Method for implementing network selection and user equipment

Abstract

The invention relates to a method for implementing network selection by a user equipment in a radio environment comprising a plurality of radio cells of a plurality of mobile communication networks, each of these radio cells being respectively associated to at least one mobile communication network of the plurality of mobile communication networks, wherein the user equipment measures or detects reception conditions with respect to the plurality of radio cells and subsequently selects and / or registers to a mobile communication network from the plurality of mobile communication networks, wherein with respect to the cell selection by the user equipment, cell selection criteria are defined, wherein in the case where the corresponding reception conditions measured by the user equipment correspond to or exceed the cell selection criteria with respect to the considered radio access technology, the radio cells of the considered radio access technology are considered as suitable radio cells, wherein with respect to the network selection by the user equipment, at least one predefined enhanced network selection criterion can be applied, wherein the method comprises the following steps: - in a first step, the determination by the user equipment of suitable radio cells of the considered radio access technology based on the cell selection criteria with respect to the considered radio access technology, - in a second step, upon initiation of the network selection according to an automatic network selection mode, only such mobile communication networks corresponding to suitable radio cells of the considered radio access technology are considered for the network selection of the user equipment, these mobile communication networks having or corresponding to reception conditions which correspond to or exceed the enhanced network selection criterion.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for implementing network selection by a user equipment being in a radio environment comprising a plurality of radio cells of a plurality of mobile communication networks, each of the radio cells being associated to at least one mobile communication network of the plurality of mobile communication networks, wherein the user equipment measures or detects reception conditions with respect to the plurality of radio cells and subsequently selects a mobile communication network from the plurality of mobile communication networks and / or registers to the mobile communication network.

[0002] Furthermore, the present invention relates to a user equipment for implementing network selection by a user equipment being in a radio environment comprising a plurality of radio cells of a plurality of mobile communication networks, each of the radio cells being associated to at least one mobile communication network of the plurality of mobile communication networks, wherein the user equipment is configured to measure or detect reception conditions with respect to the plurality of radio cells and is configured to subsequently select a mobile communication network from the plurality of mobile communication networks and / or to register to the mobile communication network.

[0003] Additionally, the present invention relates to a system or a mobile communication network for implementing network selection by a user equipment being in a radio environment comprising a plurality of radio cells of a plurality of mobile communication networks, each of the radio cells being associated to at least one mobile communication network of the plurality of mobile communication networks, wherein the user equipment is configured to measure or detect reception conditions with respect to the plurality of radio cells and is configured to subsequently select a mobile communication network from the plurality of mobile communication networks and / or to register to the mobile communication network.

[0004] Furthermore, the present invention relates to a program and a computer readable medium for implementing network selection by a user equipment being in a radio environment comprising a plurality of radio cells of a plurality of mobile communication networks according to the method of the present invention. BACKGROUND

[0005] In currently deployed mobile communication networks, a user equipment or mobile station typically experiences a radio environment comprising a plurality of radio cells which are at least detectable and / or receivable by the respective user equipment or mobile station (i.e. different radio frequency signals which the user equipment potentially can receive at its current location or position on different frequencies and / or frequency bands and / or at different points in time or time intervals or time slots). One such radio cell is typically provided by a base station entity, i.e. an antenna arrangement of a particular base station entity transmits a radio frequency signal such that the user equipment at its current location or position is able to receive such a radio frequency signal with sufficient quality (typically with sufficient signal-to-noise ratio). If this is the case, the radio environment of the user equipment comprises the considered radio cell. The plurality of radio cells (i.e. the plurality of radio cells of base station entities) is typically part of a mobile communication network as a cellular mobile communication network. Thus, the plurality of radio cells of the radio environment of the user equipment is typically part of a plurality of mobile communication networks, typically each of these radio cells is associated with one of the plurality of mobile communication networks or with more than one of the plurality of mobile communication networks, respectively. Thus, by selecting a radio cell (from the plurality of radio cells present or receivable in the radio environment at the considered location or position of the user equipment), the user equipment selects a mobile communication network (associated with the radio cell) as well. However, before a mobile communication network is considered as a network selection candidate (i.e. a candidate mobile communication network), the user equipment needs to find a suitable radio cell of a mobile communication network or public land mobile network to camp on. The criteria to consider a radio cell as a suitable radio cell (to camp on) depends on the considered network technology (or radio access technology) which is defined in or by the relevant standardization documents (mostly referred to as 3GPP (Third Generation Partnership Project) documents).

[0006] In currently known mobile communication networks, i.e. in networks complying with currently defined standards or standard documents, a number of drawbacks can occur: the 3GPP defined order or prioritization of how to select a mobile communication network for obtaining a communication service or any service in (user equipment's) bad or unfavorable radio coverage conditions is not suitable in all relevant cases. For example, in some cases the field strength or quality (of a radio signal or multiple radio signals) of a radio cell (of the radio environment of the user equipment) is not considered in the network selection procedure (PLMN selection procedure), which leads to the user equipment not being able to receive and / or transmit data after the initial network selection procedure (PLMN selection procedure). Such cases include situations in which some user equipment can fail to obtain data services, even though the selected public land mobile network fulfills the cell selection criteria for considering the respective mobile communication network (public land mobile network) in the network selection (or PLMN selection) procedure. In particular, in situations in which the user equipment is at or in an unfavorable location, the applicable cell selection criteria (e.g. the "RX Access Lev min" criterion) can be barely fulfilled, so that the user equipment considers the respective public land mobile network for PLMN selection, but in fact the data transmission between the network and the user equipment can subsequently fail due to, for example, fading or local interference at the location of the user equipment. Such situations occur especially with regard to cellular user equipment or devices for Internet of Things or M2M (machine-to-machine) communication services, which devices are typically used in a stationary manner (e.g. meters or various sensors etc.) and in situations of unfavorable radio (reception) conditions, this problem can permanently exist for such user equipment, resulting in a situation in which such user equipment (especially in automatic network selection mode) is stuck on a PLMN while being unable to transmit data. In the absence of advanced application logic, such user equipment can currently require on-site human intervention, as they are also no longer reachable; therefore, such user equipment can need to be switched or reconfigured to a manual network selection (PLMN selection) mode, and can need to permanently select an appropriate mobile communication network, which potentially leads to further difficulties in selecting an appropriate mobile communication network in situations of network modification and / or local modification of the involved respective base station entity. Such interventions can be costly for the user of such user equipment (especially but not necessarily Internet of Things devices), and due to the use of a manual network selection mode, the advantages of automatic network selection (e.g. reselection to another mobile communication network in case of an interruption of the registered network (registered public land mobile network, RPLMN)) are no longer possible. SUMMARY

[0007] It is an object of the present invention to provide a technically simple, efficient and cost-effective solution for enhanced network selection by a user equipment in a radio environment comprising a plurality of radio cells of a plurality of mobile communication networks. It is a further object of the present invention to provide a corresponding user equipment, system or mobile communication network, as well as a corresponding program and computer readable medium.

