WO2017199307A1

WO2017199307A1 - Wireless transmitting station, wireless receiving station, and wireless communication system

Info

Publication number: WO2017199307A1
Application number: PCT/JP2016/064518
Authority: WO
Inventors: 長谷川　剛
Original assignee: 富士通株式会社
Priority date: 2016-05-16
Filing date: 2016-05-16
Publication date: 2017-11-23

Abstract

In a wireless communication system (1), a wireless transmitting station (2) may divide, in time domain, a temporally continuous signal waveform that is a wireless communication transmission unit, and transmit the divided signal waveforms separately in a plurality of temporally noncontinuous time periods. A wireless receiving station (3) may extract each of the divided signal waveforms from a signal received from the wireless transmitting station (2), and combine the extracted signal waveforms through timing adjustment so that the extracted signal waveforms are continuous in time domain.

Description

Radio transmitting station, radio receiving station, and radio communication system

The technology described in this specification relates to a radio transmission station, a radio reception station, and a radio communication system.

A new radio access technology (new radio access technology, new RAT) is being discussed for the realization of the fifth generation (5G) radio communication technology. In the new RAT, for example, with respect to the existing RAT in LTE (long term evolution), LTE-Advanced, etc., further higher communication speed, larger capacity, lower delay, etc. are required.

Special table 2011-51069 gazette JP 2012-151853 A Special Table 2004-53944

However, in the existing radio frame format, since the degree of freedom of the frame configuration is low, it may be difficult to reduce communication delay and improve the utilization efficiency of radio resources.

In one aspect, one of the objects of the technology described in this specification is to improve the degree of freedom of frame configuration, to reduce communication delay and to improve the utilization efficiency of radio resources.

In one aspect, the wireless transmission station may include a division unit and a transmission unit. The dividing unit may divide a temporally continuous signal waveform, which is a transmission unit of wireless communication, in the time domain. The transmission unit may transmit the divided signal waveform separately in a plurality of time intervals that are discontinuous in time.

Further, in one aspect, the radio reception station may include a receiving unit, an extracting unit, and a combining unit. The receiving unit may receive a signal from the wireless transmission station. The wireless transmission station may divide a temporally continuous signal waveform, which is a transmission unit of wireless communication, in a time domain, and transmit the divided signal waveform separately into a plurality of temporally discontinuous time intervals. The extraction unit may extract each of the divided signal waveforms from the signal received by the reception unit. The synthesizer may synthesize the extracted signal waveform by adjusting the timing so as to be continuous in the time domain.

Furthermore, in one aspect, the wireless communication system may include a wireless transmission station and a wireless reception station. The wireless transmission station may divide a temporally continuous signal waveform, which is a transmission unit of wireless communication, in a time domain, and transmit the divided signal waveform separately into a plurality of temporally discontinuous time intervals. . The radio reception station may extract the divided signal waveforms from the signal received from the radio transmission station, and synthesize the extracted signal waveforms by adjusting the timing so as to be continuous in the time domain.

As one aspect, it is possible to improve the degree of freedom of frame configuration, reduce communication delay, and improve the utilization efficiency of radio resources.

It is a block diagram which shows the structural example of the radio | wireless communications system which concerns on one Embodiment. It is a figure which shows the example of allocation of the radio | wireless resource in F-OFDM (filtered | Orthogonal | Frequency | Division | Multiplexing). It is a figure which shows typically the example by which a signal is filtered for every subband in F-OFDM. It is a figure which shows typically an example of the OFDM symbol accommodated in 1 frame. It is a figure which shows typically the 1st example of the transmission process which concerns on one Embodiment. It is a figure which shows typically the example of a transmission process in F-OFDM which concerns on one Embodiment. It is a figure which shows typically the example of a transmission process in F-OFDM which concerns on one Embodiment. It is a block diagram which shows the 1st structural example of the transmission process part which concerns on one Embodiment. It is a block diagram which shows the 2nd structural example (application example to F-OFDM) of the transmission process part which concerns on one Embodiment. (A)-(C) are the figures for demonstrating typically the 1st example of the reception process which concerns on one Embodiment. (A)-(D) are the figures for demonstrating typically the 1st example of the reception process which concerns on one Embodiment. It is a block diagram which shows the 1st structural example of the reception process part which concerns on one Embodiment. It is a figure which shows typically the 2nd example of the transmission process which concerns on one Embodiment. It is a block diagram which shows the 3rd structural example of the transmission process part which concerns on one Embodiment. It is a figure which shows typically the 4th example of the transmission process which concerns on one Embodiment. It is a figure which shows typically the 4th example of the transmission process which concerns on one Embodiment. It is a block diagram which shows the 4th structural example of the transmission process part which concerns on one Embodiment. (A)-(C) are the figures for demonstrating typically the 2nd example of the reception process which concerns on one Embodiment. It is a block diagram which shows the 2nd structural example of the reception process part which concerns on one Embodiment. It is a block diagram which shows the structural example of the base station as an example of the transmission station which concerns on one Embodiment. It is a block diagram which shows the structural example of the radio | wireless terminal as an example of the receiving station which concerns on one Embodiment.

Hereinafter, embodiments will be described with reference to the drawings. However, the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described below. Various exemplary embodiments described below may be implemented in combination as appropriate. Note that, in the drawings used in the following embodiments, portions denoted by the same reference numerals represent the same or similar portions unless otherwise specified.

FIG. 1 is a block diagram illustrating a configuration example of a wireless communication system according to an embodiment. The wireless communication system 1 illustrated in FIG. 1 may include a base station 2 and a wireless terminal 3 exemplarily. The base station 2 may be illustratively connected to the core network 4. In the example of FIG. 1, attention is focused on one base station 2 and one wireless terminal 3, but there are two or more base stations 2 and wireless terminals 3 in the wireless communication system 1. You can do it.

The wireless terminal 3 can wirelessly communicate with the base station 2 in a wireless area formed or provided by the base station 2. The “wireless terminal” may be referred to as “wireless device”, “wireless device”, “terminal device”, or the like.

The wireless terminal 3 may be a fixed terminal whose position does not change, or may be a mobile terminal (which may be referred to as a “mobile device”) whose position changes. As a non-limiting example, the wireless terminal 3 may be a mobile UE such as a mobile phone, a smartphone, or a tablet terminal. “UE” is an abbreviation for “User Equipment”.

