Transmission method, transmission device, and communication system

An indicator in a master AP from among a plurality of APs obtains communication quality of communication with an AP which is a communication partner. In the case where the obtained communication quality is less than a threshold, the indicator causes the plurality of APs including the master AP to perform cooperative operation to transmit data. In the case where the obtained communication quality is not less than the threshold, the indicator causes the plurality of APs including the master AP to stop the cooperative operation.

TECHNICAL FIELD

The present disclosure relates to a wireless communication technique.

BACKGROUND ART

Various frequency bandwidths are used in wireless communication. In wireless LAN, for example, IEEE 802.11g uses a frequency bandwidth of 2.4 GHz to 2.5 GHz band with a maximum transmission rate of 54 Mbps. In mobile phones, for example, LTE uses a frequency bandwidth of 2 GHz with a maximum transmission rate of 112.5 Mbps.

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

To achieve larger-capacity transmission, the introduction of wireless communication using a frequency of 6 GHz or more, for example, a frequency bandwidth called millimeter wave, is desired.

In view of this, an aspect of the present disclosure provides, for example, a transmission method used in a plurality of transmission devices that each perform wireless transmission to a reception device using a millimeter wave frequency bandwidth, the transmission method including: obtaining communication quality of communication with the reception device; causing the plurality of transmission devices to perform cooperative operation to transmit data, in the case where the communication quality obtained is less than a threshold; and stopping the cooperative operation, in the case where the communication quality obtained is not less than the threshold.

These general and specific aspects may be implemented using a system, a method, an integrated circuit, a computer program, or a recording medium, or any combination of systems, devices, methods, integrated circuits, computer programs, or recording media.

With the transmission method according to the present disclosure, wireless transmission can be performed using a frequency bandwidth of millimeter wave in a plurality of transmission devices.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

1. Underlying Knowledge Forming Basis of the Present Disclosure

As a method for realizing large-capacity transmission in a unit such as Gbps, for example, a method of introducing a wireless communication scheme that uses a frequency band such as millimeter wave is known. Radio waves in the millimeter wave frequency band have properties of high straightness and fast attenuation. It is therefore difficult to widen the cell range within which radio waves reach.

The inventors of the present disclosure find it difficult to realize a wireless communication system using radio waves in the millimeter wave frequency band and having a wide cell range. The inventors of the present disclosure accordingly propose a new transmission scheme that solves this problem and achieves wireless communication using radio waves in the millimeter wave frequency band.

The inventors of the present disclosure also acknowledge the demand to realize multicast or unicast communication using radio waves in the millimeter wave frequency band. In particular, there is a need for a scheme for accommodating many terminals in multicast. There is also a need to realize unicast simultaneously with multicast.

Unicast refers to designating a single address in a network and transmitting data to the specific destination. Multicast refers to designating a plurality of destinations and transmitting data to the destinations.

Wireless communication system100according to one embodiment of the present disclosure is described below.

Parent station110is connected to a communication device (not illustrated) directly, or indirectly via a communication line. The communication device is, for example, a broadcast device for broadcasting data or a distribution system or a server for transmitting data. The communication device transmits a control signal and data. The control signal includes unicast transmission method-related setting or multicast transmission method-related setting, and phase change method setting (described later). The communication device may include a plurality of communication devices. In this case, a first communication device may transmit the control signal, and a second communication device may transmit the data. Parent station110is, for example, connected wiredly to APs121,122,123, and124. Parent station110may be connected wirelessly to APs121,122,123, and124.

Parent station110receives the control signal and the data from the communication device. Parent station110transmits the control signal and the data to each of APs121,122,123, and124. APs121,122,123, and124wirelessly transmit the data obtained from parent station110.

Terminals131,132, . . . ,138are each a mobile phone, a smartphone, a tablet, or a personal computer (PC) that has a wireless communication function using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz.

Terminal131, for example, wirelessly receives data from AP121in the case where terminal131is located near AP121. Terminals132,133, . . . ,138each wirelessly receive data from its nearby AP, as with terminal131.

Terminal131also wirelessly transmits data. In the case where terminal131is located near AP121, AP121wirelessly receives the data from terminal131. AP121transmits the received data to parent station110.

Terminals132,133, . . . ,138each wirelessly transmit data, as with terminal131. An AP located near each terminal wirelessly receives the data from the terminal. The AP transmits the data received from the terminal, to parent station110.

Parent station110receives data from each terminal via a corresponding AP. Parent station110outputs the received data to the communication device.

AP120receives control signal214from parent station110. Control signal214includes unicast transmission method-related setting or multicast transmission method-related setting, and phase change method setting.

AP120performs unicast transmission method-related setting, based on control signal214received from parent station110. AP120also performs phase change method setting, based on control signal214. In the case where multicast transmission is set, the AP is set to use the same frequency (frequency band) as other APs.

In the case where unicast transmission is set, AP120operates reception device217. In the case where multicast transmission is set, AP120may stop the operation of reception device217.

AP120performs wireless transmission/reception using the same channel (or the same frequency (frequency band)) in the case of unicast transmission and in the case of multicast transmission. Here, AP120may divide one wireless carrier into several time slots, and use each time slot as a communication channel. Alternatively, AP120may use each of a plurality of different frequencies in the frequency bandwidth of 60 GHz, as a communication channel.

Encoder202receives data201from parent station110. Encoder202also receives control signal213from a controller included in AP120. Control signal213includes information such as encoding scheme designation, error correction scheme designation, encoding rate, and block length. Encoder202performs error correction encoding, such as convolution encoding, LDPC encoding, or turbo encoding, on data201, using the schemes designated by control signal213. Encoder202outputs encoded data203.

Mapping unit206receives interleaved data205from interleaver204. Mapping unit206also receives control signal213from the controller included in AP120. Control signal213includes modulation scheme designation. Mapping unit206performs modulation, such as quadrature phase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM), or 64 quadrature amplitude modulation (64QAM), on interleaved data205according to the modulation scheme designation included in control signal213, to generate modulated signal207(the modulation scheme is not limited to such). Mapping unit206outputs modulated signal207.

Mapping unit206may perform mapping including a phase change process.

Phase changer208receives modulated signal207from mapping unit206. Phase changer208also receives control signal214. Control signal214includes phase change method setting. Phase changer208performs phase change on modulated signal207according to the phase change method setting included in control signal214, to generate phase-changed signal209. Phase changer208outputs phase-changed signal209.

Wireless unit210receives phase-changed signal209from phase changer208. Wireless unit210also receives control signal213from the controller included in AP120. Control signal213includes designation of frequency conversion, amplification, etc. Wireless unit210performs processes such as frequency conversion and amplification on phase-changed signal209, to generate transmission signal211. Wireless unit210outputs generated transmission signal211to antenna212, using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz.

Antenna215receives signal216output from each terminal as a radio wave.

Reception device217receives signal216from antenna215using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz, and performs processes such as amplification and frequency conversion on signal216, to generate data218. Reception device217outputs data218to parent station110.

Although antennas212and215are described separately for convenience's sake, they may be the same entity.

Parent station110includes transmission data separator302, reception data separator305, and indicator308, as illustrated inFIG. 3.

Indicator308is connected to the communication device and APs121,122,123, and124.

For example, indicator308receives a control signal from the communication device. The control signal includes unicast transmission-related setting or multicast transmission-related setting, and phase change method setting. For example, the communication device includes a personal computer (PC) (or a computer, or the like), and the user of the PC inputs the control signal through the PC.

A separate control signal may be set for each AP, or the same control signal may be set for all APs.

Multicast transmission may be set for all APs, or unicast transmission may be set for all APs. Multicast transmission may be set for part of the APs, and unicast transmission for the other APs. Thus, multicast transmission-related setting and unicast-related setting may be mixed for the APs.

For a plurality of APs set for multicast, the modulated signal before phase change is the same signal. In other words, the same data is transmitted. A phase change method is then indicated to each AP.

For a plurality of APs set for unicast, the modulated signal before phase change may be the same signal or a different signal. In other words, the same data may be transmitted, or different data may be transmitted.

Indicator308outputs the received control signal to transmission data separator302, reception data separator305, and APs121,122,123, and124.

Transmission data separator302is connected to the communication device, indicator308, and APs121,122,123, and124.

Transmission data separator302receives the control signal from indicator308. Transmission data separator302outputs the received control signal to APs121,122,123, and124.

Transmission data separator302also receives data from the communication device. Transmission data separator302separates the received data into data for AP121, data for AP122, data for AP123, and data for AP124. Transmission data separator302outputs the separated data to each of APs121,122,123, and124.

Reception data separator305is connected to the communication device, indicator308, and APs121,122,123, and124.

Reception data separator305receives data from each of APs121,122,123, and124. Reception data separator305outputs the received data to the communication device.

2.4 Example of Transmitted/Received Data

An example of data transmitted/received by parent station110and APs121,122,123, and124is described below.

(1) In the Case of Setting all APs for Multicast Transmission to Transmit Data

An example of transmitted data in the case of setting all APs121,122,123, and124for multicast transmission to transmit data is described below, with reference toFIG. 4.

In the case where all APs are set for multicast, transmission data separator302, upon receiving packet401, outputs same packet401to APs121,122,123, and124. APs121,122,123, and124wirelessly output packets406,411,416, and421respectively. Packets406,411,416, and421are generated based on and correspond to same packet401.

In this case, a feature lies in that APs121,122,123, and124each perform phase change on the modulated signal (alternatively, any of APs121,122,123, and124may perform no phase change).

(The phase change method will be described in detail later.)

This has the advantages of widening the cell range within the reach of a multicast modulated signal, and reducing, by means of phase change, points at which reception is difficult due to modulated signal interference.

(2) In the Case of Setting Two APs for Multicast Transmission to Transmit Data

An example of transmitted data in the case of setting two APs121and122as multicast data transmission APs and other two APs123and124as unicast data transmission APs to transmit data is described below, with reference toFIG. 5. In this case. APs121and122transmit the same data (the modulated signal after mapping and before phase change is the same). Moreover, APs123and124transmit the same data (the modulated signal after mapping and before phase change is the same).

Packets501,503,504, and506are generated from one set of multicast data. Packets502and505are generated from one set of unicast data.

Upon receiving packet501, transmission data separator302outputs same packet501to APs121and122. APs121and122wirelessly output packets511and521respectively, in multicast transmission. Packets511and521are generated based on and correspond to same packet501.

Next, upon receiving packet502, transmission data separator302outputs same packet502to APs123and124. APs123and124wirelessly output packets531and541respectively, in unicast transmission. Packets531and541are generated based on and correspond to same packet502.

Next, upon receiving packet503, transmission data separator302outputs same packet503to APs121and122. APs121and122wirelessly output packets512and522respectively, in multicast transmission. Packets512and522are generated based on and correspond to same packet503.

Next, upon receiving packet504, transmission data separator302outputs same packet504to APs121and122. APs121and122wirelessly output packets513and523respectively, in multicast transmission. Packets513and523are generated based on and correspond to same packet504.

Next, upon receiving packet505, transmission data separator302outputs same packet505to APs123and124. APs123and124wirelessly output packets532and542respectively, in unicast transmission. Packets532and542are generated based on and correspond to same packet505.

Next, upon receiving packet506, transmission data separator302outputs same packet506to APs121and122. APs121and122wirelessly output packets514and524respectively, in multicast transmission. Packets514and524are generated based on and correspond to same packet506.

As described above, in the case of transmitting the modulated signal in unicast transmission, the packets transmitted in APs123and124are based on the same data. Here, APs123and124have the same transmission parameter. APs123and124may perform different phase changes. Alternatively, any of APs123and124may perform no phase change.

This has the advantages of widening the cell range within the reach of a unicast modulated signal, and reducing, by means of phase change, points at which reception is difficult due to modulated signal interference.

A feature lies in that APs121and122each perform phase change on the modulated signal. Alternatively any of APs121and122may perform no phase change. The phase change method will be described in detail later.

This has the advantages of widening the cell range within the reach of a multicast modulated signal, and reducing, by means of phase change, points at which reception is difficult due to modulated signal interference.

(3) In the Case of Setting Two APs for Multicast Transmission to Transmit Data

An example of transmitted data in the case of setting two APs121and122for multicast transmission to transmit data and setting other two APs123and124for unicast transmission to transmit data is described below, with reference toFIG. 6. InFIG. 6, APs123and124transmit different data, unlike inFIG. 5.

Packets601,603,604, and606are generated from one set of multicast data. Packets602,607, and609are generated from one set of unicast data. Packets605,608, and610are generated from another set of unicast data.

Upon receiving packet601, transmission data separator302outputs same packet601to APs121and122. APs121and122wirelessly output packets621and625respectively, in multicast transmission. Packets621and625are generated based on and correspond to same packet601.

Next, upon receiving packet603, transmission data separator302outputs same packet603to APs121and122. APs121and122wirelessly output packets622and626respectively, in multicast transmission. Packets622and626are generated based on and correspond to same packet603.

