JP2011517392A - Apparatus and method for performing a beam tracking process - Google Patents

Abstract

A beam tracking method for a wireless communication network capable of minimizing the amount of hardware and information necessary for beam search and tracking and reducing channel time usage.
In the method, a transmitting station emits a beam pattern including a respective beam pattern index toward a receiving station, and after the radiation of the beam pattern is completed, the beam pattern is transmitted for a predetermined channel time. Are received from each receiving station. Beam pattern feedback is processed using a simple code. Furthermore, in unidirectional beam tracking, tracking can be performed at once on multiple beam links, and sub-channels that can be used for beam tracking and search are assigned to each station so that multiple stations can search simultaneously. To do.
[Selection] Figure 25

Description

  The present invention relates to a method and apparatus for allocating a beam search time necessary for wireless transmission having high directivity for efficient beam search and tracking.

  In a multiple-input multiple-output (MIMO) communication system, a transmitter uses a plurality of transmission antennas and a receiver uses a plurality of reception antennas for data transmission. One MIMO channel formed by the transmission / reception antenna can be decomposed into a plurality of independent channels. Each independent channel is one subchannel (or transmission channel) in the spatial area of the MIMO channel and occupies one scope. A MIMO system can provide improved performance (eg, improved transmission capacity) when additional regions created by multiple antennas are utilized.

  There are two types of MIMO systems: open-loop and closed-loop technologies. In an open loop system, a MIMO transmitter cannot have any prior knowledge of channel conditions, so generally space-time coding techniques are implemented in the MIMO transmitter to avoid channel fading. Achieve resistance. On the other hand, in a closed loop system, channel state information (CSI) can be fed back from the receiver to the transmitter. The transmitter then performs a pre-processing operation based on the channel state information, so that a simple receiver design and better performance can be achieved. Such a technique is called a beamforming technique and provides better performance gain in the desired receiver direction and suppresses transmission power in other directions.

  As the number of wireless communication devices participating in the wireless network increases, the possibility of occurrence of problems such as collision and loss becomes even greater. Such a collision requires a retransmission that has a fatal adverse effect on the throughput of the wireless network. In particular, when better QoS (Quality of Service) is required, such as Audio / Video data (AV data), it is extremely possible to secure a larger effective bandwidth by reducing the number of retransmissions. It is an important issue.

  Furthermore, considering the growing need for wireless transmission of high-quality video such as DVD (Digital Video Disk) video and HDTV (High Definition Television) video between various home stations, a wide bandwidth is required. There is a need for technical standards for continuous transmission and reception of high quality video.

  Currently, one task group of IEEE 802.15.3c is promoting a technical standard for transmitting a large amount of data in a wireless home network. This standard, called Millimeter Wave (mmWave), uses radio waves having a physical wavelength length of millimeters (ie, radio waves having a frequency of 30 GHz to 300 GHz) for mass data transmission. . Conventionally, such a frequency band has been used as an unlicensed band in a limited manner for applications such as communication carriers, radio astronomy, or car collision prevention.

  IEEE 802.11b and IEEE 802.11g have a carrier frequency of 2.4 GHz and a channel bandwidth of about 20 MHz. IEEE 802.11a and IEEE 802.11n have a carrier frequency of 5 GHz and a channel bandwidth of about 20 MHz. In contrast, mmWave has a channel bandwidth of approximately 0.5 to 2.5 GHz using a carrier frequency of 60 GHz. Therefore, mmWave has a much higher carrier frequency and channel bandwidth than the existing IEEE 802.11 family of standards.

  In this way, if a high-frequency signal having a wavelength in millimeters is used, a very high transmission rate in units of several gigabits (Gbps) can be shown, and the antenna size can be reduced to 1.5 mm or less. Thereby, a single chip including the antenna can be realized. Also, since the attenuation ratio in the air is very high, it is possible to reduce interference between stations.

  However, when mmWave is used, the beam reaching distance is shortened due to the high attenuation rate as described above, so that it is difficult to send a signal in all directions. In order to solve such problems, the beam should be sharpened. However, when the beam is sharp, it is transmitted only to the local area.

  On the other hand, since the beam distance is short due to the high attenuation factor and the straightness of the signal is high, there may be a problem that communication is difficult to perform in a non-line-of-sight environment. In order to solve the former problem, mmWave uses an array antenna having a high gain, and beam steering is used to solve the latter problem.

  When transmission loss is large and transmission power is limited, it is necessary to obtain a desired antenna gain using antenna technology in order to ensure a desired transmission distance. At this time, a method for establishing and maintaining the beam link is required.

  In general, a beam link is formed when a transmitting station emits a beam in all directions and a receiving station feeds back information indicating an available beam among the beams to the transmitting station. After the link is formed, the beam search is repeated to reflect channel variations. This procedure is called tracking. Channel time is used for such tracking and searching. However, when the number of beam links in a network increases, the time required to perform beam search and tracking increases. Therefore, there is a need for a method that performs such a process as simply and efficiently as possible.

  An object of the present invention is to provide a beam tracking method capable of minimizing the amount of hardware and information necessary for beam search and tracking, and adaptively scheduling channel time to reduce channel time usage.