The base station 2 forms or provides a wireless area 200 that enables wireless communication with the wireless terminal 3. The “wireless area” may be referred to as “cell”, “coverage area”, “communication area”, “service area”, and the like.

The base station 2 may be, for example, an “eNB” compliant with 3rd generation “partnership” project (3GPP) long term evolution (LTE) or LTE-Advanced (hereinafter collectively referred to as “LTE”).

“ENB” is an abbreviation for “evolved Node B”. Note that a communication point, which is called a remote radio unit (RRE), remote radio head (RRH), etc., which is separated from the base station main body and located at a remote location, may correspond to the base station 2.

The “cell” formed or provided by the base station 2 may be divided into “sector cells”. The “cell” may include a macro cell and a small cell. A small cell is an example of a cell having a radio wave coverage (coverage) smaller than that of a macro cell.

The name of the small cell may be different depending on the coverage area. For example, the small cell may be referred to as “femtocell”, “picocell”, “microcell”, “nanocell”, “metrocell”, “homecell”, and the like.

The core network 4 may include an MME 41, a PGW 42, and a PGW 43 as illustrated in FIG. “MME” is an abbreviation of “Mobility Management Entity”. “PGW” is an abbreviation for “Packet Data Gateway” and “SGW” is an abbreviation for “Serving Gateway”.

The core network 4 may be regarded as corresponding to an “upper network” for the base station 2. The MME 41, the PGW 42, and the SGW 43 may be regarded as corresponding to an element (NE) or an entity of the “core network”, and may be collectively referred to as a “core node”. The “core node” may be considered to correspond to the “upper node” of the base station 2.

The base station 2 may be connected to the core network 4 via an “S1 interface” which is an example of a wired interface. However, the base station 2 may be communicably connected to the core network 4 through a wireless interface.

A network including the base station 2 and the core network 4 may be referred to as a radio access network (RAN). An example of RAN is “Evolved Universal Terrestrial Radio Access Network, E-UTRAN”.

Further, the base station 2 may be communicatively connected to the MME 41 and the SGW 43, for example. For example, the base station 2 and the MME 41 and the SGW 43 may be communicably connected via an interface called an S1 interface.

The SGW 43 may be communicably connected to the PGW 42 through an interface called an S5 interface. The PGW 42 may be communicably connected to a packet data network (PDN) such as the Internet or an intranet.

User packets can be transmitted and received between the UE 3 and the PDN via the PGW 42 and the SGW 43. The user packet is an example of user data, and may be referred to as a user plane signal.

For example, the SGW 43 may process the user plane signal. The control plane signal may be processed by the MME 41. The SGW 43 may be communicably connected to the MME 41 via an interface called an S11 interface.

The MME 41 illustratively manages the location information of the UE 11. The SGW 43 may perform movement control such as path switching of a user plane signal accompanying movement of the UE 3 based on the position information managed by the MME 41, for example. The mobility control may include control associated with the handover of UE3.

Although not shown in FIG. 1, when there are a plurality of base stations 2 in the RAN, the base stations 2 are connected so as to be communicable by an interface between base stations called an X2 interface, for example. It's okay. The interface between base stations may be a wired interface or a wireless interface.

The radio area 200 formed by the eNB 2 which is an example of the base station 2 may be referred to as a “macro cell”. The eNB 2 forming the macro cell 200 may be referred to as “macro base station”, “macro eNB”, or “MeNB” for convenience. In the macro cell, a “small cell” having a smaller coverage than the macro cell may be arranged (overlaid).

ENB2 may control the setting (may be referred to as “allocation”) of radio resources used for radio communication with UE3. This control may be referred to as “scheduling”. Radio resources (hereinafter sometimes simply referred to as “resources”) may be two-dimensionally distinguished by a frequency domain and a time domain, for example.

The eNB 2 may allocate resources in units of a frequency / time grid in which radio resources that can be used for radio communication with the UE 3 are divided in two dimensions in the frequency domain and the time domain. Resource allocation may be referred to as “scheduling”. In LTE, the unit of scheduling is referred to as a “resource block (RB)”.

RB corresponds to one block obtained by dividing a radio lease that eNB 2 can use for radio communication with UE 3 into a slot in the time domain and a plurality of subcarriers (carrier waves) adjacent in the frequency domain.

For example, in LTE, one slot has a time length of 0.5 ms, two slots form one subframe of 1 ms length, and ten subframes form a radio frame of 10 ms length. The RB is represented by, for example, 2 slots (= 1 subframe) × 12 subcarriers.

For radio communication between the eNB 2 and the UE 3, either time division duplex (Time Division Duplex: TDD) or frequency division duplex (Frequency Division Duplex: FDD) may be applied.

In TDD, using one frequency (or frequency band), downlink (downlink, DL) communication and uplink (uplink, UL) communication are performed at different times.

For example, the eNB 2 schedules the time for DL communication and the time for UL communication at different times with respect to the UE 3 in one frequency band.

Therefore, the eNB 2 and the UE 3 perform transmission and reception at different times in one frequency band.

On the other hand, in FDD, DL communication and UL communication are performed using different frequencies (or frequency bands).

For example, the eNB 2 may schedule the frequency for DL communication and the frequency for UL communication to different frequencies regardless of the communication timing.

Therefore, the eNB 2 and the UE 3 can perform reception at a frequency different from the transmission frequency while performing transmission.

By the way, for the realization of the 5th generation (5G) radio communication technology, candidates for signal waveforms of new radio signals used for communication between the eNB 2 and the UE 3 are being discussed. For example, F-OFDM, UF-OFDM, and FBMC signal waveforms are listed as candidates.

Note that F-OFDM is an abbreviation for “filtered Orthogonal Frequency Division Multiplexing”, UF-OFDM is an abbreviation for “universal filtered OFDM”, and FBMC is an abbreviation for “Filter Bank Multi-Carrier”.

In both F-OFDM and UF-OFDM, filters are applied in units of “subbands” to be described later. On the other hand, in FBMC, a filter is applied in units of subcarriers.

In F-OFDM, a cyclic prefix (CP) is added to a symbol to suppress intersymbol interference. On the other hand, in UF-OFDM, no CP is added to symbols, and instead, inter-symbol interference is suppressed by inserting guard intervals (non-transmission intervals) between symbols.

FIG. 2 shows an example of radio resource allocation in F-OFDM (or UF-OFDM, the same shall apply hereinafter). In F-OFDM, for example, a certain frequency band (for example, all or a part of the system band) may be divided into a plurality of frequency bands # 1 to #n (n is an integer of 2 or more).

