MXPA97004310A - Best mobile assisted transfer - Google Patents

Abstract

The present invention relates to a method for mobile assisted transfer in a cellular communication system comprising a plurality of mobile stations and a terrestrial system, and a plurality of cells, comprising the steps of: assigning, to a mobile station, a list of cells for measurement, where the list is divided into two sections, a permanent section and an external section, measure the quality level of each assigned cell, report quality levels to the terrestrial system, transfer a cell from the section alternates from the list, to the permanent section of the list, when the cell has a higher quality level than one of the cells in the permanent section, where the cell with the lowest level of quality in the permanent section is transferred to the alternate section, and change the cells listed in the alternate section each predetermined time period

Description

MOBILE ASSISTED TRANSFER ME TORADA FIELD OF THE INVENTION The present invention relates to a method for transferring a call in a mobile communication system, and particularly to a mobile assisted transmission method. BACKGROUND OF THE INVENTION In previous methods of mobile assisted transfer < MAHO), a mobile station normally measures the strength of the signal received from each neighboring cell whose measurement requests the ground system to the mobile station. In addition to measuring the strength of the signal, it is also often possible to request the mobile station to measure some cell characteristics such as a color code or an identification code in base station 5 transmitted by the carrier whose force must measure the mobile. The result of these measurements is reported to the terrestrial system by means of data messages sent in a? However, it is usually a limitation on the number of frequencies, that is, cells, that a mobile station may be asked to measure.Maximum common numbers are 12, 2, or bi. n 32. A deviation as to which annals to measure is normally transferred in a measurement order sent from the terrestrial system to the mobile station 5. The limitation, in most cases, is of minor importance. However, in dense urban areas, an umbrella cell can easily have 10-12 cells nearby umbrellas and with the introduction of microcells where another 5-10 microcelu can be expected to be under the umbrella cell, the cell number being You can go to the mobile station that you measure becomes a problematic limitation.While systems with the possibility of measuring 20 or 32 channels may be less susceptible to these images, systems that can measure only 12 channels such as the its T IS-54B standard U.S. are influenced by these limitations and not adapted for environments br s and microcells. In a more recent IS-54C standard, the number of measurement channels can be expanded up to 24 channels. But for all the older mS-s versions of mobile and digital scans, the limitation of 12 measurement channels remains. In an environment of microcosmic umbrellas mistas, there are different objectives as regards the ratio of the measurement of the shaded cells and the microcell 3 s, The reason > -)? - which the mobile stations should mediate neighboring parasol cells is evidently to detect if the mobile is coming out of the cell that it is currently using. Therefore, the primary objective is an uninterrupted service. Meanwhile, the reason for measuring my cell is to determine if there is a microcell that can serve the call instead of an umbrella cell. Therefore the objective is capacity. There is therefore a need to balance these ob ects. COMPFNDT OF THE INVENTION The present invention presents a mobile assisted transfer method for use in a cellular communication system comprising a plurality of cells. First, the quality level of a cell that a mobile station is currently using is measured to determine if the quality level is above or below a threshold. If the quality level is below the threshold, a primary list of cells is assigned to the mobile station, whereas if the quality level is higher than the threshold, a secondary list of cells is assigned to the mobile station. The quality level of each of the assigned cells is then measured by the mobile station and reported to the co-ion system. According to another mode of the present invention, a mobile station can be assigned a list of cells to be measured where the list is divided into two sections, a permanent section and an alternate section. E3 quality level of each assigned cell = > and measures and reports regularly to the communication system. After a predetermined period of time, the cells in the alternate section are changed allowing the mobile station to measure several cells. In addition, the list could also be divided into three sections, a fi xed section, a permanent section, and an alternate section. According to another embodiment of the present invention, the quality levels of a plurality