[0008] The object of the present invention is achieved by a method for implementing network selection by a user equipment in a radio environment comprising a plurality of radio cells of a plurality of mobile communication networks, each of these radio cells being associated to at least one mobile communication network of the plurality of mobile communication networks,

[0009] wherein the user equipment measures or detects reception conditions with respect to the plurality of radio cells and subsequently selects a mobile communication network from the plurality of mobile communication networks and / or registers to the mobile communication network, wherein with respect to the cell selection by the user equipment, cell selection criteria are defined, wherein a radio cell of a considered radio access technology is considered to be a suitable radio cell only in case the corresponding reception conditions measured by the user equipment correspond to or exceed the cell selection criteria with respect to the considered radio access technology,

[0010] wherein with respect to the network selection by the user equipment, predefined enhanced network selection criteria can be applied, wherein the method comprises the following steps:

[0011] - in a first step, the suitable radio cells of a considered radio access technology are determined by the user equipment based on the cell selection criteria with respect to the considered radio access technology,

[0012] - in a second step, upon initiation of the network selection according to an automatic network selection mode, only such mobile communication networks corresponding to the suitable radio cells of the considered radio access technology are considered for the network selection of the user equipment, which mobile communication networks have or correspond to reception conditions corresponding to or exceeding the enhanced network selection criteria.

[0013] Thereby, according to the present invention, advantageously, network selection can be performed in an optimized manner by applying predefined enhanced network selection criteria instead of applying conventionally used procedures, i.e. considering all suitable radio cells or their corresponding mobile communication networks, in particular resulting in avoiding problems associated with using conventionally used network selection procedures, such as the above mentioned network selection procedures.

[0014] Conventionally, cell selection criteria are used for radio cells which are considered suitable radio cells (i.e. for user equipment to camp on), and these cell selection criteria usually depend on the used considered network technology (or radio access technology), i.e. the radio access technology both the user equipment and the radio cell are using. Usually, different generations of mobile communication systems (i.e. different radio access technologies) are considered, most often including one, all or a subset of the following: 2G, 3G, 4G and 5G technologies (i.e. second generation mobile communication system (GSM, Global System for Mobile communication), third generation mobile communication system (UMTS, Universal Mobile Telecommunication System (including its radio technology E-UTRA, Evolved UMTS Terrestrial Radio Access)), fourth generation mobile communication system (LTE, Long Term Evolution (including its radio technology E-UTRA, Evolved UMTS Terrestrial Radio Access)), and fifth generation mobile communication system (5GS, 5G System, including its radio technology NR, New Radio)), but further or additional or alternative radio access technologies are not excluded according to the present invention.

[0015] In the following, the conventionally used cell selection criteria (or cell selection criteria) are provided according to the different, currently most often deployed radio access technologies:

[0016] GSM network: For GSM networks, the criteria etc. for accessing or camping on a radio cell are given in 3GPP TS 43.022 "Functions related to mobile station (MS) in idle mode and group receive mode", especially version V16.0.0 (2020-07), section 3.6;

[0017] The parameter RXLEV_ACCESS_MIN, which is broadcast as system information, relates to the minimum signal the operator wants the network to receive when initially accessed by the MS.

[0018] UTRA network: For UTRA networks, the criteria etc. for accessing or camping on a cell are given in 3GPP TS 25.304 "User Equipment (UE) procedures in idle mode and in connected mode for cell reselection", especially version V16.0.0 (2020-07), section 5.2.3.1.2; the cell selection criterion S is fulfilled when, for FDD cells, Srxlev > 0 and Squal > 0, and for TDD cells, Srxlev > 0, where

[0019] Squal = Q qualmeas - (Qqualmin + QqualminOffset) - Qoffset temp , and

[0020] Srxlev = Q rxlevmeas - (Qrxlevmin + QrxlevminOffset) - Pcompensation - Qoffset temp ,

[0021] where the signaled values QqualminOffset and QrxlevminOffset are applied when evaluating a cell for cell selection as a result of a periodic search for a higher priority PLMN only when normally camped in a VPLMN (Visited Public Land Mobile Network).

[0022] LTE and NB-IoT networks / E-UTRA networks: For LTE and NB-IoT networks, the criteria for accessing or camping on a cell are given in 3GPP TS 36.304 “User Equipment (UE) procedures in idle mode”, especially in version V16.1.0 (2020-07), sections 5.2.3.2 and 5.2.3.2a:

[0023] Cell selection criteria for LTE: The cell selection criterion S in normal coverage is fulfilled when Srxlev > 0 and Squal > 0, where:

[0024] Srxlev = Qrxlevmeas - (Qrxlevmin + Qrxlevminoffset) - Pcompensation - Qoffsettemp

[0025] Squal = Qqualmeas - (Qqualmin + Qqualminoffset) - Qoffsettemp

[0026] Cell selection criteria for NB-IoT: The cell selection criterion S is fulfilled when Srxlev > 0 if the measurements are performed on a non-anchor carrier and the UE meets the requirements specified in TS 36.133, otherwise the cell selection criterion S is fulfilled when Srxlev > 0 and Squal > 0, where:

[0027] Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation - Qoffsettemp

[0028] Squal = Qqualmeas - Qqualmin - Qoffsettemp.

[0029] NR network: For an NR network, the criteria for accessing or camping on a cell, etc., are given in 3GPP TS 38.304, "User Equipment (UE) procedures in idle mode and in RRC inactive state", especially version V16.1.0 (2020-07), section 5.2.3.2; the cell selection criterion S is fulfilled when Srxlev > 0 and Squal > 0, where:

[0030] Srxlev = Qrxlevmeas - (Qrxlevmin + Qrxlevminoffset) - Pcompensation - Qoffsettemp

[0031] Squal = Qqualmeas - (Qqualmin + Qqualminoffset) - Qoffsettemp.