Next, upon receiving packet604, transmission data separator302outputs same packet604to APs121and122. APs121and122wirelessly output packets623and627respectively, in multicast transmission. Packets623and627are generated based on and correspond to same packet604.

Next, upon receiving packet606, transmission data separator302outputs same packet606to APs121and122. APs121and122wirelessly output packets624and628respectively, in multicast transmission. Packets624and628are generated based on and correspond to same packet606.

A feature lies in that APs121and122each perform phase change on the modulated signal. Alternatively, any of APs121and122may perform no phase change. The phase change method will be described in detail later.

This has the advantages of widening the cell range within the reach of a multicast modulated signal, and reducing, by means of phase change, points at which reception is difficult due to modulated signal interference.

Moreover, a flexible system in which APs123and124can perform unicast communication is realized.

There is thus the advantage of realizing a flexible system by, for example, switching the transmission state among the transmission state inFIG. 4, the transmission state inFIG. 5, and the transmission state inFIG. 6depending on time (e.g. switching depending on the terminal presence situation).

(4) In the Case of Setting Two APs for Multicast Transmission to Receive Data

An example of received data in the case of setting two APs121and122for multicast transmission and other two APs123and124for unicast transmission to receive data is described below, with reference toFIG. 7. In this case, APs121and122do not receive data (because they are multicast transmission APs). Meanwhile, APs123and124receive signals including the same data.

Reception device217in AP123receives and obtains packets711,712,713, . . . in this order. Reception device217in AP124receives and obtains packets721,722,723, . . . in this order. Suppose one packet between packets712and713received by reception device217in AP123is not obtained. Also suppose one packet between packets721and722received by reception device217in AP124is not obtained.

For example, APs123and124may perform maximum ratio combining, and then perform demodulation/decoding, to obtain packets.

(5) In the Case of Setting Two APs for Multicast Transmission to Receive Data

An example of received data in the case of setting two APs121and122for multicast transmission and other two APs123and124for unicast transmission to receive data is described below, with reference toFIG. 8. In this case. APs121and122do not receive data. Meanwhile, APs123and124receive different data.

Packets811,812,813,814, . . . are generated from one set of unicast data. Packets816,817,818,819, . . . are generated from another set of unicast data.

2.5 Mapping Method and Phase Change

(A) inFIG. 9illustrates an example of a mapping method in IQ plane of in-phase component I and quadrature component Q that constitute a signal in QPSK modulation.

As illustrated in (A) inFIG. 9, for example in the case where input data is “00”, mapping unit206outputs in-phase component I=r and quadrature component Q=r of a baseband signal. Likewise, in the case where input data is “01”, mapping unit206outputs in-phase component I=−r and quadrature component Q=r of a baseband signal. In the case where input data is “10”, mapping unit206outputs in-phase component I=r and quadrature component Q=−r of a baseband signal. Likewise, in the case where input data is “11”, mapping unit206outputs in-phase component I=−r and quadrature component Q=−r of a baseband signal. Signal points901,902,903, and904illustrated in (A) inFIG. 9are thus obtained. (B) inFIG. 9illustrates an example of a mapping method after phase change.

Rotating signal points901,902,903, and904in (A) inFIG. 9by θ(u) about the origin point (where u is a symbol number) yields signal points911,912,913, and914in (B) inFIG. 9. The phase change value is a function of symbol number u, and so is denoted as θ(u).

Here, y(t) may be set as follows.

Wireless communication system100may hold a plurality of phase change patterns. Each AP is then assigned one phase change pattern.

For example, wireless communication system100holds four phase change patterns of cycles N1, N2, N3, and N4. A phase change pattern of cycle N1(the phase change value is denoted as y1(i), where y1(i) is a function of symbol number i) is assigned to AP121. A phase change pattern of cycle N2(the phase change value is denoted as y2(i), where y2(i) is a function of symbol number i) is assigned to AP122. A phase change pattern of cycle N3(the phase change value is denoted as y3(i), where y3(i) is a function of symbol number i) is assigned to AP123. A phase change pattern of cycle N4(the phase change value is denoted as y4(i), where y4(i) is a function of symbol number i) is assigned to AP124.

Here, k=i mod N1, where N1is an integer greater than or equal to 2, and i is, for example, an integer greater than or equal to 0. i mod N1denotes the remainder after division of i by N1(mod: modulo).

Here, k=i mod N2, where N2is an integer greater than or equal to 2, and i is, for example, an integer greater than or equal to 0. i mod N2denotes the remainder after division of i by N2(mod: modulo).

Here, k=i mod N3, where N3is an integer greater than or equal to 2, and i is, for example, an integer greater than or equal to 0. i mod N3denotes the remainder after division of i by N3(mod: modulo).

Here, k=i mod N4, where N4is an integer greater than or equal to 2, and i is, for example, an integer greater than or equal to 0. i mod N4denotes the remainder after division of i by N4(mod: modulo).

If possible, different phase change patterns are preferably used. In the case where a first AP and a second AP are near each other, the phase change pattern assigned to the first AP and the phase change pattern assigned to the second AP may be different.

Alternatively, the phase change pattern assigned to the first AP and the phase change pattern assigned to the second AP may be the same.

Any of APs121,122,123, and124may perform no phase change.

2.7 Operation in Wireless Communication System100

Operation in wireless communication system100is described below.

(1) Packet Transmission Operation

Packet transmission operation in parent station110and APs121,122,123, and124in wireless communication system100is described below, with reference to sequence diagrams inFIGS. 11 to 12.

The communication device generates a packet (Step S1101), and transmits the generated packet to parent station110(Step S1102). The communication device returns to Step S1101, and repeats packet generation and packet transmission.

Transmission data separator302receives the packet from the communication device (Step S1102). Transmission data separator302determines whether the received packet is for multicast or for unicast (Step S1103). In the case where the received packet is for unicast (Step S1103: “unicast”), transmission data separator302transfers control to Step S1216.

In the case where the received packet is for multicast (Step S1103: “multicast”), transmission data separator302determines whether or not AP121is set for multicast (Step S1104). In the case where AP121is set for multicast (Step S1104: “multicast”), transmission data separator302outputs the received packet to AP121(Step S1105). AP121receives the packet (Step S1105). AP121performs processes such as encoding, interleaving, mapping, and phase change (Step S1106). AP121then wirelessly outputs a signal (Step S1107).

In the case where AP121is not set for multicast (Step S1104: “No”), transmission data separator302determines whether or not AP122is set for multicast (Step S1108). In the case where AP122is set for multicast (Step S1108: “multicast”), transmission data separator302outputs the received packet to AP122(Step S1109). AP122receives the packet (Step S1109). AP122performs processes such as encoding, interleaving, mapping, and phase change (Step S1110). AP122then wirelessly outputs a signal (Step S1111).

In the case where AP122is not set for multicast (Step S1108: “No”), transmission data separator302determines whether or not AP123is set for multicast (Step S1112). In the case where AP123is set for multicast (Step S1112: “multicast”), transmission data separator302outputs the received packet to AP123(Step S1113). AP123receives the packet (Step S1113). AP123performs processes such as encoding, interleaving, mapping, and phase change, and wirelessly outputs a signal.

In the case where AP123is not set for multicast (Step S1112: “No”), transmission data separator302determines whether or not AP124is set for multicast (Step S1114). In the case where AP124is set for multicast (Step S1114: “multicast”), transmission data separator302outputs the received packet to AP124(Step S1115). AP124receives the packet (Step S1115). AP124performs processes such as encoding, interleaving, mapping, and phase change, and wirelessly outputs a signal.

In the case where AP124is not set for multicast (Step S1114: “No”), transmission data separator302returns control to Step S1102.

In the case where the received packet is for unicast (Step S1103: “unicast”), transmission data separator302determines whether or not AP121is set for unicast (Step S1216). In the case where AP121is set for unicast (Step S1216: “unicast”), transmission data separator302outputs the received packet to AP121(Step S1217). AP121receives the packet (Step S1217). AP121performs processes such as encoding, interleaving, mapping, and phase change (Step S1218). AP121then wirelessly outputs a signal (Step S1219).

In the case where AP121is not set for unicast (Step S1216: “No”), transmission data separator302determines whether or not AP122is set for unicast (Step S1220). In the case where AP122is set for unicast (Step S1220: “unicast”), transmission data separator302outputs the received packet to AP122(Step S1221). AP122receives the packet (Step S1221). AP122performs processes such as encoding, interleaving, mapping, and phase change (Step S1222). AP122then wirelessly outputs a signal (Step S1223).

In the case where AP122is not set for unicast (Step S1220: “No”), transmission data separator302determines whether or not AP123is set for unicast (Step S1224). In the case where AP123is set for unicast (Step S1224: “unicast”), transmission data separator302outputs the received packet to AP123(Step S1225). AP123receives the packet (Step S1225). AP123performs processes such as encoding, interleaving, mapping, and phase change, and wirelessly outputs a signal.

In the case where AP123is not set for unicast (Step S1224: “No”), transmission data separator302determines whether or not AP124is set for unicast (Step S1226). In the case where AP124is set for unicast (Step S1226: “unicast”), transmission data separator302outputs the received packet to AP124(Step S1227). AP124receives the packet (Step S1227). AP124performs processes such as encoding, interleaving, mapping, and phase change, and wirelessly outputs a signal.

In the case where AP124is not set for unicast (Step S1226: “No”), transmission data separator302returns control to Step S1102.

(2) Packet Reception Operation

Packet reception operation in parent station110and APs121,122,123, and124in wireless communication system100is described below, with reference to a sequence diagram inFIG. 13.

Reception device217in AP121wirelessly receives a signal (Step S1351). Reception device217then outputs a packet to parent station110(Step S1352). Reception device217returns control to Step S1351(Step S1353), and repeats wireless reception and packet output.

Reception data separator305receives the packet from reception device217in AP121(Step S1352). Reception data separator305outputs the received packet to the communication device (Step S1354).

Reception device217in AP122wirelessly receives a signal (Step S1356). Reception device217then outputs a packet to parent station110(Step S1357). Reception device217returns control to Step S1356(Step S1358), and repeats wireless reception and packet output.

Reception data separator305receives the packet from reception device217in AP122(Step S1357). Reception data separator305outputs the received packet to the communication device (Step S1359).

Reception device217in AP123wirelessly receives a signal (Step S1361). Reception device217then outputs a packet to parent station110(Step S1362). Reception device217returns control to Step S1361(Step S1363), and repeats wireless reception and packet output.

Reception data separator305receives the packet from reception device217in AP123(Step S1362). Reception data separator305outputs the received packet to the communication device (Step S1364).

Reception device217in AP124wirelessly receives a signal (Step S1366). Reception device217then outputs a packet to parent station110(Step S1367). Reception device217returns control to Step S1366(Step S1368), and repeats wireless reception and packet output.

Reception data separator305receives the packet from reception device217in AP124(Step S1367). Reception data separator305outputs the received packet to the communication device (Step S1369).

Wireless communication system1400as a variation of wireless communication system100is described below.

In wireless communication system100, parent station110is wiredly connected to each of APs121,122,123, and124(or may be wirelessly connected to each of APs121,122,123, and124). In other words, parent station110and APs121,122,123, and124are wiredly (or wirelessly) connected in parallel. However, this is not a limitation.

Wireless communication system1400has a structure similar to that of wireless communication system100. The differences from wireless communication system100are mainly described below.

(Packet Transmission in Direction from Parent Station1410to Terminal)

Parent station1410transmits a packet for AP1421, a packet for AP1422, a packet for AP1423, and a packet for AP1424, to AP1421.

AP1421receives the packet for AP1421, the packet for AP1422, the packet for AP1423, and the packet for AP1424, from parent station1410.

Upon receiving the packet for AP1421, AP1421performs processes such as encoding on the packet, and wirelessly outputs it.

Upon obtaining the packet for AP1422, the packet for AP1423, and the packet for AP1424, AP1421transmits the packet for AP1422, the packet for AP1423, and the packet for AP1424, to AP1422.

AP1422receives the packet for AP1422, the packet for AP1423, and the packet for AP1424, from AP1421.

Upon receiving the packet for AP1422, AP1422performs processes such as encoding on the packet, and wirelessly outputs it.

Upon obtaining the packet for AP1423and the packet for AP1424, AP1422transmits the received packet for AP1423and packet for AP1424, to AP1423.

AP1423receives the packet for AP1423and the packet for AP1424, from AP1422.

Upon receiving the packet for AP1423, AP1423performs processes such as encoding on the packet, and wirelessly outputs it.

Upon obtaining the packet for AP1424, AP1423transmits the received packet for AP1424, to AP1424.

AP1424receives the packet for AP1424, from AP1423.

Upon receiving the packet for AP1424, AP1424performs processes such as encoding on the packet, and wirelessly outputs it.

(Packet Transmission in Direction from Terminal to Parent Station1410)

AP1424receives a packet transmitted from any of the terminals. Upon receiving the packet, AP1424transmits the received packet to AP1423.

