JP5595982B2 - 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. 16 shows an overview of routing in a prior art wireless multi-hop network.
In FIG. 16, 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. 16, 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. 16, 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. 16, 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. 16, 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. 17 shows a configuration example of a radio station apparatus in the prior art.
In FIG. 17, 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 constituted by a group destination station and a plurality of radio stations, between a base station and a radio station of a communication partner in a radio station, the radio packet describing the identifier information indicating the source and destination In a wireless communication system in which retransmission is repeated in multiple hops at the same frequency according to time slots synchronized between a base station and all wireless stations , the wireless station includes base station identifier acquisition means for acquiring an identifier of the base station, and received radio An identifier match judging means for judging whether or not the identifier indicating the source or destination acquired from the packet matches the identifier of the base station or the identifier of the own station, and the retransmission relay termination condition described in the wireless packet Or, according to any of the retransmission relay termination conditions defined on the system, the retransmission relay process for determining whether the retransmission relay of the received wireless packet should be performed or terminated. When the determination means and the identifier match determination means determine that either the identifier indicating the transmission source or the destination matches the identifier of the base station, and the retransmission relay execution determination means determines that the retransmission relay should be performed, The received radio packet is transmitted as it is, or the header information is changed according to a predetermined rule common between the base station and all the radio stations, and transmitted in each time slot subsequent to the time slot after receiving the radio packet. A wireless packet transmission means, an arrival notification signal transmission means for transmitting an arrival notification signal to another station, and an identifier match determination means when it is determined by the identifier match determination means that the identifier indicating the destination matches the identifier indicating the own station The wireless packet termination that terminates the received wireless packet and extracts data when it is determined that the identifier indicating the destination matches the identifier indicating the local station. And a stage, a retransmission relay implementation determining unit, when receiving the arrival notice signal, regardless of the end condition of the retransmission relay is configured to determine that end the retransmission relay of the wireless packet.

In the wireless communication system of the first invention, the arrival notification signal transmission means divides a time slot for transmitting and receiving the arrival notification signal into a plurality of subslots, and transmits the arrival notification signal in each subslot. , and the radio station, when receiving the arrival notice signal in one of the sub-slots in the next sub-slot following each of the sub-slot, further comprising an arrival notification signal retransmission means for transmitting an arrival notice signal received .

  In the wireless communication system of the first invention, the retransmission relay execution determining means satisfies the retransmission relay termination condition described in the wireless packet and receives the arrival notification signal from another station within a predetermined time. In this configuration, the retransmission relay termination condition described in the packet is reset, and it is determined that retransmission relay should be performed.

  In the wireless communication system of the first invention, the retransmission relay execution determining means is configured to wait for a predetermined period in order to receive an arrival notification signal when a wireless packet satisfying the retransmission relay termination condition is received.

The second invention is constituted by a group destination station and a plurality of radio stations, between a base station and a radio station of a communication partner in a radio station, the radio packet describing the identifier information indicating the source and destination In the wireless communication method in which retransmission is repeated in multiple hops at the same frequency according to time slots synchronized between the base station and all the wireless stations , the wireless station uses the base station identifier acquisition means to acquire the identifier of the base station When, using the identifier matching judgment means, an identifier indicating a received the source or destination acquired from the wireless packet, and determining whether to match the identifier indicating identifier or local station of the base station, the retransmission Using the relay execution determining means, the received wireless parameters are received according to either the retransmission relay termination condition described in the wireless packet or the retransmission relay termination condition defined in the system. Using the wireless packet transmission means, the identifier match determination means determines that either the source or destination identifier matches the base station identifier using the wireless packet transmission means. When the retransmission relay execution determining means determines that retransmission relay should be performed, the received wireless packet is changed as it is or the header information is changed according to a predetermined rule common between the base station and all the wireless stations. Then , using the arrival notification signal transmitting means, the identifier indicating the destination is changed to the identifier indicating the own station by using the arrival notification signal transmitting means and the step of transmitting the time slot after the time slot after receiving the wireless packet. When it is determined that the addresses match, the step of transmitting the arrival notification signal to another station and the wireless packet termination means indicate the destination by the identifier match determination means. When the identifier is determined to match the identifier indicating the own station, to execute a step of extracting the data terminates the wireless packet received, the retransmission relay implementation determining unit, when receiving the arrival notice signal, retransmits Regardless of the relay termination condition, it is determined that retransmission of the wireless packet is terminated.

In the wireless communication method of the second invention, the arrival notification signal transmitting means divides a time slot for transmitting and receiving the arrival notification signal into a plurality of subslots, and transmits the arrival notification signal in each subslot, When the wireless station receives the arrival notification signal in any of the subslots using the arrival notification signal retransmission means, the wireless station transmits the received arrival notification signal in each subslot after the next subslot. Run further .

  In the wireless communication method of the second invention, the retransmission relay execution determining means satisfies the retransmission relay termination condition described in the wireless packet, and does not receive the arrival notification signal from another station within a predetermined time. The retransmission relay end condition described in the packet is reset, and it is determined that retransmission relay should be performed.

  In the wireless communication method of the second invention, the retransmission relay execution determining means waits for a predetermined period in order to receive the arrival notification signal when a wireless packet satisfying the retransmission relay termination condition is received.

