JP2005210210A - Transmission method of wireless packet data, and transmission system of wireless packet data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission system of wireless packet data, wherein terminals connected to a wireless network can transmit the wireless packet data to the wireless network by avoiding contention, without the need for providing a back-off time. <P>SOLUTION: The wireless packet transmission system is realized, wherein a transmission right information generating means of an access point generates transmission right information related to the transmission order of the terminals connected wirelessly on the basis of a received impartation request of the transmission right, transmits the transmission right information to all the terminals; whereas the respective terminals store the received transmission right information to their transmission right information storage means 48 and transmit packet data in the stored transmission order, and when the terminal with the transmission right does not transmits data, the next terminal having the transmission right transmits the data. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wireless packet data transmission method and wireless packet data transmission system for wirelessly transmitting packetized data (information signal) to a communication network, and more particularly to IEEE (The Institute of Electrical and Electronics Engineers, Inc./USA). The present invention relates to improvement in utilization efficiency of a MAC (Medium Access Control) layer of IEEE Std 802.11, which is a wireless local area network (LAN) standard standardized by the Institute of Electrical and Electronics Engineers.

  Conventionally, an access control method in the IEEE 802.11 MAC layer has been used as a method for wirelessly transmitting packetized data. In the transmission method using radio waves as a transmission medium, unlike the wired communication method, when data is simultaneously transmitted from a plurality of transmission terminals, they interfere with each other and interfere with communication. That is, data collision is an unavoidable problem.

  That is, when the transmitting side terminal is performing data transmission, the power received by the transmitting station is larger than the power received and transmitted from other transmitting terminals. Cannot detect that is being sent. Therefore, IEEE 802.11 uses an access control method called CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) to avoid data collision.

FIG. 10 shows an example of MAC access control when the number of terminals is 3 in connection with conventional data collision avoidance.
In the figure, the terminal 1 transmits data until the time indicated by (1). The terminal 2 and the terminal 3 have data to be transmitted.

  The terminal 2 and the terminal 3 execute the carrier sense of the line from the time point (1) when the terminal 1 has finished transmitting data, and check whether it is busy, that is, whether another terminal is using the line. When a state where there is no energy on the line is continuously detected, a fixed period called DIFS (Distributed Coordination Function Inter Frame Spacing) in which the detection time is 34 μsec, and a backoff given differently for each terminal Wait for a period of time.

  Terminal 2 and terminal 3 wait for a DIFS period that is the same time. After that, it waits for different backoff periods given by random numbers for each terminal. Since the back-off period of the terminal 2 shown here is shorter than that of the terminal 3, the terminal 2 transmits data from (2) at the end point.

  Terminal 3 checks the line after the end of backoff. However, since the transmission power of the terminal 2 is detected, no transmission is performed. Then, the terminal 3 waits for the DIFS and the newly selected backoff period from (3) after the transmission of the terminal 2 is completed, and when it is detected that there is no energy on the line at time (4), You can send for the first time.

  Here, since different values are used for each terminal during the backoff period, even if the terminals detect no carrier on the line at the same time, transmission is performed from different times. Since the start is made, the possibility of collision of packets transmitted on the line is kept low.

That is, each terminal selects a random time from a time range of 0 to CW based on the current CW (Contention Window) parameter of each terminal, and uses the selected time as a back-off period.
FIG. 11 shows values of CW parameters that have been conventionally used.

  In the figure, the horizontal axis represents the number of retransmissions, and the vertical axis represents the upper limit value of the CW coefficient. That is, a random value generated between 0 and 7 is used at the first transmission. A back-off time based on a random number generated between 0 and 15 for the second time, 0 to 31 for the third time, and 0 to 255 for the sixth and subsequent times is used. The back-off time is a time obtained by multiplying the coefficient value by 9 microseconds which is a slot time.

  As described above, in the conventional access control method based on CSMA / CA, a long back-off time is set for each retransmission, and a long time is required for transmission. This back-off system is not particularly problematic when the number of terminals is small, but packet collisions frequently occur as the number of terminals increases, and an increase in communication time becomes a significant problem.

