Abstract:
The present disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates beyond 4G system. A method for controlling transmission of code words during handover including a plurality of BSs includes receiving an SINR associated with a UE served by any one of the BS, wherein the UE is associated with a plurality of coordinated transmission modes indicating whether the UE receives a complete code word from the BSs or a partial code word from the BSs or a combination of the complete code word from some of the BSs and the partial code word from other set of BSs based on a coordinated transmission threshold criteria. Further, the method includes determining whether the SINR meets the coordinated transmission threshold criteria to select the coordinated transmission mode for transmission of the code word from the BSs to the UE.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY 
       [0001]    The present application is related to and claims the benefit under 35 U.S.C. §119(a) of an Indian patent application filed on Nov. 28, 2014 in the Intellectual Property of India and assigned Serial number 5974/CHE/2014, a Korean patent application filed on Apr. 8, 2015 in the Korean Intellectual Property Office and assigned Serial number 10-2015-0049917, the entire disclosures of which are hereby incorporated by reference. 
       TECHNICAL FIELD 
       [0002]    The present disclosure generally relates to wireless communication systems and more particularly to a handover of a user equipment (UE) to a plurality of base stations (BSs). 
       BACKGROUND 
       [0003]    To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’. 
         [0004]    The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems. 
         [0005]    In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (COMP), reception-end interference cancellation and the like. 
         [0006]    In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed. 
         [0007]    Generally, handover (HO) is an important procedure in a cellular transmission as it enables service continuity within a same radio access technology (RAT) or across different RATs. In existing systems, a hard HO and a soft HO are available for a UE to switch from a source base station to a target base station; thereby, maintaining the continuity of service. In soft HO, the UE receives downlink data from multiple BS while the HO procedure is being followed i.e., during the time of HO; the UE has the radio link with both the source base station and the target base station. If the UE is connected to two (or multiple) BSs during the HO then the UE will receive complete code word from the source and target base station as indicated in  FIG. 1A . 
         [0008]    In hard HO, the UE has to break the radio link with the source base station before the new radio link can be established with the target base station i.e., at any point of time the UE has the radio link with only one base station as indicated in  FIG. 1B . In the hard HO, particularly in Global System for Mobile Communications (GSM), Long Term Evolution (LTE) and inter-frequency HO in Code division multiple access (CDMA) based technologies, when the UE meets the HO condition then the UE will transmit measurement reports of a signal strength of the neighbor BS whose signal strength is improving when compared to the source BS. Based on the reports, the source BS will provide the radio link details of the target BS to the UE. The UE will break the link with the source BS and establish the new link with the target BS. The hard HO of Long Term Evolution (LTE) is one of the causes for ping-pong effect that leads to an overhead in signaling. To mitigate ping-pong effect, one possible solution is to have a joint transmission during HO. The joint transmission of a complete code word from the serving and target base stations during the HO will increase the usage of scarce spectrum resources and decrease the overall cell spectral efficiency. 
         [0009]    The joint processing from the multiple BSs can be in the form of dynamic point switching (DPS); wherein, only one BS can transmit to the UE at a given time instant or joint transmission (JT); wherein, all the BSs in the transmission set transmit the same data to the UE simultaneously. In both the modes of transmissions, data packet for the UE is available at all the BSs in the transmitting set. The JT is more attractive in light of the link fragility in mm-wave systems. Due to the link fragility, soft handover will be preferred in comparison to hard handover. In currently known soft handover schemes, complete data is transmitted by a plurality of BSs that participate in the HO procedure. Thus, there is an overhead both during transmission of data as well as during HO. Considering the link fragility of mm-wave systems and the necessity for small cells, the number of handovers will increase. Consequently, due to the overhead during handover and increased number of handovers, the system throughput will decrease significantly. 
         [0010]    The above information is presented as background information only to help the reader to understand the present disclosure. Applicants have made no determination and make no assertion as to whether any of the above might be applicable as Prior Art with regard to the present application. 
       SUMMARY 
