GB2412548A

GB2412548A - Resouce sharing between several User Plane Servers in a radio network controller

Info

Publication number: GB2412548A
Application number: GB0504447A
Authority: GB
Inventors: Masahiko Kojima
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 2004-03-03
Filing date: 2005-03-03
Publication date: 2005-09-28
Anticipated expiration: 2025-03-03
Also published as: GB2412548B; JP2005252502A; JP4089642B2; GB0504447D0

Abstract

A mobile communication system with great scalability makes effective use of resources within the RCS and UPS in a configuration in which a radio network controller (RNC) is separated into a control plane controlling part (RCS) 13 and a user plane controlling part (UPS) 14. It is possible to make effective use of resources by sharing the MAC-d/RLC resources among plural UPSs in accordance with the load situation, whereby even if the resource of a specific UPS is deficient, the resources of other UPSs can be substituted, with the effect that the system is more flexible. Also, there is the effect that it is possible to make effective use of the resource of mobility and RAB control part within the RCS by sharing it in accordance with the load situation.

Description

- 1 - 2412548 MOBILE COMMUNICATION SYSTEM, RESOURCE CONTROL METHOD

THEREOF AND RADIO NETWORK CONTROLLER

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a mobile communication system, resource control method thereof and a radio network controller, and more particularly to effective utilization of resources in a mobile communication system of a W-CDMA (Wideband Code Multiple Access) method.

Description of the Prior Art

FIG. 8 is a functional block diagram of a W-CDMA communication system in a mobile communication system.

Under management of a core network (CN) 1 that is a switching network, the radio network controllers (RNC: Radio Network Control) 2, 3 are provided. An RNC 2 is connected to two Nodes B 4, 5, and an RNC 3 is connected to two Nodes B 6, 7. Each Node B 4 to Node B 7 is a logical node for making the radio transmission/reception, and is specifically a radio base station. Nodes B 4 to 7 cover the cell 8 to 11 respectively, and are connected via a radio interface to the mobile equipment (UK) 12.

The RNC 2 has a functional part 21 called "Mobility RAB Control & MACd/RLC" and a functional part 22 called "Cell Control & MAC-c." The former functional part 21 has - 2 a mobile and radio bearer control function, and two sub- layer functions of MAC-d (Media Access Control-dedicated) and RLC (Radio Link Control) making up a data link layer.

The latter functional part 22 has a cell control function and a MAC-c (Media Access Control-common) function making up a sub-layer of the data link layer, in which these functions are associated with the cells 8, 9. The RNC 3 is similarly configured.

The above configuration is defined by the 3GPP (Third Generation Partnership Project), and as an extended configuration of this system, "Evolution of UTRAN Architecture" is also defined by the 3GPP (refer to 3GPP TR25.897 V0.3.0 (2003-08)). The UTRAN is short for "Universal Mobile Telecommunication System (UMTS) Terrestrial Radio Access Network." FIG. 9 is a functional block diagram of this architecture. The same or like parts are designated by the same reference numerals in FIGS. 8 and 9.

In this architecture, taking notice of a user plane for controlling the transfer of user data and a control plane for controlling the transfer of signaling, the functions of the RNC 2, 3 as shown in FIG. 8 are separated into an RCS (Radio Control Server) 13 for controlling the control plane and a UPS (User Plane Server) 14, 15 for controlling the user plane.

In this example, under the management of the core network 1, one RCS 13 is disposed and a plurality of UPSs (for simplification, two UPSs 14, 15 are shown in the figure) are provided. The RCS 13 comprises a cell control part 132 and a mobility & RAB (radio access bearer) control part 131. The UPS 14 comprises a MAC-c part 142 closely contacted with the cell, and a MAC-d/RLC part 141, and the UPS 15 comprises a MAC-c part 152 and a MAC-d/RLC part 151.

The MAC-c part and MAC-d/RLC part make up a sub-layer of the data link layer in the protocol architecture of RNC, like the architecture of FIG. 8.

