KR102556726B1 - The Counteract Method for Collisions between Packets That Occur In A Communication System Using Unslotted Aloha Mechanism - Google Patents

Abstract

The present invention is a method for responding to a collision between communication packets generated in a communication system that communicates in an unslotted Aloha scheme, and more specifically, includes one AP and a plurality of devices, and includes an unslotted Aloha scheme. For collisions that occur when two or more devices transmit communication packets to the AP at the same time in a communication system performed by using one or more CRP channels, the collision between communication packets can be effectively dealt with. It's about how.

Description

The Counteract Method for Collisions between Packets That Occur In A Communication System Using Unslotted Aloha Mechanism

The present invention is a method for responding to a collision between communication packets generated in a communication system that communicates in an unslotted Aloha scheme, and more specifically, includes one AP and a plurality of devices, and includes an unslotted Aloha scheme. For collisions that occur when two or more devices transmit communication packets to the AP at the same time in a communication system performed by using one or more CRP channels, the collision between communication packets can be effectively dealt with. It's about how.

The Aloha Protocol was developed as a method for multiple users to jointly use the same channel. In the Alohan protocol, when the sending node transmits a packet, the receiving node checks whether the packet is a valid packet, sends a corresponding ACK, and the sending node waits until the ACK arrives. When the maximum round-trip propagation delay time is exceeded, the corresponding packet is retransmitted, and through this method, it corresponds to a method in which multiple nodes use the same channel. If several nodes send packets at the same time, collision between packets occurs. In this case, the receiving node does not receive the corresponding packets. That is, as the load increases, such as the number of channel nodes or the amount of communication increases, the number of collisions between packets increases, resulting in a decrease in the maximum channel utilization rate.

As a method to prevent such a collision, a method of setting an arbitrary backoff time or limiting the maximum number of retransmissions has been proposed. aloha) protocol has been proposed. In the slotted Aloha communication method, each node can transmit a packet only at the starting point of a slot, and each node is synchronized so that the starting point of the slot can be known. When two or more nodes collide in one slot, all nodes within the coverage They have the feature of detecting collisions. On the other hand, the slotted Aloha communication method also has a disadvantage that the more active nodes there are, the more collisions occur and slots are wasted. Since their clocks need to be synchronized, they must be synchronized periodically, and in the case of unsynchronized nodes, communication is difficult.

Thus, communication is performed in a simpler way without the need for synchronization, such as the unslotted aloha protocol, a completely decentralized protocol without slots, but isolating the device that wants to send the packet and the device that is potentially sending the packet from each other. Thus, there is a demand for a technology capable of preventing collisions and thereby increasing channel utilization.

The present invention is a method for responding to a collision between communication packets generated in a communication system that communicates in an unslotted Aloha scheme, and more specifically, includes one AP and a plurality of devices, and includes an unslotted Aloha scheme. For collisions that occur when two or more devices transmit communication packets to the AP at the same time in a communication system performed by using one or more CRP channels, the collision between communication packets can be effectively dealt with. It aims to provide a method.

In order to solve the above problems, an embodiment of the present invention is to respond to collisions between communication packets generated in a communication system that includes a plurality of devices and APs and communicates with an unslotted aloha method. A method comprising: a packet transmission step of generating a communication packet corresponding to an event in the device and transmitting the communication packet to the AP using a contention channel; In the AP, a contention collision detection step of performing decoding at a predetermined first cycle and detecting a collision between communication packets generated within the contention channel based on a decoding result; When the AP detects a collision between communication packets generated in the contention channel, after determining the communication state in the CRP channel, the AP instructs the device that transmitted the packet in which the collision occurred to change the communication channel from the contention channel to the CRP channel. a channel change command step of broadcasting a command on the contention channel; and a CRP retransmission step of, in the device, upon receiving the command, changing a communication channel of a communication packet transmitted to the AP from a contention channel to a CRP channel, and retransmitting the communication packet to the AP through the CRP channel. and, when the communication packet transmitted through the CRP channel is successfully transmitted to the AP, the device changes the communication channel of the device back to a contention channel.

In one embodiment of the present invention, the channel change command step, in the AP, a CRP collision detection step of determining whether there is a collision in the CRP channel; and if it is determined that a collision occurs in the CRP channel, the AP broadcasts a command to retransmit the communication packet through the contention channel to the device that transmitted the communication packet in which the collision occurred in the contention channel through the contention channel. A channel fixing command step of casting; and the device may perform a contention retransmission step of retransmitting the communication packet through the contention channel upon receiving the retransmission command.

In one embodiment of the present invention, the CRP collision detection step is performed because many devices change the communication channel to the CRP channel when the channel change command step is performed more than a preset number of times during a preset first period. It may be determined that a collision occurs within a channel.

In one embodiment of the present invention, the CRP collision detecting step, when there is no communication packet transmitted through the CRP channel for a predetermined second period, each device that has changed the communication channel to the CRP channel sends its own communication packet It can be determined that no collision occurs in the CRP channel by determining that all are successfully sent.

