The present invention relates to wireless communications, and in particular to establishing connections between wireless stations.
With the proliferation of wireless communication protocols, many wireless stations are in use in wireless networks. Such wireless stations can communicate over channels in infrastructure mode, ad hoc mode or other modes. In infrastructure mode, a wireless access point (AP) provides a coordination function by forwarding data and control messages for the wireless stations.
In ad hoc mode communication, an access point is not required. A pair of wireless stations directly establishes a connection without association to a coordinator. Establishing such a connection is achieved by signaling to reserve a data channel. Signaling includes communicating control messages, such as beacons, over a default control channel between the pair of stations.
Both in infrastructure mode and ad hoc mode communication, when connections between wireless stations need to be established in rapid succession, exchange of control message for reserving a data channel can cause a processing bottleneck and waste of bandwidth.
The present invention provides a method and a system for connection setup in wireless communication. One embodiment involves establishing a wireless connection by reserving a wireless data channel for data communication; upon completion of said data communication, maintaining a selected data channel reserved and indicating the data channel is unoccupied. While the data channel remains reserved and unoccupied, another wireless connection may be established for data communication on the data channel, by maintaining the data channel reserved and indicating that the data channel is occupied.
As such, said other connection can be established without expending time (or using channel bandwidth) in reserving the data channel again. This enables establishing rapid reconnection between wireless stations for successive data channel transmissions on the same reserved data channel.
These and other features, aspects and advantages of the present invention will become understood with reference to the following description, appended claims and accompanying figures.
The present invention provides a method and a system for connection setup in wireless communication. One embodiment involves establishing a connection by reserving a wireless data channel for data communication between a pair of wireless stations; upon completion of said data communication, maintaining a selected data channel reserved while indicating the data channel is unoccupied; and while the data channel remains reserved and unoccupied, establishing another connection for data communication by maintaining the data channel reserved and indicating that the data channel is occupied. As such, said other connection can be established without expending time (or using channel bandwidth) in reserving the data channel again. This enables establishing rapid reconnection between wireless stations for successive data channel transmissions on the same reserved data channel.
In one implementation, the data channel is reserved by an exchange of control messages between the stations on a control channel. As such, a wireless station has a first transceiver, such as a control channel transceiver, and a second transceiver, such as a data channel transceiver. The control channel transceiver is utilized for communication on a wireless control channel and the data channel transceiver is used for communication on a wireless data channel. The connection setup process involves using the control channel for communication of control information to facilitate reserving the data channel for establishing connections for data communication.
In one implementation, the control channel transceiver comprises a control communication module configured for communicating control information on the control channel, and the data channel transceiver comprises a data communication module configured for data communication on the data channel. The data channel can comprise a wireless in-band channel and the control channel can also comprise a wireless in-band channel.
Alternatively, the data channel can comprise a wireless in-band channel and the control channel can comprise a wireless out-of-band channel. An out-of-band channel is a first physical channel that is out-of-band relative to a second physical channel (i.e., an in-band channel). The out-of-band channel is at a frequency different from an in-band channel. For example, an in-band data transmission channel may operate on a 60 GHz frequency band, whereas, an out-of-band channel may operate on WLAN, Bluetooth, 5 GHz or 2.4 GHz (or even another 60 GHz) frequency band. An out-of-band frequency means a different frequency than an in-band frequency, even if both are in the same frequency band.
As those skilled in the art recognize, the present invention is equally applicable to a case when the data channel and the control channel are both in-band channels and to a case when the data channel is in-band and the control channel is out-of-band. In both cases, the connection setup process involves using the control channel for communication of control information to facilitate establishing a connection on the data channel. The latter case is described as an example of the present invention, wherein the control communication module comprises an out-of-band communication module configured for communicating control information on an out-of-band channel. Further, a data communication module comprises an in-band communication module configured for data communication on an in-band channel. The connection setup process involves using the out-of-band channel for communication of control information to facilitate establishing a connection on the in-band channel.
The present invention is applicable to high throughput wireless communications, such as ECMA standards on millimeter wave (mmWave) communication networks, and implementation of WirelessHD standard on uncompressed video trasmission. An example implementation for a 60 GHz frequency band wireless network is described below, useful with ECMA and WirelessHD (WiHD) applications. ECMA is an international organization providing ECMA-60 GHz wireless protocol. WirelessHD is an industry-led effort to define a wireless digital network interface specification for wireless HD digital signal transmission on the 60 GHz frequency band, e.g., for consumer electronics (CE) and other electronic products. An example WiHD network utilizes a 60 GHz-band mmWave technology to support a physical (PHY) layer data transmission rate of multi-Gbps (gigabits per second), and can be used for transmitting uncompressed high definition television (HDTV) signals wirelessly. The present invention is useful with other wireless communication systems as well.
A first wireless station having established and used a data channel connection (e.g., 60 GHz channel) for data communication (e.g., video) with a second wireless station, may wish to reestablish another connection with the second wireless station or a third wireless station using that same data channel. Generally, prior to starting a 60 GHz connection, control messages are exchanged between wireless stations for reserving a 60 GHz channel (the specific control message exchange depends on whether the first wireless station is operating in ad hoc or infrastructure mode). However, in scenarios where connections such as 60 GHz connections are established in rapid succession, such control message exchanges to reserve a 60 GHz channel can become quite a bottleneck and waste bandwidth. The present invention provides a connection setup process that allows establishing a rapid reconnection between stations for successive data channel transmissions on a reserved data channel, without expending time (or using channel bandwidth) in reserving the data channel again.
