GB2452690A

GB2452690A - Selecting a radio access network

Info

Publication number: GB2452690A
Application number: GB0709798A
Authority: GB
Inventors: Markus Muck; David Grandblaise
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 2007-05-22
Filing date: 2007-05-22
Publication date: 2009-03-18
Anticipated expiration: 2027-05-22
Also published as: GB2452690B; GB0709798D0; WO2008147652A1

Abstract

A heterogeneous communication system comprises a plurality of radio access systems 101-105. The system further comprises a pilot signal unit 119 which transmits a pilot signal in only part of the coverage area of the communication system. The pilot signal is independent of the radio access systems and comprises first access data for at least a first radio access system 101. The first radio access system comprises access points 111, 113 for transmitting a first communication channel comprising second access data for at least a second radio access system 103. At least some of the second access data for the second radio access system are not included in the first access data. The first access data furthermore comprises a pointer to the first communication channel. The invention provides access to different radio access systems for a configurable user equipment 109, avoiding the need to scan through a set of systems. Reconfiguration access data is also distributed over the different radio access systems thereby reducing loading on each system.

Description

A HETEROGENEOUS COMMUNICATION SYSTEM AND METHOD OF OPERATION

THEREFOR

Field of the invention

The invention relates to a heterogeneous communication system and a method of operation therefor, and in particular to a heterogeneous communication system comprising a plurality of radio access systems.

Background of the Invention

Wireless communication systems are becoming increasingly ubiquitous and are continuously developing to provide improved coverage and services. Currently, the trend is towards integrating different communication systems and standards to provide a more flexible and enhanced seamless user experience.

Specifically, communication systems may comprise a distributed network of heterogeneous radio access systems using different Radio Access Technologies (RATs) including for example WiMAXTM, WiFiTM (IEEE8O2.lla/b/g/n, etc.), cellular communication standards (e.g. Global System for Mobile communication (GSM), 3Lf Generation Partnership Project (3GPP), etc.), Digital Video Broadcast -Terrestrial (DVB-T), Digital Audio Broadcast (DAB) access networks etc. In heterogeneous and reconfigurable wireless systems, terminals and network equipments have enhanced capabilities for adapting to the available environment. In particular, the mobile terminals served by the access networks typically include reconfigurable multi-mode terminals which can use different wireless access technologies and different RATs.

Thus, in many such systems, each terminal/user can use several strategies for getting the best service requested by the user. Multi-mode and reconfigurable terminals have the capability to connect simultaneously to one or several wireless network resources and also to self-reconfigure in order to connect to a new radio access system! technology available in a cell. Multi-mode and reconfigurable network equipments allow an enhanced capability in either dynamically increasing radio access resources or in reconfiguring nodes to dynamically make new resources available depending on the resource demands in a given area.

The multi-mode and reconfigurable terminals preferably automatically adapt to new scenarios.

A critical problem in such heterogeneous communication systems is that of how to adapt the operation to the specific conditions experienced in various locations. Due to the heterogeneous nature of the system, it is practical to implement a high degree of distribution of functionality.

For example, it is advantageous that the individual mobile terminals to a large degree autonomously decides which radio access systems are available, which system(s) to access, how much resource to request from each system etc. In order to support such mobile terminal based decisions, it has been proposed to transmit information from the network providing data indicative of e.g. characteristics of the available access systems.

For example, cognitive systems have been proposed wherein cognitive data is transmitted describing properties of existing access systems, reconfiguration data required by reconfigurable terminals to adapt to the different existing systems etc. However, a problem in such systems is that in order to provide sufficient information for all eventualities the amount of data to be transmitted may be very high resulting in a high bandwidth and resource usage for transmission of this information.

Another problem of such heterogeneous system is that of how to efficiently broadcast the cognitive data. For example, it has been proposed to use a dedicated, standardised pilot signal to broadcast the cognitive data thereby allowing all mobile terminals to be preconfigured to obtain the relevant information from this broadcast. However, such an approach potentially uses a significant amount of frequency resource which must be reserved for the specific transmission of the cognitive data. Also, it requires a distribution of dedicated functionality, such as transmitters, to ensure full coverage resulting in a high cost and complexity as well as a complicated initial deployment. Also, additional functionality and resource is required to obtain the required information and to manage and maintain the system.

Hence, an improved heterogeneous communication system would be advantageous and in particular a system allowing increased flexibility, reduced complexity, facilitated and/or improved access data distribution, reduced resource consumption and/or improved performance would be advantageous.

Summary of the Invention

Accordingly, the Invention seeks to preferably mitigate, alleviate or eliminate one or more of the above mentioned disadvantages singly or in any combination.

According to a first aspect of the invention there is provided a heterogeneous communication system comprising a plurality of radio access systems, the system comprising: broadcast means for transmitting a pilot signal in only part of the coverage area of the communication system, the pilot signal being independent of the radio access systems and comprising first access data for at least a first radio access system; and a first radio access system comprising means for transmitting a first communication channel comprising second access data for at least a second radio access system, at least some of the second access data for the second radio access system not being included in the first access data; and wherein the first access data comprises a pointer to the first communication channel.