In one embodiment of the present invention, the CRP channel includes a first CRP channel, a second CRP channel, and a third CRP channel having different communication bands, respectively, and the channel change command step is performed in the AP in the contention channel. a first channel change command step of broadcasting a command to change a communication channel from the contention channel to a first CRP channel to a device having a collision when a collision between communication packets is detected; When the AP detects a collision between the communication packets generated in the contention channel and the first CRP channel, broadcasting a command to change the communication channel from the contention channel to the second CRP channel to the device in which the collision occurs channel change command step; and when the AP detects a collision between communication packets generated in the contention channel, the first CRP channel, and the second CRP channel, instructing the device in which the collision occurs to change the communication channel from the contention channel to the third CRP channel. A third channel change command step of broadcasting a command; may include.

In one embodiment of the present invention, the method for responding to the collision is performed by an AP that sequentially performs the first channel change command step, the second channel change command step, and the third channel change command step. When a collision between communication packets occurring in the contention channel is detected, a channel derivation step of deriving a channel with the least collision in the CRP channel during a period corresponding to a preset second cycle; In the channel change command step, a command to change the communication channel to the channel derived in the channel derivation step may be broadcast to the device that transmitted the communication packet in which the collision occurred.

According to an embodiment of the present invention, collisions between communication packets can be reduced by separating a device that currently wants to transmit a communication packet from a device that will potentially transmit a communication packet, and can exert an effect of improving communication efficiency in a communication system. can

According to an embodiment of the present invention, as the load increases, the number of collisions of communication packets increases, thereby preventing a corresponding channel usage rate from decreasing.

According to an embodiment of the present invention, by operating a plurality of CRP channels, even if the number of devices or the amount of communication increases in a communication system, it is possible to flexibly cope with this.

1 schematically illustrates a process of performing a method for responding to a collision according to an embodiment of the present invention.
2 schematically illustrates the configuration of a communication system communicating in an unslotted Aloha manner according to an embodiment of the present invention.
3 schematically illustrates a contention channel through which communication packets transmitted from a plurality of devices according to an embodiment of the present invention are transmitted.
4 schematically illustrates the steps of performing a method for responding to a collision when a collision occurs according to an embodiment of the present invention.
5 schematically illustrates a process of performing a channel fix command step according to an embodiment of the present invention.
Figure 6 schematically shows the performance steps of the CRP collision detection step according to an embodiment of the present invention.
7 schematically illustrates a process of performing a channel change command step performed for a plurality of CRP channels according to an embodiment of the present invention.
8 schematically illustrates a process of performing a channel derivation step according to an embodiment of the present invention.
9 schematically illustrates the internal configuration of a computing device according to an embodiment of the present invention.

In the following, various embodiments and/or aspects are disclosed with reference now to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to facilitate a general understanding of one or more aspects. However, it will also be appreciated by those skilled in the art that such aspect(s) may be practiced without these specific details. The following description and accompanying drawings describe in detail certain illustrative aspects of one or more aspects. However, these aspects are exemplary and some of the various methods in principle of the various aspects may be used, and the described descriptions are intended to include all such aspects and their equivalents.

In addition, terms including ordinal numbers, such as first and second, may be used to describe various components, but the components are not limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The terms and/or include any combination of a plurality of related recited items or any of a plurality of related recited items.

In addition, in the embodiments of the present invention, unless otherwise defined, all terms used herein, including technical or scientific terms, are generally understood by those of ordinary skill in the art to which the present invention belongs. has the same meaning as Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the embodiments of the present invention, an ideal or excessively formal meaning not be interpreted as

A “device” referred to below may be implemented as a computer or portable terminal capable of accessing a server or other terminals through a network. Here, the computer includes, for example, a laptop, desktop, laptop, etc. equipped with a web browser, and the portable terminal is, for example, a wireless communication device that ensures portability and mobility. , Smartphone, PCS(Personal Communication System), GSM(Global System for Mobile communications), PDC(Personal Digital Cellular), PHS(Personal Handyphone System), PDA(Personal Digital Assistant), IMT(International Mobile Telecommunication)-2000, All types of handheld-based wireless communication devices such as Code Division Multiple Access (CDMA)-2000, W-Code Division Multiple Access (W-CDMA), and Wireless Broadband Internet (Wibro) terminals may be included. Also, "network" means a wired network such as a Local Area Network (LAN), a Wide Area Network (WAN), or a Value Added Network (VAN), or a LoRa network (Long Range). It can be implemented in all kinds of wireless networks, such as a mobile radio communication network or a satellite communication network.

1 schematically illustrates a process of performing a method for responding to a collision according to an embodiment of the present invention, and FIG. 2 illustrates a configuration of a communication system communicating in an unslotted Aloha method according to an embodiment of the present invention. show schematically.

1 and 2, corresponding to collisions between communication packets generated in a communication system including a plurality of devices 2000 and AP 1000 and communicating in an unslotted aloha scheme. As a method, a packet transmission step (S100) of generating a communication packet corresponding to the generated event in the device 2000 and transmitting the communication packet to the AP 1000 using a contention channel; In the AP (1000), a contention collision detection step (S200) of performing decoding at a predetermined first cycle and detecting a collision between communication packets generated within the contention channel based on a decoding result; When the AP 1000 detects a collision between communication packets generated in the contention channel, after determining the communication state in the CRP channel, the communication channel is transferred to the device 2000 that transmitted the packet in which the collision occurred. a channel change command step (S300) of broadcasting a command to change to a CRP channel in the contention channel; And when the device 2000 receives the command, the communication channel of the communication packet transmitted to the AP 1000 is changed from a contention channel to a CRP channel, and the communication packet is transmitted through the CRP channel to the AP 1000. ), and a CRP retransmission step (S400) of retransmitting the device 2000, when the communication packet transmitted through the CRP channel is successfully transmitted to the AP 1000, the device 2000 Change the communication channel back to the contention channel.

