Communication apparatus, communication system and communication method

A communication apparatus wherein the function arrangement of each device is revised, thereby preventing an increase in traffic of a public network and further suppressing an increase in communication cost of the public network. In this apparatus, a control part (101), when notified of a duplication of MBMS data by RNC-c, controls a PDCP part (102), an RLC part (103) and a MAC-d part (104) so as to perform an MBMS data duplication process. The control part (101), when notified of an establishment of a communication line with a node (B), controls the PDCP part (102), RLC part (103) and MAC-d part (104) so as to establish the communication line with the node (B). The RLC part (103) duplicates, based on the control by the control part (101), the MBMS data received from the PDCP part (102). The MAC-d part (104) transmits the MBMS data as MAC processed to the node (B) via a local network between an RNC-u (100) and the node (B).

TECHNICAL FIELD

The present invention relates to a communication apparatus, communication system and communication method. More particularly, the present invention relates to a communication apparatus, communication system and communication method that provide multicast packet communication services.

BACKGROUND ART

FIG. 1is a view showing the configuration of a packet communication system that provides multicast packet communication services (Multimedia Broadcast/Multicast Services) (hereinafter referred to as “MBMS”). In MBMS, control station apparatus (hereinafter referred to as “RNC”)10duplicates MBMS data and transfers the result to base station apparatuses (hereinafter referred to as “Node B”)11. InFIG. 1, the solid line shows the signal flow in the user plane (hereinafter referred to as “U-plane”), and the dotted line shows the signal flow in the control plane (hereinafter referred to as “C-plane”).

Service center (Broadcast/Multicast Service Center) (hereinafter referred to as “BM-SC”)12provides MBMS. Core network (hereinafter referred to as “CN”)13is comprised of a GGSN (Gateway GPRS Support Node) and an SGSN (Serving GPRS Support Node), which are not illustrated. GGSN performs the setup (i.e. setup for the bearer plane) for transporting MBMS data to and from the SGSN, in accordance with commands from BM-SC12. SGSN carries out MBMS control for each user (including MBMS multicast service activation, MBMS session start, MBMS registration, MBMS session stop), and transmits MBMS data to radio access network (hereinafter referred to as “RAN”)14. RAN14is composed of RNC10, Node B11, and public network15. To allow efficient transmission of MBMS data, RNC10duplicates MBMS data and transmits the result to each Node B11. Each Node B11transmits the received MBMS data to a radio interface. Public network15is used to transmit data between RNC10and Node B11. Terminal apparatus (User Equipment) (hereinafter referred to as “UE”)16performs MBMS bearer service control, and receives MBMS data.

DISCLOSURE OF INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

However, conventionally, there is a problem that since MBMS data of the same content duplicated by the RNC is transmitted by using the public network, the traffic in the public network increases, and the communication cost of the public network increases.

It is therefore an object of the present invention to provide a communication apparatus, communication system and communication method for preventing traffic increase in the public network and increase in communication cost in the public network by redoing function allocation to apparatuses.

MEANS FOR SOLVING THE PROBLEM

The communication apparatus of the present invention adopts a configuration having: a receiving section that receives packet data to be transmitted to a plurality of slave base station apparatuses, from a public network; a control section that determines whether a notice regarding duplication of the packet data is received; a duplicating section that duplicates the packet data received at the receiving section if the control section determines that the notice is received; and a transmitting section that transmits the packet data duplicated at the duplicating section to a base station apparatuses, by a local network built in a predetermined area.

The communication system of the present invention adopts a configuration having: an upper station apparatus that duplicates packet data received via a public network and transmits the duplicated packet data by a local network built in a predetermined area; a plurality of base station apparatuses that receive the packet data transmitted from the upper station apparatus, via the local network, and transmit the received packet data by a radio channel; and a mobile terminal apparatus that receives the packet data transmitted from the base station apparatuses, via the radio channel.

The communication method of the present invention provides the steps of: receiving packet data at an upper station apparatus, via a public network; duplicating the packet data at the upper station apparatus that received the packet data; transmitting the duplicated packet data from the upper station apparatus to a plurality of base station apparatuses, by a local network built in a predetermined area; receiving at a base station apparatus the packet data transmitted from the upper station apparatus, by the local network; transmitting the received packet data from the base station apparatuses to a terminal apparatus by a radio channel; and receiving the packet data transmitted from the base station apparatuses at the terminal apparatus via the radio channel.

