JP5420599B2 - Wireless communication system and wireless communication method - Google Patents

Description

  The present invention relates to a wireless communication system in which a transmission source wireless station transmits and receives a wireless packet to and from a destination wireless station, and the distance between the transmission source wireless station and the destination wireless station is long or out of sight. The present invention relates to a wireless communication system and a wireless communication method for performing stable wireless communication even in an environment including a case where direct wireless communication is difficult.

  In particular, when direct communication between the source radio station and the destination radio station becomes difficult, when a plurality of radio stations located around the source radio station and the destination radio station have successfully received radio packets. In addition, the present invention relates to a relay transmission technique for these radio stations to perform multi-hop relay cooperatively.

  In recent years, the spread of wireless communication has been remarkable. From mobile communications such as mobile phones, provision of spot wireless LAN services in quasi-stationary environments, provision of FWA (Fixed Wireless Access) services that provide wireless lines to homes as an alternative to wired lines such as optical fibers, etc. Services utilizing the advantages of wireless communication are being developed in various forms. At this time, from a business standpoint, it is desirable to cover a wide area with a small number of base station facilities and accommodate more user terminals. However, in general, the area area that can be covered by a single base station varies depending on conditions specific to the system (for example, frequency, transmission output, antenna gain, antenna installation location, modulation method, etc.) and propagation environment. For example, when a high-power transmission amplifier is provided as a function on the transmission side of a radio station, a wider area can be set as a service area. In general, a lower frequency is transmitted farther away.

  However, using a high-function, high-power transmission amplifier with high linearity will increase the price of the equipment, and there is also an upper limit on the transmission output according to regulations such as the Radio Law, so a transmission amplifier with too much power will be used. It is not desirable to expand the service area by using it. On the other hand, low frequency microwave bands are being used in many systems as easy-to-use frequency bands, so the frequency resources are already being depleted and it is expected that licenses will be allocated to new systems. Can not.

  As a result, when providing a service to a wide service area using a relatively high frequency band, the service area area obtained from the circuit design is often not sufficient from the viewpoint of business profitability. As a countermeasure in this case, it is conceivable to construct a wireless multi-hop network using many wireless stations in the area and perform relay transmission. As an example of such a multi-hop network, for example, a meshwork in a wireless LAN standard called IEEE802.11s is famous (see Non-Patent Document 1). Here, data arrives from a source radio station to a destination radio station. A routing method such as AODV has been proposed.

FIG. 8 shows an overview of routing in a prior art wireless multi-hop network.
In FIG. 8, reference numeral 100 denotes a network, 101 to 104 are wireless stations (specifically, 101 is a transmission source wireless station, 102 is a destination wireless station, and 103 to 104 are relay nodes). Represents a radio metric value. For example, when data is transferred from the network 100 to the wireless station 103, the wireless station 101 and the wireless station 103 can simply cope with each other by directly communicating via a wireless line. On the other hand, when data is transferred to the wireless station 102 that cannot directly communicate with the wireless station 101, the route of the transmission source wireless station 101 → the relay node 103 → the destination wireless station 102 and the transmission source wireless As in the route of the station 101 → the relay node 104 → the destination wireless station 102, a routing process for searching for an optimum route from routes having a plurality of options is required.

  In this routing process, first, a wireless metric defined as an index indicating the state of a wireless line such as a transmission speed, a traffic amount, and an interference amount that can be operated between wireless stations is used. In order to simplify the description, it is assumed here that the state of the wireless line is preferable when the wireless metric value is small. For example, in FIG. 8, the wireless metric value between the transmission source wireless station 101 and the relay node 103 is “12”, the wireless metric value between the transmission source wireless station 101 and the relay node 104 is “10”, and the relay node. The radio metric value between 103 and the destination radio station 102 is “20”, and the radio metric value between the relay node 104 and the destination radio station 102 is “12”. Processing for performing routing under these conditions is shown below.

(Step 1) Each radio station exchanges radio metrics with neighboring radio stations.
(Step 2) The source wireless station 101 broadcasts a request packet in the multihop network. Specifically, a request packet containing a radio metric value is sent from the transmission source radio station 101 to neighboring relay nodes 103 to 104.

(Step 3) Each relay node 103 to 104 further adds a request packet obtained by adding (accumulating or adding) a radio metric value to the next radio station to the radio metric value in the received request packet. Send to. In FIG. 8, since both the relay node 103 and the relay node 104 have only the destination wireless station 102 as a relay destination, a request packet is transmitted to this station.

(Step 4) The destination radio station 102 refers to the radio metric value accommodated in the received request packet, and selects the one with the minimum radio metric value accumulated or added over the entire route. In FIG. 8, the route of the transmission source radio station 101 → the relay node 103 → the destination radio station 102 is the integrated (or addition) value of the radio metric values “12” and “20”, and the transmission source radio station 101 → the relay node. Since the route of 104 → destination wireless station 102 is an integrated (or added) value of the radio metric values “10” and “12”, the route of the source wireless station 101 → relay node 104 → destination wireless station 102 is the route. It is judged preferable.

(Step 5) The destination wireless station 102 notifies the relay node of the route selected using the response packet. In FIG. 8, a response packet is sent to the relay node 104.

(Step 6) The relay node 104 that has received the response packet transfers the response packet to the previous wireless station on this route. Specifically, a response packet is transmitted to the transmission source radio station 101, and in the multi-hop network, the route of the transmission source radio station 101, the relay node 104, and the destination radio station 102 is selected and communication is determined.

  The above is an outline of routing in a multi-hop network. In general, when a large number of radio stations coexist, the number of logical routes becomes enormous, and it takes time to select an optimum route from among them. Therefore, in order to appropriately perform such routing processing, there is no change in the topology of the multi-hop network for a certain period, or the state of the individual link of each route is constant for a certain period and the change is small. This assumption is necessary.

FIG. 9 shows a configuration example of a radio station apparatus in the prior art.
In FIG. 9, 121 is a radio station apparatus, 122 is a radio unit, 123 is a baseband signal processing unit, 124 is a radio packet termination unit, 125 is an interface unit, 126 is an antenna, 127 is a communication control unit, and 128 is an identifier acquisition unit. Reference numeral 129 denotes an identifier match determination unit, 130 denotes a radio metric management unit, and 131 denotes the entire control unit. The radio station apparatus here is a general radio station apparatus including a base station and a terminal station, and the basic operation is as described below. In addition, if it is a base station, the function for managing the subordinate terminal station etc. will be added, For example, these functions can be seen as a part of function of the communication control part 127. FIG.