Further, the IEEE 802.11 MAC access control system employs a mechanism for returning an ACK (Acknowledgment) from the receiving terminal side in order to ensure data delivery.
FIG. 12 shows a procedure of acknowledgment by ACK performed in the conventional IEEE 802.11 MAC access control method.

  The transmitting side terminal confirms that the DIFS period line is not used and starts data transmission. When the receiving side terminal confirms that the data is addressed to itself, it waits for 16 μsec SIFS (Short InterFrame Space) period after receiving the data, and when the data is normally received, ACK ( Acknowledgment).

  Since SIFS is set to 16 μsec and is shorter than DIFS (34 μsec) before starting normal data, ACK is transmitted with priority over other data communications. On the other hand, other terminals cannot access the line while the transmitting terminal and the receiving terminal are transmitting. That is, it is defined that other terminals can enter a transmission waiting state due to backoff in the contention section for the first time after confirming that the DIFS section line is not busy after the ACK is returned. .

  On the other hand, when a plurality of types of media data are multiplexed and transmitted from the transmission side device to the reception side device, the block generation means has a transmission side device having a function of restricting retransmission processing according to the characteristics of each medium. The media data is divided into blocks, error detection codes are attached, the multiplexing means are mixed and arranged so that the transmission means transmits, and the data retransmission means retransmits the block data notified from the receiving side device. There is a way to handle it.

In the receiving apparatus, the separating means separates the block data sequence received by the receiving means for each medium, the reproducing means reproduces each media data, and the retransmission request means detects a transmission error by the error detecting means. This block is notified to the transmission side device. Also, at least one of the transmission side device and the reception side device has a retransmission setting means for setting whether or not to perform retransmission processing for each medium, and restricts retransmission processing for each medium based on this setting. There is a method of transmitting and receiving media data including a retransmission control means (see, for example, Patent Document 1).
JP-A-10-341217

  However, in conventional access control in IEEE802.11, carrier sense is performed during DIFS (Distributed Coordination Inter Frame Spacing) before data transmission, and it is confirmed that there is no terminal using the line. After waiting for the back-off time to avoid collision with the system, the transmission can be started for the first time. The value of the back-off time increases as the number of retransmissions increases. Therefore, when the number of terminals is large, there is a problem that the line use efficiency is extremely lowered.

  Therefore, in the present invention, an access point (master unit) creates a virtual polling order (order in which a transmission right is given) in advance based on information on terminals participating in the network, and transmits them to all terminals. The terminal that receives it can grasp the order in which the transmission right is obtained, so that each terminal can perform transmission sequentially without using a back-off time to avoid contention. It is.

  Furthermore, the present invention aims to reduce the dead time on the line, which has been increased with the number of terminals in the conventional method, and further, a shorter WT (Waiting Time) compared with the normal DIFS. It is an object of the present invention to provide a wireless packet data transmission method and a wireless packet data transmission system in which the line utilization efficiency is further improved by using the carrier sense time before transmission.

In order to solve the above-mentioned problems, the present invention comprises the following means 1) to 3).
That is,

