Wireless networks are multi-user systems where access coordination co achieved using technologies such as time division multiple access (TDMA), frequency division multiple access (FDMA) or code division multiple access (CDMA). On top of this, signal insulation is attained by splitting the available resource into orthogonal chunks (frequency, time slices or coding sequence).

Overture models the multiple-access aspects of the technology through Layer Models. One layer model is assigned to each orthogonal layer in the network. Layers can also be hierarchical, to model situations where the choice of a parameter in one layer affects the performance of other layers.

Overture uses Flags to store the technology-specific settings in Radios and Sectors. The layer model links the settings of these flags to the RF performance of the network.

Accessing the Layer Model collection

You can access the collection of layer models from the Analysis > Layer Models > Edit List menu option:

This launches the layer model collection editor:

Common Properties

All layer models have the following properties:

• Adjacency Matrix. This specifies the interference relationships between each value of the associated parameter.
• Max Layers. This is the maximum number of servers that will be considered at each location on this layer.
• Name. The name of the model layer.
• Parent. This is a reference to the parent model layer. This is used when constructing hierarchical model layers, such that the choice of a parameter in the parent layer affects the performance of this layer.
• Resource Overlap Threshold. This is the trigger threshold that is used to indicate a resource overlap. It is used when generating the resource reuse report.
• Ignore Co-site Reuse. If set to True, then co-sited radios will be ignored when generating the reuse report.
• Statistical Interference. If set to True then a statistical view of interference will be taken instead of considering the actual resource assignments. This is useful if you wish to consider interference without needing to do a full parameter optimization.

Common Actions

All layer models have the following actions:

• Enforce Constraints. Enforce the channel constraints on each site.
• Resource Reuse. This action generates a resource reuse report. For each radio, this shows you the distance to the closest radio having the same assignment on that layer. This can be a useful aid to both manual and automatic planning.

Layer Model Types

The following layer model types are available:

• CDMA Layer. This layer model is configured for CDMA systems. It has the following specific properties:
  • Channel Noise. This is the thermal noise across a whole channel.
  • Channels. The number of available channels.
  • Channel Width. The bandwidth of each channel.
  • Load Flag. This is the Flag that specifies the percentage loading per radio.
  • Noise Density. This is the noise spectral density.
  • Paging Flag. This is the Flag that contains the paging channel setting.
  • Pilot Flag. This is the Flag that contains the pilot channel setting.
  • Sync Flag. This is the Flag that contains the synchronization channel setting.
• Flag Layer. This creates a layer model from a radio Flag. This type of layer is used to support technology-specific parameters. It has the following specific properties:
  • Flag. This is the Flag that is used to hold the values of the associated parameter.
• GSM Layer. This layer model is configured for GSM systems. It has the following specific properties:
  • Adjacent Interference. This specifies the amount of interference caused by adjacent channels.
  • Channel Noise. This is the thermal noise across a whole channel.
  • Channels. The number of available channels.
  • Channel Width. The bandwidth of each channel.
  • Hopping Flag. This is the Flag that indicates if the radio is configured for frequency hopping or not.
  • Interference View. This can be set to one of the following values Primary Only (only noise experienced by the primary layer will be used) or All Elements (noise will be normalized across all layers).
  • Load Flag. This is the Flag that specifies the percentage loading per radio.
  • Noise Density. This is the noise spectral density.
  • Mobile Allocation Lists. These are the mobile allocation lists used for frequency hopping.
  • Traffic Channels. This is the Flag that holds traffic channel assignment information for this sector. For hopping radios, the indices refer to hopping group numbers, and for non-hopping radios, the indices are literal channel numbers.
• LTE Layer. This layer model is configured for LTE systems. It has the following specific properties:
  • Channel Noise. This is the thermal noise across a whole channel.
  • Channels. The number of available channels.
  • Channel Width. The bandwidth of each channel.
  • Load Flag. This is the Flag that specifies the percentage loading per radio.
  • Noise Density. This is the noise spectral density.
• Technology Neutral Layer. This layer model is a generic model with no specific rules for calculating interference. It has the following specific properties:
  • Channel Noise. This is the thermal noise across a whole channel.
  • Channels. The number of available channels.
  • Channel Width. The bandwidth of each channel.
  • Load Flag. This is the Flag that specifies the percentage loading per radio.
  • Noise Density. This is the noise spectral density.
• WCDMA Layer. This layer model is configured for WCDMA systems. It has the following specific properties:
  • Channel Noise. This is the thermal noise across a whole channel.
  • Channels. The number of available channels.
  • Channel Width. The bandwidth of each channel.
  • Load Flag. This is the Flag that specifies the percentage loading per radio.
  • Noise Density. This is the noise spectral density.
  • Paging Flag. This is the Flag that contains the paging channel setting.
  • Pilot Flag. This is the Flag that contains the pilot channel setting.
• WiMAX Layer. This layer models is configured for WiMAX systems. It has the following specific properties:
  • Channel Noise. This is the thermal noise across a whole channel.
  • Channels. The number of available channels.
  • Channel Width. The bandwidth of each channel.
  • Load Flag. This is the Flag that specifies the percentage loading per radio.
  • Noise Density. This is the noise spectral density.