of lul is measured in a mobile phase. The cells are then classified by quality and type level and the cells are measured in two lists. The mobile station is then assigned some d ^ 1 cells where the cells can be from either the lists or from both lists. The quality level of the assigned cells is measured regularly and reported to the terrestrial system for a deteation of transmission. BRIEF DESCRIPTION OF THE DRAWINGS These and other features and advantages of the present invention will be readily apparent to a person with certain knowledge in the art from the following description in combination with the drawings, wherein: Figure 1 is an illustration of a cellular radio system; Figure 2 is a block diagram illustrating several measurement lists in accordance with one embodiment of the present invention; Figure 3 is a flow diagram of a mobile transfer and assisted method according to an embodiment of the present invention; Figure 4 is an illustration of a measurement list in accordance with a variant of the present invention; Figure b is a block diagram illustrating several measurement lists in accordance with another embodiment of the present invention; and Figure 7 is a block diagram of a measurement view in accordance with one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Before describing the details of the present invention, it will present an example of the construction of a cellular radio system in which the present invention can be employed. Figure 1 is a schematic diagram illustrating \ cells, C1-C.0 in a cellular mobile radio telephone system. Typically, the method according to the present invention could be implemented in a cellular mobile radio system comprising more than 10 cells. However, for this description, the system presented here is considered as an isolated part of a larger system that has been fragmented. For each cell C1-C10, e; - this is a respective base station B1-B10. Figure 1 illustrates the base stations located in the vicinity of the respective centers of the cells and having antennas omru-di ec cu canvas 1 es. The base stations of adjacent cells may, however, be located in the vicinity of cell borders and have dihedral antennae. Figure 1 also illustrates 10 mobile stations M1-M10 that can be moved within a cell and from one cell to another cell. The method according to the present invention can be implemented in a cellular mobile radio system comprising much more than 10 mobile stations. Particularly, usually1 e; This is a much larger number of mobile stations than base stations. In FIG. 1, a mobile switching center SC is also illustrated. The mobile switching center MSC is connected to the base stations illustrated by means of cables. The mobile switching center YES? it is also connected by means of cables to a PSTN fixed public switched telephony network or to a similar fixed network with ISDN facilities. All cables from the mobile switching center to the base stations and 1 or cables to the network are not shown. In addition, other means may be used instead of cables for communication between the base and the mobile switching center, for example, fixed links. The cellular mobile radio system illustrated in Figure 1 includes a plurality of communication radio communication channels. The system is designed for analogue information, for example voice, analog information, for example, digital voice, and pure digital information, for example pure digital data. In the cante; of the present invention the term connection is used for a communication channel between a mobile station and another mobile station in the same system or in another system, between two fixed telephones or terminals in a fixed network connected through the system of mobile cellular radio telephony, either between a mobile station and a fixed telephone. Each cellular system is assigned a particular frequency band over which it can operate. A set of communication channels is assigned to each cell. For example, between 10 and 3 < "< different voice channels and a control channel can be assigned to each given cell." Several sets of communication channels must always be assigned to neighboring cells since, in order to maintain full radio coverage, the cells are spliced together. use of the same channels in adjacent cells would cause interference and co-ean in these splicing areas In accordance with one embodiment of the present invention, to the mobile station can be assigned one of vain lists as illustrated in figure 2. The mobile station can be assigned a first list of cells / frequencies for its measurement, where these cells are considered the most important cells its measurement, for example, surrounding umbrellas cells. However, if the quality of the cells is good enough, it is considered that the mobile station is inside the umbrella cell 5 that it is currently using and does not require a transfer to another parasol cell. As a result, can you ask =? the mobile