JP6752754B2 - Wireless network system and communication method - Google Patents

Description

The present invention is an asymmetric wireless network system and communication composed of a macro base station that forms a macro cell and performs vertical communication under the control of an accommodation station, and a small cell base station that forms a small cell in the macro cell and performs downlink communication. Regarding the method.

Conventionally, a HetNet type wireless communication system that uses a macro cell for uplink communication from a terminal to a terminal in a small cell area and a small cell for downlink communication from the accommodation station to the terminal, and a PON (Passive Optical) for a wireless access line. A system to which Network) is applied has been proposed. Further, in wireless access systems of 5G or later, the number of small cell base stations (hereinafter referred to as small cell stations) using high frequencies such as millimeter waves is expected to increase as the wireless communication speed increases. For example, Non-Patent Document 1 discloses a technique of using different cells for uplink / downlink communication.

[1] Performance evaluation of DL only TDD frame configuration in B-5-43 LTE-Advanced (B-5. Wireless communication system A (mobile communication), general session) Proceedings of the IEICE Society Conference 2015_Communication (1), 305, 2015-08-25

When constructing an access line for a small cell station deployed at high density, TDM-PON is introduced in the access line from the small cell station to the accommodation station for the purpose of reducing the cost of the access line. In the future, with the further increase in small cell stations for 5G and beyond, the issue is how to construct an access line to the small cell stations at low cost. In order to realize cost reduction, it is necessary to apply a PON system. However, when a PON system is used, MPCP (Multi-Point Control Protocol), which is a protocol in the vertical direction, and an uplink scheduling function (DBA: Dynamic Bandwidth Allocation) are required, and a function to handle these is essential. It costs a minute. Further, in PON, when data is randomly transmitted from ONU to OLT, the data collides on the transmission path and the data cannot be demodulated by OLT. Therefore, the above-mentioned MPCP is used to control the transmission timing of ONU. There is a need to. Due to this control, in PON, a transmission delay occurs in uplink data communication.

Note that Non-Patent Document 1 does not describe the access line of each base station constituting the cell.

The present invention has been made in view of such circumstances, and is a macro base station that forms a macro cell and performs vertical communication under the control of an accommodation station, and a small cell that forms a small cell in the macro cell and performs downlink communication. An object of the present invention is to provide an asymmetric wireless network system composed of cell base stations.

(1) In order to achieve the above object, the present invention has taken the following measures. That is, the wireless network system of the present invention has a macro base station that forms a macro cell and a plurality of small cell base stations that form small cells within the macro cell under the control of the accommodation station, and the accommodation station and each of the above. A small cell base station is connected in a star shape via an optical branching device, and a terminal device in the area in one of the small cells performs downlink communication using the small cell, while uplink is performed using the macro cell. An asymmetric wireless network system configured to perform communication, the first relay device provided in the accommodation station and a plurality of second relay devices provided in each of the small cell base stations. When the accommodating station determines that the terminal device that is performing wireless communication with the macro base station is capable of data communication with the small cell base station, the accommodating station informs the first relay device. The downlink data is transmitted, the first relay device transmits downlink data to the terminal device via the second relay device, and the terminal device receives downlink data from the second relay device, while the said It is characterized in that control information including a data transmission request and uplink data are transmitted to the accommodation station via a macro base station.

As described above, the wireless network system includes a first relay device provided in the accommodation station and a plurality of second relay devices provided in each small cell base station, and the accommodation station is a macro base station. When the terminal device performing wireless communication determines that data communication with the small cell base station is possible, downlink data is transmitted to the first relay device, and the first relay device is the second. The downlink data is transmitted to the terminal device via the relay device, and the terminal device receives the downlink data from the second relay device, while accommodating the control information including the data transmission request and the uplink data via the macro base station. Since the data is transmitted to the station, the MPCP and uplink scheduling functions, which are the vertical protocols required when using the conventional PON system, are no longer required, and the first and second relay devices can be realized with a simple circuit configuration. It will be possible. As a result, the access line can be constructed at low cost. Further, since the uplink communication is performed via the macro base station, it is possible to suppress the occurrence of the uplink transmission delay, which is a problem in the conventional PON system.

(2) Further, in the wireless network system of the present invention, the first relay device includes an optical receiver that receives downlink data from an external network, a transmitter processing circuit that modulates the received downlink data into an optical signal, and the above. It is characterized by including an optical transmitter that transmits a modulated optical signal.

