JP2016029839A - Radio communication apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication apparatus capable of ensuring equitable sharing of medium.SOLUTION: The radio communication apparatus includes: a holding part; a selection section; and a transmission/reception processing section. The holding part holds: a first set which includes frame distances of one or more types; and a second set which includes frame distances one or more types in which the length of the frame distance of the type identical to the type of the frame distance included in the first set is larger than the length of the frame distance of the identical type included in the first set, and the length of frame distance of at least one first type is larger the frame distance of the first type included in the first set. The selection section selects which of the first set and the second set should be used for carrying out a communication. The transmission/reception processing section communicates with a first communication apparatus which uses a first communication mode by using the frame distance of the first set or the second set according to the selection result made by the selection section.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to wireless communications.

  In order to suppress interference from other wireless systems and interference to other wireless systems, there is a method of controlling a transmission suspension period using CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance).

JP 2001-237849 A

  However, in order to estimate the transmission suspension period in CSMA / CA, other wireless systems must be able to expect transmission periodicity, and this is applicable to wireless systems where periodic transmission is not necessarily expected. I can't. CSMA / CA is a method suitable for application in a wireless system that communicates with a plurality of wireless communication devices and may compete with the plurality of wireless communication devices. Therefore, in the case of a one-to-one proximity communication system, applying CSMA / CA all the time increases overhead and decreases efficiency. As a result, when pursuing efficient one-to-one proximity communication, it is not possible to achieve fairness of medium sharing when coexisting with wireless communication apparatuses of other wireless systems that cannot expect periodic transmission.

  An object of one aspect of the present invention is to provide a wireless communication device capable of realizing fair medium sharing when coexisting with wireless communication devices of other wireless systems.

  A wireless communication apparatus according to an embodiment of the present invention includes a holding unit, a selection unit, and a transmission / reception processing unit. The holding unit includes a first set including one or more types of frame intervals, and a frame interval of the same type in which the length of the frame interval of the same type as the type of frame intervals included in the first set is included in the first set. And a second set including one or more types of frame intervals longer than the first type of frame intervals included in the first set. And hold. The selection unit selects which of the first set and the second set is used for communication. The transmission / reception processing unit communicates with the first device using the first communication method using the frame interval of the first set or the second set according to the selection result of the selection unit.

The conceptual diagram of the one-to-one proximity communication system which concerns on this embodiment. 1 is a block diagram showing a wireless communication apparatus according to a first embodiment. The figure which shows an example of the frame exchange at the time of coexistence with the other system of the radio | wireless communication apparatus which concerns on 1st Embodiment. The figure which shows an example of an operation | movement sequence in case the access of an initiator and the preferential access in another system become simultaneous. The figure which shows an example at the time of changing a frame interval during frame transmission / reception. The figure which shows an example of the frame exchange of the radio | wireless communication apparatus which concerns on 2nd Embodiment. The figure which shows an example which transmits data from an initiator among the frame exchanges of the radio | wireless communication apparatus which concerns on 4th Embodiment. The figure which shows an example which transmits data from a responder among the frame exchanges of the radio | wireless communication apparatus which concerns on 4th Embodiment. The figure which shows the operation example at the time of coexistence with the radio | wireless communication apparatus of the one-to-one proximity communication system which concerns on 4th Embodiment, and the radio | wireless apparatus of another system. The figure which shows an example which transmits data from an initiator among the frame exchanges of the radio | wireless communication apparatus which concerns on 5th Embodiment. The figure which shows an example which transmits data from a responder among the frame exchanges of the radio | wireless communication apparatus which concerns on 5th Embodiment. The figure which shows an example of the frame exchange of the radio | wireless communication apparatus which concerns on 6th Embodiment. The figure which shows the example of a switch of the frame exchange set in the radio | wireless communication apparatus which concerns on 7th Embodiment. The figure which shows an example of the physical radio | wireless link cutting | disconnection in a one-to-one proximity communication system. The figure which shows an example of the general flame | frame exchange in a one-to-one radio | wireless communications system. The figure which shows an example of the frame exchange of the contention period in IEEE802.11 wireless LAN (Local Area Network).

Hereinafter, a wireless communication apparatus according to an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that, in the following embodiments, the same numbered portions are assumed to perform the same operation, and repeated description is omitted.
(First embodiment)
In the present embodiment, it is assumed that two wireless communication devices constitute a one-to-one proximity communication system. The one-to-one communication means that after establishing a connection with a certain wireless communication device, communication is performed only with the same wireless communication device until the connection is disconnected. Proximity communication is a communication method in which the communication range is extremely limited. For example, it is assumed that a wireless communication device existing in a communication range of several centimeters, such as a communication distance of 3 cm, can communicate. Note that when the wireless communication device includes an antenna, communication may be performed by bringing the devices into contact with each other.

