MXPA97001216A - Celu mobile communications system - Google Patents

Abstract

The present invention relates to a cellular mobile communication system comprising a number of base radio stations (BS) and a number of mobile stations (MS), wherein the system comprises a number of cells that are placed in by the minus two different preference layers. Connections carried in the communications system can be handled through one cell to another and at least one signal is monitored. At least one threshold is provided at least for each cell in the lower layers, or at least one signal parameter. The system further comprises a means for deciding and controlling delivery decisions comprising a priority rank arrangement based on the number of criteria one of which is based on the understanding between a supervised value (Io) and a signal parameter, with the threshold value (Iotr) of the service cell and a second based on a comparison of the supervised value of a signal parameter (Ii) with the corresponding threshold value (Iitr) for a neighboring cell, where the deliveries are regulated by the priority range arrangement so that systematic upward as well as downward access is obtained between

Description

and i "CELLULAR MOBILE COMMUNICATION SYSTEM" FIELD OF THE INVENTION The present invention relates to a cellular mobile communication system with radio base stations and mobile stations. The system comprises a number of cells that are placed in two or more different layers or levels, and the connections of the mobile station can surrender from one cell to another. The system comprises a means for monitoring and / or measuring at least one signal parameter of at least those cells that are not in the upper layer and at least one threshold value is provided for the signal parameter for at least each one of the cells. The system also comprises a means for controlling deliveries between different cells. The invention also relates to a method for controlling deliveries in a communication system Cellular mobile, where the cells are placed in at least two different levels or layers. A communication system of this kind comprises a number of base stations that are usually organized in a network. Each base station gives service to a geographical area that is called a cell. The geographical area can be said to be provided by radio propagation properties of the base station and the surrounding radio base stations. The system further comprises one or more mobile stations and when a mobile station is moved, the mobile connections can be delivered from one cell to another which is known as a delivery. In this context, however, a number of factors play an important role since it is of considerable importance that the most appropriate cell is selected when a delivery is carried out, both under normal circumstances and under more or less extraordinary circumstances. Therefore, it is extremely important that the cells are organized in the most appropriate manner.

CURRENT STATE OF THE TECHNIQUE A number of attempts have been made to provide a cellular mobile communication system with a cell structure that is appropriate. A known system applies a so-called "umbrella" cell treatment, the different cell layers, that is, the preference layers or priority layers, are placed in this case in accordance with the selection and placement of the radio base stations. The powerful base stations with high antennas then constitute so-called umbrella cells where the base stations of low power, eg, mounted at street level form the so-called "micro-cells", while also the calls "pico-cells" can be placed which then, v.gr, can be mounted inside. Therefore there are either two or three layers of different cells. In this case, the mechanism of normal cell selection, of location, is the mechanism responsible for providing the desired behavior. However, no logic is dedicated to this object. The intention with the use of so-called "umbrella" cells is to provide a safety net for the normal cell network by connecting coverage holes, providing reserve capacity in call establishment procedures and having the rescue function during disturbances or alterations of radio etc. The object with the micro-cells (in relation to the umbrella cells or normal cells) is to provide the main capacity, particularly in high density traffic area. The system with the umbrella cells therefore directs the traffic to the appropriate cells in the appropriate layer, in order to ensure call continuity and to ensure a satisfactory call setup procedure. The structure of the cell with umbrella cells without dedicated logic, however, does not work satisfactorily when the base stations belonging to different layers of are placed close to each other. The cell selection mechanism, the location, will then result in a number of unnecessary deliveries such as from a micro-cell to an umbrella cell even when the micro-cell provides suitable radio conditions. This is illustrated in Figure 1 which shows two micro-cells under an umbrella cell. For the mobile station MS 1, the CA micro-cell will provide the highest signal strength. Consequently, that cell will carry the connection. The mobile station MS 2 will be radio protected from both the micro-cell base stations BS 1, BS 2. In this case, the cell C and umbrella fills its object and provides coverage where the micro-cells CA 'CB they stop doing it However, for the mobile station MS 3, the micro-cell base station BS 2 remains in the line of sight and therefore must be able to carry the connection without problems. However, the BSy base station of the umbrella cell that also remains in the line of sight, has a signal strength that is higher and will therefore take over the connection. Also, during, eg, radio disturbances and congestion connections in the call establishment may unnecessarily be taken or retained by the umbrella cell or • may generally be retained or taken over by less appropriate cells. This will lead to wasted capacity that can lead to loss of connections, etc. In other words, the occupation of less appropriate resources will increase. In addition, efficient frequency applanation and efficient hardware sizing is difficult. Also, the number of deliveries is unnecessarily high which results in a considerable burden on the switches and thus a risk not despicable of losing connections. In another known system, the different cell layers are provided with different properties and a priority has been given to the deliveries to the umbrella cell layer which is higher than the property of the cell. delivery due to the number of other functions of the radio network. Interconnections with a number of radio network functions have been provided with different priorities. A higher layer has then been provided with a higher priority in the case of alternations of call setup congestion, etc. In this way, the pass between the layers is activated by means of a number of different extraordinary events such as eg, congestion during the installation of the call and poor quality (high BER, error rate of Bit). Also in this case, connections are not always directed to the most appropriate cell layer. In addition, the cover holes have not been adequately covered. Great Britain Patent Number A-2 242 806 describes a cellular system comprising macro-, and icro-cells. Deliveries are always made through the macrocell layer in order to avoid unnecessary deliveries from the macrocell to the microcell and back again. A delivery to an inner layer is simply carried out when the link from the equipment to the base station associated with the underlying microcell has a quality that exceeds the predefined criterion for a time interval that exceeds a predetermined time interval. The delivery from one microcell to another microcell therefore never happens. In this way also in this case the "wrong" resource will be occupied to a considerable degree. Patent Number O-A1-92 / 02105 of a cellular radio system is known. A delivery initiation system comprises a means for determining the distance of a mobile station to a base station of a cell and a means for measuring the signal strength to determine the trajectory of the mobile station. With the use of the location determination system it is possible, with the use of the information stored therein and the character of the signal over the calculated distance, to determine the location of a mobile station within a micro-cell. The system further comprises a means for storing pairs of information in the location and character of the location signal and a means for forming a current pair comprising these parameters for a mobile station that is moving and a means for comparing stored parameters. with the current parameters. However, also in this case, wrong resources will be taken leading to inefficient use of resources and increasing the risk of losing connections, etc.

