EP2241132A2

EP2241132A2 - Telecommunication method

Info

Publication number: EP2241132A2
Application number: EP08866155A
Authority: EP
Inventors: Dongyan Wang; Haïla WANG; Daquig Gu
Original assignee: France Telecom SA
Current assignee: Orange SA
Priority date: 2007-12-29
Filing date: 2008-12-29
Publication date: 2010-10-20
Also published as: WO2009083938A2; WO2009083938A3; WO2009083938A8

Abstract

A method for a mobile user equipment to seamlessly receive broadcast services available from a télécommunication network and a broadcast network while leaving a télécommunication network and being within the coverage of a broadcast network, said method comprising the acts of synchronizing the broadcast services received from the broadcast network with the broadcast services received from the télécommunication network when the user equipment measures one or more network level(s) that fulfils network switching criteria; and switching from the broadcast services received from the télécommunication network to the broadcast services received from the broadcast network.

Description

TELECOMMUNICATION METHOD

Field of the Invention

The present invention relates in general to a telecommunication system operable to enable handovers for mobile user equipments between DVB-H and UMTS networks.

Background of the Invention

One of the challenges that wireless industry faces today is to provide affordable mass multimedia services to mobile phones. Although 3G cellular networks have already started to deliver multimedia services based on streaming, as video clips from sport events or TV programs, their offers are still limited due to the inefficiency of the current unicast point-to-point (p-t-p) architecture in transmitting the same content to a large number of users. This limits the maximum number of users such systems can handle and prevents mass-market deployment, as both radio and transport network resources are physically limited. As an alternative to the 3G cellular networks, the technology DVB-H (Digital Video Broadcast - Handheld) is considered as a key element in future wireless networks, due to its capabilities to provide mass mobile multimedia services. DVB-H is an extension of the European terrestrial digital TV standard DVB-T (Digital Video Broadcast - Terrestrial), to reach handheld terminals or user equipments (UEs) devices. DVB-H reuses the same physical layer as DVB-T, and adds new features at the link layer, being able to share the same network infrastructure (e.g., transmitters, multiplexes, etc.). One of the major concerns of DVB-H networks is the cost of infrastructure deployment, which could lead to a price for service that is unaffordable for most users. This concern is very justified if the dimensioning of the network infrastructure is performed to support real-time streaming services and nearly full area coverage, as in traditional broadcasting. As DVB-H terminals suffer from more severe propagation conditions than DVB-T (especially for indoor and vehicular reception), reusing existing broadcasting towers for TV and radio is not enough to achieve a satisfactory DVB-H coverage. A large number of sites are then required to deploy additional DVB-H transmitters or repeaters (gap fillers, and forming dense Single Frequency Networks (SFNs), which implies a larger investment in infrastructure. This penalty is particularly evident for high coverage area targets (e.g., over 90 percent of service area locations). Further, for DVB-H network, Multi-Frequency Network (MFN) rather than SFN is required to supply the location based broadcasting service. That means more spectrum resources are required for the delivering location based broadcasting services.

To deliver multimedia content efficiently through point-to-multipoint (p- t-m) transmissions in a cell, the 3G standard was enhanced with Multimedia Broadcast Multicast Services (MBMS). The enhancement of MBMS in both Universal Mobile Telecommunication System (UMTS) Low Chip Rate Time Division Duplex (LCR TDD) and UMTS High Chip Rate Time Division Duplex (HCR TDD) technologies in the standard 3GPP Release 7 shows promising broadcast capability with configurable numbers of time slots in a frame. This scheme makes it possible to supply a few p-to-m broadcast channels to the users during the initial launch of the mobile TV services with lower cost, as no new network construction is needed for supplying the mobile TV services. Nevertheless, MBMS offers limited capacity (approximately 192~320kb/s per time slots), and gaps are needed between different MBMS broadcast clusters to reduce the adjacent cluster interference, thus it is unlikely that it will become a good option for mass multimedia services alone.

The above analysis shows that neither DVB-H or MBMS alone could offer cost efficient location based broadcast in a cost efficient way. To supply location based broadcast coverage, the convergence of DVB-H and UMTS TDD MBMS network is needed.

In the previous literature, DVB-H enables the convergence of services from broadcast and cellular domains, allowing mobile broadcast interactive services with cellular unicast channel. The convergence of DVB-H and cellular network also makes it possible to recover lost information in DVB-H session through the bidirectional cellular path.

Today there is a need for a convergence solution that can be easily implemented on the existing telecommunication infrastructures. Summary of Invention

It is an object of the present system to overcome disadvantages and/or make improvement over the prior art. To that extend, the invention proposes a telecommunication method for a mobile user equipment to seamlessly receive broadcast services available from a telecommunication network and a broadcast network while leaving a telecommunication network and being within the coverage of a broadcast network according to claims 1 to 5. The invention also proposes a telecommunication method for a mobile user equipment to seamlessly receive broadcast services available from a telecommunication network and a broadcast network while leaving a broadcast network and being within the coverage of a telecommunication network according to claims 6 to 10. The invention also relates to a telecommunication system for a mobile user equipment to seamlessly receive broadcast services available from a telecommunication network and a broadcast network while leaving a telecommunication network and being within the coverage of a broadcast network according to claims 1 1 to 15. The invention also relates to a telecommunication system for a mobile user equipment to seamlessly receive broadcast services available from a telecommunication network and a broadcast network while leaving a broadcast network and being within the coverage of a telecommunication network according to claims 16 to 20. The invention also relates to a mobile user equipment to seamlessly receive broadcast services available from a telecommunication network and a broadcast network while leaving a telecommunication network and being within the coverage of a broadcast network according to claims 21 to 25.

