Aggregation station

Abstract

This aggregation station is provided with an uplink (UL) resource allocation unit for allocating a UL resource in a time domain with respect to each user terminal group located in each extension station on the basis of location information about user terminals located in each extension station. The UL resource allocation unit allocates UL resources in different time domains to user terminal groups located in different extension stations.

Description

Concentrator 【0001】 The present invention relates to a concentrator. 【0002】 By dividing the functions of a radio base station into a concentrator and a remote station and applying analog RoF (Radio-over-Fiber), a radio area can be expanded flexibly and economically. However, there is a problem that noise called upstream coupling noise increases in the upstream link (UL) when a plurality of remote stations are connected. Therefore, when designing a radio communication system consisting of a concentrator and a remote station, it is necessary to perform circuit design considering the upstream coupling noise. For example, in Non-Patent Document 1, the NF (Noise Figure) is calculated based on the number of remote stations connected to the concentrator, and it is disclosed that line design is performed so that sufficient communication quality can be obtained when the NF reaches a predetermined value (37 dB). Such line design requires increasing the UL signal level at the remote station, which is a factor increasing the power consumption of the remote station. 【0003】 A method for allocating UL communication resources to terminals is defined (see Non-Patent Document 2). Based on this regulation, there is a method of switching the connection between the concentrator and the remote station with UL signals to remove the UL upstream coupling noise. However, since this method usually performs the above UL resource allocation without considering the connection state between the concentrator and each remote station, in the case of the OFDM (Orthogonal Frequency Division Multiplexing) system, UL resource allocation may be performed at the same time for terminal groups in the communication areas of different remote stations. In this case, since a plurality of remote stations with UL communication are connected to the concentrator at the same time, upstream coupling noise occurs and the UL communication quality deteriorates. That is, the effect of removing the upstream coupling noise depends on the result of UL resource allocation. Therefore, unless UL resources are allocated within the same time for a terminal group in the communication area of one remote station, the effect of removing the upstream coupling noise cannot be maximized, but such operation is not currently performed. As a result, it is necessary to perform circuit design considering the upstream coupling noise. 【0004】Ito, Inada, Fukuya, Development and practical application of a small-scale RoF device for countermeasures in weak field areas, NTT DOCOMO Technical Journal, 21(2), 46-51, Jul. 2013.3 GPP TS 38.214 version 16.2.0 Release 16. 【0005】 The present invention aims to provide a technology that can eliminate ingress noise without requiring circuit design that takes ingress noise into consideration. 【0006】 One aspect of the present invention is an aggregation station comprising: a UL resource allocation unit that allocates time-domain UL (uplink) resources for each group of user terminals located in each outbound station based on location information, which is information of user terminals located in each outbound station, wherein the UL resource allocation unit allocates UL resources in different time domains to groups of user terminals located in different outbound stations. 【0007】 This invention makes it possible to eliminate ingress noise without having to design a circuit that takes ingress noise into consideration. 【0008】 This figure shows an example configuration of the communication system 1 according to the first embodiment. It is an example of UL resource allocation. This is a sequence diagram of the communication system 1 according to the first embodiment. 【0009】 Embodiments of the present invention will be described in detail below with reference to the drawings. 【0010】 (First Embodiment) Figure 1 is a diagram showing an example configuration of a communication system 1 according to the first embodiment. The communication system 1 comprises a central station 2, an outpost station 3, and a user terminal 4. The communication system 1 comprises n outpost stations 3-1 to n (where n is an integer of 2 or more). The communication system 1 also comprises at least one user terminal 4 located at each outpost station 3. The communication system 1 shown in Figure 1 comprises n outpost stations 3-1 to n, and a user terminal 4-k-m located at outpost station 3-k (where k is an integer from 1 to n). ｋ (m ｋIt includes an integer greater than or equal to 1. Hereafter, if it is not necessary to distinguish each branch station 3, it will simply be referred to as "branch station 3". The same applies to the elements provided by the aggregation station 2 and branch station 3. Also, if it is not necessary to distinguish each user terminal 4, it will simply be referred to as "user terminal 4". Also, user terminal 4-k-m located in the area of ​​branch station 3-k ｋ (m ｋ A number greater than or equal to 1 is referred to as "the group of user terminals located in the service area of ​​station 3-k". 【0011】 User terminal 4 transmits radio waves to the outgoing station 3. The radio waves transmitted by user terminal 4 to the outgoing station 3 include identification information of user terminal 4, which is the source of the transmission. 【0012】 The outbound station 3 transmits an optical signal to the aggregation station 2. The outbound station 3 converts the radio waves received from the user terminal 4 into an electrical signal, converts the resulting electrical signal into an optical signal, and transmits the resulting optical signal to the aggregation station 2. The outbound station 3 also transmits an optical signal containing the identification information of the user terminal 4 to the aggregation station 2. The outbound station 3 converts the radio waves containing the identification information of the user terminal 4 into an electrical signal, converts the resulting electrical signal into an optical signal, and transmits the resulting optical signal to the aggregation station 2. 