The MAC-c part 142, 152 closely contacted with the cell in the UPS 14, 15 has one-to-one relation with the cell at Node B. in which the UPS 14 corresponds to Node B 4 (cell 8) and Node B 5 (cell 9), and the UPS 15 corresponds to Node B 6 (cell 10) and Node B 7 (cell 11). Also, a cell control part 132 within the RCS 13 exists for every cell (for simplification, only two cell control parts are shown in FIG. 9). In FIG. 9, Iu-b is an interface between Node B and UPS, Iu-i is an interface between UPS and RCS, Iu-c is an interface between RCS and core network, and Iu-u is an interface between UPS and core network.

In the architecture as shown in FIG. 9, the RNC of FIG. 8 is separated into the RCS for controlling the control plane, and the UPS for controlling the user plane, in which a plurality of UPSs are provided in accordance with the amount of user data to flexibly treat the amount of user data. However, when the use amount of MAC-d/RLC resources within a certain UPS increases, the resources within another UPS are not substituted, even though the use amount of MAC-d/RLC resources within another UPS is small. - 4

Despite a system configuration provided with the plurality of UPSs, it is less liable to flexibly treat the amount of user data, because the resources are not distributed among the UPSs even if a specific UPS has a larger or smaller amount of resources. Therefore, it is desired to make effective use of resources within the UPS.

Moreover, the RCS 13 is similarly configured. That is, though a plurality of mobility & RAB control parts 131 are provided within the RCS, it is not considered that even if a certain mobility & RAB control part is in an overload state, the load is distributed among other mobility & RAB control parts. Accordingly, it is desired to make effective use of resources within the RCS.

SUMMARY OF THE INVENTION

The present invention provides a mobile communication system comprising a radio network controller provided between a radio base station and a switching network, the radio network controller being separated into control plane controlling means and user plane controlling means, the system comprising resource selection controlling means for selectively controlling the user plane controlling means in accordance with a resource use situation of the plural user plane controlling means.

The invention provides a radio network controller provided between a radio base station and a switching network, the radio network controller having control plane controlling means and user plane controlling means, the - 5 - controller comprising resource selection controlling means for selectively controlling the plural resources in accordance with each use situation of the resources in the control plane controlling means.

The invention provides a resource control method for use in a mobile communication system comprising a radio network controller provided between a radio base station and a switching network, the radio network controller being separated into control plane controlling means and user plane controlling means, the method comprising a step of selectively controlling the user plane controlling means in accordance with the resource use situation of the plural user plane controlling means.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example, with reference to the drawings, in which: FIG. 1 is a system block diagram for explaining one operation state according to an embodiment of the present invention; FIG. 2 is a system block diagram for explaining another operation state according to the embodiment of the invention; FIG. 3 is a diagram showing a procedure for measuring a UPS use rate of RCS according to the embodiment of the invention; - 6 FIG. 4 is a graph representing the report timing of each UPS use rate according to the embodiment of the invention; FIG. 5 is a table for explaining the UPS selection examples for load balancing (load distribution) of RCS according to the embodiment of the invention; FIG. 6 is an operation sequence diagram according to the embodiment of the invention; FIG. 7 is an operation sequence diagram according to another embodiment of the invention; FIG. 8 is a diagram showing a configuration of a known W-CDMA mobile communication system) and FIG. 9 is a diagram showing another configuration of the W-CDMA mobile communication system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a system configuration diagram for explaining an embodiment of the present invention. The same or like parts as in FIG. 9 are designated by the same reference numerals throughout the drawings. In this embodiment, the system configuration is the same as in FIG. 9, except for an additional function of selecting the UPS with lowest use rate in the RCS 13, based on the latest load situation (UPS use rate) reported from each UPS, when one of the plurality of UPSs is selected in transferring the user data from a core network 1. - 7

Since the MAC-d/RLC part 141, 151 in the UPS is not associated with the cell, it is possible to transfer the user data or signaling from Node B 5 (#2) via MAC-c 142 of UPS 14 (#1) to MAC-d/RLC 141 of UPS 14 (#1) or MACd/RLC 151 of UPS 15 (#2), for example.

FIG. 1 shows how to transfer the user data (U plane route 102) and signaling (C plane route 101) from Node B 5 (#2) via MAC-c 142 of UPS 14 (#1) to MAC-d/RLC 141 of UPS 14 (#1). Also, FIG. 2 shows how to transfer the user data (U plane route 104) and signaling (C plane route 103) from Node B 5 (#2) via MAC-c 142 of UPS 14 (#1) to MAC-d/RLC 151 of UPS 15 (#2).

