of the receiving station come from the first output of receiver 1 to the first input of control unit 2. In control unit 2, these estimates can be further averaged.

, оценивают отношение сигнал-шум в сигнале передающей станции z, используя вторые фрагменты М переданных блоков данных по формулеTo clarify the estimates of the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, for example, consider the number of M ACKs _{, 2} acknowledgments of the second fragments transmitted after the first fragments were received without error when transmitting M data blocks, if each of the M data blocks contains more one fragment transmitted using the same data transmission mechanism, the same transmission rate V ^(opt) and the same fragment size

, estimate the signal-to-noise ratio in the signal of the transmitting station z, using the second fragments M of the transmitted data blocks according to the formula

- размер фрагмента, х_ACK - размер подтверждения.where α = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transmission speed V, for the transmission speed V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer speed V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transmission speed V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, V = V ^(opt) _, z ₀ is the estimate of the signal-to-noise ratio in the signal of the receiving station ,

- fragment size, x _ACK - confirmation size.

To clarify the estimates of the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, for example, consider the number M _{ACK, 1} confirmations of the reception of the first fragments when transmitting M data blocks transmitted using the same data transmission mechanism, the same transmission rate and the same fragment size, the signal-to-noise ratio in the signal of the transmitting station z is estimated using the first fragments M of the transmitted data blocks, according to the formula

where α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transmission speed V, for the transmission speed V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer speed V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transmission rate V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, V = V ^(opt) , z ₀ is the estimate of the signal-to-noise ratio in signal of the receiving station, P - estimate of the probability of collision of the station, x - fragment size, x _ACK - confirmation size.

To refine the estimate of the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, for example, an updated estimate of the signal-to-noise ratio in the signal of the transmitting station z is obtained, using the first fragments M of the transmitted data blocks, an updated estimate of the signal-to-noise ratio in the signal of the transmitting station z is obtained using the second fragments M of the transmitted data blocks, average the refined estimates of the signal-to-noise ratio obtained using the first and second fragments M of the transmitted data blocks.

For further refinement at the transmitting station, estimates of the signal-to-noise ratio in the signal of the transmitting station, for example, average the updated estimate of the signal-to-noise ratio in the signal of the transmitting station with one or more previous estimates of the signal-to-noise ratio in the signal of the transmitting station.

The process of transmitting data blocks from the transmitting station to the receiving station is as follows.

The data blocks are fed to the input of the data block storage unit 3.

Before transmitting the data block, in the control unit 2, the optimal fragment size, the optimal transmission speed and the corresponding network bandwidth value for the main data transmission mechanism are determined using the obtained signal-to-noise ratio estimate and the probability of station collision probability and the average number of stations in collision.

For this, the data block size is transmitted from the first output of the data block storage unit 3 to the third input of the control unit 2.

по формуле

где b_V=τ_V/t_V, τ_V=c₈·s+c₉+c₁₀·t_V, c₈=const - постоянная величина, равная 20, c₉=const - постоянная величина, равная 444, и с₁₀=const - постоянная величина, равная 336, s - оценка среднего количества свободных слотов между двумя последовательными передачами в сети, t_V=1/V, α_z,V=0.5·ехр(-β_V·ехр(γ_V·z)), константы β_V и γ_V разные для разных значений скорости передачи V, для скорости передачи V=1 Мб/с β₁=const=11 и γ₁=const=ln(10)/10, для скорости передачи V=2 Мб/с β₂=const=4.44 и γ₂=const=0.195, для скорости передачи V=5.5 Мб/с β_5.5=const=3.13 и γ_5.5=const=0.212, для скорости передачи V=11 Мб/с B₁₁=const=1.29 и γ₁₁=const=0.231, z - оценка отношения сигнал-шум в сигнале передающей станции; определения для каждой из четырех скоростей передачи V величины