  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.

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 Example 1 of this invention. It is a figure which shows the structural example of the radio station apparatus in Example 1 of this invention. It is a figure which shows the processing flow of the retransmission relay in Example 1 of this invention. It is a figure which shows the operation example of the retransmission relay in Example 2 of this invention. It is a figure which shows the processing flow of the retransmission relay in Example 2 of this invention. It is a figure which shows the operation example of the retransmission relay in Example 3 of this invention. It is a figure which shows the other operation example of the retransmission relay in Example 3 of this invention. It is a figure which shows the structural example of the radio station apparatus in Example 3 of this invention. It is a figure which shows the processing flow of the retransmission relay in Example 3 of this invention. It is a figure which shows the operation example of the retransmission relay in Example 4 of this invention. It is a figure which shows the processing flow of the retransmission relay in Example 4 of 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 means 29 determines that the source identifier or 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 sent to the retransmission relay execution determining means 31. The retransmission relay execution determination means 31 determines whether or not 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 relay execution conditions are met, retransmission relay is performed (S9). The relay is terminated (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 relay 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 radio packet (S10), the transmitting station proceeds to the process S5 in the same manner as when the radio packet is received, and the subsequent processing is the same as when the radio packet is received and meets the retransmission relay implementation conditions. Whether or not to perform retransmission is determined, and depending on the result of the determination, retransmission relay termination (S8) or retransmission relay execution (S9) is performed.

  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 the retransmission relay 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 the time slot (hop count) in which the retransmission relay is continued is defined as the retransmission relay 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.

  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).

  Here, if the destination of the received wireless packet is the local station, the wireless station can determine that retransmission relay of the wireless packet is not necessary, but other wireless stations can reach the destination wireless station. Whether or not it has been performed is not considered as a condition for performing retransmission relay. Therefore, when the destination wireless station and a wireless station located in the vicinity thereof receive a wireless packet by retransmission relay, the destination wireless station itself recognizes that the subsequent retransmission relay is unnecessary, Since the located radio station cannot recognize that the necessity of the retransmission relay is lost, the retransmission relay is continued unnecessarily. In the present invention, a wireless station involved in retransmission relay is provided with a means for grasping that a wireless packet has arrived at the destination wireless station, and the retransmission relay can be stopped when the wireless packet reaches the destination wireless station. Like that.

FIG. 5 shows an example of retransmission relay operation in Embodiment 1 of the present invention.
Here, an operation example of the radio station for each time slot is shown. In order to configure a time slot, the entire system may be synchronized using time synchronization means such as GPS. Even if there is no time synchronization means such as GPS, the same processing is performed so that transmission is started after the same predetermined period when each wireless station receives a wireless packet, which is similar to providing a time slot. Alternatively, the transmission timing may be aligned. In the present invention, a wireless station that has received a wireless packet determines whether or not there is an ACK transmitted from another wireless station in the next time slot, and performs retransmission relay when no ACK is received. When ACK is received, it is recognized that the wireless packet has reached the destination wireless station, and retransmission relay is stopped. Therefore, the time slot is set to a length sufficient to receive the ACK after receiving the radio packet.

  In FIG. 5, the base station (A) 11 transmits a radio packet destined for the radio station (Z) 13. The source identifier of the wireless packet is “A”, and the destination identifier is “Z”. In time slot # 1, the base station 11 transmits a wireless packet, and the wireless stations 12-1 to 12-3 receive the wireless packet. The wireless stations 12-1 to 12-3 determine whether or not the destination identifier of the received wireless packet matches the identifier of the own station, and determine that they do not match. Subsequently, it is determined whether the destination identifier or the transmission source identifier matches the identifier of the base station that manages the own station. Here, the transmission source identifier matches the identifier of the base station that manages the own station. The station recognizes that it should perform retransmission relay. In the next time slot # 2, it waits to confirm whether or not an ACK transmitted by another station (destination radio station) is received. The wireless stations 12-1 to 12-3 that have not received the ACK perform retransmission relaying of the received wireless packet in the time slot # 3, and the wireless stations 12-4 to 12-6 receive this wireless packet. .

  Similarly, since the destination identifiers of the received wireless packets do not match the identifiers of the own stations, and the transmission source identifiers match the identifiers of the base stations that manage the own stations, the wireless stations 12-4 to 12-6 The local station recognizes that it should perform retransmission relay, and waits in order to confirm whether or not an ACK transmitted by another station is received in the next time slot # 4. The wireless stations 12-4 to 12-6 that have not received the ACK perform retransmission relaying of the received wireless packet in the time slot # 5, and the wireless stations 12-7 and 12-8 and the wireless station 13 Receive the packet.

  Similarly, the wireless stations 12-7 and 12-8 are such that the destination identifier of the received wireless packet does not match the identifier of the own station, and the transmission source identifier matches the identifier of the base station that manages the own station. The local station recognizes that it should perform retransmission relay, and waits to confirm whether or not an ACK transmitted by another station is received in the next time slot # 6. On the other hand, since the destination identifier of the received wireless packet matches the identifier of the own station, the wireless station 13 transmits ACK in the next time slot # 6, and the wireless stations 12-7 and 12-8 transmit this ACK. Receive. The wireless stations 12-7 and 12-8 confirm that the wireless packet is received by the destination wireless station 13 by ACK reception, and stop subsequent retransmission relays. Also, the destination wireless station 13 naturally does not perform retransmission relay.

