WO2017105310A1 - Point d'accès, station et procédés associés de transmissions de formation de faisceau dans un réseau local sans fil - Google Patents

Point d'accès, station et procédés associés de transmissions de formation de faisceau dans un réseau local sans fil Download PDF

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Publication number
WO2017105310A1
WO2017105310A1 PCT/SE2015/051376 SE2015051376W WO2017105310A1 WO 2017105310 A1 WO2017105310 A1 WO 2017105310A1 SE 2015051376 W SE2015051376 W SE 2015051376W WO 2017105310 A1 WO2017105310 A1 WO 2017105310A1
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Prior art keywords
sta
rts
control frame
cts
reception
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PCT/SE2015/051376
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English (en)
Inventor
Meng Wang
Gustav WIKSTRÖM
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Telefonaktiebolaget Lm Ericsson (Publ)
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Priority to PCT/SE2015/051376 priority Critical patent/WO2017105310A1/fr
Publication of WO2017105310A1 publication Critical patent/WO2017105310A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0697—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using spatial multiplexing
    • 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]
    • H04W74/0816—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA] with collision avoidance
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/10—Small scale networks; Flat hierarchical networks
    • H04W84/12—WLAN [Wireless Local Area Networks]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver

Definitions

  • embodiments herein relate to an access point and a method therein for performing a beamforming transmission or reception to or from a station in the WLAN. Also, embodiments herein relate to a station and a method therein for enabling an access point of a WLAN to perform a beamforming transmission or reception to or from the station in the WLAN.
  • a Basic Serving Set In the standardized IEEE 802.1 1 Wireless LAN, WLAN, which commonly also may be referred to as a Wi-Fi network, a Basic Serving Set, BSS, is regarded the basic building block of this wireless communications network.
  • the BSS comprise an Access Point, AP, and a number of stations, STAs, located within a certain coverage area or cell being served by the AP.
  • STAs stations
  • the transmission between the AP and the STAs is typically performed in a distributed manner. This means that before a transmission, a STA may first sense the transmission medium for a specific period of time. If the transmission medium is deemed idle, then access may be assigned to this STA for transmission;
  • the STA typically has to wait a random back-off period and then again check whether the transmission medium is idle and thus available to the STA.
  • the random backoff period provides a collision avoidance mechanism for multiple STAs that wish to transmit in the same BSS.
  • the standardized IEEE 802.1 1 WLAN may thus be seen as one example of a wireless communications network using contention-based transmission resources of the same frequency or channel.
  • Beamforming that allows a transmitting AP in a BSS to focus energy towards a specific STA in order to substantially improve the Signal-to-Noise Ratio, SNR, of the transmission to that specific STA was introduced in IEEE 802.1 1 n standard. This advantageously also has the benefit of reducing the interference to other adjacent BSSs as compared to conventional omni-directional transmission.
  • IEEE 802.1 1 ac-2013 standard only so-called explicit beamforming has been standardized in which the beamforming requires an explicit channel measurement by specific channel sounding frames. The channel sounding frames are then used for channel calibration in order to determine how to radiate energy in the desired direction. This channel sounding procedure is based on Non-Data Packets, NDPs, and is illustrated in the signaling scheme in Fig. 1 .
  • the beamforming transmitter, BF TX first transmits a NDP
  • NDP AF Announcement frame
  • the intended receiver such as, e.g. RX1
  • RX1 will respond to the NDP AF and other receivers, such as, e.g. RX2, will defer channel access in order not to interfere.
  • the BF TX transmits a NDP frame.
  • the NDP frame is equivalent to a regular frame, but with its data part removed.
  • this NDP frame mainly comprises training signals through which the channel may be properly estimated.
  • the RX1 estimates the channel through the training part of the NDP frame and transmits a feedback frame back to the BF TX.
  • the feedback frame may be a Very-High
  • VHT compressed beamforming frame that comprises information on the channel state between the BF TX and RX1 as measured using the NDP.
  • the VHT compressed beamforming frame provides a steering matrix compressed via Givens rotation, which is able to save a significant amount of overhead compared to no- compressed beamforming matrices.
  • the BF TX uses the feedback steering matrix to calculate the weighting matrix for the beamforming towards the RX1 .
  • support for performing a similar type of beamforming transmission to multiple receivers simultaneously has also been included in the IEEE 802.1 1 ac-2013 standard. This may also be referred to as multi-user MIMO beamforming and is illustrated in the signaling scheme in Fig. 2.
  • Fig. 2 the same channel sounding procedure as described above with reference to Fig. 1 is initially performed for a first receiver. Then, for the remaining receivers the feedback frame is triggered in turn by a so-called Beamforming Report Poll, BRP, frame.
  • BRP Beamforming Report Poll
  • OBSS Overlapping Basic Service Sets
  • STAs STAs nearby each other that are operated by different APs.
  • RTS/CTS Request-To-Send/Clear-To-Send
  • the RTS/CTS signalling is illustrated in the signalling scheme in Fig. 3.
