Patent Publication Number: US-2018054818-A1

Title: Techniques for communication management using multiple network allocation vectors

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims benefit of U.S. Provisional Application Ser. No. 62/377,368, entitled “TECHNIQUES FOR COMMUNICATION MANAGEMENT USING MULTIPLE NETWORK ALLOCATION VECTORS” and filed Aug. 19, 2016, which is expressly incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     The present disclosure relates generally to telecommunications, and specifically to techniques for spatial reuse implemented using a plurality of network allocation vectors (NAVs). 
     The deployment of wireless local area networks (WLANs) in the home, the office, and various public facilities is commonplace today. Such networks typically employ a wireless access point (AP) that connects a number of wireless stations (STAs) in a specific locality (e.g., home, office, public facility, etc.) to another network, such as the Internet or the like. In some examples, a set of STAs can communicate with each other through a common AP in what is referred to as a basic service set (BSS). However, when two or more unrelated BSSs are close enough to hear each other and are operating in the same frequency (e.g., in a multi-dwelling setting where there may be multiple APs in a close proximity to one another), the transmissions by AP and STAs in one BSS may affect the AP and STAs in another BSS. Thus, in some examples, nearby BSSs may have overlapping coverage areas and such BSSs may be referred to as overlapping BSSs or OBSSs. 
     Some WLAN network deployments may be dense (e.g., have a large number of STAs deployed within the coverage area of multiple APs), which may result in issues related to channel or medium usage. Due to collisions and interference among STAs caused by the overlapping BSSs, channel resources may be unnecessarily wasted. For instance, in some examples, one or more STAs may receive packet(s) from an OBSS that are intended for a different STA in a different BSS. In this case, traffic from the OBSS may trigger a STA in a different BSS to initiate backoff procedures unnecessarily. For example, in order to minimize resource contentions between STAs, WLAN may require STAs to implement carrier sense multiple access (CSMA) techniques in which the STA may sense the channel and transmit only when it senses that the channel is idle (e.g., when the STA does not detect any IEEE 802.11 signals on the wireless channel from another AP or STA). In contrast, when a first STA hears the second STA (e.g., detects signals on the wireless channel from the second STA), it may be required to wait for a random amount of time for the second STA to stop transmitting before listening again for the channel to be free. Such techniques may be beneficial to avoid multiple STAs from the same BSS from attempting to transmit over the same wireless channel at the same time, and thus resulting in a condition where neither STA may be able to transmit. 
     In an alternative method to physical carrier-sensing, STAs may also utilize network allocation vector (NAV) which is a virtual carrier-sensing mechanism used with wireless network protocols such as IEEE 802.11. In some implementations, media access control (MAC) layer frame headers may contain a duration field that may specify the transmission time required for the frame, in which time the medium will be busy. Thus, a STA listening on the wireless medium may detect a frame transmitted by another STA or AP, and decode the MAC layer frame header of the frame to read the duration field in order to set its NAV, which is an indicator for a STA on how long it must defer from accessing the medium. In some aspects, the NAV may be thought of as a counter, which counts down to zero at a uniform rate. When the counter is zero, the virtual carrier sense indication is that the medium is idle. In contrast, when the counter has a nonzero value, the carrier sense indication is that the medium is busy. 
     However, in the instance where a first STA detects signals or frames on the wireless channel from a second STA that is not part of the same BSS as the first STA, initiating the backoff procedures or setting its NAV in accordance with the duration identified in the OBSS frame may unnecessarily prevent the first STA from transmitting on the wireless channel for a predetermined time period. Such delays in scheduling traffic transmission may result in reduced throughput rates experienced by the first STA. 
     SUMMARY 
     Aspects of the present disclosure solve the above-identified problem by implementing techniques to increase reuse of the frequency channel by more than one device (e.g., spatial reuse). In one or more examples, aspects of the present disclosure allow for one or more network allocation vectors (NAVs) to control whether or not the STA may transmit on the wireless channel depending on whether the NAV was set by a device in the same BSS (“intra-BSS”) or from a different BSS (OBSS or “inter-BSS”). In one aspect, the STA may maintain two NAVs (intra-BSS NAV and inter-BSS NAV). In accordance with one technique, if the inter-BSS NAV was previously set based on an in-deterministic frame (e.g., a frame received by the STA that cannot readily be identified as either intra-BSS frame or an inter-BSS frame), then the STA may respond to a trigger frame from its AP after the inter-BSS NAV has been set as though the inter-BSS NAV is intra-BSS NAV. In contrast to the “in-deterministic frame,” a “deterministic-frame” may be a frame that is capable of being identified as either an intra-BSS frame or an inter-BSS frame based on BBSID included as part of the frame, or one of the address field is not matching the BSSID (or BSSIDs) of the AP with which the STA is associated with. 
     Additionally or alternatively, another technique may include setting the intra-BSS NAV (in contrast to inter-BSS NAV) in response to receiving an in-deterministic frame. Thereafter, if the STA receives a contention free-end (CF-END) frame from an intra-BSS frame, the STA may reset only the intra-BSS NAV in response to the CF-END frame being from an intra-BSS frame. In contrast, if the STA receives the CF-END frame from an inter-BSS frame, the STA may reset only the inter-BSS NAV, while maintaining the intra-BSS NAV, in response to the CF-END frame being from an inter-BSS frame. 
     In some examples, a method for wireless communication is disclosed. The method may include determining, at a wireless STA, that a frame received by the STA cannot be identified as an intra-BSS frame or an inter-BSS frame. The method may further include setting a first NAV in response to the determination. The first NAV may be associated with intra-BSS transmissions. The method may further include receiving a CF-END message from an intra-BSS frame or an inter-BSS frame, and resetting the first NAV in response to the CF-END message being from an intra-BSS frame or a second NAV in response to the CF-END message being from an inter-BSS frame. The second NAV may be associated with the inter-BSS transmission. 
