Title of Invention	A METHOD AND SYSTEM FOR OPTIMAL GROUP SEARCH FOR GATED PILOT ACQUISITION IN WIRELESS SYSTEM
Abstract	The present invention is related to gated pilot wireless system, where initially the pilot will be acquired to get the reference for the further communication between mobile terminal and the access point of the network system. More particularly, this invention relates to a method and system for optimal group search for gated pilot acquisition. This invention explains a system and method for optimal group search for gated pilot acquisition comprising the steps of configuring initially one or more PN offsets for the coarse acquisition search by the controller; performance the search over the collected data samples for the configured PN offsets by the searcher; providing the peaks found in the coarse acquisition search to the controller by the said searcher; checking the valid peaks for the fine acquisition search by the said controller by group search; providing the peaks found in the fine acquisition search to the controller by the said searcher; and searching the peaks found in the coarse acquisition along with their adjacent PN offsets at the same position of the peak found in the coarse acquisition for the estimation of the pilot.

Title of Invention

A METHOD AND SYSTEM FOR OPTIMAL GROUP SEARCH FOR GATED PILOT ACQUISITION IN WIRELESS SYSTEM

Abstract

The present invention is related to gated pilot wireless system, where initially the pilot will be acquired to get the reference for the further communication between mobile terminal and the access point of the network system. More particularly, this invention relates to a method and system for optimal group search for gated pilot acquisition. This invention explains a system and method for optimal group search for gated pilot acquisition comprising the steps of configuring initially one or more PN offsets for the coarse acquisition search by the controller; performance the search over the collected data samples for the configured PN offsets by the searcher; providing the peaks found in the coarse acquisition search to the controller by the said searcher; checking the valid peaks for the fine acquisition search by the said controller by group search; providing the peaks found in the fine acquisition search to the controller by the said searcher; and searching the peaks found in the coarse acquisition along with their adjacent PN offsets at the same position of the peak found in the coarse acquisition for the estimation of the pilot.