  • the transmitter, TX first transmits an RTS frame to the intended receiver
  • the TX may be an AP and the RX may be a STA, or vice versa. All other RXs that are able to hear the RTS frame will in response set their Network Allocation Vector, NAV.
  • the NAV is set based on timing information in the RTS frame, e.g. the duration field ID.
  • the RX then transmits a CTS control frame back to the TX. After the RTS/CTS control frame exchange, the TX starts the transmitting of data to the RX. The RX may then acknowledge the reception of the data in an Acknowledge, ACK, frame.
  • the CTS control frame may also comprise timing information to set the NAV for the other RXs, and all RXs that hear the CTS control frame will set their NAV accordingly.
  • the main purpose of the RTS/CTS control frame exchange is to avoid collisions in a BSS; that is, to avoid multiple data packets at the same time being addressed to the same receiver over the same subcarriers. This may occur in a BSS, for example, if multiple STAs simultaneously transmits to the AP. The AP on the other hand will not transmit to multiple STAs at the same time over the same subcarriers.
  • the existing beamforming based on a channel sounding procedure in a BSS as described above with reference to Figs. 1 -2 is not particularly efficient.
  • One channel sounding procedure for a single STA requires three frames in which two specific frames, i.e.
  • the NDP AF and NDP frames are transmitted and functions only as a pilot signal. It may therefore be anticipated that, in heavily crowded scenarios, the transmission overhead for supporting beamforming to a number of STAs in a WLAN, and its associated latency, will be large. Therefore, a faster beamforming with lower overhead is desirable in WLANs for heavily crowded or latency-sensitive scenarios.
  • the object is achieved by a method performed by an Access Point, AP, of a Wireless Local Area Network, WLAN, for performing a beamforming transmission or reception to or from a station, STA, in the WLAN.
  • the AP transmits information to the STA indicating that the STA is to append a pilot signal in a first Information Element, IE, at the end of Request-To-Send/Clear-To- Send, RTS/CTS, control frames that are to be transmitted to the AP.
  • the AP also receives an RTS or CTS control frame from the STA comprising a pilot signal appended in a first IE at the end of the RTS or CTS control frame.
  • the AP further determines an Angle of Arrival, AoA, of the received RTS or CTS control frame based on the pilot signal appended in the first IE at the end of the received RTS or CTS control frame.
  • the AP performs a beamforming transmission or reception to or from the STA based on the determined AoA of the received RTS or CTS control frame.
  • the object is achieved by an AP of a WLAN for performing a beamforming transmission or reception to or from a STA in the WLAN.
  • the AP is configured to transmit information to the STA indicating that the STA is to append a pilot signal in a first IE at the end of RTS/CTS control frames that are to be transmitted to the AP.
  • the AP is also configured to receive an RTS or CTS control frame from the STA comprising a pilot signal appended in a first IE at the end of the RTS or CTS control frame and transmit the determined information to the STA.
  • the AP is further configured to determine an AoA of the received RTS or CTS control frame based on the pilot signal appended in the first IE at the end of the received RTS or CTS control frame. Furthermore, the AP is configured to perform a beamforming transmission or reception to or from the STA based on the determined AoA of the received RTS or CTS control frame. According to a third aspect of embodiments herein, the object is achieved by a method performed by a STA for enabling an AP of a WLAN to perform a beamforming transmission or reception to or from the STA in the WLAN.
  • the STA receives information from the AP indicating that the STA is to append a pilot signal in a first IE at the end of RTS/CTS control frames that are to be transmitted to the AP. Also, the STA determines that an RTS or CTS control frame is to be transmitted to the AP. Further, the STA transmits the RTS or CTS control frame to the AP comprising a pilot signal appended in a first IE at the end of the RTS/CTS control frame.
  • the object is achieved by a STA for enabling an AP of a WLAN to perform a beamforming transmission or reception to or from the STA in the WLAN.
  • the STA is configured to receive information from the AP indicating that the STA is to append a pilot signal in a first IE at the end of RTS/CTS control frames that are to be transmitted to the AP.
  • the STA is also configured to determine that an RTS or CTS control frame is to be transmitted to the AP.
  • the STA is 5 further configured to transmit the RTS or CTS control frame to the AP comprising a pilot signal appended in a first IE at the end of the RTS/CTS control frame.
  • the object is achieved by a computer program, comprising instructions which, when executed on at least one o processor, cause the at least one processor to carry out the method described above.
  • the object is achieved by a carrier containing the computer program described above, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium. 5
  • Fig. 1 is a signaling scheme illustrating a channel sounding procedure based on0 NDP according to the IEEE 802.1 1 ac-2013 standard
  • Fig. 2 is another signaling scheme illustrating a channel sounding procedure based on NDP according to the IEEE 802.1 1 ac-2013 standard
  • Fig. 3 is a signaling scheme illustrating RTS/CTS signaling
  • Fig. 4 is a schematic block diagram illustrating embodiments of an AP and a STA in a WLAN
  • Fig. 5 is a schematic block diagram illustrating AoA
  • Fig. 6 is a flowchart depicting embodiments of a method in an AP
  • Fig. 7 is a flowchart depicting embodiments of a method in a STA
  • Fig. 8 is a signaling scheme illustrating signaling according to embodiments of an
  • Fig. 9 is a schematic block diagram depicting an RTS frame and a CTS control frame according to embodiments of an AP and a STA,
  • Fig. 10 is a signaling scheme illustrating signaling according to embodiments of an
  • Fig. 1 1 is a schematic block diagram depicting an RTS frame according to
  • Fig. 12 is a schematic block diagram depicting embodiments of an AP
  • Fig. 13 is a schematic block diagram depicting embodiments of a STA.
