Method and device for the optimisation of cellular wireless message networks

Translation of description of equivalent WO 2004043096 A2

Patent application

Method and device for optimizing cellular wireless

newsnets

description

- The invention -

The invention relates to a method for optimizing the throughput of messages to cellular wireless communication networks in accordance with the preamble of claim 1 and an apparatus for implementing the method according to the preamble of the independent claim 14.

- State of the art -

With the introduction of cellular wireless communication networks was always the

Finding problem in building, future expansion and operation of systems configurations that enable the best possible use of available resources to hardware and frequency bandwidth. The aim is above all to maximize the throughput of messages with acceptable power quality and sufficient network availability or network coverage. Here, the concrete

Target size vary. Thus, for example, the blocking rate is minimized, as exemplarily set forth in U.S. Patent 5,826,218. WO 98/53621 in turn is based on measured pilot reception power values. In order to achieve the objectives of network optimization, different parameters of the network configuration are usually adapted locally limited. This is for example the adaptation of

Anteimendiagramms or the pilot power as described in US Patent No. 5,276,907 or the receiver sensitivity as described in WO 01/37446 Al.

BESTATIGUNGSKOPIE In mobile networks, which usually transmit only information of fixed transmitting stations to possibly mobile subscribers, similar as in the conventional broadcasting, - methods are used, mainly based on the radio propagation characteristics in the network configuration on the action to be achieved network coverage

optimize environment. Here are essentially radio propagation simulations and or measurements of the average received level, and the quality of service at certain locations in the network, used the basic approach for such procedures is in Norbert Geng, Werner Wiesbeck, "Planning Methods for Mobile Communications", Springer-Verlag Berlin, 1998 ISBN 3-540-64778-3 described.

In communication networks, such as the GSM standard, using many frequency bands, the frequency bands are assigned to the individual radio cells of the network. In this case, a suitable distribution of the frequency bands to the radio cells to minimize interference and thereby maximize throughput plays a decisive role.

Such methods for frequency planning of the network are summarized frequently under the term "automatic frequency planning" (AFP).

With the increasing importance of various mobile data services and the trend towards mobile networks of the third generation, for example by the UMTS

Standard that is developed as part of the international "3rd Generation Partnership Project" (3GPP), a needs-based network planning in terms of the expected service-specific Teilnehmerverkerursaufkommens is becoming increasingly important. The various services offered they vary greatly in terms of their Bursthaftigkeit who leiturigs- or packet-switched transmission mode , the data rate, the average transmit power and the symmetry / asymmetry between downlink and uplink on. in addition, in some cases very different physical transmission characteristics of each service need to be considered, since for them different transport channels are used as a rule. These specific requirements for mobile networks of third generation are not met by previously known and common methods and devices for the purpose of radio network optimization. - Object of the invention -

From the perspective of network operators, it seems important to provide all the services offered with approximately equivalent subjective quality, and coverage. It therefore seems necessary to employ a network optimization process, the existing services - the communications network throughout the coverage area with. sufficient quality provides.

The object of the invention is to provide fast, cost effective and efficient the existing

optimize network configuration of a communication network, taking into account the heterogeneous needs of different services for transmitting messages to the effect that then equal or higher quality, but usually improved network configuration with respect to throughput and network quality is available, while maintaining the existing network coverage. Any change of

Cell sites separates it from the optimization measure.

- Solution of the problem -

This object is achieved by the method initially mentioned having the features of the characterizing part of claim 1. Furthermore, the object is achieved with a device of the initially mentioned kind with the characterizing features of Eden claim 14.

The object is According to the invention in particular achieved in that it is determined by single or multiple, thereby quite iterative change certain settings of the network configuration, in particular the antenna direction or the transmit power of a reference signal, for example, a pilot channel in selected by the process of cells, an improved network configuration, for the funk of cell surface-related

Subscriber traffic is balanced as far as possible in the considered network area. In an ideal balanced traffic distribution between the cells can transport at the predetermined cell locations are optimally dissipated. The process is supported by a graphic representation of the cell surfaces with colors which correspond to the traffic of the respective radio cell, dyed. This allows problem areas with high traffic easily identified and the network configuration to be adapted to these places specifically according to the invention. Another possibility of graphic support of identification of problem regions in terms of other quantities in a mobile network is in. WO 00/28756 proposed.