Specifically, the communication system in which the method for responding to collision of the present invention is performed includes, with reference to FIG. 2, one AP 1000 and a plurality of devices 2000 located within the coverage of the AP 1000. . According to an embodiment of the present invention, the communication system may include a plurality of APs 1000, and each AP 1000 includes a plurality of devices 2000 as shown in FIG. Each of the plurality of devices 2000 corresponds to an active device 2000 in a wake up state or a sleeping device 2000 in a sleep state. The active device 2000 is in a state in which it can receive packets transmitted from the AP 1000 included in the coverage where it is located, and the sleeping device 2000 can receive packets transmitted from the AP 1000 is in a state of no

The device 2000 can be operated by switching between an active mode and a sleeping mode in one device, and the device 2000 described below is capable of communicating with the AP 1000 unless otherwise specified. It is assumed that the active device 2000 is described.

Also, the communication system shown in FIG. 2 performs communication according to an unslotted aloha mechanism. Unlike slotted Aloha communication, which time-divides a communication channel into slots of the same size, unslotted Aloha communication does not require a synchronization process and the device 2000 transmits a communication packet without a separate delay if only a collision does not occur. It has the advantage of being able to transmit to the AP (1000). Referring to FIG. 3, the collision occurs when different communication packets are transmitted on the same channel at the same time. On the other hand, the unslotted Aloha communication has a problem in that the probability of collision is higher than that of the slotted Aloha communication. Hereinafter, a method for reducing the probability of collision in the unslotted Aloha method and responding to the collision when a collision occurs will be described. do.

1 shows a schematic process of a method corresponding to a collision performed between an AP 1000 and a device 2000 described above, in which the device 2000 generates a communication packet and controls the communication packet. A packet transmission step (S100) to be sent to the AP 1000 using a contention channel is performed. According to an embodiment of the present invention, the device 2000 operates in a sleeping mode and when an event occurs, wakes up and converts to an active mode to generate a communication packet. According to another embodiment of the present invention, After the device 2000 operates in the sleeping mode and switches to the active mode, an event may occur to generate a communication packet.

Meanwhile, the AP 1000 performs decoding for each predetermined first period, independently of the operation of the device 2000 described above, and determines whether the contention channel collides with each other based on the corresponding decoding result. The contention collision detection step (S200) is performed. More specifically, the AP 1000 performs decoding for every first period. Successful decoding means that the AP 1000 successfully receives the communication packet transmitted by the device 2000. And, if decoding is not successfully performed, it means that the AP 1000 cannot successfully receive the communication packet. Through this, the AP 1000 determines that a collision has occurred in the contention channel. If the AP 1000 determines that a collision has occurred in the contention channel by performing the contention collision detection step S200, the AP 1000 performs a channel change command step S300 as follows. do.

When the AP 1000 detects a collision between communication packets generated in the contention channel, the device that transmits the packet in which the collision occurs after determining the communication state in the CRP channel (Collision Resolution Process Channel, hereinafter CRP channel) A channel change command step (S300) of broadcasting a command to change the communication channel from the contention channel to the CRP channel to (2000) is performed. In other words, when decoding fails, the AP 1000 broadcasts a packet including information indicating that decoding has failed on the contention channel. At this time, the broadcast packet includes a command to change the communication channel of the device 2000 receiving the packet from a contention channel to a CRP channel.

Meanwhile, as described above, the sleeping device 2000 operating in the sleeping mode when the AP 1000 broadcasts cannot receive a packet broadcast by the AP 1000 . That is, two or more devices 2000 operating in the active mode within the preset first period and transmitting communication packets within the period can receive the packet broadcast by the AP 1000 and transmit the corresponding packet. The receiving device 2000 performs the CRP retransmission step (S400) as follows.

The device 2000 receiving the packet broadcast by the AP 1000 changes the communication channel of the communication packet transmitted to the AP 1000 to a CRP channel, and transmits the packet through the CRP channel ( A CRP retransmission step (S400) of retransmitting the communication packet sent in step S100 to the AP 1000 is performed. The CRP channel corresponds to a channel having a different communication band from the contention channel, and is used by the AP to effectively respond to a collision occurring in a communication channel. As an embodiment of the present invention, the corresponding communication system can increase the communication efficiency of the entire communication system and reduce the load of the contention channel by operating the CRP channel together with the contention channel.

After a predetermined time has elapsed, the device 2000 that has changed the communication channel to the CRP channel transmits the communication packet transmitted in the packet transmission step (S100) to the AP 1000 again, preferably for each device 2000. The predetermined time may be set differently. Meanwhile, the CRP channel may include one or more channels, and the device 2000 whose communication channel has been changed to the CRP channel transmits the communication packet to the AP 1000 so that the AP 1000 successfully transmits the corresponding communication packet. In case of reception, the communication channel of the device 2000 is changed back to the contention channel. Hereinafter, each step described above will be described in more detail.

3 schematically illustrates a contention channel through which communication packets transmitted from a plurality of devices 2000 according to an embodiment of the present invention are transmitted.