Full Text	> ' FIELD OF THE INVENTION The present invention is related to gated pilot wireless system, where initially the pilot will be acquired to get the reference for the further communication between mobile terminal and the access point of the network system. More particularly, this invention relates to a method and system for optimal group search for gated pilot acquisition in wireless system. DESCRIPTION OF RELATED ART In a CDMA communication system the pilot is transmitted in a known format to assist the mobile station's receiver, which will be used for the synchronization of timing and frequency with the transmission source, coherent demodulation and to estimate the link quality of the various available access points of the access network. In a HRPD CDMA system the pilot will be transmitted at maximum power periodically for short durations and off for the rest of the time (gated mode), which allows terminal to estimate link quality more accurately with less time. The initial gated pilot search for acquiring the link is more complex than the continuous pilot since it is transmitted at fixed intervals of the time. Incase of the continuous pilot which is transmitted all the time and it is present in any time window, where the timing reference is the only unknown factor. In the gated pilot since the transmission is not continuous the acquisition may fail if the search window falls in the when pilot is off. The pilot acquisition search at access terminal may be done in the different stages. The first stage initial search finds the pilot with rough estimations which will be fine searched in the next stage of the search, where the inputs for the fine search are results from the first stage search. LIMITATIONS The acquisition fine search is usually performed by the group search, by configuring the more than one search at a time in the searcher by the controller. The prior art always takes 3 group searches to finish the fine search before it declares the pilot acquisition success, which results the more processing requirement for the controller. SUMMARY OF THE INVENTION The gated pilot acquisition search process held in two stages, those are coarse and fine acquisition search. In the coarse acquisition search the PN offset's timing offset will be estimated roughly by searching through all possible hypotheses for the window of the collected samples. The peaks found in the coarse acquisition will be searched along with their adjacent PN offsets at the same position of the peak found in the coarse acquisition for better estimation of the pilot. The total number of the peaks to be searched for the fine acquisition search is the number of peaks found in the coarse acquisition and its two virtual peaks. The virtual peaks significance is explained in the detailed description. Once the peaks are available from coarse acquisition and generated virtual peaks then fine acquisition search will be configured in the searcher as a group of peaks, the searcher searches the all peaks configured in group and gives the results to the controller, which is called as group search. The total number of group searches required for fine acquisition search depends on the number of the peaks found in the coarse acquisition search. The proposed idea takes less number of group searches in less multi path and good signal environment compared to the prior art's 3 (fixed always) number of fine acquisition group searches. Accordingly, this invention explains a method for optimal group search for gated pilot acquisition in a wireless system comprising the steps of: (a) configuring initially one or more PN offsets for the coarse acquisition search by the controller; (b) performing the search over the collected data samples for the configured PN offsets by the searcher; (c) providing the peaks found in the coarse acquisition search to the controller by the said searcher; (d) checking the valid peaks for the fine acquisition search by the said controller by group search; (e) providing the peaks found in the fine acquisition search to the controller by the said searcher; and (f) searching the peaks found in the coarse acquisition along with their adjacent PN offsets at the same position of the peak found in the coarse acquisition for the estimation of the pilot. If there are no valid peaks found in the coarse acquisition search then the same procedure is repeated for the rest of the PN offsets. Once valid peaks found from the coarse acquisition, then the controller goes for the fine acquisition search. The fine acquisition search is performed by the group search method, and the number of group searches required for the fine acquisition search is given by GRP_CNT = ((3 x PEAK_CNT-1) + GRP_SIZE) / GRP_SIZE Where, GRP_CNT is number of group searches required for the fine acquisition search, PEAK_CNT - peaks found in the initial coarse acquisition search and GRP_SIZE - Maximum number of peaks can be configured for the search in a group. The controller configures group search with the maximum number of peaks that can be configured in a group search. After every group search is completed the controller sorts out the best peak found in the group fine acquisition search, where the best peak is compared to the candidate peak energy which is found in the previous group fine acquisition searches and makes the strong peak among them as the candidate peak. The controller configures the pending peaks for a next group search and once all peaks are done for the fine acquisition search the controller checks if the best candidate peak is above the threshold for the fine acquisition or not. If the best candidate peak is above the threshold then the controller proceeds for frequency pull in state to declare the acquisition result. If the best candidate peak after all group searches falls below the threshold level, then the controller proceeds for the coarse acquisition search with the different PN offsets, if there are PN offsets pending to be searched and if there is no pending PN offset to search, then controller declares the acquisition failure. The number of the group searches done for fine acquisition search always depends on the number of peaks found in the initial coarse acquisition search. Two virtual peaks, the left adjacent PN offset's peak and the right adjacent PN offset's peak at the relative position of the actual peak are generated. The position parameter of the each virtual peak is calculated by the position parameter of the actual peak and the controller makes a list of peaks for fine acquisition group search which includes actual peaks found in the initial search and the virtual peaks generated and sorts it in the order of the peaks position over the sample data buffer. Accordingly, this invention further explains a system for optimal group search for gated pilot acquisition in a wireless system comprising: (a) means for configuring initially one or more PN offsets for the coarse acquisition search by the controller; (b) means