SE514844C2 - Hand=off in mobile telecommunication system - Google Patents

Abstract

The hand-off method involves choosing at least two telecommunication parameters as hand-off parameters to provide the basis for a hand-off decision, according to their measured values. The measured values are used as inputs to a fuzzy-logic circuit, including membership functions and fuzzy condition sets. The fuzzy condition sets are executed with the determined hand-off values and the consequences weighted to form a crisp-value, used to make the hand-off decision. The appts. has a fuzzy-processing unit (3) for grouping parameters and executing rules, an average-, complement-, maximum and minimum unit (4) for determining the crisp-values, and an evaluating unit (5).

Description

20 25 30 2 parameter setting, which form the basis for handover decisions. To take an example, in some cases 80 parameters per BS may be needed. The "locating" calculations therefore require extensive signaling and calculation capacity in the mobile telephony exchange and between exchanges, respectively. Switches here refer to MSCs (Mobile Services Switching Centers) or BSCs (Base Station Controllers).

The "locating" calculations take place in the exchange part called TFtH (T ransceiver Handler), which also prepares Candidate Lists, ie lists that rank BSs as candidates for handover. The handover function in TBH views the candidate list, allocates and activates a channel and orders the MS to switch to a new channel. The BSs which have a signal strength higher than a certain lower threshold M eg -90dBm but less than an upper threshold K = 0 eg -60 dBm are ranked according to the K criterion. The K-criterion is in principle a ranking from the highest to the lowest signal strength, penalties included.

Signal strengths below the M value are not ranked. The BSs that have signal strength above K are considered to have sufficient strength and are ranked according to the L criterion, which takes into account, for example, tensile attenuation and punishment. Penalties are awarded to BS who, for example, have failed to process an ordered handover. The punishment is often expressed in an extra allocation of attenuation, in the candidate list, to the BS who has failed to process a handover. The penalties are also taken into account in the K-criterion and in the event of a breach of the M-threshold. Thus, with the L criterion, the BS with the highest signal strength does not have to end up at the top of the hierarchy. Obtained measured values are equalized average values over a certain period of time, eg 480 ms in GSM.

As is clear from the state of the art, in principle only the signal strength is considered in the "locating" algorithm, however, as much as 80 parameters may have to be used for a cell "site" (BS physical location). claim, it is easy to imagine what problems arise if additional variables are considered in the "locating" procedure.

It should be added that other manufacturers of mobile phone systems do not use the "path loss" criterion in the "locating" algorithm. Other telecommunications companies also have their own designations for exchange units (MSC, BSC), which for that reason does not limit the invention to only applicable ERICSSON units. 10 15 20 25 30 r 8.4.4 '3 The following is a general description of how "fuzzy" - | ogik is used and its evaluation methods: "Fuzzy" logic is generally a generalization (extension) of classical algebra where divalent Booelsk algebra is a subset. The "fuzzy" logic that the invention incorporates is called the "max-min method". The method is based on the use of the logical operators "AND" and "OR" as well as the complement. The most popular and usually fully sufficient is the AND operator. When comparing variables in "fuzzy" logic, for example, the ANDEminimumEsection, the Oläšmaximumaunion are read and the complement is as usual.

AND selects the min variable and OR selects the max variable.

The continued approach is broadly as follows: a. Assign each invariant at least two quantities for meaningful comparisons. b. Assign each variable set an belonging function W, ie a function that defines the set. The functions in "fuzzy" logic often but not necessarily assume values between 0 and 1 on the ordinate (Y-axis, "co-domain"). In any case, the values are normalized. On the abscissa (X-axis), the domain in which the quantity assumes values (preferably numbered) is defined. c. Set up linguistic adjective expressions for comparisons between variables. d. Form "lF" and "THEN" sentences, which are conditional sentences of adjective expressions. "iF" and "THEN" are linked together by the logic operators. e. All expressions according to d. form a rulebase which is traversed sequentially by the values of the compared variables, parameters (antecedents in the condition sets). f. Each rule (condition set) produces an output value that affects a set 10 10 20 20 25 30 4 defined, via its affiliation function, pp. The value is called "firing-value" or "rule-finding". G. The values that arise when the output is affected are called "consequences". H. , or the "centroid" method ("Center of Gravity", "Momentum"), which produces the "crisp" method for any further evaluation. In the case of the invention, "crisp" values are used to update the candidate list.

Patent application EP, A2, 424 890 describes in an excellent way the approach to the centroid method. The state of the art regarding "fuzzy" hardware and the data communication between input devices is also reported in the document and is hereinafter considered known, especially when the present application states that the hardware may consist of a control unit, an application memory for sequential user instructions and "fuzzy". conclusion instructions.

