HK1137581B - A serial clear to send to self messaging procedure - Google Patents

Description

Continuous self-clearing messaging procedure

Technical Field

The present invention relates to communication networks, and more particularly, to a continuous (serial) clear to send (CTS-to-Self or CTS2Self) messaging procedure (procedure).

Background

IEEE802.11 describes a communication architecture that enables computing devices to communicate via a Wireless Local Area Network (WLAN). A Basic Service Set (BSS) is one of the building blocks of a WLAN. A BSS may include a plurality of computing devices or Stations (STAs) that may communicate wirelessly via one or more RF channels within a coverage area. The range of the coverage area may be determined based on a communication distance between the source STA and the destination STA at which data transmitted by the source STA via the RF channel may be received by the destination STA.

An independent BSS (ibss) refers to a BSS that includes a group of STAs with which each STA can communicate within the coverage area of the BSS. In an IBSS, each STA may communicate directly with any other STA in the IBSS, each STA being in the coverage area of the other STAs. An IBSS may be referred to as a point-to-point (ad hoc) network.

The infrastructure BSS involves a BSS, possibly in combination with an Extended Service Set (ESS). The ESS is identified by a Service Set Identifier (SSID). The infrastructure BSS facility may also be referred to as BSS. Each BSS in the ESS is identified by a BSS identifier (BSSID). Thus, STAs in a BSS typically determine their association in the BSS based on the BSSID and SSID.

Each BSS includes a plurality of STAs and an AP. The AP establishes an association with each STA in the BSS. The AP identifies each association using an Association Identifier (AID). The AP may provide communication services to the STAs in the BSS based on the established association.

STAs in the BSS or IBSS may negotiate operating parameters with which the STAs may communicate with other STAs in the BSS or IBSS. These operating parameters may include determining the bandwidth of the RF channel used between STAs participating in the communication. The RF channel bandwidth for communication between STAs may be 20MHz or 40 MHz. The operating parameters may also include the assignment of RF channels for communication between STAs in a given BSS or IBSS. As specified in the applicable IEEE802.11 specification, the various RF channels may have different frequency ranges. The 20MHz RF channel may comprise a single 20MHz channel. The 40MHz RF channels may include a 20MHz first channel and a 20MHz second channel.

These operating parameters may also include specifications of the modulation scheme used by the STA to transmit data via the assigned RF channel. For example, STAs communicating based on the IEEE802.11 g specification may use a Complementary Code Keying (CCK) modulation scheme when transmitting data via an RF channel, whereas STAs communicating based on the IEEE802.11 n specification may use an Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme when transmitting data via an RF channel.

STAs employing the IEEE802.11 specification may use a carrier sense multiple access/collision avoidance (CSMA/CA) method to gain access to the wireless medium. In the coverage area of RF transmissions, collisions may occur in the wireless communication medium when multiple STAs concurrently use overlapping RF channels in an attempt to transmit data. RF channels overlap when at least one frequency is shared among two or more concurrently overlapping RF channels. Collisions may cause a failure to transmit data via the wireless communication medium, thereby causing the data transmission rate at which the STA transmits data to decrease. A STA using the CSMA/CA mechanism may transmit a Request To Send (RTS) frame to initiate an attempt to access the wireless medium. The RTS frame may indicate the source STA that transmitted the RTS frame and indicate the destination STA that intends to receive the RTS frame. The RTS frame may be transmitted via an RF channel allocated for communication between the source STA and the destination STA. When the source STA and the destination STA communicate via a 40MHz RF channel, an RTS frame may be transmitted via the first channel.

An RTS frame transmitted by a source STA may be received by any STA in the RF coverage area of an RF signal transmitted by the source STA. The RTS frame transmitted via the first channel may be received by STAs in the RF coverage area that are configured to receive signals transmitted via one or more frequencies within the first channel bandwidth. The STAs that receive the RTS frame may respond by refraining from attempting to transmit signals via the primary channel for a predetermined period of time (e.g., as specified in the RTS frame), thereby reducing the likelihood of collisions occurring when the originating STA is transmitting data via the primary channel.

The destination STA responds to the received RTS frame by sending a Clear To Send (CTS) frame. The CTS frame may indicate the originating STA, which the destination STA recognizes in the received RTS frame. The CTS frame may be transmitted via an RF channel allocated for communication between the source STA and the destination STA. When the source STA and the destination STA communicate via 40MHz, the CTS frame may be transmitted via the primary channel. Upon receiving the CTS frame, the originating STA may determine that access to the wireless medium has been obtained.

Once the STA gains access to the wireless medium, e.g., following an RTS/CTS frame exchange, the STA may begin transmitting data via the assigned RF channel using the well-defined modulation scheme. In the case where the source STA and the destination STA communicate via a 40MHz RF channel, data may be transmitted via the primary channel and/or the secondary channel.

Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.

Disclosure of Invention

A clear to send to Self (CTS-to-Self or CTS2Self) messaging procedure, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims.

Various advantages, aspects and novel features of the invention, as well as details of an illustrated embodiment thereof, will be more fully described in the following description and drawings.

