Abstract:
A method of managing cell reselection for a User Equipment (UE) in an idle mode connected to a wireless network system is provided. The method includes determining system information of available cells on a given frequency, determining the system information from a plurality of cells and frequencies to determine which of the plurality of cells support a Multimedia Broadcast Multicast Service (MBMS), determining a MBMS Control CHannel (MCCH) of the plurality of cells that support the MBMS, generating a list of cells by prioritizing the plurality of cells that support the MBMS over other frequencies or cells in a ranking order, and reselecting a cell or a frequency supporting the MBMS before starting a MBMS session from among the generated list to be a cell where the MBMS session is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S)  
       [0001]    This application is a U.S. National Stage application under 35 U.S.C. §371 of an International application filed on Oct. 4, 2012 and assigned application number PCT/KR2012/008054, which claimed the benefit of a Indian patent application filed on Oct. 4, 2011 in the Indian Intellectual Property Office and assigned Serial number 3443/CHE/2011, the entire disclosure of which is hereby incorporated by reference. 
     
    
     TECHNICAL FIELD  
       [0002]    The present disclosure relates to mobile communication technology. More particularly, the present disclosure relates to management of cell selection of user equipment connected to a wireless network, such as a Long Term Evolution (LTE) type of network. 
       BACKGROUND ART  
       [0003]    A user equipment may be in an active mode or in an idle mode. The active mode of the user equipment may correspond to active data transferring between the user equipment and a base station. The idle mode of the user equipment may correspond to passive and/or inactive data transferring between the user equipment and the base station. 
         [0004]    For example, when the user equipment is in the idle mode and in need of a Multimedia Broadcast Multicast Service (MBMS), the user equipment will latch on to, or in other words, connect to and/or communicate with, a cell that provides MBMS services. When a user equipment is in the idle mode and is receiving the MBMS service, the user equipment may enter into an active mode at any time thereby causing a load on the cell as the data transfer rate and/or bit rate may be relatively high owing to the nature of applications being handled in the user equipment. In a Long Term Evolution (LTE) cell supporting carrier aggregation, there may be multiple bands, each band with multiple carriers, to facilitate uplink and downlink of data between the user equipment and the base station. Among the bands supported by an LTE cell, there may be selective bands that accommodate MBMS service in a cell. Hence, when in idle mode, the user equipment may try to connect onto the selective bands and/or band and/or a particular cell that supports such a band that has MBMS capability. When a large number of mobile communication devices, such as user equipment, latch on to a cell in an idle mode, there is a high probability that they may enter the connected mode in the same cell. When the user equipment above a limit tries to connect to the selective bands with MBMS capability, congestion may occur. In the scenario when the MBMS transmissions are scheduled in only one band or cell, the idle mode UEs that may receive MBMS service may camp onto the cell or frequency that supports MBMS services. 
         [0005]    The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure. 
       SUMMARY  
       [0006]    Aspects of the present disclosure are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present disclosure is to provide a method of managing mobile communication technology. 
         [0007]    More User Equipments (UEs) may be camped onto a cell or frequency that supports Multimedia Broadcast Multicast Service (MBMS) rather than cells that do not support MBMS services. Such scenarios lead to congestion of certain cells/frequencies than others. In order to mitigate such overload conditions, there is a need to enforce appropriate camping behaviors as well as make sure that proper convergence and dispersion mechanism are in place in Carrier Aggregated Long Term Evolution (LTE) networks supporting MBMS. 
         [0008]    In accordance with an embodiment of the present disclosure, a method of managing cell reselection for a User Equipment (UE) in an idle mode connected to a wireless network system is provided. The method includes determining system information of available cells on a given frequency, determining the system information from a plurality of cells and frequencies to determine which of the plurality of cells support MBMS, determining a MBMS Control Channel (MCCH) of cells that support the MBMS, generating a list of cells by prioritizing the plurality of cells that support the MBMS over other frequencies or cells in a ranking order, and reselecting a cell or a frequency supporting the MBMS before starting a MBMS session from among the generated list to be a cell wherein the MBMS session is provided. 