Each of the divided frequency bands (may be abbreviated as “divided band”) #i (i is any one of 1 to n) is referred to as “subband”, “subcarrier block”, or “cluster”. May be. FIG. 2 shows three subbands # 1 to # 3 as a non-limiting example.

Here, in F-OFDM, as schematically illustrated in FIG. 3, signal waveform shaping (in other words, filtering) may be performed for each subband #i. For example, a band pass filter (BPF) may be applied to the filtering.

Due to the filtering for each subband #i, the orthogonality between subcarriers may not be maintained between subbands #i, unlike normal OFDM. Therefore, it is allowed that the number of subcarriers, the subcarrier interval, the transmission time interval (transmission time interval, 等 TTI), and the like differ between subbands #i.

For example, between the subbands #i, the number of subcarriers, the number of symbols, the symbol length, the slot length, the radio frame length, the subframe length (in other words, TTI), and the like may be different. Within one subband #i, these parameters (sometimes referred to as “transmission parameters” for convenience) may be constant.

In other words, in F-OFDM, one or more of the number of subcarriers, the number of symbols, the symbol length, the slot length, the radio frame length, and the subframe length (TTI) is varied for each subband #i. It is acceptable.

Therefore, it is allowed to mix OFDM symbols having different numbers of subcarriers per OFDM symbol and different symbol lengths in a certain frequency band (for example, system band).

In the example of FIG. 2, in each of the subbands # 1 to # 3, it is considered that the frequency / time grids of different sizes surrounded by a thick frame correspond to one OFDM symbol (which may be referred to as “OFDM signal”). It's okay.

For example, the OFDM symbol of subband # 1 has a shorter symbol length and a smaller number of subcarriers than the OFDM symbols of other subbands # 2 and # 3. An OFDM symbol with a short symbol length may be used, for example, for UE3 whose radio propagation environment with eNB2 is likely to change with time, for example, for UE3 that moves at high speed.

On the other hand, the OFDM symbol of subband # 3 has a longer symbol length and a larger number of subcarriers than the OFDM symbols of other subbands # 2 and # 3 (in other words, subcarrier spacing). Is short).

The OFDM symbol of subband # 3 may be used for UE3 whose radio propagation environment does not change much in time, for example, UE3 moving at a low speed or fixed UE3. In addition, since the subcarrier interval per OFDM symbol is shorter than the other subbands # 1 and # 2, more UEs 2 can be efficiently accommodated in the subband # 3. Note that, for example, an IoT (Internet of Things) wireless device may correspond to the UE 3 that moves at a low speed or the fixed UE 3.

The subband # 2 OFDM symbol has an intermediate symbol length and number of subcarriers compared to the subband # 1 and subband # 3 OFDM symbols. The OFDM symbol of subband # 2 may be used for UE 2 having an average moving speed, for example.

As described above, F-OFDM can separate different parameters for each subband #i and coexist in a continuous frequency band by filtering, so that it is suitable for a plurality of UEs 3 in each radio environment. Parameters can be used.

A “symbol” is an example of a transmission unit in wireless communication, and has a signal waveform that is continuous in time. Since a symbol is exemplarily generated by digitally modulating one or more subcarriers with one or more transmission data signals, the “transmission unit” is rephrased as “modulation symbol unit” or “modulation unit”. Also good. Alternatively, since digital demodulation is performed in symbol units on the symbol receiving side, the “transmission unit” may be rephrased as “demodulation unit”.

The symbol length can be changed by changing the number of subcarriers to be digitally modulated. Therefore, the difference in the number of subcarriers and the symbol length per symbol means that the signal waveforms that are temporally continuous as transmission units are different.

Therefore, as described below, dividing one symbol in the time domain is equivalent to dividing a time-continuous signal waveform as a transmission unit in the time domain.

In the present embodiment, the waveform of the OFDM signal will be described as an example of the signal waveform divided in the time domain, but other signal waveforms may be used as long as they are signal waveforms used for wireless communication.

Non-limiting examples of other signal waveforms include the waveform of a signal to which an RRC (Root Raised Cosine) filter is applied and the waveform of an FBMC signal. The signal waveforms that are allowed to be mixed in a certain frequency band may be different types of signal waveforms, or may be signal waveforms having the same type but different types of transmission parameters. Different signal waveforms can be obtained by changing any one or more of the transmission parameters.

Allowing mixing of different signal waveforms in a certain frequency band means that a signal waveform belonging to one of the divided bands obtained by dividing the frequency band can be different from a signal waveform belonging to another divided band. .

For example, the waveform of the transmitted or received OFDM signal differs between subbands # 1 to # 3 illustrated in FIG.

By the way, in the 5G wireless communication technology, it is required to realize low-latency communication. Therefore, there is a request to shorten the TDD switching time (in other words, the switching time between UL communication and DL communication).

In order to shorten the switching time between the UL communication and the DL communication, for example, it is considered to shorten the DL communication time and the UL communication time (in other words, the length of the DL frame and the UL frame) in the TDD frame. Is done.

However, if the frame length is shortened, it may be difficult to mix OFDM symbols having different symbol lengths and subcarrier intervals as used in F-OFDM in one frame.

For example, as shown in (1) of FIG. 4, a TDD frame whose frame length is optimized so as to accommodate a maximum of five OFDM symbols having an average symbol length is assumed.

If an OFDM symbol having a longer symbol length than the OFDM symbol having an average symbol length is to be accommodated in the TDD frame, as illustrated in (2) of FIG. Cannot be accommodated.

As a non-limiting example, (2) in FIG. 4 shows an OFDM symbol having a symbol length twice as long as an OFDM symbol having an average symbol length. In this case, one TDD frame can accommodate, for example, only two symbols fewer than five symbols. If three symbols are to be accommodated, they will not fit in one TDD frame, and at least a part of the OFDM symbols will protrude from the TDD frame.

In order to accommodate 2 symbols, the length of CP added per OFDM symbol may be increased as illustrated in (3) of FIG. 4, but resource (for example, frequency) utilization efficiency is increased due to CP overhead. Decreases.

In FIG. 2, for simplicity of explanation, each symbol length is shown to be an integral multiple. However, since an actual OFDM symbol is added with a CP, as shown in FIG. The OFDM symbol length including the CP is not necessarily an integral multiple. For this reason, it is difficult to optimize the CP length while accommodating a plurality of OFDM symbols within a predetermined frame length.