Drawings

FIG.1 is a block diagram of an exemplary wireless data communication system that may be used in embodiments of the present invention;

FIG.2 is a block diagram of an exemplary transceiver system that may be used in embodiments of the present invention;

FIG.3 is a diagram of an exemplary continuous clear to self messaging procedure, according to an embodiment of the present invention;

fig.4 is a diagram illustrating an exemplary serial clear to send to self messaging procedure for transmitting data frames over a first channel in accordance with an embodiment of the present invention;

FIG.5 is a diagram illustrating an exemplary sequential clear to send to self messaging procedure in which data frames are transmitted via a first channel and a second channel delay in accordance with an embodiment of the present invention;

FIG.6 is a diagram of an exemplary sequential clear to self messaging procedure with cancellation of first channel access, in accordance with an embodiment of the present invention;

fig.7 is a flowchart illustrating steps of an exemplary serial clear to self messaging procedure, in accordance with an embodiment of the present invention.

Detailed Description

The present invention relates to a continuous clear to send to SELF (CTS2SELF) messaging procedure (procedure). In one embodiment, a source wireless Station (STA) using a 40MHz RF channel gains access to a wireless communication medium by attempting to transmit a Clear To Send (CTS) frame via a primary channel and a CTS frame via a secondary channel. The CTS frame may be sent in a continuous (serial) manner. For example, the source STA may send a CTS frame via the primary channel and transmit the CTS frame via a secondary primary channel at a subsequent time instant. Each CTS frame transmitted via the primary channel and the secondary channel contains an address identifying the originating STA. In this aspect of the invention, each CTS frame represents a CTS2SELF message.

The CST frames transmitted by the source STA via the primary channel and the secondary channel may be received by all STAs within the coverage area of the source STA's transmitted RF signals. The CTS frame transmitted via the primary channel may be received by STAs within the RF coverage area that are configured to receive transmitted signals via one or more frequencies within the primary channel bandwidth. The CTS frame transmitted via the secondary channel may be received by STAs within the RF coverage area that are configured to receive transmitted signals via one or more frequencies within the secondary channel bandwidth. An STA receiving a CTS frame via the primary channel may respond by refraining from attempting to transmit signals via the primary channel for a predetermined period of time, thereby reducing the likelihood of collisions occurring with the primary channel portion of the 40MHz channel when the originating STA is transmitting data via the primary channel. The STAs that receive the CTS frame via the secondary channel may respond by refraining from attempting to transmit signals via the secondary channel for a predetermined period of time, thereby reducing the likelihood of collisions occurring with the secondary channel portion of the 40MHz channel when the originating STA is transmitting data via the secondary channel.

Fig.1 is a block diagram of an exemplary wireless data communication system that may be used in embodiments of the present invention. Referring to fig.1, BSS _ 1112, BSS _ 2114 and Distribution System (DS)104 are illustrated. The BSS _ 1112 includes the AP _ 1122, the WLAN station STA _ a 124, and the STA _ B126. BSS _ 2114 includes AP _ 2132, STA _ X134, and STA _ Y136.

In BSS _ 1112, AP _ 1122 may communicate with STA _ a 124 via a 20MHz RF channel 144. The AP _ 1122 may communicate with the STA _ B126 via a 40MHz RF channel 146. The AP _ 1122 may negotiate with the STA _ a 124 to establish an RF channel allocation and RF channel bandwidth based on, for example, the transmitted beacon frame. The RF channel assignment may include a center frequency that may be used to determine the frequency range used by the RF channel 144 in the 20MHz RF channel bandwidth. The AP _ 1122 may negotiate with the STA _ B126 to establish an RF channel allocation and RF channel bandwidth based on, for example, the transmitted beacon frame. The 40MHz RF channels 146 include a first channel and a second channel. The first channel may include a range of frequencies used by the RF channel 144. The second channel may comprise an adjacent 20MHz frequency bandwidth. The second channel may include a second channel center frequency that may be used in a second channel bandwidth of 20MHz to determine a frequency range used by the second channel.

In BSS _ 2114, AP _ 2132 may communicate with STA _ X134 via a 20MHz RF channel 154. AP _ 2132 may communicate with STA _ Y136 via a 20MHz RF channel 156. AP _ 2132 may negotiate with STA _ X134 to establish an RF channel allocation and RF channel bandwidth based on, for example, the transmitted beacon frame. The RF channel assignment may include a center frequency that may be used to determine the frequency range used by the RF channel 154 in the 20MHz RF channel bandwidth. AP _ 2132 may negotiate with STA _ Y136 to establish an RF channel allocation and RF channel bandwidth based on, for example, the transmitted beacon frame. The 20MHz RF channels 156 may include the frequency range used by the RF channels 154.

DS 104 may provide an architecture that enables any one STA within BSS 1112 to communicate with any one STA in BSS 2114 and vice versa. DS 104 may use wireless communication (e.g., via one or more RF channels), wired communication (e.g., via copper or optical cables), or a combination of wireless and wired communication. STAs within BSS _ 1112 may transmit/receive data to/from the DS 104 via the AP _ 1122. The AP _ 1122 can transmit/receive data to/from the DS 104 via the interface 162. STAs within BSS _ 2114 may transmit/receive data to/from the DS 104 via AP _ 2132. AP _ 2132 may transmit/receive data to/from DS 104 via interface 164.