for performing the search over the collected data samples for the configured PN offsets by the searcher; (c) means for providing the peaks found in the coarse acquisition search to the controller by the said searcher; (d) means for checking the valid peaks for the fine acquisition search by the said controller by group search; (e) means for providing the peaks found in the fine acquisition search to the controller by the said searcher; and (f) means for searching the peaks found in the coarse acquisition along with their adjacent PN offsets at the same position of the peak found in the coarse acquisition for the estimation of the pilot. The other objects, features and advantages of the present invention will be apparent from ensuing the detailed description of the invention taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1 shows the gated pilot transmission for the HRPD CDMA system. Figure 2 is the diagram of the pilot symbol alignment in the time space and the PN space. Figure 3 is the example diagram of the coarse acquisition search results. Figure 4 shows the pilot symbol overlap over 32 chips in the PN space between the adjacent PN offsets. Figure 5 shows the configuration of the fine acquisition group searches of the prior art. Figure 6 shows the first step of the fine acquisition search, generation of the virtual peaks. Figure 7 is the diagram of the generating virtual peaks and making the groups of peaks for the fine acquisition search to be followed of the present invention. Figure 8 is the diagram depicts the fine acquisition search procedure after controller gets valid peaks from coarse acquisition search. DETAILED DESCRIPTION OF THE INVENTION The preferred embodiments of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail. In a HRPD CDMA wireless communication system that provides communication for number of cells through the access nodes also called as the base stations. The each cell of the system further divided into the sector for the better coverage of the area and to handle the more number of access terminals. The each sector supports the various number of the access terminals also called as the mobile stations. The transmission from each sector will be differentiated through allocating the different PN offsets to different sectors, here onwards the sector and PN offset refers one to the other. Figure 1 shows the gated pilot transmission for the HRPD CDMA system, the pilot will be transmitted on the forward link at the middle of the each half slot (1024 chips) for 96 chips duration with maximum power level of the sector, rest of the duration user data will be transmitted. The known sequence of the data will be transmitted as the pilot symbol; usually it is sequence of all zeros. The Figure 2 is the diagram of the pilot symbol alignment in the time space and the PN space. The pilot symbol transmission from each PN offset is aligned in time space in other words, the pilot symbol from each PN offset transmitted are synchronized with the time. The pilot symbol from the each PN offset are not aligned in PN space, since each PN offset is spaced 64 chips in PN space from the adjacent PN offsets which takes care of the interference between the transmissions from the all PN offsets at the access terminal. The Figure 3 is the example diagram of the coarse acquisition search results. The controller at access terminal configures set of the PN offsets for coarse acquisition search in the searcher. The searcher of the receiver searches the pilot symbols of the configured PN offsets over the collected data samples; if the searcher gets the any pilot symbol peaks over its search then it passes the peaks found to the controller. The controller is responsible to sort the peaks found in the coarse acquisition and configure the same for fine acquisition for better estimation of the pilot symbol presence over the results of the coarse acquisition. In the fine acquisition search the controller configures the pilot symbol peaks found for PN offsets configured in coarse acquisition search and the adjacent PN offset of the configured PN offset, the reason for inclusion of adjacent PN offset is explained in the below. The total number of the peaks to be configured for the fine acquisition is three times to the peaks found in the coarse acquisition search. The searcher searches the all peaks configured for the group search simultaneously and gives the search results back to controller for the next stage of the acquisition. The number of peaks can be configured for each group search is depends on the hardware implementation. The Figure 4 shows the pilot symbol overlap in the PN space between the adjacent PN offsets. The PN offset is spaced 64 chips from its two adjacent PN offsets over the same short PN sequence and all PN offsets transmit pilot symbols at the same instance of the time because of this, there will be 32 chips overlap of the pilot symbol between the adjacent PN offsets in the PN space. This causes the ambiguity while searching for the pilot symbol at the access terminal. The access terminal may detect the pilot symbol peak of adjacent offset on the offset which is configured for coarse acquisition search due to above said 32 chips overlap in the PN space. This ambiguity can be over come by performing the fine acquisition search for the adjacent offset's pilot symbol of the initially configured PN offset on the same collected data buffer. This search gives the fair chances to get the actual PN offset's pilot symbol peak with better energy level than the adjacent PN offsets pilot symbol peak. Figure 5 shows the configuration of the fine acquisition group searches of the prior art. In the prior art the fine acquisition search will be done in the 3 group searches, which is fixed irrespective of the number of peaks found in the coarse acquisition search. The first group search will be configured for the peaks found for the PN offsets configured in the coarse acquisition search, the second group search is configured for the peaks of the left adjacent PN offsets of the PN offsets which are configured for the coarse acquisition search and the final search will be configured for the peaks of the right adjacent PN offsets of the PN offsets which are configured for the coarse acquisition search. In a good signal environment it is possible to get the less number of coarse acquisition peaks with good energy level than the maximum number peaks can be configured for a group search. In this kind of scenarios the prior art uses 3 group searches to finish the fine acquisition search, but each group search will be configured with less number of peaks than the supported maximum number of the peaks per group search. The present invention proposes a method to reduce the number of group searches in the signal environment where less number of the peaks found in the initial coarse acquisition search. In the proposed invention the number of group searches depends on the number of peaks