To further relate to the state of the art, it is known to us an attempt, to use "funy" logic in mobile telephony published as "Fuzzy Handoff Control Using Leamt Cell Boundary for Radio PBX", author Y.Kinoshita &# et al, Dept. of Electrical and Electronics Engineering Chiba University, Chiba, 260 Japan. The document describes the use of "fuzzy" - | ogik in the form of a method for mapping the surface of a cell in X and Y coordinates and to learn the cell surface through simulations with "fuzzy" logic. So you do not use actively and in real time " fuzzy ”logic for handover decisions, which our invention claims.

Almost all terminology in "fuzzy-set" theory is derived from English (US-English).

Since many terms do not have a good equivalent in the Swedish language or are even translated, please be forgiving regarding the use of language. Roughly 10 15 20 25 30 ilfsïi1 ~ 4 in 3144. 5 adequate translations are provided, however. Here are examples of such "fuzzy" logic (blurry logic), "crisp value" (most likely to be interpreted as precise value), "firing value" (output from a rule), "antecedent" (precursor to output from rule) and "set" §mount.

DISCLOSURE OF THE INVENTION The method and apparatus of the present invention seek to replace or simplify the locating process with "fuzzy- | ogic" technology so that several variables and parameters can be weighed together for handover decisions, thus achieving soft handover decisions i.e. "Fuzzy" hardware and / or "fuzzy" software work according to the principle of minimal specification, and are also said to mimic the human way of assessing information, which is why situations such as those in the "locating" algorithm with a variety of comparisons are avoided. largely. It is also possible to minimize the necessary software. "Fuzzy" software can be realized in pure "fuzzy" hardware. This is a strength in the development of new systems, methods, products, etc. ie development and testing takes place with software. When development and simulations are performed with the desired result, the hardware is produced from the software, eg via the source code, leads to greatly reduced times from idea stage to finished product. As "fuzzy" logic for soft decisions, hysteresis can be minimized or, if desired, avoided.

It is of great importance in a cell pattern such as 3/9, 4/12, 7/21 etc, that a mobile (MS) is connected to the correct cell. This is especially true for 3/9 and 4/12 cell patterns due to the smaller frequency re-use distance ("co-channel reuse"), which is due to C / I (Carrier-to-Interference ratio) problems. The hysteresis of cell boundaries can therefore not be set too high. One problem that can arise with low-level hysteresis is the unwanted so-called "ping pong" effect, which means that an MS oscillates handover back and forth across cell boundaries. The hysteresis is equated, with different signs, on both sides of the cell boundaries precisely to avoid the said effect due to, for example, fading dips or "dead spots". Since the tensile attenuation from affected BSs is approximately equal, a cell-crossing MS may maintain its connection to serving BS a signal strength hysteresis.

The following variables and parameters, measured by the mobile and / or base station, can be used as input in the "fuzzy" method and for the "fuzzy" device: a. FiXLEV_DLšReceiver level-DownLink (BS to MS), which is the received signal strength of the MS. the value ranges from 0..63, where 0 represents -1 10 dBm and 63 represents -48dBm. b. RXLEV_ULE Receiver Level_UpLink (MS to BS), which is BS's received signal strength. ) EReceiver Level_Neighbouring Cell (n), which is the measured signal strength in MS from neighboring cell no. Nnreported value according to RXLEV_DL above.

Usually the candidate list occupies only 6 neighboring cells, but in eg GSM the mobile phone must be able to measure 32 neighboring cells. d. RXQUAL_DLEFteceiver Qualíty_DownLink, this variable represents the estimated BER for MS received data bursts. Reported values range from 0..7, where 0 is less than 0.2% and 7 corresponds to more than 12.8%. e. RXQUAL_ULEReceiver Quality_ UpLink, which is estimated BER on data received by BS. Same route (area) as for RXQUAL_DL above. f. TAšTiming (Advance or Alignment) is the measured distance between MS and BS.

The distance is calculated from the running time of the radio signal between MS and BS. g. Stored parameters such as transmitted power from neighboring base stations, distance attenuation, C / I, C / A, C / R where CšCarrier, Iëlnterference, A = -Adjacent, FiEReflexion and other parameters specified in the GSM recommendation under eg GSM Recom. 10 15 20 25 30 r rs> 1ltlrasr4r4 03.03, 04.08 and 05.08 (the "locating" algorithm).

