Abstract:
A Link Layer (e.g., TCP/IP Layer 1, OSI Layer 2) routing protocol that routes frames from a sending node to a receiving node based upon service solicitation and availability is proposed. The routing protocol may reduce control messages across the layers, and may achieve greater energy efficiency by placing non-participating nodes into a sleep mode for durations of time while an ad hoc network is being utilized by participating nodes. The proposed scheme may also reduce network setup time by enabling routing as soon as a service and corresponding request is initiated.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims the benefit of Indian Patent Application No. 1476/KOL/2009, filed Dec. 28, 2009, which is hereby incorporated by reference in its entirety. 
       BACKGROUND 
       [0002]    Ad hoc networks are decentralized wireless networks which do not rely on a pre-existing infrastructure, such as access points or dedicated routers, but instead utilize each node in forwarding data for other nodes. “For-the-purpose” networks are ad-hoc networks that are formed by a group of nodes utilizing their own wireless interfaces for collaborative tasks. These networks are generally formed when an infrastructure network is either unreliable or non-existent, and therefore are usually short lived and self-centric. By self-centric, it is implied that the node within the network may be disinterested in communication outside the network, for example with the internet. “For-the-purpose” networks may be established for conferences, exhibitions or any other such places. Such networks may or may not have a large number of participating nodes. Typically all nodes may be confined within certain predefined geographical limits. Furthermore, the nodes may be executing a predefined set of services, such as application support and communication services. 
         [0003]    One desire for “for-the-purpose” networks is quick employability to decrease the time required to start communication between nodes. This suggests reducing both network start-up time and the time for formulating a logical distribution infrastructure. In this regard, network start-up time mainly refers to topology awareness before commencement of transmission within a single hop, while logical distribution infrastructure implies the formation of a tree or mesh for distribution of data. These two activities are among the most energy and bandwidth consuming activities on the network, which can influence network performance greatly. 
         [0004]    The IEEE 802.11 standard, broadly used for wireless networking today, is designed to support both infrastructure and ad-hoc wireless networks. IEEE 802.11 coordinates a plurality of nodes&#39; access of the wireless medium through a Distributed Coordination Function (DCF) that is based on a distributed, contention based carrier sensing with collision avoidance (Carrier Sense Multiple Access with Collision Avoidance, or CSMA/CA) Media Access Control (MAC) protocol. Under this protocol, a node wishing to transmit must listen for the channel status during an interval of time called the DCF Inter-Frame Space (DIFS), wherein frames are digital data transmission units. If the channel is found to be busy during the DIFS interval, the sending node may defer its transmission. Control frames of IEEE 802.11 have a duration field which is used to set the Network Allocation Vector (NAV) within the node to identify the time period after which the node enters into a contention phase. If a channel is found to be idle for DIFS, the sending node is free to take control of the wireless medium, and does so by raising a Request to Send (RTS) frame. The receiving node waits for the Small Inter-Frame Space (SIFS) duration, after which it sends a Clear to Send (CTS) frame. Subsequently the sending node sends a DATA frame which the receiving node replies to with an Acknowledgement (ACK) frame, both of which are separated by the SIFS duration. This protocol enables peer-to-peer unicast communication between one-hop neighbors. 
         [0005]    It is convenient to characterize the control and transmission of data over a network using the concept of layers. In these characterizations, a network and what is transmitted over it are divided into separate abstraction layers, where each layer is a collection of similar functions that serve the layer above it, and receives service from the layer below it. 
         [0006]    One model, the Transmission Control Protocol/Internet Protocol (TCP/IP) reference model, abstracts network functions into four layers. TCP/IP Layer 1, the Link Layer, provides the ability to transfer data by managing the delivery of frames through the use of physical addressing. TCP/IP Layer 2, the Network Layer, manages the routing function by maintaining end to end connection from source to target machines using the routing functions. TCP/IP Layer 3, the Transport Layer, provides the inter-process communication, error correction, and other functions, such as reliability management. TCP/IP Layer 4, or the Application Layer, interacts directly with a software application, and determines the identity and availability of communication partners for an application with data to transmit to. 
         [0007]    Under another model, the Open System Interconnection Reference Model (OSI Model), layered communications are abstracted into seven layers. OSI Layer 2, the Data Link layer, is broadly analogous to TCP/IP Layer 1 in that it manages the delivery of data transfers between network entities through physical addressing. OSI Layer 3, the Network Layer, is analogous to the Network Layer of TCP/IP Layer 2. Additional models, both presently existing, or developed in the future, may also be used to characterize network interactivity, however the nomenclature is unimportant, and focus should remain instead on the roles taken by the layers. 