(First example of transmission processing)
Therefore, in this embodiment, as schematically illustrated in FIG. 5, an OFDM symbol that does not fit in one frame is divided into two or more and divided OFDM symbols (for convenience, they may be referred to as “division symbols”). .) Is transmitted separately in a plurality of frames which are different in time. In other words, the divided symbols are transmitted across different frames in time.

In the example of FIG. 5, the third OFDM symbol that does not fit in the first frame is divided into two, and among the two divided symbols, the temporally preceding divided symbol is transmitted at the end of the first frame, and the subsequent division is performed. The symbol is transmitted at the beginning of the second frame.

This makes it possible to adjust the number of accommodated symbols over a plurality of frames without greatly adjusting the CP length per symbol, thereby improving the degree of freedom of the frame configuration.

Therefore, for example, even when the existing frame length cannot be changed or when the frame length is limited to be short for communication delay, signals having different symbol lengths are transmitted while efficiently using resources. Is possible.

Note that the first frame and the second frame in which the divided symbols are accommodated separately may be frames that are not temporally continuous as illustrated in FIG. In other words, the divided symbols may be transmitted separately in time intervals that are discontinuous in time.

For example, in FIG. 5, for example, one or more frames may be interposed between the first frame and the second frame. As one non-limiting example, as shown in FIGS. 6 and 7, one or more received frames (for example, UL frames) are set between the first and second transmission frames (for example, DL frames). May be.

For example, when DL transmission is performed in a different subband #j (j is an integer from 1 to n satisfying j ≠ i) during a UL reception period in a certain subband #i, the DL transmission is performed. The reception quality of UL may deteriorate due to interference with UL reception.

Therefore, as illustrated in FIGS. 6 and 7, the TDD frame may be configured so that UL reception and DL transmission are not performed at the same time between different subbands # i- # j. In such a case, one or more UL frames may be set between the first DL frame and the second DL frame.

6 shows an example in which subbands #i and #j are discontinuous (in other words, not adjacent) in the frequency domain, and FIG. 7 shows that subbands #i and #j are continuous in the frequency domain. An example (in other words, adjacent) is shown.

5 to 7 are examples in which the divided symbols divided into two are transmitted separately in two temporally discontinuous frames. However, a part of divided symbols divided into three or more or All may be transmitted separately in three or more frames that are discontinuous in time.

(First configuration example of transmission processing unit)
FIG. 8 is a block diagram illustrating a first configuration example of the transmission processing unit 20 capable of realizing the OFDM symbol division transmission described with reference to FIG. The transmission processing unit 20 may be provided in the eNB 2 as an example. The eNB 2 including the transmission processing unit 20 may be regarded as an example of a radio transmission station (sometimes abbreviated as “transmission station”).

As illustrated in FIG. 8, the transmission processing unit 20 exemplarily includes a transmission symbol generation unit 21, a switch (SW) 22, a wireless transmission unit 23, a symbol division unit 24, a BPF 25, a timing adjustment unit 26, and an antenna 27. May be provided.

In FIG. 8, reference numeral 51 denotes a control unit that controls the operation of the transmission processing unit 20. The control unit 51 may be provided in a wireless device (for example, eNB 2) provided with the transmission processing unit 20.

The transmission symbol generation unit 21 exemplarily generates an OFDM symbol as an example of a transmission symbol. A transmission symbol is an example of a transmission signal.

The switch 22 illustratively switches the output destination of the transmission symbol generated by the transmission symbol generation unit 21 to one of the radio transmission unit 23 and the symbol division unit 24 according to control from the control unit 51.

For example, if division of the OFDM symbol is not necessary, the output destination of the switch 22 is switched to the wireless transmission unit 23 side. Therefore, the OFDM symbol is output to the wireless transmission unit 23 and transmitted from the antenna 27 as usual without being divided.

On the other hand, if the OFDM symbol does not fit into a predetermined frame unless it is divided, the output destination of the switch 22 is switched to the symbol division unit 24 side, and the OFDM symbol is output to the symbol division unit 24.

The symbol dividing unit 24 exemplarily divides the OFDM symbol as described in FIG. The number of divisions may be two or more.

The BPF 25 may be referred to as a divided transmission BPF 25, and may have a BPF characteristic according to the bandwidth of the transmission frequency band. The BPF 25 may individually filter the divided symbols input from the symbol dividing unit 24 using the BPF characteristics.

Note that the transmission frequency band may illustratively correspond to one of the subbands #i. By filtering each of the divided symbols in the BPF 25, it is possible to suppress the expansion of the frequency band due to the symbol division.

The timing adjustment unit 26 exemplarily adjusts the timing between the divided symbols so that the divided symbols filtered by the BPF 25 are transmitted in different transmission frames as illustrated in FIG.

The wireless transmission unit 23 illustratively up-converts the OFDM symbol input from the switch 22 or the timing adjustment unit 26 into a wireless signal and transmits it from the antenna 27.

The timing adjustment unit 26 and the wireless transmission unit 23 are an example of a transmission unit that transmits divided symbols in a plurality of temporally discontinuous time intervals.

Note that, as exemplified by a dotted line in FIG. 8, the non-divided OFDM symbol may be filtered by the BPF 25 for normal transmission (non-divided transmission) provided in the previous stage of the wireless transmission unit 23.

The BPF 25 for normal transmission may exemplarily have a BPF characteristic equivalent to the BPF 25 for divided transmission. However, the BPF 25 for normal transmission filters undivided OFDM symbols with the BPF characteristic.

(Application example to F-OFDM)
As illustrated in FIG. 6 and FIG. 7, when performing OFDM symbol division transmission in F-OFDM, the transmission processing unit 20 may be configured as illustrated in FIG. The configuration example illustrated in FIG. 9 corresponds to a second configuration example of the transmission processing unit 20. In FIG. 9, the same reference numerals as those in FIG. 8 are the same or similar to the same reference numerals in FIG. 8 unless otherwise specified.

In the example of FIG. 9, the configuration for split transmission illustrated in FIG. 8 (for example, the switch 22, the symbol splitting unit 24, and the timing adjustment unit 26) is applied to the subband #n. . However, the configuration for split transmission is not limited to subband #n, and may be applied to at least part of subbands # 1 to #n.

In the example of FIG. 9, the transmission processing unit 20 may include, for example, BPFs 25-1 to 25-n corresponding to the subbands # 1 to #n. Two BPFs 25-n corresponding to subband #n may be provided for normal transmission and divided transmission.

