WO1995035005A1

WO1995035005A1 - Method and device at radio network

Info

Publication number: WO1995035005A1
Application number: PCT/SE1995/000609
Authority: WO
Inventors: Paul Stjernholm
Original assignee: Telia Ab
Priority date: 1994-06-13
Filing date: 1995-05-30
Publication date: 1995-12-21
Also published as: SE515751C2; SE9402040L; EP0765585A1; SE9402040D0

Abstract

The present invention relates to a method at radio networks for determination of quality of frequency allocations. A first device is to be allotted information regarding the radio system available frequencies, channels. The first device can be allotted demands on frequency separation between channels within and between the base stations. The first device produces the frequency allocations for the base stations. The fulfilment demands for the produced frequency allocations are calculated. Further a presentation for the frequency allocations is determined where the not fulfilled demands are categorized and weighted according to importance. A decision device produces a difference between the presentation and selects that presentation which best comes up to the demands. The decision device determines whether the selected presentation is acceptable or not. Acceptable solutions are implemented in the base stations at which the definition of quality for the frequency allocations is given by the obtained presentation for the frequency allocations.

Description

Method and device at radio network.

TECHNICAL FIELD

The present invention relates to frequency allocation at radio networks. The radio network comprises a number of base stations to which a limited number of accessible frequencies, channels, are to be allocated. The invention specifies a method to determine the quality of the channel allocations in the cases where stipulated demands on frequency separation are not fulfilled.

STATE OF TECHNOLOGY

Concurrently with the need to increase the capacity in mobile telephone networks, frequency allocation has become an ever increasing optimization problem. In order to cope with the capacity, it has become more common that deviations are made from made demands on frequency separation in the network. In this connection there are difficulties to determine whether different frequency allocations are better or worse than each other.

In the patent document WO 93/15591 is shown a method where a model is created by the radio network. The model is simulated where consideration is taken to the terrain in the form of a digital map. The allocation can be optimized by adjusting parameters and perform further simulations. Presentation of traffic statistics can be made in graphical form, where, for instance, data about speech quality, number of calls etc can be shown. In patent document US 5 179 722 is described a method for deciding interferences in a radio network after a channel allocation. The result of a frequency planning is shown in graphic form.

In the European document 559 949 is described a method for dator supported cell planning of a radio network. The method is based on a digital terrain data base. The covering area of the base stations are superimposed on a digitized map och shown graphically. Interference characteristics for different sets of transmitter parameters are analyzed and the result is used as parameter for the channel allocation.

DESCRIPTION OF THE INVENTION

TECHNICAL PROBLEM

At frequency allocation in radio networks there is a need to obtain a measure of the quality of the frequency allocation. The quality determination is important in connection with frequency allocations where the demand on frequency separation between channels in or between base stations are not fulfilled. Concurrently with the capacity in the radio networks being increased, there arise more and more often problems with the demands for frequency separation being not fulfilled. To, in this connection, establish different frequency allocations' priorities over each other is a very difficult task. Mesure definitions on deviations from the frequency separation have so far not existed. Further there are lacking methods for separating the importance of different demands'"no fulfilment" of frequency separation between the channels within and between the base stations. Consequently, there is a need to find methods and means which in a simple way discern and point out which frequency allocations, in a given amount, is to be preferred to another. Further there is a need to find methods and means which evaluate which solutions that can be applied at all in the network with an acceptable risk of int4erference between current channels. The present invention is intended to solve mentioned problems.

THE SOLUTION

The present invention relates to a method at radio networks for determination of quality of frequency allocation. The radio network is allocated a number of frequencies, channels, which are to be distributed between base stations in the radio network. In order to avoid interference between channels demands on frequency separation between the channels within and between the base stations are determineed. When a frequency allocation does not meet with the demands there will be a violation of these.The mentioned violation is categorized with regard to the scope of the violation. Further there is introduced a weighting of the different violations at which interferences which are more serious for the function of the network is given a higher weight than less serious violations. The distribution of the weighted violations are after that produced. The distribution indicates the the number of weighted violations in the different categories or in total. The obtained distributions for a first respective second frequency allocation are compared. That frequency allocation which has least serious violations in its distrbution is selected. The quality of the frequency allocation is indicated by the distribution at which the number of deviations from the stipulated demands indicates the quality. The categorization is further made in intervals. The division into categories is further made in intervals. The distribution of violations is calculated by a function. The function is a function of the demand och the obtained frequency separation weighted with the weight in question. The function is

bij=(uij*Δfij)*Δvij, Δfij<uij where

where

u signifies the demand Δf signifies the frequency separation vij signifies the weight

The distribution of the weighted violations are presented i diagrams. Presentation in the form of diagranms simplifies the visual control of the achieved results.

