PS CHARGING: PCC & PCC RULES

In 3GPP R7, a new element called the PCRF - Policy and Charging Rule Function is introduced in the PS N/W .This element is used to store & provide Policy & Charging Rules for data subscribers.
A PCC rule normally consists of 2 parts:
1). Schedule
2). Trigger & related action.
Consider a Trigger as (Start busy hour at 21:00 HRS), PCRF will send the defined PCC rules to PCEF to enforce. e.g. Policy action will be enforced (reduce the MBR from 4Mbps to 256Kbps), & the required charging action  will also be enforced (from tariff X to Y).
The OCS is the charging engine for the PCC solution, if the PCRF informs the PCEF about the tariff change from X to Y, then how will the PCEF perform the charging with OCS?
There is a parameter i.e. Rating Group (RG) to play this role. e.g. if the operator wants to implement different tariffs for different types of service. The PCRF will define different RG for different service flows, the RG in OCS refers to different Rating plan. So, from the RG, we can provide different tariff for different service. If we want to change tariff from X to Y, As the trigger to be triggered (Say Start busy hour at 21:00 HRS), the PCRF will inform PCEF to change the RG from say 1 to 2 & then the rating plan in OCS will change accordingly.
Actually, the PCC rules defined in the PCRF can be very flexible, can have combined trigger conditions, such as location, time & Quota, the action also can be combined, such redirection & throttling. It depends on the scenario that the operator desires.
The PCC solution is a very hot topic for most operators, because it can enable the operator to provide more flexible data service packages to monetize the data service as well as to improve the efficiency of the PS N/W.
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