[0032] Once the user equipment (or more specifically the so-called AS, access stratum part, of the user equipment) has read one or more PLMNs, i.e. one or more radio cells (which can belong to different mobile communication networks or public land mobile networks), the radio cells or public land mobile networks are reported to the so-called NAS, non-access stratum (or NAS part of the user equipment), by the radio cells or public land mobile networks (in view of the potentially different radio access technologies to be applied respectively) via the cell selection criteria for a subsequent stage (or step) of network selection. Typically, this report also includes the transmission of the respective field strength values (such as for example RSRP, reference signal received power, values) (measured by the user equipment). Typically, according to the conventionally known and used standardized user equipment behavior, no (as measured by the user equipment) respective field strength values about such radio cells are reported to the NAS, which not only fulfill the cell selection criteria (to be applied respectively about the considered radio access technology), but also a so-called high quality criterion; however, also about such high quality radio cells, the AS indicates their high quality characteristic (or the fact that these radio cells have been measured to fulfill the high quality criterion) to the NAS and thus, at least implicitly, also the field strength values about these radio cells are transmitted.

[0033] In the following, one or more high quality criteria are provided according to the different, currently most often deployed radio access technologies, which are conventionally used:

[0034] GSM: For GSM, the high quality criterion is given as follows in 3GPP TS 43.022 "Functions related to the mobile station (MS) in idle mode and group receive mode", especially version V16.0.0 (2020-07), section 4.4.3: A PLMN shall be understood to be received with a high quality signal if the signal level is above -85 dBm.

[0035] UTRAN: For UTRA, the high quality criterion is given as follows in 3GPP TS 25.304 "User Equipment (UE) procedures in idle mode and in connected mode for cell reselection", especially version V16.0.0 (2020-07), section 5.1.2.2: For FDD cells, the measured primary CPICH RSCP value shall be greater than or equal to -95 dBm; for TDD cells, the measured P-CCPCH RSCP shall be greater than or equal to -84 dBm.

[0036] E-UTRAN: For LTE / NB-IoT, the high quality criterion is given as follows in 3GPP TS 36.304 "User Equipment (UE) procedures in idle mode", especially version V16.0.0 (2020-07), section 5.1.2.2: For E-UTRAN and NB-IoT cells, the measured RSRP value shall be greater than or equal to -110 dBm.

[0037] NR: For NR, the high quality criterion is given as follows in 3GPP TS 38.304 "User Equipment (UE) procedures in idle mode and RRC inactive state", especially version V16.0.0 (2020-07), section 5.1.2.2: For NR cells, the measured RSRP value shall be greater than or equal to -110 dBm.

[0038] Based on the reporting (especially by the AS part of the user equipment to the NAS part of the user equipment), the actual network selection can be made.

[0039] Conventionally, in the network selection phase, all radio cells (from the previous cell selection phase) that are judged suitable radio cells are taken into account.

[0040] In a simplified way, it can be said that upon start-up or recovery from lack of coverage, the last registered PLMN or a PLMN equivalent to (the last registered PLMN) is selected, or as an option configured on the SIM (Subscriber Identity Module) of the user equipment, the available HPLMN (Home Public Land Mobile Network) or the highest priority EHPLMN (Equivalent Home Public Land Mobile Network) is selected. Regarding reselection, the simplified order of network selection is as follows:

[0041] i) available HPLMN or highest priority EHPLMN,

[0042] ii) each PLMN / access technology combination (in priority order) in the "User Controlled PLMN Selector with Access Technology" data file in the SIM,

[0043] ii) each PLMN / access technology combination (in priority order) in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) or stored in the user equipment (in priority order),

[0044] iv) other PLMN / access technology combinations with "good quality" signals received in random order,

[0045] v) other PLMN / access technology combinations in order of decreasing signal quality.

[0046] In more detail, depending on the actual situation of the user equipment, in particular whether the user equipment has been switched on or recovered from lack of coverage, or whether the reselection has been triggered by the user (of the user equipment), the selection of the (mobile communication) network in the automatic network selection mode (in a radio cell reported to be receivable by the user equipment with sufficient signal strength) is defined as follows:

[0047] Upon switching on or recovery from lack of coverage, the user equipment or mobile station selects the registered PLMN (RPLMN) or equivalent PLMN, i.e. the ERPLMN. As an alternative to this, if the user equipment or mobile station is in the automatic network selection mode and it finds coverage of an EHPLMN (HPLMN or equivalent PLMN of the HPLMN), the user equipment or mobile station can register to this EHPLMN without returning to the registered PLMN or equivalent PLMN. The operator (of the HPLMN of the user equipment) should be able to control by SIM configuration whether the user equipment or mobile station supporting this option is permitted to perform this alternative behavior. If the above network selection attempt is not successful, the user equipment or mobile station selects and attempts to register on other PLMN / access technology combinations (if available and allowed) in the following order:

[0048] i) HPLMN (if the EHPLMN list is not present or empty) or highest priority EHPLMN (if the EHPLMN list is present) available;

[0049] ii) each PLMN / access technology combination (in priority order) in the "User Controlled PLMN Selector with Access Technology" data file in the SIM;

[0050] ii) each PLMN / access technology combination contained in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) or stored in the ME (in priority order);

[0051] iv) other PLMN / access technology combinations with high quality signals received in random order;

[0052] v) other PLMN / access technology combinations in order of decreasing signal quality.

[0053] User triggered reselection: At any time, the user can request the user equipment or mobile station to initiate reselection and register onto an available PLMN according to the following procedure. In the automatic network selection mode, the MS selects and attempts to register on a PLMN / access technology combination (if available and allowed) in all of its operating bands according to the following order:

[0054] i) the HPLMN (if the EHPLMN list does not exist or is empty) or the highest priority EHPLMN available (if the EHPLMN list exists);

[0055] ii) PLMN / access technology combinations contained in the "User Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) excluding the previously selected PLMN / access technology combination;

[0056] ii) PLMN / access technology combinations contained in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) or stored in the user equipment (in priority order) excluding the previously selected PLMN / access technology combination;

[0057] iv) other PLMN / access technology combinations with high quality signals received in random order excluding the previously selected PLMN / access technology combination;

[0058] v) other PLMN / access technology combinations in order of decreasing signal quality excluding the previously selected PLMN / access technology combination, or alternatively, the previously selected PLMN / access technology combination can be selected ignoring its signal quality;

[0059] vi) the previously selected PLMN / access technology combination.

[0060] In case the user equipment is in a VPLMN (Visited Public Land Mobile Network), the user equipment or mobile station shall periodically attempt to obtain service on a higher priority PLMN / access technology combination listed in its HPLMN (if the EHPLMN list is not present or empty) or its EHPLMN (if the EHPLMN list is present) or "user controlled PLMN selector" or "operator controlled PLMN selector" by scanning according to the requirements of i), ii) and iii) as defined above with respect to the case of "switching on or resuming from lack of coverage".

[0061] In case the user equipment or mobile station has a stored list of equivalent "PLMNs", the user equipment shall only select a PLMN if the priority of the PLMN is higher than those of the same country as the current serving PLMN stored in the "equivalent PLMN" list.

