Method and system for determining correct escape mechanisms and controlling interference in third generation wireless systems

Abstract

A correct escape mechanism is determined according to interference type. Transmission is arranged so that interference may be measured at all time slots as needed to compute a measure of variance in interference in time slots. If the variance is above a predetermined value, time division duplex escape mechanisms are employed. If the variance is below a predetermined value, appropriate escape mechanisms are employed depending on whether the escape mechanism is being implemented during an uplink or downlink. Interference causing FDD WTUs may be handed over to carrier bands to control interference experienced by TDD users.

1 . A method for controlling interference in a wireless communication network having overlapping time division duplex (TDD) and frequency division duplex (FDD) coverage areas, wherein a communication is transmitted in a time slotted channel, the method comprising: 
 measuring a level of interference in each time slot;    determining whether the interference is continuous or discontinuous over a predetermined number of time slots;    employing a hand over mechanism if the interference is determined to be continuous; and    employing a TDD escape mechanism if the interference is determined to be discontinuous.    
   
   
       2 . The method of  claim 1 , wherein determining whether the interference is continuous or discontinuous is based on the variance of the interference level of each time slot over a certain number of time slots.  
   
   
       3 . The method of  claim 2 , wherein the time slotted channel comprises downlink time slots, and the interference level is determined based on interference in downlink time slots.  
   
   
       4 . The method of  claim 3 , wherein the time slotted channel further comprises uplink time slots, and the interference level is determined based on interference in downlink and uplink time slots.  
   
   
       5 . The method of  claim 1 , wherein the TDD escape mechanism includes slot reallocation, dynamic channel allocation, and dynamic channel selection.  
   
   
       6 . A method for controlling interference in a wireless communication network having an overlapping time division duplex (TDD) and frequency division duplex (FDD) coverage area where a communication is transmitted in a time slotted channel, the method comprising: 
 determining a level of interference experienced by a TDD wireless transmit receive unit (WTRU) operating in a TDD mode in a TDD coverage area;    locating an FDD WTRU operating in an FDD mode in a first frequency band in the TDD coverage area; and    handing over the FDD WTRU to a second frequency band if the level of interference is above a predetermined threshold.    
   
   
       7 . The method of  claim 6 , wherein the handover procedure is initiated only when a number of TDD WTRUs operating in a TDD mode that are experiencing interference is above a predetermined threshold.  
   
   
       8 . The method of  claim 6 , wherein the second frequency band is not adjacent to a frequency band for the TDD mode.  
   
   
       9 . A system for controlling interference in a wireless communication network having an overlapping time division duplex (TDD) and frequency division duplex (FDD) coverage area where a communication is transmitted in a time slotted channel, the system comprising: 
 a wireless transmit/receive unit comprising: 
 a detector for detecting an interference level of a current channel; and,  
 a transmitter for reporting the interference level;  
   a radio network controller comprising: 
 a processor configured to determine whether the reported interference is continuous or discontinuous over a certain number of time slots, and to employ a hand over mechanism if the interference is continuous or a TDD escape mechanism if the interference is discontinuous.  
   
   
   
       10 . The system of  claim 9 , wherein the processor is further configured to determine a variance of the interference level of each time slot over a certain number of time slots.  
   
   
       11 . The system of  claim 10 , wherein the time slotted channel comprises downlink time slots, and the processor is further configured to determine the variance based on interference in downlink time slots.  
   
   
       12 . The system of  claim 11 , wherein the time slotted channel further comprises uplink time slots, and the processor is further configured to determine the variance based on interference in downlink and uplink time slots.  
   
   
       13 . The system of  claim 9 , wherein the processor is further configured to implement TDD escape mechanisms that include slot reallocation, dynamic channel allocation and dynamic channel selection.  
   
   
       14 . A system for controlling interference in a wireless communication network having an overlapping time division duplex (TDD) and frequency division duplex (FDD) coverage area where a communication is transmitted over a time slotted channel, the system comprising: 
 a TDD wireless transmit/receive unit (WTRU) operating in a TDD mode in a TDD coverage area comprising means for measuring an interference level experienced by the TDD WTRU;    a radio network controller comprising: 
 a processor configured to locate an FDD WTRU operating in an FDD mode in a first frequency band in the TDD coverage area; and to hand over the FDD WTRU to a second frequency band if the interference level is above a predetermined threshold.  
   
   
   
       15 . A system of  claim 14 , wherein the processor is configured to hand over the FDD WTRU only if a number of TDD WTRUs operating in a TDD mode that are experiencing interference is above a predetermined threshold.  
   
   
       16 . The system of  claim 14 , wherein the processor is configured to hand over the FDD WTRU to a second frequency band that is not adjacent to a frequency band for the TDD mode.  
   
   
       17 . A wireless transmit/receive unit (WTRU) for use in a wireless communication network having interference controls and an overlapping time division duplex (TDD) and frequency division duplex (FDD) coverage area, the WTRU comprising: 
 a detector for detecting an interference level of a current channel;    a transmitter for transmitting the interference level to a radio network controller (RNC) to enable the RNC to provide the WTRU with an appropriate mechanism for mitigating the effect of interference on the current channel; and    a processor configured to employ an interference control mechanism determined by the radio network controller.    
   
   
       18 . The WTRU of  claim 17 , wherein the processor is further configured to employ a handover mechanism when the radio network controller determines the interference to be continuous.  
   
   
       19 . The WTRU of  claim 17 , wherein the processor is further configured to employ a TDD escape mechanism when the radio network controller determines the interference to be discontinuous.  
   
   
       20 . The WTRU of  claim 17 , wherein the WTRU is configured as an FDD WTRU.  
   
   
       21 . The WTRU of  claim 17 , wherein the WTRU is configured as a TDD WTRU.