Patent Publication Number: US-2023156087-A1

Title: Wireless local area networks

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation of U.S. application Ser. No. 17/185,541, filed Feb. 25, 2021, U.S. Pat. No. 11,570,251, which is a continuation of U.S. application Ser. No. 15/969,956, filed May 3, 2018, U.S. Pat. No. 10,965,757, which are hereby incorporated by reference. 
    
    
     BACKGROUND 
     In a vehicle, an electronic control unit (ECU) can refer to an embedded system that controls one or more subsystems in the vehicle. Traditionally, ECUs are connected using wired connectors with data communications performed over a field bus. A vehicle can potentially include a large number of ECUs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some implementations of the present disclosure are described with respect to the following figures. 
         FIG.  1    is a block diagram of a vehicle that includes ECUs and network controllers of the ECUs that are interconnected by a vehicle wireless local area network, according to some examples. 
         FIG.  2    is a block diagram of a network controller according to some examples. 
         FIG.  3    is a block diagram of an example arrangement that includes a vehicle wireless local area network and field buses, according to further examples. 
     
    
    
     Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements. The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover, the drawings provide examples and/or implementations consistent with the description; however, the description is not limited to the examples and/or implementations provided in the drawings. 
     DETAILED DESCRIPTION 
     In the present disclosure, use of the term “a,” “an”, or “the” is intended to include the plural forms as well, unless the context clearly indicates otherwise. Also, the term “includes,” “including,” “comprises,” “comprising,” “have,” or “having” when used in this disclosure specifies the presence of the stated elements, but do not preclude the presence or addition of other elements. 
     A vehicle can refer to any type of transport structure to carry cargo and/or people between different physical locations. Examples of vehicles include any or some combination of the following: a car, a truck, a watercraft (e.g., a boat, a yacht, a ship, etc.), an aircraft, a spacecraft, a railed vehicle (e.g., a train), a cargo transportation unit (e.g., a container, a trailer, a platform, etc.), and so forth. 
     Examples of electronic control units (ECUs) that can be included in a vehicle include any or some combination of the following: an engine control module (ECM) for controlling the vehicle&#39;s engine, a powertrain control module (PCM) to control the vehicle&#39;s powertrain, a transmission control module (TCM) to control the vehicle&#39;s transmission, a brake control module (BCM or EBCM) to control the vehicle&#39;s brake subsystem, a central control module (CCM) to control specified functionalities of the vehicle, a central timing module (CTM) to control timings of subsystems in the vehicle, a general electronic module (GEM) to control the vehicle&#39;s electrical subsystem, a body control module (BCM) to control the vehicle&#39;s stabilization subsystem, a suspension control module (SCM) to control the vehicle&#39;s suspension subsystem, a door control unit to control the vehicle&#39;s doors, a power steering control unit to control the vehicle&#39;s power steering subsystem, a seat control unit to control the vehicle&#39;s power seats, a speed control unit to control the vehicle&#39;s speed, a battery management system to manage batteries in the vehicle, a human-machine interface (HMI) to provide an interface through which a human can interact with the vehicle, and so forth. 
     In some examples, field buses are used to interconnect the ECUs. Examples of field buses include a Local Interconnect Network (LIN) bus, a Controller Area Network (CAN) bus, a FlexRay bus, a Time-Triggered Protocol (TTP) bus, a ZigBee bus, or others. 
     A network in a vehicle has to have certain characteristics for reliable performance of the vehicle, including low latency (or bounded latency) and high reliability of data delivery in a timely manner. Certain ECUs of a vehicle are safety related, such as ECUs that control the brake subsystem, engine, power steering, transmission, and other critical subsystems of the vehicle. If data is not timely communicated over the vehicle&#39;s network to ECUs that control safety-related subsystems, then loss of control of the vehicle may occur leading to accidents. 
     In addition to low latency and high reliability, the network of a vehicle should also provide security (to reduce the likelihood of a hacker attacking the subsystems of the vehicle), redundancy to protect against failures of a portion of the network, a reduced communication range to prevent being compromised by a hacker, and other features (discussed further below). 