STS B126 attempts to access the wireless communication medium to reduce the likelihood of collisions during data transmission. The STA B126 may first attempt to receive signals via a wireless communication medium including one or more frequencies in the RF channel 146 of the 40MHz bandwidth to determine whether other STAs (that are transmitting RF signals in the coverage area including the STA B126) are transmitting signals using one or more frequencies in the RF channel 146 bandwidth.

In some conventional WLAN systems, e.g., using CSMA/CA, the STA B126 may transmit an RTS frame via the first channel portion of the RF channel 146. The RTS frame may indicate that STA _ a 124 is the source STA and AP _ 1122 is the destination STA. Other STAs within the AP _ 1122, BSS _ 1112 that are within the coverage area of the RF signal transmitted by the STA _ B126 may receive the RTS frame transmitted by the STA _ B126 via the primary channel portion of the RF channel 146. In response to the RTS frame, AP _ 1122 transmits a CTS frame. The CTS frame may indicate that STA B126 is the destination STA of the CTS frame.

In addition, the STA _ X134 and/or STA _ Y136 and AP _ 2132 in BSS _ 2114 that are within the coverage area of the RF signals transmitted by the STA _ B126 may receive the RTS frame transmitted by the STA _ B126 when configured to receive signals via one or more frequencies contained in the primary channel portion of the RF channel 146.

One potential drawback to the conventional CSMA/CA approach is that when the STAs and/or APs in BSS 2114 are configured to receive signals via one or more frequencies contained within the second channel portion of the RF channel 146, the STA _ X134 and/or STA _ Y136 and/or AP _ 2132 within BSS 2114 may not receive RTS frames transmitted by STA _ B126 via the first channel portion of the RF channel 146.

The STA _ B126 may communicate with the STA _ a 124 by transmitting data frames to the AP _ 1122 via the 40MHz RF channel 146. The data frame may be transmitted via the first channel portion and/or the second channel portion of the RF channel 146 using an OFDM modulation scheme. However, when the STA _ X134 and/or STA _ Y136 and/or AP _ 2132 within the BSS _ 2114 is configured to receive signals via one or more frequencies contained within the second channel portion of the RF channel 146, the STA _ X134 and/or STA _ Y136 and/or AP _ 2132 may also be configured to use CCK modulation when receiving the transmitted data signals and may not detect signals and/or data frames modulated using OFDM transmitted by the STA _ B126 via the second channel portion of the RF channel 146. Alternatively, the STA _ X134 and/or STA _ Y136 and/or AP _ 2132 within the BSS _ 2114 may attempt to detect the presence of signal energy within the wireless communication medium, but may employ a signal detection threshold level that may not detect the transmission of a signal by the STA _ B126. Thus, any of the STA _ X134 and/or STA _ Y136 and/or AP _ 2132 within the BSS _ 2114 may erroneously determine that a frequency within the RF channel bandwidth 154 and/or 156 is not currently being used to transmit signals and/or data frames.

Upon receiving the CTS frame from the AP _ 1122, the STA _ B126 may begin transmitting one or more data frames via the 40MHz RF channel 146. The data frame transmitted by the STA B126 may indicate that the AP _ 1122 is the recipient. The STA B126 may transmit data frames using OFDM modulation. Signals transmitted by the STA B126 may propagate into a coverage area that includes at least a portion of BSS 1112 and at least a portion of BSS 2114. The BSS 2114 portion includes at least one or more of the location of STA X134 and/or STA Y136 and/or AP 2132. During the transmission of a data frame by the STA _ B126 to the AP _ 1122, either the STA _ X134 or the AP _ 2132 within the BSS _ 2114 (e.g., both of which are in the coverage area of the STA _ B126 transmitting signal) may begin transmitting data frames. The STA _ X134 may transmit data frames to the AP _ 2132 via the RF channel 154 using the CCK modulation scheme. The RF channel 154 may include at least a portion of the frequencies within the second channel frequency band of the RF channel 146. Signals transmitted by the STA X134 may propagate into a coverage area that includes at least a portion of BSS 2114 and at least a portion of BSS 1112. The BSS _ 1112 portion may include at least the location of the STA _ B126 and/or the AP _ 1122.

Signals transmitted simultaneously via the 40MHz RF channel 146 and the 20MHz RF channel 154 within the common coverage area will cause collisions in the wireless communication medium. As a result of the collision, the AP _ 1122 may receive signals from the STA _ B126 via the RF channel 146 at frequencies within the primary channel portion and from both the STA _ B126 and the STA _ X134 via the secondary channel portion of the RF channel 146 at frequencies.

The reception of signals at frequencies within the secondary channel portion of the RF channel 146 by the AP _ 1122 from both the STA _ B126 and the STA _ X134 will degrade the data received by the AP _ 1122 via the secondary channel. The data to be sent to the AP _ 1122 may include data contained in a data frame transmitted by the STA _ B126. As a result of the collision, AP _ 1122 may detect errors in the received data and/or may not detect properly composed data frames at all. This will result in data loss, resulting in the STA B126 retransmitting the data. Which in turn results in reduced throughput of data communications between the STA _ B126 and the AP _ 1122. Accordingly, the data throughput of data communication between the STA _ X134 and the AP _ 2132 is reduced.

