Techniques for Radio Link Problem and Recovery Detection in a Wireless Communication System

Abstract

A technique for radio link detection in a wireless communication system includes estimating a first error rate of an indicator channel. In this case, the indicator channel includes an indication of a number of symbols in a control channel. A second error rate of the control channel is also estimated. The first and second error rates are then combined to provide a performance metric. Based on the performance metric, a determination is made as to whether a radio link problem exists.

1 - 20 . (canceled) 
     
     
         21 . A method of monitoring a radio downlink, comprising:
 at a subscriber station:   receiving reference symbols;   estimating a quality metric of the radio downlink based on the reference symbols;   comparing the quality metric of the radio downlink to a first threshold, wherein the first threshold corresponds to a value of the quality metric at which the radio downlink cannot be reliably received by the subscriber station; and   comparing the quality metric of the radio downlink to a second threshold, wherein the second threshold corresponds to a value of the quality metric indicating the subscriber station is in synchronization with a base station transmitting the reference symbols.   
     
     
         22 . The method of  claim 21 , wherein the quality metric is used to estimate a first error rate for a control channel and a second error rate for an indicator channel. 
     
     
         23 . The method of  claim 22 , wherein the control channel is a physical downlink control channel (PDCCH) and the indicator channel is a physical control format indicator channel (PCFICH). 
     
     
         24 . The method of  claim 22 , wherein the indicator channel includes a control format indicator (CFI) that indicates a number of orthogonal frequency division multiplexing (OFDM) symbols for control, wherein the CFI is based on a bandwidth of the radio downlink. 
     
     
         25 . The method of  claim 22 , wherein the first and second error rates are block error rates. 
     
     
         26 . The method of  claim 25 , further comprising:
 combining the block error rate of the control channel with the block error rate of the indicator channel to generate a combined block error rate, wherein the comparing is performed using the combined block error rate.   
     
     
         27 . The method of claim  1 , wherein the estimating further comprises:
 averaging the quality metric over a period of time to generate an average quality metric, wherein the comparing is based on the average quality metric.   
     
     
         28 . The method of  claim 27 , wherein the period of time is 200 milliseconds when comparing to the first threshold. 
     
     
         29 . The method of  claim 27 , wherein the period of time is 100 milliseconds when comparing to the second threshold. 
     
     
         30 . The method of  claim 21 , further comprising:
 reporting when the quality metric indicates the radio downlink cannot be reliably received to an upper level communication layer of the subscriber station.   
     
     
         31 . A wireless communication device, comprising:
 a receiver receiving reference symbols; and   a processor coupled to the receiver, wherein the processor is configured to:
 estimate a quality metric of the radio downlink based on the reference symbols; 
 compare the quality metric of the radio downlink to a first threshold, wherein the first threshold corresponds to a value of the quality metric at which the radio downlink cannot be reliably received by the subscriber station; and 
 compare the quality metric of the radio downlink to a second threshold, wherein the second threshold corresponds to a value of the quality metric indicating the subscriber station is in synchronization with a base station transmitting the reference symbols. 
   
     
     
         32 . The wireless communication device of  claim 31 , wherein the quality metric is used to estimate a first error rate for a control channel and a second error rate for an indicator channel. 
     
     
         33 . The wireless communication device of  claim 32 , wherein the control channel is a physical downlink control channel (PDCCH) and the indicator channel is a physical control format indicator channel (PCFICH). 
     
     
         34 . The wireless communication device of  claim 32 , wherein the indicator channel includes a control format indicator (CFI) that indicates a number of orthogonal frequency division multiplexing (OFDM) symbols for control, wherein the CFI is based on a bandwidth of the radio downlink. 
     
     
         35 . The wireless communication device of  claim 32 , wherein the first and second error rates are block error rates. 
     
     
         36 . The wireless communication device of  claim 35 , wherein the processor is further configured to:
 combine the block error rate of the control channel with the block error rate of the indicator channel to generate a combined block error rate, wherein the comparing is performed using the combined block error rate.   
     
     
         37 . The wireless communication device of  claim 31 , wherein the processor is configured to estimate the quality metric by averaging the quality metric over a period of time to generate an average quality metric, wherein the comparing is based on the average quality metric. 
     
     
         38 . The wireless communication device of  claim 37 , wherein the period of time is 200 milliseconds when comparing to the first threshold. 
     
     
         39 . The wireless communication device of  claim 37 , wherein the period of time is 100 milliseconds when comparing to the second threshold. 
     
     
         40 . The wireless communication device of  claim 31 , further configured to:
 report when the quality metric indicates the radio downlink cannot be reliably received to an upper level communication layer of the wireless communication device.