WO2013128370A1

WO2013128370A1 - Method and apparatus for providing a discovery resource in a mobile communication network

Info

Publication number: WO2013128370A1
Application number: PCT/IB2013/051530
Authority: WO
Inventors: Sami-Jukka Hakola; Matti Pikkarainen; Ville Vartiainen; Anna Pantelidou; Juha Pekka KARJALAINEN; Timo Koskela; Samuli Turtinen
Original assignee: Renesas Mobile Corp
Current assignee: Renesas Electronics Corp
Priority date: 2012-02-28
Filing date: 2013-02-26
Publication date: 2013-09-06
Anticipated expiration: 2014-08-28
Also published as: GB201203455D0; GB2499803A; GB2499803B

Abstract

An arrangement for providing network controlled discovery process and resources in a network in a manner that the use of discovery process does not interfere with the other resources of the cell. In the arrangement a frame structure is selected so that the discovery process does not interfere with the uplink and/or downlink resources of the cell. This is provided by using at least one guard period in the subframe used for discovery resources, configured in accordance with the determined largest propagation delay in the cell.

Description

METHOD AND APPARATUS FOR PROVIDING A DISCOVERY RESOURCE IN A MOBILE COMMUNICATION NETWORK

Technical Field

The invention relates to radio communication devices.

Background

In modern mobile communications proximity- based applications and services have been developed. These applications and services are expected to become very popular. In proximity based services at least two devices or users are close to each other and communicate with each other. These applications and/or services naturally generate traffic between devices. The communication may be between two or more users and users may be ordinary end users, service providers or other devices.

Examples of such applications and services include, social applications, local advertising, multiplayer gaming, network offloading, smart meters, public safety and similar. For example, social applications include exchange of files, photos, messages and similar, voice over IP conversation, video streaming, video conferencing or similar. Local advertising may be used for providing information on different services in the neighborhood. Network offloading may be used when an opportunistic proximity offload potential exists. For example, the first device initiates a transfer of the media flow from the macro network to a proximity communications session with the second device conserving macro network resources while maintaining the quality of user experience for the media session. The communication is not necessarily initiated by the device but can also be initiated by the network. Further applications and services are continuously developed the only common nominator required is the proximity of communicating parties even if there is no explicit definition for the distance between communicating devices.

A commonly known solution is to use short distance communication network technologies, such as Bluetooth, for providing proximity services. However, this has also drawbacks the major drawback being that it cannot be controlled by the network operator. Furthermore, Bluetooth and other short distance communication means are not always turned on as they require energy. Thus, it is desirable to provide proximity based services using the same communication channel with ordinary phone calls and data communication.

As a consequence of above it is desired that this radio-based discovery process used for providing proximity services needs also to be coupled with the system architecture and security architecture of a mobile network. This allows the mobile operators to retain control of the device behavior. For example, who can emit discovery signal. Furthermore, the operator may want to control what is the structure of these signals and when they are sent. The problem in providing such service using mobile communication network is how to fit it into the same communication resources with the other communication in a manner that the discovery process and the relating communication using discovery resources do not cause interference to the downlink and/or uplink communication that is transmitted in the same multiplex with the discovery related communication. Summary

The present invention discloses a method for providing a discovery resource in a mobile communication network. In the method a discovery area for at least one service is determined. The discovery area comprises at least one cell. The largest propagation delay for each cell in the determined discovery area is determined. The frame structure for discovery area communication is then configured in accordance with the largest propagation delay in the determined discovery area. The frame structure comprises a plurality of sub frames. The frame structure is configured in accordance with the determined largest propagation delay in the cells belonging to the discovery area. In an embodiment of the invention a guard period in the end of the subframe used for the discovery resource is provided. In a further embodiment a guard period in the beginning of the subframe used for the discovery resource is provided. In a further embodiment a discovery resource is configured to follow a random access channel communication. In this embodiment the guard period is not needed in the beginning of the frame as there is no uplink communication preceding the discovery resource. In a further embodiment the guard period is configured as a maximum propragation value within the discovery area. In a further embodiment the largest propagation delay is obtained by requesting and receiving it from at least one cell. The present invention may be implemented as an apparatus, such as a network element of a mobile communication network. The network element comprises a network connection to at least one mobile network cell, a memory configured to store communication parameters and a processor configured to determine and execute communication parameters for said at least one mobile network cell. The network element is configured to perform the above mentioned embodiments. The present invention may be implemented as computer software that comprises computer program code that is executed by the processor of the network element. In a further embodiment of the invention the network element is a part of a system comprising a plurality of cells for mobile communications. In a further embodiment of the invention the network is an LTE (Long Term Evolution) or LTE-A (Long Term Evolution Advanced) network.