station that measures the quality of other secondary cells that could be, for example, my ro the ul. The measurement of the quality could be 0 a signal strength, a proportion of errors in the tp uncles and / or a relation between the carrier and the interest. This embodiment is illustrated in the middle of the flow diagram shown in FIG. 3 »In step 10O, the mobile station and the quality of the call in r or with the cell 5 currently assigned. It is then determined in step 102 if the quality is higher than a predetermined threshold value.If the quality is above the predetermined threshold value, the cellular station assigns to the mobile station a secondary list of assigned cells in the cell. step <; "< 1 4, However, if the quality is not higher than the threshold value, the system assigns the mobile station a primary list of cells in the po>, where the primary list of cells is the closest neighbor cells. The quality of each of the assigned cells is then measured in case 1 8 and reported to the cellular system in step 110"to determine additional transfer ions. On a regular basis, or if the connection quality drops, you can ask the mobile station to measure the strength of the signal from the primary list or even after it has been assigned a secondary cell list. . for your measurement. Also, if any of the li -ita priman * and of the secondary list or both l? Sta = > • On less than 12 years, the l? = > n can be completed with cells from other list-. The previous modality is not ideal because the mobile unit can not sometimes hear the most important neighboring cells. One way to overcome the limitation ai riba presented e ~. sending the be mobile ion ¡m? list of assigned cells, some of them are permanently assigned and others in alternate form. For example, one umbrella cell has six neighboring shaded cells and 12 cells in each umbrella cell. Therefore, a mobile station that can measure only 1 anal s does not use all the neighbor cells and the micro cells at the same time. Ask that e ~ > The most important thing is to guarantee a service without interruption that temporary capacity improvements, all the neighboring cells should not be part of the measurement. In accordance > In a modi ily of the present invention, the first of the cells can be divided into two sections. A permanent section or section 40 and an alternate section 42 as illustrated in FIG. 4. With reference again to the example described above, the six parasol cells may be placed in the permanent section 40 of the list, while six the 12 microcells can be placed in the alternate section 42 of the list. If not - = > & If a good candidate is found, a new order can be sent to the cell phone that will continue to prevent the six neighboring cells in the permanent section 40 from the list and the other six cells in the list. section to erna 42 of the list. This pyro may continue during the call. With a larger cell-number *, more lists can be created and the mobile station will be asked to pti. in these lists. The sizes of the permanent and alternate sections of the lists do not need to be fixed and may vary from cell to cell. The selection of which cells go to 1 < * permanent section and which cells go to the alternate section can be predetermined based on l a e: p en in > : the p i i or the selection can be decided dynamically. In accordance with another embodiment of the present invention, all primary neighboring cells can be classified from the best or most important to the least important cell. In the same way, secondary secondary cells can be classified from the best1 to the worst. The content and order of the lists can either be fixed or based on prior knowledge or based on the current environment. For example, by studying a transfer pattern for a particular cell A, it may be possible to show statistically that 87 * of all transfers are made with four neighboring cells, 9V 'are made with three neighboring cells and the 4 * 4 remaining the transferences are made with the other three neighboring cells. From these data, it would be easy to classify the cells by importance and importance. However, the present invention is not limited to the above described example. The symbol illustrated in Figure 5 indicates that one unit of 12 ranales can be measured at a time. The number of primary cells or umbrellas cells and the number of secondary cells or my cells 52 listed in the order of measurement may vary according to the quality of the existing call. The higher the quality, a larger number of secondary cells can be included in the measurement order. In the same way, when the quality is more b = a, a greater number of primary ells should be included in the measurement order. This is illustrated by means of the horizontal bar 54 in Figure 5. As a standard, the quality can be measured in the amount of force of the signal, the proportion of errors in the b, or the relationship between the carrier and the interference. ia.

