Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
  • H04L69/18—Multiprotocol handlers, e.g. single devices capable of handling multiple protocols
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W80/00—Wireless network protocols or protocol adaptations to wireless operation

Definitions

• the present invention relates to wireless network, and more particularly to methods and apparatuses for transmitting and receiving legacy format data in a high throughput wireless network.
• WLANs wireless LANs
• WLANs to consumers. Although use of WLANs may reduce performance due to lower transmission rate and poorer stability as compared to wired LANs, WLANs hasve various advantages, including wireless networking capability, greater mobility and so on. Accordingly, WLAN markets have been gradually
• IEEE 802.11 which specifies a transfer rate of 1 to 2 Mbps
• IEEE 802.1 Ia which specifies a transfer rate of 1 to 2 Mbps
• IEEE 802.1 Ib which utilizes a transmission rate of 6 to 54 Mbps in the 5 GHz-National Information Infrastructure (Nil) band
• OFDM orthogonal frequency division multiplexing
• Nespot services allow access to the Internet using a WLAN according to IEEE 802.1 Ib standard, commonly called Wi-Fi (wireless fidelity).
• IEEE 802.1 Ib standard commonly called Wi-Fi (wireless fidelity).
• Communication standards for wireless data communication systems include Wide Code Division Multiple Access (WCDMA), IEEE 802.1 Ix, Bluetooth, IEEE 802.15.3, etc., which are known as 3rd Generation (3G) communication standards.
• WCDMA Wide Code Division Multiple Access
• IEEE 802.1 Ix IEEE 802.1 Ix
• Bluetooth IEEE 802.15.3
• 3G 3rd Generation
• the most widely known, cheapest wireless data communication standard is IEEE 802.1 Ib, a series of IEEE 802.1 Ix.
• An IEEE 802.1 Ib WLAN standard delivers data transmission at a maximum rate of 11 Mbps and utilizes the 2.4 GHz-Industrial, Scientific, and Medical (ISM) band, which can be used below a predetermined electric field
• IEEE 802.1 Ig developed as an extension to the IEEE 802.1 Ia standard for data transmission in the 2.4 GHz-band using OFDM and is intensively being researched.
• the Ethernet and the WLAN which are currently being widely used, both utilize a carrier sensing multiple access (CSMA) method.
• CSMA carrier sensing multiple access
• a carrier sensing multiple access with collision detection (CSMA/CD) method which is an improvement of the CSMA method, is used in a wired LAN, whereas a carrier sensing multiple access with collision avoidance (CSMA/CA) method is used in packet-based wireless data communications.
• CSMA/CD carrier sensing multiple access with collision detection
• CSMA/CA carrier sensing multiple access with collision avoidance
• a station suspends transmitting signals if a collision is detected during transmission.
• the station suspends transmission of signals when a collision is detected during the transmission of signals and transmits a jam signal to another station to inform it of the occurrence of the collision. After the transmission of the jam signal, the station has a random backoff period for delay and restarts transmitting signals.
• the station does not transmit data immediately even after the channel becomes idle and has a random backoff period for a predetermined duration before transmission to avoid collision of signals.
• the CSMA/CA method is classified into physical carrier sensing and virtual carrier sensing.
• Physical carrier sensing refers to the physical sensing of active signals in the wireless medium.
• Virtual carrier sensing is performed such that information regarding duration of a medium
• IEEE 802.11 n provides coverage for IEEE 802.11 a networks at
• the stations For operating the stations of various data rates using the CSMA/CA method, the stations must interpret MPDU/PSDU.
• some stations, that is, legacy stations may not often process data transmitted/received at high rates. In such a case, the legacy stations cannot perform virtual carrier sensing.
• FIG. 1 is a data structure of a related art format Physical Layer
• the PPDU includes a PLCP header and Physical Layer Service Data Unit (PSDU).