         [0008]    Currently, routing issues for ad-hoc networks are typically controlled from the Network Layer, TCP/IP Layer 2 (OSI Layer 3). Routing and related issues from this layer and above contribute considerable control traffic towards TCP/IP Layer 1, the Link Layer (OSI Layer 2, the Data Link Layer). Moreover, the transmission is essentially uni-casting in nature. To support multicasting and broadcasting, additional provisions should be made and maintained throughout the life of the network. 
         [0009]    Services, another essential component of a network, represent the functionality a network can perform, and typically remain at the core of network operations. Currently the service related issues for ad-hoc networks are addressed at application layer. Service-related provisions also contribute towards control traffic, creating considerable control overhead at TCP/IP Layer 1 (OSI Layer 2), and presenting a high cost for bandwidth scarce “for-the-purpose” networks. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Features of the invention are shown in the drawings, in which like reference numerals designate like elements. The drawings form part of this original disclosure in which: 
           [0011]      FIG. 1  is an example illustration of an embodiment of a routing mechanism (method) from the perspective of a sending node; 
           [0012]      FIG. 2  is an example illustration of an embodiment of a routing mechanism (method) from the perspective of a receiving node; 
           [0013]      FIG. 3  is a transition diagram illustrating an embodiment&#39;s sending state; 
           [0014]      FIG. 4  is a transition diagram illustrating an embodiment&#39;s receiving state; 
           [0015]      FIG. 5  is a table depicting an embodiment&#39;s modifications to wireless network control frames; 
           [0016]      FIG. 6  is an example illustration of a system for network communications; 
           [0017]      FIG. 7  is an example illustration of a system for network communications; and, 
           [0018]      FIG. 8  is an example illustration of a system for network communications. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    In the description which follows, a number of terms are used. Terms may be defined as follows: 
         [0020]    Node. Any device that may interact on a network, including but not limited to a computer, a handheld device, a mobile device, a netbook, a smart phone, mobile internet device, and so on. 
         [0021]    Sending node. A node that is in a state that wishes to transmit data. 
         [0022]    Listening node. Any node that is in a 1-hop vicinity of a sending node. 
         [0023]    Participating node. Any node that determines, based on a service code transmitted by a sending node, that it wishes to participate in communication with the sending node. 
         [0024]    Non-participating node. Any node that determines, based on a service code transmitted by a sending node, that it does not wish to participate in communication with a sending node. 
         [0025]    Referring to  FIG. 1 , in an embodiment of a method  100  at step  105 , the nodes may contend for a channel, using a process such as CSMA/CA, and proceed when the channel is found free. At step  110 , a first frame with an integrated service code is generated. The first frame may be in accordance with any number of routing protocols, including but not limited to any of the IEEE 802.11 specification protocols, such as 802.11a, 802.11b, 802.11 g, and 802.11n. In some embodiments, as illustrated in  FIG. 5 , the first frame may be an Integrated Request to Send (IRTS) frame  510 . In some embodiments, the IRTS frame may comprise an 802.11 RTS frame  515 , which may maintain backwards compatibility with IEEE 802.11. In some embodiments, the frame may also have an integrated frame sequence number, which can differentiate packets of data in the same transmission, or be used to determine whether a transmission was received correctly. Such a frame may be useful in avoiding routing loops by maintaining uniquely identified data packets. 
         [0026]    The service code may be of any suitable type or configuration, including but not limited to a number comprising a node identifier and a unique identification number for a service. As a non-limiting example, in some embodiments the service code could be 64 bits long, wherein the first 48 bits would identify a node within a network, while the remaining 16 bits could define the services extended by the node. The node identifier can be any suitable identifying number, including but not limited to the node&#39;s identification number, for example, the node&#39;s MAC ID number. In an embodiment, a service may be known over a network by the service code. In an embodiment, nodes may store service codes in a code table. In an embodiment, the code table may be periodically refreshed across the nodes. In an embodiment, there may be a default initial set of services. Some default services may perform basic network maintenance and operation management, including but not limited to topology assessment, and code table initialization. 
