# Patent

## Title
Hardware control interface for IEEE standard 802.11

## Abstract

A standardized 802.11 hardware control interface may be provided such that a driver may communicate with any one or more of a variety of network adapters.

## Background
BACKGROUND
1. Field of Invention
The techniques described herein relate to wireless network communication, and in particular to a hardware control interface for IEEE standard 802.11.
2. Discussion of Related Art
Computers are sometimes configured to communicate wirelessly with other devices using radio frequency messages that are exchanged in accordance with IEEE standard 802.11. To send and receive wireless messages, software running on a computer communicates with a driver, which is software running on the computer that is specially configured to control a particular wireless network adapter to engage in wireless communication. Wireless network adapters that conform to IEEE standard 802.11 include a radio that transmits and receives radio frequency messages.
SUMMARY
Applicants have developed, a standardized hardware control interface for IEEE standard 802.11 that can be used with any of a variety of different types of 802.11 network adapters and 802.11 software drivers. Previously, a hardware-specific driver needed to be developed for each type of network adapter, including a hardware-specific hardware control interface to control a particular network adapter. By standardizing the hardware control interface for IEEE standard 802.11, the design of software drivers and network adapters may be simplified. Software drivers may be designed such that the information that they exchange with a network adapter conforms to the standardized host control interface. Network adapters may be designed such that the information they exchange with a software driver conforms to the standardize host control interface. As a result, system reliability may be improved.
In some embodiments, hardware control interface may include four “core” interface components, including for example a transmission control interface component, a transmission status interface component, a reception control interface component and a channel switching interface component. However, the invention is not limited in this respect, as in some embodiments different numbers and/or types of interface components may be used.
One embodiment relates to a computer system that includes a processing unit including at least one processor and a driver module that executes on the processing unit. The driver module includes a hardware control interface. The driver module may be configured to at least partially control a network adapter to engage in communication in accordance with IEEE standard 802.11 using the hardware control interface. The hardware control interface may be designed to exchange network adapter independent control information with at least two network adapters of different types.
Another embodiment relates to a computer system comprising a driver module that at least partially controls a network adapter to engage in wireless communication in accordance with IEEE standard 802.11. The computer system may include a computer-readable medium having computer-executable instructions, which, when executed, perform a method that includes exchanging control information. The driver module exchanges control information with the network adapter to at least partially control the network adapter. The control information may be exchanged with the network adapter via a hardware control interface. The hardware control interface may be designed to exchange network adapter independent control information with at least two network adapters of different types.
Yet another embodiment relates to a method of developing a driver module. The method includes analyzing a hardware control interface developed by a first developer entity that is independent of second developer entity which is developing the driver module. The hardware control interface has been developed such that at least two network adapters of different types can exchange network adapter independent control information via the hardware control interface. The method also includes designing a driver to at least partially control one or more of the at least two network adapters via the hardware control interface to engage in IEEE 802.11 wireless communication.



BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:
FIG. 1 is a block diagram illustrating an example of a computing environment having a standardized hardware control interface, according to some embodiments;
FIG. 2 illustrates transmission control information that may be provided to a network adapter by a hardware control interface, according to some embodiments;
FIG. 3 illustrates transmission status information that may be provided to a driver module by a network adapter, according to some embodiments;
FIG. 4 illustrates reception control information that may be provided to a hardware control interface by a network adapter, according to some embodiments;
FIG. 5 illustrates an exemplary computing system on which embodiments may be implemented;
FIG. 6 is a flow chart illustrating an address matching stage, according to some embodiments;
FIG. 7 is flow chart illustrating processing logic after a packet passes an address matching stage, according to some embodiments;
FIG. 8 is flow chart illustrating BSSID matching procedure, according to some embodiments;
FIG. 9 illustrates a key lookup procedure, according to some embodiments; and
FIGS. 10-13 illustrate transmitter-receiver timing diagrams, according to some embodiments.



