WO2008127162A1

WO2008127162A1 - A method of operating a radio access network with multiple radio access technologies

Info

Publication number: WO2008127162A1
Application number: PCT/SE2007/050247
Authority: WO
Inventors: Dalibor Turina
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2007-04-17
Filing date: 2007-04-17
Publication date: 2008-10-23

Abstract

In a cellular radio system supporting a multitude of radio access technologies, knowledge of the coverage of different standards is collected in and signaled to a mobile station when it is within reach for a particular standard. Hereby the mobile station can save a lot of battery. Hence, the network is set to adaptively learn about the coverage of different standards such as Wireless Local Area Networks (WLAN) coverage and aid mobile in the task of monitoring the area where it is currently located, thereby saving a lot of power for the mobile station.

Description

A METHOD OF OPERATING A RADIO ACCESS NETWORK WITH MULTIPLE

RADIO ACCESS TECHNOLOGIES

TECHNICAL FIELD

The present invention relates to a method and a system for operating a radio access network having multiple radio access technologies.

BACKGROUND

Today, new radio access technologies are being specified and subsequently implemented by operators of cellular telecommunications systems. Consequently it has become more and more common that one operator of a radio systems network has several radio access technologies being deployed concurrently in the same geographical area.

At the same time, mobile terminals are becoming more and more sophisticated often comprising capabilities for communicating over more than one type of radio access. Such evolution will impose a requirement to be able to use multi-access capabilities in an optimal way so that operator can make best usage of the deployed radio technologies. One of the most decisive parameters for optimizing the usage is the currently used capacity in different radio access technologies (RATs).

Furthermore, within a number of the existing standards different sub-standards have been developed. For example, within GSM the General Packet Radio Services (GPRS) and the Enhanced Data rates for GSM Evolution (EDGE) have been introduced. GPRS is a digital mobile technology where data can be sent in packet switched mode over the GSM air interface and EDGE is a digital mobile phone technology that allows for increased data transmission rate and improved data transmission reliability. Similarly within WCDMA, the High-Speed Downlink Packet Access (HSDPA) has been introduced. HSDPA is an evolution of the WCDMA standard. HSDPA achieves the increase in the data transfer speeds by defining a new transport channel: a high-speed downlink shared channel (HS- DSCH) that operates in a different way from existing WCDMA channels and is used for downlink communications to the mobile. Other standards such as CDMA and Long Term Evolution (LTE) have or will potentially have other sub-standards. As stated above, all these standards may exist overlapping within an area served by an operator and the operator of such a combined network of different standards is faced with the problem of having to manage the resources within the combined network in a way that both maximizes the use of the combined resources and maximizes the service provided to each mobile user within the combined network.

In order to always be able to attach to a most appropriate access technology, a multi-access capable mobile must also monitor all the accesses for performing measurements/identification. That however excessively drains the battery in mobile stations (MS) thus deteriorating the standby-time performance. As there arc today no efficient mechanisms to save the battery if multi-access scenario embraces standards developed in different bodies, e.g. GSM/WCDMA by 3GPP and WLAN by IEEE, it is also reflected in the battery consumption, which becomes very high indeed.

For example, an MS is performing both monitoring of 2G/3G cells and WLAN cells in order to connect to WLAN when applicable. And while 2G/3G monitoring has been designed for battery saving monitoring, the monitoring of WLAN is unnecessarily adding extra battery consumption, especially when assuming that WLAN has far worse coverage.

Hence, there exists a need for a method and a system that is able to continuously monitor different radio access possibilities for a particular mobile station to be able to benefit from all available radio access technologies, and at the same time keep the battery consumption for the mobile station at an acceptable level.

SUMMARY

It is an object of the present invention to overcome or at least reduce some of the problems associated with the prior art and to provide a method and a system which is able to benefit from all available radio access technologies, and at the same time keep the battery consumption for the mobile station at an acceptable level.