Each BPF 25-i has a BPF characteristic corresponding to the bandwidth of the corresponding subband #i, and filters the input OFDM symbol with the BPF characteristic.

The transmission symbol generator 21 generates OFDM symbols of subbands # 1 to #n. The OFDM symbols of subbands # 1 to # (n−1) excluding subband #n are input to corresponding BPFs 25-1 to 25- (n−1), respectively. The OFDM symbol of subband #n is illustratively input to switch 22.

For example, according to the control from the control unit 51, the switch 22 sets the output destination of the OFDM symbol input from the transmission symbol generation unit 21 to either the BPF 25-n for normal transmission or the symbol division unit 24. Switch.

For example, if it is not necessary to divide OFDM symbols for subband #n, the OFDM symbols are output to BPF 25-n for normal transmission. On the other hand, if the OFDM symbol is not divided for subband #n and does not fit in the predetermined frame, the OFDM symbol is output to symbol division section 24.

The symbol dividing unit 24 divides the input OFDM symbol, for example, as illustrated in FIG. 6 and FIG. The number of divisions may be two or more.

The BPF 25-n for division transmission, for example, individually filters the division symbols input from the symbol division unit 24.

The timing adjustment unit 26 exemplifies the interval between the divided symbols so that the divided symbols filtered by the BPF 25-n for divided transmission are transmitted in different transmission frames as illustrated in FIG. 6 and FIG. Adjust the timing.

In this way, the divided symbols transmitted in the subband #n frame are individually filtered by the divided transmission BPF 25-n, and then transmitted by the timing adjustment unit 26 in temporally different frames. The timing is adjusted as follows.

The OFDM symbols (which may include divided symbols) of each of the subbands # 1 to #n are exemplarily added (may be referred to as “multiplexing”) by the adder 28, and are described above. It is transmitted from the antenna 27 through the wireless transmission unit 23.

(First example of reception processing)
Next, reception processing of the OFDM symbol divided and transmitted as described above will be described. The reception process may illustratively correspond to a reception process at UE3.

As schematically illustrated in FIG. 10A, in the transmission processing unit 20 described above, an OFDM symbol that does not require division is transmitted as it is (non-division transmission).

On the other hand, as schematically illustrated in FIG. 10B, in the transmission processing unit 20, the OFDM symbols subjected to symbol division are individually transmitted in temporally different frames.

In the reception process, as schematically illustrated in FIG. 10C, when the received divided symbols are synthesized by adjusting the timing so that they are temporally continuous (for example, addition), they are substantially the same as in non-divided transmission. An equivalent signal waveform is obtained.

Therefore, the OFDM symbol restored by combining can be correctly demodulated by a demodulation process equivalent to the demodulation process for a normal OFDM symbol of non-division transmission illustrated in FIG.

However, it is assumed that the received divided symbols do not include noise due to filtering or have a noise level that does not affect restoration even if included. Further, it is assumed that the radio propagation path (also referred to as “channel”) of the divided symbols does not change with time, or changes that do not affect restoration even if they change.

Note that even if the divided symbols are individually demodulated individually, the orthogonality between the sub-carriers is not maintained with the divided symbols alone, which is significantly different from the demodulation result of a normal OFDM symbol. As a result, reception characteristics (may be referred to as “reception quality”) deteriorate.

Also, the examples of FIGS. 10A to 10C do not consider the time response of filtering applied to the OFDM symbol (hereinafter sometimes referred to as “filter time response”). An example of the reception process considering the filter time response is shown in FIGS. 11 (A) to 11 (D).

As schematically illustrated in FIGS. 11A and 11B, in the transmission processing unit 20 described above, the OFDM symbol that does not need to be divided has a bandwidth of a transmission frequency band as a whole. The corresponding filtering is performed and transmitted (non-divided transmission).

Therefore, in the OFDM symbol of non-division transmission, a “round” of the signal waveform corresponding to the filter time response occurs as a whole OFDM symbol.

On the other hand, in the transmission processing unit 20, the OFDM symbols that are divided into symbols are filtered for each divided symbol and transmitted as schematically illustrated in FIG. Therefore, a “round” of the signal waveform corresponding to the filter time response occurs for each divided symbol.

However, in the reception process, as schematically illustrated in FIG. 11D, the received divided symbols are adjusted in timing so as to be temporally continuous, and are synthesized (for example, added) including the time waveform of the filter time response. ), A signal waveform substantially equivalent to that in non-divided transmission can be obtained. If OFDM symbol filtering is performed on both the transmitting side and the receiving side, the filter time response may be a combination of both filter time responses.

Therefore, the OFDM symbol restored by combining can be correctly demodulated by the demodulation processing equivalent to the demodulation processing for the normal OFDM symbol of non-division transmission illustrated in FIG.

However, in the examples of FIGS. 11A to 11D as well, as in the examples of FIGS. 10A to 10C, the received divided symbols include noise due to filtering. It is assumed that the noise level does not affect the restoration even if it is included. Further, it is assumed that the radio propagation path of the divided symbols (hereinafter may be abbreviated as “propagation path”) does not change with time, or changes that do not affect the restoration even if they change.

(First configuration example of reception processing unit)
FIG. 12 is a block diagram illustrating a first configuration example of the reception processing unit 30 capable of realizing the above-described reception processing. The reception processing unit 30 may be provided in the UE 3 as an example. The UE 3 provided with the reception processing unit 30 may be regarded as an example of a radio reception station (sometimes abbreviated as “reception station”).

As illustrated in FIG. 12, the reception processing unit 30 exemplarily includes an analog-to-digital converter (ADC) 31, a divided symbol extraction unit 32, a timing adjustment / synthesis (addition) unit 33, and a demodulation processing unit 34. May be provided.

The ADC 31 converts the received signal into a digital signal. For example, the received digital signal may be input to the divided symbol extraction unit 32 and the demodulation processing unit 34.

The division symbol extraction unit 32 illustratively extracts a division symbol from the digital signal input from the ADC 31. As illustrated in FIGS. 5 to 7, the divided symbols are accommodated at the end or the beginning of a temporally different frame, and can be detected based on the frame timing. The frame timing can be detected, for example, by establishing frame synchronization between the eNB 2 and the UE 3.

As illustrated in FIGS. 10B and 10C, FIG. 11C, and FIG. 11D, the timing adjustment / combination unit 33 determines the divided symbols extracted by the divided symbol extraction unit 32 as follows. The timing is adjusted so that it is continuous in time. As a result, the original OFDM symbol before division is restored.

