Method and apparatus for initial acquisition and cell search for an ofdma system

Abstract

A method and apparatus is provided for transmitting an orthogonal frequency domain multiple access (OFDMA) signal including a synchronization channel signal transmitted within a localized portion of a bandwidth of the OFDMA signal, the synchronization channel signal having predetermined time domain symmetry within the localized portion of the bandwidth and including information for providing at least partial cell identification information. The synchronization channel signal enables an initial acquisition and cell search method with low computational load which provides OFDMA symbol timing detection and frequency error detection and frame boundary detection and cell specific information detection in an OFDMA system supporting multiple system bandwidths, both synchronized and un-synchronized systems, a large cell index and an OFDMA symbol structure with both short and long cyclic prefix length.

What is claimed is: 
     
         1 . A method for use in a wireless communication receiver for receiving an orthogonal frequency domain multiple access (OFDMA) signal comprising a plurality of resource blocks, the wireless communication receiver including a controller and receiver circuitry, the method comprising the steps of:
 receiving, by the receiver circuitry, the OFDMA signal comprising a first guard band, a synchronization channel signal, and a second guard band, wherein the synchronization channel signal is between the first guard band and the second guard band, wherein the first guard band and the second guard band span respective first and second bandwidths of the OFDMA signal, and wherein no signal is transmitted on the first guard band and the second guard band;   the controller detecting at least a portion of a first set of the plurality of resource blocks within the OFDMA signal, wherein the first set of the plurality of resource blocks comprises the synchronization channel signal, and the synchronization channel signal spans a bandwidth less than a bandwidth spanned by the first set of the plurality of resource blocks; and   the controller detecting the synchronization channel signal within the first set of the plurality of resource blocks.   
     
     
         2 . The method of  claim 1 , wherein the step of detecting the synchronization channel signal comprises the step of the controller deriving, based on the synchronization channel signal, at least partial cell identification information associated with a base station transmitting the OFDMA signal. 
     
     
         3 . The method of  claim 1 , wherein the controller detects multiple occurrences of the synchronization channel signal within the first set of resource blocks, and the method further comprises:
 the controller further deriving the synchronization channel signal by averaging the multiple occurrences of the synchronization channel signal.   
     
     
         4 . The method of  claim 1 , wherein the synchronization channel signal comprises one or more synchronization channel signal sequence elements, and wherein the step of detecting the synchronization channel signal comprises the step of:
 the controller detecting the synchronization channel signal in response to detecting a general chirp like (GCL) sequence of the one or more synchronization channel sequence elements.   
     
     
         5 . The method of  claim 4 , wherein the GCL sequence has an index associated therewith, and wherein the step of detecting the synchronization channel signal comprises the step of detecting the synchronization channel signal in response to detecting the index of the GCL sequence. 
     
     
         6 . The method of  claim 5 , wherein the step of detecting the synchronization channel signal comprises the step of deriving at least partial cell identification information associated with a base station transmitting the OFDMA signal in response to the index of the GCL sequence. 
     
     
         7 . The method of  claim 6 , wherein the step of detecting the synchronization channel signal comprises the step of deriving the at least partial cell identification information comprising unique cell identification information identifying the base station within a group of base stations in response to the index of the GCL sequence. 
     
     
         8 . The method of  claim 1 , wherein the synchronization channel signal comprises one or more synchronization channel signal sequence elements, and wherein the step of detecting the synchronization channel signal comprises the step of the controller deriving at least partial cell identification information associated with a base station transmitting the OFDMA signal in response to detecting an amount of cyclic shift of a cyclically shifted maximal length binary m-sequence of the one or more synchronization channel sequence elements. 
     
     
         9 . The method of  claim 1 , wherein the synchronization channel signal comprises one or more synchronization channel signal sequence elements, and wherein the step of detecting the synchronization channel signal comprises the step of deriving at least partial cell identification information comprising cell group identification information identifying a cell group comprising one or more base stations including the base station transmitting the OFDMA signal in response to detecting an amount of cyclic shift of a cyclically shifted maximal length binary m-sequence of the one or more synchronization channel sequence elements. 
     
     
         10 . The method of  claim 1 , wherein the first set of the plurality of resource blocks further comprises the first guard band, the synchronization channel signal, and the second guard band. 
     