The invention also relates to a mobile user equipment to seamlessly receive broadcast services available from a telecommunication network and a broadcast network while leaving a broadcast network and being within the coverage of a telecommunication network according to claims 26 to 30. The invention also relates to a computer program to perform a method for a mobile user equipment to seamlessly receive broadcast services available from a telecommunication network and a broadcast network while leaving a telecommunication network and being within the coverage of a broadcast network according to claim 31.

The invention also relates to a computer program to perform a method for a mobile user equipment to seamlessly receive broadcast services available from a telecommunication network and a broadcast network while leaving a broadcast network and being within the coverage of a telecommunication network according to claim 32.

Brief Description of the Drawings

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, where like parts are provided with corresponding reference numerals, and in which:

Figure 1 schematically illustrates a hybrid cellular and broadcasting network incorporating two clusters of the cellular cells and a DVB-H cell according to an embodiment of the present invention;

Figures 2a-2b schematically illustrate a timing to process a DVB-H and MBMS monitor according to an embodiment of the present invention;

Figure 3 schematically illustrates a converged network architecture with shared media server according to an embodiment of the present invention;

Figure 4 schematically illustrates a terminal with the capability of receiving DVB-H and MBMS signal according to an embodiment of the present invention;

Figure 5 schematically illustrates a flow chart of a method for the handover process from Cellular system to DVB-H according to an embodiment of the present invention; Figure 6 schematically illustrates a flow chart of a method for the handover process from DVB-H to Cellular MBMS system according to an embodiment of the present invention. Description of Preferred Embodiments

This proposal aims at providing a new hybrid location based broadcast architecture based on terrestrial digital broadcast (such as DVB-H) and MBMS technology. Broadcast channel handover scheme between terrestrial broadcasting networks (such as DVB-H, MEDIA-FLO, DMB and etc.) and the TDD MBMS networks (such as UMTS LCR TDD, UMTS HCR TDD, and etc.). By this way, the location based mobile broadcast service is able to be supplied in a more cost efficient way.

The present invention relates to a method and system to improve the continuity of the location based broadcast network, which enable different programs broadcasted in different geographic areas, targeting the need of different users.

The present invention relates to network and cell handover procedures in hybrid wireless communications systems. More particularly, aspects of the invention are based on a hybrid terrestrial broadcast network (such as DVB-H, DMB, CMMB etc.) and cellular MBMS network architecture. A new broadcast channel handover procedure between the terrestrial broadcast network (such as DVB-H, DMB, CMMB, etc.) and cellular MBMS network are proposed. The content synchronization scheme between MBMS network and terrestrial broadcast network are proposed.

The Multimedia Broadcast/Multicast Service (MBMS) technical specification defines mobile multimedia services over 3G cellular networks.

MBMS represents a way for 3G network operators to offer multimedia content over their GPRS/EDGE or UMTS networks without unnecessarily consuming capacity for voice communications. MBMS multimedia content is delivered via IP packets; either as a streaming service or as a file downloads service to the end user. It is a unidirectional point-to-multipoint service in which data is transmitted from a single source entity to a group of users in a specific area. With MBMS, the same content is transmitted to multiple users in a unidirectional fashion, typically by multiple cells in order to cover the large area in which the service is provided.

UMTS TDD (TD-SCDMA and TD-CDMA) base stations are inherently synchronized, as required for a TDD air interface. Generally speaking, GPS (Global Positioning System) receivers are included in the base station of the UMTS TDD (LCR and HCR) for this purpose. For MBMS broadcast over UMTS TDD (LCR and HCR), the content is synchronized on all base stations in a service area. Actually the new enhancement of UMTS TDD MBMS is composed a synchronised, single frequency broadcast network, therefore mobile devices can combine signals from a cluster of cells and thus the signal is re-enforced, neighbouring cells do not interfere, a higher C/l gains can be achieved. More specifically, the service can be delivered based on one or several time slots of one or a group of carriers of the cellular network, thus both broadcast and the unicast services will be provided on the same group of carriers.

Whereas DVB-H is backward compatible with DVB-T, the use of time slicing results in off-periods in DVB-H, which makes the adjacent cell monitor possible in the off-period of DVB-H. In DVB-H system, handover can occur within MFN networks, between two different SFN areas that are part of the same network. However, It is quite difficult to support location based broadcast with MFN due to apparent higher spectrum requirement and indoor coverage investment.