For example, the demodulation processing unit 34 demodulates the OFDM symbol restored by the timing adjustment / combination unit 33 in the same manner as the demodulation of a normal OFDM symbol for non-division transmission.

Note that a normal OFDM symbol for non-division transmission may be demodulated as usual by the demodulation processing unit 34 through a route that does not pass through the division symbol extraction unit 32 and the timing adjustment / synthesis unit 33 from the ADC 31.

(Second example of transmission processing)
FIG. 13 is a diagram illustrating a second example of transmission processing. The second example of the transmission process may be considered to correspond to a modification of the first example of the transmission process illustrated in FIGS. As illustrated in FIG. 13, a part of the divided symbols may be transmitted in duplicate in frames that are temporally different.

For example, a part of the first division symbol transmitted in a certain frame may be redundantly transmitted in the other frame together with the second division symbol transmitted in another temporally different frame.

For example, in FIG. 13, a part may be copied from the beginning of the divided symbol transmitted in the second frame, and the copy part may be set at the end of the divided symbol transmitted in the first frame.

Alternatively, conversely, a part may be copied from the end of the divided symbol transmitted in the first frame, and the copy part may be set at the beginning of the divided symbol transmitted in the second frame.

The partial copying of the divided symbols may be performed by the symbol dividing unit 24 illustrated in FIGS. 8 and 9 exemplarily. For example, the setting of the copy portion to a different frame may be performed by the timing adjustment unit 26 illustrated in FIGS. 8 and 9. By demodulating the overlapping part at the time of demodulation on the receiving side, the demodulation process can be performed in the same manner as in FIG.

In this way, by allowing a part of the divided symbols to be transmitted in duplicate, the degree of freedom of the frame configuration can be improved.

(Third example of transmission processing)
When transmitting divided symbols in temporally different frames, the propagation path environment may change for each divided symbol. Here, in TDD communication, since the transmission / reception propagation path has objectivity, for example, the propagation path characteristic of the transmission signal may be estimated from the propagation path characteristic of the reception signal.

Therefore, for example, the eNB 2 may estimate the DL propagation path characteristic (in other words, channel estimation) based on the propagation path characteristic of the UL signal received from the UE 3. For channel estimation, a known signal between the eNB 2 and the UE 3 such as a reference signal or a pilot signal may be used.

In addition, UE3 may report the propagation path characteristic of DL to eNB2. For example, the UE 3 may perform DL channel estimation based on a DL reference signal, a pilot signal, or the like, and transmit and report the estimation result to the eNB 2.

The eNB 2 may give in advance a phase rotation that cancels the phase rotation that the divided symbol receives in the DL propagation path for each divided symbol based on the DL radio path characteristics.

For example, the phase rotation given in advance for each divided symbol may be varied by controlling the filter parameters of the BPF 25 and BPF 25-n for divided transmission in the transmission processing unit 20 illustrated in FIGS. . The control of the filter parameters may be performed by the control unit 51, for example.

Alternatively, as shown in the third configuration example of the transmission processing unit 20 in FIG. 14, the transmission processing unit 20 includes a plurality of filters 25a-1 to 25a-m that can give different phase rotation amounts to the input signal. In addition, the filters 25a-k to be passed may be changed for each divided symbol.

Each of the filters 25a-k may be a BPF. “M” represents an integer of 2 or more, and “k” is any one of 1 to m. The filters 25a-k that pass the divided symbols may be selected and controlled by the control unit 51, for example.

The third example of the transmission process described above may be implemented in combination with the second example of the transmission process described with reference to FIG.

(Fourth example of transmission processing)
As schematically illustrated in FIG. 15, the divided symbols may be multiplexed and transmitted on different frequencies (for example, subband #i). FIG. 15 shows an example in which the divided symbols are multiplexed in different subbands #i of the same frame. For example, as schematically shown in FIG. 16, different subbands of temporally different frames are shown. Divided symbols may be multiplexed on band #i.

In order to realize the transmission processing illustrated in FIGS. 15 and 16, for example, as illustrated in FIG. 17, in the configuration of the transmission processing unit 20 illustrated in FIG. 9, the BPF 25-n for divided transmission, the timing adjustment unit 26, In the meantime, a frequency shifter 29 is provided. Note that the configuration example illustrated in FIG. 17 corresponds to a fourth configuration example of the transmission processing unit 20.

The frequency shifter 29 can change the transmission frequency (for example, subband #i) for each divided symbol. At the time of demodulation on the receiving side, demodulation processing can be performed in the same manner as in FIGS. 10 to 12 by passing the frequency shifter corresponding to each frequency.

In this way, by allowing the divided symbols to be transmitted by dividing them into different frequencies, the degree of freedom of the frame configuration can be further improved.

The fourth example of the transmission process described above may be implemented in combination with one or both of the second example of the transmission process described with reference to FIG. 13 and the third example of the transmission process described with reference to FIG. Good.

(Second example of reception processing)
As schematically illustrated in FIGS. 11A to 11D, when extracting and synthesizing the divided symbols in the reception process, all time waveforms including a portion spread by the filter time response are extracted. In some cases, noise components may be combined with signal components. When the noise components are combined, the reception quality of the OFDM symbol may deteriorate.

Therefore, when the presence of a noise component is expected, the ratio of the noise component is considered to be large in the portion widened by the filter time response, as schematically illustrated in FIGS. 18 (A) to 18 (C). Some time waveforms may be excluded from the candidates for extraction and synthesis of divided symbols. In other words, a portion that is considered to have a large ratio of noise components may be cut out from the portion that has spread due to the filter time response.

Thereby, when the timing adjustment / synthesis unit 33 synthesizes the divided symbols, it can be avoided or suppressed that the noise components are synthesized and the signal quality of the OFDM symbol is deteriorated.

Note that the selection and determination of the cutout portion in the time domain of the divided symbols to be included in the candidate for synthesis (or excluded from the candidates for synthesis) may be performed in the extraction process in the divided symbol extraction unit 32, or the timing It may be implemented in the synthesis process in the adjustment / synthesis unit 33.

(Third example of reception processing)
The longer the transmission interval of the divided symbols, the higher the possibility that the propagation path environment of each divided symbol changes. If the propagation environment varies for each divided symbol, divided symbols having different propagation environments are combined in the reception process, so that the restoration accuracy of the original OFDM symbol is lowered, and as a result, reception characteristics can be lowered.