AP1423receives a packet transmitted from any of the terminals. AP1423also receives the packet (the packet wirelessly received by AP1424from a terminal), from AP1424. Upon receiving the packet from the terminal and the packet from AP1424, AP1423transmits the packet from the terminal and the packet from AP1424, to AP1422.

AP1422receives a packet transmitted from any of the terminals. AP1422also receives the packets (the packet wirelessly received by AP1424from a terminal and the packet wirelessly received by AP1423from a terminal), from AP1423. Upon receiving the packet from the terminal and the packets from AP1423, AP1422transmits the packet from the terminal and the packets from AP1423, to AP1421.

AP1421receives a packet transmitted from any of the terminals. AP1421also receives the packets (the packet wirelessly received by AP1424from a terminal, the packet wirelessly received by AP1423from a terminal, and the packet wirelessly received by AP1422from a terminal), from AP1422. Upon receiving the packet from the terminal and the packets from AP1422, AP1421transmits the packet from the terminal and the packets from AP1422, to parent station1410.

Wireless communication system1500as a variation of wireless communication system100is described below.

Wireless communication system1500has a structure similar to that of wireless communication system100. Wireless communication system1500includes parent station1598and APs1599-1,1599-2,1599-3, and1599-4instead of parent station110and APs121,122,123, and124in wireless communication system100, as illustrated inFIG. 15. The differences from wireless communication system100are mainly described below.

APs1599-1,1599-2,1599-3, and1599-4do not perform at least the processes of error correction encoding, interleaving, mapping, and phase change.

AP #1 transmission signal processor1507-1, AP #2 transmission signal processor1507-2, AP #3 transmission signal processor1507-3, and AP #4 transmission signal processor1507-4perform the processes of error correction encoding, interleaving, mapping, and phase change, respectively for APs1599-1,1599-2,1599-3, and1599-4.

In particular, a feature lies in that AP #1 transmission signal processor1507-1, AP #2 transmission signal processor1507-2, AP #3 transmission signal processor1507-3, and AP #4 transmission signal processor1507-4each perform the phase change process.

AP #1 transmission processor1509-1, AP #2 transmission processor1509-2, AP #3 transmission processor1509-3, and AP #4 transmission processor1509-4each perform processes such as frequency conversion and power amplification.

The processes by indicator1504and the processes by transmission data separator1502are respectively the same as the processes by indicator308and the processes by transmission data separator302in wireless communication system100.

An example of the processes by transmission data separator1502is as described with reference toFIGS. 4 to 6.

Wireless communication system1600as a variation of wireless communication system100is described below.

Wireless communication system1600has a structure similar to that of wireless communication system100. Wireless communication system1600includes parent station1698and APs1699-1,1699-2,1699-3, and1699-4instead of parent station110and APs121,122,123, and124in wireless communication system100, as illustrated inFIG. 16. The differences from wireless communication system100are mainly described below.

The major difference from wireless communication system100is that the function of the reception process (demodulation, decoding) is shared between parent station1698and APs1699-1,1699-2,1699-3, and1699-4.

AP #1 reception processor1603-1, AP #2 reception processor1603-2, AP #3 reception processor1603-3, and AP #4 reception processor1603-4each perform processes such as frequency conversion.

The processes by indicator1610and the processes by reception data separator1607are respectively the same as the processes by indicator308and the processes by reception data separator305in wireless communication system100.

An example of the processes by reception data separator1607is as described with reference toFIGS. 7 and 8.

1.11 Operation in the Case where Parent Station Places AP Under Control

Operation in the case where parent station110newly places an AP under control in wireless communication system100is described below, with reference to a flowchart inFIG. 17.

Suppose four APs121,122,123, and124are under control of parent station110, and then a new AP is to be added. At this point, the phase change patterns (and IDs) have already been set for four APs121,122,123, and124.

An AP that intends to be newly placed under control of parent station110notifies parent station110of a request to be placed under control of parent station110. Parent station110receives the request from the new AP (Step S1701).

Parent station110determines whether or not to place the new AP under its control (Step S1702). In the case of determining to place the new AP under its control (Step S1702: “Yes”), parent station110assigns an ID to the new AP. Here, the ID is associated with a phase change pattern. The new AP sets the phase change pattern from the assigned ID (Step S1703). This completes the operation in the case of newly placing an AP under control.

In the case of determining not to place the new AP under its control (Step S1702: “No”), parent station110notifies the new AP that the AP is not to be placed under its control (Step S1704). This completes the operation in the case of newly placing an AP under control.

Step S1703may be performed as follows.

Parent station110transmits information indicating the phase change pattern to be set by the new AP, to the new AP. The new AP receives the information indicating the phase change pattern, and sets the phase change pattern in the AP based on the received information indicating the phase change pattern. Here, parent station110may or may not assign the ID to the new AP. Assigning the ID here has the advantage that, in the case where parent station110designates the AP newly placed under its control as a unicast AP or a multicast AP, the ID and unicast or multicast can be easily designated for the AP by transmitting information “ID and unicast or multicast” to the AP.

The above describes the case where four APs121,122,123, and124are under control of parent station110and then a new AP is to be added. However, this is not a limitation.

There may be no AP under control of parent station110in an initial state. In such a case, APs may be placed under control of parent station110one by one, as described above.

In Step S1702, parent station110may determine whether or not to place the new AP under its control, depending on a limit to the number of APs placed under its control. Parent station110stores a maximum value of the number of APs placed under its control. When there is a request from one AP to be newly placed under its control, parent station110adds “1” to the number of APs currently under its control, and compares the obtained value with the maximum value. In the case where the obtained value is not greater than the maximum value, parent station110permits the AP to be under its control. In the case where the obtained value is greater than the maximum value, parent station110does not permit the AP to be under its control.

In Step S1702, parent station110may determine whether or not to place the new AP under its control, depending on the position of the new AP and the phase change pattern.

For example, when the new AP is away from each AP already under its control, parent station110permits the new AP to be under its control.

For example, when the new AP is near any AP already under its control, if there is a phase change pattern to be assigned to the new AP, parent station110permits the new AP to be under its control.

For example, when the new AP is near any AP already under its control, if there is no phase change pattern to be assigned to the new AP, parent station110does not permit the new AP to be under its control.

According to this embodiment, large-capacity transmission of Gbps level can be achieved. Moreover, the number of terminals accommodated in the case of implementing multicast can be increased. Furthermore, unicast communication can be realized simultaneously with multicast. A flexible system can thus be provided.

Wireless communication system1800according to Embodiment 2 as another embodiment of the present disclosure is described below.

Parent station1810is connected to a communication device (not illustrated) directly, or indirectly via a communication line. The communication device is, for example, a broadcast device for broadcasting data or a distribution system or a server for transmitting data. The communication device transmits a control signal and data. The control signal includes unicast transmission-related setting or multicast transmission-related setting, and phase change method setting. The communication device may include a plurality of communication devices. In this case, a first communication device may transmit the control signal, and a second communication device may transmit the data. Parent station1810is wiredly (or wirelessly) connected to APs1820-1,1820-2,1820-3, and1820-4. AP1820-1is wiredly (or wirelessly) connected to APs1820-2,1820-3, and1820-4.

Parent station1810receives the control signal and the data from the communication device. Parent station1810transmits the control signal to AP1820-1. Parent station1810transmits the data to each of APs1820-1,1820-2,1820-3, and1820-4. APs1820-1,1820-2,1820-3, and1820-4wirelessly transmit the data obtained from parent station1810.

Terminals1830-1,1830-2, . . . ,1830-8are each a mobile phone, a smartphone, a tablet, or a personal computer (PC) that has a wireless communication function using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz. Terminal1830-1, for example, wirelessly receives data from AP1820-1in the case where terminal1830-1is located near AP1820-1. Terminals1830-2, . . . ,1830-8each wirelessly receive data from its nearby AP, as with terminal1830-1.

Terminal1830-1also wirelessly transmits data. In the case where terminal1830-1is located near AP1820-1, AP1820-1wirelessly receives the data from terminal1830-1. AP1820-1transmits the received data to parent station1810.

Terminals1830-2,1830-3, . . . ,1830-8each wirelessly transmit data, as with terminal1830-1. An AP located near each terminal wirelessly receives the data from the terminal. The AP transmits the data received from the terminal, to parent station1810.

Parent station1810obtains the data transmitted from each terminal, via the corresponding AP. Parent station1810outputs the received data to the communication device.

The control signal transmitted from parent station1810to AP1820-1includes unicast transmission-related setting or multicast transmission-related setting in each AP, and phase change method setting in each AP. Parent station1810does not perform unicast transmission-related setting and multicast transmission-related setting for APs1820-2,1820-3, and1820-4. Parent station1810does not perform phase change method setting for APs1820-2,1820-3, and1820-4.

AP1820-1performs unicast transmission-related setting or multicast transmission-related setting for APs1820-2,1820-3, and1820-4. AP1820-1also performs phase change method setting for APs1820-2,1820-3, and1820-4.

AP1820-1receives control signal1901from parent station1810. Control signal1901includes unicast transmission-related setting or multicast transmission-related setting, and phase change method setting.

AP1820-1performs unicast transmission-related setting or multicast transmission-related setting, based on control signal1901received from parent station1810. AP1820-1also performs phase change method setting, based on control signal1901. In the case where multicast transmission-related setting is performed, the AP is set to use the same frequency (frequency band) as other APs.

In the case of performing unicast transmission-related setting, AP1820-1operates reception device217. In the case of performing multicast transmission-related setting, AP1820-1may stop the operation of reception device217.

AP1820-1performs wireless transmission/reception using the same channel in the case of unicast and in the case of multicast. Here, AP1820-1may divide one wireless carrier into several time slots, and use each time slot as a communication channel. Alternatively, AP1820-1may use each of a plurality of different frequencies in the frequency bandwidth of 60 GHz, as a communication channel.

Encoder202receives data201from parent station1810. Encoder202also receives control signal213from a controller included in AP1820-1. Control signal213includes information such as encoding scheme designation, error correction scheme designation, encoding rate, and block length. Encoder202performs error correction encoding, such as convolution encoding, LDPC encoding, or turbo encoding, on data201, using the schemes designated by control signal213. Encoder202outputs encoded data203.

Mapping unit206receives interleaved data205from interleaver204. Mapping unit206also receives control signal213from the controller included in AP1820-1. Control signal213includes modulation scheme designation. Mapping unit206performs modulation, such as quadrature phase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM), or 64 quadrature amplitude modulation (64QAM), on interleaved data205according to the modulation scheme designation included in control signal213, to generate modulated signal207. Mapping unit206outputs modulated signal207. Other modulation schemes may be used.

Mapping unit206may perform mapping including a phase change process.

Phase changer208receives modulated signal207from mapping unit206. Phase changer208also receives control signal1903_0. Control signal1903_0includes phase change method setting. Phase changer208performs phase change on modulated signal207according to the phase change method setting included in control signal1903_0, to generate phase-changed signal209. Phase changer208outputs phase-changed signal209.

Wireless unit210receives phase-changed signal209from phase changer208. Wireless unit210also receives control signal213from the controller included in AP1820-1. Control signal213includes designation of frequency conversion, amplification, etc. Wireless unit210performs processes such as frequency conversion and amplification on phase-changed signal209, to generate transmission signal211. Wireless unit210outputs generated transmission signal211to antenna212, using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz.

Antenna215receives signal216output from each terminal as a radio wave.

Reception device217receives signal216from antenna215using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz, and performs processes such as amplification and frequency conversion on signal216, to generate data218. Reception device217outputs data218to parent station1810.

Although antennas212and215are described separately for convenience's sake, they may be the same entity.

Indicator1902is connected to parent station1810.

Indicator1902receives control signal1901from parent station1810. Control signal1901includes unicast transmission-related setting or multicast transmission-related setting, and phase change method setting.

Separate control signal1901may be set for each AP, or same control signal1901may be set for all APs.

Here, indicator1902may perform multicast transmission-related setting for all APs, or perform unicast transmission-related setting for all APs. Indicator1902may perform multicast transmission-related setting for part of the APs, and unicast transmission-related setting for the other APs.

For a plurality of APs subjected to multicast transmission-related setting, the modulated signal before phase change is the same signal. In other words, the same data is transmitted.

Indicator1902also indicates a phase change method to each AP, using control signals1903_1, . . . ,1903_N.

For a plurality of APs subjected to unicast transmission-related setting, the modulated signal before phase change may be the same signal or a different signal. In other words, the same data may be transmitted, or different data may be transmitted.

In the case of designating unicast transmission for AP1820-1, indicator1902operates reception device217. In the case of designating multicast transmission for AP1820-1, indicator1902may stop the operation of reception device217.

AP2000receives control signal2001_0from AP1820-1which is a master AP. Control signal2001_0includes unicast transmission-related setting or multicast transmission-related setting, and phase change method setting. AP2000also receives data2002from AP1820-1which is a master AP. In the case of performing AP cooperation, AP2000may receive data2003from another non-master AP. In the case of operating singly in unicast transmission, AP2000may receive data201from parent station1810.