  To achieve the objectives of the present invention, an apparatus for controlling a beam tracking process is disclosed. The apparatus transmits data to at least one of an external station and a coordinator, and receives a data from at least one of the external station and the coordinator, and at least one first beam pattern. A controller that controls the communication module to transmit to one station and controls the communication module to receive a feedback index from at least one station during a predetermined duration. . At this time, each of the first beam patterns is identified by a beam pattern index, and the feedback index identifies one beam pattern selected by the at least one station in the first beam pattern.

  Preferably, the first status information includes mobility information of the receiver station, link status information, and antenna angular information.

  Preferably, the second status information includes quality of service (QoS) information, mobility information, channel status information, and antenna angle information of the transmitter station.

  To serve the purpose of the present invention, an apparatus for performing a beam tracking process is disclosed. The apparatus transmits data to at least one of the external station and the coordinator, and allocates a communication module for receiving data from at least one of the external station and the coordinator, and a channel time for performing the beam tracking process. Controlling the communication module to transmit a request message requesting that the request, and controlling the communication module to receive channel allocating information corresponding to the request message, based on the channel allocation information And a controller for controlling to execute the beam tracking process using a beam pattern index.

  Preferably, the channel allocation information includes starting information, duration information, and channel number information.

  At this time, the start information indicates a start point of the allocated channel time, the section information indicates a duration of the allocated channel time, and the channel number information indicates an identification for identifying a subchannel. . The subchannel is divided by a frequency band during the allocated channel time.

  To serve the purpose of the present invention, an apparatus for controlling a beam tracking process is disclosed. The apparatus transmits data to at least one of the external station and the coordinator, and transmits a first beam pattern to the communication module that receives data from at least one of the external station and the coordinator. The communication module is controlled so that each of the first beam patterns is identified by a beam pattern index, and the communication module is controlled to receive a feedback index during a predetermined period from the at least one station. However, the feedback index includes a controller that indicates one beam pattern selected by the at least one station in the first beam pattern.

  Preferably, the beam pattern index and the feedback index are generated using a barker code.

  Preferably, the predetermined section includes a plurality of subchannels, and the subchannels are divided by other frequency bands at the same time, and the feedback index of the at least one station is transmitted through the subchannels. Received.

  To achieve the objectives of the present invention, a method for performing a beam tracking process at a transmitter station is disclosed. The method includes receiving from a receiver station first state information associated with a state of a receiving station, second state information associated with a state of a transmitting station, and a beam tracking process based on the first state information. Determining the period, and performing the beam tracking process for each determined period.

  At this time, the period is a time interval between the current beam tracking process and the next beam tracking process.

  Preferably, the first state information is received periodically.

  Preferably, the first state information includes mobility information, link state information, and antenna angle information for the receiving station.

  Preferably, the second state information includes quality of service (QoS) information, mobility information, channel state information, and antenna angle information for the transmitting station.

  Preferably, in the determining step, the antenna angle information included in the first and second state information is greater than a predetermined value of at least one antenna angle in the transmitting station and the receiving station. In the case of instructing, the method further includes a control step of controlling the beam tracking processor to reduce the period.

  Preferably, the determining step may reduce the period of the beam tracking process when the QoS information included in the second state information indicates that the QoS of the transmitting station is higher than a predetermined level. A control step for controlling is further included.

  Preferably, the determining step includes the case where the mobility information included in the first and second state information is higher than a state in which at least one mobility is predetermined in the transmitting station and the receiving station. And a control step of controlling the period of the beam tracking process to be reduced.

  Preferably, the determining step includes a control step of controlling so that a period of the beam tracking process is reduced when the channel state information included in the second state information indicates an idle state of the transmitting station. In addition.

  Preferably, the antenna angle information included in the first and second state information is determined from a radio layer management element (RLME) connected to an antenna analog layer.

  To achieve the objectives of the present invention, a method for performing a beam tracking process at a station is disclosed. The method includes a transmission step of transmitting a request message requesting to allocate a channel time for performing a beam tracking process to a coordinator, and channel allocating information corresponding to the request message from the coordinator. And a performing step of performing the beam tracking process using a beam pattern index based on the channel assignment information.

  Preferably, the channel assignment information includes start information, section information, and channel number information.

  At this time, the start information indicates a start point of the allocated channel time, the section information indicates a duration of the allocated time, and the channel number information indicates an identifier for identifying a subchannel. A subchannel is divided by a frequency band during the allocated channel time.

  Preferably, the request message includes at least one of destination information, type information, duration information, and period information.

  At this time, the destination information indicates a target station of the beam tracking process, the type information indicates a direction of the beam tracking process, and the section information indicates a duration of the beam tracking process. A duration is indicated, and the period information indicates a period of the beam tracking process.

  Preferably, the channel assignment information includes station identification information identifying stations participating in the beam tracking process.

  To achieve the objectives of the present invention, a method for controlling the beam tracking process is disclosed. The method transmits a first beam pattern to at least one station, wherein each of the first beam patterns is fed back from the at least one station for a predetermined period during a transmission stage identified by a beam pattern index. An index is received, wherein the feedback index includes a receiving step indicating one beam pattern selected by the at least one station in the first beam pattern.