In an embodiment of the present invention, the STA B126 may attempt to access the wireless communication medium via the 40MHz RF channel 146 using a continuous CTS2SELF messaging procedure to enable transmission of data frames. The STA B126 may transmit the CTS frame via the primary channel portion of the RF channel 146. The CTS frame may contain an address identifying the STA B126. The CTS frame sent via the primary channel of the RF channel 146 may inform STAs and/or SPs (including AP _ 1122) within the coverage area of the STA _ B126: the STA B126 is preparing to transmit signals via the wireless communication medium using at least a portion of the frequencies within the first channel bandwidth. The STA and/or AP refrains from transmitting signals via frequencies encompassed by at least the primary channel portion of the RF channel 146 in response to the received CTS frame. The STAs and/or APs that receive data frames transmitted via at least the primary channel portion of the RF channel 146 from the STA B126 (the data frames including an address identifying the individual recipient to be addressed) may, in response, transmit signals and/or data via frequencies included in at least the primary channel portion of the RF channel 146.

Subsequently, the STA B126 transmits a CTS frame via the secondary channel of the RF channel 146. The CTS frame may contain an address identifying the STA B126. The transmitted CTS frame may inform the STAs and/or SPs within the coverage area of the STA B126 that the STA B126 is preparing to transmit signals via the wireless communication medium using at least a portion of the frequencies within the secondary channel bandwidth. The STA and/or AP refrains from transmitting signals on frequencies encompassed by the secondary channel portion of the RF channel 146 in response to the received CTS frame. The STAs and/or APs receiving data frames transmitted via at least the secondary channel portion of the RF channel 146 from the STA B126 (the data frames including an address identifying the individual recipient to be addressed) may, in response, transmit signals and/or data via frequencies included in the at least the secondary channel portion of the RF channel 146.

As a result of the CTS2SELF procedure, other STAs and APs in the BSS _ 1112 that are in the coverage area of the STA _ B126 to transmit signals may refrain from transmitting signals on the frequency included in the primary channel portion of the RF channel 146 and may refrain from transmitting signals on the frequency included in the secondary channel portion of the RF channel 146. Similarly, STAs and APs in the coverage area of the BSS 2114 where the STA B126 transmits signals may refrain from transmitting signals on the frequency included in the first channel portion of the RF channel 146 or refrain from transmitting signals on the frequency included in the second channel portion of the RF channel 146. This reduces the likelihood of collisions during the transmission of data frames by the STA B126.

Fig.2 is a block diagram of an exemplary transceiver system that may be used in embodiments of the present invention. WLANSTA and/or AP include a transceiver system and the transceivers used in various embodiments of the invention are not limited to the exemplary transceiver shown in fig. 2. Referring to fig.2, there is shown a transceiver system 200, a receive antenna 222 and a transmit antenna 232. The transceiver system 200 may include at least a receiver 202, a transmitter 204, a processor 206, and a memory 208. Although a transceiver system is shown in fig.2, the transmit and receive functions may be implemented separately.

The processor 206 may comprise suitable logic, circuitry, and/or code that may enable digital receiver and/or transmitter functionality in accordance with one embodiment of the present invention in accordance with applicable communication standards. The processor 206 may also perform various processing tasks on the received data. These processing tasks may include computing channel estimates (used to characterize the wireless communication medium), delineating frame boundaries of received data, and computing frame error rate statistics (used to indicate the detection or non-detection of errors within a received frame). The processor 206 may also be used to confirm the method of processing the received signal. The signal processing method may include one or more RF channels receiving a signal and/or confirming a modulation method of detecting a data frame received via a selected RF channel.

The receiver 202 may comprise suitable logic, circuitry, and/or code that may enable receiver functionality, including but not limited to: amplifying the received signal, generating a frequency carrier signal corresponding to the selected RF channel, down-converting the amplified RF signal by the generated frequency carrier signal, demodulating data contained in the data symbols based on the application of the selected modulation type, detecting the data contained in the demodulated signal. The RF signal may be received via a receive antenna 222. Data received via the RF signal may be communicated to the processor 206.

The transmitter 204 may comprise suitable logic, circuitry, and/or code that may enable transmitter functions including, but not limited to: the method includes modulating received data based on applying a selected modulation type to generate data symbols, generating a frequency carrier signal corresponding to a selected RF channel, upconverting the data symbols with the generated frequency carrier signal, and generating and amplifying an RF signal. Data may be received from processor 206 and/or memory 208. The RF signal may be transmitted via a transmit antenna 232.

The memory 208 may comprise suitable logic, circuitry, and/or code that may enable storage and/or retrieval of data and/or code. Memory 208 may employ any of a variety of storage media technologies, such as volatile memory, e.g., Random Access Memory (RAM); non-volatile memory, such as electrically erasable programmable read-only memory (EEPROM). In an application of the present invention, the memory 208 can store code for a continuous CTS2SELF message process.