AP2000performs unicast transmission-related setting or multicast transmission-related setting, based on control signal2001_0. AP2000also performs phase change method setting, based on control signal2001_0. In the case where multicast transmission is set, the AP is set to use the same frequency (frequency band) as other APs.

In the case where unicast transmission is set, AP2000operates reception device217. In the case where multicast transmission is set, AP2000may stop the operation of reception device217.

AP2000performs wireless transmission/reception using the same channel (or the same frequency) in the case of unicast transmission and in the case of multicast transmission. Here, A P2000may divide one wireless carrier into several time slots, and use each time slot as a communication channel. Alternatively, A P2000may use each of a plurality of different frequencies in the frequency bandwidth of 60 GHz, as a communication channel.

Encoder202receives data2002,2003, or201. Encoder202also receives control signal213from a controller included in AP2000. Control signal213includes information such as encoding scheme designation, error correction scheme designation, encoding rate, and block length. Encoder202performs error correction encoding, such as convolution encoding, LDPC encoding, or turbo encoding, on data2002,2003, or201, using the schemes designated by control signal213. Encoder202outputs encoded data203.

Mapping unit206receives interleaved data205from interleaver204. Mapping unit206also receives control signal213from the controller included in AP2000. Control signal213includes modulation scheme designation. Mapping unit206performs modulation, such as quadrature phase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM), or 64 quadrature amplitude modulation (64QAM), on interleaved data205according to the modulation scheme designation included in control signal213, to generate modulated signal207. Mapping unit206outputs modulated signal207. Other modulation schemes may be used.

Mapping unit206may perform mapping including a phase change process.

Phase changer208receives modulated signal207from mapping unit206. Phase changer208also receives control signal2001_0. Control signal2001_0includes phase change method setting. Phase changer208performs phase change on modulated signal207according to the phase change method setting included in control signal2001_0, to generate phase-changed signal209. Phase changer208outputs phase-changed signal209.

Wireless unit210receives phase-changed signal209from phase changer208. Wireless unit210also receives control signal213from the controller included in AP2000. Control signal213includes designation of frequency conversion, amplification, etc. Wireless unit210performs processes such as frequency conversion and amplification on phase-changed data209, to generate transmission data211. Wireless unit210outputs generated transmission signal211to antenna212, using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz.

Antenna215receives signal216output from each terminal as a radio wave.

Reception device217receives data216from antenna215using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz, and performs processes such as amplification and frequency conversion on signal216, to generate data218. Reception device217outputs data218to parent station1810.

Although antennas212and215are described separately for convenience's sake, they may be the same entity.

3.4 Example of Transmitted Data

An example of data transmitted by parent station1810and APs1820-1,1820-2,1820-3, and1820-4is described below.

(1) In the Case of Setting all APs for Multicast to Transmit Data

An example of transmitted data in the case of setting all APs1820-1,1820-2,1820-3, and1820-4for multicast to transmit data is described below, with reference toFIG. 21.

In this case, a feature lies in that APs1820-1,1820-2,1820-3, and1820-4each perform phase change on the modulated signal (alternatively, any of APs1820-1,1820-2,1820-3, and1820-4may perform no phase change).

This has the advantages of widening the cell range within the reach of a multicast modulated signal, and reducing, by means of phase change, points at which reception is difficult due to modulated signal interference.

(2) In the Case of Setting Two APs for Multicast to Transmit Data

An example of transmitted data in the case of setting two APs1820-1and1820-2for multicast transmission and other two APs1820-3and1820-4for unicast transmission to transmit data is described below, with reference toFIG. 22. In this case, APs1820-1and1820-2transmit the same data (the modulated signal after mapping and before phase change is the same). Moreover. APs1820-3and1820-4transmit the same data (the modulated signal after mapping and before phase change is the same).

As described above, in the case of transmitting the modulated signal in unicast transmission, the packets transmitted in APs1820-3and1820-4are based on the same data. Here, APs1820-3and1820-4have the same transmission parameter. APs1820-3and1820-4may perform different phase changes (alternatively, any of APs1820-3and1820-4may perform no phase change).

This has the advantages of widening the cell range within the reach of a unicast modulated signal, and reducing, by means of phase change, points at which reception is difficult due to modulated signal interference.

A feature lies in that APs1820-1and1820-2each perform phase change on the modulated signal (alternatively, any of APs1820-1and1820-2may perform no phase change). (The phase change method will be described in detail later.)

This has the advantages of widening the cell range within the reach of a multicast modulated signal, and reducing, by means of phase change, points at which reception is difficult due to modulated signal interference.

(3) In the Case of Setting Two APs for Multicast to Transmit Data

An example of transmitted data in the case of setting two APs1820-1and1820-2for multicast transmission and other two APs1820-3and1820-4for unicast transmission to transmit data is described below, with reference toFIG. 23. InFIG. 23, APs1820-3and1820-4transmit different data.

Packets2301,2303,2304, and2306are generated from one set of multicast data. Packets2302,2307, and2309are generated from one set of unicast data. Packets2305,2308, and2310are generated from another set of unicast data.

A feature lies in that APs1820-1and1820-2each perform phase change on the modulated signal (alternatively, any of APs1820-1and1820-2may perform no phase change).

This has the advantages of widening the cell range within the reach of a multicast modulated signal, and reducing, by means of phase change, points at which reception is difficult due to modulated signal interference.

Moreover, a flexible system in which APs1820-3and1820-4can perform unicast communication is realized.

There is thus the advantage of realizing a flexible system by, for example, switching the transmission state among the transmission state inFIG. 21, the transmission state inFIG. 22, and the transmission state inFIG. 23depending on time (e.g. switching depending on the terminal presence situation).

3.5 Operation in the Case where Master AP Newly Places AP Under Control

Operation in the case where AP1820-1which is a master AP newly places an AP under control in wireless communication system1800is described below, with reference to a flowchart inFIG. 24.

Suppose three APs1820-2,1820-3, and1820-4are under control of AP1820-1which is a master AP, and then a new AP is to be added. At this point, the phase change patterns (and (AP) IDs (identification)) have already been set for four APs1820-1,1820-2,1820-3, and1820-4.

An AP that intends to be newly placed under control of AP1820-1notifies AP1820-1of a request to be placed under control of parent station110. AP1820-1receives the request from the new AP (Step S2401).

AP1820-1determines whether or not to place the new AP under its control (Step S2402). In the case of determining to place the new AP under its control (Step S2402: “Yes”), AP1820-1assigns an ID to the new AP. Here, the ID is associated with a phase change pattern. The new AP sets the phase change pattern from the assigned ID (Step S2403). This completes the operation in the case of newly placing an AP under control.

In the case of determining not to place the new AP under its control (Step S2402: “No”), AP1820-1notifies the new AP that the AP is not to be placed under its control (Step S2404). This completes the operation in the case of newly placing an AP under control.

Step S2403may be performed as follows.

AP1820-1which is a master AP transmits information indicating the phase change pattern to be set by the new AP, to the new AP. The new AP receives the information indicating the phase change pattern, and sets the phase change pattern in the AP based on the received information indicating the phase change pattern. Here, AP1820-1which is a master AP may or may not assign the ID to the new AP. Assigning the ID here has the advantage that, in the case where AP1820-1which is a master AP designates the AP newly placed under its control as a unicast transmission AP or a multicast transmission AP, the ID and unicast transmission or multicast transmission can be easily designated for the AP by transmitting information “ID and unicast or multicast” to the AP.

The above describes the case where three APs1820-2,1820-3, and1820-4are under control of AP1820-1which is a master AP and then a new AP is to be added. However, this is not a limitation.

There may be no AP under control of AP1820-1which is a master AP in an initial state. In such a case, APs may be placed under control of AP1820-1which is a master AP one by one, as described above.

In Step S2402, AP1820-1which is a master AP may determine whether or not to place the new AP under its control, depending on a limit to the number of APs placed under its control. AP1820-1stores a maximum value of the number of APs placed under its control. When there is a request from one AP to be newly placed under its control, AP1820-1adds “1” to the number of APs currently under its control, and compares the obtained value with the maximum value. In the case where the obtained value is not greater than the maximum value, AP1820-1permits the AP to be under its control. In the case where the obtained value is greater than the maximum value, AP1820-1does not permit the AP to be under its control.

In Step S2402, AP1820-1may determine whether or not to place the new AP under its control, depending on the position of the new AP and the phase change pattern.

For example, when the new AP is away from AP1820-1and each AP already under its control, AP1820-1permits the new AP to be under its control.

For example, when the new AP is near AP1820-1or any AP already under its control, if there is a phase change pattern to be assigned to the new AP, AP1820-1permits the new AP to be under its control.

For example, when the new AP is near AP1820-1or any AP already under its control, if there is no phase change pattern to be assigned to the new AP, AP1820-1does not permit the new AP to be under its control.

According to this embodiment, large-capacity transmission of Gbps level can be achieved. Moreover, the number of terminals accommodated in the case of implementing multicast can be increased. Furthermore, unicast communication can be realized simultaneously with multicast. A flexible system can thus be provided.

Wireless communication system2500according to Embodiment 3 of the present disclosure is described below.

Parent station2510is connected to a communication device (not illustrated) directly, or indirectly via a communication line. The communication device is, for example, a broadcast device for broadcasting data or a distribution system or a server for transmitting data. The communication device transmits a control signal and data. The control signal includes unicast transmission method-related setting or multicast transmission method-related setting, and weighting method setting. The communication device may include a plurality of communication devices. In this case, a first communication device may transmit the control signal, and a second communication device may transmit the data. Parent station2510is wiredly (or wirelessly) connected to APs2520-1,2520-2,2520-3, and2520-4.

Parent station2510receives the control signal and the data from the communication device. Parent station2510transmits the control signal and the data to each of APs2520-1,2520-2,2520-3, and2520-4. APs2520-1,2520-2,2520-3, and2520-4wirelessly transmit the data obtained from parent station2510.

Terminals2530-1,2530-2, . . . ,2530-8are each a mobile phone, a smartphone, a tablet, or a personal computer (PC) that has a wireless communication function using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz.

Terminal2530-1, for example, wirelessly receives data from AP2520-1in the case where terminal2530-1is located near AP2520-1. Terminals2530-2, . . . ,2530-8each wirelessly receive data from its nearby AP, as with terminal2530-1.

Terminal2530-1also wirelessly transmits data. In the case where terminal2530-1is located near AP2520-1, AP2520-1wirelessly receives the data from terminal2530-1. AP2520-1transmits the received data to parent station2510.

Terminals2530-2,2530-3, . . .2530-8each wirelessly transmit data, as with terminal2530-1. An AP located near each terminal wirelessly receives the data from the terminal. The AP transmits the data received from the terminal, to parent station2510.

Parent station2510receives data from each terminal via a corresponding AP Parent station2510outputs the received data to the communication device.

The control signal transmitted from parent station2510to APs2520-1,2520-2,2520-3, and2520-4includes unicast transmission-related setting or multicast transmission-related setting in each AP, and weighting method setting in each AP.

AP2520performs unicast transmission method-related setting or multicast transmission-related setting, based on control signal214received from parent station2510. AP2520also performs weighting method setting, based on control signal214. In the case where multicast transmission is set, the AP is set to use the same frequency (frequency band) as other APs.

In the case where unicast transmission is set, AP2520operates reception device217. In the case where multicast transmission is set, AP2520may stop the operation of reception device217.

AP2520performs wireless transmission/reception using the same channel (or the same frequency (frequency band)) in the case of unicast transmission and in the case of multicast transmission. Here, AP2520may divide one wireless carrier into several time slots, and use each time slot as a communication channel. Alternatively, AP2520may use each of a plurality of different frequencies in the frequency bandwidth of 60 GHz, as a communication channel.

Encoder202receives data201from parent station2510. Encoder202also receives control signal213from a controller included in AP2520. Control signal213includes information such as encoding scheme designation, error correction scheme designation, encoding rate, and block length. Encoder202performs error correction encoding, such as convolution encoding, LDPC encoding, or turbo encoding, on data201, using the schemes designated by control signal213. Encoder202outputs encoded data203.

Mapping unit206receives interleaved data205from interleaver204. Mapping unit206also receives control signal213from the controller included in AP2520. Control signal213includes modulation scheme designation. Mapping unit206performs modulation, such as quadrature phase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM), or 64 quadrature amplitude modulation (64QAM), on interleaved data205according to the modulation scheme designation included in control signal213, to generate modulated signal207. Mapping unit206outputs modulated signal207. Other modulation schemes may be used.

Mapping unit206may perform mapping including a weighting process.

Weighting unit2601receives modulated signal207from mapping unit206. Weighting unit2601also receives control signal214. Control signal214includes weighting method setting. Weighting unit2601performs weighting on modulated signal207according to the weighting method setting included in control signal214, to generate weighted signal2602. Weighting unit2601outputs weighted signal2602.