ADVANTAGEOUS EFFECTS OF THE INVENTION

The present invention makes it possible to prevent traffic increase in the public network and increase in communication cost in the public network, by redoing function allocation to apparatuses.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 2is a block diagram showing a configuration of RNC-u100, which is a communication apparatus according to embodiment 1 of the present invention. In embodiment 1 of the present invention, RNC which is an upper station apparatus, is divided into an RNC-c (first upper station apparatus) to which mainly the C-plane functions of the RNC are allocated, and an RNC-u (second upper station apparatus) to which mainly the U-plane functions of the RNC are allocated. RNC-u100inFIG. 2are allocated mainly the U-plane functions of the RNC.

Control section101carries out control between RNC-u100and an RNC-c (described later). Specifically, control section101controls PDCP section102, RLC section103and MAC-d section104, based on control signals and information about the radio resource control result received from the RNC-c and received via the public network. Also, when control section101receives a notice regarding duplication of MBMS data from RNC-c, control section101controls PDCP section102, RLC section103and MAC-d section104to perform a MBMS data duplication process. Also, when control section101receives a notice regarding establishment of a channel with a Node B, control section101controls PDCP section102, RLC section103and MAC-d section104, to establish a channel with the Node B. Also, when control section101receives a notice regarding MBMS data duplication process or establishment of a channel with the Node B, control section101transmits a response signal to the RNC-c, via the public network. Then, control section101outputs the information on the radio resource control results to MAC-d section104.

Based on the control from control section101, PDCP section102performs IP header compression and the like, on the MBMS data transmitted from a CN (not shown) and received via the public network, in accordance with the packet protocol of radio layer2, and outputs the result to RLC section103.

RLC section103, which is a duplicating means, duplicates the MBMS data inputted from PDCP section102, based on the control from control section101. Then, RLC section103outputs the duplicated MBMS data to MAC-d section104.

MAC-d section104establishes a channel with the Node B, based on the control from control section101. Also, based on the control from control section101, MAC-d section104performs MAC processing of the dedicated channel, on the MBMS data inputted from RLC section103, in accordance with the MAC protocol of radio layer2. Then, MAC-d section104transmits the MAC-processed MBMS data to the Node B, via a local network. Also, MAC-d section104transmits information about the radio resource control result inputted from control section101, to the Node B, via the local network. Here, the local network represents a network built in a predetermined area, such as a private LAN (local area network).

Next, the configuration of RNC-c200will be described usingFIG. 3.FIG. 3is a block diagram showing a configuration of RNC-c200. RNC-c200ofFIG. 3is an entity where mainly the C-plane functions of the RNC are allocated.

SRNCF section201has a control function of the serving RNC in the conventional RNC. More specifically, SRNCF section201outputs a control signal, such as a handover command, etc. for controlling each UE, to Node B control section202, based on the control signal received from a CN (not shown), and also outputs a control signal for controlling RNC-u100, to RNC-u control section203. Also, upon determining that RNC-u100is selected by the Node B from RNC-c selection information inputted from Node B control section202for selection of the RNC-c, SRNCF section201selects RNC-u100for the communicating party of the Node B that transmits duplicated packet data to the Node B, based on the communication environment, using, for example, information about the RNC-u processing condition inputted from RNC-u control section203or information about the amount of delay between Node B300and RNC-u100. Then, SRNCF section201outputs the RNC-u selection information, which is information about the selected RNC-u100, to RNC-u control section203. Also, in the case that a request signal for establishment of a control channel with the UE is inputted from RRC section206, SRNCF section201commands RNC-u control section203to establish a control channel between the selected RNC-u100and the Node B. SRNCF section201outputs the information on the radio resource control result inputted from RRC section206, to RNC-u control section203.

Node B control section202is adapted to perform control between RNC-c200and the Node B, and it is possible to apply the RNSAP of 3GPP TS25.423. Node B control section202transmits control signals to the Node B via the public network, and receives control signals transmitted from the Node B via the public network. Also, Node B control section202outputs RNC-c selection information, which is received from the Node B via the public network and which is about the RNC-c selected by the Node B, to SRNCF section201. Node B control section202transmits information about the communication environment, using, for example, information about the MBMS processing condition of RNC-c200or information about the amount of delay between Node B300and RNC-c200, to the public network, to thus transmit that to the Node B.

