KR100580834B1 - Access method between mobile terminals in Mobile Ad hoc network and mobile terminal therefor - Google Patents

Abstract

The present invention provides a wireless terminal multiple access method and a terminal that can alleviate problems among various terminals while giving a plurality of terminals a more fair opportunity when multiple terminals access a TDMA channel. do.

According to the present invention, one or more synchronization points are generated by receiving a synchronization signal according to a reference time, and a channel signal is detected during a predetermined channel detection interval (SCSP) based on the synchronization point. In this case, if the channel signal is not detected, after the channel detection section is terminated, the transmission request signal is transmitted and received between the terminal for data transmission during the transmission request signal section, and after the transmission request signal section is finished, the transmission approval signal section is completed. Transmits and receives a transmission approval signal. In this way, a data channel to which data is transmitted and received is formed on the basis of the transmission request signal and the transmission approval signal, and data is transmitted and received through this data channel.

In order to secure the right to use the data channel, by performing the transmission request approval process synchronously between terminals, the system can operate stably and guarantee fairness between terminals. In addition, the problem of the hidden terminal, the problem of the exposure terminal, the problem of the standby terminal can be significantly improved.

TDMA, terminal, synchronization signal, multiple access, data channel, Ad-Hoc

Description

Random access method between terminals and a terminal device for the same {Access method between mobile terminals in Mobile Ad hoc network and mobile terminal therefor}

1 is a diagram illustrating a problem of a hidden terminal.

2 is a flowchart illustrating a hidden terminal problem in an interference avoidance multiple access (MACA) scheme.

3 is a diagram illustrating a problem of an exposed terminal.

4 is a flowchart illustrating a problem of an exposure terminal in FAMA.

5 is a flowchart illustrating a problem of a standby terminal.

6 is a synchronization timing diagram of terminals according to the first embodiment of the present invention.

7 is a synchronous timing diagram for terminal synchronization according to the first embodiment of the present invention, (a) is a view showing the overall channel occupancy state, (b) is a view showing a channel occupancy state of each terminal.

8 is a flowchart illustrating a channel multiple access method according to a first embodiment of the present invention in order.

9A is a diagram illustrating an example of using a response channel to eliminate a hidden terminal problem in a fast fading channel environment.

FIG. 9B is a diagram illustrating an example of using a reverse channel to remove a hidden UE problem in a fast fading channel environment.

10 is a diagram schematically illustrating a configuration of a multiple access terminal according to an embodiment of the present invention.

FIG. 11A illustrates a channel utilization state in a channel multiple access method according to an exemplary embodiment of the present invention, and FIG. 11B illustrates a channel utilization state in a multiple access method according to a conventional method.

The present invention relates to a time division multiple access (TDMA), and more particularly, to a multiple access scheme in which a plurality of terminals transmit and receive data through a common channel.

Currently, mobile ad hoc network technology has emerged as a new technology area in the mobile communication field. Due to the characteristics of a network, wireless service applications are endless, with a network technology for exchanging necessary wireless data by improvising a network between wireless terminals without using a wireless base station or an access point (AP).

To date, several wireless access schemes have been devised, including CSMA / CA, Multiple Access Collision Avoidance (MACA) that complements CSMA / CA of IEEE802.11, Media Access Protocol for Wireless LANs (MACA), and Floor Acquisition Multiple Access (FAMA). However, there are still three basic problems in a wireless ad hoc network, a hidden node problem, an exposed terminal problem, and a waiting terminal problem.

That is, as the number of terminals increases and the channel load increases, saturation easily occurs, and the performance approaches zero. In addition, when a specific terminal acquires a right to use a channel, it has been used for a relatively long time.

1 is a diagram illustrating a problem of a hidden terminal.

The terminal A 11 and the terminal C 13 transmit data 101 to the terminal B 12 while the terminal A 11 is not in a communication distance with each other. Terminal C 13 that does not know this state may occur when sending the data 102 to the terminal B (12). In this case, the terminal B 12 cannot receive any data due to channel interference.

In order to solve this problem, in MACA (Multiple Access with Collision Avoidance), in order to transmit a relatively long data packet, a short request request packet (hereinafter referred to as RTS) and a transmission acknowledgment packet (Clear to Send) are required. , CTS hereinafter). This is called an RTS-CTS exchange, and the terminal A 11 sends a transmission request packet and the terminal B 12 receiving the transmission transmits a transmission acknowledgment packet. The transmission acknowledgment packet is received by the terminal A 11, but is also transmitted to the terminal C 13 to cause the terminal C 13 to withhold data transmission for a certain period of time.

