JP4509921B2 - Wireless communication system and wireless communication method - Google Patents

Description

  The present invention relates to a radio communication method for digitized radio signals and a radio communication system using the radio communication method.

In the digital fiber radio (DROF) system, a radio base station is separated into a master station device having a radio modulation / demodulation function and a slave station device having a radio transmission / reception function. A radio signal such as an intermediate frequency signal is transmitted on a packet network as a packet made of digitized data (see, for example, Patent Document 1). FIG. 16 shows the configuration of a conventional digital fiber radio system. By adopting the configuration shown in the figure, in a system that requires a large number of radio base stations, the modulation / demodulation function can be centralized in the master station, reducing base station installation costs and maintenance costs, and flexibly changing modulation / demodulation methods. This is advantageous for rapid deployment of new systems. Further, since wireless signals are transferred on a packet basis, it is possible to use an existing packet-based network service and to operate at a low cost. By using this method, it is possible to widen the radio access network with a radius of several kilometers to several tens of kilometers.
Also, as a conventional technique, a cellular radio system is known in which a conventional base station does not need to be independently arranged in each microcell area by assigning a channel set that can be reused in the entire microcell system ( For example, see Patent Document 2).
Japanese Patent Laid-Open No. 2004-312150 Japanese Patent No. 3553942

  When the DROF method is realized on a packet-based network, a random delay occurs in the packet by various devices on the network. Normally, if a delay absorbing buffer is arranged on the receiving side, a signal can be reproduced without packet loss. However, when performing time division duplex (TDD), it is necessary to transmit and receive a radio signal at a specific time. The delay absorption buffer cannot adjust the time.

  Also, in a broadcast type service that transmits the same signal to a plurality of wireless cells, it is necessary to make the transmission timings simultaneously. There is a need. When using the conventional Radio-on-Fiber (ROF) technology, in order to absorb the delay difference, it is necessary to adjust the optical transmission line length after measuring the propagation delay time. Since this increases costs and takes time to change the configuration, it is difficult to realize a realistic system.

  Furthermore, in order to improve the performance of wide-area wireless access networks, spatial diversity technologies for transmission and reception in a wide area are effective. However, as an important issue in realizing these spatial diversity technologies, multiple children One example is synchronization of transmission and reception timing between stations. In the case of the conventional diversity technique, the distance between the antennas is short, and it is possible to establish synchronization between the antennas by simple electrical delay control. However, in the case of wide diversity where the distance between antennas is about several kilometers or more, it is necessary to absorb a delay difference of about several tens of microseconds, so it is not easy to realize high-performance diversity technology such as maximum ratio combining. . In response to this problem, when the conventional ROF technology is used, it is difficult to realize a realistic system as in the case of the broadcast service. Also, in the digital radio signal transmission methods proposed so far (see, for example, Patent Documents 1 and 2), in order to cope with such wide-area diversity, optical transmission is performed in the same manner as the ROF method. It is necessary to absorb the delay difference by adjusting the road length. For this reason, diversity in a wide area is difficult.

  The present invention has been made to solve such problems, and an object of the present invention is to realize transmission with a fixed delay independent of delay in a packet network between a master station and a slave station in the DROF system. In addition, a wireless communication system and a wireless communication system that can synchronize wireless signal transmission / reception timing between slave stations in a wide-area wireless system that includes a plurality of slave stations, and that can realize transmission diversity and reception diversity in a wide area. It is to provide a communication method.

The present invention has been made to solve the above problems, and is a wireless communication system comprising a master station device, a slave station device, a network connecting the master station device and the slave station device, and a wireless terminal. The master station apparatus packetizes a radio modulation circuit that modulates data, a radio demodulation circuit that demodulates data, and a digital radio signal input from the radio modulation circuit, and transmits the packetized signal to the network. A processor that receives a packet from the network, converts the received packet into a digital radio signal, and transfers the digital packet to the radio demodulation circuit, wherein the slave station device transmits a radio signal to the radio terminal. A network, a wireless receiving circuit that receives a wireless signal from the wireless terminal, and a digital wireless signal input from the wireless receiving circuit to packetize the network A processing unit that receives the packet from the network, extracts a digital wireless signal from the received packet, and transfers the packet to the wireless transmission circuit, the processing unit of the master station device and the slave station device , together with the clock synchronization and the clock frequency of the master station and the slave station apparatus, by adding time information to a packet to be transmitted in the network transmits a digital radio signal, the master station, the parent The transmission delay time of the packet between the station device and the slave station device is measured, and the processing unit of the master station device packetizes the digital wireless signal input from the wireless modulation circuit and indicates the transfer time of the digital signal In addition to adding time information, delay information indicating a time longer than a transmission delay time between the master station device and the slave station device is added to the network. The processing unit of the slave station device receives the packet transmitted by the master station device from the network, and is added to the packet with respect to the time indicated by the time information added to the packet. In addition , the wireless communication system is characterized in that a digital wireless signal extracted from the packet is transferred to the wireless transmission circuit at a time when the time indicated by the delay information is added .
Thus, the digital radio signal from the radio modulation circuit is packetized and transmitted to the optical fiber network, and the radio station of the packet received from the optical fiber network is transferred to the radio demodulation circuit, and the radio reception A digital fiber radio system using a packetized radio signal from a circuit and transmitting the packet to an optical fiber network and a slave station device for transferring the digitized radio signal of the packet received from the optical fiber network to the radio transmission circuit , The time and clock frequency of the master station device and the slave station device are synchronized, and the time information is added to the packet transmitted through the optical fiber network to transmit the radio signal.
In addition, in this way, in the master station device, the transfer time of the digital radio signal from the radio modulation circuit is added to the transmission packet as time information, and delay information larger than the transmission delay time between the master station device and the slave station device Is transmitted to the optical fiber network, and the slave station device transfers the digital radio signal to the radio transmission circuit at a time obtained by adding the time corresponding to the delay information to the time information of the received packet.