COMPENDIUM OF THE INVENTION An object of the present invention is to provide a mobile cellular communication system similar to that to which reference has been made initially, wherein the cells are organized in layers preferably in such a way that the resources of the system are used optimally. A further object of the invention is to provide a system through which it is ensured at the same time that the traffic is directed to the cells for which the network is dimensioned, that there is a free capacity in the cells to provide spare capacity during the installation of the call and to ensure that there is free capacity in the cells so that they act as rescue cells at the same time to ensure call continuity and successful call installation. It is also an object of the invention to direct the connections to the cells that can confidently take charge of the connection and connect the cover holes. Still another object of the invention is to allow efficient frequency applanation and efficient sizing of the system hardware. Still another object of the invention is to keep the number of deliveries at a low level and to minimize the load on the switches as well as to minimize the risk of losing connections. These as well as other objects are achieved through a system of the aforementioned kind, comprising a control means consisting of a rank arrangement that is based on a number of criteria. A criterion is based on a comparison of the current supervised value of a signal parameter of the serving cell with the threshold value provided for the serving cell and a second criterion is based on a comparison between a comparison of the current supervised value of a signal parameter of a neighbor cell with the threshold value determined for that neighbor cell. The deliveries between the cells are regulated by the priority range arrangement in such a way that a systemic pass is obtained between the cells or layers or cell levels, as well as to pass upwards and downwards between the layers. It is also an object of the invention to provide a method for controlling the delivery procedure in a cellular mobile communication system wherein the cells are placed by hierarchy in at least two layers or different levels so that the system resources are used in the optimal way and so that the traffic connections are directed towards the appropriate cells according to the sizing of the system, etc. These and other objects are achieved through a method where the priority range is carried out based on a means of criteria. The method comprises the steps of: entering a threshold value for the service cell; enter a threshold value for at least every cell that is not in the upper layer; monitor at least one signal connection parameter for the serving cell; monitor at least one signal connection parameter for a number of neighboring cells; compare the supervised current value of the signal parameter for the serving cell with the threshold value for the serving cell; compare the supervised value of the signal parameter for the neighboring cells with the threshold value for the respective cell; carry out the deliveries according to the priority range arrangement in such a way that a systematic pass is obtained between the cells or cell layers, as well as to pass upwards and downwards between the cell layers. The method can be modified with particularity so that it comprises any modality or any combination as it is further evaluated in relation to the system itself. A number of advantageous embodiments are provided, v.gr, by the features of the appended claims. With the cellular system according to the invention, the connections will be systematically directed towards a lower layer and during radio alterations and call installation congestion, among others, there will be a systematic redirection of connections with the cells that can deal with them confidentially. . Through the introduction of a threshold for each cell a systematic way is obtained so that there is passage between the layers. The threshold, e.g., may be for the intensity of the signal, the loss of the trajectory or both. Other signal parameters are also possible. Which signal parameter (I) will be used depends on the general delivery strategy applied by the system. In a specific modality, the strategy called Delivery Helped by Mobile Station (MAHO) is used. Then, the mobile station carries out measurements of the signal strength (and / or other) in the radio energy transmitted from a number of neighboring base stations. The mobile station transmits these measurements to the base station that delivers them to the unit responsible for the decision logic. However, other delivery strategies, such as NCHO, may also be used.

(Controlled Delivery by Network) where the mobile station is passive, MCHO (Delivery Controlled by Mobile Station) where the mobile station both measures the intensities of the received signal, etc. how he makes decisions regarding delivery. In a specific modality, the Time Division Multiple Access (TDMA) is used. With the system according to the invention, the threshold is used for the upward as well as downward pass, that is, to pass into the cells of a higher preference level as well as towards the cells of a lower preference level. , or that have a lower priority. According to a specific modality, the threshold is modified with the hysteresis that is added or subtracted according to the direction of movement. In the normal case, eg, when extraordinary events or simultaneous functions are not required, a condition for moving to a higher layer is that if the signal strength (in this specific case) monitored from the serving cell Currently the connection, that is, the service cell decreases less than the threshold for that specific cell (in an advantageous mode with the hysteresis subtracted), the system amplifies the set of neighboring cells that are eligible for delivery to cells in a Higher hierarchical layer. However, the cells in the highest layer have a lower priority of the cells in the current layer and in the lower layers. A condition for moving to a lower layer is that if the intensity of the supervised or measured signal for a neighbor cell in a lower hierarchy layer increases above the threshold for that cell (in an advantageous mode with the hysteresis added), the cell will be added to the set of neighboring cells that are eligible for delivery. This cell will have a higher priority than the cells in the current layer or in the upper layers. In the advantageous modalities, Interactions with other radio network functions are carried out. Examples of other radio network functions are intra-cell delivery, subjacent-underlying sub-cell delivery, amplified scale, directed re-trial, assignment to another cell, alarm delivery, etc. Particularly, one or more of these or other radio network functions are provided with different priorities one relative to the other and to the normal delivery functions. This is particularly relevant when different radio network functions propose different types of actions, simultaneously. In particular with the invention, the mobile stations can be systematically directed towards the lowest possible layer. This saves the ability of the upper layers for extraordinary events, such as eg, coverage spaces or call setup congestion, etc.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described more fully in a non-limiting manner with reference to the accompanying drawings in which: Figure 2 illustrates in a very schematic way a mobile communication system, Figure 3 illustrates a diagram Flow of the main flow in the location procedure, Figure 4a illustrates a table for the rank order in the two-layer structure where the serving cell is in the lowest layer and the signal strength for the cell that The service is below the threshold, Figure 4b illustrates a table for the structure of Figure 4a, but where the serving cell is in the lower layer and the signal strength of the serving cell is above the threshold, Figure 4c illustrates a frame for the structure of Figure 4a, but where the serving cell is in the upper layer (forming an "umbrella"), Figure 5a illustrates a for the range order in the three-layer structure where the serving cell is in the lowest layer and the signal strength of the serving cell is below the threshold, Figure 5b is a table related to the same structure as in Figure 5a, but where the signal strength of the serving cell is above the threshold, Figure 5c is a table that relates to the same structure as in Figure 5a, but in where the serving cell is in the second layer and where the signal strength of the serving cell is below the threshold, Figure 5d is a table that is related to the same structure as in Figure 5c, but where the signal strength of the serving cell is above the threshold, Figure 5e is a table related to the structure of Figure 5a, but where the serving cell is in the third layer or the layer further up, Figure 6 il ustra how the categories of delivery candidates are ordered, in a specific scenario.