In operation, the processor 206 enables the STA _ B126 to attempt to access the 40MHz RF channel 146. The processor 206 enables the generation of a CTS frame that is transmitted via the primary channel portion of the RF channel 146. The CTS frame may contain an address identifying the STA B126. The processor 206 may transmit the CTS frame to the transmitter 204. The processor 206 may configure the transmitter 204 to transmit the CTS frame via the primary channel portion of the RF channel 146. The processor 206 may configure the transmitter 204 to employ a modulation method, such as CCK modulation, when transmitting the CTS frame via the primary channel portion of the RF channel 146.

The processor 206 enables subsequent generation of a CTS frame transmitted via the secondary channel portion of the RF channel 146. The CTS frame may contain an address identifying the STA B126. The processor 206 may transmit the CTS frame to the transmitter 204. The processor 206 may configure the transmitter 204 to transmit the CTS frame via the secondary channel portion of the RF channel 146. The processor 206 may configure the transmitter 204 to employ a modulation method, such as CCK modulation, when transmitting the CTS frame via the secondary channel portion of the RF channel 146.

The processor 206 enables subsequent determination that access to the wireless communication medium has been obtained, thereby enabling a reduction in the likelihood of data collisions during transmission of data frames via the RF channel 146.

The processor 206 enables generation of a subsequent data frame that may be sent to the transmitter 204 and transmitted via the first channel portion and/or the second channel portion of the RF channel 146. The processor 206 may configure the transmitter 204 to use a modulation method, such as OFDM, when transmitting subsequent data frames via the first channel portion and/or the second channel portion of the RF channel 146.

Fig.3 is a diagram illustrating an exemplary continuous clear to self messaging process, in accordance with an embodiment of the present invention. Fig.3 illustrates an exemplary continuous CTS2SELF messaging procedure in which the STA B126 may transmit data frames using both the primary channel portion of the RF channel 146 and the secondary channel portion of the RF channel 146. In one embodiment of the invention, the RF channel 146 comprises a 40MHz bandwidth, and the first channel and the second channel each comprise a 20MHz bandwidth.

Referring to fig.3, the STA B126 may attempt to access the wireless communication medium by transmitting a CTS frame 302a via the primary channel. Prior to transmitting the CTS frame, the STA B126 may perform a Clear Channel Assessment (CCA) to determine whether other STAs and/or APs are transmitting signals and/or data via one or more frequencies included within the primary channel bandwidth. The CCA is performed by configuring the STA B126 to receive signals and/or data via any frequency contained within the first channel bandwidth. The STA B126 may alternatively attempt to detect signal energy and/or data during the CCA interval.

After transmitting the CTS frame 302a, at time t₀The STA B126 may initiate a CCA to determine whether other STAs and/or APs are transmitting signals and/or data via one or more frequencies included within the second channel bandwidth. If the STA _ B126 does not detect signals and/or data at a subsequent time, t, the STA _ B126 will detect the signal and/or data at the subsequent time t₁The CCA is ended. In various embodiments of the present invention, from time t₀From the start to time t₁The end time indicates a time interval, i.e., a time interval indicating a coordination function inter-frame transmission interval (PIFS). An exemplary PIFS time interval is specified by the applicable IEEE802.11 specification.

STA _ B126 at time t₁Or at time t₁Thereafter, the CTS frame 302b is transmitted via the secondary channel. The time interval after transmission of the CTS frame 302b may begin at time t₂. At this point, the STA B126 may begin preparing to transmit data frames via the primary channel and/or the secondary channel portion of the RF channel 146. The STA _ B126 may be at a later timet₃Transmission of the data frame begins. In various embodiments of the present invention, from time t₂From the start to time t₃The time period ends indicating a time interval, i.e., a time interval indicating an inter frame transmission Interval (IFS). In an exemplary embodiment of the invention, the IFS comprises a short IFS (sifs) time interval. An exemplary SIFS may be specified by an applicable IEEE802.11 specification. Time t₃The STA B126 may then begin transmitting data frames 304 via the first and/or second channel portions of the RF channel 146.

The CTS frames 302a and/or 302B indicate a time period corresponding to a length of time for which the STA B126 requests reservation during which the STA B126 transmits a data frame 304 via the primary channel and/or the secondary channel using the wireless medium. In the example of fig.3, the time period requested for the first channel is at time t₄And (6) ending. Likewise, the time period requested for the second channel is at time t₄And (6) ending. The STA and/or AP receiving the CTS frame 302a via the primary channel refrains from attempting to transmit signals and/or data using any frequency contained within the primary channel bandwidth in compliance with the CTS frame period request until time t₄At a later time. Likewise, the STA and/or AP receiving the CTS frame 302b via the secondary channel refrains from attempting to transmit signals and/or data using any of the frequencies contained within the secondary channel bandwidth in compliance with the CTS frame time period request until time t₄At a later time.