     In another example, an apparatus for wireless communication is disclosed. The apparatus may include a processor and a memory coupled to the processor. The memory may include instructions executable by the processor to determine, at a wireless STA, that a frame received by the STA cannot be identified as an intra-BSS frame or an inter-BSS frame. The instructions may further be executable by the processor to set a first NAV in response to the determination. The first NAV may be associated with intra-BSS transmission. The instructions may further be executable by the processor to receive a CF-END message from an intra-BSS frame or an inter-BSS frame. The instructions may further be executable by the processor to reset the first NAV in response to the CF-END message being from an intra-BSS frame or a second NAV in response to the CF-END message being from an inter-BSS frame. The second NAV may be associated with inter-BSS transmission. 
     In another example, a computer-readable medium storing computer executable code for wireless communications is disclosed. The computer-readable medium may include code to determine, at a wireless STA, that a frame received by the STA cannot be identified as an intra-BSS frame or an inter-BSS frame. The computer-readable medium may further include code to set a first NAV in response to the determination. The first NAV may be associated with intra-BSS transmissions. The computer-readable medium may further include code to receive a CF-END message from an intra-BSS frame or an inter-BSS frame, and resetting the first NAV in response to the CF-END message being from an intra-BSS frame or a second NAV in response to the CF-END message being from an inter-BSS frame. The second NAV may be associated with the inter-BSS transmission. 
     In another example, an apparatus for wireless communication is disclosed. The apparatus may include means for determining, at a wireless STA, that a frame received by the STA cannot be identified as an intra-BSS frame or an inter-BSS frame. The apparatus may further include means for setting a first NAV in response to the determination. The first NAV may be associated with intra-BSS transmissions. The apparatus may further include means for receiving a CF-END message from an intra-BSS frame or an inter-BSS frame, and resetting the first NAV in response to the CF-END message being from an intra-BSS frame or a second NAV in response to the CF-END message being from an inter-BSS frame. The second NAV may be associated with the inter-BSS transmission. 
     It is understood that other aspects of apparatuses and methods will become readily apparent to those skilled in the art from the following detailed description, wherein various aspects of apparatuses and methods are shown and described by way of illustration. As will be realized, these aspects may be implemented in other and different forms and its several details are capable of modification in various other respects. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of apparatuses and methods will now be presented in the detailed description by way of example, and not by way of limitation, with reference to the accompanying drawings, wherein: 
         FIG. 1  is a conceptual diagram illustrating an example of a wireless local area network (WLAN) deployment; 
         FIGS. 2A-2B  is a timing diagram of one example of techniques for improving spatial reuse in accordance with aspects of the present disclosure; 
         FIG. 3  is another timing diagram of another example of techniques for improving spatial reuse in accordance with aspects of the present disclosure; 
         FIG. 4  illustrates one example of a flowchart that shows aspects for reducing delay in traffic transmission in an OBSS environment in accordance with various aspects of the present disclosure; 
         FIG. 5  illustrates another example of a flowchart that shows aspects for reducing delay in traffic transmission in an OBSS environment, while minimizing interference in BSS region in accordance with various aspects of the present disclosure; and 
         FIG. 6  is a schematic diagram of a device including an aspect of an STA that may implement various aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     As discussed above, some WLAN network deployments may be dense (e.g., have a large number of STAs deployed within the coverage area of multiple APs), which may result in issues related to channel or medium usage. In order to minimize interference or resource contentions, IEEE 802.11 protocol dictates that STAs use a carrier sense multiple access (CSMA) method in which the STA first senses the wireless channel (e.g., monitor or detect activity on the wireless channel) and attempt to avoid collisions by transmitting only when they sense the channel to be idle (e.g., when STA does not detect any 802.11 signals on the channel). In contrast, when an STA detects a signal from a different STA, it may assume that the detected signal is from the same BSS, and thus wait for a predetermined amount of time before listening again for the channel to be free. 
     WLAN STAs may also use Request to Send/Clear to Send (RTS/CTS) signals to mediate access to the shared medium. In such situations, the AP may issue a CTS packet to one STA at a time, which in turn sends its entire frame to the AP. The STA then waits for an acknowledgement (ACK) packet from the AP indicating that the AP received the packet correctly. If the STA does not receive the ACK in time the STA presumes the packet collided with some other transmission, and thus moves the STA to execute backoff operations. The term “backoff operation” may refer to the process of waiting a designated time interval or time period before the STA or AP may attempt accessing a channel or medium. The term “backoff operation” may also be associated with techniques used to space out retransmissions over time as part of network congestion avoidance. An example of such techniques is the exponential backoff algorithm in which a random value within an acceptable range is selected to schedule retransmissions after collisions to avoid further collisions from taking place. Returning to the above example, the STA, after failing to receive an ACK and entering a backoff operation, may try to access the medium and re-transmit its packet again after the backoff counter expires. 
     As discussed above, an alternative method to physical carrier-sensing may include reliance on a network allocation vector (NAV), which is a virtual carrier-sensing mechanism used with wireless network protocols such as IEEE 802.11. In some implementations, media access control (MAC) layer frame headers may contain a duration field that may specify the transmission time required for the frame, in which time the medium will be busy. Thus, a STA listening on the wireless medium may detect a frame transmitted by another STA or AP, and decode the MAC layer frame header of the frame to read the duration field in order to set its NAV, which is an indicator for a STA on how long it must defer from accessing the medium. In some aspects, the NAV may be thought of as a counter, which counts down to zero at a uniform rate. When the counter is zero, the virtual carrier sense indication is that the medium is idle. In contrast, when the counter has a nonzero value, the carrier sense indication is that the medium is busy. 