  In the present embodiment, it is assumed that a radio communication system (hereinafter referred to as another system) using another communication method using a communication method different from the one-to-one proximity communication system coexists. “Coexistence” is, for example, a situation in which a radio signal from a radio communication device in a one-to-one proximity communication system can be detected by a radio communication device in a radio communication system having a wide communication range using another communication method. That is, communication in the one-to-one proximity communication system also affects, for example, interference, the wireless communication system having a wide communication range. In the present embodiment, such a situation is defined as “coexistence” with other systems. Although the details of the difference in the communication range will be described later, it is determined by the sum of the maximum transmission power and the antenna gain. Therefore, if the communication range of the one-to-one proximity communication system is narrower than the communication range of the other system, the sum of the maximum transmission power and the antenna gain in the one-to-one proximity communication system is the maximum transmission power and the antenna gain in the other system. Less than the sum of

A conceptual diagram of the one-to-one proximity communication system will be described with reference to FIG.
The proximity communication system 100 includes a wireless communication device 101 and a wireless communication device 102. In the example of FIG. 1, the wireless communication device 102 exists in the communication range 151 of the wireless communication device 101, and the wireless communication device 101 exists in the communication range 152 of the wireless communication device 102. Wireless communication can be performed with the device 102.
The procedure for establishing a connection for performing wireless communication, that is, the procedure for performing communication setting is a procedure for notifying each other of information necessary for realizing wireless communication so as to notify each other. The mutual information is, for example, an identifier (IDentifier: ID) of a wireless communication device or a corresponding version number when there are a plurality of versions as communication methods. Furthermore, in order to use it for determining whether or not another wireless communication device is a communication partner in light of consistency in a layer above this wireless access protocol layer, parameter information of an upper layer may be included.

When establishing a connection, one of the two wireless communication devices serves as an initiator and the other serves as a responder. The procedure for determining the relationship between the initiator and the responder is, for example, as follows.
The wireless communication apparatus 101 transmits a connection request frame to the wireless communication apparatus 102, and the wireless communication apparatus 102 receives the connection request frame. The wireless communication device 102 determines to accept the wireless communication device 101 as a connection partner, and transmits a connection acceptance frame for notifying that the wireless communication device 101 is a connection partner to the wireless communication device 101.
The wireless communication apparatus 101 receives the connection acceptance frame, determines to accept the wireless communication apparatus 102 as a connection partner, and transmits a response frame to the connection acceptance frame to the wireless communication apparatus 102 that is a communication partner. By this procedure, the connection between the wireless communication apparatus 101 and the wireless communication apparatus 102 is established. In such a connection establishment procedure, the wireless communication device that transmitted the connection request frame, that is, the wireless communication device 101 in this example, to the initiator, and the wireless communication device that transmitted the connection acceptance frame, that is, the wireless communication device 102 in this example, Become a responder.

Next, the wireless communication apparatus according to the first embodiment will be described with reference to FIG.
A wireless communication apparatus 200 according to the first embodiment includes an antenna 201, a frequency conversion unit 202, a PHY (PHYsical) processing unit 203, a parameter holding unit 204, a parameter selection unit 205, a transmission / reception processing unit 206, and an upper processing unit 207. .

  The antenna 201 is connected to a frequency conversion unit 202 described later, and receives a radio signal from the outside or transmits a radio signal to the outside. Since the antenna configuration may be a general configuration such as a dipole antenna or a patch antenna, detailed description thereof is omitted here. Since the wireless communication apparatus 200 according to the first embodiment can be configured as one apparatus including the antenna 201 by including the antenna 201, the mounting area can be reduced. Further, by sharing the antenna 201 for transmission and reception, the wireless communication device 200 can be reduced in size. In addition, although the antenna 201 shows one example here, multiple may be sufficient.

  In the case of reception processing, the frequency conversion unit 202 receives a radio signal from the antenna 201 and demodulates it into a baseband signal that can be processed by a PHY processing unit 203 described later. In the case of transmission processing, a physical packet is received from the PHY processing unit 203 and modulated to a radio signal in a frequency band for transmission, for example, a millimeter wave band of 60 GHz.

In the case of reception processing, the PHY processing unit 203 receives a baseband signal from the frequency conversion unit 202, and performs physical packet decoding processing on the baseband signal and processing for removing a preamble, a physical header, and the like. The PHY processing unit 203 extracts the payload part after these processes are performed as a frame. In the case of transmission processing, the PHY processing unit 203 receives a frame and a transmission instruction from the transmission / reception processing unit 206, performs processing such as encoding, and converts the frame into a physical packet.
The PHY processing unit 203 sends a physical packet reception start notification signal before sending the frame to the transmission / reception processing unit 206, and after sending the frame to the transmission / reception processing unit 206, the physical packet reception completion notification signal. Are sent to the transmission / reception processing unit 206. Further, notification of physical packet error detection and information on the status of the wireless medium are also sent to the transmission / reception processing unit 206.