The invention may provide an improved heterogeneous communication system. In particular, the invention may provide a dedicated pilot signal to facilitate access/reconfiguration by a configurable user equipment without requiring this pilot signal to be ubiquitous. Also, the amount of access data transmitted by the dedicated pilot signal may be reduced substantially resulting in reduced frequency and/or power resource being required. The invention may facilitate a gradual or partial roll- out of dedicated pilot signal support for access data. The invention may allow a user equipment to obtain necessary access data in the absence of the dedicated pilot signal.

Specifically, the user equipments do not require, yet can benefit from, the presence of a dedicated pilot signal independent of the individual pilot signal.

The distribution of access data across different transmission systems allows facilitated operation by the user equipment as well as an improved resource distribution between different transmission approaches.

The pilot signal is independent of the access systems in that it does not require the configurable user equipment to be configured for any of the access systems in order to receive the pilot signal. Rather, the pilot signal may be transmitted in accordance with its own standard which is different from any of the standards of the access systems.

The pilot signal may be a dedicated physical channel.

Specifically, the pilot signal may be a physical layer signal transmitted in its own dedicated frequency band.

The first communication channel may specifically be a broadcast or multi-cast channel of the first radio access system. The communication channel may be a logical channel of the first radio access system and may specially be implemented at a higher layer of the network model. For example, the communication channel may be a logical link on top of data exchange channels and may be conveyed by an existing radio access system used for user data exchange.

E.g. a Network layer application may generate the second access data and transmit it on the communication channel using standard PHY layer and MAC layer applications.

The access data may comprise access data that enables, facilitates, assists and/or controls the access or the selection of an access system by the configurable user equipment.

According to an optional feature of the invention, the heterogeneous communication system further comprises a second radio access system comprising means for transmitting a second communication channel comprising third access data for at least a third radio access system, at least some of the third access data for the second radio access system not being included in the first access data or the second access data.

According to another optional feature, the heterogeneous communication system further comprises access data management means comprising: means for receiving access data for a plurality of the access systems; means for determining non-identical access data sets to be transmitted by different access systems in response to the received access data; means for distributing the non-identical access data sets to the different access systems; and wherein each of the different access systems comprises means for broadcasting the access data set allocated to it.

Thus, access data may be distributed over a plurality of radio access systems thereby providing an improved heterogeneous communication system. In particular, the invention may reduce the loading of each access system and/or facilitate and/or speed up the retrieval of access data by the individual configurable user equipment. The invention may facilitate the interoperation of different radio access networks and may assist a configurable user equipment in better exploiting the options available to it at any given time/location.

According to another aspect of the invention there is provided a method of operation for a heterogeneous communication system including a plurality of radio access systems, the method comprising: transmitting a pilot signal in only part of the coverage area of the communication system, the pilot signal being independent of the radio access systems and comprising first access data for at least a first radio access system, and transmitting a first communication channel comprising second access data for at least a second radio access system, at least some of the second access data for the second radio access system not being included in the first access data; and wherein the first access data comprises a pointer to the first communication channel.

These and other aspects, features and advantages of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

Brief Description of the Drawings

Embodiments of the invention will be described, by way of example only, with reference to the drawings, in which FIG. 1 illustrates an example of a heterogeneous communication system in accordance with some embodiments of the invention; FIG. 2 illustrates an example of a user equipment in accordance with some embodiments of the invention; FIG. 3 illustrates an example of transmissions of access data in accordance with some embodiments of the invention; FIG. 4 illustrates an example of an access data management controller in accordance with some embodiments of the invention; and FIG. 5 illustrates a method of operation for a heterogeneous communication system in accordance with some embodiments of the invention.

Detailed Description of Some Embodiments of the Invention FIG. 1 illustrates an example of a heterogeneous communication system in accordance with some embodiments of the invention.

The heterogeneous communication system comprises a plurality of different radio access systems 101, 103, 105. In the example, each of the radio access systems 101, 103, 105 is an independent communication system capable of fully supporting communication services independently of other radio access systems 101, 103, 105. Also, in the example, the communication system comprises heterogeneous Radio Access Technologies (RATs) and in particular the air interface technology used by each radio access systems 101, 103, 105 is different. Thus, in the example each of the radio access systems 101, 103, 105 operates in accordance with a different communication standard which may include for example standards such as WiMAXTM, WiFiTM (IEEE8O2.lla/b/g/n, etc.), cellular communication standards (e.g. Global System for Mobile communication (GSM), 3Id Generation Partnership Project (3GPP), etc.) Digital Video Broadcast -Terrestrial (DVB-T), Digital Audio Broadcast (DAB) etc. FIG. 1 illustrates a first radio access system 101 which is a WMAXrM communication system, a second radio access system 103 which is a cellular Universal Mobile Telecommunication System (UMTS) and a third radio access system 105 which is an IEEE 802.lln communication system.

