Patent Publication Number: US-2015078297-A1

Title: Method of resource allocation for device to device communication, user equipment using the same and base station using the same

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of U.S. provisional application Ser. No. 61/879,129, filed on Sep. 17, 2013. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of specification. 
    
    
     TECHNICAL FIELD 
     The present disclosure is directed to a method of resource allocation for device to device communication, a user equipment using the same method, and a base station using the same method. 
     BACKGROUND 
     Device to Device (D2D) or Peer to Peer (P2P) communication is a blossoming technology for future communication systems and enables user equipment (UE) to directly communicate with another without requiring a base station to relay user data in between. To multiplex among users for D2D communications, various schemes including time division multiplex (TDM) or frequency division multiplex (FDM) have been considered. TDM resource allocation could be utilized because of its simplicity, less inter-user interferences, single timing tracking, and so forth. The IEEE 802.11 for example applies the TDM solution. However, since the TDM solution applies to a whole band, transmission power is spread to the whole band and transmission range is limited to how large the bandwidth is applied. 
     Alternatively, the FDM approach may multiplex multiple users to use the same time slot by transmitting signals in different channels of a frequency spectrum with a narrower bandwidth used for each user. However, FDM would typically result in multi-user interferences. In particular, if a device receives two signals from two users for example, the larger received power may suppress the lower received power. 
     The other case related to D2D communication is the variation of signal arrival times for difference devices. As there are many D2D UEs with different inter-distances among different D2D UE pairs, each of the different D2D communication pairs would result in a different propagation delay. If propagation delays among D2D communication pairs are too large, extra receiver complexities may be necessary. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure is directed to a method of resource allocation for device to device (D2D) communication, a user equipment using the same method, and a base station using the same method. 
     In one of the exemplary embodiments, the present disclosure is directed to a method of resource allocation for D2D communication that is applicable to a user equipment. The method would include at least but not limited to receiving a group of wireless signals, receiving from the group of wireless signals a first signal that has a highest power, transmitting a second signal comprising the first signal that has the highest power, and receiving a D2D resource allocation based on the second signal in response to transmitting the second signal. The first signal detected with the highest power may belong to a synchronous head. 
     In one of the exemplary embodiments, the present disclosure is directed to a user equipment that includes at least but not limited to a transmitter for transmitting wireless signal, a receiver for receiving wireless signal, and a processor coupled to the transmitter and the receiver and is configured for receiving via the receiver a group of wireless signals, receiving from the group of wireless signals a first signal that has a highest power, transmitting via the transmitter a second signal comprising the first signal that has the highest power, and receiving via the receiver a device to device (D2D) resource allocation in response to transmitting the second signal. The first signal detected with the highest power may belong to a synchronous head. 
     In one of the exemplary embodiments, the present disclosure is directed to a method of resource allocation for D2D communication that is applicable to a base station. The method would include at least but not limited to receiving a group of wireless signals, wherein each of the group of wireless signals comprises a report, wherein the report comprises a set of signals which have been received, receiving from the group of wireless signals a first signal that has a highest power, and transmitting a second signal comprising a D2D resource allocation based on the first signal in response to receiving the group of wireless signals. The first signal detected with the highest power may belong to a synchronous head. 
     In one of the exemplary embodiments, the present disclosure is directed to a base station that includes at least but not limited to a transmitter for transmitting wireless signal, a receiver for receiving wireless signal, and a processor coupled to the transmitter and the receiver and is configured for receiving via the receiver a group of wireless signals, wherein each of the group of wireless signals comprises a report, wherein the report comprises a set of signals which have been received, receiving from the group of wireless signals a first signal that has the highest power, and transmitting via the transmitter a second signal comprising a D2D resource allocation based on the first signal in response to receiving the group of wireless signals. The first signal detected with the highest power may belong to a synchronous head. 
     In order to make the aforementioned features and advantages of the present disclosure comprehensible, exemplary embodiments accompanied with figures are described in detail below. It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the disclosure as claimed. 
     It should be understood, however, that this summary may not contain all of the aspect and embodiments of the present disclosure and is therefore not meant to be limiting or restrictive in any manner. Also the present disclosure would include improvements and modifications which are obvious to one skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. 