       [0011]    To address the above-discussed deficiencies, it is a primary object to provide a method and system for controlling transmission of code words during handover in a wireless network. 
         [0012]    Another object of the embodiments herein is to provide a plurality of coordinated transmission modes indicating whether a user equipment (UE) receives a complete code word from a base station (BS) or a partial code word from a BS or a combination of complete code word from some BS and partial code word from other set of BS based on a coordinated transmission threshold criteria. 
         [0013]    Embodiments herein provide a method for controlling transmission of code words during handover or otherwise in a wireless network including a plurality of base stations (BSs). The method includes receiving a signal-to-interference-plus-noise ratio (SINR) associated with a user equipment (UE) served by the BS, wherein the UE is associated with a plurality of coordinated transmission modes indicating whether the UE receives a complete code word from the BS or a partial code word from the BS or a combination of complete code word from one or more BSs and partial code word from other set of BSs based on a coordinated transmission threshold criteria. Further, the method includes determining whether the SINR meets the coordinated transmission threshold criteria to select the coordinated transmission mode for transmission of the code word from the BS to the UE. 
         [0014]    Embodiments herein provide a system for controlling transmission of code words during handover or otherwise in a wireless network including a plurality of base stations (BSs), wherein each of the BS includes a controller configured to receive a signal-to-interference-plus-noise ratio (SINR) associated with a user equipment (UE) served by the BS, wherein each of the BS is associated with a plurality of transmission modes indicates whether each of the BS transmit one of a complete code word and a partial code word to the UE based on a coordinated transmission threshold criteria. Further, the controller configured to determine whether the SINR meets the coordinated transmission threshold criteria to select the coordinated transmission mode for transmission of the code word from the BS to the UE. 
         [0015]    Herein, the SINR corresponds to an example of channel quality information and another kind of channel quality information such as a carrier to interference plus noise ratio (CINR) can be applied to the SINR. 
         [0016]    These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications can be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications. 
         [0017]    Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts: This disclosure is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which: 
           [0019]      FIGS. 1A and 1B  illustrate a handover mechanism in mobile communication systems; 
           [0020]      FIG. 2  illustrates a high level overview of a system for controlling transmission of code words to a UE, according to embodiments as disclosed herein; 
           [0021]      FIG. 3  illustrates various modules in a BS  104  or a BS  106 , according to embodiments as disclosed herein; 
           [0022]      FIG. 4  illustrates various modules in a UE  102  according to an embodiment of the present disclosure; 
           [0023]      FIG. 5  illustrates an example scenario of state transition for controlling transmission of code words to a UE during one or more coordinated transmission modes, according to embodiments as disclosed herein; and 
           [0024]      FIG. 6  is a flow diagram illustrating a method for controlling transmission of code words during handover or otherwise in a wireless network, according to embodiments as disclosed herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIGS. 1 through 6 , discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged telecommunication technologies. The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The term “or” as used herein, refers to a non-exclusive or, unless otherwise indicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein. 
         [0026]    The embodiments herein disclose a method and system for controlling transmission of code words for handover or otherwise in a wireless network including a plurality of base stations (BSs). The method includes receiving a signal-to-interference-plus-noise ratio (SINR) associated with a UE served by one or more BSs. The BSs are associated with a plurality of coordinated transmission modes. The coordinated transmission mode indicates whether each of the BS transmits a complete code word or a partial code word to the UE based on transmission threshold criteria. Further, the method includes determining whether the SINR meets the coordinated transmission threshold criteria to select one or more coordinated transmission modes for transmission of the code word from the BSs to the UE. In an embodiment, the coordinated transmission threshold criteria include a time criteria. Herein, the SINR corresponds to an example of channel quality information and another kind of channel quality information such as a carrier to interference plus noise ratio (CINR) can be applied to the SINR. 
         [0027]    The method and system described herein is simple and robust for controlling transmission of code words for handover in the wireless network. 