However, even the MACA hidden terminal problem is not completely eliminated.

2 is a flowchart illustrating a hidden terminal problem in an interference avoidance multiple access (MACA) scheme.

As shown in FIG. 2, first, at a time point t1, the terminal A 11 sends an RTS 301.

At a next time t2, terminal C 13 transmits RTS 303 to terminal D 14. At the same time, the terminal B 12 transmits the CTS 302 to the terminal A 11 and the terminal C 13 in response to the RTS 301 transmitted by the terminal A 11.

However, the terminal C 13 does not know the existence of the CTS 302 transmitted from the terminal B 12 because the terminal C 13 transmits the RTS 303 to the terminal D 14.

At the time t3, the terminal D 14 transmits the CTS 306 for the RTS 303 to the terminal C 13, and the terminal A 11 transfers the data 305 to the terminal B 12. send.

At time t4, terminal A 11 continues to transmit data 305 to terminal B 12. On the other hand, since the terminal C 13 cannot communicate with the terminal A 11, the terminal C 13 does not know whether the data 305 is present and transmits the data 307 to the terminal B 12. Therefore, a collision of data in terminal B 12 occurs.

3 is a diagram illustrating a problem of an exposed terminal.

First, in FIG. 3, it is assumed that terminal A 21 and terminal C 23, terminal A 21 and terminal D 24, and terminal B 22 and terminal D 24 are in a communication impossible distance.

When the terminal B 22 transmits the data 201 to the terminal A 21, the terminal C 23 knows the data transmission of the terminal B 22 and stops transmitting and receiving the data 202 during the transmission period.

However, the terminal C 23 may transmit the data 203 to the terminal D 24 during this period, and the data 203 cannot be transmitted even though the terminal A 21 does not interfere with the terminal A 21. In other words, the channel is wasted by unnecessarily interrupting data transmission. This is a problem of the exposure terminal.

4 is a flowchart illustrating a problem of an exposed terminal in FAMA (Floor Acquisition Multiple Access).

In FIG. 4, it is shown that data transmission from the terminal B 22 to the terminal A 21 is delayed due to a transmission delay caused by the noise 403 in the terminal B 22.

5 is a flowchart illustrating a problem of a standby terminal.

At time t2, terminal C 53 sends RTS 502 to terminal D 54 and waits for CTS 506 from terminal D 54 to come from terminal B 52. Unnecessarily receiving the CTS 503 destined for 51 is treated as a noise 504 and goes to a transmission delay (505) back-off state.

However, the terminal D 54 receives the normal RTS 502 from the terminal C 53 and responds with the CTS 506 to the terminal C 53. However, since the terminal C 53 is already in the transmission delay state, there is no response, and the CTS 506 sent to the terminal C 53 by the terminal D 54 at the time t4 communicates with the terminal D 54. The terminal E 55 enters the standby 507 state by being sent to the terminal E 55 which is a possible neighbor terminal. This causes the terminal E 55 to fail to transmit and to wait.

As described above, in the MACA and FAMA schemes, there are still three basic problems: a problem of a hidden terminal, a problem of an exposed terminal, and a problem of a standby terminal.

In addition, this conventional method has relatively low demand response performance for data channel use. Therefore, once channel usage rights are secured, relatively long data is transmitted, and when the number of wireless terminals attempting to access a network increases, it is difficult to use a fair channel. Problems also exist.

In addition, in order to solve the problem of fairness, which is an important evaluation measurement factor for multiple access networks, the data packet length should be shortened to give terminals access opportunities evenly. Due to the increased number of data packets, the number of times of request response (RTS-CTS exchange or handshaking) for securing channel usage is inevitably increased. Therefore, the severity of the three basic problems in the wireless ad hoc network, the problem of the hidden terminal, the problem of the exposed terminal, the problem of the standby terminal further increases.

The technical problem to be achieved by the present invention is to alleviate the problem of the hidden terminal, the problem of the exposed terminal, the problem of the standby terminal while giving a plurality of terminals a more fair opportunity in the case of multiple access by multiple terminals in TDMA The present invention provides a multiple access method between wireless terminals and a terminal thereof.