The following parameters have ERICSSON specific designations, which, however, have their equivalent in GSM: Parameter TINIT TALLOC TALARM TDATA Range 0-120 0-120 0-600 1-5 Unit * SACCH period (480ms) * SACCH period (480ms) deci-seconds * SAACH (Slow Associated Control Channel) sends measured values from MS to BS.

Parameter EVALTYPE SSHANDF SSBQ SSTA THANDF TBQ 'ITA QLIMDL QLIMUL TALIM MAXTA MISSNM SELEC1 SELEC2 SSPAR SSPAR1 Area r 1 -2 O-63 0-63 0-63 0-600 0-600 0-600 0-1 00 0-1 00 0 -63 0-63 0-1 8 -500-500 -500-500 -1 0-1 0 -500-500 Unit dB dB dB seconds seconds seconds seconds decl-converted GSM quality units deci-converted GSM quality units GSM bit periods GSM bit periods dBm dBm deci units dBm 10 15 20 25 30 ÉS% 4 844 8 SSPARZ -500-500 dBm LPAFH -500-500 dBm LPAR2 -500-500 dBm HYSTABS 0-63 dB HYSTREL 0-63 dB MAXREP O-20 EXREP 1-20 TAAVELEN 1-40 ALNO 1-6 In general, the invention is system independent and variables, parameters are adapted to the intended system and its recommendations. By systems is meant here such as GSM, ADC (Digital-AMPS), JDC (ERICSSONS Japanese mobile phone system), NMT 450, NMT 900, DECT, C-NETZ, AMPS, TACS, N-AMPS, CT-3 or any system where handover (handoff) occurs. At least two variables or parameters must be input to a "fuzzy" hardware system, a combination of "fuzzy" hardware and "fuzzy" software or pure "fuzzy" software. RXLEV__NCELL (n) be an invariable because the signal strength from a neighboring cell is the most important variable in intercell handover (handover to another cell).

If many invariables or parameters are selected as input data, these are divided according to the invention into groups of at least two variables and / or parameters. These can individually occur in more than one group and also occur doubled, tripled, etc., then with values from different measurement times. Each group produces a "crisp value" as output. The output of the group or groups is then processed according to the invention by an average maximum-minimum forming unit (A / M / M). Its evaluations are used for handover evaluation (evaluation) in a handover evaluating unit according to the invention; HED which updates the candidate list used in the current system or in a candidate list according to the invention. It should also be noted that it is possible to provide the evaluation _all variables, parameters, rule consequence values and the rules' "firing values" for possible evaluation together with the values produced by the A / M / M unit and parameter values obtained from MSC or BSC.

FiaunFönrackuiNe Fig. 1 shows cellular mobile telephone system with base stations and mobile stations; Fig. 2 shows an example of a "fuzzy" hardware system according to the invention; Fig. 3 (a, b, c, d, e, f) shows an example of evaluation of two "fuzzy" rules with their belonging functions; 4a and 4b show candidate lists for a mobile station.

PREFERRED EMBODIMENTS: Figure 1 illustrates ten cells, designated C1 to C10, in a cellular mobile radio system. For each cell C1 to C10 there is a base station, designated B1 to B10. The base stations are located in the middle of each cell and have omnidirectional antennas. All base stations are connected to a mobile radio exchange, designated MSC, with cables or other fixed information transmission means, eg radio links. The mobile radio exchange is also connected to a fixed telecommunication network with cables or links. For the sake of clarity, Figure 1 does not illustrate the fixed telecommunication network, nor all the cables or links to and from the mobile radio exchange.

Figure 1 also illustrates ten mobile stations, designated M1 to M10. The mobile stations can be small, portable mobile stations, such as pocket telephones, or more bulky mobile stations installed in vehicles and powered by the vehicle's electrical system.

During operation, the mobile stations can communicate with the fixed part of the mobile radio system by receiving radio signals from the base stations and / or transmitting radio signals to the base stations. Connections for telephone calls, fax, data transmission or for the transmission of other information can be connected between one of the mobile stations and another of the mobile stations or a subscriber in the fixed telecommunication network. Group conversations with three or more parties can also be connected.

Connections in this application refer to all types of connections that can be connected and where at least one mobile station transmits or receives information via the connection, regardless of whether it is a connection with one or more parties in the fixed network or one or more other mobile stations, and regardless of whether it is a mobile station or a subscriber in the fixed network that initiated the connection of the connection.

The mobile radio system illustrated in Figure 1 is a simplification compared to most mobile radio systems. The simplification has been made to facilitate the understanding of the invention. Normally a mobile radio system contains more cells and base stations.