  • Fig. 4 shows an example of a wireless communications network 100 in which embodiments herein may be implemented.
  • the wireless communications network 100 in Fig. 5 comprise a Wireless Local Area Network, WLAN 135.
  • the WLAN 1 10 may be a WLAN according to the IEEE 802.1 1 standard.
  • the WLAN 135 may comprise one or more Access Points, APs, configured to provide WLAN coverage and serve stations, STAs, located within their respective coverage area or cell.
  • the APs may also be referred to as network nodes.
  • the WLAN 135 comprise an Access Point, AP
  • the AP 1 10 may be configured to provide WLAN coverage and serve stations, STAs, located within their respective, coverage area or cell, respectively, as shown by the dashed areas in Fig. 4.
  • the AP 1 10 may be a network node that forms part of a cellular, o wireless or radio communication system providing radio coverage to the STAs over cellular transmission resources. Examples of such cellular, wireless or radio
  • the AP 1 10 may e.g. be an eNB, eNodeB, or a Home Node B, a Home eNode B, femto Base Station (BS), pico BS or any other network unit capable to serve wireless devices or STAs on cellular transmission resources in the wireless
  • the AP 1 10 may also be e.g. a radio base station, a base0 station controller, a network controller, a relay node, a repeater, a Ultra-Dense
  • the AP 1 10 may be also be a network node that may use contention-based transmission resources of the same frequency, such as, e.g. WLANs.
  • This may also be referred to as the cellular, wireless or5 radio communication system may being configured to operate in parts of the so-called unlicensed spectrum, i.e. unlicensed frequency bands which are shared, decentralized and not licensed to a particular type of scheduled wireless or radio communication, such as, e.g. the frequency bands of WLANs or WiFi-networks.
  • two stations, STAs 121 , 122 are located0 in the cell of the first WLAN 135 and may thus be served by the AP 1 10.
  • the STAs 121 , 122 may e.g. be any kind of stations or wireless devices capable of communication via a WLAN.
  • the STAs 121 , 122 may be mobile phones, cellular phones,
  • PDAs Personal Digital Assistants
  • smart phones tablets, sensors or actuators with wireless communication capabilities, sensors or actuators connected to or equipped with5 wireless devices, Machine Devices (MDs), Machine-Type-Communication (MTC) devices, Machine-to-Machine (M2M) communication devices, wireless devices with D2D capability, Customer-Premises Equipments (CPEs), Laptop-Mounted Equipments (LMEs), Laptop- Embedded Equipments (LEEs), etc.
  • CPEs Customer-Premises Equipments
  • LMEs Laptop-Mounted Equipments
  • LEEs Laptop- Embedded Equipments
  • BSS Basic Service Set
  • AoA Angle of Arrival
  • DoA Direction of Arrival
  • Fig. 5 shows a schematic block diagram illustrating the principle of AoA.
  • AP 1 10 equipped with an antenna array may measure the incoming propagation direction of the signal from a STA 121 , i.e. the AoA of the transmission.
  • the AP 1 10 may then adopt various signal processing algorithms, such as, e.g. MUSIC or ESPRIT, etc., for performing the AoA estimation. These signal processing algorithms will not be described
  • Fig. 6 illustrates an example of actions or operations which may be taken by the AP 1 10 as shown in Fig. 4.
  • the method may comprise the following actions.
  • the AP 1 10 transmits information to the STA 121 indicating that the STA 121 is to append a pilot signal in a first Information Element, IE, at the end of Request-To- Send/Clear-To-Send, RTS/CTS, control frames that are to be transmitted to the AP 1 10.
  • IE first Information Element
  • the AP 1 10 may trigger, or prepare for, a modified RTS/CTS exchange with the STA 121 for the additional purpose of performing an AoA estimation to be used in
  • RTS/CTS exchange with the STA 121 will also reserve the channel for the upcoming beamforming transmission from the AP 1 10 to the STA 121 and subsequent ACK frame from the STA 121 to the AP 1 10.
  • the AP 1 10 may transmit an RTS control frame to the STA
  • a second IE is appended at the end of the RTS control frame and wherein the second IE comprises information indicating to the STA 121 to append the pilot signal in the first IE at the end of a corresponding CTS control frame.
  • the RTS control frame comprising the first IE is no different than compared to a conventional RTS control frame.
  • One example of this embodiment is shown in the signaling scheme in Figs. 8-9 described in more detail below.