  Preferably, the beam pattern index and the feedback index are generated using a Barker code.

  Preferably, the predetermined interval is the channel time allocated by the coordinator to perform the beam tracking process.

  Preferably, the at least one feedback index is received using an LBT (Listen-Before-Talk) method.

  Preferably, the predetermined interval includes a plurality of subchannels, and the subchannels are divided by other frequency bands at the same time, and the feedback index of the at least one station is the subchannel. Received through the channel.

  To achieve the objectives of the present invention, a method for controlling the beam tracking process is provided. The method transmits a first beam pattern to a target station, each of the beam patterns being identified by a beam pattern index and a first feedback index from the target station during a predetermined interval. And the second beam pattern, wherein the first feedback index indicates one beam pattern selected by the target station in the first beam pattern, and each of the second beam patterns is a beam pattern index. A receiving step identified by the step of: determining a beam pattern among the second beam patterns; and transmitting a second feedback index at the target station, wherein the second feedback index is determined in the determining step. A single beam pattern Including Shimesuru second transmission stage.

  To achieve the objectives of the present invention, a method for performing a beam tracking process at a transmitting station is disclosed. The method includes: a first receiving step of receiving first state information related to a state of a receiving station from the receiving station; and a period of a beam tracking process based on the second state information and the first state information. The second status information includes a determination message associated with the transmitting station, and a request message requesting a coordinator to allocate a channel time for performing the beam tracking process according to a period of the beam tracking process. A first transmission step of sending, a second reception step of receiving channel assignment information corresponding to the request message from the coordinator, and transmitting a beam pattern at least one receiving station according to the channel assignment information, wherein each beam pattern is Identified by beam pattern index Receiving at least one feedback index from at least one receiving station during a second transmission phase and a predetermined duration, wherein the feedback index is the at least one reception in the beam pattern. A third reception step indicating one beam pattern respectively selected by the station;

  It will be appreciated that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. Yes.

  According to the embodiment of the present invention, the beam search and tracking period are adaptively adjusted in consideration of the antenna angle of the transmitting and receiving stations and the receiver information, the beam pattern feedback is processed with a simple code, and the beam search and tracking are performed. Tracks many beam links at once with unidirectional beam tracking by minimizing the amount of hardware and information required, allocating time and channels for beam tracking to the stations that want to form the beam links Is possible. In addition, sub-channels that can be used for beam tracking and search, in which many stations send out beam patterns at the same time with bidirectional beam tracking, are assigned to each station so that many stations can search simultaneously. There is an effect that the amount of use can be reduced.

  The accompanying drawings are provided to provide a further understanding of the invention, and are illustrative of embodiments of the invention and are used in conjunction with the detailed description of the invention to explain the principles of the invention.

It is the figure which showed the hierarchical structure which concerns on invention. It is the figure which showed the case where mobility cannot be supported when the angle of a beam is narrow. It is the figure which showed the case where mobility is supported when the angle of a beam is wide. 6 is a diagram illustrating a process of controlling a beam angle and transmission power according to an embodiment of the present invention. FIG. FIG. 10 is a diagram illustrating a process of adjusting a beam search and tracking period according to another embodiment of the present invention. It is the figure which showed the example of the short distance network to which this invention is applied. It is the figure which showed the example of the exchange schedule of a general unidirectional tracking signal. It is the figure which showed the example of the beam pattern index applied to this invention. It is the figure which showed the example of the exchange schedule of the unidirectional tracking signal which concerns on one Example of this invention. It is the figure which showed the example of the exchange schedule of a general bidirectional tracking signal. It is the figure which showed the example of the exchange schedule of the bidirectional tracking signal which concerns on the other Example of this invention. It is the figure which showed the example of the frequency band which each station radiates | emits a beam pattern in FIG. 3 is a signal flow diagram of a beam tracking method considering channel time allocation according to an embodiment of the present invention; It is the figure which showed the example of the message used for the channel time request | requirement of FIG. It is the figure which showed the example of the message used for the channel time allocation of FIG. FIG. 10 is a diagram illustrating an example of a process in which a receiving station transmits a feedback index in FIG. 9. It is the figure which showed the example of the beam pattern which a transmission station radiates | emits in FIG. FIG. 18 is a diagram illustrating an example of a process in which a receiving station transmits a feedback index to a transmitting station in FIG. 17. FIG. 10 is a diagram illustrating time allocation for beam tracking in FIG. 9. It is the figure which showed the example of the beam pattern which a station radiates | emits according to the exchange schedule of the bidirectional tracking signal which concerns on the other Example of this invention. FIG. 20 is a diagram illustrating an example of a process in which stations exchange feedback indexes in FIG. 19. It is the figure which showed the time allocation for beam tracking in FIG. It is the figure which showed one example of the channel time which a coordinator allocates in FIG. It is the figure which showed the other example of the channel time which a coordinator allocates in FIG. It is the figure which showed the structure of the station | game which concerns on one Example of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the embodiments of the present invention exemplified below can be modified in various other forms, and the scope of the present invention is not limited to the embodiments described in detail below.

  FIG. 1 shows a hierarchical structure of conventional wireless communication.