【0013】 The branch station 3 functions as a slave unit in analog RoF. The aggregation station 2 functions as a master unit in analog RoF. The aggregation station 2 has the functions of a Radio Unit (RU), Distributed Unit (DU), and Central Unit (CU). 【0014】 The aggregation station 2 transmits a downlink signal to the user terminal 4. The aggregation station 2 transmits an optical signal to each branch station 3, and the branch station 3 transmits a radio wave to the user terminal 4 located within its area. 【0015】 The aggregation station 2 will now be described in detail. The aggregation station 2 comprises a converter 21 and a control unit 22. The aggregation station 2 comprises n converters 21-1 to n, each corresponding to one of the n branch stations 3-1 to n. 【0016】The converter 21 includes an O / E converter 211 and an E / O converter 212. The O / E converter 211 converts the optical signal received from the extension station 3 into an electrical signal. The E / O converter 212 converts the electrical signal into an optical signal and transmits it to the extension station 3. 【0017】 The control unit 22 controls the signals that the aggregation station 2 transmits and receives with the extension station 3. The control unit 22 includes a signal transmission unit 221, a signal processing unit 222, a UL resource allocation unit 224, and a memory 225. The UL resource allocation unit 224 and the memory 225 may be separated from the aggregation station 2 and implemented in the relay device between the aggregation station 2 and the extension station 3, or they may be implemented on the core device side higher than the aggregation station 2. 【0018】 The signal transmission unit 221 transmits a signal to the extension station 3. The signal transmission unit 221 outputs an electrical signal to the converter 21, and the electrical signal is converted into an optical signal by the converter 21 and transmitted to the extension station 3, thereby transmitting the signal to the extension station 3. The electrical signal output by the signal transmission unit 221 includes a signal containing information about the UL resources to be allocated to the extension station 3. 【0019】 The signal processing unit 222 processes the signals received from the outpost station 3. The signal processing unit 222 processes the signals received from the outpost station 3 by having the converter 21 receive an optical signal from the outpost station 3, converting the received optical signal into an electrical signal by the converter 21, and then processing the converted electrical signal. Through processing by the signal processing unit 222, the identification information of user terminals 4 located in each outpost station 3 is obtained from the optical signal indicating the identification information of the user terminals 4 located in each outpost station 3. Hereinafter, the identification information of user terminals 4 located in each outpost station 3 will simply be referred to as "location information". 【0020】 The UL resource allocation unit 224 allocates UL resources in the time domain to each group of user terminals located in the area of ​​the outpost 3, based on the location information. The UL resource allocation unit 224 allocates UL resources in different time domains to groups of user terminals located in different outpost 3s. 【0021】 Figure 2 shows an example of UL resource allocation. The UL resource allocation unit 224 allocates resources to the user terminals of the outgoing station 3-1 from time 0 to T １Allocate UL resources in this location, and send the user terminals of the extension station 3-2 to time T １ From T ２ Allocate UL resources in [location]. 【0022】 The UL resource allocation unit 224 allocates UL resources in slot units for each group of user terminals located in the area of ​​the outpost station 3, for example. In other words, the UL resource allocation unit 224 may allocate UL resources using the K2 parameter. The UL resource allocation unit 224 also allocates UL resources in OFDM symbol units for each group of user terminals located in the area of ​​the outpost station 3, for example. In other words, the UL resource allocation unit 224 may allocate UL resources using the K2 parameter and the SILV parameter. 【0023】 The UL resource allocation unit 224 may allocate UL resources in equally spaced time domains to each group of user terminals located within the service area of ​​the extension station 3. In this case, the UL resource allocation unit 224 divides the available UL resources into time units equal to the number of extension stations 3 where user terminals 4 are located, and allocates the time-divided UL resources to each extension station 3. 【0024】 The UL resource allocation unit 224 may allocate resource blocks equally to all user terminals located within the service area of ​​the outbound station 3. A resource block is the product of frequency bandwidth and time bandwidth. 【0025】 Memory 225 stores information. For example, memory 225 stores location information of the user terminal 4 to the outgoing station 3. 【0026】 The following describes the extension station 3 in detail. The extension station 3 is equipped with a converter 31 and an antenna 32. The converter 31 is equipped with an O / E converter 311 and an E / O converter 312. The O / E converter 311 converts the optical signal received from the aggregation station 2 into an electrical signal and outputs it to the antenna 32. The E / O converter 212 converts the electrical signal input from the antenna 32 into an optical signal and transmits it to the aggregation station 2. 