JP2010171648A - Radio communication method utilizing beam forming technique, and radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication method for reducing time required for setup, and to provide a radio communication system. <P>SOLUTION: In the radio communication method, radio waves are used for radio communication. Quasi-omni beams are used as radio waves. Beam forming required for radio communication is performed. In this case, a beam former (10) for transmitting radio waves decides the best transmission direction of the quasi-omni beams to be transmitted from a plurality of transmission directions. Then, a combiner (20) receiving radio waves decides the best reception direction of the quasi-omni beams to be received from a plurality of reception directions. In this manner, the best transmission and reception directions are decided separately. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication method and a wireless communication system using a beamforming technique.

  In recent years, a wireless personal area network (WPAN) has been proposed as a technique for transmitting broadband signals with high quality over a short distance. As the WPAN, there is a wireless communication system using a radio wave in a millimeter wave band (for example, 60 GHz) (for example, see Non-Patent Documents 1 and 2 below). Such a wireless communication system using millimeter-wave radio waves is expected as a wireless communication system that realizes large-capacity transmission and low cost.

  In a wireless communication system using millimeter wave radio waves, a link between two devices is established by performing a training sequence. Here, the training sequence corresponds to an operation of finding the best beam from the transmission beams transmitted from one device to the other device. This makes it possible to set up an excellent transmission link.

  However, in order to set up a good link, the sending device needs to send the data corresponding to the training sequence many times. In response to this, the receiving side device needs to perform calculations corresponding to a large number of training sequences, and a lot of load is applied. As a result, setup takes a lot of time.

Federal Communications Commission, “Amment of parts 2, 15 and 97 of the Commission's rules to permit use of radio frequencies above 40 GHz for 40 GHz. 94-124, RM-8308, December 1995 H. Ikeda, Y .; Shoji, “60 GHz Japan regulations”, IEEE 802.15-05-0525-03, October 2006

  Accordingly, a first object of the present invention is to provide a wireless communication method and a wireless communication system that can reduce the time required for setup.

  A second object of the present invention is to provide a radio communication method and a radio communication system that can sufficiently increase the gain at an antenna even if the time required for setup is reduced.

  The present invention basically relates to a wireless communication method for performing wireless communication using a beam forming technology using radio waves. In this wireless communication method, beam forming processing is required for wireless communication. Moreover, the radio wave used for this wireless communication is a quasi-omni beam. Kwasomuni beam means a quasi-omnidirectional beam.

  In this wireless communication method, a beam forming step is executed to perform wireless communication. In this beam forming step, a transmission direction determination step and a reception direction determination step are executed. In the transmission direction determination step, the best transmission direction of the quasi-omni beam to be transmitted by the beam former (10) that transmits radio waves is determined from among a plurality of transmission directions. Further, in the reception direction determination step, the best reception direction of the quasi-omni beam to be received by the combiner (20) that receives the radio wave is obtained by using the quasi-omni beam of the best transmission direction determined in the transmission direction determination step. , Determined from among a plurality of reception directions.

  Here, the transmission direction determination step and the reception direction determination step are performed individually (sequentially). This eliminates the need to consider all combinations of multiple transmission directions and multiple reception directions during beamforming. As a result, the time required for setup (link establishment between the beam former (10) and the combiner (20)) can be reduced. In addition, according to this aspect, since it becomes possible to perform wireless communication using information on the determined best transmission direction and best reception direction, it is possible to sufficiently increase the gain at the antenna of the quasi-omni beam. It becomes.

  In a preferred aspect of the present invention, in the transmission direction determination step, the beamformer (10) divides the Kwasomuni beam to be transmitted into a plurality of directional beams, and the beamformer (10) includes: The step of transmitting the directional beam as a beacon in the transmission direction corresponding to the directivity of the directional beam, and the combiner (20) has at least the highest gain among the directional beams received from the beamformer (10). A step of feeding back information on the high directional beam to the beamformer (10), and the beamformer (10) based on the information on the directional beam having the highest gain received from the combiner (20). Determining the best transmission direction of the beamformer (10). As described above, the combiner (20) feeds back to the beam former (10), so that the beam former (10) can surely grasp the best transmission direction.

