Fronthaul multiplexer, distributed antenna system, communication processing method, and program

Abstract

The objective is to provide a front-haul multiplexer, a distributed antenna system, a communication processing method, and a program that can reduce the occurrence of overflow and mitigate the degradation of uplink signals. [Solution] The fronthaul multiplexer of the embodiment includes a holding unit that acquires and holds uplink signals from multiple radio devices, each containing data corresponding to a plurality of subcarriers separated by frequency intervals; a selection unit that compares the data for each corresponding subcarrier in the plurality of uplink signals and selects the data with the maximum level for each subcarrier; and an output unit that outputs an uplink signal containing the data selected for each subcarrier.

Description

Technical Field

[0001] Embodiments of the present invention relate to a front hole multiplexer, a distributed antenna system, a communication processing method, and a program.

Background Art

[0002] Due to the spread of smartphones and the development of corporate DX, the demand for mobile communication has increased significantly. Therefore, in addition to conventional LTE (Long Term Evolution), the deployment of 5G (5th Generation Mobile Communication System), which has a higher throughput than LTE, is progressing.

[0003] Conventionally, in order to efficiently operate the RAN (Radio Access Network), in an area with low traffic, a front hole multiplexer (front hole distribution device: FHM (Front Haul Multiplexer)) is used for one radio control device to accommodate a plurality of radio devices (RU (Radio Unit)).

[0004] The front hole multiplexer relays radio signal data (IQ data) transmitted between the radio device and the radio control device. It copies the downlink (DL (Down Link)) signal received from the radio control device and distributes it to a plurality of radio devices. It also has a function of synthesizing the uplink (UL (Up Link)) signals received from a plurality of radio devices and then sending them to the radio control device. It realizes accommodating a plurality of radio devices as one cell with one radio control device.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

[0006] In fronthaul multiplexers, overflow can occur when combining UL signals received from multiple wireless devices. For example, one way to handle overflow is to shift one bit. However, this method has the problem that the gain of only that data changes.

[0007] Therefore, the problem that the present invention aims to solve is to provide a fronthaul multiplexer, a distributed antenna system, a communication processing method, and a program that can reduce the occurrence of overflow and reduce the degradation of uplink signals. [Means for solving the problem]

[0008] The fronthaul multiplexer of this embodiment includes a holding unit that acquires and holds uplink signals from multiple radio devices, each containing data corresponding to a plurality of subcarriers separated by frequency intervals; a selection unit that compares the data for each corresponding subcarrier in the plurality of uplink signals and selects the data with the maximum level for each subcarrier; and an output unit that outputs an uplink signal containing the data selected for each subcarrier. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram showing an overview of the distributed antenna system according to the embodiment. [Figure 2] Figure 2 is a block diagram showing the functional configuration of the wireless control device according to the embodiment. [Figure 3] Figure 3 is a block diagram showing the functional configuration of the wireless device according to the embodiment. [Figure 4] Figure 4 is a block diagram showing the functional configuration of the front-haul multiplexer in an embodiment. [Figure 5] Figure 5 is a diagram illustrating the processing of the uplink signal in the embodiment. [Figure 6] Figure 6 is a flowchart showing the processing of the uplink signal in the embodiment. [Figure 7] Figure 7 is a block diagram showing the functional configuration of the front-haul multiplexer in the second embodiment. [Figure 8] Figure 8 is a diagram illustrating the processing of the uplink signal in the second embodiment. [Figure 9] Figure 9 is a flowchart showing the processing of the uplink signal in the second embodiment. [Figure 10] Figure 10 is a diagram illustrating the processing of the uplink signal in the third embodiment. [Modes for carrying out the invention]

[0010] The front-haul multiplexer, distributed antenna system, communication processing method, and program of the embodiment will be described below with reference to the drawings.