         FIG. 1  illustrates an exemplary system architecture for D2D communication in accordance with the present disclosure. 
         FIG. 2  illustrates an exemplary FDM multiplexed resource allocation scheme in accordance with the present disclosure. 
         FIG. 3  is an example that illustrates a composition of two discovery signals in the time domain. 
         FIG. 4A  &amp;  FIG. 4B  illustrates an exemplary user equipment in accordance with the present disclosure. 
         FIG. 5A  &amp;  FIG. 5B  illustrates an exemplary base station in accordance with the present disclosure. 
         FIG. 6A  &amp;  FIG. 6B  illustrates a general concept and resource allocation for D2D UE in accordance with one of the exemplary embodiments of the present disclosure. 
         FIG. 7A-FIG .  7 D illustrates a proposed reporting procedure in accordance with one of the exemplary embodiments of the present disclosure. 
         FIG. 8  illustrates placements of synchronous heads in accordance with one of the exemplary embodiments of the present disclosure. 
         FIG. 9  illustrates FDM based resource allocation according to a synchronous head in accordance with one of the exemplary embodiments of the present disclosure. 
         FIG. 10  illustrates TDM based resource allocation according to a synchronous head in accordance with one of the exemplary embodiments of the present disclosure. 
         FIG. 11  illustrates implicit resource allocation according to a synchronous head in accordance with one of the exemplary embodiments of the present disclosure. 
         FIG. 12  illustrates hierarchical synchronization in accordance with one of the exemplary embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS 
     Reference will now be made in detail to the present exemplary embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
     When operating under timing synchronous D2D communication, there could be different pairs of D2D UEs having different inter-distances. First of all, it has been well known that the near-far effect may induce signal imbalances which would cause various D2D UEs to suffer from signal suppression as the result of automatic gain control (AGC) and analog to digital (A/D) converter to further filter weaker discovery signals. Second, different inter-distances among D2D communication pairs may also introduce different timing propagation delays and the associated reception performance losses. In order to reduce the effects coming from different inter-distances, a resource allocation mechanism is necessary for device discovery. These aforementioned case could be further elaborated according to  FIG. 1˜FIG .  3  and their corresponding written descriptions. 
       FIG. 1  illustrates an exemplary system architecture for D2D communication in accordance with the present disclosure. A D2D communication system architecture  100  would include at least but not limited to a base station  101  (or a cluster head) and a plurality of UEs  102 ˜10× which may possess D2D capabilities. A cluster head could be a small cell base station, a peer device, or a remote radio head. The plurality of UEs  102 ˜ 10 x may first synchronize with an external device such as the base station  101  to acquire coarse timing references, and then UEs  103 ˜ 10 x would be able to transmit signals such as discovery signals to a leading UE such as the UE  102 . 
     In one of the exemplary embodiments, one resource allocation scheme for the scenario of  FIG. 1  could be illustrated by  FIG. 2 . According to  FIG. 2 , the plurality of UEs  103 ˜ 10 x could be allocated D2D resource to transmit signal by the base station  101 . The allocated D2D resource may include a resource with a specific time slot  211  and a frequency bandwidth  212  to transmit discovery signals. The specific time slot could be, for example, about one or two milliseconds. Within the time slot  211 , each of the UEs  103 ˜ 10 x may have a dedicated frequency domain resource transmit a discovery signal. For example, UE  103  may transmit a discovery signal at a first frequency band  201 , and UE  104  may transmit a discovery signal at a second frequency band  202 . 
     However, if one discovery signal is significantly weaker than the other. In that case, the weaker signal could be suppressed or eliminated to become undetectable after digitized by an A/D converter.  FIG. 3  is an example that illustrates a composition of two discovery signals in the time domain. Assuming that after the UE  103  transmits a first discovery signal  301 , and the UE  104  transmits a second discovery signal  302 , the composite signal  303  received by the UE  102  would be the first discovery signal  301  and the second discovery signal  302  superimposed with each other as illustrated in  FIG. 3 . In this case, the second discovery signal  302  which is significantly weaker than the first discovery signal  301  could be practically indiscernible. 
     Furthermore, if the inter-distances d12, d13,˜d1x among UE D2D pairs have large variations among them. In this case, the receiver of the UE  102  would need to be unnecessarily complex. 
     Therefore, the present disclosure proposes arranging D2D UEs to be close to one synchronous head to perform D2D communications. A synchronous head could be any peer device assigned by a base station or a small cell base station in order to serve as a device for synchronization or data relay. For example, under the proposed circumstance, D2D UEs assigned by a base station to be served under a leading UE or synchronous head would transmit discovery signals at about the same time. Since the these D2D UEs assigned by a base station to a synchronous head are close to one another, the timing arrivals and power fluctuations will be limited to a fixed range. In other words, there would be significantly less timing arrival differences or less dynamic range of power fluctuations at receptions relative to the scenario without a synchronous head. In this way, a D2D UE would also be able to receive signals with higher power and greater signal to noise ratio than the scenario without having a synchronous head. 
     In this disclosure, 3GPP-like keywords or phrases are used merely as examples to present inventive concepts in accordance with the present disclosure; however, the same concept presented in the disclosure can be applied to any other systems such as IEEE 802.11, IEEE 802.16, WiMAX, and so like by persons of ordinarily skilled in the art. For exemplary purposes, a LTE communication system would be used as examples for the rest of the disclosure. Therefore, as an example a base station under a LTE system would typically be an evolved Node B (eNB). 
       FIG. 4A  illustrates an exemplary user equipment  400  in accordance with the present disclosure. The term “user equipment” (UE) in this disclosure may be, for example, a mobile station, an advanced mobile station (AMS), a server, a client, a desktop computer, a laptop computer, a network computer, a workstation, a personal digital assistant (PDA), a tablet personal computer (PC), a scanner, a telephone device, a pager, a camera, a television, a hand-held video game device, a musical device, a wireless sensor, and the like. In some applications, a UE may be a fixed computer device operating in a mobile environment, such as a bus, a train, an airplane, a boat, a car, and so forth. 
     The exemplary UE  400  may contain at least but not limited to a transceiver circuit  403  (or a transmitter and receiver), an analog-to-digital (A/D)/digital-to-analog (D/A) converter  402 , and a processor  401  (or a processing circuit). The transceiver circuit  403  transmits and receives signals wirelessly. The transceiver  403  circuit may also perform operations such as low noise amplifying, impedance matching, frequency mixing, up or down frequency conversion, filtering, amplifying, and so like. The A/D/D/A converter  402  is electrically coupled to the transceiver circuit  403  and would be able to convert from an analog signal format to a digital signal format or from a digital signal format to an analog signal format. 
     The processor  401  would be electrically coupled to the A/D/D/A converter  402  and would be configured to process digital signal and to perform at least but not limited to functions related to the proposed method of resource allocation for device to device (D2D) communication in accordance with exemplary embodiments of the present disclosure. The functions of the processor  401  could be implemented using programmable units such as a micro-processor, a micro-controller, a DSP chips, FPGA, etc. The functions of the processor  401  could be integrated under one electronic device or one integrated circuit (IC) but may also be implemented with separate electronic devices or ICs. 
     The processor  401  may further include at least but not limited to a power level determining module  411  and a resource allocation module  412  as illustrated in  FIG. 4B . In response to the transceiver circuit  403  receiving a group of signals within a time period, the power level module  411  may discern from the group of signals at least one signal having the maximum power. As for the resource allocation module  412 , in response to receiving resource allocations for D2D communication via the transceiver circuit  403 , the resource allocation module  412  would know the time and frequency domain resource to use for D2D communication. In another exemplary embodiment, the resource allocation module  412  has a table such that after being assigned to a specific synchronous head, the resource allocation module  412  would implicitly know what time domain and frequency domain could be used for D2D communication. 
       FIG. 5A  &amp;  FIG. 5B  illustrates an exemplary base station  500  in accordance with the present disclosure. The term “base station” in this disclosure may also be, for example, an evolved node B (eNB), a macro BS, a micro BS, a pico BS, a Node-B, an advanced base station (ABS), a base transceiver system (BTS), an access point, a home base station, a home eNB, a relay station, a scatterer, a repeater, an intermediate node, an intermediary, satellite-based communication base stations, and so forth. 
     An exemplary eNB  500  would contain at least but not limited to a transceiver  503  circuit (or a transmitter and receiver), an analog-to-digital (A/D)/digital-to-analog (D/A) converter  502 , a processor  501  or processing circuit. The transceiver circuit  503  transmits and receives signals wirelessly. The transceiver circuit  503  may also perform operations such as low noise amplifying, impedance matching, frequency mixing, up or down frequency conversion, filtering, amplifying, and so like. The A/D/D/A converter  502  would be electrically coupled to the transceiver circuit  503  and would be able to convert from an analog signal format to a digital signal format or from a digital signal format to an analog signal format. 
     The processing circuit  501  would be electrically coupled to the A/D/D/A converter  502  and would be configured to process digital signals and to perform functions of the proposed method of resource allocation for device to device (D2D) communication in accordance with exemplary embodiments of the present disclosure. The functions of the processor  501  could be implemented using programmable units such as a micro-processor, a micro-controller, a DSP chips, FPGA, etc. The functions of the processor  501  could be integrated under one electronic device or one integrated circuit (IC) but may also be implemented with separate electronic devices or ICs. 
     The processor  501  may further include at least but not limited to a power level determining module  511  and a resource allocation module  512  as illustrated in  FIG. 5B . In response to the transceiver circuit  503  receiving a group of signals within a time period with each of the group of signaling containing a report that records a group of signals received, the power level module  511  may discern from the group of signals at least one signal having the maximum power. As for the resource allocation module  512 , in response to the group of signals via the transceiver circuit  503 , the resource allocation module  512  would allocate time and frequency domain resource for each UE for D2D communication. In another exemplary embodiment, the resource allocation module  512  has a table such that after assigning a UE to a specific synchronous head, the resource allocation module  512  would implicitly know what time domain and frequency domain are used by the UE for D2D communication. 
       FIGS. 6A &amp; 6B  and their corresponding descriptions disclose the basic concept of the disclosure.  FIG. 7A  ˜ FIG. 12  and their corresponding descriptions disclose further details and various embodiments of the present disclosure. Referring to the exemplary communication system  600  of  FIG. 6A , a D2D UE  612  may establish synchronization with a base station  610  (or cluster head). A base station  610  may assign any UEs with D2D capabilities, such as UE  611  in  FIG. 6A , to be a synchronous head. The D2D UE  612  could also detect one or more discovery signals from one or more synchronous heads and then report to the base station  610  one or more synchronous head having highest power. After UE  612  synchronizes with the base station  610 , the base station may assign the UE  612  to the synchronous head, UE  611  assuming that the discovery signal of UE  611  received by UE  612  is among the ones with the highest power. The UE  612  would then be allocated D2D resource according to the synchronous head. 
       FIG. 6B  illustrates resource allocation for D2D UEs  612 ,  601 ˜ 60 x which are assigned to be served under the synchronous head  611  in accordance with one of the exemplary embodiments of the present disclosure. In general, all UEs which follow each synchronous head would be assigned a specific time slot  651  and a dedicated frequency band  652  that are allocated for that particular synchronous head. Within each time slot  651 , each of the UEs would be assigned an unique frequency domain resource from the allocated frequency band  652  as D2D communication resource. For example, UE  601 ˜UE  60 x could each transmit a discovery signal D 1 ˜Dx according to  FIG. 6A , and the discovery signal D 1 ˜Dx could be transmitted by using the resource allocated as  FIG. 6B . In this way, the transmitted discovery signals D 1 ˜Dx are frequency domain multiplexed as they are close the synchronous head  611 . 
       FIG. 7A˜FIG .  7 D illustrates a proposed reporting procedure in accordance with one of the exemplary embodiments of the present disclosure. Assuming that an exemplary scenario of  FIG. 7A  would include a base station  710  (or cluster head) that has already assigned UE  711  as a synchronous head. UE  701 ˜ 70 x are assumed to be under the domain of the base station  710  and could be closed to the synchronous head UE  711 . As shown in  FIG. 7B , since UE  701 ˜ 70 x are allocated resources according to the synchronous head, UE  711 , the inter-distances and signal strengths of signals received among the UE  701 - 70 x would be within a specific threshold. Also all UEs that are allocated resources according to a synchronous head would have similar timing already synchronized with the base station  710 . 
       FIG. 7C  illustrates the reporting procedure in the scenario that is consistent with  FIGS. 7A &amp; 7B  according one of the exemplary embodiments.  FIG. 7D  illustrates the reporting procedure in terms of a timing diagram according to one of the exemplary embodiments.  FIG. 7C  and  FIG. 7D  are referred together. In step S 751 , any one of the D2D UEs  701 ˜ 70 x would listen to a group of discovery signals for different synchronous heads. Under a typical circumstance, there could be a group of discovery signals in the airwave. However, any one of the D2D UEs  701 ˜ 70 x would select at least one discovery signal that has the highest power, and the discovery signal selected could only come from a synchronous head. In other words, a D2D UE would discern from one or more discovery signals and find one or more discovery signals of synchronous heads with the highest power. Assuming that the D2D UE  711  has been determined to be the synchronous head with the highest power, in step S 752  a D2D UE among UEs  701 ˜ 70 x would transmit a signal to the base station  710 , and the signal would include the information that the D2D UE  711  was determined to be the synchronous head with the highest power. The signal may also include one or more other UEs as synchronous heads having the largest power. In step S 753 , the base station  710  would allocate D2D resource for the one of the D2D UEs  701 ˜ 70 x that transmitted the signal in step S 752 , and the allocated resource would be associated with the synchronous head, the D2D UE  711 . The resource allocation scheme will be further elaborated in  FIG. 9˜11  and their corresponding descriptions. 
     A synchronous head could be assigned by a base station based on location. For example, according to  FIG. 8 , synchronous heads  801 ˜ 806  are selected by the base station  810  to spread out as far as possible in order to maximize coverage areas within a macro cell. The synchronous head could be a small cell or a cluster head. When small cell is used as synchronous head, a D2D UE may measure received power from one or more synchronous heads  801 ˜ 806  and reports to the base station  810  the associated synchronous head that could be allocated radio resource under according to the received powers. When cross small cell resource allocation is considered, the resources among different cells could be interleaved. 
       FIG. 9  illustrates FDM based resource allocation according to a synchronous head in accordance with one of the exemplary embodiments of the present disclosure. For this exemplary embodiment, radio resources allocated for a group of discovery signals of synchronous heads are FDM-multiplexed in a dedicated time slot. Radio resources allocated to UEs served under each synchronous head could be FDM-multiplexed within the time slot dedicated for each synchronous head. For example, it can be seen from  FIG. 9  that in the time slot, SH, allocated for different synchronous heads, the group of discovery signals DS  1 , DS  2 , . . . , DS N, are transmitted on different carrier frequencies. Assuming that synchronous head #2 has transmitted DS  2  that has been detected by a D2D UE as having the largest power, the synchronous head #2 could be reported to a base station as the preferred synchronous head for the D2D UE. The report may include an associated power level (e.g. −48 dBm). In response to receiving the report, in step S 901 , the base station may allocate an unique frequency domain resource, the radio resource  912  that is in the time slot SH 2 associated with synchronous head #2. The D2D UE could then utilize the allocated D2D resource  912  such as to transmit a discovery signal over the radio resource  912 . 
       FIG. 10  illustrates TDM based resource allocation according to a synchronous head in accordance with one of the exemplary embodiments of the present disclosure. For this exemplary embodiment, radio resources allocated for a group of discovery signals of synchronous heads are TDM-multiplexed on different time slots. Radio resources allocated to UEs served under each synchronous head could be FDM-multiplexed within the time slot dedicated for each synchronous head. After a UE detects the group of discovery signals across various time slots, the UE could determine a discovery signal having the highest power. The UE could then report to a base station the preferred synchronous head that transmitted the discovery signal having the highest power. The base station would then allocate a radio resource to the UE in the time slot associated with the preferred synchronous head. For example, suppose that a UE has determined that the discovery signal  1011  of synchronous head #2 has the highest power and reported the determination to the base station with the associated power level, in step S 1001 , the UE could be allocated an unique frequency domain resource, the radio resource  1012  that is in the time slot SH2 associated with synchronous head #2 by the base station. The UE could then utilize the allocated D2D resource  1012  such as to transmit a discovery signal over the allocated D2D resource  1012 . In other words, the UE may receive an unique frequency domain resource according to the synchronous head as the D2D resource allocation and transmits a discovery signal by using the unique frequency domain resource. 