  Furthermore, in a more preferred aspect of the present invention, in the reception direction determining step, the combiner (20) divides the transmitted quadrature beam into a plurality of directional beams, and the beam former (10) is the best. The data corresponding to the training sequence is transmitted in the transmission direction, and the data corresponding to the training sequence transmitted from the beam former (10) by the combiner (20) is transmitted using a plurality of directional beams. The listening (receiving) step and the step of the combiner (20) determining the best receiving direction from the directions corresponding to the plurality of directional beams are executed. In this way, the best reception direction can be easily identified by dividing the quasi-omni beam into directional beams.

  Another aspect of the present invention relates to a wireless communication system (1). In this wireless communication system (1), wireless communication is performed using radio waves.

  The wireless communication system (1) includes a beam former (10) capable of transmitting a quasi-omni beam as a radio wave and a combiner (20) capable of receiving a quasi-omni beam as a radio wave.

  Here, the beam former (10), when performing beam forming necessary for wireless communication, transmits a plurality of transmission directions of the best transmission direction of the quasi-omni beam to be transmitted by the beam former (10). Transmission direction determining means for determining from the directions is included. Similarly, when the combiner (20) performs the beam forming necessary for wireless communication, the transmission direction determining means determines the best reception direction of the quasi-omni beam to be received by the combiner (20). The reception direction determining means for determining from among a plurality of reception directions by using the Kwasomuni beam of the best transmission direction is included. In the wireless communication system (1), when performing beam forming necessary for wireless communication, the determination of the best reception direction by the reception direction determination unit is performed after the determination of the best transmission direction by the transmission direction determination unit. Done. Thereby, in this wireless communication system (1), all combinations of a plurality of transmission directions and a plurality of reception directions are not considered. For this reason, an effect equivalent to the wireless communication method described above can be obtained.

  According to the present invention, since the determination of the best reception direction is performed after the determination of the best transmission direction, it is possible to eliminate the need to consider all combinations of a plurality of transmission directions and a plurality of reception directions. The time required for setup (link establishment between the first device 10 and the second device 20) can be reduced. Further, by performing wireless communication using information on the determined best transmission direction and best reception direction, it is possible to sufficiently increase the gain at the antenna of the quasi-omni beam.

FIG. 1 is a block diagram showing a configuration example of a wireless communication system 1 according to the present invention. FIG. 2 is a flowchart showing a procedure of beam forming processing that is performed when wireless communication is performed in the wireless communication system 1 shown in FIG. FIG. 3 is a diagram schematically showing the structure of frame data when beamforming using a quasi-omni beam is performed. FIG. 4 is a diagram used for explaining a state when the beamformer transmits a sub-beacon regarding the training sequence of the beamformer. FIG. 5 is a diagram used for explaining a state when the combiner transmits feedback regarding the training sequence of the beam former. FIG. 6 is a diagram schematically showing the structure of frame data when a directivity training sequence is performed. FIG. 7 is a diagram used for explaining a state when the beamformer transmits data corresponding to the directivity training sequence with respect to the combiner training sequence. FIG. 8 is a diagram used for explaining a state when the combiner transmits feedback regarding the training sequence of the combiner.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. However, the form described below is an example, and can be appropriately modified within a range obvious to those skilled in the art.

  FIG. 1 is a block diagram showing a configuration example of a wireless communication system 1 according to the present invention. As shown in FIG. 1, the system 1 includes a first device 10 capable of wireless communication and a second device 20 capable of wireless communication. The system 1 includes the two devices 10 and 20, but may further include another communicable device.