1) Wireless packet data in a wireless packet data transmission system including a plurality of terminals that divide continuous data into packets and transmits the packets to a wireless network, and a control terminal that gives the terminals the transmission right according to the transmission order of the packet data. A transmission method,
A first step of transmitting a transmission right grant request to the control terminal from a terminal desiring to transmit packet data to the wireless network;
The control terminal that has received the request for granting the transmission right transmitted in the first step has already transmitted the grant request and includes the terminal to which the transmission right is given, and the transmission right according to the transmission order of the packet data. A second step of creating and transmitting information to the plurality of terminals;
Among the plurality of terminals, one terminal to which a transmission right is given by the transmission right information is detected after a predetermined first time has elapsed for detecting that there is no carrier in the wireless network. A third step of transmitting packet data;
When transmission from one terminal to which a transmission right is given is not performed after the first time has passed and until after the second time has passed, a terminal having the next transmission right in the next order has passed the second time. A fourth step of transmitting packet data later;
A wireless packet data transmission method characterized in that one terminal to which a transmission right is given transmits packet data in order.
2) Wireless packet data in a wireless packet data transmission system including a plurality of terminals that divide continuous data into packets and transmits the packets to a wireless network, and a control terminal that gives the terminals the transmission right according to the transmission order of the packet data. A transmission method,
A first step of transmitting a transmission right grant request from a terminal desiring to transmit packet data to the wireless network;
The control terminal that has received the transmission right grant request transmitted in the first step includes the transmission right that has already transmitted the grant request and includes the terminal to which the transmission right is given, in accordance with the transmission order of the packet data. A second step of creating and sending information to all terminals;
A third step of transmitting packet data in order from each terminal in accordance with the transmission right information after a predetermined first time has elapsed after detecting the absence of a carrier in the wireless network;
After transmission of the first time, when transmission from the terminal to which the transmission right is given and the terminal to which the next transmission right is given is not performed twice over the second time, the next next order is performed. A fourth step in which a terminal having the right to transmit transmits after the second time has elapsed;
And transmitting packet data in order from a terminal to which a transmission right is given.
3) A wireless packet data transmission system including a plurality of terminals that divide continuous data into packets and transmits the packets to a wireless network, and a control terminal that gives the terminals the transmission right according to the transmission order of the packet data,
The control terminal,
A grant request receiving means for receiving a request for granting a transmission right related to transmission of packet data transmitted from the terminal to the wireless network;
Transmission right information creating means for creating transmission right information related to the order of transmission of all terminals that wish to transmit packet data, including the received grant request;
While the apparatus has a transmission right information transmitting means for transmitting to all terminals that can receive the created transmission right information,
The respective terminals,
Transmission right information storage means for receiving the transmission right information and temporarily storing the transmission right information obtained by receiving the transmission right information;
When the transmission order stored in the transmission right information storage means is next to next, a carrier exists in the wireless network in a predetermined first time interval, and follows the first time interval Carrier detection means for detecting whether a carrier is present in the wireless network in a second time interval;
Packet data transmitting means for transmitting the packet data when no carrier is detected in both the first time interval and the second time interval by the carrier detecting means;
The wireless packet data transmission system is configured to transmit the packet data by moving up one order when no carrier is detected at the second time interval in the previous period.

According to the wireless packet data transmission method and wireless packet data transmission system of the present invention, the following effects 1) or 2) can be provided.
That is,

1) The control terminal that has received the transmission right grant request creates transmission right information related to the transmission order of the packet data and transmits it to a plurality of terminals, and the terminal that is given the transmission right transmits the packet data in order. Since the terminal having the transmission right transmits the packet data when no transmission is performed from the terminal to which the transmission right is given, the dead time due to the back-off for avoiding the packet collision is reduced, and the frequency utilization efficiency is reduced. It is possible to transmit wireless packet data having a high level.
2) As for the transmission right given to each terminal device in order, if the previous terminal and the previous terminal do not transmit, the terminal having the transmission right next to the next transmits the wireless packet data, etc. By using the waiting time assigned with the shortest time interval, the transmission right can be skipped efficiently, and wireless packet data with high frequency utilization efficiency can be transmitted.

  Hereinafter, preferred embodiments of the wireless packet data transmission method and wireless packet data transmission system according to the present invention will be described.

  FIG. 1 shows a schematic configuration of the wireless packet data transmission system, which will be described with reference to the drawings.

  The wireless packet data transmission system shown in FIG. 1 includes an access point (hereinafter abbreviated as AP, or sometimes referred to as a control terminal or a base unit) 1, a terminal A2a, and a terminal B2b. Each of terminal (hereinafter also referred to as STA) A2a, terminal B2b, and AP1 is connected to each other via a wireless network. The terminals A2a and B2b perform wireless communication while being controlled by the AP1, and transmit desired packetized digital data from the terminal A2a via the wireless network, and the terminal B2b receives it.