       FIG.  1    is a block diagram of a vehicle  100  that includes a vehicle wireless local area network (WLAN)  106  to which various ECUs  102 ,  104 , and  120  are wirelessly coupled. Although three ECUs are depicted in  FIG.  1   , it is noted that the vehicle  100  can include less than or more than three ECUs in other examples. 
     The vehicle WLAN  106  can be a WI-FI WLAN (or more simply, a “WI-FI network”) that includes wireless access points (APs)  108  to which the ECUs  102 ,  104 , and  120  are able to wirelessly connect. An AP refers to a networking device with which a wireless device can associate to perform data communications over a wireless link between the wireless device and the AP. Communications in a WI-FI network can be according to the Institute of Electrical and Electronic Engineers (IEEE) 802.11 standards. 
     In some examples, the WI-FI network can be a high frequency, high throughput network, such as according to the IEEE 802.11ay (Next Generation 60 GHz) standard, the IEEE 802.11ad standard (Microwave WI-FI/WiGig), the IEEE 802.11aj (Very High Throughput to Support Chinese Millimeter Wave Frequency Bands (60 GHz and 45 GHz)) standard, and so forth. As used here, a “high frequency” WI-FI network is able to operate using a carrier at a frequency that is greater than or equal to 10 Gigahertz (GHz), in some examples. A “high throughput” WI-FI network is able to transmit data at greater than a specified data rate, for example 10 megabits per second (Mbps). 
     Alternatively, a WI-FI network can also operate using light signals to communicate data wirelessly as a high frequency, high throughput network. The IEEE 802.11bb (Light Communication) group of IEEE 802.11 is developing a proposal for light communications in WI-FI networks. 
     The use of the IEEE 802.11ay, 802.11aj, and 802.11bb technologies can provide wireless connections with low levels of interference (and therefore congestion). In the case of light communications, the light can be fairly directional, and interference can be mitigated by any opaque object, i.e., light does not usually pass through walls to interfere with another network. In the case of IEEE 802.11ay and IEEE 802.11aj (60 GHz), signals are sent at low power and with directional antennas. As a result of directional transmissions and propagation characteristics of the 60 GHz carrier frequency, interference from nearby networks can be reduced. 
     The high throughput capabilities, together with other new features, of the foregoing technologies for implementing the WI-FI network  106  enable low latency and deterministic behavior to be provided for vehicle applications. This is a departure from traditional 802.11 WLAN, where latency and non-deterministic behavior have prevented 802.11 WLAN from being used for time sensitive applications. 
     In some examples, the APs  108  of the WI-FI network  106  are connected to network nodes  110  of the vehicle LAN  106 . The network nodes  110  can include switches, routers, bridges, gateways, and so forth. The network nodes  110  are used to transport data between APs  108 , and also between an AP and another destination, which can be off the vehicle  100 . In other examples, the network nodes  110  can be omitted, and the APs  108  can be connected to one another. 
     Each ECU  102 ,  104 , or  120  includes or is connected to a corresponding network controller. For example, the ECU  102  is associated with a network controller  112 , the ECU  104  is associated with a network controller  114 , and the ECU  120  is associated with a network controller  122 . A “network controller” can refer to a device (e.g., an integrated circuit chip, an electronic device, etc.) that can be used for performing communications over the WI-FI network  106 . The network controller can be implemented using a hardware processing circuit, which can include any or some combination of the following: a microprocessor, a core of a multi-core microprocessor, a microcontroller, a programmable integrated circuit device, a programmable gate array, or any other hardware processing circuit. Alternatively, the network controller can be implemented as a combination of a hardware processing circuit and machine-readable instructions (software and/or firmware) executable on the hardware processing circuit. 
     In the ensuing discussion, it is assumed that the network controller  112  is included in the ECU  102 , the network controller  114  is included in the ECU  104 , and the network controller  122  is included in the ECU  120 . In alternative examples, the network controller  112 ,  114 , and/or  122  can be separate from, but connected to, the corresponding ECU  102 ,  104 , and/or  120 . 