The present invention is also a wireless communication system comprising a master station device, a slave station device, a network connecting the master station device and the slave station device, and a wireless terminal, wherein the master station device is a data A wireless modulation circuit that modulates data, a wireless demodulation circuit that demodulates data, and a digital wireless signal input from the wireless modulation circuit is packetized and transmitted to the network, and a packet is received from the network and received A processing unit that converts the received packet into a digital radio signal and transfers the digital signal to the radio demodulation circuit, wherein the slave station device transmits a radio signal to the radio terminal, and a radio signal from the radio terminal. A wireless receiving circuit for receiving, and a digital wireless signal input from the wireless receiving circuit is packetized and transmitted to the network; A processing unit that receives a packet from the network and extracts a digital radio signal from the received packet and transfers the digital wireless signal to the wireless transmission circuit. The processing unit of the master station device and the slave station device includes the master station device. And the time and clock frequency of the slave station device are synchronized, and a digital wireless signal is transmitted by adding time information to a packet to be transmitted through the network, and the slave station device transmits the master station device and the slave station A packet transmission delay time between the devices, and the processing unit of the slave station device packetizes the digital radio signal input from the radio receiving circuit, time information indicating a transfer time of the digital signal and the master station The transmission delay time information between the device and the slave station device is added and transmitted to the network, and the processing unit of the master station device sends the slave station device from the network. A delay time longer than the transmission delay time between the master station device and the slave station device indicated by the information added to the packet with respect to the time indicated by the time information added to the packet. The digital radio signal extracted from the packet is transferred to the radio demodulator circuit at the time added to the radio demodulator.
Thus, the digital radio signal from the radio modulation circuit is packetized and transmitted to the optical fiber network, and the radio station of the packet received from the optical fiber network is transferred to the radio demodulation circuit, and the radio reception A digital fiber radio system using a packetized radio signal from a circuit and transmitting the packet to an optical fiber network and a slave station device for transferring the digitized radio signal of the packet received from the optical fiber network to the radio transmission circuit , The time and clock frequency of the master station device and the slave station device are synchronized, and the time information is added to the packet transmitted through the optical fiber network to transmit the radio signal.
In this way, in the slave station device, the transfer time of the digital radio signal from the radio reception circuit is added to the transmission packet as time information and transmitted to the optical fiber network, and in the master station device, the time of the reception packet is transmitted. The digital radio signal is transferred to the radio demodulation circuit at a time when a delay time larger than the transmission delay time between the master station device and the slave station device is added to the information.

Further, the present invention is the above wireless communication system, wherein the master station device and a plurality of slave station devices are connected to the network, and the processing unit of the master station device has the same digital radio signal. The same time information and the same delay information are added to the packet and transmitted to the plurality of slave station devices via the network, and the processing units of the plurality of slave station devices simultaneously transmit the same digital radio The signal is transferred to the wireless transmission circuit of the slave station device.
As a result, in a digital fiber wireless system in which a master station device and a plurality of slave station devices are connected by an optical fiber network, time information, delay information, digitization of packets transmitted from the master station device to the plurality of slave station devices The radio signals are the same, and the plurality of slave station devices simultaneously transfer the same digitized radio signal to the radio transmission circuit.

In the wireless communication system according to the present invention, the master station device and the plurality of slave station devices are connected to the network, and the processing unit of the master station device includes the plurality of slave station devices. The digital radio signal extracted from each packet is simultaneously transferred to the radio demodulation circuit by adding an individual delay time to the reception time of each packet transmitted from the same time information added thereto. And
As a result, in a digital fiber radio system in which a master station device and a plurality of slave station devices are connected by an optical fiber network, each packet from the plurality of slave station devices to the master station device is individually delayed by the master station device. Time is added and digitized radio signals having the same time information are simultaneously transferred to the radio demodulation circuit.

In the wireless communication system according to the present invention, the wireless transmission circuit of the plurality of slave station devices transmits the same wireless signal to a wireless terminal at a specified time, and the wireless terminal transmits the plurality of slave stations The same radio signal transmitted from the apparatus is received.
As a result, the same radio signal is transmitted to the terminal device at a time designated by a plurality of slave station devices at remote locations, and transmission diversity is performed.

According to the present invention, in the above wireless communication system, the wireless terminal transmits the same wireless signal to the plurality of slave station devices, and the processing units of the plurality of slave station devices receive the wireless signals received from the wireless terminals. Signals are packetized, time information indicating transfer time is added and transmitted to the master station device, and the processing unit of the master station device is transmitted from the plurality of slave station devices, and each packet with time information added thereto By adding an individual delay time to each reception time, the digital radio signal extracted from each packet is simultaneously transferred to the radio demodulation circuit, and the radio demodulation circuit receives the digital radio signal received from the processing unit. Diversity processing is performed.
Thus, reception diversity is performed in the master station device based on signals received at times designated by a plurality of slave station devices in remote locations.

  Further, in the wireless communication system according to the present invention, the processing unit of the master station device and the slave station device uses one of a global positioning system or a network time protocol as time / frequency synchronization means, The processing unit of the slave station device measures the transmission delay time by a network time protocol with the processing unit of the master station device, and transmits the measured transmission delay time information to the master station device. It is characterized by.

  Further, in the wireless communication system according to the present invention, the processing unit of the master station device and the slave station device uses one of a global positioning system and a precision time protocol as time / frequency synchronization means, The processing unit of the slave station device measures the transmission delay time by a precision time protocol with the processing unit of the master station device, and transmits the measured transmission delay time information to the master station device. It is characterized by.