Fig.4 is a diagram illustrating an exemplary serial clear to send to self messaging procedure for transmitting data frames over a first channel in accordance with an embodiment of the present invention. Fig.4 illustrates an exemplary CTS2SELF messaging procedure in which the STA B126 may use the primary channel portion of the RF channel 146 to transmit data frames while the secondary channel portion of the RF channel 146 may not be used to transmit data frames. When signals and/or data are detected via the secondary channel portion of the RF channel 146, immediately following the transmission of the CTS via the primary channel, the STA IB 126 refrains from transmitting a CTS on the secondary channel and, instead, begins transmitting data frames via the primary channel portion of the RF channel 146. In an exemplary embodiment of the invention, the RF channel 146 comprises a 40MHz bandwidth, and the first channel and the second channel each comprise a 20MHz bandwidth.

Referring to fig.4, the STA B126 may attempt to access the wireless communication medium by transmitting a CTS frame 402 via the primary channel. After transmitting the CTS frame 402, at time t₀The STA B126 may initiate a CCA to determine whether other STAs and/or APs are transmitting signals and/or data via one or more frequencies included in the second channel bandwidth. In the example of fig.4, the STA B126 detects channel activity 404 in the second channel. The detected channel activity 404 may include signals and/or data frames that may be received by the STA B126 via one or more frequencies encompassed by the second channel bandwidth. At a subsequent time t₁The STA _ B126 ends the CCA. In various embodiments of the present invention, from time t₀From the start to time t₁Ending the time indication interval indicates the PIFS time interval. At time t₁Thereafter, the STA B126 begins transmitting data frames 406 via the primary channel portion of the RF channel 146.

The CTS frame 402 indicates a time period corresponding to a length of time for which the STA B126 requests reservation during which the STA B126 transmits data frames via the primary channel using the wireless medium. In the example of fig.4, the time period requested for the first channel is at time t₃And (6) ending.

Fig.5 is a diagram illustrating an exemplary sequential self-clearing sent message process for delaying transmission of data frames via a first channel and a second channel in accordance with an embodiment of the present invention. Fig.5 illustrates an exemplary CTS2SELF messaging procedure in which the STA B126 may use the primary channel portion of the RF channel 146 to transmit data frames, but may not use the secondary channel portion of the RF channel 146 to transmit data frames. When signals and/or data are detected via the secondary channel portion of the RF channel 146, the STA B126 waits until the secondary channel becomes available and then begins transmitting a second CTS-to-self frame via the secondary channel and then transmits data frames via the primary and secondary channel portions of the RF channel 146. In one embodiment of the invention, the RF channel 146 comprises a 40MHz bandwidth, and the first channel and the second channel each comprise a 20MHz bandwidth.

See alsoFig.5, the STA B126 may attempt to access the wireless communication medium by transmitting a CTS frame 502a via the primary channel. After transmitting the CTS frame 502a, at time t₀The STA B126 may initiate a CCA to determine whether other STAs and/or APs are transmitting signals and/or data via one or more frequencies included in the second channel bandwidth. In the example of fig.5, the STA B126 detects channel activity 504 in the second channel. The STA B126 delays attempting to transmit data frames via the secondary channel portion of the RF channel 146 waiting until the secondary channel portion of the RF channel 146 becomes available. The detected channel activity 504 at a subsequent time t₁And (6) ending. The STA B126 continues CCA for the second channel portion of the RF channel 146 until a subsequent time t₂. In various embodiments of the present invention, from time t₁From the start to time t₂The end time is designated as the time interval specified by the PIFS time interval.

At time t₂Or thereafter, the STA B126 begins transmitting the CTS frame 502B via the secondary channel portion of the RF channel 146. The period of time following the CTS frame 502b begins at time t₃. At this point, the STA B126 may begin preparing to transmit data frames via the primary channel and/or the secondary channel portion of the RF channel 146. At a subsequent time t₄The STA B126 starts transmitting data frames. In various embodiments of the present invention, from time t₃From the start to time t₄The end time is designated as the time interval specified by the IFS time interval. In an exemplary embodiment of the present invention, the IFS includes SIFS time intervals. At time t₄Thereafter, the STA B126 begins transmitting data frames 506 via the primary channel and/or the secondary channel portion of the RF channel 146.

The CTS frame 502a indicates a period of time corresponding to a length of time for which the STA B126 requests reservation during which the STA B126 transmits data frames via the primary channel using the wireless medium. In the example of fig.5, the time period requested for the first channel is at time t₅And (6) ending. The CTS frame 502B indicates a period of time corresponding to a length of time that the STA B126 requests a reservation during which the STA B126 uses the wireless medium via the secondary channelThe data frame is transmitted. In the example of fig.5, the time period requested for the second channel is at time t₅And (6) ending. In various embodiments of the invention, the time period requested for the second channel may be specified to end at about the same time as the time period requested for the first channel.

Fig.6 is a diagram illustrating an exemplary sequential clear to self messaging procedure for revoking first channel access, in accordance with an embodiment of the present invention.