Specifically, FIG. 3 illustrates a process in which a plurality of devices 2000 perform communication using only the contention channel. The hatched rectangle shown in FIG. 3 means a communication packet transmitted from the device 2000 to the AP 1000, and the letters assigned to the communication packet are written to distinguish the device 2000 that transmitted the communication packet. . For example, communication packet a corresponds to a communication packet transmitted from device A (2000A), and communication packet b corresponds to a communication packet transmitted from device B (2000B). Actually, in the present invention, it is preferable to distinguish the transmitting device 2000 through an identification number included in a communication packet.

As shown in FIG. 3, the AP 1000 performs the contention collision detection step (S200) by performing decoding for each predetermined first period. In the first cycle shown in FIG. 3, since only the communication packet a was transmitted by device A (2000A), the AP 1000 can successfully perform decoding, and based on the result, the AP 1000 performs the corresponding cycle During this period, it is determined that no collision has occurred in the contention channel.

Meanwhile, in the next cycle, communication packets b, c, and d are transmitted by devices B, C, and D (2000B, 2000C, and 2000D) within the corresponding cycle, and as a result, collision between the communication packets b, c, and d occurs. . As shown in FIG. 3, even if the communication packets b, c, and d are not transmitted exactly at the same time, it is determined that a collision occurs when they are transmitted together within a preset first period. As such, when collisions between communication packets occur in a corresponding period, the AP 1000 fails to decode and cannot normally receive the communication packets b, c, and d, and based on the result, the AP 1000 determines that a collision has occurred in the contention channel.

Then, in the next cycle, since only the communication packet e is transmitted to the AP 1000 by the device E 2000E in that cycle, the AP 1000 succeeds in decoding and can normally receive the communication packet e, In the corresponding period, it is determined that no collision has occurred in the contention channel.

As described above, the AP 1000 repeatedly performs a process of determining whether a collision occurs within a corresponding decoding period according to a decoding period. On the other hand, referring to the first period and the third period as shown in FIG. 3, regardless of when the communication packet is transmitted within the period, in the case of the communication packet transmitted within the period, the AP 1000 operates normally. can receive In addition, the idle period shown in FIG. 3 corresponds to a period in which no communication packets are transmitted. As the idle period decreases, the amount of channel usage increases, but communication efficiency may decrease due to inability to flexibly respond to collisions.

4 schematically illustrates the steps of performing a method for responding to a collision when a collision occurs according to an embodiment of the present invention.

Specifically, FIG. 4 illustrates steps performed when a collision occurs with reference to the second cycle shown in FIG. 3 . More specifically, when the device 2000 operating in the sleeping mode wakes up (S110) and an event occurs (S120), a communication packet corresponding to the event is generated, and the generated communication packet is transmitted through a contention channel. is transmitted to the AP 1000 (S130). At this time, if a device other than the device 2000 also transmits a communication packet at that time, a collision occurs in the contention channel, and the AP 1000 receives the communication packet transmitted by the device 2000. Failure to do so will cause decoding to fail.

Since decoding is not successfully performed, the AP 1000 determines that a collision has occurred with the contention channel (S200). Thereafter, a packet including information to change the communication channel of the device 2000 from the contention channel to the CRP channel is broadcast (S300). The device 2000 operating in the active mode receives the broadcasting, changes the communication channel to the CRP channel (S410), and transmits the communication packet transmitted in step S130 to the AP 1000 through the changed communication channel. can be retransmitted (S420), and since the device 2000 operating in the sleeping mode cannot receive the broadcasting, the communication channel of the sleeping device 2000 is not changed to the CRP channel.

5 schematically illustrates a process of performing a channel fix command step (S320) according to an embodiment of the present invention.

As shown in FIG. 5, the channel change command step (S300) includes a CRP collision detection step (S310) of determining whether or not there is a collision in the CRP channel in the AP (1000); and if it is confirmed that a collision occurs in the CRP channel, the AP 1000 issues a command to retransmit the communication packet through the contention channel to the device 2000 that transmitted the communication packet in which the collision occurred in the contention channel. and a channel fixing command step (S320) of broadcasting on the contention channel, wherein the device 2000 retransmits the communication packet through the contention channel when the device 2000 receives the command to retransmit. ;

Schematically, FIG. 5 shows that when a collision occurs in the contention channel and a channel change command is performed by the AP 1000 in T1, and then a collision occurs again in the contention channel, the AP 1000 transmits a channel change command in T2. A process in which the fixed command step (S320) is performed is shown.

Specifically, in the first cycle shown in FIG. 5, communication packets a, b, and c are simultaneously transmitted through the contention channel to cause a collision. A command to change the communication channel to the CRP channel is broadcast to the devices A, B, and C (2000A, 2000B, 2000C) that have transmitted c, on the contention channel (S300). After T1 when the channel change command is broadcast, the devices 2000 A, B, and C (2000A, 2000B, 2000C) perform a CRP retransmission step (S400) of transmitting their own communication packets through the CRP channel.

After T1, the communication packet d is transmitted by the device D (2000D) in the contention channel. Since the device D (2000D) was operating in the sleeping mode at the time of T1, it did not receive the channel change command, and since it was switched to the active mode after T1, the device D (2000D) received the communication packet through the contention channel set as its own communication channel. d is transmitted to the AP 1000. Since no collision occurs in the second first period shown in FIG. 5 , the AP 1000 can successfully receive the communication packet d.