A terminal-to-terminal multiple access method according to an aspect of the present invention is a random access connection method between terminals for transmitting and receiving data between a plurality of terminals using a time division multiple access scheme.

a) receiving at least one synchronization signal from a specific synchronization source existing outside, and generating at least one synchronization point having a predetermined synchronization period based on the synchronization signal;

b) detecting a channel signal during a predetermined channel detection period based on the synchronization point;

delete

c) If the channel signal is not detected, after the channel detection section is terminated, the transmission request signal section and the transmission approval signal section each including a plurality of slots corresponding to each other are set, and the transmission request signal section and transmission Transmitting and receiving a transmission request signal and a transmission acknowledgment signal with a terminal that wants to transmit data through the grant signal interval; And

d) a data channel to which data is transmitted and received based on the transmission request signal and the transmission approval signal transmitted and received through the transmission request signal slot and the transmission approval signal slot corresponding to each other on the transmission request signal section and the transmission approval signal section; And transmitting and receiving data through the formed data channel.
Step c) may include a transmission request signal section for transmitting and receiving a transmission request signal; And a transmission approval signal section for transmitting / receiving a predetermined transmission approval signal after the transmission request signal section ends.

The transmission request signal section may be a time at which a plurality of transmission request signal slots may be transmitted to transmit and receive a plurality of transmission request signals.

The transmission acknowledgment signal period may be a time at which a plurality of transmission acknowledgment slots may be transmitted to transmit and receive a plurality of transmission acknowledgment signals.

When the transmission request signal is received through the first transmission request signal slot among the plurality of transmission request signal slots, the terminal that transmitted the transmission request signal is transmitted to the first transmission request signal slot from the plurality of transmission approval signal slots. The transmission approval signal may be transmitted through the corresponding first transmission approval signal slot.

The priority of channel formation may be determined based on the order of the transmission request signal and the transmission approval signal slot.

In step d), when the data channel is formed, a data channel may not be formed between two terminals connected through the data channel and other terminals in a communicable state.

In step d), when the data channel is formed, a data channel may not be formed between two terminals connected through the data channel and other terminals in a communicable state.

After the step d), after the transmission and reception of data is finished, the terminal receiving the data may further include transmitting a data reception confirmation signal to the terminal that has transmitted the data.

The data reception confirmation signal may exist between a time point at which the data transmission ends and a time point at which a channel detection section of a subsequent sync point ends.

According to another aspect of the present invention, a terminal apparatus is a random access terminal apparatus capable of transmitting and receiving data between a plurality of terminal apparatuses using a time division multiple access scheme.

Receives a synchronization signal from a specific synchronization source existing outside, generates one or more synchronization points having a predetermined synchronization period based on the synchronization signal, and detects a channel signal during a predetermined channel sensing interval based on the synchronization point. And a synchronization unit generating an event signal allowing data transmission and reception when the channel signal is not detected;

The first transmission request signal is transmitted based on the event signal, the first transmission approval signal corresponding to the first transmission request signal is received, and the second transmission request signal is generated based on the first transmission request signal and the first transmission approval signal. A data transmitter for transmitting data through the data channel; And

Receiving a second transmission request signal from a terminal requesting connection based on the event signal, transmitting a second transmission approval signal corresponding to the second transmission request signal, and transmitting the second transmission request signal and the second transmission And a data receiver configured to receive data through a data channel generated based on the grant signal.

The synchronization unit may include: a synchronization signal receiver configured to receive synchronization information on a reference time from a specific synchronization source existing outside; And generating a synchronization point having a predetermined synchronization period based on the synchronization information, and detecting a channel signal during the SCSP based on the synchronization point and generating an event signal when the channel signal is not detected. It may include a terminal synchronization unit.

The data transmitter may include: a transmission request signal transmission unit configured to receive the event signal and transmit the first transmission request signal to a terminal to transmit data; A transmission acknowledgment signal receiver which receives the first transmission acknowledgment signal corresponding to the first transmission request signal; And a data transmission unit configured to transmit data by forming a data channel based on the first transmission request signal and the first transmission approval signal.

The data receiver may include a transmission request signal receiver configured to receive the second transmission request signal from a terminal to which data is to be transmitted; Transmission acknowledgment signal / data for transmitting the second transmission acknowledgment signal corresponding to the second transmission request signal and receiving data through a data channel generated based on the second transmission request signal and the second transmission acknowledgment signal. It may include a receiver.

The first transmission request signal and the second transmission request signal are transmitted and received during a predetermined transmission request signal interval after the channel sensing interval is terminated, and the transmission request signal interval is a plurality of transmissions to transmit and receive a plurality of transmission request signals. Request signal slots may be included.

