JP7062437B2 - Wireless communication system and wireless communication method - Google Patents

Description

The present invention relates to a method for realizing wireless multi-stage relay transmission.

The standard ARIB STD-T103 established by the Association of Radio Industries and Businesses (ARIB) is used to send images of the site to the countermeasures headquarters, etc., mainly in areas where emergencies occur, such as disaster sites and incident sites. Based on the fact that the system for the realization of a 200MHz band wideband mobile radio communication system that enables transmission has been established, the system is related to a system in which the radio equipment having a base station function is portable. It is a standard (see Non-Patent Document 1).

In addition, efforts to build an ultra-big data platform, collect public medical data from countries and regions and measurement data at home, and support productivity and profit improvement while preventing cyber attacks when networking factories. Is being implemented in the "Innovative Research and Development Promotion Program ImPACT (Impacting Paradise Change Technologys Programs)".

In this case, the coverage area is limited only by the base station (hereinafter, BS) and mobile station (hereinafter, MS), which are the basic system configurations of ARIB STD-T103, and it is possible to collect data from a greater distance. There are many difficult situations. Under such circumstances, the conventional ARIB STD-T103 frequency division method (hereinafter, segment method) and the standard IEEE802.16j, which is the basis of ARIB STD-T103, have a relay method by a wireless relay station (hereinafter, RS). However, there are many restrictions in order to cover a wide area, and there are many cases where it cannot be applied in the above-mentioned usage scene.

Standard ARIB STD-T103, "200 MHz-Band Broadband Wireless Communication Systems bestween Portable BS and MSs", Association of Radio Industries and Businesses

The following cases can be considered as assumptions of usage scenes.
As the first case, for camera video relay from a disaster site, wireless communication is performed along mountains and valleys in mountainous areas, and multiple wireless devices are used when the communication distance of the wireless device is long. It is necessary to relay at. Further, in urban areas, the communication distance is narrowed by a large shield such as a building, so that the number of wireless relay stages (hereinafter referred to as the number of hops) is required to increase accordingly.
As a second case, for so-called big data collection such as medical data and sensor data in factories, it is necessary to cover a wider area and accommodate many sensor terminals, so the number of RS hops under BS will increase. And it will be necessary to increase the number of branches.
In such a usage scene, when considering the application of the above-mentioned segment method or the IEEE802.16j relay method, there are some restrictions that make it unusable.

Next, a comparison between the conventional non-relaying method of ARIB STD-T103 and the conventional relay method will be described.
The difference in the method for realizing wireless relay is the most important part of the wireless frame configuration, which is a constraint. Therefore, the difference in the wireless frame configuration will be described.
In ARIB STD-T103, the duplex system is TDD (Time Division Duplex) regardless of the presence or absence of relay, and BS is DL subframe transmission, UL subframe reception, MS is DL subframe reception, UL subframe transmission. It has become.

In the radio frame configuration of FIGS. 1 and 2, the vertical axis direction represents the frequency direction and the horizontal axis direction represents the time direction. The left side is the downlink signal for transmission from the BS to the MS, and the right side is the transmission from the MS to the BS. It is an upstream signal. Since it is a TDD system, TTG (Transmit / receive Transition Gap) and RTG (Receive / response Transition Gap) exist, respectively, for the purpose of avoiding the overlap of the downlink signal and the uplink signal.

Here, it is assumed that one opposite wireless device of BS and MS is wirelessly connected to each other and wireless communication is possible. In the present specification, such a connection form when two or more wireless devices maintain a wireless connection is referred to as a network topology. Furthermore, it may be called a network topology including not only a wireless network but also a connection form with a wired network.
In addition, the number of wireless multi-stage relays during wireless multi-stage relay is called the number of hops, and the number of hops is calculated by assuming that the first wireless link is one hop and adding 1 to each of the second and subsequent stages. do.

In the conventional network topology in which BS and MS are configured as one facing each other without wireless relay, the following wireless communication is performed.
Wireless communication from the BS to the MS is transmitted and received as a downlink signal.
Wireless communication from the MS to the BS is transmitted and received as an uplink signal.

Next, the conventional relay method will be described. The relay method includes a segment method and an IEEE802.16j relay method.
In the segment method, which is the first relay method, the radio frequency channels of the downlink signal area (hereinafter referred to as DL subframe) and the uplink signal area (UL subframe) are divided into three, and each of BS and MS is divided into 1. By using the 3/3 radio frequency channel, it is a method that enables wireless multi-stage relay up to 3 hops. Explaining with reference to FIG. 1, the segments divided into three are called segment 0, segment 1, and segment 2, respectively, and each segment is used as follows.

The upper part of FIG. 1 shows the radio frame configuration of segment 0, and all the time axis directions are used, but only the upper part of the three divisions is used in the frequency direction.
The middle part of FIG. 1 shows the radio frame configuration of segment 1, and all the time axis directions are used, but only the middle part of the three divisions is used in the frequency direction.
The lower part of FIG. 1 shows the radio frame configuration of segment 2, and all the time axis directions are used, but only the lower part of the three divisions is used in the frequency direction.

FIG. 3 shows a network topology of three-stage wireless relay by a segment method.
The wireless communication from BS1 to MS1 is transmitted and received as a downlink signal at DL_0 of FIG. 3 corresponding to DL_0 of FIG.
The wireless communication from BS2 to MS2 is transmitted and received as a downlink signal at DL_1 of FIG. 3 corresponding to DL_1 of FIG.
The wireless communication from the BS3 to the MS3 is transmitted and received as a downlink signal at the DL_2 of FIG. 3 corresponding to the DL_2 of FIG.

As another feature of the segment method, two wireless devices are required at the base for wireless multi-stage relay as shown in FIG. Then, the wireless devices are connected to each other with a wired cable. As described above, the segment method has a demerit that it is necessary to prepare two wireless devices at the base for wireless relay.

The second relay method, the IEEE802.16j relay method, is a method in which the conventional radio frame is time-divided into the first hop and the second hop. Basically, it is a method of up to 2 hops, but communication of 3 hops or more is also allowed in the method only when the radio signals of the RSs at the branch destination do not interfere with each other. However, in the above-mentioned usage scene, it is almost impossible to completely control the interference condition of the branch destination. Therefore, especially in terms of comparison with the conventional technique, the method is practically up to 2 hops. explain.
Explaining the wireless frame configuration of the IEEE802.16j relay system with reference to FIG. 2, the DL subframe and the UL subframe are divided in the time axis direction, and TTG2 and RTG2 are added for the same purpose as the conventional TTG and RTG. It has become.

FIG. 4 shows a network topology of two-stage wireless relay by the IEEE802.16j relay method.
The wireless communication from the BS to the RS is transmitted and received as a downlink signal at the DL_B of FIG. 4 corresponding to the DL_B of FIG.
The wireless communication from the RS to the MS is transmitted and received as a downlink signal by the DL_R of FIG. 4 corresponding to the DL_R of FIG.
The wireless communication from RS to BS is transmitted and received as an uplink signal in UL_R of FIG. 4 corresponding to UL_R of FIG.
The wireless communication from the MS to the RS is transmitted and received as an uplink signal in the UL_M of FIG. 4 corresponding to the UL_M of FIG.

In the IEEE802.16j relay method, there is a restriction from the part of dividing into two in the time axis direction to a maximum of two hops.
Further, since the DL subframe and the UL subframe are each divided into two, the GAP time for preventing the overlap of the radio signals is set even during the division, and the GAP time for that time is the same as that of the conventional method. Compared to this, there is a demerit that the wireless transmission rate is lowered.