The cell structure may be more complicated with umbrella cells covering an area also covered by a number of microcells. It is common to place base stations with sector antennas adjacent to cell boundaries. It is conceivable that some cells may be served by more than one base station. There may be more than one mobile radio exchange, some of the base stations being connected to different mobile radio exchanges. Finally, the number of mobile stations is normally much larger than ten.

The mobile stations are movable within a cell and from one cell to another cell. Depending on the location of a mobile station, which connections are connected to other mobile stations, radio signal propagation conditions and radio interference, there is a need to use another base station for a connected connection to the mobile station. To change base station, so-called handover, a decision basis is needed so that you know when to switch and to which base station to switch.

In order to obtain a decision basis for handover, a mobile station with a connected connection determines values of radio signal parameters of received radio signals by measuring or estimating and reports the results of the measurements and the estimates to the base station serving the mobile station, respectively. Normally, the mobile station receives radio signals both from its own base station serving the mobile station and from other nearby base stations. The reported values then refer to values of radio signal parameters also for some of these nearby.

The mobile stations can also report parameter values determined in other ways than by measurement or estimation based on received radio signals, eg the power with which the mobile station is currently transmitting, which values can also be used as a basis for handover.

The base stations also determine values of radio signal parameters of received radio signals from mobile stations by measuring or estimating based on the received radio signals. In addition, the base stations can also determine values of parameters other than by measuring radio signals. Such a parameter can be the total available communication capacity of the base station and how much of this total capacity is available. Normally, this communication capacity is expressed in channels, whereby a connection usually requires one channel but in some cases more than one channel.

It is conceivable that bodies other than base stations and mobile stations in a system comprising wireless telecommunications can also determine values of parameters as a basis for decisions on handoff in the mobile radio system. If, for example, the mobile radio system has more than one mobile radio exchange to which the telecommunication network is connected, it is in some situations conceivable that the traffic conditions in the telecommunication network are important for the choice of mobile radio exchange and thus base station when possible.

It is known that evaluation of the basis for decisions on handover and decisions on handover can take place in different parts of a mobile radio system. In some mobile radio systems according to Figure 1, this is performed only by the mobile radio exchange or corresponding means. In other mobile radio systems according to Figure 1, more or less of this is performed in the respective base station.

Some mobile radio systems, in contrast to Figure 1, have their base stations connected in groups to superior means, so-called base station controllers, which in turn are connected to means partly corresponding to the mobile radio exchange in Figure 1. In such systems, f 15; 8 44 12 evaluation and decisions concerning handover more or less fl performed by these so-called base station controllers.

Methods and devices for measuring and estimating radio signal parameters and reporting care within a mobile radio system are well known. For a method or a device according to the invention, it is normally insignificant or at least of secondary importance if evaluation of parameters is carried out in whole or in part by the respective base station or base station controller or mobile radio exchange or corresponding means in the telecommunication system. Neither the determination of values of parameters nor the reporting of parameter values to the body that uses them for evaluation and decisions will therefore be described in more detail.

An embodiment of a device for processing values of parameters to a basis for handover decisions and for handover decisions is illustrated in Figure 2.

The device includes "fuzzy" logic hardware. All invariables to the system are averaged over a certain time, eg 480 ms in GSM, and equalized via filters, FlR filters 1, which are forwarded to a common or several data buffers 2, here LIFO buffers 2 (Last ln First Out ). Input data to the "fuzzy" logic processing unit 3 is divided into the aforementioned groups where variables and parameters can be placed in more than one group. The groups can also be assigned different priorities for later evaluation, ie a special group (s) can be considered more important for obtaining the best hand evaluation. The "Fuzzy" logic processing unit 3 is either entirely hardware, a combination (hybrid) of hardware and software or built up of software only. Suitable hardware for the manufacture of the unit is marketed by several companies such as OMRON, TOGAl INFRA LOGIC CORP. , SIEMENS etc. It is optional if each group should have its own rule table (rule base) or if they should share a central.

Note: the table (s) may be implemented in terms of software or hardware. The flag tables are implemented in the form of lF and THEN conditions where the conditions IF and THEN are connected with operators from the max-min model. The THEN expression can also be evaluated according to the max-min model in cases with several output function functions in the THEN expression. The "firing" values of the THEN expression affect the output affiliation functions according to the rules of one of the evaluation methods. When all the rules have been reviewed, preferably sequentially, the consequences of all the rules are evaluated as the chosen evaluation method prescribes as follows: a. "Max-Height" means that the maximum value of the consequences constitutes the "crisp" value. b. "Average" leads to the averaging of the consequences, as will be seen in a future example. c. The "Centroid" method, which is based on a weighting of centers of gravity for interfaces between affiliation sets. The weighting results in a "crisp" value ("deffuzzy" value).