The first transmission approval signal and the second transmission approval signal are transmitted and received during a predetermined transmission approval signal interval after the transmission request signal interval is terminated, and the transmission approval signal interval is a plurality of transmission and reception signals to transmit and receive a plurality of It may be a time at which the transmission acknowledgment slot can be transmitted.
When the data channel is formed, a data channel may not be formed between two terminals connected through the data channel and other terminals in a communicable state.

delete

The data transmission on the data channel may be started before the end of the channel sensing period based on the subsequent sync point.

When data reception is completed in the data receiver, a data reception acknowledgment signal is transmitted to a terminal that has transmitted data, and when data transmission is terminated in the data transmitter, an acknowledgment signal transmission and reception that receives a data reception confirmation signal from a terminal that has received data It may further include wealth.

The data reception confirmation signal may be transmitted between the time point at which the data transmission is terminated and the time point at which the channel detection section based on the subsequent synchronization point ends.

In order to achieve the above object, the terminal introduces a device for synchronizing the time between the terminals. The synchronization reference point of the terminal adopts a device for restoring the synchronization point by receiving a signal from a broadcasting station or the like for GPS satellite or terminal synchronization.

When the synchronization period of the synchronization reference point is longer than the synchronization period of the wireless network to be used, the terminal may generate and use a separate auxiliary synchronization point corresponding to the synchronization period of the wireless network to be used using the synchronization point.

The channel signal is observed during the synchronized carrier sense period based on the synchronization point, and when there is no signal, the channel signal is divided into a transmission request signal section and a transmission approval signal section previously promised on the time axis.

The two signal intervals are used to perform a request response (RTS-CTS exchange or handshaking) process to secure the right to use the data channel, and have a subsequent right to use the data channel according to a predetermined criterion.

The starting point of the data channel is possible from the end of the transmission acknowledgment signal period and must not exceed the synchronized channel detection period (SCSP) at the subsequent synchronization point.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification.

First, the wireless Ad-Hoc channel access method according to the first embodiment of the present invention will be described in detail with reference to FIG.

6 is a synchronization timing diagram of terminals according to the first embodiment of the present invention.

In the first embodiment, all terminals receive an external unified time synchronization point, such as a GPS or a synchronization broadcast channel, and access multiple wireless channels using the synchronization point. Specifically, when the synchronization point between the terminals is checked and a carrier signal is not detected for a predetermined time period based on the synchronization point on the channel time, a predetermined number of consecutive request signal (RTS) requests to After setting sequentially to the Send section and a predetermined number of consecutive Clear to Send (CTS) sections, the request response process is performed to secure the data channel.

First, in FIG. 6, the reference numeral '600' represents a time axis of the TDMA channel, and indicates a recent time toward the right, and points 6061 to 6057 on the time axis indicate synchronization points of terminals of the sequential channel. Therefore, the terminal synchronization period is between the synchronization point and the synchronization point, for example, between the synchronization point 6061 and the synchronization point 6602.

The terminal synchronization period may include a transmission request signal section 601 and a transmission approval signal section 602.

The transmit request signal section 601 includes one or more predetermined transmit request signal slots, which are referred to as a Synchronized Carrier Sense Period (SCSP) after the synchronization point 6601. Is set when no physical channel signal is captured. For example, in the terminal synchronization periods 6055 to 6056, the transmission request signal section 601 is set because no physical channel signal is detected in the SCSP 606 after the synchronization point 6055.

The transmission approval signal section 602 is set after a predefined time (Short Inter Frame Spacing, hereinafter referred to as SIFS) 607 after the transmission request signal section 601. The transmission request signal section 601 and the transmission approval signal section 602 consist of the same number of slots.

The starting point of the data channel 603 may start from the end of the transmission acknowledgment signal interval 602 and should not exceed the time of adding the SCSP 606 at the next first sync point 6602 at the latest. The data channel 603 may be followed by a confirmation channel (ack) 604 for data.

7 is a timing diagram for terminal synchronization according to a second embodiment of the present invention, (a) is a view showing the overall channel occupancy state, (b) is a view showing a channel occupancy state of each terminal.

In Fig. 7, the reference numeral '700' is the time axis of the TDMA channel. In addition, the terminal A to the terminal E are all located in the communication area, and at one sync point 7141, the terminal A is the terminal B, the terminal C is the terminal A, and the terminal D has data to be transmitted to the terminal E. It is assumed that the slots in the transmission request signal section 701 and the transmission approval signal section 702 are each predetermined to be three.