     The example ECU  102  is used to control a brake subsystem  116  of the vehicle  100 . The example ECU  104  is used to control a camera  118  of the vehicle  100 . The example ECU  120  is used to control another subsystem (not shown). 
     Use of the WI-FI network  106  (even over short distances in the vehicle  100 ) can provide cost savings in vehicle manufacturing, installation, and maintenance, for example due to the elimination of a conventional wiring loom and the labor costs associated with its installation. For example, by using the WI-FI network  106 , cables that interconnect (some) ECUs can be omitted. 
     For longer communication paths in a vehicle, the path can be designed using prisms, lenses, mirrors, and various forms of reflectors. Light beams used for data communications can be narrow or wide, depending on the optical transducers used and the specified levels of physical isolation. Correspondingly millimetric beams used for data communications can also be narrow or wide depending on the transducers and isolation of the system. 
     In some examples, each ECU can act as an IEEE 802.11 station (e.g., each ECU has an IEEE 802.11 communications chip, in the form of a respective network controller within it) and connects to an IEEE 802.11 AP, which in turn is connected to the network through a bridge or switch. 
     It is noted that the wireless connections form an automobile WLAN and are not operating as individual point-to-point links in a star and hub configuration. Therefore, traffic from the camera  118  can flow directly to another ECU (e.g.,  120 ), through the WI-FI network  106 . 
     In some examples, an automobile regulatory requirement may specify that a rear-view camera has to turn on and be streaming video to a display screen within 2 seconds (or other time duration) of power on. This can be achieved using either of the following techniques, in some examples. 
     (1) An Optimized Connectivity Experience (OCE) WLAN solution provided by the WI-FI Alliance. OCE is based on IEEE 802.11ai allowing faster and optimized connection set up times. 
     (2) The camera in an IEEE 802.11 network can be operated in a power save mode, and when the camera is awakened, a trigger message according to IEEE 802.11ba (Wake Up Radio) can inform the ECU  104  that a video session is available. This trigger then awakens the network controller of the ECU  104  from a lower power state to a higher power state. 
     In addition, other devices can also be connected to the ECU  104 , so that a link can include several combined data feeds from one area of the vehicle  100  to another area of the vehicle  100 . 
     Synchronized Link 
     A link can be established between network controllers through the WI-FI network  106 . A “link” refers to a logical connection through the WI-FI network  106  between network controllers. In accordance with some implementations of the present disclosure, the link between network controllers is a synchronized link. A synchronized link is a link that couples multiple devices having clocks (discussed further below) that are synchronized with respect to one another. Note that a first network controller can maintain a synchronized link with multiple other network controllers. 
     As further shown in  FIG.  1   , the network controller  112  includes a wireless transceiver  130 , the network controller  114  includes a transceiver  132 , and the network controller  122  includes a transceiver  134 . A transceiver includes a transmitter and a receiver to transmit and receive, respectively, signals. In examples according to  FIG.  1   , the transceivers  130 ,  132 , and  134  are wireless transceivers that are able to communicate wireless signals. 
     In addition, the network controllers  112 ,  114 , and  122  include respective clocks  136 ,  138 , and  140 . A “clock” refers to a device that produces an oscillating signal that controls the timing of circuitry. Network controllers are synchronized to one another if their respective clocks are synchronized, i.e., transition edges of the clocks are aligned in time (to within some specified tolerance) with respect to one another. 
     In some examples, the WI-FI network  106  can include a master clock  124 . The other clocks (e.g.,  136 ,  138 , and  140 ) in the vehicle  100  can be synchronized to the master clock  124 . The master clock  124  can be included in a network node, such as in a switch or other type of network node. Alternatively, the master clock  124  can be included in an ECU that is designated a central ECU (e.g., the ECU  120 ) or an ECU that is designated as a master clock ECU. 
     The master clock  124  can be internally generated in the vehicle  100 , such as based on an oscillator in the vehicle  100 . Alternatively, the master clock  124  can be generated based on information from an external source, such as from GNSS (Global Navigation Satellite System) satellites, an atomic clock, and so forth. 