In this way, the first relay device includes an optical receiver that receives downlink data from an external network, a transmission processing circuit that modulates the received downlink data into an optical signal, and an optical transmitter that transmits the modulated optical signal. , Which eliminates the need for the MPCP and uplink scheduling functions, which are vertical protocols that were required when using a conventional PON system, and makes it possible to realize a simple circuit configuration. As a result, the access line can be constructed at low cost.

(3) Further, in the wireless network system of the present invention, the second relay device includes an optical receiver that receives an optical signal transmitted from the first relay device and a MAC that demodulates the received optical signal into data. It includes a processing unit and an optical transmitter that transmits the demodulated data to the terminal device.

In this way, the second relay device includes an optical receiver that receives the optical signal transmitted from the first relay device, a MAC processing unit that demodulates the received optical signal into data, and the demodulated data to the terminal device. Since it is provided with an optical transmitter for transmission, the circuit can be greatly simplified, and as a result, an access line can be constructed at low cost.

(4) Further, in the wireless network system of the present invention, the first relay device stores the transmission delay amount to the own device and each second relay device, and based on the stored transmission delay amount, each of the first relay devices. 2. A delay compensation circuit for notifying the transmission processing circuit of the correction value required for each destination of the relay device is further provided, and the transmission processing circuit is characterized in that the downlink data is transmitted after buffering the correction value. To do.

In this way, the first relay device stores the transmission delay amount to the own device and each second relay device, and based on the stored transmission delay amount, the correction value required for each destination of each second relay device is set. A delay compensation circuit for notifying the transmission processing circuit is further provided, and the transmission processing circuit transmits downlink data after buffering the correction value, so that a shift in transmission timing between small cells can be suppressed and the transmission processing circuit can be used in a plurality of small cells. It is possible to improve the quality of wireless communication.

(5) Further, the communication method of the wireless network system of the present invention has a macro base station that forms a macro cell under the control of the accommodation station, and a plurality of small cell base stations that form small cells in the macro cell. The accommodation station and each of the small cell base stations are connected in a star shape via an optical branching device, and a terminal device in the area in one of the small cells performs downlink communication using the small cell. A communication method of an asymmetric wireless network system configured to perform uplink communication using the macro cell, and a terminal device performing wireless communication with the macro base station at the accommodation station is the small cell base. When it is determined that data communication with the station is possible, the step of transmitting downlink data to the first relay device provided in the accommodation station and the first relay device perform the small cell bases. A step of transmitting downlink data to the terminal device via a second relay device provided in each station, and a step of receiving downlink data from the second relay device in the terminal device while receiving downlink data from the second relay device, while passing through the macro base station. It is characterized by including at least a step of transmitting control information including a data transmission request and uplink data to the accommodation station.

In this way, the communication method of the wireless network system is such that when the accommodation station determines that the terminal device performing wireless communication with the macro base station is capable of data communication with the small cell base station, the inside of the accommodation station is used. The step of transmitting downlink data to the first relay device provided in the base station, and the first relay device transmitting downlink data to the terminal device via the second relay device provided in each small cell base station. The terminal device includes at least a step of receiving downlink data from the second relay device and transmitting control information including a data transmission request and uplink data to the accommodation station via a macro base station. Therefore, the MPCP and the uplink scheduling function, which are vertical protocols, which are required when the conventional PON system is used, are not required, and the first and second relay devices can be realized by a simple circuit configuration. As a result, the access line can be constructed at low cost. Further, since the uplink communication is performed via the macro base station, it is possible to suppress the occurrence of the uplink transmission delay, which is a problem in the conventional PON system.

According to the present invention, by constructing an asymmetric wireless network system composed of a macro base station that forms a macro cell and performs vertical communication, and a small cell base station that forms a small cell in the macro cell and performs downlink communication. The circuit of the relay device can be greatly simplified, and as a result, the access line can be constructed at low cost. Further, by communicating the uplink communication via the macro and the downlink communication via the small cell, it is possible to reduce the delay of the data communication. As a result, for example, it becomes possible to satisfy the demand for low delay in 5G.