RNC-u control section203carries out control between RNC-u100and RNC-c200. More specifically, RNC-u control section203transmits the control signals inputted from SRNCF section201, to RNC-u100, via the public network. Also, from the RNC-u selection information inputted from SRNCF section201, RNC-u control section203tells the selected RNC-u100, via the public network, to perform a MBMS data duplication process. When RNC-u control section203is commanded by SRNCF section201to establish a channel with the Node B and transmit MBMS data, RNC-u control section203tells the selected RNC-u100, via the public network, to establish a channel between the selected RNC-u100and the Node B. RNC-u control section203transmits the information about the radio resource control result inputted from SRNCF section201, to RNC-u100, via the public network.

MAC-d section204receives the request signal for channel establishment for controlling the UE, from the Node B, via the public network. Then, MAC-d section204performs MAC processing for the dedicated channel, on the received request signal for channel establishment, in accordance with the MAC protocol of radio layer2, and outputs the result to RLC section205.

RLC section205performs retransmission control on the MAC-processed request signal for channel establishment inputted from MAC-d section204, in accordance with the retransmission protocol of radio layer2. Then, RLC section205outputs the retransmission control result to RRC section206.

RRC section206performs radio resource control on the retransmission control result inputted from RLC section205. Then, RRC section206outputs information about the request signal for establishing a control channel with the UE after radio resource control, and the radio resource control result, to SRNCF section201.

Next, the configuration of Node B300will be described usingFIG. 4.FIG. 4is a block diagram showing the configuration of Node B300.

Control section301performs control between RNC-c200and Node B300. More specifically, control section301selects RNC-c200, based on information about the communication environment. using, for example, information about the MBMS data processing condition of RNC-c200or information about the delay amount between Node B300and RNC-c200transmitted from Node B control section202and received via the public network. Then, control section301commands CRNCF section302to transmit the request signal for establishing a channel, to the selected RNC-c200, and transmits RNC-c200selection information of the selected RNC-c200, to RNC-c200, via the public network.

CRNCF section302has the control function of the controlling RNC in the conventional RNC. More specifically, in the case that CRNCF section302is commanded by control section301to transmit a request signal for channel establishment to the selected RNC-c200, CRNCF section302performs control of radio cell units, using, for example, information about the availability of each cell and information about the codes in use. Then, CRNCF section302outputs the control result to RRC section303.

RRC section303performs radio resource control, using the control results inputted from CRNCF section302. Then, RRC section303controls MAC processing section304and PHY section305, based on the radio resource control result. Also, RRC section303transmits the information about the radio resource control result to the UE.

When a request signal for channel establishment is inputted from PHY section305, MAC processing section304performs MAC processing on the common channel, based on the control from RRC section303, in accordance with the MAC protocol of radio layer2, and transmits the request signal for channel establishment to the selected RNC-c200, via the public network. Also, based on the control from RRC section303MAC processing section304receives the MBMS data transmitted from MAC-d section104of RNC-u100, via a local network. Then, MAC processing section304outputs the MBMS data to PHY section305. Also, MAC processing section304outputs information about the radio resource control result transmitted from RNC-u100and received via the local network, to PHY section305.

Based on the control from RRC section303, PHY section305performs modulation and demodulation, and the like, of the MBMS data inputted from MAC processing section304, for radio-transmission it, in accordance with physical layer protocol of radio layer1, and outputs the result to the UE by a radio channel. Also, PHY section305receives the request signal for channel establishment, received from the UE, and outputs the signal to MAC processing section304. PHY section305performs modulation, and the like, of the information about the radio resource control result inputted from MAC processing section304, and transmits the result to the UE by a radio channel.

Next, the configuration of UE400will be described usingFIG. 5.FIG. 5is a block diagram showing the configuration of UE400.

RRC section401controls MAC processing section403, MAC-d section404, RLC section405and PDCP section406, based on information about the radio resource control result received from RRC section303of Node B300. Also, when RRC section401starts communication, outputs the request signal for channel establishment, to PHY section402.

