Title of Invention

METHOD FOR ALLOCATING GAP PATTERNS IN A WIRELESS COMMUNICATION ENVIRONMENT

Abstract

The invention describes a method and system in which measurement gap scheduling is initiated by a User Equipment (UE) and decided by the network in an L TE system. Depending on certain criteria, the UE decides if it needs a handover from one cell to another. In order to measure performance of an Inter Layer L TE cell or an Inter RAT cell for the handover, the UE needs measurement gap scheduling. The invention proposes a gap pattern based system in which a priority cell list is sent to the UE by the network or derived by the UE itself based on its knowledge of its use cases, preferences, capabilities, history of measurement etc. The UE chooses a minimum gap pattern based on the priority cell list and informs the same to the network. The network then decides on the proper gap pattern for the UE. In addition, the cell priority list is also used for a blind handover by the network. The most prioritized cell can be used for the blind handover.

Full Text

FIELD OF INVENTION The present invention, in general, relates to the field of wireless communication. The present invention relates to RRC Mobility Protocol (Handovers and Measurements) especially in LTE system - Layer2/ Layer 3 (RRC Layer). More particularly this invention relates to UE suggested - n/w decided gap scheduling based on minimum GP in LTE system. DESCRIPTION OF RELATED ART Gap-assisted and Non-Gap assisted measurements are being talked about in the LTE. It is accepted that for the Inter measurements (measurements for all/ some of the Inter Layer cells and/ or Inter RAT (UTRA/ GSM) cells) UE would require gaps. So far nothing is available which suggest a method to accomplish the same. There is one US patent (6,845,238), which talks about Inter-frequency measurement and Handover for wireless communication. This indicates, "The quality estimate can be utilized to trigger a change or switch of frequencies/systems. Certain thresholds employed in the quality estimate- utilizing handovers provide hysteresis protection." SUMMARY OF THE INVENTION An LTE UE would require gaps to measure the Inter Layer and Inter RAT cells. There are discussions going on for gap assisted and non-gap assisted measurements. A UE would require gaps to measure the Inter Layer and Inter RAT cells. In the gap-assisted measurements, the discussions are going on to decide if the requirement for gaps and subsequently the triggering of gap patterns will be done at the n/w or at the UE. Some companies are exploring the possibility that such a gap schedule request comes from the UE itself while other companies are suggesting that the gaps pattern (GP) should be indicated by the n/w. In the latter case the decision to schedule gaps will depend on the UE measurements. This has latency involved. Also, it will be better to involve UE as in following Use Cases: 1. UE inactivity - (UE DRX) - It may not be known if the UE has already performed enough measurements on its own. 2. Bad signal area - UE can carry out some inter measurement in such situation 3. Conservative and wasteful allocation from n/w 4. Anchoring eNode-B case: No knowledge of UE capability So in such cases the decision to provide the GP to the UE without UE involvement might be a waste of resources. On the other hand if the UE decides on the gap requirement it will miss out on the bigger cell load picture. Though in this case all the above situations (use cases) can be fulfilled but it is possible that a lot of UEs request for the Gaps at the same time, so for the n/w it may not be possible to sustain the scheduling for all of them while meeting the QOS requirements. Therefore, the present invention provides a method, which can benefit from the UE knowledge of the use cases and do not overload the n/w at the same time. The present invention further provides a minimum gap pattern based, UE initiated - network controlled scheduling for LTE Inter Layer/ frequency and Inter system measurements. The present invention further aims at being efficient in terms of latency requirements (minimum signalling). The present invention proposes 1. A minimum gap pattern based, UE initiated - network controlled scheduling; where the UE based on its requirements (Use cases) selects a gap pattern and indicates the same to the network. Network may allocate the same Gap pattern to the UE based on overall cell load picture. 2. Cell Priority listing for neighbour cell measurements for better handover success rate 3. Blind Handover based on cell priority list A UE requiring a gap pattern to carry out inter frequency/ RAT measurement may participate in the gap pattern allocation process and assist the network in accomplishing the same; whereby the UE selects one minimum gap pattern out of an available set of minimum gap patterns; wherein the minimum gap pattern is an un-repeated representation of the actual available gap patterns. The selection of the minimum gap pattern is based on UE specific conditions like, but not limited to, its RAT preference, network topology, history of successful handover between a pair of cells, previous available cell rankings, already performed measurements before seeking a gap pattern from the network etc. The said selection on minimum gap pattern shall indicate the UE specific measurement requirement to the network. Wherein the said network shall try to allocate the same gap pattern for a longer period (repetitions of the minimum gap pattern) of time to the UE, failing which, e.g. due to load conditions or scheduler restrictions or complexity, the network shall allocate the next best available gap pattern to the UE; whereby the allocated gap pattern shall best fit the UE specific requirements. Accordingly the invention explains a method for UE suggested network decided gap scheduling based on minimum GP in wireless communication system comprising the steps of: deciding the need of a handover from one cell to another by the UE; providing a gap pattern in which a priority cell list is sent to the UE by the network or derived by the UE itself based on its knowledge of its use cases, preferences, capabilities, history etc. choosing a minimum gap pattern by the UE based on the priority cell list and informing the same to the network; and deciding on the proper gap pattern for the UE by the network, wherein a cell priority list is used for a blind handover by the network. Accordingly the invention also explains a system for UE suggested network decided gap scheduling based on minimum GP in wireless communication system comprising the steps of: means for deciding the need of a handover from one cell to another by the UE; means for providing a gap pattern in which a priority cell list is sent to the UE by the network; means for choosing a minimum gap pattern by the UE based on the priority cell list and informing the same