Improving coverage and capacity in cellular systems
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The document discusses methods for improving capacity in cellular systems, including cell splitting, sectoring, and coverage zones. Cell splitting involves subdividing a congested cell into smaller cells to allow for greater frequency reuse and spatial reuse, thereby increasing system capacity. Sectoring uses directional antennas to control interference and optimize frequency reuse within each cell. Coverage zones distribute a cell's coverage to extend its boundary into hard-to-reach areas.
Improving coverage and capacity in cellular systems
- 1. Improving Capacity in Cellular Systems
- 2. Improving Capacity in Cellular Systems • Methods for improving capacity in cellular systems – Cell Splitting: subdividing a congested cell into smaller cells. – Sectoring: directional antennas to control the interference and frequency reuse. – Coverage zone : Distributing the coverage of a cell and extends the cell boundary to hard-to-reach place.
- 3. Sectoring • Decrease the co-channel interference and keep the cell radius R unchanged – Replacing single omni-directional antenna by several directional antennas – Radiating within a specified sector
- 4. 4 Cell splitting • If higher capacity is needed in a spot, we need to go, locally, to smaller cluster size N • Each cell can be split into multiple “microcells” with own BS • Rescaling system to smaller cell size • Transmit power of BS reduced to obtain smaller coverage area than original BS • Enables more spatial reuse → greater system capacity • Cell splitting preserves original frequency reuse plan • Cell splitting causes increased handoff • Can use “umbrella” cells where fast-moving mobiles covered by original cell and slower mobiles covered by microcells
- 5. 5 Cell Splitting Example F D B G C F E D G C F E D B E B G C D E F G B C A F D B G C F E D G C F E D B E B G C A
- 7. Cell Splitting • Split congested cell into smaller cells. – Preserve frequency reuse plan. – Reduce transmission power. microcell Reduce R to R/2
- 8. Interference Reduction position of the mobile Interference cells