CN110651517B

CN110651517B - System information receiving method and device

Info

Publication number: CN110651517B
Application number: CN201780090939.3A
Authority: CN
Inventors: 陈冬明; 何朗; 吴环宇; 陈雍珏
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2017-05-22
Filing date: 2017-05-22
Publication date: 2022-02-25
Anticipated expiration: 2037-05-22
Also published as: CN110651517A; WO2018213974A1

Abstract

A method and a device for receiving system information are used for solving the problems that when connected BL/CE UE needs to receive changed SIBs information in the prior art, E-UTRAN needs to release BL/CE UE, resource cost for releasing BL/CE UE is increased, and signaling cost and power consumption cost for re-accessing BL/CE UE to a network are also increased. The method comprises the following steps: a terminal receives Downlink Control Information (DCI) issued by a base station, wherein the terminal is in a connected state, and the DCI carries scheduling information of a changed system message; the terminal determines the resources occupied when the changed system message is issued according to the scheduling information of the changed system message; the terminal searches the changed system message sent by the base station on the resource.

Description

System information receiving method and device

Technical Field

The present application relates to the field of wireless communications technologies, and in particular, to a method and an apparatus for receiving system information.

Background

Machine to Machine (M2M) is a popular form Of application in the Internet Of Things (IOT). The third Generation Partnership Project (3 GPP) introduced Machine Type Communication (MTC) technology and Enhanced Machine Type communication (eMTC) technology, and in order to reduce The cost of The internet of things terminal, 3GPP R13 introduced Low cost User Equipment (UE), eMTC UE, which includes UEs and UEs of Coverage Enhancement (CE), i.e., BL/CE UE, of Bandwidth reduction (BL).

The 3GPP R13 protocol specifies that BL/CE UE can schedule only one transport Block per Transmission Time Interval (TTI), i.e. a broadcast transport Block and a data transport Block cannot be received simultaneously, and paging messages and System Information Block (SIBs) messages belong to the broadcast transport Block, so that connected-state BL/CE UE cannot receive the paging messages and SIBs messages. When the SIBs message changes and the connected BL/CE UE needs to receive the changed SIBs message, an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) needs to actively release the BL/CE UE, so that the BL/CE UE is in an idle state capable of receiving the paging message and the changed SIBs message.

In summary, when the connected BL/CE UE needs to receive the changed SIBs, the E-UTRAN needs to release the BL/CE UE, thereby increasing the resource overhead of releasing the BL/CE UE, and also increasing the signaling overhead and power consumption overhead of the BL/CE UE re-accessing the network.

Disclosure of Invention

The embodiment of the application provides a method and equipment for receiving system information, which are used for solving the problems that when connected BL/CE UE needs to receive changed SIBs information in the prior art, E-UTRAN needs to release BL/CE UE, resource overhead for releasing BL/CE UE is increased, and signaling overhead and power consumption overhead for re-accessing BL/CE UE to a network are also increased.

In a first aspect, the present application provides a method for receiving system information, including: a terminal receives Downlink Control Information (DCI) issued by a base station, wherein the terminal is in a connected state, and the DCI carries scheduling information of a changed system message; the terminal determines the resources occupied when the changed system message is issued according to the scheduling information of the changed system message; the terminal searches the changed system message sent by the base station on the resource.

In the embodiment of the application, the connected terminal determines the resources occupied by the changed system message when the changed system message is issued through the received DCI, after the base station issues the changed system message to the terminal, the terminal finds the changed system message on the resources, and in the process, the E-UTRAN does not need to release the UE, so that the UE is in an idle state. By the method, the resource overhead of releasing the UE is reduced, and the signaling overhead and the power consumption overhead of re-accessing the network by the UE are also reduced.

In one possible design, the DCI also carries a scrambling code; the method further comprises the following steps: and the terminal identifies that the DCI is the DCI carrying the scheduling information of the changed system message through the scrambling code.