  The radio station apparatus 121 receives a signal via a radio line by an antenna 126, and performs filtering of an out-of-band signal by the radio unit 122, signal amplification by a low-noise amplifier, frequency conversion from an RF frequency to a baseband, and analog signal to digital Processing such as A / D conversion to a signal is performed. The digitized baseband signal is input to the baseband signal processing unit 123 and subjected to a series of baseband signal processing such as timing detection, termination of header information related to the physical layer, demodulation processing, and error correction. The specific processing content here depends on the radio system provided in the radio station apparatus, but the basic operation described below does not depend on the radio system.

  The demodulated signal output from the baseband signal processing unit 123 is input to the wireless packet termination unit 124, where the format of the packet communicated on the wired network such as Ethernet (registered trademark) from the wireless communication format. Is converted to This wireless packet includes overhead such as a so-called header area, and terminates various control information and error detection bits. For example, for a wireless packet determined to have no error by the error detection function, an identifier indicating a destination, a transmission source, or the like is extracted from the header information and transferred to the communication control unit 127. The communication control unit 127 manages the header information. The identifier acquisition unit 128 extracts the destination identifier from the header information, and the identifier match determination unit 129 determines match / mismatch with the own station identifier. This result is fed back to the communication control unit 127, and when it is determined that the destination is the local station, the communication control unit 127 instructs the wireless packet termination unit 124 to output data, and the format-converted packet The interface unit 125 adjusts electrical conditions and the like and outputs them to the outside.

  Conversely, when a packet is input from the outside, it is input to the wireless packet termination unit 124 via the interface unit 125, where header information is added according to an instruction from the communication control unit 124, and further an error detection code, etc. Is added to generate a wireless packet. Here, in addition to the identifier of the destination wireless station, the identifier of the own station is given as the identifier of the transmission source. This signal is input to the baseband signal processing unit 123, where various modulation processes are performed in addition to the addition of header information related to the physical layer and the encoding for error correction, and the preamble signal is added to the base of the radio packet. Generate a band signal. This signal is input to the wireless unit 122, performs D / A conversion for converting a digital signal into an analog signal, frequency conversion, filtering of out-of-band signals, signal amplification, and the like, and is transmitted from the antenna 126.

  When the above routing process is performed, the communication control unit 127 generates and terminates a request packet and a response packet, and manages a wireless metric value that is a communication state with surrounding wireless stations at that time. The necessary information is stored in a database through the wireless metric management means 130 for management.

  The series of signal processing described above is an overview of the entire process, and details include more detailed processing. For example, various timings such as management of a time division switch corresponding to switching between transmission and reception in the radio unit The communication control unit 127 performs control mainly from management to generation / termination of various control information. Further, here, the identifier acquisition unit 128, the identifier match determination unit 129, and the wireless metric management unit 130 have been described separately from the communication control unit 127, but it is also possible to regard all of these as one control unit 131. is there. In other words, it is not necessary to configure as a separate circuit different in hardware, and the entire control unit 131 exists as one circuit that performs software processing, and it is considered that logical functions are separated in its internal processing. It is possible.

Hidenori Aoki et al. “IEEE802.11s Wireless LAN Mesh Network Technology” NTT DoCoMo Technical Journal Vol.14 No.2 pp.14-pp.22, July 2006

The following problems exist in the multi-hop relay with the above routing.
(1) Since the routing processing of the prior art takes time from the start to the completion, frequent rerouting is necessary when the topology of each radio station that can be a relay node and the communication state of each link change rapidly. It becomes. This frequent rerouting overhead reduces communication efficiency.

  (2) Since the communication selected by routing is a combination of multiple stages of one-to-one communication, if an unstable ring exists somewhere on the path, the link is the communication characteristic of all paths. There is a risk of becoming a bottleneck that affects

  Regarding the above problem (1), for example, consider a multi-hop network composed of radio stations mounted in a large number of vehicles moving at high speed. In this case, each car is moving at a high speed, and in particular, in a network in which cars traveling in opposite directions are mixed, the topology changes rapidly. When a large number of vehicles can serve as relay nodes, it takes time to search for an optimum route when searching for various routes. For example, assume that routing takes about 1 second. If each car is moving at 60 km / h, the relative speed of cars traveling in opposite directions will be 120 km / h. Since the distance moved per second at this speed is about 33 m, the topology changes greatly with the movement of this distance. That is, the radio metric value obtained in the above (step 1) at the start of routing changes to a completely different value at the completion of routing, and if communication is continued for 1 second in that state, the accumulated car is about 67 m. It has moved. During this time, another car may enter the link where the line of sight should have been secured, and the line of sight may be interrupted. That is, the time required for routing must be small enough to be negligible with respect to the time scale in which the communication state is considered to be stable. However, this condition cannot be satisfied in the above-described wireless multi-hop network between automobiles.

  Regarding the above problem (2), consider a case where a base station connected to a network provides an FWA service to neighboring households. In this case, the base station has an antenna installed at a relatively high place, and it is highly likely that each user's home can be seen. However, since propagation attenuation with distance is inevitable, the reception level decreases as the distance increases, and as a result, the area where direct communication is possible is limited. Consider a case where an FWA terminal station in which a multi-hop network is set in the user's home is used as a relay node in such a state.

  Since each relay node is installed at a low place with respect to the base station, it is unlikely that a line of sight can be secured between the relay nodes. Furthermore, when there is an area where the density of radio stations that can locally become relay nodes is very low, the quality of communication between the relay nodes and the relay nodes deteriorates, and any of the selected routes If the link is unstable, the communication quality as a whole also becomes unstable. In the first place, the reason why such a problem occurs is that the conditions and installation environment of the base station and the general terminal station are asymmetric, and the communication between the base station and each terminal station is relatively good. However, communication between terminal stations is generally inferior in communication quality compared to communication with base stations, so if there is no element to compensate for the asymmetry, the efficiency of relaying in a multihop network Will decline.

  As described above, when the topology of the multi-hop network changes abruptly or when there is a non-target between the base station and the terminal station in the multi-hop network, the above (1), (2) New technology to solve this problem will be required.

  The present invention enables stable communication by suppressing the influence of the topology change even when the topology of the multi-hop network rapidly changes, and even when an unstable link exists somewhere on the route, An object of the present invention is to provide a wireless communication system and a wireless communication method that enable stable communication while avoiding the risk that the unstable link becomes a bottleneck that affects the communication characteristics of all paths.