         [0009]    In accordance with another embodiment of the present disclosure, an apparatus is provided. The apparatus includes a processor, a memory connected to the processor, the memory including a cell reselection management module, wherein the cell reselection management module is configured to determine system information of available cells on a given frequency, determine the system information from a plurality of cells and frequencies to determine which of the plurality of cells support a MBMS, determine a MCCH of the plurality of cells that support the MBMS, generate a list of cells by prioritizing the plurality of cells that support the MBMS over other frequencies or cells in a ranking order, and reselect a cell or a frequency supporting the MBMS before starting a MBMS session from among the generated list to be a cell where the MBMS session is provided. 
         [0010]    In order to address the above problems, this present disclosure discusses idle mode specific aspects related to MBMS service continuity, in particular this present disclosure covers aspects covering the issue of convergence, dispersion and prioritization of cells when the user equipments are in idle mode. 
         [0011]    Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the present disclosure. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS  
         [0012]    The above and other aspects, features, and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
           [0013]      FIG. 1  illustrates a block diagram of a network system according to an embodiment of the present disclosure. 
           [0014]      FIG. 2  illustrates a Multimedia Broadcast in Single Frequency Network (MBSFN), an extension of a Long Term Evolution (LTE) network system according to an embodiment of the present disclosure. 
           [0015]      FIG. 3  illustrates User Equipments (UEs) latching on to a carrier in a LTE network system capable of providing Multimedia Broadcast Multicast Service (MBMS) according to an embodiment of the present disclosure. 
           [0016]      FIG. 4  illustrates congestion of a plurality of UEs using MBMS provided via a carrier in a LTE network system according to an embodiment of the present disclosure. 
           [0017]      FIG. 5A  illustrates a method of latching on to a cell or an evolved Node B (eNB) in a LTE network system according to an embodiment of the present disclosure. 
           [0018]      FIG. 5B  illustrates a method of latching on to a cell or an eNB in a LTE network system according to an embodiment of the present disclosure. 
           [0019]      FIG. 5C  illustrates a method of establishing a MBMS session with a cell or an eNB in a LTE network system according to an embodiment of the present disclosure. 
           [0020]      FIG. 5D  illustrates a method of establishing a MBMS session with a cell or an eNB in a LTE network system according to an embodiment of the present disclosure. 
           [0021]      FIG. 5E  illustrates a method of prioritizing and selecting a cell or an eNB in a LTE network system according to an embodiment of the present disclosure. 
           [0022]      FIG. 5F  is a flow chart illustrating a method of cell selection management according to an embodiment of the present disclosure. 
           [0023]      FIG. 5G  is a flow chart illustrating a method of cell selection management according to an embodiment of the present disclosure. 
           [0024]      FIG. 6  illustrates an exploded view of a UE according to an embodiment of the present disclosure. 
           [0025]      FIG. 7  illustrates an exploded view of an eNB according to an embodiment of the present disclosure. 
       
    
    
       [0026]    Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. 
       DETAILED DESCRIPTION  
       [0027]    The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, description of well-known functions and constructions may be omitted for clarity and conciseness. 
         [0028]    The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purpose only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents. 
         [0029]    It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. 
         [0030]      FIG. 1  illustrates a block diagram of a network system according to an embodiment of the present disclosure. 
         [0031]    A network system  100  includes a User Equipment (UE)  102  that is capable of approaching more than one of cells  106 A,  106 B,  106 C,  106 D, and  106 E, which may also be referred to as evolved Node Bs (eNBs)  106 A,  106 B,  106 C,  106 D, and  106 E, to obtain a Multimedia Broadcast Multicast Service (MBMS). For example, the network system  100  can be a Long Term Evolution (LTE) network. The UE  102  establishes an idle mode data transfer link to at least one of the cells  106 A,  106 B, and  106 C, through at least one of a network connection  104 . More preferably, the network connection  104  is a wireless network happening between cell and a mobile communication device, such as the UE  102 . It is to be noted that not all of the eNBs  106 A,  106 B,  106 C,  106 D, and  106 E, are capable of providing MBMS in a LTE network. 
         [0032]      FIG. 2  illustrates a Multimedia Broadcast in Single Frequency Network (MBSFN), an extension of a LTE network system according to an embodiment of the present disclosure. 