In the embodiment of the application, the DCI is more quickly identified as the DCI carrying the scheduling information of the changed system message by identifying the scrambling code, and the type of the DCI is identified in advance.

In one possible design, the format of the DCI and the meaning of each bit in the DCI are pre-configured, and the bits of the DCI are at least 34 bits.

In one possible design, the Format of the DCI may also be a multiplexing of an existing Format6-1A Format.

In a second aspect, the present application provides a method for receiving system information, including: a base station sends Downlink Control Information (DCI) to a terminal, wherein the terminal is in a connected state, and the DCI carries scheduling information of a changed system message; the base station occupies resources required when the changed system message is issued on the terminal according to the scheduling information of the changed system message; and the base station sends the changed system information to the resources of the terminal.

In the embodiment of the application, the base station sends the DCI carrying the scheduling information of the changed system message to the connected terminal and occupies the resource occupied when the changed system message is issued, and after the base station issues the changed system message to the terminal, the terminal finds the changed system message on the resource, and in the process, the E-UTRAN does not need to release the UE, so that the UE is in an idle state. By the method, the resource overhead of releasing the UE is reduced, and the signaling overhead and the power consumption overhead of re-accessing the network by the UE are also reduced.

In one possible design, the DCI also carries a scrambling code; the method further comprises the following steps: and the base station informs the terminal of the DCI carrying the scheduling information of the changed system message through the scrambling code.

In a third aspect, the present application provides a terminal, including: a receiving unit, configured to receive downlink control information DCI sent by a base station, where the terminal is in a connected state, and the DCI carries scheduling information of a changed system message; the processing unit is used for determining resources occupied when the changed system message is issued according to the scheduling information of the changed system message; the processing unit is further configured to search the resource for the changed system message sent by the base station.

In one possible design, the DCI also carries a scrambling code;

the processing unit is further to:

and identifying that the DCI is the DCI carrying the scheduling information of the changed system message through the scrambling code.

In a fourth aspect, the present application provides a base station, comprising: a sending unit, configured to send DCI to a terminal, where the terminal is in a connected state, and the DCI carries scheduling information of a changed system message; the processing unit is used for occupying resources required when the changed system message is issued on the terminal according to the scheduling information of the changed system message; the sending unit is further configured to send the changed system message to the resource of the terminal.

In one possible design, the DCI also carries a scrambling code;

the processing unit is further to:

and informing the terminal that the DCI is the DCI carrying the scheduling information of the changed system message through the scrambling code.

In a fifth aspect, an embodiment of the present application further provides a terminal, including: a transceiver, a processor, and a memory; the memory is configured to store a software program, and the processor is configured to read the software program stored in the memory, transmit and receive data through the transceiver, and implement the method provided by the first aspect or any design of the first aspect. The terminal may be a mobile terminal, a computer, etc.

In a sixth aspect, an embodiment of the present application further provides a base station, including: a transceiver, a processor, and a memory; the memory is used for storing software programs, and the processor is used for reading the software programs stored in the memory, transmitting and receiving data through the transceiver, and implementing the method provided by the second aspect or any one of the designs of the second aspect.

In a seventh aspect, this embodiment of the present application further provides a computer storage medium, where a software program is stored, and when the software program is read and executed by one or more processors, the software program may implement the method provided by the first aspect, any design of the first aspect, or any design of the second aspect.

Drawings

Fig. 1 is a flowchart of a method for receiving system information according to an embodiment of the present disclosure;

fig. 2 is a flowchart of another method for receiving system information according to an embodiment of the present disclosure;

fig. 3 is a flowchart of a further method for receiving in a system according to an embodiment of the present application;

fig. 4 is a schematic diagram of a terminal according to an embodiment of the present application;

fig. 5 is a schematic diagram of a base station according to an embodiment of the present application;

fig. 6 is a diagram of a terminal hardware structure provided in the embodiment of the present application;

fig. 7 is a hardware structure diagram of a base station according to an embodiment of the present disclosure.

