WO2013119075A1 - 무선통신시스템에서 신호를 송수신하는 방법 및 장치 - Google Patents
무선통신시스템에서 신호를 송수신하는 방법 및 장치 Download PDFInfo
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- WO2013119075A1 WO2013119075A1 PCT/KR2013/001030 KR2013001030W WO2013119075A1 WO 2013119075 A1 WO2013119075 A1 WO 2013119075A1 KR 2013001030 W KR2013001030 W KR 2013001030W WO 2013119075 A1 WO2013119075 A1 WO 2013119075A1
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- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000004891 communication Methods 0.000 title claims abstract description 34
- 238000012549 training Methods 0.000 claims description 10
- 230000008054 signal transmission Effects 0.000 claims description 7
- 238000001994 activation Methods 0.000 description 19
- 230000004913 activation Effects 0.000 description 14
- 238000010586 diagram Methods 0.000 description 12
- 239000000523 sample Substances 0.000 description 12
- 230000004044 response Effects 0.000 description 10
- 230000003213 activating effect Effects 0.000 description 9
- 230000005540 biological transmission Effects 0.000 description 9
- 230000001419 dependent effect Effects 0.000 description 8
- 238000001228 spectrum Methods 0.000 description 7
- 230000008569 process Effects 0.000 description 6
- 238000001514 detection method Methods 0.000 description 5
- 230000006870 function Effects 0.000 description 4
- 230000003595 spectral effect Effects 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 238000012545 processing Methods 0.000 description 2
- 238000003491 array Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000010295 mobile communication Methods 0.000 description 1
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- 230000009467 reduction Effects 0.000 description 1
- 230000011664 signaling Effects 0.000 description 1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W74/00—Wireless channel access
- H04W74/08—Non-scheduled access, e.g. ALOHA
- H04W74/0808—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/14—Spectrum sharing arrangements between different networks
Definitions
- the following description relates to a method and apparatus for transmitting and receiving signals in a wireless communication system.
- IEEE 802.11a and b are described in 2.4. Using unlicensed band at GHz or 5 GHz, IEEE 802.11b provides a transmission rate of 11 Mbps and IEEE 802.11a provides a transmission rate of 54 Mbps.
- IEEE 802.11g applies Orthogonal Frequency Division Multiplexing (OFDM) at 2.4 GHz, providing a transmission rate of 54 Mbps.
- IEEE 802.11n applies Multiple Input Multiple Output OFDM (MIMO-OFDM) to provide a transmission rate of 300 Mbps for four spatial streams.
- IEEE 802.11n supports channel bandwidths up to 40 MHz, in this case providing a transmission rate of 600 Mbps.
- the standard for specifying the operation of an unlicensed device in the TV whitespace (TVWS) band is the IEEE 802.11af standard.
- TVWS is a frequency assigned to broadcast TV, which includes the Ultra High Frequency (UHF) band and the very high frequency (VHF) band, and does not interfere with the communication of licensed devices operating in that frequency band. Means the frequency band under which the use of an unlicensed device is permitted under conditions.
- the licensed device may include a TV, a wireless microphone, or the like.
- the licensed device may be referred to as an incumbent user or primary user.
- a signaling protocol such as a common beacon frame, a frequency sensing mechanism, and the like may be required to solve a coexistence problem between unlicensed devices using TVWS.
- Unlicensed devices that operate on TVWS can be classified into fixed devices, Personal / Portable Mode I devices, and Personal / Portable Mode II devices.
- the fixed device needs to register its location in the geo-location database as a fixed terminal, and accesses the geographic location database to obtain an available channel list. It operates on the available channel list and stops using it if the channel being used is no longer available.
- the Personal / Portable Mode II device does not register its location in the geographic location database as a personal portable terminal, but accesses the geographic location database to obtain a list of available channels from its location. It operates on the available channel list and stops using it if the channel being used is no longer available. Compared to fixed devices, the transmit output power is limited. Personal / Portable Mode I devices receive control from Fixed and Personal / Portable Mode II devices.
- An IEEE 802.11 TVWS terminal refers to an unlicensed device operating using an IEEE 802.11 media access control (MAC) and a physical layer (PHY) in the TVWS spectrum.
- MAC media access control
- PHY physical layer
- IEEE 802.11af PHY which uses 1/10 down-clocking of IEEE 802.11ac PHY, provides 2MHz / 4MHz / 8MHz / 16MHz / 8 + 8MHz channel bandwidth.
