JP6082995B2 - Communication method and communication system - Google Patents

Description

  The present invention relates to a communication technique in a wireless communication network, and more particularly to a communication technique in a wireless communication network in which a relay station exists between a transmitting station and a receiving station.

In recent years, cooperative relay transmission in which a relay station is introduced between a transmitting station and a receiving station has attracted attention in order to improve the communication quality of a wireless communication network. From the viewpoint of the radio link, for example, AF (Amplify and Forward), DF (Decode and Forward), and distributed self-space code have been proposed as signal processing techniques in various physical layers in cooperative relay transmission.
On the other hand, from the viewpoint of a wireless communication network constructed by a large number of wireless links, various protocols in a medium access control (MAC) layer in cooperative relay transmission have been proposed. In this way, studies for introducing cooperative relay transmission are being developed in each layer of the communication network.

In general, cooperative relay transmission is multi-hop transmission of two or more hops. In multi-hop transmission, not only a one-hop wireless medium is reserved as in single-hop transmission, but also a wireless medium over a multi-hop wide space is reserved.
IEEE (the Institute of Electrical and Electronic Engineers) 802.11 standard that is widely used as a wireless LAN (Local area network) standard as a one-hop wireless medium reservation method (see Non-Patent Document 1, for example) There is a DCF (Distributed Coordination Function) method defined in the above.
Also, a transmission protocol in multi-hop cooperative relay transmission up to 2 hops has been proposed as CoopMAC (Cooperative MAC protocol) (see, for example, Non-Patent Document 2).

  There is an EMAC method as a technique for reserving radio resources over a multi-hop wide area assuming an arbitrary number of hops (see, for example, Non-Patent Document 3). However, the EMAC scheme does not consider aggregation of radio resource information and notification of control information based on the aggregated information.

  The DCF method is a technology that originally assumes transmission of one hop. In order to perform data transmission with end-to-end from the source terminal of traffic in multi-hop transmission to the destination terminal using the DCF method, it is necessary to perform random medium access at each hop. Therefore, in the DCF method, a great overhead is caused due to a collision caused by medium access at each hop, random back-off control, and the like, resulting in waste of radio resources.

  In CoopMAC, only cooperative relay transmission up to 2 hops is assumed, so extension to cooperative relay transmission with a larger number of hops is not obvious.

  The EMAC scheme reserves a wireless medium over an end-to-end wide-area space assuming an arbitrary number of hops, and in the reserved wireless medium, the traffic is generated from the terminal to the destination terminal via one or a plurality of relay terminals. This is a technology for performing data transmission by -to-end. This eliminates the need for random media access at each hop on the multi-hop transmission path. For this reason, overhead that is problematic in the DCF method can be reduced, and transmission efficiency can be improved.

IEEE 802.11-2007, IEEE Standard for Information technology-Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. Pei Liu, Zhifeng Tao, Sathya Narayanan, Thanasis Korakis, Shivendra S. Panwar, “CoopMAC: A Cooperative MAC for Wireless LANs,” IEEE Journal on Selected Areas in Communications, vol. 25, no. 2, pp. 340-354, Feb. 2007. S. Du, Y. Sun and D.B. Johnson, “EMAC: An asynchronous routing-enhanced MAC protocol in multihop wireless networks,” In Proc. GLOBECOM 2010, Miami, FL, USA, pp. 1-6, Dec. 2010.

  However, in the EMAC scheme, communication resources are not fully utilized because communication resource information aggregation and control information notification based on the aggregated resource information are not considered.

  For multi-hop cooperative relay transmission, there is a need for a mechanism that realizes wireless medium access reservation, aggregation of radio resource information, and notification of radio resource control information in the same frame sequence.

  In view of the above circumstances, an object of the present invention is to provide a communication method and a communication system that realizes access reservation of a radio medium, aggregation of radio resource information, and notification of radio resource control information in the same frame sequence.