The inventive method may in principle for any cellular wireless

Wireless networks are used. It is particularly suitable for third-generation networks, the example. Operate on the UMTS standard, and offer a number of different services for communication to • mobile subscribers. It is an advantage of the method is that any number of services provided in the communication network can be considered in the optimization of the network configuration with different requirements.

Another advantage of the method is the high speed compared with other methods, can be achieved with the results. The reason for this is that the process purely on measurement data or planning data of the radio network or a

Combination of both is based, which are usually available already, since they are needed in the planning process. It is not a simulation of the radio network behavior within the iterative optimization process is required, as in DE AI is the case, for example, 196 19 205th The process can be automated, which is a computational conversion allows also easy. The optional Verification by the novel process adapted Netzkpnfigurationen is independent of the actual optimization process, whereby the validation method is arbitrary and interchangeable. In addition, the validation by gaining this independence much more meaningful and the other hand is possible without extensive field measurements. The accuracy of the method can be arbitrarily increased by additional data from the possibly simulative validation of the matched Network configuration and other data from the real radio network are included in the assessment of the achieved network quality.

Advantageous embodiments and variants of the method and of the device are the subject of subclaims.

- Explanation -

The invention relates to a method for optimizing the throughput of messages in cellular wireless communication networks as well as a device for implementing the method. This is in particular to cellular wireless communication networks with mobile subscribers who offer a service or a mixture of several services for communication to one or more persons simultaneously, as for example. In mobile networks based on the UMTS standard the case. A

Example configuration of such a communication network with four base stations Bl 10, B120, B130 and B140 is shown in Figure 1.

It is a critical feature of the invention that no extensive simulations, investigations or measurements are required for implementing the method.

Rather, the method is based on generally available data, which are needed in the network planning and optimization process anyway. This is a fast and oriented towards the requirements of network planning carrying out the process guarantees. The general flow of the process is shown in the block diagram of figure 2.

According to step 210 to Figure 2 assumes that present as input to the process location-based data for the communications network or for the to be optimized network section with respect to the subscriber traffic and the radio-oriented network coverage. It is necessary that this information be available in sufficient areal resolution in order for the coverage area of ​​any radio cell of the communication network each have a greater number of values ​​of said Sizes are available. A suitable, but not binding arrangement of these data is in the form of a rectangular matrix consisting of many relatively small rectangular patches, which is assigned a value of the above dimensions.

When subscriber traffic is the amount of traffic each offered in messages network service, which was determined at different locations. The subscriber traffic data extraction can be performed of both by means of measurements, computational and analytical methods or simulations, and by any combination thereof.

The required as input mesh cover is formed by the cell-related received power of a constant transmission power by each radio cell broadcast reference signal that has been established at different locations. The reference signal may, for example, be a pilot channel, as used for radio cell for identification of the subscriber terminals in many mobile networks, among others. Exist in an

News Network no such reference signal may also be a virtual reference signal, which is radiated from each radio cell of the communication network with the same transmission power will be accepted. Just as the subscriber traffic, the data recovery of the reference signal received power by measurements, computational and analytical methods or simulations and by any

carried combinations thereof. Frequently, for the area to be optimized location-based path loss data of the electric field strength of each base station location, eg. In matrix before, by means of which, taking into account the transmission power of the reference signal, the used antennas and other radio propagation losses, such as a body damping, the location-related

Reference signal received power can be calculated.

At each location where reference signal present receiving performance data, in a model of the communication network that radio cell is determined with the best reception performance. In this way, an allocation of surface elements to the radio cells.