Next, an access operation performed by the terminal A2a, the terminal B2b, and the AP1 via the wireless network will be described.
FIG. 2 shows an access procedure performed between these wireless devices by an operation diagram. An example in which terminal B2b performs communication using a wireless network in which terminal A2a and access point 1 communicate with each other will be described.

  First, the terminal B2b transmits a participation request (Association Request) to the access point in (1). The participation request is transmitted after confirming that the wireless network is not being used by another terminal after the RRIFS (Recovery / Request Inter Frame Space) period described later.

  The access point 1 that has received the participation request gives a transmission right to the terminal in (2) based on the information of the terminals that have participated in the network so far. The access point 1 determines the polling order based on the assigned transmission right and creates a Virtual Polling Order.

  The access point 1 waits for an APIFS (AP Inter Frame Space) section of 20 μsec after the Association Request from the terminal B 2b, and then in (3) the Virtual Polling Order (the order in which the transmission right is given) and then the transmission right is given. An association response including information on the terminal to be transmitted is returned to all terminals.

  All terminals on the network store these pieces of information in the storage area in the terminal in (4) and use them for determining the transmission right at the time of data transmission. As a result, all terminals to which the transmission right is given repeat transmission in the order of 5a, 5b, 5c,.

  Then, when a participation request is issued from another terminal, and when a terminal that ends data transmission and does not require participation occurs, the access point 1 updates the transmission right based on the participation request or non-participation request. A table related to is created and transmitted to each terminal. Thereafter, the above cyclic data transmission is repeated.

  When the access point 1 rejects the participation request from the terminal, the access point 1 returns a message indicating that the request cannot be approved or an association response including the necessary waiting time to the terminal.

Next, the configuration of the terminal device that performs these operations will be described.
FIG. 3 shows a schematic configuration of a transmission apparatus that generates OFDM (Orthogonal Frequency Division Multiplexing), and its operation will be described with reference to the drawings.

  The OFDM signal transmitting apparatus shown in the figure includes an error correction signal adding unit 32, a mapping unit 33, an inverse Fourier transform unit 34, a guard interval adding unit 35, a high frequency signal processing unit 36, a transmission order table unit 37, and a transmission control unit 38. Consists of.

  First, the information signal supplied to the error correction signal adding unit 32 is a signal that needs to be transmitted continuously, such as a digital video signal. The error correction signal adding unit 32 adds a correction code for correcting error data generated during transmission. Next, the digital data to be transmitted by the mapping circuit 33 is mapped onto a plurality of QAM (Quadrature Amplitude Modulation) planes.

  The respective data mapped to the plurality of QAM planes are subjected to inverse Fourier transform by an inverse Fourier transform unit 34, and a plurality of orthogonal frequency division modulated signals modulated as signals of the respective QAM planes are generated. A guard interval for reducing multipath distortion is added to the orthogonal frequency division signals by the guard interval adding unit 35.

  The orthogonal frequency division signal to which the guard interval is added is subjected to predetermined signal processing for radiating to the spatial transmission path by the high-frequency signal processing unit 36, and is transmitted to the wireless network via the antenna circuit in a time zone during which transmission is permitted. Is output.

  Here, the transmission order table unit 37 temporarily stores the information related to the transmission right transmitted and received from the access point 1, and supplies the stored information related to the transmission right to the transmission control unit 38. The transmission control unit 38 is supplied with carrier presence / absence information detected by a carrier sense 42 described later.

  The transmission control unit 38 determines a time during which transmission is permitted based on the supplied signal, and is generated by the high-frequency signal processing unit 36 and waits for the orthogonal frequency division signal to be transmitted during a time period during which transmission permission is given. Is controlled to be transmitted.

  FIG. 4 shows a schematic configuration of a receiving apparatus that receives OFDM (Orthogonal Frequency Division Multiplexing), and the operation will be described with reference to the drawings.

