Abstract:
A method and apparatus for simulating a modification to or expansion of a communications network and for determining whether the simulated modified or expanded network meets cost criteria. First logic forecasts an increase in network traffic. Second logic simulates a modification to or expansion of the network based on the forecasted increase in network traffic and/or based on performance improvement criteria and/or based on coverage expansion criteria. Third logic determines whether the simulated modified or expanded network meets cost criteria.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of Invention  
         [0002]     The present invention is directed to wireless communications networks, and more particularly, to a system that automatically determines the manner in which available capital should be spent in order to achieve a given level of performance in a wireless network.  
         [0003]     2. Description of Related Art  
         [0004]     As wireless network subscriber bases grow, decisions must be made as to what changes need to be made to the network in order to meet growing demands. Changes to the network may include adding new equipment, such as a new cell site, for example, or making modifications to existing equipment, such as, for example, changing the azimuth of an antenna of an existing cell site. The cost of making a change will vary depending on the type of change that is made. For example, adding a new cell site may cost hundreds of thousands of dollars, whereas changing the azimuth of an existing cell site antenna may cost a few thousand dollars. Therefore, it is extremely important that the solution that is implemented be a cost effective solution and that it enable a desired or necessary level of network quality performance to be achieved.  
         [0005]     Voice channel forecast (VCF) tools are used by network designers to project, or forecast, increases in network traffic that will occur as a result of increases in the number of subscribers using the network. The VCF tool is provided with financial information, such as subscriber sales information, for example, and network capacity information, such as the number of available channels of a cell site, for example. Based on this information, the VCF tool forecasts increases in network traffic for each sector of the network over a given period of time and determines whether or not the increases will exceed network capacity. Using these forecasts, designers use other tools to determine how the network can be modified or expanded to meet the forecasted increases in network traffic.  
         [0006]     A tool known as an automatic cell planning (ACP) analyzer receives as its input a network traffic forecast generated by the VCF tool and an existing network configuration. The ACP analyzer processes this information and outputs the locations of any additional cell sites that need to be added to the network to meet the forecasted increased traffic demands. If the VCF tool indicates that network capacity for a given network sector will be exceeded by a particular amount, the ACP analyzer will determine the number of cell sites that need to be added to meet the increased demand. The ACP analyzer also determines whether other types of cell site modifications need to be made such as, for example, an antenna type change, an antenna orientation change, an antenna height change, an antenna tilt change, cell site relocation, sector addition, power change, etc.  
         [0007]     A tool known as an automatic frequency planning (AFP) analyzer receives as its input a traffic forecast and an existing network configuration and outputs the number of additional frequencies that will need to be added to the network to meet the forecasted increased traffic demands. If the VCF tool indicates that network capacity for a given sector will be exceeded by a particular amount, the AFP analyzer will determine the number of channels that need to be added to a cell site to meet the increased demand. The ACP and AFP analyzers can be run simultaneously to create multiple combinations of changes.  
         [0008]     Network designers also look at the costs associated with making an expansion or modification to the network. Typically, a certain amount of capital is available to make expansions or modifications and the designer must take this into account when determining what changes will be made. The cost information is available to the designers, so they know the costs associated with making various types of changes to the network. For example, if a designer can meet the increased traffic demand by adding additional channels rather than adding an additional cell site, the designer will often opt for the less expensive solution of adding more channels. Erlang constraints limit the number of frequencies, and thus the number of channels, that can be carried by a cell site. Such constraints may make it necessary to add another cell site as opposed to increasing the number of channels of the cell site. In addition, quality of service (QoS) is taken into account to ensure that whatever changes are made to the network enable the network to achieve a particular quality of service. For example, a QoS metric known as grade of service (GOS) is a measurement of the number of blocked calls that will be tolerated. The network designer may determine that adding additional channels rather than adding another cell site will result in an intolerable number of calls being blocked, and thus opt for the more expensive solution of adding another cell site.  
         [0009]     A tool known as a QoS analyzer analyzes a network configuration generated by the ACP and/or AFP analyzers and predicts the network performance of the new network configuration. A tool known as a key performance indicators (KPI) analyzer works in conjunction with the QoS analyzer. The KPIs are metrics utilized to measure system performance. When the QoS analyzer predicts network performance, the KPI analyzer measures the predicted performance against the KPIs to determine the level of network quality performance.  
         [0010]     Although tools such as those mentioned above are available to help network designers decide which solutions are the most cost effective, the decision making process is difficult because it is a subjective process that requires the designer to look at many different variables simultaneously and determine which solutions achieve the desired level of performance and are the most cost effective. As a result, the process of making these choices is prone to human error, and the solutions that are implemented may not be cost effective and/or may not achieve the best level of performance.  
         [0011]     A need exists for a system that automates the process of determining the types of changes that can be made to a network to achieve a desired level of performance and, of those solutions, which are the most cost effective. By automating this process, it is possible to eliminate problems associated with implementing solutions that do not achieve the desired level of network quality performance and/or that are not cost effective.  