по формулеFor the main data transmission mechanism, the optimal fragment size, the optimal transmission rate and the corresponding network throughput value are determined, for example, by determining for each of the four transmission speeds V the value

according to the formula

where b _V = τ _V / t _V , τ _V = c ₈ · s + c ₉ + c ₁₀ · t _V , c ₈ = const is a constant value equal to 20, c ₉ = const is a constant value equal to 444, and with ₁₀ = const is a constant value equal to 336, s is an estimate of the average number of free slots between two sequential transfers in the network, t _V = 1 / V, α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transfer rate V, for the transfer rate V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer rate V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transfer speed V = 11 Mb / with B ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231 , z is the estimate of the signal-to-noise ratio in the signal of the transmitting station; determining for each of the four transmission rates V values

according to the formula

,where x _max is the size of the data block,

,

round {} - operation of rounding to the nearest integer,

по формуле

где

Р - оценка вероятности коллизии станции, J - оценка среднего количества станций в коллизии; определения оптимальной скорости передачи V^(Basic-opt) по формуле

определения оптимального размера фрагмента

равным размеру фрагмента

при V=V^(Basic-opt); определения значения пропускной способности сети W^(Basic-opt), соответствующего оптимальному размеру фрагмента

и оптимальной скорости передачи V^(Basic-opt), равным значению пропускной способности сети

при

V=V^(Basic-opt).ceil {} - operation of rounding up; determining for each of the four transmission speeds V network throughput values

according to the formula

Where

P - estimate of the probability of a collision of a station, J - estimate of the average number of stations in a collision; determining the optimal transmission speed V ^(Basic-opt) by the formula

determining the optimal fragment size

equal to fragment size

at V = V ^(Basic-opt) ; determining the value of network bandwidth W ^(Basic-opt) corresponding to the optimal fragment size

and optimal transmission speed V ^(Basic-opt) equal to the value of network bandwidth

at

V = V ^(Basic-opt) .

For the main data transmission mechanism, the optimal fragment size and the optimal transmission speed are understood to mean such a combination of values of the fragment size and transmission speed that maximizes network throughput when using the main data transmission mechanism. Selecting a fragment size value separately or a transmission speed value separately cannot maximize network bandwidth when using the basic data transfer mechanism. Only a combination of fragment size and transmission rate values can be selected such that it maximizes network throughput when using the basic data transfer mechanism.

In control unit 2, the optimal fragment size, the optimal transmission rate, and the corresponding network bandwidth value for the data transmission mechanism with a preliminary transmission request are determined using the obtained signal-to-noise ratio estimate and the probability of station collision probability and the average number of stations in collision.

по формулеFor a data transfer mechanism with a preliminary transfer request, the optimal fragment size, the optimal transmission rate and the corresponding network throughput value are determined, for example, by determining, for each of the four transmission speeds, V

according to the formula

Where

c₁₁=const - постоянная величина, равная 20, с₁₂=const - постоянная величина, равная 444, c₁₃=const - постоянная величина, равная 272, с₁₄=const - постоянная величина, равная 404, и с₁₅=const - постоянная величина, равная 336, s - оценка среднего количества свободных слотов между двумя последовательными передачами в сети, t_V=1/V, α_z,V=0.5·exp(-β_V·exp(γ_V·z)), константы β_V и γ_V разные для разных значений скорости передачи V, для скорости передачи V=1 Мб/с β₁=const=11 и γ₁=const=ln(10)/10, для скорости передачи V=2 Мб/с β₂=const=4.44 и γ₂=const=0.195, для скорости передачи V=5.5 Мб/с β_5.5=const=3.13 и γ_5.5=const=0.212, для скорости передачи V=11 Мб/с β₁₁=const=1.29 и γ₁₁=const=0.231, z - оценка отношения сигнал-шум в сигнале передающей станции, Р - оценка вероятности коллизии станции, J - оценка среднего количества станций в коллизии; определения для каждой из четырех скоростей передачи V величины

по формуле

где х_max - размер блока данных,

, round {} - операция округления до ближайшего целого, ceil {} - операция округления вверх; определения для каждой из четырех скоростей передачи V значения пропускной способности сети

