CN1220560A

CN1220560A - Method of providing matrix indicating interference relationships between cells of cellular communication system

Info

Publication number: CN1220560A
Application number: CN 98125344
Authority: CN
Inventors: 马克·加拉格尔; 特雷弗·汉纳
Original assignee: Motorola Ltd
Current assignee: Google Technology Holdings LLC
Priority date: 1997-12-19
Filing date: 1998-12-18
Publication date: 1999-06-23
Anticipated expiration: 2018-12-18
Also published as: GB9726946D0; GB2332600B; CN1121801C; GB2332600A; GB2332600A9

Abstract

A method of providing a matrix indicating interference relationships between subzones of a cellular communication system comprises the steps: collecting step for the first service subzone; determine step for determining a plurality of subzones identity other than the first service subzone at least partly from the collecting data; compare step for each subzone among the other plurality of subzones; determine step for determining the matrix based on the plurality of comparison values and the identity data.

Description

The method of the matrix of the interference relationships of indicating the cellular communication system minizone is provided

The present invention relates to the method for the matrix of the interference relationships between a kind of sub-district that is provided for indicating cellular communication system.

In cellular communication system, provide professional zone can be divided into the zonule that several are referred to as the sub-district.Each sub-district all provides service by a base station, and this base station has one pair of corresponding antenna or plurality of antennas, is used for sending and receiving from a subscriber board to a subscriber board (normally travelling carriage).

The radio frequency of a special use or a plurality of radio frequency are assigned to each sub-district.Owing to, thereby cause some restriction only with limited frequency spectrum and may be with several fractions in this limited frequency spectrum.A kind of restriction is to use a dedicated frequency in the different districts of a system again.Cause that another kind of restriction is to use adjacent frequency values, be different from other possible actual conditions, these frequency values are closer proximity to each other.This frequency limitation can cause that cochannel disturbs and adjacent-channel interference.Cochannel disturbs and to be meant, uses caused interference between two different districts of same frequency.Adjacent-channel interference is meant, when two different districts are using the side frequency part of used frequency spectrum in sub-district separately, and caused interference between two different districts.When the Frequency Distribution of a system was planned, a kind of consideration was how to reduce the possible cochannel interference and the level of adjacent-channel interference.

A kind of method of prior art comprises carries out so-called propagation forecast (propagationprediction).For a certain given sub-district, total zone also can be divided into littler zone.For each described littler zone, can estimate by a travelling carriage to receive relevant signal level from the base station of comparing different sub-districts with the base station of current area.This process is all carried out in a lot of sub-districts.According to resulting these estimations, in this system, carry out Frequency Distribution, or change existing Frequency Distribution.This process comprises provides some so-called C/I matrixes (matrix).This first matrix comprises some by C/I value that above-mentioned propagation forecast calculated.Value C is meant carrier signal strength, and in other words, this estimated signal will be received from the base station of the sub-district considered.Value I is meant interference signal intensity, and in other words, this estimated signal will be received from the base station of other sub-districts of just considering propagation forecast separately.

When the C/I matrix is provided, increase propagation forecast by driving test (drive testing).Drive test and relate to operator's driving one by one around the area of coverage of honeycomb media (vehicle).

Select to drive route, this route is a kind of route that is used for representing in the communication service of being studied that the sub-district comprised.This driving method of testing relates to the selected route of driving, and these routes still are that the station, land all can be used for carrying out a plurality of calls to the travelling carriage direction at travelling carriage to station, land direction.The information of each calling all can be recorded and subsequent treatment.

A this basic propagation prediction method and a shortcoming of the driving test effect that adds are that wherein used all values only are some non-representational sample value or mean values that obtain from specific position.These positions are artificial selections, therefore do not represent actual comprehensive situation of using in this sub-district.Another shortcoming is, unless these processes often repeat, otherwise can't consider the variation of this system.It is that these values in this matrix have constituted the absolute value of result of calculation C/I that another shortcoming of the existing method of C/I matrix is provided.So this absolute value frequency reuse candidate that can not distinguish or not so good.Specifically, these values do not contain the reflection of the level of user's use, and are certain although in fact this level plays a part in whether any frequency planning can make the problem of carrying out Frequency Distribution in a system smoothly.

Fig. 1 has illustrated the spendable typical cellular communication system according to the present invention.