The present invention is also a wireless communication method used in a wireless communication system comprising a master station device, a slave station device, a network connecting the master station device and the slave station device, and a wireless terminal, The master station device packetizes a radio modulation circuit that modulates data, a radio demodulation circuit that demodulates data, and a digital radio signal input from the radio modulation circuit, and transmits the packet to the network. A processing unit that receives the packet, converts the received packet into a digital radio signal and transfers the digital packet to the radio demodulation circuit, and the slave station device transmits a radio signal to the radio terminal; A wireless reception circuit that receives a wireless signal from a wireless terminal, and a digital wireless signal input from the wireless reception circuit is packetized and transmitted to the network And a processing unit that receives a packet from the network, extracts a digital wireless signal from the received packet, and transfers the digital wireless signal to the wireless transmission circuit, the processing unit of the master station device and the slave station device, Synchronizing the time and clock frequency of the master station device and the slave station device, adding time information to a packet to be transmitted through the network, and transmitting a digital radio signal , the master station device is connected to the master station device The transmission delay time of the packet between the slave station devices is measured, and the processing unit of the master station device packetizes the digital radio signal input from the radio modulation circuit, and displays time information indicating the transfer time of the digital signal And adding delay information indicating a time longer than the transmission delay time between the master station device and the slave station device to the network. The processing unit of the slave station device receives the packet transmitted by the master station device from the network, and the delay information added to the packet with respect to the time indicated by the time information added to the packet The wireless communication method is characterized in that a digital wireless signal extracted from the packet is transferred to the wireless transmission circuit at the time when the time indicated by is added .

The present invention is also a wireless communication method used in a wireless communication system comprising a master station device, a slave station device, a network connecting the master station device and the slave station device, and a wireless terminal, The master station device packetizes a radio modulation circuit that modulates data, a radio demodulation circuit that demodulates data, and a digital radio signal input from the radio modulation circuit, and transmits the packet to the network. A processing unit that receives the packet, converts the received packet into a digital radio signal and transfers the digital packet to the radio demodulation circuit, and the slave station device transmits a radio signal to the radio terminal; A wireless reception circuit that receives a wireless signal from a wireless terminal, and a digital wireless signal input from the wireless reception circuit is packetized and transmitted to the network And a processing unit that receives a packet from the network, extracts a digital wireless signal from the received packet, and transfers the digital wireless signal to the wireless transmission circuit, the processing unit of the master station device and the slave station device, Synchronizing the time and clock frequency of the master station device and the slave station device, adding time information to a packet to be transmitted through the network, and transmitting a digital radio signal, the slave station device is connected to the master station device Measuring the transmission delay time of the packet between the slave station devices, the processing unit of the slave station device packetizes the digital radio signal input from the radio reception circuit, and time information indicating the transfer time of the digital signal; Information on a transmission delay time between the master station device and the slave station device is added and transmitted to the network. The packet transmitted from the slave station device is received from the network, and the time indicated by the time information added to the packet is between the master station device and the slave station device indicated by the information added to the packet. A digital radio signal extracted from the packet is transferred to the radio demodulation circuit at a time when a delay time longer than the transmission delay time is added.

  Further, the present invention is the above-described wireless communication method, wherein the master station device and the plurality of slave station devices are connected to the network, and the processing unit of the master station device has the same digital radio The same time information and the same delay information are added to a signal packet and transmitted to the plurality of slave station devices via the network, and the processing units of the plurality of slave station devices simultaneously A digital wireless signal is transferred to the wireless transmission circuit of the slave station device.

  Further, the present invention is the above-described wireless communication method, wherein the master station device and the plurality of slave station devices are connected to the network, and the processing unit of the master station device includes the plurality of slave devices. A digital radio signal extracted from each packet is simultaneously transferred to the radio demodulation circuit by adding an individual delay time to the reception time of each packet transmitted from the station apparatus and having the same time information added thereto; It is characterized by.

  Further, the present invention is the above-described wireless communication method, wherein the wireless transmission circuits of the plurality of slave station devices transmit the same wireless signal to a wireless terminal at a designated time, and the wireless terminal The same radio signal transmitted from the slave station device is received.

  Further, the present invention is the above-described wireless communication method, wherein a wireless terminal transmits the same wireless signal to the plurality of slave station devices, and a processing unit of the plurality of slave station devices receives from the wireless terminal. Packetized wireless signal, added time information indicating the transfer time and transmitted to the master station device, the processing unit of the master station device was transmitted from the plurality of slave station devices, the time information was added A digital radio signal extracted from each packet is simultaneously transferred to the radio demodulator circuit by adding an individual delay time to the reception time of each packet, and the radio demodulator circuit receives the digital radio signal received from the processing unit. The reception diversity processing is performed.

  Further, the present invention is the above-described wireless communication method, wherein the processing unit of the master station device and the slave station device uses one of a global positioning system or a network time protocol as time / frequency synchronization means. And the processing unit of the slave station device measures the transmission delay time by a network time protocol with the processing unit of the master station device, and transmits the measured transmission delay time information to the master station device. It is characterized by transmitting.

  Further, the present invention is the above-described wireless communication method, wherein the processing unit of the master station device and the slave station device uses one of a global positioning system and a precision time protocol as time / frequency synchronization means. And the processing unit of the slave station device measures the transmission delay time by a precision time protocol with the processing unit of the master station device, and transmits the measured transmission delay time information to the master station device. It is characterized by transmitting.

  As described above, according to the present invention, in the DROF scheme, transmission with a fixed delay independent of delay in a packet network between a master station and a slave station is realized, and a wide area having a plurality of slave stations is provided. In such a wireless system, synchronization of wireless signal transmission / reception timings between slave stations can be realized, and transmission diversity and reception diversity in a wide area can be realized.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of a wireless communication system according to a first embodiment of this invention.
In the wireless communication system shown in the figure, using a digital fiber radio (DROF) system, a radio base station is separated into a master station device 100 having a radio modulation / demodulation function and a slave station device 300 having a radio transmission / reception function, The master station device 100 and the slave station device 300 are connected by an optical fiber network 200. In this wireless communication system, it is the slave station device 300 that actually transmits and receives data to and from the wireless terminal 500, and the slave station device 300 transmits the radio signal received from the wireless terminal 500 to the master station device 100 via the optical fiber network 200. Forward. The master station device 100 demodulates the transferred radio signal and uses it by transferring it to other terminals as necessary. Further, the signal addressed to the wireless terminal 500 is modulated by the master station device 100 and transferred to the slave station device 300 via the optical fiber network 200. The slave station device 300 transmits the transferred signal to the wireless terminal 500. Specific functions of each part are shown below.