         [0033]    A MBSFN  200  has a network architecture that provides a MBMS session over a single frequency in a network system such as the LTE network system. The MBFSN  200  includes an eNB  202 , which may also be referred to as, or be, a cell  202  or a base station  202 , a LTE internal control plane interface, which is referred to as M2  204 , a user plane interface, which is referred to as M1  206 , a Multicast Coordination Entity (MCE)  208 , a control plane interface between a LTE network and an Evolved Packet Core (EPC), which is referred to as M3  210 , a Mobility Management Entity (MME)  212 , and a MBMS Gateway  214 . 
         [0034]    The above mentioned terms are standard terminology used in an LTE type of network system and is known to the person skilled in the art. 
         [0035]      FIG. 3  illustrates UEs latching on to a carrier in a LTE network system capable of providing Multimedia Broadcast Multicast Service (MBMS) according to an embodiment of the present disclosure. 
         [0036]    Latching  300  is performed by the UE  102  at a carrier  302  in accordance with an embodiment of the present disclosure. The carrier  302  includes an uplink  312 , and a downlink  314 . The combination of a plurality of carriers, including the carrier  302  and carriers  304 ,  306 , and  308 , may form bandwidth  310 . This combination of a number of carriers may also be referred to as carrier aggregation. In LTE networks, carrier aggregation allows expansion of effective bandwidth delivered to a user terminal through concurrent utilization of radio resources across multiple carriers. Multiple component carriers are aggregated to form a larger overall transmission bandwidth, such as the bandwidth  310 . For example, two or more component carriers can be aggregated to support wider transmission bandwidths up to 100 MHz. In an embodiment of the present disclosure, in LTE networks, when carrier aggregation is enabled there is a possibility of MBMS being deployed on at least one supported band. 
         [0037]      FIG. 4  illustrates congestion of a plurality of UEs using MBMS provided via a carrier in a LTE network system, in accordance with an embodiment of the present disclosure. 
         [0038]    When at least one UE  102 , such as a plurality of UEs  102  as shown in  FIG. 4 , try to latch on to a carrier, such as the carrier  302 , a congestion  400  may occur. For example, the congestion  400  may imply that a number of UEs  102  that can be accommodated within the carrier is exceeded. 
         [0039]    For example, when the MBMS transmissions are scheduled in only one bandwidth or a cell, the UEs  102  that are in the idle mode and that would like to receive the MBMS service would like to camp onto the cell and/or frequency that supports MBMS services. This can lead to more UEs being camped onto a cell and/or frequency that supports MBMS rather than the UEs being camped onto cells that do not support MBMS. Such scenarios may lead to congestion of certain cells and/or frequencies with respect to other cells and/or frequencies. 
         [0040]      FIG. 5A  illustrates a method of latching on to a cell or eNB in a LTE network system according to an embodiment of the present disclosure. 
         [0041]    A latching method  500 A denotes latching of the UE  102  to the eNB  106 A according to an embodiment of the present disclosure. A session of Multimedia Broadcast Multicast Service (MBMS), or in other words, a read session is started at operation  504 . The UE  102  sends a MBMS request to access the MBMS session in the eNB  106 A at operation  506 . The eNB  106 A responds, at operation  508 , with carrier information where the MBMS session is provided in the bandwidth spectrum to the UE  102 . The user equipment  102 , after operation  508 , latches on to a MBMS carrier of the eNB  106  to access the MBMS session. 
         [0042]      FIG. 5B  illustrates another method of latching on to a cell or an eNB in a LTE network system according to an embodiment of the present disclosure. 
         [0043]    Another latching method  500 B illustrates the UE  102  latching on to the eNB  106 A according to an embodiment of the present disclosure. The UE  102  sends a MBMS request for accessing a MBMS session to the eNB  106 A at operation  506 . The eNB  106 A redirects the MBMS request to the eNB  106 B, which is included in the LTE network system, at operation  512 . The redirection of the MBMS request may be performed owing to unavailability of MBMS or incompatibility at the eNB  106 B. At operation  512 A, an information notice, or in other words, a notification, on redirection of the MBMS request may be sent to the UE  102 . The eNB  106 B sends carrier information such that the UE  102  receives the MBMS carrier information at operation  514 . The UE  102  latches on to the MBMS carrier, as provided by the eNB  106 B, to access the MBMS session in operation  510 . 
         [0044]      FIG. 5C  illustrates a method of establishing a MBMS session with a cell or an eNB in a LTE network system according to an embodiment of the present disclosure. 
         [0045]    A MBMS session establishment method  500 C denotes establishment of a MBMS session between the UE  102  and the eNB  106 B in an embodiment of the present disclosure. The UE  102  latches on to a MBMS service carrier of the eNB  106 B at operation  510 . At operation  516 , the eNB  106 B determines whether the UE can be accommodated on the MBMS service carrier, or in other words, determines whether the eNB  106 B will be able to accommodate the UE  102 . If the eNB  106 B can accommodate the UE  102 , then a MBMS session acceptance signal is sent to the UE  102  at operation  518 . The MBMS session is established at operation  520 . 
         [0046]      FIG. 5D  illustrates another method of establishing MBMS session with a cell or an eNB in a LTE network system according to an embodiment of the present disclosure. 
         [0047]    Another MBMS session establishment method  500 D illustrates establishing a MBMS session between the UE  102  and the eNB  106 C. At operation  510 , the UE  102  latches on to a MBMS service carrier of the eNB  106 B. At operation  516 , the eNB  106 B determines if the eNB  106 B can accommodate the UE  102  using the MBMS service carrier hosting the MBMS session. A latching rejected notification is sent to the user equipment  102  at operation  522 A. Thereafter, at operation  522 B, a latching request, to access MBMS session and sent from the UE  102 , is redirected to the eNB  106 C. At operation  518 , a MBMS session acceptance signal is sent to the UE  102  from the eNB  106 C. At operation  520 , a MBMS session is established between the UE  102  and the eNB  106 C. 
         [0048]      FIG. 5E  illustrates a method of prioritizing and selecting a cell or an eNB in a LTE network system according to an embodiment of the present disclosure. 
         [0049]    At operation  524 , the UE  102  accesses MBMS capability information of the eNBs  106 C,  106 D, and  106 E, which are included in the LTE network system. At operation  526 , a selection priority criterion is applied to the eNBs  106 C,  106 D, and  106 E. At operation  528 , a ranking of cells, which respectively corresponding to the eNBs  106 C,  106 D, and  106 E, is performed based on an outcome of applying the selection priority criterion in operation  526 . Thereafter, at operation  530 , at least one eNB with a highest rank, from among at least one of the eNBs  106 C,  106 D, and  106 E, is reselected, or in other words, a cell is reselected in operation  530 . In operation  532 , a MBMS session is established between the UE  102  and the eNB having the highest rank from among the eNBs  106 C,  106 D, and  106 E, for example the eNB  106 C. 
         [0050]    According to an embodiment of the present disclosure, the UE  102  trying to establish a MBMS session may randomly select a target cell or eNB, from among the eNBs  106 A,  106 B,  106 C,  106 D, and  106 E. However, during such a random selection, the selected eNB may not have a MBMS session capability. Then, the UE  102  performs random reselection again to find a suitable eNB. 
         [0051]      FIG. 5F  is a flow chart illustrating a method of cell selection management according to an embodiment of the present disclosure. 
         [0052]    At operation  534 , the UE  102  reads, or in other words, determines, all the cells in a frequency. At operation  536 , a ranking is performed on the cells to determine a first cell for latching or camping. At operation  538 , the UE  102  selects the first cell suitable for idle mode camping on a given frequency upon determining the first cell to be a highest ranked cell. At operation  540 , the UE  102  camps on to the first cell. At operation  542 , the UE  102  reads, or in other words, determines, the system information of other cells in different frequencies to know if the other cells in the other frequencies support MBMS service. At operation  544 , the UE  102  determines which cell, from among the other cells of operation  542 , is suitable for MBMS service. The UE  102  for example, determines the information about which frequency supports the MBMS service, and in one example, the UE  102  determines the information about which frequency supports the MBMS service through the electronic program guide that could be made available to the UE  102  during the “service announcement” phase and/or procedure. At operation  546 , the UE  102  determines whether a second cell satisfies suitability criteria, or in other words and/or additionally, determine whether the second cell is providing the MBMS service better than the first cell. At operation  548 , the UE  102  camps on to the second cell, or in other words, if suitable, the UE  102  selects the MBMS cell, even if the MBMS cell is not the best cell, just before the start of the MBMS session. The reselection performed in the operations above is done regardless of S search parameters and Qhyst parameters, at times. Here the Qhyst parameters may include a hysteresis value for ranking criteria. The Ssearch parameters may include SIntraSearchP, which specifies a Srxlev threshold (in dB) for intra-frequency measurements, SIntraSearchQ, which specifies a Squal threshold (in dB) for intra-frequency measurements, SnonIntraSearchP, which specifies the Srxlev threshold (in dB) for LTE inter-frequency and inter-RAT measurements, and SnonIntraSearchQ, which specifies the Squal threshold (in dB) for E-UTRAN inter-frequency and inter-RAT measurements. According to another embodiment, the reselection may be performed randomly to select a better cell. 
         [0053]      FIG. 5G  is a flow chart illustrating a method of cell selection management according to an embodiment of the present disclosure. 
         [0054]    Upon the stop of a MBMS session, a dispersion mechanism is applied if frequencies or cells are found to be of equal priority and if a UE had earlier prioritized a MBMS cell or a frequency, at operation  550 . At operation  552 , a highest ranked frequency is selected without considering the sSearch parameters and the Qhyst parameters. 
         [0055]      FIG. 6  illustrates an exploded view of a UE according to an embodiment of the present disclosure. 
         [0056]    The UE  102  includes a processor  602 , a communication interface  604 , a bus  606 , memory  608 , a Read Only Memory (ROM)  610 , a transmitter  612 , and a receiver  614 . 
         [0057]    The processor  602 , as used herein, may be any type of computational circuit, such as, but not limited to, a microprocessor, a microcontroller, a Complex Instruction Set Computing (CISC) microprocessor, a Reduced Instruction Set Computing (RISC) microprocessor, a Very Long Instruction Word (VLIW) microprocessor, an Explicitly Parallel Instruction Computing (EPIC) microprocessor, a graphics processor, a digital signal processor, or any other type of processing circuit and/or hardware element that may perform information processing. The processor  402  may also include embedded controllers, such as generic or programmable logic devices or arrays, application specific integrated circuits, single-chip computers, smart cards, and the like. 
         [0058]    In an embodiment of the present disclosure, the memory  604  includes a cell selection management module  616  capable of performing all the operations performed in  FIGS. 5A to 5E  by the UE  102 . 
         [0059]    The memory  604  may be volatile memory and/or non-volatile memory. A variety of computer-readable storage media may be stored in and accessed from the memory elements. Memory elements may include any suitable memory devices for storing data and machine-readable instructions, such as a ROM, a Random Access Memory (RAM), an Erasable Programmable Read Only Memory (EPROM), an Electrically EPROM (EEPROM), a hard drive, a removable media drive for handling memory cards, Memory Sticks™, and the like. 
         [0060]    Various embodiments of the present disclosure may be implemented in conjunction with modules, including functions, procedures, data structures, and application programs, for performing tasks, or defining abstract data types or low-level hardware contexts. Machine-readable instructions stored on any of the above-mentioned storage media may be executable by the processor  602 . 
         [0061]      FIG. 7  illustrates an exploded view of an eNB according to an embodiment of the present disclosure. 
         [0062]    The eNB  106  includes a processor  702 , a communication interface  704 , a bus  706 , a memory  708 , a ROM  710 , a transmitter  712 , and a receiver  714 . 
         [0063]    The memory  708  includes the cell selection management assisting module  716 , which is configured to work with the UE  102  to assist and/or facilitate in selection of an appropriate cell or eNB, such as the eNBs  106 A,  106 B,  106 C,  106 D, and  106 E, in accordance with an embodiment of the present disclosure. Further, the eNB  106 , according to an embodiment of the present disclosure is capable of performing all the operations at the eNB end as mentioned in the  FIGS. 5A to 5E . 
         [0064]    While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.