  The first invention is composed of one base station and a plurality of radio stations, and the radio packet is transmitted directly or while performing multi-hop relay between the base station and a radio station of a communication partner in the radio station. In a wireless communication system that performs transmission / reception, a wireless station acquires information on a geographical area where a wireless packet transmitted by the local station can be received at a certain level or higher, or a signal arrival area indicating a receivable wireless station. , Comprising means for notifying the base station, the base station comprising signal arrival area acquisition means for collecting information on the signal arrival area acquired by the radio station, and the base station acquiring information on the signal arrival area of each radio station The base station and each radio station use the same frequency channel to determine a time slot that can be transmitted at the same time without interfering with each other, and transmit the radio packet in the time slot Line packet transmission means, and the wireless station determines whether any of the identifier information indicating the transmission source wireless station and the destination wireless station of the received wireless packet matches the identifier information of the base station or the identifier indicating the own station. According to either the identifier match determination means to be determined and the retransmission relay termination condition described in the wireless packet or the retransmission relay termination condition defined in the system, whether or not to perform retransmission relay of the received wireless packet should be terminated. The retransmission relay execution determining means for determining whether the identifier information indicating the source radio station or the destination radio station matches the identifier information of the base station, and the retransmission relay execution determining means When it is determined that retransmission relay should be performed, the packet is transmitted by a wireless packet transmission unit that performs retransmission relay of the received wireless packet and an identifier match determination unit When any one of identifier information indicating the radio station or the destination radio station is determined to match the identifier information of its own station, and a radio packet terminator for extracting data terminates the wireless packet.

  In the radio communication system of the first invention, the radio packet transmitting means transmits a signal of each radio station in N time slots after transmitting the previous radio packet as a time slot for transmitting the next radio packet. By comparing the area and the area where the signal transmitted by the local station reaches, there is no overlap, so that the base station and each radio station can transmit at the same time without interfering with each other using the same frequency channel It is determined that

  The second invention is composed of one base station and a plurality of radio stations, and the radio packet is transmitted directly or while performing multi-hop relay between the base station and a radio station of a communication partner in the radio station. In a wireless communication method of a wireless communication system that performs transmission / reception, information on a geographical area where a wireless station can receive a wireless packet transmitted by the local station at a certain level or more, or information on a signal arrival area indicating a wireless station that can be received And the base station has a signal arrival area acquisition step for collecting information on the signal arrival area acquired by the wireless station, and the base station acquires each wireless station acquired by the base station. The base station and each radio station use the same frequency channel to determine time slots that can be transmitted at the same time without interfering with each other. A wireless packet transmission step of transmitting a line packet, wherein the wireless station is one of identifier information indicating a transmission source wireless station and a destination wireless station of the received wireless packet, or an identifier indicating the base station The identifier match determination step for determining whether or not the packets match, and the retransmission relay of the received wireless packet according to either the retransmission relay termination condition described in the wireless packet or the retransmission relay termination condition defined in the system Re-transmission relay execution determination step for determining whether to perform or end, and the identifier match determination step determines that either of the identifier information indicating the transmission source radio station or the destination radio station matches the identifier information of the base station, and When it is determined that retransmission relay should be performed in the retransmission relay execution determination step, a wireless parameter that performs retransmission relay of the received wireless packet is determined. When it is determined that either of the identifier information indicating the source wireless station or the destination wireless station matches the identifier information of the local station in the packet transmission step and the identifier match determination step, the wireless packet is terminated and data is stored. And a radio packet termination step to be extracted.

  In the wireless communication method of the second invention, in the wireless packet transmission step, as a time slot for transmitting the next wireless packet, a signal of each wireless station arrives in N time slots after transmitting the previous wireless packet. By comparing the area and the area where the signal transmitted by the local station reaches, there is no overlap, so that the base station and each radio station can transmit at the same time without interfering with each other using the same frequency channel It is determined that

  The wireless communication system and the wireless communication method of the present invention enable the transmission source wireless station and the destination wireless station to perform relay relay in a multi-hop manner in a situation where it is difficult for the transmission source wireless station and the destination wireless station to directly perform data communication. When communication between stations is realized, it is possible to realize without requiring a routing process for optimizing a route in which one-to-one communication is combined in multiple stages. As a result, even when the topology of the multi-hop network changes abruptly, it becomes possible to provide stable communication while suppressing the influence of the topology change.

  Also, instead of combining one-to-one communication in multiple stages, a plurality of wireless stations are involved in retransmission relay, so even if there is an unstable ring somewhere on the route, many other Since routes are operated in parallel, it is possible to avoid the risk that unstable local links become a bottleneck that affects the communication characteristics of all routes.

  Furthermore, the present invention controls the base station and the radio station that transmit radio packets at the same time using the same frequency channel by using the signal arrival area of the signal transmitted by the base station and the radio station. Utilization efficiency can be improved.

It is a figure which shows the system configuration example to which the retransmission relay in this invention is applied. It is a figure which shows the basic operation example of the retransmission relay in this invention. It is a figure which shows the basic structural example of the radio station apparatus in this invention. It is a figure which shows the basic processing flow of the retransmission relay in this invention. It is a figure which shows the operation example of the retransmission relay in the Example of this invention. It is a figure which shows the example of the signal arrival area management table which a base station uses. It is a figure which shows the packet transmission processing flow of the base station in this invention. It is a figure which shows the outline | summary of the routing in the radio | wireless multihop network of a prior art. It is a figure which shows the structural example of the radio station apparatus in a prior art.

  Embodiments of a wireless communication system according to the present invention will be described below with reference to the drawings. First, the overall basic operation will be described before the description of the individual embodiments. In this specification, the term “retransmission relay” is used, but this is different from communication in which one-to-one communication at the time of multi-hop relay is combined in multiple stages, and the transmission source described in the header area It is intended to relay without rewriting the identifier of the destination wireless station, and does not mean so-called retransmission for error correction (ARQ: Automatic Repeat reQest).

FIG. 1 shows a system configuration example to which the retransmission relay according to the present invention is applied.
In FIG. 1, 1-1 to 1-2 are base stations, 2-1 to 2-7 and 3-1 to 3-7 are radio stations, 4-1 to 4-2 are radio packets, 5-1 to 5 -2 represents the service area of each base station, and 100 represents a network.