- the Guard Interval For 1/10 down-clocking, the Guard Interval (GI) will increase from 0.8 us to 8 us.
- An embodiment of the present invention relates to a frame structure that can facilitate carrier sensing of other terminals, particularly in a method of transmitting and receiving a signal.
- a signal for carrier sensing of another terminal for a predetermined time interval in a frequency band of a frequency bandwidth of a channel used by the terminal is transmitted. And transmitting the signal, wherein the signal for carrier sensing includes information on the frequency bandwidth of the channel.
- a second technical aspect of the present invention is a terminal device for transmitting a signal in a wireless communication system, comprising: a transceiver; And a processor for controlling the apparatus including the transceiver, wherein the processor transmits a signal for carrier sensing of another terminal for a predetermined time interval in a frequency band of a frequency bandwidth of a channel used by the terminal,
- the carrier sensing signal is a terminal device including information on a frequency bandwidth of the channel.
- the first to second technical aspects may include all of the following.
- the signal for carrier sensing may be transmitted before the terminal transmits a signal in the frequency bandwidth of the channel.
- the partial frequency band may correspond to a frequency band in which a plurality of channels having different bandwidths overlap each other, which are set in the wireless communication system.
- signal transmission may not be performed in the remaining frequency band except for the partial frequency band.
- the signal for carrier sensing may include a narrowband short training field (N-STF), a narrowband long training field (N-LTF), and a narrowband signal (N-SIG).
- N-STF narrowband short training field
- N-LTF narrowband long training field
- N-SIG narrowband signal
- Information on where the frequency bandwidth of the channel is located in the entire frequency band of the wireless communication system may be included in the beacon frame.
- receiving a signal for carrier sensing for a predetermined time interval in a frequency band of a channel set in the wireless communication system Includes, the signal for the carrier sensing, the signal receiving method comprising information on the frequency bandwidth of the channel.
- a fourth technical aspect of the present invention is a terminal device for receiving a signal in a wireless communication system, comprising: a transceiver; And a processor for controlling the apparatus including the transceiver, wherein the processor receives a signal for carrier sensing for a predetermined time period in a part of a frequency band of a channel set in the wireless communication system, and receives the signal for the carrier sensing.
- the signal is a terminal device that includes information about the frequency bandwidth of the channel.
- the third to fourth technical aspects may include all of the following.
- the signal for carrier sensing may be transmitted before transmitting a signal in the frequency bandwidth of the channel.
- the frequency band may correspond to a frequency band in which a plurality of channels having different bandwidths set in the wireless communication system including the channel overlap each other.
- signal transmission may not be performed in the remaining frequency band except for the partial frequency band.
- the signal for carrier sensing may include a narrowband short training field (N-STF), a narrowband long training field (N-LTF), and a narrowband signal (N-SIG).
- N-STF narrowband short training field
- N-LTF narrowband long training field
- N-SIG narrowband signal
- Information on where the frequency bandwidth of the channel is located in the entire frequency band of the wireless communication system may be received from the beacon frame.
- the terminal can sense the carrier of the channels of different frequency bands while minimizing the processing burden.
- FIG. 1 is a diagram illustrating an example of a configuration of a WLAN system.
- FIG. 2 is a diagram illustrating another example of a configuration of a WLAN system.
- FIG. 3 is a schematic diagram of active scanning.
- 5 is a diagram illustrating an activation process of an STA.
- FIG. 6 is a view for explaining a frame structure proposed in the present invention.
- 15 is a view for explaining a beacon frame according to an embodiment of the present invention.
- 16 is a block diagram illustrating a configuration of a wireless device according to an embodiment of the present invention.
- FIG. 1 is a diagram illustrating an example of a configuration of a WLAN system.
- the WLAN system includes one or more basic service sets (BSSs).
- BSS is a set of stations (STAs) that can successfully synchronize and communicate with each other.
- STA is a logical entity that includes a medium access control (MAC) and a physical layer interface to a wireless medium, and includes an access point (AP) and a non-AP non-AP station (STA). do.
- the portable terminal operated by the user among the STAs is a non-AP STA, and when referred to simply as an STA, it may also refer to a non-AP STA.
- a non-AP STA is a terminal, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile terminal, or a mobile subscriber. It may also be called another name such as a mobile subscriber unit.
- the AP is an entity that provides an associated station (STA) coupled to the AP to access a distribution system (DS) through a wireless medium.