Further, in the conventional ARIB STD-T103, the ratio of the DL subframe and the UL subframe (hereinafter referred to as the TDD ratio) can be selected from three types depending on the usage scene.
FIG. 5 shows three types of TDD ratios (upper, middle, and lower).
The upper part of FIG. 5 shows the uplink signal priority allocation method, and is a TDD ratio suitable for transmitting a camera image from the MS to the BS from the above-mentioned disaster site.
The middle part of FIG. 5 shows an allocation method of equal uplink and downlink, and is a TDD ratio suitable for a case where it is desired that the transmission capacities in the uplink direction and the downlink direction are the same as in the above-mentioned segment method. ..
The lower part of FIG. 5 shows the downlink signal priority allocation method, and is a TDD ratio suitable for cases where downloads are frequently used, for example, when a plurality of PCs are connected to the MS side to browse the Internet WEB. ..

A case where the application of the IEEE802.16j relay method is assumed for such a TDD ratio will be described with reference to FIG.
As can be easily seen from FIG. 6, when the upper DL subframe and the lower UL subframe are divided into two and the GAP time is inserted as in TTG2, the bandwidth that can be used for communication becomes very small. Will end up. For this reason, it is assumed that there will be a demerit that data in almost one direction will not flow.

As described above, in the conventional segment method and the IEEE802.16j relay method, there are restrictions on the upper limit of the number of hops, the radio transmission rate, and the interference status of the radio signal.
The present invention has been made in view of the above-mentioned conventional circumstances, and the upper limit of the number of hops during wireless relay is lifted, the decrease in wireless transmission rate during wireless relay is reduced, and the wireless devices during wireless relay are used with each other. The purpose is to avoid interference.

In order to achieve the above object, in the present invention, the wireless communication system is configured as follows.
That is, as shown in the outline of the network topology in FIG. 8, wireless multi-stage relay is realized by wirelessly connecting a base station, which is a wireless device, and a mobile station, and further connecting another mobile station to the mobile station. do. In addition, a plurality of wireless connections to the wireless device are allowed. In the example of FIG. 10, the base station (BS) is wirelessly connected to two mobile stations (RS1, RS2), RS1 is wirelessly connected to RS3 and RS4, and RS2 is wirelessly connected to RS5 and RS6. It shows that it is.

For the wireless frame, a method in which the downlink signal and the uplink signal are repeated in the wireless frame cycle is used as in the conventional method, but the downlink signal area is used for data transmission from the BS in FIG. 8 to the RS3, RS4, RS5, and RS6 sides. On the contrary, in the data transmission from the RS3, RS4, RS5, RS6 side to the BS side, the uplink signal region is used.

Here, since the wireless band is shared between the wireless devices in units of wireless frames, it is necessary to have a function of synchronizing the wireless frame timings of the wireless devices so that the wireless signals do not interfere with each other. This is realized by using a reference signal with a cycle of 1 second that can be acquired from the satellite positioning system and the timing adjustment value of the UL signal that can be acquired by the range function of ARIB STD-T103.

Further, in order to realize wireless communication between a plurality of wireless devices, a scheduler unit (scheduler server in FIG. 8) is provided in the system, and the wireless band requirement amount required for each wireless device to wirelessly transmit user data. Is collected in the scheduler section. The scheduler unit calculates the timing of wireless transmission / reception by each wireless device according to the collected wireless band request amount, and distributes it as wireless band allocation information to all wireless devices.

Since the wireless band requirement constantly changes due to a change in the network topology or an increase or decrease in user data, it has a function of maintaining the wireless communication system while constantly updating the notification of the wireless band requirement and the wireless band allocation information.
In the generation of wireless band allocation information, as described above, while satisfying the wireless band requirements of all wireless devices for the purpose of responding to the wireless band requirements that change over time and shortening the transmission delay time of user data. A wireless band allocation method that shortens the transmission / reception interval of each wireless device as much as possible is realized.

In addition, each RS is connected to the network, such as when multiple RSs are sequentially connected to the network over time and the scale of the network topology increases, or when RSs are deleted from the network as needed. It is assumed that maintaining a wireless connection with the connection destination RS at that time is not always the optimum form for maximizing the performance of the entire network.

Therefore, each wireless device has a means for sensing the wireless signal, senses the wireless signal of another wireless device that is always around during communication, and sends the sensing result to the scheduler unit in the same manner as the wireless band request amount. Notice.
Then, the scheduler unit calculates the optimum form of the network topology based on the collected sensing results, and notifies each wireless device of the necessary instructions for disconnecting and reconnecting the wireless connections between the wireless devices, thereby transmitting the network. Achieve topology optimization.

In addition, the scheduler unit grasps the interference status of wireless signals between wireless devices based on the collected sensing results, and allocates the same wireless frame as a wireless band to wireless devices that do not interfere with each other. In this way, by having wireless devices that do not interfere with each other perform wireless transmission / reception in the same wireless frame, it is possible to increase the transmission capacity of the entire system and realize the effect of shortening the wireless transmission delay. Become.

The present invention has a function of collecting wireless band requests from each wireless device, a function of calculating and distributing wireless band allocation information according to the wireless band request, a function of sensing transmission signals from each wireless device, and a network topology for switching wireless connection destinations. By having a switching function, it is theoretically possible to perform wireless multi-stage relay in a wide coverage area without restrictions on the number of hops. In addition, by configuring the relay device with one wireless device, it is possible to suppress the increase in the number of devices when the coverage area is expanded, and by not dividing the wireless frame, it is possible to suppress the decrease in the wireless transmission rate, and the data transmission capacity of each wireless device. It is possible to allocate the wireless band according to the fluctuation of the system scale.

It is a figure which shows the example of the wireless frame configuration (segment system) of the conventional wireless relay system. It is a figure which shows the example of the radio frame configuration (IEEE802.16j system) of the conventional wireless relay system. It is a figure which shows the example of the network topology (segment system) of the conventional wireless relay system. It is a figure which shows the example of the network topology (IEEE802.16j system) of the conventional wireless relay system. It is a figure which shows the example of the radio frame configuration (without the conventional radio relay) for each TDD ratio. It is a figure which shows the example of the radio frame configuration for each TDD ratio (there is a conventional radio relay, and the IEEE802.16j system). It is a figure which shows the example of the radio frame configuration (details) of a conventional system. It is a figure which shows the outline of the network topology of the wireless relay system which concerns on this invention. It is a figure which shows the example of the network topology (no branch, 3 hops). It is a figure which shows the example of the radio band allocation (no branch, 3 hops). It is a figure which shows the example of the radio band allocation (2 branches, maximum 2 hops). It is a figure which shows the example of the radio band allocation (communication with a plurality of wireless devices in one frame). It is a figure which shows the example of the radio band allocation (operation of each radio device). It is a figure which shows the example of the relationship between 1PPS signal and a radio frame. It is a figure which shows the example of the delay time of the UL signal of the conventional method. It is a figure which shows the example of the delay time adjustment of a UL signal by the range function of the conventional method. It is a figure which shows the example of delay time adjustment of UL signal when the satellite positioning system of this invention is used. It is a figure which shows the example of the system synchronization and the delay time adjustment of a UL signal when the satellite positioning system of this invention is not used. It is a figure which shows the example of the collection method of a radio band request. It is a figure which shows the example of the radio band allocation which took the network topology with a camera as an example. It is a figure which shows the example of the radio band allocation (minimization of a global cycle). It is a figure which shows the example of the radio band allocation (global cycle shortening). It is a figure which shows the example of the number of radio frames (from terminal RS to BS) applied to wireless multi-stage relay. It is a figure which shows the example of the number of radio frames (from BS to terminal RS) applied to a wireless multi-stage relay. It is a figure which shows the example of the radio band allocation before optimization. It is a figure which shows the example of the radio band allocation after optimization. It is a figure which shows the example of the global cycle which repeats in a network cycle. It is a figure which shows the example of the radio frame timing which performs the sensing operation. It is a figure which shows the example of the network topology before optimization. It is a figure which shows the example of the radio band allocation before optimization. It is a figure which shows the example of the network topology after optimization. It is a figure which shows the example of the radio band allocation after optimization. It is a figure which shows the example of the wireless transmission signal reach range of each wireless device. It is a figure which shows the example of the sensing result of each wireless device. It is a figure which shows the example of the radio band allocation before resource reuse. It is a figure which shows the example of the radio band allocation after resource reuse.