Wireless unit210receives weighted data2602from weighting unit2601. Wireless unit210also receives control signal213from the controller included in AP2520. Control signal213includes designation of frequency conversion, amplification, etc. Wireless unit210performs processes such as frequency conversion and amplification on weighted signal2602, to generate transmission signal211. Wireless unit210outputs generated transmission signal211to antenna212, using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz.

Antenna215receives signal216output from each terminal as a radio wave.

Reception device217receives signal216from antenna215using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz, and performs processes such as amplification and frequency conversion on signal216, to generate data218. Reception device217outputs data218to parent station2510.

Although antennas212and215are described separately for convenience's sake, they may be the same entity.

Parent station2510includes transmission data separator302, reception data separator305, and indicator308, as illustrated inFIG. 27.

Indicator308is connected to the communication device and APs2520-1,2520-2,2520-3, and2520-4.

Indicator308receives control signal307. Control signal307includes unicast transmission-related setting or multicast transmission-related setting, and weighting method setting. For example, the communication device includes a PC, and the user of the PC inputs the control signal through the PC.

Separate control signal307may be set for each AP, or same control signal307may be set for all APs.

Multicast transmission may be set for all APs, or unicast transmission may be set for all APs. Multicast transmission may be set for part of the APs, and unicast transmission for the other APs. Thus, multicast transmission-related setting and unicast-related setting may be mixed for the APs.

For a plurality of APs set for multicast, the modulated signal before weighting is the same signal. In other words, the same data is transmitted.

Indicator308also indicates a weighting method to each AP.

For a plurality of APs set for unicast, the modulated signal before weighting may be the same signal or a different signal. In other words, the same data may be transmitted, or different data may be transmitted.

Transmission data separator302is connected to the communication device, indicator308, and APs2520-1,2520-2,2520-3, and2520-4.

Transmission data separator302also receives data301from the communication device. Transmission data separator302separates the received data into data for AP2520-1, data for AP2520-2, data for AP2520-3, and data for AP2520-4. Transmission data separator302outputs the separated data to each of APs2520-1,2520-2,2520-3, and2520-4.

Reception data separator305is connected to the communication device, indicator308, and APs2520-1,2520-2,2520-3, and2520-4.

4.4 Example of Transmitted Data

An example of data transmitted by parent station2510and APs2520-1,2520-2,2520-3, and2520-4is described below.

(1) In the Case of Setting all APs for Multicast Transmission to Transmit Data

An example of transmitted data in the case of setting all APs2520-1,2520-2,2520-3, and2520-4for multicast transmission to transmit data is described below with reference toFIGS. 28 and 29.

Transmission data separator302outputs packets2811,2812,2813,2814, . . . in this order, to each of APs2520-1,2520-2,2520-3, and2520-4.

(a) Process 1 of Each AP

(b) Process 2 of Each AP

The process of each AP is described below, with reference toFIG. 29.

c(0) is a mapped baseband signal related to packet2811, c(1) is a mapped baseband signal related to packet2812, c(2) is a mapped baseband signal related to packet2813, c(3) is a mapped baseband signal related to packet2814, . . . .

In the case where mapped baseband signal complex numbers2913“c(2)”,2914“c(3)”, . . . are generated, AP2520-1operates in the same way as above.

c(0) is a mapped baseband signal related to packet2811, c(1) is a mapped baseband signal related to packet2812, c(2) is a mapped baseband signal related to packet2813, c(3) is a mapped baseband signal related to packet2814, . . . .

In the case where mapped baseband signal complex numbers2913“c(2)”,2914“c(3)”, . . . are generated, AP2520-2operates in the same way as above.

APs2520-3and2520-4operate in the same way as above.

Thus, features lie in that each packet is subjected to different weighting and transmitted a plurality of times, and that each packet is transmitted a plurality of times from a plurality of APs.

Transmission using a plurality of APs has the advantageous effect of widening the cell area. In addition, transmitting each packet a plurality of times with different weighting has the advantageous effect of maintaining more uniform reception quality in the cell area because the packet is transmitted a plurality of times with different directivity.

For example, weighting coefficients A1(i), A2(i), A3(i), and A4(i) have the following properties.Suppose a modulated signal of packet A is transmitted N times (N is an integer greater than or equal to 2). Let A1(u) be a weighting coefficient used to transmit the u-th modulated signal of packet A, and A1(v) be a weighting coefficient used to transmit the v-th modulated signal of packet A. u and v are each an integer greater than or equal to 1 and less than or equal to N, where u≠v. For all u and v that are each an integer greater than or equal to 1 and less than or equal to N where u≠v, A1(u)≠A1(v) holds.Equally suppose a modulated signal of packet A is transmitted N times (N is an integer greater than or equal to 2). Let Ak(u) be a weighting coefficient used to transmit the u-th modulated signal of packet A, and Ak(v) be a weighting coefficient used to transmit the v-th modulated signal of packet A. u and v are each an integer greater than or equal to 1 and less than or equal to N, where u≠v. For all u and v that are each an integer greater than or equal to 1 and less than or equal to N where u≠v, Ak(u)≠Ak(v) holds (k is an integer greater than or equal to 1).Weighting coefficient Ak(i) may have a cycle. When the cycle is denoted by M (M is an integer greater than or equal to 2), the following Expression (8) holds.
[Math. 8]
Ak(i)=Ak(imodM)  Expression (8).

i mod M is the remainder after division of i by M.

(2) In the Case of Setting APs2520-1and2520-2for Multicast Transmission and APs2520-3and2520-4for Unicast Transmission to Transmit Data

An example of transmitted data in the case of setting APs2520-1and2520-2for multicast transmission and APs2520-3and2520-4for unicast transmission to transmit data is described below, with reference toFIGS. 30 and 31. In this case, APs2520-1and2520-2transmit the same data (the modulated signal after mapping and before phase change is the same). Moreover, APs2520-3and2520-4transmit the same data (the modulated signal after mapping is the same).

Transmission data separator302outputs multicast packets3011,3013,3014,3016, . . . in this order, to each of APs2520-1and2520-2. Transmission data separator302also outputs unicast packets3012,3015, . . . in this order, to each of APs2520-3and2520-4.

(a) Process 1 of Each AP

(b) Process 2 of Each AP

Another example of the process of each AP is described below, with reference toFIG. 31.

c(0) is a mapped baseband signal related to packet3011, c(1) is a mapped baseband signal related to packet3013, c(2) is a mapped baseband signal related to packet3014, c(3) is a mapped baseband signal related to packet3016, . . . .

In the case where mapped baseband signal complex numbers3113“c(2)”,3114“c(3)”, . . . are generated, AP2520-1operates in the same way as above.

c(0) is a mapped baseband signal related to packet3011, c(1) is a mapped baseband signal related to packet3013, c(2) is a mapped baseband signal related to packet3014, c(3) is a mapped baseband signal related to packet3016, . . . .

In the case where mapped baseband signal complex numbers3113“c(2)”,3114“c(3)”, . . . are generated, AP2520-2operates in the same way as above.

d(0) is a mapped baseband signal related to packet3051, d(1) is a mapped baseband signal related to packet3052, d(2) is a mapped baseband signal related to packet3053, . . . .

After mapped baseband signal complex number “d(0)” is generated, AP2520-3wirelessly outputs mapped baseband signal complex number “d(0)” (3151), as illustrated inFIG. 31.

After mapped baseband signal complex number “d(1)” is generated, AP2520-3wirelessly outputs mapped baseband signal complex number “d(1)” (3152), as illustrated inFIG. 31.

d(0) is a mapped baseband signal related to packet3061, d(1) is a mapped baseband signal related to packet3062, d(2) is a mapped baseband signal related to packet3063, . . . .

After mapped baseband signal complex number “d(0)” is generated, AP2520-4wirelessly outputs mapped baseband signal complex number “d(0)” (3161), as illustrated inFIG. 31.

After mapped baseband signal complex number “d(1)” is generated, AP2520-4wirelessly outputs mapped baseband signal complex number “d(1)” (3162), as illustrated inFIG. 31.

Thus, features lie in that each multicast packet is subjected to different weighting and transmitted a plurality of times, and that each multicast packet is transmitted a plurality of times from a plurality of APs.

Transmission using a plurality of APs has the advantageous effect of widening the cell area. In addition, transmitting each multicast packet a plurality of times with different weighting has the advantageous effect of maintaining more uniform reception quality in the cell area because the packet is transmitted a plurality of times with different directivity.

In APs2520-3and2520-4, phase change may be performed or weighting may be changed with respect to time or frequency. This has the advantageous effect of improving unicast packet reception quality.

(3) in the Case of Setting APs2520-1and2520-2for Multicast and APs2520-3and2520-4for Unicast to Transmit Data

An example of transmitted data in the case of setting APs2520-1and2520-2for multicast transmission and APs2520-3and2520-4for unicast transmission to transmit data is described below, with reference toFIGS. 32 and 33. In this case, APs2520-3and2520-4transmit different data.

(a) Process 1 of Each AP

(b) Process 2 of Each AP

Another example of the process of each AP is described below, with reference toFIG. 33.

c(0) is a mapped baseband signal related to packet3211, c(1) is a mapped baseband signal related to packet3213, c(2) is a mapped baseband signal related to packet3214, c(3) is a mapped baseband signal related to packet3216, . . . .

In the case where mapped baseband signal complex numbers3313“c(2)”,3314“c(3)”, . . . are generated, AP2520-1operates in the same way as above.

c(0) is a mapped baseband signal related to packet3211, c(1) is a mapped baseband signal related to packet3213, c(2) is a mapped baseband signal related to packet3214, c(3) is a mapped baseband signal related to packet3216, . . . .

In the case where mapped baseband signal complex numbers3313“c(2)”,3314“c(3)”, . . . are generated, AP2520-2operates in the same way as above.

d(0) is a mapped baseband signal related to packet3251, d(1) is a mapped baseband signal related to packet3252, d(2) is a mapped baseband signal related to packet3253, . . . .

After mapped baseband signal complex number “d(0)” is generated, AP2520-3wirelessly outputs mapped baseband signal complex number “d(0)” (3351), as illustrated inFIG. 33.

After mapped baseband signal complex number “d(1)” is generated, AP2520-3wirelessly outputs mapped baseband signal complex number “d(1)” (3352), as illustrated inFIG. 33.

e(0) is a mapped baseband signal related to packet3261, e(1) is a mapped baseband signal related to packet3262, e(2) is a mapped baseband signal related to packet3263, . . . .

After mapped baseband signal complex number “e(0)” is generated, AP2520-4wirelessly outputs mapped baseband signal complex number “e(0)” (3361), as illustrated inFIG. 33.

After mapped baseband signal complex number “e(1)” is generated, AP2520-4wirelessly outputs mapped baseband signal complex number “e(1)” (3362), as illustrated inFIG. 33.

Thus, features lie in that each multicast packet is subjected to different weighting and transmitted a plurality of times, and that each multicast packet is transmitted a plurality of times from a plurality of APs.

Transmission using a plurality of APs has the advantageous effect of widening the cell area. In addition, transmitting each multicast packet a plurality of times with different weighting has the advantageous effect of maintaining more uniform reception quality in the cell area because the packet is transmitted a plurality of times with different directivity.

Moreover, a flexible system in which APs2520-3and2520-4can transmit unicast packets is realized.

There is thus the advantage of realizing a flexible system by, for example, switching the transmission state among the transmission state inFIG. 28, the transmission state inFIG. 30, and the transmission state inFIG. 32depending on time (e.g. switching depending on the terminal presence situation).

According to this embodiment, large-capacity transmission of Gbps level can be achieved. Moreover, the number of terminals accommodated in the case of implementing multicast can be increased. Furthermore, unicast communication can be realized simultaneously with multicast. A flexible system can thus be provided.

Wireless communication system3400according to Embodiment 4 as another embodiment of the present disclosure is described below.

Parent station3410is connected to a communication device (not illustrated) directly, or indirectly via a communication line. The communication device is, for example, a broadcast device for broadcasting data or a distribution system or a server for transmitting data. The communication device transmits a control signal and data. The control signal includes unicast transmission method-related setting or multicast transmission method-related setting, and weighting method setting. The communication device may include a plurality of communication devices. In this case, a first communication device may transmit the control signal, and a second communication device may transmit the data. Parent station3410is wiredly (or wirelessly) connected to APs3420-1,3420-2,3420-3, and3420-4. AP3420-1is wiredly (or wirelessly) connected to APs3420-2,3420-3, and3420-4.

Parent station3410receives the control signal and the data from the communication device. Parent station3410transmits the control signal to AP3420-1. Parent station3410transmits the data to each of APs3420-1,3420-2,3420-3, and3420-4. APs3420-1,3420-2,3420-3, and3420-4wirelessly transmit the data received from parent station3410.

Terminals3430-1,3430-2, . . . ,3430-8are each a mobile phone, a smartphone, a tablet, or a personal computer (PC) that has a wireless communication function using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz. Terminal3430-1, for example, wirelessly receives data from AP3420-1in the case where terminal3430-1is located near AP3420-1. Terminals3430-2, . . . ,3430-8each wirelessly receive data from its nearby AP, as with terminal3430-1.