     Although the Clear Channel Assessment (CCA) and Collision Avoidance (CA) protocols serves well to divide the channel relatively equally among all participants within the collision domain, its efficiency decreases when the number of participants grows very large. In some examples, a factor that contributes to network inefficiency may include having a plurality of APs with overlapping areas of service. Thus, as discussed above, in the instance where the first STA detects signals on the wireless channel from a second STA that is not part of the same BSS as the first STA, initiating the backoff procedures or setting the NAVs based on OBSS frames prevents the first STA from transmitting on the wireless channel for a predetermined time period. This prevents the medium to be used inadvertently by the first STA and effect the transmissions on the air by the second STA. However, if the second STA now completes its transmission and it sends a CF-END, the first STA can start using the medium, and it can affect any ongoing transmission in its own BSS (transmissions to the AP from a hidden node). Also, the first STA will not be able to use the medium even if there is medium allocation in a Trigger frame by its own AP, because it senses the medium to be busy. 
     To improve the system level performance and the efficient use of spectrum resources in dense deployment scenarios, the IEEE 802.11ax standard implements a spatial reuse technique. Particularly, the IEEE 802.11ax standard indicates that the STA should have a mechanism to remember and distinguish NAVs set by intra-BSS frame and OBSS frame. In some examples, in order to determine which BSS is the origin of the frame, the standard proposes the use of BSS color. In some examples, BSS color may refer to the BSS identification (ID) associated with each BSS. 
     Thus, STAs can identify signals or frames from OBSS and make appropriate decisions on medium contention and interference management based on this information. For example, when an STA that is actively listening to the medium detects an IEEE 802.11ax frame, the STA checks the BSS color bit or MAC address in the MAC header. If the BSS color in the detected frame is the same color as the one that the STA&#39;s associated AP has already announced, then the STA considers that frame as an intra-BSS frame and sets its intra-BSS NAV. However, if the detected frame has a different BSS color than its own, then the STA considers that frame as an inter-BSS frame from an overlapping BSS and sets its inter-BSS NAV. 
     However, in some situations, it may be difficult to determine whether a detected frame is an intra-BSS frame or an inter-BSS frame due to the lack of BSS color or MAC address associated with the frame. For example, CTS frames or acknowledgment (ACK) frames that are transmitted in response to the RTS frame or data frame respectively, do not generally include BSS information. In such situations, generally the STA does not know whether to set intra-BSS NAV or inter-BSS NAV. In order to resolve the above problem, some systems propose setting the inter-BSS NAV in response to receiving or detecting an in-deterministic frames. However, setting the inter-BSS NAV in response to an in-deterministic frame may result in two issues. 
     First, if, the STA receives a trigger frame from an AP (same BSS as the STA) while the inter-BSS NAV is set, the STA is limited in what it can transmit on the wireless medium if the STA is allocated resources in the trigger fame, also until the inter-BSS NAV counter reaches zero or the STA receives a CF-END frame from an inter-BSS STA the STA cannot access the medium to transmit its data by regular EDCA. Second, because only the inter-BSS NAV was set (and not intra-BSS NAV) based on the in-deterministic frame, if the STA subsequently receives a CF-END from an inter-BSS STA, the STA would be free to access the medium and potentially collide with an intra-BSS transmissions (e.g., another STA communicating with the AP). Thus, such implementations of setting an inter-BSS NAV in response to receiving an in-deterministic frames limits the STA from responding to trigger frames from the AP and/or may cause interference with communications within its own BSS. 
     Aspects of the present disclosure solve the above-identified problems by implementing techniques to increase reuse of the frequency channel by more than one device (e.g., spatial reuse). In accordance with one technique, if the STA receives a trigger frame from an AP after an inter-BSS NAV has been set, the STA may determine whether the inter-BSS NAV was previously set based on an in-deterministic frame (e.g., a frame received by the STA that cannot readily be identified as either intra-BSS frame or an inter-BSS frame). If the inter-BSS NAV was set in response to an in-deterministic frame, aspects of the present disclosure allow for the STA to transmit, in response to receiving the trigger frame and before the inter-BSS NAV is reset, a response to the trigger frame by operating the inter-NAV as an intra-NAV associated with intra-BSS transmissions. Particularly, because trigger frames include resource allocations from the AP that identify the time slots and frequency the STA is to utilize in communicating with the AP for its response, the potential for causing interference on its own BSS is severely minimized. Such an implementation also solves the first problem identified above by not limiting the STA from responding to trigger frames from its own BSS. 
     Another technique may include setting the intra-BSS NAV (in contrast to inter-BSS NAV) in response to receiving an in-deterministic frame. Thereafter, if the STA receives a CF-END frame from an intra-BSS frame, the STA may reset only the intra-BSS NAV in response to the CF-END frame being from an intra-BSS frame. In contrast, if the STA receives the CF-END frame from an inter-BSS frame, the STA may reset only the inter-BSS NAV (while maintaining the inter-BSS NAV), in response to the CF-END frame being from an inter-BSS frame. Thus, in such situations, the STA may be prevented from accessing the wireless medium and causing interference on its own BSS until such time that the STA receives a CF-END frame from an intra-BSS STA. 
     Various concepts will now be described more fully hereinafter with reference to the accompanying drawings. These concepts may, however, be embodied in many different forms by those skilled in the art and should not be construed as limited to any specific structure or function presented herein. Rather, these concepts are provided so that this disclosure will be thorough and complete, and will fully convey the scope of these concepts to those skilled in the art. The detailed description may include specific details. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring the various concepts presented throughout this disclosure. 
       FIG. 1  is a conceptual diagram  100  illustrating an example of a wireless local area network (WLAN) deployment in connection with various techniques described herein. The WLAN may include one or more access points (APs) and one or more mobile stations (STAs) associated with a respective AP. In this example, there are two APs deployed: AP 1   105 - a  in basic service set  1  (BSS 1 ) and AP 2   105 - b  in BSS 2 , which may be referred to as an OBSS. AP 1   105 - a  is shown as having at least two associated STAs (STA 1   115 - a  and STA 2   115 - b ) and coverage area  110 - a , while AP 2   105 - b  is shown having at least two associated STAs (STA 1   115 - a  and STA 3   115 - c ) and coverage area  110 - b . The STAs and AP associated with a particular BSS may be referred to as members of that BSS. In the example of  FIG. 1 , the coverage area of API  105 - a  may overlap part of the coverage area of AP 2   105 - b  such that STA 1   115 - a  may be within the overlapping portion of the coverage areas. The number of BSSs, APs, and STAs, and the coverage areas of the APs described in connection with the WLAN deployment of  FIG. 1  are provided by way of illustration and not of limitation. 