PHY section402performs demodulation, and the like, of the MBMS data received from PHY section305of Node B300, in accordance with the physical layer protocol of radio layer1, and outputs the result to MAC processing section403. Also, when a request signal for channel establishment is inputted from RRC section401, PHY section402transmits the request signal for channel establishment, to PHY section305of Node B300.

MAC processing section403performs MAC processing of the common channel, on the MBMS data inputted from PHY section402, in accordance with the MAC protocol of radio layer2. Then, MAC processing section403outputs the MAC-processed MBMS data to MAC-d section404.

MAC-d section404performs MAC processing of the dedicated channel, on the MBMS data inputted from MAC processing section403, in accordance with the MAC protocol of radio layer2. Then, MAC-d section404outputs the MAC-processed MBMS data to RLC section405.

RLC section405processes the MBMS data inputted from MAC-d section404, in accordance with the retransmission protocol of radio layer2, and outputs the result to PDCP section406.

PDCP section406processes the MBMS data inputted from RLC section405, in accordance with the packet protocol of radio layer2.

Next, the function allocation of the RNC and Node B will be described usingFIG. 6.FIG. 6is a schematic view showing a packet communication system which employs RNC-u100, RNC-c200, Node B300and UE400. InFIG. 6, the broken lines show control signal channels and the solid lines show MBMS data channels.

The packet communication system shown inFIG. 6is configured by dividing the functions of the RNC into RNC-c200, to which mainly the C-plane functions of the RNC are allocated, and RNC-c200, to which mainly the U-plane functions of the RNC are allocated, and allocating part of the functions of the RNC to Node B300. The MBMS data from CN13is not duplicated upstream of public network502, but is duplicated in RNC-u100, which is provided downstream of public network502, and is distributed to slave Nodes B300. InFIG. 6, RNC-c200has the same configuration as that shown inFIG. 3, RNC-u100has the same configuration as that shown inFIG. 2, and Nodes B300have the same configuration as that shown inFIG. 4.

Next, the operation of RNC-u100, RNC-c200, Node B300and UE400will be described usingFIG. 7.FIG. 7is a sequence diagram showing the operation of RNC-u100, RNC-c200, Node B300and UE400. The circle symbols inFIG. 7show that the messages pass through the above-mentioned nodes.

First, UE400transmits an “RRC connection request” from PHY section402to PHY section305of Node B300, to set up the RRC connection (step ST601). Next, control section301of Node B300selects RNC-c200for C-plane processing, based on the communication environment using, for example, information about MBMS data duplication process condition or information about the delay amount between Node B300and RNC-c200.

Next, PHY section305of Node B300transmits the “RRC connection request” received from UE400to the selected RNC-c200, via MAC processing section304, RRC section303, CRNCF section302and control section301(step ST602). Next, RNC-c200, which received the “RRC connection request” at MAC-d section204, transmits a “radio link setup request” from Node B control section202to Node B300, via the public network, to set up a radio link for RRC connection (step ST603).

Next, Node B300, which received the “radio link setup request” at control section301, performs the radio link setup in Node B300, and transmits a “radio link setup response” from control section301to RNC-c200(step ST604).

Next, in RNC-c200, which has received the “radio link setup response” at Node B control section202, SRNCF section201selects RNC-u100for U-plane processing, based on the communication environment, using, for example, information about the processing condition of RNC-u100or information about the delay amount between Node B300and RNC-u100. Next, RNC-c200transmits a “RRC connection setup” from RRC section206to Node B300, via SRNCF section201and Node B control section202, to set up a radio link for RRC connection. Further, Node B300, which has received the “RRC connection setup” at control section301, transmits the “RRC connection setup” from RRC section303to UE400, via CRNCF section302(step ST605).

Next, UE400which received the “RRC connection setup” performs the radio link setup for RRC connection and transmits an “RRC connection setup complete” from RRC section401to Node B300, via PHY section402. Node B300, which has received the “RRC Connection Setup Complete” at PHY section305, transmits the “RRC Connection Setup Complete” via MAC processing section304, RRC section303, CRNCF section302and control section301, to RNC-c200, over the public network (step ST606).

Next, UE400transmits a “PDP context activation request” to Node B300, to set up a bearer for receiving MBMS data. Node B300transmits the received “PDP context activation request” to RNC-c200. RNC-c200transmits the received “PDP context activation request” from SRNCF section201, to CN13(step ST607).