Terminal3430-1also wirelessly transmits data. In the case where terminal3430-1is located near AP3420-1, AP3420-1wirelessly receives the data from terminal3430-1. AP3420-1transmits the received data to parent station3410.

Terminals3430-2,3430-3, . . . ,3430-8each wirelessly transmit data, as with terminal3430-1. An AP located near each terminal wirelessly receives the data from the terminal. The AP transmits the data received from the terminal, to parent station3410.

Parent station3410receives the data from each terminal, via the corresponding AP. Parent station3410outputs the received data to the communication device.

The control signal transmitted from parent station3410to AP3420-1includes unicast transmission-related setting or multicast transmission-related setting in each AP and weighting method setting in each AP. Parent station3410does not perform unicast transmission-related setting and multicast transmission-related setting for APs3420-2,3420-3, and3420-4. Parent station3410does not perform weighting method setting for APs3420-2,3420-3, and3420-4.

AP3420-1performs unicast transmission-related setting or multicast transmission-related setting, based on control signal3501received from parent station3410. AP3420-1also performs weighting method setting, based on control signal3501. In the case where multicast transmission setting is performed, the AP is set to use the same frequency (frequency band) as other APs.

In the case of performing unicast transmission setting, AP3420-1operates reception device217. In the case of performing multicast transmission setting, AP3420-1may stop the operation of reception device217.

AP3420-1performs wireless transmission/reception using the same channel in the case of unicast transmission and in the case of multicast transmission. Here, AP3420-1may divide one wireless carrier into several time slots, and use each time slot as a communication channel. Alternatively, AP3420-1may use each of a plurality of different frequencies in the frequency bandwidth of 60 GHz, as a communication channel.

Encoder202receives data201from parent station3410. Encoder202also receives control signal213from a controller included in AP3420-1. Control signal213includes information such as encoding scheme designation, error correction scheme designation, encoding rate, and block length. Encoder202performs error correction encoding, such as convolution encoding, LDPC encoding, or turbo encoding, on data201, using the schemes designated by control signal213. Encoder202outputs encoded data203.

Mapping unit206receives interleaved data205from interleaver204. Mapping unit206also receives control signal213from the controller included in AP3420-1. Control signal213includes modulation scheme designation. Mapping unit206performs modulation, such as quadrature phase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM), or 64 quadrature amplitude modulation (64QAM), on interleaved data205according to the modulation scheme designation included in control signal213, to generate modulated signal207. Mapping unit206outputs modulated signal207. Other modulation schemes may be used.

Mapping unit206may perform mapping including a weighting process.

Weighting unit3511receives modulated signal207from mapping unit206. Weighting unit3511also receives control signal3503_0. Control signal3503_0includes weighting method setting. Weighting unit3511performs weighting on modulated signal207according to the weighting method setting included in control signal3503_0, to generate weighted signal3512. Weighting unit3511outputs weighted signal3512.

Wireless unit210receives weighted signal3512from weighting unit3511. Wireless unit210also receives control signal213from the controller included in AP3420-1. Control signal213includes designation of frequency conversion, amplification, etc. Wireless unit210performs processes such as frequency conversion and amplification on weighted signal3512, to generate transmission signal211. Wireless unit210outputs generated transmission signal211to antenna212, using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz.

Antenna215receives signal216output from each terminal as a radio wave.

Reception device217receives signal216from antenna215using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz, and performs processes such as amplification and frequency conversion on signal216, to generate data218. Reception device217outputs data218to parent station3410.

Although antennas212and215are described separately for convenience's sake, they may be the same entity.

Indicator3502is connected to parent station3410.

Separate control signal3501may be set for each AP, or same control signal3501may be set for all APs.

Indicator3502performs multicast transmission setting or unicast transmission setting for all APs including AP3420-1, using control signals3503_0,3503_1, . . . ,3503_N.

Here, indicator3502may perform multicast transmission setting for all APs, or perform unicast transmission setting for all APs. Indicator3502may perform multicast transmission setting for part of the APs, and unicast transmission setting for the other APs. Thus, multicast transmission setting and unicast transmission setting may be mixed for the APs.

For a plurality of APs set for multicast transmission, the modulated signal before weighting is the same signal. In other words, the same data is transmitted.

For a plurality of APs set for unicast transmission, the modulated signal before weighting may be the same signal or a different signal. In other words, the same data may be transmitted, or different data may be transmitted.

In the case of designating unicast transmission for AP3420-1, indicator3502operates reception device217. In the case of designating multicast transmission for AP3420-1, indicator3502may stop the operation of reception device217.

AP3600receives control signal3601_0from master AP3420-1. Control signal3601_0includes unicast transmission-related setting or multicast transmission-related setting, and weighting method setting. AP3600also receives data3602from master AP3420-1. In the case of performing AP cooperation, AP3600may receive data3603from another non-master AP. In the case of operating singly in unicast transmission, AP3600may receive data201from parent station3410.

AP3600performs unicast transmission-related setting or multicast transmission-related setting, based on control signal3601_0. AP3600also performs weighting method setting, based on control signal3601_0. In the case where multicast transmission is set, the AP is set to use the same frequency (frequency band) as other APs.

In the case where unicast transmission is set, AP3600operates reception device217. In the case where multicast transmission is set, AP3600may stop the operation of reception device217.

AP3600performs wireless transmission/reception using the same channel (or the same frequency (frequency band)) in the case of unicast transmission and in the case of multicast transmission. Here, AP3600may divide one wireless carrier into several time slots, and use each time slot as a communication channel. Alternatively AP3600may use each of a plurality of different frequencies in the frequency bandwidth of 60 GHz, as a communication channel.

Encoder202receives data3602,3603, or201. Encoder202also receives control signal213from a controller included in AP3600. Control signal213includes information such as encoding scheme designation, error correction scheme designation, encoding rate, and block length. Encoder202performs error correction encoding, such as convolution encoding, LDPC encoding, or turbo encoding, on data3602,3603, or201, using the schemes designated by control signal213. Encoder202outputs encoded data203.

Mapping unit206receives interleaved data205from interleaver204. Mapping unit206also receives control signal213from the controller included in AP3600. Control signal213includes modulation scheme designation. Mapping unit206performs modulation, such as quadrature phase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM), or 64 quadrature amplitude modulation (64QAM), on interleaved data205according to the modulation scheme designation included in control signal213, to generate modulated signal207. Mapping unit206outputs modulated signal207. Other modulation schemes may be used.

Mapping unit206may perform mapping including a weighting process.

Weighting unit3611receives modulated signal207from mapping unit206. Weighting unit3611also receives control signal3601_0. Control signal3601_0includes weighting method setting. Weighting unit3611performs weighting on modulated signal207according to the weighting method setting included in control signal3601_0, to generate weighted signal3612. Weighting unit3611outputs weighted signal3612.

Wireless unit210receives weighted signal3612from weighting unit3611. Wireless unit210also receives control signal213from the controller included in AP3600. Control signal213includes designation of frequency conversion, amplification, etc. Wireless unit210performs processes such as frequency conversion and amplification on weighted signal3612, to generate transmission signal211. Wireless unit210outputs generated transmission signal211to antenna212, using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz.

Antenna215receives signal216output from each terminal as a radio wave.

Reception device217receives signal216from antenna215using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz, and performs processes such as amplification and frequency conversion on signal216, to generate data218. Reception device217outputs data218to parent station3410.

Although antennas212and215are described separately for convenience's sake, they may be the same entity.

Parent station3410includes transmission data separator302, reception data separator305, and indicator308, as illustrated inFIG. 37.

Indicator308is connected to the communication device and APs3420-1,3420-2,3420-3, and3420-4.

Indicator308receives control signal307. Control signal307includes unicast transmission-related setting or multicast transmission-related setting, and weighting method setting. For example, the communication device includes a PC, and the user of the PC inputs the control signal through the PC.

Separate control signal307may be set for each AP, or same control signal307may be set for all APs.

Multicast transmission may be set for all APs, or unicast transmission may be set for all APs. Multicast transmission may be set for part of the APs, and unicast transmission for the other APs. Thus, multicast transmission-related setting and unicast-related setting may be mixed for the APs.

For a plurality of APs set for multicast, the modulated signal before weighting is the same signal. In other words, the same data is transmitted.

Indicator308also indicates a weighting method to each AP.

For a plurality of APs set for unicast, the modulated signal before weighting may be the same signal or a different signal. In other words, the same data may be transmitted, or different data may be transmitted.

Indicator308outputs the received control signal to transmission data separator302, reception data separator305, and APs3420-1,3420-2,3420-3, and3420-4.

Transmission data separator302is connected to the communication device, indicator308, and APs3420-1,3420-2,3420-3, and3420-4.

Transmission data separator302receives a control signal from indicator308. Transmission data separator302outputs the received control signal to APs3420-1,3420-2,3420-3, and3420-4.

Transmission data separator302also receives data from the communication device. Transmission data separator302separates the received data into data for AP3420-1, data for AP3420-2, data for AP3420-3, and data for AP3420-4. Transmission data separator302outputs the separated data to each of APs3420-1,3420-2,3420-3, and3420-4.

Reception data separator305is connected to the communication device, indicator308, and APs3420-1,3420-2,3420-3, and3420-4.

Reception data separator305receives respective data from APs3420-1,3420-2,3420-3, and3420-4. Reception data separator305outputs the received data to the communication device.

5.5 Example of Transmitted Data

An example of data transmitted by parent station3410and APs3420-1,3420-2,3420-3, and3420-4is described below.

(1) In the Case of Setting all APs for Multicast Transmission to Transmit Data

An example of transmitted data in the case of setting all APs3420-1,3420-2,3420-3, and3420-4for multicast transmission to transmit data is described below, with reference toFIGS. 38 and 39.

(a) Process 1 of Each AP

(b) Process 2 of Each AP

Another example of the process of each AP is described below, with reference toFIG. 39.

c(0) is a mapped baseband signal related to packet3811, c(1) is a mapped baseband signal related to packet3812, c(2) is a mapped baseband signal related to packet3813, c(3) is a mapped baseband signal related to packet3814, . . . .

In the case where mapped baseband signal complex numbers3913“c(2)”,3914“c(3)”, . . . are generated, AP3420-1operates in the same way as above.

c(0) is a mapped baseband signal related to packet3811, c(1) is a mapped baseband signal related to packet3812, c(2) is a mapped baseband signal related to packet3813, c(3) is a mapped baseband signal related to packet3814, . . . .

In the case where mapped baseband signal complex numbers3913“c(2)”,3914“c(3)”, . . . are generated, AP3420-2operates in the same way as above.

APs3420-3and3420-4operate in the same way as above.

Thus, features lie in that each packet is subjected to different weighting and transmitted a plurality of times, and that each packet is transmitted a plurality of times from a plurality of APs.

Transmission using a plurality of APs has the advantageous effect of widening the cell area. In addition, transmitting each packet a plurality of times with different weighting has the advantageous effect of maintaining more uniform reception quality in the cell area because the packet is transmitted a plurality of times with different directivity.

For example, weighting coefficients A1(i), A2(i), A3(i), and A4(i) have the following properties.Suppose a modulated signal of packet A is transmitted N times (N is an integer greater than or equal to 2). Let A1(u) be a weighting coefficient used to transmit the u-th modulated signal of packet A, and A1(v) be a weighting coefficient used to transmit the v-th modulated signal of packet A. u and v are each an integer greater than or equal to 1 and less than or equal to N, where u≠v. For all u and v that are each an integer greater than or equal to 1 and less than or equal to N where u≠v, A1(u)≠A1(v) holds.Equally suppose a modulated signal of packet A is transmitted N times (N is an integer greater than or equal to 2). Let Ak(u) be a weighting coefficient used to transmit the u-th modulated signal of packet A. and Ak(v) be a weighting coefficient used to transmit the v-th modulated signal of packet A. u and v are each an integer greater than or equal to 1 and less than or equal to N, where u≠v. For all u and v that are each an integer greater than or equal to 1 and less than or equal to N where u≠v, Ak(u)≠Ak(v) holds (k is an integer greater than or equal to 1).Weighting coefficient Ak(i) may have a cycle. When the cycle is denoted by M (M is an integer greater than or equal to 2), the following holds.
[Math. 9]
Ak(i)=Ak(imodM)  Expression (9).

i mod M is the remainder after division of i by M.

(2) In the Case of Setting APs3420-1and3420-2for Multicast Transmission and APs3420-3and3420-4for Unicast Transmission to Transmit Data

An example of transmitted data in the case of setting APs3420-1and3420-2for multicast transmission and APs3420-3and3420-4for unicast transmission to transmit data is described below, with reference toFIGS. 40 and 41. In this case, APs3420-3and3420-4transmit the same data (the modulated signal after mapping is the same).

(a) Process 1 of Each AP

(b) Process 2 of Each AP

Another example of the process of each AP is described below, with reference toFIG. 41.

c(0) is a mapped baseband signal related to packet4011, c(1) is a mapped baseband signal related to packet4013, c(2) is a mapped baseband signal related to packet4014, c(3) is a mapped baseband signal related to packet4016, . . . .