- STA station
- DS distribution system
- the AP may be called a centralized controller, a base station (BS), a Node-B, a base transceiver system (BTS), or a site controller.
- BS base station
- BTS base transceiver system
- BSS can be divided into infrastructure BSS and Independent BSS (IBSS).
- IBSS Independent BSS
- the BBS shown in FIG. 1 is an IBSS.
- the IBSS means a BSS that does not include an AP. Since the IBSS does not include an AP, access to the DS is not allowed, thereby forming a self-contained network.
- FIG. 2 is a diagram illustrating another example of a configuration of a WLAN system.
- the BSS shown in FIG. 2 is an infrastructure BSS.
- Infrastructure BSS includes one or more STAs and APs.
- communication between non-AP STAs is performed via an AP.
- AP access point
- a plurality of infrastructure BSSs may be interconnected through a DS.
- a plurality of BSSs connected through a DS is called an extended service set (ESS).
- STAs included in the ESS may communicate with each other, and a non-AP STA may move from one BSS to another BSS while seamlessly communicating within the same ESS.
- the DS is a mechanism for connecting a plurality of APs.
- the DS is not necessarily a network, and there is no limitation on the form if it can provide a predetermined distribution service.
- the DS may be a wireless network such as a mesh network or a physical structure that connects APs to each other.
- Spectrum not used by a licensed device is called whitespace and can be used by an unlicensed device.
- whitespace In order for an STA to operate in the whitespace spectrum, it is necessary to first provide a protection scheme for an incumbent user. In order for the STA or the AP to protect the licensed device, only the channel not used by the licensed device must be used. Channels that can be used by an unlicensed device because they are not being used by a licensed device are called available channels.
- the most basic way for the STA or AP to determine the availability of a TV channel is to find a TV channel schedule by accessing spectrum sensing and a database (DB).
- the information of the DB includes information such as usage schedule of a specific channel of a licensed device at a specific location. Therefore, an STA or AP that wants to determine whether a TV channel is available must access a DB through the Internet and obtain DB information based on its location information.
- the STA In order to access the network, the STA must find a network that can participate. The STA must identify a compatible network before joining the wireless network. A network identification process existing in a specific area is called scanning. There are two types of scanning methods, active scanning and passive scanning.
- FIG. 3 is a schematic diagram of active scanning.
- the STA performing scanning transmits a probe request frame and waits for a response to discover which AP exists in the vicinity while moving channels.
- the responder transmits a probe response frame to the STA that transmits the probe request frame in response to the probe request frame.
- the responder is the STA that last transmitted the beacon frame in the BSS of the channel being scanned.
- the AP transmits a beacon frame, so the AP becomes a responder.
- the responder is not constant because the STAs in the IBSS rotate and transmit the beacon frame.
- the scanning STA 300 transmits a probe request frame 305
- Responder 1 310 of BSS1 and Responder 2 320 of BSS2 that have received the probe request frame are each probe response frame 1 ( 315 and the probe response frame 2 325 are transmitted to the scanning STA 300.
- the scanning STA 300 receiving the probe response frame stores the BSS related information included in the received probe response frame, moves to the next channel, and performs scanning on the next channel in the same manner.
- the STA performing scanning waits for a beacon frame while moving channels.
- the beacon frame is one of management frames in IEEE 802.11.
- the beacon frame is notified of the existence of a wireless network and is periodically transmitted to allow the STA performing scanning to find the wireless network and participate in the wireless network.
- the AP In the infrastructure BBS, the AP periodically transmits a beacon frame.
- the STA that performs the scanning receives the beacon frame, the STA stores the information on the BSS included in the beacon frame and records beacon frame information in each channel while moving to another channel.
- the beacon frame 1 415 transmitted by the AP1 410 of the BSS1 and the beacon frame transmitted by the AP2 420 of the BSS2 are performed by the scanning STA 400 performing the channel scanning by the passive scanning method on the specific channel. If receiving 2 425 and not receiving beacon frame 3 435 transmitted by AP3 430 of BSS3, scanning STA 400 stores that two BSSs (BSS1, BSS2) were found in the measurement channel. And move to another channel.
- active scanning has the advantage of less delay and power consumption than passive scanning.
- Unlicensed devices operating in the white space band may be classified into an enabling STA and a dependent STA.
- the activating STA is an STA capable of activating the dependent STA.
- the activating STA may transmit a signal without receiving an enabling signal and may initiate a network.
