MXPA00009665A - Cell selection in mobile radio systems - Google Patents

Abstract

The present invention relates generally to the problem of cell selection, for e.g. cell handover, in mobile telecommunication systems, and more particularly to the problem of selecting the optimum cell among cells with differing capabilities due to different air interface modes. Known algorithms for cell selection and handover are extended by applying additional criteria that take into account the capabilities, due to different modulation and coding schemes, of the mobile station and the base stations that are possible candidates.The quality of service ("QoS") is predicted for the different cell candidates based on a combination of signal strength or C/I, different cell capabilities, multislot capability, etc. Then the cell is selected for which the predicted QoS is maximum. In another embodiment the invention is extended by taking into account further criteria which are suitable from a system point of view, e.g. to avoid a significant increase of average outage probability or interference level. The present invention increases the use of base stations supporting high data rates. The result is an increase in overall system throughput.

Description

SELECTING CELLS IN MOBILE RADIO SYSTEMS FIELD OF THE INVENTION The present invention relates generally to the problem of cell selection, for example, cell transfer, in Mobile Telecommunications Systems, and more particularly to the problem of selecting the optimal cell between cells with different characteristics due to different air interface modes. RELATED TECHNIQUE FIGURE 1 shows a view of a typical Mobile System with many cells and numerous Mobile Stations ("MS"). Each of these cells has a Station Associated base ("BS") which is responsible for radio communication over the air interface to the Mobile Station in that cell. For a given mobile station at a given time there is normally a service cell which is the cell with the Base Station from which the mobile station is receiving service so that the mobile station can receive and transmit a communication by means of the Service base station. It is a characteristic of modern cellular systems that it is possible to change a call from a station. from base to another while the Mobile Station is moving from one cell to another within the Mobile Communication System. This is known as transfer. In Mobile Communication Systems, the transfer process uses measurements made by the Mobile Station, the Service Base Station and / or neighboring Base Stations, using these measurements in the decision making process for the transfer. These measurements can be taken from the quality of the connections, or links, between the mobile station and the base station or neighboring base stations. "Link quality" measurements include, for example, the frequency of errors in the raw bits ("BER") and the strength of the signal received from the different links between the mobile station and its Service Base Station or between the mobile station and the neighboring base stations. For example, in the Mobile Communication System known as GSM ("Global Communication System Mobile "), a Mobile Station monitors the quality of the link (example: a rough BER estimate and the received signal strength) of a received signal (downlink signal) received from the base station of the service cell, as well as the quality of the link in terms of reception level, being this, the intensity of the received signal, of the downlink signal of the base station in cells adjacent to the service cell. In addition, the base station of the cell monitors the quality of the signal (uplink signal) received at the Base Station for each Mobile Station that is served by that Base Station. The transfer occurs when either the MS / BS measurement indicates that the quality of the link in the cell serving at that time is low and that a better quality can be obtained from an adjacent cell, or an adjacent cell allows communication with lower transmission levels. The problem of transfer in current systems can be summarized by saying that the strategy is to keep the mobile station connected to the "best" cell. The problem of selecting the "best" cell in the current systems compared to the new systems to be developed in the years to come. These future systems will be based on different radio interface modes (example: with different coding and modulation schemes). An example of the developments in these future systems is the gradual introduction of several coding and modulation schemes in existing systems such as GSM. The modulation is essentially the function which imposes the characteristics of the electromagnetic field (example: amplitude and frequency) in a set of rules and in the data to be transmitted (which "modulate" the transmission). In the case of current GSM is the phase of the electromagnetic field which carries the information. It is normal to distinguish modulation and demodulation on the one hand, and the reception and transmission by another. The first processes transform the digital data to and from a modulated frequency signal, and the second pair of processes transform this low modulated frequency signal to and from the electromagnetic field. In current GSM systems the modulation method used is the Gaussian Minimum Change ("GMSK"). The GMSK provides a balance between a fairly high efficiency spectrum and a reasonable demodulation complexity. In current IS-136, the modulation scheme is p / 4 - Differential Quaternary Change Phase Keying (DQPSK). During the evolution of the second generation cellular systems such as GSM and D-AMPS, the proposed changes have been made to the modulation scheme