[0062] Thus, in conventional mobile communication networks, the (mobile communication) network selection behavior as usually applied or implemented as defined in 3GPP standardization documents has the disadvantage that, once a radio cell (or corresponding public land mobile network) has passed one or more cell selection criteria as indicated above, the mobile communication network is selected (at the network selection stage) based on "non-field strength or quality based" criteria only. This is typically the root cause of the above-mentioned problems and disadvantages of the currently applied steps of both cell selection and network selection (especially at switching on or resuming from lack of coverage), i.e. the considered user equipment is only able to register (to the radio cell due to the applicable cell selection criteria being fulfilled), but subsequently fails in actually transferring data, since such user equipment can be in a relatively poor or disadvantaged coverage situation, e.g. experiencing fading or local interference at the user equipment location. Thus, despite the fact that other (mobile communication) networks with better conditions (or being able to provide enhanced quality of service) would be available, such user equipment is stuck on the selected mobile communication network by applying the above-mentioned conventional known procedures.

[0063] According to the present application, it is proposed that with respect to the network selection by the user equipment, a predefined enhanced network selection criterion can be applied, i.e. such predefined enhanced network selection criterion is defined and used by the user equipment (or mobile station) when performing network selection (especially according to an automatic network selection mode), which results in considering - at least initially for the purpose of network selection of the user equipment - only such mobile communication networks (corresponding to suitable radio cells of the considered radio access technology) having or corresponding to a reception condition corresponding to or exceeding the enhanced network selection criterion.

[0064] This means that according to the present application, with respect to the cell selection, the conventionally known criteria can be applied (including reporting such suitable radio cells (and corresponding public land mobile networks) to the NAS); however, only a subset of all such reported suitable radio cells is considered for network selection purposes (i.e. the subset which fulfils the enhanced network selection criteria) - at least initially.

[0065] Generally, applying the enhanced network selection criteria in the network selection procedure according to the present application (i.e. proposing a modification to be applied to the currently known and used network selection procedure) will have the effect that - by considering only at least initially suitable radio cells corresponding to or exceeding the enhanced network selection criteria (i.e. having a (measured by the user equipment) better signal level, e.g. a higher level of received radio signal strength or field strength) - initially in the network selection phase a possibly lower number of radio cells and corresponding public land mobile networks is considered in the network selection phase (compared to the case of a user equipment applying the conventionally known network selection). However, with respect to such possibly reduced number of selectable public land mobile networks (or mobile communication networks) fulfilling the enhanced network selection criteria, it is very likely that the user equipment is not only able to register to these radio cells, but also to actually transfer (payload) data depending on the intended application the user equipment is used for. Thus, according to the present application, in a first step, the user equipment determines suitable radio cells (of the considered radio access technology) based on the (conventionally known) cell selection criteria with respect to the considered radio access technology, and in a second step, during the network selection phase (especially during the network selection phase according to the automatic network selection mode), for the network selection of the user equipment only such mobile communication networks (corresponding to the suitable radio cells of the considered radio access technology) are considered (at least initially) which have or correspond to a reception condition corresponding to or exceeding the enhanced network selection criteria.

[0066] According to the present application, advantageously possible and preferred is that the enhanced network selection criteria corresponds to a high quality criterion, wherein the high quality criterion corresponds to:

[0067] - with respect to GSM (Global System for Mobile Communications) as the radio access technology: a signal level associated with a high quality reception to a public land mobile network according to the 3GPP standardization,

[0068] -- with respect to UTRAN (UMTS Terrestrial Radio Access Network), E-UTRA (Evolved UMTS Terrestrial Radio Access), NB-IoT (Narrow Band Internet of Things), or NR (New Radio) in a 5G system as radio access technology: a respective signal level according to 3GPP standardization associated with the high quality criterion, which triggers reporting of the respective public land mobile network as high quality public land mobile network in the cell selection phase.

[0069] Thereby, advantageously according to the present application, instead of values of an enhanced network selection criterion different from the high quality criterion, (regularly known values) of the high quality criterion are simply applied during the network selection phase. Thus, there is no need to store or transfer (to the user equipment) actual values of the enhanced network selection criterion (e.g. within a subscriber identity module of the user equipment); (regularly known) values of the high quality criterion can simply be applied.

[0070] According to the present application, for a public land mobile network reported as corresponding to a suitable radio cell (in the cell selection phase), a measured signal quality indicator (during the cell selection phase) or an indication that the considered public land mobile network is a high quality network (i.e. the respective measured signal quality indicator corresponds to or exceeds the high quality criterion) is reported to the NAS. According to the present application, the value of the enhanced network selection criterion preferably corresponds to a value higher than the respective cell selection criterion to be applied with respect to the respective considered radio access technology (i.e. in the direction of better signal quality corresponding to the selection procedure in the cell selection phase). However, the value of the enhanced network selection criterion at most corresponds to the high quality criterion.

[0071] According to the present application, it is further advantageously possible and preferred that the user equipment has or is associated with a home public land mobile network HPLMN, and wherein the enhanced network selection criterion comprises or considers a home operator controlled value set or adjustable by the HPLMN or its operator, wherein the enhanced network selection criterion is particularly more restrictive compared to the cell selection criterion lacking a home operator controlled component,

[0072] wherein in particular the enhanced network selection criterion is at most as restrictive as the high quality criterion, wherein the application of the network selection and the enhanced network selection criterion is triggered, in particular in case the corresponding reception conditions measured by the user equipment do not correspond to or do not exceed the cell selection criterion.

[0073] It is thus advantageously possible that the home public land mobile network is able to influence the behavior of the user equipment even if the user equipment is using a visited mobile communication network. For example, it is advantageously possible that the user equipment individually (or in groups) adjusts the value of the enhanced network selection criterion in order to direct the network selection of those user equipment in such a way that the required or intended communication service can be provided by any one (home or visited or further) mobile communication network in a stable and reliable manner.

[0074] According to the present application, it is further advantageously possible and preferred that the home operator controlled value of the enhanced network selection criterion corresponds to

[0075] - an offset value applied in addition to the cell selection criterion, or

[0076] - an absolute value.

[0077] According to the present application, it is thus advantageously possible to flexibly adjust and modify the home operator controlled value of the enhanced network selection criterion. In general, the use of an offset value can be preferred over the use of an absolute value; however, there can be (individual) cases or reception conditions for which the use of an absolute value can be preferred.

[0078] According to the present application, it is further advantageously possible and preferred that the home operator controlled value of the enhanced network selection criterion or the indication that a high quality criterion is used as the enhanced network selection criterion

[0079] - is stored in the user equipment, in particular in a subscriber identity module, another secure element or a part of or as a part of the user equipment, and / or

[0080] - in particular is provided or transmitted to the user equipment by the HPLMN or its operator, in particular by means of using an over-the-air transmission method.

[0081] By means of providing different possibilities and ways to modify and / or store and / or transmit the home operator controlled value of the enhanced network selection criterion, it is advantageously even possible to flexibly manage a significant number of user equipment or a group of user equipment for different specific tasks, such as for example Internet of Things devices or Machine Type Communication devices, according to the present application.

[0082] Furthermore, it is advantageously possible and preferred according to the present application that the mobile communication network corresponding to the suitable radio cell of the considered radio access technology determined by the user equipment in or during the second step on the basis of the enhanced network selection criterion is

[0083] - carried out after switching on the user equipment, or

[0084] - after recovery from lack of coverage, or

[0085] - upon network reselection triggered by the user, or

[0086] - periodically, in the case of a user equipment in a visited communication network.

[0087] Furthermore, it is advantageously possible and preferred according to the present application that in a third step after the second step - in the case of a lack of a mobile communication network corresponding to a suitable radio cell of the considered radio access technology having or corresponding to a reception condition corresponding to or exceeding the enhanced network selection criterion - the network selection is continued based on the cell selection criterion instead of the enhanced network selection criterion.

[0088] Thereby, it is advantageously possible to complete the network selection phase (after its initial phase as described above) by applying the conventionally known method, i.e. applying the cell selection criterion, which corresponds to using or considering all suitable radio cells reported to the NAS with respect to the network selection (i.e. it is not necessary to focus on a subset corresponding to or exceeding the enhanced network selection criterion only, because according to the present application this is done initially in the network selection phase corresponding to the second step according to the present application).

[0089] Furthermore, the present application relates to a user equipment for implementing a network selection within a radio environment comprising a plurality of radio cells of a plurality of mobile communication networks, each of the radio cells being associated to at least one of the plurality of mobile communication networks,

[0090] wherein the user equipment is configured to measure or detect reception conditions with respect to the plurality of radio cells and to subsequently select a mobile communication network from the plurality of mobile communication networks and / or to register to the mobile communication network, wherein with respect to the cell selection by the user equipment, a cell selection criterion is defined, wherein a radio cell of a considered radio access technology is considered to be a suitable radio cell only in the case that the corresponding reception condition measured by the user equipment corresponds to or exceeds the cell selection criterion with respect to the considered radio access technology,

[0091] wherein with respect to the network selection by the user equipment, at least one predefined enhanced network selection criterion can be applied, wherein the user equipment is configured such that:

[0092] - a suitable radio cell of a considered radio access technology is determined by the user equipment based on the cell selection criterion with respect to the considered radio access technology,

[0093] -- in case of initiating network selection according to an automatic network selection mode, for network selection of the user equipment, only such mobile communication networks are considered which correspond to suitable radio cells of the considered radio access technology having or corresponding to a reception condition corresponding to or exceeding the enhanced network selection criterion.

[0094] Furthermore, the present application relates to a system or a mobile communication network for implementing cell selection by a user equipment in a radio environment comprising a plurality of radio cells of a plurality of mobile communication networks, each of the radio cells being associated to at least one of the plurality of mobile communication networks,

[0095] wherein the user equipment is configured to measure or detect reception conditions with respect to the plurality of radio cells and is configured to subsequently select a mobile communication network from the plurality of mobile communication networks and / or to register to the mobile communication network, wherein a cell selection criterion is defined with respect to the cell selection by the user equipment, wherein a radio cell of a considered radio access technology is considered to be a suitable radio cell only in case the corresponding reception condition measured by the user equipment corresponds to or exceeds the cell selection criterion with respect to the considered radio access technology,

[0096] wherein at least one predefined enhanced network selection criterion can be applied with respect to the network selection by the user equipment, wherein the system and the mobile communication network are configured such that:

[0097] -- a suitable radio cell of a considered radio access technology is determined by the user equipment based on the cell selection criterion with respect to the considered radio access technology,

[0098] -- in case of initiating network selection according to an automatic network selection mode, for network selection of the user equipment, only such mobile communication networks are considered which correspond to suitable radio cells of the considered radio access technology having or corresponding to a reception condition corresponding to or exceeding the enhanced network selection criterion.

[0099] Additionally, the present application relates to a program comprising computer readable program code which, when executed on a computer, and / or on a user equipment, and / or on a network node of a mobile communication network, or partially on a user equipment, and / or partially on a network node of a mobile communication network, causes the computer and / or the user equipment and / or the network node of the mobile communication network to perform the method according to the present application.

[0100] Additionally, the present application relates to a computer readable medium comprising instructions which, when executed on a computer, and / or on a user equipment, and / or on a network node of a mobile communication network, or partly on a user equipment, and / or partly on a network node of a mobile communication network, cause the computer and / or the user equipment and / or the network node of the mobile communication network to carry out the method according to the present application.

[0101] These and other characteristics, features and advantages of the present application will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the application. This description is given for the sake of example and the details are not intended to limit the scope of the application. The reference figures quoted below refer to the attached drawings. BRIEF DESCRIPTION OF DRAWINGS

[0102] Figure 1 A user equipment in a radio environment comprising a plurality of radio cells of a plurality of mobile communication networks is schematically illustrated.

[0103] Figure 2 A situation where the user equipment measures different signal strengths of different radio cells is schematically illustrated. DETAILED DESCRIPTION

[0104] The application will be described with respect to particular embodiments and with reference to certain drawings but the application is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements can be exaggerated and not drawn on scale for illustrative purposes.

[0105] When using a definite article or an indefinite article, such as "a", "an", "the", in reference to a singular noun, e.g. "a user equipment", "the user equipment", "an application", "the application", etc., these articles do not, unless otherwise specified, exclude the plural form of the noun having the same meaning. For example, "a user equipment" includes one or more user equipment.

[0106] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the application described herein are capable of operation in other sequences than described or illustrated herein.

[0107] In Figure 1 In the example of a radio environment comprising a plurality of radio cells of a plurality of mobile communication networks, a user equipment 20 is schematically illustrated. In Figure 1 In the example representation of a radio environment comprising a plurality of radio cells of a plurality of mobile communication networks, a first radio cell 11 is associated or related to a first mobile communication network 100, a second radio cell 12 is associated or related to a second mobile communication network 200, and a third radio cell 13 is associated or related to a third mobile communication network 300.

[0108] Schematic, each of the three radio cells 11, 12, 13 detected or “seen” by user equipment 20 represents a base station entity: (typically but not necessarily of the first mobile communication network 100) a first base station entity 111 generates or provides radio coverage of or about the first radio cell 11, (typically but not necessarily of the second mobile communication network 200) a second base station entity 112 generates or provides radio coverage of or about the second radio cell 12, and (typically but not necessarily of the third mobile communication network 200) a third base station entity 113 generates or provides radio coverage of or about the third radio cell 13.

[0109] exist Figure 1 In the diagram, user equipment 20 is shown located within the radio coverage area of ​​the first radio cell 11, the second radio cell 12, and the third radio cell 13 (illustrated by dashed circles). User equipment 20 measures or detects reception status with respect to the plurality of radio cells 11, 12, 13, and subsequently selects a mobile communication network from the plurality of mobile communication networks 100, 200, 300 and / or registers with that mobile communication network.

[0110] According to the present invention, cellular selection criteria used by user equipment 20 for cellular selection are defined. Figure 2 The diagram schematically illustrates the cell selection criteria, representing the different signal strengths measured by user equipment 20 for different radio cells 11, 12, and 13. The vertical axis of the diagram corresponds to signal strength 500 or its indicators (such as field strength values ​​or signal quality parameters). Following mechanisms in conventionally known mobile communication networks, user equipment 20 applies conventionally defined cell selection criteria 510 during the cell selection phase. According to this (conventionally defined) cell selection criteria 510, both the first radio cell 11 and the third radio cell 13 will be considered suitable radio cells (corresponding to the first step of the method of the present invention, in the cell selection phase according to or applying cell selection criteria 510), because the two radio cells 11 and 13 are schematically shown as having or providing (at the location of user equipment 20) signal strengths corresponding to or exceeding cell selection criteria 510. According to the present invention, during the network selection phase (at least in its initial portion, corresponding to the second step of the method of the present invention), when selecting a public terrestrial mobile network during the network selection phase (the first or initial portion), an enhanced network selection criterion 620 is defined and considered. Because enhanced network selection criterion 620 typically requires higher or increased received signal levels or quality (in... Figure 2In this context, by way of indicating, above the conventionally defined cellular selection criterion 510, an enhanced network selection criterion 620 is shown (i.e., the enhanced network selection criterion 620 is particularly restrictive compared to the conventionally defined cellular selection criterion 510), therefore, in the first part of the network selection phase according to the invention, only the third radio cell 13, or more precisely, its associated public land mobile network 300, is considered by the user equipment 20 and by the measurements performed by the user equipment 20. Figure 2 The diagram schematically indicates another criterion corresponding to high-quality criterion 630. As previously mentioned, enhanced network selection criterion 620 (regarding the corresponding radio access technology) corresponds to the signal strength or signal strength level between (conventionally used) cell selection criterion 510 and high-quality criterion 630. Therefore, in Figure 2 In the exemplary case shown, although both the first radio cell 11 and the third radio cell 13 are considered suitable radio cells during the cell selection phase, only the third radio cell 13 (or its corresponding public land mobile network 300) is considered (initially) during the network selection phase (because it is the only radio cell among the three represented that, according to the user equipment 20, corresponds to or exceeds the enhanced network selection criterion 620 regarding the radio access technology under consideration). Figure 1 and Figure 2 Both only show radio cells and mobile communication networks without distinguishing between different radio access technologies. However, it will be understood that this also applies to different radio access technologies; for example, the third radio cell 13 may only exceed the enhanced network selection criterion 620 for one specific radio access technology, but may also include radio cells of another radio access technology provided or generated by the third base station entity 113 (not shown in the text). Figure 1 (or as specifically stated in 2) may not exceed the corresponding enhanced network selection criteria 620 for the application of the other radio access technology, and may also apply to other radio cells 11, 12.

[0111] According to the application, the network selection (i.e. the determination of a suitable radio cell by the user equipment 20 based on the (regularly defined) cell selection criteria 520 with respect to the considered radio access technology) is done in a first step and in a second step, upon initiation of the network selection according to the automatic network selection mode, only such mobile communication networks are considered for the network selection of the user equipment 20 which have or correspond to a reception condition corresponding to or exceeding the enhanced network selection criteria 620. Thereby, by restricting the candidate networks or candidate public land mobile networks (at least in the initial phase of the network selection phase), a higher signal quality or performance of the user equipment 20 can be achieved (if a suitable higher quality public land mobile network can be found in this initial phase of the network selection phase according to the application).

[0112] According to the application, preferably, the high quality criteria 630 are used as enhanced network selection criteria 620.

[0113] Additionally, especially according to the preferred embodiment that the user equipment 20 has a home public land mobile network HPLMN or is associated with the HPLMN, and wherein the enhanced network selection criteria 620 comprise or consider a home operator controlled value set or adjustable by the HPLMN or its operator, it is advantageously possible according to the application that the home operator can influence the network selection procedure of the user equipment 20. The enhanced network selection criteria 620 are especially more restrictive compared to the cell selection criteria 510, or more precisely, compared to considering all reported public land mobile networks with the reported suitable radio cells from the beginning of the network selection phase. As previously mentioned, the enhanced network selection criteria 620 are especially at most as restrictive as the high quality criteria 630.

[0114] According to the present application, it is advantageously possible - at least initially - that the network selection phase is performed in a different way than conventionally known by considering only such radio cells or corresponding public land mobile networks which are at or above the enhanced network selection criterion 620 as target networks. According to the present application, it is not necessarily required that all user equipment (e.g. all of a group of user equipment with e.g. Internet of Things functionality etc.) have to apply - by applying (based on the definition of the cell selection criterion) the enhanced network selection criterion 620 - a value of a network selection criterion which is different from the conventionally defined cell selection criterion 510 (i.e. considering all suitable radio cells for network selection): by defining the enhanced network selection criterion 620 different from the conventionally performed network selection procedure - and especially by the enhanced network selection criterion 620 comprising or considering a home operator controlled value which is set by the HPLMN or its operator or which can be adjusted by it - the home operator (or the operator of the HPLMN, i.e. the operator to which the user equipment 20 "belongs") advantageously can influence the behavior of the user equipment 20, especially of a part of a group of user equipment, in a flexible way. In an example, this is further detailed below: if e.g. a group (e.g. 1000) of user equipment is deployed with respect to a certain task such as providing measurement values etc., and in case e.g. 900 of these 1000 user equipment can be used and operated without any problems based on the implementation of the present application, i.e. using the enhanced network selection criterion 620 as network selection criterion (instead of using or considering all reported suitable radio cells obtained based on the conventionally defined cell selection criterion 510), wherein, however, and despite the (new) definition of the enhanced network selection criterion 620, the actual (field strength) values to be compared to can correspond to the same values (e.g. in dB, i.e. if the enhanced network selection criterion 620 is defined to comprise an additional addend compared to the conventionally defined cell selection criterion 510, wherein, however, the additional addend equals zero (e.g. in dB)), then no modifications have to be applied with respect to these 900 operating user equipment (especially no different network selection values have to be applied artificially compared to the conventionally defined cell selection criterion 510). However, with respect to the remaining 100 user equipment (which do not necessarily operate completely), the present application provides the home public land mobile network with the possibility to apply a more stringent cell selection criterion (compared to using or considering all reported suitable radio cells based on the conventionally defined cell selection criterion 510) by means of the suggested modification definition of the network selection criterion, i.e. the enhanced network selection criterion 620, resulting in a reduced failure rate of such user equipment when communicating with the respective mobile communication network to which it is connected.