DETAILED DESCRIPTION OF THE INVENTION The cellular communication system comprises a cell structure in which the cells are placed in at least two layers in a hierarchical manner.

Figure 2 illustrates in a very schematic way a cellular mobile communication system, in this case, the GSM system. Figure 2 is shown only for reasons of brief explanation, indicating very schematically a part of a mobile cellular system and certainly, in no way has a limiting effect on the invention. The BSS Base Station System comprises a number of Base Transceiver Stations BTSs where a group of BTSs is controlled by a BSC Base Station Controller and a number of Base Station Controllers BSCs are controlled by a Switching Center Mobile MSC of the SS Switching System that controls calls to and from a network such as eg, the PSTN Public Switched Telephone Network, the PLMN Public Land Mobile Network, the Public Switched Data Network of the PSPDN Pack, the Network of Public Data Switched by Circuit, the ISDN Integrated Services Digital Network or any other network. The Switching Center also includes a Visitor Location Registration VLR comprising a Data Location Area, a HLR Home Location Register with the date on the subscribers, etc. which, however, is not related to the present invention. WTO indicates a WTO Operation and Maintenance Center in a manner known per se. The lines of ions in the Figure are related to the transmission of information and the continuous lines are related to the connections of call and the transmission of information and the lines of scripts are also related, in the case of cells, with alternative networks, functions alternatives or optional (of SS, etc.). In accordance with the invention, a threshold is introduced, at least for each cell that is not in the upper layer. This is a characteristic for the provision of a systematic way to pass between the layers. The threshold can be for the signal strength or for the path loss or for both or for any other parameter that depends on the general delivery strategy of the system (among others). In the modalities described below, only those cases that relate to a threshold of signal intensity will be described. This, however, is not in any way limiting and the treatment when v.gr., a path loss threshold or other threshold is applied or both are essentially identical. The threshold is used to pass up as well as down in the hierarchy of the cell. According to the advantageous embodiments, the threshold for passing up and down is generally referred to as a threshold. However, it can be modified with a hysteresis that is added or subtracted according to the direction of movement. In a generalized case, the condition to pass up, that is, from a lower layer to a higher layer is that if the intensity of the signal measured from the cell currently serving the connection, that is, the cell When the service is below the threshold for that cell (particularly with a hysteresis subtracted), the system amplifies the set of neighboring cells that are eligible for delivery to cells in a higher hierarchical layer. The cells in the upper layer will have a lower priority than the cells in the current layer and in any lower layer. The corresponding condition to pass downward, i.e., from an upper layer to a lower layer, ie, if the intensity of the signal measured from a neighboring cell in a lower hierarchical layer increases above the threshold for that cell (particularly with the hysteresis added), that cell will be added to the set of neighboring cells that are eligible for delivery. That cell will have a higher priority than the cells in the current layer or in a higher layer. Therefore, the cell structure can be said to be a hierarchical cell structure. Through it, the location function is carried out and modified. The basic range is done over different cell levels and a basic range list is formed. This list includes a number of candidates and the list is organized depending on different conditions. The organization can be regulated by a table and eg, provided as the permanent exchange data. The candidates on the list are also divided into categories, which will be discussed further below. Some of the concepts are explained below. The basic range means the range of the cells based on the strength of the signal and / or the path loss criterion (or any other appropriate parameter). The location is related to the procedure that, using the measurement and parameter data, proposes the most appropriate connection. The exit from the location procedure is a list of possible candidates, the list of candidates to be delivered or assigned. Urgency refers to a condition that requires an urgent delivery. This is present if the quality of the transmission is too low, if the Timed Advance (TA) is too large, if the time dispersion is too large or if any other criteria for extraordinary radio events is satisfied, depending on which of the Physical measurements are available for the radio connection. As for the umbrella cell concept, a cell can be defined as an umbrella cell. An umbrella cell is a cell in a network of large cells that spans the normal network. However, this invention is based on the concept of hierarchical cells. There will usually be a large number of different requirements in the BSC Base Station Controller, for the location algorithm. The location algorithm is here defined particularly as a joint term for the selection of cell and its cell, including all types of intra-cell channel change. The location function, in general, describes a functionality comprising one of many functional components of the location algorithm. Next, a delivery generally describes a channel change between the cells. Next, reference will be made to the parameters or quantities measured. Those are quantities that are monitored in the MS (in a specific modality), the Mobile Station and in the BTS by means of a measuring device, eg, as specified in the GSM recommendations. When the Mobile Station Assisted Delivery MHO strategy is applied, the measured or supervised quantities in the MS Mobile Station are transferred to BSC via air. The quantities measured or monitored at the BTS Base Transceiver Station are transferred to the BSC. However, the ways in which the measures are carried out, or information is given about them, etc., depends on the specific delivery strategy used. In a specific embodiment, as will be discussed further below, the measures that are considered include uplink and downlink signal strength and uplink and downlink signal quality measures. As already stated, of course there are a number of other alternatives. In the same modality disclosed, the amounts refer to the quantities used in the MS, the Mobile Station. The values disclosed are transferred from the MS to the BSC, Base Station Controller through the air. The reports are considered in the described modality and include Timed Advance, TA, which come from the BTS. As in any known system, filtration may be required. It may be necessary to standardize stochastic variations, etc. this however, will not be discussed further. In one embodiment, such as in a number of known systems, the evaluation of the cell and sub-cell can be carried out together in a cycle that is completed at least within a period of SACH (Slow Associated Control Channel) and each SACCH period is repeated unless certain mechanisms prevent the selection during a time interval. This, however, is only one example among many others. As will be discussed more fully below, the selection of the cells is based on the rank in the range list that is established. The preference rank list is established at the beginning of the cycle according to the basic principles determined. The final cell selection is obtained through the reorganization of the list, according to the different principles that depend on different criteria that will be discussed further below. The location function continuously monitors and evaluates the radio environment and suggests the most favorable cell (and / or sub-cell). Based on a number of measurements of measured and disclosed quantities, a list of candidates is produced. This list of candidates comprises cells in the order of preference. In an advantageous embodiment, the quality of the signal and the synchronization advance are continuously monitored and evaluated together with the calculations of the signal strength (which includes possible filtering functions). The candidate list that is produced, e.g., in a known manner will be sent to the cell process handler to be used for channel assignment. Generally, the location comparison and the preparation of the candidate list in accordance with the predetermined pre-requisites starts immediately after the initiation of the location algorithm. Once the candidate list is received by the function that manages the candidate list, candidates are used to try to assign the channel according to the information in each candidate entry. In the attempts, the candidates are used in the order in which they are placed on the list, eg, with an intent for each candidate. If the channel assignment to a specific candidate fails (eg, in the case of a congestion), the next candidate on the list must be used for the next attempt and so on until the channel has been successfully assigned or all the candidates have been tested unsatisfactorily. This is a procedure that is generally known per se, which of course could be more or less modified, but also completely exchanged through another procedure, without deviating from the scope of the invention. With particularity, the interactions with other functions of the radio network, such as the intra-cell delivery, the subjacent-subjacent subcell delivery, the amplified scale, the directed re-trial, the assignment to another cell, the delivery of the alarm , etc. they will be discussed later. This is particularly relevant when several functions of the radio network propose different types of actions at the same time. The cell candidates, according to the invention, are classified into categories depending on a number of factors, in one modality into three factors, namely the layer, the range compared to the cell serving and a measured parameter such as the intensity of the signal (or loss of trajectory or similar) compared to the threshold. Each combination of the results of the evaluations of the radio network control functions is connected to a defined category list that describes the precedence of the candidates in a so-called "delivery candidate list". Figure 3 illustrates in a general manner the main flow of the location procedure in a specific modality. The TA Timing Advance reports and measurements are filtered in to, where among other things the bit error rate, etc. is checked. In b, the basic range is carried out which will be discussed more fully below. In c, the hierarchical cell level evaluations are carried out, that is, the evaluations as to whether a cell is above / below a threshold, etc.