found in the coarse acquisition search. The reduced number of the group searches helps to minimize the mean acquisition time by avoiding the excessive group search configurations. The maximum number of group searches required for the proposed invention required are 3 which is same as the prior art takes always. Figure 6 shows the first step of the fine acquisition search, generation of the virtual peaks. The controller prepares the list of the peaks found from the coarse acquisition search which are above the threshold level. The virtual peaks are the peaks to be searched for the fine acquisition search; there will be two virtual peaks corresponding to the each peak qualified for the fine acquisition search. They are left adjacent PN offset's peak and the right adjacent PN offset's peak at the relative position of the actual peak. The position parameter of the each virtual peak will be calculated by the position parameter of the actual peak, by putting 64 chips away from it. Since, the PN offsets are spaced at 64chips. Then controller makes a list of peaks for fine acquisition group search which includes actual peaks found in the initial search and the virtual peaks generated and sorts it in the order of the peaks position over the sample data buffer. Figures 7 and 8 are the diagrams of the fine acquisition search method of the present invention. The controller initially configures one or more PN offsets for the coarse acquisition search. The searcher performs the search over the collected data samples for the configured PN offsets and gives the peaks found in the search to the controller. Then the controller checks the valid peaks for the fine acquisition search. If there are no valid peaks found in the search then the same procedure will be repeated for the rest of the PN offsets. Once valid peaks found from the coarse acquisition then the controller goes for the fine acquisition search. The fine acquisition search will be performed be the group search method, the number of group searches required for the fine acquisition search is GRP_CNT = ((3 x PEAK_CNT-1) + GRP_SIZE) / GRP_SIZE Where, GRP_CNT - number of group searches required for the fine acquisition search. PEAK_CNT - peaks found in the initial coarse acquisition search. GRP_SIZE - Maximum number of peaks can be configured for the search in a group. The controller configures group search with the maximum number of peaks that can be configured in a group search. After every group search is completed the controller sorts out the best peak found in the group fine acquisition search, the best peak will be compared to the candidate peak energy which is found in the previous fine acquisition group searches and makes the strong peak among them as the candidate peak. Then controller continues to configure the pending peaks for next group search. Once all peaks are done for the fine acquisition search the controller checks the best candidate peak is above the threshold for the fine acquisition or not. If the best candidate peak is above the threshold then the controller proceeds for frequency pull in state to declare the acquisition result. If the best candidate peak after all group searches falls below the threshold level, then the controller proceeds for the coarse acquisition search with the different PN offsets, if there are PN offsets pending to be searched. If there is no pending PN offset to search, then controller declares the acquisition failure. In the current invention the number of the group searches done for fine acquisition search always depends on the number of peaks found in the initial coarse acquisition search. This method reduces the number of group searches significantly in the environment where searcher gets less number of peaks in the initial search which helps to improve the mean acquisition time at the access terminal. Advantages of the Invention The proposed invention is advantageous in the less multi path and good signal environment to reduce the mean acquisition time of the gated pilot acquisition time. It will also be obvious to those skilled in the art that other control methods and apparatuses can be derived from the combinations of the various methods and apparatuses of the present invention as taught by the description and the accompanying drawings and these shall also be considered within the scope of the present invention. Further, description of such combinations and variations is therefore omitted above. It should also be noted that the host for storing the applications include but not limited to a microchip, microprocessor, handheld communication device, computer, rendering device or a multi function device. Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are possible and are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom. N GLOSSARY OF TERMS AND DEFINITIONS THEREOF 1. PN Offset - is one of the 512 codes used to differentiate sectors for communication with the mobile units The 512 points within the short PN sequence have been selected as the PN offsets (from 0-511) each 64 chips apart. Each base station uses a different point in the sequence to create a unique PN offset that can identify the base station sector. 2. PNJ3ROUP - the group of the PN offsets which will be configured for the coarse acquisition search at the same instance. 3. Full slot - the 2048 chips which lasts for 1,66msec. Each full slot contains 2 pilot symbols at the middle of the each half slot. 4. Px - the coarse acquisition peak with number x. 5. Pvpxy - the yth virtual peak of the coarse acquisition peak Px. 6. INDEX - the position of the peak from starting point of the collected data samples of the acquisition search (coarse or fine). 7. Grp #x- fine group search with group search number x. 8. PEAK_CNT - the number of valid peaks found in the coarse acquisition search. 9. GRP_CNT - the number of group searches required for the fine acquisition search. 10. CAND PEAK - the best peak from all fine group acquisition searches, which is the candidate peak to declare the acquisition success. 11. CAND_PEAK_ENG - the energy of the CAND_PEAK. WE CLAIM 1. A method for optimal group search for gated pilot acquisition in a wireless system comprising the steps of: (a) configuring initially one or more PN offsets for the coarse acquisition search by the controller; (b) performing the search over the collected data samples for the configured PN offsets by the searcher; (c) providing the peaks found in the coarse acquisition search to the controller by the said searcher; (d) checking the valid peaks for the fine acquisition search by the said controller by group search; (e) providing the peaks found in the fine acquisition search to the controller by the said searcher; and (f) searching the peaks found in the coarse acquisition along with their adjacent PN offsets at the same position of the peak found in the coarse acquisition for the estimation of the pilot. 