  In the wireless communication system 1, wireless communication (data communication) using radio waves (beams) is performed between the devices 10 and 20. Wireless communication is performed using radio waves in the 60 GHz band, for example, in a wireless personal area network (WPAN). The frequency band of radio waves is not limited to that in the 60 GHz band, but in WPAN, the frequency band of radio waves is preferably selected from 59 to 76 GHz. The system 1 is configured to be capable of transmitting data from the first device 10 to the second device 20, transmitting data from the second device 20 to the first device 10, and bidirectional data transmission. ing. As wireless communication, data transfer in a home video system can be considered.

  The first device 10 includes a transmission unit that functions as a transmitter that transmits a beam, and a reception unit that functions as a receiver. Moreover, the 1st device 10 has a piconet controller (PNC) in this aspect, as shown in FIG. Similarly to the first device 10, the second device 20 includes a transmission unit that functions as a transmitter, a reception unit that functions as a receiver, and a piconet controller (PNC). Each transmission unit has a plurality of antenna elements, and constitutes an antenna array. Each receiving unit has a plurality of antenna elements, and constitutes an antenna array. Then, the first device 10 and the second device 20 establish a link with each other by using a beamforming technique, and perform data transmission / reception (communication). In this aspect, an antenna symmetric system (ASS) will be described as an example. In this antenna symmetric system, the first device 10 and the second device 20 have the same configuration, and the antenna on the transmitter side and the antenna on the receiver side are arranged symmetrically. Therefore, in this antenna symmetric system, the number of antennas on the transmitting side of the first device 10 and the number of antennas on the receiving side of the second device 20 are the same.

  Various antennas can be used for the devices 10 and 20. Examples of the antenna include a single antenna element, a sectorized antenna, a switching antenna, a one-dimensional (1D) beamforming antenna array, and a two-dimensional (2D) beamforming antenna array. The controller provided in the devices 10 and 20 is not limited to a piconet controller (PNC), and may be another controller, but is preferably a controller that can handle a code book described later.

  In the wireless communication system 1 illustrated in FIG. 1, beam forming (BF) processing is performed in order to perform wireless communication between the first device 10 and the second device 20. At this time, of the devices 10 and 20, for example, the first device 10 functions as a beam former that transmits radio waves. One second device 20 functions as a combiner that receives radio waves from the beamformer and feeds back information about the received radio waves to the beamformer. Both the first device 10 and the second device 20 use a quasi-omni beam as a radio wave. Here, the quasi-omni beam means a quasi-omnidirectional beam.

  Although the details of the beam forming process will be described later, generally, first, the best transmission direction of the quasi-omni beam to be transmitted is determined from among a plurality of transmission directions, and then the quasi beam in the best transmission direction is determined. The best receiving direction of the quasi-omni beam to be received is determined from a plurality of receiving directions using the geomni beam. Therefore, in this aspect, the best transmission direction and the best transmission direction are determined individually (sequentially).

  Further, in this embodiment, an algorithm (program) for beam forming is stored in each device 10 and 20 in order to determine the best transmission direction and the best reception direction. This algorithm changes the antenna mode of the beamformer (first device 10) or combiner (second device 20), and is read and executed by a piconet controller (PNC). Here, as the antenna mode, there are a first mode in which a beam pattern (for example, a fan-shaped beam pattern) is formed by a quadriom beam and a second mode in which a beam pattern is formed by a directional beam.

  A code book is used to change the antenna mode. The code book is based on the MAC layer protocol and can be handled by a piconet controller (PNC). Specifically, the code book is a matrix. By designing each value of the matrix, a quasi-omnidirectional beam can be changed to a directional beam.

Next, the flow of the beam forming process will be described in more detail with reference to the drawings.
FIG. 2 is a flowchart showing a procedure of beam forming processing that is performed when wireless communication is performed in the wireless communication system 1 shown in FIG. S in FIG. 2 indicates each step. When this beam forming process is performed, a link is established between the first device 10 and the second device 20, and data communication is possible between them.