Considering the need of affordable mass multi-media broadcast service as well as the cost efficient location based broadcast. There is a great need to build up new network architecture. This proposal proposed a hybrid terrestrial broadcast and cellular MBMS network architecture, with aim to meet the affordable and location based broadcast requirement. Based on the new network architecture, the related broadcast channel handover aspects and the content synchronization aspects are in the focus of the proposal. This solution should lead to lower deployment costs, higher coverage, higher practical spectrum efficiency and improved location based broadcast service realization.

With cellular MBMS broadcast sites being a good complement to terrestrial broadcasting towers, especially for indoor reception planning, a cost-efficient hybrid DVB-H and cellular MBMS deployment could be achieved even if high coverage and capacity levels are targeted. Efforts should be focused mostly on implementing adaptive applications based on geographic area with unified broadcast content source server.

According to the present method and system, an implementation of a DVB-H and cellular hybrid network is proposed. Said hybrid broadcast network is composed of several cellular cells and DVB-H cells, the DVB-H cells are assumed (as it generally the case) to be larger than cellular cells. Inside the DVB-H coverage, there are some clusters of cellular cells, one cluster is generally composed of several continuous cells, all the cells share the same cell ID inside a cluster, the same content is broadcasted synchronously in a cluster. The signals from different cells of a cluster can be combined in the receiver to get a higher broadcast gain. This way, different contents may be broadcasted into different clusters. To eliminate inter- cluster interferences, there should be some distance between the different clusters. The apparent drawback comes from the discontinuous broadcast when user equipments move from one location to another location. When users move away from a cluster, they may be able to receive the DVB-H broadcast service in order to continue the broadcast service by a broadcast channel handover scheme. Generally, cellular cells clusters are used to cover areas such as e.g. densely populated areas, commercial centers, office buildings, kindergartens, campus, hospitals, hotels, traffic route, entertainment centers etc... which generally need a good indoor coverage and a diversity of the message broadcast, such as emergence notification and location based advertisements. A gap is needed between these different clusters to prevent inter-cluster interferences. By combining the advantage of existing mobile indoor coverages and outdoor DVB-H coverage, the location based mobile broadcast may be realized in a spectrum efficient way without looking for more frequency to construct a MFN. Using cellular MBMS broadcast channels for location based broadcast services bear on two advantages: - cellular broadcast channels complement the DVB-H for indoor coverage thanks to the better indoor coverage of cellular network;

- localized content may be broadcasted cluster by cluster with no requirement of extra spectrum for building DVB-H MFN (multi-frequency network) network.

In an exemplary embodiment according to the present method and system, Figure 1 describes cellular UMTS and DVB-H networks coverage. DVB-H coverage is generated by a DVB-H transmitter 100. Inside the DVB-H coverage, there are two clusters C1 and C2 composed of cellular cells. Cluster C1 is composed of UMTS TDD LCR cells 101 , 102 and 103. Cluster C2 is composed of UMTS TDD LCR cells 201 , 202, 203. Different dedicated information may be broadcasted in cluster C1 and C2. For instance, instructions may be broadcasted to some clusters during emergency events, such as e.g. fire or traffic jam, in the related area. The terminals or user equipments (UEs) 1 a, 2a and 3a may receive both UMTS TDD LCR MBMS broadcast signals and terrestrial broadcast DVB-H signals. Terminal or UE 1 a is within the coverage of cluster C1 and may only receive broadcast signals from cluster C1 and DVB-H (if DVB-H signal is strong enough), but the terminal 1 a is not able to receive the broadcast services from the cluster C2. Terminal 2a is within the coverage of cluster C2 and may only receive broadcast signals from C2 and DVB-H (if DVB-H signal is strong enough), but 2a is not able to receive the broadcast service from the cluster C1. Terminal 3a is in the gap between cluster C1 and cluster C2 and within the coverage of DVB-H signals transmitted by the DVB- H transmitter 100. Terminal 3a can thus be only provided with DVB-H broadcast services.

In order to guarantee seamless mobile broadcast services, a broadcast channels handover has to be considered when a user moves from one cluster to another area. For instance, when the terminal 1 a is moving away from the area covered by the cluster C1 , it detects that the cellular signal is lower than the predetermined threshold MBMS_THD at the edge of cluster C1. The DVB-H signals monitoring is triggered thereafter. As shown in the figure 3, DVB-H signal could be monitored by DVB-H receiver 503, while MBMS signals could be received simultaneously. DVB-H signal monitor is quite different from the signal monitor in MFN, as no offtime is used in the DVB-H signal monitor. However, the "lower than MBMSJΗD" event will wakeup the DVB-H receiver.