Then follows (d) the evaluations in relation to other Functions of the Radio Network, such as, eg, emergency conditions, superjacent / underlying evaluation, intra-cell evaluation, etc. These so-called flags are introduced in the tables and constitute examples of the conditions that can be controlled or modified. Then follow the organizational procedure that depends on a - d and where a list of candidates is organized. Then, continue eg, as in any known system or location flow. In a specific embodiment described in the initiation procedure, the BSC Base Station Controller block is started, the channel assignment process is started and the frames are read. The initiations are carried out during the activation of a single location or a cell eg during the delivery at the reception in the BSC Base Station Controller of a complete delivery signal from the MS (Mobile Station) in the delivery procedure. Among others, the parameter layer is read, better / worse, above / below the threshold. The initiation block also includes the process called CPH (Call Process Manager) that handles BSC (Base Station Controller) signals, the structure of the data, the update and processing of the parameters, eg, intensities of signal, etc. reports to the case of active location. The procedures to which reference is made are mentioned in a simplified manner, since most of the steps in the procedure correspond to the procedures that are carried out in the known cellular mobile communications systems, eg, with the cells of conventional umbrellas. e.g., the filtering functions are carried out in a manner known per se, etc. The basic range procedure will be discussed further below in relation to two examples of the establishment of a priority table based on the hierarchical structure comprising two and three levels, respectively. In the location procedure, measurement reports, e.g., can be made directly in the location procedure itself and placed in a buffer. However, they are preferably made directly. Both conditions of urgency and of superjacent / underlying evaluation and intra-cell evaluation are handled in a manner similar to the known cellular systems comprising the umbrella cells. After the intra-cell evaluation follows an organization procedure. This is different from the known topics and will be further discussed and illustrated later. The organization procedure may comprise a preparation procedure after which the list is sent in a manner known per se, as well as the administration of the allocation response which is carried out in any appropriate manner. In one embodiment, the organization procedure, e.g., may comprise four procedures wherein the reference frames are constructed for cells in the parameter list, e.g., signal strength, etc. for cells in the range list. The cells in the parameter list to the cells in the measurement value list. The cells in the list range to cells in the parameter list and cells in the range list to cells in the measurement value list. This procedure is followed by the second procedure where each cell in the range list is fragmented according to three parameters, namely (as referenced above) 1 - layer 2 - better or worse than the cell that gives service, and 3 - if it is above or below its own threshold. Then, the cells are classified into a three-dimensional data structure. The range list is advanced in the order of the range value.