Fig. 2 shows a kind of expression that is close to table.

Fig. 3 is the process flow diagram of one embodiment of the present invention.

Fig. 4 has illustrated the histogram that forms in the method for one embodiment of the present invention.

This preferred implementation relates to a kind of cellular communication system of gsm system that is, be to be understood that, the present invention is not limited to this system, equally also can be used in the cellular communication system of TDMA/CDMA system that other time division multiple accesses (TDMA) system, code division multiple access (CDMA) system or other contain combination.

Fig. 1 has illustrated a typical cellular communication system 10, and this system has an area of coverage that is made of several sub-districts 12-22.Usually describe the zone of this sub-district with a kind of graphical representation of hexagonal cell form, but in fact, the shape of each sub-district can be different with size.In each sub-district, generally there is a base station 24-34 at heart place therein, and this base station is by the well-known process control of the those of skill in the

art communication service

36,38,40 in the sub-district separately.Each base station (BS) 24-34 can send signal 40 from travelling carriage (MS) 42-46 received signal 38 with to travelling carriage (MS) 42-46, these travelling carriages move in communication system 10 everywhere-in this preferred implementation,

base station

24,26,28 and 30 is all passed through a certain base station controller (BSC) 47 and is connected to mobile services switching centre (MSC) 50, and

base station

32 and 34 all is connected to MSC 50 by another BSC 48.Operation also links to each other with MSC 50 with maintenance centre (OMC) 49.According to the size of this communication system, OMC 49 can be responsible for whole system, perhaps also can provide several OMC according to the zone.MSC 50 links to each other with public switched telephone network (PSTN) 51.

MS 44 utilizes following process to be assigned to BS 28 as its Serving cell.When MS 44 starts, it is searched for by technical well-known process, attempts to receive from signal of base station.In this search phase, this MS utilizes all frequencies of this system to search for.MS44 receives the signal from the BS in BS 28 and this example 24,26,30,32 and 34.This MS judges the signal that received, and which is the strongest, communicates by letter with corresponding BS (being BS 28 under the present case) then, and this BS will link to each other with this system.BS 28 and MS 44 engage in the dialogue, thereby set up a communication path, also inquire about this MS 44 to confirm the details that comprises its identity from it in this stage.This BS sends to BSC 47 with the identity of MS 44 and other such as details such as encrypted messages, and sends to MSC 50.This MSC 50 these details of storage, with this travelling carriage of box lunch when paged, it can be called out for this and select from PSTN 51 via MSC 50 to BSC 47 again to the route of BS 28, so just can carry out communicating by letter between MS 44 and this system.In this stage of this assigning process, by BS 28 control MS 44.Control information sends to MS 44 from BS28.This control information comprises that especially is used to indicate the control messages that hereafter should search for which frequency subsets.These frequencies in this subclass are corresponding to the used frequency of BS in the current contiguous table of BS 28.This current contiguous table will be done more detailed explanation in the back.In addition, in the present embodiment, this control information comprises that MS 44 also should search for an instruction of some used in this system other frequencies.In this communication system, some frequency (frequency channels) can be exclusively used in and carry control messages, and some other frequency (frequency channels) can be exclusively used in and carries communication service.A kind of selection of searching for which other frequency is, this travelling carriage search of selection instruction all used frequencies of control messages in this system, and this is relative with the used frequency of communication service.The result of this assigning process is that MS 44 is assigned to so is called as the BS 28 of its Serving cell.After this, MS 44 will respond a paging or communicate by letter with BS 28 on schedule, thereby confirm that to BS28 it is still in operate as normal.

MS 44 will be assigned to the BS 28 as its Serving cell together, be shut down up to it, perhaps be handed off to another contiguous sub-district.Be handed over to another sub-district and relate to current contiguous table, will describe this table in detail below.