In the example, the radio access systems 101, 103, 105 are coupled together via an interconnecting network 107 which allows data to be exchanged between the different radio access systems 101, 103, 105. The interconnecting network 107 may be a complex network comprising routing functionality etc or may e.g. be a simple network providing a direct data connection between different radio access systems 101, 103, 105. Each of the radio access systems 101, 103, 105 comprises interworking functions allowing communication with the interconnecting network 107 and/or with other radio access systems 101, 103, 105. Thus, the system allows for interaction between the different radio access systems 101, 103, 105 and for example allows communication between user equipments supported by different radio access systems 101, 103, 105 or may allow a communication service to be supported by any one or more of the radio access systems 101, 103, 105.

FIG. 1 also illustrates a user equipment 109 which is arranged to communicate using one or more communication services of one or more of the radio access systems 101, 103, 105. The user equipment 109 may e.g. be a mobile phone, a FDA, a laptop or any other communication entity capable of communicating over the air interface of one or more of the radio access systems 101, 103, 105.

The user equipment 109 is a configurable user equipment which can adapt its operation to the specific requirements and conditions currently experienced by the user equipment 109. In the example, the user equipment 109 is a software definable radio which can change its configuration and operation to communicate over at least two of the radio access systems 101, 103, 105. Furthermore, the user equipment 109 can reconfigure its operation depending on the specific characteristics of one or more of the radio access systems 101, 103, 105. For example, it may adapt the used resource from each radio access systems 101, 103, 105 depending on the loading and resource availability of each radio access system 101, 103, 105.

Thus, in the heterogeneous communication system, the terminals (user equipments) and network equipments have enhanced capabilities for adapting to the available environment. Such adaptation may include the modification and reconfiguration of the user equipments to enable new capability and functionality as well as an adaptation of the operational procedures, such as resource allocation/request procedures.

In the system, each of the radio access systems 101, 103, 105 comprises a number of access points 111-117 which support communications over the air interface in accordance with the air interface standards of the individual radio access system 101, 103, 105. The access points 111-117 may for example include wireless IEEE 802.lln access points 111, 113 of the first radio access system 101, Node Bs (base stations) 115 of the second radio access system 103 and wireless WiMAXTM access points 117 of the third radio access system 105. Indeed the access points 111-117 may be any functional entity allowing a user equipment to access any of the radio access systems.

In order to facilitate the reconfigurability and adaptation of the user equipment 109, cognitive data is transmitted by the infrastructure of the communication system and the user equipment 109 uses this cognitive data to configure the capability and/or operation for the current conditions.

Specifically, the cognitive data is access data which provides information that may assist, restrict or control the access of the different radio access systems 101, 103, 105 by the user equipment 109. In the system the decision of which radio access system to access is performed by the individual user equipment based on distributed decision making assisted by the access data.

In the example, the broadcast access data comprises three different elements (but it will be appreciated that in other embodiments the access data may comprise other access data or may only comprise one or some of the described types of access data) * Context Data. This data element provides information of which access systems are available in the given region as well as characteristics of these systems.

The characteristics may for example indicate a current loading of the system, a cost of access, which communication services are available, the Quality of Service that can be provided by the individual services etc. * Resource Usage Constraint Data. This data provides a number of constraints on the resource allocation and requests that can be made by the user equipment 109 for each radio access system. Specifically, the resource usage constraint data can include a set of resource policies for each communication system that provides restrictions on the amount of resource that can be used. This data allows distributed resource management by the user equipments and thus reduces or eliminates the need for a centralised resource controller performing common resource management for all radio access systems.

* Reconfiguration Data. This data may provide configuration settings and/or data that allows the configurable user equipments to reconfigure themselves to provide the functionality required to access the selected radio access system(s) . The data may e.g. be generic reconfiguration information, for example represented by a generic reconfiguration language. As another example, the data may be vendor specific data and may specifically be software or firmware executable code that may be executed by a software definable radio element of a user equipment.

In the system of FIG. 1, the cognitive! access data is distributed and multiplexed over a plurality of different pilot signals and logical communication channels. In particular, the system comprises a pilot signal unit 119 which transmits a pilot signal which is independent of the radio access systems 101, 103, 105.

Specifically, the independent pilot signal is a pilot signal which is dedicated to only transmit access data. Also, the independent! dedicated pilot signal is not part of any of the radio access systems 101, 103, 105 but is transmitted on a dedicated pilot signal carrier on which no user data or communication service is supported. Indeed, in the example the pilot signal is a downlink only signal on which no other time varying data than the access data is transmitted. The dedicated pilot signal is a PHYsical (PHY) layer signal which is transmitted in accordance with a suitable PHY layer standard. Thus, the pilot signal is a dedicated physical channel on which access data is transmitted.

Furthermore, the pilot signal is not transmitted in the entire coverage area of the communication system but is only transmitted in smaller reqions!islands of coverage. FIG.1 may be considered to illustrate a hybrid heterogeneous cell of the heterogeneous communication system and the pilot signal may be transmitted to cover the entire hybrid cell while at the same time no pilot signal is transmitted in other hybrid cells. As another example, the pilot signal may be transmitted at a power level allowing it to only be received in part of the coverage area. Thus, in the system, the pilot signal is an optional signal which need not be transmitted throughout the system but rather may be gradually or partially deployed thereby reducing the cost and the complexity of providing a dedicated pilot signal carrying access information supporting configurable user equipments.