по формуле

c ₁₁ = const is a constant value equal to 20, with ₁₂ = const is a constant value equal to 444, c ₁₃ = const is a constant value equal to 272, with ₁₄ = const is a constant value equal to 404, and with ₁₅ = const - a constant value equal to 336, s is an estimate of the average number of free slots between two consecutive transmissions in the network, t _V = 1 / V, α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), constants β _V and γ _{V are} different for different values of the transfer rate V, for the transfer rate V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer speed V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transmission rate V = 5.5 Mb / s _5.5 β = const = 3.13 and _5.5 γ = const = 0,212, for scab transmission V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, z - estimate signal to noise ratio in the signal transmitting station, P - probability estimate station collision, J - estimate of the average number of stations in the collision; determining for each of the four transmission rates V values

according to the formula

where x _max is the size of the data block,

, round {} - the operation of rounding to the nearest integer, ceil {} - the operation of rounding up; determining for each of the four transmission speeds V network throughput values

according to the formula

определения оптимальной скорости передачи V^{(RTS-CTS-opt)} по формуле

определения оптимального размера фрагмента

равным размеру фрагмента

при V=V^{(RTS-CTS-opt)}; определения значения пропускной способности сети W^{(RTS-CTS-opt)}, соответствующего оптимальному размеру фрагмента

и оптимальной скорости передачи V^{(RTS-CTS-opt)}, равным значению пропускной способности сети

при

и V=V^{(RTS-CTS-opt)}.Where

determining an optimum transmission rate V ^{(RTS-CTS-opt)} by the formula

determining the optimal fragment size

equal to fragment size

at V = V ^{(RTS-CTS-opt)} ; determine the value of network bandwidth W ^{(RTS-CTS-opt)} corresponding to the optimal fragment size

and optimal transmission speed V ^{(RTS-CTS-opt)} equal to the value of network bandwidth

at

and V = V ^{(RTS-CTS-opt)} .

For a data transfer mechanism with a preliminary transfer request, the optimal fragment size and the optimal transmission rate are understood to mean such a combination of fragment size and transmission rate that maximizes network throughput when using a data transfer mechanism with a preliminary transfer request. Selecting a fragment size value separately or a transmission speed value separately cannot maximize the network throughput when using a data transfer mechanism with a preliminary transfer request. Only a combination of fragment size and transmission rate values can be selected such that it maximizes network throughput when using a data transfer mechanism with a preliminary transfer request.

In the control unit 2, the main data transmission mechanism is selected for transmission of the data block with the optimal fragment size and optimal transmission speed corresponding to it if the network bandwidth value for the main data transmission mechanism is greater than the network bandwidth value for the data transmission mechanism with a preliminary transmission request.

In the control unit 2, a data transmission mechanism with a preliminary transfer request with the corresponding optimal fragment size and optimal transmission speed is selected for transmission of the data block if the network bandwidth value for the data transmission mechanism with the preliminary transmission request is greater than the network bandwidth value for the main mechanism data transmission.

To transfer all fragments of the data block, the selected data transmission mechanism and the corresponding optimal fragment size are used.

Information about the selected data transfer mechanism is transmitted from the first output of the control unit 2 to the first input of the transmitter 6, and information about the selected optimal fragment size is transmitted from the second output of the control unit 2 to the first input of the fragmentation unit 4.

From the second output of the data block storage unit 3, the next data block arrives at the second input of the fragmentation unit 4, after which it is excluded from the data block storage unit 3.

In block 4 fragmentation carry out fragmentation of the next data block, using information about the selected optimal fragment size.

The set of fragments of the data block comes from the output of the fragmentation block 4 to the first input of the node 5 for storing fragments of the data block.

When transmitting fragments of a data block, the selected optimal transmission rate is used until a new estimate of the average number of free slots between two consecutive transmissions in the network or a new estimate of the signal-to-noise ratio in the signal of the transmitting station is obtained, after which a new optimal transmission rate is selected, which is used when transmitting fragments of the block data.

The next fragment of the data block comes from the output of the node 5 for storing fragments of the data block to the second input of the transmitter 6.

When the first fragment of the data block is transmitted for the first time, the selected optimal transmission rate is used, which comes from the third output of the control unit 2 to the third input of the transmitter 6.