in order to provide higher bit ratios within the same spectrum. These are several of the proposed schemes. One of these is the Binary Continuous Phase Modulation encoded Differentially ("DBCPM"). This is a family of modulation types, one example of which is p / 4-DBCPM, with the advantage of a high amplifier power efficiency. Another proposed scheme is the Quaternary Deviation Quadrature Amplitude Modulation ("Q-O-QAM"), also known as Deviation-16QAM. A key difference between these modulation schemes is that they provide users with different ranges of data. The goal of the evolution of these systems is to increase the bit rate. The result is that the Systems will be using different modulation schemes, often in neighboring cells, in order to provide different users with more options for which they will use the data rate. In addition, different data reasons will require different channel coding schemes. Also, several coding schemes can be used for a modulation. As a result, there will be a variety of coding and modulation schemes that provide different data ranges. The current transfer algorithms establish that link between a Base Station and a Mobile Station which provides the highest link quality. There are also many variations of this Base scheme where additional criteria are used, such as vehicle speed, as illustrated in O-9702716"Method to Determine Transfer in a Multicellular Communication System", or interference in other cells, as illustrated in WO-9528808"Method and Transfer Arrangement". However, none of the existing methods attacks the problem which will exist in Evolved cellular systems, for example, the problem of selecting the best cell for transfer between cells with different modes of air interference (example: with different modulation and coding schemes) . COMPENDIUM OF THE INVENTION The present invention relates generally to the problem of cell selection, for example, cell transfer, in Mobile telecommunications systems, and more particularly to the problems indicated above, the means for solving these problems according to the present invention. invention are summarized in the following. As noted above, there is a problem at present because the current transfer methods do not take into account the ability of different cells in terms of different modes of air interference when deciding which cell to make the transfer to. It should also be noted that the general problems of selecting the best cell during the transfer also apply to other situations where the selection of cells occurs, for example, during the call establishment or when the Mobile Station continuously selects the cells during the inactive mode. In current Mobile Communication Systems this selection of cells is not a problem because current systems typically use only one modulation scheme and one coding scheme in addition to typically using one carrier and one segment. Compared, the new Systems that are being proposed and are being developed, for example, GSM evolutions. In these systems involved there will be simultaneously different systems and cells, each with different modulation and / or coding schemes to provide different data reasons to different users. The current selection methods are optimally designed to select the "best" cell for the transfer in these evolved Systems. Accordingly, it is an object of the present invention to provide a method for selecting the best cell from the user's point of view, this being in terms of maximizing the Quality of Service ("QoS"). The maximum QoS can be given in terms of for example: speed and data production-higher bits. This new method of selecting the best cell is done by extending the known algorithm for cell selection and transfer, and then applying additional criteria that take into account the faculties of the Mobile Station and the Base Station that are possible candidates. Preferably, the obtainable data rate (for "transparent" services) or production (for "non-transparent" services) is predicted for different candidate cells, based on the intensity of the received signal or C / I estimates, their different faculties , availability of segments, etc., and the cell for which the predicted data rate or production is maximum is selected. For the prediction of data rate and production, the different levels of robustness of the air interface modes against noise and interference must be taken into account. This can be done for non-transparent services inherently by estimating the Quality of Service in terms of production.

For transparent services, the quality of the service is given by the bit rate and the frequency of errors in the required bits, it is an appropriate criterion. A strategy for the latter case is to select the "closest", example: measured by the intensity of the signal received in the transmission channel, the cell that provides the required QoS. By applying the extended algorithm for the selection of cells according to the present invention, the speed of data and production in some connections can be increased by increasing the cost of greater interference. Therefore, another embodiment of the present invention is to take into account measurements of the System such as, for example, load and estimated interference level. This can be useful in order to enable the operator to allow such long-distance connections with high data reasons only if the impact on the System is low. This would be true where, for example, the system load is low. Although the present invention has been summarized above, the method according to the present invention is defined in accordance with appended claims 1 and 21. Various embodiments are further defined in dependent claims 2 to 20 and 22.