  The parameter holding unit 204 holds two sets of parameters related to the frame interval. The frame interval indicates the time that is available before sending a frame. More specifically, the frame interval is determined after a frame is transmitted from its own device, after receiving a frame from a wireless communication device of the same system, after receiving a wireless signal from a wireless communication device of a different wireless system, or on a wireless medium. After detecting that the carrier is busy as a result of carrier sense and detecting that it has become idle again, it is the time that is available before transmitting a frame. If the operation that causes the carrier to be recognized as busy during frame transmission from its own device is included, in any of the above cases, the frame interval is finally detected as a result of carrier sense on the wireless medium. Is the time from when it is detected that the frame becomes idle again until the frame is transmitted.

The first set held by the parameter holding unit is a frame interval used in normal times, that is, when interference countermeasures are not required. Specifically, in the initiator interface space (InitIFS), responder interface space (RspIFS), and SIFS. is there. For example, this is called the first set. The second set is a frame interval used when interference countermeasures are required, and the frame interval length of the same type as the frame interval type included in the first set is the frame interval included in the first set. This is the length. This is defined as InitIFS_C, RspIFS_C, and SIFS_C. For example, this is called the second set. In addition, when providing ERIFS, ERIFS and ERIFS_C are similarly added to each set. The types of frames included in each set will be described later.
The parameter holding unit 204 may hold one set (InitIFS, RspIFS, and SIFS in the above example) and an offset value.

  The parameter holding unit 204 causes the transmission / reception processing unit 206 to use the set selected by the parameter selection unit 205 described later. That is, the transmission / reception processing unit 206 may refer to the set to be used, or the transmission / reception processing unit 206 may send a set to be used.

  The set held by the parameter holding unit 204 may be configured to be changed by the transmission / reception processing unit 206 or the parameter selection unit 205.

  The parameter selection unit 205 selects which of the sets related to the frame interval in the parameter holding unit 204 is used. When the parameter holding unit 204 holds one set and an offset value, the parameter selection unit 205 selects whether to use the offset value. The selection of the set is performed based on, for example, information on transmission errors such as the number of retransmissions and transmission failure acquired through the transmission / reception processing unit 206, and information on reception errors such that decoding cannot be performed or a carrier has been lost (missed). Alternatively, the set may be selected based on access-related information such as carrier sense busy time or time taken for actual transmission after preparing a transmission frame.

In other words, based on the above information, when a certain value is equal to or greater than the threshold value, it is assumed that another system exists or may exist in the vicinity, in other words, communication is affected or affected by the other system. The parameter selection unit 205 determines that it is necessary to avoid interference with other systems. For example, when the number of retransmissions is equal to or greater than a threshold, the parameter selection unit 205 may determine that countermeasures for interference and coexistence are necessary, and select the second set as the frame interval. The parameter selection unit 205 notifies the parameter holding unit 204 of the selected set so that the parameter holding unit 204 can grasp the set selected by the parameter selection unit 205.
Note that the parameter selection unit 205 may change the determination method according to an instruction from the host processing unit 207. That is, it is only necessary that the parameter selection unit 205 selects which set to be held by the parameter holding unit 204 is to be used, and the transmission / reception processing unit 206 can use the selected set to transmit / receive frames. The timing at which the transmission / reception processing unit 206 changes the set is the time when a data frame or a management frame is transmitted, that is, when the access right is acquired on the wireless medium.
The transmission / reception processing unit 206 handles the type of frame, data frame, control frame, and management frame used in the one-to-one proximity communication system, and uses either the first set or the second set of frame intervals from the parameter selection unit 205. Receive instructions. The transmission / reception processing unit 206 refers to the set of frame intervals held in the parameter holding unit 204, and uses the frame interval of either the first set or the second set to establish a radio link with another radio communication device. (Connection) is established and frame exchange is performed.

  Also, the transmission / reception processing unit 206 performs processing related to media access control (Media Access Control: MAC). For data frames, control of data frame transmission on the transmission side and on the reception side are performed so that the order of data transmission and the order of data reception coincide at the application layer level between wireless communication devices exchanging data. Processing with data rearrangement may be performed. Specifically, in the case of reception processing, the transmission / reception processing unit 206 receives a data frame from the PHY processing unit 203 and generates a response frame for delivery confirmation for the data frame. The transmission / reception processing unit 206 transmits a response frame to the PHY processing unit 203 after the end of reception of the physical packet including the data frame, with a short frame space (SIFS) period. The SIFS will be described later. Further, the transmission / reception processing unit 206 rearranges the received data frames as necessary, and extracts data from each data frame.