Since the SCSP 721 channel signal is not detected from the synchronization point 7141 for a predetermined time, the terminal C transmits a request packet to the first slot in the transmission request signal section 701 and the terminal D also transmits a request packet to the first slot. UE A transmits a transmission request packet to the third slot.

The first slot in the transmission approval signal section 702 has no content to be received at the destination due to a collision between the transmission request signal slots of the terminal C and the terminal D. However, the third transmission request signal slot sent by the terminal A is received by the terminal B, and the terminal B transmits a transmission acknowledgment packet for it through the third transmission approval signal slot.

Upon receipt of the transmission acknowledgment packet sent by terminal B, terminal A transmits a secure data packet 709 to terminal B.

For the synchronization points 7142, 7143, and 7144 occurring during data packet transmission, the standby terminals maintain the transmission standby mode because the signal of the terminal A is detected during the SCSP after each synchronization point. When the reception of the data packet is terminated, the terminal B transmits an ack signal 710 to the terminal A.

Since the channel signal is not detected during the SCSP 722 after the synchronization point 7145, the transmission request signal section 703 and the transmission approval signal section 704 are sequentially set.

In this case, due to the collision between the terminal D and the terminal C, there is no transmission approval packet in the transmission approval signal section 704 and the transmission request signal section 705 again because the channel is still empty during the SCSP 723 from the subsequent synchronization point 7146. ) And the transmission approval signal section 706 are sequentially set.

In this case, the terminal D receives the transmission approval from the terminal E through the first slot, and the terminal B receives the transmission approval from the terminal A through the second slot, but the terminal B yields the data channel right to the terminal D using the first slot. . This is because the terminal B can receive all slots of the transmission approval signal section. The method of judging whether to make concessions can be determined separately.

After the synchronization point 7148, the terminal D transmits data 711 to the terminal E, and the terminal E transmits a data reception confirmation signal ack to the terminal D.

Then, in the transmission request signal section 707 and the transmission approval signal section 708 starting from the synchronization point 7148, the terminal A and the terminal C have competed, but the terminal A has not received the transmission request signal slot at the receiving side. In this case, the transmission approval signal slot is transmitted to the terminal C from the terminal D on the receiving side of the transmitting terminal C. Therefore, the terminal C uses the data channel 713.

8 is a flowchart illustrating a channel multiple access method according to a first embodiment of the present invention in order.

The block 801 generates a sync point signal event to identify every sync cycle point of the network, manages sync points, and detects a physical channel signal for a predetermined time (SCSP) from the sync point.

When there is no channel signal for a certain time (SCSP) from the synchronization point, a transmission request signal event is generated.

802 waits for the transmission request signal event and starts controlling the multiple access flow when the event is received. If there is data to be transmitted, an instruction 803 for generating a transmission request packet is received, and then all the packets of the current transmission request signal interval are received (806) regardless of the presence or absence of data to be transmitted.

If there is a packet transmitted to the own terminal among the packets received at 806, the transmission approval packet is transmitted using the corresponding slot position of the transmission approval signal section (810), and subsequent data is received (811) and required. In case ACK, the packet is transmitted (812).

If none of the packets received in step 806 is transmitted to its own terminal, all packets in the transmission approval signal interval are received 807 and it is determined whether to transmit data in a manner determined according to the reception result (808). .

If the data transmission is determined, the data is transmitted (809) after the transmission approval signal section ends. After that, the process returns to the reception state of the transmission request signal event.

FIG. 9A is a diagram illustrating an example of using a response channel to eliminate hidden UE problem in a fast fading channel environment, and FIG. 9B is a diagram of an example of using a reverse channel.

First, in FIG. 9A, reference numeral '900' denotes a time axis of a TDMA channel, and 901 to 906 denote terminal synchronization points sequentially arranged at regular intervals.

At sync point 901, there is currently a data packet for terminal A to transmit to terminal B. First, since the channel signal was not detected during the SCSP 9091 period at the synchronization point 901, the transmission request signal section 911 and the transmission approval signal section 912 are sequentially set.

As shown in FIG. 9A, the terminal A selects the first slot of the transmission request signal section 911 to send a transmission request packet, and the terminal B receives this and transmits the transmission approval packet to the first slot of the transmission approval signal section 912. The terminal A secures the data channel 913 for transmitting data to the terminal B.

Under the fast fading environment, the terminal B may prevent the interference from the hidden terminal around which the transmission acknowledgment packet 912 is transmitted from the terminal B within the transmission acknowledgment signal interval 912 and the data packet 913 that cannot receive the terminal. The response packet 914 for the data packet 913 is transmitted over the following SCSP (9082) interval.

