Title of Invention

FINGER MANAGEMENT FOR CDMA SYSTEMS WITH HIGH RATE PACKET DATA

Abstract

The present invention relates to the Wireless communication, CDMA, finger management, rake receiver. More particularly the present Invention relates to finger management for CDMA systems with high rate packet data. The invention explains a method of finger management for CDMA systems with high rate packet data comprising the steps of getting active set search results for all sectors; assigning fingers to serving sector's candidate paths; assigning fingers to all sects to achieve cell diversity; and assigning fingers to all sects to achieve path diversity

Full Text

FIELD OF INVENTION The present invention relates to the Wireless communication, CDMA, finger management, rake receiver. More particularly the present invention relates to a method of finger management for CDMA systems with high rate packet data DESCRIPTION OF THE RELATED ART In a cellular communication system, the transmitted signals from Base Transceiver Station(s) (BTS) pass through wireless channel consisting of several distinct propagation paths (known as multipaths) and reach the access terminal (AT). In wireless channels these multipaths are caused by reflection of the transmitted signal from buildings, trees, cars etc.. In a CDMA cellular system, the received signal can be separated into various multipaths and signals from each multi-path is demodulated and combined in a rake receiver to achieve multipath diversity gain. The BTS transmits a pilot signal (continuously/time multiplexed) along with other signals. The AT can use (with its path searcher,) this pilot information to detect multipaths and configures the rake receiver fingers. When the AT is in soft handoff there can be more than one BTS (group and termed as active set pilots/sectors) transmitting signals to AT and AT can identify the signal paths corresponding to each BTS and assigns fingers based on the finger assignment/management rules. In High Rate Packet Data (HRPD) systems, out of all active set sectors only one sector transmits data channel and is known as sen/ing sector. The access terminal continuously monitors the radio link between the access terminal and access network by measuring the strength of the pilots transmitted by all the active set pilots/sectors. Active Set: The set of pilots (specified by the pilot"s PN offset and the pilot"s CDMA Channel) associated with the sectors currently serving the access terminal or access terminal is monitoring the sectors control channel. The Figure 1 shows procedure for finger management procedure for each cycle of the search process of the CDMA receiver. In the existing procedure, the searcher periodically schedules the active set searches. At the end of search controller reads the search results. The following steps explain how existing procedure manages fingers: 1. The controller gets search results (100) and it analyses the paths from search results and gets the list of paths which are above the threshold. These sorted paths can be called as candidate paths for the finger management. 2. The controller first assigns the candidate paths to the fingers which are available for path assignment to promote the sector diversity (102). 3. Once sector diversity is achieved then controller assigns the strongest paths to the available fingers (103). In the existing approach, if there is more than one sector in the active set the finger management algorithm assigns at least one finger to each and every sector in the active set. So that all sectors in the active set will be demodulated and there won"t be any loss in sector specific information such as power control information. In the algorithm after performing the sector diversity operation, if there is scope to have any free finger to assign to a candidate path then algorithm assigns fingers to available strongest candidate paths. In the existing approach, If there are more sectors in the active set and each sector is received with almost equal signal strength the finger management algorithm assigns available fingers to various sectors to increase the sector diversity. But due to this the signal strength received from the serving sector may be less because insufficient fingers assigned to serving sector which results in reduced throughput. And also AT always relies on the sector switching algorithm for better reception. SUMMARY OF THE INVENTION The present invention is a method for systems like high rate packet data (HRPD) to assign the multiple fingers to the set of candidate paths from the search results, which guarantees to assign minimum number of fingers to the serving sector. Since in HRPD systems, the user data in traffic state transmitted only on the serving sector, new method attempts to increase the throughput by assigning sufficient number of fingers to the serving sector In a data call when there are more than one sectors in the active set. The minimum number of fingers for serving sector will be deducted from the total energy of the serving sector and Its candidate paths. While assigning