  On the other hand, in the case of transmission processing, the transmission / reception processing unit 206 receives data from a higher-level processing unit 207, which will be described later, and converts the data into a data frame. The transmission / reception processing unit 206 measures the transmission timing, and sends both the generated data frame and the transmission instruction to the PHY processing unit 203. At this time, the transmission / reception processing unit 206 may also perform instructions of modulation and coding methods necessary for transmission. If the generated frame is a frame subject to retransmission processing (data frame or management frame), it is determined that transmission has failed unless a response frame for the transmitted frame is started within a predetermined time after transmission. Will be resent. Since the processing related to these retransmissions is the same as a conventionally known technique, a description thereof is omitted here. When a response frame for the transmitted frame is received, it is determined that retransmission of the transmitted frame is unnecessary.

  In the case of reception processing, the host processing unit 207 performs processing such as receiving data from the transmission / reception processing unit 206 and inputting the data to the application. In the case of transmission processing, the upper processing unit 207 receives data to be transmitted from the application by a user operation or the like, and transmits the data to the transmission / reception processing unit 206.

  Further, in the wireless communication apparatus 200 according to the first embodiment, one PHY processing unit 203 and one transmission / reception processing unit 206 are provided. However, the present invention is not limited to this, and there may be a plurality of different PHY processing units, and there may be a transmission / reception processing unit corresponding to each, or there may be a common processing unit across different PHY processing units.

Next, an example of frame exchange when the wireless communication apparatus according to the first embodiment coexists with another system will be described with reference to FIG.
A sequence 300 of the wireless communication apparatus shown in FIG. 3 represents frame exchange between the initiator and the responder in time series, and the upper part of the time axis in FIG. 3 shows the operation of the wireless communication apparatus as the initiator. Shows the operation of the wireless communication apparatus as a responder.

There are three types of normal frame intervals used in the one-to-one proximity communication system: InitIFS, RspIFS, and SIFS. However, in order to distinguish from the case of other systems described later, here, SIFS is expressed as SIFS1 for convenience.
InitIFS is a frame interval that is freed when the initiator starts frame exchange. RspIFS is a frame interval that is opened when the responder starts frame exchange. SIFS1 is a frame interval used when a response frame that is a delivery confirmation for a data frame or a management frame is transmitted. The frame exchange is started, for example, by transmission of a data frame or a management frame, and is terminated upon receipt of a response frame that is a delivery confirmation for the data frame or the management frame. Assume that frame exchange fails unless a response frame is received.
For example, the minimum of InitIFS is 3.0 μs and it is sufficient if it is more than that, RspIFS is minimum 7.0 μs and it is only necessary that it is more than that, and SIFS1 is minimum 2.0 μs and the maximum is 2.5 μs. is there.

The normal InitIFS 301 has a minimum of 3 μs as described above, but in the first embodiment, the InitIFS 301 is used in a concept equivalent to PIFS, which is a frame interval prepared for preferential transmission in another system. Assume frame spacing. Therefore, the offset period 302 is added to the InitIFS 301 so that the period length of the frame interval is increased so that the period is the same as that of the PIFS. In the first embodiment, the offset period 302 is set to 5 μs so as to have the same period as PIFS (8 μs) of another system. Here, a frame interval obtained by adding an offset period 302 (5 μs) to InitIFS 301 is referred to as InitIFS_C303. Similarly, a frame in which the offset period 302 (5 μs) is added to the SIFS 305 is referred to as SIFS_C306.
The initiator transmits data (DATA1) 304 to the responder after the InitIFS_C303 period has elapsed. Thereafter, the responder that has received the data 304 transmits an ACK 307 to the initiator after the SIFS_C 306 period has elapsed.

In this way, the frame interval value used at the start of frame exchange at the initiator is matched with the frame interval (PIFS in the first embodiment) prepared for preferential transmission in another system. Thus, the access at the initiator and the preferential access at the other system are equivalent. Therefore, since the responder is inferior to the preferential access in the other system, it is possible to improve the situation where the initiator and the responder can advantageously start frame exchange at a short frame interval with respect to the wireless communication device of the other system. it can.
In FIG. 3, the case where the data frame is transmitted from the initiator has been described. However, the responder may similarly provide an offset. For example, an offset period of 5 μs may be added to RspIFS, RspIFS_C having a minimum period of 7 μs + 5 μs = 12 μs may be defined, and RspIFS_C may be used at the start of frame exchange.

Next, a sequence in the case where initiator access and preferential access in another system are performed simultaneously will be described with reference to FIG.
FIG. 4 shows the operation sequence of the wireless communication apparatus of the one-to-one proximity communication system according to the present embodiment in the upper part, and the operation sequence of the wireless apparatus in the other system in the lower part.
In step S401, the initiator and the wireless communication device of another system detect the end of carrier sense busy (that is, carrier sense has returned to idle). Here, the carrier sense busy is, for example, due to transmission in one of the wireless systems.

  In step S402, the initiator of the one-to-one wireless communication system according to the first embodiment frees the InitIFS_C period, and the wireless device of the other system frees the PIFS period.

