GB2471861A

GB2471861A - Data and control information routing in wireless communication network

Info

Publication number: GB2471861A
Application number: GB0912249A
Authority: GB
Inventors: Zhaojun Li
Original assignee: Fujitsu Ltd
Current assignee: Fujitsu Ltd
Priority date: 2009-07-14
Filing date: 2009-07-14
Publication date: 2011-01-19
Anticipated expiration: 2029-07-14
Also published as: GB2471861B; GB0912249D0

Abstract

A wireless communication system comprising a core network and a radio access network, the radio access network including at least one access node, preferably a base station for a femtocell, such as a home NodeB in UMTS or a home eNodeB in a LTE system, for wireless communication of data and control information with user equipment (UE), the control information route from the access node to the core network being entirely within the wireless communication system and which may be relayed through a macrocell access node or a controller such as an RNC in UMTS; and the data route from the access node to the core network being via a separate communication system which may be a public network such as the internet.

Description

INTELLECTUAL

. .... PROPERTY OFFICE Application No. GB09 12249.0 RTM Date:16 October 2009 The following terms are registered trademarks and should be read as such wherever they occur in this document:

UMTS 3GPP

Intellectual Property Office is an operating name of the Patent Office www.ipo.gov.uk Data and Control Information Routing in Wireless Communication Systems The present invention relates to wireless communication systems, more particularly but not exclusively to wireless communication system adopting the use of a small geographical coverage area basestation. Such basestations provide smaller cells amongst the standard cells in the system, which we will refer to as "macro cells" served by macro basestations. The smaller cells are commonly referred to as micro-, pico-or femtocells. In a IJMTS system, these can be Home NodeBs (HNBs) and in the long-term evolution (LTE) of UMTS they are known as Home eNodeBs (HeNBs).

UMTS (or 3G) wireless communication systems are being deployed worldwide. The current UMTS system supports both circuit-switched and packet-switched communication. One view of the connection of macrocells to the core network in such a system is shown in Figure 1. The UMTS radio access network (UTRAN) is shown to the left of the Figure and it is this radio access network which connects users (or more precisely user equipments, UEs) to the network using access nodes which are effectively basestations, referred to in Figure 1 as 3G NodeB. One or more of these basestations are linked to a controller known as the radio network controller (RNC) which controls the NodeBs connected to it, carries out radio resource management and some validity management and acts as an encryption point. The RNC connects to the core network via different interfaces, depending on the communication type. The connection to the circuit-switched core network and the packet-switched core network are shown separately in the Figure. Connections to the broadcast (BC) domain are also separate.

Future development of UMTS systems is centred on the so-called evolved UMTS terrestrial radio access network (evolved UTRAN or eUTRAN), more commonly referred to by the project name LTE.

In LTE, the architecture of the wireless communication system evolves from one supporting both circuit-switched and packet-switched communications, to an all-IP, packet-switched system. The overall architecture of the eUTRAN and its core network becomes simplified, and they combine to form the so-called Evolved Packet System (EPS), also called System Architecture Evolution (SAE).

As in current UMTS systems, the basic architecture proposed for LTE consists of a radio access network (the eUTRAN) connecting users (or more precisely, user equipments, UEs) to access nodes acting as base stations, these access nodes in turn being linked to a core network. In eUTRAN terminology the access node is called an eNode B or eNB and is the sole type of node in the eUTRAN as such, thus simplifying the architecture and reducing the number of hops in comparison with earlier wireless communication systems. A separate radio network controller (RNC) as used in previously-proposed systems is no longer required, its functions being incorporated into the eNodeB. The eNBs connect to the core network which, in LTE, is referred to as the evolved packet core (EPC).

Each eNB is in communication with one or more UEs and is also connected to entities of the core network (EPC) via an interface referred to as Si. Such entities include a mobility management entity (MME) and a serving gateway (S-GW).

Any wireless communication system involves both communication links for user data and communication links for control information (sometimes alternatively known as control signalling or control data). These aspects of the system are often referred to as the "user plane" and "control plane". In LTE the user plane and control plane are logically distinct, but their routing is always through the mobile operator's network for macrocells. The E-UTRAN comprises the eNBs which provide the E-UTRA user plane and control plane terminations towards the UEs.