fingers to serving sector, care is taken about the cell diversity by putting the maximum limit for number of fingers to be assigned for the serving sector. Once fingers are assigned for candidate paths of the serving sector and to candidate paths of other sectors for the cell diversity then strongest paths in the candidate path list will be assigned by the fingers If still they are available for new assignments. The invention explains a method of finger management for CDMA systems with high rate packet data comprising the steps of: getting active set search results for all sectors; assigning fingers to serving sector"s candidate paths; assigning fingers to all sects to achieve cell diversity;and assigning fingers to all sects to achieve path diversity These and other objects, features and advantages of the present invention will become more readily apparent from the detailed description taken In conjunction with the drawings and the claims. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1: depicts the Finger Management procedure in the existed approach. Figure 2: depicts the Finger Management procedure in the current invention Figure 3: depicts the detailed finger management procedure (part 1) Figure 4: depicts the detailed finger management procedure (part 2) DETAILED DESCRIPTION OF THE INVENTION The preferred embodiments of the present invention will now be explained with reference to the accompanying drawings. The following description and drawings are illustrative of the invention and are not to be construed as limiting the innovation. Numerous specific details are described to provide a through understanding of the present invention. However in certain instances well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail. The figure 2 shows the over all operation of the finger management algorithm for systems like high data rate packet data (HRPD). Initially controller gets active set search results from searcher and they will be sorted as per their energies and positions over the PN role to make the candidate path list (100). Now serving sector"s candidate paths are considered for finger assignment as per the procedure explained below (101). Once serving sector"s candidate paths are assigned to the fingers then the all other candidate paths will be assigned to fingers to achieve the cell diversity and the strongest path diversity as per the free fingers availability as it is in existed approach (102 and 103). The figures 3 and 4 explain the new approach (101) to assign serving sector"s candidate paths. In the flowchart it is seen that initially number of fingers and finger energy are set to 0. P is assigned to first path of serving sector. Then a check is made to confirm whether P is assigned by a finger. If P is assigned by a finger the finger count and finger energy gets incremented. If P is not assigned by a finger, a check is made to confirm whether it Is the last path of serving sector and if it is not the last path next path is assigned to P. If it is not the last path, first path of serving sector is assigned to P. Then a check is made to confirm whether FING_CNTs is less than MAX_FINGs and If It is positive further check is made to confirm if FING_ENGs is less than MIN_ENGs.lf both the conditions said above are satisfied a check Is made to confirm whether P Is assigned by a finger and also a check Is made to confirm whether it is the last path of serving sector. If It Is the last path then control transfers to step (102). If P is not assigned by a finger a check is made to confirm whether any free finger available or not and if available P is assigned with the new finger .Also FING_CNTs and FING_ENGs gets Incremented. In the above check when it is found that no free finger Is available a check is made to confirm whether any weak finger from non serving sector Is available and if no weak fingers are found a check is made to confirm whether 3dB weak finger are there. If there is any 3dB weak finger then that finger will be re-assigned to the serving sector"s candidate path under consideration for finger assignment and proceeds to the next to assign fingers to achieve the cell diversity. If there is no finger which satisfies the above conditions then algorithm proceeds to next with out any finger re-assignments. Initially as shown in the figure 3 It calculates the total number of fingers (FING_CNTs) already assigned to demodulate the serving sector"s paths, total energy (FING_ENGs) of serving sector"s energy which is demodulated by the already assigned fingers. Once total number of fingers already assigned to the serving sector (FING_CNTs) and total energy of the all fingers which are demodulating the serving sector (FING_ENGs) are known then the parameters deducted as follows: 1. The number fingers that can be assigned to the serving sector with out compromising much in cell diversity (MAX_FINGs) MAX_FINGs = min (T0T_FINGS/2, (TOT_FINGS - MAX_CD_FINGS)) 2. The maximum fingers required to give for the cell diversity ( MAX_CD_FINGS) MAX_CD_FINGS = min (T0T_FINGS/2, (CELL_GNT-1)) Where > TOT_FINGS - Total available fingers > CELL_CNT - Number of cells in the active set > MAX_CD_FINGS - Maximum fingers required for the Cell diversity Once all these parameters deducted, algorithm proceeds to assign fingers for rest of the candidate paths of the serving sector as shown in the figure 4. As long as the total number of the fingers assigned to the serving sector is less than MAX_FINGs and total energy covered by the all fingers assigned to the serving sector is less than FING_ENGs then the algorithm continues to assign the more fingers to the candidate paths of the serving sector. The additional fingers for serving sector will be assigned with out any limitations until above said equality satisfied when unassigned fingers are available. When unassigned fingers are not available and yet serving sector needs to assign more fingers to get above requirement satisfied then one more finger will be made available for serving sector by one of the below said conditions: 1. If there is a finger, which is assigned to the non serving sector and the cell to which this finger is assigned is having more than one stronger finger than this finger. 2. If there is no finger which satisfies the above condition, then it will checked for the finger which is assigned to the serving sector"s path and its energy is 3dB less the candidate path of the serving sector which is under consideration for finger assignment. If we get a weak finger from above said two conditions then that finger will be re-assigned to the serving sector"s candidate path under consideration for finger assignment and proceeds to the next to assign fingers to achieve the cell diversity (102). If there is no finger which satisfies the above two conditions then algorithm proceeds to next with out any finger re-assignments. After assigning fingers to the serving sector algorithm proceeds to assign the fingers to the candidate paths to achieve the cell diversity. The maximum number of the fingers can be assigned to the cell diversity is MAX_CD_FINGS; this assumption satisfies the finger requirement for the cell diversity. The algorithm continues to assign the fingers to the candidate paths to get cell diversity and strongest path diversity as it is in existing procedure. While assigning fingers for cell diversity and strongest path diversity the fingers already assigned to the serving sector with out disturbing the above said requirement for serving sector. In the description herein, numerous specific details are provided, such as examples of components and/or methods, to provide a thorough understanding of embodiments of the present invention. One skilled in the relevant art will recognize, however, that an embodiment of the invention can be practiced without one or more of the specific details. In other instances, well-known operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments of the present invention. It will also be appreciated that one or more of the elements depicted in the drawings/figures can also be implemented in a more separated or integrated manner, or even removed or rendered as inoperable in certain cases, as is useful in accordance with a particular application. The foregoing description of illustrated embodiments of the present invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed herein. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the present invention, as those skilled in the relevant art will recognize and appreciate. As indicated, these modifications may be made to the present invention in light of the foregoing description of illustrated embodiments of the present invention and are to be included within the spirit and scope of the present invention. Thus, while the present invention has been described herein with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosures, and it will be appreciated that in some instances some features of embodiments of the invention will be employed without a corresponding use of other features without departing from the scope and spirit of the invention as set forth. Therefore, many modifications may be made to adapt a particular situation to the essential scope and spirit of the present invention. It is intended that the invention not be limited to the particular terms used in following claims, but that the invention will include any and all embodiments and equivalents falling within the scope of the appended claims. References Reference Documents Document Index Document Name C.S0024 v4.0 CDMA 2000 high rate packet data air interface specification C.S0002-C to C.S0005-C CDMA2000 Release A Standards for L1, L2 and L3 US patent No US005490165A Demodulation element assignment in a system capable of receiving multiple signals Glossary of Terms and their definitions Access Terminal: A device providing data connectivity to a user. An access terminal may be connected to a computing device such as a laptop personal computer or it may be a self-contained data device such as a personal digital assistant. An access terminal is equivalent to a mobile station. Channel: The set of channels transmitted between