         [0027]    Once the first frame has been generated, the sending node may have to wait until the network channel is free to transmit the frame. Returning to  FIG. 1 , the signaling process can be seen in step  120 , which calls for transmitting the first frame, such as an IRTS frame, from a sending node to one or more listening nodes. The transmission itself may be over any form of wireless transmitter, including but not limited to the 802.11 standard devices, Bluetooth, and nonstandard proprietary transmitters. The transmission may use any suitable frequency band, including but not limited to the 2.4 GHz Industrial, Scientific, and Medical (ISM) Band, and the 5 GHZ Unlicensed National Information Infrastructure (U-NII) band. 
         [0028]    As seen in step  130 , once the first frame has been transmitted from the sending node to the listening nodes, the sending node determines if at least one of the one or more listening nodes has determined that it is a participating node. In some embodiments, the sending node&#39;s determination process comprises receiving a second frame from each participating node. The second frame may be in accordance with any number of routing protocols, including but not limited to any of the IEEE 802.11 specification protocols, such as 802.11a, 802.11b, 802.11 g, and 802.11n. In some embodiments, as illustrated in  FIG. 5 , the second frame may be an Integrated Clear to Send (ICTS) frame  520 , comprising the receiving node&#39;s identification number including but not limited to the node&#39;s MAC ID number. In some embodiments, the ICTS frame may comprise an 802.11 CTS frame  525 , which may maintain backwards compatibility with IEEE 802.11. In some embodiments, the ICTS frame  520  may also contain a frame sequence number, which can differentiate packets of data in the same transmission, or be used to determine whether a transmission was received correctly. This can be useful in avoiding routing loops by maintaining uniquely identified data packets. 
         [0029]    If there are no participating nodes, then there are no nodes to which data may be transferred. In an embodiment, if no ICTS frames are received by the sending node within a predetermined interval of time, the sending node may mark the transmission accordingly, and may resume with other transmissions on queue. Returning to  FIG. 1 , if there is at least one participating node, however, then the sending node may transmit a piece of data from the sending node to the participating nodes ( 140 ). 
         [0030]    In some embodiments where at least one listening node is a participating node, determining if any listening nodes are participating nodes comprises receiving a second frame from the participating nodes. The method  100  may further comprise receiving a third frame from the participating nodes. In some embodiments, method  100  may further comprise determining path reliability from the third frame ( 160 ). This may be done by any suitable means, including but not limited to comparing the third frame and the second frame to analyze deviation in their existence or content. 
         [0031]    The third frame may be in accordance with any number of routing protocols, including but not limited to any of the IEEE 802.11 specification protocols, such as 802.11a, 802.11b, 802.11 g, and 802.11n. In some embodiments, as illustrated in  FIG. 5 , the third frame may be an Integrated Acknowledgement (IACK) frame  530 , comprising the receiving node&#39;s MAC ID number. In some embodiments, the IACK frame may comprise an 802.11 ACK frame  535 , which may maintain backwards compatibility with IEEE 802.11. In some embodiments, the IACK frame  530  may also contain a frame sequence number, which can differentiate packets of data in the same transmission, or be used to determine whether a transmission was received correctly. As an example, in an embodiment if a sending node in a previous transmission does not receive the third frame (such as an IACK frame) from all participating nodes, then it may try to retransmit the piece of data for participating nodes that raised the second frame (such as an ICTS frame), but did not successfully transmit the third frame to the sending node within a specified time. In an embodiment, the participating node may adopt a suitable strategy for power saving by differentiating between current and retransmitted frames, based on the frame sequence number. 
         [0032]      FIG. 2  illustrates a method  200  for performing routing over a network. One or more listening nodes may initially perform channel assessment  205  to assess the channel state and listen for any on going transmissions. At step  210 , the one or more listening nodes receive a first frame comprising an integrated service code. The first frame may conform to any number of routing protocols, including but not limited to any of the IEEE 802.11 specification protocols, such as 802.11a, 802.11b, 802.11 g, and 802.11n. In some embodiments, as illustrated in  FIG. 5 , the first frame may be an IRTS frame  510 . In some embodiments the frame could also have an integrated frame sequence number, which can differentiate packets of data in the same transmission, or be used to determine whether a transmission was received correctly. Such a frame may be useful in avoiding routing loops by maintaining uniquely identified data packets. In an embodiment, the listening node may be in an idle state when it receives the frame. 