In the system of present embodiment, for each base station, must distribute some other special BS, these BS will be as candidate's handover BS.The identity table of handover BS that is distributed and the handover sub-district therefore distributed is called as contiguous table.In the system according to present embodiment, this vicinity table is stored in this place, base station.Yet in other system, it can also be stored in BSC place, OMC place or even farther place.These candidate's handovers BS in this example of BS 28, can from those very approaching geographically BS of the cell area of BS 28 selected, and under the situation that lacks other factors, will distribute according to all geographical those sub-districts of going up around it simply.Yet, note, some other factor may be influential such as geographical and building characteristic, and these characteristics are obstacle, user density, user's move mode and size or the uneven sub-district of shape etc. for example, and preferably should distribute the sub-district by less system this moment.Therefore the allocative decision of the candidate's handover relation between the BS (and corresponding sub-district) in this cellular communication system that is produced is called as the topological structure of this system.In the present embodiment, each in five sub-districts be illustrated in sub-district 16 among Fig. 1 around, promptly

sub-district

12,14,18,20 and 22 is all in the current contiguous table of BS 28.Moreover, in the present embodiment, there is not more sub-district in the current contiguous table.Yet, should be pointed out that usually that in a given cellular communication system sub-district number that generally can be included in the current contiguous table of a certain sub-district has the maximum restriction.

In the gsm system of present embodiment, each BS is with form broadcasting continuously on its control frequency of a certain Broadcast Control Channel (BCCH).Under this GSM situation, this control channel frequency occurs with absolute radio-frequency channel number (ARFCN) form.In this BCCH, also the BS identifier that is called as BS identification code (BSIC) is encoded.Therefore, all BCCH-ARFCN and BSIC constitute the identity data relevant with the identity of this base station, in other words, and the identity data relevant with the identity of this sub-district.

As noted earlier, MS 44 search is by from the determined frequency of the control messages of BS 28, the frequency that is comprised in the search list of promptly so-called BS 28.Because MS 44 receives some signals of this control frequency, so it can determine a signal strength signal intensity value (metric), this value is used to measure the signal strength signal intensity of the BCCH that receives about each.It is also decoded to BSIC.Therefore, be assigned to that MS 44 as the BS 28 of its Serving cell obtains identity datas and the signal quantity data of forming with three partial information forms of each BS (being other sub-districts) that searches for smoothly of controlling oneself, i.e. BSIC, signal strength signal intensity value and control channel frequency separately.Under this GSM situation, this control channel frequency occurs with the ARFCN exponential form.This three partial information combines with the form of data module.By the i.e. determined data module separately in a plurality of sub-districts except that this Serving cell of a plurality of different BS, transferred back to BS 28.In this GSM execution mode, MS 44 arranges these data modules according to this signal strength signal intensity value, and only with six the data module of high rank send to BS 28.They are sent to BS 28 with the form of measuring form (measurement report).In the specification 4.08 of ETSI GSM, intactly defined this measurement form.

Signal quantity in this measurement form comprises two kinds of values.A kind of value is relevant with transmission continuous and that use so-called full speed channel.Another kind of value then with interruption and become with input signal and silent period and use the transmission of so-called subrate channel relevant.This interruption signaling is commonly called discontinuous transmission (DTX).Indicate this of measuring in the form but which kind of value effectively in the indication measurement form.These data modules are constantly sent.

In BS 28, this BCCH-ARFCN and BSIC combination are switched to a BS identity, are BS 32 here.This conversion have only when this BCCH-ARFCN and BSIC combination and BS identity be included in this vicinity show in the time could occur.Fig. 2 shows a kind of expression that is close to table, can see that therefrom how corresponding with a certain special BS identity a BCCH-ARFCN and BSIC combination is.

The method of this preferred implementation is shown in the process flow diagram among Fig. 3 300.With reference to Fig. 2, functional block 305 expressions are used for the collection step of first Serving cell, this step is in order to collect the relevant identity data of identity with a plurality of sub-districts except that described first Serving cell, and with from the relevant signal strength signal intensity magnitude data of the value of signal strength signal intensity separately of described first Serving cell and described a plurality of other sub-districts, thereby collected data are provided.In the present embodiment, obtain this identity data and signal quantity data by a plurality of travelling carriages by searching for other sub-districts and Serving cell at first, as mentioned before.These data occur to be included in the data module form of measuring in the form.Therefore, for example, about by MS 44 resulting data, this measurement form sends to BS28 from MS 44, and wherein these data further are sent to BSC 47 from BS 28, at this, collects this data, thereby collected data are provided.In the present embodiment, also be sent to BS 28 from the corresponding data of a plurality of other travelling carriages of distributing to BS 28, and further be sent to BSC 47 from BS 28, but, should be pointed out that however, utilize and only just can use the present invention effectively from the data of a travelling carriage.Should be noted that according to other execution modes of the present invention, can oneself collect these data, perhaps also can collect this data at other network node places at BS 28 places.