         [0028]    Unlike conventional systems, the resources are conserved and the signaling overhead is decreased. The handover is no longer limited to changing the serving BS for the UE. During the handover with joint transmission, the length of the code word transmitted by each of the BS is not same. The handover is similar to the soft handover with the difference being that the length of the code word transmitted by the multiple BSs is not same. For example, if one BS transmits the complete code word and the other BS transmits a function of the code word whose length is less than that of the complete code word; thereby achieving a significant decrease in the DL transmission overhead. 
         [0029]    Referring now to the drawings, and more particularly to  FIGS. 2 through 5 , where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments. 
         [0030]      FIG. 2  illustrates a high level overview of a system  200  for controlling transmission of code words to a UE, according to embodiments as disclosed herein. In an embodiment, the system  200  can be configured to include a UE  102 , a base station (BS)  104 , and a base station (BS)  106 . 
         [0031]    The UE  102  described herein can be for example but not limited to a mobile phone, a mobile station, a smart phone, a personal digital assistants (PDAs), a tablet, a phablet, or any other electronic device. The UE  102  can be configured to get served by the BS  104  through a “link-A” and the BS  106  through a “link-B” in the downlink as shown in the  FIG. 2 . 
         [0032]    The BS  104  and BS  106  forms the transmission set for transmitting either complete or partial code words to the UE  102 . The BS  104  and BS  106  can send code words to the UE  102  through the “link-A” and “link-B”. For the purpose of transmission to the UE  102 , the transmission set can have a leader called as master BS (not shown). In an embodiment, the master BS can either be one among the transmission set (i.e. either the BS  104  or the BS  106 ) or it can be distinct from the BS  104  and the BS  106  in the transmission set. The BS  104  and BS  106  can be configured to be associated with a plurality of coordinated transmission modes. Here, the coordinated transmission modes indicate whether each of the BS  104  and BS  106  should transmit either the complete code word or the partial code word to the UE  102  based on the coordinated transmission threshold criteria. In an embodiment, the master BS can be required in a centralized scheduling for the UE  102 . In another embodiment, if a distributed scheduling is used then the master BS can be optional. 
         [0033]    The BS  104  and the BS  106  can be configured to receive the information regarding the SINR and other measurements data of the UE  102  through the centralized or distributed mechanism. For example, in the centralized mechanism, the information can be made available to either of the BS  104  and the BS  106 . Further, the BS  104  or the BS  106  can be configured to receive the SINR associated with the UE  102 . Further, the BS  104  or the BS  106  can be configured to determine whether the SINR meets the coordinated transmission threshold criteria to select the coordinated transmission mode for the transmission of the code words from the BS  104  and the BS  106  to the UE  102 . For example, in the coordinated transmission mode either BS  104  or the BS  106  can transmit a function of the partial code word or even the partial information corresponding to the function of a code word. In another coordinated transmission mode, either BS  104  or the BS  106  can transmit the complete code word to the UE  102 . For example, consider a scenario wherein 2 BSs (i.e. a first BS and a second BS) can serve the UE  102  either singly or jointly. The set of possible coordinated transmission modes are as follows: 
         [0034]    Only either of the first BS or the second BS transmits the complete code word to the UE  102 . 
         [0035]    Both the first BS and the second BS transmits the complete code word to the UE  102 . 
         [0036]    The first BS transmits the complete code word while the second BS transmits either partial code word or even the function of the original code word with the code word length being less than or equal to that transmitted by the first BS. 
         [0037]    Both the first BS and the second BS transmit only the partial code word. Again the partial code word can be part of the original code word or a function of the original code word with the length of the partial code word being strictly less than that of the complete code word. 
         [0038]    Further, the UE  102  can be configured to maintain a set of timer values and radio link failure (RLF) counters at the BS for the handover based on the selected coordinated transmission mode. The timer values to be satisfied for the UE  102  to transition from one coordinated transmission mode to the another coordinated transmission mode are disclosed below: 
         [0039]    S 12 : t 11  for all the BS that will transmit partial code word, t 12  for all the BS that will transmit complete code word
       S 13 : t 2      S 14 : t 3      S 21 : t 4      S 23 : t 5      S 24 : t 6      S 31 : t 7      S 32 : t 81  for all the BS that will transmit partial code word, t 82  for all the BS that transmit complete code word   S 34 : t 9          
 
         [0048]    The  FIG. 2  show a limited overview of the system  200  but, it is to be understood that another embodiment is not limited thereto. Further, the system  200  can include different BSs communicating among each other along with other hardware or software components. 
         [0049]      FIG. 3  illustrates various modules in a BS  104  or a BS  106 , according to embodiments as disclosed herein. In an embodiment, the BS  104  or BS  106  can be configured to include a receiver (Rx) module  302 , a controller module  304 , a storage module  306 , and a transmitter (Tx) module  308 . 
         [0050]    The Rx module  302  can be configured to receive the SINR associated with the UE  102  served by the BS  104  or the BS  106 . In an embodiment, the UE  102  is associated with one or more coordinated transmission modes indicating whether the UE  102  receives a complete code word from the BS, or a combination of complete code word from some BS and partial code word from other set of BS based on a coordinated transmission threshold criteria. Further, the Rx module  302  can be configured to send the received SINR associated with the UE  102  to the controller module  304 . On receiving the SINR, the controller module  304  can be configured to determine whether the SINR meets the coordinated transmission threshold criteria to select the coordinated transmission mode for transmission of the code words from the BS  104  or the BS  106  to the UE  102 . 
         [0051]    In an embodiment, determining whether the SINR meets the coordinated transmission threshold criteria to select the coordinated transmission mode for reception of the code word from the BS  104  or the BS  106  to the UE  102  includes determining whether the SINR is within the first coordinated transmission threshold by the controller module  304  where the first coordinated transmission threshold is associated with a first coordinated transmission mode from the one or more coordinated transmission modes. The first coordinated transmission mode is selected in after determining that the SINR is within the first coordinated transmission threshold and the first coordinated transmission mode allows the BS  104  and the BS  106  to transmit the complete code word to the UE  102 . 
         [0052]    In another embodiment, if the controller module  304  determines whether the SINR is within a second coordinated transmission threshold criteria after determining that the SINR exceeds the first coordinated transmission threshold where the second coordinated transmission threshold is associated with a second coordinated transmission mode from the plurality of coordinated transmission modes. The second coordinated transmission mode is selected after determining that the SINR is within the second coordinated transmission threshold and the second coordinated transmission mode allows BS  104  or the BS  106  to transmit the complete code word to the UE  102  and BS  104  or the BS  106  to transmit the partial code word to the UE  102 . 
         [0053]    In another embodiment, if the controller module  304  determines the SINR is within a third coordinated transmission threshold after determining that the SINR exceeds the second coordinated transmission threshold where the third coordinated transmission threshold is associated with a third coordinated transmission mode from the plurality of coordinated transmission modes. The third coordinated transmission mode is selected after determining that the SINR is within the third coordinated transmission threshold where the third coordinated transmission mode allows the BS  104  and the BS  106  to transmit the partial code word to the UE  102 . 
         [0054]    In another embodiment, the controller module  304  can be configured to select a fourth coordinated transmission mode after determining that the SINR exceeds the third coordinated transmission threshold where the fourth coordinated transmission mode allows only BS  104  or BS  106  to transmit the complete code word to the UE  102 . 
         [0055]    The storage module  306  can be configured to store coordinated transmission threshold criteria for each coordinated transmission mode. The storage module  306  can be configured to store control instructions to perform various operation. The Tx module  308  can be configured to transfer the complete or partial code words to the UE  102  based on the determined coordinated transmission mode. 
         [0056]    The  FIG. 3  show a limited overview of the BS  104  or the BS  106  but, it is to be understood that other embodiment is not limited thereto. Further, the BS  104  or the BS  106  can include any number of modules communicating among each other along with the other components of the system  200 . 
         [0057]    According to the described embodiment,  FIG. 4  illustrates various modules in a UE  102 . In the embodiment, the UE  102  can include an receiver (Rx) module  402 , a controller module  404 , a storage module  406 , and a transmitter (Tx) module  408 . 
         [0058]    The Rx module  402  receives a signal transmitted from another device. For example, the Rx module  402  can be configured to receive a complete code word or a partial code word according to a coordinated transmission mode from the BS  104  or the BS  106  in the UE  102 . The controller module  404  controls overall functions of the UE  102 . For example, the controller module  404  can receive and transmit a signal by controlling the Rx module  402  and the Tx module  408 . Further, the controller module  404  can store data in the storage module  406  and read the stored data. The storage module  406  is configured to store a control command for performing various operations. The Tx module  408  is configured to transmit the SINR to the BS  104  or the BS  106 . 
         [0059]    In the embodiment, the UE  102  is associated with one or more coordinated transmission mode representing whether the UE  102  receives a complete code word from the BS, whether the UE  102  receives a combination of the complete code word from one BS, and whether the UE  102  receives a partial code word from another BS set on the basis of a coordinated transmission threshold criteria. 
         [0060]      FIG. 4  illustrates a limited overview of the UE  102 . However, this should not be understood as a limitation of the embodiment. Also, the UE  102  can include a predetermined module which communicates with another element of the system  200 . 
         [0061]      FIG. 5  illustrates an example scenario of state transition for controlling transmission of code words to a UE during one or more coordinated transmission modes, according to embodiments as disclosed herein. In an embodiment, the different coordinated transmission modes during the handover procedure are described below as shown in the  FIG. 4 . The Y-axis represents increase in signal strength value. Here, X1, X2, X3, and X4 are the four coordinated transmission modes. Where:
       X1: Transmission of complete code word by all BSs for the UE;   X2: Transmission of partial code word by some BSs and complete code word by the rest of the BSs for the UE;   X3: Transmission of partial code word by all BSs for the UE; and   X4: Transmission of complete code word by only one BS in for the UE.       
 