The "crisp" value (s) are then sent to the A / M / M unit, where the max, min and average "crisp" values are obtained. No mean value is obtained when the "fuzzy" processing unit 3 only consists of a group without the A / M / M unit 4 then leaving only one value namely the only "crisp" value or alternatively the max, min and mean value of As partly mentioned earlier, you have access to all input data, "firing" values and the consequence values if desired.

The values from the A / M / M unit 4 were in turn sent to the HED unit 5 for partial decision, partial decision or final handover decision. The HED unit 5 communicates in duplex or full duplex with a BSC and / or MSC from which the unit can obtain supplementary information such as candidate lists, variables, parameters, etc. The HED unit can also provide information to the BSC / MSC.

Furthermore, the decisions in A / M / M 4 and HED 5 can be made in whole or in part by "fuzzy" logic. In an embodiment of the invention, the candidate list is available in HED 5, where the list contains fields or entries with a ranking of own BS (serving cell) and neighboring base cells. The list may contain more information than is currently the case, for example, it would be advantageous if it also contained an approximate measure of the number of free speech channels in 10 15 20 25 30 'in 8944,' in 14 fields or records. Alternatively, the candidate list contains the same information as in the current system.

The "fuzzy" hardware is controlled via one or more processors such as microprocessors, then preferably "fuzzy" processors, which are manufactured by the aforementioned companies. The units 1, 2, 3, 4 and 5 are controlled by a control unit 6 possibly via a bus structure. The hardware may consist of a control unit 6, an application memory for sequential user instructions and "fuzzy" conclusion instructions, for the state of the art see EP, A2, 424 890. The control unit 6 controls the L1FO buffers 2, the "fuzzy" processing unit 3 with its memories , The A / M / M unit 4, the HED unit 5 and its communication with the outside world. It is also possible to control the communication from the exchange unit. In general, data communication follows principles which are well known to those skilled in the art.

The hardware units are installed in or next to MS, BTS (Base Station System), BSC or MSC. If the system is installed in or next to BTS, BSC or MSC, the possibility arises that the hardware unit can service all MSs that are connected to the same cell-site. The hardware unit can also serve all MSs where the signaling is controlled by the same BSC or that all MSs are connected to their respective hardware unit depending on the system design.

The fact that the hardware device can also be placed in MS is supported by the fact that GSM introduces MAHO (Mobile Assisted HandOff).

Example 1.

Here now follows an embodiment which in itself only exemplifies a possible application among many in a handover decision system according to the invention. The example uses two input variables RXLEV_UL and RXLEV_NCELL (1) defined by their affiliation to two sets each, namely FIXLEV_UL large measurement value, RXLEV_UL small measurement value, RXLEV__NCELL (1) large measurement value and RXLEV_s value of value (1) values range between 0.0 and 1.0 and define how large or small affiliation each measured value has to the defined 10 15 20 25 30 å5 ïtt41 s 44gi 15 quantity. The output function has also been assigned two sets with its affiliation functions, namely large affiliation to NCELL (n) and small affiliation to NCELL (n). Between the diagram lines in Figure 3, the instantaneous input variables RXLEV_UL and RXLEV_NCELL (1) 1 are shown for neighboring cell no. signal strength value. In the example, input data is obtained from mobile station M6 (Fig. 1) and the mobile is connected to serving base station B1. RXLEV_NCELL (1) derives from the neighboring base B6 and RXLEV_UL measured values from M6. For the sake of simplicity, only two rules are analyzed in the example, which, however, is fully sufficient to understand the procedure: R1: IF FtXLEV_UL has a large measured value AND RXLEV_NCELL (n) has a small measured value THEN low affiliation to NCELL (n).

Ft2: IF RXLEV_UL has a small measurement value AND RXLEV_NCELL (n) has a large measurement value THEN a large affiliation to NCELL (n).

To facilitate the understanding of the following examples, some clarifications follow.