Meanwhile, in the third first cycle shown in FIG. 5, collisions between communication packets e and f transmitted by devices E and F (2000E and 2000F) occur in the contention channel. In a general situation, like the AP 1000 in T1, the AP 1000 transmits a channel change command to the devices E and F (2000E, 2000F), but the AP 1000 performs the CRP collision detection step in T2. By performing (S310), it is possible to detect that a collision has occurred in the CRP channel.

If the AP 1000 determines that a collision has occurred in the CRP channel, then the AP 1000 sends a packet containing a command to retransmit the communication packet to the devices E and F (2000E, 2000F) on the contention channel. is broadcast on the contention channel. At this time, devices E and F (2000E, 2000F) operating in an active mode with a contention channel as the communication channel can receive the broadcasted packet, and devices A and B with the CRP channel as the communication channel. , C (2000A, 2000B, 2000C) cannot receive the broadcast packet. Upon receiving the channel fix command, each of the devices E and F (2000E, 2000F) transmits communication packets e and f again through the contention channel after a predetermined time. A more detailed description of the CRP collision detection step (S310) will be described later.

On the other hand, as described above, the AP 1000 does not transmit a command by pointing to a specific device 2000, but broadcasts a channel change command or a channel fix command, but sets the broadcast channel as a communication channel. However, by configuring so that only the device 2000 operating in the active mode can receive, computing resources in the AP 1000 can be reduced. In addition, the communication channel of the device 2000 that transmitted the communication packet in which the collision occurred is By changing to the CRP channel, it is possible to exert an effect of separating the device 2000 to send a communication packet from the device 2000 to potentially transmit a communication packet, and as a result, collision between communication packets can be reduced. It is possible to exert an effect of improving communication efficiency in the communication system.

6 schematically illustrates the steps of performing the CRP collision detection step (S310) according to an embodiment of the present invention.

As shown in FIG. 6, the CRP collision detection step (S310) changes the communication channel to the CRP channel when the channel change command step (S300) is performed more than a predetermined number of times during a first predetermined period. Since there are many devices 2000, it can be determined that a collision occurs in the CRP channel, or in the CRP collision detection step (S310), when there is no communication packet transmitted through the CRP channel for a predetermined second period. , It is determined that each of the devices 2000 that changed the communication channel to the CRP channel has successfully sent all of their respective communication packets, and it is determined that no collision occurs within the CRP channel.

Specifically, the AP 1000 may determine whether a collision between communication packets has occurred in the contention channel through the contention collision detection step (S200). As an embodiment of the present invention, the AP 1000 that detects a collision in the contention channel due to decoding failure, as shown in FIG. 6, in the CRP channel through two steps (S311 to S312) described later You can check the communication status of The steps S311 and S312 are included in the CRP collision detection step (S310).

First, the AP 1000 counts (S311) whether the channel change command step (S300) has been performed more than a predetermined number of times during a first predetermined period. Preferably, the first period corresponds to a time during which the first cycle can be performed several times. More specifically, the AP 1000 may perform the contention collision detection step (S200) and the channel change command step (S300) for each of the first cycles, and as a result, the contention collision detection for the predetermined time period. Step (S200) and channel change command step (S300) may be repeatedly performed. In this way, when the channel change command step (S300) is repeatedly performed, if the channel change command step (S300) is performed more than a predetermined number of times, the AP (1000) changes the communication channel to the CRP channel (2000). ), it can be determined that a collision may occur in the CRP channel.

As such, when the AP 1000 determines that a collision may occur in the CRP channel, the AP 1000 sends a channel change command step ( It is possible to prevent an additional collision from occurring in the CRP channel by performing the channel fixing command step (S320) without performing S300). If, as a result of performing the step S311, if the channel change command step (S300) is performed less than a predetermined number of times by the AP 1000 during the first period, the AP 1000 has a collision within the period. For the device 2000 that transmitted the generated communication packet, a channel change command step (S300) is performed.

Second, the AP 1000 determines the communication state in the CRP channel by determining whether there is a communication packet transmitted through the CRP channel for a predetermined second period (S312). More specifically, when a collision also occurs in the CRP channel, the devices 2000 that have transmitted the communication packet in which the collision occurred retransmit the corresponding communication packet after a certain period of time. In this way, the devices 2000 using the CRP channel as a communication channel can solve the collision in the CRP channel by adjusting the transmission timing on their own.

That is, when there is a device 2000 transmitting on the CRP channel, the AP 1000 can continuously receive communication packets through the CRP channel, and when the collision in the CRP channel is resolved, The AP 1000 cannot receive any more communication packets through the CRP channel. Accordingly, when the AP 1000 does not receive a communication packet during the second period, it may be determined that there is no device 2000 transmitting a communication packet through the CRP channel, and a communication in which a collision occurs in the contention channel A channel change command step (S300) of broadcasting a channel change command to the device 2000 that has transmitted the packet is performed.

If the AP 1000 receives a communication packet through the CRP channel during the second period, when the AP 1000 performs a channel change, the number of devices 2000 using the CRP channel as the communication channel increases. Therefore, it is determined that the load of the CRP channel will increase, and a channel fixation command step (S320) of broadcasting a channel fixation command to devices 2000 that have transmitted communication packets in which collisions occur in the contention channel is performed.