Fig.6 illustrates an exemplary CTS2SELF messaging procedure in which the STA B126 may use the primary channel portion of the RF channel 146 to transmit data frames, but may not use the secondary channel portion of the RF channel 146 to transmit data frames. When signals and/or data are detected via the second channel portion of the RF channel 146, the STA B126 may cancel access to the wireless medium using the first channel portion of the RF channel 146. The STA B126 may attempt to access the wireless medium at a later time. In an exemplary embodiment of the invention, the RF channel 146 comprises a 40MHz bandwidth, and the first channel and the second channel each comprise a 20MHz bandwidth.

Referring to fig.6, the STA B126 may attempt to access the wireless communication medium by transmitting a CTS frame 602 via the primary channel. After transmitting the CTS frame 602, at time t₀The STA B126 may initiate a CCA to determine whether other STAs and/or APs are transmitting signals and/or data via one or more frequencies included in the second channel bandwidth. In the example of fig.6, the STA B126 detects 604 channel activity in the second channel. The STA B126 delays attempting to transmit data frames via the secondary channel portion of the RF channel 146 waiting until the secondary channel portion of the RF channel 146 becomes available. In addition, the STA B126 relinquishes access to the wireless communication medium for transmitting data via the primary channel portion of the RF channel 146 that was obtained in response to transmitting the CTS frame 602. STA _ B126 at subsequent time t₁The CCA is ended. In various embodiments of the present invention, from time t₀From the start to time t₁The end time is designated as the time interval specified by the IFS time interval.

After the CCA for the second channel is complete, the STA B126 relinquishes the first channel by transmitting a contention free End (CF-End) frame 606 via the first channel. The recipient of the CF-End frame 606 may inform the receiving STA _ a 124 that the STA _ B126 (which may have previously gained access to the wireless communication medium to transmit signals via the primary channel) is relinquishing previously gained access. Upon receiving the CF-End frame 606, the receiving STA may attempt to access the wireless medium to transmit signals via one or more frequencies contained within the primary channel portion of the RF channel 146. The STA B126 may then attempt to gain access to the wireless communication medium to transmit signals via the primary channel and/or the secondary channel portion of the RF channel 146.

Fig.7 is a flowchart illustrating steps of an exemplary process for continuous clear to self messaging, in accordance with an embodiment of the present invention. Referring to fig.7, at step 702, the STA B126 performs a CCA on the primary channel portion of the RF channel 146. At step 704, the STA B126 determines whether a usable or clear (clear) wireless communication medium is available for transmitting data frames via frequencies contained in the primary channel portion of the RF channel 146. In the event that the first channel is confirmed as unclean in step 704, the STA B126 returns to step 702 to continue CCA for the first channel.

In the event that the primary channel is confirmed to be clean in step 704, the STA B126 transmits a CTS frame via the primary channel in step 708. At step 710, the STA B126 performs a CCA on the second channel portion of the RF channel 146. At step 712, the STA B126 may confirm whether the second channel is clean. When it is confirmed that the secondary channel is clean in step 712, the STA B126 may transmit a CTS frame via the secondary channel in step 714. At step 716, the STA B126 begins transmitting data frames via the primary channel and/or the secondary channel.

When it is confirmed in step 712 that the second channel is not clean, the STA B126 may confirm whether to transmit the data frame only via the first channel in step 718. When the STA B126 acknowledges transmitting the data frame via the primary channel only in step 718, the STA B126 transmits the data frame via the primary channel in step 720.

When the STA B126 confirms that the data frame is not transmitted only via the primary channel in step 718, the STA B126 confirms whether the secondary channel is waiting to become clear before transmitting the data frame in step 722. When the STA B126 confirms that the second channel is not to be cleared in step 722, the STA B126 transmits a CF-End frame to relinquish the first channel in step 724. At a subsequent time, the STA B126 repeats the process from step 702.

When STA B acknowledges to wait for the second channel to become available in step 722, it returns to step 710 where STA B continues to perform CCA on the second channel.

The invention provides a continuous self-clearing messaging procedure. The system of the present invention includes a wireless local area network Station (STA)126 that enables transmission of a channel reservation confirmation message, such as a CTS frame, via a reference RF channel, such as a primary channel. The STA126 may enable transmission of one or more subsequent channel reservation confirmation messages, e.g., CTS frames, via a corresponding one or more subsequent (subsequent) RF channels, e.g., a secondary channel. The STA126 may enable transmission of data frames via at least a portion of the reference RF channel and/or the corresponding one or more subsequent RF channels. In various embodiments of the present invention, the one or more subsequent RF channels may comprise a second channel. Various embodiments of the present invention enable the STA126 to transmit data frames via the primary channel, the secondary channel, the tertiary channel, etc.

The STA126 may enable assessment of the reference RF channel, e.g., CCA, prior to transmitting the channel reservation confirmation message via the reference RF channel. The evaluation may include attempting to detect a signal or receive data via a reference RF channel. Transmitting the channel reservation confirmation message may be based on the evaluation. After transmitting the channel reservation confirmation message via the reference RF channel, the STA126 enables each of the corresponding one or more subsequent RF channels to be continuously evaluated. The STA126 evaluates a current one of the corresponding one or more subsequent RF channels before evaluating the next channel. Based on the continuous evaluation, a portion of one or more subsequent RF channels may be selected for transmitting the data frame.