[0011] Figure 1 is a block diagram illustrating the overview of the distributed antenna system 1 according to the embodiment. As shown in Figure 1, the distributed antenna system 1 comprises a wireless device (RU) 2 (2-1 to 2-N), a front haul multiplexer (FHM) 10, and a wireless control device 3. The wireless control device 3 and the core network 4 are also connected in a communicative manner.

[0012] Wireless device 2 sends the DL signal received from FHM10 to a terminal (not shown). It also sends the UL signal from the terminal to FHM10. Wireless device 2 sends the DL signal to terminals included in a cell within the range of radio waves from one wireless device 2.

[0013] The wireless control device 3 is connected to the core network 4 and performs processes such as communication control of the MAC (Medium Access Control) layer and radio resource management of terminals. Also, it transmits the signal received from the core network 4 to the FHM10. Further, it transmits the signal received from the FHM10 to the core network 4.

[0014] The FHM10 copies the downlink (DL) signal from the wireless control device 3 and distributes it to a plurality of wireless devices 2. Also, it combines the uplink (UL) signals received from the plurality of wireless devices 2 and sends them to the wireless control device 3. By the FHM10, it is possible to accommodate a plurality of wireless devices 2 as one physical cell ID (PCI: Physical cell identifier) in one wireless control device 3. Note that the physical cell ID is an identifier of a physical cell.

[0015] Figure 2 is a block diagram showing the functional configuration of the wireless control device 3 of the embodiment. As shown in Figure 2, the wireless control device 3 includes an upper layer processing unit 31, a modulation unit 32, a mapping unit 33, a demapping unit 34, a channel estimation unit 35, and a demodulation unit 36.

[0016] The upper layer processing unit 31 communicates with the core network 4 and performs processes of upper layers such as radio resource scheduling management and packet encryption processing.

[0017] The modulation unit 32 performs encoding and modulation processing on the DL signal output from the upper layer processing unit 31 according to the MCS (Modulation and Coding Scheme).

[0018] The mapping unit 33 maps the DL signal output from the modulation unit 32 to radio resources based on the scheduling information generated by the upper layer processing unit 31 and outputs it to the FHM10.

[0019] The demapping unit 34 acquires the UL signal output from the FHM 10 based on the scheduling information generated by the upper layer processing unit 31, and sends the control signal for channel estimation from the UL signal to the channel estimation unit 35. It also sends the UL signal to the demodulation unit 36.

[0020] The channel estimation unit 35 estimates the channel state of the transmission line based on the channel estimation control signal output from the demapping unit 34, and sends the estimation result to the demodulation unit 36.

[0021] The demodulation unit 36 ​​demodulates and decodes the UL signal from the demapping unit 34 based on the results estimated by the channel estimation unit 35.

[0022] Figure 3 is a block diagram showing the functional configuration of the wireless device 2 of the embodiment. As shown in Figure 3, the wireless device 2 includes an IFFT / CP (Inverse Fast Fourier Transform / Cyclic Prefix) addition unit 21, a DAC (Digital Analog Converter) unit 22, an analog processing unit 23, an antenna unit 24, an ADC (Analog Digital Converter) unit 25, and an FFT / CP removal unit 26.

[0023] The IFFT / CP addition unit 21 processes the signal output from the FHM10 using IFFT, adds CP, and sends it to the DAC unit 22.

[0024] The DAC unit 22 acquires a digital signal from the IFFT / CP add-on unit 21, converts it to an analog signal, and sends it to the analog processing unit 23.

[0025] The analog processing unit 23 processes the analog signal output from the DAC unit 22, including upconversion and signal amplification, and sends it to the antenna unit 24. It also acquires the signal from the antenna unit 24, processes it with signal amplification and downconversion, and sends it to the ADC unit 25.

[0026] The ADC unit 25 acquires an analog signal from the analog processing unit 23, converts it to a digital signal, and sends it to the FFT / CP removal unit 26.

[0027] The FFT / CP removal unit 26 removes the CP and performs FFT processing. The signal after FFT processing is sent to the FHM 10.