       SUMMARY OF THE INVENTION  
       [0012]     The present invention provides a method and apparatus for simulating a modification to or expansion of a communications network and for determining whether the simulated modified or expanded network meets cost criteria.  
         [0013]     In accordance with the preferred embodiment, the apparatus includes first logic that forecasts an increase in network traffic, second logic that simulates a modification to or expansion of the network based on the forecasted increase in network traffic and/or based on performance improvement criteria and/or coverage expansion criteria. Third logic of the apparatus determines whether the simulated modified or expanded network meets cost criteria.  
         [0014]     The method of the present invention comprises forecasting an increase in network traffic, simulating a modification to or expansion of the network based on the forecasted increase in network traffic and/or based on performance improvement criteria and/or coverage expansion criteria, and determining whether the simulated modified or expanded network meets cost criteria.  
         [0015]     The present invention also provides a computer program for automatically determining whether a modification to or expansion of a communications network meets cost criteria. The program comprises a first code segment for forecasting an increase in network traffic, a second code segment for simulating a modification to or expansion of the network based on the forecasted increase in network traffic and/or based on performance improvement criteria and/or coverage expansion criteria, and a third code segment for determining whether the simulated modification or expansion meets cost criteria.  
         [0016]     These and other features and advantages of the present invention will become apparent from the following description, drawings and claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a pictorial illustration of the apparatus of the present invention in accordance with an embodiment.  
         [0018]      FIG. 2  is a flow chart of the method of the invention in accordance with an embodiment for determining whether a simulated network configuration meets growth demands, quality standards and cost constraints.  
         [0019]      FIG. 3  is a functional flow diagram of the invention in accordance with an exemplary embodiment in which category weighting is utilized by the configuration simulation and selection software modules to obtain a new network configuration that meets quality and performance goals and cost constraints. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0020]      FIG. 1  is a block diagram of the apparatus  1  of the present invention in accordance with the preferred embodiment. The apparatus  1  includes a computer  10  that is programmed to execute software modules  20 ,  30  and  40 . The computer  10  receives input  11  in the form of current network configuration information, quality of service (QoS) metrics, cost information relating to the costs associated with making various types of additions or modifications to the network, and financial information relating to advertisements or promotions aimed at increasing the subscriber base. The computer  10  processes this information in accordance with a VCF software module  20 , a network configuration simulation software module  30  and a network configuration selection software module  40  and selects a new network configuration  50  that is capable of handling the increased demand, that meets QoS goals and that is cost effective. Preferably, the selected new network configuration  50  is the most cost effective solution, as described below in more detail with reference to  FIG. 2 .  
         [0021]     Each of the software modules  20 ,  30  and  40  performs a different function. These functions will now be described with reference to  FIG. 2 .  FIG. 2  is a flow chart of the method of the present invention in accordance with an embodiment. The VCF module  20  performs the typical aforementioned functions of a VCF tool. The VCF module  20  uses information about the current network configuration to determine the limitations on the capacity of the current network. The VCF module  20  uses financial information, such as advertisements and promotions targeted at subscribers, for example, to forecast an increase in network traffic. Based on the projected increase in network traffic and the current capacity of the network, the VCF module  20  determines whether or not the increase will exceed network capacity, and if so, the extent to which the increase will exceed current capacity. The operations performed by the VCF module  20  are represented by block  61 .  
         [0022]     Once the extent to which the increase in network traffic will exceed current network capacity has been determined by the VCF module  20 , the network configuration simulation software module  30  automatically modifies the current network configuration through simulation to meet the increased network traffic and/or that achieves performance improvement goals and/or coverage expansion goals, as indicated by block  62 . There may be cases in which no increase in network traffic is predicted or anticipated, and yet performance improvements are needed or desired, such as, for example, a reduction in the number of dropped calls. In such cases, the simulation software module  30  is capable of simulating a modification to or expansion of the current network configuration to achieve the performance improvement. Similarly, there may be cases in which no increase in network traffic is predicted or anticipated, and yet an expansion in coverage is needed or desired to handle more users. In such cases, the simulation software module  30  is capable of simulating a modification to or expansion of the current network configuration to achieve the expansion in coverage.  
         [0023]     The simulation software module  30  preferably is a combination of existing software tools that interact with each other to achieve a new network configuration. These tools preferably include the aforementioned ACP, AFP, QoS and KPI analyzers, which operate in conjunction with each other to determine whether any additional cell sites or additional frequencies are needed or whether any other network modifications are needed. Network modifications include adding new channels, adding new cell sites, changing the antenna type, changing the antenna orientation, changing the antenna height, changing the antenna tilt, relocating a cell site, adding a new sector, changing the power, etc. These analyzers work together to find the best solution that meets performance requirements.  
