JP4637757B2 - Mobile communication system, base station apparatus, and control method for base station apparatus - Google Patents

Description

  The present invention relates to a mobile communication system, a base station apparatus, and a control method for the base station apparatus, and in particular, a first base station apparatus that receives a radio signal from a first terminal apparatus, a first base station apparatus, and a network And a second base station apparatus that transmits a radio signal to a second terminal apparatus.

  In recent years, in mobile communication systems such as mobile phones and PHS (Personal Handy-phone System), the backbone between base station apparatuses is the conventional ISDN (Integrated Service Digital Network) for the purpose of improving call quality and reducing line costs. ) Or the like is being switched to an IP (Internet Protocol) network (including the Internet). In such a mobile communication system, the base station device serves as a gateway that connects the Internet network and the wireless communication section, and plays a role of mutually converting the protocols of the IP network and the wireless communication section. That is, a base station apparatus that performs protocol conversion type voice IP communication converts voice data received from a terminal apparatus into IP packets including RTP (Real-time Transport Protocol) packets and the like, and sends the IP packets to an IP network. Conversely, the IP packet received from the IP network is converted into a radio signal corresponding to the voice data and transmitted to the terminal device.

In addition, there is an end-to-end type voice IP communication system that does not require protocol conversion in the base station apparatus by converting the communication protocol in the wireless section to IP. For example, in Patent Document 1 below, in a wireless information terminal that performs end-to-end real-time data communication such as VoIP (Voice over IP) via an IP network and a wireless section, between the wireless information terminal and the IP network. Session information based on the wireless status of the wireless section and the wireless interface information of the wireless information terminal (wireless interface device type, voice codec type, voice codec packetization period, real-time communication data transmission status, etc.) A technique for determining (RTP parameter information and the like) and establishing a session is disclosed. According to this technique, when an IP network and a wireless communication section are seamlessly connected on an IP basis, and one wireless communication state deteriorates during communication, session information is re-determined in the wireless information terminal, and SIP (Session Initiation Protocol) The session information can be shared by both terminals through a call control protocol such as
JP 2004-328079 A

  In a system that performs the above-described protocol conversion type voice IP communication in which the IP network and the non-IP-based wireless communication section are connected by the base station apparatus, the base station apparatus grasps the communication state in the wireless section on the communication partner side. There was no way to do it. For this reason, for example, even if one terminal device has a situation in which a FER (Frame Error Rate) increases due to the deterioration of the radio wave condition and a handover is required, the base station device on the communication partner side starts the handover. Because it is impossible to know the timing, it is impossible to perform control such as discarding the noise signal generated at the time of handover and transmitting a silence signal to the terminal device instead, and noise is sent to the partner terminal There was a problem.

  The present invention has been made in view of the above-described conventional problems. In the base station apparatus, the end-to-end communication state can be maintained in an optimum state according to the wireless communication quality on the communication partner side. It is an object of the present invention to provide a mobile communication system, a base station apparatus, and a control method for the base station apparatus.

  To achieve the above object, a mobile communication system according to the present invention is connected to a first base station apparatus that receives a radio signal from a first terminal apparatus, and the first base station apparatus via a network. And a second base station apparatus that transmits a radio signal to the second terminal apparatus, wherein the first base station apparatus receives from the first terminal apparatus Radio communication quality information representing communication quality in radio communication between the first terminal device and means for converting the radio signal into real-time data corresponding to the signal and transmitting the real-time data to the second base station device Communication quality notification means for notifying the second base station apparatus of the communication quality, and the second base station apparatus responds to the received real-time data with the real-time data received from the first base station apparatus. A radio signal corresponding to the received real-time data, based on radio communication quality information notified from the first base station apparatus, and means for converting the radio signal into the second terminal apparatus And wireless communication control means for restricting transmission of signals to the second terminal device.

  A base station apparatus according to the present invention is a base station apparatus that receives real-time data corresponding to a radio signal from another base station apparatus that receives the radio signal from the first terminal apparatus via a network. Generating a radio signal corresponding to the real-time data received from the other base station apparatus, transmitting the radio signal to the second terminal apparatus, and notifying from the other base station apparatus, Based on wireless communication quality information indicating communication quality in wireless communication between a base station device and the first terminal device, a wireless signal corresponding to the received real-time data is transmitted to the second terminal device. And a wireless communication control means for adding a restriction.