In the transmitter 6, a data packet is formed from the incoming fragment of the data block, a preamble and a physical layer header are added to it, and a data packet is transmitted from the output of the transmitter 6 to the receiving station.

If the data packet was received at the receiving station without errors, then an acknowledgment is transmitted from the receiving station to the transmitting station. If the confirmation is received at the transmitting station without errors, then it arrives at the input of the receiver 1, from the third output of which it goes to the fourth input of the control unit 2, from the fourth output of which goes to the second input of the node 5 for storing fragments of the data block. Upon receipt of confirmation for a fragment, this fragment is excluded from the node 5 for storing fragments of the data block.

If the data packet is received at the receiving station with errors or the confirmation is received at the transmitting station with errors, then the fragment is not excluded from the node 5 for storing fragments of the data block and is transmitted again.

When retransmitting the first fragment of the data block or when transmitting other fragments of the data block, a situation is possible in which, before transmission, a new estimate of the average number of free slots between two successive transmissions in the network or a new estimate of the signal-to-noise ratio in the signal of the transmitting station was obtained. In this situation, in the control unit 2, a new optimal transmission rate is selected, which comes from the third output of the control unit 2 to the third input of the transmitter 6. When retransmitting the first fragment of the data block or when transmitting other fragments of the data block, the new optimal transmission speed is used, the previously selected mechanism data transmission and the previously selected optimal fragment size.

The new optimal transmission rate for the main data transfer mechanism 5 is determined, for example, by the formula

размер фрагмента x равен полученному ранее оптимальному размеру фрагмента для основного механизма передачи данных

t_V=1/V, α_2,v=0.5·exp(-β_V·ехр(γ_V·z)), константы β_V и γ_V разные для разных значений скорости передачи V, для скорости передачи V=1 Мб/с β₁=const=11 и γ₁₁=const=ln(10)/10, для скорости передачи V=2 Мб/с β₂=const=4.44 и γ₂=const=0.195, для скорости передачи V=5.5 Мб/с β_5.5=const=3.13 и γ_5.5=const=0.212, для скорости передачи V=11 Мб/с β₁₁=const=1.29 и γ₁₁=const=0.231, τ_V=c₈·s+c₉+c₁₀·t_V, с₈=const - постоянная величина, равная 20, c₉=const - постоянная величина, равная 444, и c₁₀=const - постоянная величина, равная 336, s - последняя оценка среднего количества свободных слотов между двумя последовательными передачами в сети, z - последняя оценка отношения сигнал-шум, Р - последняя оценка вероятности коллизии станции, J - последняя оценка среднего количества станций в коллизии.Where

fragment size x is equal to the previously obtained optimal fragment size for the main data transfer mechanism

t _V = 1 / V, α _{2, v} = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transmission speed V, for the transmission speed V = 1 Mb / s β ₁ = const = 11 and γ ₁₁ = const = ln (10) / 10, for the transmission speed V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transmission speed V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transmission speed V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, τ _V = c ₈ · s + c ₉ + c ₁₀ · t _V , with ₈ = const - a constant value equal to 20, c ₉ = const - a constant value equal to 444, and c ₁₀ = const - a constant value equal to 336, s - the last estimate of the average number of free slots between two consecutive transmissions in the network, z - the last estimate of the signal-to-noise ratio, P is the last estimate of the probability of collision of a station, J is the last estimate of the average number of stations in a collision.

The new optimal transmission rate for the data transfer mechanism with a preliminary transfer request is determined by the formula