[0115] According to the present application, since only (mobile communication) networks that have passed the (to be applied) network selection criteria are considered initially in the network selection procedure, preferably only the modification with respect to the initial part of the network selection procedure (i.e. corresponding to the second step of the inventive method) exists. However, if no public land mobile network is found in this initial part of the network selection procedure, the later part of the network selection procedure (i.e. corresponding to the third step of the inventive method) and all subsequent specified procedures with respect to network selection can remain unchanged while the desired behavior is achieved.

[0116] According to the present application, therefore, it is proposed to introduce and apply a new initial stage or part of the network selection procedure (second step of the inventive method), i.e. new, radio technology related selection levels (enhanced network selection criteria 620; in terms of absolute values or offset values according to the radio access technology), which can be provided by a signaling means from the HPLMN or retrieved from corresponding fields on the SIM maintained by the HPLMN. During the selection procedure, this or these selection levels are applied to the networks in the PLMN list.

[0117] The new selection levels (NSL, or enhanced network selection criteria 620) can be stored as absolute numbers or offset values with respect to the high quality level (high quality criteria 630) or the cell selection criteria (regularly used cell selection criteria 510). The new selection levels (enhanced network selection criteria 620) should only be applied if they are in the range between the HQ level (high quality criteria 630) and the cell selection criteria (regularly used cell selection criteria 510). This ensures that no changes are required on the lower layer (i.e. AS - Access Stratum) since the regular information reported to the NAS (i.e. signal quality indications based on measurements performed by the user equipment 20) is sufficient.

[0118] A variant is preferred, which provides an offset (i.e. an additional value added to the definition of the regular defined cell selection criteria 510 or subtracted from the definition of the high quality criteria 630) to be applied or used in the new initial stage or part of the network selection procedure (second step of the inventive method). After the new initial stage or part of the network selection procedure according to the present application (second step of the inventive method), the network selection procedure can remain unchanged with respect to the regular procedure since in this later network selection procedure all reported suitable radio cells are considered.

[0119] According to the present application, the network selection stage is initiated as follows:

[0120] - at switch-on or recovery from lack of coverage, select the last registered PLMN with field strength higher than NSL (enhanced network selection criteria 620) or an EPLMN (Equivalent Public Land Mobile Network) to the last registered PLMN with field strength greater than NSL (enhanced network selection criteria 620) or, as an option configured on the SIM, select the available HPLMN with field strength greater than NSL (enhanced network selection criteria 620) or the highest priority EHPLMN with field strength greater than NSL (enhanced network selection criteria 620);

[0121] - if no such network is available, or in the case of reselection, the further step is:

[0122] - the available HPLMN with field strength greater than NSL (enhanced network selection criteria 620) or the highest priority EHPLMN with field strength greater than NSL (enhanced network selection criteria 620);

[0123] - each PLMN / access technology combination (in order of priority) in the "User Controlled PLMN Selector by Access Technology" data file in the SIM with field strength greater than NSL (enhanced network selection criteria 620);

[0124] - each PLMN / access technology combination (in order of priority) in the "User Controlled PLMN Selector by Access Technology" data file in the SIM or stored in the ME with field strength greater than NSL (enhanced network selection criteria 620);

[0125] - other PLMN / access technology combinations with "high quality" signals received in random order.

[0126] In the case where no network meeting the above criteria is available, further procedures of the network selection phase are applied, in particular the procedures known in the art are applied, i.e. as follows:

[0127] - at switch-on or recovery from lack of coverage, select the last registered PLMN or an EPLMN to the last registered PLMN or, as an option configured on the SIM, select the available HPLMN or the highest priority EHPLMN;

[0128] - then:

[0129] - the available HPLMN or the highest priority EHPLMN,

[0130] - each PLMN / access technology combination (in order of priority) in the "User Controlled PLMN Selector by Access Technology" data file in the SIM;

[0131] -- each PLMN / access technology combination stored in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) or in the ME (in priority order);

[0132] -- other PLMN / access technology combinations in order of decreasing signal quality.

[0133] As already mentioned, according to an embodiment of the application, during the initial period or phase of the network selection procedure, the high quality criterion is applied as an enhanced network selection criterion 620. As such, no new parameters on the SIM are required and only the network selection procedure is changed in the same way as described above (i.e. the NSL is replaced by the high quality criterion (enhanced network selection criterion 620)). According to a further variant of this embodiment, a control flag (i.e. an indication carrying basically one bit of information) is additionally introduced to control whether the network selection procedure follows or applies the new procedure according to the application or the conventionally known procedure. The control flag is in particular provided by a signalling means from the HPLMN or retrieved from a corresponding field on the SIM maintained by the HPLMN.

Claims

1. A method for implementing network selection by a user equipment (20) in a radio environment comprising a plurality of radio cells (11, 12, 13) of a plurality of mobile communication networks (100, 200, 300), each of these radio cells (11, 12, 13) being respectively associated to at least one mobile communication network of the plurality of mobile communication networks (100, 200, 300), wherein the user equipment (20) measures or detects reception conditions with respect to the plurality of radio cells (11, 12, 13) and subsequently selects and / or registers to a mobile communication network from the plurality of mobile communication networks (100, 200, 300), wherein cell selection criteria (510) are defined with respect to cell selection by the user equipment (20), wherein a radio cell of a considered radio access technology is considered as a suitable radio cell in case the corresponding reception conditions measured by the user equipment (20) correspond to or exceed the cell selection criteria (510) with respect to the considered radio access technology, wherein a predefined enhanced network selection criterion (620) can be applied with respect to network selection by the user equipment (20), wherein the method comprises the following steps: - in a first step, determining suitable radio cells of a considered radio access technology by the user equipment (20) based on the cell selection criteria (510) with respect to the considered radio access technology, - in a second step, upon initiation of network selection according to an automatic network selection mode, only considering for network selection of the user equipment (20) such mobile communication networks corresponding to suitable radio cells of the considered radio access technology having or corresponding to reception conditions corresponding to or exceeding the enhanced network selection criterion (620), wherein the user equipment (20) has or is associated to a Home Public Land Mobile Network, HPLMN, and wherein the enhanced network selection criterion (620) comprises or considers a home operator controlled value set or adjustable by the HPLMN or its operator, wherein the enhanced network selection criterion (620) is more restrictive than the cell selection criteria (510) lacking a home operator controlled component.