     In some examples, the APs (e.g., AP 1   105 - a  and AP 2   105 - b ) shown in  FIG. 1  are generally fixed terminals that provide backhaul services to STAs  115  within its coverage area or region. In some applications, however, the AP may be a mobile or non-fixed terminal. The STAs (e.g., STA 1   115 - a , STA 2   115 - b  and STA 3   115 - c ) shown in  FIG. 1 , which may be fixed, non-fixed, or mobile terminals, utilize the backhaul services of their respective AP to connect to a network, such as the Internet. Examples of an STA include, but are not limited to: a cellular phone, a smart phone, a laptop computer, a desktop computer, a personal digital assistant (PDA), a personal communication system (PCS) device, a personal information manager (PIM), personal navigation device (PND), a global positioning system, a multimedia device, a video device, an audio device, a device for the Internet-of-Things (IoT), or any other suitable wireless apparatus requiring the backhaul services of an AP. An STA may also be referred to by those skilled in the art as: a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless station, a remote terminal, a handset, a user agent, a mobile client, a client, user equipment (UE), or some other suitable terminology. An AP may also be referred to as: a base station, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, or any other suitable terminology. The various concepts described throughout this disclosure are intended to apply to all suitable wireless apparatus regardless of their specific nomenclature. 
     Each of STA 1   115 - a , STA 2   115 - b , and STA 3   115 - c  may be implemented with a protocol stack. The protocol stack can include a physical layer for transmitting and receiving data in accordance with the physical and electrical specifications of the wireless channel, a data link layer for managing access to the wireless channel, a network layer for managing source to destination data transfer, a transport layer for managing transparent transfer of data between end users, and any other layers necessary or desirable for establishing or supporting a connection to a network. 
     Each of AP 1   105 - a  and AP 2   105 - b  can include software applications and/or circuitry to enable associated STAs to connect to a network via communications link  125 . The APs can send frames or packets to their respective STAs and receive frames or packets from their respective STAs to communicate data and/or control information (e.g., signaling). Each of AP 1   105 - a  and AP 2   105 - b  can establish a communications link  125  with an STA that is within the coverage area of the AP. Communications link  125  can comprise communications channels that can enable both uplink and downlink communications. When connecting to an AP, an STA can first authenticate itself with the AP and then associate itself with the AP. Once associated, a communications link  125  may be established between the AP  105  and the STA  115  such that the AP  105  and the associated STA  115  may exchange frames or messages through a direct communications channel. It should be noted that the wireless communication system, in some examples, may not have a central AP (e.g., AP  105 ), but rather may function as a peer-to-peer network between the STAs. Accordingly, the functions of the AP  105  described herein may alternatively be performed by one or more of the STAs  115 . 
     While aspects of the present disclosure are described in connection with a WLAN deployment or the use of IEEE 802.11-compliant networks, those skilled in the art will readily appreciate, the various aspects described throughout this disclosure may be extended to other networks employing various standards or protocols including, by way of example, BLUETOOTH® (Bluetooth), HiperLAN (a set of wireless standards, comparable to the IEEE 802.11 standards, used primarily in Europe), and other technologies used in wide area networks (WAN)s, WLANs, personal area networks (PAN)s, or other suitable networks now known or later developed. Thus, the various aspects presented throughout this disclosure for performing operations based on modifications and enhancements to dynamic sensitivity control may be applicable to any suitable wireless network regardless of the coverage range and the wireless access protocols utilized. 
     In some aspects, one or more APs ( 105 - a  and  105 - b ) may transmit on one or more channels (e.g., multiple narrowband channels, each channel including a frequency bandwidth) a beacon signal (or simply a “beacon”), via a communications link  125  to STA(s)  115  of the wireless communication system, which may help the STA(s)  115  to synchronize their timing with the APs  105 , or which may provide other information or functionality. Such beacons may be transmitted periodically. In one aspect, the period between successive transmissions may be referred to as a superframe. Transmission of a beacon may be divided into a number of groups or intervals. In one aspect, the beacon may include, but is not limited to, such information as timestamp information to set a common clock, a peer-to-peer network identifier, a device identifier, capability information, a super-frame duration, transmission direction information, reception direction information, a neighbor list, and/or an extended neighbor list, some of which are described in additional detail below. Thus, a beacon may include information that is both common (e.g., shared) amongst several devices and specific to a given device. 
     In some aspects, wireless devices (e.g., STA  115  and/or AP  105 ) may, in order to increase reuse of the spectrum, transmit on top of transmissions coming from an OBSS and refrain from transmitting on top of transmissions coming from the same BSS (also known as in-BSS). To enable a wireless device to determine whether a transmission is from the same BSS as the wireless device or from an OBSS, some packets may have a color code/information that identifies the BSS from which the packets originated, in some cases the BSSID field is also included along with BSS color. Color code/information may be a BSS identifier (BSSID) or a partial BSSID or separate value advertised by the AP. When the wireless device receives a packet with color information, the wireless device may determine if the packet is associated with the same BSS as the wireless device, and may therefore defer transmissions, or if the packet is associated with an OBSS, in which case the wireless device may reuse the spectrum. 
     However, in some situations, it may be difficult to determine whether a detected frame is an intra-BSS frame (e.g., transmitted from BSS 1 ) or an inter-BSS frame (e.g., transmitted from BSS 2 ) due to the lack of BSS color or MAC address associated (BSSID) with the frame. Examples of in-deterministic frames may include, but are not limited to CTS frames or ACK frames. 