  The conventional hierarchical structure includes an application layer, an upper layer, a MAC layer, and a physical (PHY) layer. The application layer is connected to a device management element (DME), the upper layer is an upper layer management element (HLME), the MAC layer is a MAC layer management element (MLME), and the physical layer is through a physical layer management element (PLME). Connected to device management element. Since the existing wireless communication has a two-stage structure including a physical (PHY) / MAC layer, there is a problem that an antenna angle or the like cannot be taken into consideration during beam search and tracking.

  In the case of wireless communication with strong directivity such as mmWave, it is necessary to consider an RF / analog front end (RF / analog front end) as one layer in order to perform harmonized management. In the hierarchical structure, an antenna analog layer added as a layer for the RF / analog front end is connected to a radio layer management element (RLME).

  FIG. 2 shows a case where mobility cannot be supported when the beam angle is narrow.

  As shown in FIG. 2, when the beam angle is narrow, mobility cannot be supported unless beam search and tracking are frequently performed.

  On the other hand, if the beam angle is wide, it is easy to support mobility. As the beam angle becomes wider, the beam arrival distance becomes shorter. However, the short beam distance can be compensated by adjusting the transmission power.

  FIG. 3 shows a case where mobility is supported when the beam angle is wide.

  In the case of FIG. 3, the beam transmission angle from the station A is larger than that in FIG. In this case, in proportion to how wide the beam angle is compared with FIG. 2, the probability that the station B will leave the beam while moving is less than in the case of FIG.

  FIG. 4 shows a process of controlling the beam angle and the transmission power according to an embodiment of the present invention.

  By adjusting the transmission power and the beam angle according to the distance between the stations or the received signal strength, an optimum beam can be formed in each case. In FIG. 4, when the received signal strength is higher than necessary, the antenna angle can be expanded instead of reducing the transmission power. In this case, the probability that the station will leave the beam while moving is reduced.

  FIG. 5 shows a process of adjusting a beam search and tracking period according to another embodiment of the present invention.

  The beam search and tracking period is the time interval between the current beam tracking process and the next beam tracking process. The beam search and tracking period may be determined by the parameters in Table 1.

  That is, the beam search and tracking period are periodically changed in consideration of the beam angle of the transmitting station or the receiving station, service quality (Application QoS) of the application layer, station mobility, channel time status, etc. be able to.

  For example, as shown in Table 1, each parameter can be information indicating whether the parameter level is higher or lower than a certain level.

  When the beam angle is wide, when the sensitivity of QoS is low, or when the channel time is sufficient, beam tracking can be performed at long cycle intervals. If the station is highly mobile, many Beam Tracking Efforts are required. Accordingly, it is desirable to determine the beam search and tracking period in consideration of at least one of the above parameters in the device management element (DME).

  If a plurality of stations establishing a beam link mutually exchange receiver information as state information in addition to the parameters shown in Table 1, an optimum period can be determined. In FIG. 6, the receiver information includes the receiving station mobility of the application layer, the link status of the physical layer, the antenna angle of the antenna analog layer, and the like. The receiver information can be transmitted periodically to the transmitting station, whereby the beam search and tracking period can also be changed periodically.

  The period of beam search and tracking can be determined by the transmitting station or the receiving station. In one example, the device management element of the transmitting station uses the beam angle of the transmitting station, service quality of the application layer, station movement information, channel time state information, movement information of the receiving station, antenna angle information, and link state information. Thus, how often beam tracking is performed can be determined.

  For example, it is advantageous to track as frequently as possible if the channel time is sufficient, but if the channel time is not sufficient, beam search and tracking can be performed as frequently as possible in a higher QoS beam link. .

  The beam search and tracking periods are determined by each station, and channel allocation information including the channel time or the determined period can be requested from the coordinator. In this case, the optimal beam tracking operation can proceed without coordinator interference.

  FIG. 6 shows an example of a short-distance network to which the present invention is applied.

  As shown in FIG. 6, a notebook personal computer (A), a monitor (B), a PMP (C), an external hard disk drive (E), etc. can be connected wirelessly. At this time, a beam link is formed between the notebook computer (A) and the monitor (B), between the notebook computer (A) and the PMP (C), and between the notebook computer (A) and the external hard disk drive (E). be able to.

  FIG. 7 shows an example of a general unidirectional tracking signal exchange schedule.

  In general, beam link tracking is performed by the transmitting station (A) for each of the receiving stations (B, C, E). That is, beam tracking between the transmitting station (A) and the receiving station (B) is performed independently of the remaining receiving stations (C, E) within a certain time 210 after the data transmission 200 is completed. Beam tracking between the transmitting station (A) and the receiving station (C) is also performed independently of the remaining receiving stations (B, E) within a certain time 220 after the data transmission 215 is completed. Similarly, beam tracking between the transmitting station (A) and the receiving station (E) is performed independently of the remaining receiving stations (B, C) within a certain time 230 after the data transmission 225 is completed. . Such a method is not efficient when the number of beam links in the network is large, because the time required for beam search and tracking becomes very long.

  In order to form a beam link, each station needs to transmit feedback on the received beam pattern. Since a method of exchanging or feeding back an antenna weight vector (Antenna Weight Vector) has a large amount of data, it requires a lot of time.