DETAILED DESCRIPTION
As discussed above, some computers are configured to engage in wireless communication using a specially-designed driver that controls a network adapter to communicate according to IEEE standard 802.11. Previously, each driver was specially designed to function with a single type of network adapter. As a consequence, a different type of software driver has been provided to control each different type of network adapter. Different developers might design their drivers and/or network adapters differently, resulting in different information being exchanged between them. Additionally, a developer might design one driver to function with a particular model of network adapter and another driver to function with a different model, as different network adapter models might have different specifications. For example, different network adapter models might be configured to engage in wireless communication at different speeds. One network adapter might be capable of communicating at a relatively low speed (e.g., in accordance with IEEE Standard 802.11b), but a different network adapter may be capable of communicating at a relatively high speed (e.g. in accordance with IEEE Standard 802.11g). As a result, previous interfaces between drivers and network adapters might be different depending on the requirements of a particular network adapter.
Applicants have appreciated that a variety of problems may arise from providing hardware control interfaces that are specialized to a particular type of network adapter. As one example, creating new drivers for each different type of network adapter may be expensive and time-consuming for network adapter developers, as they may need to develop and test the network adapters with their drivers for each new network adapter released. As another example, specialized hardware control interfaces are sometimes not designed adequately to perform at the speeds required by IEEE standard 802.11, particularly when control information is exchanged over a serial bus (such as a universal serial bus), possibly causing the driver to crash.
Applicants have developed a standardized hardware control interface for network adapters that communicate according to IEEE standard 802.11. Providing a standard hardware control interface may simplify network adapter and software driver development. As a result, network adapters may be designed to function with a standardized hardware control interface, relieving network adapter developers of the need to provide such an interface and increasing software driver reliability.
FIG. 1 is a block diagram illustrating an example of a computing environment 1, according to some embodiments. Computing environment 1 includes a computer 2 that runs software module 3 and a driver module 4. Driver module 4 includes a hardware control interface 5 having a plurality of interface components (a, b and c) for interfacing with a network adapter. Computing environment 1 also includes a network adapter having a radio 7 for engaging in wireless radio frequency communications.
Software module 3 may engage in network communication over a wireless network via driver module 4. Driver module 4 may send and/or receive one or more control messages with network adapter 6, which controls radio 7 to engage in wireless radio frequency communications, including the sending and/or receiving of a wireless message. Using radio 7, network adapter 6 may enable computer 1 to communicate with another wireless-enabled device. It should be appreciated that network adapter 6 may engage in wireless communication with any suitable device, as the techniques described herein are not limited in any way by the device with which wireless communication is performed.
Computer 2 may be any suitable type of computing device that includes at least one processor. By way of example and not limitation, computer 1 may be a laptop computer, a desktop computer, a cellular telephone or a personal digital assistant. In some embodiments, the at least one processor processors may have an operating system that executes thereon. Software module 3 may be any suitable software that executes on the processing unit. In some embodiments, software module 3 may be a portion of the operating system configured to support network communications, but the invention is not limited in this respect. As one example, software module 3 may be a portion of the TCP/IP (Transport Control Protocol/Internet Protocol) stack.
Software module 3 may engage in network communication by exchanging information with driver module 4. Driver module 4 may be a software module that executes on a processing unit of computer 2, and may be configured to control a network adapter to engage in wireless communications in accordance with IEEE standard 802.11. Driver module 4 may exchange control signals with network adapter 6 via a hardware control interface 5. Hardware control interface 5 may be a portion of driver module 4 that is configured to exchange control information with network adapter 6 for wireless communications according to IEEE standard 802.11, as discussed in further detail below. Network adapter 6 may include hardware, firmware and/or software configured to exchange control information with driver module 4 via hardware control interface 5. At least partially based on the control information exchanged with driver module 4, network adapter 6 may send and/or receive data via a wireless medium by controlling radio 7 to transmit and/or receive wireless messages in accordance with IEEE standard 802.11.
In one embodiment, hardware control interface 5 may be a standardized hardware control interface. The term “standardized” means that the hardware control interface is configured to exchange control information with a plurality of different types of network adapters. Thus, any of a variety of different network adapters may be configured to exchange information with driver module 4 using hardware control interface 5. Hardware control interface 5 may be network adapter independent, such that hardware control interface 5 is suitable for operating with any suitable type of network adapter. Providing a standardized hardware control interface may simplify network adapter design, development and testing and increase network adapter reliability, which are key benefits to a standardized hardware interface in some embodiments.
