UMTS Capacity Planning

To figure out the WCDMA network, we have to associate the several information. As WCDMA blockage can occur at several part also the multiple-service will consume different resource in the network. Furthermore the congestion in WCDMA is consisting of soft and hard blocking.To avoid the congestion and blockage of the service, we have to monitor the following resources 



CE/Iub Dimensioning
A channel element (CE) is defined as the baseband resources required in the NodeB to provide capacity for 12.2 k AMR voice, including 3.4 k DCCH. The HSUPA shares the CE resource with the R99 services.

• Signaling and CCH not required CE

• CE are pooled per NodeB for all cells

• Low CE resource required for higher data rate

• Advance algorithm improve the utilize efficiency of Iub transmission

Each service type will occupy different resources. Hence we  should divide the traffic volume corresponding to each service type to understand the characteristic of the cell. 
– AMR 
– VP 
– PS R99 DL 
– PS R99 UL 
– HSDPA 
– HSUPA 

CE resource is consisting of hardware and software. CE is  the pool resource at NodeB level, all cells connected to NodeB will share the same CE resource.
OVSF Code Resource 
OVSF Code is the limit resource of each cell. The expansion  can’t be possible in a single cell. OVSF Code will be limited only DL direction. 
• Typical usage of OVSF code 
             –AMR           : SF128 – SF256  
             –VP              : SF32 
             –PS R99 DL   : SF8 – SF128 
             –HSDPA        : SF16, Maximum is 15 * SF16 
HSDPA Code usage is depended on Manual or Automatic assignment. More OVSF code manually assigned to HSDPA is less OVSF code left for R99. 
more OVSF Code Resource
UL and DL Power Resource 

• Even the UL power is not limit corresponding to each UE  power, but the noise raise will trig the rejection due to Call Admission Control as well. Hence, the increment in UL load can cause service rejection and slow down the data service. 

• DL Power Limit is considered at RRU total power. Typical use  of RRU power in True move is 20 and 40 watt. 

• In general, the common control channel will consume about  20% of total power. 

• The power consumption of each service will be different as  well as the radio condition of each UE (e.g. distance, RSCP, Ec/Io) 

• HSDPA will use the remaining power left from R99 service.

• Iub is the pool resource at NodeB, each Radio Unit have to share  same Iub resource. 
• Typical configuration bandwidth of Iub is 10, 16 and 20 Mbps, based on traffic. 
• True move deploys IP based Iub transmission. 
Total resource usage
Total resource usage

2 states of service interruption from the picture
• The user can’t get the service (rejection). 
• The user can’t get at the desire QoS (low throughput of data service)
Total Power in a Cell
Total Carrier Power (TCP) is one of limited resource depending upon Radio unit total power output that impact directly to cell capacity and performance. Although it’s the same Radio unit power, it may different in the capacity because of UE distribution in a cell. To overview the power setting in a cell, we can check parameter setting of total power and CPICH power. 
CPICH Power 
– MaxPCPICHPower (~ 10% of total cell power) 
– Default = 33 or 36 dBm
Total Power
– MaxTxPower 
– Default = 43 or 46 dBm according to license
CPICH power + common channel will consume around  20% of total cell power. 

Source:http://www.ajusady.com/