文档介绍：Hierarchical Cell Structures
HCS
03813-LZU 108 3704 Uae Rev c Slide 1 (28) GSM work Features
Introduction
• Today, capacity is a problem
• Only small cells give limited coverage
• Only large cells give limited capacity
• Situation where to favor a weaker cell
- Combined microcell/macrocell
- Multiband GSM 900/GSM 1800
03813-LZU 108 3704 Uae Rev C Slide 2(28) GSM work Features
Background
• Locating primarily based on "best server"
• Situation where to favor a weaker cell
- combined micro/macro
- multiband GSM 900/GSM 1800
03813-LZU 108 3704 Uae Rev c Slide 3 (28) GSM work Features
What Can Be Achieved
• Network in layers and bands
• Large cells as umbrella cells and small cells to
provide extra "hot spot" capacity
• HCS makes it possible to pass between layers in a
controlled way
• Traffic is directed to lower layers
03813-LZU 108 3704 Uae Rev c Slide 4 (28) GSM work Features
Cell layer
Cells that have similarities in function and size can be
seen as belonging to the same cell layer. HCS can be
used to give different priority to different layers.
Examples of layers are;
• macrocells, providing the main coverage and often
main
capacity
• street cells or microcells with their lower antennas, less
expensive and more shielded sites
• indoor/picocells
• macro-, micro- or picocells of another system type in a
work
03813-LZU 108 3704 Uae Rev c Slide 5 (28) GSM work Features
Frequency Band
• The available frequencies can be grouped into different
bands that do not cause interference to each other
• The 900 and 1800 MHz frequencies naturally form
different bands.
• These bands can be further divided into sub bands.
03813-LZU 108 3704 Uae Rev c Slide 6 (28) GSM work Features
Bands and Layers
• The priority of a cell is given by associating a layer to the
cell.
• Each layer is also belonging to an HCS band. The lower
the layer (and HCS band), the higher is the priority.
• Up to eight layers may be