Referring to FIG. 3, a UPS selection function in the RCS 13 will be described below. The RCS requests each UPS to measure the UPS use rate (load situation) (steps S1, S3). Each UPS returns an acknowledgement response to this request (steps S2, S4). Each UPS reports to the RCS at a timing where the use rate is changed upon this request.

For example, the use rate is provided with thresholds at an interval of 25%, as shown in FIG. 4. When the use rate is beyond or below the threshold, the UPS reports to the RCS (steps S5, S6). In the RCS, one of the plurality of UPSs is selected, based on the latest use rate from each UPS, but when there are more than one UPS with the lowest use rate, they are selected alternately, as shown in FIG. 5. Such a UPS selection logic is called a load balancing.

FIG. 6 is an operation sequence diagram when the RCS performs this load balancing. Now, suppose that a packet - 8 is transferred from the core network 1 to the UE 12 residing in the cell #2. First of all, an "RAB ASSIGNMENT REQUEST" (RAB setup request) conforming to the RANAP (Radio Access Network Application Part) protocol is sent from the core network 1 to the Mobility & RAB Control part 131 within the RCS 13 (step S11). This request contains the IP address and the GTP (GPRS Tunneling Protocol) SN (Sequence Number) of the SGSN (Serving GPRS Support Node) having a packet switching function on the core network 1. The GTP is a protocol for implementing a tunneling function for transferring the user packet, and the SN is the number of RLC message in this protocol.

The RCS 13 performs a selection process for the UPS with the load balancing upon receiving this request (step S12). At this time, it is assumed that the UPS #2 is selected (step S13). Then, the RCS generates an RAB setup request to the UPS #2 (step S14). This request contains the GTP SN of the SGSN.

Herein, the so-called binding is required between the UPS #2 selected by load balancing in the RCS 13 and the UPS #1 corresponding to the cell #2 where UE 12 resides.

Therefore, the MAC-d/RLC 151 of UPS #2 and the MAC-c 142 of UPS #1 are made conductive through a negotiation for the IP address and TEID (Tunnel End point Identifier) between UPS #2 and UPS #1 in conducting the user plane (see FIG. 2).

The details of TEID were disclosed in 3GPP TS25.413.

Thus, a Binding request from the UPS #2 to the UPS #1 is generated (step S15). This request contains the IP - 9 - address and TEID of the UPSP #2. The UPS #1 returns the Binding result to the UPS #2 upon receiving this request (step S16). This Binding result contains the IP address and TEID of the UPS #1. Thereby, the binding between UPSs is enabled.

Thereafter, the UPS #2 makes the RAB setup (step S17), and sends out an RAB setup response to the RCS 13 (step S18). This RAB response contains the IP address and GTP SN of the UPS #2. The RCS 13 returns an RAB ASSIGNMENT RESPONSE message conforming to the RANAP to the SGSN of the core network 1. This message contains the IP address and GTP SN of the UPS #2. Thus, the user data is transferred from the SGSN of the core network 1 via the MAC-d/RLC 151 of the UPS #2 and the MAC-c 142 of the UPS #1 to the UE 12.

The signaling, which is required to be passed via the mobility & RAB control part 131 within the RCS 13, is transferred via both the MAC-d/RLC 151 of the UPS #2 and the mobility & RAB control part 131 of the RCS 13 to the core network 1.

Another embodiment of the invention will be described below. The system configuration in this embodiment is the same as in FIG. 9 (i.e., FIGS. 1 and 2), except that one of the plurality of mobility & RAB control parts 131 within the RCS 13 is selected to have the lowest use rate (load situation). This function of load balancing is made in the cell control part 132 within the RCS 13.

Since the mobility & RAB control part 131 within the RCS is not associated with the cell, it is possible to - 10 transfer the signaling from the mobility & RAB control part 131 to the UPS #1 or UPS #2 (see the C plane route 101 of FIG. 1 and the C plane route 103 of FIG. 2). Accordingly, one of the mobility & RAB control parts for use is decided in the cell control part 132 within the RCS in accordance with the load balancing procedure as described in FIGS. 3 to 5. An operation sequence at this time is shown in FIG. 7.