For embodiments of various methods that are important for multi-stage relay of wireless communication, wireless frame configuration and radio band allocation, system synchronization and transmission delay adjustment when linked with a satellite positioning system, and system synchronization when not linked with a satellite positioning system. The explanation will be given from the viewpoints of transmission delay adjustment, band request and band allocation information notification, and sensing function.

[About wireless frame configuration]
A conventional wireless frame configuration will be described with reference to FIG. 7.
As described above, the radio frame cycle is the TDD repetition cycle, and there are DL subframes and UL subframes, and TTG and RTG exist between them.
The DL subframe has a preamble, FCH, MAP information, and a DL data burst area, and the UL subframe has a rangening area and a UL data burst area.

The preamble is a signal used by the MS to synchronize the radio characteristics (timing, gain, frequency, phase, etc.) of the BS radio transmission signal.
The FCH (Flame Control Header) is data such as the radio modulation method and size of the MAP information that follow.
The MAP information is information indicating an identifier of a device that wirelessly transmits a downlink signal, a wireless frame number, data arrangement in a DL subframe, and the like.
The DL data burst is an area for transmitting and receiving control data and user data necessary for link maintenance.
The range area is an area in which the MS transmits / receives a signal for detecting the radio characteristics (timing, gain, frequency, etc.) of the uplink signal on the BS side.
The UL data burst is an area for transmitting and receiving control data and user data necessary for link maintenance.

[Terminology]
The terms used to describe the wireless multi-stage relay will be described using the network topology of the wireless multi-stage relay of FIG.
In FIG. 8, the BS is connected to a plurality of RSs, and the scheduler server managed when a new RS connects to the RS under the BS is connected to the BS via the Internet. Further, a line monitoring server or the like that performs maintenance of the entire network is connected via the Internet.

First, to explain the wireless link, FIG. 8 shows a lightning bolt line as a symbol between the BS and each RS, which indicates that a wireless connection is made between the devices, and this wireless connection is provided. The connection is called a wireless link.
Next, the upper RS will be described as a wireless device that is wirelessly connected on the side close to the BS. For example, the upper RS of RS1 is BS, and the upper RS of RS5 is RS2.
Next, the lower RS will be described as a wireless device that is wirelessly connected on the side far from the BS. For example, the lower RSs of RS2 are RS5 and RS6, and the lower RSs of RS4 do not exist.
Next, the terminal RS will be described as an RS having no lower RS. In the example of FIG. 8, RS3, RS4, RS5, and RS6 are terminal RSs.
Next, when the branch connection is described, BS, RS1 and RS2 are each connected to a plurality of lower RSs, and the state in which a plurality of lower RSs are connected in this way is called branching, and the lower RS is 1. The connection state of only the unit is called no branch.

[About the wireless frame of the present invention]
FIG. 9 shows a network topology (no branching, 3 hops) in which four wireless devices are connected without branching. An example of the wireless frame configuration of each wireless device in this case will be described with reference to FIG. FIG. 10 shows that the radio frames are continuous for three frames, and the radio frame numbers (hereinafter referred to as FN (Frame Number)) = N, N + 1, N + 2.

FN = N is a wireless frame in which only BS and RS1 perform wireless communication, and in the connection between BS and RS1, since BS is the upper RS and RS1 is the lower RS, the BS performs wireless transmission in the DL subframe. , RS1 performs wireless transmission in UL subframe.
FN = N + 1 is a wireless frame in which only RS1 and RS2 perform wireless communication, and according to the relationship between the upper ERS and the lower RS, the same wireless communication as in the case of FN = N is performed. The same applies to FN = N + 2.

In this way, an individual wireless frame is assigned to each wireless link, and each wireless link wirelessly transmits in a DL subframe or a UL subframe according to the relationship between the upper RS and the lower RS. That is, if the number of wireless frames is one, it means that one hop of wireless relay can be performed, and when wirelessly relaying from the BS in the terminal RS direction, wireless transmission / reception is performed in the DL subframe of each wireless link. In the case of wireless relay from the terminal RS in the BS direction, wireless transmission / reception is performed in the UL subframe of each wireless link.
In FIG. 10, the number of wireless frames used by each wireless link is one frame, but the number of wireless frames used will be described in the wireless band allocation method described later.

Next, a wireless frame configuration in the case of a network topology in which a branch exists in the wireless connection will be described. Here, it is assumed that the wireless network configuration under the BS has the same network topology (two branches, two hops) as in FIG. An example of the wireless frame configuration of each wireless device in this case will be described with reference to FIG. FIG. 11 shows a case where one wireless frame is assigned to each wireless link, as in FIG. 10 described above.

FN = N is a wireless frame in which only BS and RS1 perform wireless communication.
FN = N + 1 is a wireless frame in which only BS and RS2 communicate wirelessly.
FN = N + 2 is a wireless frame in which only RS1 and RS3 communicate wirelessly.
FN = N + 3 is a wireless frame in which only RS1 and RS4 communicate wirelessly.
FN = N + 4 is a wireless frame in which only RS2 and RS5 communicate wirelessly.
FN = N + 5 is a wireless frame in which only RS2 and RS6 communicate wirelessly.
In both cases, the upper RS transmits in the DL subframe, and the lower RS transmits in the UL subframe.

Which wireless link is assigned to which wireless frame depends on the network topology, the application at the time of data transmission, and the communication protocol, and it is considered that the optimum allocation exists under these various conditions. There are no restrictions on the determination method of assigning which radio link to which radio frame.

A radio frame configuration as an advanced form of FIG. 11 will be described with reference to FIG. FIG. 11 shows a method of allocating one wireless frame to a wireless link, but FIG. 12 shows a DL subframe or a UL subframe with one wireless frame for a common upper RS and a plurality of lower RSs. The method of dividing and allocating is shown. More specifically, DL subframes and UL subframes are divided and assigned in the frequency direction.
According to this advanced radio frame configuration, a certain upper RS can communicate with a plurality of lower RSs in one radio frame, and as a result, the repetition cycle of the radio frame assigned to all the radio devices is set. Can be shortened.

By using the wireless frame configuration as described above, the restriction on the number of hops of the wireless multi-stage relay that existed in the conventional segment method and the IEEE802.16j relay method is removed, and the GAP such as the IEEE802.16j relay method is eliminated. It is possible to avoid a decrease in the transmission rate due to additional time.

[About system synchronization when linking with satellite positioning system]
First, system synchronization will be described. Although the wireless frame configuration in the case of the network topology of FIG. 9 has been described with reference to FIG. 10, the operation of each wireless device will be described with reference to FIG. Regarding the allocation to the wireless link, FN = N, N + 1, N + 2 are the same as in FIG. 10, and FN = N + 3, N + 4, N + 5 indicate that the same allocation is repeated, and further is repeated. ..

Explaining mainly the operation of the BS, FN = N and N + 3 indicate that DL transmission and UL reception are performed with RS1, and wireless transmission / reception is not performed with other wireless frames.
Explaining mainly the operation of RS1, FN = N + 1 and N + 4 indicate that DL transmission and UL reception are performed with RS2, and wireless transmission / reception is not performed with other wireless frames. The same applies to RS2 and RS3.

In this way, since different wireless transmissions and receptions are performed in the wireless frame cycle, if the wireless frame timing of each wireless device is deviated, the wireless signals overlap and interfere with each other. Therefore, the operation of synchronizing the wireless frame timing is a very important function in the wireless multi-stage relay, and this operation is called system synchronization.