The entries in the table are in any appropriate way that is usually known per se. Particularly, in relation to a modality, the concept of known umbrella cell can be said to be extended to a hierarchical cell structure. Through this, e.g., can be used to cover the holes in the cover from the normal cells. According to one modality (which may or may not include a hysteresis threshold or a second threshold), the transitions between the normal cells and the "umbrella" cells are controlled by the threshold (the threshold I ^ r of the intensity of the signal) and the modified threshold, that is, the threshold of the intensity of the modified signal with the hysteresis H ^ r. In a specific modality, these parameters (the first and second thresholds, are defined for normal cells, that is, not for the cells that form the so-called "umbrellas." In this specific case, this leads to a list of basic range (among others which are referenced in Figure 3) which comprises 7 categories.This is illustrated in Figures 4a to 4c.For cells at level 1 (the lowest layer) in this mode, the so-called normal cells, the intensity of the signal is compared with the threshold value In relation to the modality described here "above" for the cells that provide service means that the intensity of the signal IQ >; Io ^ r ~ H0 ^ "r And" below "for the cells that give service means that the intensity of the signal IQ <I ^ -ro -HtrQ where for neighboring cells" above "means that the intensity of the signal I-¡_> Ii * -r + while "below" means that the intensity of the signal I¿ <Iitr + H-tr.The list of candidates is organized according to different conditions. one or more categories that could normally be left on the list can be removed from the list, and categories, etc. can be added, and the categories are placed in an appropriate order according to the specific needs and requirements. This table forms permanent exchange data but can also be changeable and possible to correct, etc. The table includes a part that is referred to as conditions Conditions, v.gr ., will be according to the following Table which will be referred to below as Table A: 1 - . 1 - Assignment Request that was arrived at, 2 - State AW (meaning Assignment to the worst cell), 3 - Urgency of Excessive Timed Advance (TA), 4 - Poor Quality Urgency 5 - Subjacent Cell Change -Subjacent, 6 - Intra-cell delivery. (Table A) Of course, other possibilities are also possible / "To conditions as well as there could be less or more than 10 conditions, depending on the specific needs and the specific requirements, the conditions can be true with a" 1", false, indicated as" 0"and finally they can be inapplicable , which is indicated as II _ II 15 The table also relates to different categories. In the tables illustrated in Figures 4a-4c s - means serving cell, 1 bo-cell better in layer one, SS (Cell Intensity) above the threshold, 20 1 bu - better cell in layer one, SS below the threshold, 1 wo-worst cell in layer one, SS above threshold 1 wu - worst cell in layer one, SS below 25 threshold, 2b - cell better in layer 2 2w - worst cell in layer 2 The box in Figure 4a illustrates the cell serving in layer 1 (normal) where the signal strength is below the threshold. 24 different cases are illustrated, in the tables (Figures 4a-4c) a reference is made as to whether the serving cell has a signal strength that is above or below the threshold for the serving cell (see also FIGS. 5a-5e). The tables of Figure 4 have been constituted in accordance with the guide lines that have been provided with a certain order of priority among the different radio network functionalities. This order of priority is provided by the following table, which will be referred to below as Table B: 1 - Normal Delivery 2 - Emergency Advance Temperate TA 3 - Going to a lower layer 4 - Change of Sub-cell 5 - Delivery of Intra-cell 6 - Urgency BQ 7- Going to a higher layer (Table B) The table in Figure 4b illustrates the cell that serves in layer one (normal) and the intensity of the signal that remains above the threshold for 24 cases and finally the table in Figure 4c illustrates the cell serving in layer 2 (this case is related to an "umbrella" cell) for 24 different cases. Particularly it is also possible to divide a number of cases in different cases for conditions of change of their cell which however will not be discussed further in the present. The modality described in the foregoing relates to a case with two layers or cell levels, of course, there may be more layers, then another modality will be described. In this case there are three different cell layers. The hierarchical cell structure according to the invention can be applied to the functionality of the umbrella cell. An umbrella cell functionality provides a second level in a network comprising large cells that logically (and physically) are organized above the network of the original cell and work for it as a backup network. In the present mode, a third level is introduced which logically (and physically places it below the original cell network and comprises small cells.

In one modality, this level forms a network of micro-cells. Here, the first level or lowest level (level 1) or lower level is called the micro-level and the second level or intermediate level is called a normal level or an original level and the third level or higher level can be called a third level or higher level. In general, the intention to assign the mobile stations in the hierarchical cell structure is to fill the first lower level, that is, the mobile station should receive services through a cell in the lowest level or layer possible because this level particularly has the highest capacity. This has the consequence that the mobile station will not always receive service for the best cell from v.gr., a point of view of signal intensity or path loss, but by means of a cell that is good enough and that is in the lowest possible layer. The invention relates particularly to the treatment with a threshold and with a frame system, e.g., it is illustrated in Figure 4, it also allows any other strategy changing the properties eg, which are provided by the table B and to which reference has been made in the foregoing. In addition, the system comprising frames, e.g., in Figure 4, allows different strategies in different layers, e.g., in this way, traffic can be directed to any layer and not only to the lowest, etc. Of course, the invention also relates to networks having more than two or three layers, but since at the beginning it is the same regardless of the number of layers, only the networks comprising a two- and three-layer structure will be described more fully in the present. A hierarchical cell structure according to the invention can relate to both the umbrella cell concept and the cells generally in different layers or levels. Through the introduction of the threshold Iotr of signal strength or a threshold for upward transition below which a transition can occur, transitions to a logically higher level or layer is facilitated. A flag, in a manner known per se which indicates that a delivery to an upper layer cell is permitted must be graduated when the signal strength in the normal serving cell falls below Iotr ~ Hotr- A flag, v. gr., will be referred to as a flag that allows a Higher Level Change. A list of candidates that contains only the best cells according to the basic rank must be sent if the flag is set (and if no other flags are set). If the list is empty, however, that is, there are no better cells; then the mobile station remains in the current cell, that is, in the service cell. However, if after delivery to a higher level cell the signal strength from a lower layer cell rises again above the threshold, then this cell must not become part immediately (according to the modality) specific) of the list of candidates. The signal strength of preference must reach a level somewhat above Itr or the threshold I ^ -r + Htr or a u bal for descending transition in order to obtain a hysteresis effect that will prevent repeated deliveries or so-called "deliveries" of ping-pong ". When the signal strength from the lowest level cell exceeds Itr + H ^ 1", a flag is set (in this specific mode) This flag can be seen as a lower level change allowed. candidates is then sent, which contains the lowest level cell that exceeds Itr + H ^ r. itr and E ^ t here relate to the parameters of the cell and the serving cell uses its own threshold values when evaluating ltr-I_tr (IQ ^ G _ Ho-r) (for a possible movement to a higher level) When the serving cell evaluates the neighbors it uses the threshold values that correspond to the neighboring cells (Iitr + Hitr) If a third level is introduced below the other two levels, the cells at that level will generally have secured traffic, preferably at all other levels, this is achieved if the reasoning above is applied to the lower level. , the lower level is called level 1 For the provision of '"* - a list of candidates is carried out a basic range among all the cells that meet a minimum criterion. After this, a level-oriented rearrangement is carried out. Any cell in the lower layer with a signal strength that exceeds (which refers to a preferred mode) will place a flag indicating that the Lower Layer Change is Allowed, which will make the cell the top candidate in the candidate list. If there are more of these cells, the result of the basic range will be used in the range between them. If the Upper Layer Change flag is set, it is allowed, the assembly of the candidate list continues generally as follows: the cells better than the cell serving the same or higher layer may be candidates, the cells in the same layer take priority through the upper layer cells . The cells between the "best" cells above with a signal strength lower than the threshold allowed for the upper layer change, have a lower priority (in this case there are). In the last category, the top-level cells have priorities above the lower-level cells. This is due to the fact that when going to a lower layer cell with a signal strength lower than the threshold for the allowed upper layer change, it would immediately result in a -. transfer to an upper layer anyway.