Although the present invention has been discussed primarily in the context of GSM systems, it should be understood by anyone skilled in the art that the present invention is equally applicable to other types of systems such as the evolved IS-136. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be described in more detail with reference to the preferred embodiments of the present invention, indicated only by way of example, and illustrated in the accompanying drawings, in which: FIGURE 1 is a communication system Mobile phone. FIGURE 2a is a diagram of a Mobile Station and candidates for transfer in the System shown in FIGURE 1. FIGURE 2b is a graph showing the relationship between the data rate and signal strength for a given interference level . FIGURE 3a and FIGURE 3b is a flow diagram illustrating the steps of the method of the present invention. FIGURE 4a and FIGURE 4b show a flow diagram illustrating the steps of the method of the present invention for non-transparent services. FIGURE 5a and FIGURE 5b show a flow diagram illustrating the steps of the method of the present invention for transparent services.

DETAILED DESCRIPTION In FIGURE 2a a closer view can be seen for a few cells, for example: 210 and 220, in a Mobile System 200 with numerous cells and associated Base Stations. A Mobile Station ("MS") is also shown although, of course, the present invention is not limited to Systems with the number of cells shown here or to be used with a mobile station only. The mobile station here is preparing for a transfer to several possible transfer candidates. Although the method illustrated here is specifically presented, it is one for "cell selection" in general, equally applicable for example: the initial cell selection problem during call set-up or for the selection of cells carried out by the cell. Mobile Station for example: inactive mode. For the purpose of illustration only two suitable candidates are shown here, either the first cell 210 or the second cell 220. The responsibility for communication over the air interface 215 in the first cell 210 is taken by the first base station BS1. Responsibility for communication over the air interface 225 in the second cell 220 is taken by the second base station BS2.

It is assumed here that the mobile station supports various air interface modes (example: schemes SI, S2 and S3) which are based on different coding and modulation schemes. These schemes provide different data reasons. Nevertheless, the signal strength required to provide a given link quality and a given interference level for each of the schemes is different. As illustrated in FIGURE 2a, the first base station BS1 also supports these air interface schemes SI, S2 and S3. In contrast, the second base station BS2 supports only one SI scheme, which provides the lowest data rate. It should be emphasized, however, that the present invention is not restricted to base station having this particular number of schemes. For example, in the proposed standards for GSM it is planned that the Base Station will be able to support up to eight different schemes. The general method described below will work in all cases, for example: if (1) the mobile station supports SI to S3 and BS1 supports SI to S3 (as shown in FIGURE 2a), or (2) the mobile station supports SI to S2, and BS1 supports SI to S2, or (3) the mobile station supports SI to S3, and BS1 supports SI to S2, or (4) the current standard transfer situation where both MS and BS1 support SI everywhere. The present method works the same regardless of how many schemes support the mobile station and the BSs. In general, all possible links are verified for maximum QoS or production, and the link that provides it will be selected. FIGURE 2b shows a typical relationship between the signal power which is required, for example, to obtain the frequency of errors in the desired bits for a given interference level (and noise), and provides a data rate in the Air interface (including correction of advanced error). It can be appreciated that the required signal strength is typically increased as the data rate increases. As a result, the air interface modes SI, S2 and S3 provide different data ratios, but on the other hand they are differently susceptible to interference (and noise). Estimates as to which transfer selection is best should take this sensitivity into account when deciding which scheme will provide the best data rate. Looking again at FIGURE 2a, if it is assumed here that link quality 225 from BS2 to MS is higher than from BS1 to MS then the standard algorithm for cell selection