Therefore, in the reception processing, for example, the synthesis may be performed after performing equalization processing of the propagation path for each divided symbol.

FIG. 19 shows a configuration example (second configuration example) of the reception processing unit 30 according to this example. The configuration example illustrated in FIG. 19 is a case where the number of OFDM symbol divisions in the transmission process is 2, for example, two division symbol extraction units 32-1 and 32-2 corresponding to the number of symbol divisions, 2 Two equalizers 35-1 and 35-2 are provided. If the number of symbol divisions is 3 or more, the reception processing unit 30 may be provided with three or more sets of divided symbol extraction units and equalizers.

The divided symbol extraction units 32-1 and 32-2 each extract a divided symbol from the received signal converted into a digital signal by the ADC 31. The division symbol extraction may be performed in the same manner as the division symbol extraction unit 32 illustrated in FIG.

The equalizer 35-1 equalizes the divided symbols extracted by the divided symbol extractor 32-1, and the equalizer 35-2 equalizes the divided symbols extracted by the divided symbol extractor 32-2.

After the equalization processing by the equalizers 35-1 and 35-2, the divided symbols are synthesized by the timing adjustment / synthesis unit 33 with the timing adjusted as described above, and the demodulation processing unit 34 performs the demodulation processing as usual. Is done.

In this way, by performing equalization processing for each divided symbol and then combining each divided symbol with timing adjustment, even if the propagation environment fluctuates for each divided symbol, the OFDM symbol restoration accuracy in reception processing is reduced. Can be avoided or suppressed. Therefore, it is possible to avoid or suppress a decrease in reception characteristics of the OFDM symbol.

Note that the third example of the reception process described above may be implemented in combination with the second example of the reception process described with reference to FIGS. 18A to 18C.

(Configuration example of transmitting station)
FIG. 20 is a block diagram illustrating a configuration example of the eNB 2 that is an example of a transmission station. 20 may be considered to correspond to a configuration example in which the transmission processing unit 20 illustrated in FIG. 8 is applied to the eNB 2.

As illustrated in FIG. 20, the eNB 2 includes an error correction encoding unit 211, a modulation unit 212, an inverse fast Fourier transformer (IFFT) 213, and a CP adder 214 as an example of the transmission symbol generation unit 21. Good.

The eNB 2 includes the switch 22, the radio transmission unit 23, the symbol division unit 24, the BPF 25, the timing adjustment unit 26, and the control unit 51, and also includes a DAC (Digital-to-Analog Converter) 22A. Good.

The error correction coding unit 211 illustratively performs error correction coding on the transmission data signal. As a non-limiting example, a convolutional code such as a turbo code may be applied to the error correction code.

The modulation unit 212 illustratively modulates a transmission data signal that has been subjected to error correction coding. In the case of OFDM or F-OFDM, a plurality of subcarriers may be modulated by different transmission data signals.

As a non-limiting example, QPSK or multi-level QAM may be applied to the modulation scheme (may be referred to as “modulation format”). QPSK is an abbreviation for “quadrature phase shift keying”, and QAM is an abbreviation for “quadrature amplitude modulation”. The multilevel value of QAM may illustratively be 16, 64, 128, 256, or the like. A transmission symbol represented by complex data is generated by modulation of the transmission data signal.

The IFFT 213 converts, for example, a transmission symbol sequence for each subcarrier obtained by the modulation unit 212 into a time-domain signal sequence by performing inverse fast Fourier transform. Note that IFFT 213 may be replaced by an inverse discrete Fourier transformer (IDFT).

CP adder 214 illustratively adds a CP in the time domain to the transmission symbol sequence in the time domain obtained by IFFT 214. Note that CP may be referred to as a guard interval (GI). By adding a CP, it is possible to reduce intersymbol interference and improve multipath tolerance.

A transmission symbol to which a CP is added (in other words, an OFDM symbol) is output to the switch 22, and the output destination of the switch 22 is controlled by, for example, the control unit 51 as described above, so that normal transmission and divided transmission are performed. And can be switched.

In response to the switching of the output destination of the SW 22, the OFDM symbol during normal transmission or the divided symbol during divided transmission is selectively input to the DAC 22A (in other words, time division). The DAC 22 </ b> A converts an input symbol that is a digital signal into an analog signal and outputs the analog signal to the wireless transmission unit 23.

The wireless transmission unit 23 may be provided with a high power amplifier (HPA) 231. The HPA 231 amplifies the analog signal input from the DAC 22A to a specified transmission power and outputs the amplified signal to the antenna 27. The transmission power may be controlled by the control unit 51, for example. The control of the transmission power may be performed by controlling the amplification gain of the HPA 231, for example.

In the configuration illustrated in FIG. 20, instead of the configuration corresponding to the transmission processing unit 20 illustrated in FIG. 8, any one or more of the transmission processing units 20 illustrated in FIG. 9, FIG. 14, and FIG. A configuration may be applied.

(Configuration example of receiving station)
FIG. 21 is a block diagram illustrating a configuration example of the UE 3 that is an example of a receiving station. FIG. 21 may be regarded as corresponding to a configuration example in which the reception processing unit 30 illustrated in FIG. 12 is applied to the eNB 2.

As illustrated in FIG. 21, the UE 3 exemplarily includes the antenna 31, the radio reception unit 37, the BPF 38, and the demodulation / decoding process in addition to the ADC 31, the divided symbol extraction unit 32, and the timing adjustment / synthesis unit 33 described above. A unit 34A and a channel estimation unit 39 may be provided.

The antenna 36 illustratively receives a DL radio signal transmitted by the eNB 2 which is an example of a transmission station, and outputs the DL radio signal to the radio reception unit 37.

The radio reception unit 37 amplifies the radio signal input from the antenna 36 by, for example, a low noise amplifier (LNA) 371 and then down-converts the radio signal to a baseband signal.

The BPF 38 may have a BPF characteristic corresponding to the bandwidth of the reception frequency band. The BPF 38 may filter the signal input from the wireless reception unit 37 with the BPF characteristic. The received frequency band may illustratively correspond to one of subband #i.

The received signal filtered by the BPF 38 is input to the ADC 31 and converted into a digital signal. The received digital signal obtained by the ADC 31 may be input to the divided symbol extraction unit 32 and the demodulation / decoding processing unit 34A.

The operations of the divided symbol extraction unit 32 and the timing adjustment / synthesis unit 33 are as described above.