  In the present invention, the amount of data can be reduced by using the beam pattern index. In particular, the beam pattern index can be transmitted in a preamble form without being transmitted in the data transmission physical layer (PHY). In particular, a barker code can be used in the beam pattern index.

  The 13-bit Barker code has a narrow band of 38.4 kHz, has a very good auto-correlation characteristic, and has high accuracy and resolution.

  FIG. 8 shows an example of a beam pattern index applied to the present invention.

  FIG. 8 is an example showing 32 beams with a simple Barker code of length 5. In this way, the beam pattern index can be recognized even with a simple correlator. This allows stations that are to form beam links to easily exchange pattern indexes.

  FIG. 9 shows an example of a unidirectional tracking signal exchange schedule according to one embodiment of the present invention.

  In a wireless solution used for a PC peripheral device, there are many cases where many stations communicate at the same time centering on a PC. In this case, beam tracking of each individual link is inefficient.

  As shown in FIG. 9, the transmitting station (A) emits the beam pattern once, and the receiving station feeds back within a certain time 330. After the data transmission (300, 315, 325) is completed, when the transmitting station (A) emits a beam pattern for beam tracking, peripheral devices (B, C, E) participate in the beam tracking process at a time. . This method can receive as much feedback as possible in one search.

  For this purpose, the search and tracking sections need to be assigned to beacons and broadcast. Also, the associated station must be prepared to feed back the beam pattern index within the time allotted to the beacon.

  FIG. 10 shows an example of a general bidirectional tracking signal exchange schedule.

  Beam tracking between stations (A) and (B) is performed independently of the remaining stations (C, D, E, F) within a certain time 410 after data transmission 400 is completed. Beam tracking between stations (C) and (D) is also performed independently of the remaining stations (A, B, E, F) within a predetermined time 420 after data transmission 415 is completed. Similarly, beam tracking between stations (E) and (F) is performed independently of the remaining stations (A, B, C, D) within a determined time 430 after data transmission 425 is completed. . Such a system is not efficient if the number of beam links in the network increases, and the time required for beam search and tracking becomes very long.

  FIG. 11 shows an example of a bidirectional tracking signal exchange schedule according to another embodiment of the present invention.

  If a sub-channel for beam search is determined for each station, beam search for several links can be performed simultaneously. In this way, channel time can be saved.

  As shown in FIG. 11, after data transmission (500, 515, 525) is completed, each station simultaneously performs beam tracking using a subchannel assigned to each station within a certain time (510, 520, 530). Can be executed. On the other hand, if the channel time is insufficient to radiate all the beam patterns at a specific station, the beam patterns can be emitted separately without radiating all the patterns at once.

  FIG. 12 shows an example of a frequency band in which each station emits a beam pattern in FIG.

  As shown in FIG. 12, each station (A, B, C, D, E, F) can emit a beam pattern simultaneously. At this time, since the frequency bands (A, B, C,..., F) of the subchannels assigned to the respective stations are different from each other, no interference occurs. This requires the coordinator to allocate channel time for beam tracking and search so that each station can use the channel time when performing beam tracking and search.

  FIG. 13 is a signal flow diagram of a beam tracking method considering channel time allocation according to one embodiment of the present invention.

  First, the station A transmits a request message requesting a channel time for beam tracking to the coordinator (710). FIG. 13 shows a form in which the coordinator exists in a device independent of the stations A, B, and C. In the case of unidirectional tracking, it can also be added to the transmitting station in the form of software or hardware.

  Next, the coordinator transmits a response to the request message to the station A (720). This process can be omitted.

  The coordinator allocates a beam tracking start time, a tracking interval, and the like in response to the request message. If different subchannels are used for each station, the coordinator can assign a channel number to each station. The coordinator transmits the allocation result through the allocation information (730). At this time, the allocation information can be broadcast through a beacon signal.

  When the station A receives the allocation information from the coordinator, the station A radiates a beam pattern including each beam pattern index toward the stations B and C based on the allocation information (740).

  Stations B and C can also receive coordinator assignment information. The stations B and C that have received the beam pattern feed back to the station A the index of the beam pattern having the strongest signal strength among the received beam patterns, that is, the feedback index (751, 752). When the stations B and C receive the allocation information, the stations B and C can feed back the feedback index to the station A at the channel time indicated by the allocation information.

  On the other hand, in the case of bidirectional beam tracking, the stations B and C can transmit the feedback index simultaneously while radiating their own beam patterns.

  FIG. 14 shows an example of a message used for the channel time request (710) of FIG.

  For smooth beam search and tracking, any one of the stations in the network can request a search and tracking time from the coordinator. Not only the station that requested the search and tracking time, but also the associated station can operate according to the time allocated by the coordinator. The station that requests the search and tracking time from the coordinator can be a station with relatively low mobility or a stationary station.

  The request message for such beam search or beam tracking may include the following fields.

  The Destination field indicates a target station identifier (STA ID), and the Type indicates an allocation purpose, that is, beam tracking and search. Preferably, Type can indicate whether beam tracking is uni-directional or bi-directional.

  The duration (Duration) indicates the time required for beam tracking or search, and the period (Period) information indicates how often beam tracking should be executed.

