RAN Planning
Planning the UMTS RAN and core network side is basically selecting the desired network layout, future expansion approach, calculating the required hardware, deciding software features and dimensioning all interfaces.
Radio Access Network has several interfaces, which need to be configured and dimensioned. This dimensioning is out of the scope of this page, but these are the RAN interfaces that need to be configured:
Iu: Interface between the RNC and the Core Network (MSC or SGSN).
- Iucs: Iu circuit switched (voice from/to MSC)
- Iups: Iu packet switched (data from/to SGSN)
Iub: Interface between the RNC and the Node B.
Iur: Interface between two RNCs.
Node B amount is derived form air interface capacity and coverage calculations, but Node Bs also have to be configured. Hardware configuration is vendor specific, but here is a general list of things that need to be considered when configuring Node Bs:
Call mix of expected traffic
Type of Node Bs (outdoor vs. indoor)
Amount of low capacity Node Bs
Required redundancies (e.g. 2N, N+1)
Required diversities
Number of carriers per sector
Number of sectors per Node B
Number of users
Voice and data traffic to be carried
Node B software features
Required Node B optional features
Requirements for special antenna systems
Requirements for power and transmission systems
The RNC planning is done after the air interface dimensioning and network interfaces planning. After those are prepared, the bandwidth of each RNC link is known. RNC dimensioning is to calculate the number RNCs and configuration of RNCs needed to support the radio access network requirements. Any network side equipment will have the trade-offs in configuration selection. Network can be designed for maximising the ease of future expansion or for minimising the total cost. Usually RNC locations are fixed based on network operator's main site locations and transmission costs will determine the most cost effective RNC configurations. RNC Hardware configuration is also vendor specific, but here is a general list of things that need to be considered when dimensioning RNCs:
RNC capacity and configuration options
Total CS traffic (Erlangs)
Total PS traffic (Mbps)
Total traffic and signalling load
Total number of Node Bs
Total number of cells
Total number of carriers
Used channel configurations
RNC software features
Required RNC optional features
Type of transmission interfaces
Expansion possibilities
Next: Core Network Design.
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3G Network Planning Basics
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