         [0024]     Once the configuration simulation module  30  has simulated a new network configuration (i.e., a modification or expansion of the existing network configuration), the network configuration selection module  40  determines whether the new configuration meets cost constraints, as indicated by block  63 . If so, the network configuration selection module  40  will select this modified or expanded network configuration as the new network configuration to be implemented, as indicated by block  64 . If not, then the network configuration selection module  40  preferably will cause the simulation to be re-run so that a more cost effective configuration can be found, as indicated by the arrow  65  from block  63  to block  62 .  
         [0025]     Preferably, this process is repeated until the most cost effective solution is found. Each time a simulation is run, preferably a report is generated that lists the modifications to be made and a cost associated with each type of modification. The configuration selection module  40  uses this information to determine whether the new network configuration meets the cost target. A report describing the simulated network configuration and projected cost preferably is displayed on display  12  to the network designer. The computer  10  may be connected to a printer  13  to enable the report to be printed out by the designer.  
         [0026]     In order to enable the network configuration simulation software module  30  to simulate modified or expanded network configurations that achieve the desired levels of performance, preferably the module  30  is provided with priority information that prioritizes modifications or expansions. The network configuration simulation module  30  uses this priority information to generate a new network configuration that meets quality and performance goals. The network configuration simulation software module  30  performs the prioritization by weighting certain parameters more than others.  FIG. 3  is a functional flow diagram of the invention in accordance with an exemplary embodiment in which weighting is utilized by the configuration simulation software module  30  to obtain a new network configuration that meets quality and performance goals and cost constraints. In accordance with this embodiment, the input  71  to the computer  10  ( FIG. 1 ) includes QoS criteria, KPI metrics (e.g., grade of service (GOS)), percent weighting factors (i.e., prioritization), cost models that indicate the costs of the different types of modifications, and an interference matrix that indicates call interference zones in the network sectors.  
         [0027]     The percent weighting factors indicate the amount of weight that should be given to certain network objectives, such as, for example, revenue initiatives, growth planning and quality of service. Revenue initiatives include information such as, for example, the number of capacity cell sites that should be deployed to help meet revenue initiatives, the types of network modifications that should be made to help meet revenue initiatives, the number of channels that should be added to meet revenue initiatives, and the number of base controller stations (BCSs) and mobile switching centers (MSCs) that should be added to help meet revenue initiatives. Growth planning includes, for example, the number of in-building cell sites that should be deployed to meet growth planning objectives, the number of in-fill coverage cell sites that need to be deployed to meet growth planning objectives and the number of coverage expansion sites that need to be deployed to meet growth planning objectives. Quality of service includes, for example, the number of interference cell sites that need to be deployed, customer retention goals that need to be met, and levels of voice quality that need to be achieved. By weighting the amount of emphasis that will be placed on revenue initiatives, growth planning, and quality of service, network strategies that lead to cost effective network improvement are made possible.  
         [0028]     The input  71  is received by network configuration simulation logic  70 , which includes logic for processing the input  71  in accordance with ACP, AFP, QoS and KPI algorithms performed by ACP logic  74 , AFP logic  75 , QoS logic  76  and KPI logic  77 . The manner in which these algorithms typically process information and interact with each other is described above with reference to  FIG. 1 . The network configuration simulation logic  70  also receives the output of the VCF logic  81 . The VCF logic  81  performs the VCF functions described above with reference to  FIG. 1 .  
         [0029]     The output  73  generated by the network configuration simulation logic  70  includes a new network configuration (i.e., a modified or expanded network) and the cost of the modified or expanded network configuration. This output  73  is received and processed by network configuration selection logic  80 . The network configuration selection logic  80  determines whether the new network configuration meets the forecasted increase in growth and QoS standards, as indicated by block  82 . If not, the simulation is re-run by the simulation logic  80 . If the forecasted increase in growth and QoS standards are met, then a determination is made as to whether the cost is within a particular range (e.g., between 97% and 100% of the projected cost) that is deemed to be optimum or acceptable, as indicated by block  83 . If the cost is not within this range, the simulation is re-run. When the simulation is re-rerun, the network configuration selection logic  80  may inform the network configuration simulation logic  70  to make certain alterations to the network configuration to reduce the overall cost, such as, for example, reducing the number of coverage cell sites and interference cell sites. If a determination is made at block  83  that the cost is within the specified range, then the network configuration is selected as the new network configuration, as indicated by block  84 .  
         [0030]     It should be noted that the present invention has been described with reference to particular embodiments and that the invention is not limited to these embodiments. For example, the decisions represented by blocks  82  and  83  may be made in an order that is the reverse of the order shown. However, the order shown is preferred because it is the most efficient. If a network configuration does not meet growth demands and quality standards, there is no need to determine whether the configuration meets cost constraints. Other modifications can be made to the embodiments described herein and all such modifications are within the scope of the invention.