  FIG. 15 shows an example of a message used for the channel time allocation (730) of FIG.

  The message or channel assignment information includes the following information. Source information indicates an identifier (STA ID) of a station that emits a beam pattern. Destination information indicates a target station identifier (STA ID). From the source information and destination information, each station knows which station emits the beam pattern and to which station it should feed back.

  Type indicates the assignment purpose, ie beam tracking and search. Preferably, the Type can indicate whether the beam tracking is uni-directional or bi-directional.

  A duration (Duration) indicates a time allocated by the coordinator for beam tracking or search, and a period (Period) indicates a tracking period determined by the coordinator.

  The channel number (CH No.) is subchannel information assigned to each station by the coordinator when beam search is performed separately for each subchannel. If the subchannels are different, there may be no interference even if searching at the same time.

  The coordinator can broadcast the information via a beacon signal.

  FIG. 16 shows an example of one process. Here, as shown in FIG. 9, the receiving station transmits a feedback index.

  Station A receives a time allocation for beam tracking from the coordinator and sends out a beam pattern including a beam pattern index. Station B listens to such a beam pattern and determines the optimum beam pattern with the best signal quality. In FIG. 16, station B determines “m” as the optimum beam pattern. If station B transmits the feedback index “m” to station A, a beam link is formed between station A and station B.

  FIG. 17 shows an example of the beam pattern radiated from the transmitting station in FIG.

  When the transmitting station emits a beam in many directions, different beam pattern indexes are included in each direction. Each receiving station can determine a beam having the maximum signal strength in the beam pattern and feed back the corresponding beam pattern index to the transmitting station.

  FIG. 18 shows an example of the process in which the receiving station transmits the feedback index to the transmitting station in FIG.

  If the station A is assigned channel time for beam tracking by the coordinator and sends out a beam pattern including a beam pattern index, the stations B and C listen to such a beam pattern and have the best signal quality. Determine the optimal beam pattern. In FIG. 18, station B determines “m” as the best beam pattern, and station C determines “n” as the best beam pattern.

  Stations B and C feed back a beam pattern index indicating an optimum beam pattern for the channel time allocated for feedback. At this time, channel access can be performed using an LBT (Listen-Before-Talk) method or a method using a time allocated for feedback for each station. .

  FIG. 19 shows channel time allocation for beam tracking in FIG.

  FIG. 19 shows the beam pattern that station A emits sequentially on the time axis. Each of the receiving stations (B, C, E) transmits a feedback index to the station A in a time interval allocated to itself for transmitting a feedback signal.

  FIG. 20 shows an example of a beam pattern emitted by a station according to a bidirectional tracking signal exchange schedule according to another embodiment of the present invention.

  After station A emits its beam pattern, if bi-directional beam tracking is required, station B can emit its beam pattern to transmit a feedback index. That is, when performing feedback, each station can emit a rotating beam pattern for feedback in all directions instead of transmitting a beam pattern in a specific direction.

  FIG. 21 shows an example of a process in which stations exchange feedback indexes in FIG.

  First, assume that station A has emitted a beam pattern including its own beam pattern index (m). If station B emits a beam pattern including its own beam pattern index (n) and feedback index (m), station A determines an optimum beam pattern among the beam patterns emitted by station B. If station A transmits a feedback index (n) indicating an optimal beam pattern to station B, a bi-directional beam link is formed between station A and station B.

  FIG. 22 shows time allocation for beam tracking in FIG.

  FIG. 22 shows the channel time that station B is assigned to transmit its beam pattern index and feedback index in all directions. Thus, if a bi-directional link is required, the station can emit a beam pattern and transmit a feedback index in all directions. If the station transmits a feedback index, station A can simply transmit the feedback index to station B without having to emit a beam pattern.

  FIG. 23 shows an example of the channel time allocated by the coordinator in FIG.

  The beacon signal includes information on the channel time allocated by the coordinator. If the beacon signal allocation information is changed, the operation related to the tracking of the station is also changed. Allocation information can be reflected every beacon period.

  The time interval or channel time for beam tracking can be assigned to various forms by the coordinator, and after data transmission between stations (1210, 1220, 1230, 1240) is completed as shown in FIG. Can also be done.

  The channel time or time interval 1250, 1260, 1270, 1280 in the beam tracking channel time or time interval is assigned to each station that emits the beam pattern, and each channel time or time interval is associated with the beam pattern emission of the corresponding station. Used for feedback transmission for this. A separate time interval is required for each station that emits the beam pattern. However, as described above, when operating on subchannels different from station to station, a single time interval, for example, the first time interval 1250 is often used. Stations can operate simultaneously.

  FIG. 24 shows another example of the channel time allocated by the coordinator in FIG.

  If it is determined that the channel time is insufficient with respect to the channel time request, the coordinator can also distribute and accommodate the request for the channel time in many beacon periods.

  For example, as shown in FIG. 23, half (1350, 1360) can be allocated to the first beacon period and the remaining half (1370, 1380) can be allocated to the second beacon period. .

  The time interval for beam tracking can be assigned to various forms by the coordinator, and data transmission between stations (1310, 1311, 1320, 1321, 1330, 1331, 1340, 1341) as shown in FIG. ) Can be completed after completion.