         [0066]    Also, T1, T2, and T3 are the coordinated transmission threshold criteria&#39;s and delta is related to a bias value of a specific state. If the signal strength is very low then the BS  104  and the BS  106  will transmit the complete code word to the UE  102 . For example, if the SINR of the UE  102  is within the first coordinated transmission threshold “T1” where the first coordinated transmission threshold “T1” is associated with the first coordinated transmission mode “X1”, then the first coordinated transmission mode “X1” is selected which allows the BS  104  and BS  106  to transmit the complete code word to the UE  102 . Further, if the signal strength increases to the second coordinated transmission threshold “T2” exceeding the first coordinated transmission threshold “T1” (i.e., the SINR of the UE  102  is within a second coordinated transmission threshold “T2”) after determining that the SINR exceeds the first coordinated transmission threshold “T1” then the second coordinated transmission mode “X2” is selected allowing either the BS  104  or the BS  106  to transmit the complete code word to the UE  102  and allows either the BS  104  or the BS  106  to transmit the partial code word to the UE  102 . For example, in the second coordinated transmission mode “X2”, the BS  104  can transmit the complete code word to the UE  102  and the BS  106  can transmit the partial code word to the UE  102 . In another example, in the second coordinated transmission mode “X2”, the BS  104  can transmit the partial code word to the UE  102  and the BS  106  can transmit the complete code word to the UE  102 . 
         [0067]    If the signal strength increases to the third coordinated transmission threshold “T3” exceeding the second coordinated transmission threshold “T2” (i.e., the SINR of the UE  102  is within the third coordinated transmission threshold “T3”) after determining that the SINR exceeds the second coordinated transmission threshold “T2” then the third coordinated transmission mode “X3” is selected allowing the BS  104  and the BS  106  to transmit the partial code word to the UE  102 . Further, if the signal strength exceeds the third receive threshold “T3” (i.e., the SINR of the UE  102  exceeds the third coordinated transmission threshold “T3”), then the fourth coordinated transmission mode “X4” is selected allowing only the BS  104  or the BS  106  to transmit the complete code word to the UE  102 . For example, in the fourth coordinated transmission mode “X4”, only the BS  104  can transmit the complete code word to the UE  102 . In another example, in the fourth coordinated transmission mode “X4”, only the BS  106  can transmit the complete code word to the UE  102 . 
         [0068]    In another example, if the SINR of the UE  102  is within the first coordinated transmission threshold “T1” where the first coordinated transmission threshold “T1” is associated with the first coordinated transmission mode “X1”, then the first coordinated transmission mode “X1” is selected which allows the BS  104  and the BS  106  to transmit the complete code word to the UE  102 . Further, if the signal strength increases to the third coordinated transmission threshold “T3” exceeding the first coordinated transmission threshold “T1” and the second coordinated transmission threshold “T2” (i.e., the SINR of the UE  102  is within a third coordinated transmission threshold “T3”) after determining that the SINR exceeds the first coordinated transmission threshold “T1” and the second coordinated transmission threshold “T2” then the third coordinated transmission mode “X3” is selected allowing the BS  104  and the BS  106  to transmit the partial code word to the UE  102 . 
         [0069]    In an embodiment, the transition of the UE  102  from one coordinated transmission mode to the another coordinated transmission modes depend on the effective received SINR associated with the UE  102  after receiving the complete or partial code words from the BS  104  and the BS  106 . The effective received SINR (also called as post-processing SINR) depends on the length of the code word selected for the partial code word transmission and the number of BSs co-operating in the transmission of the code words. The notation SINRi denotes the averaged SINR at the UE from the BSi. For example, SINR1 denotes the averaged SINR at the UE  102  from the BS  104 . In another example, SINR2 denotes the averaged SINR at the UE  102  from the BS  106 . The method to determine the possible coordinated transmission modes and the length of the code word from each of the BS is disclosed below: 
         [0070]    By estimating the length of the code word from each BS (xi) that maximizes a utility function (f) as given below subject to the constraint that the length of each code word from all the BSs should be at least “l 1 ” and the number of BSs transmitting the data from |B| BS is less than “a” and “I” denotes the indicator function 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
                         
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         [0071]    Quantize the lengths to match that of the transport block size (TBS): 
         [0000]        {tilde over (x)}=Q ( x )  Equation 2
 
         [0072]    Obtain the effective SINR with the new quantized lengths: 
         [0000]      SNR c   =g ( {tilde over (x)} ,SINR 1 , . . . SINR |B| )  Equation 3
 
         [0073]    The effective SINR should satisfy the following conditions for transition from one coordinated transmission mode to another coordinated transmission mode: 
         [0074]    Complete code word by the BS: SINR C ≦T1. 
         [0075]    Partial code word by some BS and complete code word by the other BS: T1&lt;SINR C ≦T2. 
         [0076]    Partial code word by all BS: T2≦SINR C ≦T3. 
         [0077]    Complete code word by the BS: SINR C &gt;T3. 
         [0078]    The timer values for the transition of the UE from one coordinated transmission mode to another coordinated transmission mode should satisfy the conditions which are described in conjunction with the  FIG. 2 . 
         [0079]    In an embodiment, the conditions for each of the coordinated transmission modes (i.e., X1, X2, X3, and X4) are described below. Here, the BS1 can be BS  104  and the BS2 can be BS  106 . 
         [0000]        S   12 : SINR i   &lt;T 1∀ i   εB   1  
 
         [0000]        T 1≦SINR j   ≦T 2∀ j   εB   2  
 
         [0000]    
       
      
       B=B 
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         [0000]        B   1   ∩B   2 =θ
 
         [0000]        S   21 : SINR i   &lt;T 1−Δ 21   ∀iεB  
 
         [0000]        S   31 : SINR i   &lt;T 1−Δ 31   ∀iεB  
 
         [0000]        S   13   : T 2&lt;SINR i   &lt;T 3∀ iεB  
 
         [0000]        S   24 : SINR i   &gt;T 3+Δ 24  for at least one BS (say  i )
 
         [0000]        S   42   : T 1&lt;SINR i   &lt;T 2−Δ 42   ∀iεB   1  
 
         [0000]        T 1≦SINR i   &lt;T 3∀ jεB   2  
 
         [0000]    
       
      
       B=B 
       1 
       ∪B 
       2  
      
     
         [0000]        B   1   ∩B   2 =θ
 
         [0000]        S   43   : T 2&lt;SINR i   &lt;T 3−Δ 43   ∀iεB  
 
         [0000]        S   34 : SINR i   &gt;T 3 for at least one BS (say,  i ) 
         [0000]        S   14 : SINR i   &gt;T 3+Δ 14  for at least one BS (say,  i )
 
         [0000]        S   41 : SINR i   &lt;T 1−Δ 41   ∀iεB  
 
         [0000]        S   23 : SINR i   &lt;T 2≦ T 3∀ iεB  
 
         [0000]        S   32 : SINR i   &lt;T 2−Δ 32   ∀iεB  
 
         [0000]        T 2−Δ 32 &lt;SINR j   ≦T 3∀ jεB  
 
         [0000]    
       
      
       B=B 
       1 
       ∪B 
       2  
      
     
         [0000]        B   1   ∩B   2 =θEquation 4
 
         [0000]    where: 
         [0080]    S 12  indicates UE transition from the first coordinated transmission mode “X1” to the second coordinated transmission mode “X2” and S 21  indicates UE transition from the second coordinated transmission mode “X2” to the first coordinated transmission mode “X1”. 
         [0081]    S 13  indicates UE transition from the first coordinated transmission mode “X1” to the third coordinated transmission mode “X3” and S 31  indicates UE transition from the third coordinated transmission mode “X3” to the first coordinated transmission mode “X1”. 
         [0082]    S 14  indicates UE transition from the first coordinated transmission mode “X1” to the fourth coordinated transmission mode “X4” and S 41  indicates UE transition from the fourth coordinated transmission mode “X4” to the first coordinated transmission mode “X1”. 
         [0083]    S 23  indicates UE transition from the second coordinated transmission mode “X2” to the third coordinated transmission mode “X3” and S 32  indicates UE transition from the third coordinated transmission mode “X3” to the second coordinated transmission mode “X2”. 
         [0084]    S 24  indicates UE transition from the second coordinated transmission mode “X2” to the fourth coordinated transmission mode “X4” and S 42  indicates UE transition from the fourth coordinated transmission mode “X4” to the second coordinated transmission mode “X2”. 
         [0085]    S 34  indicates UE transition from the third coordinated transmission mode “X3” to the fourth coordinated transmission mode “X4” and S 43  indicates UE transition from the fourth coordinated transmission mode “X4” to the third coordinated transmission mode “X3”. 
         [0086]    In another embodiment, the average SINR is computed which is required to determine the coordinated transmission mode. For every sub-band (or entire band) that is to be allocated to the UE, the SINR across the reference symbols of the past N1 sub-frames (or minimum time-frequency unit of scheduling) spaced N2 sub-frames apart is taken into consideration. The average SINRi is computed as follows: 
         [0087]    (a) For UE speeds below v1 m/s, a sample average is taken by 
         [0000]    
       
         
           
             
               
                 
                   
                     S 
                      
                     
                         
                     
                      
                     I 
                      
                     
                         
                     
                      
                     N 
                      
                     
                         
                     
                      
                     
                       R 
                       i 
                     
                   
                   = 
                   
                     
                       ( 
                       
                         1 
                         
                           
                             N 
                             1 
                           
                            
                           
                             W 
                             1 
                           
                         
                       
                       ) 
                     
                      
                     
                       
                         ∑ 
                         
                           t 
                           = 
                           0 
                         
                         
                           W 
                           I 
                         
                       
                        
                       
                           
                       
                        
                       
                         S 
                          
                         
                             
                         
                          
                         I 
                          
                         
                             
                         
                          
                         N 
                          
                         
                             
                         
                          
                         
                           R 
                            
                           
                             ( 
                             
                               i 
                               - 
                               
                                 
                                   N 
                                   2 
                                 
                                  
                                 t 
                               
                             
                             ) 
                           
                         
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   5 
                 
               
             
           
         
       
     
         [0088]    where “I” indicates the index of the sub-frame, i−N2*a&gt;0, where 1&lt;a&lt;W. 
         [0089]    For the UE speeds between v1 and v2 m/s, if the coefficient of variation (ratio of standard deviation to mean) of the SINR samples (that are used in the summation in Eq. 1 above) is below a threshold value (i.e., coordinated transmission threshold criteria) t1, then the sample mean of the SINR is calculated as shown in Eq. 1 above. Otherwise, the median of the samples is reported. 
         [0090]    For speeds above v2 m/s, one of the following options can be chosen: 
         [0091]    Minimum SINR from the samples as shown in Eq. 1 above. 
         [0092]    In an embodiment, the effective SINR has to satisfy the value for a time period as given by the timer values as described in the Paragraph 0026. Here, the single value of the timer in the LTE will become a set of values of the timer depending on the BS in the transmission set and the signal strength at the UE from each of the BS in the transmission set. 
         [0093]    In an embodiment, if the signal strength decreases below a threshold Qout, the UE is the to enter a Radio Link Failure State (RLF). A single counter is used to count the number of RLF measurements. If the number of counts is satisfied, the UE has to initiate RRC Connection Re-establishment procedure. For the case of partial transmission of information, only if the RLF condition is satisfied from all BSs in the transmission set, the RLF is declared. Further, if there is “k” BSs in the transmission set, there are k different counters for, determining the RLF, each counter corresponding to the number of BSs that can actively transmit. Accordingly, there will be “k” thresholds for RLF. Only if the RLF condition is satisfied for the “k” thresholds using the corresponding counters, RLF is declared. 
         [0094]    In another embodiment, the HO method can be executed at the UE or can be executed at the BS, if the BS has adequate information. The UE estimates the effective received SINR from each BS to which it is connected during joint transmission. 
         [0095]    In another embodiment of the disclosure, all the Δk (k=1 to 7) can have the same values, possibly 0 too. The thresholds are for the SINR values averaged over suitable time or frequency. The decision for transition of the UE can be taken without consideration of the effective SINR. The time duration to check the signal strengths can be configured by the network or can be selected by the UE. 
         [0096]    Unlike conventional systems, the partial information transmission wherein one of the BS (i.e., either BS  104  or BS  106 ) can transmit only a portion of the code word for the UE  102  (possibly, even a function of the code word) and other BSs can transmit the complete code word and the partial to complete code word transmission by other BS are functions of the signal conditions reported by the UE  102 . The ping-pong effect of the soft-handover can be reduced and also decrease the number of resources used due to partial information transmission on the links is achieved. 
         [0097]      FIG. 6  is a flow diagram illustrating a method  500  for controlling transmission of code words during handover or otherwise in a wireless network, according to embodiments as disclosed herein. At step  502 , the method  500  includes receiving a SINR associated with the UE served by one or more base stations (BSs). The BSs can be associated with a plurality of coordinated transmission modes indicating whether the BSs transmit a complete code word or a partial code word to the UE based on transmission threshold criteria. The method  500  allows a controller module  304  in the BS to receive the SINR associated with the UE served the BSs. At step  504 , the method  500  includes determining whether the SINR is within the first coordinated transmission threshold. The first coordinated transmission threshold criteria can be associated with a first coordinated transmission mode from the plurality of coordinated transmission modes. The method  500  allows the controller module  304  to determine whether the SINR is within the first coordinated transmission threshold. 
         [0098]    If it is determined at step  506  that the SINR is within the first coordinated transmission threshold, then at step  508  the method  500  allows selecting the first coordinated transmission mode. The first coordinated transmission mode allows all the BSs to transmit the complete code word to the UE. The method  500  allows the controller module  304  to select the first coordinated transmission mode where all the BSs transmit complete code word to the UE. If it is determined at step  506  that the SINR exceeds the first coordinated transmission threshold, then at step  510  the method  500  includes determining whether the SINR is within the second coordinated transmission threshold. The second coordinated transmission threshold can be associated with a second coordinated transmission mode from the plurality of coordinated transmission modes. The method  500  allows the controller module  304  to determine whether the SINR is within the second coordinated transmission threshold. If it is determined at step  512  that the SINR is within the second coordinated transmission threshold and exceeds the first coordinated transmission threshold, then at step  514  the method  500  includes selecting a second coordinated transmission mode. The second coordinated transmission mode allows some BSs to transmit the complete code word to the UE and some BSs to transmit the partial code word to the UE. The method  500  allows the controller module  304  to select the second coordinated transmission mode which allows some BSs to transmit the complete code word to the UE and some BSs to transmit the partial code word to the UE. 
         [0099]    If it is determined at step  512  that the SINR exceeds the second coordinated transmission threshold, then at step  516  the method  500  includes determining whether the SINR is within a third coordinated transmission threshold. The third coordinated transmission threshold can be associated with a third coordinated transmission mode from the plurality of coordinated transmission modes. The method  500  allows the controller module  304  to determine whether the SINR is within the third coordinated transmission threshold. If it is determined at step  518  that the SINR is within the third coordinated transmission threshold and exceeds the second coordinated transmission threshold, then at step  520  the method  500  includes selecting the third coordinated transmission mode. The third coordinated transmission mode allows all the BSs to transmit the partial code word to the UE. The method  500  allows the controller module  304  to select the third coordinated transmission mode which allows all the BSs to transmit the partial code word to the UE. If it is determined at step  518  that the SINR exceeds the third coordinated transmission threshold, then at step  522  the method includes selecting a fourth coordinated transmission mode. The fourth coordinated transmission mode allows only one BS to transmit the complete code word to the UE. The method  500  allows the controller module  304  to select the fourth coordinated transmission mode allowing only one BS to transmit the complete code word to the UE. In an embodiment, the UE can be configured to maintain a set of timer values and the RLF counters at the BS for the handover based on the selected coordinated transmission mode. 
         [0100]    The various actions, acts, blocks, steps, and the like in method  500  can be performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some actions, acts, blocks, steps, and the like may be omitted, added, modified, skipped, and the like without departing from the scope of the disclosure. 
         [0101]    The embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the elements. The elements shown in  FIGS. 2 and 3  include blocks which can be at least one of a hardware device, or a combination of hardware device and software module. 
         [0102]    Although the present disclosure has been described with an exemplary embodiment, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.