- the activating STA may provide geo-location information to a database (DB) and obtain available channel information available at the geographic location from the DB.
- the activating STA does not necessarily need to be a WLAN STA, but may be a logical entity or a network server capable of providing services related to activation.
- a dependent STA is a STA that can transmit a signal only when receiving an activation signal and is controlled by the activation STA.
- the dependent STA must be activated through the activating STA and cannot be independently activated.
- 5 is a diagram illustrating an example of an activation process of an STA.
- IEEE 802.11y is a standard created for the operation of an unlicensed device in the 3.5 GHz band.
- the activation process is described, and the activation process is called Dynamic STA Enablement (DSE).
- DSE Dynamic STA Enablement
- the process of activating the dependent STA by the activating STA may follow a process similar to the dynamic STA activation of IEEE 802.11y.
- the activation process applied in the white space may not necessarily be the same as the DSE process, but basically the same in that STAs dependent on the corresponding band / channel may transmit signals only after receiving the activation signal.
- the activating STA may transmit a beacon or probe response frame including an activation signal to the dependent STA (S510).
- a signal indicating that activation is possible is called an enabling signal.
- a beacon or probe response frame including an activation signal element corresponds to an activation signal.
- the dependent STA that receives and decodes the activation signal transmits an activation request frame to the activation STA using the channel receiving the signal (S520), and receives an activation response frame from the activation STA.
- Receive S530.
- an unlicensed device that wants to use TVWS should provide protection for the licensed device. Therefore, the unlicensed device must check whether the licensed device occupies the band before starting to transmit the signal in the TVWS.
- the unlicensed device may perform spectrum sensing / carrier sensing to determine whether the corresponding band is used by the licensed device.
- Spectrum sensing mechanisms include energy detection, feature detection, and the like.
- the unlicensed device may determine that the licensed device is using the specific channel when the strength of the signal received on the specific channel is greater than or equal to a predetermined value or when the DTV preamble is detected. If it is determined that the licensed device is in use in a channel immediately adjacent to the channel currently being used, the unlicensed device should lower the transmission power.
- the unlicensed device should access a database (DB) through the Internet or a dedicated network to obtain channel list information available for the unlicensed device in the corresponding area.
- the DB is a database that stores and manages channel usage information that is dynamically changed according to the information of the licensed device registered to the user and the geographical location and usage time of the licensed devices.
- the white space band includes the above-described TVWS, but is not limited thereto.
- the term white space band refers to a band in which an operation of an unlicensed device is allowed only when the operation of the licensed device is preferentially permitted and protection for the licensed device is provided.
- a white space device refers to a device operating in a white space band.
- a device according to the IEEE 802.11 system may also be an example of a white space device.
- the white space device uses an IEEE 802.11 medium access control (MAC) layer and a physical layer (PHY) layer in the white space band. It may refer to an unlicensed device that operates. That is, a general AP and / or STA according to the 802.11 standard operating in the white space band may correspond to an example of an unlicensed device.
- MAC medium access control
- PHY physical layer
- the channel may mean an example illustrated in the IEEE 802.11ac PHY and the IEEE 802.11af PHY described in Table 1 above, but is not necessarily limited thereto, and other than the wireless communication system illustrated above.
- WLAN This may mean a channel set in a wireless communication system.
- the terminal may be replaced with the above-mentioned terms such as AP, STA, User Equipment (UE), Mobile Station (MS), Mobile Subscriber Station (MSS), and Subscriber Station (SS).
- the frequency bandwidth of the illustrated channel is x MHz, and it is understood that a specific signal is transmitted only in some frequency bands (z MHz) of the frequency bands of the channel at the beginning (0 to tn) of the channel on the time axis.
- the specific signal may be transmitted by a terminal using the channel (for example, a signal transmitted by the channel) for carrier sensing of other terminals.
- the specific signal for carrier sensing may include information on the frequency bandwidth of the channel.
- the signal for carrier sensing may include information that may inform that the bandwidth of the corresponding channel is x MHz.
- the specific signal for carrier sensing may include a narrowband short training field (N-STF), a narrowband long training field (N-LTF), and a narrowband signal (N-SIG) as illustrated in FIG. 6.
- the N-STF may be for automatic gain control convergence, timing acquisition, and coarse frequency acquisition for common sensing band.
- the N-LTF may be for estimating a channel between each spatial mapper input and the reception chain for a common sensing band.