the access network and the access terminals within a given frequency assignment. A Channel consists of a Forward Link and a Reverse Link. HRPD: High Rate packet Data system Finger: A branch of Rake receiver which demodulates a received path WE CLAIM 1. A method of finger management for CDMA systems with high rate data comprising the steps of: a) getting active set search results for all sectors; b) assigning fingers to serving sector"s candidate paths; c) assigning fingers to all sects to achieve cell diversity; and d) assigning fingers to all sects to achieve path diversity 2. A method as claimed in claim 1 wherein initially controller gets active set search results from searcher and sorts these path results as per their energies and positions over the PN role to make the candidate path list. 3. A method as claimed in claim 1 wherein once serving sector"s candidate paths gets assigned to the fingers then all the other candidate paths will be assigned to fingers to achieve the cell diversity and the strongest path diversity as per the free fingers availability. 4. A method as claimed in claim 1 wherein the said method is used to assign the multiple fingers to the set of candidate paths from the search results, which guarantees to assign minimum number of fingers to the serving sector 5. A method as claimed in claim 1 wherein the user data in traffic state transmitted only on the serving sector increases the throughput by assigning sufficient number of fingers to the serving sector in a data call when there are more than one sectors in the active set. 6. A method as claimed in claim 1 wherein the minimum number of fingers for serving sector shall be deducted from the total energy of the serving sector and its candidate paths. 7. A method as claimed in claim 1 wherein while assigning fingers to serving sector, the cell diversity is taken care by putting the maximum limit for number of fingers assigned for the serving sector. 8. A method as claimed in claim 1 wherein to assign serving sector"s candidate paths initially the total number of fingers (FING_CNTs) already assigned to demodulate the serving sector"s paths and total energy (FING_ENGs) of serving sector which is demodulated by the already assigned fingers are calculated. 9. A method as claimed in claim 1 wherein the number fingers that can be assigned to the serving sector with out compromising much in cell diversity (MAX_FINGs)is given by MAX_FINGs = min (T0T_FINGS/2, (TOT_FINGS -MAX_CD_FINGS)). 10. A method as claimed in claim 1 wherein the maximum fingers required for the cell diversity ( MAX_CD_FINGS) is given by MAX_CD_FINGS = min (T0T_FINGS/2, (CELL_CNT-1)). 11. A method as claimed in claim 1 wherein as long as the total number of the fingers assigned to the serving sector is less than MAX_FINGs and total energy covered by the all fingers assigned to the serving sector is less than FING_ENGs, more fingers are assigned to the candidate paths of the serving sector. 12. A method as claimed in claim 1 wherein when unassigned fingers are not available and when the serving sector needs to assign more fingers to get above the requirement satisfied then one more finger will be made available for serving sector. 13. A method as claimed in claim 12 wherein one more finger will be made available for the serving sector when there is a finger which is assigned to the non serving sector and the cell to which this finger is assigned is having at least one stronger finger than this finger. 14. A method as claimed in claim 12 wherein one more finger will be made available for the serving sector when there is no free finger and there is a finger which is already assigned to the serving sector"s path and its energy is 3dB less than the candidate path of the serving sector which is under consideration for finger assignment. 15. A method as claimed in claim 12 wherein if a finger is re-assigned to the serving sector"s candidate path under consideration, the controller proceeds to assign fingers to achieve the cell diversity. 16. A method as claimed in claim 12 wherein if there is no finger which satisfies the required conditions then the algorithm proceeds with out any finger re-assignments. 17. A method as claimed in claim 1 wherein after assigning fingers to the serving sector algorithm proceeds to assign the fingers to the candidate paths to achieve the cell diversity. 18. A method as claimed in claim 1 wherein the maximum number of the fingers can be assigned to the cell diversity is MAX_CD_FINGS. 19. A method of finger management for CDMA systems with high rate packet data such as herein substantially described particularly with reference to the accompanying drawings.

Documents:

1478-che-2004 abstract.pdf

1478-che-2004 claims-duplicate.pdf

1478-che-2004 claims.pdf

1478-che-2004 correspondence-others.pdf

1478-che-2004 correspondence-po.pdf

1478-che-2004 description (complete)-duplicate.pdf

1478-che-2004 description (complete).pdf

1478-che-2004 drawings.pdf

1478-che-2004 form-1.pdf

1478-che-2004 form-13.pdf

1478-che-2004 form-19.pdf

1478-che-2004 form-26.pdf