2. A method as claimed in claim 1 wherein if there are no valid peaks found in the coarse acquisition search then the same procedure is repeated for the rest of the PN offsets. 3. A method as claimed in claim 1 wherein once valid peaks found from the coarse acquisition, then the controller goes for the fine acquisition search. 4. A method as claimed in claim 1 wherein the fine acquisition search is performed by the group search method, and the number of group searches required for the fine acquisition search is given by GRP_CNT = ((3 x PEAK_CNT-1) + GRP_SIZE) / GRP_SIZE where, GRP_CNT is number of group searches required for the fine acquisition search, PEAK_CNT - peaks found in the initial coarse acquisition search and GRP_SIZE - Maximum number of peaks can be configured for the search in a group. 5. A method as claimed in claim 1 wherein the controller configures group search with the maximum number of peaks that can be configured in a group search. 6. A method as claimed in claim 1 wherein after every group search is completed the controller sorts out the best peak found in the group fine acquisition search, where the best peak is compared to the candidate peak energy which is found in the previous group fine acquisition searches and makes the strong peak among them as the candidate peak. 7. A method as claimed in claim 1 wherein the controller configure the pending peaks for a next group search and once all peaks are done for the fine acquisition search the controller checks if the best candidate peak is above the threshold for the fine acquisition or not. 8. A method as claimed in claim 1 wherein if the best candidate peak is above the threshold then the controller proceeds for frequency pull in state to declare the acquisition result. 9. A method as claimed in claim 1 wherein if the best candidate peak after all group searches falls below the threshold level, then the controller proceeds for the coarse acquisition search with the different PN offsets if there are PN offsets pending to be searched and if there is no pending PN offset to search, then controller declares the acquisition failure. 10. A method as claimed in claim 1 wherein the number of the group searches done for fine acquisition search always depends on the number of peaks found in the initial coarse acquisition search. 11. A method as claimed in claim 1 wherein, two virtual peaks, the left adjacent PN offset's peak and the right adjacent PN offset's peak at the relative position of the actual peak are generated in the fine acquisition search. 12. A method as claimed in claim 1 wherein the position parameter of the each virtual peak is calculated by the position parameter of the actual peak and the controller makes a list of peaks for fine acquisition group search which includes actual peaks found in the initial search and the virtual peaks generated and sorts it in the order of the peaks position over the sample data buffer. 13. A system for optimal group search for gated pilot acquisition in a wireless system comprising: (a) means for configuring initially one or more PN offsets for the coarse acquisition search by the controller; (b) means for performing the search over the collected data samples for the configured PN offsets by the searcher; (c) means for providing the peaks found in the coarse acquisition search to the controller by the said searcher; (d) means for checking the valid peaks for the fine acquisition search by the said controller by group search; (e) means for providing the peaks found in the fine acquisition search to the controller by the said searcher; and (f) means for searching the peaks found in the coarse acquisition along with their adjacent PN offsets at the same position of the peak found in the coarse acquisition for the estimation of the pilot. 14. A system as claimed in claim 13 wherein if there are no valid peaks found in the coarse acquisition search then the same procedure is repeated for the rest of the PN offsets. 15. A system as claimed in claim 13 wherein once valid peaks found from the coarse acquisition, then the controller goes for the fine acquisition search. 16. A system as claimed in claim 13 wherein the fine acquisition search is performed by the group search method, and the number of group searches required for the fine acquisition search is given by GRP CNT = ((3 x PEAK_CNT-1) + GRP_SIZE) / GRP_SIZE where, GRP_CNT is number of group searches required for the fine acquisition search, PEAK_CNT - peaks found in the initial coarse acquisition search and GRP_SIZE - Maximum number of peaks can be configured for the search in a group. 17. A system as claimed in claim 13 wherein the controller configures group search with the maximum number of peaks that is configured in a group search. 18. A system as claimed in claim 13 wherein after every group search is completed the controller sorts out the best peak found in the group fine acquisition search, where the best peak is compared to the candidate peak energy which is found in the previous group fine acquisition searches and makes the strong peak among them as the candidate peak. 19. A system as claimed in claim 13 wherein the controller configure the pending peaks for a next group search and once all peaks are done for the fine acquisition search the controller checks if the best candidate peak is above the threshold for the fine acquisition or not. 20. A system as claimed in claim 13 wherein if the best candidate peak is above the threshold then the controller proceeds for frequency pull in state to declare the acquisition result. 21. A system as claimed in claim 13 wherein if the best candidate peak after all group searches falls below the threshold level, then the controller proceeds for the coarse acquisition search with the different PN offsets, if there are PN offsets pending to be searched and if there is no pending PN offset to search, then controller declares the acquisition failure. 22. A system as claimed in claim 13 wherein the number of the group searches done for fine acquisition search always depends on the number of peaks found in the initial coarse acquisition search. 23. A method as claimed in claim 13 wherein, two virtual peaks, the left adjacent PN offset's peak and the right adjacent PN offset's peak at the relative position of the actual peak are generated in the fine acquisition search. 24. A system as claimed in claim 13 wherein the position parameter of the each virtual peak is calculated by the position parameter of the actual peak and the controller makes a list of peaks for fine acquisition group search which includes actual peaks found in the initial search and the virtual peaks generated and sorts it in the order of the peaks position over the sample data buffer. 25. A method for optimal group search for gated pilot acquisition substantially described particularly with reference to the accompanying drawings. 26. A system for optimal group search for gated pilot acquisition substantially described particularly with reference to the accompanying drawings.