         [0033]    Returning to  FIG. 2 , the illustrated method  200  further comprises step  220 , in which one or more listening nodes determine, based on the integrated service code, if the listening nodes are participating nodes. This determination may be made by any suitable means, including but not limited to comparing the service code with an internal list of approved service codes, or verifying that the service code is not on a list of banned service codes. In an embodiment, a listening node may determine that it is a participating node if it is an intermediate router for next hop neighbors. 
         [0034]    If based on the service code a listening node is a participating node, the participating node may then proceed to step  230 , where it may transmit a second frame. The second frame may be in accordance with any number of routing protocols, including but not limited to any of the IEEE 802.11 specification protocols, such as 802.11a, 802.11b, 802.11 g, and 802.11n. In some embodiments, as illustrated in  FIG. 5 , the second frame may be an ICTS frame  520 . The second frame may comprise the participating node&#39;s identification number including but not limited to the node&#39;s MAC ID number. In some embodiments, the ICTS frame  520  may also contain a frame sequence number, which can differentiate packets of data in the same transmission, again useful in avoiding routing loops by maintaining uniquely identified data packets, or be used to determine whether a transmission was received correctly. 
         [0035]    Returning to the embodiment of  FIG. 2 , as shown in step  240 , the participating node may then receive a piece of data from the sending node. In some embodiments, as seen in step  250 , the method may further comprise transmitting a third frame from the participating nodes to the sending node. This third frame may be in accordance with any number of routing protocols, including but not limited to any of the IEEE 802.11 specification protocols, such as 802.11a, 802.11b, 802.11 g, and 802.11n. In some embodiments, as illustrated in  FIG. 5 , the third frame may be an IACK frame  530 . The third frame may comprise the receiving node&#39;s identification number including but not limited to the node&#39;s MAC ID number. In some embodiments, the IACK frame  530  may also contain a frame sequence number, which can differentiate packets of data in the same transmission, or be used to determine whether a transmission was received correctly. In some embodiments, the participating node may enter an idle state following transmission of the third frame. 
         [0036]    As seen in step  260  of the embodiment of method  200  in  FIG. 2 , some embodiments may further comprise initiating a sleep mode on the listening nodes that are not participating nodes. This sleep mode may be initiated in any suitable way, including, but not limited to, updating the NAV value of the non-participating node, disabling power to the wireless transmitter, entering a reduced power mode, and so on. The duration of the sleep mode may be of any defined time interval, including but not limited to a calculated time wherein the non-participating nodes may awake when the sending nodes and the participating nodes have completed their transmissions. After this, the method may return back to step  205 . 
         [0037]    In an embodiment, this duration includes the time required for any participating nodes to transmit the first frame (which may include the integrated service code), the second frame, the piece of data, and the third frame. As a non-limiting example, in embodiments where the frames are respectively IRTS, ICTS, and IACK, the duration of the sleep mode may be a time t 1 , wherein t 1 =(T IRTS +SIFS+N*T ICTS(N) +α*SIFS+T DATA +N*T IACK(N) )−β*T IACK . Within the calculation of such an embodiment, T values are the time to transmit each frame or piece of data, SIFS is the time of the Small Inter-Frame Space (the time between a data frame and an acknowledgement), N is the number of nodes transmitting the respective frames, and α and β are appropriate constants. In an embodiment, any values of α and β may be used which provide sufficient time for contention and confirmation. In various embodiments, the value of the constant α may be selected to provide time for retransmission of collided ICTS frames that may occur in spite of the common contention process. In some embodiments, the value of β may be chosen such that all non-participating nodes awaken from their sleep modes prior to a subsequent transmission, which may ensure that all nodes have the opportunity to access the medium, and are not habitually asleep when the medium is free for transmission. In an embodiment, β may be selected to provide a fractional time of T IACK . In some embodiments, α and β are approximately 3 and 0.5 respectively. In other embodiments, other values for α and β may of course be used. In some embodiments, after sleeping the node may proceed back to channel assessment (step  205 ), and take part in communication afresh. 