- the N-SIG may include information (eg, frequency bandwidth, length, rate, address, etc.) of a wideband body (corresponding to a channel frequency band in FIG. 6).
- the N-SIG may perform a function of notifying which channel is transmitted at what length and rate in the actual frame transmitted after the N-SIG through such information as bandwidth, length, and rate.
- the frequency bandwidth represents the bandwidth over which the W-STF, W-LTF, W-SIG, and DATA are transmitted, that is, the bandwidth of the corresponding channel, and the W-STF, W-LTF, and W-SIG. Is needed to detect it.
- the address information informs the sender / receiver of the corresponding frame. If the receiver is a receiver, the address information may be used to receive the actual frame transmitted subsequently using information such as bandwidth, length, and rate.
- the NAV is set using the length and rate information.
- the above-mentioned specific signal for carrier sensing may consist of at least one OFDM symbol.
- the specific configuration of the specific signal for the carrier sensing that is, N-STF, N-LTF, N-SIG is only an example, as long as the terminal / channel includes at least some of the above-described information.
- the wireless communication system may have a different name and configuration depending on the type / setting of the wireless communication system.
- a signal for carrier sensing including information related to the bandwidth of the channel is transmitted through some bandwidth of the channel before the signal transmission using the bandwidth of the corresponding channel is performed.
- the aspect of transmitting a signal and the side of receiving a signal in such a frame structure will be briefly described.
- the terminal may transmit a signal for carrier sensing of another terminal for a predetermined time interval in some frequency bands of the frequency bandwidth of the channel used by the terminal.
- the signal for carrier sensing may include information on the frequency bandwidth of the channel.
- the terminal may transmit control information (for example, in the case of FIG. 6, STF, LTF, and SIG) and data.
- the terminal may perform carrier sensing to check whether a plurality of channels corresponding to the frequency band are available in a specific frequency band. In this case, the terminal may not perform carrier sensing in accordance with the bandwidth of all channels set in the wireless communication system, but may perform carrier sensing only in accordance with the frequency bandwidth in which the signal for carrier sensing described above is transmitted.
- a frequency bandwidth through which a signal for carrier sensing is transmitted may correspond to a frequency band in which a plurality of channels having different bandwidths are set in a wireless communication system operating in a terminal.
- the frequency bandwidth through which the signal for carrier sensing is transmitted may mean a common sensing band.
- the channelization structure of the TVWS and an example of a frame structure for carrier sensing in the channel division structure are described, but are not necessarily limited thereto and include a plurality of channels having different bandwidths in a specific frequency band. It turns out that the channels are set and are generally applicable to a wireless communication system in which the terminal can use the corresponding channel through carrier sensing.
- FIG. 7 is a diagram illustrating channel division that may be the premise of Embodiment 1.
- the horizontal axis is the frequency axis and each square box represents a WLAN channel.
- the number in the square box is the bandwidth of the channel and the center frequency of the channel is indicated in the center of the box.
- the shaded part is the common sensing band.
- FIG. 7 illustrates WLAN channel division in four consecutive TV channels, and the illustration of FIG. 7 is repeated every four TV channels in the total TV WS bandwidth.
- the WLAN terminal has a guard band of 1 MHz on both sides of the TV channel so that only one TV channel can be used. Located. This is to satisfy the spectrum mask of the Regulation. If a WLAN terminal can use two consecutive TV channels, it can use an 8 MHz channel or two 4 MHz channels as defined above. The 8 MHz channel is centered between two consecutive channels with a guard band of 2 MHz on either side of the total 12 MHz. In order for a WLAN terminal to use a 16 MHz channel, at least three consecutive 6 MHz TV channels are required. In this case, however, there is only 1 MHz of guard band on each side. In this case, it is assumed that RF satisfying the spectral mask is difficult in this case. Therefore, in the example of FIG.
- the WLAN terminal may use the 16 MHz channel only when there are four consecutive TV channels.
- the WLAN terminal may use two or more 4 MHz channels or 8 MHz channels instead of the 16 MHz channels.
- the 16 MHz channel is centered with guard bands of 4 MHz on either side of the total 24 MHz (6 MHz * 4 TV channels).
- a 32 MHz channel may also be defined in a similar manner as described above. They are centered with guard bands of 2 MHz on each side of six consecutive TV channels. The 32 MHz channel can be repeated every six TV channels.