Full Text

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FIELD OF THE INVENTION
The present invention is related to gated pilot wireless system, where initially the pilot will be acquired to get the reference for the further communication between mobile terminal and the access point of the network system. More particularly, this invention relates to a method and system for optimal group search for gated pilot acquisition in wireless system.
DESCRIPTION OF RELATED ART
In a CDMA communication system the pilot is transmitted in a known format to assist the mobile station's receiver, which will be used for the synchronization of timing and frequency with the transmission source, coherent demodulation and to estimate the link quality of the various available access points of the access network. In a HRPD CDMA system the pilot will be transmitted at maximum power periodically for short durations and off for the rest of the time (gated mode), which allows terminal to estimate link quality more accurately with less time. The initial gated pilot search for acquiring the link is more complex than the continuous pilot since it is transmitted at fixed intervals of the time. Incase of the continuous pilot which is transmitted all the time and it is present in any time window, where the timing reference is the only unknown factor. In the gated pilot since the transmission is not continuous the acquisition may fail if the search window falls in the when pilot is off. The pilot acquisition search at access terminal may be done in the different stages. The first stage initial search finds the pilot with rough estimations which will
be fine searched in the next stage of the search, where the inputs for the fine search are results from the first stage search.
LIMITATIONS
The acquisition fine search is usually performed by the group search, by configuring the more than one search at a time in the searcher by the controller. The prior art always takes 3 group searches to finish the fine search before it declares the pilot acquisition success, which results the more processing requirement for the controller.
SUMMARY OF THE INVENTION
The gated pilot acquisition search process held in two stages, those are coarse and fine acquisition search. In the coarse acquisition search the PN offset's timing offset will be estimated roughly by searching through all possible hypotheses for the window of the collected samples. The peaks found in the coarse acquisition will be searched along with their adjacent PN offsets at the same position of the peak found in the coarse acquisition for better estimation of the pilot. The total number of the peaks to be searched for the fine acquisition search is the number of peaks found in the coarse acquisition and its two virtual peaks. The virtual peaks significance is explained in the detailed description. Once the peaks are available from coarse acquisition and generated virtual peaks then fine acquisition search will be configured in the searcher as a group of peaks, the searcher searches the all
peaks configured in group and gives the results to the controller, which is called as group search. The total number of group searches required for fine acquisition search depends on the number of the peaks found in the coarse acquisition search. The proposed idea takes less number of group searches in less multi path and good signal environment compared to the prior art's 3 (fixed always) number of fine acquisition group searches.
Accordingly, this invention explains a method for optimal group search for gated pilot acquisition in a wireless system comprising the steps of:
(a) configuring initially one or more PN offsets for the coarse acquisition search by the controller;
(b) performing the search over the collected data samples for the configured PN offsets by the searcher;
(c) providing the peaks found in the coarse acquisition search to the controller by the said searcher;
(d) checking the valid peaks for the fine acquisition search by the said controller by group search;
(e) providing the peaks found in the fine acquisition search to the controller by the said searcher; and
(f) searching the peaks found in the coarse acquisition along with their adjacent PN offsets at the same position of the peak found in the coarse acquisition for the estimation of the pilot.
If there are no valid peaks found in the coarse acquisition search then the same procedure is repeated for the rest of the PN offsets. Once valid peaks found from the coarse acquisition, then the controller goes for the fine acquisition search. The fine acquisition search is performed by the group search method, and the number of group searches required for the fine acquisition search is given by
GRP_CNT = ((3 x PEAK_CNT-1) + GRP_SIZE) / GRP_SIZE Where, GRP_CNT is number of group searches required for the fine acquisition search, PEAK_CNT - peaks found in the initial coarse acquisition search and GRP_SIZE - Maximum number of peaks can be configured for the search in a group.
The controller configures group search with the maximum number of peaks that can be configured in a group search. After every group search is completed the controller sorts out the best peak found in the group fine acquisition search, where the best peak is compared to the candidate peak energy which is found in the previous group fine acquisition searches and makes the strong peak among them as the candidate peak. The controller configures the pending peaks for a next group search and once all peaks are done for the fine acquisition search the controller checks if the best candidate peak is above the threshold for the fine acquisition or not. If the best candidate peak is above the threshold then the controller proceeds for frequency pull in state to declare the acquisition result. If the best candidate peak after all group searches falls below the threshold level, then the controller proceeds for the coarse acquisition search with the different PN offsets, if there are PN offsets pending to be searched and if there is no pending PN offset to search, then controller declares the acquisition failure. The number of the
group searches done for fine acquisition search always depends on the number of peaks found in the initial coarse acquisition search. Two virtual peaks, the left adjacent PN offset's peak and the right adjacent PN offset's peak at the relative position of the actual peak are generated. The position parameter of the each virtual peak is calculated by the position parameter of the actual peak and the controller makes a list of peaks for fine acquisition group search which includes actual peaks found in the initial search and the virtual peaks generated and sorts it in the order of the peaks position over the sample data buffer.
Accordingly, this invention further explains a system for optimal group search for gated pilot acquisition in a wireless system comprising:
(a) means for configuring initially one or more PN offsets for the coarse acquisition search by the controller;
(b) means for performing the search over the collected data samples for the configured PN offsets by the searcher;
(c) means for providing the peaks found in the coarse acquisition search to the controller by the said searcher;
(d) means for checking the valid peaks for the fine acquisition search by the said controller by group search;
(e) means for providing the peaks found in the fine acquisition search to the controller by the said searcher; and
(f) means for searching the peaks found in the coarse acquisition along with their adjacent PN offsets at the same position of the peak found in the coarse acquisition for the estimation of the pilot.
The other objects, features and advantages of the present invention will be apparent from ensuing the detailed description of the invention taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1 shows the gated pilot transmission for the HRPD CDMA system. Figure 2 is the diagram of the pilot symbol alignment in the time space and the PN space.
Figure 3 is the example diagram of the coarse acquisition search results. Figure 4 shows the pilot symbol overlap over 32 chips in the PN space between the adjacent PN offsets.
Figure 5 shows the configuration of the fine acquisition group searches of the prior art.
Figure 6 shows the first step of the fine acquisition search, generation of the virtual peaks.
Figure 7 is the diagram of the generating virtual peaks and making the groups of peaks for the fine acquisition search to be followed of the present invention. Figure 8 is the diagram depicts the fine acquisition search procedure after controller gets valid peaks from coarse acquisition search.
DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiments are merely exemplary of the invention, which may be
embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail.
In a HRPD CDMA wireless communication system that provides communication for number of cells through the access nodes also called as the base stations. The each cell of the system further divided into the sector for the better coverage of the area and to handle the more number of access terminals. The each sector supports the various number of the access terminals also called as the mobile stations. The transmission from each sector will be differentiated through allocating the different PN offsets to different sectors, here onwards the sector and PN offset refers one to the other. Figure 1 shows the gated pilot transmission for the HRPD CDMA system, the pilot will be transmitted on the forward link at the middle of the each half slot (1024 chips) for 96 chips duration with maximum power level of the sector, rest of the duration user data will be transmitted. The known sequence of the data will be transmitted as the pilot symbol; usually it is sequence of all zeros.