  Thus, when the wireless stations 12-9 to 12-11 exist ahead of the wireless stations 12-7 and 12-8, the wireless stations 12-7 and 12-8 perform retransmission relaying in the configuration of the prior application. Although there is a possibility of performing this, in the present invention, subsequent retransmission relays can be stopped at the radio stations 12-7 and 12-8.

  Further, FIG. 5 shows a case where a radio packet received by each radio station is retransmitted only once, but a configuration in which retransmission relay is performed N times or more times may be employed. That is, in the retransmission relay shown in FIG. 5, the base station 11 and the radio stations 12-1 to 12-6 each end with one retransmission relay, but the radio stations 12-7 and 12-8 receive ACK. Does not perform retransmission relay itself. In any case, when the wireless packet reaches the destination wireless station 13, it is possible to avoid that the wireless stations subsequent to the destination wireless station repeat the relay (the wireless packet is relayed indefinitely). In addition, as a condition for a radio station to stop retransmission relaying except for ACK reception, the time slot (hop count) set in the retransmission counter by the radio station that first transmitted the radio packet is specified, not the number of retransmissions at each radio station. Such a case will be described in the third and subsequent embodiments.

FIG. 6 shows a configuration example of a radio station apparatus according to Embodiment 1 of the present invention.
In FIG. 6, the radio station apparatus according to the first embodiment has a configuration in which an ACK reception determination unit 40 and an ACK transmission determination unit 42 are added to the basic configuration example of the radio station apparatus illustrated in FIG. 3. When the communication control unit 27 receives an ACK transmitted from another station via the wireless unit 22 or the like, the communication control unit 27 transfers the information to the ACK reception determination unit 40, and the ACK reception determination unit 40 receives the ACK at a predetermined time. The result is output to the retransmission relay execution determination unit 31 and the ACK transmission determination unit 42. The retransmission relay execution determining unit 31 and the ACK transmission determining unit 42 determine the necessity of retransmission relay and the necessity of ACK transmission based on the match information output from the identifier match determination unit 29. In this configuration example, the retransmission relay execution determination unit 31, the ACK transmission determination unit 42, and the like are shown separated from the communication control unit 27. However, these functions may be integrated into one control unit 32 as a whole. Good. 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 divided in the internal processing. It can be considered.

FIG. 7 shows a processing flow of retransmission relay in Embodiment 1 of the present invention.
In FIG. 7, when each wireless station receives a wireless packet (S101), it acquires a transmission source identifier and a destination identifier from predetermined fields of the received wireless packet (S102), and the destination identifier matches the identifier of its own station. It is determined whether or not (S103). If they match (Yes in S103), an ACK is transmitted (S104), the wireless packet is terminated and data output processing is performed (S105), and the processing is terminated as “no retransmission relay” (S106). On the other hand, if the identifier of the own station does not match the destination identifier (No in S103), it is determined whether or not the source identifier or the destination identifier matches the identifier of the base station that manages the own station (S107). If they do not match (No in S107), the processing is terminated as “no retransmission relay” (S106). If they match (Yes in S107), the system waits for one time slot (S108), and determines whether or not an ACK has been received (S109). If an ACK has been received (Yes in S109), the processing is terminated as “no retransmission relay” (S106). If ACK has not been received (No in S109), it is determined whether or not the retransmission relay execution conditions are met (S110), and as long as they match (Yes in S110), retransmission relay is performed (S112). The process of S110 is repeated. As shown in FIG. 5, the retransmission relay execution condition may be a condition that the retransmission relay is performed only once after the packet is received, or the retransmission relay execution condition may be set as a retransmission relay execution condition a predetermined number of times.

  In addition, regarding the transmission / reception of said ACK, it is necessary to communicate on the conditions which the radio | wireless station or base station which exists widely can receive normally. If the transmission method used for transmission of large-capacity user data (corresponding to communication in time slots # 1, # 3, # 5, etc.) is used for ACK transmission as it is, insufficient gain in the line design becomes a problem. However, since it is an ACK notification with a small amount of information, a decrease in transmission efficiency is limited even if a very robust modulation scheme is used. For example, a training signal having a known pattern may be transmitted and recognized as ACK by correlation detection. That is, various conditions including the transmission method in the transmission of the ACK may be completely different from those when transmitting a large amount of user data or the like. The technology disclosed in the present invention is merely to set a time slot for transmitting an ACK between time slots that perform retransmission relay of large-capacity user data or the like in the background art, and this ACK time slot This is a technique relating to signal processing and apparatus configuration for stopping retransmission relaying when a signal recognized as ACK is detected in FIG.

  In the first embodiment, an operation example in which only the destination wireless station transmits an ACK is shown. However, in the second embodiment, not only the destination wireless station but also wireless stations located in the vicinity thereof transmit ACK in cooperation with each other. explain. In other words, a method in which a plurality of radio stations cooperatively relay and relay the ACK is adopted. In this case, a shortage of line gain in an area where ACK needs to be notified can be compensated by simultaneously retransmitting ACKs by a plurality of wireless stations.