  The OFDM signal receiving apparatus shown in the figure includes a high frequency signal processing unit 41, a carrier sense unit 42, a guard interval removal unit 44, a Fourier transform unit 45, a demapping unit 46, an error signal correction processing unit 47, and a transmission order table acquisition unit. 48.

  First, a signal on the wireless network, which is a spatial transmission path acquired by the antenna circuit, is amplified by the high frequency signal processing unit 41. A part of the amplified signal is supplied to the carrier sense unit 42 and the other part is supplied to the guard interval removing unit 44.

The carrier sense unit 42 detects whether or not a carrier signal exists on the wireless network, and the detected result is supplied to the transmission control unit 38.
The guard interval removing unit 44 removes the guard interval signal added by the guard interval adding unit 35.

  Next, the orthogonal frequency division multiplexed signal from which the guard interval portion is removed by the Fourier transform unit 45 is Fourier transformed, and as a result, signal point information on the QAM plane is obtained. The demapping unit 46 performs an operation complementary to that performed by the mapping unit 33 to obtain the transmitted digital information.

When the transmitted information signal includes error data, the error signal correction processing unit 47 corrects the error data and outputs the obtained digital information signal.
On the other hand, the transmission order table transmitted from the access point 1 is subjected to predetermined signal processing by the high-frequency signal processing unit 41, the guard interval removal unit 44, the Fourier transform unit 45, and the demapping unit 46, and the transmission order table acquisition unit 48. Supplied to get.

  The acquired transmission order table is supplied to the above-described transmission order table unit 37, temporarily stored therein, and time control of the transmission signal is performed. Similarly, when an association response including a virtual polling order is returned from the access point in response to a participation request from each terminal, all terminals existing on the network have the current polling order and transmission right. You can know the information of the terminal.

  The configuration of the OFDM signal transmitting apparatus and the OFDM signal receiving apparatus and their operations have been outlined above. The terminal device is a device having both an OFDM signal transmitting device and an OFDM signal receiving device, and the access point 1 has a determination function for managing transmission rights in addition to the functions possessed by the terminal device, and a transmission order table. It has a function and a function for managing the operation of the terminal on the wireless network by distributing the transmission order table to each terminal device. These functions are realized by executing a built-in computer.

Next, time management of signals flowing through the wireless network performed by the access point will be described in detail.
FIG. 5 shows an operation related to establishment of a communication path performed by the terminal A2a and the terminal B2b accessing the access point 1 and its time relationship.

AP1, terminal A2a, and terminal B2b are shown vertically, and the horizontal axis shows time.
First, the terminal A2a transmits a participation request to the AP1. That is, the terminal A2a transmits (7) an association request (Association Request) after elapse of 24 μs, which is a time during which data transmission in AP1, for example, is completed and no carrier is detected in the wireless network, as shown in (6).

  Here, the above 24 μs is a time defined as RRIFS (Recovery / Request Inter Frame Space) described later. Upon receiving the request, AP1 returns a response (Association Response) (8) to the participation request after the elapse of 20 μs defined as APIFS (Access Point Inter Frame Space).

  Next, the terminal B 2 b transmits a participation request (9) after 24 μs (PRIFS) has elapsed after the end of (Association Response) (8), when no carrier is detected. AP1 creates a transmission order table in which the right to transmit is given to the terminal B2b after the elapse of 20 μs as described above, and returns the table as an Association Response (10).

The relationship between the operation time related to the transmission of the participation request from the terminal and the return from the AP has been described above. These operations will be further described.
FIG. 6 shows four IFS (Inter Frame Space) and one WT (Waiting Time), which will be described.

  In the figure, the four IFSs are defined as the elapsed time since the carrier is no longer detected in the wireless network, SIFS (Short Inter Frame Space) is 16 μs, APIFS is 20 μs, RRIFS is 24 μs, VPIFS (Virtual Poling Inter Frame Space) is defined as 28 μs. The WT is defined as 4 μsec.