  FIG. 25 shows the configuration of a station according to one embodiment of the present invention.

  Referring to FIG. 25, the station of the present invention includes a timer (timer, 10), a communication module 20, a beam tracking process management unit (management unit of beam tracking process, 30), and a controller (controller, 40). it can.

  The timer 10 serves to notify the start and end of a beacon interval indicating the interval between the beacon signal and the next beacon signal. In addition, the timer 10 can provide time information within the beacon period. For example, timer 10 can provide a point in time of the channel time allocated by the coordinator. The communication module 20 can transmit data or signals at other stations or coordinators, or can receive data or signals transmitted from other stations or coordinators. For example, under the control of the control unit 40, receiver status information is received from a receiver, a channel time allocation request message for beam tracking is transmitted to a coordinator, and a beam pattern is transmitted or received by another station. Can play a role.

  The beam tracking process management unit 30 may determine the beam tracking period based on at least one of the receiving station status information and the transmitting station status information received through the communication module 20. In addition, a channel time request message for beam tracking can be defined. For example, when a channel time request for beam tracking is requested, an identifier of the target station, a beam tracking direction, a channel time interval, and a beam tracking period can be determined. If channel time allocation information for the channel time requested by the coordinator is received through the communication module 20, the channel time information for beam tracking can be determined. At this time, the received channel time allocation information may include information about subchannels, which includes a plurality of subchannels having different frequency bands within the same channel time, and beam tracking between stations. Can be executed simultaneously. In addition, a beam pattern index for each beam pattern can be set for beam tracking. It is also possible to determine the best beam pattern from among the beam patterns received from other stations.

  The control unit 40 can perform control so as to execute beam tracking according to the beam tracking period determined by the beam tracking process management unit 30. Further, it is possible to control to transmit a channel time request message for beam tracking determined by the beam tracking management unit 30 to the coordinator through the communication module 20. Further, it is possible to perform control so that beam tracking is executed according to the channel time for beam tracking using the channel time information determined by the beam tracking management unit 30. The beam pattern identified by the beam pattern index set by the beam tracking management unit 30 can be controlled to be transmitted through the communication module 20. Further, the beam pattern index information can be transmitted to the corresponding station for the optimum beam pattern determined by the beam tracking management unit 30.

  In this embodiment, the roles of the control unit 40 and the beam tracking management unit 30 are described separately. However, it is obvious that the control unit 40 can include the role of the beam tracking management unit 30.

  Although the present invention has been described with reference to one embodiment shown in the drawings, this is by way of example only, and various modifications and variations of the embodiments can be made by those having ordinary skill in the art. Understand the point. Such modifications should be considered to be within the technical protection scope of the present invention. Therefore, the true technical protection scope of the present invention must be determined by the technical idea of the appended claims.

  The present invention relates to a method for efficiently searching and tracking a beam during wireless transmission with strong directivity, and can be applied to a wireless station constituting a communication network with strong directivity such as mmWave.

Claims (28)