Detailed Description

Embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

Hereinafter, some terms in the present application are explained to be understood by those skilled in the art.

A terminal, which may be referred to as a user equipment, a mobile station, a terminal device, or a mobile terminal, may communicate with one or more core Network devices via a Radio Access Network (RAN). The terminal may be a mobile telephone (or so-called "cellular" telephone) or a computer with a mobile terminal, etc., which may also be a portable, pocket, hand-held, computer-included, or car-mounted mobile device, for example. The terminal can also be thing networking device, for example table class terminal, wearing equipment, commodity circulation is tracked, thing allies oneself with equipment such as elevator picture or sanitary. They exchange voice and/or data with the radio access network.

Resources, may include multiple types, such as: computing resources for providing computing power, storage resources for providing storage space, network resources for providing transmission channels, and so forth. The computing resource may be a Central Processing Unit (CPU) resource, and the storage resource may be a memory resource.

The plural in the present application means two or more.

The embodiment of the application provides a method and equipment for receiving system information, which are used for solving the problems that when connected BL/CE UE needs to receive changed SIBs information in the prior art, E-UTRAN needs to release BL/CE UE, resource overhead for releasing BL/CE UE is increased, and signaling overhead and power consumption overhead for re-accessing BL/CE UE to a network are also increased. The method and the device are based on the same inventive concept, and because the principles of solving the problems of the method and the device are similar, the implementation of the device and the method can be mutually referred, and repeated parts are not repeated.

An embodiment of the present application provides a method for receiving system information, as shown in fig. 1, including the following processes:

s101, a terminal receives downlink control information DCI issued by a base station, wherein the terminal is in a connected state, and the DCI carries scheduling information of a changed system message.

Specifically, the DCI is transmitted through an enhanced machine type communication Physical Downlink Control Channel (MTC Physical Downlink Control Channel, MPDCCH). The MPDCCH search space is divided into a user level search space USS and a common search space CSS, the CSS comprises a typeO CSS, the typeO CSS is used for feedback, 3/3A, user level TPC and other control messages, the narrow band (Narrowband, NB), Physical Resource Block (PRB) and scrambling codes which are the same as those of the user level search space USS are used, and the BL/CE UE in a connection state only monitors the MPDCCH of the USS and the typeO CSS at the same time. In order to enable the connected BL/CE UE to receive the system message change, the TypeO CSS function is enhanced, and the DCI directly carries the scheduling information for updating the system message.

S102, the terminal determines the resources occupied when the changed system message is issued according to the scheduling information of the changed system message.

S103, the terminal finds the changed system message sent by the base station on the resource.

In the embodiment of the application, a system information receiving method is provided, in which a connected terminal determines resources occupied when a changed system message is issued through received DCI, and after a base station issues the changed system message to the terminal, the terminal finds the changed system message on the resources, and in the process, the E-UTRAN does not need to release UE, so that the UE is in an idle state. By the method, the resource overhead of releasing the UE is reduced, and the signaling overhead and the power consumption overhead of re-accessing the network by the UE are also reduced.

In one possible implementation, the DCI also carries a scrambling code; the method further comprises the following steps: and the terminal identifies that the DCI is the DCI carrying the scheduling information of the changed system message through the scrambling code.

Specifically, the scrambling code may be SI-RNTI, and the DCI is identified as the scheduling information of the indication system message through the SI-RNTI.

In a possible implementation manner, the format of the DCI and the meaning of each bit in the DCI are pre-configured, and the bit of the DCI is at least 34 bits.

For example, the following steps are carried out: the Format of the DIC is Format 6-X, which is used to indicate scheduling information of the changed system message, and the specific Format is shown in table 1:

TABLE 1

Wherein the meaning of each bit is as follows:

flag SIB1-BR/SI other than SIB1-BR differentiation (SIB1/other SI Flag) -1bit, where a value of "0" indicates SIB1-BR and a value of "1" indicates SI other than SIB 1-BR.