As described above, the CRP collision detection step (S310) can determine the communication state of the CRP channel through two methods. According to an embodiment of the present invention, it is preferable that the AP 1000 perform both steps S311 and S312 to determine the communication state of the CRP channel. According to another embodiment of the present invention, the step S311 Alternatively, the communication state of the CRP channel may be grasped using only one of step S312.

7 schematically illustrates a process of performing a channel change command step (S300) performed for a plurality of CRP channels according to an embodiment of the present invention.

As shown in FIG. 7, the CRP channel includes a first CRP channel, a second CRP channel, and a third CRP channel having different communication bands, and the channel change command step (S300), in the AP 1000, When a collision between communication packets occurring within the contention channel is detected, a first channel change command step of broadcasting a command to change the communication channel from the contention channel to the first CRP channel to the device 2000 in which the collision occurred ( S330); When the AP 1000 detects a collision between communication packets generated in the contention channel and the first CRP channel, a command to change the communication channel from the contention channel to the second CRP channel to the device 2000 in which the collision occurs a second channel change command step of broadcasting (S340); And when the AP 1000 detects a collision between communication packets generated in the contention channel, the first CRP channel, and the second CRP channel, the communication channel is assigned to the device 2000 in which the collision occurred in the contention channel. and a third channel change command step (S350) of broadcasting a command to change to a third CRP channel.

Specifically, FIG. 7, as an embodiment of the present invention, shows a process in which a method for responding to a collision of the present invention is performed when there are three CRP channels. Meanwhile, in the following description, the number of CRP channels is assumed to be 3 for convenience of description, but in the actual invention, the present invention is not limited thereto, and the manager or designer may set the number of CRP channels in consideration of the communication environment of the corresponding communication system. can be set

As shown in FIG. 7, when a collision between communication packets a, b, and c occurs in the first period of the contention channel, the AP 1000 performs the contention collision detection step (S200) in T1, Thereafter, devices A, B, and C (2000A, 2000B, and 2000C) that have transmitted the communication packets a, b, and c during the corresponding period send a command to change the communication channel from the contention channel to the first CRP channel to the contention channel. The broadcasting first channel change command step (S330) is performed. Upon receiving the broadcasting, the devices A, B, and C (2000A, 2000B, and 2000C) change the communication channel to the first CRP channel and transmit the communication packets a, b, and c to the AP 1000 through the first CRP channel. ) is resent.

On the other hand, as shown in the first CRP channel of FIG. 7, a collision may also occur in the first CRP channel based on T2, and at the same time, between communication packets d, e, and f in the second first cycle of the contention channel. A collision may occur. That is, in T2, the AP 1000 may detect a collision between the contention channel and the first CRP channel by performing the contention collision detection step (S200) and the first CRP collision detection step (S310), and responding thereto In order to do so, the devices D, E, and F (2000D, 2000E, 2000F) that transmitted the communication packets d, e, and f during the corresponding period (the second and first periods in FIG. 7) change the communication channel from the contention channel to the second CRP channel. A second channel change command step (S340) of broadcasting a change command to the contention channel is performed. The devices D, E, and F (2000D, 2000E, 2000F) receiving the broadcasting change the communication channel to the second CRP channel, and transmit the communication packets d, e, and f to the AP using the second CRP channel. Retransmit to (1000).

On the other hand, as shown in the 2nd CRP channel of FIG. 7, collisions may also occur in the 1st CRP channel and the 2nd CRP channel based on T3, and at the same time, in the first cycle of the contention channel, communication packets g, A collision between h and i may occur. At T3, the AP 1000 performs the contention collision detection step (S200), the first CRP collision detection step (S310), and the second CRP collision detection step (S310) to determine the contention channel, the first CRP channel, and the A collision can be detected in the second CRP channel, and then the devices G, H, I (2000G, 2000H, 2000I) that transmitted the communication packets g, h, and i during the corresponding period (the third and first period in FIG. 7) cause A third channel change command step (S350) of broadcasting a command to change the communication channel from the contention channel to the third CRP channel is performed on the contention channel. The devices G, H, and I (2000G, 2000H, and 2000I) receiving the broadcasting change the communication channel to the 3rd CRP channel, and transmit the communication packets g, h, and i to the AP using the 3rd CRP channel. Retransmit to (1000).

As described above, the AP (1000) can reduce the load of each channel and maximize the channel utilization rate by utilizing the contention channel and a plurality of channels, and collisions between communication packets increased by the plurality of devices (2000). can exert the effect of being able to respond flexibly to In addition, by operating a plurality of CRP channels, even if the number of devices 2000 in the communication system increases or communication usage increases, an effect of flexibly coping with this can be exerted. Additionally, in the case of the contention channel, the AP (1000) has little authority to control, so when only the contention channel was operated, it was difficult for the AP (1000) to control collisions occurring in the contention channel. Since the devices 2000 that change the communication channel to the CRP channel through the command generated by the AP 1000 can be controlled to some extent through the AP 1000, the biggest problem of the conventional unslotted Aloha communication method is It can exert an effect that can partially solve the collision problem.

8 schematically illustrates the process of deriving a channel (S600) according to an embodiment of the present invention.