In the case where mapped baseband signal complex numbers4113“c(2)”,4114“c(3)”, . . . are generated, AP3420-1operates in the same way as above.

c(0) is a mapped baseband signal related to packet4011, c(1) is a mapped baseband signal related to packet4013, c(2) is a mapped baseband signal related to packet4014, c(3) is a mapped baseband signal related to packet4016, . . . .

In the case where mapped baseband signal complex numbers4113“c(2)”,4114“c(3)”, . . . are generated, AP3420-2operates in the same way as above.

d(0) is a mapped baseband signal related to packet4051, d(1) is a mapped baseband signal related to packet4052, d(2) is a mapped baseband signal related to packet4053, . . . .

After mapped baseband signal complex number “d(0)” is generated, AP3420-3wirelessly outputs generated d(0) (4151).

After mapped baseband signal complex number “d(1)” is generated, AP3420-3wirelessly outputs generated d(1) (4152).

d(0) is a mapped baseband signal related to packet4061, d(1) is a mapped baseband signal related to packet4062, d(2) is a mapped baseband signal related to packet4063, . . . .

After mapped baseband signal complex number “d(0)” is generated, AP3420-4wirelessly outputs generated d(0) (4161).

After mapped baseband signal complex number “d(1)” is generated, AP3420-4wirelessly outputs generated d(1) (4162).

Thus, features lie in that each multicast packet is subjected to different weighting and transmitted a plurality of times, and that each multicast packet is transmitted a plurality of times from a plurality of APs.

Transmission using a plurality of APs has the advantageous effect of widening the cell area. In addition, transmitting each multicast packet a plurality of times with different weighting has the advantageous effect of maintaining more uniform reception quality in the cell area because the packet is transmitted a plurality of times with different directivity.

In APs3420-3and3420-4, phase change may be performed or weighting may be changed with respect to time or frequency. This has the advantageous effect of improving unicast packet reception quality.

(3) in the Case of Setting APs3420-1and3420-2for Multicast Transmission and APs3420-3and3420-4for Unicast Transmission to Transmit Data

An example of transmitted data in the case of setting APs3420-1and3420-2for multicast transmission and APs3420-3and3420-4for unicast transmission to transmit data is described below, with reference toFIGS. 42 and 43. In this case, APs3420-3and3420-4transmit different data.

(a) Process 1 of Each AP

(b) Process 2 of Each AP

Another example of the process of each AP is described below, with reference toFIG. 43.

c(0) is a mapped baseband signal related to packet4211, c(1) is a mapped baseband signal related to packet4213, c(2) is a mapped baseband signal related to packet4214, c(3) is a mapped baseband signal related to packet4216, . . . .

In the case where mapped baseband signal complex numbers4313“c(2)”,4314“c(3)”, . . . are generated, AP3420-1operates in the same way as above.

c(0) is a mapped baseband signal related to packet4211, c(1) is a mapped baseband signal related to packet4213, c(2) is a mapped baseband signal related to packet4214, c(3) is a mapped baseband signal related to packet4216, . . . .

In the case where mapped baseband signal complex numbers4313“c(2)”,4314“c(3)”, . . . are generated, AP3420-2operates in the same way as above.

d(0) is a mapped baseband signal related to packet4251, d(1) is a mapped baseband signal related to packet4252, d(2) is a mapped baseband signal related to packet4253, . . . .

After mapped baseband signal complex number “d(0)” is generated, AP3420-3wirelessly outputs generated d(0) (4351).

After mapped baseband signal complex number “d(1)” is generated, AP3420-3wirelessly outputs generated d(1) (4352).

e(0) is a mapped baseband signal related to packet4261, e(1) is a mapped baseband signal related to packet4262, e(2) is a mapped baseband signal related to packet4263, . . . .

After mapped baseband signal complex number “e(0)” is generated, AP3420-4wirelessly outputs generated e(0) (4361).

After mapped baseband signal complex number “e(1)” is generated, AP3420-4wirelessly outputs generated e(1) (4362).

Thus, features lie in that each multicast packet is subjected to different weighting and transmitted a plurality of times, and that each multicast packet is transmitted a plurality of times from a plurality of APs.

Transmission using a plurality of APs has the advantageous effect of widening the cell area. In addition, transmitting each multicast packet a plurality of times with different weighting has the advantageous effect of maintaining more uniform reception quality in the cell area because the packet is transmitted a plurality of times with different directivity.

Moreover, a flexible system in which APs3420-3and3420-4transmit unicast packets is realized.

There is thus the advantage of realizing a flexible system by, for example, switching the transmission state among the transmission state inFIG. 38, the transmission state inFIG. 40, and the transmission state inFIG. 42depending on time (e.g. switching depending on the terminal presence situation).

According to this embodiment, large-capacity transmission of Gbps level can be achieved. Moreover, the number of terminals accommodated in the case of implementing multicast can be increased. Furthermore, unicast communication can be realized simultaneously with multicast. A flexible system can thus be provided.

Wireless communication system4400according to Embodiment 5 as another embodiment of the present disclosure is described below.

For example, APs4420-1,4420-2,4420-3, and4420-4are installed on the roof of building4451, and parent station4410-1is installed inside building4451. Moreover, APs4420-11,4420-12,4420-13, and4420-14are installed on the roof of building4452, and parent station4410-2is installed inside building4452. Their installation is, however, not limited to such.

Consider a use case where there is no obstacle such as another building between APs4420-1,4420-2,4420-3, and4420-4and APs4420-11,4420-12,4420-13, and4420-14(although such a use case is not a limitation).

Parent station4410-1is connected to a communication device (communication device A) (not illustrated) holding data transmitted by APs, either directly or indirectly via a communication line. Communication device A is, for example, a mobile phone, a smartphone, a tablet, or a personal computer. Communication device A may be, for example, a broadcast device for broadcasting data or a distribution system or a server for transmitting data. Communication device A transmits a control signal for controlling the parent station and the APs, and “data to be transmitted by AP”. The control signal may include unicast setting. Communication device A may include a plurality of communication devices. In this case, a first communication device may transmit the control signal, and a second communication device may transmit the data. Communication device A may be used inside building4451. Communication device A may be used outside buildings4451and4452. Parent station4410-1is wiredly (or wirelessly) connected to APs4420-1,4420-2,4420-3, and4420-4, and APs4420-1,4420-2,4420-3, and4420-4transmit data obtained from communication device A.

The control signal includes information of a setting parameter when each AP performs unicast transmission, and a parameter of a phase change method when each AP performs phase change.

Parent station4410-2is connected to another communication device (communication device B), either directly or indirectly via a communication line. Communication device B is, for example, a mobile phone, a smartphone, a tablet, or a personal computer. Communication device A may be installed in a building or the like or installed outdoors, as mentioned above. Communication device B may be used inside building4452. Communication device B may be used outside buildings4451and4452. Parent station4410-2is wiredly (or wirelessly) connected to APs4420-11,4420-12,4420-13, and4420-14, and APs4420-11,4420-12,4420-13, and4420-14transmit data obtained from communication device B.

AP4420-11is also a master AP, and so has the same structure as master AP4420-1.

AP4420-1receives control signal4401from parent station4410-1. Control signal4401includes unicast transmission setting for each AP, and phase change parameter setting when performing phase change.

AP4420-1performs unicast transmission-related setting, based on control signal4401received from parent station4410-1. AP4420-1also performs phase change method parameter setting, based on control signal4401.

In the case of performing unicast transmission, AP4420-1operates reception device217.

Encoder202receives data201from parent station4410-1. Encoder202also receives control signal213from a controller included in AP4420-1. Control signal213includes information such as encoding scheme designation, error correction scheme designation, encoding rate, and block length. Encoder202performs error correction encoding, such as convolution encoding, LDPC encoding, or turbo encoding, on data201, using the schemes designated by control signal213. Encoder202outputs encoded data203.

Mapping unit206receives interleaved data205from interleaver204. Mapping unit206also receives control signal213from the controller included in AP4420-1. Control signal213includes modulation scheme designation. Mapping unit206performs modulation, such as quadrature phase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM), or 64 quadrature amplitude modulation (64QAM), on interleaved data205according to the modulation scheme designation included in control signal213, to generate modulated signal207. Mapping unit206outputs modulated signal207. Other modulation schemes may be used.

Mapping unit206may perform mapping including a phase change process.

Phase changer208receives modulated signal207from mapping unit206. Phase changer208also receives control signal4403_0. Control signal4403_0includes phase change method setting. Phase changer208performs phase change on modulated signal207according to the phase change method setting included in control signal4403_0, to generate phase-changed signal209. Phase changer208outputs phase-changed signal209.

Wireless unit210receives phase-changed signal209from phase changer208. Wireless unit210also receives control signal213from the controller included in AP4420-1. Control signal213includes designation of frequency conversion, amplification, etc. Wireless unit210performs processes such as frequency conversion and amplification on phase-changed signal209, to generate transmission signal211. Wireless unit210outputs generated transmission signal211to antenna212, using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz.

Antenna215receives signal216output from each terminal as a radio wave.

Reception device217receives signal216from antenna215using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz, and performs processes such as amplification and frequency conversion on signal216, to generate data218. Reception device217outputs data218to parent station4410-1.

Although antennas212and215are described separately for convenience's sake, they may be the same entity.

Indicator4402is connected to parent station4410-1.

Indicator1902receives control signal4401from parent station4410-1. Control signal4401includes information of unicast-related setting and phase change method setting.

Indicator4402provides unicast transmission-related setting information to all APs including AP4420-1, based on control signal4401.

Indicator4402also indicates a phase change method to each AP.

In the case of performing unicast transmission for AP4420-1, indicator4402operates reception device217.

AP4600receives control signal4601_0from AP4420-1which is a master AP. Control signal4601_0includes unicast transmission-related information and phase change-related information. AP4600also receives data4602(not performing AP cooperation) from AP4420-1which is a master AP. In the case of performing AP cooperation, AP4600may receive data4603from another AP. AP4600may receive data201from parent station4410-1, and pass the data to another AP.

AP4600performs unicast transmission-related setting, based on control signal4601_0. AP4600also performs phase change method setting, based on control signal4601_0.

In the case of performing unicast setting, AP4600operates reception device217.

Encoder202receives data4602,4603, or201from parent station4410_1. Encoder202also receives control signal213from a controller included in AP4600. Control signal213includes information such as encoding scheme designation, error correction scheme designation, encoding rate, and block length. Encoder202performs error correction encoding, such as convolution encoding, LDPC encoding, or turbo encoding, on data4602,4603, or201, using the schemes designated by control signal213. Encoder202outputs encoded data203.

Mapping unit206receives interleaved data205from interleaver204. Mapping unit206also receives control signal213from the controller included in AP4600. Control signal213includes modulation scheme designation. Mapping unit206performs modulation, such as quadrature phase shift keying (QPSK), 16 quadrature amplitude modulation (16QAM), or 64 quadrature amplitude modulation (64QAM), on interleaved data205according to the modulation scheme designation included in control signal213, to generate modulated signal207. Mapping unit206outputs modulated signal207. Other modulation schemes may be used.

Mapping unit206may perform mapping including a phase change process.

Phase changer208receives modulated signal207from mapping unit206. Phase changer208also receives control signal4601_0. Control signal4601_0includes phase change method setting. Phase changer208performs phase change on modulated signal207according to the phase change method setting included in control signal4601_0, to generate phase-changed signal209. Phase changer208outputs phase-changed signal209.

Wireless unit210receives phase-changed signal209from phase changer208. Wireless unit210also receives control signal213from the controller included in AP4600. Control signal213includes designation of frequency conversion, amplification, etc. Wireless unit210performs processes such as frequency conversion and amplification on phase-changed signal209, to generate transmission signal211. Wireless unit210outputs generated transmission signal211to antenna212, using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz.

Antenna215receives signal216output from each terminal as a radio wave.

Reception device217receives signal216from antenna215using a frequency bandwidth of 6 GHz or more such as millimeter wave, e.g. a frequency bandwidth of 60 GHz, and performs processes such as amplification and frequency conversion on signal216, to generate data218. Reception device217outputs data218to parent station4410-1or4410-2.

Although antennas212and215are described separately for convenience's sake, they may be the same entity.

6.4 Example of Transmitted Data

An example of data transmitted by parent station4410-1and APs4420-1,4420-2,4420-3, and4420-4is described below.

It is assumed here that all APs are set for unicast to perform transmission.

(1) During Clear Weather

An example of transmitted data in the case of setting all APs4420-1,4420-2,4420-3, and4420-4for unicast to transmit data during clear weather is described below, with reference toFIG. 47.

AP4420-1processes, by itself, packets4701,4705, . . . generated from the first unicast data in this order. AP4420-1also transmits packets4702,4706, . . . generated from the second unicast data in this order, to AP4420-2. AP4420-1also transmits packets4703, . . . generated from the third unicast data in this order, to AP4420-3. AP4420-1also transmits packets4704, . . . generated from the fourth unicast data in this order, to AP4420-4.