This saves two unnecessary deliveries. However, if a flag is urgently placed simultaneously on the flag indicating the change of Allowed Top Layer, then also the worst cells can be appended to the candidate list. The assembly in the list of candidates is provided through a table that implements the priority principle considered above. The table can be supplied as a permanent exchange data that allows the tuning of the algorithm without changing the real code. However, in a modality Alternatively, the table is not permanent but can be changed eg by a command. Of course it is ible to provide means eg to prevent deliveries to lower layer cells under certain conditions, such as in the case of rapidly moving mobile stations, etc. it is also ible to add additional cell types eg, inner cells or pico-cells, etc. Through this it may be necessary to enter more levels in the range of cells list. The thresholds and hysteresis parameters can be graduated according to BSC or by cell level or by MSC level or by system level. In the case of three layers or cell levels, the basic range is carried out through the three cell levels. The candidates in the candidate list, as already discussed, are divided into categories and the intensity of the signal given, the threshold of signal strength and hysteresis and the level of the cells are used to graduate the categories for the neighboring cells. Also, as already mentioned, it does not have to be the signal strength but it could also be path loss, signal strength as well as loss of trajectory or any other convenient parameter. In Figures 5a-5e the tables are illustrated from where the lists of candidates are formed as already mentioned above in relation to the modality comprising two cell layers. First, a basic range is advantageously carried out among those cells that fulfill a minimum criterion of exceeding a threshold value of at least one determined signal parameter.

Then, a hierarchical level evaluation is carried out, that is, a level-oriented rearrangement is carried out. This means that a candidate list is assembled regulated by one or more tables. The examples of these tables are illustrated in Figures 5a-5e. These tables will be explained below. As in the previous TA it is related to the Advance of Timing and AW is related to the Assignment to the worst cell. In the pictures, the number defines the layer, that is, in this case three layers, layer 1, layer 2 and layer 3, where layer 1 is the lowest layer, etc. Better and worse is illustrated through b and w respectively, where o and u mean above and below the threshold respectively, more or less the hysteresis as the case may be, eg, whether the hysteresis is applied or not. If the hysteresis is applied, this can be treated by the location function. As in the modality related to the hierarchical two-layer structure, the table (Figures 5a-5e) comprises a number of conditions, namely: 1 - Assignment assignment to which has been reached and AW status (Assignment to the worst cell ), 2 - Request of assignment to which has arrived and no AW status, 3 - Urgency of Excessive Timed Advancement TA, 4 - Urgency of Poor Quality, 5 - Request of Subjacent-Subjacent subcell change, 6 - Delivery Request Intra-cell, 7,8 - Layer, where 00 indicates the lowest layer, 01 indicates the second layer, 10 indicates the third layer and finally 11 indicates the highest layer, 9 - Intensity of the own signal below the threshold, 10 - Not used (but in this case it indicates 0).

This table will be referred to below as Table C. Table 5a is related to layer 1 below, that is, the cell itself (the cell that serves) is in the lower layer (conditions 7 and 8) and the Signal strength is below the threshold of that specific cell (condition 9). 32 different cases are indicated in the table. Table 5b refers to layer 1 above, that is, the cell itself is in the lower layer and the intensity of the signal is above the threshold. Table 5c is related to layer 2 that is below, that is, the second layer where the cell itself is in the second layer (in this case intermediate) and where the intensity of the signal is below the threshold of that cell specific; that is, I2 < l2 ^ r- Table 5d is related to layer 2 above, that is, the second layer and a signal intensity 5 that exceeds the threshold (I2 > l2 ^ r) • Finally, table 5e is related to the layer 3 above that indicates layer 3 of the cell itself in the upper layer, in this case and a signal strength "" "** that exceeds the threshold, alternatively, the threshold. Next, two specific examples of the interactions of the hierarchical cell structure with other functions of the network will be provided. Particularly the interactions with other functions of the The network is provided with a priority that yields the classified order in the system priority box, whether or not the tables (such as Figure 4 and Figure 5) are based on the priority between network functions radio or not. In a first example, the interaction with the intra-cell delivery function will be described for a specific modality. Two or more functions of the radio network can make their own proposals at the same time, in this case the intra-cell delivery function proposes a change of channel within a cell at the same time as the function of the structure of the hierarchical cell proposes a delivery to another cell, either of an upper layer or a lower one. In this specific modality, a delivery to an upper layer has preference in relation to an intra-cell delivery (see Table B). however, an intra-cell delivery takes precedence over eg, a quality alarm delivery, but of course, eg, a quality alarm delivery may alternatively have preference in relation to a delivery of intra-cell, etc. This depends on the needs and requirements of a specific system. When the measurements of the cells of the mobile station have been received, the corresponding cells are categorized according to the combination of three parameters, namely 1 - the hierarchical layer to which they belong, 2 - their rank as to whether they are better or worse than the cell that serves according to the normal location criterion and finally 3 - if the measured signal strength is above or below the threshold for that cell. In this case, the three hierarchical layers are implemented and twelve categories are obtained.