  As shown in FIG. 2, in the beamforming (BF) process, the best transmission direction determination process (S10), the corresponding feedback process (S20), the best reception direction determination process (S30), and the corresponding feedback process. (S40) is executed. Hereinafter, each process will be described in detail.

  In the best transmission direction determination process in step S10, the combiner (second device 20) determines the best transmission direction of the quasi-omni beam to be transmitted by the beamformer (first device 10) from a plurality of transmission directions. It is a step.

  Therefore, first, the first device 10 (beamformer) transmits a beacon in a plurality of transmission directions using a quasi-omni beam. A beacon is defined by the MAC layer protocol, and is a signal for informing other devices of basic information of a device that is a wireless communication terminal.

  In transmitting a beacon in a plurality of transmission directions, it is preferable to cover all areas around the piconet controller (PNC) of the first device 10. Here, different areas may partially overlap. For this reason, a plurality (for example, L) of quasi-omni beams are required.

  Therefore, as shown in the frame data of FIG. 3, the quasi-omni section (beacon) is composed of L quasi-omni sub-beacons. Further, CAP is also divided into L sub-CAPs as shown in FIG. 3 in correspondence with L Kwasomuni beacons. For this purpose, the piconet controller (PNC) on the beamformer side switches the antenna mode from the first mode to the second mode using a code book. Each of these sub-beacons is transmitted by a different quadomni beamformer (that is, via a different antenna on the transmitting side of the first device 10). Here, the quasi-omni beamformer to transmit the sub-beacon can be selected by appropriately designing the quasi-omni codebook.

  By doing in this way, the transmission direction of a sub beacon can be varied. In other words, the beam transmitted by the first device 10 is a plurality of directional beams. The plurality of sub-beacons cover all areas around the piconet controller (PNC) of the first device 10 as shown in FIG.

  During the association (directivity period), the piconet controller (PNC) of the first device 10 has N direction candidates, and the second device 20 also has M direction candidates. The piconet controller (PNC) of the first device 10 and the second device 20 complete the association by using a quasi-omni beam antenna. When the association is completed, device number #u is assigned to at least one CTA (see FIG. 6).

  The CTA to which the device number #u is assigned corresponds to a period during which beam forming processing using a directional beam is performed (directional training period). Specifically, as shown in FIG. A period (B training period) for training a former (here, a beamformer having N direction candidates) is included. The CTA to which the device number #u is assigned further includes a listening period and a period for training the directional combiner (C training period). The listen period and C training period will be described later. Note that the training stages corresponding to the B training period and the C training period are supported by the MAC layer protocol.

  In the B training period, the piconet controller (PNC) of the first device 10 switches the antenna mode from the first mode to the second mode. During the B training period, the training sequence is repeated N times. As a result, the training area around the piconet controller (PNC) of the first device 10 is maintained in a different state (sweep or scan) as shown on the left side of FIG. However, different training areas may partially overlap. Data corresponding to each training sequence is transmitted by using different codebooks.

  In contrast, the second device 20 listens for beacons in each of its own M directions using the Kwasomuni antenna as shown on the right side of FIG. 4 during the B training period. Receiving) is possible.

  And the 2nd device 20 grasps | ascertains the best direction from the strongest beacon (beacon with the highest gain) among the beacons which can be received by itself. That is, the second device 20 determines the best direction (here, the direction i) for itself. Accordingly, the second device 20 can also determine the best direction of the piconet controller (PNC) of the first device 10 (here, the direction is j, or this is indicated by the beam number #n). This determination is particularly easy in the antenna-symmetric system described above, because the radio wave transmission direction and reception direction are the same.

  Then, during the listening period, the second device 20 transmits feedback information to the first device 10 as shown in FIG. 5 (step S20). This feedback information includes information indicating the direction in which the second device 20 has received the strongest signal. During the listening period, both the piconet controller (PNC) of the first device 10 and the second device 20 are operating in the quasi-omni mode (first mode). Thereafter, the piconet controller (PNC) of the first device 10 receives an ACK from the second device 20 by using a quasi-omni beam.