  In step S403, the initiator and the wireless device of the other system transmit data frames (DATA1 and W_DATA1), respectively. Since InitIFS_C and PIFS have the same period of 8 μs, DATA1 and W_DATA1 collide, and the wireless communication device on the data frame receiving side (the wireless device that is the transmission destination of the data frame in the responder and other systems) is the data frame. Cannot be received or decoded. Therefore, the responder does not transmit ACK1 that is a response frame, and the wireless device that is the transmission destination of the W_DATA1 frame in another system does not transmit W_ACK1 that is a response frame.

In step S404, the wireless device on the data transmission side of the other system determines that there is no response frame as a result of the confirmation operation for the presence / absence of a response frame, and performs data frame retransmission processing. Here, it is assumed that DATA1 and W_DATA1 happen to occupy the same period. When an IEEE 802.11 wireless LAN (Local Area Network) system is assumed as another system, in a wireless device that transmits a data frame after the PIFS has elapsed, the presence / absence of a response frame is determined by transmitting the data frame W_DATA1 and the SIFS2 (3 μs ) Determination is made in the first half of the subsequent SLOT2 (5 μs) period. That is, if carrier sense busy is not detected during this period, a switching operation from reception to transmission is performed within the period of SLOT2, and retransmission of W_DATA1 is performed after the period of SLOT2. In other words, W_DATA1 is transmitted and SIFS2 + SLOT2 (that is, 8 μs) is performed, and W_DATA1 is retransmitted.
On the other hand, in the initiator of the one-to-one proximity communication system according to the present embodiment, the presence / absence of a response frame is determined after SIFS1_C (at least 7 μs) after adding a 5.0 μs offset period after transmitting the data frame DATA1. The presence / absence of ACK1 is determined within the slot time (shown here as SLOT1). SLOT1 is set to a period of 1.0 μs in common even when the frame interval is adjusted to be long as a countermeasure against interference even in a normal state. As one of the parameters related to the frame interval, an offset period of 5.0 μs is added in the same way as other frame intervals at the time of interference countermeasures, and newly defined as SLOT1_C (1.0 μs + 5.0 μs = 6.0 μs). You may make it use. In the example where the data frames shown in FIG. 4 collide, since the initiator does not receive ACK1 within a predetermined time, the state of carrier sense is confirmed again, and the operation shifts to the operation of retransmitting DATA1.

  In the case where the initiator operates after SLOT1 (1.0 μs) has elapsed, the InitIFS_C is re-opened after the SLOT1 has elapsed and DATA1 is retransmitted. In the example of FIG. 4, there is a transmission of W_DATA1 of another system. Subsequently, in another system, W_ACK1 is transmitted to SI_W1 after SIFS2 (3 μs) has elapsed. Further, when there is a data frame to be transmitted in another system, a series of frame exchanges such that the next data frame W_DATA2 is transmitted after SIFS2 of 3 μs if within the transmission burst time limit is assumed to be performed. Is done. In the meantime, the InitIFS_C carrier sense idle period cannot be obtained in the initiator, and DATA1 cannot be retransmitted until such a series of frame exchanges on the other system side is completed.

  In this way, the initiator access and the access using the preferential PIFS in the other system are the same when accessing the first medium, but the other system side is overwhelmingly advantageous in the recovery operation (that is, retransmission). . On the other hand, the InitIFS_C used when accessing the medium of the initiator is shorter than the frame interval (AIFS and DIFS used in normal operation or EIFS used when an error occurs) used during access other than the highest priority PIFS in other systems. This is advantageous for the initiator side. Further, since the frame interval RspIFS_C used at the time of access by the responder is 12 μs, it becomes shorter than any of the default values (described later) of the frame interval used at access other than PIFS in other systems, which is advantageous for the responder side.

  In the above-described example, an example of setting the offset period so that InitIFS_C and PIFS are equivalent to each other is shown. However, the present invention is not limited to this, and the offset period is set so as to be equivalent to other frame intervals. It may be set. For example, the offset period may be set so that InitIFS_C has an equivalent value for either AIFS or DIFS, which is used for contention in another system instead of PIFS and has a different value for each access category. Specifically, an offset period of 10 μs is added to InitIFS so that the default value (13 μs) of AC_VI / AC_VO, which is a type of AIFS, and InitIFS have the same period length, and other types used in the one-to-one proximity communication system An offset period of 10 μs may be added to each frame interval.

  According to the first embodiment described above, by adding an offset period considering the frame interval of another system to the frame interval of the one-to-one proximity communication system according to the present embodiment, Share a fair medium with the system. That is, the communication opportunity can be obtained in each wireless communication system without monopolizing the medium for a long period of time so that at least one wireless communication system is determined to be disconnected by the other wireless communication system.

(Second Embodiment)
In the first embodiment, the initiator and the responder respectively hold both the first set of IFS, which is a normal frame interval, and the second set of IFS, in which a fixed-length offset is added to all frame intervals. ing. Therefore, if the same set of frame intervals is not used, a shift occurs in the mutual IFS. In the second embodiment, when one of the initiator and the responder determines to set a longer frame interval, the other is notified that a longer frame interval set (set 2) is used. In this way, it is possible to dynamically switch between sets of the same frame interval between the initiator and the responder.