  Base stations 1-1 and 1-2 connected to the network 100 form service areas 5-1 and 5-2, respectively. The service area 5-1 is an area managed by the base station 1-1, and the service area 5-2 is an area managed by the base station 1-2. Radio stations 2-1 to 2-7 exist in the service area 5-1, and radio stations 3-1 to 3-7 exist in the service area 5-2. The radio stations 2-1 to 2-3 can communicate with the base station 1-1, but the other radio stations 2-4 to 2-7 cannot directly communicate with the base station 1-1. The service area here refers to an area that is expanded as a multi-hop network by a radio station managed by the base station 1-1 and in which the radio station can communicate with the base station 1-1. Each of the base stations 1-1 to 1-2 and each of the wireless stations 2-1 to 3-7 is assigned an identifier. For example, the base station 1-1 has “A”, and the base station 1-2 has The identifier of “B”, “a” for the wireless station 2-1, “b” for the wireless station 2-2,..., “N” for the wireless station 3-7.

  Assume that the radio stations 2-1 to 3-7 belonging to each service area 5-1 to 5-2 know the identifier of the base station that manages the service area. This grasping method may be any method. For example, in the case of an FWA service, base station information for each service area may be set at the time of service contract. If the position of the wireless station is known, it is provided on the network or the wireless station. The identifier of the base station may be grasped by referring to the database and the position information. Furthermore, the base station may notify the users in the area. In this way, for example, the wireless stations 2-1 to 2-7 in the service area 5-1 recognize in advance that the identifier of the base station 1-1 that manages the own station is “A”. .

  Next, consider a case where there is data to be transmitted from the network 100 to the radio station 2-7. This data is input from the network 100 to the base station 1-1, and the base station 1-1 generates a wireless packet 4-1 including a transmission source identifier “A” and a destination identifier “g” in the header area. Send. This wireless packet 4-1 is received by wireless stations 2-1 to 2-3 in the vicinity of the base station 1-1. For example, when the wireless station 2-1 receives the wireless packet 4-1, the wireless station 2-1 recognizes the transmission source identifier “A” and the destination identifier “g” given to the header area. Here, since the identifier of the base station 1-1 that manages the own station is “A”, it can be recognized that the transmission source is the base station 1-1 that manages the own station. Assume that the wireless stations 2-1 to 2-3 that have received the wireless packet 4-1 under such conditions retransmit the wireless packet and the wireless stations 2-4 to 2-6 have received it. Similarly, these wireless stations 2-4 to 2-6 receive the wireless packet equivalent to the wireless packet 4-1, and recognize the transmission source identifier “A” and the destination identifier “g” given to the header area thereof. To do.

  Here, since the identifier of the base station 1-1 that manages the wireless station 2-4 to 2-6 is "A", the transmission source is the base station 1-1 that manages the local station. Can be recognized. Similarly, the radio packet is retransmitted and received by the radio station 2-7. The wireless station 2-7 recognizes the transmission source identifier “A” and the destination identifier “g” given to the header area of the received wireless packet, and recognizes that the destination identifier matches the identifier of the own station. As a result, it is possible to recognize that this wireless packet is addressed to the own station, terminate this wireless packet, and take out the data contained therein. In this way, communication from the base station 1-1 to the radio station 2-7 is realized.

  Next, uplink communication from the downstream to the upstream of the multihop network will be described. For example, consider a case where there is data to be transmitted from the wireless station 3-7 to the network 100 side. The wireless station 3-7 generates a wireless packet 4-2 including a transmission source identifier “n” and a destination identifier “B” in the header area, and transmits this. This wireless packet is received by wireless stations 3-4 to 3-6 in the vicinity of the wireless station 3-7. For example, when receiving the wireless packet 4-2, the wireless station 3-4 recognizes the transmission source identifier “n” and the destination identifier “B” given to the header area. Here, since the identifier of the base station 1-2 that manages the own station is “B”, it can be recognized that the destination is the base station 1-2 that manages the own station. Assume that the wireless stations 3-4 to 3-6 that have received the wireless packet 4-2 under such conditions retransmit the wireless packet and that the wireless stations 3-1 to 3-3 have received it. Similarly, these wireless stations 3-1 to 3-3 receive a wireless packet equivalent to the wireless packet 4-2 and recognize the transmission source identifier “n” and the destination identifier “B” given to the header area. To do.

  Here, since the identifier of the base station 1-2 that manages its own station is “B”, the wireless stations 3-1 to 3-3 also recognize that the destination is the base station 1-2 that manages its own station. can do. Similarly, the wireless packet is retransmitted and received by the base station 1-2. The base station 1-2 recognizes the transmission source identifier “n” and the destination identifier “B” given to the header area of the received wireless packet, and recognizes that the destination identifier matches the identifier of the own station. As a result, it is possible to recognize that this wireless packet is addressed to the own station, terminate this wireless packet, take out the data accommodated therein, and transfer it to the network 100. In this way, communication from the radio station 3-7 to the base station 1-2 is realized.

  It should be noted here that, for example, a signal equivalent to the wireless packet 4-2 retransmitted by the wireless station 3-4 due to leakage of radio waves from a nearby service area is transmitted to the base station 1-1. It is assumed that, for example, the radio station 2-3 or the radio station 2-6 (which means that the radio station 2-3 exists in the service area 5-1 of the base station 1-1) has been received. At this time, the wireless station 2-3 or 2-6 can recognize the transmission source identifier “n” and the destination identifier “B” given to the header area of the received wireless packet. Since it does not match the identifier “A” of the base station 1-1 that manages the retransmission, retransmission relay is not performed.

  The above is the basic operation. The feature is that there are a plurality of radio stations that perform retransmission relay, and all of them transmit signals of the same content at the same frequency and at the same timing. When the frequency error of each radio station can be ignored, even if there is a slight timing error, it can be regarded as a signal equivalent to a multipath signal. In addition, in FIG. 1, since three radio stations transmit at the same time, the total transmission power is tripled, and a diversity effect is also obtained because the signals are from physically different places. On the receiving side, signals from multiple radio stations are combined and received, so it is expected that the characteristics will vary from radio station to radio station, but the gain is improved by the number of relay stations with respect to the average received power. Therefore, it is expected that the line gain of the entire system is greatly improved. In particular, even if there is a locally unrecognizable link, signals can be received from a plurality of radio stations, and a plurality of candidates exist on the receiving side, so the diversity effect is very large. Furthermore, since the one-to-one communication is not configured in multiple stages, a routing process for selecting an optimum route is unnecessary, and it is possible to flexibly cope with a sudden change in topology.