  The base station apparatus control method according to the present invention also includes a base station apparatus that receives real-time data corresponding to a radio signal from another base station apparatus that receives the radio signal from the first terminal apparatus via a network. A method of generating a radio signal corresponding to real-time data received from the other base station apparatus, transmitting the radio signal to a second terminal apparatus, and notifying from the other base station apparatus The second radio signal corresponding to the received real-time data is based on the wireless communication quality information indicating the communication quality in the wireless communication between the other base station device and the first terminal device. And a wireless communication control step for restricting transmission to the terminal device.

  In the present invention, the base station apparatus receives real-time data corresponding to the radio signal from another base station apparatus that receives the radio signal from the first terminal apparatus. And the radio signal according to the real-time data received from the other base station apparatus is produced | generated, and this radio signal is transmitted to a 2nd terminal device. Moreover, the radio | wireless communication quality information between this other base station apparatus and 1st terminal device notified from another base station apparatus is acquired. Based on the wireless communication quality information, transmission of a wireless signal corresponding to the received real-time data to the second terminal device is limited. ADVANTAGE OF THE INVENTION According to this invention, in the base station apparatus, it becomes possible to grasp | ascertain the radio | wireless communication quality of a communicating party side in real time, and to control transmission of the radio signal to a terminal device according to it, End-to-End communication The state can be kept in an optimum state.

  In the aspect of the present invention, the real-time data is voice data, and the wireless communication control unit is configured to perform the second operation when the communication quality indicated by the wireless communication quality information is equal to or lower than a predetermined quality. A wireless signal corresponding to silent audio data is transmitted to the terminal device, or transmission of the wireless signal to the second terminal device is stopped. In this way, in the base station apparatus, the wireless communication quality of the communication partner side is grasped in real time, and the wireless signal corresponding to the silent audio data is transmitted to the terminal apparatus accordingly, or the wireless signal is transmitted to the terminal apparatus. Can be stopped, and the end-to-end communication state in voice communication can be maintained in an optimum state.

  In one embodiment of the present invention, the network is an IP network. In this way, in the base station device that connects the IP network and the non-IP-based wireless communication section, the wireless communication quality of the communication partner side is grasped in real time, and the transmission of the wireless signal to the terminal device is controlled accordingly. Thus, the end-to-end communication state can be maintained in an optimum state.

  In one aspect of the present invention, the transmission of the real-time data is performed based on RTP (Real-time Transport Protocol), and the communication quality notification means converts the wireless communication quality information into an RTCP (RTP Control Protocol) packet. To the second base station apparatus. In this way, in the base station device that connects the IP network and the non-IP-based wireless communication section, the wireless communication quality of the communication partner is received at any time by the PTCP packet, and the wireless signal is transmitted to the terminal device accordingly. It becomes possible to control the end-to-end communication state in the real-time data transmission / reception based on RTP.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a mobile communication system 10 according to an embodiment of the present invention. As shown in the figure, the mobile communication system 10 includes a plurality of base station devices 12 connected to an IP network 16 and a plurality of terminal devices 14 connected to the base station devices 12 through wireless transmission paths. Consists of.

  FIG. 2 is a functional block diagram showing the configuration of the base station apparatus 12. The base station apparatus 12 includes a control unit 20, an antenna 30, a radio communication unit 40, and an IP interface unit 50, and transmits and receives radio signals to and from each of the plurality of terminal apparatuses 14 and also a plurality of other base station apparatuses. Real-time data is transmitted / received via the IP network 16 with each.

  Hereinafter, the base station apparatus 12a in the case where the terminal apparatus 14a and the terminal apparatus 14b mutually transmit and receive real-time data in FIG. 1 will be described as an example. The base station device 12a receives real-time data corresponding to the radio signal from the base station device 12b that receives the radio signal from the terminal device 14b via the IP network 16, and a radio signal corresponding to the received real-time data. And transmits the radio signal to the terminal device 14a. The base station apparatus 12a receives a radio signal from the terminal apparatus 14a, generates real-time data corresponding to the radio signal, and transmits the real-time data to the base station apparatus 12b via the IP network 16.

  The wireless communication unit 40 includes a wireless unit 42, a demodulation unit 44, a modulation unit 46, and a signal processing unit 48. The antenna 30 is connected to the radio unit 42. The wireless unit 42 includes a transmission unit and a reception unit, and sequentially switches between transmission and reception by controlling the antenna 30 in a time division manner. The reception unit of the radio unit 42 includes a low noise amplifier, a down converter, and the like, amplifies the reception signal received by the antenna 30 and outputs the amplified signal to the demodulation unit 44. The demodulator 44 converts the received signal input from the receiver of the radio unit 42 into a baseband signal and outputs the baseband signal to the signal processor 48. The modulation unit 46 converts the baseband signal input from the signal processing unit 48 into a transmission signal and outputs the transmission signal to the transmission unit of the radio unit 42. The transmission unit of the radio unit 42 includes an up converter, a power amplifier, and the like, amplifies the transmission signal input from the modulation unit 46 to a transmission output level, and outputs the amplified signal to the antenna 30.