and transfer will lead to a traffic connection between MS and BS2, although production can be increased by allowing a traffic connection between MS and BSl if a scheme with higher data ratios can be used. However, assuming that MS applies the cell selection algorithm according to the present invention we can obtain a different result. According to the new algorithm, the MS-BSl 215 and MS-BS2 225 links are verifiers not only for a maximum link quality, but the faculties of these two Base stations, BSl and BS2, as well as the mobile station are also taken into consideration. In this context, as before, the quality of the link may be given by one or several measurements, such as, for example, the level of the signal received in the transmission channel, the carrier-to-interference power ratio ("C / I"), the estimation of the frequency of errors in the raw bits. Here it may seem that the connection to BSl will provide a higher data rate or a higher output than the BS2 connection. In this case, the cell 210 with BS1 is selected by the selection algorithm of the present invention which is normally carried out by the network side control unit, eg, the controller of the base station ("BSC"). ") in a GSM System. The application of this algorithm differs according to whether the type of service being provided is a "transparent" service or a "non-transparent" service. A brief explanation of this is necessary. It is known that for a given noise and interference level and given channel conditions, the characteristics of the transmission when error correction is provided is a balance between the data production, the delay of the transmission and the frequency of errors remaining. In modern systems, no exchange is adjusted to the different types of services (example: voice vs. data). Of all the possibilities, a small delay in spite of a relatively high error frequency is better in some cases, where (example: fax) a large delay can be tolerated in order to obtain a better transmission quality. For these reasons, several types of connections are provided in GSM. For these services to which the transmission is "transparent" (example: voice) the System provides a connection with a constant bit rate. For "non-transparent" services (example: fax) there is no continuous connection. The information is sent in packets which can be transmitted if errors occur, leading to a lower "effective bit rate", which is known as "production". The present invention uses a prediction of data rate and production in the transfer decision process. To do this, different levels of robustness of the air interface modes against noise and interference are taken into consideration. For non-transparent services this is carried out estimating the production. For transparent services, the quality of service ("QoS"), given, for example, the bit rate and frequency of errors in the required bits, is the most appropriate criterion. QoS can also be defined for non-transparent services, and is then equal to production. This general definition of QoS is used particularly in the following general definition of the present invention. FIGURE 3a shows a flow chart illustrating an embodiment of the algorithm according to the present invention. This modality is described independently of the service, and can be used for non-transparent services as well as for transparent services. The first step 310 in the algorithm is to determine, by monitoring, the faculties of the candidate BSs.

These faculties include, for example, supported coding schemes, supported modulation schemes, multi-carrier capability and multi-segment capability. This determination is carried out continuously and will be carried out typically in, for example, the controller of the base station BSC. In addition, the faculties of the mobile station must also be verified in the first step 310. This is because the mobile station may not necessarily support all the schemes available for each candidate BS. Only the faculties of the links in a BS which is supported by the mobile station need to be considered. The second step 320 of the algorithm is to measure the binding qualities of the candidate BSs. The quality of the link may be given by one or more of several possible measurements, including, but not limited to, (1) the intensity of the signal received in the BCH transmission channel, (2) carrier interference estimate ("C / I ") for the BCH or traffic channel and (3) estimate" BER "in a traffic channel. The third step 330 of the algorithm is to estimate a quality of service ("QoS") value for each possible connection with each base