  Here, SIFS is an IFS used to transmit high priority data, and 16 μs is allocated. APIFS is an IFS for the access point to transmit data preferentially to the terminal, and 20 μs is allocated. RRIFS is an IFS for a terminal to request allocation of VPIFS, and includes a request for participation (Association Request), an authentication request (Authentication request), and a probe request (Probe request). 24 μs is allocated.

  VPIFS (Virtual polling IFS) is an IFS used when a terminal to which a transmission right is attached transmits data, and 28 μsec is allocated. Unless transmission with priority over VPIFS is performed, only a terminal having a transmission right transmits continuous data such as AV data following the period of VPIFS.

The WT waits for the terminal having the transmission right to start transmission when the terminal having the transmission right does not transmit during the VPIFS period and the carrier is not detected during the WT period. It's time. 4 μs is allocated.
In the above, four IFS and one WT have been described.

Next, a case where data is transmitted from a plurality of terminals according to VPIFS will be described.
FIG. 7 illustrates an example in which terminals A to C sequentially transmit continuous data under the control of VPIFS.

  Here, according to the transmission order table (Virtual Polling Order) from the access point, each terminal in advance is the order of the terminals that perform transmission, and which terminal is currently in a transmittable state, that is, in a virtually polled state. Suppose that you always know.

  First, the terminal A designated to perform transmission first confirms by carrier sense that the line is not busy for 28 μsec of VPIFS. If no carrier is detected, the first part of the continuous data is transmitted. Note that the period indicated as data transmission in the figure includes ACK (acknowledgement) that is a response from the receiving terminal for data transmission and reception (the same applies hereinafter).

  Terminal B and terminal C refer to the transmission order table transmitted and stored from the AP, and recognize that terminal A is transmitting data. Terminal B waits for 28 μsec of the next VPIFS after terminal A completes data transmission. If no carrier is detected, terminal B transmits terminal B data. Similarly, terminal C transmits data after the next VPIFS.

  When the AP does not change the transmission order table (Virtual Polling Order) and each terminal A, B, and C has data to be transmitted, the data is sequentially received while waiting for the VPIFS period. Send.

  Next, for example, when there is no data to be transmitted to the terminal A, the terminal A does not transmit, and the terminal B in the next order transmits continuously. That is, when no carrier is detected during the WT period following VPIFS, terminal B recognizes that the transmission order is the next terminal B and transmits data.

  Similarly, when terminal A and terminal B do not transmit data, terminal A does not transmit at the next WT of VPIFS, and terminal B does not transmit at the next WT. Data transmission of terminal C is performed in the next period.

  The operation example when there is no transmission data has been described above. The terminal given the transmission order by the AP performs data transmission every VPIFS period, and when there is no data to be transmitted, the terminal order given every WT period is automatically skipped and data is transmitted. Yes. Here, 28 μsec is allocated for the VPIFS period, but the time for skipping transmission is performed using, for example, a 4 μsec WT.

  Therefore, the transmission order is determined by the transmission order table and the data is transmitted in order to fix the use of the band and reduce the utilization rate. However, the transmission order is changed for each WT having a period of 2 μs. Skip, that is, the transmission right is transferred to prevent a decrease in frequency utilization rate.

The above is an example in the case of operating with a terminal that transmits a small amount of data. Next, the handling of a terminal that has no data to transmit will be further described.
FIG. 8 shows and describes an operation when a terminal that does not perform data transmission is excluded from the transmission order table.

  In this figure, since it is expected that terminal A will not generate transmission data for a while, terminal A issues a Virtual Polling Skip Request itself. Terminal A that does not generate transmission data transmits a Virtual Polling Skip Request during the data transmission period given to terminal A.

  The AP that has received the Virtual Polling Skip Request creates a Virtual Polling Order excluding the terminal A. A Virtual Polling Skip Response that specifies the created Virtual Polling Order and the terminal to be transmitted next to that Order is returned.