Hardware control interface 5 may exchange information with network adapter 6 using any suitable type of data bus. Thus, in one aspect, hardware control interface may be bus-independent such that it is capable of operating with any of a plurality of different bus types, such as a serial bus or a parallel bus.
Hardware control interface 5 may include one or more interface components, such as interface components 5a, 5b and 5c. In one aspect, a standard hardware control interface may include a relatively small number of interface components, such as less than fifty and/or less than ten. Providing a standard hardware control interface with a relatively small number of hardware control interface components may simplify driver and network adapter design compared with prior systems. Each network interface component may be configured to send and/or receive a portion (a “field”) of the control information exchanged with a network adapter, as will be discussed in further detail below.
In some embodiments, hardware control interface 5 may include a transmission control interface component 5a. The transmission control interface component 5a may be configured to provide transmission control information to network adapter 6 for the transmission of data packets) on the wireless medium. Any suitable type of transmission control information may be provided, some examples of which are illustrated in FIG. 2.
FIG. 2 illustrates an example of transmission control information 20 that may be provided to network adapter 6 using transmission control interface 5a in accordance with one embodiment, although the invention is not limited the example illustrated in FIG. 2. The transmission control information may include one or more fields 21 of transmission control information 20 that the transmission control interface is configured to provide.
As illustrated in FIG. 2, a first field may include one or more flags that indicate a parameter of the data transmission. Any suitable types of flags may be used, such as a flag that indicates whether the wireless medium is to be held or released after transmission of a packet, whether acknowledgement is required for a wireless message, whether a packet is to be encrypted, the type of packet preamble to be used, and/or any other suitable type of flag that indicates any suitable transmission-related information. A flag may include a single bit or multiple bits. In one aspect, seven or more flags may be used, as illustrated in FIG. 2. However, it should be appreciated that any suitable number of flags may be used, as the techniques described herein are not limited in this respect.
As further illustrated in FIG. 2, a second field may include information relating to the transmission rate that is to be used by the network adapter. A third field may include arbitration inter-frame space number (AIFSN) information. A fourth field may include maximum and/or minimum contention window size information (CWmin, CWmax). A fifth field may include basic service set (BSS) information and/or peer table information. However, it should be appreciated that these are only examples of information that may be provided by transmission control interface component 5a to at least partially control network adapter 6, and the techniques described herein are not limited to the exchange of these particular types of information. In some embodiments, this information may be provided by transmission control interface component 5a in the same field and/or bit configuration and having the same order as illustrated in FIG. 2. However, exchange of other types of information and/or other data configurations are possible.
In some embodiments, hardware control interface 5 may include a transmission status interface component 5b configured to provide transmission status information to driver module 4 regarding the status of a transmission by the network adapter.
FIG. 3 illustrates an example of transmission status information 25 provided by network adapter 6 and received by a transmission status interface component 5b, although the invention is not limited to the example illustrated in FIG. 3. As discussed above with respect to transmission control interface component 5a, the transmission status interface component 5b may include one or more fields 36 of transmission status information 25 that the transmission status interface component 5b is configured to receive.
As illustrated in FIG. 3, a first field may include one or more flags related to the status of the transmission. Any suitable transmission status flags may be used, such as a flag that indicates the failure of transmission. A second field may include information about the number of times that the network adapter has attempted to re-transmit a packet. A third field may include transmission rate information indicating, the data rate at which a packet was successfully transmitted. A fourth field may include information about the data rate at which an 802.11 acknowledgement frame (ACK frame) was received. A fifth field may include received signal strength information (RSSI) about the strength of the signal received by the network adapter. A sixth field may include information related to a noise floor of an 802.11 ACK frame. In some embodiments, this information may be provided to transmission status interface component 5b in the same field and/or bit configuration and having the same order as illustrated in FIG. 3. However, exchange of other types of information and/or other data configurations are possible.
In some embodiments, hardware control interface 5 may include a reception control interface component. The reception control interface component may be configured to receive reception control information from network adapter 6 for the reception of data. Any suitable type of reception control information may be provided.
FIG. 4 illustrates an example of reception control information 30 provided by network adapter 6 and received by a reception control interface component 5c, although the invention is not to the example illustrated in FIG. 4. As discussed above with respect to transmission control interface component 5a, the reception control interface component 5c may include one or more fields 31 of reception control information 30 that the reception control interface component 5c is configured to receive.