- the channel division as shown in FIG. 7 has an advantage that a good performance can be achieved even in an environment having one or two consecutive TV channels. If 4 MHz is not in the TV channel, it is difficult to satisfy the spectral mask, which is why WLAN terminals cannot use the channel or use expensive RF chips. In the urban area, the channel division of the present invention exhibits a great effect because there are only a few TVWS available for WLAN terminals in the urban area and most of them are not continuous. On the other hand, in the channel division shown in FIG. 7, since the 8 MHz and 16 MHz channels do not include 4 MHz channels, the carrier sensing method of 802.11ac does not operate.
- 802.11ac transmits frames in 40 MHz, 80 MHz, and 160 MHz channels
- the PHY header portion is repeatedly transmitted in the same structure on the frequency axis by 20 MHz. Even if the terminal receives only the 20 MHz channel, it is possible to know that the frame is transmitted in the 40 MHz, 80 MHz, and 160 MHz channels through the PHY header. However, this is possible because the 802.11ac channels are perfectly overlapped (40 MHz channel consists of two 20 MHz channels, 80 MHz channel consists of two 40 MHz channels and 160 MHz channel consists of two 80 MHz channels). It is not applicable to the discontinuous channel structure such as 7.
- the common sensing band is assigned to a specific frequency band common to each channel. This can be solved by setting to and applying the frame structure of the present invention as described above. That is, in FIG. 7, a frequency band corresponding to a shaded portion in which 4, 8, and 16 MHz channels overlap may be set as a common sensing band.
- a header for transmitting a signal for carrier sensing shown in FIG. 8 may be transmitted.
- the terminal performing carrier sensing may determine the presence or absence of the signal by measuring the energy level of the signal received in the common sensing band.
- the reference value of the energy level may be set in consideration of the ratio of the total channel bandwidth of the overlapping portion, the transmission power, and the like.
- FIG. 8 shows a frame having the same structure as that described in FIG. 6 in (a) 4 MHz, (b) 8 MHz, and (c) 16 MHz channels, respectively, and the detailed description thereof will be replaced with the description of FIG. 6. do.
- the common sensing band may be located on either the right or the left side of the channel (based on a low frequency), and thus the terminal needs to distinguish the channel.
- the channel division is modified so that the common sensing band is always present at both ends of the 4 MHz channel regardless of the 4 MHz channel position so that the UE does not need to distinguish it, it may be as shown in FIG. 9.
- the channel division structure as shown in FIG. 9 when the frame structure proposed in the present invention is applied to a channel having a bandwidth of 4 MHz, 8 MHz, and 16 MHz, the channels shown in FIGS. 10A, 10B, and 10C are illustrated in FIGS. As shown.
- a WLAN terminal can use a 16 MHz channel with a guard band of 1 MHz on each side of three consecutive TV channels. If the RF chip performance is good enough, it is possible.
- a common sensing band may be up to 3 MHz.
- the common sensing band can be set to 1 MHz or 2 MHz for symmetry. 12 (a), (b) and (c) show a frame structure to which the present invention is applied in the channel division structure as shown in FIG.
- the channel division structure may be configured as shown in FIG. 13, and in this case, the frame structure of each channel is as shown in FIGS. 14A, 14B, and 14C. Detailed description thereof will be replaced with the above description.
- the terminal performing carrier sensing when the terminal performing carrier sensing knows information about the bandwidth of the corresponding channel through the common sensing band, the terminal may determine whether the corresponding channel is available.
- the premise is that the terminal performing the carrier sensing should know in advance information on where the channel is located in the frequency band.
- information about where each channel is located in the frequency band may be set to be included in the beacon frame. That is, information on where each channel is located in the frequency band may be configured as a channel information field and included in a beacon frame as illustrated in FIG. 15. In FIG. 15, each field is defined in the 802.11 standard, and a detailed description thereof will be omitted.
- the UE can inform the UE of the channel in which the WLAN network is operating by notifying only the channel number.
- the designated channel number is changed once, it is difficult for the terminal to recognize it, and there may be a burden of knowing all the channel numbers for each country.
- ii) consists of center frequency and bandwidth
- the terminal does not need to know all the channel numbers and can accurately move the operating channel.
- Table 2 shows the value of the channel information field of the beacon frame that the AP operating on the previous 8 MHz channel 5 sends on the 4 MHz channel 1 and 2.
- the number of bits required is the smallest when i) is used, but there is a disadvantage in that the terminal has a lot of additional information.