Thereafter, the terminal A transmits a subsequent data packet 915 to the next sync point 903 and transmits a response packet 916 for the data packet 915 to span the SCSP 9083.

In the same manner, subsequent transmission and reception of data is performed, and the transmission position of the final response slot 918 of the data is independent of the SCSP.

Next, in FIG. 9B, reference numeral '930' indicates a time axis of a TDMA channel, and 931 to 936 indicate sequentially arranged terminal synchronization points having a predetermined period.

At the sync point 931, there is a data packet for terminal A to transmit to terminal B.

First, since the channel signal was not detected during the SCSP 9381 period at the synchronization point 931, the transmission request signal section 941 and the transmission approval signal section 942 are sequentially set.

As shown in FIG. 9B, the terminal A selects the first slot of the transmission request signal interval and sends a transmission request packet, and the terminal B receives the transmission and transmits the transmission approval packet to the first slot of the transmission approval signal interval 942. A data channel 943 that terminal A sends to terminal B is secured.

To prevent interference from a hidden terminal under a fast fading environment, terminal A transmits data 943 to occupy a portion of SCSP 9282 past the next sync point and terminal B sends data 944 to terminal A. Subsequent transmission is initiated within SCSP 9382 and transmitted to occupy a portion of the next SCSP 9383.

If the data to be sent is short, fill it with arbitrary data and send it. That is, the SCSPs 9382, 9383, and 9384, which start transmitting or receiving data and end until they terminate, control the transmission period of each terminal.

10 is a diagram schematically illustrating a configuration of a multiple access terminal using synchronization.

The multiple access terminal 1000 includes a synchronization signal receiver 1001, a terminal synchronizer 1002, a data transmitter 1100, a data receiver 1200, and an acknowledgment signal receiver 1005.

The data transmitter 1100 includes a transmit request packet transmitter 1008, a transmit acknowledgment signal receiver 1003, and a data transmitter 1004, and the data receiver 1200 includes a transmit request signal receiver 1006 and a transmit acknowledgment signal. And a transmission / data receiving unit 1007.

The synchronization signal receiver 1001 receives a signal from various external synchronization sources (GPS, synchronization broadcast, synchronization terminal, etc.) and provides a reference point for terminal synchronization to the terminal synchronization unit 1002.

The terminal synchronizer 1002 generates a plurality of sync points so as to be divided into a plurality of sync cycles previously promised with reference to the provided sync reference points. In addition, if the channel signal is not detected during the SCSP from the generated synchronization point and the channel signal is not detected, the transmission request signal event is transmitted to the transmission approval signal receiver 1003, the transmission request signal receiver 1006, and the transmission request signal transmitter 1008. do.

The transmission approval signal receiving unit 1003, the transmitting request signal receiving unit 1006, and the transmitting request signal transmitting unit 1008, which receive a signal event, serve to provide a reference point for normal operation.

The transmission acknowledgment signal receiving unit 1003 recognizes the transmission acknowledgment signal section by using the event received from the terminal synchronization unit 1002 as a reference point, and receives the transmission acknowledgment signal and receives the transmission acknowledgment signal to receive the priority acknowledgment signal. For reference, the data transmission unit 1004 instructs data transmission. The data transmission unit 1004 instructed to transmit the data transmits the prepared data and transfers control to the confirmation signal receiving unit 1005 if necessary.

When the transmission request signal receiving unit 1006 receives the transmission request signal event from the terminal synchronization unit 1002, the transmission request signal receiving unit 1006 receives all the slots in the transmission request signal section and, if there is a packet coming to it, the transmission approval signal transmission / data receiving unit 1007. Forwards the request packet.

The transmission acknowledgment signal transmission / data receiving unit 1007 generates a transmission acknowledgment packet, transmits a transmission acknowledgment packet using a slot corresponding to the transmission request signal slot in the transmission acknowledgment signal interval, receives the data packet, and receives the data packet reception result. The signal is transmitted to the confirmation signal transmission / reception unit 1005.

When the transmission request signal transmission unit 1008 receives the transmission request signal event from the terminal synchronization unit 1002, the transmission request signal generation unit generates a transmission request packet when data to be transmitted is waiting, and transmits the transmission request using one slot selected within the transmission request signal interval. Send the packet.

FIG. 11A illustrates a channel utilization state in a channel multiple access method according to an embodiment of the present invention, and FIG. 11B illustrates a channel utilization state in a multiple access method according to a conventional method.