As illustrated in FIG. 4, a first field may include one or more flags that indicate a parameter of the data reception. Any suitable types of flags may be used, such as a flag that indicates whether a buffer (e.g., a reception buffer of network adapter 6) has overflowed, whether a reception error has occurred, whether an address has been matched, whether a key is available, whether decryption of a received packet has failed, whether the received packet is a probe response, and/or any other suitable reception related information. In one aspect, six or more flags may be used, as illustrated in FIG. 4
A second field may include information about the rate at which data is received by the network adapter 6. A third field may include information about the strength of the signal carrying the received data. A fourth field may include information about the noise floor, such as how much background noise is present on the wireless medium. A fifth field may include information indicating the channel on which a particular packet has been received. A fifth field may include information indicating a time at which a packet was received. However, it should be appreciated that these are only examples of information that may be provided to reception control interface component 5c by network adapter 6, and the techniques described herein are not limited to the exchange of these particular types of information. In some embodiments, this information may be received by reception control interface component 5c in the same field and/or bit configuration and having the same order as illustrated in FIG. 4. However, exchange of other types of information and/or other data configurations are possible.
Three examples of host control interface components have been described with respect to FIGS. 1-4. However, any of a variety of hardware control interface components may be used. One example is an interface component configured for the exchange of channel control information for switching between different channels. The channel control information may include a first field related to a band or channel, a second field that includes a power level for transmitting via a new channel and/or a third field that includes one or more transmission queue flags Another example of a hardware control interface component is an interface component configured to provide beacon transmission control information to network adapter 6 such that network adapter 6 transmits IEEE standard 802.11 beacon messages. Yet another example is an interface component configured to exchange power control information with network adapter 6. Further illustrative interface components are described in further detail below in the section entitled. “Example 1.”
As discussed above, one embodiment is directed to employing a standardized hardware control interface for use with IEEE standard 802.11 wireless communications. As used herein, the term IEEE standard 802.11 refers to the 802.11 family of standards. The techniques described herein may be used for any of these standards, including legacy IEEE standard 802.11, IEEE standard 802.11b, IEEE standard 802.11a, IEEE standard 802.11g, IEEE standard 802.11n or any other suitable 802.11 standard including those developed hereafter.
A computing system will now be described, on which embodiments of the invention may be implemented. With reference to FIG. 5, an exemplary system for on which embodiments of the invention may be implemented includes a computing device, such as computing device 40, which may be a device suitable to function as computer 2, for example. Computing device 40 may include at least one processing unit 41 and memory 42. Depending on the exact configuration and type of computing device, memory 42 may be volatile, non-volatile or some combination of the two. One possible configuration is illustrated in FIG. 5 by dashed line 43. Additionally, device 40 may also have additional features/functionality. Memory 42 is a form of computer-readable media that may store information such as computer-readable instructions, which, when executed, implement software module 3, driver module 4 and/or hardware control interface 5.
Device 40 may include at least some form of computer readable media. Computer readable media can be any available media that can be accessed by device 40. By way of example, and not limitation, computer readable media may comprise computer storage media and communication media. For example, device 40 may also include additional storage (removable and/or non-removable) including, but not limited to, magnetic or optical disks or tape. Such additional storage is illustrated in FIG. 5 by removable storage 44 and non-removable storage 45. Computer storage media includes 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. Memory 12, removable storage 44 and non-removable storage 45 are all examples of computer storage media.
Device 40 may also include output device(s) 46, input device(s) 47 and/or one or more communication connection(s) 48. Communication connection(s) 48 may include, for example, a bus interface that enables device 40 to communicate with network adapter 6 via any suitable data bus, such as a parallel bus or a serial bus.
It should be appreciated that the invention is not limited to executing on any particular system or group of systems. For example, embodiments of the invention may run on one device or on a combination of devices. Also, it should be appreciated that the invention is not limited to any system or network architecture
Example 1
One exemplary embodiment will now be described with respect to an illustrative hardware control interface specification. It should be appreciated that the illustrative specification is merely one possible implementation according to the techniques described herein, as the techniques described herein are not limited to those described in the following illustrative specification. Furthermore, although the following specification contains words such as “shall” and “must,” such words only apply to with respect to the illustrative specification below, as other embodiments are not so limited. 
























