• PSDU Physical Layer Service Data Unit
• a data rate field 3 and a data length field 4 are used to determine a length of a data field that follows the PLCP header of
• the data rate field 3 and the data length field 4 are also used to determine the time of the data being received or transmitted, thereby performing virtual carrier sensing.
• a "Dur/ID" field which is one field among the header fields of the MPDU, is interpreted and the medium is virtually determined to be busy for an expected use time period of the medium.
• media may attempt data transmission by a backoff at a predetermined Extended Inter-Frame Space (EIFS), which is longer than a Distributed Coordination Function (DCF) Inter-Frame Space (DIFS), so that fairness in media access of all stations available in DCF is not ensured.
• EIFS Extended Inter-Frame Space
• DCF Distributed Coordination Function
• DIFS Distributed Coordination Function
• FIG. 2 is a diagram illustrating that a legacy station with a low
• a transmitter-side high throughput station (abbreviated as transmitter-side HT STA) 101 is a station complying with the IEEE 802.1 In protocols and operating using a channel bonding technique or a multiple input
• MIMO multiple output
• the MIMO technique is one type of adaptive array antenna technology that electrically controls directivity using a plurality of antennas. Specifically, in an MIMO system, directivity is enhanced using a plurality of antennas by narrowing a beam width, thereby forming a plurality of transmission paths that are independent from one another. Accordingly, a data transmission speed of a device that adopts the MIMO system increases as many times as there are antennas in the MIMO system.
• Physical carrier sensing enables a physical layer to inform an MAC layer whether a channel is busy or idle by detecting whether the physical layer has received a predetermined level of reception power. Thus, the physical carrier sensing is not associated with interpreting of data transmitted and received.
• receiver-side HT STA 102 receives the HT data and transmits an HT
• a legacy station 201 is a station complying with the
• the IEEE 802.11 standard specifies a control response frame, such as an ACK, a Request-to-Send (RTS) or a Clear-to-Send (CTS) frame, is
• the HT data has HT preamble and HT signal fields added thereto, which leads to an increase in the overhead of an PPDU, which may cause the ACK frame to result in deteriorated performance compared to the legacy format PPDU. That is to say, the length of the legacy format PPDU
• FIG. 1 is a schematic diagram of a related art format PPDU as defined by the IEEE 802.11 protocol
• FIG. 2 is a diagram illustrating that a station with a low transmission rate is incapable of performing virtual carrier sensing when a plurality of stations having a variety of transmission capabilities coexist in a network;
• FIG. 3 is a diagram illustrating a method of transmitting a
• FIG. 4 is a diagram illustrating data structures of a PPDU transmitted and received by an HT station
• FIG. 5 is a diagram showing a procedure in which a receiving unit transmits a legacy response frame when a transmitting unit transmits an HT data using channel bonding according to an exemplary embodiment of the present invention
• FIG. 6 is a diagram showing a procedure in which a receiving unit transmits a legacy response frame when a transmitting unit transmits an
• FIG. 7 is a diagram showing a procedure in which a receiving unit transmits a legacy response frame when the transmitting unit transmits an
• FIG. 8 is a schematic illustrating an HT station of transmitting
• FIG. 9 is a flowchart illustrating a procedure in which an HT station receives an HT frame and transmits a legacy frame as a response according to an exemplary embodiment of the present invention. Disclosure of Invention Technical Problem
• the present invention provides a method and apparatus for enabling a legacy station to perform virtual carrier sensing when a plurality of stations with heterogeneous capabilities coexist in a wireless network.
• the present invention also provides a method and apparatus for transmitting and receiving legacy format data in a high throughput wireless network.
• the present invention relates to wireless network, and more particularly to methods and apparatuses for transmitting and receiving legacy format data in a high throughput wireless network.
• a method of transmitting legacy format data in a high throughput (HT) wireless network comprising accessing to the wireless network, receiving first data compliant with a first protocol, wherein the first data is transmitted by a first station accessed to the wireless network, and second data compliant with a second protocol to the first station, wherein the first protocol is downward compatible with the second protocol.