- the terminal may operate without any problem even if the terminal does not know the channel number or the channel number is changed.
- a specific signal is added to a guard tone for use.
- the reason for having a guard tone is generally to avoid interference at both ends, which can be used to facilitate carrier sensing.
- the leftmost 4 MHz channel and the 16 MHz channel will be described as an example.
- the right side of the 4 MHz channel and the left side of the 16 MHz channel overlap 1 MHz.
- the overlap of data / pilot tones is about 0.2 MHz. If two channels are transmitted with a guard tone, 0.2 MHz signals are sensed with each other. In this situation, the energy detection method is used because the channels are different from each other. However, since only 0.2 MHz signals are caught from each other, the received power is very low, making detection very difficult. Eventually, the sensing fails, causing simultaneous transmission and interfering with each other. However, if a specific signal is put on the protection tone and transmitted, the detection and reception may be easier since all 1 MHz signals are received and sensed.
- the guard tone may only be available on some channels.
- the 4 MHz channel is difficult to satisfy the spectral mask, so it is not used with a guard tone.
- a signal can be put on the guard tone.
- other signals can be placed on the guard tone only on the 16 MHz channel.
- the signal to be raised on the guard tone can be used for various applications as follows.
- PAPR Reduction A specific signal can be raised to the guard tone to reduce PAPR. First, the data / pilot tone is mapped according to the conventional method, and then a signal is added to the protection tone which can reduce the PAPR by recognizing the current signal pattern.
- Dummy signal A signal that is literally meaningless. This case has the advantage of being easy to implement.
- iii) Data Copy the data in the middle of the signal and put it on the guard tone.
- the reliability of data transmission may increase.
- it can be used as a data tone like other carriers. In this case, the yield is improved by increasing the number of data tones without copying.
- Pilot It is used for channel estimation by pilot.
- 16 is a block diagram illustrating a configuration of a wireless device according to an embodiment of the present invention.
- the AP 1600 may include a processor 1610, a memory 1620, and a transceiver 1630.
- the STA 1650 may include a processor 1660, a memory 1670, and a transceiver 1680.
- the transceivers 1630 and 1680 may transmit / receive wireless signals and, for example, may implement a physical layer in accordance with the IEEE 802 system.
- the processors 1610 and 1660 may be connected to the transceivers 1630 and 1660 to implement a physical layer and / or a MAC layer according to the IEEE 802 system.
- the processor 1610 may operate to process the various embodiments of the invention described above.
- Embodiments of the present invention described above may be implemented through various means.
- embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.
- a method according to embodiments of the present invention may include one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), and Programmable Logic Devices (PLDs). It may be implemented by field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.
- ASICs Application Specific Integrated Circuits
- DSPs Digital Signal Processors
- DSPDs Digital Signal Processing Devices
- PLDs Programmable Logic Devices
- FPGAs field programmable gate arrays
- processors controllers, microcontrollers, microprocessors, and the like.
- the method according to the embodiments of the present invention may be implemented in the form of a module, a procedure, or a function that performs the functions or operations described above.
- the software code may be stored in a memory unit and driven by a processor.
- the memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
Description
IEEE 802.11ac PHY | IEEE 802.11af PHY | ||
Channel bandwidth | Throughput | Channel bandwidth | Throughput |
20 | 86.7 | 2 | 8.67 |
40 | 200 | 4 | 20 |
80 | 433.3 | 8 | 43.33 |
160 | 866.7 | 16 | 86.67 |
80+80 | 866.6 | 8+8 | 86.66 |
i) 경우 | Channel information in beacon frame on ch.1: Channel number = 5Channel information in beacon frame on ch.2: Channel number = 5 |
ii) 경우 | Channel information in beacon frame on ch.1: Center frequency = f + 6, Bandwidth = 8Channel information in beacon frame on ch.2: Center frequency = f + 6, Bandwidth = 8 |
iii) 경우 | Channel information in beacon frame on ch.1: Low frequency = f + 2, High frequency = f + 10Channel information in beacon frame on ch.2: Low frequency = f + 2, High frequency = f + 10 |
iv) 경우 | Channel information in beacon frame on ch.1: Center frequency offset = + 3, Scaling factor = 2Channel information in beacon frame on ch.2: Center frequency offset = - 3, Scaling factor = 2 |
Claims (14)
- 무선통신시스템에서 단말이 신호를 전송하는 방법에 있어서,상기 단말이 사용하는 채널의 주파수 대역폭 중 일부 주파수 대역에서 소정 시간 구간 동안 다른 단말의 반송파 센싱을 위한 신호를 전송하는 단계;를 포함하며,상기 반송파 센싱을 위한 신호는, 상기 채널의 주파수 대역폭에 대한 정보를 포함하는, 신호 전송 방법.