  First, when a plurality of wireless stations including a destination wireless station receive a wireless packet in a certain time slot but the distance between the wireless station and the destination wireless station is long, that is, the destination wireless station transmits. A situation where other wireless stations cannot receive ACK is conceivable. At this time, the radio station that has not received the ACK performs unnecessary retransmission relay. In order to prevent this, in the present embodiment, the ACK is transmitted not only to the destination radio station but also to a radio station far from the destination radio station by transmitting the ACK in cooperation with the radio stations located in the vicinity. Is possible.

  FIG. 8 shows an example of retransmission relay operation in Embodiment 2 of the present invention. Here, a case is shown in which each wireless station performs retransmission relay only once, but it may be possible to perform retransmission relay N times or more. That is, even when no ACK is received, there is no retransmission relay more than the specified number of times.

  In FIG. 8, the operations up to time slot # 5 are the same as those in the first embodiment shown in FIG. That is, the wireless stations 12-4 to 12-6 that have not received the ACK in the time slot # 4 perform retransmission relay on the received wireless packet in the time slot # 5, and the wireless stations 12-7 to 12-9 The destination wireless station 13 receives this wireless packet. The destination radio station 13 transmits an ACK in the next time slot # 6 because the destination identifier of the received radio packet matches the identifier of its own station, and the radio stations 12-8 and 12-9 send this ACK. Although it can be received, the radio station 12-7 is in a position where it cannot receive this ACK directly.

  Therefore, in the second embodiment, each wireless station recognizes a time slot for transmitting / receiving an ACK as a subslot. In FIG. 8, the number of subslots constituting a time slot is set to 3, but is not limited to this value and is determined by a setting value on the system.

  The destination wireless station 13 that has received the wireless packet transmits ACK in the first subslot # 1 (indicated as “A” in the figure), and subsequently transmits ACK also in the subsequent subslots # 2 and # 3. To do. Here, when the wireless stations 12-8 and 12-9 receive the ACK transmitted by the wireless station 13 in the subslot # 1 (indicated as “receive” in the figure), the wireless stations 12-8 and 12-9 ACK is retransmitted in subslots # 2 and # 3. Then, the wireless station 12-7 receives the ACK transmitted by the wireless station 12-8 in the subslots # 2 and # 3. In this way, the wireless stations 12-7 to 12-9 that have received the wireless packet in the time slot # 5 can receive the ACK transmitted by the destination wireless station 13 and recognize that retransmission relay is unnecessary. Can do.

  The configuration of the radio station apparatus in the second embodiment is the same as the configuration of the radio station apparatus in the first embodiment shown in FIG.

  FIG. 9 shows a processing flow of retransmission relay according to the second embodiment of the present invention. 7 differs from the first embodiment shown in FIG. 7 in that S104 is replaced with S114, and S108 to S109 are replaced with S115 to S119.

  In FIG. 9, when the destination identifier of the received wireless packet matches the identifier of its own station (Yes in S103), the wireless station transmits ACK in all subslots constituting the time slot (S114). When the destination identifier of the received wireless packet does not match the identifier of the own station (No in S103) and the source identifier or the destination identifier matches the identifier of the base station that manages the own station (Yes in S104), one sub It waits for a slot (S115) and determines whether or not an ACK has been received (S116). If no ACK has been received, this is repeated for a predetermined number of subslots constituting the time slot (S117), and if no ACK is received during that time (Yes in S117), the retransmission relay execution condition is met. Whether or not (S110), as long as they match (Yes in S110), repeat relay is performed (S112), and the processing of S115 to S110 is repeated.

  On the other hand, if an ACK is received while waiting for a predetermined number of subslots (Yes in S116), it is determined whether or not a predetermined number of subslots have been waited (S118). If a predetermined number of subslots are not waited (No in S118), ACK is transmitted in all remaining subslots (S119), and it is determined that there is no data packet retransmission relay (S106). When waiting for a predetermined number of subslots (Yes in S118), it is determined that there is no retransmission of the data packet without transmitting its own ACK (S105).

  In the first and second embodiments, the wireless station that has received the ACK stops retransmission relay at that time, but the number of times each wireless station performs retransmission relaying is limited (once in FIGS. 5 and 8), Even when each wireless station does not receive ACK, retransmission relay is stopped when the number of retransmission relays reaches the designated number. As a result, even if the wireless station cannot receive ACK, it is possible to avoid infinite retransmission of the wireless packet in each wireless station. However, since retransmission relay itself is taken over from a wireless station that cannot receive ACK to the next wireless station, retransmission relay continues in the entire wireless communication system. Note that the second embodiment is a method of extending the range in which ACK can be received by cooperatively relaying ACK by resending ACK even if there is a radio station that cannot directly receive ACK. There is a limit in the relationship between the number of subslots and the number of hops from the destination wireless station that transmits the ACK.