  One aspect of the present invention is a communication method between a plurality of wireless stations participating in multi-hop transmission having an arbitrary number of hops in a wireless communication network, wherein a start station that starts wireless communication communicates within the wireless communication network. Acquiring a right, recording a listening station for each hop transmitting station in a pre-processing control frame processed before the multi-hop transmission by the starting station that acquired the communication right, and the communication right The acquired starting station has a step of recording the hearing station for each hop transmitting station in a data frame based on the processing result of the preprocessing control frame and executing the multi-hop transmission.

  In one aspect of the present invention, the preprocessing control frame includes a forward control frame relay and a backward control frame relay, and the start station that has acquired the communication right is based on the forward control frame relay, Based on the aggregated resource information based on the backward control frame relay, while performing the access reservation of the wireless medium in each wireless station participating in the multi-hop transmission, and collecting the resource information of the wireless medium that has reserved the access Resource control information is notified to each wireless station participating in the multi-hop transmission.

  In one aspect of the present invention, the preprocessing control frame includes the forward control frame relay and the backward control frame relay in a route to the relay station for the multi-hop transmission.

  In one aspect of the present invention, the start station acquires a communication right in the wireless communication network based on a medium access control method.

  One aspect of the present invention is a communication system including a plurality of wireless stations participating in multi-hop transmission having an arbitrary number of hops in a wireless communication network, wherein a starting station that starts wireless communication is communication within the wireless communication network. Obtain the right, record the listening station for each hop transmitting station in the preprocessing control frame processed before the multi-hop transmission, and based on the processing result of the preprocessing control frame, for each hop transmitting station The station is recorded in a data frame and the multi-hop transmission is performed.

  ADVANTAGE OF THE INVENTION According to this invention, the access reservation of a radio | wireless medium, aggregation of radio | wireless resource information, and the notification of radio | wireless resource control information are realizable by the same frame sequence.

It is a block diagram in the multihop cooperative relay transmission method which concerns on one Embodiment of this invention. It is a block diagram which shows the internal structure of each radio station. It is a flowchart which shows the specific example of the flow of a process of the multihop cooperative relay transmission method. It is a block diagram in the multihop transmission processing method with 3 relay stations. It is a figure which shows the example of an entry when writing a transmitting station group and a receiving station group in the control frame for front and the control frame for back, respectively. It is a figure which shows the specific example of a frame sequence. It is a figure which shows the specific example of a frame sequence.

[Embodiment 1]
FIG. 1 is a configuration diagram of a multihop cooperative relay transmission method (communication method) according to an embodiment of the present invention.
In FIG. 1, a radio station S1 and a radio station S2 are a pair of any one radio station that belongs to the same radio communication network and performs communication. The communication direction between the radio station S1 and the radio station S2 is not limited.
Next, radio stations R1, R2,..., RP represent relay stations that cooperate in communication between the radio stations S1 and S2. In FIG. 1, an unmarked circle is a radio station that is not selected as a relay station without cooperating with communication between the radio station S1 and the radio station S2. The wireless station may be of any form other than an AP (Access Point) or STA (Station) terminal.

FIG. 2 is a block diagram showing an internal configuration of each radio station (radio station S1, radio station S2, radio station R1, radio station R2,..., Radio station RP), and functional blocks related to the present embodiment. Only extracted and shown. As shown in the figure, the radio station 10 includes an antenna 11, a radio communication unit 12, and a communication control unit 13.
The antenna 11 transmits and receives radio signals. Although the figure shows a case where a plurality of antennas 11 are provided, one antenna may be used.
The wireless communication unit 12 performs wireless signal transmission processing, reception processing, and relay processing. In the relay process, data obtained by demodulating / decoding the radio signal received by the antenna 11 by the reception process may be encoded / modulated by the transmission process and output to the antenna 11, or the radio signal received by the antenna 11 may be output. May be amplified and output to the antenna 11.
The communication control unit 13 controls the wireless communication unit 12 and includes a route selection unit 14, a communication right acquisition unit 15, a preprocessing control unit 16, a forward control unit 17, a backward control unit 18, and a transmission control unit 19. .

FIG. 3 is a flowchart showing a specific example of the processing flow of the multi-hop cooperative relay transmission method.
First, one wireless station that starts multi-hop transmission acquires a communication right in the wireless communication network (S1). As a premise, wireless stations included in a transmission frame in a wireless communication network compete for communication rights according to the medium access method. For example, in the case of a wireless LAN, a plurality of wireless stations included in a transmission frame compete for communication rights using a CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) method. In FIG. 1, for example, the wireless station S1 acquires a communication right in the network.

Next, the start station performs preprocessing so that data transmission can be performed from the start station of the multi-hop transmission that has acquired the communication right to the end station of the multi-hop transmission (S2).
The preprocessing of this step has the following two contents.
(Content 1) Record the listening station for the transmitting station of each hop in the pre-processing control frame so that the listening communication not on the multi-hop route can be performed.
(Content 2) A pre-processing control frame sequence is composed of a forward control frame relay and a backward control frame relay.
The direction from the start station to the end station is defined as forward, and conversely, the direction from the end station to the start station is defined as backward. Further, the control frame relay means that a control frame is transmitted from the end of the communication route to the start end via a plurality of wireless stations on the communication route along a certain communication route.
The forward control frame relay means that a control frame is transmitted from the start station to the end station in a direction from the start station to the end station. Similarly, the backward control frame relay means that the control frame is transmitted from the end station to the start station in the direction from the end station to the start station.

  In the control frame sequence, first, through the forward control frame relay, the wireless medium access reservation in each wireless station participating in the multi-hop transmission and the resource information of the reserved medium are aggregated. Next, resource control information based on the aggregated resource information is notified to each wireless station participating in multi-hop transmission through a backward control frame relay. Prepare for multi-hop transmission through the implementation of these two control frame relays.

Next, the start station performs multi-hop transmission and a success / failure response according to the result of the preprocessing (S3).
The multi-hop transmission and success / failure response of this step has the content that the listening station for the transmitting station of each hop is also recorded in the data frame and the success / failure response control frame so that the listening communication not on the multi-hop route is possible. ing.

  Next, after the multi-hop transmission and the success / failure response are completed, the communication right is released to the wireless communication network (S4). A plurality of wireless stations included in a transmission frame belonging to a wireless communication network starts a competition for communication rights of the wireless communication medium again using a medium access control method (for example, a CSMA / CA method used in a wireless LAN).

  The present embodiment establishes a mechanism that realizes wireless medium access reservation, aggregation of radio resource information, and notification of radio resource control information with a unified control frame sequence, assuming an arbitrary number of hops.

  The wireless communication resource information means various information that can be used for communication between a certain wireless station pair. Examples of radio communication resource information include radio channel information (CSI: Channel State Information), received signal-to-noise power ratio (SNR) information, modulation coding scheme (MCS). There is information related to various communication links such as information and traffic (TSI: Traffic State Information) information. The wireless communication resource information is not limited to these examples.

  The preprocessing in step S2 in FIG. 3 will be described in detail. In order to realize high-efficiency multi-hop transmission, it is necessary to perform access reservation of the wireless communication medium, aggregation of resource information of the reserved medium, and notification of resource control information as preprocessing.

With reference to FIG. 4, the contents of preprocessing will be described for multi-hop transmission with three relay stations and four hops between a start radio station and an end radio station. Note that the preprocessing described here can be applied to multi-hop transmission with an arbitrary number of relay stations and hops.
FIG. 4 is a configuration diagram in the multi-hop transmission processing method with three relay stations. The pre-processing control frame sequence is composed of a forward control frame relay having four time steps (see FIG. 4A) and a backward control frame relay having four time steps (see FIG. 4B). The

As a breakdown of the forward control frame relay, at time step # 1, the control frame is transmitted from the radio station S1 to the radio station R1 through the radio link L-S1R1. Further, as a breakdown of the forward control frame relay, the control frame is transmitted from the radio station R1 to the radio station R2 through the radio link L-R1R2 at time step # 2. As a breakdown of the forward control frame relay, the control frame is transmitted from the radio station R2 to the radio station R3 through the radio link L-R2R3 at time step # 3. As a breakdown of the forward control frame relay, the control frame is transmitted from the radio station R3 to the radio station S2 through the radio link L-R3S2 at time step # 4.
The wireless link information means various information that can be used for communication between a certain wireless station pair. For example, as radio link information, radio channel information (CSI: Channel State Information), received signal to noise power ratio (SNR) information, modulation coding scheme (MCS) information, Information related to various wireless links such as traffic (TSI: Traffic State Information) information can be considered. The wireless propagation path information and the received signal-to-noise power ratio information can be obtained as indirect information from the reception state of the training signal or the like in the wireless communication unit 12. Further, the modulation system coding system can be obtained directly from information set in the preprocessing control frame or the like by the transmission source radio station 10. The traffic information can be obtained by monitoring the transmission source of the wireless signal received by the wireless communication unit 12.

  As a breakdown of the backward control frame relay, the control frame is transmitted from the radio station S2 to the radio station R3 at time step # 5. As a breakdown of the backward control frame relay, a control frame is transmitted from the radio station R3 to the radio station R2 at time step # 6. Further, as a breakdown of the backward control frame relay, a control frame is transmitted from the radio station R2 to the radio station R1 at time step # 7. As a breakdown of the backward control frame relay, the control frame is transmitted from the radio station R1 to the radio station S1 at time step # 8.

  In the forward control frame and backward control frame, the addresses of all radio stations participating in multi-hop transmission are disassembled into a transmitter station group TG (Transmitter Group) and a receiver station group RG (Receiver Group), and the order is Put it on.

FIG. 5 shows an example of entry when the transmitting station group TG and the receiving station group RG are described in the forward control frame [see FIG. 5 (a)] and the backward control frame [see FIG. 5 (b)], respectively. FIG.
When implementing forward control frame relay, an example of entry of TG and RG described in the control frame transmitted from the single hop R1 to R2 at time step # 2 is as follows.

Transition from hop R1 to R2 at time step # 2.
TG: S1, R1
RG: R2, R3, S2

In the transmitting station group TG, the addresses of the radio stations S1 and R1 transmitted so far are described in order.
In the receiving station group RG, addresses of receivable radio stations R2, R3, and S2 are described in order.
The first radio station described in the transmission station group TG is a start station of multihop transmission. The start station of multihop transmission corresponds to the radio station S1 in the example of FIG.
The radio station described at the end of the receiving station group RG is a multi-hop transmission end station. The end station of multihop transmission corresponds to the radio station S2 in the example of FIG.
The radio station described at the end of the transmission station group TG is a single-hop R1 to R2 transmission station that is currently implementing control frame relay. This transmission station corresponds to the radio station R1 in the example of FIG.
The first radio station described in the receiving station group RG is a receiving station for the transmitting station R1 of the single hop R1 to R2 that is currently implementing the control frame relay. This receiving station corresponds to the radio station R2 in the example of FIG.
The radio stations described from the second to the last in the receiving station group RG are hearing stations for the transmitting station R1 of the single hop R1 to R2 that are currently implementing the control frame relay. This hearing station corresponds to the radio stations R3 and S2 in the example of FIG.

  The receiving station R2 of the single hop R1 to R2 receives the control frame from the transmitting station R1, and after performing a predetermined process, the receiving station R2 itself becomes the transmitting station R2 in the next single hop R2 to R3, and the transmitting station R2 The control frame updated toward the receiving station R3 and the listening station S2 is relayed toward the end station. The transmitting station group TG and the receiving station group RG described in the control frame are updated as follows.

  The last of the transmitting station group TG in which the address of the first radio station R2 of the described receiving station group RG is described in the control frame received as the receiving station of the previous single hop R1 to R2 Move behind the radio station address. As a result, the transmitting station group TG and the receiving station group RG are as follows.

Transition from hop R1 to R2 at time step # 2.
TG: S1, R1
RG: R2, R3, S2
TG and RG are updated.
Transition from hop R2 to R3 at time step # 3.
TG: S1, R1, R2
RG: R3, S2
The same applies to the update of the transmission group TG and the reception group RG from the next single hop R3 to S2.

  Next, an example of entry of TG and RG described in the control frame transmitted from the single hop R3 to R2 at time step # 6 when performing the backward control frame relay is shown below.

Transition from hop R3 to R2 at time step # 6.
TG: S2, R3
RG: R2, R1, S1

  Similar to the forward control frame relay, S2 is a multi-hop transmission start station, S1 is a multi-hop transmission end station, R3 is a single-hop R3 to R2 transmitting station that currently performs control frame relay, and R2 R1 and S1 are a receiving station and a listening station for the transmitting station R3, respectively. Subsequent updating of the transmission group TG and reception group RG in a single hop at time steps # 7 and # 8 can be similarly analogized.

  However, radio stations that are not described in either the transmitting station group TG or the receiving station group RG of the control frame receive multi-hop transmission by receiving a network allocation vector (NAV) after receiving the control frame. Avoid collisions in the wireless medium with participating wireless stations.

In addition, a wireless link between the transmitting station and the receiving station is set as a desired link, and a wireless link between the transmitting station and the listening station is set as a listening link. In the example of FIG. 5, the radio link between the radio station R1 and the radio station R2 is a desired link, and the radio link between the radio station R1 and the radio stations R3 and S2 is a listening link.
In FIG. 5, the desired link is indicated by a solid line, and the listening link is indicated by a dotted line. While communication between the transmitting station and receiving station is possible on the desired link, communication between the transmitting station and the listening station may or may not be possible on the listening link. Inability to communicate means that communication between the transmitting station and the hearing station cannot be performed accurately.

  As can be seen from FIG. 5, there are four desired links between the radio station S1 which is the start station of the forward multi-hop transmission and the radio station S2 which is the end station, but there are six listening links. . There are a total of 10 wireless links, including the desired link and the listening link. Hearing link communication is an incremental communication resource obtained by recording the station as well as the receiving station for each single-hop transmitting station in the control frame.

In this way, not only the addresses of all radio stations participating in multi-hop transmission are described in the control frame, but also the listening station is recorded in addition to the receiving station for each single-hop transmitting station as follows. Advantages A and B can be obtained.
A, Both desired link communication and listening link communication are possible. This increases the number of patterns in which cooperative relay transmission can be carried out, resulting in an increase in choices for multi-hop transmission routes.
B, Diversity combining reception processing can be applied to the same signal received by each wireless station at different time steps when transmitting a control frame or a data frame without changing the default transmission route.

  From here, for the multi-hop transmission configurations of FIG. 4 and FIG. 5, using a unified control frame sequence, the medium access reservation of each wireless station and the resource information of the reserved wireless medium (that is, for multi-hop transmission). Aggregation of information related to each radio communication link) and notification of radio resource control information (that is, information such as radio resource allocation pattern in each radio station related to multi-hop transmission) through a specific frame sequence A method for realizing this will be described.

  FIG. 6 shows a specific example of the above frame sequence. In FIG. 6, the horizontal axis represents time. In FIG. 6, there are six time axes, and the uppermost time axis is the entire pre-processing control frame sequence in which control frames transmitted by the radio stations S1, S2, R1, R2, and R3 are arranged in time order. . The remaining five time axes have control frames transmitted by the radio stations S1, R1, R2, R3, and S2 as transmitting stations, and radio stations S1, R1, R2, R3, and S2 as receiving stations and listening stations, respectively. The received control frames after radio propagation are arranged in order of time. In FIG. 6, the control frame that was observed is indicated by a dotted frame.

  Here, it is assumed that the anti-collision control RTS (Request To Send) control frame and the CTS (Clear To Send) control frame adopted in the wireless LAN are extended and used. The use of other control frames or control frames of systems other than the wireless LAN may be assumed. The time interval between control frames is SIFS (Short InterFrame Space) used in the wireless LAN.

  Depending on the acquisition method, the resource information can be classified into two types: a type obtained by estimation as unknown and a type obtained by directly receiving information as known. In the present embodiment, both types of resource information are used.

Hereinafter, time steps # 1 to # 4 will be described as a forward control frame relay.
In time step # 1, at hops S1 to R1, the transmitting station group TG and the receiving station group RG are updated, and the transmitting station S1 is extended to the receiving station R1 and the listening stations R2, R3, and S2, and an extended RTS (Extended RTS). Relay the control frame forward.
Detailed exchanges at each related radio station regarding the extended RTS are described in the time axis related to each radio station at the bottom. The transmitting station S1 of hops S1 to R1 transmits an extended RTS including a training signal. The receiving station R1 and the listening stations R2, R3, and S2 receive the extended RTS frame, and use the training signal therein, and the unknown radio resource information L-S1R1, L-S1R2, L- S1R3 and L-S1S2 are estimated.

  In time step # 2, at the hops R1 to R2, the transmitting station group TG and the receiving station group RG are updated, and the transmitting station R1 extends the receiving station R2 and the listening stations R3 and S2 as destinations. ) Relay the control frame forward. In the extended CTS control frame, resource information L-S1R1 obtained in time step # 1 is added in addition to the training signal. The receiving station R2 and the listening stations R3 and S2 of the hops R1 to R2 receive the extended CTS frame from the transmitting station R1, and use the training signal in the received CTS frame to unknown radio resource information with the radio station R1. L-R1R2, L-R1R3, and L-R1S2 are estimated. Furthermore, the known radio resource information L-S1R1 included in the extended CTS is received.

  At time step # 3, at hops R2 to R3, the transmitting station group TG and the receiving station group RG are updated, and the transmitting station R2 relays forward the CTS control frame extended to the receiving station R3 and the listening station S2. . In the extended CTS control frame, resource information L-R1R2 and L-S1R2 obtained in time steps # 1 and # 2 are added in addition to the training signal. The receiving station R3 and the listening station S2 of the hops R2 to R3 receive the extended CTS frame from the transmitting station R2, and use the training signal therein to unknown radio resource information L-R2R3, L- Estimate R2S2. The receiving station R3 and the hearing station S2 in the hops R2 to R3 receive the known radio resource information L-R1R2, L-S1R2, and L-S1R1 included in the extended CTS.

  At time step # 4, at hops R3 to S2, the transmitting station group TG and the receiving station group RG are updated, and the CTS control frame extended to the receiving station S2 by the transmitting station R3 is relayed forward. In the extended CTS control frame, resource information L-R1R3 and L-R2R3 obtained at time steps # 2 and # 3 are added in addition to the training signal. The receiving station S2 of hops R3 to S2 receives the extended CTS frame from the transmitting station R3, and estimates unknown radio resource information L-R3S2 with the radio station R3 using the training signal therein. The receiving station S2 of hops R3 to S2 receives the known radio resource information L-R1R3 and L-R2R3 included in the extended CTS.

  Here, since the communication link S1R3 cannot communicate, the resource information L-S1R3 could not be estimated at time step # 1, or the resource information L-S1R3 is transmitted by the transmitting station R3 in order to reduce the overhead of the control frame. Do not add to the control frame to be transmitted. As described above, it is necessary to update the transmitting station group TG and the receiving station group RG of the control frame to be relayed, but the addition of the resource information may be determined according to the requirements of the system.

  As can be seen from FIG. 6, through the forward control frame relay from time steps # 1 to # 4, access reservation of the wireless medium in each wireless station participating in multihop transmission between the start station S1 and the end station S2 is performed. it can. Also, using both desired link communication and listening link communication (assuming that all listening links are communicable), one, three, six, and nine wireless stations R1, R2, R3, and S2, respectively. Resource information can be aggregated.

  Some of the radio stations R1, R2, R3, and S2 can perform resource control such as route reselection and subchannel allocation based on the aggregated resource information. In order to implement multi-hop transmission according to control information, it is necessary to notify the control information to wireless stations other than itself that participate in the multi-hop transmission.

In the following, time steps # 5 to # 8 will be described as a backward control frame relay.
At time step # 5, at hops S2 to R3, the transmitting station group TG and the receiving station group RG are updated, and the transmitting station S2 transmits the extended CTS control frame to the receiving station R3 and the listening stations R3, R2, and S1. Relay to. The extended CTS control frame includes resource control information S2-RCI (Resource Control Information). The receiving station R3 and the listening stations R2, R1, and S1 of the hops S2 to R3 receive the extended CTS frame from the transmitting station S2, and receive the resource control information S2-RCI included in the extended CTS frame.

  At time step # 6, at hops R3 to R2, the transmitting station group TG and the receiving station group RG are updated, and the CTS control frame extended by the transmitting station R3 to the receiving station R2 and the listening stations R1 and S1 is relayed backward. To do. The extended CTS control frame includes resource control information R3-RCI. The receiving station R2 and the listening stations R1 and S1 of the hops R3 to R2 receive the extended CTS frame from the transmitting station R3 and receive the resource control information R3-RCI included in the extended CTS frame.

  At time step # 7, at hops R2 to R1, the transmitting station group TG and the receiving station group RG are updated, and the CTS control frame extended by the transmitting station R2 to the receiving station R1 and the listening station S1 is relayed backward. The extended CTS control frame includes resource control information R2-RCI. The receiving station R1 listening station S1 of the hops R2 and R1 receives the extended CTS frame from the transmitting station R2, and receives the resource control information R2-RCI included in the extended CTS.

  In time step # 8, at hops R1 to S1, the transmitting station group TG and the receiving station group RG are updated, and the CTS control frame extended to the receiving station S1 by the transmitting station R1 is relayed backward. The extended CTS control frame includes resource control information R1-RCI. The receiving station S1 of hops R1 to S1 receives the extended CTS frame from the transmitting station R1, and receives the resource control information R1-RCI included in the extended CTS frame.

As can be seen from FIG. 6, the resource control information can be notified to each radio station participating in multi-hop transmission from the end station S2 to the start station S1 through the backward control frame relay from time steps # 5 to # 8. .
The resource control information R1-RCI, R2-RCI, R3-RCI, and S2-RCI are each a subset of the former and the latter.

  As can be seen from FIG. 5, if listening link communication is used, diversity combining reception processing is applied to the forward control frame and the backward control frame including the same information received by each wireless station at different time steps. it can. Therefore, the use of a listening link also helps to reduce error propagation due to multi-hop transmission.

[Embodiment 2]
This embodiment is different from the first embodiment in the following points.
First, from the viewpoint of communication broadcasting, the forward control frame relay transmitted by a certain hop transmitting station can be received by the hop receiving station at the same time that the hop receiving station can be received. Therefore, when a transmitting station of a hop transmits a forward control frame, there is a reservation function for the receiving station of the hop, and at the same time, whether or not it is reserved as a receiving station for the transmitting station of the previous hop. There is also a response [ACK (ACKnowledge)] function.

When a certain hop is reached, if the transmitting station of the hop (assuming that it is not the end station) passes the SIFS interval and does not continue to transmit a forward control frame, the transmitting station of the previous hop is determined by itself. It is determined that the reservation to the receiving station has failed.
In that case, in order to reduce the overhead, the relay station that was able to reserve at the end is terminated instead of starting the media reservation by the forward control frame relay from the beginning in order to perform multi-hop transmission from the start station to the end station. Considering the station, the forward control frame relay is terminated, and the backward control frame relay is performed from the relay station toward the start station.