The affiliation value for RXLEV_UL = u instantaneous value is denoted A (u) and the corresponding value for RXLEV_NCELL (n) = v is B (v). The affiliation values A (u) and B (v) are obtained by designating the instantaneous values, whose domain is on the X-axis in Figures 3 (a, b, d, e), the affiliation value on the Y-axis. The values obtained in this way form antecedents in the rules which are compared with the min-operator (AND). The min value then obtained implies via the THEN expression a definite affiliation function (exterior function) in Figures 3 (c, f), by pointing out via the Y-axis, with the min value, an X-axis value according to one of the exterior functions, which is called the rule consequence and here is denoted Z (A (u)) or Z (B (v)). When all rules have been run sequentially for a set of instantaneous values, all Z () values are weighted. In the example according to the mean value method with a "crisp" value ("defuzzy" value) as a result, the "crisp" value is then updated with a candidate list according to Figures 4 (a, b). ~ According to the max-min model, with reference to Fig. 3 (a, b, c, d, e, f) the following occurs: 10 15 20 25 30 16 Given RXLEV_UL = u = 30 dB and RXLEV_N- CELL (1) = v = 38. The linguistic expression of rule 1 says that u = 30 dB gets its affiliation value A (30) = O.31 to the amount RXLEV_UL large measured value from Fig. 3a (dotted line). The expression for rule 1 further says that v = 38 dB gets its affiliation value B ( 38) = 0.41 to the amount RXLEV_NCELL (1) small measurement value from Fig. 3e (dotted line).

The belongings A (30) and B (38) are then compared according to the IF expression in rule 1 the condition set with the mine operator AND with the result that A (30) = O.31 is selected. Then the instantaneous input values for THEN take on the expression, which according to the linguistic expression for rule 1 says that the minimum value A (30) = O.31 should imply the output quantity low belonging to NCELL (1), fig. 3f. On the Y-axis, in Fig. 3f, for A (30) = O.31, the corresponding X-value denoted Z (A (30) = 0.31) = 70 is read, constituting the consequence value for rule 1. The next step will be to execute rule 2 with the same procedure as for rule 1. According to the linguistic expression for rule 2, the affiliation A (30) = O.70 is obtained from Fig. 3d and from Fig. 3b B (38) = 0.65. In the comparison in rule 2 with the minoperator AND between A (30) = O.70 and B (38) = 0.65 it is obtained that B (38) = 0.65 according to the THEN expression in rule 2 shall imply the output data large affiliation to NCELL (1) fig 3c. On the Y-axis, in Figure 3c, for B (38) = 0.65, the corresponding X-value denoted Z (B (38) = O.65) = 65 constitutes the consequential value for rule 2. Consequently, the rule table with the rules Ftt and F22 were run sequentially and the evaluation of the consequences of the rules is done with the mean value method as below.

Here, a brief summary, in rule form, of the above TGSOFIGITIGTIQ is first presented.

F11: iF A (so) = o.s1 AND B (38) = 0.41 THEN Z (A (30) = 0.31) = 70 H2: IF A (30) = O.70 AND B (38) = 0.65 THEN z (ß (ss) = o.ss) = es The mean value method states that the impact values in the example should be weighted as follows to obtain a "crisp" value ("defuzzy" value): 10 15 20 25 30 s .1 4 ee 4 4. 17 c fi sp = (belonging to rm NCELL (1)) = A (so) * z (A (so)) + B (3s) * z (B (sa)) / A (so) + ß (ss) = (o , s1) (7o) + (o, es) (es) / (o, s1 + o, es) e 67 within a range from 0 to 100 ie the mobile station should belong to NCELL (1) with unit 67 and current serving cell with unit 100-67 = 33.

The procedure shown above is repeated cyclically with comparisons between, for example, 6 neighboring cells and the serving cell for the mobile M6.

The parameter RXLEV_UL belongs to serving cell B1 (own cell) and mobile M6.

RXLEV_NCELL (1) belongs to neighboring cell 1 (B6 in Fig. 1). With the obtained "crisp" values 67 and 33, it is now shown, in Figs. 4a and 4b, how a candidate list is updated. The list is based on the cell pattern according to Fig. 1.

Before updating, the candidate list looks according to Fig. 4a with neighboring cell 1 (B6) at the top of the hierarchy and serving cell B1 at the third level in the list. The candidate list is now updated with the "crisp" values 67 and 33 according to Fig. 4b. Since neighboring cell 1 (B6) is the best cell, this means that own cell B1 receives its worst complement and own cell must be updated with the complement in the Candidate List (Fig. 4b). The neighboring cells are always updated with their new value. Note that the candidate lists in Fig. 4 (a, b) belong to the mobile M6. In this example, a min threshold level, which indicates when M6 should be allowed to do handover has been selected to 35, ie when the complement value for own cell is close to or below 35, a decision on handover should be made, for example, to one of the neighboring cells B6 or B7. The example gave the complementary "crisp" value 33 for own cell and consequently a handover decision will be executed according to the candidate list in Fig. 4b.