As an explanation of system synchronization for linking with a satellite positioning system, first, a method in which each wireless device receives a positioning signal from a satellite will be described. Here, as in FIG. 9, a network topology in which three RSs are connected under the BS without branching will be described as an example.
First, the positioning signal wirelessly transmitted from the transmitting antenna of the satellite is received by the positioning signal receiving antenna provided in each wireless device. Each wireless device has a built-in positioning signal receiver, and the positioning signal receiver extracts a reference signal (hereinafter referred to as 1PPS (pulse per second) signal) having a cycle of 1 second from the positioning signal. Then, all the wireless devices synchronize the 1PPS signal with the transmission start timing of the wireless frame, so that all the wireless devices can synchronize the wireless frame.

Next, a method of synchronizing the 1PPS signal and the wireless frame will be described with reference to FIG.
The radio frame period of ARIB STD-T103 is 10 milliseconds (hereinafter referred to as msec), and 100 radio frames are collected in one second. Therefore, the timing of the 100-frame cycle is synchronized with the timing of the 1PPS signal, such as FN = N to N + 99 and N + 100 to N + 199. As a result, each wireless device does not need to share information up to the wireless frame number (FN), and the 1PPS signal and the wireless frame can be synchronized.

[About UL transmission delay adjustment function]
Next, the delay adjustment function of UL transmission, which is a function required for the system synchronization method that does not cooperate with the satellite positioning system, will be described.
Even if the wireless transmission start timing of the DL subframe has been established in synchronization with all wireless devices by the system synchronization as described above, the time for the signal of the DL subframe to reach the lower RS is the time for the upper RS and the lower RS. It varies depending on the distance of the radio propagation path and the multipath environment. The conventional method is provided with a ranging function for adjusting the transmission timing so that the radio signals do not overlap according to the radio propagation path environment. In the following, a method for realizing a system synchronization of wireless multi-stage relay and a delay adjustment function of UL transmission by using a part of the conventional range function will be described.

[Conventional ranging function]
In order to facilitate the description of the method of the present invention and the comparison with the conventional method, first, the conventional rangening function will be described. The range function in the conventional method without wireless relay is used for adjusting the UL transmission function, and does not have a function for realizing system synchronization.
Explaining with reference to FIG. 15, even if the MS receives the DL signal from the BS, it cannot recognize the Delay DL which is the delay time until the radio signal arrives from the BS to the MS. Therefore, the delay time in the first UL transmission. Do not adjust. The state in which the delay time is not adjusted at this time means that the UL transmission is started after the TTG time has elapsed after the DL reception. The UL signal transmitted from the MS reaches the BS side after the delay time of the DayUL. Since the propagation path environment between the BS and MS antennas is communicated by TDD, it can be regarded as almost the same, and since the DayUL is the delay time for the round trip between the BS and the MS, the DayUL is twice as long as the DayDL. be.

After receiving the UL signal from the MS, the BS measures the Delivery UL and notifies the MS by wireless communication. The MS that has received this Delay UL adjusts the transmission start timing of the UL signal by extending the length of the TTG.
Explaining with reference to FIG. 16, the MS receives the DL signal delayed by the Delay DL as in FIG. 15. After that, according to the value of DelayUL notified from the BS, the value of TTG is changed to TTG-DelayUL, and UL transmission is started. By such a cooperative operation of the BS and the MS, the UL signal transmitted from the MS is adjusted to match the timing in which the BS is waiting.

However, since this series of UL delay adjustment operations does not always complete the adjustment at one time, the timing-adjusted UL transmission from the MS and the notification of the deviation amount from the BS are repeated to finally complete the adjustment. It is possible to adjust the start timing of the UL transmission of the MS so that the UL signal can be received within the allowable range of the reference timing expected by the BS. In addition, the propagation path environment between BS and MS may change due to changes in the positional relationship between BS and MS during communication and changes in the surrounding environment. Therefore, the above UL delay adjustment operation is periodically performed even during communication. There is a function that keeps updating the delay time of UL transmission to the optimized state by repeating the above.

[About the delay adjustment function of UL transmission when using the satellite positioning system]
In the present invention, by using the satellite positioning system, the delay adjustment of UL transmission is performed without using the notification of the amount of deviation of the BS timing described above. Hereinafter, this method will be described.
First, by using the satellite positioning system, it is a prerequisite that the system synchronization of each wireless device has been established in advance. In this case, it is possible for the lower RS to measure how long the DL signal from the upper RS is delayed and received on the lower RS side. That is, since the MS can specify the start timing of the DL transmission, it is possible to independently measure the Day DL, which is the delay time of the DL signal. Further, as described above, in the TDD method, the propagation paths in the DL direction and the UL direction can be regarded as the same, so that the lower RS can reflect the Day DL, which is the delay time of the DL signal, in the UL transmission timing. That is, as shown in FIG. 17, the MS may change the value of TTG to TTG- (2 × DelayDL) and start UL transmission.

Therefore, unlike the conventional method, it is not necessary for the BS to notify the MS of the Wireless UL, which is the delay time of the UL signal. Therefore, even if the UL transmission start timing is adjusted each time each MS receives the DL signal, the data is obtained. No load is applied to the wireless band for communication. In addition, the time required to adjust the start timing of UL transmission is shortened within the same frame.

[About system synchronization and delay adjustment function of UL transmission when satellite positioning system is not used]
When the satellite positioning system is not used, of course, there is no input of the 1PPS reference signal from the receiver of the satellite positioning system, so it is necessary to propagate the timing to all RSs based on the BS radio frame timing. For that purpose, DelayUL, which is the amount of timing deviation notified from the BS, which is used in the conventional rangening function, is required. This method will be described with reference to FIG. In addition, in FIG. 18, the portions of FN = N and FN = N + 1 in FIG. 13 are extracted and shown.

Since RS1 as a lower RS does not synchronize the system based on the 1PPS signal transmitted from the receiver of the satellite positioning system, even if the DL signal is received from the BS, the Delay DL, which is the delay time of the DL signal, is measured. I can't. Therefore, as in the conventional method, the RS1 transmits the UL signal to the BS in the first UL transmission, that is, in the radio frame of FN = N, without performing timing adjustment.

The BS, which is the upper RS, measures the Delay UL, which is the amount of deviation in the reception timing of the UL signal, and notifies the lower RS, RS1. Here, the DayUL acquired by RS1 is a value obtained by totaling the delay amount of the DL signal and the delay amount of the UL signal, and as described above, the delay amounts of both can be regarded as substantially the same. Can be regarded as half the value of. That is, by acquiring the DayUL, the DayDL can also be acquired.

In the radio frame of FN = N + 1, the lower RS1 is adjusted in the direction of advancing the deviation amount notified from the upper RS by half from the FramePeriodRx which is the reception timing at the beginning of the DL subframe when the DL is received from the upper RS. Based on the FramePeriodTx, the DL signal can be transmitted to the lower RS of RS1 at the timing synchronized with the start timing of the DL transmission of the BS.

The UL transmission delay adjustment of each device adjusts the amount of UL transmission timing deviation by adjusting with TTG-DelayUL for TTG in FramePeriodRX according to the DeliveryUL from the upper RS, as in the conventional method. It can be realized by.
In this way, each device in the network can perform system synchronization in which the delay time of the UL signal transmission timing with respect to the BS is adjusted and the start timing of DL transmission to the lower RS is adjusted at the same time.

[About wireless band request and wireless band allocation method]
In the conventional ARIB STD-T103, the MS connected to the BS notifies the BS of the radio band request amount. The BS notifies the MS of the radio band allocation information by the MAP information in consideration of the requested amount. Notification of radio band request from MS is performed irregularly, and MAP information from BS is always transmitted in DL subframe, but the allocation amount of radio band is left to the discretion of BS, and the requested band amount. Does not have to be assigned to ensure satisfaction.

In the method of the present invention, as described above, since the wireless band is allocated to all wireless devices in units of wireless frames, it is necessary to consider the wireless band required by all RSs in order to calculate the allocated information. In addition, the calculated radio band allocation information must be shared by all wireless devices and operate so as not to interfere with each other's wireless communication.