Specifically, the feedback information is transmitted as follows.
First, the second device 20 transmits feedback information to the first device 10 every time the best direction is determined. This feedback is performed, for example, by transmitting an announcement command from the best direction i during the period corresponding to the j-th sub-CAP.

  Similarly, in the period corresponding to the l-th sub-CAP (where l is an integer between 1 and L), the piconet controller (PNC) of the first device 10 has the same beamformer, that is, the l-th quat. Listen using a beamformer (transmission direction) used to transmit information including geomuni beacons. When the piconet controller (PNC) of the first device 10 receives the feedback information from the direction j, the piconet controller (PNC) determines the direction j as the best direction for itself (see FIG. 5). Thereby, the first device 10 can also grasp (determine) the best direction (best transmission direction).

  That is, in this aspect, the first device 10 associates sub-beacon by scanning the area around the piconet controller (PNC) with L beams and associating the period equally with L. The transmission direction (or the corresponding beam number #) at the time of transmission can be associated with the best direction (reception direction) determined by the second device 20. Therefore, even if it is not an antenna symmetrical system, the 1st device 10 can determine the best transmission direction based on the feedback information (best direction) from the 2nd device 20. FIG.

  In the subsequent step S30, the best reception direction of the second device 20 is determined using the beam in the determined best transmission direction (best beam).

  Specifically, during the C training period, the piconet controller (PNC) of the first device 10 sends data corresponding to the directivity training sequence (TS data) for the second device 20 for one group. Transmission is performed using the beam determined in the period (the beam in the best direction #n determined in the listening period) (see the left side of FIG. 7). Here, the TS data for one group is included in the allocated CTA as shown in FIG.

  In response to this, the second device 20 switches the antenna mode from the first mode to the second mode. The training sequence is repeated M times during this C training period. Thereby, as shown on the right side of FIG. 7, the state where the training areas around the second device 20 are different is maintained (sweep or scan). However, different training areas may partially overlap. This sweep is performed by transmitting a directional beam using a code book in various directions.

  When the sweep for the M directions is completed, the second device 20 determines the best direction (best reception direction or beam number #m corresponding thereto) from these directions. Subsequently, the second device 20 transmits the determined best reception direction as feedback information to the piconet controller (PNC) of the first device 10 (see FIG. 8). The feedback information is included in the CAP. At the same time, the second device 20 completes beamforming and performs channel estimation with CES.

  By doing as described above, the piconet controller (PNC) of the first device 10 and the second device 20 grasp the best quasi-omni direction (best transmission direction #n and best reception direction #m). It becomes.

  As described in detail above, in this embodiment, first, the best transmission direction #n is determined in the B training period (steps S10 to S20), and then the C training period is determined using the determined best transmission direction #n. Thus, the best reception direction is determined only by considering the combination of the best transmission direction #n and a plurality of reception directions (steps S30 to S40). Here, dividing the B training period and the C training period corresponds to making the timing at which the first device 10 divides the beam different from the timing at which the second device 20 divides the beam. This makes it possible to determine the best transmission direction and the best reception direction individually (sequentially).

  This eliminates the need to consider all combinations of multiple transmission directions and multiple reception directions. Specifically, it is not necessary to perform a training sequence so as to cover all combinations. Therefore, according to this aspect, it is possible to reduce the number of times the training sequence is repeatedly performed as compared with the conventional case. As a result, the time required for setup (link establishment), specifically, the time required for beamforming operation can be greatly reduced. In addition, according to this aspect, since it becomes possible to perform wireless communication using information on the determined best transmission direction and best reception direction, it is possible to sufficiently increase the gain at the antenna of the quasi-omni beam. It becomes.

  Moreover, in the said aspect, the information regarding the best direction which the 2nd device 20 determined is transmitted to the 1st device 10 as feedback information (step S20). Thereby, the first device 10 can surely grasp (determine) the best transmission direction.

