Abstract:
A wireless transmit/receive unit (WTRU) ( 152 ) in a wireless communications system includes a transceiver ( 153 ) for transmitting and receiving data from a plurality of base stations ( 154, 156, 357 ) and a controller ( 151 ) communicatively coupled to the transceiver ( 153 ) and configured to adjust an operation mode of the transceiver ( 153 ). In the WTRU ( 152 ), adjusting comprises configuring the transceiver ( 153 ) to begin a radio link handover procedure responsive to receiving a handover (HO) command from a first of the plurality of base stations ( 154, 156, 357 ) over a first communications link, specifying a first time, and reconfiguring the transceiver ( 153 ) to begin a radio link interruption procedure responsive to an expiry of the first time prior to completion of the radio link handover procedure. In the WTRU ( 152 ), the radio link interruption procedure first attempts to re-establish the first communications link.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. provisional application No. 61/023,704 filed Jan. 25, 2008 and entitled “Consistent Radio Link Failure Procedure”, which is incorporated by reference as if fully set forth herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is related to wireless communication systems. More particularly, the present invention is related to a method and system for managing radio link failures in wireless systems. 
       BACKGROUND 
       [0003]    Long term evolution (LTE) is now being considered for next generation (3.9G) communications system for developing a new radio interface and radio network architecture that provides a high data rate, low latency, packet optimization, and improved system capacity and coverage. For proposed LTE systems, instead of using code division multiple access (CDMA), which is currently being used in 3G systems, orthogonal frequency division multiple access (OFDMA) and single-carrier frequency division multiple access (SC-FDMA) are proposed to be used in downlink and uplink transmissions, respectively. However, the use OFDMA and FDMA typically requires changes in handover procedures and related operations. Specifically, while in IS-95/CDMA2000 systems (based on CDMA technology) it is possible to have soft handovers (make a connection with a new base station before breaking connection with the current base station), this is not possible in LTE. LTE requires hard handovers where connection with the current base station must be broken before establishing connection with a new base station. 
         [0004]    Generally, the user equipment (UR) and associated base stations handle all necessary steps for seamless handover in the proposed LTE systems. These steps can include making an intra-LTE handover decision on a source network side, (i.e., control and evaluation of UP and evolved Node-B (eNB) measurements taking into account UE-specific area restrictions), preparing radio resources on a target network side, commanding the USE to interface with new radio resources, releasing radio resources on the source network side, and the like. The UE mobility management mechanism supports the transfer of context data between involved eNBs, and the update of node relations on a control plane (C-plane) and a user plane (U-plane). However, these proposed LTE systems typically do not provide robust procedures for managing radio link interruptions and/or failures during handover and other communications processes. 
       SUMMARY 
       [0005]    This Summary is provided to comply with 37 C.F.R. §1.73, presenting a summary of the invention briefly indicating the nature and substance of the invention. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 
         [0006]    In a first embodiment of the present invention, a wireless transmit/receive unit (WTRU) in a wireless communications system is provided. The WTRU can include a transceiver for transmitting and receiving data from a plurality of base stations and a controller communicatively coupled to the transceiver and configured to adjust an operation mode of the transceiver. In the WTRU, the adjusting comprises configuring the transceiver to begin a radio link handover procedure responsive to receiving a handover (HO) command from a first of the plurality of base stations over a first communications link, specifying a first time, and reconfiguring the transceiver to begin a radio link interruption procedure responsive to an expiry of the first time prior to completion of the radio link handover procedure. In the method, the radio link interruption procedure first attempts to re-establish the first communications link. 
         [0007]    In a second embodiment of the present invention, a method for handover of a wireless transmit/receive unit (WTRU) from a source base station to a target base station in a wireless communication system is provided. The method can include configuring the WTRU to begin a radio link handover procedure responsive to receiving a handover (HO) command from the source base station over a first communications link. The method can further include specifying a first time at the WTRU and reconfiguring the WTRU to begin a radio link interruption procedure responsive to an expiry of the first time prior to completion of the radio link handover procedure. In the WTRU, the radio link interruption procedure first attempts to re-establish the first communications link. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  shows a signaling diagram of handover process for LTE systems configured according to an embodiment of the present invention. 
           [0009]      FIG. 2A  is a signal diagram of router advertisement messaging using a dedicated preamble for identifying handover process interruptions according to an embodiment of the present invention. 
           [0010]      FIG. 2B  is a signal diagram of router advertisement messaging using a random preamble for identifying handover process interruptions according to another embodiment of the present invention. 
           [0011]      FIGS. 3A and 3B  show a signaling diagram of an intra-LIE radio link failure management process in accordance with yet another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    The present invention is described with reference to the attached figures, wherein like reference numerals are used throughout the figures to designate similar or equivalent elements. The figures are not drawn to scale and they are provided merely to illustrate the instant invention. Several aspects of the invention are described below with reference to example applications for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One having ordinary skill in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details or with other methods. In other instances, well-known structures or operations are not shown in detail to avoid obscuring the invention. The present invention is not limited by the illustrated ordering of acts or events, as some acts may occur in different orders and/or concurrently with other acts or events. Furthermore, not all illustrated acts or events are required to implement a methodology in accordance with the present invention. 
         [0013]    As used herein, a “wireless transmit/receive unit” or “WTRU” can include, but is not limited to any particular type of user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a computer, or any other type of user device capable of operating in a wireless environment. Also as used herein, an “eNB” includes but is not limited to a base station, an evolved Node-B, a site controller, an access point (AP), or any other type of interfacing device capable of operating and supporting communications in a wireless environment. Although the exemplary embodiments will be described in terms of a LTE system, the embodiments of the present invention are not limited in this regard and can be used with other types of communications systems and/or protocols for managing communications between any wireless communications system including a WTRU and an eNB. 
         [0014]    Embodiments of the present invention provide systems and methods for managing radio link failures, including radio link failures during handovers. In particular, the various embodiments of the present invention provide for managing handover failures using the same framework used for managing radio link failures and interruptions. That is, the WTRU can be configured to manage failures and interruptions during handover and non-handover processes in a consistent manner by implementing a timer/counter scheme for managing the handover process similar to timer/counter schemes for managing radio link failures during non-handover processes. 
         [0015]      FIG. 1  is a signal diagram for an exemplary handover process  100  in an LTE-based wireless communications system configured according to an embodiment of the present invention. As shown in  FIG. 1 , the WTRU  152  can include a transceiver  153  for communicating with the one or more eNBs and a controller  151  for configuring operation of the WTRU  152 , including operation of the transceiver  153 . The controller  151  can be configured to perform the one or more tasks for the WTRU  152  in process  100 , as well as any tasks required for processes  200 ,  250 , and  300  described below in more detail in  FIGS. 2A ,  2 B, and  3 , respectively. 
         [0016]    Referring back to  FIG. 1 , the handover process  100  can begin with a WTRU  152  and a source eNB  154  performing measurements and exchanging measurement reports (step  102 ). The source eNB  154  then makes a handover decision based on the measurement reports (step  104 ). The source eNB  154  can then send a handover request to a target eNB  156  (step  106 ). The handover decision and subsequent procedures before handover completion are performed without involving a mobility management entity/user plane entity (MME/UPE)  158 , (i.e., handover preparation messages are directly exchanged between the source eNB  154  and the target eNB  156 ). 
         [0017]    The target eNB  156  performs an admission control for the WTRU  152  (step  108 ). If the target eND  156  can accept the WTRU  152 , the target eND  156  sends a handover response to the source eNB  154  (step  110 ). The source eND  154  sends a handover command to the WTRU  152  (step  112 ). For seamless handover, a U-plane tunnel is established between the source eND  154  and the target eND  156 . 
         [0018]    The WTRU  152  and the target eNB  156  then exchange router advertisement (RA) messages (step  114 ). During handover execution, user data may be forwarded from the source eNB  154  to the target eND  156 . The forwarding may take place in a service dependent and implementation specific way. Forwarding of user data from the source eNB  154  to the target eND  156  should take place as long as packets are received at the source eND  154  from the UPE  158 . 
         [0019]    After a connection to the target eNB  156  is established, the WTRU  152  sends a handover complete message to the target eNB  156  (step  116 ). The target eND  156  sends a handover complete message to the MME/UPE  158  (step  117 ). The target eNB can also send the WTRU  152  a contention resolution message (step  118 ). The MME/UPE  158  then sends a handover complete acknowledgement (ACK) to the target eNB  156  (step  120 ). After the MME/UPE  158  is informed by the target eNB  156  that the WTRU  152  has gained an access at the target eNB  156  by the handover complete message, the U-plane path is switched by the MME/UPE  158  from the source eND  154  to the target eNB  156 . 
         [0020]    The release of the radio resources at the source eND  154  is triggered by a release resource message sent by the target eNB  156  (step  122 ). After receiving the release resource message from the target eNB  156 , the source eNB  154  releases the radio resources for the WTRU  152  (step  124 ). The WTRU  152  can optionally perform a location update with the MME/UPE  158  (step  126 ). 
         [0021]    Typically, handover from a source eNB to a target eNB proceeds without any interruption. However, in some cases, motion of the WRTU or external factors, such as weather conditions, interference from surrounding objects, or interference from other electrical messages, can interrupt the handover process. Therefore, in such cases, a WRTU may need to stop the handover process and revert to the source eNB or may lose a connection altogether and require reconnection to a communications system. Accordingly, the actions the WRTU can vary depending on the type of interruption or error being detected. Therefore, one aspect of the present invention provides for first monitoring and detecting handover process interruptions. 
         [0022]    The present Inventors have discovered that in the case of a dedicated preamble, once the routing advertisement (RA) messaging (step  114 , referring to  FIG. 1  described above) is completed, handover can be considered to have been completed and successful. That is, once a WRTU determines that it can upload and download data from a target eNB, the WTRU can determine that the handover has been completed. Accordingly, handover process interruptions can be detected by determining that the RA messaging was not completed within an allotted timeframe. However, depending on whether a dedicated or a random preamble is used, the point at which a handover can be considered complete can vary. 
         [0023]      FIG. 2A  shows a signal diagram for RA messages  200  using a dedicated preamble for detecting a handover process interruption according to an embodiment of the present invention. In a dedicated preamble scheme, a WTRU and an eNB communicate using uniquely assigned identifiers. That is, the eNB sends an indentifying token to WTRU, so that once the eNB receives this token from the WTRU in a communications from the WTRU, the eNB recognizes the source of the communications and sends confirmation immediately. Therefore, only uploading and downloading capabilities generally need to be confirmed. Therefore, as shown in  FIG. 2A , for handover using dedicated preamble, a handover can be considered complete at point  207  once RA messages have been exchanged between a target eNB  152  and a WTRU  156 . In embodiments of the present invention using a dedicated preamble, the target eNB  156  can first transmit a RA preamble assignment message indirectly to the WTRU  152 . That is, a message is first transmitted to the source eNB  154  in step  201 , which includes an the identifier for the WTRU  152  and a request for the source eNB  154  to forward the identifier to the target eNB  156 . Afterwards in step  202 , the source eNB  154  can forward a preamble assignment message to WTRU  152  (step  202 ) containing the identifier. Second, in response to the RA preamble assignment message, the WTRU  152  can transmit a random access preamble message (step  204 ). Third, the target eNB  156  can responsively transmit a random access response message (step  206 ). Therefore, if the WTRU  152  fails to receive the RA preamble assignment message or the random access response message, point  207  of the signal diagram is not reached (i.e., the WTRU  152  is unable to download data from the target eND  156 ) and the WTRU  152  can determine that an interruption of the handover process has occurred and that correction or recovery is needed. The present Inventors note that under many circumstances, a failure to reach point  207  in the signal diagram can occur. By way of example and not by way of limitation, one circumstance is that the target eNB  156  fails to detect the random access preamble message and consequently fails to generate the random access response message. That is, the WTRU  152  is unable to upload data to the target eNB  156 . 