Figure 2 shows a typical HeNB deployment scenario in LTE. The E-UTRAN provides relatively wide-area cells each served by an eNodeB and connected to the EPC via the S-GW and MME. In contrast, the Home eNodeB connects to the EPC via an lP access network such as the internet using an IP gateway as part of the customer's broadband.

The Home eNodeB is shown separately from the E-UTRAN but could be geographically speaking within the E-UTRAN or to the edge of it, to enhance coverage or fill coverage holes.

A similar arrangement applies for the Home NodeB and UTRAN in 3G, with the user plane and control plane both routed through the internet to the mobile operator's core network. However, the Home NodeB links to the mobile operator's network via a gateway known as a 3G i-IN B GW.

The Home NodeB or eNodeB corresponds to the so-called femtocell of some other proposa's. One basic idea of the home NodeB or eNodeB or femtocell is to enable fixed-mobile covergence, in which a single handset (UE) is capable of communicating with a NodeB/eNodeB covering a macrocell whilst the user is out and about, and thus of switching to an HNB/eNB once the user is within range of a home or office cell without needing to duplicate hardware resources needed for systems of different types.

HNBs and HeNBs are also considered a promising solution to solve many other issues in mobile communication networks, such as coverage, capacity and cost. They can deliver an improved user experience for services in the home or work location, at a very low cost. As shown in Figure 2, they can use the customers broadband (such as DSL or cable) for backhaul, that is connections to the core network are routed via the internet. In both LTE and 3G the connection between the internet and the EPC shown in Figure 2 is usually via a security Gateway. Although the internet connection gateway is shown in the Figure separately from the serving gateway S-GW, it is possible for a single hardware unit to provide both functions.

The low cost connection of the femtocell (or other cell with such a connection) is advantageous but can, in some circumstances bring uncertain delay into the access architecture and thus potentially unreliability.

It is therefore desirable to increase the reliability of the architecture. According to one aspect of the invention there is provided a wireless communication system comprising a core network and a radio access network, the radio access network including at least one access node for wireless communication of data and control information with user equipment (UE), the control information route from the access node to the core network being entirely within the wireless communication system; and the data route from the access node to the core network being via a separate communication system.

The access node (often a serving base station of a femtocell, such as a Home NodeB or eNodeB) routes the control plane (that is the control information path) only within the wireless communication system itself. This gives more reliable control plane signalling delivery completely over the wireless communication system and thus entirely within the control of the operator of that system. Security and reliability of the control signalling are one of the operators' main concerns regarding femtocells deployment.

Thus embodiments of the invention provide a secure and reliable solution for control plane delivery. This is a particular'y useful femtocell enterprise deployment scenario, because reliability is crucial for business customers.

At the same time, embodiments of the invention allow the user plane to be delivered flexibly and at low cost via a different communication system, for example a public network such as the internet.

In many circumstances, the access node is a basestation having a smaller geographical coverage area than at least one other access node of the wireless communication system. Thus, as outlined above for example, the access node may be an HNB or HeNB of a system in which macrocells are also present. Using more general terminology, the access node may be the basestation of a micro-, pico-or femtocell in a cellular system. The radio access network may comprise further entities, for example, a controller provided between the access node and the core network. In this case the control information (control plane) can be routed from the access node to the core network via the controller. The link between the controller and the core network may be a fixed (or wired) link.

Advantageously, the controller is a radio network controller (RNC) of a UMTS system.

This entity is previously available in macrocells of many 3G systems which are already deployed and therefore embodiments of the invention allow an operator to use the existing RNC to provide the route for the access node's control plane. Thus the control plane routing can be essentially identical to the control plane routing for macrocell NodeBs.

In previous 3G systems, the data and control information were to be routed together from the HNB access node to a 3G HNB gateway and then, for example, via the internet. However, in some invention embodiments, the access node can be directly responsible for the user plane functionality, with an RNC now mainly responsible for the control plane functionalities. In these circumstances, the data may be routed directly from the access node to the separate communication system, without passing via another entity. Here, the RNC is preferably operable to transmit information to the access node to allow the access node to perform this data transmission functionality.

Effectively, this information may relate to the user plane at the interface between the core network and the radio access network.