The invention further relates to a device at radio network for defining of quality of frequency allocations.A first device is at that to be allotted information regarding in the radio system available frequencies, channels, and the need of channels in the base stations. The demands for frequency separation between the channels within and between the base stations are further to be allotted to the first device. The first device further produces suggestions for frequency allocations for the base stations. In the first device further occurs a calculation of the fulfilments of demands for the produced frequency allocations. For frequency allocations where the demands are not fulfilled, a presentation is put produced. In the presentation the deviations from the stipulated demands are categorized according to importance. Further a weighting function has been introduced to increase the importance of serious violations against made demands. The result is transferred to a decision device which determines a difference between the presentations and selects that presentation which best complies with the demands.The decision device further examines whether the selected presentation in spite of deviations from the demands can be accepted or not. Acceptable solutions are after that implemented in the base station/stations in question. A quality determination of the frequency allocation is at that given by the obtained presentation of the frequency allocation.

ADVANTAGES

The invention consequently makes possible for the quality of a radio network to be easily presented.

Further the invention makes it possible to, in advance, define a minimum acceptable level of the network. The invention further makes it possible to get a mesure of the quality of the network. It is further possible to compare the quality of different frequency allocations at which the best allocation is to be selected. The invention is further possible to use at manual as well as automatic frequency allocation. The algorithm which is used to evaluate the different frequency allocations against each other is simple to change. It is further simple to compare the obtained results. The invention accordingly constitutes a tool which considerably simplifies the frequency allocation in those cases when determineed demands on the frequency separation can not bE completely fulfilled. DESCRIPTIONS OF FIGURES

Figure 1 and 2 show examples of different frequency allocations with a number of violations indicated.

Figure 2 shows the fundamental construction of the invention at which

a: defines frequency need, exclusions and weights, presupplied frequences, available frequences and prohibited frequences.

b: frequency allocation

c: violation calculation

d: presentation

e: decision

PREFERRED EMBODIMENT

In the following is described the idea of the invention with references to the figures and the designations therein.

In a radio network comprising a number of base radio stations a limited number of accessible frequences, channels, are to be distributed in an optimal way between the base stations in the radio system. In order to achieve a network free from interference, demands for frequency separation have made. The demands for frequency separation, exclusions, indicate which channels can be used in one and the same base station or closely located base stations without interfering with each other. In the radio systems which are established or modified there is a strong desire to increase the capacity. An extension of capacity, however, can imply that the demands which originally were put forward can not be completely fulfilled. The different violations which at that occur against the original demands effect the network function to different degrees. Accordingly two channels which are being located in one and the same base station can in certain cases not be accepted at all. On the contrary, the same channels can possibly be allowed in base stations which are neighbours to each other under certain circumstances. Decisive for whether to channels can be used is at that to what extent the mentioned channels interfere with each other and with other channels in its surroundings.

In the following two base stations, i and j, are observed. Further is defined an exclusion demand U. At measurements and calculations has further a frequency separation Δf been determineed. The relation between the exclusion demand and the frequency separation constitues a mesure of the risk of interference between the base stations in question. A violation of the exclusion demand is obtained when Δf< uij. In other cases the determineed demands are fulfilled. In the following only the case when Δfij< uij is regarded where i and j signify base station i respective j.

In a radio network where frequencies are to be allocated between base stations, the need of frequencies, exclusions and weigths, presupplied frequencies and available frequencies to a first unit is defined according to Figure 3. The unit A sends on information regarding indata, for instance exclusions which make violation calculations, to a decision device, E, which decides regarding found results. From A the information regarding frequency need etc is further transferred to unit B. In the unit B calculations and frequency allocations to the different base stations is performed. The frequency allocation is made in way previously established and known. The unit B can in this connection function according to different alternatives. One alternative is that a number of different alternatives of frequency allocations are calculated. Another alternative is that only one frequency allocation is worked out (calculated) and forwarded to the violation calculation device, C. According to what has been previously described, it is supposed that the frequency allocation implies violation of the exclusions. In the violation calculation device there is a built in function which takes into consideration the exclusion demand, u, and the obtained frequency separation Δf's relation to each other. The different violations are further classified in relation to the scope of violation. With scope of violation is in this case referred to the degree of risk of interference present between the base stations in question. The produced calculation result is transferred to a presentation module, D. In the presentation module the violations are arranged according to violation scope and number of violations within each violation scope. The accordingly obtained presentation is presentable in different ways with regard to how the presentation is to be used. For visual comparison the information is preferably arranged in the form of diagrams, according to Figure 1 and 2. Other presentations can also be used, depending on how the information is to be used. The presentation is after that transferred to a decision device, E. The decision device compares the obtained results och decides which result is to be preferred. If, for instance, two presentations according to Figure 1 and 2 have been obtained, the presentation according to Figure 1 is to be preferred. From the diagrams can be seen that more serious violations are present in allocation according to Figure 2. The decision device further compares the obtained result with the demands which have been oput forward regarding violations that can be accepted. If the result can not be accepted, the information is brought back to the unit A. New calculations and new frequency allocations are after that calculated and being subject to the same procedures as described above. If no frequency allocations that can fulfil the demands is found,either the conditions must be changed, or a decision be taken that the wished frequency allocations are not posssible to perform. If a result which is acceptable is obtained, this is transferreed to the radio network where the frequency plan is determineed and introduced.