The invention described above discloses a method and required hardware components for implementing network controlled discovery communications that do not interfere with the conventional communication of the mobile network. Some Embodiments of the present invention are suitable for different types of mobile networks and are scalable for different types of network configurations. Some Embodiments of the present invention do not set limits for the discovery area like short distance networks but the network operator may determine the discovery area in accordance with the actual need and the network design.

Brief Description of the Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

Fig. 1 is a block diagram of an embodiment according to the present invention, Fig. 2 is a flowchart of an embodiment according to the present invention, and Fig. 3 is an illustration of a frame structure according to an embodiment of the present invention. Detailed Description

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

Figure 1 is a block diagram of an embodiment of the present invention. In the figure a network element 10 is arranged to communicate with cells 14a - 14d of a mobile network. The network element 10 comprises a processor 11, a memory 12 and a network connection 13. The network connection 13 is capable of communicating with cells 14a - 14d. Typically this connection is a fixed connection but also wireless connections may be used. Cells 14a - 14d are cells of a mobile communication network. For example, eNodeB's in an LTE network. The present invention is typically used in a network that has synchronized downlink and uplink transmission, such as an LTE-network. The network element 10 is configured to perform the inventive method in accordance with figure 2 that is explained below. In the method the processor 11 is configured to determine a discovery area for services that are used. The determination may be done manually or the network element can be configured to monitor discovery request made in the whole network and then based on statistical analysis to divide the network into suitable discovery areas automatically. Automatic configuration may be assisted by a system administrator. The network element 10 is configured to follow downlink frame timing and to adjust guard periods to the frame structure in accordance with the largest propagation delay in the neighborhood.

The allocated discovery resources are multiplexed with resources used for normal cellular communications of the network. The multiplexing can be in time and/or frequency domain. In the embodiment of figures 1 and 2 the guard periods are provided in time domain in the beginning and the end of each subframe allocated for discovery resources. This facilitates appropriate discovery resource communication so that different devices that are located in different distances from the cell do not cause interference to other communication. The required length of the guard periods is determined by the propagation delay of the devices in the discovery area. As the different devices are located at different distances from the cell or cells they are connected to they all have respective propagation delay from the device to the cell. If no impact to any cellular user either in previous or next subframe is desired the guard periods for the discovery signal should correspond with largest propagation delay of connected devices. It should be noticed that it is not necessary to use the largest propagation delay but a shorter period may be chosen. However, shorter periods are not sufficient to guarantee interference free discovery communication and are sufficient only for reducing the interference.

In figure 1 a further embodiment of the invention is disclosed. Signaling 15 and 16 discloses an arrangement wherein the network element 10 communicates with cell 14a. Corresponding communication is performed also with all cells belonging to the same discovery area, such as cells 14b - 14d in figure 1, however, for the sake of the clarity only one cell is explained here. The network in the example is an LTE network wherein max (TA/2)-value (Timing Adjustment) corresponds with the largest propagation delay. Thus, the (TA/2)-value may be requested and received in accordance with the invention. The LTE network is just an example used in the embodiment of figure 1. Different network types may also be used. Thus, instead of (TA/2)-value differently named value or different mechanism for acquiring largest propagation delay may be used.

In signal 15 a request for max (TA/2)-value in a cell is sent. As a response the max (TA/2)-value in a cell is received. The requested value is then used for configuring frame structure for the cell with proper guard periods as discussed above. In addition to the determination of the guard periods the configuring the frame structure may comprise further selections, such as the frame format. These further selections may depend on the determined discovery area, included cell types, or other parameters that need to be configured.