The Figure 2 is the diagram of the pilot symbol alignment in the time space and the PN space. The pilot symbol transmission from each PN offset is aligned in time space in other words, the pilot symbol from each PN offset transmitted are synchronized with the time. The pilot symbol from the each PN offset are not aligned in PN space, since each PN offset is spaced 64 chips in PN space from the adjacent PN offsets which takes care of the interference between the transmissions from the all PN offsets at the access terminal.
The Figure 3 is the example diagram of the coarse acquisition search results. The controller at access terminal configures set of the PN offsets for coarse acquisition search in the searcher. The searcher of the receiver searches the pilot symbols of the configured PN offsets over the collected data samples; if the searcher gets the any pilot symbol peaks over its search then it passes the peaks found to the controller. The controller is responsible to sort the peaks found in the coarse acquisition and configure the same for fine acquisition for better estimation of the pilot symbol presence over the results of the coarse acquisition. In the fine acquisition search the controller configures the pilot symbol peaks found for PN offsets configured in coarse acquisition search and the adjacent PN offset of the configured PN offset, the reason for inclusion of adjacent PN offset is explained in the below. The total number of the peaks to be configured for the fine acquisition is three times to the peaks found in the coarse acquisition search. The searcher searches the all peaks configured for the group search simultaneously and gives the search results back to controller for the next stage of the acquisition. The number of peaks can be configured for each group search is depends on the hardware implementation.
The Figure 4 shows the pilot symbol overlap in the PN space between the adjacent PN offsets. The PN offset is spaced 64 chips from its two adjacent PN offsets over
the same short PN sequence and all PN offsets transmit pilot symbols at the same instance of the time because of this, there will be 32 chips overlap of the pilot symbol between the adjacent PN offsets in the PN space. This causes the ambiguity while searching for the pilot symbol at the access terminal. The access terminal may detect the pilot symbol peak of adjacent offset on the offset which is configured for coarse acquisition search due to above said 32 chips overlap in the PN space. This ambiguity can be over come by performing the fine acquisition search for the adjacent offset's pilot symbol of the initially configured PN offset on the same collected data buffer. This search gives the fair chances to get the actual PN offset's pilot symbol peak with better energy level than the adjacent PN offsets pilot symbol peak.
Figure 5 shows the configuration of the fine acquisition group searches of the prior art. In the prior art the fine acquisition search will be done in the 3 group searches, which is fixed irrespective of the number of peaks found in the coarse acquisition search. The first group search will be configured for the peaks found for the PN offsets configured in the coarse acquisition search, the second group search is configured for the peaks of the left adjacent PN offsets of the PN offsets which are configured for the coarse acquisition search and the final search will be configured for the peaks of the right adjacent PN offsets of the PN offsets which are configured for the coarse acquisition search. In a good signal environment it is possible to get the less number of coarse acquisition peaks with good energy level than the maximum number peaks can be configured for a group search. In this kind of scenarios the prior art uses 3 group searches to finish the fine acquisition search, but each group search will be configured with less number of peaks than the supported maximum number of the peaks per group search. The present invention proposes a method to reduce the number of group searches in the signal environment where less number of the peaks found in the initial coarse acquisition search. In the proposed invention the number of group searches depends on the number of peaks found in the coarse acquisition search. The reduced number of the group searches helps to minimize the mean acquisition time by avoiding the excessive group search configurations. The maximum number of group searches required for the proposed invention required are 3 which is same as the prior art takes always.
Figure 6 shows the first step of the fine acquisition search, generation of the virtual peaks. The controller prepares the list of the peaks found from the coarse acquisition search which are above the threshold level. The virtual peaks are the peaks to be searched for the fine acquisition search; there will be two virtual peaks corresponding to the each peak qualified for the fine acquisition search. They are left adjacent PN offset's peak and the right adjacent PN offset's peak at the relative position of the actual peak. The position parameter of the each virtual peak will be calculated by the position parameter of the actual peak, by putting 64 chips away from it. Since, the PN offsets are spaced at 64chips. Then controller makes a list of peaks for fine acquisition group search which includes actual peaks found in the initial search and the virtual peaks generated and sorts it in the order of the peaks position over the sample data buffer.
Figures 7 and 8 are the diagrams of the fine acquisition search method of the present invention. The controller initially configures one or more PN offsets for the coarse acquisition search. The searcher performs the search over the collected data samples for the configured PN offsets and gives the peaks found in the search to the controller. Then the controller checks the valid peaks for the fine acquisition search. If there are no valid peaks found in the search then the same procedure will be repeated for the rest of the PN offsets. Once valid peaks found from the coarse acquisition then the controller goes for the fine acquisition search. The fine acquisition search will be performed be the group search method, the number of group searches required for the fine acquisition search is
GRP_CNT = ((3 x PEAK_CNT-1) + GRP_SIZE) / GRP_SIZE
Where,
GRP_CNT - number of group searches required for the fine acquisition search. PEAK_CNT - peaks found in the initial coarse acquisition search. GRP_SIZE - Maximum number of peaks can be configured for the search in a group.
The controller configures group search with the maximum number of peaks that can be configured in a group search. After every group search is completed the controller sorts out the best peak found in the group fine acquisition search, the best peak will be compared to the candidate peak energy which is found in the previous fine acquisition group searches and makes the strong peak among them as the candidate peak. Then controller continues to configure the pending peaks for next group search. Once all peaks are done for the fine acquisition search the controller checks the best candidate peak is above the threshold for the fine acquisition or not. If the best candidate peak is above the threshold then the controller proceeds for frequency pull in state to declare the acquisition result. If the best candidate peak after all group searches falls below the threshold level, then the controller proceeds for the coarse acquisition search with the different PN offsets, if there are PN offsets pending to be searched. If there is no pending PN offset to search, then controller declares the acquisition failure.
In the current invention the number of the group searches done for fine acquisition search always depends on the number of peaks found in the initial coarse acquisition search. This method reduces the number of group searches significantly in the environment where searcher gets less number of peaks in the initial search which helps to improve the mean acquisition time at the access terminal.
Advantages of the Invention
The proposed invention is advantageous in the less multi path and good signal environment to reduce the mean acquisition time of the gated pilot acquisition time.
It will also be obvious to those skilled in the art that other control methods and apparatuses can be derived from the combinations of the various methods and apparatuses of the present invention as taught by the description and the
accompanying drawings and these shall also be considered within the scope of the present invention. Further, description of such combinations and variations is therefore omitted above. It should also be noted that the host for storing the applications include but not limited to a microchip, microprocessor, handheld communication device, computer, rendering device or a multi function device.
Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are possible and are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.
N
GLOSSARY OF TERMS AND DEFINITIONS THEREOF
1. PN Offset - is one of the 512 codes used to differentiate sectors for communication with the mobile units The 512 points within the short PN sequence have been selected as the PN offsets (from 0-511) each 64 chips apart. Each base station uses a different point in the sequence to create a unique PN offset that can identify the base station sector.
2. PNJ3ROUP - the group of the PN offsets which will be configured for the coarse acquisition search at the same instance.
3. Full slot - the 2048 chips which lasts for 1,66msec. Each full slot contains 2 pilot symbols at the middle of the each half slot.
4. Px - the coarse acquisition peak with number x.
5. Pvpxy - the yth virtual peak of the coarse acquisition peak Px.
6. INDEX - the position of the peak from starting point of the collected data samples of the acquisition search (coarse or fine).
7. Grp #x- fine group search with group search number x.
8. PEAK_CNT - the number of valid peaks found in the coarse acquisition search.
9. GRP_CNT - the number of group searches required for the fine acquisition search.
10. CAND PEAK - the best peak from all fine group acquisition searches, which is the candidate peak to declare the acquisition success.
11. CAND_PEAK_ENG - the energy of the CAND_PEAK.