After continuously evaluating one of the one or more subsequent RF channels, the STA126 enables transmission of a corresponding one of the subsequent channel reservation confirmation messages. After transmitting the current one or corresponding one or more subsequent RF channels, the STA126 enables evaluation of the next one of the corresponding one or more subsequent RF channels. After sending the CTS message for the current RF channel, the STA126 may evaluate the next RF channel. As the STA126 evaluates each subsequent RF channel, the STA126 may transmit a CTS message when the channels are deemed to be in a channel clear-to-clear state.

The STA126 may enable access to the wireless communication medium based on transmitting a channel reservation confirmation message via the reference RF channel and based on transmitting each of one or more subsequent channel reservation confirmation messages. After gaining access to the wireless communication medium based on the transmitted channel reservation confirmation message and based on transmitting each of the one or more subsequent channel reservation confirmation messages, the STA126 enables simultaneous transmission of data frames via the reference RF channel and at least a portion of the one or more subsequent RF channels. The STAs 126 may transmit data frames simultaneously via each of the reference RF channel and the subsequent RF channel.

In various embodiments of the present invention, the channel reservation may be cancelled based on subsequent RF channel evaluations. The STA126 may enable transmission of the channel reservation confirmation message via the reference RF channel. The STA126 may enable evaluation of one or more subsequent RF channels and may subsequently transmit a channel reservation confirmation message via the reference RF channel. The STA126 may enable transmission of a channel reservation cancellation message, such as a CF-End frame, via the reference RF channel based on the evaluation. The STA126 may enable transmission of one or more subsequent channel reservation confirmation messages and one or more corresponding channel reservation cancellation messages.

Another embodiment of the present invention provides a machine readable storage, having stored thereon, a computer program having at least one code section for execution by a machine to cause the machine to perform the steps of the serial clear to self messaging procedure described herein.

The present invention can be realized in hardware, software, or a combination of hardware and software. The present invention can be realized in a centralized fashion in at least one computer system, or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware and software could be a general purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein.

The present invention can also be implemented by a computer program product, which comprises all the features enabling the implementation of the methods of the invention and which, when loaded in a computer system, is able to carry out these methods. The computer program in the present document refers to: any expression, in any programming language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following a) conversion to another language, code or notation; b) reproduced in different material forms.

While the invention has been described with reference to several particular embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims (2)

1. A method of transmitting data, comprising:

step 702, performing clear channel estimation on the reference RF channel;

step 704, determine whether the reference RF channel is clean, if so, go to step 708; if not, go to step 702;

step 708. transmitting a channel reservation confirmation message via the reference RF channel;

step 710. performing clear channel estimation on the respective one or more subsequent RF channels;

step 712, determining whether the corresponding one or more subsequent RF channels are clean; if yes, go to step 714; if not, go to 718;

step 714. transmitting one or more channel reservation confirmation messages via the respective one or more subsequent RF channels;

step 716 transmitting a data frame via at least a portion of the reference RF channel and the corresponding one or more subsequent RF channels, and then ending;

step 718. determining whether to transmit data frames only via the reference RF channel, if so, performing step 720; if not, go to 722;

step 720. transmitting a data frame via the reference RF channel, and then ending;

step 722, determining whether to wait for the corresponding one or more subsequent RF channels to become clean, and if so, performing step 710; if not, go to step 724;

step 724 transmitting a channel reservation cancellation message to relinquish the reference RF channel and one or more subsequent RF channels.

2. A system for transmitting data, comprising:

a clear channel estimation module A for performing clear channel estimation on the reference RF channel;

the judging module A enables to judge whether the reference RF channel is clean; wherein the clear channel estimation module a is further configured to perform clear channel estimation on the reference RF channel when the reference RF channel is not clean;

a transmission module A for transmitting a channel reservation confirmation message via the reference RF channel when the reference RF channel is clean;

a clear channel estimation module B enabling clear channel estimation to be performed on the respective one or more subsequent RF channels;

a judging module B enabling to judge whether the corresponding one or more subsequent RF channels are clean;

a transmitting module B for transmitting one or more channel reservation confirmation messages via the respective one or more subsequent RF channels when the respective one or more subsequent RF channels are clean;

a transmitting module C enabling simultaneous transmission of data frames via at least a portion of the reference RF channel and the respective one or more subsequent RF channels;

an acknowledgement module a for acknowledging whether the data frame was transmitted only via the reference RF channel when the corresponding one or more subsequent RF channels are unclean;

a transmitting module D for transmitting a data frame via a reference RF channel when it is confirmed that the data frame is transmitted only via the reference RF channel;

an acknowledgement module B for, when it is acknowledged that the data frame is transmitted not only via the reference RF channel, acknowledging whether to wait for the respective one or more subsequent RF channels to become clean; wherein the clear channel estimation module B is further configured to perform clear channel estimation on the respective one or more subsequent RF channels upon confirming that the respective one or more subsequent RF channels are waiting to become clean;

a transmitting module E for transmitting a channel reservation cancellation message to relinquish the reference RF channel and the one or more subsequent RF channels upon confirmation that the respective one or more subsequent RF channels do not wait for becoming clean.