station candidate. This estimation procedure can be carried out according to appropriate algorithms which are not objects of the present invention. The objective is to use the information available for each cell, for example, intensity of the received signal combined with the faculties of the cell. To estimate the best QoS for each cell. The final step 10 of the algorithm is to select the BS from the list of transfer candidates to which the connection provides the best QoS. Then the transfer will be made to the cell that provides the best QoS. FIGURE 3b illustrates an optional extension for this final step. The first three steps 310, 320 and 330 in FIGURE 3a have corresponding equivalent steps 315, 325 and 335, in the embodiment shown in FIGURE 3b. In FIGURE 3b the final estimation procedure 345 of selecting the BS with the best QoS can additionally take into account the criteria of the System as load and interference levels, as further described below. In the algorithm as presented in FIGURE 3a, no System criteria are explicitly used. Instead, these values can be taken into account inherently by estimating the best QoS in the different links. However, it should be noted that the parameters of the System such as the load can also be used explicitly as in FIGURE 3b. These additional criteria used in FIGURE 3b are those which are suitable from the point of view of the System, for example, to avoid a significant increase in the probability of average loss or level of interference. One of said System criteria may be the load on the candidate Base station, this information is available in the control unit, example, which carries out the cell selection algorithm. A simple implementation is to allow the connection, example: MS-BSl, only if the load on BSl is below a predefined threshold. This can be defined by the percentage of traffic channels used. By means of this additional criterion, an impact on the total interference can be avoided. The network operator may be able to adapt the parameters of this extended algorithm individually. For example, it may be possible to have MSs with higher priority for high-speed data connections than other MSs. This can be implemented using different thresholds for the load allowed for the selection of cells that provide higher data ratios. However, the System "load" criterion may not be sufficient where, for example: the increase in interference is more important, and the load is only a rough estimate of this value. In this case, the appropriate System criterion for cell selection is the estimation of the interference increase by selecting the MS-BS! With higher data reasons. further, it is apparent that the criteria can be combined to take into account several aspects. An example combination of criteria can be defined by a combination of the data rate provided in individual links and the load in the individual BS. Calculate Q - a * (provided - gives cough - speed) - b * (load - on - BS), where a and b are positive constants. Here, the base station with maximum value Q >; 0 would be selected. FIGURE 4a shows a flow chart illustrating an embodiment of the algorithm according to the present invention in the case of non-transparent services. The first step 410 in the algorithm is to determine, by monitoring, the faculties of the candidate BSs. These capabilities include, for example, supported coding schemes, supported modulation schemes, multi-carrier capability and ulti-segment capability. this determination is carried out continuously t will typically be carried out in for example, the base station BSC controlled. In addition, the faculties of the mobile station must also be verified. This is because the mobile station may not necessarily support all the schemes available for each candidate BS. Only the faculties of the links in a BS which is supported by the mobile station need to be taken into consideration. The second step 420 of the algorithm is to measure the binding qualities of the candidate BS. The quality of the link may be given by one or more of several possible measurements, including, but not limited to, (1) received signal strength in the BCH transmission channel, (2) carrier-to-carrier interference estimation ("C / I"). ) for the BCH or traffic channel and (3) gross estimate "BER" in a traffic channel. The third step 430 of the algorithm is to estimate the output for all BS. This can be compared to the method in FIGURES 3a and 3b. The best QoS in the general method of FIGURES 3a and 3b, makes the data production higher when it is supplied to non-transparent services as in FIGURES 4a and 4b.