If SIB1/other SI flag＝0：

Scheduling Info SIB1-BR-5bit, System Information Block Type1-BR Scheduling Information, the same as Scheduling Info SIB1-BR carried by the MIB.

If SIB1/other SI flag＝1：

si-Narrowband-

bit, NB location where the SI message is located.

And (4) a hopping flag is-1 bit, whether the SI information hops or not is judged, 0 represents that the SI hopping is not supported, and 1 represents that the SI hopping is supported.

Hopping NB-1bit, 0 indicates frequency Hopping between 2 NBs, 1 indicates frequency Hopping between 4 NBs

The Hopping interval-2bit is consistent with the interval-DL Hopping configcommon ModeB parameter carried in SIB 1-BR.

The Hopping Offset-3bit, frequency Hopping frequency domain interval, is consistent with the mpdcch-pdsch-Hopping Offset parameter carried in SIB 1-BR.

The SI-TBS-3bit, TBS of SI message, is consistent with SI-TBS parameter carried in SIB 1-BR.

The SI-Repetition Pattern-2bit, the repeating Pattern of the SI message, is consistent with the SI-Repetition Pattern parameter carried in the SIB 1-BR.

The SI-Window Length-BR-3bit, the SI message Window Length, is consistent with the SI-Window Length-BR parameter carried in SIB 1-BR.

The SIB-Type-4bit, the SI message Type, is consistent with the SIB-Type parameter carried in the SIB 1-BR.

DL Bitmap BR-10bit, the bit map of the Downlink available Subframe, is consistent with the previous 10 bits of the fdd-Downlink Or Tdd Subframe Bitmap BR parameter carried in SIB 1-BR.

In this embodiment, the DCI Format may also be a Format multiplexing an existing Format 6-1A.

An embodiment of the present application provides a method for receiving system information, as shown in fig. 2, including the following processes:

s201, a base station sends Downlink Control Information (DCI) to a terminal, wherein the terminal is in a connected state, and the DCI carries scheduling information of the changed system message.

S202, the base station occupies resources required when the changed system message is issued on the terminal according to the scheduling information of the changed system message.

S203, the base station sends the changed system information to the resource of the terminal.

In the embodiment of the present application, through interaction between a base station and a terminal, a connected terminal is implemented to receive a system change message, and therefore, a system information receiving method is provided, as shown in fig. 3, the method includes the following processes:

s301, the base station determines that the system message needs to be changed.

S302, the base station determines that the UE in the connection state which needs to accept the changed system message exists.

S303, the base station sends downlink control information DCI to the UE in a connection state, wherein the DCI carries the scheduling information of the changed system message.

S304, the UE in the connection state receives downlink control information DCI issued by the base station.

S305, the connected UE determines the resources occupied when the changed system message is issued according to the scheduling information of the changed system message.

S306, the base station sends the changed system information to the resource of the terminal.

S307, the UE in the connection state searches the changed system message sent by the base station on the resource.

Optionally, when the base station determines that there is no connected-state UE that needs to receive the changed system message but there is an idle-state UE, the base station notifies the idle-state UE of the need to change the system message through a Paging message.

Based on the same inventive concept as the method embodiment, the present application further provides a terminal schematic diagram, as shown in fig. 4, the terminal device includes:

a receiving unit 401, configured to receive downlink control information DCI sent by a base station, where the terminal is in a connected state, and the DCI carries scheduling information of a changed system message.

A processing unit 402, configured to determine, according to the scheduling information of the changed system message, a resource occupied when the changed system message is issued.

The processing unit 402 is further configured to find the changed system message sent by the base station on the resource.

In the embodiment of the application, a terminal in a connected state determines resources occupied when a changed system message is issued through received DCI, after a base station issues the changed system message to the terminal, the terminal finds the changed system message on the resources, and in the process, the E-UTRAN does not need to release UE, so that the UE is in an idle state. By the method, the resource overhead of releasing the UE is reduced, and the signaling overhead and the power consumption overhead of re-accessing the network by the UE are also reduced.