где

размер фрагмента х равен полученному ранее оптимальному размеру фрагмента для механизма передачи данных с предварительным запросом на передачу

t_V=1/V, α=0.5·exp(-β_V·ехр(γ_V·z)), константы β_V и γ_V разные для разных значений скорости передачи V, для скорости передачи V=1 Мб/с β₁=const=11 и γ₁=const=ln(10)/10, для скорости передачи V=2 Мб/с β₂=const=4.44 и γ₂=const=0.195, для скорости передачи V=5.5 Мб/с β_5.5=const=3.13 и γ_5.5=const=0.212, для скорости передачи V=11 Мб/с β₁₁=const=1.29 и γ₁₁=const=0.231,

c₁₁=const - постоянная величина, равная 20, с₁₂=const - постоянная величина, равная 444, с₁₃=const - постоянная величина, равная 272, c₁₄=const - постоянная величина, равная 404, и c₁₅=const - постоянная величина, равная 336, s - последняя оценка среднего количества свободных слотов между двумя последовательными передачами в сети, z - последняя оценка отношения сигнал-шум, Р - последняя оценка вероятности коллизии станции, J - последняя оценка среднего количества станций в коллизии.

Where

fragment size x is equal to the previously obtained optimal fragment size for the data transfer mechanism with a preliminary transfer request

t _V = 1 / V, α = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transfer rate V, for the transfer rate V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer speed V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transfer rate V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231,

c ₁₁ = const is a constant value equal to 20, c ₁₂ = const is a constant value equal to 444, c ₁₃ = const is a constant value equal to 272, c ₁₄ = const is a constant value equal to 404, and c ₁₅ = const - a constant value equal to 336, s is the last estimate of the average number of free slots between two consecutive transmissions in the network, z is the last estimate of the signal-to-noise ratio, P is the last estimate of the probability of collision of a station, J is the last estimate of the average number of stations in a collision.

The inventive method of transmitting data in a wireless local area network according to the IEEE 802.11b standard allows you to maximize the throughput of the wireless local area network according to the IEEE 802.11b standard.

This advantage is achieved due to the fact that before transmitting each data block, such a data transmission mechanism and the corresponding optimal fragment size and optimal transmission speed are selected that maximize network throughput taking into account the signal-to-noise ratio in the signal of the transmitting station and taking into account the current network load .

Claims (19)

1. The method of transmitting data in a wireless LAN according to the IEEE 802.11b standard, including at least one transmitting station and one receiving station, which consists in periodically evaluating at the transmitting station the average number of free slots between two consecutive transmissions in the network, evaluating the number of active stations in the network, using the estimate of the average number of free slots between two consecutive transmissions in the network, using the estimate of the number of active stations in the network, estimate the probability of collision and the stations and the average number of stations in collision, transmit L data blocks from the transmitting station to the receiving station, where L is greater than or equal to one, using the main data transmission mechanism, the most noise-resistant transmission rate and such a fragment size that is the same for all L data blocks so that one data block contained two or more fragments, and the first two fragments of each data block were of the same size, they received confirmation at the transmitting station on those fragments of L data blocks that were received without error at receiving station, evaluate the signal-to-noise ratio in the signal of the receiving station at the transmitting station according to the received acknowledgments, evaluate the signal-to-noise ratio in the signal of the transmitting station at the transmitting station, using information about the number of confirmations received after transmitting L data blocks before transmitting the data block, determine the optimal fragment size, the optimal transmission rate and the corresponding value of network bandwidth for the main data transfer mechanism, using the resulting estimate Signal-to-noise ratio and estimates of the probability of collision of the station and the average number of stations in the collision determine the optimal fragment size, the optimal transmission rate and the corresponding network throughput value for the data transfer mechanism with a preliminary transmission request using the obtained signal-to-noise ratio estimate and estimates the probability of collision of the station and the average number of stations in the collision, choose the main data transmission mechanism with the corresponding optimal size f agent and the optimal transmission speed, if the value of the network bandwidth for the main data transmission mechanism is greater than the network bandwidth value for the data transmission mechanism with a preliminary transfer request, select a data transmission mechanism with a preliminary transfer request with the corresponding optimal fragment size for transmitting the data block and optimal transmission speed if the value of network bandwidth for the data transmission mechanism with a preliminary request for transfers the network bandwidth is greater than the value for the main data transmission mechanism, the selected data transmission mechanism and the corresponding optimal fragment size are used to transfer all fragments of the data block; when transmitting fragments of the data block, the selected optimal transmission speed is used until a new estimate of the number of active stations in the network or new estimates of the signal-to-noise ratio in the signal of the transmitting station, after which a new optimal transmission rate is selected, which is used when transmitting fra cops of the data block, periodically specify at the transmitting station an estimate of the signal-to-noise ratio in the signal of the transmitting station, using information on the number of confirmations received after the transmission of M data blocks transmitted using the same data transmission mechanism, the same transmission rate, and the same fragment size. 2. The method according to claim 1, characterized in that to obtain at the transmitting station an estimate of the average number of free slots between two consecutive transmissions in the network, carry out K, where K is greater than or equal to 1, consecutive measurements of the number of free slots between two consecutive transmissions in the network , averaged To consecutive measurements of the number of free slots between two consecutive transfers in the network, obtaining a first estimate of the average number of free slots between two consecutive transfers in the network, azhduyu subsequent measurement of the average number of free slots between two successive transmissions in the network are obtained by averaging with each new measurement of the (K-1) previous measurements. 3. The method according to claim 1, characterized in that if the number of stations N ₀ registered in the network is known at the transmitting station, then the number of active stations in the network N is estimated by the formula