  The Virtual Polling Skip Response is managed in the order of transmission by the AP, is received by all terminals in the active state, and updates the transmission order table stored in the storage area of the transmission order table of each terminal. As a result, the terminal A is deleted from the list at the time of sequential transmission.

Next, an operation in the case where data to be transmitted to the terminal A is generated and the transmission is performed again for the AP that restores the transmission right will be described.
FIG. 9 shows the operation in the case of applying for the resurrection of transmission rights.

  In the figure, for example, after the VPIFS period after the terminal B transmits data, the transmission right is transferred to the next terminal. Therefore, a Virtual Polling Recovery Request is transmitted from the terminal A after a RRIFS period shorter than the waiting time VPIFS. The AP that has received the Virtual Polling Recovery Request creates a Virtual Polling Order with the terminal A added again, and transmits a Virtual Polling Recovery Response including this information and terminal information that should have the next transmission right.

  All the terminals in the network have received this, and update the Virtual Polling Order stored in each terminal to the latest state. Through these processes, the terminal A is added to the terminal that sequentially transmits data.

  As described above, an AP (access point) that should also be referred to as a parent device is defined in the wireless network, and the AP creates a transmission order table and transmits it to each terminal wirelessly connected to the network. Each terminal recognizes the transmission order based on the transmission order table, and transmits data during the period assigned to the terminal. A terminal with less data to transmit transmits data transmission to the next terminal after WT by appropriately suspending data transmission.

  The terminal to which the transmission right is given performs data transmission every VPIFS period. The other terminal that desires data transmission requests the transmission right from the AP during the RRIFS period shorter than VPIFS, and the AP that has received it creates an updated transmission right list and transmits it to all terminals.

  According to the wireless packet data transmission system described in the present embodiment, even if the amount of data to be transmitted is different for each terminal, the transmission right can be transferred within a short period of WT. A wireless data transmission system with high bandwidth utilization efficiency can be configured without transmitting information relating to the transfer of rights.

  Note that the information related to the granting of the transmission right transmitted from the AP including the virtual polling order is important information for normal operation of the wireless packet transmission system, so that the information is normally received from all terminals. After obtaining the confirmation information (ACK), the operation related to transmission right assignment and transfer may be executed.

  In addition, the transmission right grant and transfer made by connecting two or three terminals to one AP have been described. The number of terminals is not limited to this. For example, even when the number of terminals exceeds 10, for example, transmission right can be assigned and assigned. In that case, for example, a wireless packet transmission system with improved bandwidth utilization efficiency is configured to recursively operate so as to transfer the transmission right to the next terminal every time WT, which is a short time of 4 μs, for example. can do.

  The configuration and operation of the wireless packet data transmission system have been described above in detail. The system defines and operates four IFS examples. Different times may be allocated as long as the difference between each IFS is recognized by the terminal and the priority order can be defined. In addition, although four types of IFS have been described, the number of IFSs may be defined and used according to the purpose and function in system design, and is suitable even when the number is less than four or more than four. An operating wireless network system can be configured.

  The present invention can be used to realize a wireless packet data transmission system applicable to a wireless LAN that connects a plurality of terminal devices to the Internet.

It is a figure which shows schematic structure of the radio | wireless packet data transmission system based on the Example of this invention. 6 is an operation diagram illustrating a procedure of access performed between wireless devices according to an embodiment of the present invention. It is a figure which shows schematic structure of the OFDM transmitter which has a transmission order table based on the Example of this invention. It is a figure which shows schematic structure of the OFDM receiver which acquires the transmission order table based on the Example of this invention. It is a figure which shows the operation | movement which concerns on establishment of the transmission right based on the transmission order based on the Example of this invention. It is a figure which shows the time relationship of four IFS and one WT based on the Example of this invention. It is a figure which shows the transmission sequence of radio | wireless packet data based on the Example of this invention. It is a figure which shows the operation | movement in the case of removing from a transmission order table based on the Example of this invention. It is a figure which shows the resurrection operation | movement of the radio | wireless packet data transmission right based on the Example of this invention. It is a figure which shows the outline of operation | movement of the wireless packet data transmission system based on a prior art example. It is a figure which shows the value of a CW parameter based on a prior art example. It is a figure which shows the procedure of the delivery confirmation by ACK based on a prior art example.