First, a method of collecting radio band requests from all wireless devices in order to calculate radio band allocation information will be described with reference to FIG. 19, and then a method of distributing radio band allocation information will be described.
FIG. 19 assumes a network topology in which an Internet to which a BS is connected and a scheduler unit connected to the Internet are added to the connection configuration of the wireless device of FIG.

The radio band request of each radio device is collected in the functional unit that performs the calculation processing of the radio allocation band. The functional unit is referred to as a scheduler unit (or scheduler server) in the present specification. The scheduler unit has a function of collecting radio band request information from each radio device and distributing the calculated radio band allocation information to all RSs. If this function is feasible, there is no problem where the scheduler section is placed on the system. For example, considering the efficiency of distributing the above-mentioned radio band allocation information to all wireless devices, it is considered effective to install the scheduler unit side by side with the BS, built-in BS, or on the cloud side. In the following description, a configuration in which the scheduler unit is installed on the cloud side (that is, the configuration shown in the upper part of FIG. 19) will be described as an example.

As a method of transmitting the band request amount from each wireless device to the scheduler, there are three types of FIGS. 19 (a), (b), and (c).
In the method of FIG. 19A, each wireless device sets the amount of data to be wirelessly transmitted to the upper RS or lower RS as the wireless band request amount, and notifies the scheduler unit via wireless multi-stage relay.
In the method of FIG. 19B, the higher RS receives the radio band request amount notified from the lower RS side, combines the radio band request amount of the own RS with the radio band request amount of the own RS, and further notifies the upper RS. In this method, it is possible to match the arrival timing of the information of the radio band request amount notified from each wireless device to the scheduler unit.
In the method of FIG. 19C, the higher RS receives the radio band request amount notified from the lower RS side, totals the radio band request amount of the own RS, and further notifies the upper RS. In this method, the radio band allocation information distributed to all wireless devices can be reduced, and the load on the entire network can be suppressed.

Next, the calculation of the radio band allocation information of the scheduler unit will be described with reference to FIG.
FIG. 20 shows a network in which an Internet to which a BS is connected, a scheduler unit and a video monitor unit connected to the Internet, and a camera are connected to each wireless device are added to the connection configuration of the wireless device of FIG. Assuming a topology. The purpose of this network is to transmit the video from the camera connected to each wireless device to the video monitor unit.

The scheduler unit calculates the radio band allocation information for each radio device according to the radio band requests from all RSs. For the sake of simplicity, the amount of video transmission from each camera will be described as uniform.
The video data of the camera 4 connected to the RS3 is UL-transmitted in the order of RS3, RS2, RS1 in each wireless frame of wireless frame number (FN) = N, N + 2, N + 5, and is transmitted from the BS only via the wired connection system. Is transmitted to the video monitor unit.
The video data of the camera 3 connected to RS2 is UL transmitted in the order of each wireless frame RS2 and RS1 of wireless frame number (FN) = N + 1, N + 4, and the video monitor unit is transmitted from the BS only via the wired connection system. Is transmitted to.
The video data of the camera 2 connected to the RS1 is UL transmitted from the RS1 in a wireless frame with a wireless frame number (FN) = N + 3, and is transmitted from the BS to the video monitor unit via only the wired connection system.
The video data of the camera 1 connected to the BS is transmitted to the video monitor unit only via the wired connection system without being wirelessly transmitted.

Considering such a method of data relay transmission, each RS has its own bandwidth requirement and all of its subordinates in order to transmit the data of all the lower RS groups connected under its own RS to the upper RS. The radio band requirement of RS is required.
In other words, the closer the RS is to the BS, the more the radio band for transmitting the data from the subordinate RS is required, so if the radio band allocation is not calculated in consideration of that amount, all the data from the terminal RS will be required. Can no longer reach the BS. This tendency is the same for the band allocation from the BS side to the terminal RS side, in which the flow of data transmission is reversed.

In addition, the scheduler unit updates and distributes the radio bandwidth allocation information according to the bandwidth request from each RS that changes according to the entry or exit of a new RS to the network system or the increase or decrease in the traffic load during communication. You need to keep doing it.
Furthermore, the notification cycle of bandwidth request information and the calculation cycle of bandwidth allocation information can be set by the operator as system parameters, and can be dynamically changed according to the network scale, the size of the bandwidth request, and the amount of change. Is.

[About the method of allocating wireless frames to each wireless device]
The following two points can be mentioned as important points in the method of the present invention.
-Migrate to new radio band allocation information without interruption in the entire system.
-Consider shortening the transmission delay in wireless relay.
In the present invention, the above two points are realized by setting two cycles, "global cycle" and "network cycle".

The global cycle is the minimum number of radio frames required when the radio frame is set as the minimum unit and the radio band is allocated to each radio device based on the radio band requirement collected from all the radio devices. The cycle generated by repeating this global cycle a plurality of times is referred to as a network cycle.

The global cycle can generate a very long global cycle by increasing or decreasing the number of radio frames allocated to each wireless device at the same ratio. However, as described above, since it is necessary to constantly update the wireless band allocation information according to the network environment, if the continuous occupation period of the wireless band for each wireless device is too long, the wireless transmission delay of the entire system increases. Resulting in.
Therefore, in the present invention, a cycle that can satisfy the band requirement of all wireless devices and can minimize the allocation amount of the radio band to the wireless device having the largest band requirement is defined as a global cycle. This portion will be described with reference to FIG.

Pattern 1 in FIG. 21 expresses the same result as the radio band allocation in FIG. 20 in a form in which the DL subframe and the UL subframe are not separated. In the case of pattern 1, the radio frame numbers (FN) = N to N + 5 represent the global cycle, and FN = N + 6 to N + 11 represent the next global cycle.
In pattern 2 of FIG. 21, the number of continuous band allocation wireless frames for each wireless device is doubled, the global cycle is also doubled, and the wireless frame number (FN) from N to N + 11 is the global cycle. It has become.

When each of the global cycles of pattern 1 and pattern 2 is repeated in a long cycle, the amount of radio band allocated to each radio device becomes the same. However, what should be noted here is not the wireless band but the transmission cycle of each wireless device.
In the case of pattern 1, even if the RS3 has the longest transmission cycle, the period during which wireless transmission is not possible is 5 frames for wireless frames, whereas in pattern 2, the period during which wireless transmission is not possible is 10 frames for wireless frames. ing.

As described above, even if the wireless band is allocated according to the required amount of the wireless band, the waiting time until the wireless transmission may become long depending on the allocation method. Therefore, when there are a plurality of allocations satisfying the same radio bandwidth as in the present invention, it is possible to obtain the effect of shortening the transmission delay by selecting the allocation having the shortest global cycle.

Next, a radio band allocation method when the difference in the amount of radio band demand of each wireless device is large will be described with reference to FIG. 22. FIG. 22 shows a case where the ratio of the radio band demand from RS1 to BS and the radio band demand from RS2 to RS1 is 100:27.

In pattern 1, according to the ratio of the radio band request amount, the ratio of the number of radio frames as the allocated band is set to 100 frames and 27 frames, and 127 frames are set as the global cycle. In this case, since the RS2 has 100 consecutive frames that cannot be wirelessly transmitted, the wireless transmission delay may become too large to be ignored.
Pattern 2 represents repeating two types of global periods, 10 frames and 2 frames, and 10 frames and 3 frames. Even if the ratio is not completely obeyed and the band allocation is executed by rounding down the fraction, the radio device with insufficient bandwidth at that time increases the radio band requirement, so the global cycle is shortened and the radio transmission delay is shortened. It is assumed that it will be possible to operate with higher network performance by communicating with each other and complying with new bandwidth requirements.

In the present invention, in addition to the scheduling method that satisfies the band request from each wireless device as in pattern 1, it is possible to optimally adjust the band request amount and wireless delay time from each wireless device as in pattern 2. Scheduling method can be used.