It is a figure which shows the schematic structure of the wireless network system which concerns on Example 1. FIG. It is a circuit diagram of OLT used in the conventional PON system. It is a circuit diagram of ONU used in the conventional PON system. It is a circuit diagram of the 1st relay device which concerns on Example 1. FIG. It is a circuit diagram of the 2nd relay device which concerns on Example 1. FIG. It is a sequence chart about the downlink data transmission of the wireless network system which concerns on Example 1. FIG. 6 is a sequence chart relating to uplink data transmission of the wireless network system according to the first embodiment. It is a sequence chart about management of the cell in which a terminal device UT exists. It is a figure which shows the schematic structure of the circuit of the 1st relay device which concerns on Example 2. FIG. It is a circuit diagram of the 1st relay device which concerns on Example 3. FIG. It is a circuit diagram of the 2nd relay device which concerns on Example 3. FIG. It is a circuit diagram of the 1st relay device which concerns on Example 3. FIG.

The present inventors have focused on the need to construct an access line as the number of small cell base stations increases in a heterogeneous network, and have found that cost reduction can be realized by introducing a PON system. Furthermore, in order to solve the problem of low delay in uplink data communication, which is a problem in PON systems, we found that it is possible to solve the low delay in uplink data communication by using a relay device only for downlink data communication. I came to invent.

That is, the wireless network system of the present invention has a macro base station that forms a macro cell and a plurality of small cell base stations that form small cells within the macro cell under the control of the accommodation station, and the accommodation station and each of the above. A small cell base station is connected in a star shape via an optical branching device, and a terminal device in the area in one of the small cells performs downlink communication using the small cell, while uplink is performed using the macro cell. An asymmetric wireless network system configured to perform communication, the first relay device provided in the accommodation station and a plurality of second relay devices provided in each of the small cell base stations. When the accommodation station determines that the terminal device that is performing wireless communication with the macro base station is capable of data communication with the small cell base station, the accommodating station informs the first relay device. The downlink data is transmitted, the first relay device transmits downlink data to the terminal device via the second relay device, and the terminal device receives downlink data from the second relay device, while the said It is characterized in that control information including a data transmission request and uplink data are transmitted to the accommodation station via a macro base station.

As a result, the present inventors construct an asymmetric wireless network system composed of a macro base station that forms a macro cell and performs vertical communication, and a small cell base station that forms a small cell in the macro cell and performs downlink communication. As a result, the circuit of the relay device can be greatly simplified, and as a result, the access line construction cost can be reduced. Furthermore, by communicating upstream communication via macros and downlink communication via small cells, it is possible to reduce the delay of data communication.

In the C-RAN type cellular system, the embodiment according to the present invention includes a macro base station having a function of controlling communication and performing uplink data communication in a large-scale area such as a macro cell, and the inside of the macro cell. In addition, in a network configuration in which there are multiple small cell base stations that realize only large-capacity downlink data communication at high frequencies, etc., a simple device that has a communication function only in the downlink direction is introduced instead of the conventional TDM-PON. Provide a network to accommodate small cells.

[Example 1]
FIG. 1 is a diagram showing a schematic configuration of a wireless network system according to a first embodiment. The accommodation station A corresponds to a radio control device (BBU: Base band Unit) 10 that controls communication of radios (RRH: Remote Radio Head) from macro stations S1 to Sn, and a master unit of a TDM-PON type system. The first relay device 1 is installed. Further, in the macro station, an antenna AT0 corresponding to the radio MR0 for the macro station is installed. Radios SR1 to SRn for each small cell station and second relay devices 2-1 to 2-n corresponding to slave units of the TDM-PON type system are installed.

The terminal device UT1 that has moved to the area of the small cell station S1 is notified by the macro station M of auxiliary information for establishing synchronization with the small cell station S1, and establishes a link with S1. After that, the data in the downlink direction (base station → terminal device UT) is transmitted via the data channel of the small cell station. When transmitting data in the downward direction within the coverage area of the small cell station, the data is transmitted from the BBU 10 to the first relay device 1, and the first relay device 1 confirms the destination for each data and is an appropriate second relay. It is transmitted to the device 2-n and is transmitted to the desired UT via SRn and ATn. In addition, all communication control of terminals in the area covered by the macro station is performed via the macro station.

FIG. 2A is a circuit diagram of an OLT used in a conventional PON system. Further, FIG. 2B is a circuit diagram of an ONU used in a conventional PON system. As shown in FIG. 2A, the OLT (Optical Line Terminal) 100 used in the conventional PON system includes a duplexer (101, 121), an optical receiver (103, 123), and a reception processing circuit 105. It is composed of a transmission processing circuit 125, an optical transmitter (107, 127), and an MPCP (Multi-Point-Control-Protocol) link management circuit 111. The combiner demultiplexer 101 synthesizes a plurality of optical signals received from a plurality of ONUs (Optical Network Units) 200 and outputs them to the optical receiver 103. The optical receiver 103 receives an optical signal, and the reception processing circuit 105 outputs the received optical signal to the MPCP link management circuit 111 and the optical transmitter 107. The optical transmitter 107 outputs the input optical signal to the combiner demultiplexer 121, and the combiner demultiplexer 121 outputs the input optical signal to the external network.