In general, all possible situations and combinations of situations are related to the different evaluations of the controlled function of the radio network are analyzed. Based on these, a unique sequence of cell categories is assigned to that specific combination of evaluation results. The sequence of the categories, e.g., can be carried out in order to comply with a given priority list, such as eg, that which is provided in Table B. This sequence or list of candidates as explained above therefore represents the list of delivery candidates in the order of specific preference. Figure 6 further explains how the different categories of the cells can be placed in the order of priority in a list, e.g., cases 6, 7, 8 in Figure 4a. In Figure 4a, the two categories 2bo and 2bu form a single category 2b. For 2w, the corresponding release together has been carried out for 2wo and 2wu. In addition, in Figure 6 or / u (above / below) it is related to the signal strength of the neighbor cell that is above / below the threshold value for that neighbor (or candidate) cell. r. The reason for this division is to avoid the unnecessary ping-pong delivery effects (which first go down one layer and directly after that they will have to go up to an upper layer again). Next, an example will be taken into account where the structure comprises two cell layers and where the cell giving service in the lower layer. It is assumed that in addition to the normal location, the radio network evaluations have proposed three actions simultaneously namely, a bad quality alarm delivery, a delivery to a higher hierarchical layer and an overlying / subjacent subcell change. In this case, a delivery to a higher hierarchical layer has the highest priority whereas a poor quality alarm delivery has the lowest priority. The highest priority of all is to remain in the lower layer, that is, a better normal cell delivery that is initiated by the normal location. With this combination of evaluation results, the list of candidates for delivery candidates as illustrated in Figure 6 can be obtained. First, a range through the location function is carried out where the cell is represented as better and worse than the service cell and then the list of delivery candidates is established. As referred to above above / below the threshold, it refers to the threshold for that specific cell. According to this list, the highest priority is to remain in the lower layer, but only if a better cell appears that is illustrated in the first line. The second priority will be to go up to the top layer illustrated in lines 2 and 3 of Figure 6. If going to a better cell results in immediately going up to a top layer or an "umbrella" cell which is the case if the intensity of the signal of that cell is below the threshold, the first delivery will not be made and instead of this there will be a delivery directly to the upper cell or the "umbrella" illustrated in lines 1 and 4. The third priority will be to carry out a sub-cell change that is illustrated in line 5. Finally, the lowest priority is to go to the cell that is classified as worse than the cell that currently serves the the connection. Also in this case, a cell in the lower layer has preference with respect to a cell in the upper layer, but this is not the case if it follows a second delivery towards the upper layer, which can be seen in lines 6 to 8 of the Figure 6. The advantageous embodiments of the invention are applied to TDMA (Time Division Multiple Access) or FHMA (Multiple Frequency Hopping Access) or CDMA (Code Division Multiple Access). Furthermore, the invention is not limited to any specific delivery strategy but a number of different strategies can be used, such as the delivery strategy aided by the MAHO mobile station, NCHO Controlled Delivery or Controlled Delivery by the MCHO Station. With the invention, it is possible to apply a systematic approach when designing the structures of the hierarchical cell. Of course, an arbitrary number of layers can be designed and the detailed conditions for switching between the layers can be controlled in terms of criteria for switching between the layers as well as a detailed interplay with other functions controlled by the radio network. Because among others is the fact that it is generally predictable to pass between the layers, it is possible to plan and dimension the systematic cell. It is also possible to direct the mobile stations to the lower layer in a systematic manner which, as already stated above, saves the capacity of the upper layers for v.gr., coverage spaces or call setup congestion, etc.

Alternatively it is possible to direct the mobile stations to any preferred layer. With the invention, it is intended, among other things, to be able to direct traffic to the cells for which the network or HCS Hierarchical Cellular System is actually sized to ensure that there is a free capacity in those cells that will provide spare capacity during the installation of the call and that have the function of rescue cells. Cells in a higher layer have priority in the coverage holes and in the radio alterations to ensure the continuity of the call. The congestion cells during the call installation in a top layer also have priority in order to ensure satisfactory call installation procedures. The invention, of course, is not limited to the embodiments shown, but may be varied in a number within the scope of the claims. With particularity, the invention can be applied to each standard, generally known as GSM, PDC, all the standards PCS, IS54, IS90, ADC, (D-) AMPS, DECT, etc.

Claims (33)

CLAIMS:

1. A mobile cellular communication system with a number of radio base stations (BS) and a number of mobile stations (MS), the system comprises a number of cells that are placed in at least two different layers or levels, wherein the mobile stations (MS) can be operated from one cell to the other and comprise a means for monitoring or measuring at least one signal connection parameter of at least those cells that are not in the upper layer, and where at least one threshold value (Io * -r, Iitr) for at least one signal parameter is provided for at least each cell (CQ, CÍ i =? .... n) not being in the upper layer , the system further comprises a means of control for deciding and controlling delivery decisions characterized in that the control means comprises a priority rank arrangement based on a number of criteria of which the first criterion is based on a comparison of the value supervised (IQ ) of a signal parameter (Iss, Ipi) of the cell serving with the determined threshold value (I? -r) of the serving cell (CQ) OR the cell currently serving a connection determined, and a second criterion that is based on the comparison of the supervised value (I¿) of a signal parameter of a neighboring cell with a determined threshold value (Ij_trj for the same neighbor cell (Cj where the deliveries are regulated by a priority rank arrangement such that a systematic pass is obtained between the cells or cell layers or levels, as well as to pass up and down between the cell layers.