The demodulator / decoder processor 34A may include a CP remover 341, a fast Fourier transformer (FFT) 342, a demodulator 343, and an error correction decoder 344, as illustrated in FIG.

The CP remover 341 illustratively removes the CP added to the received digital signal (eg, OFDM symbol or divided symbol) input from the ADC 31 or the timing adjustment / synthesis unit 33.

The FFT 342 illustratively converts the signal sequence from which the CP is removed into a frequency domain signal sequence by performing a fast Fourier transform. Note that the FFT 342 may be replaced with a discrete Fourier transformer (DFT).

The demodulator 343 illustratively demodulates the received signal sequence in the frequency domain input from the FFT 342 in a demodulation scheme corresponding to the modulation scheme in the transmission station 2, for example, for each subcarrier. For example, a received data symbol sequence for each subcarrier is obtained by demodulation.

The channel estimation value obtained by the channel estimation unit 39 may be used for demodulation. For example, the channel estimation unit 39 estimates a channel state with the transmitting station 2 based on a reference signal or a pilot signal mapped to a predetermined subcarrier to obtain a channel estimation value.

The error correction decoding unit 344 exemplarily performs error correction decoding on the received data symbol sequence input from the demodulation unit 343 by a decoding method corresponding to the error correction encoding method in the transmission station 2.

In the case of F-OFDM, for example, the configuration after BPF 38 may be regarded as corresponding to one subband #i. In other words, it may be considered that the configuration after the BPF 38 is provided in the receiving station 3 in parallel for each subband.

21, the configuration of the reception processing unit 30 illustrated in FIG. 19 may be applied instead of the configuration corresponding to the reception processing unit 30 illustrated in FIG. 12.

The eNB 2 illustrated in FIG. 20 may have a configuration corresponding to the reception system of the UE 3 illustrated in FIG. 21 as an example of the reception system. The UE 3 illustrated in FIG. 21 is illustrated in FIG. 20 as an example of the transmission system. A configuration corresponding to the transmission system of the eNB 2 may be provided.

However, the reception system of the eNB 2 may not include the divided symbol extraction unit 32 and the timing adjustment / synthesis unit 33 illustrated in FIG. Also, the transmission system of the UE 3 may not include the switch 22, the symbol division unit 24, the BPF 25 for division transmission, and the timing adjustment unit 26 illustrated in FIG.

1 wireless communication system 2 base station (eNB)
20 Transmission Processing Unit 21 Transmission Symbol Generation Unit 211 Error Correction Coding Unit 212 Modulation Unit 213 IFFT
214 CP Adder 22 Switch (SW)
22A DAC
23 Wireless transmission unit 24 Symbol division unit 25, 25-1 to 25-n BPF
25a-1 to 25a-m filter 26 timing adjustment unit 27 antenna 28 adder 29 frequency shifter 3 radio terminal (UE)
30 reception processing unit 31 ADC
32, 32-1, 32-2 Division symbol extraction unit 33 Timing adjustment / combination (addition) unit 34 Demodulation processing unit 34A Demodulation / decoding processing unit 341 CP remover 342 FFT
343 Demodulator 344 Error correction decoder 35-1, 35-2 Equalizer 36 Antenna 37 Wireless receiver 371 HPA
38 BPF
39 Channel estimation unit 4 Core network 41 MME
42 PGW
43 SGW
51 Control unit 200 Wireless area

Claims

A division unit that divides a time-continuous signal waveform, which is a transmission unit of wireless communication, in a time domain;
A transmitter that transmits the divided signal waveform separately in a plurality of temporally discontinuous time intervals;
A wireless transmitter station.
The transmitter is
The radio transmission station according to claim 1, wherein a part of the divided signal waveform is transmitted in a time interval different from a time interval in which the signal waveform is transmitted.
The wireless transmission station according to claim 1 or 2, further comprising a filter that individually filters each of the divided signal waveforms.
The filter has a characteristic of individually canceling in advance a phase rotation that each of the divided signal waveforms receives in a radio propagation path by transmitting the divided signal waveforms separately in the discontinuous time interval. Item 4. The wireless transmission station according to Item 3.
The signal waveform that is temporally continuous as the transmission unit of the wireless communication is a signal waveform that belongs to one of a plurality of divided bands obtained by dividing a certain frequency band in the frequency domain, and a signal that belongs to another divided band. The wireless transmission station according to any one of claims 1 to 4, wherein the wireless transmission station has a waveform different from the waveform.
The radio transmission station according to any one of claims 1 to 5, wherein the transmission unit is a unit of a modulation symbol obtained by digitally modulating one or more carriers with one or more transmission data signals.
The wireless transmission station according to any one of claims 1 to 6, wherein the transmission unit transmits the divided signal waveforms at different frequencies.
The signal waveform is a waveform of an OFDM (Orthogonal Frequency Division Multiplexing) signal, a waveform of a signal to which an RRC (Root Raised Cosine) filter is applied, or a waveform of an FBMC (Filter Bank Multi-Carrier) signal. 8. The wireless transmission station according to any one of 1 to 7.
A signal waveform that is continuous in time, which is a transmission unit of wireless communication, is divided in a time domain, and a signal is received from a wireless transmission station that transmits the divided signal waveform in a plurality of time intervals that are discontinuous in time. A receiver,
An extraction unit for extracting each of the divided signal waveforms from the signal received by the reception unit;
A combining unit that adjusts the timing so that the extracted signal waveform is continuous in the time domain; and
A wireless receiver station.
The extraction unit includes:
The radio reception station according to claim 9, wherein the divided signal waveform is extracted including the entire time response waveform of filtering applied to each of the divided signal waveforms.
The extraction unit includes:
The radio receiving station according to claim 9, wherein the divided signal waveform is extracted by excluding a part of a widened portion of a time response waveform of filtering applied to each of the divided signal waveforms.
12. The radio receiving station according to claim 9, further comprising an equalizer that individually equalizes each of the divided signal waveforms extracted by the extraction unit and outputs the equalized signal waveforms to the synthesis unit.
A radio transmission station that divides a time continuous signal waveform, which is a transmission unit of wireless communication, in a time domain, and transmits the divided signal waveform separately in a plurality of time discontinuous time sections;
Each of the divided signal waveforms is extracted from the signal received from the wireless transmission station, and the extracted signal waveform is synthesized by adjusting the timing so as to be continuous in the time domain, and
A wireless communication system comprising: