Abstract:
A cellular communications system is described in which a mobile cellular device is configured to return status data to the network when instructed to obtain cell measurements. When used, the status data may indicate that measurements are in hand and that further measurement reports may or will follow. The status data may also indicate if the reporting interval and/or the measurement gaps defined by the network are suitable to make the measurements given the current status of the mobile device. A network node is also disclosed that can receive the measurement reports and interpret the status data to decide to wait for further measurement results or to issue a new reporting interval or a new cell list or arrange a new configuration of idle gaps in which cell measurements may be made.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to cellular communication devices. The invention has particular relevance to cellular devices that operate in accordance with the ETSI and 3GPP standards, such as the GSM standards, UTRAN standards and the Long Term Evolution (LTE) of UTRAN (called Evolved Universal Terrestrial Radio Access Network (E-UTRAN)) standards. 
       BACKGROUND ART 
       [0002]    There are a number of different cellular telephone standards, such as GSM, UMTS, LTE that define different operating frequencies and protocols to allow user equipment (UE), such as a mobile telephone, to communicate with other user equipment via the telephone network. Many UEs are able to operate using a number of these different standards and typically will connect with the network node that provides the best signal strength and the best service level. However, as the UE moves, it has to handover to a different network node, which may operate using a different technology. For example, the UE may initially be connected with an LTE network node and may move out of coverage of that node into the cell coverage of a UMTS network node. Such handover is called “inter-RAT” handover as the UE changes the Radio Access Technology (RAT) during the handover. According to the current 3GPP standards, it is the responsibility of the network nodes to determine when a UE should handover to another network node. The network node makes this decision based on measurements provided by the UE for a number of candidate neighbouring cells (defined in a neighbour cell list) provided to the UE by the network node. 
         [0003]    With the number of different technologies supported within a single phone on the increase (i.e. three or more), the task of managing inter-RAT measurements gets ever more complex. The current principle is that the network is all knowing (it knows the theoretical capabilities of the UE and its current state in sufficient detail). So the network should be able to manage traffic gaps (directly or indirectly, according to the technology) to allow inter-RAT measurements to be made by the UE. Moreover, the network assumes that the UE is able to act as planned and expects results within a certain timeframe. 
         [0004]    Thus, when the network requires a UE to make inter-RAT measurements, it may define the measurements to be made and set up periodic reporting. In response, the UE makes the measurements during the managed gaps and then in due course, the UE sends measurement reports. It may:
       report some measurements;
 
in which case the network might assume that more measurements will be coming, if the report is incomplete (i.e. some cells have not been measured yet).
   report no measurements;
 
in which case the network might assume that the UE has completed all its measurements (i.e. any missing cell in the reports is invisible to the UE).
       
 
         [0007]    However, the inventors have realized that these assumptions made by the network are problematic and could be wrong and it may be a waste of effort to try and achieve absolute mastery of the UE&#39;s real-time state and capability. For instance the reporting interval provision might have been inappropriate for the UE&#39;s actual capabilities and circumstances on the current RAT and the UE might have been unable to do any measurements at all, without that implying that the measurements are complete (i.e. that it definitely cannot use any of the neighbouring cells). This problem could be solved by the network defining a relatively long reporting interval, but this is inefficient. 
       SUMMARY OF THE INVENTION 
       [0008]    According to one aspect, a preferred embodiment provides new signalling in measurement reports, allowing the UE to indicate explicitly whether or not more measurements are to be expected (e.g. a continuation flag) or that network provisions are inadequate. That way, the network need not make assumptions one way or the other and, in the case where the UE is signalling that measurements are not complete, yet is not reporting any measurements, the network might then conclude that its gap scheduling policy or the defined measurement interval requires adjustment, at least with respect to that particular UE. 
         [0009]    A cellular communications system is provided in which a mobile cellular device is configured to return status data to the network when instructed to obtain cell measurements. When used (the status data may not be needed, for example if the measurements can be completed and reported as requested), the status data may indicate that measurements are in hand and that further measurement reports may or will follow. The status data may also indicate if the reporting interval and/or the measurement gaps defined by the network are suitable to make the measurements given the current status of the mobile device. A network node is also provided that can receive the measurement reports and interpret the status data to decide to wait for further measurement results or to issue a new reporting interval or a new cell list or arrange a new configuration of idle gaps in which cell measurements may be made. 
         [0010]    According to one aspect, the invention provides a cellular communications device comprising: means for receiving a measurement control command including a neighbour cell list; means for determining a suitability of network provisions for making the measurements in dependence upon a current status of the cellular communications device; and means for generating a measurement report including measurement status data indicative of the status of the requested measurements or indicative of the suitability of the network provisions. 
         [0011]    The first measurement report may include cell measurements as well as the status data. However, the report may be sent before the first measurement opportunity defined by the reporting interval, especially if the status data indicates that the reporting interval is not suitable for the device. 
         [0012]    The reported status data may include binary flags or enumerated values that indicate whether or not all cells that can be reported have been reported and whether or not more cells may or will be reported at a subsequent reporting opportunity. The status data may include data indicating that more cells may be reported but that the reporting interval makes for inefficient operation. 
         [0013]    The status data may include data indicating whether or not the device can perform the requested measurements by a first reporting time defined by the reporting interval or data indicating whether or not measurement gaps are too short and/or too close to other reserved resources. 
         [0014]    The status data may include data indicating an estimated time for completing the measurements or data indicating a minimum reporting interval required to enable efficient measurements. 
         [0015]    According to another aspect, the invention provides a network communications node operable to communicate with one or more cellular communication devices, the network communications node comprising: means for outputting a measurement control command including a first neighbour cell list to a cellular communication device; means for receiving a measurement report from the mobile communications device, the measurement report including measurement status data indicative of the status of the requested measurements or indicative of the suitability of network provisions for the measurements; and means for determining whether to wait for one or more further measurement reports or to determine new network provisions in dependence upon said status data. 
         [0016]    If the status data indicates that cell measurements may or will be reported at a subsequent reporting opportunity then the determining means determines to wait for one or more further measurement report. However, if the status data includes data indicating that more cells may be reported but that the measurement gap makes for inefficient operation or that the measurement gaps are too short and/or too close to other reserved resources, then the determining means is operable to determine a new measurement gap pattern for the cellular device. 
         [0017]    If the status data includes data indicating a minimum measurement gap required to enable efficient measurements, then the network node may determine if a different measurement gap can be defined. The measurement gap can be signalled explicitly to the cellular device or it may be implicitly provisioned by the network node through defined idle times. 
         [0018]    In response to receiving a measurement report known to be final (as indicated in the status data from the cellular device), the network node will determine whether or not to generate a new measurement command with a new cell list or whether to handover to another cell. 
         [0019]    The innovation applies primarily when a UE supports handovers between two or more access technologies (RATs). It applies when handover from one or any of the access technologies is controlled by the network after obtaining neighbour cell measurements from the UE which may be specified in terms of cells to report on and when to report results. The invention therefore applies to, among others, GSM and its derivatives, UMTS and its derivatives and LTE and its derivatives. 
         [0020]    In some embodiments, more values are defined so that the UE may provide more information with an empty report or even with non-empty reports (meaning with or without any measurement results). For example:
       a flag may be provided that indicates whether or not the network provisions for the inter-RAT measurements are sufficient. Obviously such a flag is not needed in a non-empty report, as provisions are then clearly adequate. However, in an empty report, a negative value may be used to imply that the UE requires a different gap pattern to provide any measurement at all. There is still some ambiguity in this case since a positive value in an empty report can be interpreted in two ways: a) the UE did not manage any complete measurement by this reporting opportunity, but non-empty reports are to be expected eventually, however slowly, as the gap pattern is deemed acceptable by the UE; or b) the UE has indeed nothing to report.   a flag may be provided that indicates whether or not measurements are complete. That is whether the network should expect any more, but not qualifying the scheduling policy. In a non-empty report, the flag is unambiguous: it signals the end of a measurement cycle (further reports will relate to cells already reported) even if not all the required cells could be measured. In an empty report, a positive value signals that there is nothing to report, but a negative value could be interpreted in two ways: a) further measurements will eventually be reported; or b) the UE cannot use the current gap pattern.   A flag may be provided that has three states (resolving the ambiguities noted above): “all measurements done” (report may or may not be empty); “more measurements to be expected” (report may or may not be empty); and “please provide a different gap pattern” (the report should logically be empty).       
 
         [0024]    Alternatively, the notions of measurement completeness and gap pattern adequateness could be reported via independent flags. 
         [0025]    In a further embodiment, in addition to the options above, a further value may be provided indicating an estimate of how many more reporting opportunities will be required to complete the current cycle of measurements, including a value signifying that the UE cannot estimate the end of the current measurement cycle. 
         [0026]    In one embodiment, the “all measurements done” value, or another value, could also be used by the UE to signify that it has decided not to measure any further cells. 
         [0027]    Whilst such measurement reporting is typically carried out on a periodic basis, the concept could be extended to non-periodic reporting. For example, the UE might decide to report a partial set of measurements and indicate that it intends to send more. The UE can then send the other results at an appropriate time outside the normal periodic reporting interval and the network will wait for the next report. 
         [0028]    The present invention also provides corresponding methods and a computer implementable instructions product comprising computer implementable instructions for causing a programmable computer device to become configured as the above mobile device or as the above network node. The product may include a computer readable medium or a signal that carries the instructions. 
         [0029]    These and various other aspects of the invention will become apparent from the following detailed description of embodiments which are described, by way of example only, with reference to the accompanying Figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]      FIG. 1  schematically illustrates a mobile telecommunication system of a type to which the embodiment is applicable; 
           [0031]      FIG. 2  is a block diagram illustrating components of a network base station forming part of the system shown in  FIG. 1 ; 
           [0032]      FIG. 3  is a block diagram illustrating components of a mobile communication device forming part of the system shown in  FIG. 1 ; 
           [0033]      FIG. 4  is a timing diagram illustrating the data flow between the mobile communication device and the base station shown in  FIG. 1 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     (Overview) 
       [0034]      FIG. 1  schematically illustrates part of a mobile (cellular) telecommunications system  1  having a mobile telephone  3 , three radio access networks  5 - 1 ,  5 - 2  and  5 - 3  and corresponding core networks  7 - 1 ,  7 - 2  and  7 - 3 . Each of the radio access networks  5  operates to communicate with mobile telephones  3  within a respective cell, which are illustrated in  FIG. 1  by the dashed circles labelled C 1 , C 2  and C 3  respectively. In this embodiment, radio access network  5 - 1  is an E-UTRAN access network, radio access network  5 - 2  is a UMTS access network and radio access network  5 - 3  is a GSM access network. In this embodiment, the mobile telephone  3  is a multi-RAT device that can connect or communicate with E-UTRAN cells, UMTS cells and GSM cells. In the illustrated Figure, the mobile telephone  3  is within the all of the cells and so can therefore connect with any of the three radio access networks  5  to be able to communicate with other users (not shown) via the selected radio access network  5 , its associated core network  7  and the telephone network  9 . 
       (Radio Access Network) 
       [0035]    Although each radio access network  5  may operate a number of different cells, each providing different services to the mobile telephone  3 , in this embodiment it will be assumed, for simplicity, that each radio access network  5  operates a single cell. In the case of E-UTRAN, the radio access network  5 - 1  is foamed by a base station (referred to as an eNodeB or just eNB) and it is the base station&#39;s responsibility to instruct the mobile telephone  3  to make the cell measurements so that it can make the appropriate handover decision. In other radio access networks the responsibility for instructing the mobile telephone  3  to perform the cell measurements may fall to some other network node in the radio access network or in the core network  7 . For ease of description, however, in this embodiment, it will be assumed that the mobile telephone  3  is associated with the E-UTRAN base station  5 - 1  and the main components of this base station  5 - 1  are illustrated in  FIG. 2 . As shown, the base station  5 - 1  includes a transceiver circuit  21  which is operable to transmit signals to and to receive signals from the mobile telephone  3  via one or more antennae  22  and which is operable to transmit signals to and to receive signals from the core network  7 - 1  via a core network interface  23 . The base station  5 - 1  also includes a controller  25  which controls the operation of the base station  5 - 1  in accordance with software stored in memory  27 . The software includes, among other things, an operating system  31 , a handover module  32  and a report module  33 . The handover module  32  is operable to control the handover of the mobile telephone  3  to another cell. The report module  33  is operable to command the mobile telephone  3  to perform the desired inter-RAT measurements and to provide those measurements to the base station  5 - 1  within a defined time, so that this information can be used by the handover module  32  to identify the best target cell for the handover. 
         [0036]    The memory  27  also stores various data including neighbour cell data  34  and mobile telephone (MT) capability data  35 . The report module  33  uses the neighbour cell data  34  to identify to the mobile telephone  3  the cells for which measurements are to be obtained. The report module  33  uses the MT capability data  35  to calculate an appropriate reporting interval by which the mobile telephone  3  is expected to provide a measurement report. 
       (Mobile Telephone) 
       [0037]      FIG. 3  schematically illustrates the main components of the mobile telephone  3  shown in  FIG. 1 . As shown, the mobile telephone  3  includes a transceiver circuit  71  that is operable to transmit signals to and to receive signals from a radio access network  5  via one or more antennae  73 . As shown, the mobile telephone  3  also includes a controller  75  which controls the operation of the mobile telephone  3  and which is connected to the transceiver circuit  71  and to a loudspeaker  77 , a microphone  79 , a display  81 , and a keypad  83 . The controller  75  operates in accordance with software modules stored within memory  85 . As shown, these software modules include, among other things, an operating system  87 , a measurement module  89  and a reporting module  91 . In response to receiving a command from the base station  5 - 1 , the reporting module  91  is operable to make the measurement module  89  obtain the desired measurements and to send the measurements to the radio access network  5 . The memory  85  also stores a neighbour cell list  93  that is received from the radio access network  5 . The measurement module  89  uses the neighbour cell list  93  to identify the cells for which measurements are to be obtained and the report module  91  sends one or more reports to the radio access network  5  to report the measurements that have been obtained. As will be described in more detail below, in this embodiment, the report module  91  also determines and sends feedback information to the radio access network  5  to help the radio access network  5  draw the correct conclusions when interpreting the measurement reports received from the mobile telephone  3 . 
         [0038]    In the above description, both the base station  5 - 1  and the mobile telephone  3  are described, for ease of understanding, as having various discrete software modules. Whilst these software modules may be provided in this way for certain applications, for example where an existing system has been modified to implement the invention, in other applications, for example in systems designed with the inventive features in mind from the outset, the functionalities of these modules may be performed by a single module or they may be built into the overall operating system or code and so these modules may not be discernible as discrete entities. 
       (Operation) 
       [0039]    The operation of the present embodiment will now be illustrated through a discussion of an example scenario that is given with reference to the timing diagram shown in  FIG. 4 . As shown, the process starts when the base station  5 - 1  sends, in step s 1 , the mobile telephone  3  a measurement control command asking the mobile telephone  3  to report to it at one or more specified reporting times (specified in the command by a reporting interval—reporting_interval) with measurements for neighbouring cells (specified in the command—nc_list). The base station  5 - 1  determines the reporting interval based on the capability data  35  it has stored for the mobile telephone  3  and it determines the cells to include in the neighbour cell list based on its stored neighbour cell data  34 . In response to receiving this command, the mobile telephone  3  records the reporting interval and stores the neighbour cells as the current cell list  93 . In this example, as illustrated at step s 3 , at the time that this command is received by the mobile telephone  3 , the telephone  3  is busy (for example the base station  5 - 1  may have provided a reporting interval which is too close to a Multimedia Broadcast Multicast Service (MBMS) resource which the user of the mobile telephone  3  has unilaterally selected, so it cannot make full use of the reporting interval due to frequency switching delays) and so is unable to obtain all the desired measurements and report them to the base station  5 - 1  by the first reporting opportunity. Therefore, in this illustration at the first reporting opportunity the mobile telephone  3  sends, in step s 5 , a report with no measurements, but with a flag indicating that “more” measurements may follow. In step s 7 , the base station  5 - 1  identifies the “more” flag contained in the report and interprets it to mean that measurements may be sent. Therefore, the base station  5 - 1  decides to do nothing and to wait until the next reporting opportunity before making any further decisions for this mobile telephone  3 . At the next reporting opportunity, at step s 9 , the mobile telephone  3  has some (but not all) of the measurements to report and so prepares and sends another measurement report that includes the available cell measurements and another “more” flag, indicating that more measurements may still be reported. 
         [0040]    At step s 11 , the base station  5 - 1  receives the second measurement report and stores the measurements contained therein. The base station  5 - 1  again identifies and interprets the “more” flag and again waits until the next reporting opportunity before making further decisions for this mobile telephone  3 . In step s 13 , the mobile telephone  3  sends a final measurement report to the base station  5 - 1 . The mobile telephone  3  identifies the report as being the final one in respect of the received command by including a “finished” flag in the report together with the final measurements. (If the command is a request for periodic reports, then this “final” report may not actually be final, just the last one for the current cycle.) In step s 15 , the base station  5 - 1  stores the final measurements and interprets the “finished” flag to mean that the mobile telephone  3  has finished sending (in the current cycle) measurement reports for the cells listed in the neighbour cell list sent by the base station in step s 1 . The base station  5 - 1  then processes the stored measurements and determines if it should wait for another measurement cycle; or if a new cell list should be sent to the mobile telephone  3 ; or if a handover should be performed and if so, with which target cell. 
         [0041]    Thus the embodiment above allows the mobile telephone  3  to provide some feedback on the status of its measurements at measurement reporting opportunities, with or without any measurements, which may be incomplete. 
       (Advantages of the Embodiment) 
       [0042]    Advantages of the embodiment include: 
         [0043]    1. The feedback should help the network to make the most appropriate decision, in particular when the measurements appear incomplete or missing altogether. Depending on the feedback, it might be best for the network to wait for the next measurement reporting opportunity, or it might be best for the network to offer a new set of cells to consider, or extend the measurement gaps, or arrange them differently, etc. 
         [0044]    2. With the proposed feedback information, the network can avoid having to make assumptions based on a statistical analysis, such as “When a mobile telephone  3  does not report measurements in time, it usually means it cannot detect the proposed cells” or some other heuristic the network implements. 
         [0045]    3. With mobile telephones that use this feedback mechanism, the network may choose to “sail close to the wind”: by not applying a conservative margin when deciding the reporting period, as the network can be confident that the mobile telephone  3  will immediately inform the network of its desire for a longer reporting period. 
         [0046]    4. Besides a possible reduction in handover time, the frequency of handover failures (or successful but with Quality of Service reduction) should be reduced as candidate cells are assessed better and thus chosen better. 
         [0047]    Thus the present embodiment requires changes to be made to the existing standards. In particular, to implement the above embodiment, the existing standard must be adapted to allow the mobile telephone  3  to provide the feedback information to the network. Additionally, the standard must be adapted to allow the base station  5 - 1  (or other network node depending on the RAT involved) to accept and use the feedback information when deciding on whether to wait for further measurements or to issue a new cell list. 
       (Modifications and Alternatives) 
       [0048]    A detailed embodiment has been described above. As those skilled in the art will appreciate, a number of modifications and alternatives can be made to the above embodiment whilst still benefiting from the invention embodied therein. By way of illustration only a number of these alternatives and modifications will now be described. 
         [0049]    There is a range of feedback information the mobile telephone might return. Ideally, comprehensive feedback (such as a sensible combination of all the options mentioned below) would allow the network to make the optimal decision. However, the relevant standards bodies may prefer a more basic feedback to reduce the bit overhead involved. For example the feedback may be restricted to a simple flag indicating whether or not the measurements are possible under current conditions; or a simple flag indicating whether or not the measurement report is considered complete by the mobile telephone (confirming then that waiting for further reports would be wasteful as any non reported cells are either non detectable or anyway definitely worse than those that are reported); or, of course, a combination of both such flags. The mobile telephone  3  might also qualify any problems it has with the resources available for measurements (such as: measurement gaps are too short, or the measurement gaps are too close to a reserved resource (e.g. MBMS “slot”) by so much). The standards bodies may accept unused feedback codes for future use. The mobile telephone  3  might also return an estimate of the time required to complete the current round of measurements, under current conditions (given as a number of reporting opportunities). There could also be a value indicating the report is complete (e.g. zero more opportunities) and there could a value meaning never (this would be equivalent to an indication that measurement gaps are unsuitable). All these options are not mutually exclusive though some, of course, are. 
         [0050]    Measurement reports in GSM and UMTS are very flexible. There would be no difficulty in adding a new optional Information Element (IE). The same flexibility will exist in succeeding standards, but in this case, the addition of an IE is even less problematic. Examples of IEs suggested by this proposal are defined below. Further IEs could be defined by combining fields from different examples. Any of the fields might be mandatory or optional. The decision on that is a matter for the standards bodies concerned. 
         [0051]    A reasonable option consists in a single optional IE comprising a small set of fields, chosen from those given below. Note that some combinations of the examples below may be redundant and should not be selected within a solution. 
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Possible components of a Measurement Feedback IE 
               
             
          
           
               
                 Name (arbitrary) 
                 Size 
                 Values 
                 Meaning 
               
               
                   
               
               
                 More flag 
                 1 bit 
                 0 
                 All cells that can be measured (or will be measured) have 
               
               
                   
                   
                   
                 been reported at least once. 
               
               
                   
                   
                 1 
                 Not all cells have been reported. The mobile telephone may 
               
               
                   
                   
                   
                 report some more at a further reporting opportunity. 
               
               
                 Finished flag 
                 1 bit 
                 0 
                 Not all cells have been reported. The mobile telephone will 
               
               
                   
                   
                   
                 report some more at a further reporting opportunity. 
               
               
                   
                   
                 1 
                 All cells that can be measured (or will be measured) have 
               
               
                   
                   
                   
                 been reported at least once. 
               
               
                 Happy flag 
                 1 bit 
                 0 
                 The mobile telephone cannot perform the requested 
               
               
                   
                   
                   
                 measurements as its capabilities and currently used services 
               
               
                   
                   
                   
                 do not allow them. 
               
               
                   
                   
                 1 
                 The mobile telephone can perform the requested 
               
               
                   
                   
                   
                 measurements in current conditions. 
               
               
                 Feasibility.status 
                 Suitable 
                 0 
                 No problem; measurements are complete or forthcoming. 
               
               
                   
                 for 
                   
                 (Other flags may complement this information.) 
               
               
                   
                 value 
                 1 
                 Measurement gaps are too short. 
               
               
                   
                 range 
                 2 
                 Measurement gaps are too close to other reserved resources. 
               
               
                   
                   
                 3 
                 Measurement gaps are too short and too close to other 
               
               
                   
                   
                   
                 reserved resources. (case 1 + 2). 
               
               
                   
                   
                 ? 
                 Depending on the technology considered, other cases may be 
               
               
                   
                   
                   
                 relevant. 
               
               
                 General status 
                 2 bits or 
                 0 
                 All cells that can/will be measured have been reported at 
               
               
                   
                 more 
                   
                 least once. 
               
               
                   
                   
                 1 
                 More cells may be reported. 
               
               
                   
                   
                 2 
                 More cells may be reported, but the measurement gaps make 
               
               
                   
                   
                   
                 for inefficient operation. 
               
               
                   
                   
                 3 
                 No measurements reported because the measurement gaps 
               
               
                   
                   
                   
                 are unsuitable. 
               
               
                   
                   
                 ? 
                 Depending on the technology considered, other cases may be 
               
               
                   
                   
                   
                 relevant. 
               
               
                 Estimated Time of 
                 Suitable 
                 0 
                 All cells that can/will be measured have been reported at 
               
               
                 Delivery 
                 for 
                   
                 least once. 
               
               
                   
                 value 
                 1 to 
                 Number of reporting intervals likely to be required to report 
               
               
                   
                 range 
                 max-2 
                 on all cells. 
               
               
                   
                   
                 max-1 
                 Never (measurement gaps unsuitable). 
               
               
                   
                   
                 max 
                 ETD unknown. 
               
               
                 Gap requirement 
                 ? 
                 ? 
                 Minimal interval configuration required to enable most 
               
               
                   
                   
                   
                 efficient measurements. This information may need to be 
               
               
                   
                   
                   
                 Access Technology specific. So no examples are given (gap 
               
               
                   
                   
                   
                 duration may not be the only relevant factor). 
               
               
                   
               
             
          
         
       
     
         [0052]    Fields can also be combined into enumerated types (rather than binary flags), as long as the different values are mutually exclusive. The actual numerical values used are arbitrary and need only be fixed by the standard. 
         [0053]    Finally, it should be possible for the measurement feedback IE to be the only IE in a measurement report, or at least the only optional IE. In this case it is sent purely for feedback purposes and need not necessarily be sent after the designated interval. For example, if the mobile telephone  3  can determine that the measurement gaps are unsuitable, then it could send the feedback immediately without waiting for the first reporting opportunity. 
         [0054]    It might be useful to enhance the mobile telephone&#39;s capability signalling, allowing the mobile telephone  3  to indicate to the network that it will use this measurement feedback. 
         [0055]    In the above embodiment, the base station was responsible for issuing the measurement commands and for deciding on the handover. As those skilled in the art will appreciate, this functionality may be performed by some other network node in other radio access technologies. 
         [0056]    In the above embodiments, a number of software modules were described. As those skilled will appreciate, the software modules may be provided in compiled or un-compiled form and may be supplied to the core network, radio access network or to the mobile telephone as a signal over a computer network, or on a recording medium. Further, the functionality performed by part or all of this software may be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred as it facilitates the updating of radio access network  5  and the mobile telephone  3  in order to update their functionalities. 
         [0057]    In the above embodiment, a mobile telephone was provided that communicated with a number of radio access networks. As those skilled in the art will appreciate, the invention is applicable to other types of user equipment (UE) such as laptop computers, Personal Digital Assistants or other hand held portable computer devices. 
         [0058]    In the above embodiment, each radio access network was connected to its own core network  7 . As those skilled in the art will appreciate, a cell can be part of a network sharing architecture in which there may be several core networks  7  that use the same cell or there may be several cells (of different RATs) that operate in connection with the same core network.