It is another object of the present invention to provide a method and a system that is able to reduce the battery consumption for mobile stations in a system where radio access technologies providing coverage only at some spots of a geographical area co-exist with radio access technologies having a broad coverage in the same geographical area. These objects and others are obtained by the method and system as set out in the appended claims. Thus by collecting the knowledge of the coverage of different standards in the cellular radio system e.g. in the Operation and Maintenance (O&M) system and signaling to the mobile station when it is within reach for a particular standard a lot of battery in the mobile station can be saved. In other words, the network can be set to adaptively learn about the coverage of different standards such as Wireless Local Area Networks (WLAN) coverage and aid mobile in the task of monitoring the area where it is currently located, thereby saving a lot of power for the mobile station.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in more detail by way of non-limiting examples and with reference to the accompanying drawings, in which:

- Fig. 1 is a view illustrating a radio system network comprising multiple radio access technologies.

- Fig.2 is a flowchart illustrating different steps performed when updating the radio system network, and when signaling radio access information from a radio system to a mobile station - Fig. 3 is a flow chart illustrating different steps performed in a mobile station (MS) when receiving radio access information from a radio network.

DETAILED DESCRIPTION

In Fig.l a view illustrating an exemplary radio system network comprising multiple radio access technologies is shown. The system depicted in Fig. 1 comprises two different radio access technologies deployed within the same geographical area. It is understood that additional radio access technologies can be deployed along side the two radio access technologies shown in Fig. 1 , but to simplify the Figure only two radio access technologies are shown. The radio access technologies may for example be a GSM system comprising cells 101 and WLAN cells 103 deployed at hot spots within the GSM network. However, the system and method as described herein is not limited to any particular radio access technologies and the cells 101 and 103 could equally well correspond to WCDMA, LTE, WiMAX or any other technology providing radio access. A mobile station (MS) supporting a number of radio access technologies, which is present in the geographical area depicted in - A -

Fig.l will continuously monitor all the radio access technologies that it supports to try to find the best way of access when moving around within the geographical area.

In the area depicted in Fig. 1 the mobile station can be instructed not to activate monitoring of WLAN until signaled to activate WLAN monitoring by the network. For the mobile station not to miss any WLAN access opportunities the network should have as good knowledge as possible of where WLAN coverage exists.

In accordance with one embodiment the network is provided with precise and updated knowledge of the WLAN coverage mapped onto the cellular one.

The information about the WLAN coverage mapping onto the cellular one can be obtained by performing regular cell-selection measurements with separate equipment at each WLAN access point location. This information about the macro cell that embraces the coverage of the particular WLAN access point is then stored by the network.

In accordance with another embodiment every WLAN access point can be provided with a measurement capability for macro cells in the area such as GSM/WCDMA in order to regularly perform a cell-reselection procedure using identical algorithm as a regular mobile station. However instead of registering itself in the network the WLAN access point can be adapted to signal to the network through its own backhaul, the information about the "macro cell" that has best radio coverage in accordance with the performed cell reselection procedure performed. With such an approach, the network can always have the accurate information about where in the network a particular WLAN access point is located. The information collected and sent to the network can typically include: WLAN access point identity and network identity (SSID), macro cell base station identity (BSID) and possibly its own location such as coordinates established via a Global Positioning System (GPS), if available. The information collected using any of the methods above or any other suitable method can be stored into the O&M databases and than used to signal to the mobile station when the mobile station is located in an area where it is possible that WLAN coverage can be obtained as determined by the information stored in the O&M system. Such a method is depicted in Fig. 2.

Thus with reference to Fig. 2 information relating to the WLAN is first transmitted to the network, step 201. Next the information relating to all access points received is stored in a memory of the network, step 203. Thereupon when a mobile station enters an area where WLAN access is possible in accordance with the information stored by the network, the network transmits an activation signal to the mobile station signaling the existence of WLAN access points in the area where the mobile station is present, step 205.