In some other invention embodiments, no separate controller is required, so only access nodes are provided in the RAN. This is true, for example of an implementation in LIE systems. In these and some other circumstances, the links between the access node and core network may be slightly different. In one preferred embodiment, the wireless communication system also comprises at least one macro access node (having a larger geographical coverage area than the access node). Here the control information/control plane is preferably routed via the macro access node. This macro access node thus acts as a relay. The link between the access node and the macro access node may be wireless or wired, but is more preferably wireless and may be for example a microwave link.

In any of the invention embodiments, the data/user plane can be routed via a fixed line to the different communication system. As set out previously, the different communication system can be a public network such as an IP access network, for example the internet and the link can be a specific connection belonging to an operator of the access node. For example, the access node may be operated by a home or business owner and the specific connection may be the business or home owner's broadband internet access.

Preferably, the access node and the core network are operable to set up a tunnel via the separate communication system for transmission of the data. For example, the tunnel may be a security enhanced tunnel, such as a secure IPSec tunnel.

Another aspect of the invention relates to an access node in a wireless communication system. Accordingly, embodiments of the invention provide an access node in a wireless communication system comprising the access node, a core network and at least one user equipment, the access node including: transmission/reception means for wireless communication means of data and control information with the user equipment; control information interface means operable to allow communication of control signalling between the access node and the core network via the wireless communication system only; and data interface means operable to allow communication of data between the access node and the core network via a separate communication system.

The external connections of the access node will be provided specifically for the separate routing of the control plane (control signalling) and user plane (data) and can thus be arranged separately and each suited to the specific requirements of the routing. For example, and as explained in more detail above, the control information interface may be a connection from the access node to the RNC in a 3G network or a microwave connection to a relay eNodeB in a LTE network.

The invention also extends to method aspects in the wireless communication system and in the access node. Features of any of the aspects can be combined.

Thus in some preferred embodiments of the invention there is provided a method of communication in a wireless communication system comprising a core network and a radio access network, the method comprising transmitting data and control information between user equipment and the radio access network and transmitting the control information from the radio access network to the core network within the wireless communication system but transmitting the data from the radio access network to the core network via a different communication system.

In a further preferred embodiment there is provided a method of communication in an access node of a wireless communication system comprising the access node, a core network and at least one user equipment, wherein the access node communicates data and control information wirelessly with the user equipment, routing the data towards the core network along a path via a separate communication system and routing the control information towards the core network along a path entirely within the wireless communication system.

A further aspect of the invention provides a computer program which when executed by a processor of an access node in a wireless communication system carries out a method in an access node. In an alternative definition, the computer program (or computer software) may be downloaded to an entity in a wireless communication system to allow it to function as the access node defined above.

Preferred features of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram showing one view of architecture of a UMTS network; Figure 2 is a schematic diagram of a typical related art eHNB deployment; Figure 3 is a schematic diagram of a general embodiment of the invention; Figure 4 is a 3G embodiment of the present invention in schematic form; Figure 5 shows a protocol stack for CS domain architecture in 3G; Figure 6 shows a protocol stack for PS domain user plane architecture in 3G; Figure 7 shows a schematic diagram of an LTE embodiment of the invention; Figure 8 shows protocol stacks for user plane in LTE; and Figure 9 shows protocol stacks for the control plane in LTE.

Figure 3 is an illustration of the general embodiment of the invention. User equipment (UE) such as a handset, PDA or other mobile device is shown as telephone 10 within femtocell 30. The access node 20 provides coverage within the cell 30. Control and data is routed together from the UE to the access node and then the routing divides with data being routed via a different system, for example a system managed by a different operator or a publicly available system such as the internet to the core network. In contrast, the control information is routed directly to the core network without passing through any other system. This arrangement allows a low cost use of a different system such as the internet for data along with the reliability of a direct connection to the core network for control information.

Specific embodiments of the present invention propose a User Plane (UP) and Control Plane (CP) separation framework for 3G Home NodeB and LTE Home eNodeB.

HNB Architecture with UP and CP Separation Fig. 4 illustrates 3G HNB functional architecture. The Home NodeB is shown with the lu interface (lu-CS, lu-PS) to the core network for the user plane. For control information transmission purposes it is connected to the RNC using the lub interface. One key consideration for the architecture of these embodiments is the functional split of the RNC role between the HNB and the RNC. Here, the RNC provides the Control Plane functionalities for the connected HNB while the HNB is responsible for the User Plane functionalities.