2. The method according to claim 1, wherein the enhanced network selection criterion (620) is at most as restrictive as a high quality criterion (630), wherein: - with respect to Global System for Mobile Communications, GSM, as a radio access technology, the high quality criterion (630) corresponds to a signal level associated to high quality reception with a public land mobile network according to 3GPP standardization, - with respect to Universal Mobile Telecommunications System, UMTS, as a radio access technology, the high quality criterion (630) corresponds to a signal level associated to high quality reception with a public land mobile network according to 3GPP standardization, - with respect to Long Term Evolution, LTE, as a radio access technology, the high quality criterion (630) corresponds to a signal level associated to high quality reception with a public land mobile network according to 3GPP standardization, - with respect to New Radio, NR, as a radio access technology, the high quality criterion (630) corresponds to a signal level associated to high quality reception with a public land mobile network according to 3GPP standardization. -- for UMTS Terrestrial Radio Access Network, UTRAN, as radio access technology, Evolved UMTS Terrestrial Radio Access, E-UTRA, Narrow Band Internet of Things, NB-IoT, or New Radio, NR, in 5G systems, the high quality criterion (630) corresponds to: a respective signal level associated with the high quality criterion according to 3GPP standardization, which triggers reporting of a respective public land mobile network as high quality public land mobile network at a cell selection stage.

3. The method according to claim 1, wherein the home operator controlled value of the enhanced network selection criterion (620) corresponds to: -- an offset value additionally reserved compared to the cell selection criterion (510), or -- an absolute value.

4. The method according to claim 1, wherein the home operator controlled value of the enhanced network selection criterion (620) or an indication that the high quality criterion (630) is used as the enhanced network selection criterion (620), -- is stored in the user equipment (20), and / or -- is provided or transmitted to the user equipment (20) by the HPLMN or its operator by means of using over-the-air transmission methods.

5. The method according to claim 1, wherein determining by the user equipment (20) in the second step a mobile communication network corresponding to a suitable radio cell of the considered radio access technology based on the enhanced network selection criterion (620) is -- performed after switching on the user equipment (20), or -- performed after recovering from lack of coverage, or -- performed at a user triggered network reselection, or -- performed periodically in case of the user equipment (20) in a visited communication network.

6. The method according to claim 1, wherein in a third step after the second step - in case of lack of a mobile communication network having or corresponding to a received condition corresponding to or exceeding the enhanced network selection criterion (620) corresponding to a suitable radio cell of the considered radio access technology - network selection is continued based on the cell selection criterion (510) instead of the enhanced network selection criterion (620).

7. A user equipment (20) for implementing network selection within a radio environment comprising a plurality of radio cells (11, 12, 13) of a plurality of mobile communication networks (100, 200, 300), each of the radio cells (11, 12, 13) being associated to at least one mobile communication network of the plurality of mobile communication networks (100, 200, 300), respectively, wherein the user equipment (20) comprises a processor, wherein the processor is configured to measure or detect reception conditions with respect to the plurality of radio cells (11, 12, 13) and to subsequently select and / or register to a mobile communication network out of the plurality of mobile communication networks (100, 200, 300), wherein cell selection criteria (510) are defined with respect to cell selection by the user equipment (20), wherein a radio cell of a considered radio access technology is considered to be a suitable radio cell in case the corresponding reception conditions measured by the user equipment (20) correspond to or exceed the cell selection criteria (510) with respect to the considered radio access technology, wherein at least one predefined enhanced network selection criterion (620) can be applied with respect to network selection by the user equipment (20), wherein the processor is configured to cause: - determining suitable radio cells of a considered radio access technology based on the cell selection criteria (510) with respect to the considered radio access technology, - in case network selection is initiated according to an automatic network selection mode, only considering such mobile communication networks corresponding to suitable radio cells of a considered radio access technology for network selection of the user equipment (20) having or corresponding to reception conditions corresponding to or exceeding the enhanced network selection criterion (620), wherein the user equipment (20) has or is associated with a home public land mobile network, HPLMN, and wherein the enhanced network selection criterion (620) comprises or considers a home operator controlled value set or adjustable by the HPLMN or its operator, wherein the enhanced network selection criterion (620) is more restrictive compared to the cell selection criteria (510) lacking a home operator controlled component.

8. A system for implementing cell selection by a user equipment (20) in a radio environment comprising a plurality of radio cells (11, 12, 13) of a plurality of mobile communication networks (100, 200, 300), each of these radio cells (11, 12, 13) being respectively associated to at least one mobile communication network out of the plurality of mobile communication networks (100, 200, 300), wherein the user equipment (20) is configured to measure or detect reception conditions with respect to the plurality of radio cells (11, 12, 13) and to subsequently select a mobile communication network and / or register to a mobile communication network out of the plurality of mobile communication networks (100, 200, 300), wherein with respect to the cell selection by the user equipment (20) a cell selection criterion (510) is defined, wherein a radio cell of a considered radio access technology is considered to be a suitable radio cell in case the corresponding reception condition measured by the user equipment (20) corresponds to or exceeds the cell selection criterion (510) with respect to the considered radio access technology, wherein with respect to the network selection by the user equipment (20) at least one predefined enhanced network selection criterion (620) can be applied, wherein the system is configured such that: - a suitable radio cell of a considered radio access technology is determined by the user equipment (20) based on the cell selection criterion (510) with respect to the considered radio access technology, - in case the network selection is initiated according to an automatic network selection mode, for the network selection of the user equipment (20) only such mobile communication networks corresponding to suitable radio cells of the considered radio access technology are considered which have or correspond to reception conditions corresponding to or exceeding the enhanced network selection criterion (620), wherein the user equipment (20) has or is associated with a home public land mobile network, HPLMN, and wherein the enhanced network selection criterion (620) comprises or considers a home operator controlled value set or adjustable by the HPLMN or its operator, wherein the enhanced network selection criterion (620) is more restrictive compared to the cell selection criterion (510) lacking a home operator controlled component.

9. A program product comprising computer readable program code which, when executed on a computer and / or on a user equipment (20), causes the computer and / or the user equipment (20) to perform the method according to any one of claims 1 to 6.

10. A computer readable medium comprising instructions which, when executed on a computer and / or on a user equipment (20), cause the computer and / or the user equipment (20) to perform the method according to any one of claims 1 to 6.

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