In Fig. 11A, the reference numeral '1100' indicates the TDMA time axis and the time flow flows from left to right. 11061 to 11066 indicate terminal synchronization points having a predetermined time period. In addition, it is assumed that there is no communication between the terminal C and the terminal D, the terminal E and the terminal A, and the terminal A and the terminal D cannot interfere with each other. Therefore, if the terminal D can only transmit and receive the transmission request packet and the transmission approval packet with the terminal E, the terminal A can only transmit and receive the transmission request packet and the transmission approval packet with the terminal C.

Specifically, in FIG. 11A, the terminal A 110A at the overlapping time shows the case in which there is data to be transmitted to the terminal C 110C and the terminal D 110D to the terminal E 110E. Here, it is assumed that one slot is set in each of the transmission request signal section 1101 and the transmission approval signal section 1102.

Although the terminal A 110A and the terminal D 110D simultaneously transmit the transmission request packets 11071 and 11072 in the transmission request signal section 1101, the interference does not occur in the terminal C 110C and the terminal E 110E.

In addition, the terminal C (110C) and the terminal E (110E) simultaneously transmits the transmission approval packet (11081, 11082) in the section (1102), but the terminal A (110A) and the terminal D (110D) does not occur.

Accordingly, the terminal A 110A and the terminal D 110D may simultaneously transmit data packets 1103 and 1104, and likewise, the terminal C 110C and the terminal E 110E may receive it normally. This improves channel performance to 200%.

Meanwhile, in FIG. 11B, the transmission approval packet 11181 transmitted by the terminal C 111C is transmitted through the transmission approval signal section 1114 and the terminal E 111E transmits the transmission request packet from the terminal D 111D. 11172 cannot be received in the transmission request signal section 1113, and terminal E111E does not send a transmission approval packet to terminal D111D. Therefore, data transmission from the terminal D 111D to the terminal E 111E is not performed.

Although not specifically shown, the same effect can be obtained also in the case of the data transfer direction opposite to the data transfer direction in Figs.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited thereto, and various other changes and modifications are possible.

According to the present invention described above, all the terminals receive the external unified time synchronization point such as GPS or synchronous broadcast channel, and the number of terminals sharing one wireless channel increases in a wireless channel multiple access method using the synchronization point. Even so, the system is not easy to fall out of service.

In addition, when the length of the data packet is relatively short and the number of data packets to be processed is large, a lot of request approval (RTS-CTS exchange or handshaking) processes are required to secure the right of the data channel. Operation can be facilitated to ensure the fairness (fairness) between terminals.

In addition, even if the distribution density of the terminal is increased, the problem of the hidden terminal, the problem of the exposure terminal, the problem of the standby terminal described above is eliminated or greatly reduced, thereby greatly improving the performance and service quality of the wireless ad hoc network required in the future. have.

Claims (20)