【0027】Antenna 32 converts the electrical signal input from O / E converter 311 into radio waves and transmits them to user terminals 4 located in the service area of ​​each extension station 3. Antenna 32 converts the radio waves received from user terminals 4 into electrical signals and outputs them to E / O converter 212. 【0028】 Figure 3 is a sequence diagram of the communication system 1 according to the first embodiment. Each user terminal 4 transmits a radio wave containing its own identification information to the branch station 3 in its service area (step S10). Each branch station 3 receives a radio wave containing identification information from the user terminals 4 in its service area (step S12). Subsequently, each branch station 3 transmits an optical signal containing the identification information of the user terminal 4 to the aggregation station 2 (step S14). Here, each branch station 3 converts the radio wave received from the user terminal 4 into an electrical signal using the antenna 32, and generates an optical signal by converting the electrical signal into an optical signal using the E / O converter 312. 【0029】 The aggregation station 2 receives optical signals containing the identification information of user terminals 4 from each branch station 3 (step S16). The O / E converter 211 converts the received optical signals into electrical signals (step S18). The signal processing unit 222 obtains the identification information of user terminals 4 from the converted electrical signals (step S20). As a result, the aggregation station 2 obtains the location information of user terminals 4. 【0030】 The UL resource allocation unit 224 allocates UL resources to each group of user terminals located in the extension station 3 based on the acquired location information of the user terminals 4 (step S22). Subsequently, the signal transmission unit 221 transmits an optical signal containing the allocated UL resource information to each extension station 3 (step S24). Here, the electrical signal output from the signal transmission unit 221 is converted into an optical signal by the E / O converter 212 and transmitted to each extension station 3. 【0031】Each outbound station 3 receives an optical signal containing UL resource information from the aggregation station 2 (step S26). Each outbound station 3 transmits radio waves containing UL resource information to user terminals 4 located in its area (step S28). Each user terminal 4 receives radio waves containing UL resource information from the outbound station 3 where it is located (step S30). Subsequently, the user terminal 4 transmits UL to the outbound station 3 based on the UL resource information. The outbound station 3 receives radio waves from the user terminal 4 and transmits the generated optical signal to the aggregation station 2. 【0032】 The aggregation station 2 assigns UL resources in different time domains to user terminals located in different branch stations 3. This prevents the reception of optical signals from different branch stations in the same time domain, thereby preventing the generation of ingress noise. 【0033】 The outbound station 3 transmits an optical signal containing the identification information of the user terminal 4 to the aggregation station 2 by converting the radio waves containing the identification information of the user terminal 4 into an electrical signal, converting the generated electrical signal into an optical signal, and transmitting the generated optical signal to the aggregation station 2. However, it is not limited to this. For example, the outbound station 3 may generate an optical signal containing the identification information of the user terminal 4 located within its service area, and transmit the generated optical signal to the aggregation station 2, thereby transmitting an optical signal containing the identification information of the user terminal 4 to the aggregation station 2. 【0034】 The branch station 3 may transmit an optical signal containing information about the UL signal received from the user terminal 4 to the aggregation station 2. The information about the UL signal received from the user terminal 4 includes, for example, the timing of UL signal reception, communication time, frequency band used, or reception level. The signal processing unit 222 of the aggregation station 2 may process the optical signal containing the information about the UL signal to obtain the information about the UL signal from each user terminal 4, and identify the user terminal 4 based on the information about the UL signal from each user terminal 4. 【0035】 Furthermore, the function for identifying the user terminal 4 may be separated from the branch station 3 and implemented in a device that relays between the aggregation station 2 and the branch station 3. 【0036】(Second Embodiment) The following describes the communication system 1 according to the second embodiment. In the first embodiment, the optical signal includes identification information of the user terminal 4, while in the second embodiment, in addition to the identification information of the user terminal 4, the optical signal includes information on the quality of the signal received by the outgoing station 3 from the user terminal 4. The signal quality information is either the signal's SNR (Signal-to-Noise Ratio) or the signal's reception level. The signal processing unit 222 obtains the identification information of the user terminal 4 and the information on the quality of the signal received from the user terminal 4 by processing the optical signal which includes the identification information of the user terminal 4 and the information on the quality of the signal received from the user terminal 4. 【0037】 In the second embodiment, the UL resource allocation unit 224 allocates UL resources to each outpost station 3 based on the quality of the signals received by the outpost station 3 from the user terminals 4 located in the area. The UL resource allocation unit 224 allocates UL resources based on the average value of the signal quality received by each outpost station 3 from the user terminals 4 located in the area. For example, the UL resource allocation unit 224 may allocate UL resources for a longer period of time to an outpost station 3 with a high average value of the signal quality received from the user terminals 4, compared to an outpost station 3 with a low average value of the signal quality received from the user terminals 4, from the viewpoint of maximizing UL system throughput, or for a shorter period of time from the viewpoint of improving the equality of UL throughput for each user terminal. 