     
         11 . The method of  claim 1 , wherein the step of detecting the synchronization channel signal comprises the step of detecting the synchronization channel signal within at least a substantial portion of a center  1 . 25  MHz of the portion of the OFDMA signal. 
     
     
         12 . The method of  claim 1 , further comprising:
 the controller detecting at least a portion of a second set of the plurality of resource blocks within the OFDMA signal, wherein a data signal is within the second set of the plurality of resource blocks, and wherein the second set of the plurality of resource blocks is different from the first set of the plurality of resource blocks; and   the controller decoding the data signal from within the second set of the plurality of resource blocks.   
     
     
         13 . A wireless communication receiver for receiving an orthogonal frequency domain multiple access (OFDMA) signal comprising a plurality of resource blocks, the wireless communication receiver comprising:
 receiver circuitry receiving the OFDMA signal comprising a first guard band, a synchronization channel signal, and a second guard band, wherein the synchronization channel signal is between the first guard band and the second guard band, wherein the first guard band and the second guard band span respective first and second bandwidths of the OFDMA signal, and wherein no signal is transmitted on the first guard band and the second guard band; and   a controller coupled to the receiver circuitry and detecting at least a portion of a first set of the plurality of resource blocks within the OFDMA signal, wherein the first set of the plurality of resource blocks spans a first bandwidth and comprises the synchronization channel signal, and the synchronization channel signal spans a second bandwidth less than the first bandwidth, the controller further detecting the synchronization channel signal within the first set of the plurality of resource blocks.   
     
     
         14 . The wireless communication receiver of  claim 13 , wherein the controller derives at least partial cell identification information in response to the synchronization channel signal, wherein the at least partial cell identification information is associated with a base station transmitting the OFDMA signal. 
     
     
         15 . The wireless communication receiver of  claim 13 , wherein:
 the controller detects at least a portion of a second set of the plurality of resource blocks within the OFDMA signal, and wherein a data signal is within a bandwidth spanned by the second set of the plurality of resource blocks, and wherein the second set of the plurality of resource blocks is different from the first set of the plurality of resource blocks, the controller further decoding the data signal from within the second set of the plurality of resource blocks.   
     
     
         16 . The wireless communication receiver of  claim 13 , wherein the controller detects multiple occurrences of the synchronization channel signal within the first set of the plurality of resource blocks and derives the synchronization channel signal by averaging the multiple occurrences of the synchronization channel signal. 
     
     
         17 . The wireless communication receiver of  claim 13 , wherein the synchronization channel signal comprises one or more synchronization channel signal sequence elements, the controller detects a general chirp like (GCL) sequence of the one or more synchronization channel sequence elements, the GCL sequence has an index associated therewith, and the controller detects the synchronization channel signal in response to detecting the index of the GCL sequence. 
     
     
         18 . The wireless communication receiver of  claim 17 , wherein the controller derives at least partial cell identification information associated with a base station transmitting the OFDMA signal in response to the index of the GCL sequence. 
     
     
         19 . The wireless communication receiver of  claim 18 , wherein the controller derives the at least partial cell identification information comprising unique cell identification information identifying the base station within a group of base stations in response to the index of the GCL sequence. 
     
     
         20 . The wireless communication receiver of  claim 13 , wherein the synchronization channel signal comprises one or more synchronization channel signal sequence elements, and wherein the controller derives at least partial cell identification information associated with a base station transmitting the OFDMA signal in response to detecting an amount of cyclic shift of a cyclically shifted maximal length binary m-sequence of the one or more synchronization channel sequence elements. 
     
     
         21 . The wireless communication receiver of  claim 13 , wherein the synchronization channel signal comprises one or more synchronization channel signal sequence elements, and wherein the controller derives at least partial cell identification information comprising cell group identification information identifying a cell group comprising one or more base stations including a base station transmitting the OFDMA signal in response to detecting an amount of cyclic shift of a cyclically shifted maximal length binary m-sequence of the one or more synchronization channel sequence elements. 
     
     
         22 . The wireless communication receiver of  claim 13 , wherein the first set of the plurality of resource blocks further comprises the first guard band, the synchronization channel signal, and the second guard band.