  In the downlink direction, the digitized radio signal output from the radio modulation / demodulation circuit 110 of the master station device 100 is packetized by the packetization processing unit 120. The radio signal is a radio baseband signal or a radio intermediate frequency band signal. After the digitized radio signal is packetized, the DROF header processing unit 130 adds a transmission / reception device number and the like, and in addition, a timing processing unit based on time / frequency information from the time / frequency synchronization unit 170 The time information and delay time information generated by 160 are added. After these pieces of information are added, the network processing unit 140 converts the information into an Ethernet (registered trademark) packet (hereinafter also referred to as “ether packet”), and outputs the packet from the optical interface 150 to the optical fiber network 200.

  In the slave station device 300, when the optical interface 310 receives the Ethernet packet from the optical fiber network 200, the network processing unit 320 extracts the DROF packet from the received Ethernet packet, and the DROF header processing unit 330 extracts the time from the DROF packet. Information and delay time information are extracted. The ether packet is transferred to the timing processing unit 340 and the packetization processing unit 350 reproduces the digital data string. The time / frequency information used by the timing processing unit 340 at this time uses information generated by the time / frequency synchronization unit 370. The reproduced digital data sequence is transferred to the wireless transmission / reception circuit 360 at a time obtained by adding the time indicated by the delay time information to the time indicated by the time information based on the timing data from the timing processing unit 340, and is wirelessly transmitted as a wireless signal. It is sent to the terminal 500.

  Conversely, in the uplink direction, a radio signal from radio terminal 500 is received by radio transmission / reception circuit 360 of slave station apparatus 300, sampled and digitized at the sampling timing from timing processing unit 340, and packetized processing unit 350. Is packetized. The digitized radio signal is packetized, and time information and transmission delay time information are added by the DROF header processing unit 330 based on the sampling timing in the timing processing unit 340, and the network processing unit 320 converts the digital radio signal into an ether packet. It is converted and output from the optical interface 310 to the optical fiber network 200. In the master station device 100, when the Ethernet packet is received by the optical interface 150 via the optical fiber network 200, the network processing unit 140 extracts the DROF packet from the received Ethernet packet, and the DROF header processing unit 130 extracts time information. The transmission delay time information is extracted and transferred to the timing processing unit 160, and the packetization processing unit 120 reproduces the digital data string. The reproduced digital data sequence is transferred to the radio modulation / demodulation circuit 110 at a time obtained by adding a fixed delay time equal to or greater than the transmission delay time to the time indicated by the time information based on the timing data from the timing processing unit 160, and the data Is demodulated.

FIG. 2 is a diagram for explaining transmission with a constant delay in the wireless communication system shown in FIG.
DROF packet A to the master station apparatus 100 child station apparatus 300, B, when outputting the C, each packet A, B, different delay times _T dA for _{C, T dB,} T _dC occurs in the optical fiber network 200 . By using this embodiment, even when the delay times T _dA , T _dB , and T _dC of the DROF packets A, B, and C change due to delay fluctuations in the optical fiber network 200, as shown in FIG. A radio signal can be transmitted between the apparatus 100 and the slave station apparatus 300 with a constant delay time _Td . When time division duplex (TDD) is used in the wireless system using the present embodiment, the slave station device 300 can make the switching timing of uplink and downlink constant, so that stable operation is realized. The

  For time synchronization and frequency synchronization in the present embodiment, a global positioning system (GPS) device is used as the time / frequency synchronization unit 170 of the master station device 100 and the time / frequency synchronization unit 370 of the slave station device 300, respectively. It can be realized by arranging. Further, in the slave station device 300 that cannot sufficiently receive radio waves from GPS satellites, separate time and frequency synchronization means are required. As this separate synchronization means, there is a network-based synchronization using a Network Time Protocol (NTP) or a Precision Time Protocol (PTP). In these protocols, frequency synchronization and time synchronization are established by transmitting and receiving a time measurement packet between the time / frequency synchronization unit 170 of the master station device 100 and the time / frequency synchronization unit 370 of the slave station device 300. The transmission delay time between the master station device 100 and the slave station device 300 can be measured, and delay time information can be generated. The NTP protocol is RFC 2030: Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI (IETF), 1996. The PTP protocol is IEEE 1580: IEEE Standard for a Precision Clock Synchronization Protocol for Networked. Well shown in Measurement and Control Systems, 2002.

Next, the operation of the wireless communication system using the NTP protocol will be described.
FIG. 3 shows the format of the NTP message packet.
In the figure, an NTP message packet includes a leap second indicator (LI), a version number (VN), a mode (Mode), a hierarchy (Stratum), a polling interval (Poll Interval), a precision (Precision), and a root delay (Root Delay). ), Root Dispersion, Reference Identifier, Reference Timestamp, Start Timestamp, Receive Timestamp, and Transmit Timestamp fields Contains.

  4 is a diagram showing a time synchronization operation using NTP in the wireless communication system shown in FIG. The NTP client unit 371 in the time / frequency synchronization unit 370 of the slave station device 300 generates an NTP packet in which the time information T1 of the current time of the slave station device 300 is written in a transmission time stamp (Transmit Timestamp). The generated NTP packet is processed by the network processing unit 320 and then transferred from the optical interface 310 to the NTP server unit 171 in the time / frequency synchronization unit 170 of the master station device 100 through the optical fiber network 200 for reception. Time information T2 is recorded (step S11). The NTP server unit 171 uses the time information T1 of the received NTP packet as the start time stamp (Originate Timestamp), the reception time information T2 of the parent station device 100 as the reception time stamp (Receive Timestamp), and the transmission time preference of the parent station device 100. An NTP packet in which the time signal T3 is written in a transmission time stamp (Transmit Timestamp) is generated and sent to the slave station device 300 (step S12). When the NTP client unit 371 receives an NTP packet, the NTP client unit 371 detects a phase error from a deviation in transmission / reception time stamp variation between a plurality of packets and performs frequency synchronization. Further, the NTP client unit 371 calculates the time lag Toffset and the transmission delay time ΔT from the time information (T1, T2, T3) in the received NTP packet and the time information T4 when the slave station device 300 receives the NTP packet. Calculate with the following formula.

Toffset = ((T4-T3)-(T2-T1)) / 2

ΔT = ((T4−T3) + (T2−T1)) / 2

  Time synchronization is realized by correcting the time of the slave station device 300 based on the calculated time difference Toffset. The transmission delay time ΔT is written in the upstream DROF header, transferred to the master station device 100, and becomes a basis for generating delay time information to be added to the downstream packet.

  FIG. 5 is a diagram showing delay time measurement using PTP in the wireless communication system shown in FIG. In the case of PTP, the processing is based on the time stamp as in NTP, and includes information on the transmission time transmitted from the PTP master 172 in the time / frequency synchronization unit 170 of the master station device 100 as shown in FIG. Based on the synchronization message, the PTP slave 372 in the time / frequency synchronization unit 370 of the slave station device 300 returns a delay request message including the delay time in the synchronization message (steps S21 and S22). The PTP master 172 calculates the transmission delay time based on the content of the delay request message and the reception time, transfers it to the slave station device 300 as a delay response message, and corrects the time (step S23). That is, the time when the master station device 100 transmits the synchronization message is t1, the time when the slave station device 300 receives the synchronization message is t2, the time when the slave station device 300 transmits the delay request message is t3, and the master station device 100 is When the time at which the delay request message is received is t4, the PTP master 172 of the master station device 100 calculates the time lag Toffset and the transmission delay time ΔT by the following equations.

Toffset = ((t2-t1)-(t4-t3)) / 2

ΔT = ((t4−t3) + (t2−t1)) / 2

Next, a second embodiment of the present invention will be described.
FIG. 6 is a diagram illustrating a configuration of a wireless communication system according to the second embodiment of the present invention. In this figure, the same parts as those in the first embodiment are denoted by the same reference numerals. The difference between the present embodiment and the first embodiment is that a single master station device and a plurality of slave station devices are connected. Therefore, the master station device 101 includes a plurality of packetization processing units 121 to 12N, a plurality of DROF header processing units 131 to 13N, a plurality of network processing units 141 to 14N, and a plurality of optical interfaces 151 to 15N. These correspond to the respective slave station devices 301 to 30N. Each of the slave station devices 301 to 30N has the same configuration as that of the slave station device 300 of the first embodiment.

  In the downstream direction, the digitized radio signal output from the radio modulation / demodulation circuit 110 is packetized by the packetization processing units 121 to 12N. The radio signal is a radio baseband signal or a radio intermediate frequency band signal. After the digitized radio signal is packetized by the packetization processing units 121 to 12N, the transmission / reception device number and the like are added from the DROF header processing units 131 to 13N, and the time information from the radio modulation / demodulation circuit 110 In addition, delay time information from the timing processing unit 160 is added. After these pieces of information are added, the network processing units 141 to 14N convert the information into Ethernet (registered trademark) packets, which are output from the optical interfaces 151 to 15N to the optical fiber network 200. In the slave station devices 301 to 30N, packets from the corresponding optical interfaces 151 to 15N are extracted and processed in the same manner as the processing in the slave station device 300 described in the first embodiment.

  In the upstream direction, signals transmitted from the slave station devices 301 to 30N via the optical fiber network 200 are received by the optical interfaces 151 to 15N, and packet processing is performed. That is, the network processing units 141 to 14N extract the DROF packet from the Ethernet packets received by the optical interfaces 151 to 15N, the time information is extracted by the DROF header processing units 131 to 13N, and is transferred to the timing processing unit 160. At the same time, the digital data string is reproduced by the packetization processing units 121 to 12N. The reproduced digital data sequence is transferred to the wireless modulation / demodulation circuit 110 based on the timing data from the timing processing unit 160, and the data is demodulated.

In this embodiment, since Ethernet (registered trademark) is used for the optical fiber network 200, packet multiplexing is easy, and the network processing units 141 to 14N and the optical interfaces 151 to 15N of the master station device 101 are integrated. It is also possible to do. FIG. 7 is a diagram illustrating a configuration of a wireless communication system when packet multiplexing is used in the second embodiment.
In this case, there are a configuration using an Ethernet (registered trademark) switch 210 and a configuration using a Gigabit Ethernet (registered trademark) -Passive Optical Network (GE-PON) in connection with each of the slave station devices 301 to 30N. GE-PON is well described in IEEE 802.3ah: Amendment: Media Access Control Parameters, Physical Layers, and Management Parameters for Subscriber Access Networks, 2004.

  FIG. 8 is a diagram showing a configuration of the optical fiber network 200 when an Ethernet (registered trademark) switch 210 is used in connection with each of the slave station devices 301 to 30N. In the figure, a master station device 101 and slave station devices 301 to 30N communicate via an Ethernet (registered trademark) switch 210.

  FIG. 9 is a diagram showing this configuration when GE-PON is used in connection with each of the slave station devices 301 to 30N. In the figure, a master station device 101 and slave station devices 301 to 30N are an OLT (Optical Line Terminal) 220 and an optical coupler 230, and an ONU (Optical Network Unit) 241 corresponding to each slave station device 301 to 30N. Communicate via ~ 24N.