[0028] Figure 4 is a block diagram showing the functional configuration of the fronthaul multiplexer of the embodiment. As shown in Figure 4, the FHM10 includes a copy unit (data copy unit) 11, a holding unit (received data holding unit) 12, a selection unit (data selection unit) 13, and an output unit (data output unit) 14.

[0029] The copy unit 11 acquires the DL signal from the wireless control device 3, duplicates it for the number of wireless devices 2, and sends it to the multiple wireless devices 2.

[0030] The holding unit 12 acquires and holds UL signals from multiple wireless devices 2. It also sends the held UL signals to the selection unit 13. Each UL signal contains data corresponding to each of the subcarriers separated by frequency intervals in a single data sequence.

[0031] The selection unit 13 compares the levels of multiple UL signals acquired from the holding unit 12 and selects the data with the highest level from among the UL signals. Specifically, it compares the data for each corresponding subcarrier in the multiple UL signals and selects the data with the highest level for each subcarrier.

[0032] The output unit 14 sends data to the wireless control device 3 that has the maximum level selected by the selection unit 13. Specifically, it outputs a UL signal containing the data selected for each subcarrier.

[0033] Figure 5 is a diagram illustrating the processing of uplink signals in the embodiment. Figure 5 shows the UL signals sent to the FHM10 from multiple wireless devices 2 and the processing results of the UL signals selected by the selection unit 13.

[0034] Figure 5 shows multiple subcarriers separated by frequency intervals from multiple UL signals. Figure 5 illustrates the case where one data sequence is divided into 10 subcarriers. The data level (amplitude level) corresponding to each subcarrier is shown. For illustrative purposes, the levels are indicated by numbers from 0 to 9. Data with a level exceeding 9 is defined as an overflow.

[0035] The selection unit 13 acquires UL signals from multiple wireless devices 2. For example, it acquires UL signals from wireless devices 2-1 to 2-N. The selection unit 13 compares the data levels for each corresponding subcarrier in the multiple UL signals. For example, in the case of Figure 5, it compares the levels from wireless device 2-1 to wireless device 2-N for each subcarrier. Then, it selects the data with the maximum level for each subcarrier.

[0036] Figure 5 shows the FHM10, which displays the results of the selection unit 13 selecting the data with the maximum level for each subcarrier of the UL signals from radio devices 2-1 to 2-N. By selecting the data with the maximum level for each subcarrier, the selection unit 13 can prevent overflow where the combined level exceeds 9.

[0037] Furthermore, by selecting the data with the maximum level for each subcarrier, the influence of noise components can be reduced because unselected data with low levels are not combined with the selected data. In addition, the selection unit 13 prevents overflow, eliminating the need for clipping, and thus preventing fluctuations in the signal data gain due to clipping.

[0038] Furthermore, when a terminal establishes a connection with the wireless control device 3 through initial access or other means, PRACH (Physical Random Access Channel), which is used for resynchronization and other purposes, may collide. However, by selecting the data with the highest level, the probability of discarding both colliding signals is reduced, and efficiency is improved.

[0039] Figure 6 is a flowchart illustrating the processing of uplink signals in an embodiment. As shown in Figure 6, the holding unit 12 of the FHM 10 acquires and holds the UL signals from multiple wireless devices 2. The holding unit 12 sends the acquired multiple UL signals to the selection unit 13. The UL signals contain data corresponding to each of the multiple subcarriers separated by frequency intervals (step S1).

[0040] The selection unit 13 selects the data with the maximum level for each corresponding subcarrier in the multiple UL signals from the acquired multiple UL signals. The output unit 14 then outputs a UL signal containing the data selected for each subcarrier selected by the selection unit 13 (step S2).

[0041] Figure 7 is a block diagram showing the functional configuration of the fronthaul multiplexer of the second embodiment. As shown in Figure 7, the FHM10 includes a copy unit 11, a holding unit 12, a selection unit 13, an output unit 14, a synthesis unit (data synthesis unit) 15, and an overflow detection unit 16.