This production estimation procedure can be carried out according to appropriate algorithms which are not part of the present invention. The objective is to use the information available for each cell, for example, the received signal strength combined with the faculties of the cell, to estimate the maximum production for each cell. The final step 440 of the algorithm is to select the BS from the list of transfer candidates to which the connection provides maximum output. Then the transfer will be carried out to that cell that provides the maximum production. FIGURE 4b illustrates an optional extension for this final step. The first three steps 410, 320 and 430 in FIGURE 4a have corresponding equivalent steps 415, 425 and 435, in the embodiment shown in FIGURE 4b. In FIGURE 4b the final selection procedure 445 of selecting the BS with the best QoS may additionally take into account SYSTEM criteria such as load and interference level, as further described below in relation to FIGURE 3b. In the algorithm as presented in FIGURE 4a, no explicit SYSTEM criteria are used. Instead, these values can be inherently taken into account by the production estimate obtainable in the various links. However, it should be noted that the parameters of the SYSTEM such as the load can also be used explicitly as in FIGURE 4b. In FIGURE 5a there is shown a flow diagram illustrating one embodiment of the algorithm according to the present invention in the case of transparent services. The first step 510 in the algorithm is to determine, by monitoring, the faculties of the candidate BSs. These faculties include, for example, supported coding schemes, supported modulation schemes, multi-carrier capability and uiti-segment capability. This determination is carried out continuously and will be carried out typically in, for example, the controller of the base station BSC. In addition, these faculties of the mobile station must also be verified. This is because the mobile station may not necessarily support all the schemes available for each candidate BS. Only the faculties of the links in a BS which are supported by the mobile station need to be taken into consideration. The second step 520 of the algorithm is to measure the binding qualities of the candidate BS, as discussed previously. The quality of the link may be given by one or more of several possible measurements, including, but not limited to, (1) received signal strength in the BCH transmission channel, (2) carrier-to-carrier interference estimation ("C / I"). ) for the BCH or traffic channel and (3) gross estimate "BER" in a traffic channel. The carrier-to-interference ratio, C / I, provides a better estimate of link quality. The third step 530 of the algorithm in FIGURE 5a shows a difference in the application of the present invention to transparent services in contrast to the general method of FIGURES 3a and 3b, and with non-transparent services in FIGURES 4a and 4b. The third step of the algorithm is to estimate the quality of service ("QoS"), in terms of example of the bit rate and frequency of errors in the required bits, for all candidate BSs. Those BS are preselected which provide sufficient QoS for the requested service. In the case of transparent services using a fixed source speed, a high QoS is equivalent to a low BER with a sufficient data rate, as shown in FIGS. 5a and 5b. Other modalities in the case of transparent services that use an adaptive source rate will evaluate a high QoS as equivalent to a sufficient BER with a high data rate. In modalities for voice services, a QoS would be evaluated as equivalent to a high quality voice. This would be used in the situation where several voice codes would be in use, which is the case with ("AMR") multi-range GSM. The final step 540 of the algorithm is to select the BS from the candidate BS list with maximum link quality, example, as measured by the signal strength of the candidate BS among those BSs which provide sufficient QoS as shown in FIGURE 5a. Then the transfer will be carried out to that cell that provides sufficient QoS. FIGURE 5b illustrates an optional extension for this final step. The first three steps 510, 520 and 530 in FIGURE 5a have corresponding equivalent steps 515, 525 and 535, in the embodiment shown in FIGURE 5b. In FIGURE 5b the final estimation procedure 345 of selecting the BS with the best QoS can additionally take into account the criteria of the System as load and interference levels, as described further above in relation to FIGURE 3b. In fact, the final step 545 of the algorithm of FIGURE 5b consists of simultaneously verifying which BS satisfies two requirements: maximum link quality and SYSTEM criteria applied. The modalities described above serve only as an illustration and not as a limitation. It will be apparent to those of ordinary skill in the art that one can leave the modes described above without departing from the spirit and scope of the present invention. The present invention should not be considered as limited to the examples described, but its scope is defined in the following Claims.

Claims (22)

1. CLAIMS A method for cell selection in a cellular Mobile Communication System having a plurality of cells, each with at least one Base Station, and a Mobile Station for communication with said Mobile System, using a supported air interface scheme by at least one Base Station and the Mobile Station, through an air interface link with one of said Base Stations; comprising the steps of: measuring the quality of the links between said Mobile Station and said Base Station; said method is characterized in that it also comprises the following steps: determining the communication faculties of said base Station and said Mobile Station; estimate the value of the Quality of Service for each possible link between said Mobile Station and said Base Station; and select the cell with the Base Station that has the highest estimated Quality of Service.
2. The method of claim 1 further characterized in that: each air interface scheme is based on a different coding and modulation scheme.
3. The method of claim 1 or claim 2 further characterized in that: said communication faculties of said base station and said mobile station are measured in terms of the faculties of said air interface schemes.