- 제1항에 있어서,상기 반송파 센싱을 위한 신호는, 상기 단말이 상기 채널의 주파수 대역폭에서 신호를 전송하기 이전에 전송되는, 신호 전송 방법.
- 제1항에 있어서,상기 일부 주파수 대역은, 상기 무선통신시스템에 설정된, 서로 다른 대역폭을 갖는 복수의 채널들이 서로 오버랩되는 주파수 대역에 해당되는, 신호 전송 방법.
- 제1항에 있어서,상기 소정 시간 구간 동안 상기 일부 주파수 대역을 제외한 나머지 주파수 대역에서는 신호 전송이 이루어지지 않는, 신호 전송 방법.
- 제1항에 있어서,상기 반송파 센싱을 위한 신호는, N-STF(Narrowband Short Training Field), N-LTF(Narrowband Long Training Field), N-SIG(Narrowband Signal)를 포함하는, 신호 전송 방법.
- 제1항에 있어서,상기 채널의 주파수 대역폭이, 상기 무선통신시스템의 전체 주파수 대역에서 어느 곳에 위치하는지에 대한 정보는 비콘 프레임에 포함되는, 신호 전송 방법.
- 무선통신시스템에서 단말이 신호를 수신하는 방법에 있어서,상기 무선통신시스템에 설정된 채널의 일부 주파수 대역에서 소정 시간 구간 동안 반송파 센싱을 위한 신호를 수신하는 단계;를 포함하며,상기 반송파 센싱을 위한 신호는, 상기 채널의 주파수 대역폭에 대한 정보를 포함하는, 신호 수신 방법.
- 제7항에 있어서,상기 반송파 센싱을 위한 신호는, 상기 채널의 주파수 대역폭에서 신호를 전송하기 이전에 전송되는 것인, 신호 수신 방법.
- 제7항에 있어서,상기 일부 주파수 대역은, 상기 채널을 포함하여 상기 무선통신시스템에 설정된 서로 다른 대역폭을 갖는 복수의 채널들이 서로 오버랩되는 주파수 대역에 해당되는, 신호 수신 방법.
- 제7항에 있어서,상기 소정 시간 구간 동안 상기 일부 주파수 대역을 제외한 나머지 주파수 대역에서는 신호 전송이 이루어지지 않는 것인, 신호 수신 방법.
- 제7항에 있어서,상기 반송파 센싱을 위한 신호는, N-STF(Narrowband Short Training Field), N-LTF(Narrowband Long Training Field), N-SIG(Narrowband Signal)를 포함하는, 신호 수신 방법.
- 제7항에 있어서,상기 채널의 주파수 대역폭이, 상기 무선통신시스템의 전체 주파수 대역에서 어느 곳에 위치하는지에 대한 정보는 비콘 프레임으로부터 수신되는, 신호 수신 방법.
- 무선통신시스템에서 신호를 전송하는 단말 장치에 있어서,송수신기; 및상기 송수신기를 포함하는 상기 장치를 제어하는 프로세서를 포함하고,상기 프로세서는, 상기 단말이 사용하는 채널의 주파수 대역폭 중 일부 주파수 대역에서 소정 시간 구간 동안 다른 단말의 반송파 센싱을 위한 신호를 전송하며, 상기 반송파 센싱을 신호는 상기 채널의 주파수 대역폭에 대한 정보를 포함하는, 단말 장치.
- 무선통신시스템에서 신호를 수신하는 단말 장치에 있어서,송수신기; 및상기 송수신기를 포함하는 상기 장치를 제어하는 프로세서를 포함하고,상기 프로세서는, 상기 무선통신시스템에 설정된 채널의 일부 주파수 대역에서 소정 시간 구간 동안 반송파 센싱을 위한 신호를 수신하며, 상기 반송파 센싱을 위한 신호는 상기 채널의 주파수 대역폭에 대한 정보를 포함하는, 단말 장치.
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US14/377,534 US9445434B2 (en) | 2012-02-08 | 2013-02-08 | Method and apparatus for transceiving signals in wireless communication systems |
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