where s is the estimate of the average number of free slots between two consecutive transfers in the network, c ₁ = const is a constant value equal to 1.55, c ₂ = const is a constant value equal to 0.9, and c ₃ = const is a constant value equal to 6.949. 4. The method according to claim 1, characterized in that if the number of stations registered in the network is not known at the transmitting station, then the number of active stations in the network N is estimated by the formula

where s is the estimate of the average number of free slots between two consecutive transfers in the network, c ₁ = const is a constant value equal to 1.55, c ₂ = const is a constant value equal to 0.9, and c ₃ = const is a constant value equal to 6.949. 5. The method according to claim 1, characterized in that the probability of a collision of the station P is estimated by the formula

where N is an estimate of the number of active stations in the network, c ₄ = const is a constant value equal to 0.114, and c ₅ = const is a constant value equal to 1.11. 6. The method according to claim 1, characterized in that the average number of stations in collision J is estimated by the formula

where N is an estimate of the number of active stations in the network, c ₆ = const is a constant value equal to 0.0263, and c ₇ = const is a constant value equal to 1.744. 7. The method according to claim 1, characterized in that to obtain at the transmitting station an estimate of the signal-to-noise ratio in the signal of the transmitting station, the number L _{ACK, 2} confirmations of the reception of the second fragments transmitted after receiving the first fragments without error when transmitting L data blocks are counted , estimate the signal-to-noise ratio in the signal of the transmitting station z, using the second fragments L of the transmitted data blocks, according to the formula

Where

β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, z ₀ - evaluation of the signal-to-noise ratio in the signal of the receiving station, x - fragment size, X _ACK - confirmation size. 8. The method according to claim 1, characterized in that to obtain at the transmitting station an estimate of the signal-to-noise ratio in the signal of the transmitting station, count the number L _{ACK, 1} confirmations of receipt of the first fragments when transmitting L data blocks, evaluate the signal-to-noise ratio in the transmitting signal station z, using the first fragments of L transmitted data blocks, according to the formula

Where

β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, z ₀ is the estimate of the signal-to-noise ratio in the signal of the receiving station, P is the estimate of the probability of collision of the station, x is the fragment size, x _ACK is the confirmation size. 9. The method according to claim 1, characterized in that to obtain at the transmitting station an estimate of the signal-to-noise ratio in the signal of the transmitting station, the signal-to-noise ratio in the signal of the transmitting station z is estimated, using the first fragments L of the transmitted data blocks, the signal-to-noise ratio is evaluated in the signal of the transmitting station z, using the second fragments L of the transmitted data blocks, average the signal-to-noise ratio estimates obtained using the first and second fragments L of the transmitted data blocks. 10. The method according to claim 1, characterized in that for the main data transmission mechanism, by the optimal fragment size and optimal transmission speed is understood such a combination of values of the fragment size and transmission speed that maximizes network bandwidth when using the main data transmission mechanism. 11. The method according to claim 1, characterized in that for a data transmission mechanism with a preliminary request for transmission, the optimal fragment size and optimal transmission speed are understood to mean such a combination of fragment size and transmission speed that maximizes network bandwidth when using the transmission mechanism data with a preliminary transfer request. 12. The method according to claim 1, characterized in that for the main data transfer mechanism, the optimal fragment size, the optimal transmission rate and the corresponding network throughput value are determined by determining for each of the four transmission speeds V values