Explanation of symbols

1 Access point 2a Terminal A
2b Terminal B
32 Error correction signal adding unit 33 Mapping unit 34 Inverse Fourier transform unit 35 Guard interval adding unit 36 High frequency signal processing unit 37 Transmission rank table unit 38 Transmission control unit 41 High frequency signal processing unit 42 Carrier sense unit 44 Guard interval removing unit 45 Fourier transform Unit 46 demapping unit 47 error signal correction processing unit 48 transmission order table acquisition unit

Claims (3)

Wireless packet data transmission method in a wireless packet data transmission system comprising a plurality of terminals that divide continuous data into packets and transmit them to a wireless network, and a control terminal that gives the terminals the transmission right according to the transmission order of the packet data Because
A first step of transmitting a transmission right grant request to the control terminal from a terminal desiring to transmit packet data to the wireless network;
The control terminal that has received the request for granting the transmission right transmitted in the first step has already transmitted the grant request and includes the terminal to which the transmission right is given, and the transmission right according to the transmission order of the packet data. A second step of creating and transmitting information to the plurality of terminals;
Among the plurality of terminals, one terminal to which a transmission right is given by the transmission right information is detected after a predetermined first time has elapsed for detecting that there is no carrier in the wireless network. A third step of transmitting packet data;
When transmission from one terminal to which a transmission right is given is not performed after the first time has passed and until after the second time has passed, a terminal having the next transmission right in the next order has passed the second time. A fourth step of transmitting packet data later;
A wireless packet data transmission method characterized in that one terminal to which a transmission right is given transmits packet data in order. Wireless packet data transmission method in a wireless packet data transmission system comprising a plurality of terminals that divide continuous data into packets and transmit them to a wireless network, and a control terminal that gives the terminals the transmission right according to the transmission order of the packet data Because
A first step of transmitting a transmission right grant request from a terminal desiring to transmit packet data to the wireless network;
The control terminal that has received the transmission right grant request transmitted in the first step includes the transmission right that has already transmitted the grant request and includes the terminal to which the transmission right is given, in accordance with the transmission order of the packet data. A second step of creating and sending information to all terminals;
A third step of transmitting packet data in order from each terminal in accordance with the transmission right information after a predetermined first time has elapsed after detecting the absence of a carrier in the wireless network;
After transmission of the first time, when transmission from the terminal to which the transmission right is given and the terminal to which the next transmission right is given is not performed twice over the second time, the next next order is performed. A fourth step in which a terminal having the right to transmit transmits after the second time has elapsed;
And transmitting packet data in order from a terminal to which a transmission right is given. A wireless packet data transmission system comprising a plurality of terminals that divide continuous data into packets and transmits the packets to a wireless network, and a control terminal that gives transmission rights to those terminals in the order of transmission of packet data,
The control terminal,
A grant request receiving means for receiving a request for granting a transmission right related to transmission of packet data transmitted from the terminal to the wireless network;
Transmission right information creating means for creating transmission right information related to the transmission order of all terminals that wish to transmit packet data, including the received grant request;
While the apparatus has a transmission right information transmitting means for transmitting to all terminals that can receive the created transmission right information,
The respective terminals,
Transmission right information storage means for receiving the transmission right information and temporarily storing the transmission right information obtained by receiving the transmission right information;
When the transmission order stored in the transmission right information storage means is next to next, a carrier exists in the wireless network in a predetermined first time interval, and follows the first time interval. Carrier detection means for detecting whether a carrier is present in the wireless network in a second time interval;
Packet data transmission means for transmitting the packet data when no carrier is detected in both the first time interval and the second time interval by the carrier detection means;
The wireless packet data transmission system is configured to transmit the packet data by moving up one order when no carrier is detected at the second time interval in the previous period.