On the other hand, the optical receiver 123 receives an optical signal from the external network via the duplexer 121 and outputs it to the transmission processing circuit 125. The transmission processing circuit 125 outputs the input optical signal to the optical transmitter 127 and the MPCP link management circuit 111. The optical transmitter 127 transmits to each ONU 200 via the combiner demultiplexer 101.

The MPCP link management circuit 111 has an MPCP function and is mainly composed of the following three functions. (1) Discovery: A function for detecting a connected ONU, an identifier LLID (Logical Link ID) of the ONU is assigned, and an RRT (Round Trip Time) between the OLT and the ONU is measured. (2) Report: The ONU notifies the OLT of the transmission request (data amount) of the uplink signal. (3) Gate: Notifies the ONU of the transmission permission of the uplink signal, the transmission permission time, and the transmission permission amount. In addition, the OLT has a function of calculating the transmission band to be transmitted by each ONU by using the Gate / Report function of the MPCP. This is called a DBA (Dynamic Bandwidth Allocation) function.

As shown in FIG. 2B, the ONU 200 used in the conventional PON system includes a combiner demultiplexer (201, 221), an optical receiver (203, 223), an optical transmitter (207, 227), and a MAC ( Media access control) Consists of processing unit 205. The optical receiver 203 receives the optical signal transmitted from the OLT 100 via the duplexer 201 and outputs the optical signal to the MAC processing unit 205. The MAC processing unit 205 performs media access control in the data link control (DLC) layer of the communication protocol and demodulates the optical signal. The output signal output from the MAC processing unit 205 is transmitted from the optical transmitter 207 to the user network via the duplexer 221.

On the other hand, the optical receiver 223 receives an optical signal from the user network via the duplexer 221 and outputs it to the MAC processing unit 205. The output signal from the MAC processing unit 205 is transmitted from the optical transmitter 227 to the OLT 100 via the duplexer 201.

As described above, in the conventional OLT, as shown in FIG. 2A, the communication in each ONU200 direction (downlink) from the OLT100 is a TDMA (Time Division Multiple Access) type communication, and the signal from each ONU200 is an optical splitter. The waves are combined and transmitted to the OLT 100. In this case, if the data is randomly transmitted from the ONU 200, the data collides on the transmission path and the data cannot be demodulated by the OLT 100. Therefore, the process of adjusting the transmission timing of the ONU 200 is performed using the MPCP. Further, as shown in FIG. 2B, the conventional ONU 200 combines the signals received from each terminal device and transmits them to the OLT 100, and demultiplexes the signals received from the OLT 100 and transmits them to each terminal device.

FIG. 3A is a circuit diagram of the first relay device according to the first embodiment. Further, FIG. 3B is a circuit diagram of the second relay device according to the first embodiment. As shown in FIG. 3A, the first relay device 1 according to the first embodiment is composed of an optical receiver 11, a transmission processing circuit 13, and an optical transmitter 15. Further, as shown in FIG. 3B, the second relay device 2 according to the first embodiment is composed of an optical receiver 21, a MAC processing unit 23, and an optical transmitter 25.

In the first embodiment, each terminal device transmits data in the upstream direction to the BBU in the accommodation station via the macro station instead of the PON. Therefore, it is not necessary to control the uplink transmission timing of the PON, and the functions of MPCP and DBA can be deleted. As a result, as shown in FIG. 3A, the circuit can be greatly simplified. Similarly, as shown in FIG. 3B, since the second relay device may have a transmission function in only one direction, the circuit can be greatly simplified as compared with the ONU.

FIG. 4 is a sequence chart relating to downlink data transmission of the wireless network system according to the first embodiment. The BBU 10 receives downlink data from the external network (step S1). The BBU 10 determines whether or not the terminal device UT exists in the small cell (Sn) (step S2). When the terminal device UT exists in the small cell (Sn), the BBU 10 transmits the received downlink data to the terminal device UT via the first relay device 1, the second relay device 2, and the RRH (Sn). (Steps S3 to S6). On the other hand, in step S2, when the terminal device UT does not exist in the small cell (Sn), the received downlink data is transmitted to the terminal device UT via the macro cell (MR0) (steps S7 and S8).