When the above pre-processing is completed, multi-hop transmission with the last relay station that can be reserved from the start station and its success / failure response are performed. When they are completed, the communication right is released to the wireless communication network.
FIG. 7 shows a specific example of the above frame sequence.

According to each of the above embodiments, assuming an arbitrary number of hops, the wireless medium access reservation, the aggregation of radio resource information, and the notification of radio resource control information can be realized by a unified control frame sequence Can do.
That is, for multi-hop cooperative relay transmission having an arbitrary number of hops, wireless medium access reservation, radio resource information (that is, information in each radio communication link related to multi-hop transmission), radio resource control information ( That is, notification of information (such as an allocation pattern of radio resources in each radio station related to multi-hop transmission) can be realized through a unified frame sequence.
According to each of the above embodiments, improved communication quality such as higher system throughput and shorter transmission delay can be realized as compared with the conventional wireless communication network.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes a design that does not depart from the gist of the present invention. Needless to say, the above-described embodiment and a plurality of modifications can be combined within a range in which the contents do not conflict with each other. Further, in the above-described embodiments and modifications, the structure of each part has been specifically described, but the structure and the like can be changed in various ways within a range that satisfies the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Radio station, 11 ... Antenna, 12 ... Wireless communication part, 13 ... Communication control part, 14 ... Route selection part, 15 ... Communication right acquisition part, 16 ... Pre-processing control part, 17 ... Forward control part, 18 ... Backward control unit, 19 ... Transmission control unit

Claims (3)

In a communication method between a plurality of wireless stations participating in multi-hop transmission having an arbitrary number of hops in a wireless communication network,
A starting station for starting wireless communication obtains a communication right in the wireless communication network;
The starting station that has acquired the communication right records the listening station for each hop transmitting station in a pre-processing control frame that is processed before the multi-hop transmission;
Starting station acquires the communication right, based on the processing result of the pretreatment control frame, and record the hearing station data frame possess a step of performing the multi-hop transmission for the transmitting station for each hop,
The preprocessing control frame includes a front control frame relay and a rear control frame relay,
The starting station that acquired the communication right is
Based on the forward control frame relay, performing access reservation of the wireless medium in each wireless station participating in the multi-hop transmission, and collecting resource information of the wireless medium that has reserved access,
Based on the backward control frame relay, the resource control information based on the aggregated resource information is notified to each wireless station participating in the multi-hop transmission,
Each radio station participating in the multi-hop transmission is
After transmitting the forward control frame relay, if the forward control frame relay receiving station does not transmit the forward control frame even after a predetermined time, terminate the forward control frame relay, A communication method for performing a backward control frame relay from its own station toward the start station . The communication method according to claim 1, wherein the start station acquires a communication right in the wireless communication network based on a medium access control method. In a communication system including a plurality of wireless stations participating in multi-hop transmission having an arbitrary number of hops in a wireless communication network,
The starting station that starts wireless communication is
Obtaining a communication right in the wireless communication network;
Record the listening station for each hop transmitting station in a pre-processing control frame that is processed before the multi-hop transmission,
Based on the processing result of the pre-processing control frame, record the hearing station for the transmission station of each hop in the data frame and execute the multi-hop transmission ,
The preprocessing control frame includes a front control frame relay and a rear control frame relay,
The starting station that acquired the communication right is
Based on the forward control frame relay, performing access reservation of the wireless medium in each wireless station participating in the multi-hop transmission, and collecting resource information of the wireless medium that has reserved access,
Based on the backward control frame relay, the resource control information based on the aggregated resource information is notified to each wireless station participating in the multi-hop transmission,
Each radio station participating in the multi-hop transmission is
After transmitting the forward control frame relay, if the forward control frame relay receiving station does not transmit the forward control frame even after a predetermined time, terminate the forward control frame relay, A communication system for performing a backward control frame relay from the own station toward the start station .

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