     In accordance with one technique, the STA 1   115 - a  sets an inter-BSS NAV in response to receiving an in-deterministic frame. Subsequently, if the STA 1   115 - a  receives a trigger frame from an AP after an inter-BSS NAV has been set, the STA 1   115 - a  may determine whether the inter-BSS NAV was previously set based on an in-deterministic frame. If the inter-BSS NAV was set in response to an in-deterministic frame, aspects of the present disclosure allow for the STA 1   115 - a  to transmit, in response to receiving the trigger frame and before the inter-BSS NAV is reset, a response to the trigger frame by operating the inter-BSS NAV as an intra-BSS NAV associated with intra-BSS transmissions. Particularly, because trigger frames include resource allocations from the AP  105 - a  that identify the duration and frequency the STA 1   115 - a  is to utilize in communicating with the AP  105 - a  for its response, the potential for causing interference on its own BSS (e.g., in BSS 1 ) is minimized. 
     In accordance with another technique, the STA 1   115 - a  may set the intra-BSS NAV (in contrast to inter-BSS NAV) in response to receiving an in-deterministic frame. Thereafter, if the STA 1   115 - a  receives a CF-END frame from an intra-BSS device (e.g., STA 2   115 - b  or AP  105 - a  in BSS 1 ), the STA 1   115 - a  may reset only the intra-BSS NAV in response to the CF-END frame being from an intra-BSS frame. In contrast, if the STA receives the CF-END frame from an inter-BSS device (e.g., STA 3   115 - c  or AP  105 - b  in BSS 2 ), the STA 1   115 - a  may reset only the inter-BSS NAV (while maintaining the inter-BSS NAV), in response to the CF-END frame being from an inter-BSS frame. Thus, in such situations, the STA 1   115 - a  may be prevented from accessing the wireless medium and causing interference on its own BSS until such time that the STA 1   115 - a  receives a CF-END frame from an intra-BSS STA (e.g., STA 2   115 - b ). 
       FIGS. 2A and 2B  are a timing diagrams  200  and  250  associated with managing inter-BSS NAV and intra-BSS NAV based on reception of one or more frames on the shared wireless channel. The timing diagram  200  illustrates an OBSS device  205  that may be an AP or STA as illustrated in  FIG. 1 . In one example, the OBSS device  205  may be an AP  105 - b  and/or STA 3   115 - c  belonging to or being a member of BSS 2  described with reference to  FIG. 1 . Additionally or alternatively, the timing diagram  200  may include a BSS AP  105 - a  (e.g., in-BSS) that may be an example of AP  105 - a  illustrated in  FIG. 1  as being a member of BSS 1 . In some examples, each of the OBSS device  205 , STA  115 - a  and BSS AP  105 - a  may be configured to communicate over the shared wireless channel such that a transmission of a nearby STA or AP may be overheard by another STA. 
     In some aspects, an OBSS device  205  that may be in relatively close proximity to the STA  115 - a  may transmit a first frame  215  (e.g., RTS frame). Due to the proximity of the STA  115 - a  to the OBSS device  205 , the STA  115 - a  may also receive (or detect) the first frame  215  on the wireless channel, even though the STA  115 - a  may not be the intended recipient of the first RTS frame  215 . In some aspects, the STA  115 - a , upon detecting the first frame  215 , may decode portions of the MAC layer frame headers of the first frame  215  to identify a duration field that may specify the transmission time required for the first frame  215  (e.g., based on the size of the packet, the duration field may identify the time the medium may be busy). Because the first frame  215  (e.g., RTS frame or data packet) may include BSS color information in the packet, the STA  115 - a  may also be able to determine that the received first frame  215  is an OBSS frame. Accordingly, in some aspects, the STA  115 - a  may set its inter-BSS NAV  220 - a  based on the information derived from the duration field of the first frame  215 . As noted above, the inter-BSS NAV  220 - a  may be a counter, which counts down to zero at a uniform rate. When the counter is zero, the virtual carrier sense indication is that the medium is idle. In contrast, when the counter has a nonzero value, the carrier sense indication is that the medium is busy. Thus, while the inter-BSS NAV  220 - a  is non-zero value, the STA  115 - a  may be prevented from transmitting on the wireless medium. 
     As noted earlier, WLAN STAs use RTS/CTS frames to mediate access to the shared medium. Thus, an RTS frame  215  may generally correspond with a CTS frame  230  being transmitted by the intended recipient of the RTS frame  215 . In some examples, the period of time between RTS frame  215  and the CTS frame  230  may be based on the short interframe space (SIFS)  225 . In contrast to RTS frame  215 , a CTS frame  230  does not include BSS color information. As such, CTS frame  230  (and ACK frames) are considered to be “in-deterministic” frames because such frames cannot be identified as an intra-BSS frame or an inter-BSS frame based on decoding the frame itself. 
     In some examples, aspects of the present disclosure may attempt to infer whether the in-deterministic frame (e.g., CTS frame  230 ) is an intra-BSS frame or an inter-BSS frame based on the characteristics of a preceding frame (e.g., RTS frame  215 ) detected before the receipt of the in-deterministic frame. In some examples, the STA  115 - a  may determine whether the frame is received at the STA within a threshold period of time (e.g., within SIFS period  225 ) since detecting a preceding frame  215  (e.g., RTS frame or data frame) that included BSS color information, BSSID field, there is a match between the address fields in RTS/Data frames and the frame received. As such, in some aspects, the STA  115 - a  may be configured to identify the in-deterministic frame as the intra-BSS frame or the inter-BSS frame based on determining whether the frame is received within the threshold period of time since detecting the preceding frame. 