       FIG. 11  illustrates implicit resource allocation according to a synchronous head in accordance with one of the exemplary embodiments of the present disclosure. Upon a UE reporting to a base station the synchronous head associated with a discovery signal having the highest power and associated power level, the UE would implicitly know the allocated radio resource without requiring the base station to allocated such radio resource. For example, a D2D UE may detect the power of discovery signals from different time slots and compare the power of discovery signals among each other to determine a discovery signal having the highest power. Assuming that the discovery signal  1111  of synchronous head #2 has been determined to be the discovery signal having the highest power and reported to the base station, in step S 1101 , implicitly the UE would know that the radio resource  1112  associated with synchronous head #2 would be implicitly assigned to be used. The UE could then utilize the radio resource  1112  such as to transmit a discovery signal. 
     As for the synchronization relationship between a base station, a synchronous head, and D2D UEs served under the synchronous head and the base station, a hierarchical synchronization scheme is proposed.  FIG. 12  illustrates hierarchical synchronization in accordance with one of the exemplary embodiments of the present disclosure. For this exemplary embodiment, a synchronous head  1202  may synchronize with a base station  1201  so that the timing advance would be adjusted between the base station  1201  and the synchronous head  1202 . A D2D UE such as one of UE  1203  could synchronize with the synchronous head  1202  to acquire reference timing. The D2D UE  1203  could measure the arrival signal from the base station  1201  and the synchronous head  1202  to adjust the timing difference. The D2D UE  1203  could sends signal timing advance to be the same as the synchronous head  1202  and maintain the similar timing advance as synchronous head  1202 . 
     In one of the exemplary embodiment, the assignment of a synchronous head may not be static but could change from time to time. For example, assuming that a group of D2D UEs has been assigned by a base station to follow a synchronous head. The base station could choose one of the D2D UEs from this group to serve as the synchronous head instead, and the device that has previously been assigned as the synchronous head could then become one of the UEs of the group. 
     In one of the exemplary embodiments, an assigned synchronous head could be selected as a UE relay. In this way, the synchronous head may collect user data from a base station or from another UE targeted aimed toward a targeted UE. The synchronous head may then forward the collected user data for the targeted UE camping on this synchronous head. In the same way, the synchronous head may also forward user data from the targeted UE to a base station or to another UE. 
     In one of the exemplary embodiment, a synchronous head could be selected by a base station to serve as a cluster head to coordinate a group of D2D UEs. 
     In view of the aforementioned descriptions, the present disclosure is suitable for being used in a wireless communication system and is able to allocate D2D resources and achieve synchronization in such as a way that the near-far effect would be reduced and the variations of inter-distances among different UE pairs are minimized so that different timing propagation delays would not cause associated reception performance losses. 
     No element, act, or instruction used in the detailed description of disclosed embodiments of the present application should be construed as absolutely critical or essential to the present disclosure unless explicitly described as such. Also, as used herein, each of the indefinite articles “a” and “an” could include more than one item. If only one item is intended, the terms “a single” or similar languages would be used. Furthermore, the terms “any of” followed by a listing of a plurality of items and/or a plurality of categories of items, as used herein, are intended to include “any of”, “any combination of”, “any multiple of”, and/or “any combination of multiples of the items and/or the categories of items, individually or in conjunction with other items and/or other categories of items. Further, as used herein, the term “set” is intended to include any number of items, including zero. Further, as used herein, the term “number” is intended to include any number, including zero. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents. 
     Moreover, the claims should not be read as limited to the described order or elements unless stated to that effect. In addition, use of the term “means” in any claim is intended to invoke 35 U.S.C. §112, ¶6, and any claim without the word “means” is not so intended.