according to the formula

where b _V = τ _V / t _V , τ _V = c ₈ · s + c ₉ + c ₁₀ · t _V , c ₈ = const is a constant value equal to 20, c ₉ = const is a constant value equal to 444, and c ₁₀ = const is a constant value equal to 336, s is an estimate of the average number of free slots between two consecutive transfers in the network, t _V = 1 / V, α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transfer rate V, for the transfer rate V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer rate V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transfer speed V = 11 Mb / with β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, z - estimation of the signal-to-noise ratio in the signal of the transmitting station; determining for each of the four transmission rates V values

according to the formula

where x _max is the size of the data block,

round {} - operation of rounding to the nearest integer, ceil {} - operation of rounding up; determining for each of the four transmission speeds V network throughput values

the formula

Where

P - estimate of the probability of a collision of a station, J - estimate of the average number of stations in a collision; determining the optimal transmission speed by the formula

determining the optimal fragment size x ^{~ (Basic-opt)} equal to the fragment size

at V = V ^(Basic-opt); determining the value of network bandwidth W ^(Basic-opt) corresponding to the optimal fragment size

and optimal transmission speed V ^(Basic-opt) equal to the value of network bandwidth

for x = x ^{~ (Basic-opt)} and V = V ^(Basic-opt) . 13. The method according to claim 1, characterized in that for the data transmission mechanism with a preliminary transfer request, the optimal fragment size, the optimal transmission rate and the corresponding network throughput value are determined by determining for each of the four transmission speeds V values

according to the formula

Where

c ₁₁ = const - a constant value equal to 20, c ₁₂ = const - a constant value equal to 444, c ₁₃ = const - a constant value equal to 272, c ₁₄ = const - a constant value equal to 404, and c ₁₅ = const - a constant value equal to 336, s is an estimate of the average number of free slots between two consecutive transmissions in the network, t _V = 1 / V, α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), constants β _V and γ _V are different for different values of the transmission speed V, for the transmission speed V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transmission speed V = 2 Mb / with β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer rate V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for transmission rates V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, z - estimate of the signal-to-noise ratio in the signal of the transmitting station, P - estimate of the probability of collision of the station, J - estimate of the average number of stations in the collision; determining for each of the four transmission rates V values

according to the formula

where x _max - data block size

round {} - operation of rounding to the nearest integer, ceil {} - operation of rounding up; determining for each of the four transmission speeds V network throughput values

according to the formula

Where

determining an optimum transmission rate V ^{(RTS-CTS-opt)} by the formula

determine the optimal size x ^{~ (RTS-CTS-opt)} fragment x equal to the size of the fragment

at V = V ^{(RTS-CTS-opt)} ; determining the value of network bandwidth W ^{(RTS-CTS-opt)} corresponding to the optimal fragment size x ^{~ (RTS-CTS-opt)} and the optimal transmission speed V ^{(RTS-CTS-opt)} equal to the value of network bandwidth

at x = x ^{~ (RTS-CTS-opt)} and V = V ^{(RTS-CTS-opt)} . 14. The method according to claim 1, characterized in that the new optimal transmission speed for the main data transfer mechanism is determined by

Where

fragment size x is equal to the previously obtained optimal fragment size for the main data transfer mechanism

t _V = 1 / V, α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transmission speed V, for the transmission speed V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer speed V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transmission speed V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, τ _V = c ₈ · s + c ₉ + c ₁₀ · t _V , c ₈ = const is a constant value equal to 20, c ₉ = const is a constant value equal to 444, and c ₁₀ = const is a constant value equal to 336, s is the last estimate of the average number of free slots between two consecutive transmissions in the network, z - by Lednov estimate signal-to-noise score P -Update station collision probability, J - The latest estimate of the average number of stations in the collision. 15. The method according to claim 1, characterized in that the new optimal transmission speed for the data transfer mechanism with a preliminary transfer request is determined by the formula