All patches that are associated with a particular cell, are in their entirety (the only radio cell) considered radio cell area. by virtue of the physical propagation conditions in the radio channel, which apply to all services offered in the communications network, as well as the cell change algorithm to ensure the subscriber mobility, which is usually based on the measured at the subscriber terminals received power of the reference signal, the data obtained in communication network model radio cell surfaces can be a good approximation for the are actually used in a communications network occurring radio cells. In exemplary section of a mobile network according to Figure 1 are viewed located at the base stations Bl 10, B120, B130 and B140 around the just described manner adjusting radio cells with solid lines.

The aim of the process is to improve the throughput of messages in the communications network through an optimal distribution of the participants offered traffic between the radio cells. It has been found that the participants movement of all services can then be removed with the best quality, if there is a balanced possible traffic distribution between the radio cells. To this extent, this method aims to prepare these balance of traffic between the radio cells. To achieve this goal, ie specific radio cell surfaces must be shifted from each other, so that the otherwise unchanged fixed subscriber traffic can be abgetauscht between the radio cells.

The subscriber traffic per cell area is generally determined by accumulating the present traffic values ​​within the respective radio cells in the model of the communication network. Since multiple services, traffic per service at a particular location can be very different, have the

Fair values ​​of different services are summed accordingly suitably weighted. The weighting depends on the radio interference effectively generated by the respective service and resource utilization. Therefore, flow depending on the radio system parameter, such as, the system bandwidth, the channel bandwidth, the achievable ratio of signal power to interference power, the spreading factor, the average or maximum data rate, activity factor, the code boundary, etc., .in the Traffic weighting a. In Figure 1 are summed in this way traffic values ​​per cell with VI 10, VI 20, VI 30 and VI 40 indicated.

After the zeilbezogenen values ​​of subscriber traffic ready, must first in step 220 in Figure 2, a judgment of approximation achieved to the desired greatest possible balance of the subscriber traffic between the cells take place. For this purpose, as a possible variant of the invention a graphical representation of the examined mobile radio network, as in Figure 1, be used as an aid, wherein the individual radio cell surfaces are filled respectively with a guided in them subscriber traffic associated color. If after checking in step 230, according to Figure 2 a sufficient balance of the subscriber traffic between the cells already achieved, the process can be interrupted and the network configuration found in the simplest case be made available in accordance with step 270 in Figure 2 as an improved basis for planning of network planning. If this condition has not been reached, this is used

Representation in step 240 of the procedure shown in Figure 2 in which adjacent radio cells lead to the rapid detection of problem areas, very different traffic. In another variant of the invention, identification of problem areas can also be automated by a computationally industrial process, are examined in the differences of the subscriber traffic values ​​between adjacent cells. This automated step is then in the overall optimization process consisting to Figure 2, embedded in the steps 220 to 250 in order to minimize the differences of the subscriber traffic values ​​between the radio cells.

One after step 250 then in Figure 2 local shift of radio cell surfaces can be achieved by changing certain network configuration parameters at individual network elements in the model of the communication network, in particular by an appropriate adjustment of the antenna tilt angle or the antenna height of the antenna pattern used in each case or, eg. By adapting of the

Transmission power of the reference signal at selected radio cells. Because how. described above, all of these parameters in the determination of the reference signal received power received, which is of course for the training of radio cell areas of crucial importance, can thus be varied in this way, the radio cell surfaces. If, for example. In the network configuration of Figure 1 a locally limited high subscriber traffic VI 10 found in the cell of base station BL-10, an appropriate adjustment of network parameters should be done according to the invention, the reduction of these cell surface and therefore an acquisition of parts traffic from this cell causes in adjacent cells. After adjusting the network configuration, the relocation of the cell areas shown by dotted lines Ziph have set. This 10 cell were the stationary part Fair Values ​​VI 12, VI 13 and VI 14 withdrawn at the base station B110 from traffic VI.

These were divided according to the picture on the cells of the base stations B120, B130 and B140, which have now the market values ​​V120 + VI 12, V130 + VI 13 and VI 40 + VI 14th The reaching network configuration is then better if the unauthorized modification participants market value of the individual radio cells balanced than previously smd.