FIG. 5 is a sequence chart relating to uplink data transmission of the wireless network system according to the first embodiment. The terminal device UT transmits the uplink data to the BBU 10 via the macro cell (MR0) (steps T1 and T2). The BBU 10 transmits the received uplink data to the external network (step T3).

FIG. 6 is a sequence chart relating to the management of the cell in which the terminal device UT exists when the downlink data of the wireless network system according to the first embodiment is transmitted. The terminal device UT transmits control information (radio quality information, data transmission request, etc.) to the BBU 10 via the macro cell (MR0) (steps P1 and P2). The BBU 10 associates the terminal device UT with each cell based on the radio quality information, and performs radio resource allocation, handover processing, and the like. Further, control information (radio resource information) is transmitted to the terminal device UT via the macro cell (MR0) (steps P3 and P4).

As described above, according to the first embodiment, it is possible to realize a great simplification of the configurations of the first relay device 1 and the second relay device 2. As a result, the access line construction cost can be reduced. Further, the BBU 10 is provided in the BBU 10 when the terminal device UT performing wireless communication with the RRH (macro base station) MR0 determines that data communication with the RRH (small cell base station) Sn is possible. The downlink data is transmitted to the first relay device 1, and the first relay device 1 transmits the downlink data to the terminal device UT via the second relay device 2 provided in the small cell base station. It is possible to suppress the delay in uplink data communication.

[Example 2]
In the network configuration as in the first embodiment, the cable length of the optical fiber between the first relay device and each second relay device is different. For example, the cable length difference between small cells in the coverage area of a macro station of about 1 km may be several hundred meters at the maximum. If there is a cable length difference of 400 meters, the round-trip transmission delay of light will be 2 microseconds. LTE CoMP function (technology to improve wireless communication quality by controlling data transmitted from multiple small cells (antenna sites) or receiving data transmitted from one UE in multiple small cells) In order to use it, it is necessary to make the difference in transmission timing between small cells ± 1.5 microseconds or less. Further, in order to realize TDD LTE, timing synchronization of ± 1.5 microseconds or less is required. Such a problem can be solved by providing a circuit for compensating for the delay between the first relay device and each second relay device in the first relay device.

FIG. 7 is a diagram showing a schematic configuration of a circuit of the first relay device according to the second embodiment. The circuit of the first relay device 1 shown in FIG. 3A is further provided with a delay compensation circuit 17. The delay compensation circuit 17 stores the transmission delay amount from the first relay device 1 to each of the second relay devices 2, and notifies the transmission processing circuit of the offset value required for each destination of the second relay device 2. As the delay amount to be input to the delay compensation circuit 17, it is possible to input a value measured by using an external device when the second relay device 2 is installed. In the transmission processing circuit 13, after buffering for a required offset time, data is transmitted to the second relay device 2, so that the reception timing at the end of the second relay device can be aligned. Although the delay compensation circuit 17 is described separately from the transmission processing circuit 13 in FIG. 7, the delay compensation circuit 17 may be configured in the transmission processing circuit 13. As described above, according to the second embodiment, the transmission delay can be reduced.

[Example 3]
FIG. 8A is a circuit diagram of the first relay device according to the third embodiment. Further, FIG. 8B is a circuit diagram of the second relay device according to the third embodiment. As shown in FIG. 8A, the first relay device 1 according to the third embodiment receives downlink data from an external network via a BBU, modulates the received downlink data into an optical signal, and transmits the modulated optical signal. The optical media converter 31 is provided. Further, as shown in FIG. 8B, the second relay device 2 according to the third embodiment receives an optical signal transmitted from the first relay device, converts the received optical signal into an electric signal, and outputs the optical media. The converter 31, the MAC processing unit 33 that controls media access to the electric signal input from the optical media converter 31, and the electric signal input from the MAC processing unit 33 are transmitted to the terminal device via the RRH. A PHY (Physical layer) unit 35 is provided. By adopting such a configuration, it is possible to greatly simplify the circuits of the first relay device and the second relay device.

Further, as shown in FIG. 8C, it is also possible to further provide the delay compensation circuit 37 in the first relay device in the third embodiment. The delay compensation circuit 37 may be configured in the optical media converter 31. By adopting such a configuration, it is possible to reduce the transmission delay.

As described above, according to the present embodiment, an asymmetric wireless network composed of a macro base station that forms a macro cell and performs vertical communication, and a small cell base station that forms a small cell in the macro cell and performs downlink communication. By constructing the system, the circuit can be greatly simplified, and as a result, the access line construction cost can be reduced. Further, by communicating the uplink communication via the macro and the downlink communication via the small cell, it is possible to reduce the delay of the data communication.

1 1st relay device 2, 2-1-2-n 2nd relay device 10 BBU
11 Optical receiver 13 Transmission processing circuit 15 Optical transmitter 17 Delay compensation circuit 21 Optical receiver 23 MAC processing unit 25 Optical transmitter 31 Optical media converter 33 MAC processing unit 35 PHY unit 37 Delay compensation circuit 100 OLT
101 Combined demultiplexer 103 Optical receiver 105 Reception processing circuit 107 Optical transmitter 111 MPCP link management circuit 121 Combined demultiplexer 123 Optical receiver 125 Transmission processing circuit 127 Optical transmitter 200 ONU
201 Combined demultiplexer 203 Optical receiver 205 MAC processing unit 207 Optical transmitter 221 Combined demultiplexer 223 Optical receiver 227 Optical transmitter A Accommodation station AT0 to ATn Antenna M Macro station MR0 Radio S1 to Sn Small cell Station SR1 to SRn Radio UT terminal device UT1 to UTn Each terminal device

Claims (5)

Under the control of the accommodation station, there is a macro base station that forms a macro cell, and a plurality of small cell base stations that form small cells in the macro cell, and the accommodation station and each small cell base station provide an optical branching device. It is configured to be connected in a star shape via a terminal device in the area of one of the small cells so that the small cell is used for downlink data communication and the macro cell is used for uplink data communication. An asymmetric wireless network system
The first relay device provided in the accommodation station and
A BBU (Base band Unit) provided in the accommodation station and controlling communication with the RRH (Remote Radio Head) in the macro cell, and
A plurality of second relay devices provided in each of the small cell base stations are provided.
When the accommodation station determines that the terminal device is capable of data communication with the small cell base station based on the control information received by the BBU from the terminal device that is performing wireless communication with the macro base station. , the BBU receives the downlink data from the external network, and transmits the downlink data to the received in the first relay device, the first relay device via the second relay device, wherein to said terminal device Send the received downlink data and
The terminal device, while receiving the downlink data from the second relay device, via the macro base station, and transmits the control information and the uplink data including the data transmission request to the receiving station radio Network system. The first relay device is
An optical receiver for receiving via downlink data the BBU from the external network,
A transmission processing circuit that modulates the received downlink data into an optical signal,
The wireless network system according to claim 1, further comprising an optical transmitter for transmitting the modulated optical signal. The first relay device is
A delay that saves the transmission delay amount to the own device and each second relay device, and notifies the transmission processing circuit of the correction value required for each destination of the second relay device based on the saved transmission delay amount. With additional compensation circuit
The wireless network system according to claim 2, wherein the transmission processing circuit transmits downlink data after buffering the correction value. The second relay device is
An optical receiver that receives an optical signal transmitted from the first relay device, and
A MAC processing unit that demodulates the received optical signal into data,
The wireless network system according to any one of claims 1 to 3, further comprising an optical transmitter that transmits the demodulated data to the terminal device via RRH. Under the control of the accommodation station, there is a macro base station that forms a macro cell, and a plurality of small cell base stations that form small cells in the macro cell, and the accommodation station and each small cell base station provide an optical branching device. It is configured to be connected in a star shape via a terminal device in the area of one of the small cells so that the small cell is used for downlink data communication and the macro cell is used for uplink data communication. A communication method for asymmetric wireless network systems
In the accommodation station, a BBU (Base band Unit) provided in the accommodation station and performing communication control with the RRH (Remote Radio Head) in the macro cell from a terminal device that wirelessly communicates with the macro base station. When the terminal device determines that data communication with the small cell base station is possible based on the received control information, the BBU receives downlink data from an external network and accommodates the received downlink data. The data is transmitted to the first relay device provided in the station, and the first relay device transmits the received downlink data to the terminal device via the second relay device provided in each small cell base station. Steps and
In the terminal device, while receiving the downlink data from the second relay device, including via the macro base station, and transmitting the control information and the uplink data including the data transmission request to the receiving station, at least A communication method characterized by that.