Figure 2 discloses a method according to an embodiment of the present invention. In the method first a discovery area is determined, step 20. The determination may be manual selection of a skilled person or determined automatically by using discovery communication analysis. In the communication analysis the use of discovery resources is measured and then the areas are determined so that the effective use of resources is guaranteed. In addition to above mentioned methods it is possible to use a combination of both, wherein a person skilled in the art fine tunes the parameters of the automatically determined area. Then the largest propagation delay within the discovery area is requested for each cell, step 21. As explained above it is possible to acquire this knowledge by requesting from each of the cells in the discovery area. Then the frame structure is determined accordance with the largest propagation delay in the whole discovery area, step 22. In the embodiment of figure 2 guard periods corresponding with (TA/2)-value are provided in the beginning and end of the each subframe allocated for discovery process and resources. The length of the guard period is determined in accordance with the largest propagation delay in the discovery area. Finally the allocated resource is used for communication, step 23.

In a further embodiment the subframe structure utilizes a longer structure by not shrinking the subframe from the beginning of the subframe when the discovery or D2D (Device to device) communications resource is taking place on the same resources as RACH (Random Access Channel) in previous uplink subframe. This connection can be specified as an implicit mapping between the discovery resource allocation and known RACH resources by devices. This is applicable in case there is an uplink subframe in neighbor cells simultaneously with the mentioned RACH resources in the cell in question. This embodiment may be used in the subframe following the special subframe in TDD-system, basically when discovery takes place in subframe #2 in the frame.

Figure 3 discloses an illustration of a frame structure according to an embodiment of the present invention. In the first row of the illustration four subframes 30 - 33 are arranged in accordance with DL TX (Downlink Transmitter) timing. In the second row DL RX (Downlink Receiver) timing for a device located near the cell center is disclosed. Thus, the propagation delay 34 is small. In the third row DL RX timing for a device located near the cell edge is disclosed. Thus, the propagation delay 35 is large. In the figure this is assumed as the largest propagation delay. The discovery process follows the DL TX timing. Thus, the discovery transmission would cause interference to the transmissions as illustrated by the hatched area in rows 2 and 3 respectively. The hatched are equals to the propagation delay of the corresponding row. In the fourth row discovery communication 36 is sent according to a conventional method. From this figure it can be seen the above explained interference in the beginning of the transmission. In the fifth row a discovery communication according to the present invention is disclosed. The discovery communication is sent in the subframe 31 and it is preceded and followed by subframes 30, 32 used for conventional communication, as can be seen from the figure. The discovery communication 38 is preceded by guard period 37 in order to avoid the above described interference related to the downlink communication. The uplink communication is not illustrated in the figure, however, a guard period 39 is arranged after discovery communication 38 in order to avoid the corresponding interference in the uplink transmission.

The above mentioned method may be implemented as computer software which is executed in a network element, such as the network element disclosed above. When the software is executed in a computing device it is configured to perform the above described inventive method in order to facilitate discovery resources in a mobile communication network. The software is embodied on a computer readable medium so that it can be provided to the computing device.

As stated above, the components of the exemplary embodiments can include computer readable medium or memories for holding instructions programmed according to the teachings of the present inventions and for holding data structures, tables, records, and/or other data described herein. Computer readable medium can include any suitable medium that participates in providing instructions to a processor for execution. Such a medium can take many forms, including but not limited to, nonvolatile media, volatile media, transmission media, and the like. Non-volatile media can include, for example, optical or magnetic disks, magneto -optical disks, and the like. Volatile media can include dynamic memories, and the like. Transmission media can include coaxial cables, copper wire, fiber optics, and the like. Transmission media also can take the form of acoustic, optical, electromagnetic waves, and the like, such as those generated during radio frequency (RF) communications, infrared (IR) data communications, and the like. Common forms of computer-readable media can include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other suitable magnetic medium, a CD-ROM, CD±R, CD±RW, DVD, DVD-RAM, DVD±RW, DVD±R, HD DVD, HD DVD-R, HD DVD-RW, HD DVD-RAM, Blu- ray Disc, any other suitable optical medium, a RAM, a PROM, an EPROM, a FLASH-EPROM, any other suitable memory chip or cartridge, a carrier wave or any other suitable medium from which a computer can read.