         [0038]    In an embodiment illustrated in  FIG. 3 , the sending node may move from an idle state  300  to enter a contending loop  310 , where it waits until a channel is acquired  315 , and the node is free to begin signaling  320 . In the illustrated embodiment, signaling  320  comprises transmitting a first frame  325 , such as an IRTS frame. After transmitting the first frame  325 , the sending node enters a receiving state  330 , where it waits to receive a second frame  335 , such as an ICTS frame from any participating nodes. The duration by which the sending node waits after receiving the second frame may be any suitable time, including but not limited to a time that is greater than or equal to a integer multiple of the SIFS interval. If the number of second frames, such as ICTS frames, received by the sending node equals zero, represented in  FIG. 3  as n(ICTS)=0, then the sending node may presume that there are no participating nodes, and may return to the idle state  300 , where it may wait before attempting to send or receive its next transmission. If the number of second frames received by the sending node is greater than or equal to one, represented in the illustrated embodiment as n(ICTS)≧1, then the sending node is free to begin transmitting data  340 . In an embodiment, after transmitting data, the sending node may wait to receive a third frame  345 , represented in the illustrated embodiment as an IACK frame, which it may use to determine path reliability. 
         [0039]    In an embodiment, as seen in  FIG. 4 , a listening node may wait in an idle state  400  until it receives a first frame  425 , such as an IRTS frame, from a sending node. The listening node then enters a signaling state  430 , where it may determine based on the service code within the first frame whether the listening node is a participating node or a non-participating node. If the listening node is a participating node, it transmits a second frame  435 , such as an ICTS frame, to the sending node. The participating node is then free to begin receiving data  440 . In an embodiment, the receiving node may transmit a third frame  445 , such as an IACK frame, which may allow the sending node to determine path reliability. 
         [0040]    If after receiving the first frame  425  the listening node determines based on the service code within the first frame that it is a non-participating node, then the listening node may enter a sleep state  450 . This sleep state may be for any suitable duration, including the time required for any participating nodes to transmit the first frame (which may include the integrated service code), n(ICTS) frames, the piece of data, and n(IACK) frames. After the sleep duration is complete, the non-participating node may awake  460 , and return to an idle state  400 , wherein it may wait before attempting to send or receive its next transmission 
         [0041]    Turning now to  FIG. 6 , embodiments may also include a system for network communications containing a sending node  600 . The sending node  600  may be of any suitable type, including but not limited to, a desktop computer, a laptop computer, a netbook, a handheld device, a smart-phone, and so on. The system contains at least one first processor  610 . The first processor  610  may be of any suitable type or configuration, including but not limited to a computer processor, a network processor, a microprocessor, or an integrated circuit. The first processor  610  may be configured to execute sending instructions  620 . The sending instructions  620  may comprise a step of generating a first frame with an integrated service code. The first frame can be any suitable type or configuration, including but not limited to an IRTS frame, depicted as IRTS frame  510  in  FIG. 5 . Returning to  FIG. 6 , the service code can be of any suitable type, including but not limited to a service code comprising a node identifier and a unique identification number for a service. Sending instructions  620  also may comprise transmitting the first frame from the sending node  600  to one or more listening nodes  640 . The transmission process can be performed by any suitable means, including but not limited to via a transmitter-receiver, or as shown in the non-limiting embodiment in  FIG. 6 , via a wireless transceiver  630 . Sending instructions  620  may further comprise determining if at least one or more listening nodes  640  are participating nodes  650 . This may be accomplished by any suitable means, including but not limited to, receiving a second frame from the participating nodes  650 . Sending instructions  620  may further comprise transmitting a piece of data from the sending node  600  to the participating nodes  650 . 
         [0042]    As depicted in  FIG. 7 , in some embodiments of the system comprising the sending node  600 , at least one or more listening nodes  640  may comprise at least one second processor  710 , which may be of any suitable type or configuration, including but not limited to a computer processor, a network processor, a microprocessor, and an integrated circuit. The second processor  710  may be configured to execute receiving instructions  720 . The receiving instructions  720  may comprise a step of receiving the first frame. The first frame can be any suitable type or configuration, including but not limited to an IRTS frame, depicted as IRTS frame  510  in  FIG. 5 . Returning to  FIG. 7 , receiving instructions  720  may further comprise determining, based on the service code, if the listening node  640  is a participating node. If the listening node  640  is a participating node, receiving instructions  720  typically further comprise transmitting a second frame from the listening node  640  to the sending node  600 . The second frame may be of any suitable type or configuration, including but not limited to an ICTS frame, depicted as ICTS frame  520  in  FIG. 5 . 