Here, an example of changing the frame interval during frame transmission / reception in the one-to-one proximity communication system according to the first embodiment will be described with reference to FIG.
FIG. 5 shows the operation sequence of the initiator in the upper part and the operation sequence of the responder in the lower part.
In the one-to-one proximity communication system, the timing for changing the frame interval set is when a data frame or a management frame is transmitted, that is, when an access right is acquired on a wireless medium. Therefore, the frame interval set must not be changed when a response frame to the received data frame or management frame is transmitted. Specifically, the frame interval may be changed from InitIFS to InitIFS_C in the initiator before the initiator transmits DATA1 to the responder. However, the responder must not change the frame interval from SIFS to SIFS_C when transmitting ACK, which is a response frame having received DATA1, to the initiator.

  In the example of FIG. 5, the initiator checks whether there is ACK1 from the responder within a period of SIFS1 (minimum 2.0 μs) + SLOT1 (1.0 μs) after transmitting DATA1. Therefore, even if the responder tries to send a response frame ACK1 after receiving DATA1 after SIFS1_C (minimum 7 μs), the initiator moves to retransmission processing assuming that the response frame ACK1 is not sent, and sets DATA1 to “SIFS1 + SLOT1 + InitIFS” (minimum 6 μs) to the responder.

  On the other hand, since the responder transmits ACK1 to the initiator by SIFS1_C, assuming that a switching time of 1.0 μs is required, even if the responder performs an operation of waiting for the result of carrier sense, the responder receives it after 6.0 μs has elapsed after receiving DATA1. That is, the carrier sense is stopped and the process proceeds to retransmit DATA1. Therefore, ACK1 is transmitted to the initiator after 7.0 μs without detecting the retransmitted DATA1 by carrier sense and waiting for transmission of ACK1. As a result, ACK1 and retransmitted DATA1 collide, and frame exchange between the initiator and the responder fails.

  When it is acceptable to change the frame interval set even when the response frame is transmitted, when changing from a short frame interval set to a long frame interval set, the frame exchange fails at least once Need to be considered as.

  Therefore, in the second embodiment, the initiator and the responder use the first set of frame intervals when establishing a connection, and if it is determined that one wireless communication device uses the second set of frame intervals after establishing the connection, Information that the second set is used in the data frame or the management frame that is transmitted after access using the two sets is added. For example, the transmission / reception processing unit 206 prepares 1 bit (hereinafter referred to as a notification bit) in the frame header of the data frame or the management frame. If “0”, the first set may be used, and if “1”, the second set may be used. The wireless communication device that has received this data frame determines which frame interval set is used by the wireless communication device of the communication partner from the state of the notification bit, and matches the frame interval set.

An example of frame exchange of the wireless communication apparatus according to the second embodiment will be described with reference to FIG.
The upper part shows the operation sequence of the initiator, and the lower part shows the operation sequence of the responder.
In step S601, the initiator transmits DATA1 to the responder after InitIFS using the first set of normal frame intervals, and the responder transmits ACK1 to the initiator after SIFS1 has elapsed. Here, since the initiator uses the first set of frame intervals, the notification bit indicating the set of frame intervals in DATA1 is set to “0”.
In step S602, the initiator uses the second set of frame intervals and transmits DATA2 to the responder after InitIFS_C has elapsed. Here, since the initiator uses the second set of frame intervals, the notification bit indicating the frame interval set is set to “1”.
In step S603, when the responder receives DATA2 and extracts the notification bit from DATA2, the responder recognizes that the value is set to “1” and uses the second set of frame intervals. Thereafter, ACK1 is transmitted to the initiator after SIFS_C has elapsed.

As shown in FIG. 6, it is desirable to use the second set of SIFS1_C from when the response frame is transmitted to the initiator. However, it may be difficult to immediately switch between SIFS1 and SIFS1_C by analyzing the contents of the data frame or the management frame (here, in particular, a notification bit related to the frame set). In particular, it is difficult to respond immediately when switching from a long set (second set) to a short set (first set).
In this case, in the frame exchange including the notification of switching of the first set, the previous old frame interval set may be used, and the new set may be used from the subsequent frame exchange. Also in the response frame, as described above, for example, a notification bit is prepared in the frame header, and a set of frame intervals to be used is notified.
By doing so, in the wireless communication device on the data frame and management frame transmission side, it is understood that the reception-side wireless communication device has recognized the change in the frame interval even if the response time has not yet been updated. Can do. Therefore, the updated frame interval set can be used in the subsequent frame exchange. In addition, by always using the notification bit regarding the frame interval set during subsequent frame exchanges, both wireless communication devices can operate using the same frame interval set while confirming the frame interval set. Can do.