  In the third embodiment, in order to cope with this, a method is used in which a retransmission counter that is decremented for each retransmission relay is used to set an upper limit of the number of retransmission relays performed in the entire wireless communication system. In this method, each time a wireless station that transmits a wireless packet and a wireless station that receives the wireless packet perform retransmission relaying, the retransmission counter stored in the wireless packet is decremented by 1 and retransmitted until the retransmission counter reaches zero. Repeat the relay. On the other hand, when the retransmission counter reaches zero, the retransmission relay is terminated, so that no further retransmission relay is performed as the entire system. However, this method cannot determine whether or not the wireless packet has reached the destination wireless station. Accordingly, if a small upper limit value is set for the number of retransmission relays, a situation may occur in which the wireless packet does not reach the destination wireless station while the retransmission counter is in a zero state.

  Thus, in the third embodiment, when the wireless packet has not reached the destination wireless station, the wireless packet has not reached the destination wireless station among the wireless stations that have received the wireless packet whose retransmission counter is zero. The wireless station that has grasped this enables the wireless packet to reach the destination wireless station by transmitting the wireless packet in which the retransmission counter is reset (resending the retransmission relay). In the first embodiment and the second embodiment, an ACK transmission / reception time slot is assigned every time a wireless packet is retransmitted, but in the third embodiment, until the retransmission counter becomes 0, the ACK transmission / reception time slot is Only when the retransmission counter is 0 without assigning, a time slot is assigned to transmit / receive ACK.

FIG. 10 illustrates an operation example of retransmission relay according to the second embodiment of the present invention.
In FIG. 10, a base station (A) 11 transmits a radio packet destined for a radio station (Z) 13. The source identifier of the wireless packet is “A”, and the destination identifier is “Z”. The wireless packet retransmission counter (RC) is set to “2”. In time slot # 1, the base station 11 transmits a wireless packet, and the wireless stations 12-1 to 12-3 receive the wireless packet. Since the destination identifiers of the received radio packets do not match the identifiers of the own stations and the destination identifier or the transmission source identifier matches the identifier of the base station that manages the own station, The station recognizes that it should perform retransmission relay. In time slot # 2, the base station 11 subtracts 1 from the RC of the transmitted radio packet, and transmits the reconfigured radio packet with RC = 1. Also, in the same time slot # 2, the radio stations 12-1 to 12-3 subtract 1 from the RC of the received radio packet, retransmit the radio packet reconstructed by setting RC = 1, and the radio station 12 -4 to 12-6 receive this wireless packet. In the time slot # 3, the base station 11 and the radio stations 12-1 to 12-3 subtract 1 from the RC of the transmitted radio packet, and set RC = 0 to retransmit the reconstructed radio packet. Also, in the same time slot # 3, the radio stations 12-4 to 12-6 subtract 1 from the RC of the received radio packet, retransmit the radio packet reconstructed with RC = 0 set, and the radio station 12 -7 to 12-9 receive this radio packet.

  The base station 11 and the radio stations 12-1 to 12-6 stop further retransmission relay since the transmitted radio packet is RC = 0. On the other hand, the radio stations 12-7 to 12-9 that have received the radio packet with RC = 0 stand by in order to confirm whether or not an ACK transmitted by another station (destination radio station) is received in time slot # 4. Here, since the destination wireless station 13 has not yet received the wireless packet, the wireless stations 12-7 to 12-9 do not receive the ACK and recognize that the wireless packet has not reached the destination wireless station. To do. Therefore, in time slot # 5, the radio stations 12-7 to 12-9 resume retransmission retransmission of radio packets for which RC is newly set. Here, RC = 0 is set so that retransmission relay is performed once.

  When resetting the retransmission counter and restarting the retransmission relay, a retry flag or retry counter is set in the header area of the wireless packet so that the wireless packet received by the wireless station can be recognized as the restarted retransmission relay. It may be set. This is to prevent resetting of the retransmission counter and resumption of retransmission relay from being repeated indefinitely. For example, by setting the retry flag from 0 to 1 for a wireless station that resumes retransmission relay, it is possible to let other wireless stations know that resumption of subsequent retransmission relay is prohibited. Further, in the retry counter that defines the upper limit value of the number of retransmission restarts, the counter value can be added or subtracted each time the retransmission relay is restarted to allow retransmission restart until a predetermined value is reached. Here, since the wireless stations 12-7 to 12-9 have not received the ACK, the retransmission relay is resumed. However, when the ACK is received, the retransmission relay is not resumed.

  In time slot # 5, the radio stations 12-7 to 12-9 resume retransmission of the radio packet with RC = 0, and the radio stations 12-10 to 12-11 and the destination radio station 13 receive the radio packet. To do. In time slot # 6, the radio stations 12-10 to 12-11 stand by in order to confirm whether or not an ACK transmitted by another station (destination radio station) is received.

  On the other hand, the wireless station 13 transmits an ACK because the destination identifier of the wireless packet received in the time slot # 5 matches the identifier of the own station, and the waiting wireless stations 12-10 to 12-11 receive this ACK. Receive. The radio stations 12-10 to 12-11 confirm that the radio packet is received by the destination radio station 13 by ACK reception, and stop the subsequent retransmission relay. Also, the destination wireless station 13 naturally does not perform retransmission relay.

  Note that RC may be set to 1 or more when retransmission relay is resumed. For example, when RC = 1 is set, the radio stations 12-7 to 12-9 continuously transmit radio packets with RC = 1 in time slot # 5 and RC = 0 in # 6, and radio stations 12-10 and 12-11. Transmits a radio packet with RC = 0 once in time slot # 6 and ends retransmission relaying. Here, the destination wireless station 13 receives the RC = 1 wireless packet transmitted by the wireless stations 12-7 to 12-9 in the time slot # 5, but until the RC = 0 wireless packet is received. Wait for time and send an ACK in time slot # 7. The radio stations 12-12 and 12-13 that have received the radio packet of RC = 0 from the radio stations 12-10 and 12-11 in the time slot # 6 receive the ACK in the time slot # 7 and complete the retransmission relay. . This is shown in FIG.

FIG. 12 shows a configuration example of a radio station apparatus according to the third embodiment of the present invention.
In FIG. 12, the radio station apparatus according to the third embodiment has a configuration in which a retransmission counter acquisition unit 33 and a retransmission counter value match determination unit 34 are added to the configuration example of the radio station apparatus according to the first embodiment illustrated in FIG. . In the operation, when a wireless packet is received via a wireless line, the information of the retransmission counter is transferred from the communication control unit 27 to the retransmission counter obtaining unit 33 from the header area of the wireless packet. The retransmission counter acquisition unit 33 checks whether or not the predetermined value matches the value of the retransmission counter. The result is notified to the retransmission relay execution determining means 31, and the retransmission relay is performed with reference to the instruction.

FIG. 13 shows an operation flow of retransmission relay according to the third embodiment of the present invention.
In FIG. 13, when each wireless station receives a wireless packet (S201), it acquires a transmission source identifier, a destination identifier and a retransmission counter RC from predetermined fields of the received wireless packet (S202). Subsequently, it is determined whether or not the destination identifier matches the identifier of the own station (S203). If they match (Yes in S203), the reception time of the radio packet with RC = 0 is calculated and waits (S204), ACK is transmitted (S205), the radio packet is terminated, and data output processing is performed. (S206), the processing is terminated as "no retransmission relay" (S207). When a radio packet with RC = 0 is received and the destination identifier matches the identifier of the own station, ACK is transmitted without waiting (S205).

  On the other hand, when the destination identifier does not match the identifier of the own station (No in S203), it is determined whether or not the source identifier or the destination identifier matches the identifier of the base station that manages the own station (S208). If they do not match (No in S208), the processing ends as “no retransmission relay” (S207). If they match (Yes in S208), it is determined whether or not the received radio packet is RC = 0 (S209). If RC = 0 is not satisfied (No in S209), 1 is subtracted from RC (S213), the radio packet is reconstructed (S214), and retransmission relay is performed using the radio packet (S215). This is repeated until RC = 0 (until No in S216), and retransmission relay is terminated (S217). On the other hand, if RC = 0 (Yes in S209), the system waits for one time slot (S210) and determines whether or not an ACK has been received (S211). When ACK is received (Yes in S211), it is recognized that the wireless packet has reached the destination wireless station, and it is recognized that retransmission relay is unnecessary (S207). If ACK is not received (No in S211), RC is reset (S212), and a radio packet is reconstructed (S214). The reconstructed radio packet is retransmitted (S215), and until RC = 0 (Yes in S216), S213 to S215 are repeated, and the retransmission relay ends (S217).

  In the third embodiment, the operation in which only the destination radio station 13 transmits an ACK has been described. However, the process may be extended to a process of transmitting an ACK in cooperation with surrounding radio stations as in the second embodiment.

  In the third embodiment, when an ACK is not received in a time slot (time slot # 4 in FIG. 10) provided after receiving a radio packet with RC = 0, the radio station has reached the destination radio station. It is possible to make the wireless packet reach the destination wireless station by grasping that there is no transmission and transmitting the wireless packet in which RC is reset (retransmission of retransmission relay). However, a time slot for ACK transmission / reception is not allocated until a radio packet with RC = 0 is received, and only when a radio packet with RC = 0 is received, the time slot is allocated to transmit / receive ACK. Therefore, ACK cannot be transmitted even if it reaches the destination radio station before RC of the radio packet becomes 0, and the reception time of the radio packet of RC = 0 is calculated as shown in S204 of FIG. 11 and FIG. And wait.

  In the fourth embodiment, even when RC ≠ 0, when the destination wireless station receives the wireless packet, the subsequent retransmission relay can be stopped. That is, a time slot for ACK transmission / reception is assigned every time a wireless packet is retransmitted.

  FIG. 14 shows an example of retransmission relay operation in Embodiment 4 of the present invention. Here, each radio station sets a waiting time of one time slot during RC update in retransmission relay (from reception of a wireless packet to retransmission of the wireless packet, or from transmission of a wireless packet to the next retransmission relay). Provided, and whether or not the other station is transmitting ACK.

  In FIG. 14, the base station (A) 11 transmits a radio packet destined for the radio station (Z) 13. The source identifier of the wireless packet is “A”, and the destination identifier is “Z”. The wireless packet retransmission counter (RC) is set to “2”. In time slot # 1, the base station 11 transmits a wireless packet, and the wireless stations 12-1 to 12-3 receive the wireless packet. In the next time slot # 2, it waits to confirm whether or not an ACK transmitted by another station (destination radio station) is received. In time slot # 3, the base station 11 subtracts 1 from the RC of the transmitted radio packet, and transmits the reconfigured radio packet with RC = 1. Also, in the same time slot # 3, the radio stations 12-1 to 12-3 subtract 1 from the RC of the received radio packet, retransmit the reconstructed radio packet with RC = 1, and the radio station 12 -4 to 12-6 receive this wireless packet. In the next time slot # 4, the radio stations 12-1 to 12-6 stand by in order to confirm whether or not an ACK transmitted by another station (destination radio station) is received.