  • the RTS control frame may be transmitted to the STA 121 when no uplink frame has been received from the STA 121 for a duration of a determined measurement time period and when there is a scheduled data transmission from the AP 1 10 to the STA 121 . Since an AoA estimation may be performed by the AP 1 10 based on any uplink frame, such as, e.g. data frames, ACK frames, RTS frames, or CTS control
  • the AP 1 10 may prefer not to send the RTS control frame with the second IE to the STA 121 in case it has recently, i.e. for the duration of a determined measurement time period, received an uplink frame from the STA 121 . Additionally, in case there is no data transmission scheduled in the AP 1 10, the AP 1 10 may prefer not to send the RTS control frame with the second IE to the STA 121 just in order to enable possible upcoming
  • the AP 121 may transmit configuration information to the STA 121 indicating that the STA 121 is to append the pilot signal in the first IE at the end of a RTS or CTS control frame that is to be transmitted to the AP 1 10.
  • the configuration information may be transmitted as part of an attach procedure between the AP 1 10 and the STA 121 .
  • the AP 1 10 may pre-configure the STA 121 to append a pilot signal in a first IE at the end of RTS/CTS control frames that are to be transmitted to the AP 1 10.
  • the AP 1 10 may prepare the STA 121 to enable beamforming reception in the AP 1 10 of data transmitted from the STA 121 .
  • One example of this embodiment is shown in the signaling scheme in Figs. 10-11 described in more detail below.
  • the AP 1 10 receives an RTS or CTS control frame from the STA 121 comprising a pilot signal appended in a first IE at the end of the RTS or CTS control frame.
  • the AP 121 may receive a modified CTS control frame with more pilot symbols for AoA estimation comprised in the first IE at the end of the modified CTS control frame.
  • the AP 1 10 may also receive a modified RTS frame with more pilot symbols for AoA estimation comprised in the first IE at the end of the modified RTS frame.
  • the pilot symbols is the content of the pilot signal.
  • this enables the AP 101 to perform a beamforming transmission or reception, i.e. as described in Action 603-604, based on signalling wherein the channel sounding overhead is reduced for the beamforming transmission in the WLAN. For example, instead of requiring three explicit messages, such as, e.g.
  • the implicit channel sounding procedure described in Actions 601 -604 herein requires only two messages in order to enable beamforming transmissions to the STA 121 .
  • the AP 1 10 After receiving the RTS or CTS control frame as described in Action 602, the AP 1 10 determines an Angle of Arrival, AoA, of the received RTS or CTS control frame based on the pilot signal appended in the first IE at the end of the received RTS or CTS control frame. This advantageously allows the AP 1 10 to determine an improved AoA estimation since the pilot signal appended in the first IE will provide more pilot symbols for the AP 1 10 to perform the AoA estimation on as compared to, for example, using a regular uplink frame. Action 604
  • the AP 1 10 After the determination as described in Action 603, the AP 1 10 performs a beamforming transmission or reception to or from the STA 121 based on the determined AoA of the received RTS or CTS control frame. In other words, this means that relying on an AoA estimation in the uplink, the AP 1 10 may extract a weighting vector in order to steer its antennas to transmit data to the STA 121 . For example, with an estimated AoA 8, beamforming is made possible by applying complex weight to individual transmit antennas as:
  • This weighting vector, or its variant, the beamforming matrix may be calculated by the AP 1 10 as a function of the AoA estimate. This calculation may be performed by the AP 1 10 online, or alternatively, by a look-up table in the AP 1 10 that is calculated offline and stored in a memory or database in or connected to the AP 1 10.
  • the AP 1 10 may skip this and simply read the beamforming matrix from a memory or database in or connected to the AP 1 10.
  • a precoder codebook may be available to the AP 1 10, and according to the calculated beamforming matrix, an optimal precoder may be selected by the AP 1 10 and stored in the memory or database instead of the beamforming matrix itself.
  • the algorithms for calculating 3 ⁇ 4 are out of the scope of the embodiments described herein.
  • the implicit channel sounding procedure described in Actions 601 -604 above may be extended to MU-MIMO.
  • the AP 1 10 may periodically update the channel sounding information for all STAs potential for MU- MIMO based on their corresponding uplink frames. For example, in case the AP 1 10 is 5 missing or has outdated channel sounding information from the STA 121 in order to
  • the implicit channel sounding procedure described in Actions 601 -604 may be performed by the AP 1 10 prior to performing MU- MIMO beamforming transmissions. It should also be noted that, the implicit sounding procedure described in Actions 601 -604 may not be necessary for each STA or for every o MU-MIMO beamforming transmission. Hence, the overhead of the signalling for enabling the MU-MIMO beamforming transmissions may be substantially lower than the existing mechanism of using NDP and BRP frames in order to enable MU-MIMO beamforming transmissions.
  • per-SNR information may be 5 required for calculating the beamforming matrix.
  • the SNR information may also be a measurement on an uplink frame, e.g. a Received Signal Strength Indicator, RSSI, measurement or similar.