  Although the operation using the first set by the initiator and the responder at the start of communication after establishing the connection has been described above, the frame interval may be adjusted at the time of establishing the connection. For example, when one of the wireless communication devices (the initiator or responder has not been determined since the connection has been established) uses the second set with a long frame interval at the time of searching for a wireless communication device to be a communication partner. Suppose. Here, for convenience, a wireless communication device that transmits a connection request frame is a first wireless communication device, and a wireless communication device that receives a connection request frame and transmits a connection acceptance frame is a second wireless communication device.

  When the first wireless communication device transmits a connection request frame to the second wireless communication device, a notification bit for notifying a set of frame intervals to be used is set in the header of the connection request frame, as in the case after the connection is established. It is only necessary to set and notify the second wireless communication apparatus that the second set is used by the notification bit. When receiving a connection request at the second wireless communication apparatus that has received the connection request frame, in order to notify that the second set is used in accordance with the first wireless communication apparatus that has transmitted the connection request frame, A similar notification bit is set in the header. Then, the first wireless communication apparatus is notified that the second set of frame intervals is to be used. In the first wireless communication device, when the connection with the second wireless communication device that has transmitted the connection acceptance frame is permitted, an acknowledgment frame for the connection acceptance frame is transmitted to the second wireless communication device. Therefore, the notification bit is also set in the header of the confirmation response frame, the confirmation response frame is transmitted to the second wireless communication device, and the second wireless communication device is notified that the second set of frame intervals is used for reconfirmation. To do.

  On the contrary, in the received connection request frame, the first set which is the default remains as it is, but when the second wireless communication apparatus determines to use the second set, the connection to be returned to the connection request frame Set the notification bit set in the reception frame header. Accordingly, it is possible to notify the first wireless communication apparatus that the second set is used. Thereafter, when the first wireless communication device permits connection with the second wireless communication device that has transmitted the connection acceptance frame, the confirmation response frame is transmitted to the second wireless communication device in response to the connection acceptance frame as described above. To do. Therefore, the notification bit set in the acknowledgment frame header is used to notify the counterpart wireless communication device that the second set of frame intervals is used in accordance with the wireless communication device that transmitted the connection acceptance frame.

  In this way, when one of the wireless communication devices determines that the longer frame interval set should be used before establishing the connection, the connection establishment procedure can be notified of the determination by the connection establishing procedure. It is possible to exchange frames immediately after establishing a connection using the same set of frame intervals.

  In the one-to-one proximity communication, there is a demand for completing connection establishment in as short a time as possible. As described above, since the number of frames transmitted in the connection establishment procedure is very small compared to the IEEE 802.11 wireless LAN assumed as another system, it can be said that the influence of interference on the other system at the time of connection establishment is extremely small. Further, as described above, transmission / reception of an acknowledgment frame is performed within a short fixed time, and there is a retransmission process based on the expected reception time. For these reasons, it is desirable to use the normal first set of frame intervals as the frame interval in the connection establishment procedure.

  According to the second embodiment described above, a set of frame intervals to be used can be recognized by including a bit indicating a change in the frame interval in a frame to be transmitted during frame transmission and reception. Thus, stable communication can be performed while changing the set of frame intervals.

(Third embodiment)
In the first and second embodiments, a predetermined value is used for the frame interval of the second set. In the third embodiment, the value of the frame interval of the second set can be set when establishing a connection. The point is different from the above-described embodiment.

  That is, an arbitrary frame interval value is set in a connection request frame or a connection acceptance frame that is a management frame used when establishing a connection. For example, if the frame interval value used as the second set can be added to the frame body portion, each frame interval value specifically used as the second set can be arbitrarily set when the connection is established. .

  In addition, when there are a plurality of candidates as assumed other systems, a set of frame intervals to be adjusted may be prepared for each candidate system, and the set may be used according to the candidate system. Specifically, for example, it may be prepared in the parameter holding unit 204, and when a system to be interfered is designated by the parameter selection unit 205, the predetermined set may be selected and used. When there are a plurality of other systems, the one-bit notification bit described in the second embodiment does not have enough information, and therefore a notification field that can represent all of a plurality of candidate target sets may be provided.

  According to the third embodiment described above, an arbitrary frame interval can be used by referring to the information on the value of the frame interval. In addition, when there are other system candidates other than the one-to-one proximity communication, it is possible to set a frame interval according to each system, and it is possible to share a more flexible medium.

(Fourth embodiment)
In the first embodiment and the second embodiment, since an offset is added to all frame intervals used in frame exchange, the same frame interval is set between the wireless communication devices connected when the response frame is transmitted and received. If the set is not used, proper frame transmission / reception cannot be performed. The fourth embodiment is different in that an offset is added only to a frame interval used when accessing a wireless medium when frame exchange is started.

  The configuration of the wireless communication apparatus according to the fourth embodiment is the same as that of the wireless communication apparatus 200 according to the first embodiment, but the set held in the parameter holding unit 204 is different.