[0042] The copy unit 11, the holding unit 12, and the output unit 14 are the same as in the first embodiment. In the second embodiment, a synthesis unit 15 and an overflow detection unit 16 are further included. In the second embodiment, the method for dealing with the situation after the signals have been synthesized and an overflow has been detected will be described.

[0043] The synthesis unit 15 synthesizes the UL signal data acquired from the holding unit 12. Then, it sends the synthesized data to the overflow detection unit 16.

[0044] The overflow detection unit 16 detects whether or not there is an overflow in the synthesized data acquired from the synthesis unit 15. It then notifies the selection unit 13 of the detection result.

[0045] The selection unit 13, for subcarriers in which the overflow detection unit 16 has detected an overflow, compares the data for each subcarrier of multiple UL signals acquired from the holding unit 12 and selects the data with the highest level from among the UL signal data.

[0046] Furthermore, the selection unit 13 selects the data synthesized by the synthesis unit 15 for subcarriers for which the overflow detection unit 16 did not detect an overflow.

[0047] The output unit 14 acquires a UL signal containing the data selected by the selection unit 13 and sends it to the wireless control device 3.

[0048] Figure 8 is a diagram illustrating the processing of uplink signals in the second embodiment. Figure 8 shows the UL signals sent to the FHM10 from multiple wireless devices 2 and the processing results of the UL signal selected from the multiple UL signals by the selection unit 13.

[0049] As shown in Figure 8, the UL signals sent from the multiple wireless devices 2 to the FHM10 are the same as in the first embodiment.

[0050] The combining unit 15 combines multiple UL signals sent to the FHM 10 from multiple wireless devices 2, subcarrier by subcarrier. Specifically, it combines the UL signals from wireless devices 2-1 to 2-N. The combined data for each subcarrier is sent to the overflow detection unit 16.

[0051] The overflow detection unit 16 detects whether or not an overflow has occurred with respect to the data synthesized by the synthesis unit 15 for each subcarrier. For example, in Figure 8, for illustrative purposes, the data levels corresponding to each subcarrier are shown from 0 to 9. If the level exceeds 9, it is considered that an overflow has occurred. A predetermined level is one example of a level exceeding 9.

[0052] The overflow detection unit 16 determines, for example, that the level of the synthesized data for the leftmost subcarrier shown in Figure 8 is 2, and therefore no overflow occurs for that subcarrier, and notifies the selection unit 13.

[0053] Furthermore, the overflow detection unit 16, for example, separates one data sequence shown in Figure 8 into 10 subcarriers, designating the leftmost subcarrier as the 1st subcarrier and the rightmost subcarrier as the 10th subcarrier. For example, since the level of the data synthesized with respect to the 3rd subcarrier is 10, the unit determines that an overflow has occurred and notifies the selection unit 13.

[0054] The selection unit 13 selects data synthesized by the synthesis unit 15 for subcarriers for which it has been notified that no overflow will occur. For subcarriers for which it has been notified that an overflow will occur, it does not perform synthesis and processes them in the same manner as in the first embodiment. Specifically, it compares the data of subcarriers for which an overflow will occur and selects the data with the highest level.

[0055] As a result, the selection unit 13 can select the data with the maximum level from multiple UL signals before synthesis for the subcarrier in which overflow is detected, thereby preventing overflow.

[0056] Furthermore, by selecting the data with the highest level, the influence of noise components can be reduced because the unselected data with low levels will not be combined with the selected data. In addition, the selection unit 13 prevents overflow, so fluctuations in the signal data gain due to clipping and other factors do not occur.

[0057] Figure 9 is a flowchart illustrating the processing of uplink signals in the second embodiment. As shown in Figure 9, the holding unit 12 of the FHM 10 acquires and holds UL signals containing data corresponding to each of the multiple subcarriers separated by frequency intervals from multiple radio devices 2. The holding unit 12 sends the acquired multiple UL signals to the combining unit 15 (step S21).

[0058] The synthesis unit 15 synthesizes (adds) data for each corresponding subcarrier in multiple UL signals (step S22).

[0059] The overflow detection unit 16 detects whether or not an overflow has occurred for each subcarrier from the data synthesized for each subcarrier and notifies the selection unit 13 of the detection result (step S23).

[0060] If the selection unit 13 receives a result from the overflow detection unit 16 indicating that an overflow has occurred (step S23; Yes), it compares multiple data of the subcarrier in question before synthesis and selects the data with the highest level. The output unit 14 sends a UL signal containing the selected data of the subcarrier in question to the wireless control device 3 (step S24).

[0061] If the overflow detection unit 16 receives a result indicating that no overflow occurred (step S23; No), it selects data synthesized by the synthesis unit 15 for the subcarriers that did not experience an overflow. The output unit 14 sends a UL signal containing the selected data to the wireless control device 3 (step S25).

[0062] Figure 10 is a diagram illustrating the processing of the uplink signal in the third embodiment. In the first and second embodiments, the case where there is one physical cell ID for grouping multiple wireless devices 2 was described as an example. Therefore, there was only one output data from the FHM10 to the wireless control device 3.

[0063] As shown in Figure 10, the third embodiment takes the example of a case where there are multiple physical cell IDs that group together multiple wireless devices 2. Therefore, the output data from FHM10 to wireless control device 3 is also multiple, as it is output for each physical cell ID. For example, if there are M physical cell IDs, the output data from FHM10 to wireless control device 3 will also be M.

[0064] In the third embodiment, as shown in Figure 10, processing is performed for each physical cell ID from physical cell ID #1 to physical cell ID #M, similar to at least one of the first and second embodiments. This allows the UL signals from multiple wireless devices 2 to be aggregated by a single FHM 10, and the UL signal for each physical cell ID can be sent to the wireless control device 3.

[0065] Specifically, we will explain using physical cell ID#M as an example. The UL signals from each of the wireless devices 2-L to 2-N are sent to FHM10. FHM10 processes the UL signals from wireless devices 2-L to 2-N as a single physical cell ID#M, similar to at least one of the first and second embodiments, and then sends it to the wireless control device 3. Similarly, the UL signal of physical cell ID#1 sent from FHM10 to the wireless control device 3 is shown as "A". The UL signal of physical cell ID#2 sent from FHM10 to the wireless control device 3 is shown as "B".

[0066] The fronthaul multiplexer of this embodiment includes a holding unit that acquires and holds an uplink signal as a single data sequence containing data corresponding to each of a plurality of subcarriers separated by frequency intervals from a plurality of radio devices; a selection unit that compares the data for each corresponding subcarrier in the plurality of uplink signals and selects the data with the maximum level for each subcarrier; and an output unit that outputs an uplink signal containing the data selected for each subcarrier.

[0067] This reduces the occurrence of overflow. Furthermore, by selecting the data with the highest level, noise and other unwanted elements in the data with lower levels can be removed.

[0068] Furthermore, the fronthaul multiplexer of this embodiment further includes a combining unit that combines data for each corresponding subcarrier in multiple uplink signals, and an overflow detection unit that detects an overflow where the data combined for each subcarrier exceeds a predetermined level. The selection unit selects the combined data if no overflow is detected, and if an overflow is detected, it compares the data held before the combination of the subcarrier in which the overflow is detected and selects the data with the maximum level.

[0069] This allows for the reduction of overflows by selecting the data that would result in the highest level, even if an overflow occurs.

[0070] Furthermore, in the front haul multiplexer of this embodiment, the uplink signal acquired by the holding unit is an OFDM signal separated into multiple subcarriers.

[0071] Furthermore, the programs executed by each device in the communication relay system S of this embodiment are provided as installable or executable files recorded on a computer-readable recording medium such as a CD-ROM, flexible disk (FD), CD-R, or DVD (Digital Versatile Disk).

[0072] Furthermore, the programs executed by each device in the communication relay system S of this embodiment may be stored on a computer that can communicate with other communication devices via a network such as the Internet, and provided by allowing users to download them via the network.

[0073] Furthermore, the program of this embodiment may be provided or distributed via a network such as the Internet. Alternatively, the program of this embodiment may be pre-installed in ROM or the like and provided as such.

[0074] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0075] 1: Distributed antenna system 2: Radio equipment 3: Wireless control device 10: FHM (Front Hole Multiplexer) 11: Copy Department 12: Holding part 13: Selection Section 14: Output section 15: Synthesis part 16: Overflow detection unit

Claims

1. A holding unit that acquires and holds uplink signals containing data corresponding to each of multiple subcarriers separated by frequency intervals from multiple wireless devices, A selection unit compares data for each corresponding subcarrier in multiple uplink signals and selects the data with the maximum level for each subcarrier. An output unit that outputs an uplink signal containing the selected data for each subcarrier, A front-hole multiplexer equipped with this feature.

2. A combining unit that combines data for each corresponding subcarrier in multiple uplink signals, The system further includes an overflow detection unit that detects an overflow where the synthesized data for each subcarrier reaches a predetermined level or higher, The aforementioned selection unit is If no overflow is detected, select the synthesized data, If the overflow is detected, the data of the subcarrier where the overflow is detected is compared with the data before synthesis, and the data with the maximum level is selected. The front hole multiplexer according to claim 1.

3. A holding unit that acquires and holds uplink signals containing data corresponding to each of multiple subcarriers separated by frequency intervals from multiple wireless devices, A selection unit compares data for each corresponding subcarrier in multiple uplink signals and selects the data with the maximum level for each subcarrier. An output unit that outputs an uplink signal containing the selected data for each subcarrier, A distributed antenna system equipped with [the following features].

4. A combining unit that combines data for each corresponding subcarrier in multiple uplink signals, The system further includes an overflow detection unit that detects an overflow where the synthesized data for each subcarrier reaches a predetermined level or higher, The aforementioned selection unit is If no overflow is detected, select the synthesized data, If the overflow is detected, the data of the subcarrier where the overflow is detected is compared with the data before synthesis, and the data with the maximum level is selected. The distributed antenna system according to claim 3.

5. Uplink signals containing data corresponding to each of multiple subcarriers separated by frequency intervals are acquired and stored from multiple radio devices. The data is compared for each corresponding subcarrier in the multiple uplink signals, and the data with the maximum level is selected for each subcarrier. For each of the subcarriers, an uplink signal containing the selected data is output. Communication processing method.

6. Data is synthesized for each corresponding subcarrier in the multiple uplink signals. For each subcarrier, an overflow is detected where the synthesized data exceeds a predetermined level. If no overflow is detected, select the synthesized data, If the overflow is detected, the data of the subcarrier where the overflow is detected is compared with the data before synthesis, and the data with the maximum level is selected. The communication processing method according to claim 5.

7. A program for controlling a front haul multiplexer by computer, The aforementioned computer, A holding means for acquiring and holding uplink signals containing data corresponding to each of multiple subcarriers separated by frequency intervals from multiple radio devices, A selection means for comparing data for each corresponding subcarrier in multiple uplink signals and selecting the data with the maximum level for each subcarrier, Output means for outputting an uplink signal containing the selected data for each subcarrier, A program that makes something work.

8. The aforementioned computer, A synthesis means for synthesizing data for each corresponding subcarrier in a plurality of uplink signals, The overflow detection means further functions to detect an overflow where the synthesized data for each subcarrier exceeds a predetermined level. The aforementioned selection means is, If no overflow is detected, select the synthesized data, If the overflow is detected, the data of the subcarrier where the overflow is detected is compared with the data before synthesis, and the data with the maximum level is selected. The program according to claim 7.

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