High performance window searcher for cell measurement

Abstract

Disclosed are various embodiments involving a window searcher for cell measurement. A window search is configurable and scalable as to a number of scrambling codes to be searched in parallel over a window span for each scrambling code. A received signal is descrambled. A coherent accumulation is performed on the descrambled received signal at a first subchip resolution to produce a coherent accumulation result. The coherent accumulation result is interpolated to a second subchip resolution. A non-coherent accumulation is performed on the descrambled received signal at the second subchip resolution based at least in part on the interpolated coherent accumulation result.

Therefore, at least the following is claimed: 
     
         1 . A system for cell measurement, comprising:
 a wireless communications device including at least one processor and/or circuit configured to:
 descramble a received signal; 
 perform a coherent accumulation on the descrambled received signal at a first subchip resolution to produce a coherent accumulation result; 
 interpolate the coherent accumulation result to a second subchip resolution; and 
 perform a non-coherent accumulation on the descrambled received signal at the second subchip resolution based at least in part on the interpolated coherent accumulation result. 
   
     
     
         2 . The system of  claim 1 , wherein the received signal corresponds to a wideband code division multiple access (WCDMA) signal. 
     
     
         3 . The system of  claim 1 , wherein the coherent accumulation and the non-coherent accumulation are employed as part of a window search. 
     
     
         4 . The system of  claim 3 , wherein the window search is configurable as to a plurality of scrambling codes i to be searched in parallel over a respective window span L(i) in chips. 
     
     
         5 . The system of  claim 4 , wherein the wireless communications device is further configured to offset each scrambling code i phase by a predetermined number of chips for L(i) chips to cover the respective window span L(i). 
     
     
         6 . The system of  claim 4 , wherein the window search is configurable as to a plurality of transmit antenna and receive antenna pairs (t, r) such that the scrambling codes i are searched in parallel over the respective window span L(i) for each of the transmit antenna and receive antenna pairs (t, r). 
     
     
         7 . The system of  claim 4 , wherein the at least one processor and/or circuit includes a set of M coherent accumulators to perform the coherent accumulation, wherein a scalable subset of the M coherent accumulators are active based at least in part on a number of scrambling codes i to be searched, the respective window spans L(i), a number of receive antennas, and a number of transmit antennas. 
     
     
         8 . The system of  claim 1 , wherein the at least one processor and/or circuit includes a set of M coherent accumulators to perform the coherent accumulation and a set of M*N non-coherent accumulators to perform the non-coherent accumulation, wherein N corresponds to an interpolation factor used in the interpolation. 
     
     
         9 . A method for cell measurement in a wireless communications device, comprising:
 configuring window search logic including M coherent accumulators to perform a window search on a received signal for a set of scrambling codes i, wherein each one of the set of scrambling codes i is to be searched for a respective window span L1(i); and   performing the window search for each of the set of scrambling codes i in parallel in the window search logic, wherein the window search utilizes a scalable number M1 of the coherent accumulators based at least in part on a number of scrambling codes i and the respective window spans L1(i) to be searched, and M1 is less than or equal to M.   
     
     
         10 . The method of  claim 9 , further comprising:
 reconfiguring the window search logic to perform another window search on the received signal for another set of scrambling codes i, wherein each one of the other set of scrambling codes i is to be searched for a respective window span L2(i); and   performing the other window search for each of the other set of scrambling codes i in parallel in the window search logic, wherein the other window search utilizes M2 of the coherent accumulators, M2 is less than or equal to M, and M2 does not equal M1.   
     
     
         11 . The method of  claim 10 , wherein the set of scrambling codes i and the other set of scrambling codes i each have a different number of scrambling codes. 
     
     
         12 . The method of  claim 9 , wherein M1 is less than M, and at least one of the M coherent accumulators is inactive and in a reduced power consumption state during the window search. 
     
     
         13 . The method of  claim 9 , wherein M1 equals M. 
     
     
         14 . The method of  claim 9 , wherein the window search utilizes the scalable number M1 of the coherent accumulators based at least in part on whether transmit diversity is enabled for each respective scrambling code i. 
     
     
         15 . The method of  claim 9 , wherein the window search utilizes the scalable number M1 of the coherent accumulators based at least in part on whether receive diversity is enabled for each respective scrambling code i. 
     
     
         16 . The method of  claim 9 , wherein performing the window search comprises:
 descrambling the received signal;   performing a coherent accumulation on the descrambled received signal at a first subchip resolution to produce a coherent accumulation result;   interpolating the coherent accumulation result to a second subchip resolution; and   performing a non-coherent accumulation on the descrambled received signal at the second subchip resolution based at least in part on the interpolated coherent accumulation result.   
     
     
         17 . The method of  claim 16 , wherein the window search logic includes a set of N*M non-coherent accumulators, N is based at least in part on an interpolation factor relating the first subchip resolution to the second subchip resolution, and N is greater than 1. 
     
     
         18 . A system for cell measurement, the system comprising:
 a wireless communications device including at least one processor and/or circuit configured to:
 perform a window search for each of a set of scrambling codes i in parallel, wherein the window search utilizes a configurable number M1 of a set of M coherent accumulators based at least in part on a number of scrambling codes i and a respective window span L1(i) for each scrambling code i to be searched, and M1 is less than or equal to M, the window search producing a respective set of energy results; and 
 sort the respective set of energy results for each scrambling code i based at least in part on a selected sorting approach, the selected sorting approach being selected from per-receive-antenna-based sorting or per-receive-antenna-pair-based sorting. 
   
     
     
         19 . The system of  claim 18 , wherein the at least one processor and/or circuit is further configured to:
 report the respective sorted set of energy results for each scrambling code i based at least in part on a selected reporting approach; and   wherein:
 when the selected sorting approach is per-receive-antenna-based sorting, the selected reporting approach is per-receive-antenna-based reporting; and 
 when the selected sorting approach is per-receive-antenna-pair-based sorting, the selected reporting approach is selected from per-receive-antenna-based reporting or per-receive-antenna-pair-based reporting. 
   
     
     
         20 . The system of  claim 18 , wherein the at least one processor and/or circuit is further configured to disable one of a plurality of receive antenna paths for the window search in response to determining that a signal strength associated with the one of the receive antenna paths meets a threshold.