         [0043]      FIG. 8  is a block diagram illustrating an example computing device  900  that is arranged for service oriented ad-hoc wireless network communications in accordance with the present disclosure. In a very basic configuration  901 , computing device  900  typically includes one or more processors  910  and a system memory  920 . A memory bus  930  may be used for communicating between processor  910  and system memory  920 . 
         [0044]    Depending on the desired configuration, processor  910  may be of any type including but not limited to a microprocessor (μP), a microcontroller (μC), a digital signal processor (DSP), or any combination thereof. Processor  910  may include one more levels of caching, such as a level one cache  911  and a level two cache  912 , a processor core  913 , and registers  914 . An example processor core  913  may include an arithmetic logic unit (ALU), a floating point unit (FPU), a digital signal processing core (DSP Core), or any combination thereof. An example memory controller  915  may also be used with processor  910 , or in some implementations memory controller  915  may be an internal part of processor  910 . 
         [0045]    Depending on the desired configuration, system memory  920  may be of any type including but not limited to volatile memory (such as RAM), non-volatile memory (such as ROM, flash memory, etc.) or any combination thereof. System memory  920  may include an operating system  921 , one or more applications  922 , and program data  924 . Application  922  may include a service oriented network routing algorithm  923  that is arranged to perform the functions as described herein including those described with respect to method  100  of  FIG. 1 , or method  200  of  FIG. 2 . Program data  924  may include service oriented identification data  925  that may be useful for determination if a listening node is a participation node, and to ensure communication reliability by matching the information conveyed in various frames, for example the ICTS frame and the IACK frame as is described herein (e.g. as shown in  FIGS. 1-4 ). In some embodiments, application  922  may be arranged to operate with program data  924  on operating system  921  such that determinations of network participation based on the applicable service may be made as described herein. This described basic configuration  901  is illustrated in  FIG. 8  by those components within the inner dashed line. 
         [0046]    Computing device  900  may have additional features or functionality, and additional interfaces to facilitate communications between basic configuration  901  and any required devices and interfaces. For example, a bus/interface controller  940  may be used to facilitate communications between basic configuration  901  and one or more data storage devices  950  via a storage interface bus  941 . Data storage devices  950  may be removable storage devices  951 , non-removable storage devices  952 , or a combination thereof. Examples of removable storage and non-removable storage devices include magnetic disk devices such as flexible disk drives and hard-disk drives (HDD), optical disk drives such as compact disk (CD) drives or digital versatile disk (DVD) drives, solid state drives (SSD), and tape drives to name a few. Example computer storage media may include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. 
         [0047]    System memory  920 , removable storage devices  951  and non-removable storage devices  952  are examples of computer storage media. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which may be used to store the desired information and which may be accessed by computing device  900 . Any such computer storage media may be part of computing device  900 . 
         [0048]    Computing device  900  may also include an interface bus  942  for facilitating communication from various interface devices (e.g., output devices  960 , peripheral interfaces  970 , and communication devices  980 ) to basic configuration  901  via bus/interface controller  940 . Example output devices  960  include a graphics processing unit  961  and an audio processing unit  962 , which may be configured to communicate to various external devices such as a display or speakers via one or more A/V ports  963 . Example peripheral interfaces  970  include a serial interface controller  971  or a parallel interface controller  972 , which may be configured to communicate with external devices such as input devices (e.g., keyboard, mouse, pen, voice input device, touch input device, etc.) or other peripheral devices (e.g., printer, scanner, etc.) via one or more I/O ports  973 . An example communication device  980  includes a network controller  981 , which may be arranged to facilitate communications with one or more other computing devices  990  over a network communication link via one or more communication ports  982 . 
         [0049]    The network communication link may be one example of a communication media. Communication media may typically be embodied by computer readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave or other transport mechanism, and may include any information delivery media. A “modulated data signal” may be a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media may include wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, radio frequency (RF), microwave, infrared (IR) and other wireless media. The term computer readable media as used herein may include both storage media and communication media. 
         [0050]    Computing device  900  may be implemented as a portion of a small-form factor portable (or mobile) electronic device such as a cell phone, a personal data assistant (PDA), a personal media player device, a wireless web-watch device, a personal headset device, an application specific device, or a hybrid device that include any of the above functions. Computing device  900  may also be implemented as a personal computer including both laptop computer and non-laptop computer configurations. 
         [0051]    The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. 
         [0052]    With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. 
         [0053]    It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” 
         [0054]    In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. 
         [0055]    As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth. 
         [0056]    While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.