Next, a method of determining the number of repetitions of the global cycle in the network cycle will be described.
First, the global cycle and the delay time of the wireless multi-stage relay will be described with reference to FIG. 23. FIG. 23 shows a case where the same network topology as in FIG. 20 and the radio band allocation in FIG. 20 is repeatedly performed.
As described above, within the global cycle, one radio device is assigned one frame or a plurality of consecutive frames for communication between the upper RS and the lower RS of the own station.

Specifically, RS1 in FIG. 23 will be described as a radio band allocation for communication with RS2 in which radio frame number (FN) = N + 1 and N + 2 are lower RSs, and FN = N + 3 to N + 5 are higher RSs. It is a radio band allocation for communication with BS.
From this, in one global cycle, only one layer of the RS group wirelessly connected in multiple stages under the BS can transmit data. That is, it means that two global cycles are required for two-stage relay, and 30 global cycles are required for 30-stage relay.

Although it differs depending on the restrictions on mounting on the wireless device, FIG. 23 assumes that when the RS transfers data, it can be transmitted after 3 frames from the reception of the data.
At FN = N in FIG. 23, RS3 is UL-transmitted to RS2, but RS2 can UL-transmit this data to RS1 at the fastest speed three frames after FN = N and the radio for RS1 and RS2. Since it is a wireless frame to which the band is allocated, FN = N + 7. The data relayed to RS1 at FN = N + 7 can be UL-transmitted to the BS at the fastest speed because of the same restrictions as described above, FN = N + 10.

As described above, the number of wireless frames required for wireless relay differs depending on the restrictions peculiar to the wireless device, and the number of global cycles required for wireless multi-stage relay also differs accordingly. The restricted time required for this wireless relay is called the wireless transfer restricted time.
The scheduler section should calculate the radio band allocation according to the wireless transfer constraint time of each device, but for the sake of simplicity, the following explanation is given with the constraint that the wireless multi-stage relay is transferred one hop in the global cycle. I do.

So far, the wireless multi-stage relay from the terminal RS to the BS direction has been described, but the same delay time occurs in the wireless multi-stage relay from the BS to the terminal RS in the opposite direction.
FIG. 24 shows a wireless multi-stage relay from the BS to RS3 of the terminal RS, and the delay time until the data received by the RS is transmitted is the same as that of FIG. 23.

With FN = N + 3, BS first DL-transmits to RS1 which is a lower RS. The data received from the BS by RS1 can be DL-transmitted to RS2 of the lower RS at the fastest speed after 3 frames from FN = N + 3, and the radio frame to which the radio bands of RS1 and RS2 are assigned is the radio frame. = N + 7. Similarly, RS2 can wirelessly relay to RS3 at FN = N + 12.
In this way, if the order of band allocation to each wireless device is different in the global cycle, the delay time will change slightly, but in the part where the minimum wireless multi-stage relay is performed for one hop in one global cycle, from the BS. There is no difference between wireless relay to the terminal RS and wireless relay from the terminal RS to the BS.

Next, a band allocation method within the global cycle for reducing the transmission delay due to relay when the number of hops for multi-stage relay is large will be described. Here, a case where the maximum number of hops from the BS to the terminal RS is 6 hops in a network topology without branching will be described as an example.
FIG. 25 shows the radio band allocation when the wireless band requirements required for wireless communication between the BS and each RS are equal, and the allocation increases the wireless band allocation amount to the wireless link on the side closer to the BS. It has become. In this case, the global period is 21 frames.

The following two points can be mentioned as problems of the radio band allocation result shown in FIG. 25.
-The delay time for wireless multi-stage relay due to the wireless relay constraint time increases.
-There is a bias in the delay time of the wireless multi-stage relay in the downlink direction and the uplink direction.

The first issue will be explained.
Similar to the description of FIGS. 23 and 24, when the wireless transfer constraint time is 3 frames, when the wireless frame number (FN) = N in FIG. 25, the data transmitted UL from RS6 to RS5 is transmitted to RS5 by RS5. UL cannot be transmitted to RS4 in the sections of N + 1 and N + 2, and UL is transmitted to RS4 in the next global cycle.
In the case of the network topology without branching and the radio band allocation in FIG. 25, it is possible to wirelessly relay to the BS within the global cycle except for the above cases. However, if the number of radio frames from UL reception to UL transmission of a certain wireless device is less than the wireless relay constraint time, the band must be allocated until the next global cycle for wireless relay. That is, it means that only one hop can be transferred in one global cycle.

The second issue will be explained.
In the radio band allocation of FIG. 25, considering the radio multi-stage relay from the BS to the terminal RS, as is clear from the figure, only one hop can be transferred for one global cycle. This delay time cannot be shortened even if the wireless transfer constraint time is 0 frame.

Next, a band allocation method for solving the above two problems will be described with reference to FIG. 26.
First, to give an overall explanation, the global cycle is the same as in FIG. 25, which is 21 frames, and the number of frames for allocating the radio band to each radio link in the global cycle is also the same.
The difference between FIGS. 25 and 26 is that the order of radio band allocation to each wireless device within the global cycle is changed.

Specifically, the radio band to the radio link having an even number of hops when counted from the BS is assigned to the radio frame number (FN) = N to N + 8, which is the first half of the global cycle. On the other hand, the radio band to the radio link having an odd number of hops is assigned from FN = N + 9 to N + 20.
In this way, by dividing the continuous wireless multi-stage relay into the first half and the second half of the global cycle, the wireless multi-stage relay from the BS to the terminal RS direction and the wireless multi-stage relay from the terminal RS to the BS direction, which is the opposite direction, can be performed in both directions. In both cases, it is possible to transfer two hops in one global cycle.

Next, a method of determining the number of repetitions of the global cycle in the network cycle will be described.
As described above, in the system of the present invention, as the system environment changes with time, it is necessary to change the radio band allocation information accordingly. In order to adapt the radio band allocation according to the change of the system environment, the radio band allocation is updated through the following three steps. These procedures will be described with reference to FIG. 27.

FIG. 27 shows a case where the radio band allocation of FIG. 20 is repeatedly performed in the same network topology as that of FIG. 20.
The first procedure is a procedure for collecting the radio band request amount from all the wireless devices to the scheduler unit. In FIG. 27, it corresponds to the section 1.
The second procedure is a procedure for calculating the radio band allocation information based on the radio band request amount collected in the first procedure. In FIG. 27, it corresponds to the section 2.
The third procedure is a procedure for distributing the radio band allocation information calculated in the second procedure to all wireless devices. In FIG. 27, it corresponds to the section 3.
That is, the number of repetitions of the global cycle in the network cycle is a value obtained by totaling the number of global cycles from the above-mentioned section 1 to the section 3.

[Sensing function]
The sensing function of the present invention is to find all the wireless devices to which each wireless device can be wirelessly connected, and select and reflect the optimum network topology from the combinations of all the wireless devices to which the scheduler unit can connect. It is a function to do.

The following three points can be mentioned as important points of the sensing function of the present invention.
-Operation to receive DL signals of other stations and acquire data (sensing processing)
-Notification of acquired data (hereinafter referred to as sensing data) to the scheduler section-Optimization of wireless connection form using collected sensing data

First, the operation of receiving DL signals of other stations will be described with reference to FIG. 28. FIG. 28 shows the case where the radio band allocation of FIG. 20 is performed in the same network topology as that of FIG.
As described above, each wireless device has an allocated band for communication with the upper RS of its own station and an allocated band for communication with the lower RS within the global cycle, but other stations have other stations. It means that you are communicating wirelessly. Therefore, all the wireless devices receive the DL signal transmitted by another station other than the band allocated for the own station.