FIG. 2 shows a basic operation example of retransmission relay in the present invention.
In FIG. 2, 11 is a base station, 12-1 to 12-9 are radio stations that perform retransmission relay, and 13 is a destination radio station. 2 (1) shows the positional relationship between the base station 11, the radio stations 12-1 to 12-9, and the destination radio station 13, and FIG. 2 (2) shows the transmission of each radio station in the time slots # 1 to # 8. Or a reception state is shown and a horizontal axis shows time.

  In time slot # 1, when the base station 11 transmits a radio packet to the radio station 13, the radio stations 12-1 to 12-3 receive this signal. In the next time slot # 2, the base station 11 transmitting in the previous time slot # 1 and the receiving radio stations 12-1 to 12-3 perform retransmission relaying, and the radio stations 12-4 to 12-12. -6 receives this radio packet. In the next time slot # 3, the base station 11 and the radio stations 12-1 to 12-3 transmitting in the previous time slot # 2 and the receiving radio stations 12-4 to 12-6 repeat retransmission The wireless stations 12-7 to 12-9 receive this wireless packet. In the next time slot # 4, the base station 11 and the radio stations 12-1 to 12-6 that have been transmitting in the previous time slot # 3 and the radio stations 12-7 to 12-9 that have received the transmission operation The destination wireless station 13 receives this wireless packet. Thereby, the wireless packet transmitted by the base station 11 can be received by the destination wireless station 13.

  Similarly, when the wireless station 13 transmits a wireless packet addressed to the base station 11, when the wireless station 13 transmits the wireless packet in time slot # 5, the wireless stations 12-7 to 12-9 receive this wireless packet. . In the next time slot # 6, the wireless station 13 transmitting in the previous time slot # 5 and the receiving wireless stations 12-7 to 12-9 perform retransmission relaying, and the wireless stations 12-4 to 12-12. -6 receives this radio packet. In the next time slot # 7, the radio station 13 and radio stations 12-7 to 12-9 transmitting in the previous time slot # 6 and the receiving radio stations 12-4 to 12-6 repeat retransmission The wireless stations 12-1 to 12-3 receive this wireless packet. In the next time slot # 8, the radio station 13 and radio stations 12-4 to 12-9 that were transmitting in the previous time slot # 7 and the radio stations 12-1 to 12-3 that were received are retransmitted. The destination base station 11 receives this wireless packet. As a result, the radio packet transmitted by the radio station 13 can be received by the base station 11.

  Here, until a predetermined time slot, each wireless station continues to repeatedly transmit the received wireless packet. In this manner, the final radio packet delivery can be ensured by increasing the total transmission power.

FIG. 3 shows a basic configuration example of a radio station apparatus according to the present invention.
In FIG. 3, 21 is a radio station device, 22 is a radio unit, 23 is a baseband signal processing unit, 24 is a radio packet termination unit, 25 is an interface unit, 26 is an antenna, 27 is a communication control unit, and 28 is an identifier acquisition unit. , 29 is an identifier match determination unit, 30 is a base station identifier acquisition unit, 31 is a retransmission relay execution determination unit, and 32 is an entire control unit. As described in the description of the prior art, the wireless station device here is a general wireless station device including a base station and a terminal station. If it is a base station, a function for managing a terminal station under its control, etc. However, since these functions can be regarded as a part of the functions of the communication control unit 27, it is basically possible to understand including the base station and the terminal station in the following description. .

  The basic operation is the same as that of the prior art, but the operation in the case of retransmitting a packet other than the wireless packet addressed to the own station is different. Therefore, only this point will be described here. A signal via a wireless line is received by the antenna 26, and the signal processed by the wireless unit 22 and the baseband signal processing unit 23 is input to the wireless packet terminator 24. Is converted to a typical packet format. Here, the header information attached to the wireless packet is taken out and transferred to the communication control unit 27. The communication control unit 27 manages the header information. The identifier acquisition unit 28 extracts the source identifier and the destination identifier from the header information, and the identifier match determination unit 29 connects the local station identifier and the local station to which the local station is connected. A match / mismatch determination with the identifier is performed. This result is fed back to the communication control unit 27, and when it is determined that the destination is the local station, the communication control unit 27 instructs the wireless packet termination unit 24 to output data, and the format-converted packet Is output to the outside by adjusting the electrical conditions and the like in the interface unit 25.

  On the other hand, when the identifier match determining unit 29 determines that the source identifier or the destination identifier is not addressed to the own station but matches the identifier of the base station to which the own station is connected, this result is used as the retransmission relay execution determining unit 31. The retransmission relay execution determination means 31 determines whether or not the retransmission relay can be performed in consideration of various determination conditions described later, and notifies the communication control unit 27 of the result. When the communication control unit 27 receives an instruction to perform retransmission relay, the wireless packet termination unit 24 receives the wireless packet as it is or changes the header information according to a predetermined rule, and performs processing such as error detection coding. The wireless packet is updated, and this is transmitted to the wireless line via the baseband signal processing unit 23, the wireless unit 22, and the antenna 26. In this way, retransmission relay is performed.

  In addition, although the change rule of the header information of a radio | wireless packet, the judgment conditions of retransmission relay implementation judgment, etc. are demonstrated in the following examples, it is not limited to these examples. Also, the base station identifier acquisition means 30 is a base station to which the own station is to be connected when the communication control unit 27 acquires the base station identifier notified by the base station or from various information provided by itself. Get identifier information. That is, the identifier of the base station may be acquired from a radio packet received from the base station, or may be referred to from a database held by the own station. In this case, if the wireless station can acquire the position information of its own station such as GPS, an identifier corresponding to the nearest base station is acquired based on the position information and the position of the base station on the database, etc. It is also possible to acquire based on other information. In the case of an FWA service or the like, it may be set at the time of contracting or at the time of equipment installation. As described above, the purpose of “acquisition of identifier” by the base station identifier acquisition means 30 is not necessarily active acquisition, but is processing of reading setting values in the apparatus and searching from a database. Also good. Thus, the base station identifier acquisition means 30 manages the identifier information acquired in various forms, and responds to the inquiry of the identifier match determination means 29. The communication control unit 27, the identifier acquisition unit 28, the identifier match determination unit 29, the base station identifier acquisition unit 30, and the retransmission relay execution determination unit 31 have been described separately from the communication control unit 27. It can also be regarded as the entire control unit 32 of the above. That is, it is not necessary to configure as a separate circuit different in hardware, and the entire control unit 32 exists as one circuit that performs software processing, and the logical functions are considered to be separated in its internal processing. It is also possible.

  The above is the operation when a wireless packet is received through a wireless line, but when a packet is input from the outside, naturally the reference such as the identifier is omitted and the transmission operation similar to the conventional technique is performed. . However, in the prior art, the operation for routing is specified, but here, since the wireless packet is transferred without performing routing, these functions are not necessary.