As shown in Figure 2a, a TD-SCDMA system with enhanced MBMS, a sub-frame with a period of 5 ms is composed of 10 time slots, in which TSO, DWPTS,TS3, TS4, TS5 and TS6 are downlink time slots; and UPPTS, TS1 and TS2 are uplink time slots. TSO is used for system message broadcasting. In each sub-frame, TS3 is configured as a point-to-multicast (p-to-m) broadcasting slot, meaning that every terminal in the cluster is able to receive the same broadcasting service through TS3. The other time slots in the sub- frame can be used for voice calls or other unicast services. This gives the flexibility for the operator to configure the system with reasonable ratio of broadcasting time slots or unicast time slots. During the initial rollout of the mobile broadcast services, such as mobile TV service, the broadcast time slots are configured dynamically with the increasing need of such kind of service or diminished requirements of this service for different time and places, this is different from the current existing technology that using the fix resources used for broadcast services, which may lead to under-utilized spectrum for different scenarios. The apparent advantage of the broadcast or unicast resources configurable flexibility is that it could minimize the underutilized spectrum with best effort, thus potentially increasing the practical spectrum efficiency.

The handover measurement in DVB-H system has to be performed in the off- time as shown in Figure 2b; no off time is scheduled in the broadcast channel of the cellular MBMS system, the handover measurement can be implemented in the idle time slot of the cellular system. The scheme makes a more cost efficient handover than DVB-H handover in MFN scenarios.

Thanks to the intrinsic bidirectional capability of the UMTS LCR TDD cellular network, terminal 1 a detects that the broadcast signal from the UMTS LCR TDD cellular system, and reports the monitor results to the Radio Network Controller periodically. When the Radio network controller finds that the signal strength is lower than a predetermined threshold, it will wake up the DVB-H receiver 503 for signal monitor. DVB-H receiver 503 will receive the MPE sections for monitoring after the DVB-H synchronization process. To reduce the power consumption of the terminal, terminal can power down the DVB-H receiver when DVB-H monitor process is completed. To increase the monitor accuracy, it is necessary to define a special DVB-H monitor mode, During this mode, several MPEs of DVB-H could be monitored continuously under the control of central controller 500. The DVB-H monitor mode is different from the DVB-H working mode, as no inter-burst off time is available in the DVB-H monitor mode, however, inter-burst offtime is necessary to prolong the battery life for DVB-H work mode. The average value of DVB-H monitor results are submitted to RNC. Radio Network Controller makes the decision according to the measurement results. If RNC finds that the MBMS signal is weaker than the threshold or according to predetermined decision algorithms, it decides to switch to DVB-H, to make the seamless handover, it will transfer a HANDOVERtoDVB-H command to the terminal 1 a, 1a processes the handover process after receiving this command.

There are two modes to process the handover, one mode is seamless handover; another mode is automatic channel switch handover.

For seamless handover, the program content synchronization between the broadcast channels of DVB-H and the cellular MBMS system is required.

To avoid packet loss during the handover, the same service in adjacent cells may be sent out exactly at the same points of time. As shown in Figure 3, Mobile MBMS and DVB-H network share the same broadcast content source 300. Both MBMS network and the DVB-H network can get the synchronization from GPS. As the network delay for MBMS and DVB-H may be different, a synchronization scheme should be developed to guarantee the content synchronization of the two networks at the UE receiving side.

Pair channels should be defined for MBMS and DVB-H network to hold the same contents synchronously. Assuming two regional channels are available in Cluster C1 , C1_ch1 and C1_ch2, the counterpart pair channels in DVB-H network should be defined accordingly, channel PAIR_C1_ch1 in DVB-H network defined as pair channel with channel C1_ch1 in cluster C1 of MBMS network; Channel PAIR_C1_ch2 in DVB-H network defined as pair channel with channel C1_ch2 in cluster C2 of MBMS network.

The unified SERVICE ID should be defined for the same service that is broadcasted in MBMS network and DVB-H network.

Further more, to synchronize the content between the pair channels, a synchronization scheme should be introduced.

One embodiment is to introduce an element called SYNC-U 600 in the said system, SYNC-U 600 receives the source packet data from the Multicast and Broadcast Multimedia Source 300, and makes the synchronization preprocessing before distributing the packet data to the MBMS system and DVB-H system. SYNC-U 600 receives the reference synchronization signal, such as GPS as a reference to process the received source data from 300. The pre-processing functions in SYNC-U include:

1. Timing stamp processing: add the timing stamp information to the transmission stream data packet from the source 300. The time stamp indicates the time instant when packet has to be transmitted to the radio.

2. Propagation delay variance elimination process: the stamped data has to be sent early enough to the concerned systems, such as MBMS or DVB- H systems in this embodiment so as different systems are able to buffer the data until the radio transmission time occurs. 3. To facilitate SYNC-U 600 with knowledge of the propagation delay, on one hand, SYNC-U is able to receive the delay configuration information through the connection between SYNC-U 600 and GGSN 302. on the other hand, SYNC-U is able to receive the delay configuration from DVB-

H through the connection between SFN-Adapter 403 and SYNC-U 600.

By this way, SYNC-U is able to calculate the TA (time advance) After the pre-processing in SYNC-U, the stamped data is distributed to the corresponding systems. SYNC-MAP units can be introduced to adapt the different transmission format and transmission delay in different systems.