The core network is shown in part only; that is the relevant circuit switched (CS) and packed switched (PS) regions are indicated with their connection to the IMS (The IP Multimedia Subsystem, which is an architectural framework for delivering IP multimedia services).

Some of the main features of this 3G HNB architecture embodiment are firstly that the HNB connects to the RNC via an lub-based interface (see Universal Mobile Telecommunications System (UMTS); UTRAN lub Interface: general aspects and principles (3GPP TS 25.430 version 7.5.0 Release 7) which is incorporated herein by reference). The RNC provides Control Plane functionalities via the standardized interfaces defined in 3GPP, while the HNB provides the User Plane radio access network connectivity to the UE. The RNC therefore needs to forward the lu User Plane information to the HNB, so that the HNB can provide User Plane functionalities, for example setting up a GTP (GPRS Tunnelling Protocol) tunnel with the prior GGSN (Gateway GPRS Support Node) of 3G for PS user plane services. The GGSN is not shown here, for reasons of simplicity.

Secondly, the HNB is customer premises equipment (CPE) which offers a standard radio interface Uu for UE connectivity (not shown). Standard 3G User Equipments (or other UEs) are supported.

Thirdly, for security reason, a secure IPSec tunnel may be set-up between the HNB and the Core Network for mutual authentication, encryption and data integrity.

The diagram shows which parts essentially exist already in a UMTS system and which parts are new or modified. The RNC, transit of the internet, CS-CN, PS-CN and IMS are essentially existing elements. Previously, the RNC was known in another context (an HNB gateway acted as the main attach point for Home NodeBs to connect to the core network). The invention uses functionality of the existing RNC to provide the route for the HNB's control plane.

Thus the new elements in Figure 4 include the function of an lu user plane in an HNB and the modified lub interface between the RNC and HNB, The RNC may also be slightly modified, for example the lub interface used towards the HNB in this architecture only requires control plane functionality.

The connection from the HNB to the internet is typically via user broadband, and the connection between the RNC and the core network is typically also a fixed link, rather than a wireless link. This connection is already essentially known from the arrangement of macrocell RNCs within 3G networks and the HNB connects to the RNC as a normal NodeB through the lub interface for control plane functions.

Fig. 5 shows the User Plane protocol architecture for lu-CS, where RTP/UDP/lP is used as the user data bearer towards the CS domain in the IP transport option (see Universal Mobile Telecommunications System (UMTS); UTRAN lu interface: General aspects and principles (3GPP TS 25.410 version 7.0.0 Release 7) which is incorporated herein by reference). Fig. 6 shows the User Plane protocol stacks for lu-PS, where the optional function Direct Tunnel (see Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); General Packet Radio Service (GPRS); Service description; Stage 2 (3GPP TS 23.060 version 8.1.0 Release 8) which is incorporated herein by reference) is used that allows the SGSN (serving GPRS Support Node) to establish a direct user plane tunnel between RAN and GGSN within the PS domain.

LTE HeNB Architecture with UP and CP Separation Fig. 7 illustrates LTE HeNB functional architecture with the same division between new and existing parts. Thus the eNodeB, MME and S-GW, as well as the transit of the IP access network are all known. The HeNB however has new functionality and the control plane routing is new. One key consideration for the proposed architecture of LTE embodiments is the route split of HeNB's Control Plane and User Plane. In this embodiment, it is proposed that the HeNB provides the Si Control Plane functionalities via the relayed eNodeB (e.g. by microwave frequencies) and sets up the Si User Plane interface towards S-GW through the public network (e.g. the Internet).

Fig. 8 shows the User Plane protocol architecture for the user plane interface from the HeNB access node to the serving gateway, known as Si-U. A GTP-U tunnel is set up between the HeNB and Serving Gateway (S-GW) (see Universal Mobile Telecommunications System (UMTS); General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access (3GPP TS 23.401 version 8.2.0 Release 8) which is incorporated herein by reference). For security reasons, a secure IPSec tunnel may be set-up between the HeNB and the Core Network for mutual authentication, encryption and data integrity.

Fig. 9 shows the Control Plane protocol architecture for the control plane interface between the HeNB access node and the MME, known as the S1-MME, where a macro eNodeB relays all the signalling messages between the HeNB and an MME. Methods by which the HeNB links to a relaying macro eNodeB will be known to a person skilled in the art and are outside the scope of this invention.