It is also possible to vary the mixture of the parasol and microcell cells according to the speed of the mobile station. The speed of the mobile station can be estimated by measuring the frequency of fading of a signal received from the mobile station in the terrestrial system in a known manner. It would be desirable to let a mobile station with rapid deployment reach more neighboring shade cells than microcellular cells. " In addition, it is also possible to decide on the ordering of the measurement order based on both quality and speed. An additional modality of the aforementioned techniques is the realization of a complete location of the mobile station and letting the result of the location determine which cells are listed in the measurement order. The location of the mobile station involves the steps of collecting the signal strengths from neighboring cells, comparing these forces against minimum thresholds, and adding vain hiters, is and c ompensa tion, and still useful manipulation. ational in the river *, esamiepto. After the processing of the measurement data, if a cell does not show a better signal strength than the cell. Currently, a transfer to this other cell is normally initiated. In addition, other criteria may also be considered before deciding whether a transfer is required, such as connection quality, bit error rate, carrier-to-inter-carrier relationship, etc. In accordance with one embodiment of the present invention, the mobile station is instructed to take quality measurements of up to 12 cells in a predetermined period of time. The mobile station to then add additional units or additional units of other cells. A location evaluation is then carried out and the 12 mi cells are selected. s is / is jores. The location evaluation can compare the strengths of the received signals well the levels: of quality that have been adjusted by means of a compensation value, where the compensation value can be used for certain base staci. These channels are milled during a predefined trip. Then, the 12 channels were changed by another 12 channels to evaluate if any of these channels has become the best transference candidate than the cells in the list of 12-higher as illustrated in figure 6. The 3 Í. I was added to a shorter period of time than the primary one and then the mobile station measured the quality of the 12 cells? strong / better, again. It is important to note that this primary line may be different from the previous primary list since the 12 strongest / best cells may have changed over time.

In another embodiment of the present invention, instead of alternating between groups of 12 channels, the list of selected cells can be divided into a plurality of sections, for example, a permanent section and an alternate section. In es + a mode, if u (\ cell in the alternate part is considered as better than a cell in the permanent sec- tion, this cell can be inserted in the permanent section and the lowest-ranking cell in the per- anent section is then transferred In addition, in some cases, it can be vital to constantly measure some of the neighboring cells.As a result, the cell is able to split the train And íons that contain a? section, a permanent section and a blunt alternate section is illustrated in? Figure 7. Therefore, some cells can be placed in a fixed section and can therefore be measured each time. One could also leave cells in the permanent section each time they qualify for this experiment, while cells that only qualify the alternate section will not always be monitored. It will be observed by persons with certain knowledge in the art that the present invention can be realized in other specific forms without departing either from the spirit or from the concept of "the same." The modalities presented here are therefore considered in all of them. the aspects as illustrative and not limitative The scope of the present invention is indicated in the appended claims and not in the foregoing description, and all the changes that are within the scope and range of equivalence of the rei indications are considered included in them.

Claims (25)

1. CLAIMS 1. A method for mobile assisted transfer in a cellular communication system comprising a plurality of mobile stations and a terrestrial system and a plurality of cells, comprising the steps of: assigning to a mobile station a list of cells for measurement, where said list is divided into two sections, a permanent section and an alternate section; measure the quality level of each assigned cell; report said quality levels to said terrestrial system; transfer a cell from the alternating section of the list to the permanent section of the list where the cell has a higher level of quality than one of the cells in the permanent section, where the cell with the lowest quality level in the permanent section will be referred to said section a terna; and changing said cells listed in said alternate section to a redeemed period of time.
2. 2. A mobile assisted transfer method according to claim 1, wherein said level of quality is determined by means of the signal strength.
3. 3. A mobile assisted transfer method according to claim 1, wherein said level of quality is deter- mined by means of a ratio of & r r '< =! ^ in the bios t ios.
4. 4. A mobile assisted transfer method in accordance with rei indicates ion 1, where said level of quality is determined by means of a relationship between the carrier and the interference.
5. 5. A mobile assisted transfer method according to claim 1, wherein said quality levels are adjusted in accordance with neither the precollects of • breakdown.
6. 6. A mobile assisted transfer method in a cellular communication system comprising a plurality of mobile stations and a terrestrial system and a plurality of cells, comprising the steps of: assigning to a mobile station a list of cells for its measurement, where said list is divided into two sections, a permanent section and an alternate section; me i the quality n3 ve3 of each assigned cell; report said quality levels to said terrestrial system; transfer a cell from the alternate list to the permanent section of the list when the cell has an adjusted quality level superior to one of the cells in the permanent section, where the section with the quality level adjusted or in the permanent section, I will go to said section to the office; and IB changing said cells listed in said section alternates each predetermined period of time.