In UTRAN MBMS system, the stamped data is fed into MB-SC or GGSN. SYNC-MAP unit 601 is introduced in UNTRAN MBMS system to extract the synchronization timing in the data packets and calculate the CFN for the data packet. To make sure the synchronization of service data sent by each related cell, MAC-m in UTRAN configures the beginning CFN for data packets in one TTI then copy it to the Node Bs corresponding to the FACH FP channel. Based on the unified SFN frame number and identical CFN, Node Bs obtain the transmission time in radio interface, as a result, the synchronization transmission between multi cells is realized. The transmission delay for different UTRAN can be considered as usual. Optionally, the stamped data could be fed into the GGSN directly for further processing.

In DVB-H system, the stamped data packet is fed into IPE, the corresponding timing is extracted at SYNC-MAP unit 602 and fed into the SFN-adapter 403 to form the DVB-H specific timing according to different path delay.

The advantage of this scheme is that inter-GGSN synchronization can be achieved. What's more, by introducing the SYNC-MAP unit, the synchronization between MBMS and DVB-H can be achieved. This should not limit to MBMS or DVB-H system, as SYNC_MAP can be adapt to different system. Thus the content synchronization between MBMS and DVB-H can be achieved.

By this way, the service is able to be sent out simultaneously from MBMS and DVB-H modulator and transmitter 404. And the services in paired channels can be received simultaneously by the terminal 1 a. Further, specific SERVICEJD format has been defined in different systems, such as UMTS MBMS and DVB-H, there is a need to define the common SERVICEJD format for the share services to facilitate the seamless handover between different systems. Therefore, the SERVICE_ID_U is introduced in SYNC-U 600 and Multicast and Broadcast Multicast Source 300. The SERVICEJDJJ is defined as following:

SERVICEJDJJ is the unique identifier of a service within a TS globally. The format of SERVICE_ID_U is out of the scope of this patent and therefore can be defined in another literature.

During the Handover to DVB-H process, first the synchronization is setup at terminal 1 a, 1 a first checks the list of SERVICEJDJJ of the DVB-H, when the value of a SERVICEJD_U of DVB-H network is the same as that of the Cluster C1 of the MBMS network, that means the two channels are paired channels.

1 a switches to the paired channel in DVB-H network, which is with the same program as that of the cluster C1 . Thus the broadcast channel is switched from cellular MBMS system to the terrestrial broadcast channel. As the program content synchronization has been achieved between the broadcast channels of DVB-H and the cellular system in this proposal, the seamless handover can be implemented in the location based broadcasting network.

Figure 4 describes a flowchart of a seamless handover from cellular system UMTS MBMS to DVB-H is shown in figure 4.

The handover procedure starts and terminal, or UE 1 a receives in an act 420 the broadcast program through TS3, TS3 is configured as a broadcast Time Slot, which is also called C1_ch1. The SERVICEJDJJ of the channel is read out by System control 500 and stored in the memory 501 of the terminal 1 a. The quality of the broadcasting signal in TS3 is reported by the terminal 1 a periodically to RNC. In step 430, the RNC checks to find if the quality of the broadcast signal is lower than the predetermined threshold, then the RNC sends the message DVB-H_MEA to 1 a in an act 440. In an act 450, 1 a activates the integrated DVB-H receiver 503 as shown in figure 4 and synchronizes with the DVB-H system. This consists in the user equipment synchronizing the idle time slot of the UMTS network with the time-slice burst of the DVB-H network in order for the UE to be able to monitor said burst during the allocated idle time slot. The monitoring of said burst of DVB-H broadcasting allows measuring the level of the signal corresponding to the DVB-H broadcast services. While synchronized, UE 1 a receives the broadcast signal from DVB-H, calculates the Received Signal Strength Indicator (RSSI) of the received DVB-H signal and reports the measurement to RNC. In act 460, the RNC checks to find if the DVB-H measurement is greater than the threshold, then it will instruct 1 a to check the SERVICEJDJJ list of DVB-H in an act 470. When the matching SERVICEJD_U of the broadcast service is found out in DVB-H signal in an act 480, then the paired channel of C1 -Ch1 , that is Pair_C1_ch1 has been found and, in an act 490, 1a switches to the paired DVB-H channel, pair_C1_ch1 , and power down the MBMS transceiver 502.

When terminal 3a moves from the DVB-H coverage area to cluster C2, it reports the DVB-H receiving signal strength RSSI periodically to the UMTS

RNC using a DVB-H_REPORT message. The RNC sends back an MBMS-

MEA message to 3a when the reported DVB-H signal strength RSSI is lower than the threshold DVB_THD set by the operator. 3a starts measuring the

MBMS signal in slot TS3 after receiving the MBMSJvIEA command and reports the measurement results to the RNC. The RNC sends an

HANDOVER-to-MBMS message to 3a when the MBMS signal strength is greater than the MBMS_THD threshold set by the operator. Figure 6 describes a flowchart of handover execution process from DVB-H to UMTS MBMS.