  The signal processing unit 48 includes a signal conversion circuit or the like, converts a plurality of real-time data input from the real-time data processing unit 24 of the control unit 20 into a baseband signal, and transmits the baseband signal to the terminal device 14a. Output to the modulation unit 46. In addition, real-time data is extracted from the baseband signal from the terminal device 14 a input from the demodulation unit 44, and the real-time data is output to the real-time data processing unit 24.

  The IP interface unit 50 is connected to the IP network 16 (including the Internet) and is also connected to the real-time data processing unit 24 and the communication quality notification unit 26, and inputs from the real-time data processing unit 24 and the communication quality notification unit 26, respectively. The RTP packet and the RTCP packet to be transmitted are transmitted to the base station apparatus 12b via the IP network 16. Further, the IP interface unit 50 outputs the RTP packet and the RTCP packet from the base station apparatus 12b input from the IP network 16 to the real time data processing unit 24 and the communication quality measuring unit 26, respectively.

  The control unit 20 includes a wireless communication quality measurement unit 22, a real-time data processing unit 24, a communication quality notification unit 26, and a wireless communication control unit 28, and controls the entire base station apparatus 12. The control unit 20 includes a CPU and a memory.

  The wireless communication quality measuring unit 22 is connected to the wireless unit 42, measures communication quality in wireless communication with the terminal device 14a based on a received signal from the terminal device 14a, and communicates wireless communication quality information representing the communication quality. The data is output to the quality measuring unit 26. The communication quality is expressed by, for example, the size of the FER, and the FER increases with the deterioration of the radio wave state, that is, with the increase of the interference wave level. Therefore, the wireless communication quality information includes the FER in the wireless communication between the terminal device 14a and the base station device 12a and the ratio (D / of the desired wave signal level received by the base station device 12a to the interference wave signal level). U ratio) or the like is used.

  The real-time data processing unit 24 generates an RTP packet by adding an RTP header or the like to the real-time data input from the signal processing unit 48 and outputs the RTP packet to the IP interface unit 50. In addition, real-time data is extracted from the RTP packet received from the IP network 16 and output to the signal processing unit 48. Further, the real-time data processing unit 24 measures the loss of the received RTP packet, the jitter (distortion) of the arrival time interval, and the like, and periodically sends statistical data related to the measurement to the communication quality notification unit 26. As shown in FIG. 3, the RTP packet includes an IP header, a UDP (User Datagram Protocol) header, an RTP header, and an RTP payload including real-time data such as G711 and G723.1.

  The communication quality notification unit 26 acquires statistical data related to the received RTP packet from the real-time data processing unit 24, generates an RTCP packet by adding an RTCP header or the like to the statistical data, and outputs the RTCP packet to the IP interface unit 50. Further, statistical data regarding the RTP packet on the communication partner side is extracted from the RTCP packet input from the IP interface unit 50. RTCP is a protocol that transmits and receives audio / video data itself, while RTCP periodically evaluates line quality such as packet loss, delay jitter, and round trip, and realizes real-time communication that matches the bandwidth. This is a protocol for transmitting and receiving information.

  Further, the communication quality notification unit 26 adds an RTCP header or the like to the wireless communication quality information input from the wireless communication quality measurement unit 22 to generate an RTCP packet, and outputs the RTCP packet to the IP interface unit 50. This RTCP packet is, for example, an RTCP packet APP (Application-Defined). Further, the wireless communication quality information on the communication partner side (between the base station device 12 b and the terminal device 14 b) is extracted from the RTCP packet input from the IP interface unit 50 and output to the wireless communication control unit 28. Thereby, the base station apparatus can grasp | ascertain the communication state in the radio area of the communicating party side. Note that the communication quality notifying unit 26 receives the wireless communication quality information input from the wireless communication quality measuring unit 22 as one of RTCP packets, and is described below as a sender report (hereinafter referred to as SR) or a receiver report (hereinafter referred to as receiver report). , RR) or the like (eg, profile-specific extension), and may be output to the IP interface unit 50.