  In time slot # 5, the base station 11 and the radio stations 12-1 to 12-3 subtract 1 from the RC of the transmitted radio packet, and set RC = 0 to retransmit the reconstructed radio packet. Also, in the same time slot # 5, the radio stations 12-4 to 12-6 subtract 1 from the RC of the received radio packet, retransmit the radio packet reconstructed by setting RC = 0, and the radio station 12 -7 to 12-9 receive this radio packet.

  The radio stations 12-1 to 12-6 stop further retransmission relay since the transmitted radio packet is RC = 0. On the other hand, the radio stations 12-7 to 12-9 that have received the radio packet with RC = 0 stand by in order to confirm whether or not an ACK transmitted by another station (destination radio station) is received in time slot # 6. Here, since the destination wireless station 13 has not yet received the wireless packet, the wireless stations 12-7 to 12-9 do not receive the ACK and recognize that the wireless packet has not reached the destination wireless station. To do. Therefore, in the time slot # 7, the radio stations 12-7 to 12-9 retransmit the radio packet in which RC is newly set. In this case, RC = 2 is set to perform three retransmission relays.

  As described in the third embodiment, when the retransmission counter is reset and the retransmission relay is restarted, the wireless packet received by the wireless station can be recognized as the restarted retransmission relay, as described in the third embodiment. A retry flag or a retry counter may be set in the header area.

  In the time slot # 7, the radio stations 12-10 to 12-11 and the destination radio station 13 receive the radio packet by the retransmission relay that has been resumed. In the next time slot # 8, the radio stations 12-7 to 12-11 stand by in order to confirm whether or not an ACK transmitted by another station (destination radio station) is received. Since the destination identifier of the wireless packet received in time slot # 7 matches the identifier of the local station, the wireless station 13 transmits an ACK in time slot # 8, and the wireless stations 12-7 to 12-11 receive this ACK. Receive. The radio stations 12-7 to 12-11 confirm that the radio packet is received by the destination radio station 13 by ACK reception, and stop subsequent retransmission relays even if RC is not zero. Also, the destination wireless station 13 naturally does not perform retransmission relay.

FIG. 15 shows an operation flow of retransmission relay according to the fourth embodiment of the present invention.
In FIG. 15, each radio station receives a radio packet (S301), and acquires a transmission source identifier, a destination identifier, and a retransmission counter RC from predetermined fields of the received radio packet (S302). Subsequently, it is determined whether or not the destination identifier matches the identifier of the own station (S303). If they match (Yes in S303), ACK is transmitted (S304), the wireless packet is terminated and data output processing is performed (S305), and the processing is terminated as “no retransmission relay” (S306). On the other hand, when the destination identifier does not match the identifier of the own station (No in S303), it is determined whether the source identifier or the destination identifier matches the identifier of the base station that manages the own station (S307). If they do not match (No in S308), the processing is terminated as “no retransmission relay” (S307). If they match (Yes in S307), it is determined whether the received radio packet is RC = 0 (S308).

  If the received radio packet is not RC = 0 (No in S308), it waits for one time slot (S315), and determines whether or not an ACK has been received (S316). If ACK has not been received (No in S316), 1 is subtracted from RC (S312), the radio packet is reconstructed (S313), and retransmission relay of the radio packet is performed (S314). Waiting for one time slot again (S315), it is determined whether or not an ACK has been received (S317). If ACK is not received (No in S317), S312 to S317 are repeated until RC = 0. If ACK has been received (Yes in S316), retransmission relay is terminated (S318).

  On the other hand, if the received radio packet is RC = 0 (Yes in S308), it waits for one time slot (S309) and determines whether or not an ACK has been received (S310). When ACK is received (Yes in S310), it is recognized that retransmission relay is unnecessary (S306). If ACK has not been received (No in S310), RC is reset (S311), the radio packet is reconstructed (S313), and this is relayed again (S314). Waiting for one time slot again (S315), it is determined whether or not an ACK has been received (S316). When ACK is not received (No in S316), S313 to S317 are repeated until RC = 0. If ACK has been received (Yes in S316), retransmission relay is terminated (S318).

  In the fourth embodiment, the operation example in which only the destination wireless station transmits the ACK has been described. However, the processing may be extended to the process of transmitting the ACK in cooperation with the surrounding wireless stations as in the second embodiment.

1-1 to 1-2 Base station 2-1 to 2-7, 3-1 to 3-7 Radio station 4-1 to 4-2 Radio packet 5-1 to 5-2 Service area of each base station 100 Network DESCRIPTION OF SYMBOLS 11 Base station 12-1-12-11 Radio station which performs resending relay 13 Destination radio station 21 Radio station apparatus 22 Radio | wireless part 23 Baseband signal processing part 24 Radio | wireless packet termination means 25 Interface part 26 Antenna 27 Communication control part 28 Identifier Acquisition means 29 Identifier match determination means 30 Base station identifier acquisition means 31 Retransmission relay execution determination means 32 Entire control unit 33 Retransmission counter acquisition means 34 Retransmission counter match determination means 40 ACK reception determination means 42 ACK transmission determination means

Claims (8)

It is constituted by a group destination station and a plurality of radio stations, with the wireless station of the communication partner in the said base station radio station, and a source and a wireless packet describing the identifier information indicating the destination the base station In a wireless communication system that repeats and relays multihop by the same frequency according to time slots synchronized between all the wireless stations ,
The radio station is
And the base station identifier acquiring means for acquiring an identifier of the base station,
Identifier matching judgment means for judging whether or not an identifier indicating a transmission source or a destination acquired from the received wireless packet matches an identifier of the base station or an 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;
Received when it is determined by the identifier match determining means that either the identifier indicating the source or the destination matches the identifier of the base station, and when the retransmission relay execution determining means determines that retransmission relay should be performed. The radio packet is left as it is or the header information is changed according to a predetermined rule common between the base station and all the radio stations, and the time slot after the time slot after receiving the radio packet is changed. A wireless packet transmitting means for transmitting; an arrival notification signal transmitting means for transmitting an arrival notification signal to another station when it is determined by the identifier match determination means that an identifier indicating a destination matches an identifier indicating its own station;
A wireless packet terminating means for terminating the received wireless packet and extracting data when the identifier matching determining means determines that the identifier indicating the destination matches the identifier indicating the own station; and
The wireless communication system according to claim 1, wherein the retransmission relay execution determining means determines that the retransmission relay of the wireless packet is terminated regardless of the retransmission relay termination condition when the arrival notification signal is received. . The wireless communication system according to claim 1, wherein
The arrival notification signal transmitting means divides a time slot for transmitting and receiving the arrival notification signal into a plurality of subslots, and transmits the arrival notification signal in each subslot,
The radio station is
When the arrival notification signal is received in any one of the subslots, it further comprises arrival notification signal retransmission means for transmitting the received arrival notification signal in each subslot after the next subslot. Wireless communication system. The wireless communication system according to claim 1, wherein
The retransmission relay execution determining means is described in the wireless packet when the retransmission relay termination condition described in the wireless packet is satisfied and the arrival notification signal is not received from another station within a predetermined time. A wireless communication system, characterized in that a retransmission relay termination condition is reset and it is determined that retransmission relay should be performed. The wireless communication system according to claim 1, wherein
The wireless communication system according to claim 1, wherein the retransmission relay execution determination unit is configured to wait for a predetermined period in order to receive the arrival notification signal when a wireless packet that satisfies the retransmission relay termination condition is received. It is constituted by a group destination station and a plurality of radio stations, with the wireless station of the communication partner in the said base station radio station, and a source and a wireless packet describing the identifier information indicating the destination the base station In a wireless communication method for performing relay relay by multi-hop by the same frequency according to time slots synchronized between all the wireless stations ,
The radio station is
Using a base station identifier acquisition unit, acquiring the identifier of the base station,
Using the identifier matching judgment means, an identifier indicating the source or destination acquired from the wireless packet received, and determining whether to match the identifier indicating the identifier or local station of the base station,
Retransmission relay execution determination means is used to perform retransmission relay of the received wireless packet in accordance with either the retransmission relay termination condition described in the wireless packet or the retransmission relay termination condition defined in the system. A step of determining whether to finish or
Using wireless packet transmission means, it is determined that either the identifier indicating the source or the destination matches the identifier of the base station by the identifier match determination means, and retransmission relay should be performed by the retransmission relay execution determination means The received wireless packet is left as it is or the header information is changed according to a predetermined rule common between the base station and all the wireless stations, and the time slot of the received wireless packet is determined. Transmitting in each of the next and subsequent timeslots ;
Using the arrival notification signal transmitting means, and when the identifier match determining means determines that the identifier indicating the destination matches the identifier indicating the own station, transmitting the arrival notification signal to another station;
Performing a step of terminating the received wireless packet and extracting data when the identifier match determining means determines that the identifier indicating the destination matches the identifier indicating the own station using the wireless packet terminating means. ,
The retransmission relay implementation determining means, when receiving the arrival notification signal, determines that retransmission relay of the wireless packet is ended regardless of the retransmission relay end condition. The wireless communication method according to claim 5, wherein
The arrival notification signal transmitting means divides a time slot for transmitting and receiving the arrival notification signal into a plurality of subslots, and transmits the arrival notification signal in each subslot,
The radio station is
When the arrival notification signal is received in any one of the subslots using the arrival notification signal retransmission unit, a step of transmitting the received arrival notification signal in each subslot after the next subslot is further executed . A wireless communication method. The wireless communication method according to claim 5, wherein
The retransmission relay execution determining means is described in the wireless packet when the retransmission relay termination condition described in the wireless packet is satisfied and the arrival notification signal is not received from another station within a predetermined time. A wireless communication method, characterized by resetting retransmission relay termination conditions and determining that retransmission relay should be performed. The wireless communication method according to claim 5, wherein
The retransmission relay execution determining means waits for a predetermined period to receive the arrival notification signal when receiving a wireless packet that satisfies the retransmission relay termination condition.

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