Referring to FIG. 7, the UE 12 of the mobile equipment firstly makes access via the MAC-c 142 of the UPS #1 upon an "RRC CONNECTION REQUEST" (radio connection request) conforming to the RRC (Radio Resource Control) protocol (steps S21, S22). The cell control part 132 within the RCS 13 selects one of the mobility & RAB control parts by load balancing (steps S23, S24). To this selected mobility & RAB control part (supposed #1), the cell control part 132 sends out a radio connection request (step S25). The mobility & RAB control part #1 sets up the radio connection with the UE 12 (steps S26 to S28).

According to the present invention, it is possible to make effective use of resources by sharing the MAC-d/RLC resources among plural UPSs in accordance with the load situation, whereby even if the resource of a specific UPS is deficient, the resources of other UPSs can be substituted, with the effect that the system is more flexible. In the system construction great scalability is allowed by making effective use of resources within the RCS and UPS in a configuration in which the radio network - 11 controller (RNC) is separated into the control plane controlling part (RCS) and the user plane controlling part (UPS). Also, there is the effect that it is possible to make effective use of the resources of the mobility & RAB control parts within the RCS. - 12

Claims

CL

1. A mobile communication system comprising a radio network controller provided between a radio base station and a switching network, said radio network controller being separated into control plane controlling means and user plane controlling means, said system comprising: resource selection controlling means for selectively controlling said user plane controlling means in accordance with a resource use situation of said plural user plane controlling means.

2. The mobile communication system according to claim 1, wherein said resource selection controlling means receives a report of said resource use situation of said plural user plane controlling means, and selectively controls said user plane controlling means in accordance with the latest resource use situation.

3. The mobile communication system according to claim 2, wherein said resource selection controlling means selectively controls said user plane controlling means so that the use situation of each resource in said plural user plane controlling means may be balanced. 13

4. The mobile communication system according to any one of claims 1 to 3, wherein said resource selection controlling means is provided in said control plane controlling means, and said resource is a data link layer functional part of said user plane controlling means.

5. A radio network controller provided between a radio base station and a switching network, said radio network controller having control plane controlling means and user plane controlling means, said controller comprising: resource selection controlling means for selectively controlling the plural resources in accordance with each use situation of said resources in said control plane controlling means.

6. The radio network controller according to claim 5, wherein said resource selection controlling means receives a report of each use situation of said plural resources, and selectively controls said resources in accordance with the latest resource use situation.

7. The radio network controller according to claim 6, wherein said resource selection controlling means selectively controls said resources so that the use situation of each of said plural resources may be balanced.

8. The radio network controller according to any one of claims 5 to 7, wherein said resource is the mobile equipment or a radio access bearer control functional part.

9. A resource control method for use in a mobile communication system comprising a radio network controller provided between a radio base station and a switching network, said radio network controller being separated into control plane controlling means and user plane controlling means, said method comprising: a step of selectively controlling said user plane controlling means in accordance with the resource use situation of said plural user plane controlling means.

10. The resource control method according to claim 9, wherein said step comprises receiving a report of the resource use situation of said plural user plane controlling means, and selectively controls said user plane controlling means in accordance with the latest resource use situation.

11. The resource control method according to claim 10, wherein said step comprises selectively controlling said user plane controlling means so that the use situation of each resource in said plural user plane controlling means may be balanced. -

12. The resource control method according to any one of claims 9 to 11, wherein said step is performed by said control plane controlling means, and said resource is a data link layer functional part of said user plane controlling means.

13. A resource control method for use in a radio network controller provided between a radio base station and a switching network, said radio network controller having control plane controlling means and user plane controlling means, said method comprising: a step of selectively controlling plural resources in accordance with each use situation of said resources in said control plane controlling means.

14. The resource control method according to claim 13, wherein said step comprises receiving a report of each use situation of said plural resources, and selectively controls said resources in accordance with the latest resource use situation.

15. The resource control method according to claim 14, wherein said step comprises selectively controlling said resources so that the use situation of each of said resources may be balanced. - 16

16. The resource control method according to any one of claims 13 to 15, wherein said resource is the mobile equipment or a radio access bearer control functional part.

17. A mobile communication system, or a radio network controller therefor, substantially as any of the embodiments herein described with reference to FIGS. 1 to 7 of the drawings.

18. A resource control method substantially as any of the embodiments herein described with reference to FIGS. 1 to 7 of the drawings.