• HT high throughput
• a method of receiving legacy format data in a high throughput wireless network comprising accessing to the wireless network, transmitting first data compliant with a first protocol to a first station connected to the wireless network, and receiving second data compliant with a second protocol from the first station, wherein the first station is downward compatible with the second protocol.
• an apparatus of transmitting and receiving legacy format data in a high throughput (HT) wireless network comprising a transmitting unit which transmits first data compliant with a first protocol or second data compliant with a second protocol to the wireless network, the first station being downward compatible with the second protocol, a receiving unit which receives data from the wireless network, and a legacy transmission controlling unit which controls the transmitting unit to transmit the second data in accordance with the second protocol.
• a method of transmitting data in a wireless network comprising accessing to the wireless network, receiving first data according to channel bonding, wherein the first data is transmitted from a first station connected to the wireless network, and transmitting an acknowledgement
• a wireless network apparatus comprising a receiving unit which accesses a wireless network and receives first data according to channel bonding, wherein the first data is transmitted from a first station connected to the wireless network, and a transmitting unit which transmits an acknowledgement (Ack) frame via each of channels associated with the channel bonding.
• the computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that are executed on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.
• Each block of the flowchart illustrations may represent a module, segment, or portion of code, which comprises one or more executable
• FIG. 3 is a diagram illustrating a method of transmitting a response frame by using legacy method according to an exemplary embodiment of the present invention.
• HT stations 101, 102, and 103 and a legacy station 201 coexist in a wireless network.
• the transmitter-side HT station 101 transmits HT data to the receiver-side HT station 102.
• the HT data means data transmitted at a high rate using a channel bonding or MIMO technique.
• the HT (High Throughput) stations include stations adapting to protocol enabling high rate data
• the legacy station 201 is not capable of interpreting HT data, it cannot perform virtual carrier sensing. Instead, the legacy station determines that a medium is
• operation SI l begins and a backoff may be performed after waiting of an EIFS duration.
• the transmitter-side HT station 101 completes transmission of the HT data, the procedure goes to operation Sl 1.
• the receiver- side HT station 102 transmits a legacy response frame after a duration of a SIFS.
• the legacy response frame is an Ack frame generated according to the 802.1 Ia, 802.1 Ib, or 802.1 Ig protocol.
• the legacy response frame can be transmitted to and received from both a legacy station and an HT station. After receiving each legacy response frame, each of the HT stations 101, 102, 103
• the HT stations 101, 102, and 103 go to operation S 12 and perform a backoff procedure after the duration of a DIFS.
• the legacy station since the legacy station is capable of interpreting a legacy response frame but incapable of interpreting HT data, it is allowed to wait for the duration of the DIFS in operation S 12 to prohibit the legacy station 201 from performing the backoff procedure. Consequently, the legacy
• FIG. 4 is diagram illustrating a structure of a PPDU transmitted and received by an HT station according to an exemplary embodiment of the present invention.
• a legacy format PPDU ((PLCP Protocol data unit)(30) includes a L-STF (Legacy Short Training Field), a L-LTF (Legacy Long Training Field) and a L-SIG (Legacy Signal Field), and a DATA payload. Similar to FIG. 1, the L-SIG includes data transmission rate, Reserved bits, LENGTH, Parity, and Tail Bits.
• the legacy format PPDU has the DATA payload following the L-STF, L-LTF, L-SIG.
• L-STF, L-LTF, L-SIG contains information regarding power management, signal and so on, respectively.
• Legacy data follows the legacy preamble.
• the legacy preamble 30 can be interpreted by both an HT station and a legacy station.
• the HT preamble contains information regarding HT data.
• the HT preamble consists of an HT-SIG, an HT-STF, and an HT-LTF.