Appropriately, the change in the radio cell areas to achieve broadest balance of the subscriber traffic between the cells is iterative, so that the original network configuration can be gradually approximated to an optimized network configuration. In one iteration, only one or a few parameters of the network configuration can be changed. After approaching the desired balance of the subscriber traffic between the cells is checked again according to steps 220/230 in Figure 2, the new radio cell areas are used as a basis due to changes in network configuration. the necessary change is from the result of the review of

Network configuration in the next iteration derived. This procedure can also be automated by means of computational methods. The gradual approach can be canceled if there is sufficient balance of the subscriber traffic has been reached between the radio cells. In particular, it is a criterion that the traffic in the radio cells with the originally highest

Participants erverkehr significantly compared to the average Teilnehrnerverkehr was reduced in the radio network model. Such a reduction in traffic also reduces the local interference level, whereby the network quality may improve.

If a network configuration achieved, which has a considerably more balanced distribution of the subscriber traffic between the cells as the original configuration, can be an advantageous variant of the invention, the result of the power adjustment in accordance

Step 260 will be validated according to figure 2. Validation can; eg. by a

Network simulation done. It is expediently desirable but not essential, to be considered in this simulation, the time behavior of the network in order to evaluate the network quality. As a measure of power quality can include the number and locations of blocked connection attempts or of broken connections, the specified error rate and delay

Connections or the throughput per connection or radio cell are used.

Of course, even after the interworking sufficient network coverage must still be guaranteed, ie that the various services must be available at the predetermined locations.

Results of the radio network validation can then be used as a further advantageous variant of the invention, to use them in a renewed optimization of the radio network to increase the accuracy of the method. Such variables can, in particular, the actually occurring in the network simulation subscriber traffic, but also the harmful interference expressing sizes be. The latter include, inter alia, the so-called "Noise Rise", which characterizes the proportion of, based locally in a radio cell, caused by other subscriber radio interference on overall interference advent of the radio cell in the uplink. This size provides particularly for CDMA networks interesting clues to the local network utilization. Likewise, information about the local occurrence of Rufabweisungen, disconnections or failed cell change attempts can be used as boundary conditions for subsequent optimization of the radio network. In addition, also come designed to assess the cell separation, such as. the

Ratio of transmission power of the reference signal to the total interference power per radio cell, for this refinement of the method in question. Likewise, those aforementioned network simulations can be already applied to the original network configuration to enable a comparison to the optimized network configuration in terms of network quality in a further variant of the invention. This can also feed the said additional quantities from the network simulation in the process of the invention. Besides simulative determined traffic values ​​as direct input size in particular further boundary conditions for the process can be set. This concerns for example the various reasons and the local limitations of disconnections and -abweisungen whose analysis interesting insights for fine control of the invention

Method returns. As a variant, which may include some readings of other quantities from the real communication network, in particular the aforementioned variables, included in the initial review of the original network configuration.

In order to make the determined by the inventive method improved network configuration in the communication network used, the process in the device of the invention is embedded after Figure. 3 For further explanation, a distinction of the communication network in the radio access network 310 and the message switching network 330 was taken that can communicate via a bidirectional interface 320 together. The radio access network refers to the portion of the

News network, the direct harmful compound to the mobile! manufactures participants, ie, it mainly includes the base stations of the cellular network and possibly other ingredients, provided that they are necessary for direct communication with the participants. The message switching network is the network of base stations in the radio access network together with switching stations and gateways to other networks or service providers. Via the interface 320, both the transmitted messages of the participants as well as various signaling and control information can be transmitted in both directions. For the communications network, there is a database 350, the location data, configuration data of the individual network elements, measurement data of different sizes from the communications network, meter data from the network elements, call statistics, etc. Plaπungsdaten are summarized. It provides the database icon in Figure 3 first only a logical grouping all this data is - depending on the implementation with a network operator, this data collection can also be implemented in multiple needs moderately coupled databases. Data from the communication network at any time stored via the bidirectional interface 340 in the database as well as new network configurations are also recorded in the communications network. In addition, optional for example with a mobile measuring device 399 (not necessarily motorized as shown in the illustration), measured values ​​and parameters of the communications network in the database are stored.