  • the AP 1 10 may switch to performing beamforming
  • Non-Data Packet NDP
  • transmissions according to the IEEE 802.1 1 ac-2013 standard based on a determined threshold value for a signal quality measurement of the beamforming transmission or reception to or from the STA 121 that is performed based on the determined AoA of the RTS/CTS control frame from the STA 121 .
  • This allows the AP 1 10 to switch between the5 channel sounding procedures, e.g. between using the implicit channel sounding
  • the signal quality measurement may be the variation in the determined AoA from the RTS/CTS control frame from the STA 121 determined by the AP 1 10 for a determined period of time.
  • the AP 1 105 may switch from the implicit channel sounding procedure as described in Actions 601 -604 above to the explicit channel sounding procedure using NDP transmissions according to the IEEE 802.1 1 ac-2013 standard as described in Figs. 1 -2, when the estimated AoA has a time variation that is above a determined threshold value which may indicate that the implicit channel sounding procedure as described in Actions 601 -604 above is currently 5 not performing well.
  • the signal quality measurement is the difference between a Signal-to-Noise-Ratio or Packet Error Rate, SNR/PER, when the beamforming transmission or reception to or from the STA 121 is performed based on the determined o AoA of the RTS/CTS control frame from the STA 121 and a SNR/PER for a non- beamformed transmission or reception to or from the STA 121 is performed.
  • SNR/PER Signal-to-Noise-Ratio or Packet Error Rate
  • the non-beamformed transmission or reception to or from the STA 121 may, for example, be the RTS/CTS transmission or reception itself.
  • the signal quality measurement may be the difference between a SNR/PER when the beamforming transmission or reception to or from the STA 121 is performed based on the determined AoA of the RTS/CTS control frame from the STA 121 and a SNR/PER when the beamforming transmission or reception to or from the STA 121 is performed based on NDP transmissions according to5 the IEEE 802.1 1 ac-2013 standard.
  • This may, for example, be performed in case when a SNR/PER for performing the beamforming transmission or reception to or from the STA 121 based on NDP transmissions according to the IEEE 802.1 1 ac-2013 standard is known in the AP 1 10.
  • the AP 1 10 may also in this case switch from the implicit channel sounding procedure as described in Actions 601 -604 above to the explicit
  • the AP 1 10 may also receive a request to fall back to the5 explicit channel sounding procedure using NDP transmissions according to the IEEE 802.1 1 ac-2013 standard as described in Figs. 1 -2 from the STA 121 .
  • the request to fall back may be received by the AP 1 10 in a transmitted RTS frame from the STA 121 .
  • the request to fall back may be received by the AP 1 10 in a transmitted RTS frame from the STA 121 .
  • the AP 1 10 may receive a RTS frame from the STA 121 in which an additional IE or field has been be added which explicitly indicate the preferred channel sounding procedure by STA 121 .
  • Fig. 7 illustrates an example of actions or operations which may be taken by the STA 121 as shown in Fig. 4.
  • the method may comprise the following actions.
  • the STA 12 receives information from the AP 1 10 indicating that the STA 121 is to append a pilot signal in a first IE at the end of RTS/CTS control frames that are to be transmitted to the AP 1 10.
  • the STA 121 may receive an RTS control frame from the AP 1 10 wherein a second IE is appended at the end of the RTS control frame and wherein the second IE comprises information indicating to the STA 121 to append the pilot signal in the first IE at the end of a corresponding CTS control frame.
  • a second IE is appended at the end of the RTS control frame and wherein the second IE comprises information indicating to the STA 121 to append the pilot signal in the first IE at the end of a corresponding CTS control frame.
  • the STA 12 may receive configuration information from the AP 1 10 indicating that the STA 121 is to append the pilot signal in the first IE at the end of a RTS or CTS control frame that is to be transmitted to the AP 1 10.
  • the configuration information may be received as part of an attach procedure between the AP 1 10 and the STA 121 . This means that the STA 121 may be
  • the STA 121 determines that an RTS or CTS control frame is to be transmitted to the AP 1 10. In some embodiments, the STA 121 may determine that an RTS control frame is to be transmitted to the AP 1 10 when 5 there is a scheduled data transmission to the AP 1 10 in the STA 121 .
  • the STA 121 transmits the RTS or CTS control frame to the AP 1 10 comprising a pilot signal appended in a first IE at the end of
  • the STA 121 may occur once the STA 121 receives a CTS control frame from the AP 1 10 in response to the transmitted RTS control frame. It should be noted, however, that in this case the CTS frame from the AP 1 10 has no function for the beamforming.
  • the STA 121 may also request to fall back to the explicit channel sounding procedure using NDP transmissions according to the IEEE 802.1 1 ac-
  • Figs. 1 -2 20 2013 standard as described in Figs. 1 -2.
  • This may, for example, be performed when the SNR/SINR or PER that the STA 121 experience by using the implicit sounding procedure based on AoA estimation described in Actions 601 -604 is not significantly improved during beamforming transmission.
  • the STA 121 may, for example, request to fall back by indicating this in a transmitted RTS frame.
  • 25 IE or field may be added to the RTS frame in order to explicitly indicate the preferred
  • Fig. 8 shows a signaling scheme illustrating signaling according to embodiments of the AP 1 10 and the STA 121 .