     In some examples, synchronization of the timings of the clocks in the vehicle  100  can be according to the IEEE 802.1AS standard (also referred to as “Generalized Precision Time Protocol”). 
     In other examples, synchronization of the timings of the clocks in the vehicle  100  can employ different techniques. 
     Synchronizing the clocks of the network controllers allows for operations of the ECUs to be time-aligned with one another, such as to provide consistent transmission delays among the ECUs. 
     Real-Time Access Class 
     In accordance with some implementations of the present disclosure, a real-time access class (or multiple real-time access classes) can be defined for communicating data over the WI-FI network  106  of the vehicle  100 . 
     IEEE 802.11 allows for the definition of access classes to distinguish different types of traffic to be communicated over a WI-FI network. An access class can also define medium access rules for transmission. A real-time access class (referred to as AC_RT) according to some implementations of the present disclosure can be associated with time-sensitive data to be communicated over the WI-FI network  106 . The real-time access class is associated with a real-time WLAN bearer used to carry traffic of the real-time access class. 
     It is noted that traffic can dynamically switch among different access classes, which can be set during the provisioning of the WI-FI network  106 . 
       FIG.  2    shows an example network controller  200 , which can be any of the network controllers  112 ,  114 , and  122  of  FIG.  1   . The network controller  200  includes a clock  202  and a transceiver  204 , similar to those discussed in connection with  FIG.  1   . 
     In addition, the network controller  200  can include an AC_RT queue  206  to buffer data according to the real-time access class. Different queues (not shown) can be provided for other access classes in the network controller  200 . The buffered data in the AC_RT queue  206  can be communicated over a synchronized link  201  through the WI-FI network  106  between network controllers. 
     In some examples, the synchronized link  201  over which data of the AC_RT queue  206  is communicated, may be independent of or separate from other logical links used to carry data of other access classes. This is to prevent synchronous traffic (according to the real-time access class) from being mixed with asynchronous traffic (e.g., according to the legacy access classes, AC_VI, AC_VO, etc.) on the same logical link. 
     In other examples, if the bandwidth and timing capabilities of the WI-FI network  106  that uses high frequency, high throughput technologies are sufficient, then the AC_RT traffic and legacy AC traffic may share the same link, but the WI-FI network  106  that uses high frequency, high throughput technologies would have to be carefully managed to ensure that the AC_RT traffic maintains its target operational envelope (e.g., if interference becomes an issue, non-AC_RT traffic may have to be discarded or buffered). 
     In further examples with multiple real-time access classes, the network controller  200  can include multiple respective AC_RT queues  206 . 
     In examples where multiple real-time access classes are defined, IEEE 802.1Qbv provides a time-aware scheduler  208  so that traffic of different real-time access classes may be carried over one logical link. For example, different real-time access classes (e.g., AC_RT 0 , AC_RT 1 ) may be mapped to respective different priorities, such as the priorities of the IEEE 802.1 Time Sensitive Networking (TSN) technology. The different priorities allows the scheduler  208  to select buffered data from multiple AC_RT queues  206  for transmission over the synchronized link. 
     More generally, the network controller  200  can be configured with media access parameters to allow the network controller  200  to transmit data according to a real-time access class over the synchronized link  201 . 
     Latency 
     The network controller  200  further includes a segmentation logic  210  and a reassembly logic  212 . The segmentation logic  210  divides data in the AC_RT queue  206  into packets (also referred to as protocol data units or PDUs) of a specified size (segmentation size). The divided data can be transmitted by the network controller  200  in respective packets having the segmentation size. Data in received packets (as received by the network controller  200 ) can be reassembled by the reassembly logic  212 . 
     If lower latency is desired, the segmentation size can be reduced. On the other hand, if higher latency can be tolerated, then the segmentation size can be increased. 
     In some examples, segmentation and reassembly performed by the segmentation logic  210  and the reassembly logic  212  can be according to IEEE 802.11ay, 802.11aj or 802.11bb. In other examples, other segmentation and reassembly techniques can be employed. 