  The series of signal processing described above is an overview of the entire process, and details include more detailed processing. For example, various timings such as management of a time division switch corresponding to switching between transmission and reception in the radio unit The communication control unit 27 performs control mainly from management to generation / termination of various control information.

FIG. 4 shows a basic processing flow of retransmission relay in the present invention.
In FIG. 4, when each wireless station receives a wireless packet (S1), it acquires a transmission source identifier and a destination identifier from predetermined fields of the received wireless packet (S2), and the destination identifier matches the identifier of its own station. Whether or not (S3). If they match, the wireless packet is terminated and data output processing is performed (S6), and the processing is terminated as "no retransmission relay" (S7).

  On the other hand, if they do not match in step S3, it is determined whether or not the source identifier or destination identifier matches the identifier of the base station that manages the own station (S4). The process is terminated as “none” (S7). On the other hand, if they match, it is determined whether or not the retransmission relay execution conditions are met (S5). If the retransmission execution conditions are met, retransmission relay is performed (S9). If they do not match, retransmission relay is performed. Is finished (S8). When retransmission relay is performed in step S9, the process returns to step S5 again after the retransmission relay is performed, and it is continuously determined whether or not the conditions for retransmission relay are met. If the repeated retransmission execution condition is met, the retransmission relay is continued a plurality of times, and the retransmission relay is terminated when the condition is not met. Note that the retransmission relay execution condition here is a specific example in the following embodiment. For example, to what time slot the retransmission relay is continued, and how many times the retransmission relay is repeated until the retransmission relay is finished. It means conditions such as.

  The above description does not involve any routing processing as described in the prior art. When a base station or a terminal station is a transmitting station, it is necessary to ensure consistency such as setting header information of radio packets as needed or adapting frame conditions and broadcast information to retransmission relay conditions as necessary. There is. Further, after the new transmission of the wireless packet (S10), the transmitting station proceeds to the process S5 in the same manner as when receiving the wireless packet, and the subsequent processing is the same as when receiving the wireless packet and matches the retransmission execution condition. Whether or not retransmission relay is completed (S8) or retransmission relay execution (S9) is executed according to the determination result.

  Here, the retransmission relay implementation condition in which the wireless station repeats the retransmission relay will be described. When the number of retransmissions at each radio station is specified as a retransmission execution condition, the following is performed. For example, the retransmission relay may be performed only once in the next time slot after receiving the wireless packet. Similarly, the number of times may be limited to twice, such as the next time slot after receiving the wireless packet and the next time slot only. In any case, retransmission relay is repeated at the previous wireless station, but the number of retransmissions at each wireless station is limited.

  Further, when a time slot (hop count) in which retransmission relaying is continued is defined as a retransmission execution condition, it is as follows. As a condition for grasping the remaining number of retransmissions in a wireless packet, for example, a retransmission counter is recorded, and when there is a remaining number of retransmission counters when a wireless packet is received, retransmission relay is performed only for the remaining period. carry out. If the retransmission counter (hereinafter referred to as “RC”) indicates the remaining number of retransmissions, when RC = 2 is received, the counter value is subtracted by 1 at the time of the first retransmission relay, and RC = 1, the next retransmission At the time of relaying, RC = 0 is set, the counter value is updated, accommodated in a radio packet, and transmitted. The radio station that has received the radio packet with RC = 0 does not perform the next retransmission relay. That is, it is limited to retransmission relays up to the time slot (hop count) set in the retransmission counter by the wireless station that first transmitted the wireless packet. In this operation, the contents of the radio packet are changed every time the relay is retransmitted. However, since all the radio stations update the contents of the radio packet with the same rule, the same radio packet is eventually transmitted. It is possible to send.

  Furthermore, a frame configuration is set for the time slot when relaying a wireless packet, and retransmission relay is continued within the same frame, but the retransmission relay is terminated at the end of the frame and the retransmission relay is not carried forward until the next frame. Good. In addition to the transmission of the wireless packet, the base station may instruct whether to perform retransmission relay, and may determine whether to perform retransmission relay according to the instruction.

  The basic concept of retransmission relay described above is a technical feature of the invention described in the prior application (Japanese Patent Application No. 2011-082022).

  In such a configuration that performs retransmission relay, stable communication can be realized by not involving a diversity effect by cooperation of a plurality of radio stations and routing processing. However, as a factor that determines the characteristics of the system, it is also important how to operate a time slot when the base station or the wireless station transmits or retransmits a wireless packet.

FIG. 5 shows an operation example of retransmission relay in the embodiment of the present invention.
In FIG. 5, 11 is a base station (A), 12-1 to 12-9 are radio stations, and 13 is a destination radio station (Z). FIG. 5 (1) shows the positional relationship between the base station 11 and the radio stations 12-1 to 12-9,13. FIG. 5 (2) shows the transmission or reception states of the base station and each radio station in time slots # 1 to # 8, and the horizontal axis represents time. The signal arrival areas # 1 to # 4 are used to transmit signals in the base station 11, the radio stations 12-1 to 12-3, the radio stations 12-4 to 12-6, and the radio stations 12-7 to 12-9, respectively. Indicates the reach area.

  The feature of the present invention is that the base station 11 uses the information of the signal arrival areas # 1 to # 4 of the radio stations 12-1 to 12-9 to control the time slot in which the base station 11 transmits radio packets. It is in.

  The signal arrival areas # 1 to # 4 are information managed by the base station 11, and when the base station 11 and the radio stations 12-1 to 12-9 transmit radio packets, the radio packets are set to a certain level. The geographical area information that can be received as described above, or the information of the receivable wireless station itself is shown. The base station 11 manages this information, and controls the time slot for transmitting the wireless packet so that the signal arrival areas do not overlap between the wireless stations at the time of retransmission relay, thereby suppressing co-channel interference and unnecessary. Therefore, it is possible to suppress a decrease in frequency reuse efficiency due to a simple interference avoidance.