     In some examples, the in-deterministic frame  230  may be identified as the intra-BSS frame if the BSSID or BSS color or an address field matches of the preceding frame  215  is associated with the intra-BSS frame and the in-deterministic frame  230  was subsequently received within the threshold period of time of the preceding frame (e.g., SIFS), and/or the address field matches one of the address fields of the preceding frame. Similarly, the in-deterministic frame  230  may be identified as the inter-BSS frame if the BSSID or BSS color or an address field of the preceding frame  215  is associated with the inter-BSS frame and the in-deterministic frame  230  was subsequently received within the threshold period of time of the preceding frame (e.g., SIFS) and/or the address field matches one of the address fields of the preceding frame. Even further, the CTS frame  230  (e.g., in-deterministic frame) may be identified as the inter-BSS frame if the BSSID of the preceding frame is associated with OBSS frame or if the frame was not received within the threshold period of time, or if the preceding frame did not have any of its address fields match with the BSSID of the STA. In the illustrated example, the BSS color information of the preceding frame  215  may correspond to the OBSS frame, the STA  115 - a  may be able to identify the detected CTS frame  230  as a OBSS frame so long as the CTS frame  230  was received within the threshold period of time  225 . 
     In accordance with the first technique of the present disclosure, the STA  115 - a , upon receiving an in-deterministic frame  230  (regardless of whether it is from OBSS device  205  or BSS device (e.g., AP  105 - a  or STA 2   115 - b )), may set the inter-BSS NAV  220 - b . This is illustrated in  FIG. 2B , where in response to receiving an inter-deterministic frame  230  from a BSS device  210 , the STA  115 - a  nonetheless sets the inter-BSS NAV  220  (instead of intra-BSS NAV). In contrast, a frame that includes BSS color information (e.g., RTS frame  215 ) or a frame that has address field(s) that is that may be associated with BSS device  210  may trigger the STA  115 - a  to set the intra-BSS NAV  245 . 
     Returning to the example of  FIG. 2A , in some examples, during the time period that the inter-BSS NAV  220 - b  is set, a trigger frame  235  may be received at the STA  115 - a  from an AP  105 - a  associated with the STA  115 - a . In such situations, the STA  115 - a  may determine if the inter-BSS NAV  220 - b  was previously set based on an in-deterministic frame  230 . If, the inter-BSS NAV  220 - b  was set based on the in-deterministic frame  230 , the STA  115 - a  may be configured to respond  240  to a trigger frame  235  from an AP  105 - a  after the inter-BSS NAV has been set as though the inter-BSS NAV is intra-BSS NAV. In other words, the STA  115 - a  may be configured to transmit, in response to receiving the trigger frame  235  and before the inter-BSS NAV  220 - b  is reset, a response  240  to the trigger frame  235  by operating the inter-BSS NAV as an intra-BSS NAV associated with intra-BSS transmissions. 
       FIG. 3  is another timing diagram  300  of another example of techniques for improving spatial reuse in accordance with aspects of the present disclosure. In accordance with  FIG. 3 , STA  115 - a  may be configured to set the inter-BSS NAV  320  in response to receiving frames that include BSS color information (e.g., RTS frame  315 ) if the RTS frame  315  is received from an OBSS device  305  (e.g., STA 3   115 - c  in  FIG. 1 ). In contrast, if the RTS frame  315  was received from a BSS device  210 , the STA  115 - a  may be configured to set the intra-BSS NAV  335  based on the decoding of the packet. 
     In contrast to the conventional systems, aspects of the present disclosure provide setting the intra-BSS NAV  335  in response to receiving an in-deterministic frame  330 , regardless of whether the in-deterministic frame  330  is received from an OBSS device  305  or BSS device  310 . In accordance with further aspects of the second technique, the STA  115 - a  may reset the intra-BSS NAV  335  in response to the CF-END message  345  being from a BSS device  310  (e.g., based on decoding of an intra-BSS frame). Additionally or alternatively, the STA  115 - a  may reset the inter-BSS NAV  320  in response to the CF-END message  355  being from an OBSS device  305  (e.g., based on decoding of the inter-BSS frame). As such, in some examples, the STA  115 - a  may be configured to transmit data  360  on the wireless channel once the inter-BSS NAV  320  and the intra-BSS NAV  335  have been reset in response to their respective CF-END messages. 
       FIG. 4  is a flowchart conceptually illustrating one example of a method  400  of wireless communication, in accordance with aspects of the present disclosure. For clarity, the method  400  is described below with reference to STA  115   FIG. 1 . 
     At block  405 , the method  400  may include determining, at a STA, that a frame received by the STA cannot be identified as an intra-BSS frame or an inter-BSS frame. In some examples, the method may further include determining whether the frame is received at the STA within a threshold period of time since detecting a preceding frame that included BSSID(s) used by the AP in one of the address field and identifying the frame as the intra-BSS frame or the inter-BSS frame based on determining whether the frame is received with the threshold period of time since detecting the preceding frame, or has address field matching to one of the address field of the preceding frame. The frame may be identified as the intra-BSS frame if the BSSID of the preceding frame is associated with the BSS of the STA, or the frame has the address field that matches one or more of the address fields of the previous frame that was received and that has one of the address field matching the BSSID(s) used by the AP, and the frame was received within the threshold period of time. Alternatively, the frame may be identified as the inter-BSS frame if the BSSID of the preceding frame or any of the address field of the previous frame do not match the BSSID(s) used by the AP of the STA or the frame was not received within the threshold period of time. In some examples, the frame may be one of a CTS or ACK frame that does not include a BSSID. Aspects of  405  may be performed by frame decoding component  655  described in more detail below with reference to  FIG. 6 . 
     At block  410 , the method  400  may include setting a first NAV in response to the determination. In some examples, the first NAV may be associated with inter-BSS transmissions. Aspects of block  410  may be performed by NAV management component  660  described in more detail below with reference to  FIG. 6 . 
     At block  415 , the method may include receiving a trigger after the first NAV is set. In some examples, an AP associated with the STA  115  may transmit the trigger frame. In one or more examples, the trigger frame may include identifications of allocated resources (e.g., time slots and frequency) that STA  115  may use to respond to the trigger frame. Aspects of block  415  may be performed by transceiver  602 , and more specifically the receiver  606  described in more detail below with respect to  FIG. 6 . 
