SYSTEM AND METHOD FOR
CONCURRENT OPERATION OF A
WIRELESS DEVICE IN TWO DISJOINT
This invention relates generally to wireless network communications. In particular, the invention relates to the operation of a wireless node functioning at the same time as a 10 member of two disjoint wireless networks, such as an infrastructure network and an ad-hoc network.
BACKGROUND OF THE INVENTION
Devices conducting network communications over wire- 15 less links are becoming increasing popular. Wireless links typically transmit data over radio frequency channels but may operate over other carrier frequency ranges, such as infrared. Most radio frequency ("RF") based wireless networks are designed to operate in two basic modes: the 20 infrastructure mode and the peer-to-peer or ad hoc mode.
In the infrastructure ("IS") mode, which is also sometimes referred to as the managed network mode, each wireless network node communicates with the other nodes in the 25 network through an access point ("AP") node of the IS network. The packets directed by an IS node to another IS node carry the AP's Media Access Control ("MAC") address in the link layer header. The access point functions as a bridge, repeater, gateway, and firewall between wireless 3Q nodes and wired nodes of the network. The access point also apportions bandwidth of the communication channel to the wireless IS nodes to ensure the quality of the communications.
In the ad hoc ("AH") mode, a wireless node communi- 35 cates directly, i.e., in a peer-to-peer fashion, with other nodes within its RF range without going through an intermediate node such as the access point of the IS network. Ad hoc wireless network connections are useful when close-by users want to communicate with each other in places where no IS 40 network exists, or when they fail to be authorized by the access point of an existing IS network.
Conventionally, there is no interaction between nodes in an infrastructure network and nodes in an ad hoc network even if they have overlapping transmission ranges. There 45 are, however, many situations where the ability for a wireless device to operate in both the ad-hoc and infrastructure networks may be desirable. For instance, in one scenario, employees from company A conduct a business meeting at company B with an employee of company B. Company B 50 has an internal corporate network that supports an infrastructure wireless network. The visitors need to share electronic information such as documents, presentations, and data with their host. This can be done if the visitors can use their laptop computers to communicate wirelessly with the 55 laptop computer of company B. For security concerns, the visitors are not allowed access to company B's internal network. Thus, the laptop computers of the visitors cannot operate as nodes of company B's infrastructure network.
One solution is that the visitors' computers can form an ad 60 hoc wireless network with the host's computer. This solution requires the host's computer to operate as an ad hoc node. This, however, can pose a problem to the computer of the host, i.e., company B's employee, if he intends to have his computer connected wirelessly to the internal network of 65 company B so that he can retrieve data for sharing with the visitors. Traditionally, nodes operating in the IS mode can
not talk to any node operating in the AH mode, and vice versa. This is because the IS nodes talk through the AP while AH nodes talk directly among themselves, and the AP does not know about AH nodes. To function as a node of the ad hoc network, the host's computer has to disconnect and log off from the infrastructure network. This is done by an administrative program that manages the wireless configuration of the card on the computer by telling the wireless driver to disassociate from the AP and enter the ad hoc mode. When operating in the ad hoc mode, the host's computer will not be able to access the IS network. When it later wants to function as a node of the infrastructure network, it then has to exit the ad hoc network and reconnect to the infrastructure network.
SUMMARY OF THE INVENTION
In view of the foregoing, the invention provides a system and method for a wireless device to operate concurrently as a member of first and second wireless networks, such as an infrastructure ("IS") network and an ad hoc ("AH") network, that are separate and disjoint. In other words, the wireless device functions as a "dual-mode" node in the two wireless networks. The dual-mode node has a wireless controller driver inserted in its networking stack (e.g., the stack comprising the network and NDIS drivers) that exposes two virtual wireless network adapters, one for the first wireless network and one for the second wireless network. Each virtual wireless network adapter has an associated queue for queuing packets in the flow for the corresponding wireless network mode. The wireless controller driver controls the switching of the network mode, which may be triggered by signals transmitted by the first network, such as poll signals sent by an access point of an IS network. When the mode is switched from operating in the first network to operating in the second network, the first virtual network adapter is disabled and the second virtual network adapter is enabled, and the queued packets in the queue for the second virtual network adapter are transmitted over the second wireless network.
Additional features and advantages of the invention will be made apparent from the following detailed description of illustrative embodiments, which proceeds with reference to the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
While the appended claims set forth the features of the present invention with particularity, the invention, together with its objects and advantages, may be best understood from the following detailed description taken in conjunction with the accompanying drawings of which:
FIG. 1 is a block diagram generally illustrating an exemplary computer system on which the present invention may be implemented;
FIG. 2 is schematic diagram showing a dual-mode wireless device that participates concurrently in an infrastructure network and an ad hoc network;
FIG. 3 is a schematic diagram showing a wireless controller driver in a networking stack for enabling a dual-mode wireless device to switch its operation mode;
FIG. 4 is a schematic diagram showing an implementation of the wireless controller driver;
FIG. 5 is a schematic diagram showing an alternative implementation of the wireless controller driver; and
FIG. 6 is a schematic diagram showing the data structure of a poll signal used to cause mode switching of the dual-mode node.