     Security 
     In some examples, an IEEE 802.11 security scheme (e.g., WI-FI Protected Access II or WPA2 or any IEEE 802.11 protocol configured to use Robust Security Network (RSN)) can be implemented using a security logic  214  in the network controller  200 , where the security scheme can provide a higher level of security over a link than that of many wired technologies. 
     Each ECU (or other device) that connects to the WI-FI network  106  employs a security protocol and credentials (e.g., a password, a key, etc.) to connect to that WI-FI network  106 . The security protocol can either be standards based or proprietary. 
     It is possible that a single WI-FI network  106  utilizes several security protocols at the same time, again with the assumption that an authentication server can also support the multiple security protocols. 
     A device (any of network nodes  110 , for example) on the WI-FI network  106  can act as an authentication server (possibly co-located with one of the primary ECUs), so that ECUs and devices connecting to and disconnecting from the WI-FI network  106  can be managed. The authentication server can also authenticate the network controllers in the ECUs. In further examples, mechanisms such WI-FI Alliance Device Provisioning Protocol (DPP) Network Introduction, or a Fast Initial Link Setup (FILS) Public Key (defined in IEEE 802.11ai) can be used to allow ECUs to authenticate over a WLAN. Devices can be provisioned with a public key/private key pair signed by a Certificate Authority (CA) trusted by the vehicle to perform authentication. In further examples, devices can also be provisioned with a passphrase that can allow them to authenticate. 
     Provisioning 
     A new ECU (or other device, such as a network controller) placed in the vehicle  100  can be provisioned by a provisioning server (e.g., any of network nodes  110 ) with requirements or parameters to operate over the WI-FI network  106 . Provisioning can be achieved in many ways, using protocols such as DPP. This can be achieved at the time of assembly of the device or ECU, or when a device or ECU is added to the vehicle  100 . Alternatively, a device or ECU can be provisioned remotely, such as over a cellular or other wireless link. 
     Each ECU (or other device) that joins the vehicle&#39;s WI-FI network  106  can be associated with a profile that is provisioned and configured for the WI-FI network  106 . In some examples, a profile can include information relating to transmission power, network bandwidth use, support for a Medium Access Control (MAC) protocol, and so forth. The profile can also include information relating to an operation of the ECU or other device. For example, for a camera, the profile can specify an image resolution. 
     An out-of-band technique (such as DPP) can be used to provision the profile with the ECU (or other device). After the ECU (or other device) is provisioned with the profile, the ECU (or other device) after starting (e.g., powering up, resetting, etc.) is correctly configured to connect to the WI-FI network  106 . Once an ECU (or device) is provisioned, it can set up a secure connection to the WI-FI network  106 . 
     There are also other ways of provisioning ECUs (or other devices), for example, using a manual technique or connecting an ECU (or other device) to an external network (e.g., in a garage or manufacturing plant). 
     Power Saving 
     Power savings can be implemented in the ECUs (or other devices) on the WI-FI network  106 . Since a wireless technology is used, the ECUs (or other devices) can be battery powered (or powered by other alternative power sources). IEEE 802.11 power saving schemes can be used in some examples. 
     In other examples, the vehicle  100  itself can provide environmental inputs. For example, when the vehicle  100  is stationary, signals from on-board sensor(s)  150  can indicate to ECUs (or other devices, such as network controllers) that they can remain in a low power state until the vehicle  100  starts to move again. Such power save information can be transmitted through a power network/bus, using a scheme such as the wake-up radio defined by IEEE 802.11ba or by another method. 
     A network controller within a first ECU can be powered off when the vehicle  100  is powered off, and a network controller within a second ECU can be powered on when the vehicle  100  is powered off. 
     Discovery 
     When an ECU (or device) is either added or removed from the vehicle&#39;s WI-FI network  106 , a discovery process may be performed. The discovery process can be performed in response to any of the following: 1) when all the ECUs are powered up (e.g., the vehicle  100  is powered up), 2) once the vehicle  100  is already powered up (and possibly moving), or 3) a system reset (or re-configuration). 