When realizing present embodiment, use a kind of statistical sampling process, promptly the measurement form of this GSM will pass through a kind of statistical sampling process.In other words, needn't all handle all measurement forms.In the present embodiment, measure form to thousands of and handle, these are measured form resulting a large amount of signal matrix in the time in the past are provided, thereby carry out the calculating of being carried out accurately.Its advantage is that for example the communication of the vice-minister between MS 44 and the BS 28 can not make the result produce skew, because replace the resulting result of mass communication who uses between MS 44 and the BS 28.Therefore, can provide the whole area of coverage of crossing over BS 28 is information on the whole sub-district.Because therefore the mobility of the travelling carriage in the gsm system of present embodiment utilizes the data that come from mass communication, this measurement report data can obtain from the user who moves in whole sub-district.About any other mobile communication system, also can obtain same advantage.These are measured form sample, thereby, a form is analyzed, skip then and promptly ignore a number, again the next one is measured form and analyze, and then skip a number according to these a series of measurement forms of collecting, and the like.A good method that realizes this process is, select each n to measure form, and n is an integer here.This sampling process produces a subclass in the whole statistics set.For a given calculator memory capacity and disposal ability, this process allows to handle more information.Moreover, because a lot of form of measuring is similarly, therefore adopting a sampling process, just the more distortion of the information module in this measurement form can be listed with given computer.The methods of sampling on other statistics also can be used for present embodiment, and can by the skilled person according to general data pattern (pattern ofdata) and desired or effectively the processing capacity select.For example, can collect these data on the basis of sampling, and then the data of all collections are handled, this can comprise that only some travelling carriage from certain sub-district is collected.

Determining step, this step are determined the identity of the described a plurality of sub-districts except that described first Serving cell, shown in the functional block among Fig. 3 310 at least in part from described collected data.In the present embodiment, the manner of execution of this step is as follows.According to collected data, each is measured each ARFCN-BCCH that is reported in form, and combination separates with BSIC, and the list that contrasts this class combination of being preserved in the current contiguous table compares.This process can be by being connected to this BSC with a computer and utilizing technical well-known customary computer approach to realize.The another kind of device of realizing these processes is to utilize a computer or be integrated in BSC or the part of the computer of BS itself.It is separated to appear at those identity in the current contiguous table and corresponding ARFCN-BCCH and BSIC combination.This also available customary computer approach is realized.By supposing that this ARFCN-BCCH and BSIC combination is unique for a specific BS, the determining of the just the easiest identity of finishing this sub-district.If in some cases, prove this supposition defectiveness, then can use side information, for example the X of each BS in this system and Building Y mark.Adopt technical well-known triangulation calculation method, can calculate the distance between this serving BS broadcasts and the every other BS, thereby a database is provided, this database comprise with separately from ARFCN-BCCH and the BSIC combination of corresponding each BS of the distance of this serving BS broadcasts.According to ARFCN-BCCH and BSIC combination and by storing this database with the rising order of this serving BS broadcasts spacing.Search this database, thereby find those to have candidate ARFCN-BCCH and BSIC combination and from the suitable sub-district of the distance of this serving BS broadcasts.This distance is suitable for the scope and the covering of this Serving cell and the adjacent cell around it.For example, in the sub-district, city, should be thought of as several kilometers far away, and in rural areas, its adjacent cell can be farther.In addition also can according to the directed of antenna and in the area of coverage of Serving cell the information of precognition signal strength signal intensity, in order to differentiating in a system, when two adjacent cells have and similar distance of Serving cell and identical ARFCN-BCCH and BSIC combination.

Before any calculating begins, respectively these are measured form and detect, to determine this signal metric any part effectively.This is by detecting the DTX sign and suitably utilizing full rate or subrate value in this service cell information that this measurement form comprised to finish.About with the other system of the system similarity of present embodiment, the skilled person obviously knows, according to data format special in this system, with which type of process of needs to determine this effective value from useful data.