Next, RNC-c200receives a “RAB assignment request” to set up a bearer, from CN13(step ST608).

Then, RNC-c200transmits a “RAB setup”, which is a notice regarding MBMS data duplication, from RNC-u control section203to RNC-u100, to set up a bearer between CN13and RNC-u100(step ST609). Thus, RNC-u100can recognize that RNC-u100itself is to duplicate MBMS data.

Next, RNC-c200transmits a “radio link reconfiguration prepare” from Node B control section202to Node B300, to set up a bearer between RNC-u100and Node B300, and set up a radio link between Node B300and UE400(step ST611).

Then, Node B300performs the bearer setup between RNC-u100and Node B300and the radio link setup between Node B300and UE400, and transmits a “radio link reconfiguration ready” from control section301to RNC-c200(step ST612).

Next, RNC-c200transmits a “radio link reconfiguration commit” from Node B control section202to Node B300, to enact the bearer setup between RNC-u100and Node B300and enact radio link setup between Node B300and UE400(step ST613).

Then, RNC-c200transmits a “radio bearer setup” from Node B control section202to Node B300, to set up a radio link between Node B300and UE400, and Node B300transmits the received “radio bearer setup” from RRC section303to UE400(step ST614).

Next, UE400performs the radio link setup between Node B300and UE400to transmit a “radio bearer setup complete” from RRC section401, and Node B300transmits the received “radio bearer setup complete” to RNC-u100, via PHY section305and MAC processing section304. Further, RNC-u100transmits the radio bearer setup complete to RNC-c200, via MAC-d section104, RLC section103and control section101(step ST615).

Then, in RNC-u100, PDCP section102receives MBMS data from CN13, RLC section103duplicates the MBMS data, and MAC-d section104transmits the duplicated MBMS data to Node B300. Then, Node B300, which has received the MBMS data at MAC processing section304, transmits the MBMS data to UE400, via PHY section305(step ST617). In comparison to the conventional method, the present method introduces: a selection of selecting RNC-c200, carried out by Node B300, between step ST601and step ST602; a selection step of selecting RNC-u100, carried out by RNC-C200, between step ST604and step ST605; the “RAB setup step” of step ST609; and the “RAB setup complete” step of step ST610.

For example, it is possible to use RNC-u100as a company server and place Nodes B300in different rooms in the company, and establish connection between RNC-c100and Nodes B300by a local network such as company LAN.

Thus, according to embodiment 1, by dividing the functions of the RNC into RNC-u100and RNC-c200, providing RNC-c200in an upper position than the public network, and providing RNC-u100in a lower position than the public network, RNC-u100is able to duplicate MBMS data and transmit duplicated MBMS data to Node B300by a local network, so that it is possible to prevent traffic increase in the public network and prevent increase in communication cost of the public network. Also, according to embodiment 1, part of the functions of the RNC is implemented in Node B300and Node B300selects RNC-c200, and the RNC-c200selected by Node B300selects RNC-u100, so that, as a result, Node B200can select RNC-u100having a small amount of processing or RNC-u100with a small delay amount, which can reduce the concentration of MBMS data duplication processes in a particular RNC-u100.

FIG. 8is a sequence diagram showing the operation of RNC-u100, RNC-c200, Node B300and UE400. The circle symbols ofFIG. 8show that the messages pass through the nodes. In embodiment 2, since the configuration of RNC-u100is the same as that shown inFIG. 2, the configuration of RNC-c200is the same as that shown inFIG. 3, the configuration of Node B300is the same as that shown inFIG. 4, and the configuration of UE400is the same as that shown inFIG. 5, description thereof is hereby omitted. Also, parts inFIG. 8, having the same operation as those shown inFIG. 7are assigned the same reference numeral, and further description thereof is hereby omitted.

RNC-c200, which has received a “RRC connection request” at Node B control section202, transmits a “radio link setup request” from Node B control section202to Node B300, via a public network, to set up a radio link for RRC connection (step ST603).

Then, Node B300reports the selected RNC-u100to RNC200by transmitting information about the selected RNC-u100from control section301to RNC-c200(step ST701).