  • the AP 1 10 then performs a beamforming transmission of data to the STA 121 .
  • the STA 121 responds by sending an ACK when the transmitted data has been received.
  • Fig. 9 shows a schematic block diagram depicting an RTS frame and a CTS control frame according to embodiments of the AP 1 10 and the STA 121 .
  • the AP 1 10 and the STA 121 show a schematic block diagram depicting an RTS frame and a CTS control frame according to embodiments of the AP 1 10 and the STA 121 .
  • 5 second IE 801 appended in the RTS control frame is denoted as Sounding Indication.
  • the first IE 802 appended at the end of the corresponding CTS control frame, e.g. in the signaling scheme in Fig. 8, is denoted as Pilot.
  • the duration IE or field which comprise a time value indicating the 1 0 duration for which the medium will be busy, will here be configured to cover the
  • Fig. 10 is a signaling scheme illustrating signaling according to embodiments of 1 5 the AP 1 10 and the STA 121 .
  • the STA 121 has been preconfigured by the AP 1 10 by receiving configuration information indicating that the STA 121 is to append the pilot signal in the first IE at the end of a RTS control frame that is to be transmitted to the AP 1 10.
  • the STA 121 determines that an RTS control frame is to be transmitted to the AP 1 10, e.g. when having data to transmit to the AP 1 10
  • the STA 20 121 transmit an RTS control frame in which a pilot signal is appended in a first IE 1001 at the end of the RTS control frame.
  • the AP 1 10 may here respond with a conventional CTS control frame. Upon receiving the conventional CTS frame, the STA 121 may transmit the data to the AP 1 10. By having receiving the pilot signals in the first IE 1001 in the RTS control frame earlier which the AP 1 10 may use for the AoA estimation, the AP 1 10 may 25 perform a beamforming reception of the data transmitted from the STA 1 10.
  • Fig. 11 is a schematic block diagram depicting an RTS frame according to embodiments of the AP 1 10 and the STA 121 .
  • the first IE 1001 appended at the end of the RTS control frame comprising pilot signal is denoted as Pilot.
  • the AP 1 10 may comprise the following arrangement depicted in Fig. 12.
  • Fig. 12 shows a schematic block diagram of
  • the AP 1 10 may comprise a processing circuitry 1210, a memory 1220 and at least one antenna (not shown).
  • the AP 1 10 may also comprise a receiving module 1211 and a transmitting module 1212.
  • the receiving module 121 1 and the transmitting module 1212 may comprise Radio Frequency, RF, circuitry and baseband processing circuitry.
  • the receiving module 121 1 and the transmitting module 1212 may also be co- located, such as, in a transceiver, and may also be said to form part of the processing circuitry 1210.
  • some or all of the functionality described above as being performed by the AP 1 10 may be provided by the processing circuitry 1210 executing instructions stored on a computer-readable medium, such as, e.g. the memory 1220 shown in Fig. 12.
  • Alternative embodiments of the AP 1 10 may comprise additional components, such as, a determining module 1213, a performing module 1214, and a switching module 1215, responsible for providing its functionality necessary to support the embodiments described herein.
  • the AP 1 10 or processing circuitry 1210 is configured to, or may comprise the transmitting module 1212 configured to, transmit information to the STA 121 indicating that the STA 121 is to append a pilot signal in a first IE at the end of RTS/CTS control frames that are to be transmitted to the AP 1 10. Also, the AP 1 10 or processing circuitry 1210 is configured to, or may comprise the receiving module 121 1 configured to, receive an RTS or CTS control frame from the STA 121 comprising a pilot signal appended in a first IE at the end of the RTS or CTS control frame and transmit the determined information to the STA 121 .
  • the AP 1 10 or processing circuitry 1210 is configured to, or may comprise the determining module 1213 configured to, determine an AoA of the received RTS or CTS control frame based on the pilot signal appended in the first IE at the end of the received RTS or CTS control frame. Furthermore, the AP 1 10 or processing circuitry 1210 is configured to, or may comprise the performing module 1214 configured to, perform a beamforming transmission or reception to or from the STA 121 based on the determined AoA of the received RTS or CTS control frame.
  • the AP 1 10 or processing circuitry 1210 may be configured to, or may comprise the transmitting module 1212 configured to, transmit an RTS control frame to the STA 121 , wherein a second IE is appended at the end of the RTS control frame and wherein the second IE comprises information indicating to the STA 121 to append the pilot signal in the first IE at the end of a corresponding CTS control frame.
  • the AP 1 10 or processing circuitry 1210 may be configured to, or may comprise the transmitting module 1212 configured to, transmit the RTS control frame to the STA 121 when no uplink frame has been received from the STA 121 for a duration of a determined measurement period, and when there is a scheduled data transmission from the AP 1 10 to the STA 121 .
  • the AP 1 10 or processing circuitry 1210 may be configured to, or may comprise the transmitting module 1212 configured to, transmit configuration information to the STA 121 indicating that the STA 121 is to append the pilot signal in the first IE at the end of a RTS or CTS control frame that is to be transmitted to the AP 1 10.