     The discovery process can operate according to high frequency, high throughput technology used by the WI-FI network  106 , such as by using IEEE 802.11bb, in which light communication devices can find and discover other devices within their vicinity. Alternatively, the discovery process can be performed at a higher layer (e.g. using the IEEE 802.11 MAC layer to find/discovery devices that are physically connected to the WLAN, but require synchronization and packet level discovery). 
     A device in a vehicle can search for a service by a network identifier (e.g., SSID), or the device can search via a Service identifier or hash as specified in IEEE 802.11aq. 
     When a device is installed in a vehicle, there are several possible techniques for discovery and provisioning. First, at the time the device is installed in the vehicle, the device is provisioned with network information and credentials for the vehicle. Second, the vehicle is updated out of band with the device identity and credentials, which allow the device to connect to the vehicle when the device is installed. The device has its credentials installed at the factory. Third, the vehicle is provisioned with credentials using a root CA at manufacturing. The vehicle is provisioned with the root CA information. The vehicle validates the device credentials when the device tries to connect the first time. There may be some user interaction with the vehicle to confirm that the device is being added. 
     Vehicle manufacturers can decide whether the associations (i.e., WLAN sessions) are maintained between powering the vehicle  100  up and down. WLAN sessions (e.g., that include security keys and network addresses such as Internet Protocol (IP) or MAC addresses) can be maintained by regularly updating a cache in an ECU (or several ECUs), so that when the vehicle  100  is powered down, a saved state of the vehicle&#39;s configuration is stored for future use. At the time of power up, the saved state enables all wireless ECUs (or more specifically the network controllers in the ECUs) to quickly re-establish their WLAN sessions and possibly perform a quick integrity check (e.g., by sending ping or keep-alive packets over each link) before any data is transmitted. 
     The security association of each ECU (or other device) can be considered in two contexts. The first begins when the ECU (or other device) is added at the assembly plant, or added by a mechanic, and ends when the part is removed from the vehicle. The second is a session that exists when the ignition key is turned on and ends when the car is turned off. 
     Note though that some of the components may continue to run even when the vehicle  100  is off, and thus a certain portion of the WI-FI network  106  may have to remain powered continually. The continually powered components can include a central computing device that stores ECU/device profiles and credentials for the system. For example, an electric vehicle has a remote prestart function for the climate control feature, and some antitheft systems specify that various electronics/communications links to stay running continually. 
     All or most of the ECUs (or other devices) can be powered down. Similarly, a portion of the vehicle&#39;s WI-FI network  106  can be powered down (e.g., the APs, bridges, and switches). 
     The WI-FI network  106  may also support a cellular backhaul communications link for remote locking/unlocking of the vehicle  100 , for supporting a find-my-car feature, for remotely starting or shutting off the vehicle  100 , and so forth. 
     Legacy Field Buses 
     In addition to the WI-FI network  106 , the vehicle  100  can also include legacy field buses.  FIG.  3    shows an example that includes field buses  302  and  304  connected to respective legacy devices  306  and  308 . Data on a field bus  302  or  304  can be transported by the WI-FI network  106  that includes an AP  310  as shown in  FIG.  3   . 
     Alternatively, the AP  310  can be omitted, so that a direct link can be established between network controllers  313  and  315  through the WI-FI network  106 . 
     A data frame structure used on a field bus  302  or  304  can be carried in IEEE 802.11 data frames over the WI-FI network  106 . 
     Gateways 
     In some examples, a gateway  312  or  314  can be used to encapsulate data, according to a field bus data format, into a frame according to an IEEE 802.11 data format. Each gateway  312  or  314  can include or be coupled to an IEEE 802.11 network controller  313  or  315 , respectively, to communicate over the WI-FI network  106 . In some examples, each gateway  312  or  314  can include or be coupled to a switch that connects into the respective field bus  302  or  304  using a suitable field bus connector. 
     Timing information (e.g. clock signals) may be copied from the field bus packets to serve as metadata or to assist with clock synchronization in the IEEE 802.11 backbone network. 