It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above; instead they may vary within the scope of the claims.

Claims

1. A method for providing a discovery resource in a mobile communication network comprising:

determining a discovery area for at least one service, wherein the discovery area comprises at least one cell;

determining a largest propagation delay for each cell in the determined discovery area; and

configuring the frame structure for each cell for discovery area communication in the determined discovery area, wherein the frame structure comprises a plurality of subframes and wherein said frame structure is configured in accordance with the determined largest propagation delay in the discovery area.

2. A method according to claim 1 , wherein configuring the frame structure comprises providing a guard period in the end of a subframe used for the discovery resource.

3. A method according to claim 1 or 2, wherein configuring the frame structure comprises providing a guard period in the beginning of a subframe used for the discovery resource.

4. A method according to claim 2, comprising arranging the discovery resource subsequent to a random access channel communication.

5. A method according to any of claims 2 to 4, wherein the or each guard period is configured as a maximum (T A/2)- value within the cell.

6. A method according to any of claims 1 to 5, wherein the method further comprises:

requesting the maximum propagation delay from at least one cell; and receiving said requested maximum propagation delay from at least one cell.

7. An apparatus comprising:

network connection to at least one mobile network cell;

a processing system arranged to cause the apparatus to:

determine a discovery area for at least one service, wherein the discovery area comprises at least one cell;

determine a largest propagation delay for each cell in the determined discovery area;

configure the frame structure for each cell for discovery area communication in the determined discovery area, wherein the frame structure comprises a plurality of subframes and wherein said frame structure is configured in accordance with the determined largest propagation delay.

8. An apparatus according to claim 7, wherein the processing system is further arranged to cause the apparatus to configure the frame structure by providing a guard period in the end of the subframe used for the discovery resource.

9. An apparatus according to claim 7 or 8, wherein the processing system is further arranged to cause the apparatus to configure the frame structure by providing a guard period in the beginning of the subframe used for the discovery resource.

10. An apparatus according to claim 8, wherein the discovery resource is arranged subsequent to a random access channel communication.

11. An apparatus according to any of claims 7 to 10, wherein the guard period is configured as a maximum propagation delay within the cell.

12. An apparatus according to any of claims 7 to 11, wherein the processing system is further arranged to cause the apparatus to:

request a maximum propagation delay from at least one cell; and receive said requested maximum propagation delay from at least one cell.

13. An apparatus according to any of claims 7 to 12, wherein said apparatus is a network element of an LTE or LTE-A network.

14. A computer program comprising a set of instructions, which, when executed by a computer, causes the computer to implement the method of any of claims 1 to 6.

15. The computer program according to claim 14 wherein said computer program is stored on a computer readable medium.

16. A system comprising :

a mobile network comprising a plurality of cells;

a network element, which network element further comprises:

a network connection to at least one mobile network cell;

a memory configured to store communication parameters; and

a processor configured to determine and execute communication parameters for said at least one mobile network cell;

wherein the network element is configured to:

17. A system according to claim 16, wherein the network element is further configured to configure the frame structure by providing a guard period in the end of the subframe used for the discovery resource.

18. A system according to claim 16 or 17, wherein the network element is further configured to configure the frame structure by providing a guard period in the beginning of the subframe used for the discovery resource.

19. A system according to claim 16 or 17, wherein a subframe used for the discovery resource is configured to follow a random access channel communication.

20. A system according to any of claims 16 to 19, wherein the or each guard period is configured as a maximum (TA/2)-value within the cell.

21. A system according to any of claims 16 - 20, wherein the network element is further configured to:

request a maximum propagation delay from at least one cell; and

receive said requested maximum propagation delay from at least one cell.

22. A system according to any of claims 21 to 26, wherein said mobile network is an LTE or LTE-A network.