     At block  420 , the method may include transmitting, in response to receiving the trigger frame and before the first NAV is reset, a response to the trigger frame by operating the first NAV as a second NAV associated with intra-BSS transmissions. In some examples, the method may include transmitting the response using resources allocated to the STA by an AP in the trigger frame. Aspects of block  420  may be performed by transmission control component  685  described in more detail below with reference to  FIG. 6 . 
       FIG. 5  is a flowchart conceptually illustrating another example of a method  500  of wireless communication, in accordance with aspects of the present disclosure. For clarity, the method  500  is described below with reference to STA  115  of  FIG. 1 . 
     At block  505 , the method  500  may include determining, at a STA, that a frame received by the STA cannot be identified as an intra-BSS frame or an inter-BSS frame. In some aspects, determining that the frame received by the STA cannot be identified as the intra-BSS frame or the inter-BSS frame comprises failing to identify whether the frame was transmitted by an access point (AP) of same BSS or a different BSS as the STA. In some examples, the method may further include determining whether the frame is received at the STA within a threshold period of time since detecting a preceding frame that included BSSID(s) of the AP of the STA in one or more address fields and identifying the frame as the intra-BSS frame, or the inter-BSS frame based on determining whether the frame is received with the threshold period of time since detecting the preceding frame. The frame may be identified as the intra-BSS frame if the BSSID of the preceding frame is associated with the BSS, or the address fields of the preceding frame match any of the BSSID(s) used by the AP of the STA, and the frame was received within the threshold period of time (e.g., pre-determined inter frame spacing such as SIFS). Alternatively, the frame may be identified as the inter-BSS frame if the BSSID of the preceding frame is associated with OBSS frame, or none of the address fields of the preceding frame do not match the BSSID(s) used by the AP or the frame was not received within the threshold period of time. In some examples, the frame may be one of a CTS or ACK frame that does not include a BSSID. Additionally or alternatively, the frame received at the STA may include a BSSIDs associated with a plurality of APs. Aspects of  505  may be performed by frame decoding component  655  described with reference to  FIG. 6 . 
     At block  510 , the method  500  may include setting a first NAV in response to the determination. In some examples, the first NAV may be associated with intra-BSS transmissions. Aspects of block  510  may be performed by NAV management component  660  described with reference to  FIG. 6 . 
     At block  515 , the method may include receiving a CF-END message from an intra-BSS frame or an inter-BSS frame. Aspects of block  515  may be performed by transceiver  602 , and more specifically the receiver  606  with respect to  FIG. 6 . 
     At block  520 , the method may include resetting the first NAV in response to the CF-END message being from an intra-BSS frame or a second NAV in response to the CF-END message being from an inter-BSS frame. In one or more examples, the second NAV may be associated with inter-BSS transmissions. Aspects of block  520  may also be performed by NAV management component  660  described with reference to  FIG. 6 . 
     At block  525 , the method may include transmitting a packet on a wireless channel after both of the first NAV and the second NAV are reset. In some examples, the method may include transmitting the response using resources allocated to the STA by an AP in the trigger frame. Aspects of block  525  may be performed by transmission control component  685  in conjunction with the transceiver  602  described with reference to  FIG. 6 . 
       FIG. 6  describes hardware components and subcomponents of the STA  115  for implementing one or more methods (e.g., methods  400  and  500 ) described herein in accordance with various aspects of the present disclosure. For example, one example of an implementation of STA  115  may include a variety of components, some of which have already been described above, but including components such as one or more processors  612  and memory  614  and transceiver  602  in communication via one or more buses  644 , which may operate in conjunction with communication management component  650  to enable one or more of the functions described herein related to including one or more methods of the present disclosure. Further, the one or more processors  612 , modem  614 , memory  616 , transceiver  602 , RF front end  688  and one or more antennas  665 , may be configured to support voice and/or data calls (simultaneously or non-simultaneously) in one or more radio access technologies. 
     In an aspect, the one or more processors  612  can include a modem  614  that uses one or more modem processors. The various functions related to communication management component  650  may be included in modem  614  and/or processors  612  and, in an aspect, can be executed by a single processor, while in other aspects, different ones of the functions may be executed by a combination of two or more different processors. For example, in an aspect, the one or more processors  612  may include any one or any combination of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a receiver processor, or a transceiver processor associated with transceiver  602 . In other aspects, some of the features of the one or more processors  612  and/or modem  614  associated with communication management component  650  may be performed by transceiver  602 . 
     Also, memory  614  may be configured to store data used herein and/or local versions of applications or communication management component  650  and/or one or more of its subcomponents being executed by at least one processor  612 . Memory  616  can include any type of computer-readable medium usable by a computer or at least one processor  612 , such as random access memory (RAM), read only memory (ROM), tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, memory  616  may be a non-transitory computer-readable storage medium that stores one or more computer-executable codes defining communication management component  650  and/or one or more of its subcomponents, and/or data associated therewith, when STA  115  is operating at least one processor  612  to execute communication management component  650  and/or one or more of its subcomponents. 
     Transceiver  602  may include at least one receiver  606  and at least one transmitter  608 . Receiver  606  may include hardware, firmware, and/or software code executable by a processor for receiving data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). Receiver  608  may be, for example, a radio frequency (RF) receiver. In an aspect, receiver  606  may receive signals transmitted by at least one AP  105 . Additionally, receiver  606  may process such received signals, and also may obtain measurements of the signals, such as, but not limited to, Ec/Io, SNR, RSRP, RSSI, etc. Transmitter  608  may include hardware, firmware, and/or software code executable by a processor for transmitting data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). A suitable example of transmitter  602  may including, but is not limited to, an RF transmitter. 