FIG. 10 is a diagram for explaining delay time adjustment by the wireless communication system according to the second embodiment.
In this embodiment, transmission delay times in the optical fiber network 200 are generally determined by the optical interfaces of the master station device (optical interfaces 151 to 15N in FIG. 6) and slave station devices (slave station devices 301 to 30N in FIG. 6). It depends on the combination. Therefore, even when the slave station devices 301 to 30N receive radio signals from the master station device 101 with different transmission delay times, the timings of the radio signals output from the slave station devices 301 to 30N are the same time. As described above, the delay time information of each downlink DROF packet is set to a value larger than the maximum transmission delay time. In the upstream direction, the packetization processing units 121 to 12N have the longest transmission delay time so that the radio signals received by the slave station devices 301 to 30N at the same time are simultaneously transferred to the radio modulation / demodulation circuit 110. The timing of each packet is adjusted to the timing. By performing the processing of the above delay time, as shown in a) of the figure, regardless of the delay time difference in the optical fiber network 200, the signal from the master station device 101 is sent to each of the slave station devices 301 to 301 at the same time. Transmission from 30N to the wireless terminal 500 becomes possible. Further, as shown in b) of the figure, even when the master station device 101 receives signals received from the wireless terminal 500 at the same time by the slave station devices 301 to 30N at different timings, Signals can be processed simultaneously.

FIG. 11 shows an example of a broadcast service using the communication system of this embodiment.
As shown in the figure, by using this embodiment, one master station apparatus 101 is arranged in different wireless cells 601 to 60N, and communicates with the master station apparatus 101 via the optical fiber network 200. Broadcast-type services can be performed using a plurality of slave station devices 301 to 30N. In this case, it is possible to simultaneously transmit the same signal from the radio transmission / reception circuit of each of the slave station devices 301 to 30N to the terminal device 500 in each of the radio cells 601 to 60N.

Also, according to the present embodiment, the timing of the received signal at each slave station apparatus can be adjusted, so that radio access networks of downlink TDM (time division multiplexing) and uplink TDMA (time division multiple access) are provided. It is feasible.
FIG. 12 is a diagram illustrating an example of a TDM / TDMA service using the communication system of the present embodiment. In the figure, a single master station device 101 is arranged between different slave cells 301 to 30N which are arranged in different wireless cells 601 to 60N and connected to the master station device 101 via the optical fiber network 200. A radio access network of downlink TDM (time division multiplexing) and uplink TDMA (time division multiple access) is realized.

FIG. 13 is a diagram illustrating an example of diversity in a wide area using the communication system of the present embodiment.
As shown in the figure, when a plurality of slave station devices 301 to 30N are arranged in one radio cell 600, the wireless terminal 500 is transmitted from the plurality of slave station devices 301 to 30N at the same timing in the downlink direction. A plurality of radio waves can be received. As a result, it is possible to receive a radio signal even at a point where the user interface cannot be received by a single slave station device. That is, the dead zone can be reduced by applying the transmission diversity technique in a wide area. Furthermore, in the uplink direction, a plurality of slave station devices receive radio waves from the wireless terminal 500 and transmit the received signals to the master station device 101, thereby enabling diversity reception at the master station device 101 and fading environment. High performance is realized below.

FIG. 14 is a diagram showing a configuration of a wireless modulation / demodulation circuit 110 used in the master station device 101 of FIG.
In the figure, a wireless modulation / demodulation circuit 110 includes a modulation / demodulation processing unit 112 and a diversity processing unit 111. As a diversity method, the diversity processing unit 111 in the radio modulation / demodulation circuit 110 distributes signals in the downlink direction, and in the uplink direction, any of selection combining, equal gain combining, and maximum ratio combining according to the requirements of the wireless system. Diversity can be selected. By using such diversity technology, a wide-area wireless transmission system can be realized.

  FIG. 15 is a diagram showing a wide area wireless transmission system using the wireless modulation / demodulation circuit 110 shown in FIG. 14 in the communication system of the present embodiment. As shown in FIG. 15, the wireless terminal 500 can receive diversity by a plurality of slave station devices that communicate with the master station device 101 via the optical fiber network 200, and is higher-order than the master station device 101. A high-performance wide-area wireless transmission system that performs data communication between the network 400 and the wireless terminal 500 arranged in a wide area can be constructed.

As described above, in this embodiment, transmission / reception of data with controlled timing is realized by adding time information (time information and delay time information) to a transfer packet between the master station device and the slave station device.
Furthermore, multiple slave station devices are installed so that wireless cells do not overlap each other, and the same data is transmitted to and received from multiple slave station devices at the same timing, thereby controlling the timing of data with multiple slave station devices. Realize transmission and reception.
Further, a plurality of slave station devices are installed so that wireless cells overlap each other, and the same data is transmitted / received to / from the plurality of slave station devices at the same timing. In this case, the signals received simultaneously at the wireless terminal are combined, so that a transmission diversity function is realized. Further, when the wireless terminal transmits a signal, a reception diversity function is realized by using a signal that is simultaneously received by the master station device.

It is a figure which shows the structure of the radio | wireless communications system by the 1st Embodiment of this invention. It is a figure for demonstrating transmission with a fixed delay by 1st Embodiment. It is a figure which shows the format of an NTP message packet. It is a figure which shows the time synchronous operation | movement using NTP by 1st Embodiment. It is a figure which shows the measurement of the delay time using PTP by 1st Embodiment. It is a figure which shows the structure of the radio | wireless communications system by the 2nd Embodiment of this invention. It is a figure which shows the structure of the radio | wireless communications system in the case of using the packet multiplexing by 2nd Embodiment. It is a figure which shows the structure of the optical fiber network by 2nd Embodiment. It is a figure which shows the structure of the optical fiber network by 2nd Embodiment. It is a figure for demonstrating delay time adjustment by 2nd Embodiment. It is a figure which shows the broadcast type service using the radio | wireless communications system by 2nd Embodiment. It is a figure which shows the TDM / TDMA service using the radio | wireless communications system by 2nd Embodiment. It is a figure which shows the diversity in the wide area using the radio | wireless communications system by 2nd Embodiment. It is a figure which shows the structure of the radio | wireless modulation / demodulation circuit used for the master station apparatus of FIG. It is a figure which shows the wide area radio | wireless transmission system using the radio | wireless communications system by 2nd Embodiment. It is a figure which shows the structure of the conventional digital fiber radio | wireless.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100, 101 ... Master station apparatus 110 ... Radio modulation / demodulation circuit 111 ... Diversity processing part 112 ... Modulation / demodulation processing part 120, 121-12N ... Packetization processing part 130, 131-13N ... DROF header processing part 140, 141-14N ... Network processing Units 150, 151 to 15N ... Optical interface 160 ... Timing processing unit 170 ... Time / frequency synchronization unit 171 ... NTP server unit 172 ... PTP master 200 ... Optical fiber network 210 ... Ethernet (registered trademark) switch 220 ... OLT (Optical Line Terminal) )
230 ... Optical couplers 241 to 24N ... ONU (Optical Network Unit)
300, 301 to 30N ... Slave station device 310 ... Optical interface 320 ... Network processing unit 330 ... DROF header processing unit 340 ... Timing processing unit 350 ... Packetization processing unit 360 ... Wireless transmission / reception circuit 370 ... Time / frequency synchronization unit 371 ... NTP Client unit 372 PTP slave 400 Host network 500 Wireless terminal 600, 601-60N Wireless cell