Benefits of the Invention To summarise, embodiments of the invention provide a User Plane and Control Plane separation framework particularly suitable for 3G Home NodeB and LTE Home eNodeB. The architecture provides many benefits for supporting uncoordinated HNB/HeNB integration to the mobile network through unmanaged, generic IP networks.

Reliable control plane signalling delivery can be achieved via Macro eNB relay in LTE.

This is particularly important for femtocell enterprise deployment scenario, where reliability is crucial for business customers. Flexible user plane data delivery can be realised at the same time via public network (e.g. Internet) at very low cost. Using public transportation for user plane data delivery supports various application services at home, on campus or in the office, all at very low cost. It also has a good potential to create a totally new set of services in a "connected home", "connected classroom" or "connected office" environment.

The framework does not introduce any new network entities into an operator's system, which minimises the effect on the existing standards. This is important in order to protect the operators' investment.

Although described in reference to a 3GPP or 3GPP LTE system, the present invention is not limited to such use and can be applied to any wireless communication system in which the access nodes can be connected to the core network via a separate communication system.

In any of the above aspects, the various features may be implemented in hardware, or as software modules running on one or more processors. Features of one aspect may be applied to any of the other aspects.

The invention also provides a computer program or a computer program product for carrying out any of the methods described herein, and a computer readable medium having stored thereon a program for carrying out any of the methods described herein.

A computer program embodying the invention may be stored on a computer-readable medium, or it could, for example, be in the form of a signal such as a downloadable data signal provided from an Internet website, or it could be in any other form.

Claims

CLAIMS1. A wireless communication system comprising a core network and a radio access network, the radio access network including at least one access node for wireless communication of data and control information with user equipment (UE), the control information route from the access node to the core network being entirely within the wireless communication system; and the data route from the access node to the core network being via a separate communication system.
2. The wireless communication system according to claim 1, wherein the wireless communication system is a cellular system and the access node is the base station of a femtocell.
3. The wireless communication system according to claim 1 or 2, wherein the access node is a Home NodeB in a UMTS system or a Home eNodeB in a UMTS LTE system.
4. A wireless communication according to any of the preceding claims, wherein the radio access network also comprises a controller between the access node and the core network, the control information route being provided from the access node to the core network via the controller.
5. A wireless communication system according to claim 4 wherein the link between the controller and the core network is a fixed link.
6. The wireless communication system according to claim 4 or 5, wherein the controller is a radio network controller of a UMTS system.
7. A wireless communication system according to any of claims 4 to 6, wherein the data is routed directly from the access node to the separate communication system; and wherein the controller is operable to transmit information for transmission of the data to the access node, to allow the access node to provide data transmission functionality.
8. The wireless communication system according to any of claims 1 to 3, wherein the access node is the sole type of entity in the radio access network; wherein the wireless communication system also comprises a macro access node which has a larger geographical coverage area than the access node and preferably wherein the control information route is via the macro access node, which acts as a relay.
9. A wireless communication system according to claim 8 wherein a link between the access node and macro access node for transmission of the control information is wireless, for example a microwave link.
10. A wireless communication system according to any of the preceding claims, wherein the data is routed via a fixed line to the separate communication system.
11. A wireless communication system according to any of the preceding claims, wherein the separate communication system is,a public network such as the internet and preferably wherein the link to the public network is via a connection specific to an operator of the access node.
12. A wireless communication system according to any of the preceding claims, wherein the access node and the core network are operable to set up a tunnel via the separate communication system for transmission of the data.
13. An access node in a wireless communication system comprising the access node, a core network and at least one user equipment, the access node including: transmission/reception means for wireless communication means of data and control information with the user equipment; control information interface means operable to allow communication of control signalling between the access node and the core network via the wireless communication system only; and data interface means operable to allow communication of data between the access node and the core network via a separate communication system.
14. A method of wireless communication in an access node of a wireless communication system comprising the access node, a core network and at least one user equipment, wherein the access node communicates data and control information wirelessly with the user equipment, routing the data towards the core network along a path via a separate communications system and routing the control information towards the core network along a path entirely within the wireless communication system.
15. A computer program which when executed by a processor of an access node in a wireless communication system carries out the method of claim 14.