  • the AP 1 10 or processing circuitry 1210 may be configured to, or may comprise the transmitting module 1212 configured to, transmit the configuration information as part of an attach procedure between the AP 1 10 and the STA 121 .
  • the AP 1 10 or processing circuitry 1210 may be configured to, or may comprise the switching module 1215 configured to, switch to performing beamforming transmission or reception to or from the STA 121 based on NDP
  • the signal quality measurement may be the variation in the AoA of the RTS/CTS control frame from the STA 121 determined by the AP 1 10 for a determined period of time.
  • the signal quality measurement may be the difference between a SNR/PER when the beamforming transmission or reception to or from the STA 121 is performed based on the determined AoA of the RTS/CTS control frame from the STA 121 and a SNR/PER for a non-beamformed transmission or reception to or from the STA 121 is performed.
  • the signal quality measurement may be the difference between a SNR/PER when the beamforming transmission or reception to or from the STA 121 is performed based on the determined AoA of the RTS/CTS control frame from the STA 121 and a SNR/PER when the beamforming transmission or reception to or from the STA 121 is performed based on NDP transmissions according to the IEEE 802.1 1 ac-2013 standard.
  • the AP 1 10 or processing circuitry 1210 may be configured to, or may comprise the receiving module 121 1 configured to, receive a request to fall back to the explicit channel sounding procedure using NDP transmissions according to the IEEE 802.1 1 ac-2013 standard as described in Figs. 1 -2 from the STA 121 .
  • the AP 1 10 or processing circuitry 1210 may be configured to, or may comprise the receiving module 121 1 configured to, receive the request to fall back in a transmitted RTS frame from the STA 121 .
  • the AP 1 10 or processing 5 circuitry 1210 may be configured to, or may comprise the receiving module 121 1
  • transmission or reception to or from a STA 121 in the WLAN 135 described above may be implemented through one or more processors, such as, the processing circuitry 1210 in the AP 1 10 depicted in Fig. 12, together with computer program code for performing the functions and actions of the embodiments herein.
  • processors such as, the processing circuitry 1210 in the AP 1 10 depicted in Fig. 12, together with computer program code for performing the functions and actions of the embodiments herein.
  • 1 5 may also be provided as a computer program product, for instance in the form of a data carrier, such as, e.g. an electronic signal, optical signal, radio signal, or computer- readable storage medium, carrying computer program code or code means for performing the embodiments herein when being loaded into the processing circuitry 1210 in the AP 1 10.
  • the computer program code may e.g. be provided as pure program code in the AP
  • processing circuitry 1210 and the memory 1220 described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in a memory, that when executed by the one or more processors such as the
  • processing circuitry 1220 perform as described above.
  • processors, as well as the other digital hardware may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).
  • ASIC application-specific integrated circuit
  • SoC system-on-a-chip
  • modules of the AP 1 10 may in some embodiments be implemented as computer programs stored in memories, e.g. in the memory module 1220 in Fig. 12, for execution by processors, e.g. the processing module 1210 of Fig. 12.
  • the STA 121 may comprise the following arrangement depicted in Fig. 13.
  • Fig. 13 shows a schematic block diagram of embodiments of the STA 121 .
  • the embodiments of the STA 121 described herein may be considered as independent embodiments or may be considered in any combination with each other to describe non-limiting examples of the 5 example embodiments described herein.
  • the STA 121 may comprise a processing circuitry 1310, a memory 1320 and at least one antenna (not shown).
  • the STA 121 may also comprise a receiving module 1311 and a transmitting module 1312.
  • the receiving module 131 1 and the transmitting module 1312 may comprise Radio Frequency, RF, circuitry and baseband processing
  • the receiving module 131 1 and the transmitting module 1312 may also be co- located, such as, in a transceiver, and may also be said to form part of the processing circuitry 1310.
  • some or all of the functionality described above as being performed by the STA 121 may be provided by the processing circuitry 1310 executing instructions stored on a computer-readable medium, such as, e.g. the memory
  • Alternative embodiments of the STA 121 may comprise additional components, such as, the determining module 1313 responsible for providing its functionality necessary to support the embodiments described herein.
  • the STA 121 or processing circuitry 1310 is configured to, or may comprise the receiving module 131 1 configured to, receive information from the AP 1 10 indicating that
  • the STA 121 is to append a pilot signal in a first IE at the end of RTS/CTS control frames that are to be transmitted to the AP 1 10.
  • the STA 121 or processing circuitry 1310 is configured to, or may comprise the determining module 1313 configured to, determine that an RTS or CTS control frame is to be transmitted to the AP 1 10.
  • the STA 121 or processing circuitry 1310 is configured to, or may comprise the transmitting module
  • 25 1312 configured to, transmit the RTS or CTS control frame to the AP 1 10 comprising a pilot signal appended in a first IE at the end of the RTS/CTS control frame.