The handover procedure starts and terminal 3a receives in an act 520 the broadcast program through DVB-H. The SERVICEJDJJ of the channel is read out by the system control 500 and stored in the memory 501 of the terminal 3a as shown in Figure 4. The quality of the DVB-H broadcast signal is reported by the terminal 3a periodically to the RNC when the UE is in the coverage of the UMTS network. In an act 530, the RNC checks to find if the quality of the broadcast signal is lower than the predetermined threshold DVB_THD. If so, the RNC sends the message MBMS_MEA to 3a in an act 540. In an act 550, 3a activates the integrated MBMS transceiver 502 and synchronizes with the DVB-H system. This consists in the user equipment synchronizing at least one time slot used for broadcasting MBMS broadcasted services of the UMTS network with an off-peak interval of the DVB-H network in order for the UE to be able to monitor said time slot used for broadcasting MBMS broadcasted services during the off-peak interval of the DVB-H The monitoring of said time slot used for broadcasting MBMS broadcasted services allows measuring the level of the signal corresponding to MBMS broadcasted services. Then 3a receives the broadcast signal from DVB-H, calculates the RSSI of the received MBMS signal and reports the measurement to RNC. In an act 560, the RNC checks to find if the MBMS measurement is greater than the threshold MBMS_THD. If so, it will instruct 3a to check the SERVICE_ID_U list of MBMS in an act 570. Whenever the matched SERVICE_ID_U is found out in MBMS network in an act 580, then the paired channels has been found and, in an act 590, 3a switches to the paired MBMS channel and power down the DVB-H receiver 503.

In some circumstances, pair relationship is not defined for all the channels between MBMS and DVB-H broadcast network, no identical SERVICE_ID_U is available for both networks. The seamless handover is not possible for this case. Channels with random SERVICE_ID_U could be picked for the automatic channel switch handover when the subscribers move between MBMS coverage area to DVB-H coverage area. Or optionally, some rules could be defined for automatic channel switch when subscribers move from one geographic broadcast area to another. Such as service switch table could be defined in RNC or terminal, which is stored in the memory 501 of the terminal.

Although DVB-H is taken as an example for embodiment description, the other terrestrial broadcast technologies such as DVB-T, T-DMB, MedioFlo, CMMB and etc., are also belong to the scope of this proposal. Although UMTS LCR TDD MBMS is taken as an example for embodiment description, the other TDD based MBMS technologies, such as LTE TDD E- MBMS, MBMS over WiMAX and etc...

Although the RNC is taken as an example for signal measurement reporting, threshold comparing and handover decision making in this embodiment description, thus the related signaling and procedures are defined as a reference. The other network entities in the different network architecture, such as BM-SC centre could also be used for this function. In this case, the network entities could be used for signal measurement reporting, threshold comparing and handover decision making. It is apparent that they belong to the scope of this invention.

Nevertheless, for different kinds of scenarios, the signal measurement reporting, threshold comparing and handover decision making can also be undertaken by related terminal. In this case, the threshold parameter has to be set or updated by the network through the system information or control channel periodically. Terminal receives the threshold information and store in the memory of terminal for measurement results comparing with threshold and making handover decision between MBMS and terrestrial broadcast network.

Although signal strength, such as RSSI is used as a measurement parameter in this embodiment, the other parameters related to the error rate measurement and the radio reception measurement are also belong to the scope of this invention.

Any statistical averaging before reporting or after reporting of the measurement can be applied for this invention.

In order to improve the handover, it might be necessary to combine with the service identifier as well the original network identifier and the transport stream identifier.

The method according to the invention, wherein the broadcasted services are broadcasted from the broadcast network in bursts separated by off-peak intervals, said method further comprises, prior to the measurement of the second level by the user equipment during the idle time slot an act of synchronizing the idle time slot with a burst received from the broadcasted network.

The method according to the invention, wherein the broadcasted services are broadcasted from the broadcast network in bursts separated by off-peak intervals and wherein the telecommunication network broadcasted services are broadcasted on at least one broadcasting time slot, said method further comprising, prior to the act of determining an off-peak interval allowing the measurement of the second signal level by the user equipment, an act of synchronizing an off-peak interval with at least one broadcasting time slot of the telecommunication network.

Claims

1. A method for a mobile user equipment to seamlessly receive broadcast services available from a telecommunication network and a broadcast network while leaving a telecommunication network and being within the coverage of a broadcast network, said method comprising the acts of:

- synchronizing the broadcast services signals received from the broadcast network with the broadcast services received from the telecommunication network,

- measuring one or more network level(s) that fulfils network switching criteria;

- switching from the broadcast services received from the telecommunication network to the broadcast services received from the broadcast network, wherein the broadcast services signal from the telecommunication network comprises idle time slots while the broadcast services signal from the broadcast network comprises broadcast bursts for broadcasting the broadcast services, the synchronizing act comprising the synchronizing of said idle time slots with said broadcast bursts, so that the measuring act is carried out during said idle time slot.

2. The method according to claim 1 , wherein the broadcast services comprise a plurality of channels, each channel being characterized by a service identifier, the user equipment receiving from the telecommunication network a first channel corresponding to a first identifier, wherein the synchronizing act further comprising the act of identifying a second channel corresponding to said first service identifier from the broadcast services received from the broadcast network and wherein the act of switching further comprises the act of switching from said first channel to said second channel.