Next, in RNC-c200, which has received a “radio link setup response” at Node B control section202, SRNCF section201selects RNC-u100for U-plane processing. In this case, the RNC-u100selected by RNC-c200is the RNC-u100selected by Node B300and reported to RNC-c200. Next, RNC-c200transmits a “RRC connection setup” from RRC section206to Node B300, via SRNCF section201and Node B control section202, to set up a radio link for RRC connection. Further, Node B300, which has received the “RRC connection setup” at control section301, transmits the “RRC connection setup” from RRC section303to UE400, via CRNCF section302(step ST605).

Also, RNC-c200receives the “RAB assignment request” from CN13, to set up a bearer (step ST608).

Next, RNC-c200transmits an “RAB Setup”, which is a notice regarding duplication of MBMS data from RNC-u control section203to the RNC-u100reported from Node B300in step ST701, to set up a bearer between CN13and RNC-u100(step ST702) Thus, RNC-u100can recognize that RNC-u100itself is to duplicate MBMS data.

Next, RNC-u100performs the bearer setup between CN13and RNC-u100, and transmits a “RAB setup complete”, to RNC-c200(step ST610).

Then, the function distribution and the communication steps will be next described usingFIG. 6. As shown inFIG. 6, MBMS data can be duplicated at RNC-u100, and load can be shared between RNC-c200and between RNC-u100. Specifically, the C-plane functions of the RNC are divided into SRNCF section201having a mobile terminal control function of performing control of the mobile terminal apparatus such as handover or the like, and CRNCF section302having a radio cell control function for performing radio cell setup for the terminal apparatus, release of the terminal apparatus from the radio cell and radio resource control, SRNCF section201is provided at RNC-c200, and CRNCF section is provided at Node B300. Also, the U-plane functions of the RNC are divided into PDCP section102and RLC section103having mobile terminal user functions for performing packet retransmission control for the terminal apparatus and access control for the dedicated radio channel occupied by the terminal apparatus, and MAC processing section304having radio cell user functions for performing access control for a common radio channel (for instance, FACH and HS-SDCH of HSDPA) shared by a plurality of terminal apparatuses, PDCP section102and RLC section103are provided in RNC-u100, and MAC processing section304is provided at Node B300. According to the radio cell user function, packet data to be sent to a plurality of terminal apparatuses through a common radio channel shared by a plurality of terminal apparatuses, is multiplexed in downlink, and packet data to be sent to each terminal apparatus is separated from the RACH which transmits packet data from the plurality of terminal apparatuses, in uplink.

Then, in addition to these function allocations, a step in which Node B300selects RNC-c200and Node B300selects RNC-u100, is adopted. Also, it is possible to duplicate and distribute MBMS data at RNC-u100and disperse load between RNC-c200and between RNC-u100. The MBMS data transmitted from CN13is received by RNC-u100, via public network502. Also, the MBMS data duplicated and transmitted by RNC-u100is received at Node B300, via local network506between RNC-u100and each Node B300.

Thus, according to embodiment 2, by dividing the RNC functions into RNC-u100and RNC-c200, with RNC-c200being provided at a higher position than the public network and RNC-u100being provided at a lower position than the public network, and reallocating functions to apparatuses, RNC-u100is able to duplicate MBMS data and transmit duplicated MBMS data to Node B300via the local network, so that it is possible to prevent traffic increase in the public network and increase in communication cost in the public network. Also, according to embodiment 2, part of the RNC functions is implemented in Node B300and Node B300selects RNC-u100, so that Node B300is able to select the RNC-u100with a small amount of processing or the RNC-u100with a small delay amount, and it is possible to reduce the concentration of MBMA data duplication processes in a particular RNC-u100. Also, according to embodiment 2, when damage to RNC-c200occurs and it becomes necessary to shift the processes to a different RNC-c200, it is sufficient that Node B selects a new RNC-c200, without the need that the newly selected RNC-c200further reselects a new RNC-u100, which makes it is possible to reduce the switching time to a new RNC-c200.

The present application is based on Japanese Patent Application No. 2005-000607, filed on Jan. 5, 2005, the entire content of which is expressly incorporated by reference herein.

INDUSTRIAL APPLICABILITY

The communication apparatus, communication system and communication method of the present invention are useful in providing multicast packet communication services.