For example, suppose APs4420-1,4420-2,4420-3,4420-4,4420-11,4420-12,4420-13, and4420-14inFIG. 44include antennas that perform beam forming and the like and have strong directivity. In this case, suppose APs4420-1and4420-11communicate with each other. APs4420-2and4420-12communicate with each other. APs4420-3and4420-13communicate with each other, and APs4420-4and4420-14communicate with each other.

In the case where APs4420-11,4420-12,4420-13, and4420-14simultaneously receive a modulated signal transmitted from AP4420-1, a modulated signal transmitted from AP4420-2, a modulated signal transmitted from AP4420-3, and a modulated signal transmitted from AP4420-4, the signal received by AP4420-11, the signal received by AP4420-12, the signal received by AP4420-13, and the signal received by AP4420-14are subjected to a separation process to separate and obtain the packets.

As another example, suppose parent station4410-1obtains only packet U1-# X (X=1, 2, 3, . . . ). In such a case, for example, AP4420-1transmits packet U1-# X while the other APs stop operation. This reduces the number of APs in operation, and so has the advantageous effect of reducing power consumption in the system. During rainfall, transmission is performed as illustrated inFIG. 48(the operation inFIG. 48will be described in detail later). The advantages of this are as follows.

Particularly in the case of transmitting a modulated signal using a frequency in the millimeter wave band, rainfall causes significant attenuation of the signal (radio wave). To maintain a decrease in reception field intensity of the communication partner in a state where such attenuation occurs, the communication device needs to transmit the modulated signal with high average transmission power. However, a regulation value is often imposed on the average transmission power that can be transmitted by each communication equipment. Hence, the communication device may be unable to transmit the modulated signal with transmission power increased to such a level of average transmission power that can reduce the influence of rainfall attenuation.

In view of this, by transmitting modulated signals including the same data from a plurality of communication equipment as illustrated inFIG. 48, the advantageous effect that the communication partner has high reception field intensity while each communication device conforms to the regulation value on the average transmission power can be achieved.

Moreover, by performing such operation that “AP4420-1transmits packet U1-# X while the other APs stop operation” during clear weather as mentioned above, the advantageous effect of reducing power consumption in the system during clear weather can be achieved.

Thus, with different operations of the parent stations and APs between clear weather and rainfall, an advantageous system that can flexibly ensure communication quality and control power consumption can be realized.

(2) During Rainfall

An example of transmitted data in the case of setting all APs4420-1,4420-2,4420-3, and4420-4for unicast to transmit data during rainfall is described below, with reference toFIG. 48.

A feature lies in that APs4420-1,4420-2,4420-3, and4420-4transmit the same packets at the same time (the modulated signals after mapping at the same time are the same), as described in the other embodiments. Therefore, AP4420-1performs phase change, AP4420-2performs phase change, AP4420-3performs phase change, and also AP4420-4performs phase change (alternatively, any of APs4420-1,4420-2,4420-3, and4420-4may perform no phase change).

AlthoughFIG. 48illustrates an example where four APs are present and transmit packet U1-# X (X=1, 2, 3, . . . ), this is not a limitation. For example, N APs (N is an integer greater than or equal to 2) may be present, where M APs (M is an integer less than or equal to N, and greater than or equal to 2) transmit packet U1-# X (X=1, 2, 3, . . . ).

The following structure can be derived from the above.

N APs (N is an integer greater than or equal to 2) are present. During clear weather (when radio wave attenuation due to rainfall is low (a situation where it is raining but radio wave attenuation is low is regarded as “during clear weather”)), LAPs (L is an integer greater than or equal to 1, and less than or equal to N−1) transmit packet U1-# X (X=1, 2, 3, . . . ).

During rainfall (when radio wave attenuation due to rainfall is high), M APs (M is an integer less than or equal to N, greater than or equal to 2, and greater than L) may transmit packet U1-# X (X=1, 2, 3, . . . ).

By such transmission, a decrease in reception quality of the communication partner caused by propagation attenuation during rainfall can be suppressed, so that an advantageous system that can flexibly ensure communication quality and control power consumption can be realized. During clear weather, any AP not transmitting packet U1-# X may transmit other packets (or not transmit other packets). Likewise, during rainfall, any AP not transmitting packet U1-# X may transmit other packets (or not transmit other packets).

Reception device217in AP4420-11simultaneously receives a modulated signal corresponding to packet4811, a modulated signal corresponding to packet4821, a modulated signal corresponding to packet4831, and a modulated signal corresponding to packet4841. Reception device217in AP4420-11then simultaneously receives a modulated signal corresponding to packet4812, a modulated signal corresponding to packet4822, a modulated signal corresponding to packet4832, and a modulated signal corresponding to packet4842. Reception device217in AP4420-11then simultaneously receives a modulated signal corresponding to packet4813, a modulated signal corresponding to packet4823, a modulated signal corresponding to packet4833, and a modulated signal corresponding to packet4843. Reception device217in AP4420-11then simultaneously receives a modulated signal corresponding to packet4814, a modulated signal corresponding to packet4824, a modulated signal corresponding to packet4834, and a modulated signal corresponding to packet4844.

6.5 Operation of AP4420-1as Master AP

The operation of AP4420-1which is a master AP is described below, with reference to a flowchart inFIG. 49.

Indicator4402in AP4420-1which is a master AP obtains communication quality of communication with AP4420-11which is a communication partner (Step S4901). Indicator4402then determines whether or not the obtained communication quality is not less than a threshold (Step S4902).

In the case where the obtained communication quality is less than the threshold (Step S4902: “less than threshold”), for example, indicator4402causes APs4420-2,4420-3, and4420-4to perform cooperative operation to transmit the same data (Step S4903). Indicator4402then returns to Step S4901and repeats the process.

In the case where the obtained communication quality is not less than the threshold (Step S4902: “not less than threshold”), for example, indicator4402stops the cooperative operation of APs4420-2,4420-3, and4420-4(stops the transmission of the same data) (Step S4904). For example, indicator4402causes APs4420-2,4420-3, and4420-4to resume independent operation. The independent operation is operation before the cooperative operation starts (Step S4905). Indicator4402then returns to Step S4901and repeats the process.

6.6 Transmission of Training Signal by Each AP

For example, AP4420-1transmits a training signal both during clear weather, and during rainfall. A communication partner receives the training signal, and transmits the reception result to AP4420-1. AP4420-1obtains the reception result, thus obtaining communication quality with the AP on the receiving side. AP4420-1determines whether to perform or stop the above-mentioned cooperative operation, using the obtained communication quality. AP4420-1transmits the result indicating “whether to perform or stop cooperative operation”, to APs4420-2,4420-3, and4420-4(here, AP4420-1may transmit “whether to perform or stop cooperative operation” to APs4420-2,4420-3, and4420-4via the parent station, or transmit “whether to perform or stop cooperative operation” directly to APs4420-2,4420-3, and4420-4). In the case of determining to “perform cooperative operation”, AP4420-1transmits information about a phase change value method, a modulation scheme, and encoding method to be used, to APs4420-2,4420-3, and4420-4(here, AP4420-1may transmit information about a phase change value method, a modulation scheme, and encoding method to be used, to APs4420-2,4420-3, and4420-4via the parent station).

In this embodiment, no mode for setting “multicast” may be provided (for example, in the case of applying this embodiment to a communication device installed in a building and a communication device installed in a building, there may be instances where multicast need not be performed).

Although the above describes an example where a master AP and non-master APs perform cooperative operation, cooperative operation in the case where a parent station has part of the functions of a master AP as illustrated inFIGS. 1, 25, etc. may be employed in switching the frame structure as illustrated inFIG. 47and the frame structure as illustrated inFIG. 48during clear weather and during rainfall. The structure of a transmission system for switching cooperative operation between during clear weather and during rainfall is not limited to such, and the above-mentioned function of “switching cooperative operation between during clear weather and during rainfall” per se is important.

According to this embodiment, large-capacity transmission of Gbps can be achieved. In addition, wireless communication can be ensured even in the case of rainfall. Furthermore, since the master AP stops cooperative operation when returning to clear weather from rainfall, so that unnecessary power consumption caused by performing cooperative operation during clear weather can be prevented.

Although the above embodiment describes the case where four APs perform cooperative operation, this is not a limitation. Two or more APs may perform cooperative operation.

The embodiments and other contents in this description may be combined.

The embodiments and other contents are merely illustrative. For example, even when “modulation scheme, error (loss) correction encoding scheme (error correction encoding, code length, encoding rate, etc.), control information, etc.” are illustrated, other “modulation scheme, error (loss) correction encoding scheme (error correction encoding, code length, encoding rate, etc.), control information, etc.” may be similarly used in the same structure.

The transmission method in the wireless communication scheme may be a transmission method (SISO (Single-Input Single-Output) transmission method, SIMO (Single-Input Multiple-Output) transmission method) in which a transmission device has one antenna and a reception device receives a signal with one or more antennas, or a transmission method (MIMO (Multiple-Input Multiple-Output) transmission method, MISO (Multiple-Input Single-Output) transmission method) in which a transmission device transmits a plurality of streams and a reception device receives a modulated signal with one or more antennas. Moreover, space-time block encoding or space-time trellis encoding may be used (in the case of using a multicarrier scheme such as OFDM, symbols may be arranged in a time axis direction, in a frequency axis direction, or in a frequency-time axis direction).

The term “complex number” in this description is used to refer to “defining in a complex number”, which includes a real number with an imaginary component being 0.

The present disclosure is not limited to the above embodiments, and can be implemented in any form for achieving the object according to the present disclosure and its related or subsidiary object. For example, the following are applicable.

(1) The operation procedure of the communication device on the communication station side described in each of the above embodiments may be described in a program, and the program may be stored in read only memory (ROM) beforehand. A central processing unit (CPU) may then read the program stored in the ROM and execute it. Alternatively, the program describing the operation procedure of the communication device on the communication station side may be stored in a computer-readable storage medium and loaded into random access memory (RAM) in a computer. A CPU of the computer may then read the program stored in the RAM and execute it.

(2) The structural elements in each of the above embodiments may be typically realized by large scale integration (LSI) which is an integrated circuit. The structural elements may each be individually implemented as one chip, or may be partly or wholly implemented on one chip.

Although LSI is mentioned here, the integrated circuit may be called (integrated circuit) IC, system LSI, super LSI, or ultra LSI, depending on the degree of integration.

The integrated circuit technology is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. A field programmable gate array (FPGA) which can be programmed or a reconfigurable processor which is capable of reconfiguring connections and settings of circuit cells in LSI after LSI manufacturing may be used.

Furthermore, when an integrated circuit technology that replaces LSI emerges from development of semiconductor technologies or other derivative technologies, such a technology may be used to integrate the functional blocks. For instance, biotechnology may be adapted in this way.

In this description, for example, communication/broadcast equipment such as a broadcast station, a base station, an access point, a terminal, or a mobile phone includes a transmission device, and communication equipment such as a television, a radio, a terminal, a personal computer, a mobile phone, an access point, or a base station includes a reception device. A transmission device and a reception device according to the present disclosure may be equipment that has a communication function and can be connected, via some kind of interface, to a device for executing an application such as a television, a radio, a personal computer, or a mobile phone.

In each embodiment, symbols other than data symbols, such as pilot symbols (pre-amble, unique word, post-amble, reference symbol, etc.) and control information symbols, may be arranged in a frame in any way. Although the terms such as pilot symbols and control information symbols are used here, any terms may be used, and the functions per se are important.

For example, a pilot symbol is any known symbol modulated in a transmitter/receiver using PSK modulation (alternatively, the receiver may be able to know the symbol transmitted by the transmitter, through synchronization). The receiver performs frequency synchronization, time synchronization, channel estimation (channel state information (CSI) estimation) (of each modulated signal), signal detection, etc., using this symbol.

A control information symbol is a symbol for transmitting information (e.g. modulation scheme, error (loss) correction encoding scheme, encoding rate in error (loss) correction encoding scheme, upper layer setting information, etc. used in communication) that needs to be transmitted to the communication partner to realize communication of information (e.g. application) other than data.

The transmission device and the reception device need to be notified of a transmission method (MIMO, SISO, space-time block encoding, interleave scheme), a modulation scheme, an error correction encoding scheme, and a packet-level error (loss) correction scheme, although the description of this part is omitted in some embodiments. A symbol for transmitting these information is present in a frame transmitted by the transmission device, with the reception device obtaining the symbol and changing its operation.

The present disclosure is not limited to the above embodiments, and various modifications are possible. For example, although each of the above embodiments is carried out as a communication device, this is not a limitation, and its communication method may be realized as software.

INDUSTRIAL APPLICABILITY

A transmission method according to the present disclosure enables wireless transmission in a plurality of transmission devices using a millimeter wave frequency bandwidth, and so is useful as a wireless communication technique.

REFERENCE MARKS IN THE DRAWINGS