2. The system according to claim 1 characterized in that, the first criterion is used to decide whether a delivery from a cell in a lower hierarchical layer to a cell in a higher hierarchical layer is to be taken into account.

3. The system according to claim 2 characterized in that, according to the first criterion, a cell in an upper layer is eligible for delivery if the current value of the parameter value of the supervised signal (IQ) of the cells that gives service (Cn) is less than the threshold value (I? -r) and / or the threshold value (Io * -r) modified with a hysteresis (Ho ^ -r) for that cell.

4. The system according to claim 3, characterized in that, a cell in an upper hierarchical layer is eligible for deliveries if the current value of the supervised signal parameter (IQ) is smaller than the threshold value minus a hysteresis (Ho ^ r).

5. The system according to any of the preceding claims, characterized in that, the second criterion is used to decide whether a delivery from a higher hierarchical layer to a cell in a lower hierarchical layer must be taken into account.

6. The system according to claim 5 characterized in that, according to the second criterion, a cell (C-- in a lower hierarchical layer is eligible for delivery if the current supervised value in the parameter of the supervised signal (I -_) exceeds the threshold value (Ij_tr) of that cell, and / or the threshold value modified with a hysteresis (H-_tr)

7. The system according to claim 6, characterized in that, the value The threshold (I-Δtr) is modified in such a way that a hysteresis is added to it (Hj ^ rj.

8. The system according to any of the preceding claims, characterized in that the cells (CQ, C- ^) are classified into categories based on a number of classification criteria.

The system according to claim 8, characterized in that, a classification criterion comprises the normal location, that is, the neighboring cells (Cj_) are classified in comparison with the service cell (Cn), v.gr. , if they are better or worse than that cell (Cn) for at least one supervised signal parameter (Iss;? pl) *

10. The system according to any of the preceding claims, characterized in that the cells (C) are classified into categories based on the criteria related to both the supervised signal parameter compared to the corresponding supervised value of the serving cell (Cn), as well as to the supervised value of a cell (C-¡) compared to the threshold value of that same cell (Cj_).

11. The system according to any of the preceding claims, characterized in that the cells are classified into categories based on which layer they are.

The system according to any of claims 8 to 11, characterized in that, the priority range arrangement comprises a number of criteria related to a number of conditions.

The system according to claim 12, characterized in that the cells are placed according to the classification criteria depending on whether the conditions have been filled or not.

The system according to claim 12 or 13, characterized in that, at least some of the conditions are called alarm criteria, such as eg, bad quality urgency, e.t.c.

15. The system according to any of the preceding claims, characterized in that the priority range arrangement comprises a cell category organization table that is classified depending on the number of criteria.

16. The system according to claim 15, characterized in that the cells are classified in the organization table into categories that depend on at least the first and second criteria and a number of conditions.

17. The system according to claim 15 or 16, characterized in that a priority list or a list of delivery candidates of the organization table is formed.

18. The system according to any of the preceding claims, characterized in that, the signal parameter is the signal strength.

19. The system according to any of the preceding claims, characterized in that, the signal parameter (s) is / are path loss or path loss as well as signal strength.

20. The system according to any of the preceding claims, characterized in that the cells are divided into two different layers.

21. The system according to any of claims 1 to 19, characterized in that the cells are divided into three different layers eg, pico-celdsd, micro-cells and macro-cells.

22. The system according to any of claims 1 to 19, characterized in that the cells are divided into more than three layers.

23. The system according to any of the foregoing claims, characterized in that, the delivery strategy used is the strategy of Delivery Helped by Mobile Station (MAHO).

24. The system according to any of the preceding claims, characterized in that a threshold value (In1: r / I ± ^ r) is provided for cells also in the upper layer.

25. The system according to any of the preceding claims, characterized in that the cells in an upper layer form a call "umbrella" for the cells in a lower layer.

26. The system according to any of the preceding claims, characterized in that the interactions with the other functions of the network are provided with a priority yielding the classified order in the system priority table.

27. The system according to any of the preceding claims, characterized in that, for an evaluation of the function controlled with a specific network, a unique sequence of cell categories is assigned to that combination of evaluation results.

28. The system according to any of the preceding claims, characterized in that the Time Division Multiple Access (TDMA) or the Frequency Division Multiple Access (FDMA) or the Code Division Multiple Access (CDMA) is applied. ).

29. The system according to any of the foregoing claims, characterized in that it is a telephone communication system.

30. The system according to any of the foregoing claims, characterized in that the GSM standard is used.

31. The system according to any of claims 1 to 29, characterized in that, eg, an ADC, PDC or DECT standard is used.

32. The system according to any of claims 1 to 29, characterized in that it is an ISDN communication system.

33. The method for delivering connections between a mobile station and the different cells in a cellular mobile communication system, comprising a number of radio base stations and a number of mobile stations, the system comprises a number of cells that are placed in at least two different layers or levels, the method comprises the following steps: entering a threshold value for at least one signal parameter of the cell serving a terminated connection; - entering a threshold value for at least one signal parameter for at least each cell that is not in the upper layer; monitor at least one parameter of the signal for the serving cell; monitor at least one parameter of the signal for a number of neighboring cells; compare the supervised current value of the signal parameter for the serving cell with the threshold value for the serving cell; comparing the supervised value of the signal parameter for the neighboring cell with the threshold value of the respective cell; use the comparisons to carry out the deliveries in accordance with an order of priority range determined in such a way that a systematic pass is obtained between the cells or cell layers, as well as to pass upwards and downwards between the cell layers .