  In this embodiment, a case will be described in which retransmission relaying is performed only in the next time slot after receiving a wireless packet (the number of retransmission relays is 1). For example, in time slot # 1, assuming that radio stations 12-1 to 12-3 adjacent to the base station 11 can receive, an area in which these radio stations 12-1 to 12-3 are located (predicted) The signal arrival area # 1 can be defined as Alternatively, the radio stations 12-1 to 12-3 themselves that can receive a signal from the base station 11 may be defined as a signal arrival area. Similarly, in the time slot # 2, the radio stations 12-4 to 12-6 adjacent to the radio stations 12-1 to 12-3 can receive, and these radio stations 12-4 to 12-6 are located ( Signal arrival region # 2 can be defined as a region to be predicted. Here, the signal arrival area # 2 includes the base station 11 that exists in the direction opposite to the signal transmission direction, but when a wireless packet that has been transmitted in the past is received, it is discarded. If the retransmission relay is not performed, the signal arrival area is practically shifted in place every time slot. In this way, when it seems that the effect is small even if retransmission relay is performed, that is, in the area where retransmission relay has been performed in the past, by suppressing the number of transmitting radio stations, interference to surrounding service areas is reduced. Can be reduced.

  Therefore, combinations such as signal arrival areas # 1 of the base station 11 and signal arrival areas # 4 of the radio stations 12-7 to 12-9 shown in FIG. Wireless packets can be transmitted. In order to perform such simultaneous transmission, the transmission time slot interval of the base station 11 is set to 3, that is, wireless packets are transmitted in time slots # 1, # 4, and # 7. If the transmission time slot interval is 2, the base station 11 and the radio stations 12-4 to 12-6 transmit radio packets in the same time slot. Since # 3 is overlapped by the wireless stations 12-1 to 12-3, they interfere with each other, and the wireless stations 12-1 to 12-3 may not be able to receive signals correctly. On the other hand, if the transmission time slot interval is 4 or more, there is no base station and radio station that transmit radio packets in the same time slot, so there is no risk of interference, but frequency reuse efficiency decreases.

  In this way, the base stations and the radio stations control the time slots in which radio packets can be transmitted using the same frequency channel based on the information on the signal arrival areas, so that the signal arrival areas do not overlap each other. That is, it is possible to achieve high frequency reuse efficiency by performing relay transmission of wireless packets while maintaining a minimum distance where the base station and the wireless station do not interfere with each other.

FIG. 6 shows an example of a signal arrival area management table used by the base station.
Here, information on wireless stations that can receive wireless packets at a certain level or higher is shown for each wireless station that performs retransmission relay in a coordinated manner. In the signal arrival area management table shown in FIG. 6 (2), the wireless stations that transmit / receive in one time slot are arranged in the order in which the wireless packets are relayed, that is, in the number of hops. At this time, it can be seen that the transmission of the base station 11 addressed to the radio stations 12-1 to 12-3 can be spatially reused in the time slot # 4. Based on this signal arrival area management table, the base station 11 determines a time slot in which a wireless packet can be transmitted.

  Here, it is common for each wireless station to acquire the signal arrival area and notify the base station. The acquisition can be carried out in various ways. For example, when the wireless station can acquire the position information of its own station such as GPS, the signal arrival distance may be calculated based on the position information and the attenuation amount of the signal to be transmitted, and set as the signal arrival area. In addition, nearby wireless stations that can receive signals may be detected by carrier sense, and the wireless stations may be used as signal arrival areas. Thus, the base station notifies the base station of the signal arrival area information acquired by each wireless station by notifying the base station by retransmission relay or using a control channel of a different frequency band. Collect area information. The timing at which the base station collects signal arrival area information may be sent from the base station to the radio station in a centralized manner at a certain time, or in a control time slot predetermined as a system. May autonomously collect and notify the signal arrival area information.

  Since the information on the signal arrival areas of the base station and each radio station generally changes with time, the above-described processes may be performed at a predetermined cycle.

  In addition, when the base station cannot acquire information on the signal arrival areas of all the radio stations, only the information on the signal arrival areas in the vicinity of the base station is used, and signals transmitted by other radio stations that perform retransmission relaying. It is also possible to measure the radio field intensity.

  In the case of an FWA service or the like, it may be set at the time of contracting or at the time of equipment installation. Information on the signal arrival area acquired in various forms in this way is managed by the base station.

  In addition, as the signal arrival area information, it is necessary to grasp the signal arrival area when a plurality of radio stations cooperate and transmit simultaneously. Therefore, the cooperative radio station is selected from the individual radio stations, and the signal arrival area is determined. calculate. Which radio station cooperates may be inferred from the position information that can be acquired by GPS or the like as a group of radio stations that cooperate with each other, and the radio stations with which the base station cooperates are determined in advance. Any means such as instructing at the time of wireless packet relay transmission may be used.

Next, an operation example of the present embodiment will be described with reference to FIG.
In time slot # 1, when the base station 11 transmits a wireless packet, the wireless stations 12-1 to 12-3 receive this signal. In the next time slot # 2, the radio stations 12-1 to 12-3 that were received in the previous time slot # 1 perform a transmission operation, and the radio stations 12-4 to 12-6 receive this signal. The base station 11 receives the signal but discards it. In the next time slot # 3, the radio stations 12-4 to 12-6 that received in the previous time slot # 2 perform a transmission operation, and the radio stations 12-7 to 12-9 receive this signal. The radio stations 12-1 to 12-3 also receive the signal but discard it.

  In the next time slot # 4, the radio stations 12-7 to 12-9 that have been received in the previous time slot # 3 perform a transmission operation, and the destination radio station 13 receives this signal. The radio stations 12-4 to 12-7 also receive the signal but discard it. At the same time, the base station 11 transmits a new radio packet, and the radio stations 12-1 to 12-3 receive this signal.

  In the next time slot # 5, the radio stations 12-1 to 12-3 that have been received in the previous time slot # 4 perform a transmission operation, and the radio stations 12-4 to 12-6 receive the signals. To do. The base station 11 receives the signal but discards it. In the next time slot # 6, the radio stations 12-4 to 12-6 that have been received in the previous time slot # 5 perform a transmission operation, and the radio stations 12-7 to 12-9 receive this signal. The radio stations 12-1 to 12-3 also receive the signal but discard it.

  In the next time slot # 7, the radio stations 12-7 to 12-9 that have been received in the previous time slot # 6 perform a transmission operation, and the destination radio station 13 receives this signal. The radio stations 12-4 to 12-7 also receive the signal but discard it. At the same time, the base station 11 transmits a new radio packet, and the radio stations 12-1 to 12-3 receive this signal. In the next time slot # 8, the radio stations 12-1 to 12-3 that have been received in the previous time slot # 7 perform a transmission operation, and the radio stations 12-4 to 12-6 receive the signals. To do. The base station 11 receives the signal but discards it.

  In this way, the radio packet transmitted by the base station 11 is retransmitted without interference between the radio stations, and can be received by the destination radio station 13.