The signaling message to the mobile station should preferably be a standardized message to be standardized. When a mobile station enters a certain cell or location area, the system checks if and if there are access points present in that cell/location area for that mobile station to access by referring to the information stored about access points and transmitting that information back to the mobile station. It is then up to the mobile station to activate the WLAN monitoring if deemed needed, e.g. the mobile station recognizes its home access point that it wants to attach to by default. When WLAN monitoring activated, the mobile station can proceed with regular WLAN attach procedures.

In Fig. 3, a flow chart illustrating different steps performed in a mobile station (MS) when receiving radio access information from a radio network is shown. Thus, first in a step 301 , the mobile station receives a message from the radio network that the cell where the mobile station currently is present has at least one WLAN access point deployed that the mobile station may want to connect to. Based on the information received by the radio network, the mobile station may or may not enable WLAN monitoring. Activation of WLAN monitoring can be dependent on a number of parameters. The parameters may be user configurable. For example the mobile station can be configured to only monitor WLAN if close to its home access point or it may be configured to always search for WLAN access points regardless of location. This is performed in step 303. When the mobile station continues to travel the radio network continuously transmits new information corresponding to the current location of the mobile station. Thus, if the mobile station enters a cell where no WLAN access is possible the radio network informs the mobile station by signaling such information to the mobile station, which then can deactivate WLAN monitoring to save battery consumption.

By using the method and system as described herein a significant battery saving for monitoring of a multitude of radio access technologies can be obtained. The method and system are particularly power saving when monitoring radio access technologies being of a spotty nature such as a WLAN or other similar radio access technologies, where large parts of a geographical area is not covered by that radio access technology.. To update the network with up to date information about wherein the network different access points are located, the access points can be equipped with a device corresponding to a receiver of a mobile station, such as a GSMAVCDMA receiver, which will keep the cost low and not causing any additional load in the cellular network.

Claims

1. A method of monitoring radio access in a mobile station enabled to access a cellular radio system through at least two different radio access technologies, characterized by:

- receiving an information message from the cellular radio system related to available radio access technologies at a position where the mobile station currently is located, and

- monitoring radio access in response to the received information message.

2. The method according to claim 1, characterized in that the information message comprises information about which radio access standards that are currently within reach for the mobile station.

3. The method according to claim 2, characterized in that the mobile station is set to only monitor radio access standards that are currently within reach for the mobile station as given by the infoπnation message or a subset thereof.

4. The method according to any of claims 1 - 3, characterized in that the information message comprises infoπnation about if a spotty standard is within reach for the mobile station.

5. The method according to any of claims 1 - 4, characterized in that the information message comprises information about if a Wireless Local Area Network (WLAN) is within reach for the mobile station.

6. A mobile station enabled to access a cellular radio system through at least two different radio access technologies, characterized by:

- means for receiving an information message from the cellular radio system related to available radio access technologies at a position where the mobile station currently is located, and

- means for monitoring radio access in response to the received information message.

7. The mobile station according to claim 6, characterized by means for only monitoring radio access standards that are currently within reach for the mobile station as given by the information message or a subset thereof.

8. The mobile station according to any of claims 6 or 7, characterized by means for only monitoring a spotty radio access standard if the information message comprises information about a spotty standard being within reach for the mobile station.

9. The mobile station according to any of claims 6 - 8, characterized in that the mobile station supports a Wireless Local Area Network (WLAN) standard.

10. A radio coverage node of a cellular radio system supporting at least two different radio access technologies, characterized by: - means for collecting and storing information about different radio access points within the cellular radio system, and

- means for transmitting messages to mobile stations within the cellular radio system comprising information related to which radio access technologies that are available at the position where a particular mobile station is currently located.

1 1. The radio coverage node according to claim 10, characterized in that the information message comprises information about which radio access standards that are currently within reach for the mobile station.

12. The radio coverage node according to any of claims 10 or 1 1, characterized in that the information message comprises information about if a spotty standard is within reach for the mobile station.

13. The radio coverage node according to any of claims 10 - 12, characterized in that the information message comprises information about if a Wireless Local Area Network (WLAN) is within reach for the mobile station.