As shown in FIG. 8, the method for responding to the collision includes the first channel change command step (S330), the second channel change command step (S340), and the third channel change command step (S350). When a collision between communication packets generated in the contention channel, which is performed by the sequentially performing AP 1000, is detected, the channel with the least collision among the CRP channels during the period corresponding to the preset second cycle is selected. Deriving a channel derivation step (S600); further comprising, the channel change command step (S300), the communication channel to the device 2000 that transmitted the communication packet in which the collision occurred, the derived in the channel derivation step (S600) Broadcasts a command to change to a channel.

Specifically, as shown in (a) of FIG. 8, the AP 1000 performs the first channel change command step (S330), the second channel change command step (S340), and the The third channel change command step (S350) is sequentially performed. In other words, when a collision occurs on the contention channel, the AP 1000 first sends a command to change the communication channel to the first CRP channel to the devices 2000 that transmit the communication packets in which the collision occurred. broadcast to the contention channel, then broadcast a command to change the communication channel to the second CRP channel to the contention channel, and then broadcast a command to change the communication channel to the third CRP channel to the contention channel; Thereafter, a command to change the communication channel to the first CRP channel is broadcast to the contention channel. When such a circular process is performed for a period corresponding to the second period, the AP 1000 performs a channel derivation step (S600) of deriving a channel with the least collision among the first to third CRP channels.

In the channel derivation step (S600), as shown in (b) of FIG. 8, after deriving the number of collisions occurring during the second period in each CRP channel, a channel with the least collision among them is deduced. Subsequently, when a collision occurs in the contention channel, the AP 1000 broadcasts a command to change the communication channel to the channel with the least collision derived in the channel derivation step (S600) to the contention channel, and then , a command to change the communication channel to the channel with the next least collision is broadcast to the contention channel. According to an embodiment of the present invention shown in (b) of FIG. 8, the AP 1000 broadcasts a command to change a communication channel to the second CRP channel. Preferably, the channel derivation step (S600) is performed every second cycle.

9 schematically illustrates the internal configuration of a computing device according to an embodiment of the present invention.

All or part of the AP and device shown in FIG. 1 may include components of a computing device shown in FIG. 9 described later.

As shown in FIG. 9, a computing device 11000 includes at least one processor 11100, a memory 11200, a peripheral interface 11300, an input/output subsystem ( It may include at least an I/O subsystem (11400), a power circuit (11500), and a communication circuit (11600).

Specifically, the memory 11200 is, for example, a high-speed random access memory (high-speed random access memory), a magnetic disk, SRAM (SRAM), DRAM (DRAM), ROM (ROM), flash memory or non-volatile memory can include The memory 11200 may include a software module, a command set, or other various data necessary for the operation of the computing device 11000.

In this case, access to the memory 11200 from other components, such as the processor 11100 or the peripheral device interface 11300, may be controlled by the processor 11100. The processor 11100 may be composed of single or multiple processors, and may include GPU and TPU type processors in order to improve calculation processing speed.

The peripheral interface 11300 may couple input and/or output peripherals of the computing device 11000 to the processor 11100 and the memory 11200 . The processor 11100 may execute a software module or instruction set stored in the memory 11200 to perform various functions for the computing device 11000 and process data.

The input/output subsystem 11400 can couple various input/output peripherals to the peripheral interface 11300. For example, the input/output subsystem 11400 may include a controller for coupling a peripheral device such as a monitor, keyboard, mouse, printer, or touch screen or sensor to the peripheral device interface 11300 as needed. there is. According to another aspect, the peripheral input/output devices may be coupled to the peripheral device interface 11300 without going through the input/output subsystem 11400.

The power circuit 11500 may supply power to all or some of the terminal's components. For example, the power circuit 11500 may include a power management system, one or more power sources such as a battery or alternating current (AC), a charging system, a power failure detection circuit, a power converter or inverter, a power status indicator, or It may include any other components for power generation, management and distribution.

The communication circuit 11600 may enable communication with another computing device using at least one external port. Alternatively, as described above, the communication circuit 11600 may include an RF circuit and transmit/receive an RF signal, also known as an electromagnetic signal, to enable communication with another computing device.

The embodiment of FIG. 9 is only an example of the computing device 11000, and the computing device 11000 may omit some components shown in FIG. 9 or may further include additional components not shown in FIG. , may have a configuration or arrangement that combines two or more components. For example, a computing device for a communication terminal in a mobile environment may further include a touch screen or a sensor in addition to the components shown in FIG. 9 , and the communication circuit 1160 may include various communication methods (Wi-Fi, A circuit for RF communication of 3G, LTE, Bluetooth, NFC, Zigbee, etc.) may be included. Components that may be included in the computing device 11000 may be implemented as hardware including one or more signal processing or application-specific integrated circuits, software, or a combination of both hardware and software.

Methods according to embodiments of the present invention may be implemented in the form of program instructions that can be executed through various computing devices and recorded in computer readable media. In particular, the program according to the present embodiment may be composed of a PC-based program or a mobile terminal-specific application. An application to which the present invention is applied may be installed in a user terminal through a file provided by a file distribution system. For example, the file distribution system may include a file transmission unit (not shown) that transmits the file according to a request of a user terminal.