FIG. 7 shows a packet transmission processing flow of the base station in the present invention.
In FIG. 7, when a new wireless packet transmission process is started (S11), the signal arrival area management table is referred to grasp the time slot utilization status of retransmission relay in other wireless stations (S12). It is determined whether or not there is any overlap (S13). The time slot use information here is not only directly grasped from the signal arrival area management table shown in FIG. 6 (2) but also whether the other radio stations near the base station are transmitting radio signals. It may be measured and guessed. In the case of inferring from the radio wave intensity, whether or not the radio wave intensity exceeds a certain threshold is a determination criterion in step S12. For example, when transmitting in the time slot, a radio station that receives the time slot determines that there is an overlap if the radio field intensity of a signal transmitted from another radio station exceeds a certain threshold. If Yes in step S13, no new wireless packet is transmitted in the current slot, and only one time slot is waited (S14), and the process returns to step S12 to perform transmission processing in the next time slot. On the other hand, in the case of No in step S13, in consideration of a predetermined number of retransmission relays, when performing N retransmission relays, the system waits for N-1 time slots (S15) and transmits a new wireless packet. Processing is performed (S16), and the processing is terminated (S17).

  In the description of FIG. 5 and FIG. 6, the number of retransmission relays of the wireless station has been described as one, but it may be two or more. At this time, the signal arrival area is set according to the number of radio stations performing retransmission relay, and the base station efficiently transmits radio packets from a plurality of base stations / radio stations that can transmit at the same time using the same frequency channel. Determine a time slot that can be transmitted well.

  The present invention is realized by giving an operation in the base station. The wireless station other than the base station does not use the signal arrival area information, and the operation flow of the retransmission relay is the basic operation shown in FIG. It is the same as the processing. If the number of retransmission relays is different, the determination condition is the number of retransmission relays in step S5 of FIG.

1-1, 1-2 Base stations 2-1 to 2-7, 3-1 to 3-7, 101 to 104 Wireless stations 4-1 and 4-2 Wireless packets 5-1 and 5-2 Service area 100 Network DESCRIPTION OF SYMBOLS 11,101 Base station 12-1-12-9 Radio station which performs resending relay 13 Destination radio station 21, 121 Radio station apparatus 22, 122 Radio part 23, 123 Baseband signal processing part 24, 124 Radio packet termination means 25 , 125 interface unit 26, 126 antenna 27, 127 communication control unit 28, 128 identifier acquisition unit 29, 129 identifier match determination unit 30 base station identifier acquisition unit 31 retransmission relay execution determination unit 32, 131 control unit 130 wireless metric management unit

Claims (4)

A radio comprised of one base station and a plurality of radio stations, which transmits and receives radio packets directly or while performing multi-hop relay between the base station and a radio station of a communication partner in the radio station In a communication system,
The radio station acquires information on a geographical area where radio packets transmitted by the own station can be received at a certain level or higher, or information on a signal arrival area indicating a receivable radio station, and notifies the base station of the information. With means,
The base station comprises signal arrival area acquisition means for collecting information on the signal arrival area acquired by the wireless station,
The base station refers to the acquired information on the signal arrival area of each radio station, and determines the time slot that the base station and each radio station can transmit at the same time without interfering with each other using the same frequency channel. The wireless packet transmitting means for transmitting the wireless packet in the time slot,
The wireless station is
Identifier match determining means for determining whether any of the identifier information indicating the source wireless station and the destination wireless station of the received wireless packet matches the identifier information of the base station or the identifier indicating the own station;
Retransmission relay for determining whether or not to perform retransmission relay of the received wireless packet according to either a retransmission relay termination condition described in the wireless packet or a retransmission relay termination condition defined on the system Implementation decision means;
It is determined by the identifier match determination means that either identifier information indicating a source radio station or a destination radio station matches the identifier information of the base station, and it is determined that retransmission relay execution determination means should perform retransmission relay. Wireless packet transmission means for performing retransmission relay of the received wireless packet,
Radio packet termination means for terminating the radio packet and extracting data when it is determined by the identifier match judgment means that either identifier information indicating the source radio station or the destination radio station matches the identifier information of the own station And a wireless communication system. The wireless communication system according to claim 1, wherein
The radio packet transmission means includes a time slot for transmitting the next radio packet, and a region in which a signal of each radio station arrives in N time slots after transmitting a previous radio packet and a signal transmitted by the own station. Compared with the reachable area, the base station and each radio station are determined to be time slots that can be transmitted at the same time without interfering with each other by using the same frequency channel because there is no overlap. Wireless communication system. A radio comprised of one base station and a plurality of radio stations, which transmits and receives radio packets directly or while performing multi-hop relay between the base station and a radio station of a communication partner in the radio station In a wireless communication method of a communication system,
The radio station acquires information on a geographical area where radio packets transmitted by the own station can be received at a certain level or higher, or information on a signal arrival area indicating a receivable radio station, and notifies the base station of the information. Has steps,
The base station has a signal arrival area acquisition step of collecting information of a signal arrival area acquired by the wireless station,
The base station refers to the acquired information on the signal arrival area of each radio station, and determines the time slot that the base station and each radio station can transmit at the same time without interfering with each other using the same frequency channel. And a wireless packet transmission step of transmitting the wireless packet in the time slot,
The wireless station is
An identifier match determination step for determining whether any of the identifier information indicating the source radio station and the destination radio station of the received radio packet matches the identifier information of the base station or the identifier indicating the own station;
Retransmission relay for determining whether or not to perform retransmission relay of the received wireless packet according to either a retransmission relay termination condition described in the wireless packet or a retransmission relay termination condition defined on the system An implementation decision step;
In the identifier match determination step, it is determined that either of the identifier information indicating the source radio station or the destination radio station matches the identifier information of the base station, and it is determined in the retransmission relay execution determination step that retransmission relay should be performed. A wireless packet transmission step for performing retransmission relay of the received wireless packet,
Radio packet termination step for terminating the radio packet and extracting data when it is determined in the identifier match judgment step that either identifier information indicating the source radio station or the destination radio station matches the identifier information of the own station And a wireless communication method. The wireless communication method according to claim 3,
In the wireless packet transmission step, as a time slot for transmitting the next wireless packet, an area in which the signal of each wireless station arrives in N time slots after transmitting the previous wireless packet and a signal transmitted by the own station are Compared with the reachable area, the base station and each radio station are determined to be time slots that can be transmitted at the same time without interfering with each other by using the same frequency channel because there is no overlap. Wireless communication method.

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