The comparison step that is used for each sub-district of described a plurality of other sub-districts, this step will be separately the signal strength signal intensity value compare with corresponding signal intensity value from described Serving cell, thereby for each sub-district in described a plurality of other sub-districts provides separately one group of comparison value, shown in the functional block among Fig. 3 315.In the present embodiment, the manner of execution of this step is as follows.For a given ARFCN-BCCH and BSIC combination (being cell identity), measure form according to each of being sampled, determine appropriate signals intensity level (be designated as Ni, wherein i represents i measurement form of being sampled) from this measurement report messages module.Also according to same i this Serving cell of measuring in the form, determine the corresponding value of full rate or subrate, i.e. signal strength values Si in addition.In the present embodiment, according to the step of front, be to calculate the value that Si deducts Ni for each measurement form of being sampled with the method for a comparison step that compares from the signal quantity of Serving cell from the signal quantity of other sub-districts and.This can utilize some known computer approach to realize automatically.According to many measurement forms of being sampled, work out out each Si-Ni result's count value list.Each Si-Ni table that combination is produced for each ARFCN-BCCH and BSIC carries out statistical disposition, thereby the various situations that occur are counted, and produces a histogram thus.This histogram 400 as shown in Figure 4.So this histogram shows for certain specific ARFCN-BCCH and BSIC combination (in other words, certain other sub-district) resulting each S-N value.

In the present embodiment, used the histogram of 400 types as shown in Figure 4 in the determining step, this step is according to described many group comparison values and described identity datas, is identified for indicating the matrix of the interference relationships between each sub-district of cellular communication system.This step is shown in the functional block 320 of Fig. 3.This respectively organizes comparison value is exactly the S-N value.The occurrence number of each S-N value (level ofoccurence) is with being with hatched to represent in the histogram.In the present embodiment, these occurrence numbers each all with respect to carrying out normalization at sum for all S-N values of being comprised in the collected total data of this Serving cell.Amount to these normalized values then in some preset range of S-N value in histogram, thereby provide separately interference coefficient for these other specific sub-districts.These preset ranges are specified according to specific system requirements.As for present embodiment, used frequency reuse and disturb criterion relevant in these preset ranges and this communication system.These preset ranges depend on that also the interference matrix that is determined is used for cochannel interference relationships or adjacent-channel interference relation.Be used for the present embodiment of gsm system, the scope of S-N value can from-63 to+63.In the present embodiment, suppose that adjacent channel frequency is used again and the interference criterion is+9dB, and allow the error margin of 3dB, this just draws+the 6dB value, then amount between-63 and-6 through normalized occurrence number, thereby the interference coefficient that calculates adjacent-channel interference (is noted, positive S-N value representation server signal strength signal intensity is greater than the signal strength signal intensity of other sub-districts of being discussed, otherwise, negative value represents that the signal strength signal intensity of other sub-districts is greater than server's signal strength signal intensity, therefore, the used positive dB value of frequency reuse criterion is corresponding with the negative S-N value in the histogram).The present calculating of considering the interference coefficient that relevant cochannel disturbs is supposed the cochannel frequency reuse and disturbs criterion to be-9dB that when allowing the error margin of 3dB, this just draws-the 12dB value.Then amount to-63 with+between 12 through normalized occurrence number, thereby calculate the interference coefficient of cochannel interference.

In the present embodiment, may comprise that also one has precedence over the step of calculating interference coefficient, promptly carries out statistical weight to the described comparison value that the preset range with described comparison value becomes.An example of these scopes is as the scope in the histogram of Fig. 4 (ⅰ), (ⅱ) with (ⅲ), wherein, scope (ⅰ) is corresponding to the S-N value between-63 and-6, and scope (ⅱ) is corresponding to the S-N value between-6 and 0, and scope (ⅲ) corresponding to 0 and+S-N value between 12.For example, about calculating the interference coefficient that cochannel disturbs, this statistical weight can comprise, those occurrence numbers in the scope (ⅰ) be multiply by the factor 2, those occurrence numbers in the scope (ⅱ) be multiply by the factor 1, and those occurrence numbers in the scope (ⅲ) be multiply by the factor 0.5.Should be appreciated that the skilled person will be according to selected any of these scope of the accurate characteristic of the system that is considered and the appropriate specification requirement of multiplication factor separately thereof.

In the present embodiment, can repeat all above-mentioned steps for other Serving cell, thereby the interference coefficient in the formed matrix further is provided.