• the HT-SIG consists of multiple fields including a length of HT data (Length), an MCS information defining modulation and coding schemes (MSC), an bits specifying the presence of advanced coding, a Sounding packet indicating whether transmission has been
• HT data follows HT-SIG containing the above information, HT-STF, and HT-LTFs as much as the number of HT- LTFs indicated in the HT-SIG.
• FIG. 5 is a diagram showing a procedure in which a receiving unit transmits a legacy response frame when a transmitting unit transmits an HT data using channel bonding according to an exemplary embodiment of the present invention.
• a transmitting unit selects two adjacent channels of a current channel, that is, the current channel and a directly next channel or a directly previous channel and the current channel, bonded to each other, and transmits the same to a receiving unit, the receiving unit receives the same and transmits a legacy response frame to each channel.
• FIG. 5 shows an example in which each antenna is incapable of handling different channels.
• HT station employs an overlap mode in which data containing a legacy response frame 30 overlaps from a lower sub-channel to an upper sub-channel through a single antenna 181.
• the legacy response frame 30 can be transmitted through the upper and lower sub-channels.
• the legacy response frame 30 can be received by HT stations and legacy stations existing
• a PPDU including a legacy response frame consists of an L-STF (Legacy Short Training Field), an L-LTF (Legacy Long Training Field), an L-SIG (Legacy Signal Field), and a DATA (Legacy Data) payload, as described above with reference to FIG. 4.
• L-STF Legacy Short Training Field
• L-LTF Legacy Long Training Field
• L-SIG Legacy Signal Field
• DATA Legacy Data
• FIG. 6 is a diagram showing a procedure in which a receiving unit transmits a legacy response frame when a transmitting unit transmits an HT data using channel bonding according to another exemplary embodiment of the present invention, in which antennas 181 and 182 transmit data to different channels, unlike in FIG. 5.
• the transmitting unit selects two adjacent channels of a current channel, that is, the current channel and a directly next channel or a directly previous channel and the current channel, bonded to each other, and transmits the same to the receiving unit
• the receiving unit receives the same and transmits a legacy response frame to
• the respective antennas 181 and 182 are capable of handling different channels.
• the receiving unit accesses lower and upper sub-channels using the respective antennas 181 and 182 and transmits the same legacy response frame 300.
• a structure of a legacy format frame is the same as described in FIG. 4.
• Legacy format data is simultaneously transmitted to both a control channel and an extension channel in response to a frame transmitted using channel bonding, as shown in FIG. 5 and 6, which allows the legacy format data to be received by stations in the extension channel as well.
• FIG. 7 is a diagram showing a procedure in which a receiver-
• the side HT station transmits a legacy response frame when the transmitter-side HT station transmits HT data without using channel bonding according to an exemplary embodiment of the present invention.
• the receiver-side HT station utilizes one antenna 181 to transmit a legacy response frame via a
• the transmitter-side HT station is capable of receiving the legacy response frame received through the current channel.
• Other HT stations can interpret the legacy response frame to enable virtual carrier sensing.
• legacy stations communicating via the current channel can also interpret the legacy response frame.
• a structure of a legacy format frame is the same as described in FIG. 4. [52] As illustrated in FIGS. 5 through 7, the receiver-side HT station transmits the legacy PPDU in various manners according to the transmission method employed by the transmitter-side HT station.
• the receiver-side HT station can be informed of the transmission method employed by the transmitter-side HT station from MCS values in the HT-SIG field of the HT PPDU shown in FIG. 4.
• MCS modulation and coding scheme
• An HT station can transmit not only the response frame but also an PPDU of a control frame including short data such as a CTS (Clear- to- Send) frame or an RTS (Ready-to-Send) frame.
• a legacy station can perform virtual carrier sensing.
• a legacy format PPDU is transmitted, thereby reducing a total amount of data transmitted and received in the overall wireless network and implementing a wireless network in which the HT station and a legacy station coexist.