3. The method according to any of the preceding claims, wherein the telecommunication network comprises a telecommunication network controller, said method further comprising the act of:

- measuring a first signal level of the telecommunication network broadcast services;

- forwarding said first signal level to the network controller;

- measuring a second signal level of the broadcast network broadcast services upon reception of a request from the network controller when the first signal level fulfils a first network switching criterion.

4. The method according to any of the preceding claims, further comprising the acts of:

- forwarding the second level to the network controller; - initiating the synchronization act when the second level fulfils a second network switching criterion.

5. The method according to claims 3 and 4, further comprising, prior to the act of measuring the second level, the act of requesting to the network controller an idle time slot with the telecommunication network, said idle time slot allowing the measurement of the second level by the user equipment.

6. A method for a mobile user equipment to seamlessly receive broadcast services available from a broadcast network and a telecommunication network while leaving a broadcast network and being within the coverage of a telecommunication network, said method comprising the acts of:

- synchronizing the broadcast services received from the telecommunication network with the broadcast services received from the broadcast network

- measuring one or more network level(s) that fulfils network switching criteria; - switching from the broadcast services received from the broadcast network to the broadcast services received from the telecommunication network, wherein the broadcast services signal from the telecommunication network comprises time slots to broadcast the broadcast services, while the broadcast services signal from the broadcast network comprises broadcast off-peak intervals, the synchronizing act comprising the synchronizing of said time slots with said off-peak intervals, so that the measuring act is carried out during said off peak intervals.

7. The method according to claim 6, wherein the broadcast services comprise a plurality of channels, each channel being characterized by a service identifier, the user equipment receiving from the broadcast network a first channel corresponding to a first identifier, wherein the synchronizing act further comprising the act of identifying a second channel corresponding to said first service identifier from the broadcast services received from the telecommunication network and wherein the act of switching further comprises the act of switching from said first channel to said second channel.

8. The method according to any of the preceding claims 6 and 7, wherein the telecommunication network comprises a telecommunication network controller, said method further comprising the act of: - measuring a first signal level of the broadcast network broadcast services;

- forwarding said first signal level to the network controller;

- measuring a second signal level of the telecommunication network broadcast services upon reception of a request from the network controller when the first signal level fulfils a first network switching criterion.

9. The method according to any of the preceding claims 6 to 8, further comprising the acts of:

- forwarding the second signal level to the network controller;

- initiating the synchronization act when the second level fulfils a second network switching criterion.

10. The method according to claims 8 and 9, wherein the broadcasted services are broadcasted from the broadcast network in bursts separated by off-peak intervals, said method further comprising, prior to the act of measuring the second signal level, the act of determining an off-peak interval allowing the measurement of the second signal level by the user equipment.

11. A system for a mobile user equipment to seamlessly receive broadcast services available from a telecommunication network and a broadcast network while leaving a telecommunication network and being within the coverage of a broadcast network, said system being operable to:

- synchronize the broadcast services received from the broadcast network with the broadcast services received from the telecommunication network,

- switching from the broadcast services received from the telecommunication network to the broadcast services received from the broadcast network, wherein the broadcast services signal from the telecommunication network comprises idle time slots while the broadcast services signal from the broadcast network comprises broadcast bursts for broadcasting the broadcast services, the system being further operable to synchronize said idle time slots with said broadcast bursts, so that said system measures one or more network level(s) during said idle time slot.

12. The system according to claim 1 1 , wherein the broadcast services comprise a plurality of channels, each channel being characterized by a service identifier, the user equipment receiving from the telecommunication network a first channel corresponding to a first identifier, said system being further operable to:

- identify a second channel corresponding to said first service identifier from the broadcast services received from the broadcast network: - switch from said first channel to said second channel.

13. The system according to any of the preceding claims 11 and 12, wherein the telecommunication network comprises a telecommunication network controller, said system being further operable to:

- measure a first signal level of the telecommunication network broadcast services;

- forward said first signal level to the network controller;

- measure a second signal level of the broadcast network broadcast services upon reception of a request from the network controller when the first signal level fulfils a first network switching criterion.

14. The system according to any of the preceding claims 11 to 13, further operable to:

- forward the second level to the network controller;

- initiate the synchronization act when the second level fulfils a second network switching criterion.

15. The system according to claims 13 and 14, further operable to request to the network controller an idle time slot with the telecommunication network, said idle time slot allowing the measurement of the second level by the user equipment.

16. A system for a mobile user equipment to seamlessly receive broadcast services available from a broadcast network and a telecommunication network while leaving a broadcast network and being within the coverage of a telecommunication network, said system being operable to:

- synchronize the broadcast services received from the telecommunication network with the broadcast services received from the broadcast network - measure one or more network level(s) that fulfils network switching criteria;

- switch from the broadcast services received from the broadcast network to the broadcast services received from the telecommunication network; wherein the broadcast services signal from the telecommunication network comprises time slots to broadcast the broadcast services, while the broadcast services signal from the broadcast network comprises broadcast off-peak intervals, the system being further operable to synchronize said time slots with said off-peak intervals, so said system measures one or more network level(s) during said off peak intervals.