In addition to the access data being transmitted on the dedicated pilot signal, the system comprises functionality for at least one of the radio access systems 101, 103, 105 transmitting a communication channel comprising access data.

The communication channel is in the specific example a logical channel which specifically is a broadcast channel.

The broadcast channel is a broadcast channel of the given radio access system 101, 103, 105 and follows the Technical Specifications! Standards of the specific radio access system 101, 103, 105. In the example, the broadcast channel carrying the access data is a logical broadcast channel of the radio access system 101, 103, 105 and the access data can be generated at the network layer and transmitted on the broadcast channel using the standard procedures/applications of the lower layers. Thus, the access data can be broadcast by a standard broadcast channel of the individual radio access system 101, 103, 105 and this broadcast can thus be achieved with little or no added complexity or cost and in particular does not require any deployment of additional equipment.

Thus, in the system access data is also transmitted on at least a communication channel which is a logical channel of one of the radio access systems 101, 103, 105. Thus, access data is also conveyed by an existing radio access system 101, 103, 105 which is used for user data exchange. Thus, a communication channel is provided which in the example is a logical link on top of data exchange channels of the radio access systems 101, 103, 105.

This is in contrast to the pilot signal which is independent of the radio access systems 101, 103, 105 and which in the specific example is part of a subsystem that cannot provide user data communication.

The access data broadcast by the logical broadcast channel may be provided by a network operator. As another example, it may be provided by a 3 party service provider (or any other entity) independent of operators and may be provided across operator domains.

The access data to be transmitted to assist the configurable user equipments is distributed and transmitted over these parallel broadcast means. Furthermore, the access data transmitted by the different broadcast means is not identical. Specifically, the access data transmitted on the dedicated pilot signal comprises first access data for a first radio access system 101 which broadcasts access data on a broadcast channel. The first access data allows the user equipment 109 to reconfigure itself such that it can access the first radio access system 101 and specifically such that it can receive the logical broadcast channel of the first radio access system 101. The first access data furthermore comprises a pointer to the first broadcast channel thereby indicating that further access data (referred to as second access data) can be retrieved from this broadcast channel. The pointer may for example be an indication of the first radio access system, of the specific broadcast channel and/or of a specific data segment or resource allocation for the second access data.

The second access data comprises access data for a second radio access system and at least some of this access data is not included in the first access data transmitted on the independent pilot signal. For example, the first radio access system 101 may comprise access data for the second radio access system 103 (corresponding to access data for the UMTS radio access system being transmitted on the IEEE 802.lln radio access system) . In the system, other broadcast channels may be transmitted by other radio access systems 101, 103, 105. For example, both the second and third radio access system 103, 105 (i.e. the UMTS and the WiMAXTM communication system may carry broadcast channels comprising access information for themselves and/or other radio access systems) In the system of FIG. 2, only a small amount of access data is transmitted on the independent pilot signal.

Specifically, the pilot signal comprises a small amount of context information for each available radio access system 101, 103, 105 (e.g. simply identifying the radio access systems 101, 103, 105 present) but does not carry any resource constraint data. Furthermore, the pilot signal comprises only user equipment reconfiguration data for a single radio access system, namely the first radio access system 101 (the IEEE 802.lln radio access system) . This reduces the dedicated resource required for the pilot signal (e.g. it may reduce the required bandwidth) while providing sufficient information to allow an efficient adaptation of, and access determination by, the user equipment 109.

In the example, the second access data may also comprise all the information transmitted by the pilot signal (possibly with the exception of some or all of the reconfiguration data for the first radio access system itself) . In addition, it may comprise further user recc. figuration data including reconfiguration data for at least one other radio access system. E.g. the broadcast channel of the first radio access system 101 can include user equipment reconfiguration data required for accessing the second radio access system 103 (and possibly also for accessing the third radio access system 105) Also, the second access data comprises resource usage constraint data thereby facilitating! enabling efficient resource management by the user equipments.

Thus, the second access data is in the example a significantly larger amount of data than the first access data and thus requires more resource to be transmitted.

However, this resource is part of the resource allocated to the first radio access system 101 and may be dynamically maintained and controlled. E.g. the resource usage affects only the first radio access system 101 and is not a dedicated resource affecting all radio access systems (as well as potentially other systems) The distribution of the access data across different broadcast means provides for a flexible and efficient system with different advantages in different scenarios.

In the heterogeneous communication system a logical access data broadcast channel exists any time and anywhere (provided by at least one local radio access system) and a dedicated physical pilot signal carrying access data exists in some areas but the presence of this pilot signal is not guaranteed and cannot be relied on by the user equipment 109.