7. 7. A mobile assisted transfer method in accordance with claim < , where said level of quality is determined by means of signal strength.
8. 8. A mobile transfer and assisted method according to claim 6, wherein said level of quality is determined by a proportion of errors in the uncles.
9. 9. A mobile assisted transfer method according to claim 6, wherein said level of quality is determined in a relationship between the carrier and the ferenc a.
10. 10. A mobile transfer and assisted method according to claim A, wherein said quality levels are adjusted in accordance with preclear levels of compensation.
11. 11. A mobile assisted transferep method in a cellular communication system1 comprising a plurality of mobile stations and a terrestrial system and a plurality of cells, comprising the steps of; assign to a mobile station a list of cells to be measured, where said list is divided into three sections, a fixed section, a permanent section and an alternate section, said fixed section with cells always being measured; measure the quality level of each assigned cell; report said quality levels to said terrestrial system; transfer a cell from the alternating section of the list to the permanent section of the list when said cell 11 has a higher quality level than one of the cells in the permanent section, where the cell with the quality level plus bo in the permanent section is transferred to that alternate section; and changing1 said cells listed in said section alternates each predetermined period of time.
12. 12. A mobile assisted reference method according to claim 11, wherein said level of quality is determined by the strength of the signal.
13. 13. A mobile assisted transfer method in accordance with rei indicates i n 11, where said level of quality is determined by a proportion of errors in the bits.
14. 14. A mobile assisted transfer method in accordance with the indication lt, where said level of quality is determined by means of a relationship between the carrier and the interference.
15. 15. A mobile assisted transfer method according to claim 11, wherein said quality levels are adjusted in accordance with rele- vated compensation levels. you. A mobile assisted transference method in a cellular communication system comprising a plurality of mobile stations and a terrestrial system and a plurality of cells, comprising the steps of: assigning to a mobile station a list of cells to be measured, where said list is divided into three sections, a fixed section, a permanent section and an alternating section, said fixed section contains cells that are measured at the same time; measure the quality level of each assigned cell; to report said quality levels to said terre re system; transfer a -cell from the se > alternating the list to the permanent section of the list when said cell has a quality level set higher than one of the cells in the permanent section, where the cell with the lowest quality level set in IB permanent section is transferred to said cell. alternate section; and changing said cells listed in said section alternates each predetermined period of time. I "7. An assisted transfer method m-. V? 3 in accordance with 13 claimed in 16, wherein said level of quality is determined by means of the signal strength 18. A mobile assisted transfer method of In accordance with claim 16, where the quality level is determined, it determines the average of a "bug fix" in the bits. 19. A mobile assisted transfer method according to claim 16, wherein said level of quality is determined by means of a relationship between the carrier and the interference. 20. A mobile assisted transfer method according to claim 1, wherein said quality level s are adjusted in accordance with pre-defined levels of compensating i n. 21. A communication system with mobile assisted transmission comprising a plurality of mobile stations and a terrestrial system and a plural number of cells comprising: a device for assigning a list of cells to be measured to a mobile station, where said list is It divides into two sections, a permanent section and an alternate section; device to go the level of quality of each cell ignate; device to report the quality levels to said terrestrial system; device to transfer a cell from the alternating section of the list to the permanent section of the list when said cell has a quality level higher than one of the cells in the permanent section, where the cell with the highest quality level ba or in the permanent section is transferred to said alternate section; and device for changing said cells listed in said section alternates each predetermined period of time. 22. A communication system according to claim 21, wherein said level of ali d is determined by means of signal strength. 23. A communication system according to claim 21, wherein said level of quality is determined by means of a proportion of errors in the bits. 24. A communication system according to claim 21, wherein said level of quality is determined by means of a relationship between the carrier and the inter- ference. 25. A communication system in accordance with claim 21, wherein said quality levels are adjusted in accordance with preca 1 levels c-compensated i n.