• the term "unit” as used herein, means, but is not limited to, a software or hardware component or module, such as a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks.
• a unit may advantageously be configured to reside on the addressable storage medium and configured to be executed on one or more processors.
• a unit may include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data,
• components and units may be combined into fewer components and modules or further separated into additional components and units.
• the components and units may be implemented such that they are executed on one or more CPUs in a communication system.
• FIG. 8 is a schematic illustrating an HT station which transmits legacy format data according to an exemplary embodiment of the present invention.
• the HT station 100 includes a transmitting unit 110, a receiving unit 120, an encoding unit 130, a decoding unit 140, a controlling unit 150, a legacy transmission controlling unit 160, and two antennas 181 and 182.
• the antennas 181 and 182 receive and transmit wireless signals.
• the transmitting unit 110 transmits signals to the antennas 181 and 182, and the encoding unit 130 encodes data to generate signals to be transmitted to the antennas 181 and 182 by the transmitting unit 110.
• the data In order to transmit signals via two or more antennas using an MIMO technique, the data must be divided and then encoded separately.
• the transmitting unit 110 selects two adjacent channels, including a current channel and a directly next channel or a directly previous channel, to be bonded to each other, and transmits the signals
• the receiving unit 120 receives signals from the antennas 181 and 182, and the decoding unit 140 decodes the signals received by the receiving unit 120 into data. When the data is received using an MIMO technique, it is necessary to integrate the data transmitted via the two channels.
• the legacy transmission controlling unit 160 controls short- length data, e.g., a response (ACK) frame, a CTS frame, or an RTS frame, to be transmitted in a legacy format.
• the control unit 150 manages and controls the exchange of information among various elements of the HT station 100.
• FIG. 9 is a flowchart illustrating a procedure in which an HT station receives an HT frame and transmits a legacy frame as a response frame according to an exemplary embodiment of the present invention.
• the HT station accesses a wireless network in operation S301.
• the accessing the wireless network encompasses not only accessing an existing wireless network but also newly generating a wireless network.
• operation S301 may include generating a basic service set (BSS), such as operation of an Access Point (AP).
• BSS basic service set
• AP Access Point
• a first station existing in the wireless network receives first data compliant with a first protocol in operation S302.
• the first protocol includes protocols enabling high rate data transmission and reception, e.g., the IEEE 802.1 In protocol.
• the first protocol may include protocols having
• the term "downward compatibility" used herein means that an upgraded protocol or software is compatible with past proposed protocols or software.
• the IEEE 802.1 In protocols can interpret data that is transmitted and received in the IEEE 802.1 Ia, IEEE 802.1 Ib, or IEEE 802.1 Ig protocol, and can transmit/receive HT data according to the interpretation. The same is true when upgraded software is available to allow data generated from existing version software to be interpreted or managed.
• After receiving the first data it is determined whether the first data is transmitted using channel bonding in operation S310. If the first data is transmitted using channel bonding, second data compliant with a second protocol is transmitted via the respective channels used with channel bonding in operation S320.
• the second protocol frames that can be interpreted by legacy stations receiving channels associated with channel bonding are transmitted.
• the first protocol is compliant with the IEEE 802.1 In
• the second protocol includes protocols with which the IEEE 802.1 In protocol is downward compatible, e.g., IEEE 802.1 Ia, 802.1 Ib, 802.1 Ig, or the like.
• the transmission procedures have been described above with reference to FIG. 5.
• the wireless network shown in FIG. 9 may be an BSS with an
• the second data is short data including control frames, such as Ack, CTS, RTS, etc.
• the second data can be interpreted by legacy stations, so that
• the legacy stations can perform virtual carrier sensing. Accordingly, the use of the second data enhances transmission efficiency in a wireless network without legacy stations.
• the legacy stations can perform virtual carrier sensing.
• short data is transmitted in a legacy format, thereby enhancing transmission efficiency.

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• 2006
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