A physical access data channel on the dedicated pilot signal provides user equipments with a quick and easy means of obtaining access data. It specifically avoids that the user equipment 109 needs to scan through a set of radio access systems to determine which radio access systems are present in the current location. Rather, the user equipment 109 can simply access the known pilot signal to retrieve the access data. It can immediately reconfigure itself to the first radio access system (if required) and then access the broadcast channel of this system. The approach may enable/facilitate the user device adapting to a completely unknown environment.

The logical access data channel(s) is(are) carried by one or more of the radio access systems 101, 103, 105 without any requirement for any additional equipment deployment.

The additional access data broadcast by the individual radio access systems 101, 103, 105 can quickly be recovered by the user equipment 109 based on the access data transmitted on the independent pilot signal.

Furthermore, in areas where the independent pilot signal is not present, the user equipment 109 can use the access data broadcast by the radio access system(s) to adapt and configure to the local and current conditions.

Specifically, the user equipment may first attempt to detect the presence of a dedicated pilot signal based on the known (standardised) characteristics of this signal (e.g. frequency, modulation scheme, error correcting code etc) . If it is not successful it proceeds to scan for any existing radio access systems which it is capable of receiving. If one is detected, it monitors the broadcas t channels to detect access data. It then proceeds to select which radio access system(s) to use and to reconfigure itself based on this (these systems) Thus, the user equipment 109 uses two different approaches to access the radio access systems 101, 103, depending on whether a dedicated pilot signal is detected. If the pilot signal is present, it may quickly access the pilot signal, then the radio access system indicated in the access data of the pilot signal, and based on the access data retrieved from this radio access system it can proceed to select and reconfigure itself for the most appropriate radio access system.

FIG. 2 illustrates an example of the user equipment 109 in more detail. The user equipment 109 comprises a transceiver 201 which is capable of receiving and transmitting radio communications. The transceiver 201 is a configurable transceiver which can be reconfigured for different radio access technologies, e.g. in response to new firmware code and/or configuration data in a standard configuration language.

The transceiver 201 is coupled to a pilot signal processor 203 which initially detects if the pilot signal can be received. This operation is very simple and can be performed quickly as all characteristics of the pilot signal (frequency, modulation scheme, data rate etc) are standardised and thus known to the user equipment 109. If the pilot signal is detected, the pilot signal processor 203 proceeds to receive the first access data transmitted by the pilot signal. This data is then fed to an access processor 205 which proceeds to select one or more of the radio access systems 101, 103, 105 in response to the received access data. Specifically, the access process involves the access processor 205 configuring the transceiver for the first radio access system 101 in response to configuration data for this radio access system comprised in the first access data. It then retrieves the second access data from the logical broadcast channel of the first radio access system 101 in response to the pointer in the first access data and potentially uses this data to select or access another radio access system. For example, it may use configuration data for the second radio access system 103 comprised in the second access data.

If the pilot signal is not detected, the access processor 205 instructs an access system scan processor 207 to perform a scan for radio access systems. The user equipment 109 will comprise a set of access systems for which it stores configuration data that allows it to receive transmissions from these access systems. For example, the user equipment 109 can comprise configuration data for WiMAXTM and IEEE 802.lln systems (but e.g. not foi UMTS) . The access system scan processor 207 then sequentially configures itself for one of these predetermined access systems and monitors whether a corresponding system is present in the current location.

When a system is detected, the access system scan processor 207 receives the access data transmitted on a logical broadcast channel of the radio access system.

This data is then fed to the access processor 205 which uses it to select a radio access system and to configure the transceiver 201 to access the selected radio access system. For example, when scanning, the access system scan processor 207 may detect the first radio access system (101) (i.e. the IEEE 802.lln system) and receive the second access data from the transmitted logical access data channel. It may then feed this data to the access processor 205 which may select the second radio access system 103 and accordingly configure the transceiver 201 for UNTS.

Thus, the system allows the user equipment 109 to benefit from the presence of a dedicated pilot signal such that selection and access to one or more specific radio access systems can be achieved quickly and efficiently. At the same time, the user equipment 109 is not reliant on the presence of the dedicated pilot signal but can perform selection of, and reconfiguration for, one or more specific radio access systems based on access data transmitted by the individual radio access systems.

As a specific example compatible with FIG.l, a heterogeneous cell is assumed to include the following radio access systems: two IEEE 802.lln access points, 1 WIMAX access point and 1 UMTS access point. A dedicated PHY channel is present on a dedicated pilot signal and broadcasts data relating to: i) The presence of these systems.

ii) Reconfiguration data which allows a user equipment to reconfigure itself to the IEEE 802.lln standard (the reconfiguration data amount required for the IEEE 802.lln PHY and MAC layer is typically less than the corresponding WIMAXTM and UMTS/CDMA data) iii) A pointer to a higher-data-rate logical access data channel broadcast by the IEEE 802. lln access point. This access data will include data that will assist a user equipment to connect to the WIMAXTM and UMTS radio access systems.