It should be pointed out that it is optional which adequate affiliation functions are chosen, ie not necessarily linear. But linear functions are often good and they are easy to store in memories, ie all functions that are triangular or trapezoid can be stored in memories, as three points with their vertex as coordinates, here reference is made to EP, A2, 424 890. This leads to simple calculations of the intersection points of the variables with a 10 15 20 25 30 ïši: r 4.1 .'rå.é 44 in 18 line according to the line equation. With trapezoidal functions, the position of the origin is implied.

If you instead use the centroid method for evaluation to obtain the "crisp" value, the procedure is as follows: Ftegel output implies the output data function so that the vertex is moved to the rule output value ("firing" value) and the overlapping quantity surfaces S1, S2, ..., SN and their centers of gravity G1, G2, ..., GN are weighted according to Cn-sp: S1 * G1 + S2 * G2 + ... + SN-1 * GN-1 + SN * GN / S1 + S2 + ... + SN-1 + SN, for information refer to EP, A2, 424 890. more detailed As before, RXLEV_NCELL (n) should always be invariable to at least one group during intercell handover, it is also advantageous that RXLEV_UL belongs to at least one of RXLEV_NCELL (n) s Assume that RXLEV_UL also forms a group with RXQUAL_UL. cell compared to the specific neighboring cell NCELL (X). If the group to which RXLEV_NCELL (X) belongs gives the best "crisp" value and the "crisp" value of the other group is equal to or less than a minus threshold value, it is necessary to hand over according to the candidate list. The candidate list should be updated at least with the value from at least one group to which F {XLEV_NCELL (N) belongs. The "crisp" values of several groups can also be used to update the candidate list.

Example 2.

The "fuzzy" part is the same in this alternative example. The alternative is that variables and parameters are doubled, tripled, etc., ie the same variable serves as input data in duplicate, triplet, etc. to any variable parameter group. One or more of these input variables or input parameters then carries the last value obtained and the other (s) some suitable previous value, eg the nearest previous value or even earlier care. This procedure requires that the previous current value (s) has been saved. The method includes that each group is supplied with at least two input variables or input parameters, but that it can be the same variables (duplicates, triplets, etc.) but with time-shifted values. In other respects, the procedure follows the previous one with minor adjustments. It is by no means obvious to compare several variables in order to obtain smoother and safer handover decisions. Today's "locating" procedure would quickly become unmanageable. Regarding "fuzzy" logic, its practical applications, at present, are not a matter of course. Almost all applications occur in control technology. The knowledge that this technology is equally useful for decision-making seems to have passed almost unnoticed. Implementing the technology for decision-making, in real time, in telecommunications should therefore not be perceived as professional. Handover in eg non-cellular mobile phone systems requires extensive knowledge of "locating" and to also master "fuzzy" logic is today almost excluded. classified project, according to the invention, to take part in how "fuzzy" is applied and works in practice.

Claims (1)