  As shown in FIG. 4, the RTCP packet is composed of an RTCP payload including an IP header, a UDP header, an RTCP header, sender information, a report block, and the like. RR, which is one of the RTCP packets, is an RTCP packet for notifying the sender of the RTP reception status (information regarding the reception quality of the RTP packet) from the receiver. As shown in FIG. Is version information (V: Version), padding (P: Padding), reception report count (RC), packet type (PT), report length, and the synchronous transmission source of the sender of this packet ( Each field for storing an SSRC (Sychronization Source) identifier is provided. In addition, a report block made up of RTP reception information is stored in the RTCP payload following the RTCP header. That is, the report block includes a synchronous sender (SSRC) identifier of a packet sender, an RTP loss rate, a number of lost RTP packets, a reception sequence number, an average jitter of arrival time intervals, and a transmission of the SR received last. The time from when the SR was last received until this RR is sent is stored.

  SR, which is one of the RTCP packets, is an RTCP packet for notifying the transmission state (information on transmission real-time data) from the sender to the receiver. In the SR, as shown in FIG. 5, as RTCP payload following the RTCP header, sender information including an NTP (Network Time Protocol) time stamp, an RTP time stamp, a transmission RTP packet number, and a transmission RTP byte number is stored. A report block consisting of RTP transmission information is to be stored. Both SR and RR can use profile-specific extension for additional information.

  The wireless communication control unit 28 receives the real-time data received from the base station device 12b based on the wireless communication quality information of the communication partner (between the base station device 12b and the terminal device 14b) input from the communication quality notification unit 26. Restriction is applied to the transmission of the radio signal corresponding to the terminal device 12a. For example, when the received real-time data is voice data, if the communication quality (for example, FER or D / U ratio) between the base station device 12b and the terminal device 14b is below a predetermined quality, the terminal device 14b May be handed over to a base station apparatus (for example, base station apparatus 12c in FIG. 1) to prevent deterioration of communication quality. At this time, the base station apparatus 12a can grasp the start timing of the handover of the terminal apparatus 14b in advance from the wireless communication quality information notified from the base station apparatus 12b as needed. For this reason, it is possible to perform control so that the noise generated during the handover is not transmitted to the terminal device 14a as it is. That is, the base station apparatus 12a can transmit a radio signal corresponding to silent audio data to the terminal apparatus 14a at the timing when the terminal apparatus 14b which is the communication partner of the terminal apparatus 14a starts handover. Moreover, you may stop transmission of the radio signal to the terminal device 14a. In this way, it is possible to prevent noise generated during handover from being sent to the counterpart terminal device.

  Next, noise silence processing at the time of handover according to the embodiment of the present invention will be described based on the flowchart of FIG. Here, it is assumed that the terminal device 14a wirelessly connected to the base station device 12a and the terminal device 14b wirelessly connected to the base station device 12b perform voice communication (wireless signals transmitted and received by the terminal devices 14a and 14b, etc.) Is not shown). In FIG. 7, the RTP packet and RTCP packet from the base station apparatus 12a and the RTP packet and RTCP packet from the base station apparatus 12b are shown to be transmitted in the same number and alternately. The number of packets and the transmission order are not limited to the processing sequence shown in FIG.

  First, voice communication is started between the terminal device 14a and the terminal device 14b (S100). The base station device 12a converts the received signal from the terminal device 14a into voice data by the signal processing unit 48, converts the voice data into the RTP packet format by the real-time data processing unit 24, and then passes through the IP interface unit 50. The RTP packet is transmitted to the base station apparatus 12b (S102). At the same time or before and after, the base station device 12a receives an RTP packet including voice data corresponding to the received signal from the terminal device 14b from the base station device 12b via the IP interface 50 (S104). The base station device 12a extracts voice data from the RTP packet received by the real-time data processing unit 24, converts the voice data into a radio signal by the signal processing unit 24, and transmits the radio signal to the terminal device 12a.

  During this time, the base station apparatus 12a and the base station apparatus 12b measure various transmission information related to voice data, statistical information regarding the reception status of RTP packets measured by the real-time data processing unit 24, or measurement by the wireless communication quality measuring unit 22. The wireless communication quality information (for example, FER) and the like with the terminal device to be transmitted is converted into the RTCP packet format by the communication quality notification unit 26 and transmitted to the base station device on the other side with high frequency (S106, S108). ). Similarly, the base station apparatus 12a and the base station apparatus 12b repeat transmission / reception of RTP packets and RTCP packets (S110, S112, S114).