The user equipment 109 may not be able to receive or configure itself to any of the radio access systems when arriving in the heterogeneous cell. However, it may proceed with the following approach: i) The user equipment 109 initially accesses the dedicated physical pilot signal and recovers the context information and (generic) reconfiguration information thereby enabling it to be reconfigured for access to the IEEE 802.lln access points. At the same time, the user equipment 109 recovers pointers indicating the availability of further access data in the IEEE 802.lln broadcast channels.

ii) The user equipment 109 reconfigures itself to IEEE 802.lln and connects to both IEEE 802.lln Access Points (in parallel or sequentially) . In the example, the first IEEE 802.lln access point is assumed to transmit the WiMAXTM reconfiguration data and the second broadcast channel is assumed to transmit the UNTS reconfiguration data.

iii) The user retrieves the reconfiguration information for the WiMAXTM and UMTS standards from the IEEE 802.lln Access Points.

iv) The user equipment 109 derives an optimum strategy of resource usage (e.g. using one or two IEEE 802.lln access points in parallel to a WiMAXTM and/or UMTS access point) and configures itself accordingly.

v) The user equipment 109 accesses the selected access points using the appropriate configuration/ communication standard.

In the example, the presence of the dedicated physical pilot signal is optional. I.e., if the user equipment 109 is not able to receive a pilot signal, it proceeds to find available radio access systems allowing it to receive access data therefrom. Accordingly, the user equipment 109 comprises sufficient functionality for receiving at least one of the available radio access systems. This allows it to be provided with access data which can include reconfiguration information for other radio access systems.

In the system of FIG. 2, the access data is not only distributed between the radio access systems 101, 103, 105 and a physical dedicated pilot signal independent of the radio access systems 101, 103, 105 but is also distributed between the radio access systems 101, 103, 105 themselves.

Thus, the access data is multiplexed over a plurality of radio access systems 101, 103, 105 with at least some of the radio access systems 101, 103, 105 broadcasting different access data.

For example, in the system the second radio access system 103 may also transmit a broadcast channel comprising access data. However, this access data is not identical to the first access data transmitted on the dedicated pilot signal or to the second access data transmitted by the first radio access system 101. Rather the broadcast of the second radio access system 103 can transmit third access data which may comprise access data for another radio access system where at least some of the third access data is not comprised in the first or second access data.

For example, the pilot signal can comprise reconfiguration data for only the first radio access system 101, the first radio access system 101 can transmit access data comprising reconfiguration data for only the second radio access system 101 and the second radio access system 103 can transmit access data comprising reconfiguration data for the third radio access system 105. The third radio access system 105 may e.g. comprise configuration data for the first radio access system 101. Thus, the reconfiguration access data is distributed over the different radio access systems 101, 103, 105 thereby reducing the associated loading of each radio access system.

The access data transmitted by each of the radio access systems 101, 103, 105 may furthermore comprise pointers to one or more of the broadcast channels of the other radio access systems 101, 103, 105. For example, the second access data transmitted by the first radio access system 101 can comprise a pointer to the broadcast channel of the second and third radio access systems 103, 105, the second access data transmitted by the second radio access system 103 can comprise a pointer to the broadcast channel of the first and third radio access systems 101, 105 etc. Thus, the system provides a distributed transmission of access data by multiplexing this over a plurality of broadcast channels of different radio access systems 101, 103, 105. Some access data, such as the context data indicating which systems are present, can be transmitted by all radio access systems 101, 103, 105 whereas other data, such as the configuration data, is only transmitted on a subset of the radio access systems 101, 103, 105.

Furthermore, the access data transmitted on a radio access system comprises pointers or references to the access data of the other radio access systems 101, 103, 105. This system provides an efficient and flexible access process. For example, in the absence of a dedicated pilot signal, a user equipment may upon detecting one radio access system be provided with information of all available systems as well as a direct pointer to, and configuration data for, a broadcast channel for each access system the user equipment may select.

Furthermore, a very low data rate dedicated pilot signal is achieved which may be deployed in an ad-hoc manner and specifically may be gradually or partly rolled out. In the presence of such a pilot signal a facilitated access process can be achieved as no scanning for access systems is required (and indeed no capability of accessing any radio access system is required) . For example, an access of the second radio access system 103 may comprise the user equipment 109 initially receiving the first access data and in response selecting the second radio access system 103 and reconfiguring for the first radio access system 101. In response to the pointer of the first access data, it then retrieves the second access data from the broadcast channel of the first radio access system 101. This data comprises the reconfiguration data and pointer for the second radio access system 103. It then proceeds to reconfigure for the second radio access system 103, receive the access data broadcast by the second radio access system 103, and finally it proceeds to access the second radio access system 103.

In some embodiments, the first access data may comprise a plurality of pointers. For example, it may comprise a pointer to the broadcast channels of both the first and second radio access systems 101, 103. This may facilitate access in many scenarios.

It will be appreciated that the described principles may also apply to a distribution of access data over a plurality of access points of the same radio access system. For example, the first radio access system 101 can comprise two access points 111, 113 transmitting different access data.

E.g. the first access point 111 can transmit configuration data for only the second radio access system 103 whereas the second access point 113 can transmit configuration data for only the third radio access system 105.