4. The method of claim 1 or claim 2 further characterized in that: said powers of said base station and said mobile station are measured in terms of availability of multiple segments in the links to said base station.
5. The method of claim 1 or claim 2 further characterized in that: said powers of said base station and said mobile station are measured in terms of the availability of multi-carrier in the links to said base station.
6. The method of claims 1 to 5 further characterized in that: the highest Quality of Service is equivalent to the highest production in said link.
7. The method of claims 1 to 5 further characterized in that: said higher Quality of Service is equivalent to a combination of the lowest bit error frequency and a sufficient data rate.
8. The method of claims 1 to 5 further characterized in that: said higher Quality of Service is equivalent to a combination of the frequency of errors in the sufficient bits and the highest data rate.
9. The method of claims 1 to 5 further characterized in that: said higher Quality of Service is equivalent to the higher speech quality.
10. The method of the preceding claims wherein said method further comprises the step of: testing a given System criterion.
11. The method of claim 10, further characterized in that: said System criterion is a test of whether the load is below a given threshold.
12. The method of claim 10, further characterized in that: said System criterion is a test to see if the increase in the interference level is below a given threshold.
13. The method of claim 10, further characterized in that: said System criterion is a test if the System criteria indicator based on a combination of load, interference level and desired data rate are below a given threshold.
14. The method of the preceding claims further characterized in that: said Mobile Station is currently accessing said Mobile System from a first Mobile Station and said cell selection is carried out for the purpose of implementing a transfer for said Mobile Station to a second Mobile Station. of base.
15. The method of claims 1 to 13 further characterized in that: said Mobile Station is being prepared to access said Mobile System and said cell selection is carried out for the purpose of selecting the best cell through from which to access said System.
16. The method of claims 1 to 13 further characterized in that: said selection of cells is carried out while said Mobile Station is in idle mode.
17. The method of the preceding claims further characterized in that: said Mobile Station and said Base Station support an equal number of air interface schemes.
18. The method of claims 1 to 16 further characterized in that: said Mobile Station and at least one of said Base stations support an equal number of air interface schemes, and at least one Base station supports fewer air interface schemes than said Mobile Station.
19. The method of claims 1 to 16 further characterized in that: said Mobile Station and at least one of said Base stations support an equal number of air interface schemes, and at least one Base station supports more air interface schemes than said Mobile Station.
20. The method of claims 1 to 16 further characterized in that: said Mobile Station, at least one Base Station and a second one of said Base Stations each supports a different number of air interface schemes.
21. 21. A system for the selection of cells in a cellular mobile communication system having a plurality of cells, each with at least one base station, and a mobile station for Communication with said Mobile System through an air interface link with one of said Base Stations, comprising: means for measuring the quality of the links between said mobile station and said Base Stations; and further characterized by: said Mobile Station and said base Stations supporting at least one air interface scheme; means for determining the faculties of said Base Stations and said Mobile Station; means for estimating a Quality of Service value for each possible link between said Mobile Station and said Base Stations; and means to select the cell with the base station that has the highest estimated Quality of Service.
22. 22. The system for cell selection of claim 21 further characterized by: means for testing by a given system criterion SUMMARY OF THE INVENTION The present invention relates generally to the problem of cell selection, for example, cell transfer, in mobile telecommunications systems, and more particularly to the problem of selecting the optimal cell between cells with different capacities due to different modes of air interface. Known algorithms for cell selection and transfer are extended by applying additional criteria that take into account the capabilities, due to different modulation and coding schemes, of the mobile station and the base stations that are possible candidates. Quality of service ("QoS") is predicted for the different cells that are candidates based on a combination of signal strength or C / I, different cell capacities, multiple segment capacity, etc. Then the cell for which the predicted quality of service is maximum is selected. In another embodiment, the invention is extended by taking into account additional criteria that are suitable from a system perspective, for example, to avoid a significant increase in the probability of interruption or level of interference. The present invention increases the use of base stations that support high data rates. The result is an increase in the overall performance of the system.