WE CLAIM
1. A method for optimal group search for gated pilot acquisition in a wireless system comprising the steps of:
(a) configuring initially one or more PN offsets for the coarse acquisition search by the controller;
(b) performing the search over the collected data samples for the configured PN offsets by the searcher;
(c) providing the peaks found in the coarse acquisition search to the controller by the said searcher;
(d) checking the valid peaks for the fine acquisition search by the said controller by group search;
(e) providing the peaks found in the fine acquisition search to the controller by the said searcher; and
(f) searching the peaks found in the coarse acquisition along with their adjacent PN offsets at the same position of the peak found in the coarse acquisition for the estimation of the pilot.
2. A method as claimed in claim 1 wherein if there are no valid peaks found in the coarse acquisition search then the same procedure is repeated for the rest of the PN offsets.
3. A method as claimed in claim 1 wherein once valid peaks found from the coarse acquisition, then the controller goes for the fine acquisition search.
4. A method as claimed in claim 1 wherein the fine acquisition search is performed by the group search method, and the number of group searches required for the fine acquisition search is given by
GRP_CNT = ((3 x PEAK_CNT-1) + GRP_SIZE) / GRP_SIZE where, GRP_CNT is number of group searches required for the fine acquisition search, PEAK_CNT - peaks found in the initial coarse acquisition search and GRP_SIZE - Maximum number of peaks can be configured for the search in a group.
5. A method as claimed in claim 1 wherein the controller configures group search with the maximum number of peaks that can be configured in a group search.
6. A method as claimed in claim 1 wherein after every group search is completed the controller sorts out the best peak found in the group fine acquisition search, where the best peak is compared to the candidate peak energy which is found in the previous group fine acquisition searches and makes the strong peak among them as the candidate peak.
7. A method as claimed in claim 1 wherein the controller configure the pending peaks for a next group search and once all peaks are done for the fine acquisition search the controller checks if the best candidate peak is above the threshold for the fine acquisition or not.
8. A method as claimed in claim 1 wherein if the best candidate peak is above the threshold then the controller proceeds for frequency pull in state to declare the acquisition result.
9. A method as claimed in claim 1 wherein if the best candidate peak after all group searches falls below the threshold level, then the controller proceeds for the coarse acquisition search with the different PN offsets if there are PN offsets pending to be searched and if there is no pending PN offset to search, then controller declares the acquisition failure.
10. A method as claimed in claim 1 wherein the number of the group searches done for fine acquisition search always depends on the number of peaks found in the initial coarse acquisition search.
11. A method as claimed in claim 1 wherein, two virtual peaks, the left adjacent PN offset's peak and the right adjacent PN offset's peak at the relative position of the actual peak are generated in the fine acquisition search.
12. A method as claimed in claim 1 wherein the position parameter of the each virtual peak is calculated by the position parameter of the actual peak and the controller makes a list of peaks for fine acquisition group search which includes actual peaks found in the initial search and the virtual peaks generated and sorts it in the order of the peaks position over the sample data buffer.
13. A system for optimal group search for gated pilot acquisition in a wireless system comprising:
(a) means for configuring initially one or more PN offsets for the coarse acquisition search by the controller;
(b) means for performing the search over the collected data samples for the configured PN offsets by the searcher;
(c) means for providing the peaks found in the coarse acquisition search to the controller by the said searcher;
(d) means for checking the valid peaks for the fine acquisition search by the said controller by group search;
(e) means for providing the peaks found in the fine acquisition search to the controller by the said searcher; and
(f) means for searching the peaks found in the coarse acquisition along with their adjacent PN offsets at the same position of the peak found in the coarse acquisition for the estimation of the pilot.
14. A system as claimed in claim 13 wherein if there are no valid peaks found in the coarse acquisition search then the same procedure is repeated for the rest of the PN offsets.
15. A system as claimed in claim 13 wherein once valid peaks found from the coarse acquisition, then the controller goes for the fine acquisition search.
16. A system as claimed in claim 13 wherein the fine acquisition search is performed by the group search method, and the number of group searches required for the fine acquisition search is given by
GRP CNT = ((3 x PEAK_CNT-1) + GRP_SIZE) / GRP_SIZE where, GRP_CNT is number of group searches required for the fine acquisition search, PEAK_CNT - peaks found in the initial coarse acquisition search and GRP_SIZE - Maximum number of peaks can be configured for the search in a group.
17. A system as claimed in claim 13 wherein the controller configures group search with the maximum number of peaks that is configured in a group search.
18. A system as claimed in claim 13 wherein after every group search is completed the controller sorts out the best peak found in the group fine acquisition search, where the best peak is compared to the candidate peak energy which is found in the previous group fine acquisition searches and makes the strong peak among them as the candidate peak.
19. A system as claimed in claim 13 wherein the controller configure the pending peaks for a next group search and once all peaks are done for the fine acquisition search the controller checks if the best candidate peak is above the threshold for the fine acquisition or not.
20. A system as claimed in claim 13 wherein if the best candidate peak is above the
threshold then the controller proceeds for frequency pull in state to declare the acquisition result.
21. A system as claimed in claim 13 wherein if the best candidate peak after all group searches falls below the threshold level, then the controller proceeds for the coarse acquisition search with the different PN offsets, if there are PN offsets pending to be searched and if there is no pending PN offset to search, then controller declares the acquisition failure.
22. A system as claimed in claim 13 wherein the number of the group searches done for fine acquisition search always depends on the number of peaks found in the initial coarse acquisition search.
23. A method as claimed in claim 13 wherein, two virtual peaks, the left adjacent PN offset's peak and the right adjacent PN offset's peak at the relative position of the actual peak are generated in the fine acquisition search.
24. A system as claimed in claim 13 wherein the position parameter of the each virtual peak is calculated by the position parameter of the actual peak and the controller makes a list of peaks for fine acquisition group search which includes actual peaks found in the initial search and the virtual peaks generated and sorts it in the order of the peaks position over the sample data buffer.
25. A method for optimal group search for gated pilot acquisition substantially
described particularly with reference to the accompanying drawings.
26. A system for optimal group search for gated pilot acquisition substantially described particularly with reference to the accompanying drawings.

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Patent Number

278362

Indian Patent Application Number

1749/CHE/2005

PG Journal Number

53/2016

Publication Date

23-Dec-2016

Grant Date

21-Dec-2016

Date of Filing

30-Nov-2005

Name of Patentee

SAMSUNG R&D INSTITUTE INDIA-BANGALORE PRIVATE LIMITED

Applicant Address

#2870 ORION BUILDING BAGMANE CONSTELLATION BUSINESS PARK OUTER RING ROAD DODDANEKUNDI CIRCLE MARATHAHALLI POST BANGALORE 560037

Inventors:

#	Inventor's Name	Inventor's Address
1	VENKATA SUBBA RAO MANNE	BAGMANE LAKEVIEW BLOCK 'B'NO.66/1 BAGMANE TECH PARK CV RAMAN NAGAR BYRASANDRA, BANGALORE -560093

PCT International Classification Number

G08C

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA