Abstract:
A mobile communication device is provided with a plurality of processing logic units. A first processing logic unit is configured to connect the mobile communication device to a first wireless network for wireless transceiving via a first link. A second processing logic unit is configured to determine whether a second link to a second wireless network is available in response to detecting a low performance condition of the first link. Particularly, the first wireless network and the second wireless network are heterogeneous networks. A third processing logic unit is configured to hand over the mobile communication device from the first wireless network to the second wireless network in response to a transceiving rate of the second link being greater than a first value.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Divisional of co-pending application Ser. No. 13/569,901, filed on Aug. 8, 2012, the entire contents of which are hereby incorporated by reference and for which priority is claimed under 35 U.S.C. §120. This application also claims priority to U.S. Provisional Application No. 61/522,045, filed on Aug. 10, 2011, the entire contents of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention generally relates to handovers in the field of wireless communications, and more particularly, to apparatuses and methods for handovers between heterogeneous networks to improve the performance of wireless transceiving. 
     2. Description of the Related Art 
     With growing demand for ubiquitous computing and networking, various wireless technologies have been developed, such as the Wireless Fidelity (WiFi) technology, Global System for Mobile communications (GSM) technology, General Packet Radio Service (GPRS) technology, Enhanced Data rates for Global Evolution (EDGE) technology, Wideband Code Division Multiple Access (WCDMA) technology, Code Division Multiple Access 2000 (CDMA-2000) technology, Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) technology, Worldwide Interoperability for Microwave Access (WiMAX) technology, Long Term Evolution (LTE) technology, Time-Division LTE (TD-LTE) technology, and others. For user convenience and flexibility, most Mobile Stations (MSs) nowadays are equipped with more than one wireless communication module for supporting different wireless technologies. However, each wireless technology has its own features, such as bandwidth, average coverage, and service rate, etc. Particularly, the bandwidth and coverage provided to an MS by a wireless network may vary according to the location conditions of the MS and/or the time condition. 
     Take an MS operating in either an Android or a Windows system, which supports WiFi and WCDMA technologies, for example. The MS always selects a WiFi network over a WCDMA network, even if the signal quality of the WiFi network is bad while the signal quality of the WCDMA network is fair/good. That is, the MS is configured to stay connected with the WiFi network with bad signal quality, regardless of the availability of the WCDMA network with fair/good signal quality. In such circumstances, even browsing a web page may take a long time, and accordingly, the user may experience a serious delay of wireless connectivity. Thus, to improve the performance of wireless transceiving, it is desirable to provide smart handovers between heterogeneous networks. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect of the invention, a mobile communication device is provided. The mobile communication device comprises a first processing logic unit, a second processing logic unit, and a third processing logic unit. The first processing logic unit is configured to connect the mobile communication device to a first wireless network for wireless transceiving via a first link. The second processing logic unit is configured to determine whether a second link to a second wireless network is available in response to detecting a low performance condition of the first link, wherein the first wireless network and the second wireless network are heterogeneous networks. The third processing logic unit is configured to hand over the mobile communication device from the first wireless network to the second wireless network in response to a transceiving rate of the second link being greater than a first value. 
     In another aspect of the invention, a method for a mobile communication device to handover between a plurality of heterogeneous networks is provided. The method comprises the steps of connecting to a first wireless network for wireless transceiving via a first link, determining whether a second link to a second wireless network is available in response to detecting a low performance condition of the first link, wherein the first wireless network and the second wireless network are heterogeneous networks, and handing over the mobile communication device from the first wireless network to the second wireless network in response to a transceiving rate of the second link being greater than a first value. 
     In yet another aspect of the invention, a mobile communication device is provided. The mobile communication device comprises a first processing logic unit, a second processing logic unit, a third processing logic unit, and a fourth processing logic unit. The first processing logic unit is configured to connect the mobile communication device to a first wireless network for wireless transceiving via a first link. The second processing logic unit is configured to scan for a nearby second wireless network with a current signal quality, wherein the first wireless network and the second wireless network are heterogeneous networks. The third processing logic unit is configured to apply a condition check on the current signal quality of the second wireless network according to a result of whether the mobile communication device was previously connected to the second wireless network prior to being connected to the first wireless network. The fourth processing logic unit is configured to hand over the mobile communication device from the first wireless network to the second wireless network in response to passing of the condition check. 
     In still another aspect of the invention, a method for a mobile communication device to handover between a plurality of heterogeneous networks is provided. The method comprises the steps of connecting to a first wireless network for wireless transceiving via a first link, scanning for a nearby second wireless network with a current signal quality, wherein the first wireless network and the second wireless network are heterogeneous networks, applying a condition check on the current signal quality of the second wireless network according to a result of whether the mobile communication device was previously connected to the second wireless network prior to being connected to the first wireless network, and handing over the mobile communication device from the first wireless network to the second wireless network in response to passing of the condition check. 
     Other aspects and features of the present invention will become apparent to those with ordinarily skill in the art upon review of the following descriptions of specific embodiments of the mobile communication devices and the methods for a mobile communication device operating as an MS to handover between a plurality of heterogeneous networks. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1  is a block diagram of a wireless communications environment according to an embodiment of the invention; 
         FIG. 2  is a block diagram illustrating an exemplary software architecture of the mobile communication device  110  according to an embodiment of the invention; 
         FIG. 3  is a block diagram illustrating an exemplary software architecture of the mobile communication device  110  according to another embodiment of the invention; 
         FIG. 4  is a state transition diagram illustrating state machine operations of the mobile communication device  110  according to an embodiment of the invention; 
         FIG. 5  is a schematic diagram illustrating the ping-pong effect for the mobile communication device  110  wandering around the coverage edge of the WLAN  130  and the coverage of the cellular network  120 ; 
         FIG. 6  is a flow chart illustrating a smart handover method for handing over the mobile communication device  110  from the cellular network  120  to the WLAN  130  according to an embodiment of the invention; 
         FIG. 7  is a curve diagram illustrating a 2-stage monitoring for the signal quality of nearby WLANs according to an embodiment of the invention; 
         FIG. 8A  is a schematic diagram illustrating RSSI changes for inward movement towards a WLAN according to an embodiment of the invention; 
         FIG. 8B  is a schematic diagram illustrating RSSI changes for outward movement from a WLAN according to an embodiment of the invention; 
         FIG. 9  is a flow chart illustrating a smart handover method for handing over the mobile communication device  110  from the WLAN  130  to the cellular network  120  according to an embodiment of the invention; and 
         FIG. 10  is a curve diagram illustrating a 2-stage monitoring for the signal quality of nearby WLANs according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. It should be understood that the embodiments may be realized in software, hardware, firmware, or any combination thereof. 
       FIG. 1  is a block diagram of a wireless communications environment according to an embodiment of the invention. The wireless communications environment  100  comprises a mobile communication device  110 , a cellular network  120  and a non-cellular network  130 . The mobile communication device  110  may selectively connect to one or both of the cellular network  120  and the non-cellular network  130  for obtaining wireless services. The cellular network  120  may be a GSM system, GPRS system, WCDMA system, CDMA-2000 system, TD-SCDMA system, WiMAX system, LTE system, or TD-LTE system, etc., depending on the Radio Access Technology (RAT) in use. The cellular network  120  comprises at least one cellular station  121  (or so-called base station or access station), at least one control node  122 , and a core network  123 , wherein the cellular station  121  is controlled by the control node  122  to provide the functionality of wireless transceiving for the cellular network  120 , and the cellular station  121  and the control node  122  together may be referred to as a radio access network or access network. For example, if the cellular network  120  is a WCDMA system, the cellular station  121  may be a NodeB, the control node  122  may be a Radio Network Controller (RNC), and the core network  123  may be a General Packet Radio Service (GPRS) core which includes a Home Location Register (HLR), at least one Serving GPRS Support Node (SGSN), and at least one Gateway GPRS Support Node (GGSN). Alternatively, the cellular network  120  may not comprise any control node. For example, if the cellular network  120  is an LTE system, the cellular station  121  may be an Evolved-NodeB (E-NodeB), and the core network  123  may be an Evolved Packet Core (EPC) which includes a Home Subscriber Server (HSS), Mobility Management Entity (MME), Serving Gateway (S-GW), and Packet Data Network Gateway (PDN-GW or P-GW). 
     The non-cellular network  130  may be a Wireless Local Area Network (WLAN), a Bluetooth Personal Area Network (BT PAN), ZigBee Wireless PAN (ZigBee WPAN), or others, implemented as an extension of wired local area networks and may be able to provide the last few meters of connectivity between a wired network and mobile or fixed devices. As shown in  FIG. 1 , the non-cellular network  130 , which is illustrated as a WLAN for example, is established by an Access Point (AP)  131  which may connect to a local area network by an Ethernet cable. The AP  131  typically receives, buffers, and transmits data between the WLAN and the wired network infrastructure. The AP  131  may have, on average, a coverage varying from 20 meters in an area with obstacles (walls, stairways, elevators etc) to 100 meters in an area with clear line of sight. Note that, in the following description, the WLAN is only given as an example, and the invention is not limited thereto. Alternatively, the non-cellular network  130  may be a BT PAN, ZigBee WPAN, or others. 
     The mobile communication device  110  may also be referred to as a Mobile Station (MS), Mobile Terminal (MT), or User Equipment (UE). For example, the mobile communication device  110  may be a mobile phone (also known as a cellular or cell phone), a smart phone, a laptop computer with wireless communications capability, or others. The mobile communication device  110  may comprise two wireless modules (not shown) for performing the functionality of wireless transceiving to and from the cellular network  120  and the non-cellular network  130 . To further clarify, each wireless module may comprise a Baseband unit (not shown) and a Radio Frequency (RF) unit (not shown). The Baseband unit may contain multiple hardware devices to perform baseband signal processing, including analog to digital conversion (ADC)/digital to analog conversion (DAC), gain adjusting, modulation/demodulation, encoding/decoding, and so on. The RF unit may receive RF wireless signals, convert the received RF wireless signals to baseband signals, which are processed by the Baseband unit, or receive baseband signals from the Baseband unit and convert the received baseband signals to RF wireless signals, which are later transmitted. The RF unit may also contain multiple hardware devices to perform radio frequency conversion. For example, the RF unit may comprise a mixer to multiply the baseband signals with a carrier oscillated in the radio frequency of the wireless communications system, wherein the radio frequency may be 2.4 GHz utilized in WiFi systems, or 900 MHz, 1900 MHz, or 2100 MHz utilized in WCDMA systems, or may be 900 MHz, 2100 MHz, or 2.6 GHz utilized in LTE systems, or others depending on the RAT in use. Also, the mobile communication device  110  may comprise a controller module (not shown) for controlling the operation of the two wireless modules and other functional components, such as a display unit and/or keypad serving as a Man-Machine Interface (MMI), a storage unit storing the program codes of applications, or others. Alternatively, the two wireless modules may negotiate with each other for coordinating the respective operations thereof, without any mediator, e.g., the controller module. 
       FIG. 2  is a block diagram illustrating an exemplary software architecture of the mobile communication device  110  according to an embodiment of the invention. In the exemplary software architecture, two protocol stack handlers  10  and  20 , each of which may be implemented as program code, when loaded and executed by a processing unit or Micro-Processing Unit (MCU) (e.g., an MCU of a Baseband unit) with a plurality of processing logic units, are configured to communicate with the cellular network  120  and the non-cellular network  130 , respectively, in compliance with a respective wireless communication protocol. Also, the exemplary software architecture includes an mediator  30  which may be implemented as program code and when loaded and executed by a processing unit or MCU with a plurality of processing logic units, is configured to control/coordinate the operations of the protocol stack handler  10  and  20  to practice the smart handover method of the invention. Alternatively, in another embodiment as shown in  FIG. 3 , the protocol stack handler  10  and  20  may directly negotiate with each other for coordinating the respective operations thereof to practice the smart handover method of the invention, without the mediator  30 . 
     Specifically, the mobile communication device  110  is capable of performing smart handovers between the cellular network  120  and the non-cellular network  130  for obtaining wireless services with fair transceiving rates.  FIG. 4  is a state transition diagram illustrating state machine operations of the mobile communication device  110  according to an embodiment of the invention. The “Cellular-connected” state represents a state where the mobile communication device  110  is connected to the cellular network  120  for obtaining wireless services, while the “WiFi-associated” state represents a state where the mobile communication device  110  is connected to the non-cellular network  130  for obtaining wireless services. For the case where the mobile communication device  110  is in the “Cellular-connected” state, if a new AP is detected with a signal quality greater than a threshold value, the mobile communication device  110  may disconnect with the cellular network  120  and connect to the non-cellular network  130  via the new AP, and then enter the “WiFi-associated” state. In one embodiment, the signal quality of the AP may be determined by measuring the Received Signal Strength Indicator (RSSI) of the signals from the AP. Note that, other measuring indicators, such as Signal to Noise Ratio (SNR), Interference to Signal Ratio (ISR), Packet Error Rate (PER), and Bit Error Rate (BER), etc., may be employed for determining the signal quality of an AP, and the invention is not limited thereto. In another situation, if the signal quality of a previously detected AP increases so that the currently detected signal quality is greater than the sum of the previously detected signal quality and a margin value, the mobile communication device  110  may disconnect with the cellular network  120  and connect to the non-cellular network  130  via the AP, and then enter the “WiFi-associated” state. To further clarify, the margin value may be a predetermined buffer to eliminate the ping-pong effect as shown in  FIG. 5 . Particularly, the ping-pong effect occurs when the coverage of the cellular network  120  and the non-cellular network  130  overlap and the mobile communication device  110  wanders near the coverage edge of the non-cellular network  130 . Around the coverage edge, the signal quality of the non-cellular network  130  may be weak and unstable, and without the margin value, handovers back and forth between the cellular network  120  and the non-cellular network  130  may be too frequent, thus consuming unnecessary power. Thus, by configuring a proper margin value, frequent handovers between the cellular network  120  and the non-cellular network  130  may be avoided. For the case where the mobile communication device  110  is in the “WiFi-associated” state, if the transceiving rate (referred to herein as “speed” for brevity) of the link to the currently associated AP is lower than the speed of the link to the cellular network  120 , the mobile communication device  110  may disconnect with the non-cellular network  130  and connect to the cellular network  120 , and then enter the “Cellular-connected” state. To be more specific, the speed of the link to the currently associated AP may be determined according to the transceiving status between the mobile communication device  110  and the associated AP, and the speed of the link to the cellular network  120  may be determined according to the system information broadcasted by the cellular network  120 . In another embodiment, the mobile communication device  110  may transit from the “WiFi-associated” state to the “Cellular-connected” state if the speed of the link to the currently associated AP is lower than a predetermined value (e.g., 2 Mbps). 
       FIG. 6  is a flow chart illustrating a smart handover method for handing over the mobile communication device  110  from the cellular network  120  to the non-cellular network  130  according to an embodiment of the invention. In this embodiment, the mobile communication device  110  is initially connected to the cellular network  120  and is in a “Cellular-connected” state. To begin, the mobile communication device  110  periodically scans for any nearby non-cellular network (step S 610 ). If a non-cellular network is detected, the mobile communication device  110  then determines whether it was previously connected to the detected non-cellular network (step S 620 ). If so, the mobile communication device  110  further determines whether the currently detected signal quality of the non-cellular network is greater than the sum of the previously detected signal quality of the non-cellular network and a margin value to eliminate the ping-pong effect (step S 630 ). Specifically, the mobile communication device  110  may distinguish a new non-cellular network from a previously associated non-cellular network by identifying the Media Access Control (MAC) addresses and/or Service Set Identifiers (SSIDs) of all detected non-cellular networks. That is, if the MAC address or SSID of a detected non-cellular network is not found in the connection history stored in the mobile communication device  110 , then the detected non-cellular network is a new non-cellular network; otherwise, the detected non-cellular network is a previously associated non-cellular network. It is noted that, there may be a situation where two or more non-cellular networks in an area are configured with the same SSID, and in this case, the MAC address instead of the SSIDs should be used to uniquely identify each one of the non-cellular networks in the area. The previously detected signal quality of the non-cellular network may be the signal quality of the non-cellular network at the time when the mobile communication device  110  decided to perform handover from the non-cellular network to the cellular network  120 . If the currently detected signal quality of the non-cellular network is greater than the sum of the previously detected signal quality of the non-cellular network and a margin value to eliminate the ping-pong effect, the mobile communication device  110  conducts handover to the non-cellular network. Specifically, the mobile communication device  110  first tries to establish a connection to the non-cellular network (step S 640 ), and then waits for acceptance of the connection from the non-cellular network (step S 650 ). If the connection is accepted by the non-cellular network, the mobile communication device  110  then disconnects with the cellular network  120  (step S 660 ) and enters the “WiFi-associated” state; otherwise, if the connection is rejected by the non-cellular network, the mobile communication device  110  stays in the “Cellular-connected” state. Subsequent to step S 620 , if not, i.e., the detected non-cellular network is a new non-cellular network which the MS has never connected to previously, the mobile communication device  110  determines whether the signal quality of the new non-cellular network is greater than a threshold value (step S 670 ). If so, the flow proceeds to step S 640 , and if not, the flow goes back to the initial state. 
     It is noted that, before performing the smart handover method of  FIG. 6 , the mobile communication device  110  may first perform a 2-stage monitoring of the signal quality of any nearby non-cellular network, as shown in  FIG. 7 . In the first stage, the mobile communication device  110  may periodically detect the signal quality of any nearby non-cellular network during every N seconds, wherein N may be configured to be 6, 15, or any other number, depending on the power-saving settings of the mobile communication device  110 . Once the signal quality of a non-cellular network is detected to be greater than a first threshold X 1 , then the mobile communication device  110  proceeds to the second stage where it continues to monitor the signal quality of the detected non-cellular network and detect its moving direction in relation to the detected non-cellular network. When the signal quality of the detected non-cellular network is greater than a second threshold X 2  and it is detected that the mobile communication device  110  is moving towards the AP of the detected non-cellular network, the mobile communication device  110  may perform the smart handover method of  FIG. 5 , wherein the second threshold X 2  is greater than the first threshold X 1 . Specifically, the moving direction of the mobile communication device  110  may be determined by calculating the moving average of the monitored signal quality of the non-cellular network.  FIG. 8A  is a schematic diagram illustrating RSSI changes for inward movement towards a non-cellular network according to an embodiment of the invention. As shown in  FIG. 8A , the RSSIs of the detected non-cellular network monitored at time t 1 , t 2 , t 3 , t 4 , and t 5  are −91 dBm, −88 dBm, −86 dBm, −90 dBm, −84 dBm, respectively, wherein the RSSI monitored at time t 4  may be discarded as noise. The moving average of the mobile communication device  110  may be determined by calculating the slope of the monitored RSSIs. Since the slope of the monitored RSSIs is positive, it is determined that the mobile communication device  110  is moving towards the AP of the detected non-cellular network.  FIG. 8B  is a schematic diagram illustrating RSSI changes for outward movement from a non-cellular network according to an embodiment of the invention. As shown in FIG. B, the RSSIs of the detected non-cellular network monitored at time t 1 , t 2 , t 3 , t 4 , and t 5  are −91 dBm, −88 dBm, −86 dBm, −8 dBm, −90 dBm, respectively, wherein the RSSI monitored at time t 3  may be considered as a turning point with respect to the moving direction of the mobile communication device  110 . The moving average of the mobile communication device  110  may be determined by calculating the slope of the monitored RSSIs. Since the slope of the monitored RSSIs is negative, it is determined that the mobile communication device  110  is moving away from the AP of the detected non-cellular network. In another embodiment, the Simple Moving Average (SMA) formula may be employed for determining the moving direction of the mobile communication device  110 , and the invention is not limited thereto. Note that the detailed descriptions concerning the calculation of the SMA are omitted herein as they are beyond the scope of the invention. 