The device described above may be implemented as a hardware component, a software component, and/or a combination of hardware components and software components. For example, devices and components described in the embodiments may include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA) , a programmable logic unit (PLU), microprocessor, or any other device capable of executing and responding to instructions. The processing device may run an operating system (OS) and one or more software applications running on the operating system. A processing device may also access, store, manipulate, process, and generate data in response to execution of software. For convenience of understanding, there are cases in which one processing device is used, but those skilled in the art will understand that the processing device includes a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that it can include. For example, a processing device may include a plurality of processors or a processor and a controller. Other processing configurations are also possible, such as parallel processors.

Software may include a computer program, code, instructions, or a combination of one or more of the foregoing, which configures a processing device to operate as desired or processes independently or collectively. You can command the device. Software and/or data may be any tangible machine, component, physical device, virtual equipment, computer storage medium or device, intended to be interpreted by or to provide instructions or data to a processing device. , or may be permanently or temporarily embodied in a transmitted signal wave. Software may be standardized on a networked computing device and stored or executed in a standardized manner. Software and data may be stored on one or more computer readable media.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program commands recorded on the medium may be specially designed and configured for the embodiment or may be known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. - includes hardware devices specially configured to store and execute program instructions, such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language codes that can be executed by a computer using an interpreter, as well as machine language codes such as those produced by a compiler. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

According to an embodiment of the present invention, collisions between communication packets can be reduced by separating a device that currently wants to transmit a communication packet from a device that will potentially transmit a communication packet, and can exert an effect of improving communication efficiency in a communication system. can

According to an embodiment of the present invention, as the load increases, the number of collisions of communication packets increases, thereby preventing a corresponding channel usage rate from decreasing.

According to an embodiment of the present invention, by operating a plurality of CRP channels, even if the number of devices or the amount of communication increases in a communication system, it is possible to flexibly cope with this.

As described above, although the embodiments have been described with limited examples and drawings, those skilled in the art can make various modifications and variations from the above description. For example, the described techniques may be performed in an order different from the method described, and/or components of the described system, structure, device, circuit, etc. may be combined or combined in a different form than the method described, or other components may be used. Or even if it is replaced or substituted by equivalents, appropriate results can be achieved. Therefore, other implementations, other embodiments, and equivalents of the claims are within the scope of the following claims.

Claims (6)

As a method for responding to collisions between communication packets generated in a communication system that includes a plurality of devices and APs and communicates in an unslotted aloha manner,
a packet transmission step of generating a communication packet corresponding to an event in the device and transmitting the communication packet to the AP using a contention channel;
In the AP, a contention collision detection step of performing decoding at a predetermined first cycle and detecting a collision between communication packets generated within the contention channel based on a decoding result;
When the AP detects a collision between communication packets generated in the contention channel, after determining the communication state in the CRP channel, the AP instructs the device that transmitted the packet in which the collision occurred to change the communication channel from the contention channel to the CRP channel. a channel change command step of broadcasting a command on the contention channel; and
In the device, upon receiving the command, a CRP retransmission step of changing a communication channel of a communication packet transmitted to the AP from a contention channel to a CRP channel and retransmitting the communication packet to the AP through the CRP channel; do,
The device, when the communication packet transmitted through the CRP channel is successfully transmitted to the AP, changes the communication channel of the device back to a contention channel,
The channel change command step,
CRP collision detection step of determining, at the AP, whether there is a collision in the CRP channel; and
In the AP, if it is confirmed that a collision occurs in the CRP channel, a command to retransmit the communication packet in the contention channel is broadcasted on the contention channel to the device that transmitted the communication packet in which the collision occurred in the contention channel. Including; a channel fixing command step to do;
The device performs a contention retransmission step of retransmitting the communication packet through the contention channel when receiving the retransmission command;
The CRP collision detection step,
When the channel change command step is performed more than a predetermined number of times during a first predetermined period, it is determined that a collision occurs in the CRP channel because there are many devices that have changed the communication channel to the CRP channel. .
delete delete The method of claim 1,
The CRP collision detection step,
If there is no communication packet transmitted through the CRP channel during the second preset period, each device that has changed the communication channel to the CRP channel determines that each device has successfully sent all of its communication packets, and a collision occurs within the CRP channel. How to respond to a conflict, judged not to.
The method of claim 1,
The CRP channel includes a first CRP channel, a second CRP channel, and a third CRP channel having different communication bands, respectively;
The channel change command step,
A first channel change command step of broadcasting, in the AP, a command to change the communication channel from the contention channel to the first CRP channel to the device in which the collision occurred, when a collision between communication packets generated within the contention channel is detected. ;
When the AP detects a collision between the communication packets generated in the contention channel and the first CRP channel, broadcasting a command to change the communication channel from the contention channel to the second CRP channel to the device in which the collision occurs channel change command step; and
When the AP detects a collision between communication packets generated in the contention channel, the first CRP channel, and the second CRP channel, a command to change the communication channel from the contention channel to the third CRP channel to the device in which the collision occurs A third channel change command step of broadcasting; including, a method for responding to collisions.
The method of claim 5,
How to respond to the collision,
Performed by the AP that sequentially performed the first channel change command step, the second channel change command step, and the third channel change command step,
When a collision between communication packets occurring within the contention channel is detected, a channel derivation step of deriving a channel with the least collision in the CRP channel during a period corresponding to a preset second cycle; further comprising,
The channel change command step,
A method for responding to a collision comprising broadcasting a command to change a communication channel to a channel derived in the channel derivation step to a device that has transmitted a communication packet in which a collision occurs.

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