  Here, when the radio wave condition near the base station device 12b deteriorates and the FER in the wireless communication with the terminal device 14b increases in the base station device 12b, the base station device 12a receives the FER notified from the base station device 12b. Based on the above, the increase in FER in the base station apparatus 14b is recognized, and the terminal apparatus 14b grasps the start and timing of the handover (S116). When the FER exceeds a predetermined value, the terminal device 14b disconnects the voice communication with the terminal device 14a (S118), and hands over from the base station device 12b to the base station device 12c (S120). During this time (from S118 to S120), the base station apparatus 12a temporarily stops the transmission of the radio signal to the terminal apparatus 12a by the radio communication control unit 28, and the noise generated with the handover of the terminal apparatus 14b remains as it is. To prevent being sent to.

  According to the mobile communication system, the base station apparatus, and the control method for the base station apparatus described above, the base station apparatus grasps the wireless communication quality of the communication counterpart in real time, and accordingly the radio signal to the terminal apparatus Can be controlled, and the end-to-end communication state can be maintained in an optimum state.

  The present invention is not limited to the embodiment described above. For example, the present invention is applicable not only to mobile communication systems in which base station apparatuses connected via an IP network transmit and receive RTP packets to each other, but also to all types of mobile communication systems in which base station apparatuses are connected via a network. Is possible.

1 is a configuration diagram of a mobile communication system according to an embodiment of the present invention. It is a functional block diagram of the base station apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of a RTP packet. It is a figure which shows the structure of a RTCP packet. It is a figure which shows the structure of a RTCP packet (Sender Report). It is a figure which shows the structure of a RTCP packet (Receiver Report). It is a sequence diagram explaining the silence process of the noise which generate | occur | produces at the time of a hand-over.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Mobile communication system, 12 Base station apparatus, 14 Mobile station apparatus, 16 Communication network, 20 Control part, 22 Wireless communication quality measurement part, 24 Real time data processing part, 26 Communication quality notification part, 28 Wireless communication control part, 30 Antenna, 40 Radio communication unit, 42 Radio unit, 44 Demodulation unit, 46 Modulation unit, 48 Signal processing unit, 50 IP interface unit

Claims (6)

A first base station device that receives a radio signal from a first terminal device, and a second base that is connected to the first base station device via a network and transmits a radio signal to the second terminal device A mobile communication system including a station device,
The first base station apparatus
Means for converting a radio signal received from the first terminal device into real-time data corresponding to the signal, and transmitting the real-time data to the second base station device;
Communication quality notification means for notifying the second base station device of wireless communication quality information indicating communication quality in wireless communication with the first terminal device;
The second base station apparatus is
Means for converting real-time data received from the first base station apparatus into a radio signal corresponding to the received real-time data, and transmitting the radio signal to the second terminal apparatus;
Wireless communication control means for restricting transmission of the wireless signal corresponding to the received real-time data to the second terminal device based on the wireless communication quality information notified from the first base station device ,
A mobile communication system. The mobile communication system according to claim 1, wherein
The real-time data is audio data,
The wireless communication control means transmits a wireless signal corresponding to silent audio data to the second terminal device when the communication quality represented by the wireless communication quality information is equal to or lower than a predetermined quality, or the first Stop transmitting wireless signals to the terminal device of 2,
A mobile communication system. The mobile communication system according to claim 1 or 2,
The network is an IP network;
A mobile communication system. The mobile communication system according to claim 3,
The transmission of the real-time data is performed based on RTP (Real-time Transport Protocol),
The communication quality notification means includes the wireless communication quality information in an RTCP (RTP Control Protocol) packet and notifies the second base station apparatus;
A mobile communication system. A base station device that receives, via a network, real-time data corresponding to the radio signal from another base station device that receives the radio signal from the first terminal device,
Means for generating a radio signal according to real-time data received from the other base station apparatus, and transmitting the radio signal to a second terminal apparatus;
According to the received real-time data based on the wireless communication quality information indicating the communication quality in the wireless communication between the other base station device and the first terminal device, notified from the other base station device. Wireless communication control means for restricting transmission of the transmitted wireless signal to the second terminal device,
A base station apparatus. A control method for a base station apparatus that receives real-time data corresponding to a radio signal from another base station apparatus that receives a radio signal from a first terminal apparatus via a network,
Generating a radio signal corresponding to the real-time data received from the other base station apparatus, and transmitting the radio signal to the second terminal apparatus;
According to the received real-time data based on the wireless communication quality information indicating the communication quality in the wireless communication between the other base station device and the first terminal device, notified from the other base station device. A wireless communication control step of restricting transmission of the transmitted wireless signal to the second terminal device,
A control method for a base station apparatus.

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