to the network; and means for deciding on the proper gap pattern for the UE by the network, wherein a cell priority list is used for a blind handover by the network These and other objects, features and advantages of the present invention will become more apparent from the ensuing detailed description of the invention taken in conjunction with the accompanying drawings. BRIEF DESCRPTION OF ACCOMPNAYIN DRAWINGS Figure 1 depicts MSC for Gap pattern request from the UE. DETAILED DESCRIPTION OF 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 order to support efficient mobility in any wireless cellular system, the UEs (user equipment) are required to identify and measure the relevant measurement quantities of neighbor cells and the serving cell. Such measurements for mobility are needed in various mobility functions like PLMN selection, Cell Selection and reselection, handover decisions etc. The present invention only concerns the Inter frequency) measurements. Neighbor cell measurements are considered inter-frequency measurements when the UE needs to re-tune its (Frequency synthesizer) receiver in order to carry out the measurements. This corresponds to the cases when - the neighbor cell is operating on a different carrier frequency than the current cell, or - the neighbor cell is operating on the same carrier frequency as the current cell, but the UE maximum bandwidth capability is smaller than the network system bandwidth and the UE is currently "camping" within a band so that the common channels of the target cell are outside the UE receiving bandwidth. The inter frequency measurements could be made both on the present as well as on a different Radio Access Technology (RAT) like GERAN, UMTS, LTE etc. In case of inter-frequency measurements, the network needs to be able to provide UL/DL idle periods for the UE to perform necessary neighbor measurements. These idle UL/ DL periods are called gaps. A set of gaps which are especially designed to facilitate the efficient measurement of a neighboring frequency is called a gap pattern. Therefore a gap pattern contains of two parts: i) gaps: where the UE performs measurement of the neighboring frequency ii) non-gaps: where the UE performs the activity on the current frequency. There can be a number of gap patterns with different performance requirement. Both the UE and the network shall know which gap pattern is being used and they shall be synchronized. While the UE has some use cases (conditions or scenarios) where it can better tell what kind of gaps it require to carry out the inter measurements, network, on the other hand is in control of the overall cell load. Also the scheduler at the network decides the UE traffic activity scheduling based on the incoming traffic in downlink. Therefore it needs to be deciding as to who shall control the gap pattern allocation between UE and the network. Due to UE's micro knowledge (about its own measurement requirements) and network's macro knowledge (of cell load) it is better than both of them participate in this decision. It is better that both UE and the network have a fair amount of control over the Gap Scheduling process. Now, we will go through all the steps involved in scheduling of gaps starting with the intra measurements which are required to find out the quality for the current cells. We will, at the same time, discuss the area relevant to our proposal. 1. UE receives Measurement Control from the n/w and performs Intra measurements 2. Intra quality goes bad 3. UE decides on a Min_GP to be used. This selection will be based on a. UE's knowledge of its own condition (Use cases) b. Cell Priority list (explained below in point 4). UE in its measurement report indicating bad intra quality will also indicate the Min_GP to network. This message in addition may (optionally) contain the measurement report of all the inter cells already measured by the UE (as in point 1 and 2 of Use Cases - section 4). N/w can use this measurement report and may use this for an Immediate HO decision. The idea to send the minimum gaps from the UE takes advantage of UE knowledge of its own situations and at the same time it does not 'over burden' the network. The min_gap should be designed in such a way that they allow the LTE UE to measure a bare minimum of Inter Cells. The bare minimum cell number could be decided by the network and should be a result of network optimization. This value could be anything starting with 1 and can be more based on Cell-Load and scheduling condition. It can be dynamically changed and informed to UE using the BCH or it can be kept static. Both the options should be explored. 4. UE should measure the cells based on a priority order. The priority of the cells will depend on many things and the followings are some of them. Some of the aspects of priority could be implementation specific. a. LTE Service Handover [4] b. Cell/ network Topology c. Previous History d. Cell rank based on old measurements e. Performed Measurements UE will pick the min_GP based on the cells it wishes to measure first, which will be decided by the cell priority list. For a description of the above criteria and CPL the Cell Priority Criteria given at the end of this section may be referred to. 5. At the n/w side: a. Option 1: The n/w scheduler at periodic scheduling interval (possibly every TTI or multiple thereof) does the 'Admission check' for all the min_GPs and prepares a 'lookup table' for next schedule period - something like min_GP1 OK min_GP2 OK min_GP3 NOK min_GP4 OK Upon receiving a min_GP request, n/w uses the lookup table to indicate the UE - min_GP: OK/ NOK. b. Option 2: N/w uses the Min_GP signaled from the UE to estimate what kind of gap pattern the UE is looking for. It can be used as an important parameter to decide on a proper Gap Pattern (to measure greater number of inter cells). As and when the requirement for gaps ceases, the UE indicates the same to n/w using some "special"/ good CQI reports. In either case (option 1 or option 2) the n/w will send the Gap Indication to the UE with an explicit message. Option 1 however will be less time consuming and therefore better turnaround time to start the GAP assisted measurements. 6. Blind HO based on Cell Priority: If the priority ordering of cells above (point 4) give successful results i.e. the attempts of HO lead to an increased HO successes rate (based on overall n/w experience) then the n/w may decide on a Blind HO. The concept is that between a pair of cells the n/w is reasonably confident that the HO can be carried out without supporting measurements. The best cell according to the cell priority (in 4) can be a good candidate for Blind HO. If implemented successfully, this will lead to immediate HO, which will be beneficial in situation when the quality degrades sharply in the serving cells. This will also avoid lot of signaling load. Referring to Figure 1, the message sequence chart, the UE is performing the intra frequency measurements (stepl). It realizes that the present frequency goes below a certain threshold and that it needs to perform the inter frequency/ RAT measurements (step2). UE has to decide on a gap pattern, which it shall indicate to the network as the best, suited pattern. It shall take into consideration all (but not limited to) the followings: Its priority for RAT Network topology Handover history cell rank and, performed measurements in long DRX. Explanation of Cell Priority Criteria Cell Priority List (CPL) can be told to the UE in measurement control message or the common part of the CPL (criteria applicable to all the UEs in the cell) can be broadcasted. In the latter case the UEs themselves apply the individual priority (cell rank, service HO IE etc.) and get the exact CPL. A modified CPL can be indicated by the n/w in the message where it informs the UE about the GP allocated to it. Explanation of the entire criterion: Service Handover in LTE: In UTRA the RAB ASSIGNMENT REQUEST contained a parameter called Service Handover. This parameter indicates a priority of HOs between UTRA and GSM cells. A similar IE in the other wireless communication systems will indicate the preference between different neighboring RATs like LTE, E-UTRA, UTRA and GSM cells. Cell/ network Topology: This will indicate the affinity in terms of geographical location of two cells. For example cells situated along a busy street will be more likely candidate for HO from one another than off-road cells. Previous History: This indicates the successful HOs to this cell and the source cell. Cell rank: This is same as measurement based cell ranking in UTRA cells for the particular UE. Performed measurements: UE shall take into account the measurements which it has already performed e.g. in a long DRX. It should be noted that none of the criterion is binding and should be implementation specific. ADVANTAGES 1. UE can take care of its actual requirements - 'Use Cases' and Network has the bigger overall control. 2. Immediate HO is possible using the UE's 'already measured' Inter cell measurement report. 3. Measuring better cells will avoid complete n-cell measurements and the resulting successful HOs will bring down the overall cell load condition. 4. Min GP allocation using the lookup table by the n/w should be less time consuming. 5. Overall cell load may go down as a result of successful HOs (from less number of required measurements). 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 there from. GLOSSARY OF TERMS AND DEFINITIONS THEREOF GM - Gap Mode GP - Gap Pattern HO - Handover LTE - Long Term Evolution Inter Cells - All/ some of the Inter Layer cells and/ or Inter RAT (UTRA/ GSM) cells Inter Measurement - Measurements on the Inter Cells Intra Measurement - Measurements on the Intra Layer Cells Min_gap/ Min_GP - Minimum Gaps which will be required to measure one or more Inter Cell(s). The values will change on Inter cell types (for different Inter System Cells) and number. So there will be a set of predefined min_gap pattern (Min_GP) corresponding to a set of 'bare minimum' Inter cell(s); e.g. Min_GP1 can be used to measure 1 GSM cell + 1 UTRA cell and Min_GP2 can be used to measure 1 GSM cell + 1 inter LTE cell etc. Exactly how the Min_GP will look like is FFS. n/w - E-UTRA RAN UE - User Equipment GM is not the same as UTRA Compressed Mode. We Claim, 1. A method for UE suggested network decided gap scheduling based on minimum GP in wireless communication system comprising the steps of: deciding the need of a handover from one cell to another by the UE; providing a gap pattern in which a priority cell list is sent to the UE by the network or derived by the UE ; choosing a minimum gap pattern by the UE based on the priority cell list and informing the same to the network; and deciding on the proper gap pattern for the UE by the network, wherein a cell priority list may also be used for a blind handover by the network. 2. A method as claimed in claim 1 wherein the said priority cell list is derived from UEs preference for a particular RAT which may be service specific, network topology, history of mobility which signifies the handover success rates between a pair of cells, cell rankings, performed measurements by which the UE shall take into account the measurements which it has already performed. 3. A method as claimed in claim 1 wherein when intra quality goes bad UE decides on a Min_GP to be used based on UE's knowledge of its own condition and cell Priority list. 4. A method as claimed in claim 1 wherein UE in its measurement report indicating bad intra quality also indicate the Min_GP to network, where the message in addition may contain the measurement report of all the inter cells already measured by the UE. 5. A method as claimed in claim 1 wherein network use the measurement report and can use the said report for an Immediate HO decision. 6. A method as claimed in claim 1 wherein UE measure the cells based on a priority order. 7. A method as claimed in claim 1 wherein UE pick the min_GP based on the cells it wishes to measure first which will be decided by the cell priority list. 8. A method as claimed in claim 1 wherein the network scheduler at periodic scheduling interval does the 'Admission check' for all the min_GPs and prepares a 'lookup table' for next schedule period. 9. A method as claimed in claim 1 wherein upon receiving a min_GP request, network uses the lookup table to indicate the UE - min_GP: OK/ NOK. 10. A method as claimed in claim 1 wherein network uses the Min_GP signaled from the UE to estimate what kind of gap pattern the UE is looking for. 11. A method as claimed in claim 1 wherein when the requirement for gaps ceases, the UE indicates the same to network. 12. A method as claimed in claim 1 wherein the network sends the Gap indication to the UE with an explicit message. 13. A system for UE suggested network decided gap scheduling based on minimum GP in wireless communication system comprising the steps of: means for deciding the need of a handover from one cell to another by the UE; means for providing a gap pattern in which a priority cell list is sent to the UE by the network; means for choosing a minimum gap pattern by the UE based on the priority cell list and informing the same to the network; and means for deciding on the proper gap pattern for the UE by the network, wherein a cell priority list is used for a blind handover by the network 14. A method for UE suggested network decided gap scheduling based on minimum GP in wireless communication system substantially described particularly with reference to the accompanying drawings 15. A system for UE suggested network decided gap scheduling based on minimum GP in wireless communication system substantially described particularly with reference to the accompanying drawings.

Documents:

1844-CHE-2006 AMENDED CLAIMS 26-08-2014.pdf

1844-CHE-2006 AMENDED CLAIMS 28-06-2013.pdf

1844-CHE-2006 AMENDED PAGES OF SPECIFICATION 26-08-2014.pdf

1844-CHE-2006 AMENDED PAGES OF SPECIFICATION 28-06-2013.pdf

1844-CHE-2006 EXAMINATION REPORT REPLY RECEIVED 26-08-2014.pdf

1844-CHE-2006 EXAMINATION REPORT REPLY RECEIVED. 28-06-2013.pdf

1844-CHE-2006 FORM-1 26-08-2014.pdf

1844-CHE-2006 FORM-1 28-06-2013.pdf

1844-CHE-2006 FORM-13 28-06-2013.pdf

1844-CHE-2006 FORM-13 12-12-2013.pdf

1844-CHE-2006 FORM-3 28-06-2013.pdf

1844-CHE-2006 FORM-3 28-06-2013.tif

1844-CHE-2006 OTEHR PATENT DOCUMENT 28-06-2013.pdf

1844-CHE-2006 OTEHR PATENT DOCUMENT 1 28-06-2013.pdf

1844-CHE-2006 OTHERS 26-08-2014.pdf

1844-CHE-2006 POWER OF ATTORNEY 26-08-2014.pdf

1844-CHE-2006 POWER OF ATTORNEY 28-06-2013.pdf

1844-CHE-2006 ABSTRACT.pdf

1844-CHE-2006 CLAIMS.pdf

1844-CHE-2006 CORRESPONDENCE OTHERS.pdf

1844-CHE-2006 DESCRIPTION (COMPLETE).pdf

1844-CHE-2006 DRAWINGS.pdf

1844-CHE-2006 FORM 1.pdf

1844-CHE-2006 FORM 18.pdf

1844-CHE-2006 FORM 5.pdf

1844-CHE-2006 FORM-13 16-12-2013.pdf

1844-che-2006-correspondence-others.pdf

1844-che-2006-description-provisional.pdf

1844-che-2006-form1.pdf

1844-che-2006-form26.pdf