     Moreover, in an aspect, STA  115  may include RF front end  688 , which may operate in communication with one or more antennas  665  and transceiver  602  for receiving and transmitting radio transmissions, for example, wireless communications transmitted by at least one base station  105  or wireless transmissions transmitted by STA  115 . RF front end  688  may be connected to one or more antennas  665  and can include one or more low-noise amplifiers (LNAs)  690 , one or more switches  692 , one or more power amplifiers (PAs)  698 , and one or more filters  696  for transmitting and receiving RF signals. 
     In an aspect, LNA  690  can amplify a received signal at a desired output level. In an aspect, each LNA  690  may have a specified minimum and maximum gain values. In an aspect, RF front end  688  may use one or more switches  692  to select a particular LNA  690  and its specified gain value based on a desired gain value for a particular application. 
     Further, for example, one or more PA(s)  698  may be used by RF front end  688  to amplify a signal for an RF output at a desired output power level. In an aspect, each PA  698  may have specified minimum and maximum gain values. In an aspect, RF front end  688  may use one or more switches  692  to select a particular PA  698  and its specified gain value based on a desired gain value for a particular application. 
     Also, for example, one or more filters  696  can be used by RF front end  688  to filter a received signal to obtain an input RF signal. Similarly, in an aspect, for example, a respective filter  696  can be used to filter an output from a respective PA  698  to produce an output signal for transmission. In an aspect, each filter  696  can be connected to a specific LNA  690  and/or PA  698 . In an aspect, RF front end  688  can use one or more switches  692  to select a transmit or receive path using a specified filter  696 , LNA  690 , and/or PA  698 , based on a configuration as specified by transceiver  602  and/or processor  612 . 
     As such, transceiver  612  may be configured to transmit and receive wireless signals through one or more antennas  665  via RF front end  688 . In an aspect, transceiver may be tuned to operate at specified frequencies such that STA  115  can communicate with, for example, one or more AP  105  or one or more cells associated with one or more AP  105 . In an aspect, for example, modem  614  can configure transceiver  602  to operate at a specified frequency and power level based on the UE configuration of the STA  115  and the communication protocol used by modem  614 . 
     In an aspect, modem  614  can be a multiband-multimode modem, which can process digital data and communicate with transceiver  602  such that the digital data is sent and received using transceiver  602 . In an aspect, modem  614  can be multiband and be configured to support multiple frequency bands for a specific communications protocol. In an aspect, modem  614  can be multimode and be configured to support multiple operating networks and communications protocols. In an aspect, modem  614  can control one or more components of STA  115  (e.g., RF front end  688 , transceiver  602 ) to enable transmission and/or reception of signals from the network based on a specified modem configuration. In an aspect, the modem configuration can be based on the mode of the modem and the frequency band in use. In another aspect, the modem configuration can be based on UE configuration information associated with STA  115  as provided by the network during cell selection and/or cell reselection. 
     The communication management component  650  may include a frame decoding component  655  for identifying in-deterministic frames. In some examples, aspects of the frame decoding component  655  may be responsible for attempting to infer whether the in-deterministic frame is an intra-BSS frame or an inter-BSS frame based on the characteristics of a frame or signal detected preceding the receipt of the in-deterministic frame. In some examples, the frame decoding component  655  may determine whether the frame is received at the STA within a threshold period of time (e.g., within SIFS period) since detecting a preceding frame (e.g., RTS frame or Data frame) that included BSS identification(s) (BSSID) used by the AP in one of the address fields. As such, in some aspects, the frame decoding component  655  may be configured to identify the frame as the intra-BSS frame or the inter-BSS frame based on determining whether the frame is received with the threshold period of time since detecting the preceding frame. Particularly, the frame decoding component  655  determines whether the in-deterministic frame is associated with any preceding frame (e.g., CTS message in response to previously sent RTS or an ACK message in response to a data frame that was transmitted). 
     In some examples, the in-deterministic frame may be identified as the intra-BSS frame if the BSSID of the preceding frame (e.g., by having decoded at least a portion of the preceding frame—RTS or data frame) is associated with the BSS of the STA, or an address field matches the BSSID(s) used by the AP of the STA, and the in-deterministic frame was subsequently received within the threshold period of time of the preceding frame (e.g., SIFS). In contrast, the frame decoding component  655  may identify the frame (e.g., in-deterministic frame) as the inter-BSS frame if the BSSID of the preceding frame or any of the address field of the preceding frame is not associated with the BSSID(s) used by the AP of the STA, or if the frame was not received within the threshold period of time. The communication management component  650  may also include NAV management component  660  that sets inter-BSS NAV  670  and/or intra-BSS NAV  680  based on receiving one or more frames. In some aspects, the communication management component  650  may further include transmission control component  685  for transmitting packets on the wireless channel when both the inter-BSS NAV  670  and the intra-BSS NAV  680  counters are zero. The transmission control component  685  may further transmit, in response to receiving the trigger frame and before the inter-BSS NAV is reset, a response to the trigger frame by operating the inter-BSS NAV as an intra-BSS NAV associated with intra-BSS transmissions. 
     The above detailed description set forth above in connection with the appended drawings describes examples and does not represent the only examples that may be implemented or that are within the scope of the claims. The term “example,” when used in this description, means “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other examples.” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and apparatuses are shown in block diagram form in order to avoid obscuring the concepts of the described examples. 
     Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, computer-executable code or instructions stored on a computer-readable medium, or any combination thereof. 
     The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a specially-programmed device, such as but not limited to a processor, a digital signal processor (DSP), an ASIC, a FPGA or other programmable logic device, a discrete gate or transistor logic, a discrete hardware component, or any combination thereof designed to perform the functions described herein. A specially-programmed processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A specially-programmed processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
     The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a non-transitory computer-readable medium. Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a specially programmed processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Also, as used herein, including in the claims, “or” as used in a list of items prefaced by “at least one of” indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). 
     Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media. 
     The previous description of the disclosure is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the common principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Furthermore, although elements of the described aspects and/or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. Additionally, all or a portion of any aspect and/or embodiment may be utilized with all or a portion of any other aspect and/or embodiment, unless stated otherwise. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.