Method and system for integrating resource allocation between time division duplex and frequency division duplex in wireless communication systems
The present invention integrates resource allocation between time division duplex (TDD) and frequency division duplex (FDD) in wireless communication systems. A radio network controller (RNC) receives a radio access bearer (RAB) request from a core network or a wireless receive/transmit unit. The RNC utilizes a TDD-FDD selector to assign radio resources in response to the request. The TDD-FDD selector evaluates various parameters regarding the received RAB request and determines whether it is preferable to assign TDD resources or FDD resources and whether such resources are currently available. Once resources are assigned, system conditions are evaluated to determine whether optimizations may be made to a current resource allocation.
1. A method for integrating time division duplex (TDD) and frequency division duplex (FDD) in wireless communication systems, the method comprising the steps of:
receiving radio access bearer (RAB) requests at a radio network controller (RNC) along with a plurality of parameters regarding the request;
estimating at the RNC a degree of symmetry in uplink (UL) and downlink (DL) connections required to support communication associated with the RAB requests;
selecting either a TDD connection for both UL and DL or a FDD connection for both the UL and DL based on the estimated symmetry of the UL and DL connections, wherein a difference is calculated between a data rate on the uplink and a data rate on the downlink and TDD is selected where said difference is greater than a predetermined threshold and FDD is selected where the difference is not greater than the predetermined threshold.
2. The method of claim 1 wherein FDD connection is selected for RAB requests associated with voice applications.
3. The method of claim 1 further comprising: evaluating a symmetry status of the UL and DL connections periodically once an initial connection has been established in response to a RAB request; and switching between TDD and FDD modes based on said symmetry status.
4. The method of claim 1 wherein all RAB requests are processed through a FDD RNC.
5. The method of claim 4 wherein only the FDD RNC is connected to a core network through an Iu interface, and a TDD RNC is indirectly connected to the core network through the FDD RNC.
6. The method of claim 5 wherein the FDD RNC performs all call connections and disconnections.
7. A system for integrating TDD and FDD in a communication system, the system comprising:
a core network (CN);
a time division duplex radio network controller (TDD RNC);
a frequency division duplex radio network controller (FDD RNC); and,
a TDD-FDD selector configured to receive a RAB request and to estimate a symmetry of data rates between uplink (UL) and downlink (DL) connections that is required to support the RAB assignment request and to calculate a difference between a data rate on the uplink and a data rate on the downlink, and to make a decision to assign radio resources in either TDD mode for both UL and DL or FDD mode for both UL and DL based on the estimated symmetry of data rates between UL and DL connections, wherein TDD is selected where the difference of data rates between UL and DL connections is greater than a threshold and FDD is selected where the difference of data rates between UL and DL connections is not greater than the threshold.
8. The system of claim 7 wherein a FDD connection is selected for RAB requests associated with voice applications.
9. The system of claim 7 wherein the TDD RNC, the FDD RNC, and the TDD-FDD selector are integrated into an integrated TDD/FDD RNC.
10. The system of claim 7 wherein the FDD RNC includes a TDD serving radio network controller (S-RNC) and is configured to support TDD Iur protocols.
11. The system of claim 10 wherein only the CN and the FDD RNC are connected via an Iu interface and RAB requests are processed through the FDD RNC.