  • the STA 121 or processing circuitry 1310 may be configured to, or may comprise the receiving module 131 1 configured to, receive an RTS control frame from the AP 1 10 wherein a second IE is appended at the end of the RTS
  • the second IE comprises information indicating to the STA 121 to append the pilot signal in the first IE at the end of a corresponding CTS control frame.
  • the STA 121 or processing circuitry 1310 may be configured to, or may comprise the receiving module 131 1 configured to, receive configuration information from the AP 1 10 indicating that the STA 121 is to append the pilot signal in the first IE at the
  • the STA 121 or processing circuitry 1310 may be configured to, or may comprise the receiving module 131 1 configured to, receive the configuration information as part of an attach procedure between the AP 1 10 and the STA 121 .
  • the STA 121 or processing circuitry 1310 may be
  • determining module 1313 configured to, determine that an RTS control frame is to be transmitted to the AP 1 10 when there is a scheduled data transmission to the AP 1 10 in the STA 121 .
  • the STA 121 or processing circuitry 1310 may be
  • the STA 121 or processing circuitry 1310 may be configured to, or may comprise the transmitting module 1312 configured to, indicating this in a transmitted RTS frame.
  • processing circuitry 1310 may be configured to, or may comprise the transmitting module 1312 configured to, add an additional IE or field to the RTS frame in order to explicitly indicate the preferred channel sounding procedure.
  • the embodiments of the STA 121 for enabling an AP 1 10 of a WLAN 20 135 to perform a beamforming transmission or reception to or from the STA 121 in the WLAN 135 described above may be implemented through one or more processors, such as, the processing circuitry 1310 in the STA 121 depicted in Fig. 13, together with computer program code for performing the functions and actions of the embodiments herein.
  • the program code mentioned above may also be provided as a computer program 25 product, for instance in the form of a data carrier, such as, e.g. an electronic signal, optical signal, radio signal, or computer-readable storage medium, carrying computer program code or code means for performing the embodiments herein when being loaded into the processing circuitry 1310 in the STA 121 .
  • the computer program code may e.g. be provided as pure program code in the STA 121 or on a server and downloaded to the STA 30 121 .
  • processing circuitry 1310 and the memory 1320 described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in a memory, that when executed by the one or more processors such as the
  • processing circuitry 1320 perform as described above.
  • processors, as well as the other digital hardware may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC).
  • ASIC application-specific integrated circuit
  • SoC system-on-a-chip
  • modules of the STA 121 may in some embodiments be implemented as computer programs stored in memories, e.g. in the memory module 1320 in Fig. 13, for execution by processors, e.g. the processing modules 1310 of Fig. 13.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

Des modes de réalisation de l'invention concernent un procédé réalisé par un point d'accès (AP) (110) d'un réseau local sans fil (WLAN) (135) pour effectuer une transmission ou une réception de formation de faisceau d'une station (STA) (121) dans le WLAN (135). L'AP (110) transmet des informations à la STA (121) indiquant que la STA (121) doit ajouter un signal pilote dans un premier élément d'information (IE) à la fin de trames de commande de RTS/CTS (demande pour émettre/prêt à émettre) qui doivent être transmises à l'AP (110). L'AP (110) reçoit une trame de commande de RTS ou de CTS de la STA (121) comprenant un signal pilote ajouté à un premier IE à la fin de la trame de commande de RTS ou de CTS. L'AP (110) détermine aussi un angle d'arrivée (AoA) de la trame de commande de RTS ou de CTS reçue en fonction du signal pilote ajouté dans le premier IE à la fin de la trame de commande de RTS ou de CTS reçue. De plus, l'AP (110) effectue une transmission ou une réception de formation de faisceau vers la STA (121) ou une réception de formation de faisceau provenant de celle-ci en fonction de l'AoA de la trame de commande de RTS ou de CTS reçue. L'invention concerne aussi des modes de réalisation de l'AP (110). Des modes de réalisation de l'invention concernent également un procédé réalisé par une STA (121) permettant à un AP (110) d'un WLAN (135) d'effectuer une transmission de formation de faisceau à la STA (121) ou une réception de formation de faisceau provenant de celle-ci dans le WLAN (135), et des modes de réalisation de la STA (121).
PCT/SE2015/051376 2015-12-18 2015-12-18 Point d'accès, station et procédés associés de transmissions de formation de faisceau dans un réseau local sans fil WO2017105310A1 (fr)

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EP4101184A4 (fr) * 2020-02-06 2024-03-06 Deeyook Location Tech Ltd Collecte anonyme de transmissions directionnelles

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Publication number Priority date Publication date Assignee Title
EP3534665A1 (fr) * 2018-03-01 2019-09-04 Apple Inc. Conception de demande pour émettre (rts)/prêt à émettre (cts) en 5g
CN110225548A (zh) * 2018-03-01 2019-09-10 苹果公司 在5g中请求发送(rts)/清除发送(cts)设计
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CN110225548B (zh) * 2018-03-01 2022-09-06 苹果公司 在5g中请求发送(rts)/清除发送(cts)设计
EP4101184A4 (fr) * 2020-02-06 2024-03-06 Deeyook Location Tech Ltd Collecte anonyme de transmissions directionnelles

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