In such an example, the first access data can comprise a pointer to both access points thereby allowing the user equipment 109 to access both of these (or to select the access point carrying the desired reconfiguration data).

An example of the transmitted access channels for such a scenario is illustrated in FIG. 3 wherein one IEEE 802.lln access point carries reconfiguration data for WiMAXTM whereas another 802.lln access point carries reconfiguration data for UMTS (CDMA). The dedicated pilot signal carries a Cognitive Pilot Channel (CPC) providing a pointer to both reconfiguration data segments.

In the example, the access data channels provided by the radio access system is time multiplexed with user data channels on a shared carrier. Thus, the radio access system provides a logical access data channel by sharing an existing carrier with other logical channels which in this case includes user channels. This allows a highly efficient transmission of access data while allowing the existing solutions and functionality of the individual radio access system to be used. It thus provides an easy and flexible

introduction of the access data transmission.

In the system of FIG. 1, the distribution of the access data is jointly managed by a centralised access data controller 121 coupled to the interconnecting network 107. The access data controller 121 jointly manages not only what access data is transmitted on the broadcast channels of the individual radio access systems 101, 103, 105 but in the example also what access data is transmitted by the independent pilot signal.

FIG. 4 illustrates the access data controller 121 in more detail.

The access data controller 121 comprises a network interface 401 which interfaces the access data controller 121 to the interconnecting network 107 and through this couples the access data controller 121 to the pilot signal unit 119 and the appropriate functionality of the radio access systems 101, 103, 105.

The network interface 401 comprises an access data receiver 403 which receives access data for (and possibly from) a plurality of the radio access systems 101, 103, 105 (and specifically from all the radio access systems 101, 103, 105) . The received access data from each radio access system 101, 103, 105 can comprise information required or desired for a user equipment accessing the system. As such it can comprise context data (e.g. characteristics of the system such as an identification, supported communication services etc), resource constraint information providing constraints on the resource that may be used by the user equipment (e.g. a maximum data rate or a maximum transmit power) and reconfiguration data for the radio access system.

Thus, in the system, each of the radio access systems 101, 103, 105 comprises functionality for gathering and transmitting access data to the access data receiver 403.

This may for example be achieved by the access data being manually generated and entered into suitable network equipment by an operator. The network equipment (e.g. an Operations and Management Centre) may then transmit the access data to the access data receiver 403.

The access data receiver 403 is coupled to an access data set processor 405 which receives the received access data from the different radio access systems 101, 103, 105. The access data set processor 405 determines a plurality of non-identical access data sets where one set is to be transmitted by the pilot signal and each of the other sets is to be transmitted by one of the radio access systems 101, 103, 105.

The access data sets will typically comprise some shared information and some non-shared information but will not be identical (at least two access sets will be non-identical although some identical sets could be used by other radio access systems 101, 103, 105) . In the specific example, the context data for all radio access systems 101, 103, 105 are included in all the access data sets such that information of which access systems are available will be provided to the user equipment 109 regardless of which access data transmission is received.

In the example, at least one of the access data sets comprises access data which is not included in any other of the non-identical access data sets. For example, the reconfiguration data for the second radio access system 103 may only be included in the access data set for the first radio access system 101 but not in the sets for the pilot signal or the third radio access system 105.

The access data set processor 405 is coupled to an access data distribution processor 407 which receives the access data sets for the radio access systems 101, 103, 105. The access data distribution processor 407 is coupled to the network interface 401 through which it transmits each of the access data sets to the corresponding radio access system 101, 103, 105. When received by the radio access system 101, 103, 105, the access data set is repeatedly transmitted on the appropriate broadcast channel using the standard functionality of the radio access systems 101, 103, 105 for transmitting broadcast channels.

The access data set processor 405 is furthermore coupled to a pilot signal access data processor 409 which receives the access data set for the pilot signal. The pilot signal access data processor 409 is coupled to the network interface 401 through which it transmits the access data set to the pilot signal unit 119 for transmission on the dedicated pilot signal.

It will be appreciated that the access data transmitted by the pilot signal or a single radio access system! access data point may comprise access data and specifically reconfiguration data for more than one radio access system.

FIG. 5 illustrates a method of operation for a heterogeneous communication system including a plurality of radio access systems.

In step 501 a pilot signal is transmitted in only part of the coverage area of the communication system. The pilot signal is independent of the radio access systems and comprises first access data for at least a first radio access system.

In step 503 a first broadcast channel comprising second access data for at least a second radio access system is transmitted. At least some of the second access data for the second radio access system is not included in the first access data.

The first access data comprises a pointer to the first broadcast channel.

It will be appreciated that although FIG. 5 shows steps 501 and 503 to be sequential and iterated it will be appreciated that the steps 501, 503 may be performed in parallel and continuously.

It will be appreciated that the above description for clarity has described embodiments of the invention with reference to different functional units and processors.