Such a control message C1 from a wireless station (e.g., station A) can have a source MAC address (SA) and a destination MAC address (DA) of the peer station (e.g., station B) with which the data transmission on the particular 60 GHz data channel recently occurred. Optionally, the destination address may be avoided or set to the broadcast address. The control message C1 further includes a Timer field indicating the time period the particular 60 GHz data channel is reserved for future use. Before the expiry of the Timer, the station A transmits another control message C1 to renew or extend the reservation period.
In the meantime, in one scenario, if the station A needs to start another 60 GHz connection with the station B, then the station A may change the control message type to C2 (i.e., transmit another control message type, C2, on the control channel) to indicate that said particular 60 GHz data channel is busy (i.e., occupied by data transmission), such that the station A can start a 60 GHz communication with the station B on that particular 60 GHz data channel, without expending time (or using channel bandwidth) in reserving the 60 GHz data channel again. This enables establishing rapid reconnection between stations for successive data channel transmissions. The control messages C1 and C2 can also be of the same type, but have differing field values that differentiate them.
In another scenario, while the station A is still transmitting control message C1, the station X may wish to start transmitting data to the station Y on a 60 GHz data channel. Upon receiving a control message C1, the station X transmits a control message C2 on the control channel indicating that the particular 60 GHz data channel (the same channel as used recently by stations A and B) is busy and reserved (i.e., occupied) for transmissions by the station X. Upon receiving such a control message C2, the station A ceases transmitting the control messages C1. The control message C2 can include the same type of information (e.g., Timer, SA, DA) as a control message C1.
When a data channel is indicated as busy (i.e., occupied) for a pair of stations, other stations wait until the data channel is indicated as not busy, before attempting to communicate on that data channel. Though in the example above the station A (sender) is indicated as transmitting the control message C1, in other examples, either the station A or the station B (receiver), or both, can transmit the control messages C1.
In steps 45-48, the third station may indeed be the first station itself wishing to communicate on the data channel again. In that case, steps 46 and 47 are unnecessary, wherein in step 45 the first station transmits a control message (e.g., C2) on the control channel indicating that the data channel is reserved and busy, and in step 48 the first station begins transmitting data on the data channel again.
Referring to the example process 60 in
The MAC layer 31 further include a communication module 31A which implements the connection setup processes described hereinabove (e.g.,
The LR PHY 32B and the HR PHY 33B can be in-band (e.g., both using 60 GHz) or out-of-band (e.g., HR PHY 33B is on 60 GHz and the LR PHY 32B is on WLAN, Bluetooth, 60 GHz, etc.). The HR PHY 33B includes multiple antennas 33C, and the LR PHY 32B can have one or multiple antennas 32C. In one example, the communication module 33 provides a MAC/PHY path for the data communication over an in-band channel, and the communication module 32 provides a MAC/PHY path for control message communication over an out-of-band channel. Specifically, the communication module 32 implements out-of-band communication for control transmission via an antenna 32C on an LR out-of-band channel 16. The communication module 33 implements an in-band communication for transmission of information (e.g., data, video, audio, etc.) via the antennas 33C on an HR in-band channel 18. The communication module 33 includes a HR MAC/PHY path for the in-band data channel 18 (e.g., a 60 GHz frequency band). The HR PHY layer 33B supports directional (or beamformed/steered) wireless communication on the in-band channel 18. The communication module 32 comprises a LR MAC/PHY path for the out-of-band channel 16 (e.g., Bluetooth, UWB or WLAN, or a different 60 GHz band as used in the HR path), and supports omni-directional wireless communication over the out-of-band channel 16.
In infrastructure mode, a wireless access point (AP) provides a coordination function by forwarding data and control messages for the wireless stations, enabling the wireless stations to establish connections with each other via communication links through the access point. A station can transmit an information request to the access point to obtain the information about other stations within a communication system such as a wireless network. Wireless stations can periodically receive control messages such as beacons from the access point, wherein the beacons indicate channel reservation and occupation information, allowing the stations to reserve a data channel based on such information. Further, a channel reservation scheme may be applied to a wireless channel (out-of-band channel and/or in-band channel) based on a superframe structure including superframes separated by beacons. In a contention-free period (CFP), time scheduling is utilized, wherein beacons provide information about scheduled channel time blocks. Reserving a channel includes reserving channel bandwidth for communication during a reserved period. For example, a bandwidth reservation scheme is applied based on the superframe structure, wherein beacons divide the channel time into multiple superframes. In each superframe there are contention periods and CFPs. In each CFP there are one or more schedules, wherein each schedule includes one or more reserved channel time blocks reserved for a requested transmission. The schedules represent reserved channel time block periods, and the time periods between the schedules are unreserved channel time blocks. The length of each reserved channel time block is defined in a schedule for a pair of stations. In one example, a beacon can include bandwidth allocation information elements (IE), indicating channel occupation information (e.g., certain duration of a channel time block is reserved for communication).
As is known to those skilled in the art, the aforementioned example architectures described above, according to the present invention, can be implemented in many ways, such as program instructions for execution by a processor, as logic circuits, as an application specific integrated circuit, as firmware, etc. The present invention has been described in considerable detail with reference to certain preferred versions thereof; however, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.
This application claims priority from U.S. Provisional Patent Application Ser. No. 60/881,444 filed on Jan. 19, 2007, incorporated herein by reference.
Number | Date | Country | |
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60881444 | Jan 2007 | US |