17. The system according to claim 16, wherein the broadcast services comprise a plurality of channels, each channel being characterized by a service identifier, the user equipment receiving from the broadcast network a first channel corresponding to a first identifier, said system being further operable to:

- identify a second channel corresponding to said first service identifier from the broadcast services received from the telecommunication network;

- switch from said first channel to said second channel.

18. The system according to any of the preceding claims 16 and 17, wherein the telecommunication network comprises a telecommunication network controller, said system being further operable to: - measure a first signal level of the broadcast network broadcast services;

- forward said first signal level to the network controller;

- measure a second signal level of the telecommunication network broadcast services upon reception of a request from the network controller when the first signal level fulfils a first network switching criterion.

19. The system according to any of the preceding claims 16 to 18, further operable to: - forward the second signal level to the network controller;

20. The system according to claims 18 and 19, wherein the broadcasted services are broadcasted from the broadcast network in bursts separated by off-peak intervals, said method further comprising, prior to the act of measuring the second signal level, the act of determining an off-peak interval allowing the measurement of the second signal level by the user equipment.

21 . A mobile user equipment operable to seamlessly receive broadcast services available from a telecommunication network and a broadcast network while leaving a telecommunication network and being within the coverage of a broadcast network, said mobile user equipment being operable to:

- synchronize the broadcast services received from the broadcast network with the broadcast services received from the telecommunication network - measure one or more network level(s) that fulfils network switching criteria;

- switch from the broadcast services received from the telecommunication network to the broadcast services received from the broadcast network, wherein the broadcast services signal from the telecommunication network comprises idle time slots while the broadcast services signal from the broadcast network comprises broadcast bursts for broadcasting the broadcast services, the mobile user equipment being further operable to synchronize said idle time slots with said broadcast bursts, so that said mobile user equipment measures the one or more network level(s) during said idle time slot.

22. The mobile user equipment according to claim 21 , wherein the broadcast services comprise a plurality of channels, each channel being characterized by a service identifier, said mobile user equipment receiving from the telecommunication network a first channel corresponding to a first identifier and being further operable to: - identify a second channel corresponding to said first service identifier from the broadcast services received from the broadcast network:

- switch from said first channel to said second channel.

23. The mobile user equipment according to any of the preceding claims

21 and 22, wherein the telecommunication network comprises a telecommunication network controller, said mobile user equipment being further operable to:

- forward said first signal level to the network controller;

24. The mobile user equipment according to any of the preceding claims 21 to 23, further operable to:

- forward the second level to the network controller;

25. The mobile user equipment according to claims 23 and 24, further operable to request to the network controller an idle time slot with the telecommunication network, said idle time slot allowing the measurement of the second level by the user equipment.

26. A mobile user equipment operable to seamlessly receive broadcast services available from a broadcast network and a telecommunication network while leaving a broadcast network and being within the coverage of a telecommunication network, said mobile user equipment being operable to: - synchronize the broadcast services received from the telecommunication network with the broadcast services received from the broadcast network;

- measure one or more network level(s) that fulfils network switching criteria; /monitoring/ - switch from the broadcast services received from the broadcast network to the broadcast services received from the telecommunication network; wherein the broadcast services signal from the telecommunication network comprises time slots to broadcast the broadcast services, while the broadcast services signal from the broadcast network comprises broadcast off-peak intervals, the mobile user equipment being further operable to synchronize said time slots with said off-peak intervals, so said system measures one or more network level(s) during said off peak intervals.

27. The mobile user equipment according to claim 26, wherein the broadcast services comprise a plurality of channels, each channel being characterized by a service identifier, said mobile user equipment receiving from the broadcast network a first channel corresponding to a first identifier and being further operable to:

- switch from said first channel to said second channel.

28. The mobile user equipment according to any of the preceding claims 26 and 27, wherein the telecommunication network comprises a telecommunication network controller, said mobile user equipment being further operable to:

- measure a first signal level of the broadcast network broadcast services;

- forward said first signal level to the network controller; - measure a second signal level of the telecommunication network broadcast services upon reception of a request from the network controller when the first signal level fulfils a first network switching criterion.

29. The mobile user equipment according to any of the preceding claims

26 to 28, further operable to:

- forward the second signal level to the network controller;

30. The mobile user equipment according to claims 28 and 29, further operable to request to the network controller an idle time slot with the telecommunication network, said idle time slot allowing the measurement of the second signal level by the user equipment.

31. A computer program providing computer executable instructions stored on a computer readable medium, which when loaded on to a data processor causes the data processor to perform a method for a user equipment to seamlessly receive broadcast services available from a telecommunication network and a broadcast network while leaving a telecommunication network and being within the coverage of a broadcast network according to one of the claims 1 to 5.

32. A computer program providing computer executable instructions stored on a computer readable medium, which when loaded on to a data processor causes the data processor to perform a method for a user equipment to seamlessly receive broadcast services available from a broadcast network and a telecommunication network while leaving a broadcast network and being within the coverage of a telecommunication network according to one of the claims 6 to 10.