  Moreover, in the said aspect, in order to determine the best transmission direction and the best receiving direction, the Kwasomuni beam is divided | segmented into the directional beam. That is, the antenna mode is switched. As a result, sweeping (scanning) is facilitated, and the best transmission direction and the best reception direction can be easily identified.

  In the aspect described above, the best transmission direction of the first device 10 is determined, and then the best reception direction of the second device 20 is determined. However, instead of this, the best transmission direction of the first device 10 may be determined after the best reception direction of the second device 20 is determined. Even in such a case, an effect equivalent to the above-described effect can be obtained.

  The aspect described above mainly relates to the wireless communication system 1 and the wireless communication method. However, the devices 10 and 20 constituting the wireless communication system 1 of the present invention, antennas, transmitters, receivers, beam forming processing and feedback processing in the wireless communication method of the present invention, and further used in the wireless communication method The code book and frame structure to be formed also constitute the present invention or a part of the present invention. Needless to say, a program (algorithm) corresponding to part or all of the above-described processing and an information storage medium storing the program also constitute the present invention or a part of the present invention.

  The present invention is not limited to data transfer in a home video system, but can be used in all fields of wireless communication. The present invention can also be used when switching wired communication to wireless communication.

1 wireless communication system 10 first device 20 second device

Claims (4)

A wireless communication method for performing wireless communication using radio waves,
The radio wave is a quasi-omni beam,
A beam forming step of performing beam forming necessary for performing the wireless communication,
The beam forming step includes:
A transmission direction determination step of determining a best transmission direction of the quasi-omni beam to be transmitted by the beam former (10) for transmitting the radio wave from a plurality of transmission directions;
The best receiving direction of the quasi-omni beam to be received by the combiner (20) that receives the radio wave is determined by using the quasi-omni beam of the best transmission direction determined in the transmission direction determining step. A receiving direction determining step for determining from the inside,
By separately performing the transmission direction determination step and the reception direction determination step, it is possible to eliminate the need to consider all combinations of the plurality of transmission directions and the plurality of reception directions during the beamforming. Nah,
Wireless communication method. The transmission direction determination step includes:
The beamformer (10) splits a Kwasomuni beam to be transmitted into a plurality of directional beams;
The beam former (10) transmitting the directional beam as a beacon in a transmission direction corresponding to the directivity of the directional beam;
The combiner (20) feeds back at least information on a directional beam having the highest gain among the directional beams received from the beamformer (10) to the beamformer (10);
The beamformer (10) includes determining a best transmission direction of the beamformer (10) based on information on the directional beam having the highest gain received from the combiner (20); The wireless communication method according to claim 1. The receiving direction determining step includes:
The combiner (20) splits a transmitting Kwasomuni beam into a plurality of directional beams;
The beam former (10) transmitting data corresponding to a training sequence toward the best transmission direction;
The combiner (20) listens (receives) data corresponding to the training sequence transmitted from the beamformer (10) using the plurality of directional beams;
The wireless communication method according to claim 2, wherein the combiner (20) includes a step of determining a best reception direction from directions corresponding to the plurality of directional beams. A wireless communication system (1) for performing wireless communication using radio waves,
A beam former (10) capable of transmitting a quasi-omni beam as the radio wave;
A combiner (20) capable of receiving a quasi-omni beam as the radio wave,
The beam former (10)
Transmission direction determining means for determining a best transmission direction of the quadrature beam to be transmitted by the beam former (10) from a plurality of transmission directions when performing beam forming necessary for performing the wireless communication. Including
The combiner (20)
When performing the beam forming, the best receiving direction of the quasi-omni beam to be received by the combiner (20) is determined by using the quasi-omni beam of the best transmission direction determined by the transmission direction determining means. Including reception direction determining means for determining from among reception directions;
The reception direction determining means performs the determination of the best reception direction after the determination of the best transmission direction by the transmission direction determination means,
Thereby, when performing the beam forming, do not consider all combinations of the plurality of transmission directions and the plurality of reception directions,
Wireless communication system (1).

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