Specifically described with reference to the BS of FIG. 28, communication between the BS and RS1 is performed in the section from FN = N + 3 to N + 5, and the DL signal for sensing is received from FN = N to N + 2.
The DL signal contains MAP information, and the radio device identifier is stored in the DL signal. Therefore, if the DL signal is received and the MAP information can be analyzed normally, the wireless device that transmitted the DL signal can be identified. In the present invention, the process of receiving the DL signal of another station in a wireless frame that does not allocate the wireless band to the own station and analyzing the MAP information is called a sensing process.

In the sensing process, in addition to the identifier of the wireless device, RSSI (Received Signal Strength Inspection), which is the received signal strength that can be measured when wirelessly received and decoded, and the carrier level vs. interference and noise ratio, which are indicators of wireless line quality, are used. A certain CINR (Carrier to Interference and Noise Radio) is also acquired data of the sensing process. In the present invention, data that can be acquired by sensing processing such as an identifier of a wireless device, RSSI, and CINR is referred to as sensing data.

Next, the notification to the scheduler unit of the sensing data will be described.
Similar to the above-mentioned notification of the band request information to the scheduler unit, each wireless device notifies the scheduler unit of the acquired sensing information by wireless communication in the wireless band assigned to its own station by wireless multi-stage relay.
From the relationship between the above-mentioned radio band allocation information and the global cycle, it is assumed that the DL signal of the same radio device is acquired by sensing processing. Therefore, the sensing data acquired by the DL signal from the same wireless device is combined into one, RSSI, CINR, etc. notify the average value, the maximum value and the minimum value are notified, and so on. You may aggregate and notify the sensing data that has become.

Next, the optimization of the wireless connection form using the sensing data will be described.
The following two points will be described for optimizing the wireless connection form.
・ Optimization of network topology ・ Optimization by reuse of radio band (hereinafter referred to as resource reuse)

First, the optimization of the network topology will be described.
In a wireless multi-stage relay system, after BS starts communication as a reference, RS wirelessly connects from under the BS, and the network scale is expanded while extending the number of multi-stage relays while branching multi-stage relays. It will expand. Further, the number of branches of the wireless connection may be restricted as a device or as various wireless protocols, and there may be a case where a device having a small number of multi-stage relays cannot always be connected as a higher RS of the own station.

In addition, new RSs are not always added to the terminal RSs due to changes or additions of user data collection bases, and new RSs are placed in areas where wirelessly connected RSs are densely populated. Cases also occur. In such a case, the network topology constructed by wirelessly connecting one unit at a time is not always the optimum network topology at that time.
Then, in order to review and optimize the network topology that is not in the optimum state as described above, the network topology is reconstructed using the above-mentioned sensing data to reduce the delay and increase the throughput, which are the performance of the entire network. It is the sensing function of the present invention that is intended.

Specifically, the operation of switching the connection destination of the upper RS and the lower RS of all the wireless devices is performed, and the method thereof will be described.
As described above, assuming that the scheduler unit collects sensing data from all wireless devices, how many other stations around each wireless device can analyze the MAP information of the DL signal. It is in a state where it can be grasped whether it exists. In addition to whether or not MAP analysis is possible, information on RSSI and CINR can be grasped.

In such a state, the scheduler section reviews the wireless connection destination of each RS, and if the review result differs from the current network topology, the scheduler section sends control information to the target RS. Notify new destination. The RS notified of the new connection destination switches the connection destination RS according to the control message.
In this way, by reconstructing the network topology using the sensing data aggregated during communication, it is possible to always maintain the optimum state of the entire network.

The reconstruction of the network topology will be described below.
FIG. 29 has the same wireless device arrangement as that of FIG. 18, and shows the presence / absence of wireless connection and the possibility of wireless connection with solid lines and broken lines, respectively. FIG. 30 shows the radio band allocation in the wireless connection shown by the solid line in FIG. 29.
As is clear from FIG. 29, the network topology has no branch from BS to RS2 of the terminal RS, and the global period of FIG. 30 is also in the form of sequentially allocating one frame from BS to the terminal RS. The points to be optimized here are the system capacity and delay time of the entire network.

Focusing on the terminal RS in particular, when the terminal RS communicates with the network device on the cloud side, it is necessary to relay all the wireless devices, so the allocated bandwidth of all the wireless devices and the number of wireless frames required for it are wasted. Resulting in.
In this case, if the sensing information can be collected up to the scheduler section, it can be recognized that the wireless connection can be made in the broken line portion, and the number of hops to the BS of each wireless device can be calculated. Will be changed.

FIG. 31 shows the modified network topology. FIG. 32 shows the radio band allocation in the wireless connection shown by the solid line in FIG. 31.
As shown in FIG. 31, after the network topology is changed, the upper RSs of RS2, RS4, RS5, and RS6 are switched. RS2 and RS6 have been wirelessly connected before the change, but the relationship between the upper RS and the lower RS is reversed.
By changing from FIG. 29 to the network topology of FIG. 31 in this way, the number of hops of each wireless device from the BS becomes a maximum of 2 hops, and it becomes possible to suppress the waste of wireless bandwidth and delay time due to wireless multi-stage relay. ..

Further, to explain the change in the radio band allocation from FIG. 30 to FIG. 32, the global cycle itself does not change in 6 frames, but the number of hops wirelessly relayed to each device and the BS is 2 hops at the maximum. .. The terminal RSs RS3 and RS4 can exchange data with the BS only by relaying with RS1, and the terminal RSs RS5 and RS6 can exchange data with the BS only by relaying with RS2.

Next, the optimization of resource reuse will be described.
Until now, as a method of wireless band allocation, a band allocation has been performed so as to give permission to use only one wireless link to a certain wireless frame, and other wireless devices prohibit wireless communication in that wireless frame. , We have explained the mechanism to avoid the interference of each other's wireless communication. However, depending on the positional relationship of each wireless device and the surrounding environment, there are cases where the wireless signals do not interfere with each other. Therefore, by allocating the same wireless frame to the wireless links that do not interfere with each other, the wireless band can be allocated. The function to be effectively used is the outline of resource reuse.

First, the presence / absence of interference between wireless signals of wireless devices will be described with reference to FIGS. 33 and 34. FIG. 33 shows that in the network topology without branching, the radio signals do not interfere with each other in the radio links after the third hop. Specifically, the BS transmission signal reaches RS2, but does not reach RS3, RS4, and RS5. FIG. 34 shows in a table the wireless devices detected by each wireless device in the sensing operation. List each wireless device in the leftmost column "Device type", and list one or more wireless devices in "Wireless device detected by sensing" in the right column of the table. There is.

As described above, in the case where the interference state of the radio signal is orderly as shown in FIG. 33 in the network topology without branching, the sensing result summarized in FIG. 34 is also in an easy-to-understand form. However, it is assumed that relatively complicated sensing results tend to be obtained in urban areas where moving objects such as obstacles and vehicles exist in the vicinity in a network topology with branches.

Changes in radio band allocation before and after application of resource reuse will be described with reference to FIGS. 35 and 36.
FIG. 35 shows the radio band allocation before the application of resource reuse, and the radio band is sequentially allocated frame by frame from the BS to the terminal RS RS5. The global period is 5 frames.
FIG. 36 shows the radio band allocation after the resource reuse is applied. Focusing on the changed part from FIG. 35, the radio band is allocated one frame at a time from BS to RS4, but RS4 and RS5. Radio frame numbers (FN) = N, N + 4 are assigned to the radio band for communication with. That is, FN = N and N + 4 indicate that wireless reception is performed simultaneously on the two wireless links of BS and RS1 and RS4 and RS5. As a result, the global period is 4 frames, which is 1 frame less than that in FIG. 35. As described above, shortening the global cycle improves the effect of increasing the system capacity and shortening the radio transmission delay.

As described above, in the wireless communication system of this example, the direction of wireless data transmission from the base station side to the mobile station side is the downward direction, and the direction of wireless data transmission from the mobile station side to the base station side is the upward direction. One downlink radio data transmission and one uplink radio data transmission are performed in one wireless frame. Then, the mobile station is directly wirelessly connected to the base station, or indirectly wirelessly connected to the base station via wireless relay by one or more other mobile stations operating as a relay station, and repeats the wireless frame. This is configured to perform multiple stages of wireless relay.
According to such a configuration, it is possible to efficiently perform wireless relay with a larger number of stages than the conventional segment method and the IEEE802.16j relay method.