Claims (16)

A wireless communication system comprising a master station device, a slave station device, a network connecting the master station device and the slave station device, and a wireless terminal,
The master station device is
A wireless modulation circuit for modulating data;
A radio demodulation circuit for demodulating data;
A processing unit that packetizes the digital radio signal input from the radio modulation circuit and transmits the packet to the network, receives the packet from the network, converts the received packet into a digital radio signal, and transfers the packet to the radio demodulation circuit And
The slave station device is
A wireless transmission circuit for transmitting a wireless signal to the wireless terminal;
A radio receiving circuit for receiving a radio signal from the radio terminal;
A processing unit that packetizes the digital radio signal input from the radio reception circuit and transmits the packet to the network, receives the packet from the network, extracts the digital radio signal from the received packet, and transfers the packet to the radio transmission circuit And
The processing unit of the master station device and the slave station device synchronizes the time and clock frequency of the master station device and the slave station device, and adds time information to a packet to be transmitted through the network, thereby adding a digital radio signal to transmit,
The master station device measures a packet transmission delay time between the master station device and the slave station device,
The processing unit of the master station device packetizes the digital radio signal input from the radio modulation circuit, adds time information indicating the transfer time of the digital signal, and between the master station device and the slave station device Add delay information indicating a time longer than the transmission delay time and send to the network,
The processing unit of the slave station device receives the packet transmitted from the master station device from the network, and the delay information added to the packet is compared to the time indicated by the time information added to the packet. A digital wireless signal extracted from the packet is transferred to the wireless transmission circuit at the time when the time indicated is added,
A wireless communication system. A wireless communication system comprising a master station device, a slave station device, a network connecting the master station device and the slave station device, and a wireless terminal,
The master station device is
A wireless modulation circuit for modulating data;
A radio demodulation circuit for demodulating data;
A processing unit that packetizes the digital radio signal input from the radio modulation circuit and transmits the packet to the network, receives the packet from the network, converts the received packet into a digital radio signal, and transfers the packet to the radio demodulation circuit And
The slave station device is
A wireless transmission circuit for transmitting a wireless signal to the wireless terminal;
A radio receiving circuit for receiving a radio signal from the radio terminal;
A processing unit that packetizes the digital radio signal input from the radio reception circuit and transmits the packet to the network, receives the packet from the network, extracts the digital radio signal from the received packet, and transfers the packet to the radio transmission circuit And
The processing unit of the master station device and the slave station device synchronizes the time and clock frequency of the master station device and the slave station device, and adds time information to a packet to be transmitted through the network, thereby adding a digital radio signal to transmit,
The slave station device measures a packet transmission delay time between the master station device and the slave station device,
The processing unit of the slave station device packetizes the digital wireless signal input from the wireless reception circuit, and includes time information indicating a transfer time of the digital signal and a transmission delay time between the master station device and the slave station device. Add information and send it to the network,
The processing unit of the master station device receives the packet transmitted from the slave station device from the network, and the parent indicated by the information added to the packet with respect to the time indicated by the time information added to the packet. Transferring a digital radio signal extracted from the packet to the radio demodulation circuit at a time to which a delay time longer than a transmission delay time between the station device and the slave station device is added;
A wireless communication system. The master station device and a plurality of the slave station devices are connected to the network,
The processing unit of the master station device adds the same time information and the same delay information to the same digital radio signal packet and transmits the packets to the plurality of slave station devices via the network,
The processing units of the plurality of slave station devices simultaneously transfer the same digital radio signal to the radio transmission circuit of the slave station device.
The wireless communication system according to claim 1 . The master station device and a plurality of the slave station devices are connected to the network,
The processing unit of the master station device adds the individual delay time to the reception time of each packet transmitted from the plurality of slave station devices and to which the same time information is added, thereby extracting the digital extracted from each packet. Transferring a radio signal to the radio demodulation circuit simultaneously;
The wireless communication system according to claim 2 . The wireless transmission circuits of the plurality of slave station devices transmit the same wireless signal to a wireless terminal at a designated time,
The wireless terminal receives the same wireless signal transmitted from the plurality of slave station devices.
The wireless communication system according to claim 3 . The wireless terminal transmits the same wireless signal to the plurality of slave station devices,
The processing units of the plurality of slave station devices packetize a radio signal received from the radio terminal, add time information indicating a transfer time, and transmit the packet to the master station device.
The processing unit of the master station device adds the individual delay time to the reception time of each packet transmitted from the plurality of slave station devices to which time information is added, thereby extracting the digital radio signal extracted from each packet Simultaneously to the wireless demodulation circuit,
The radio demodulation circuit performs reception diversity processing of the digital radio signal received from the processing unit.
The wireless communication system according to claim 4 . The processing unit of the master station device and the slave station device uses one of a global positioning system or a network time protocol as time / frequency synchronization means,
The processing unit of the slave station device measures the transmission delay time by a network time protocol with the processing unit of the master station device, and transmits the measured transmission delay time information to the master station device.
Wireless communication system as claimed in any one of claims 6, characterized in that. The processing unit of the master station device and the slave station device uses one of a global positioning system or a precision time protocol as time / frequency synchronization means,
The processing unit of the slave station device measures the transmission delay time by a precision time protocol with the processing unit of the master station device, and transmits the measured transmission delay time information to the master station device.