     The field bus packets are encapsulated into IEEE 802.11 frames by the gateway  312  or  314 , using copies of the field bus addressing as metadata in the IEEE 802.11 backbone network. The IEEE 802.11 frames are then sent to their destinations, which can involve going through another gateway back to a field bus. In other examples, the IEEE 802.11 frames can be sent to a destination on the WI-FI network  106 , so that the frames do not have to traverse through another gateway. 
     Each gateway  312  or  314  also allows a mix of legacy field bus devices and fieldbus-over-802.11 devices to be connected to the WI-FI network  106 . The WI-FI network  106  is completely transparent to the legacy field bus devices. 
     Dongle 
     Instead of using a gateway  312  or  314 , a dongle  316  or  318  can be used instead to communicate data of the legacy field bus device  306  or  308  over the WI-FI network  106 . A dongle allows an IEEE 802.11 station (the network controller  313  or  315 ) to be directly connected to a single legacy field bus device and can connect into the existing field bus connector on that device. As a result, the legacy field bus device does not have to be connected to the field bus. 
     The dongle  316  or  318  performs conversion between field bus frames and IEEE 802.11 frames in similar manner as a gateway  312  or  314 . 
     The dongle  316  or  318  can be separate from a respective field bus device, or alternatively, can be embedded into the field bus device. The embedded dongle can communicate over the WI-FI network  106 , but not over a field bus. 
     A benefit of using an embedded dongle is that the field bus device  306  or  308  would no longer have to be provided with a physical field bus interface, thereby simplifying the field bus device  306  or  308 . 
     Alternatively, a field bus device ( 306  or  308 ) can include a field bus interface as well as an embedded dongle. 
     Management 
     As noted above, a field bus device  306  or  308  connected to a respective field bus  302  or  304  does not know that its data is traversing anything other than the field bus. The IEEE 802.11 bridge (gateway or dongle) is transparent to the endpoints, including the field bus devices  306  and  308 . 
     A field bus  302  or  304  can be an actual bus with multiple field bus devices, or implemented as a dongle (separate or embedded) for a single field bus device. 
     Assuming that the bandwidth and timing requirements of the WI-FI network  106  are sufficient to support field bus traffic, it is also possible that the same WI-FI network  106  can carry normal IEEE 802.11 traffic at the same time, subject to the legacy field bus traffic using different access classes. 
     System Architecture 
       FIG.  2    shows various components, including the scheduler  208 , segmentation logic  210 , reassembly logic  212 , and security logic  214 . These components can be implemented as hardware processing circuits, or as machine-readable instructions executable on a processor to perform tasks. A processor can include a microprocessor, a core of a multi-core microprocessor, a microcontroller, a programmable integrated circuit, a programmable gate array, or another hardware processing circuit. Machine-readable instructions executable on a processor can refer to the instructions executable on a single processor or the instructions executable on multiple processors. 
     A storage medium to store machine-readable instructions can include any or some combination of the following: a semiconductor memory device such as a dynamic or static random access memory (a DRAM or SRAM), an erasable and programmable read-only memory (EPROM), an electrically erasable and programmable read-only memory (EEPROM) and flash memory; a magnetic disk such as a fixed, floppy and removable disk; another magnetic medium including tape; an optical medium such as a compact disk (CD) or a digital video disk (DVD); or another type of storage device. Note that the instructions discussed above can be provided on one computer-readable or machine-readable storage medium, or alternatively, can be provided on multiple computer-readable or machine-readable storage media distributed in a large system having possibly plural nodes. Such computer-readable or machine-readable storage medium or media is (are) considered to be part of an article (or article of manufacture). An article or article of manufacture can refer to any manufactured single component or multiple components. The storage medium or media can be located either in the machine running the machine-readable instructions, or located at a remote site (e.g., a cloud) from which machine-readable instructions can be downloaded over a network for execution. 
     In the foregoing description, numerous details are set forth to provide an understanding of the subject disclosed herein. However, implementations may be practiced without some of these details. Other implementations may include modifications and variations from the details discussed above. It is intended that the appended claims cover such modifications and variations.