In the random access connection method between terminals for transmitting and receiving data between a plurality of terminals using a time division multiple access method, a) receiving at least one synchronization signal from a specific synchronization source existing outside, and generating at least one synchronization point having a predetermined synchronization period based on the synchronization signal; b) detecting a channel signal during a predetermined channel detection period based on the synchronization point; c) If the channel signal is not detected, after the channel detection section is terminated, the transmission request signal section and the transmission approval signal section each including a plurality of slots corresponding to each other are set, and the transmission request signal section and transmission Transmitting and receiving a transmission request signal and a transmission acknowledgment signal with a terminal that wants to transmit data through the grant signal interval; And d) a data channel to which data is transmitted and received based on the transmission request signal and the transmission approval signal transmitted and received through the transmission request signal slot and the transmission approval signal slot corresponding to each other on the transmission request signal section and the transmission approval signal section; Transmitting and receiving data through the formed data channel Random access connection method between terminals including a. The method of claim 1, wherein c) A transmission request signal section for transmitting and receiving a transmission request signal; And And a transmission approval signal section for transmitting / receiving a predetermined transmission approval signal after the transmission request signal section ends. The method of claim 2, The transmission request signal interval is a random access connection method between terminals that is a time when a plurality of transmission request signal slots can be transmitted to transmit and receive a plurality of transmission request signals. The method of claim 2, The transmission approval signal interval is a random access connection method between the terminals is a time when a plurality of transmission approval signal slots can be transmitted to transmit and receive a plurality of transmission approval signal. The method according to claim 3 or 4, When the transmission request signal is received through the first transmission request signal slot among the plurality of transmission request signal slots, the terminal that transmitted the transmission request signal is transmitted to the first transmission request signal slot from the plurality of transmission approval signal slots. A random access connection method between terminals transmitting a transmission approval signal through a corresponding first transmission approval signal slot. The method of claim 5, And a priority of channel formation is determined based on the order of the transmission request signal slot and the transmission approval signal slot. The method of claim 1, In step d), And when the data channel is formed, a random access connection method between terminals, in which a data channel is not formed between two terminals connected through the data channel and other terminals in a communicable state. The method of claim 1, In step d), And a start point of the data channel is between a time point at which the transmission request signal section and a transmission approval signal section ends and a time point at which the channel sensing section based on the subsequent synchronization point ends. The method of claim 1, After step d), After the transmission and reception of data is finished, the terminal receiving the data further comprises the step of transmitting a data reception confirmation signal to the terminal that sent the data. The method of claim 9, And the data reception confirmation signal is present between the time point at which the data transmission is terminated and the time point at which a channel detection section of a subsequent sync point ends. In the random access terminal apparatus capable of transmitting and receiving data between a plurality of terminal apparatuses using a time division multiple access method, Receives a synchronization signal from a specific synchronization source existing outside, generates one or more synchronization points having a predetermined synchronization period based on the synchronization signal, and detects a channel signal during a predetermined channel sensing interval based on the synchronization point. And a synchronization unit generating an event signal allowing data transmission and reception when the channel signal is not detected; The first transmission request signal is transmitted based on the event signal, the first transmission approval signal corresponding to the first transmission request signal is received, and the second transmission request signal is generated based on the first transmission request signal and the first transmission approval signal. A data transmitter for transmitting data through the data channel; And Receiving a second transmission request signal from a terminal requesting connection based on the event signal, transmitting a second transmission approval signal corresponding to the second transmission request signal, and transmitting the second transmission request signal and the second transmission Data receiving unit for receiving data through the data channel generated based on the acknowledgment signal Random access terminal device comprising a. The method of claim 11, The synchronization unit, A synchronization signal receiver for receiving synchronization information on a reference time from a specific synchronization source existing outside; And A terminal for generating a synchronization point having a predetermined synchronization period based on the synchronization information, and detecting a channel signal during the SCSP based on the synchronization point and generating an event signal when the channel signal is not detected. Motivation Random access terminal device comprising a. The method of claim 11, The data transmission unit, A transmission request signal transmission unit for transmitting the first transmission request signal to a terminal to receive the event signal and to transmit data; A transmission acknowledgment signal receiver which receives the first transmission acknowledgment signal corresponding to the first transmission request signal; And Data transmission unit for transmitting data by forming a data channel based on the first transmission request signal and the first transmission approval signal Random access terminal device comprising a. The method of claim 11, The data receiver, A transmission request signal receiver which receives the second transmission request signal from a terminal to which data is to be transmitted; Transmission acknowledgment signal / data for transmitting the second transmission acknowledgment signal corresponding to the second transmission request signal and receiving data through a data channel generated based on the second transmission request signal and the second transmission acknowledgment signal. Receiver Random access terminal device comprising a. The method according to claim 13 or 14, The first transmission request signal and the second transmission request signal are transmitted and received during a predetermined transmission request signal period after the channel sensing section ends. The transmission request signal section comprises a plurality of transmission request signal slots for transmitting and receiving a plurality of transmission request signals. The method according to claim 13 or 14, The first transmission approval signal and the second transmission approval signal are transmitted and received during a predetermined transmission approval signal interval after the transmission request signal interval is finished, The transmission approval signal section is a random access terminal apparatus that is a time when a plurality of transmission approval signal slots can be transmitted to transmit and receive a plurality of transmission approval signals. The method of claim 11, When the data channel is formed, the random access terminal apparatus that the data channel is not formed between the two terminals connected through the data channel and the other terminals in the communication state. The method of claim 11, The random access terminal apparatus starts data transmission through the data channel before the end of the channel detection period based on a subsequent sync point. The method of claim 11, When data reception is completed in the data receiver, a data reception acknowledgment signal is transmitted to a terminal that has transmitted data, and when data transmission is terminated in the data transmitter, an acknowledgment signal transmission and reception that receives a data reception confirmation signal from a terminal that has received data. part Random access terminal device further comprising. The method of claim 19, And the data reception confirmation signal is transmitted between the time point at which the data transmission is terminated and the time point at which a channel detection section based on a subsequent synchronization point ends.

Images