The wireless communication system according to any one of claims 1 to 6 , wherein the wireless communication system is characterized by that. A wireless communication method used in a wireless communication system including a master station device, a slave station device, a network connecting the master station device and the slave station device, and a wireless terminal,
The master station device is
A wireless modulation circuit for modulating data;
A radio demodulation circuit for demodulating data;
A processing unit that packetizes the digital radio signal input from the radio modulation circuit and transmits the packet to the network, receives the packet from the network, converts the received packet into a digital radio signal, and transfers the packet to the radio demodulation circuit And
The slave station device is
A wireless transmission circuit for transmitting a wireless signal to the wireless terminal;
A radio receiving circuit for receiving a radio signal from the radio terminal;
A processing unit that packetizes the digital radio signal input from the radio reception circuit and transmits the packet to the network, receives the packet from the network, extracts the digital radio signal from the received packet, and transfers the packet to the radio transmission circuit And
The processing unit of the master station device and the slave station device synchronizes the time and clock frequency of the master station device and the slave station device, and adds time information to a packet to be transmitted through the network, thereby adding a digital radio signal to transmit,
The master station device measures a packet transmission delay time between the master station device and the slave station device,
The processing unit of the master station device packetizes the digital radio signal input from the radio modulation circuit, adds time information indicating the transfer time of the digital signal, and between the master station device and the slave station device Add delay information indicating a time longer than the transmission delay time and send to the network,
The processing unit of the slave station device receives the packet transmitted from the master station device from the network, and the delay information added to the packet is compared to the time indicated by the time information added to the packet. A digital wireless signal extracted from the packet is transferred to the wireless transmission circuit at the time when the time indicated is added,
A wireless communication method. A wireless communication method used in a wireless communication system including a master station device, a slave station device, a network connecting the master station device and the slave station device, and a wireless terminal,
The master station device is
A wireless modulation circuit for modulating data;
A radio demodulation circuit for demodulating data;
A processing unit that packetizes the digital radio signal input from the radio modulation circuit and transmits the packet to the network, receives the packet from the network, converts the received packet into a digital radio signal, and transfers the packet to the radio demodulation circuit And
The slave station device is
A wireless transmission circuit for transmitting a wireless signal to the wireless terminal;
A radio receiving circuit for receiving a radio signal from the radio terminal;
A processing unit that packetizes the digital radio signal input from the radio reception circuit and transmits the packet to the network, receives the packet from the network, extracts the digital radio signal from the received packet, and transfers the packet to the radio transmission circuit And
The processing unit of the master station device and the slave station device synchronizes the time and clock frequency of the master station device and the slave station device, and adds time information to a packet to be transmitted through the network, thereby adding a digital radio signal to transmit,
The slave station device measures a packet transmission delay time between the master station device and the slave station device,
The processing unit of the slave station device packetizes the digital radio signal input from the radio reception circuit, and includes time information indicating a transfer time of the digital signal and a transmission delay time between the master station device and the slave station device. Add information and send it to the network,
The processing unit of the master station device receives the packet transmitted by the slave station device from the network, and the parent indicated by the information added to the packet with respect to the time indicated by the time information added to the packet Transferring a digital radio signal extracted from the packet to the radio demodulation circuit at a time to which a delay time longer than a transmission delay time between the station device and the slave station device is added;
A wireless communication method. The master station device and a plurality of the slave station devices are connected to the network,
The processing unit of the master station device adds the same time information and the same delay information to the same digital radio signal packet, and transmits the packets to the plurality of slave station devices via the network,
The processing units of the plurality of slave station devices simultaneously transfer the same digital radio signal to the radio transmission circuit of the slave station device.
The wireless communication method according to claim 9 . The master station device and a plurality of the slave station devices are connected to the network,
The processing unit of the master station device adds the individual delay time to the reception time of each packet transmitted from the plurality of slave station devices and added with the same time information, thereby extracting the digital extracted from each packet Transferring a radio signal to the radio demodulation circuit simultaneously;
The wireless communication method according to claim 10, characterized in that. The wireless transmission circuits of the plurality of slave station devices transmit the same wireless signal to a wireless terminal at a designated time,
A wireless terminal receives the same wireless signal transmitted from the plurality of slave station devices.
The wireless communication method according to claim 11 . The wireless terminal transmits the same wireless signal to the plurality of slave station devices,
The processing units of the plurality of slave station devices packetize a radio signal received from the radio terminal, add time information indicating a transfer time, and transmit the packet to the master station device.
A digital radio signal extracted from each packet by the processing unit of the master station device adding an individual delay time to the reception time of each packet transmitted from the plurality of slave station devices to which time information is added. Simultaneously to the wireless demodulation circuit,
The radio demodulation circuit performs reception diversity processing of the digital radio signal received from the processing unit.
The wireless communication method according to claim 12 . The processing unit of the master station device and the slave station device uses one of a global positioning system or a network time protocol as time / frequency synchronization means,
The processing unit of the slave station device measures the transmission delay time by a network time protocol with the processing unit of the master station device, and transmits the measured transmission delay time information to the master station device.
The wireless communication method according to any one of claims 14 claim 9, characterized in that. The processing unit of the master station device and the slave station device uses one of a global positioning system or a precision time protocol as time / frequency synchronization means,
The processing unit of the slave station device measures the transmission delay time by a precision time protocol with the processing unit of the master station device, and transmits the measured transmission delay time information to the master station device.
The wireless communication method according to any one of claims 14 claim 9, characterized in that.

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