In one possible implementation, the DCI also carries a scrambling code; the processing unit 401 is further configured to: and identifying that the DCI is the DCI carrying the scheduling information of the changed system message through the scrambling code.

Based on the same inventive concept as the method embodiment, the present application further provides a schematic diagram of a base station, as shown in fig. 5, the base station includes:

a sending unit 501, configured to send downlink control information DCI to a terminal, where the terminal is in a connected state, and the DCI carries scheduling information of a changed system message.

A processing unit 502, configured to occupy, on the terminal, resources required when the modified system message is issued according to the scheduling information of the modified system message.

The sending unit 501 is further configured to send the changed system message to the resource of the terminal.

In the embodiment of the application, a base station is provided, where the base station sends DCI carrying scheduling information of a changed system message to a connected terminal and occupies a resource occupied when the changed system message is issued, and after the base station issues the changed system message to the terminal, the terminal finds the changed system message on the resource, and in this process, the E-UTRAN does not need to release the UE, so that the UE is in an idle state. By the method, the resource overhead of releasing the UE is reduced, and the signaling overhead and the power consumption overhead of re-accessing the network by the UE are also reduced.

In one possible implementation, the DCI also carries a scrambling code; the processing unit is further to: and informing the terminal that the DCI is the DCI carrying the scheduling information of the changed system message through the scrambling code.

The division of the modules in the embodiments of the present application is schematic, and only one logical function division is provided, and in actual implementation, there may be another division manner, and in addition, each functional module in each embodiment of the present application may be integrated in one processor, may also exist alone physically, or may also be integrated in one module by two or more modules. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode.

When the integrated module may be implemented in the form of hardware, as shown in fig. 6, the terminal may include a processor 601, and the hardware of the entity corresponding to the processing unit 402 may be the processor 601. The terminal may further include a transceiver 604, and the hardware of the entity corresponding to the receiving unit 401 may be the transceiver 604. The processor 601 may be a Central Processing Unit (CPU), a digital processing module, or the like. The terminal device further includes: a memory 602 for storing programs executed by the processor 601. The memory 602 may be a nonvolatile memory, such as a hard disk (HDD) or a solid-state drive (SSD), and may also be a volatile memory, such as a random-access memory (RAM). The memory 602 is any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer, but is not limited to such.

The processor 601 is configured to execute a program code stored in the memory 602, specifically invoke a program instruction stored in the memory 602, receive downlink control information DCI delivered by a base station through the transceiver 604, and determine a resource occupied when the modified system message is delivered according to the scheduling information of the modified system message; and searching the changed system message sent by the base station on the resource.

The specific connection medium between the processor 601 and the memory 602 is not limited in the embodiments of the present application. In the embodiment of the present application, the processor 601 and the memory 602 are connected by a bus 603 in fig. 6, the bus is represented by a thick line in fig. 6, and the connection manner between other components is merely illustrative and not limited thereto. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 6, but this is not intended to represent only one bus or type of bus.

As shown in fig. 7, the base station may include a processor 701, and the hardware of the entity corresponding to the processing unit 502 may be the processor 701. The base station may further include a transceiver 704, and the hardware of the entity corresponding to the sending unit 501 may be the transceiver 704. The processor 701 may be a Central Processing Unit (CPU), a digital processing module, or the like. The terminal device further includes: a memory 702 for storing programs executed by the processor 701. The memory 702 may be a nonvolatile memory such as a hard disk (HDD) or a solid-state drive (SSD), and may also be a volatile memory such as a random-access memory (RAM). The memory 702 is any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer, but is not limited to such.