An advantage of the formed matrix of present embodiment is, value wherein comprises above-mentioned interference coefficient, and this interference coefficient has been represented the direct relevant relative value of applicability with corresponding Serving cell/other cell combination (for the cochannel frequency state that is assigned with in any frequency assignment procedure that is used for this system or adjacent channel frequency state and this matrix of employing) in essence.In addition,, therefore comprise the level that the user uses, and therefore help carrying out smoothly frequency planning owing to, calculate this interference coefficient, and interference coefficient is carried out normalization with respect to these data according to collected data in the actual use from this system.The another kind of favourable result of the interference coefficient of this form is, because they are relative values, therefore can obtain another advantage, in this step by carrying out further normalization step, the interference coefficient of the maximum in the matrix is made as 1, and other coefficient normalization are in this.

Another aspect of the present invention is to use this matrix in the frequency planning process.Formed this matrix of the present invention is particularly useful for (AFP) in the Automatic Frequency Planning, and its process is well-known technically.

Should be appreciated that the present invention is not limited to above-mentioned specific examples.In addition, will also be understood that, the present invention not merely comprise with published or other data modes of being seen the situation of this matrix is provided, or rather, it comprises that also other hard copy forms that easily read with electronic installation or other devices (as magnetic holder or disk) provide the situation of this matrix, and for example situation when providing in calculator memory or other electronic memories or storing this matrix also is provided when only providing this matrix with electronic form.Equally, the present invention also comprises such situation, promptly manual analysis can't directly be carried out when matrix like this, the situation when but can be used for next stage of the frequency processing of any kind or the planing method Automatic Frequency Planning of contained information in this matrix (as comprise).

Moreover, should be further appreciated that and implementing the while of the present invention, available several different methods will in above-mentioned preferred implementation, be mentioned each make up aspect optional.

Claims

1. the method for the value of the interference relationships between the sub-district that is provided for indicating cellular communication system,

This method may further comprise the steps:

-be used for the collection step of first Serving cell, this step is in order to collect the relevant identity data of identity with a plurality of sub-districts except that described first Serving cell, and with from the relevant signal strength signal intensity magnitude data of the value of signal strength signal intensity separately of described first Serving cell and described a plurality of other sub-districts, thereby collected data are provided;

-determining step, this step are determined the identity of the described a plurality of sub-districts except that described first Serving cell at least in part from described collected data;

-be used for the comparison step of each sub-district of described a plurality of other sub-districts, this step will be separately the signal strength signal intensity value compare with corresponding signal intensity value from described Serving cell, thereby provide separately one group of comparison value for each sub-district in described a plurality of other sub-districts; With

-determining step, this step is determined described matrix according to described many group comparison values and described identity data.

2. the method for claim 1, wherein said step in the time at the past resulting a plurality of described signal quantity carry out.

3. the method for claim 1, wherein one or more described steps are carried out according to the statistical sampling process.

4. method as claimed in claim 3, wherein said system are gsm systems, and described identity data and described signal strength signal intensity magnitude data occur to measure report form, and described statistical sampling process comprises a statistical sampling selecting described measurement form.

5. the method for claim 1, wherein said status data and described signal quantity data are obtained by searching for described other sub-districts and/or described Serving cell by one or more travelling carriages.

6. the method for claim 1 is wherein for other Serving cell repeating said steps.

7. the method for claim 1, wherein said determining step may further comprise the steps:

-according to described collected data, described each that respectively organize in the comparison value is all carried out normalization; With

-be that interference coefficient is separately calculated in each described other sub-district thus.

8. method as claimed in claim 7, wherein said determining step is further comprising the steps of:

-before the step of the described interference coefficient separately of described calculating, the described comparison value that the preset range with described comparison value is become carries out statistical weight.

9. used frequency reuse and/or disturb criterion relevant in the method as claimed in claim 8, wherein said preset range and described system.

10. method as claimed in claim 9, wherein said frequency reuse and/or interference criterion depend on that described interference matrix is to concern at the cochannel interference relationships or at adjacent-channel interference.

11. be provided for indicating the method for matrix of the interference relationships between the sub-district of cellular communication system in fact as indicated above with reference to accompanying drawing.

12. the method for cellular communication system medium frequency planning comprises the matrix that method provided of use by any aforesaid right requirement.