However, it will be apparent that any suitable distribution of functionality between different functional units or processors may be used without detracting from the invention. For example, functionality illustrated to be performed by separate processors or controllers may be performed by the same processor or controllers. Hence, references to specific functional units are only to be seen as references to suitable means for providing the described functionality rather than indicative of a strict logical or physical structure or organization.

The invention can be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may optionally be implemented at least partly as computer software running on one or more data processors and/or digital signal processors. The elements and components of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the invention may be implemented in a single unit or may be physically and functionally distributed between different units and processors.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term comprising does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Also the inclusion of a feature in one category of claims does not imply a limitation to this category but rather indicates that the feature is equally applicable to other claim categories as appropriate. Furthermore, the order of features in the claims does not imply any specific order in which the features must be worked and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order.

Claims

1. A heterogeneous communication system comprising a plurality of radio access systems, the system comprising: broadcast means for transmitting a pilot signal in only part of the coverage area of the communication system, the pilot signal being independent of the radio access systems and comprising first access data for at least a first radio access system; and a first radio access system comprising means for transmitting a first communication channel comprising second access data for at least a second radio access system, at least some of the second access data for the second radio access system not being included in the first access data; and wherein the first access data comprises a pointer to the first communication channel.

2. The heterogeneous communication system of claim 1 comprising a configurable user equipment, the configurable user equipment comprising: means for determining if the second pilot signal can be received; first means for, if the pilot signal can be received, receiving the first access data and selecting a radio access system in response to the first access data; second means for, if the pilot signal cannot be received, scanning for a radio access system of a predetermined set of radio access systems and selecting a radio access system in response to access data of a detected radio access system of the predetermined set, the predetermined set comprising radio access systems for which communication channels are receivable by the configurable user equipment.

3. The heterogeneous communication system of claim 2 wherein the first means is arranged to receive the second access data in response to the pointer and to reconfigure the configurable user equipment for the second radio access system in response to user equipment configuration data of the second access data.

4. The heterogeneous communication system of claim 1 wherein the first access data comprises context data identifying a set of radio access systems available in a region and user equipment configuration data for at least the first radio access system.

5. The heterogeneous communication system of claim 4 wherein the first access data comprises user equipment reconfiguration data only for the first radio access system.

6. The heterogeneous communication system of claim 1 wherein the second access data comprises user equipment reconfiguration data for the second radio access system which is not comprised in the first access data.

7. The heterogeneous communication system of claim 1 wherein the second access data comprises resource allocation constraint data which is not comprised in the first access data; and user equipments of the heterogeneous communication system are arranged to request resource in response to the resource allocation constraint data.

8. The heterogeneous communication system of claim 1 further comprising: a second radio access system comprising means for transmitting a second communication channel comprising third access data for at least a third radio access system, at least some of the third access data for the third radio access system not being included in either of the first access data and the second access data.

9. The heterogeneous communication system of claim 8 wherein the first access data further comprises a pointer to the second communication channel.

10. The heterogeneous communication system of claim 8 wherein the second access data further comprises a pointer to the second communication channel.

11. The heterogeneous communication system of claim 1 wherein the first radio access system comprises a first access point arranged to transmit the second access data and a second access point arranged to transmit third access data for at least a third radio access system, at least some of the third access data for the second radio access system not being included in either of the first access data and the second access data.

12. The heterogeneous communication system of claim 1 further comprising access data management means comprising: means for receiving access data for a plurality of the radio access systems; means for determining non-identical access data sets to be transmitted by different radio access systems in response to the received access data; means for distributing the non-identical access data sets to the different radio access systems; and wherein each of the different radio access systems comprises means for broadcasting the access data set allocated to the radio access system.

13. The heterogeneous communication system of claim 12 wherein access data management means further comprises means for determining an access data set to be transmitted by the pilot signal in response to the received access data.

14. The heterogeneous communication system of claim 12 wherein at least one of the non-identical access data sets comprises access data for a radio access system not comprised in any other of the non-identical access data sets.

15. The heterogeneous communication system of claim 12 wherein at least two of the non-identical access data sets comprises some common access data.

16. The heterogeneous communication system of claim 12 wherein at least some of the radio access systems comprises means for transmitting access data to the access data management means. -

17. The heterogeneous communication system of claim 1 wherein the broadcast means is arranged to transmit the pilot signal on a dedicated pilot signal carrier and the first communicatIon channel is a logical channel transmitted on a shared carrier shared with other logical channels.

18. The heterogeneous communication system of claim 16 wherein the first communication channel is time multiplexed with user data channels on the shared carrier.

19. The heterogeneous communication system of claim 1 arranged to transmit a lower amount of access data on the first pilot signal than on the first communication channel.

20. A method of operation for a heterogeneous communication system including a plurality of radio access systems, the method comprising: transmitting a pilot signal in only part of the coverage area of the communication system, the pilot signal being independent of the radio access systems and comprising first access data for at least a first radio access system, and transmitting a first communication channel comprising second access data for at least a second radio access system, at least some of the second access data for the second radio access system not being included in the first access data; and wherein the first access data comprises a pointer to the first communication channel.