Where

fragment size x is equal to the previously obtained optimal fragment size for the data transfer mechanism with a preliminary transfer request

t _V = 1 / V, α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)) the constants β _V and γ _{V are} different for different values of the transmission speed V, for the transmission speed V = 1 Mb / with β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer speed V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transmission speed V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231,

c ₁₁ = const - a constant value equal to 20, c ₁₂ = const - a constant value equal to 444, c ₁₃ = const - a constant value equal to 272, c ₁₄ = const - a constant value equal to 404, and c ₁₅ = const - a constant value equal to 336, s is the last estimate of the average number of free slots between two sequential transmissions in the network, z is the last estimate of the signal-to-noise ratio, P is the last estimate of the probability of collision of a station, J is the last estimate of the average number of stations in a collision. 16. The method according to claim 1, characterized in that to clarify at the transmitting station the estimates of the signal-to-noise ratio in the signal of the transmitting station, consider the number M _{ACK, 2} confirmations of receipt of the second fragments transmitted after the first fragments were received without error when transmitting M data blocks if each of the M data blocks contains more than one fragment transmitted using the same data transmission mechanism, the same transmission rate V ^(opt) and the same fragment size x ^{~ (opt)} , the signal-to-signal ratio is estimated noise in the transmission signal station z using the second fragments M of transmitted data blocks according to the formula

where α _{z, V} = 0.5 · exp (-β _V · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transmission speed V, for the transmission speed V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer speed V = 5.5 Mb / s β _5.5 = const = 3.13 and γ _5.5 = const = 0.212, for the transfer rate V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, V = V ^{~ (opt)} , z ₀ is the ratio estimate, the signal is noise in the signal of the receiving station, x = x ^{~ (opt)} - fragment size, x _ACK - confirmation size. 17. The method according to claim 1, characterized in that to clarify the transmitting station estimates the signal-to-noise ratio in the signal of the transmitting station, consider the number M _{ACK, 1} confirmations of the first fragments when transmitting M data blocks transmitted using the same mechanism transmitting data of the same transmission rate and the same fragment size, estimate the signal-to-noise ratio in the signal of the transmitting station z, using the first fragments M of the transmitted data blocks, according to the formula

where α _{z, V} = 0.5 · exp (-β · exp (γ _V · z)), the constants β _V and γ _{V are} different for different values of the transmission speed V, for the transmission speed V = 1 Mb / s β ₁ = const = 11 and γ ₁ = const = ln (10) / 10, for the transfer rate V = 2 Mb / s β ₂ = const = 4.44 and γ ₂ = const = 0.195, for the transfer speed V = 5.5 Mb / s V _5.5 = const = 3.13 and γ5.5 = const = 0.212, for the transmission speed V = 11 Mb / s β ₁₁ = const = 1.29 and γ ₁₁ = const = 0.231, V = V ^(opt) , z ₀ is the estimate of the signal-to-noise ratio in the signal of the receiving station, P is the estimate of the probability of collision of the station, x is the fragment size, x _ACK is the acknowledgment size. 18. The method according to claim 1, characterized in that to clarify the estimate of the signal-to-noise ratio in the signal of the transmitting station 5 at the transmitting station, an updated estimate of the signal-to-noise ratio in the signal of the transmitting station z is obtained, using the first fragments M of the transmitted data blocks, an updated estimating the signal-to-noise ratio in the signal of the transmitting station z using the second fragments M of the transmitted data blocks, average the refined estimates of the signal-to-noise ratio obtained using the first and second fragments M of the transmitted data blocks. 19. The method according to claim 1, characterized in that for further clarification at the transmitting station the estimates of the signal-to-noise ratio in the signal of the transmitting station average the updated estimate of the signal-to-noise ratio in the signal of the transmitting station with one or more previous estimates of the signal-to-noise ratio in the signal transmitting station.

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