       FIG. 9  is a flow chart illustrating a smart handover method for handing over the mobile communication device  110  from the non-cellular network  130  to the cellular network  120  according to an embodiment of the invention. In this embodiment, the mobile communication device  110  is initially connected to the non-cellular network  130  and is in a “WiFi-associated” state. To begin, the mobile communication device  110  periodically determines whether the speed of the link to the AP  131  is lower than 2 Mbps and whether the signal quality of the non-cellular network  130  is lower than a threshold T (step S 910 ). Specifically, the speed of the link to the AP  131  may be determined according to the transceiving status between the mobile communication device  110  and the AP  131 , and the threshold T is used to eliminate the situation where the mobile communication device  110  may be moving at a high speed away from the AP  131  and used to eliminate the situation where the detected speed of the link to the AP  131  may not be accurate for real-time changes. For example, the speed of the link to the AP  131  detected at time t 1  is greater than 2 Mbps and the next periodic detection is 6 seconds thereafter. In this example, the mobile communication device  110  moves rapidly away from the AP  131  to a place where the signal quality of the non-cellular network  130  drops sharply in less than 6 seconds. Note that the speed of the link to the AP  131  detected at time t 1  is not accurate enough to be taken as the only measuring factor. Accordingly, the threshold T is used. The value of the threshold T may be predetermined to be a specific number according to any one or more considerations, such as the coverage of the non-cellular network  130 , the geological environment of the non-cellular network  130 , etc. Note that, the lower bound for the speed of the link to the AP  131  may be configured to any value other than 2 Mbps, and the invention is not limited thereto. 
     Subsequent to step S 910 , if so, the mobile communication device  110  further determines whether a link to the cellular network  120  is available and whether the speed of the link to the cellular network  120  is greater than the speed of a GPRS link (step S 920 ). Specifically, the mobile communication device  110  may first perform an attachment procedure to register to the cellular network  130 , and a link to the cellular network  120  is available if the registration is successful. The speed of the link to the cellular network  120  may be determined according to the system information broadcasted by the cellular network  120 , and in general, the speed of a GPRS link is up to 80 Kbps for downlink and 20 Kbps for uplink with Coding Scheme 4 (CS-4). In another embodiment, if the type of wireless service in use requires a higher data rate, the mobile communication device  110  may instead determine, in step S 920 , whether the speed of the link to the cellular network  120  is greater than (or equal to) the speed of a WCDMA link, an HSPA link, or an LTE link. 
     If a link to the cellular network  120  is available and the speed of the link is greater than the speed of a GPRS link, then the mobile communication device  110  conducts handover from the non-cellular network  130  to the cellular network  120  (step S 930 ), and then disconnects with the non-cellular network  130  and enters the “Cellular-connected” state. In another embodiment, before step S 930 , the mobile communication device  110  may prompt the user to confirm whether to proceed to perform handover from the non-cellular network  130  to the cellular network  120 , and only proceed to step S 930  when the user confirms the decision. Subsequent to steps S 910  and S 920 , if not, the mobile communication device  110  stays in the “WiFi-associated” state and waits for the next periodic check on the speed of the link to the AP  131 . 
     It is noted that, before performing the smart handover method of  FIG. 9 , the mobile communication device  110  may first perform a 2-stage monitoring of the signal quality of any nearby non-cellular network, as shown in  FIG. 10 . In the first stage, the mobile communication device  110  may periodically detect the signal quality of the non-cellular network  130  in every N seconds, wherein N may be configured to be 6, 15, or any other number, depending on the power-saving settings of the mobile communication device  110 . If once the signal quality of the non-cellular network  130  is detected to be lower than a first threshold Y 1 , then the mobile communication device  110  proceeds to the second stage where it continues to monitor the signal quality of the non-cellular network  130  and detect its moving direction against the non-cellular network  130 . When the signal quality of the non-cellular network  130  is lower than a second threshold Y 2  and it is detected that the mobile communication device  110  is moving away from the AP  131 , the mobile communication device  110  may perform the smart handover method of  FIG. 9 , wherein the first threshold Y 1  is greater than the second threshold Y 2 . Specifically, the moving direction of the mobile communication device  110  may be determined by calculating the moving average of the monitored signal quality of the non-cellular network  130 . For the calculation of the moving average, reference may be made to the related descriptions of  FIGS. 8A and 8B . 
     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. Those who are skilled in this technology can still make various alterations and modifications without departing from the scope and spirit of this invention. 
     Use of ordinal terms such as “first”, “second”, “third”, etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.