The diagram which can be obtained from the presentation device further indicate a marking of the quality of the frequency allocation.In judging what frequency allocation is to be preferred, the decision device can for instance calculate a difference between the distributions of the different frequency distributions. The obtained difference at that clearly indicates which frequency allocation is to be preferred.

Alternative presentation:

List of violations comprising - Category of violation

- The scope of the violation

- Demands for exclusion

- Weight

- Base station i and j involved - Frequencies at respective base station causing the violation. The list can be sorted on optional parameter (according to what has been described) and formatted or presented in a suitable way.

A number of frequency allocations are in this way possible to be produced for the radio system. The frequency allocations can on one hand completely fulfil the determineed demands and on the other relate to a number of solutions which do not fulfil the requirements according to preceding description. A comparison of the results with regard to frequency allocations is at that obtainable, at which the consequences of changed frequency allocations in the different base stations and closely located radio network is obtainable. The obtained presentations present in this case the decision device in form of a difference. The difference after that makes use of the decision device to determine which solution is optimal and best.In the cases where the solutions do not fulfil the determineed demands, the optimal solution is used, at which a valuation of the quality of the network is achieved. The obtained quality of the network is, with the conditions which have been drawn up, after that possible to evaluate with regard to the desired quality one is aiming at. It is further possible to, in this way, obtain a limit for what the netweork can achieve under determineed conditions.After that one has to decide whether a solution can be accepted with regard to the determineed conditions, or that the conditions shall be changed, for instance a change of the number of channels in the network, number of channels that may be used in base stations etc.

The invention is not limited to the above shown embodiment but may be subject to modifications within the frame of the following patent demands and idea of invention.

Claims

PATENT CLAIMS

1. Method, at radio network, for defining of quality of frequency allocation, which radio network is allocated a number of frequencies, channels, which are to be allocated between base stations in the radio network and demands for frequency separation between the channels within and between the base stations are determineed, and violation occurs when the frequency allocation do not fulfil the demands, c h a r a c t e r i z e d in that the violations are registered with regard to grade of violation, that the violations are allotted weights, the values of which increase with the grade of violation, that a distribution over the weighted violations is produced, that the distributions of a first and a second frequency allocations is compared, at which the distribution with the least number of serious violations is selected, and that the quality of the frequency allocation is indicated by the allocation.

2. Method according to patent claim 1, c h a r a c t e r i z e d in that the categorization of the violations is made in intervals.

3. Method according to patent claim 1, c h a r a c t e r i z e d in that the violation distribution is calcultated from an algorithm which is depending on the deamnd and the obtained frequency separation weighted with the current weight.

4. Method according to any of the previous patent claims, c h a r a c t e r i z e d in that the used algorithm is

bij=(uij*Δfij)* Δfij<uij where u signifies the demand,

Δf signifies the frequency separation, v signifies the weight, and i an j signifies the base stations i and j.

5. Method according to any of the previous patent claims, c h a r a c t e r i z e d in that the distribution of the weighted violations are presented in the form of diagrams.

6. Means at radio network for defining of quality of frequency allocations, at which a first device can be allocated information regarding available frequencies, channels, in the radio system, and the need for channels in the present base stations in the radio network, and the first device can be given demands for frequency separation between the channels in and between the base stations, and that the first device produces the frequency allocations for the base stations, c h a r a c t e r i z e d in that the first device is arranged to calculate the fulfilment of demands for the produced frequency allocations, and determine a presentation for the frequency allocations, where the not fulfilled demands are categorized and weighted according to importance, that de decision device is arranged to determine whether the selected presentation is acceptable or not, that acceptable solutions can be implemented in the base stations, at which the defining of quality at the frequency allocation is given by the obtained presentation of the frequency allocation.

7. Device according to patent claim 6, c h a r a c t e r i z e d in that the first device categorizes the violations in intervals.

8. Device according to patent claim 6 or 7, c h a r a c t e r i z e d in that a decision device is arranged to produce a difference between the presentations and select the presentation which best fulfils the demands.

9. Device according to patent claim 6 up to and including 7, c h a r a c t e r i z e d in that the decision device is arranged to present the violations in the form of diagrams.

10. Device according to patent claim 8, c h a r a c t e r i z e d in that the decision device is arranged to determine a difference between the obtained presentation and stipulated demands, that the decision device uses the difference for deciding whether the obtained presentation for the frequence allocation is acceptable or not, and which out of two presentations is to be preferred.