Having now described some embodiments of the invention, it should be apparent to those skilled in the art that the foregoing is merely illustrative and not limiting, having been presented by way of example only. Numerous modifications and other embodiments are within the scope of one of ordinary skill in the art and are contemplated as falling within the scope of the invention. The foregoing description and drawings are by way of example only. In particular, although many of the examples presented herein involve specific combinations of method acts or system elements, it should be understood that those acts and those elements may be combined in other ways to accomplish the same objectives. Acts, elements and features discussed only in connection with one embodiment are not intended to be excluded from a similar role in other embodiments.
Use of ordinal terms such as “first”, “second”, “third”, etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements. The use of “including,” “comprising,” or “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

## Claims

1. A method performed on a computing device, the method comprising: exchanging information via a hardware control interface (“HCI”) between a hardware network adapter and a driver software module that corresponds to the hardware network adapter, where the hardware control interface is configured for operating with a variety of different hardware network adapters of different types, where the different hardware network adapters include the hardware network adapter, and where the hardware control interface is network adapter independent.

2. The method of claim 1 where the hardware control interface is configured for supporting at least a portion of a wireless communication standard.

3. The method of claim 1 where the hardware control interface comprises:
a transmission control interface;
a transmission status interface;
a reception control interface; or
a channel switching interface.

4. The method of claim 1 where the driver software module comprises the hardware control interface.

5. The method of claim 4 where the driver software module controls the hardware network adapter according to at least a portion of a wireless communication standard.

6. The method of claim 5 where the wireless communication standard comprises at least one 802.11 standard.

7. The method of claim 1 where the hardware control interface is implemented at least in part in software.

8. At least one computer storage media storing computer-executable instructions that, based on execution by a computing device, configure the computing device to perform actions comprising: exchanging information via a hardware control interface (“HCI”) between a hardware network adapter and a driver software module that corresponds to the hardware network adapter, where the hardware control interface is configured for operating with a variety of different hardware network adapters of different types, where the different hardware network adapters include the hardware network adapter, and where the hardware control interface is network adapter independent.

9. The at least one computer storage media of claim 8 where the hardware control interface is configured for supporting at least a portion of a wireless communication standard.

10. The at least one computer storage media of claim 8 where the hardware control interface comprises:
a transmission control interface;
a transmission status interface;
a reception control interface; or
a channel switching interface.

11. The at least one computer storage media of claim 8 where the driver software module comprises the hardware control interface.

12. The at least one computer storage media of claim 11 where the driver software module controls the hardware network adapter according to at least a portion of a wireless communication standard.

13. The at least one computer storage media of claim 12 where the wireless communication standard comprises at least one 802.11 standard.

14. The at least one computer storage media of claim 8 where the hardware control interface is implemented at least in part in software.

15. A computing device comprising:
at least one processor;
memory coupled to the at least one processor;
a hardware network adapter coupled to the at least one processor and the memory;
a hardware control interface (“HCI”) via which the computing device exchanges information between the hardware network adapter and a driver software module that corresponds to the hardware network adapter, where the hardware control interface is configured for operating with a variety of different hardware network adapters of different types, where the different hardware network adapters include the hardware network adapter, and where the hardware control interface is network adapter independent.

16. The computing device of claim 15 where the hardware control interface is configured for supporting at least a portion of a wireless communication standard.

17. The computing device of claim 15 where the hardware control interface comprises:
a transmission control interface;
a transmission status interface;
a reception control interface; or
a channel switching interface.

18. The computing device of claim 15 where the driver software module comprises the hardware control interface that is implemented at least in part in software.

19. The computing device of claim 18 where the driver software module controls the hardware network adapter according to at least a portion of a wireless communication standard.

20. The computing device of claim 19 where the wireless communication standard comprises at least one 802.11 standard.