A communication module configured to transmit data to at least one of the external station and the coordinator and receive data from at least one of the external station and the coordinator;
Configured to control the communication module to transmit a first beam pattern to at least one station and to control the communication module to receive a feedback index from the at least one station in a predetermined interval. A control unit;
Have
Each of the first beam patterns is identified by a beam pattern index, and the feedback index controls a beam tracking process that indicates one beam pattern selected by the at least one station from the first beam pattern. Device to do.   The apparatus for controlling a beam tracking process according to claim 1, wherein the first state information includes mobility information, link state information, and antenna angle information about the receiving station.   The apparatus for controlling a beam tracking process according to claim 1, wherein the second state information includes quality of service (QoS) information, mobility information, channel state information, and antenna angle information for the transmitting station. A communication module configured to transmit data to at least one of the external station and the coordinator and receive data from at least one of the external station and the coordinator;
Controlling the communication module to send a request message requesting to allocate a channel time for performing a beam tracking process, and controlling the communication module to receive channel assignment information corresponding to the request message. And a controller configured to control to perform the beam tracking process using a beam pattern index based on the channel assignment information;
An apparatus for performing a beam tracking process including:   The channel assignment information includes start information, section information, and channel number information, the start information indicates a start point of the allocated channel time, the section information indicates a section of the allocated channel time, 5. To perform the beam tracking process of claim 4, wherein the channel number information indicates an identification identifying a subchannel, the subchannel being divided by a frequency band during the assigned channel time. Equipment. A communication module configured to transmit data to at least one of the external station and the coordinator and receive data from at least one of the external station and the coordinator;
Configured to control the communication module to transmit a first beam pattern to at least one station and to control the communication module to receive a feedback index from the at least one station in a predetermined interval. A control unit;
Have
Each of the first beam patterns is identified by a beam pattern index, and the feedback index controls a beam tracking process that indicates one beam pattern selected by the at least one station from the first beam pattern. Device to do.   The apparatus for controlling a beam tracking process according to claim 6, wherein the beam pattern index and the feedback index are generated using a Barker code.   The predetermined section includes a plurality of subchannels, and the subchannels are divided by different frequency bands at the same time, and the feedback index of the at least one station is received via the subchannels. The apparatus for controlling a beam tracking process according to claim 6. A method for performing a beam tracking process at a transmitting station, comprising:
Receiving from the receiving station first state information associated with the state of the receiving station;
Determining a period of the beam tracking process based on second state information associated with the state of the transmitting station and the first state information;
Performing the beam tracking process for each determined period;
Including
A method for performing a beam tracking process, wherein the period is a time interval between a current beam tracking process and a next beam tracking process.   The method for performing a beam tracking process according to claim 9, wherein the first state information is received periodically.   The method for performing a beam tracking process according to claim 9, wherein the first state information includes mobility information, link state information, and antenna angle information for the receiving station.   The method for performing a beam tracking process according to claim 11, wherein the second state information includes quality of service (QoS) information, mobility information, channel state information, and antenna angle information for the transmitting station. The determining step includes:
If the antenna angle information included in the first and second state information indicates that at least one antenna angle of the transmitting station and the receiving station is greater than a predetermined value, the beam tracking process includes: The method for performing the beam tracking process of claim 12, further comprising controlling to reduce the period. The determining step includes:
And further comprising controlling to reduce the period of the beam tracking process when the QoS information included in the second state information indicates that the QoS of the transmitting station is higher than a predetermined level. A method for performing the beam tracking process of claim 12. The determining step includes:
If the mobility information included in the first and second state information indicates that at least one mobility of the transmitting station and the receiving station is higher than a predetermined state, the beam tracking process The method for performing the beam tracking process of claim 12, further comprising controlling to reduce the period. The determining step includes:
13. The beam tracking process according to claim 12, further comprising controlling to reduce the period of the beam tracking process when the channel state information in the second state information indicates an idle state of the transmitting station. How to do.   The method for performing a beam tracking process according to claim 12, wherein the antenna angle information included in the first and second state information is determined from a radio hierarchy management element connected to an antenna analog hierarchy. A method for performing a beam tracking process at a station, comprising:
Transmitting a request message requesting to allocate channel time for performing the beam tracking process to the coordinator;
Receiving channel assignment information corresponding to the request message from the coordinator;
Performing the beam tracking process using a beam pattern index based on the channel assignment information;
A method for performing a beam tracking process comprising:   The channel assignment information includes start information, section information, and channel number information, the start information indicates a start point of the allocated channel time, the section information indicates a section of the allocated channel time, 19. To perform the beam tracking process of claim 18, wherein channel number information indicates an identification identifying a subchannel, the subchannel being divided by a frequency band during the allocated channel time. the method of. The request message includes at least one of destination information, type information, section information, and period information,
The destination information indicates a target station of the beam tracking process, the type information indicates a direction of the beam tracking process, the section information indicates a section of the beam tracking process, and the period information indicates the beam tracking process. The method for performing a beam tracking process according to claim 18, wherein the beam tracking process is indicative of a period.   The method for performing a beam tracking process according to claim 18, wherein the channel assignment information includes station identification information identifying a station participating in the beam tracking process. Transmitting a first beam pattern to at least one station, each of the first beam patterns being identified by a beam pattern index;
Receiving a feedback index from the at least one station in a predetermined interval, the feedback index indicating one beam pattern selected by the at least one station from the first beam pattern; Stages,
A method for controlling a beam tracking process comprising:   The method for controlling a beam tracking process according to claim 22, wherein the beam pattern index and the feedback index are generated using a Barker code.   The method for controlling a beam tracking process according to claim 22, wherein the predetermined interval is a channel time allocated by a coordinator to perform the beam tracking process.   The method for controlling a beam tracking process according to claim 22, wherein the at least one feedback index is received using an LBT scheme.   The predetermined section includes a plurality of subchannels, and the subchannels are divided by one frequency band at the same time, and the feedback index of the at least one station is received via the subchannels. 23. A method for controlling a beam tracking process according to claim 22, wherein: Transmitting a first beam pattern to a target station, each of the first beam patterns being identified by a beam pattern index;
Receiving a first feedback index and a second beam pattern from the target station in a predetermined interval, wherein the first feedback index is selected from the first beam pattern by the target station; Two beam patterns, each of the second beam patterns being identified by a beam pattern index;
Determining one beam pattern from the second beam patterns;
Transmitting a second feedback index to the target station, the second feedback index indicating the one beam pattern determined in the determining step;
A method for controlling a beam tracking process comprising: A method for performing a beam tracking process at a transmitting station, comprising:
Receiving from the receiving station first state information associated with the state of the receiving station;
Determining a period of the beam tracking process based on second state information associated with the state of the transmitting station and the first state information;
Transmitting to the coordinator a request message requesting to allocate a channel time for performing the beam tracking process according to the period of the beam tracking process;
Receiving channel assignment information corresponding to the request message from the coordinator;
Transmitting a beam pattern to at least one receiving station according to the channel assignment information, each of the beam patterns being identified by a beam pattern index;
Receiving at least one feedback index from the at least one receiving station in a predetermined interval, wherein the feedback index is selected from the beam patterns by the at least one receiving station. Each stage of
A method for performing a beam tracking process comprising:

Images