The processor 701 is configured to execute a program code stored in the memory 702, specifically invoke a program instruction stored in the memory 702, send downlink control information DCI to a terminal through the transceiver 704, and occupy, on the terminal, a resource required when the modified system message is issued according to the scheduling information of the modified system message; sending the changed system message to the resources of the terminal via the transceiver 704.

The specific connection medium between the processor 701 and the memory 702 is not limited in the embodiment of the present application. In the embodiment of the present invention, the processor 701 and the memory 702 are connected by a bus 703 in fig. 7, the bus is indicated by a thick line in fig. 7, and the connection manner between other components is merely illustrative and not limited thereto. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown in FIG. 7, but this is not intended to represent only one bus or type of bus.

The embodiment of the present invention further provides a computer-readable storage medium, which is used for storing computer software instructions required to be executed for executing the processor, and which contains a program required to be executed for executing the processor.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present application without departing from the spirit and scope of the embodiments of the present application. Thus, if such modifications and variations of the embodiments of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to encompass such modifications and variations.

Claims

1. A method for receiving system information, comprising:

a terminal receives downlink control information DCI issued by a base station, wherein the terminal is in a connected state, and the DCI carries scheduling information and scrambling codes of changed system information;

the terminal determines the resources occupied when the changed system message is issued according to the scheduling information of the changed system message;

the terminal finds the changed system message sent by the base station on the resource;

the method further comprises the following steps:

and the terminal identifies that the DCI is the DCI carrying the scheduling information of the changed system message through the scrambling code.

2. The method of claim 1, wherein a format of the DCI and a meaning of each bit in the DCI are pre-configured, and wherein the bits of the DCI are at least 34 bits.

3. A method for receiving system information, comprising:

a base station sends Downlink Control Information (DCI) to a terminal, wherein the terminal is in a connected state, and the DCI carries scheduling information and scrambling codes of changed system information;

the base station occupies resources required when the changed system message is issued on the terminal according to the scheduling information of the changed system message;

the base station sends the changed system information to the resource of the terminal;

the method further comprises the following steps:

and the base station informs the terminal of the DCI carrying the scheduling information of the changed system message through the scrambling code.

4. The method of claim 3, wherein the format of the DCI and the meaning of each bit in the DCI are pre-configured, and wherein the bits of the DCI are at least 34 bits.

5. A terminal, comprising:

a receiving unit, configured to receive downlink control information DCI sent by a base station, where the terminal is in a connected state, and the DCI carries scheduling information and a scrambling code of a changed system message;

the processing unit is used for determining resources occupied when the changed system message is issued according to the scheduling information of the changed system message;

the processing unit is further configured to search the resource for the changed system message sent by the base station;

the processing unit is further to:

6. The terminal of claim 5, wherein the format of the DCI and the meaning of each bit in the DCI are pre-configured, and wherein the bits of the DCI are at least 34 bits.

7. A base station, comprising:

a sending unit, configured to send DCI to a terminal, where the terminal is in a connected state, and the DCI carries scheduling information and a scrambling code of a changed system message;

the processing unit is used for occupying resources required when the changed system message is issued on the terminal according to the scheduling information of the changed system message;

the sending unit is further configured to send the changed system message to the resource of the terminal;

the processing unit is further to:

8. The base station of claim 7, wherein the format of the DCI and the meaning of each bit in the DCI are pre-configured, and wherein the bits of the DCI are at least 34 bits.

9. A terminal, comprising:

a transceiver, a processor, and a memory;

the memory is used for storing software programs, and the processor is used for reading the software programs stored in the memory, transmitting and receiving data through the transceiver, and realizing the method of any one of claims 1 to 2.

10. A base station, comprising:

a transceiver, a processor, and a memory;

the memory is used for storing software programs, and the processor is used for reading the software programs stored in the memory, transmitting and receiving data through the transceiver, and realizing the method of any one of claims 3 to 4.

11. A computer-readable storage medium comprising instructions which, when executed on a computer, cause the computer to perform the method of any one of claims 1 to 2 or 3 to 4.