Here, in the wireless communication system of this example, one wireless frame is shared by a plurality of wireless connections having the same number of stages of wireless relay, and the downlink wireless data transmission section and the uplink wireless data transmission section of the wireless frame are shared. It also includes a configuration in which and is divided and assigned to each wireless connection. According to such a configuration, when constructing a network topology in which a plurality of wireless devices are wirelessly connected under one wireless device, the repetition period of the wireless frame assigned to each wireless device can be shortened.

Further, in the wireless communication system of this example, it is necessary to synchronize the start timing of the wireless frame in all the wireless devices in the system. This synchronization process may be realized by each radio device synchronizing the start timing of the radio frame with the reference signal having a cycle of 1 second acquired from the satellite positioning system, or each radio device may be within the radio frame. It may be realized by adjusting the start timing of the wireless frame by using the timing adjustment value used for adjusting the transmission timing of the wireless transmission section in the upstream direction.

Further, the wireless communication system of this example further includes a scheduler unit for calculating the number of wireless frames allocated to each of the wireless devices, and includes the amount of wireless bandwidth required for each wireless device to transmit its own user data. The wireless band request amount information is notified to the scheduler unit, and the scheduler unit calculates the number of wireless frames allocated to each wireless device based on the wireless band request amount information notified from all the wireless devices in the system. The number of radio frames allocated to each radio device may be configured to be distributed to all radio devices in the system. This makes it possible to efficiently distribute wireless frames to all wireless devices in the system without competing with each other. Further, since the allocation of the wireless frame is shared by all the wireless devices, each wireless device can operate so as not to interfere with each other's wireless communication.

Here, the scheduler unit may generate an allocation pattern that minimizes the number of wireless frames allocated to each wireless device, and each wireless device may be configured to repeatedly apply this allocation pattern. Thereby, the effect of shortening the delay of wireless transmission can be obtained.

Further, each radio device receives a signal of a downlink radio transmission section in the radio frame assigned to another radio device during a period other than the radio frame assigned to itself, and is measured based on the signal. The measurement information including the wireless quality information and the identification information of the wireless device of the transmission source included in the signal may be transmitted to the scheduler unit. As a result, the information necessary for optimizing the wireless connection form in the system can be aggregated in the scheduler unit during the operation of the system.

Further, the scheduler unit calculates the optimum connection form for some or all wireless devices in the system based on the measurement information transmitted from each wireless device, and based on the calculation result, some or all of them. It may be configured to instruct the wireless device to disconnect and reconnect the wireless connection. This makes it possible to always maintain the communication performance of the system in the optimum state.

Further, even if the scheduler unit is configured to allocate a common wireless frame to a plurality of wireless connections in which the signals of the wireless frames do not interfere with each other based on the measurement information transmitted from each wireless device. good. As a result, it is possible to increase the communication capacity of the system and shorten the delay of wireless transmission.

The configuration of the system, the device, and the like according to the present invention is not necessarily limited to those shown above, and various configurations may be used.
Further, the present invention can also be provided as a method or method for executing the above-mentioned processing, a program for realizing such a method or method, a storage medium for storing the program, or the like.

The present invention can be used in a wireless communication system including a base station and a mobile station, which are wireless devices.

BS: Base station, MS: Mobile station, RS: Relay station

Claims (7)

In a wireless communication system including a base station and a mobile station, which are wireless devices,
The direction of wireless data transmission from the base station side to the mobile station side is the downlink direction.
The direction of wireless data transmission from the mobile station side to the base station side is the upward direction.
One wireless data transmission in the downlink direction and one wireless data transmission in the uplink direction are performed in one wireless frame.
The mobile station is directly wirelessly connected to the base station or indirectly wirelessly connected to the base station via wireless relay by one or more other mobile stations operating as a relay station.
By repeating the wireless frame, multiple stages of wireless relay can be performed and at the same time.
It has a scheduler unit that calculates the number of wireless frames allocated to each wireless device.
Each radio device notifies the scheduler unit of radio band request amount information including the radio band amount required for transmitting each user data.
The scheduler unit calculates the number of wireless frames allocated to each of the wireless devices based on the wireless band request amount information notified from all the wireless devices in the system, and determines the number of wireless frames allocated to each wireless device. Delivered to all wireless devices in
Each radio device receives a signal in the downlink radio transmission section in the radio frame assigned to another radio device during a period other than the radio frame assigned to itself, and the radio is measured based on the signal. Measurement information including quality information and identification information of the transmission source wireless device included in the signal is transmitted to the scheduler unit.
The scheduler unit calculates a connection form that optimizes the system capacity and delay time of the entire network for all wireless devices in the system based on the measurement information transmitted from each wireless device, and based on the calculation result. A wireless communication system comprising instructing a part or all of the wireless devices to disconnect and reconnect the wireless connection . In the wireless communication system according to claim 1,
One wireless frame is shared by a plurality of wireless connections having the same number of wireless relay stages, and the downlink wireless data transmission section and the uplink wireless data transmission section of the wireless frame are divided and assigned to each wireless connection. A wireless communication system characterized by. In the wireless communication system according to claim 1 or 2.
Each wireless device synchronizes the start timing of the wireless frame with the reference signal with a 1-second cycle acquired from the satellite positioning system, so that all the wireless devices in the system synchronize the start timing of the wireless frame. Wireless communication system. In the wireless communication system according to claim 1 or 2.
By adjusting the start timing of the wireless frame by using the timing adjustment value used by each wireless device to adjust the transmission timing of the upstream wireless transmission section in the wireless frame, all the wireless devices in the system can wirelessly operate. A wireless communication system characterized by synchronizing the start timing of frames. The wireless communication system according to any one of claims 1 to 4 .
The scheduler unit generates an allocation pattern that minimizes the number of wireless frames allocated to each wireless device.
Each wireless device is a wireless communication system characterized in that the allocation pattern is repeatedly applied. The wireless communication system according to any one of claims 1 to 5 .
The scheduler unit allocates a common wireless frame to a plurality of wireless connections in which signals of the wireless frames do not interfere with each other based on the measurement information transmitted from each wireless device. system. In a wireless communication method performed by a base station and a mobile station, which are wireless devices,
The direction of wireless data transmission from the base station side to the mobile station side is the downlink direction.
The direction of wireless data transmission from the mobile station side to the base station side is the upward direction.
One wireless data transmission in the downlink direction and one wireless data transmission in the uplink direction are performed in one wireless frame.
The mobile station is directly wirelessly connected to the base station or indirectly wirelessly connected to the base station via wireless relay by one or more other mobile stations operating as a relay station.
By repeating the wireless frame, multiple stages of wireless relay can be performed and at the same time.
Each wireless device notifies the scheduler unit that calculates the number of wireless frames allocated to each wireless device of wireless band requirement information including the wireless bandwidth required to transmit the user data.
The scheduler unit calculates the number of wireless frames allocated to each of the wireless devices based on the wireless band request amount information notified from all the wireless devices in the system, and determines the number of wireless frames allocated to each wireless device. Delivered to all wireless devices in
Each radio device receives a signal in the downlink radio transmission section in the radio frame assigned to another radio device during a period other than the radio frame assigned to itself, and the radio is measured based on the signal. Measurement information including quality information and identification information of the transmission source wireless device included in the signal is transmitted to the scheduler unit.
The scheduler unit calculates a connection form that optimizes the system capacity and delay time of the entire network for all wireless devices in the system based on the measurement information transmitted from each wireless device, and based on the calculation result. A wireless communication method comprising instructing a part or all of the wireless devices to disconnect and reconnect the wireless connection .

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