A patent in a system comprising wireless communication, wherein at least two telecommunication parameters are selected to be included as handover parameters as a basis for decision on handover, and actual values of the handover parameters are measured, can be used to indicate the measuring the values including affiliation functions and fuzzy condition sets as inputs to fuzzy logic, executing the fuzzy condition sets with the determined values of the handover parameters, weighting consequences from the executed fuzzy condition sets to a well-defined value and using the defined value concerning handover. Method according to claim 1, characterized in that at least two parameter groups are formed, that at least one condition set for each parameter group is formed and executed, and that well-defined values from both condition sets are used. Method according to claim 2, characterized in that a parameter group contains at least two of the parameters received power from neighboring base stations (FtXLEV_NCELL (n)), received power in uplink (RXLEV_UL) and received power in downlink (FtXLEV_DL). Method according to claim 2, characterized in that a parameter group contains the parameters received power from neighboring base stations (RXLEV_N-CELL (n)), received power in uplink (RXLEV__UL) and received power in downlink (RXLEV_DL). Method according to claim 1 or 2, characterized in that the number of available radio channels at a base station is one of the handover parameters. 10 15 20 25 10. 11. i i 844; 21 A method according to claim 1 or 5, characterized in that the condition sets together contain at least four different parameters. Method according to any one of claims 1-6, characterized in that at least one list of handover candidates is established with a ranking based on well-defined values from condition sets in which an effect received from handover parameters from neighboring base statons (RXLEV_NCELL (n)), received effect in uplink (RXLEV_UL) and received downlink power (RXLEV_DL) are included. Method according to claim 7, characterized in that the candidate list contains information about the approximate available communication capacity of the candidates included in the candidate list. Procedure according to one of Claims 1 to 6, characterized in that an existing list of candidates is updated with the aid of well-defined values. Method according to one of the preceding claims, characterized in that the belonging functions are linear, ie form triangles or trapezoids if their vertex is connected. Method according to one of the preceding claims, characterized in that the fuzzy condition sets are executed partly with last determined values of handover parameters and partly with previously determined values of the handover parameters, and that both consequences from execution with previous values and consequences from execution with last determined values are weighted to well-defined values. 10 15 20 25 12. 13. 14. r rí t5> 1s 4 a -44 22 Method according to claim 1 or 2, characterized in that the handover parameters are selected from received power in downlink (RXLEV_DL, received power in uplink ( RXLEV_UL), power received from neighboring base stations (RXLEV_NCELL (n)), data quality in downlink (RXQUAL_DL), data quality in uplink (RXQUAL_UL), TA, transmitted power from neighboring base stations, line attenuation, C / l, C / A and C / R. according to any one of the preceding claims in a cellular mobile radio system with base stations and mobile stations, characterized in that both the base stations and the mobile stations measure radio signal parameters for received radio signals, that the mobile stations report measurement results to the base stations, and that both measurement results from the base stations and the measurement stations are used. Device for producing data for handover based on at least two radio signal parameters in a system comprising wireless telecommunication, characterize at least one data buffer (2) for receiving values of at least two parameters, of a "fuzzy" processing unit (3) for executing fuzzy condition sets with values of the parameters, in which condition sets operators compare the parameters of the parameter values to input quantities and depending on the result of the comparison, an affiliation function specified by the condition statement implies an output quantity so that a consequence is obtained, by a unit (4) for weighting consequences from the fuzzy handling unit to at least one defined value, and by a hand-deciding unit ( 5) for generating a basis for decisions on handover in dependence on well-defined values. Device according to claim 14, characterized in that the processing unit comprises a "fuzzy" control unit (6), an application memory for sequential user input ions. and "fuzzy" conclusion instructions and that the control unit controls the data flow from and between the buffer (s), the unit (4) for weighting of consequences and the hand-deciding unit (5) in harmony with the gear unit. Device according to claim 15, characterized in that the gear unit is a BSC or an MSC. Device according to claim 16, characterized in that if only one group is formed in the treatment unit (3), the unit (4) for weighting consequences makes its decisions on the consequence values and the only well-defined value. Device according to claim 16 or 17, characterized in that the hand-deciding unit (5) has access to all input values, output values and consequence values for evaluation. Device according to one of the preceding claims, characterized in that the unit (4) for weighting consequences and the hand-deciding unit (5) contain "fuzzy" logic for decision-making. Device according to claim 19, characterized in that the unit (4) for weighting consequences produces its output data via hardware or software "fuzzy" "OR" and "AND" decisions. Device according to claims 19 or 20, characterized in that the hand-deciding unit (5) has stored, has access to or produces a candidate list. 10 15 20 25 22. 23. 24. 25. - s 44 24 Device according to claim 21, may indicate that handover decision in the handover decision unit (5) is made via "fuzzy" "OR" and "AND" operators in hearth - or software "IF" and "THEN" statements. Device according to one of the preceding claims, characterized in that there is an exchange of data information between the exchange unit and the hand-deciding unit (5). A base station in a system comprising wireless telecommunications, which base station comprises a device for producing data for handover between base stations based on at least two radio signal parameters in the system, can be provided with means for receiving actual values of at least two parameters, and "fuzzy logic means "for executing fuzzy condition sets with values of the parameters and to weight consequences to at least one well-defined value and to generate a basis for decisions on handover depending on well-defined values. A switch in a telecommunication system comprising wireless communication via base stations, which switch comprises a device for producing data for handover based on at least two radio signal parameters in the system, characterized by means for receiving actual values of at least two parameters, and "fuzzy logic means "for executing fuzzy condition sets with values of the parameters and to weight consequences to at least one well-defined value and to generate a basis for decisions on handover depending on well-defined values. 1. 10 15 26. 27. i _ 151.1 4 s f8b fl4 tr4 25 A telecommunication system comprising base stations for wireless communication, which system comprises a device for producing data for handover based on at least two radio signal parameters in the system, capable of being detected by means for receiving actual values of at least two parameters, and "fuzzy logic means" for executing fuzzy condition sets with values of the parameters and to weight consequences to at least one well-defined value and to generate a basis for handover decisions depending on well-defined values. A mobile station in a system comprising wireless telecommunications, which mobile station comprises a device for producing data for handover between base stations based on at least two radio signal parameters in the system, characterized by means for receiving actual values of at least two parameters, and fuzzy logic means "for executing fuzzy condition sets with values on the parameters and to weight consequences to at least one well-defined value and to generate a basis for decisions on handover depending on well-defined values.