To implement the method of the invention in the device is a

Computing means 370 which contains a computational implementation of the radio access network in the form of a radio network model 380th In this model, the initial network configuration reflects that was loaded via the bidirectional interface 360 ​​from the database. In the computing device now, the inventive method 390 operates according to Figure 2 on the basis of the

Radio network model to determine an improved network configuration. The changes to the network configuration are also conducted in computationally implemented radio network model 380, so that subsequently the improved configuration is set right there. If necessary, the optimization of the communication network can be controlled and monitored by a radio network optimizer.

This influence can also be limited largely by the above-described automation of the process.

The determined improved network configuration can be initially transmitted via the interface 360 ​​to the database and from there in the communications network. Through readings from the communications network 310, 330 itself, or via a measuring device 399, which reached improvement of throughput and power quality can be fully evaluated. Such measured quantities may again be played in the computing device in order to contribute there to the validation of the improved network configuration. Because in a communications network, especially of several services offered, the local subscriber traffic per service even briefly, that can be quite strong change several times a day to make, it is expedient to promptly adjust the network configuration to the changed conditions in terms of traffic. This can be done with a variant of the device according to the invention, the high speed of the underlying process is beneficial. In this variant, the current status of network configuration and traffic congestion, which are stored in the database 350, dubbed into the computing device 370 and, where they immediately processed with the inventive method. The timely detected, the current network conditions better suited to network configuration is then again transferred back to the database, from where they transferred directly to the communications network and is active there. In this way can be relatively quickly respond to a changing subscriber traffic in the communications network.

Although the present invention has been described in detail, along with their advantages, however, should be made clear that various other modifications and variations of the invention within the meaning of the above, can be realized without the spirit and scope of the invention as covered in the claims, departing would be.

The embodiment described below is used to illustrate the method according to the invention for optimizing communication networks based on a selected portion of a UMTS / FDD radio network whose general characteristics eg. In H. Holma and A. Toskala (ed.), "WCDMA for UMTS", 2nd Ed., John Wiley & Sons, Chichester, UK, 2002, ISBN 0-470-84467-1 are described. the starting point is an approximately 10km² comprehensive area represents, were arranged and configured in the total of 15 broadcast stations with 3 cells by usual today and the prior art planning methods. For each broadcasting station the path loss of arranged in a matrix receiving locations (path loss matrix) with a spatial resolution of 10m after the current state of the art with

calculated using ray optical dispersion models with the aid of a detailed 3-D world model. Furthermore, for a voice service (Speecfi) and a WWW service set (WWW) information for location-dependent traffic density in the form of traffic matrices with a spatial resolution of 25 m basis.

In the embodiment, the initial network configuration is analyzed using a dynamic UMTS-system simulator in terms of capacity and quality of news broadcasts. Then, the radio network is optimized by the method according to the invention and subjected to the changed network configuration of a new dynamic analysis was performed with respect to changes in capacity and quality.

For each cell is the resulting equivalent traffic based on the underlying traffic models and the present location-related

Traffic density information calculated. The situation resulting from the wave propagation conditions and network configuration local coverage area of ​​each cell can be color-code, the color code corresponding to the previously calculated equivalent traffic in Erlang. It is not the absolute value, but the relative deviation of the values ​​each of adjacent cells crucial.

For spatially adjacent cells very different to be taken off of traffic is expected. After analyzing the network configuration using a dynamic system simulator in terms of capacity and quality is inventively determined by iteratively changing the antenna bearings and the transmission power of reference signals solely based on the given location-based traffic and radio propagation data radio network configuration to be expected, a relative to the initial configuration much more balanced

having traffic.

It can be shown that the acquired with the optimization process of the invention network configuration having a more balanced distribution of the expected traffic volume on the cells. This should be the available overall radio network capacity can be better utilized. It is apparent that with the help of the optimization method according to the invention, the original block and connection breaking probability can be reduced in the example. It can nearly all service requests are allowed with the optimized network configuration and operated. In the exemplary embodiment, an increase in the simultaneously served by the radio network connections under the described conditions of 11% are demonstrated.