         [0024]      FIG. 2B  shows a signal diagram for RA messages  250  using a random preamble for detecting a handover process interruption according to an embodiment of the present invention. In a random preamble scheme, a WTRU and an eNB communicate using randomly assigned identifiers. Therefore, since more than one WTRU could be assigned the same identifier, not only do uploading and downloading capabilities generally need to be confirmed, but also the identity of the proper WTRU (to which downloading has been enabled) needs to be confirmed. This is typically done at the WTRU by determining that a properly configured contention resolution message has been received after completion of step  118  (contention resolution), as shown in  FIG. 1 . That is, since the eNB has no idea of the identity of the WTRU, so the WTRU has to first send a request first for a token. Only after the eNB receives the request, will it assign the token back the requester. 
         [0025]    Therefore, as shown in  FIG. 2B , a handover can be considered complete at point  211  once a complete set of messages have been exchanged between a target eNB  156  and a WTRU  152  and a valid contention resolution message has been received at the WTRU  152 . In embodiments of the present invention using a random preamble, the target eNB  156  can first transmit a random access preamble message to the WTRU  152  (step  204 ), which provides the random identifier to the WTRU  152 . Second, in response to the random access preamble message, the eNB  156  can transmit a random access response message (step  206 ). Afterwards, the WTRU  152  can transmit the scheduled message (step  116 ), as previously described, which includes a message for the target eNB  156  that includes the identifier information for the WTRU  152  and that the handover is complete. Finally, the WTRU  152  confirms handover by receiving a contention resolution from the target eNB  156  that properly identifies the WTRU  152  (step  118 ), as previously described with respect to  FIG. 1 . 
         [0026]    Therefore, if the WTRU  152  fails to receive the random access response message or a contention resolution message, point  211  of the signal diagram is not reached (i.e., the WTRU  152  is unable to download data from the target eNB  156 ) and the WTRU  152  can determine that an interruption of the handover process has occurred and that correction or recovery is needed. The present Inventors note that a failure to reach point  211  in the signal diagram can also be caused by various circumstances. By way of example and not by way of limits, a failure can be caused by the target eNB  156  failing to detect the random access preamble message and consequently failing to generate the random access response message. That is, the WTRU  152  is unable to upload data to the target eNB  156 . Alternatively, a failure to reach point  211  in the signal diagram can also be caused by a failure of the WTRU  152  to receive a properly configured contention resolution message from the target eNB  156 . 
         [0027]    Regardless of the type of interruption, another aspect of the present invention provides detailed procedures for signaling and operations at a WTRU, a target eNB, a source eNB, an MME/UPE, and other eNBs in the case of intra-LTE handover process interruption. In particular, in the case of radio link failures, including handover process interruption, embodiments of the present invention attempt to access the target eNB, the source eNB, and other eND devices sequentially and according to a pre-determined timing. That is, after detection of any type of radio link problem or failure, a limited time is provided for the WTRU to contact an eNB and establish a radio link before attempting (again during a limited time) to establish a connection with another eNB to recover from the failure or problem or enter and idle state if no connection with any eNB can be established. Such an exemplary procedure is described below with respect to  FIGS. 3A and 3B . 
         [0028]      FIGS. 3A and 3B  show a signaling diagram of an intra-LTE handover process  300  for managing radio link failures in accordance with another embodiment of the present invention. Although the various embodiments of the present invention are described solely in terms of intra-LTE handover, the invention is not limited in this regard. Rather, the various embodiments of the present invention are equally applicable to recovery from any other type of radio link failures. In process  300 , as shown in  FIG. 3A , the WTRU  152  sends a radio resource control (RRC) measurement report to the source eNB  154  indicating the measured quality of signals from eNB  154  to WTRU  152  (step  302 ). The source eNB  154  makes a handover decision based on the measurement report and the result of its own measurement (step  304 ). The source eNB  154  then sends a handover (HO) request to a target eNB  156  (step  306 ). The target eNB  156  performs an admission control for the WTRU  152  (step  308 ). If the target eNB  156  can accept the WTRU  152 , the target eNB  156  sends a HO response to the source eNB  154  indicating that a handover should commence (step  310 ). The source eND  154  then sends an RRC reconfiguration or HO command to the WTRU  152  (step  312 ). The WTRU  152  can then begin the handover process (step  314 ). 
         [0029]    The HO command can include reconfiguration information including, but not limited to information for specifying RRC, radio link control (RLC), medium access control (MAC) and physical (PHY) layer. The HO command can also include information regarding timing adjustment when handing over from the source eNB  154  to the target eNB  156 , (i.e., whether the WTRU  152  should perform timing adjustment autonomously or using a random access channel (RACH) procedure. If a RACH is to be used, the information can also specify whether random or dedicated access signature will be used, or the like). The HO command can further include relative timing difference information between eNBs (or cells) for autonomous timing adjustment, information regarding initial radio resource scheduling procedure at the target eNB  156 , measurement information for the target eNB  156 , and the like. The information regarding the initial scheduling procedure at the target eNB  156  indicates whether a RACH access procedure should be used for a resource assignment request or the target eNB  156  can schedule resources for the WTRU  152  without receiving an explicit resource assignment request from the WTRU  152 . Alternatively, the measurement configuration and other configuration information can be sent to the WTRU  152  by the target eNB  156  after receiving a handover complete message from the WTRU  152 . 
         [0030]    In general, a U-plane tunnel can be established between the source eNB  154  and the target eNB  156  to provide a seamless handover. After sending the HO command in step  312 , the source eNB  154  can forward the user data to the target eNB  156 . The forwarding can take place in a service dependent and implementation specific way. 
         [0031]    Once a handover process has begun, the WTRU  152  can attempt to complete a handover process to a target eNB  156 . That is, the WTRU  152  can monitor the handover process to see if an upload and a download link have been established, as previously described in  FIGS. 2A and 2B  for dedicated and random preambles messages, respectively. However, in the various embodiments of the present invention, the WTRU  152  allows only a limited amount of time for completing the handover process. Therefore, when the handover process begins (step  314 ), a counter or timer in the WTRU  152  is also initiated to count down a pre-determined time (T_Handover) allotted for connecting and completing the handover process (step  316 ). Although any amount of time can generally be allotted for T_Handover, a short period can be used to provide a WTRU  152  user with seamless operation. For example, any time period between 50 and 200 ms can be used for a typical LTD communications system. Thus, as long as T_Handover has not elapsed, the WTRU  152  can repeatedly attempt to contact and reconnect with the target eNB  156  until a connection is established (step  317 ). If a handover is completed successfully at WTRU  152 , the WTRU  152  can attempt to complete the remainder of the handover process (step  318 ) to the target eNB as described in  FIG. 1  in steps  114 - 124 . 
         [0032]    In the various embodiments of the present invention, timers and counters can be used interchangeably. However, in some embodiments, synchronized timer and/or counters may be used by different elements in the wireless communications system to synchronize monitoring or execution of tasks. 
         [0033]    If the handover process is not completed within the allotted time (T_Handover), the WTRU  152  can determine that the interruption is a radio link problem between the WTRU  152  and the target eNB  156  and the method  300  can continue, as shown in  FIG. 3B . In the various embodiments of the present invention, the WTRU  152  attempts to recover from the radio link failure by halt the handover process and reestablishing the radio link between the source eNB  154  for the WTRU  152 . However, the radio link failure recovery process is also generally limited in time. That is, upon determining that any type of radio link failure has occurred, the WTRU  152  starts a second timer to count down a second pre-determined time (T 1 ) allotted for reestablishing the connection with the source eND  154  (step  320 ), as shown in  FIG. 3B . Similar as described above with respect to steps  317  and  318  in  FIG. 3A , the WTRU  152  can repeatedly attempt to contact and reestablish a connection with the source eND (step  322 ) for the duration of the second pre-determined time allotted (T 1 ). Although any amount of time can be allotted for T 1 , a short period can be used to provide a WTRU  152  user with seamless operation. For example, any time period between 50 and 200 ms can be used for a typical LTE communications system. Therefore, until the time allotted (T 1 ) elapses, the WTRU  152  can continue making attempts to reconnect with the source eNB  154 . If a reconnection is successful, the WTRU  152  can reinstate the original communications link with the source eNB  154  (step  324 ). 
         [0034]    In some cases, the WTRU  154  may be outside the range of the source eNB  154  or the source eNB  154  may be unavailable for other reasons. Accordingly, in such cases, the WTRU  154  can determine that the unavailability of both the source eNB  154  and the target eNB indicates that a radio link failure has occurred and that a new radio link needs to be established. Consequently, in some embodiments of the present invention, the WTRU  154 , upon determination of such any type of radio link failure, can attempt to re-establish a connection with any available eNB. Therefore, upon determining a radio link failure has occurred, the WTRU  152  starts a third timer to count down a third pre-determined time (T 2 ) allotted for establishing a connection with any of eNBs  154 ,  156 , and  357  (step  326 ). Subsequently or in combination with initiating the third timer, the WTRU  152  can repeatedly attempt to detect and establish a connection with any of eNBs  154 ,  156 , and  357  in communications range. Although any amount of time can be allotted for T 2 , a longer period than T, can be used to allow the WTRU  152  to locate at least one available eNB. For example, any time period between 0.5 and 10s can be used for a typical LTE communications system. Therefore, until the time allotted (T 2 ) elapses, the WTRU  152  can continue making attempts to contact one of eNBs  154 ,  156 , and  357 . 
         [0035]    The connection establishment procedure can proceed by first synchronizing a WTRU  152  with any of eNBs  154 ,  156 , and  357  by exchanging RA messages. In particular, the WTRU  152  can transmit a message specifying a random preamble (step  328 ) followed by a reply from the contacted one of eNBs  154 ,  156 , and  357 . The contacted eND can then transmit a RA response message to the WTRU  152  (step  330 ). The connection establishment process can then proceed by using an RRC re-establishment and re-configuration process, That is, an RRC re-establishment request can be transmitted from the WTRU  152  to the contact one of eNBs  154 ,  156 , and  357  (step  332 ). In response, the contacted one of eNBs  154 ,  156 , and  357  can transmit a RRC re-establishment message including a contention resolution (step  334 ) as previously described with respect to step  118  (contention resolution), as shown in  FIG. 1 . The WTRU  152  can then transmit back a message indicating receipt of a valid RRC contention resolution, indicating the RRC re-establishment has been completed (step  336 ). Afterwards, the contacted one of eNBs  154 ,  156 , and  357  can transmit a RRC reconfiguration message (step  338 ) to finalize the configuration of the WRTU  152 . Finally, the WTRU  152  can transmit a RRC reconfiguration complete message (step  340 ) to signal that the WRTU  152  is ready to receive data communications. Subsequently or in combination with steps  336  and  338 , the MME/UPE  158  can be notified of the U-plane path switch (step  342 ). 
         [0036]    Although steps  328 - 340  have been described in terms of a response to a radio link failure, the invention is not limited in this regard. In some embodiments, step  324  can also include the same or similar synchronization, re-establishment, and reconfiguration steps described in steps  328 - 340 . 
         [0037]    In some cases, the WTRU  152  can be outside the range or any of eNBs  154 ,  156 , and  357  or these eNBs may be otherwise unavailable. In such cases, the WTRU can determine that no connection is possible and that the WTRU  152  should change to a standby or idle mode. Therefore, in the various embodiments of the present invention, if the time allotted (T 2 ) expires and the WTRU  152  has been unable to establish a connection with one of eNBs  154 ,  156 , and  357 , WTRU  152  can switch to an RRC_IDLE mode. That is, the WTRU  152  switches to a standby mode in which it no longer attempts to connect with an eNB until requested by the user and/or an eNB is detected by the WTRU  152 . During such an idle state, no user place communication data will be exchanged. 
         [0038]    These are but a few examples. Accordingly, the breadth and scope of the present invention should not be limited by any of the above described embodiments. Rather, the scope of the invention should be defined in accordance with the following claims and their equivalents. 
         [0039]    Although the invention has been illustrated and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described components (assemblies, devices, circuits, systems, etc.), the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations of the invention. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description and/or the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” 
         [0040]    The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the following claims.