【0038】 In the second embodiment, the aggregation station 2 allocates UL resources in different time domains to the outbound station 3 based on information about the signal quality received by the outbound station 3 from the user terminal 4. In the second embodiment, ingress noise is prevented, and the UL system throughput can be maximized or equalized based on the difference in signal quality such as SNR and received power, or the received quality can be equalized for each outbound station 3. 【0039】(Third Embodiment) Hereinafter, the communication system 1 according to the third embodiment will be described. In the first embodiment, the optical signal including the identification information of the user terminal 4 includes, in the third embodiment, in addition to the identification information of the user terminal 4, information on the amount of UL resources requested. The signal processing unit 222 acquires the identification information of the user terminal 4 and the information on the amount of UL resources requested by processing the optical signal including the identification information of the user terminal 4 and the information on the amount of UL resources requested. The user terminal 4 stores the UL signal in a buffer and requests the amount of UL resources via the relay station 3 to the aggregation station 2 according to the buffer amount. 【0040】 In the third embodiment, the UL resource allocation unit 224 allocates UL resources based on the amount of UL resources requested from the user terminals 4 in the coverage of each relay station 3. The UL resource allocation unit 224 allocates UL resources, for example, based on the average value of the amount of UL resources requested from the user terminals 4 in the coverage of each relay station 3. The UL resource allocation unit 224 allocates UL resources for a longer time, for example, to the relay station 3 with a higher average value of the amount of UL resources requested from the user terminals 4 compared to the relay station 3 with a lower average value of the amount of UL resources requested from the user terminals 4. 【0041】 In the second embodiment, the aggregation station 2 allocates UL resources in different time regions to the relay station 3 based on the information on the amount of UL resources requested by the relay station 3 from the user terminal 4. In the third embodiment, it is possible to prevent the occurrence of flow combination noise and allocate UL resources to the relay station 3 according to the amount of UL resources requested by the user terminal 4. 【0042】 (Other Embodiments) Although one embodiment of this invention has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the gist of this invention. 【0043】In the above description, the signal processing unit 222 and the UL resource allocation unit 224 are provided in the aggregation station 2, but they may be provided in another device. For example, the signal processing unit 222 may be provided in the master unit in analog RoF, and the UL resource allocation unit 224 may be provided in the RU / DU / CU, and the master unit in analog RoF and the RU / DU / CU may be configured to communicate with each other. 【0044】 The processing by the control unit 22 in the above-described embodiment may be realized by a computer using software. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to be realized. Here, the "computer system" is assumed to include hardware such as an OS and peripheral devices. Also, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, etc., and a storage device such as a hard disk built in a computer system. Furthermore, the "computer-readable recording medium" also includes, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, a medium that dynamically holds a program for a short time, and in that case, a volatile memory inside a computer system serving as a server or a client that holds a program for a certain period of time may also be included. Also, the above program may be for realizing a part of the above-described functions, and furthermore, it may be realized in combination with a program already recorded in the computer system for the above-described functions, and it may be realized using a programmable logic device such as an FPGA (Field Programmable Gate Array). 【0045】 1 Communication system, 2 Aggregation station, 21 Converter, 211 O / E converter, 212 E / O converter, 22 Control unit, 221 Signal transmission unit, 222 Signal processing unit, 224 UL resource allocation unit, 225 Memory, 3 Remote station, 31 Converter, 311 O / E converter, 312 E / O converter, 32 Antenna, 4 User terminal

Claims

1. An aggregation station comprising: a UL resource allocation unit that allocates time-domain UL (uplink) resources to each group of user terminals located in each outpost station based on location information, which is information about user terminals located in each outpost station, wherein the UL resource allocation unit allocates UL resources in different time domains to groups of user terminals located in different outpost stations.

2. The aggregation station according to claim 1, wherein the UL resource allocation unit allocates UL resources in equally spaced time domains to each group of user terminals located in the area of ​​the outbound station.

3. The aggregation station according to claim 1, wherein the UL resource allocation unit equally distributes and allocates resource blocks to each group of user terminals located in the service area of ​​the outbound station.

4. The aggregation station according to claim 1, wherein the UL resource allocation unit allocates UL resources based on the quality of the signals received by each outgoing station.

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