  The parameter holding unit 204 holds (InitIFS, RspIFS, SIFS1) as the first set, and holds (InitIFS_C, RspIFS_C, SIFS1) as the second set.

Next, an example of frame exchange of the wireless communication apparatus according to the fourth embodiment will be described with reference to FIGS.
FIG. 7 assumes a case where the initiator accesses and transmits DATA1 to the initiator. The upper part shows the operation sequence of the initiator, and the lower part shows the operation sequence of the responder.

  In step S701, as in the first embodiment, it is assumed that the initiator uses a long frame interval (second set) in order to avoid interference. After that, instead of normal InitIFS (3 μs), for example, using InitIFS_C (8 μs) in which an offset period of 5 μs is added to InitIFS so as to be equivalent to PIFS (8 μs) of another system, wait until InitIFS_C has elapsed. .

  In step S702, the initiator transmits DATA1 to the responder after InitIFS_C has elapsed.

  In step S703, with respect to the frame interval used in the frame exchange, the normal SIFS1 is used as it is without adding an offset period. Therefore, when the responder receives DATA1, ACK1 is transmitted to the initiator after SIFS1 has elapsed since the reception of DATA1 was completed.

Next, FIG. 8 shows a case where the responder accesses and transmits DATA1. The upper row shows the responder transmission frame, and the lower row shows the initiator transmission frame.
In step S801, the responder sets a frame interval that is the same as the default minimum value of the frame interval AIFS used for the contention period in the other system, 13 μs (default value for AC_VI and AC_VO). Specifically, the responder waits until RspIFS_C elapses using RspIFS_C (13 μs) obtained by adding an offset period of 6 μs to normal RspIFS (7 μs). In this way, the frame interval at the time of access used by the responder can be matched with another type of frame interval of another system.

  In step S802, the responder transmits DATA1 to the initiator after RspIFS_C has elapsed.

  In step S803, the initiator uses the same value for the frame interval used in the frame exchange as in the case shown in FIG. 7, and transmits ACK1 to the responder after SIFS1 has elapsed.

  7 and 8 show an example in which the initiator and the responder match the access frame interval to the PIFS of the other system and the minimum AIFS by default. However, the combination of frame intervals of other systems is not limited to this, and may be adjusted to the default minimum AIFS and the second shortest AIFS by default.

As described above, frames can be transmitted / received between wireless communication apparatuses even if the set of frame intervals used for frame exchange is not equivalent. For example, it is assumed that the wireless communication apparatus that has been determined to change the frame interval for coexistence with another system is the initiator.
As shown in FIG. 7, the initiator accesses the responder with InitIFS_C (8 μs). On the other hand, since the responder has not yet reached the determination to change the frame interval at that time, the responder accesses the initiator with normal Rsp IFS (7 μs). In this case, the responder can preferentially access. However, in one-to-one proximity communication, if one wireless communication device (here, the initiator) can grasp the situation where it interferes with another system, the other wireless communication device (here, the responder) naturally has the same situation. It is assumed that Accordingly, if the switching determination of the frame interval used by each wireless communication apparatus can be performed appropriately, the other wireless communication apparatus also performs the switching determination of the frame interval within a certain period. Therefore, in the above-described example, it is considered that the responder also performs the access as shown in FIG. 8 by making a determination to use RspIFS_C, and finally the power relationship of the access opportunity is maintained between the initiator and the responder.

  As shown in the second embodiment, information about the frame interval used by one of the wireless communication apparatuses (the first set or the second set, ie, the normal frame interval or the frame interval adjusted for coexistence) ) May be notified to the wireless communication apparatus of the communication partner in a frame header, for example.

  Next, the operation at the time of coexistence of the wireless communication device of the one-to-one proximity communication system according to the fourth embodiment and the wireless communication device of another system will be described with reference to FIG. Here, for example, it is assumed that the initiator matches the frame interval PIFS when performing preferential transmission in another system.

  Since the processing from step S401 to step S403 is the same as that in FIG. 4, description thereof is omitted here.

  In step S901, the initiator determines that there is no ACK1 transmission after a period of SIFS1 (2 μs) + SLOT1 (1 μs) after transmission of DATA1, and retransmits DATA1 after waiting for an idle period of InitIFS_C (8 μs). And

However, in step S902, the wireless device of the other system retransmits W_DATA1 after a period of SIFS2 (3 μs) + SLOT2 (5 μs) after transmitting W_DATA1 as in FIG. 4 in the first embodiment.
Therefore, the initiator detects the W_DATA1 signal by carrier sense, and postpones the retransmission of DATA1. Similar to the first embodiment, the access of the initiator and the access using the preferential frame interval (PIFS) in the other system have the same opportunity at the time of accessing the first medium, but the recovery operation ( In other words, in the retransmission, the other system side is overwhelmingly advantageous.

  On the other hand, it is assumed that the responder adjusts the frame interval used for access so as to be equivalent to the default minimum value (13 μs) of the frame interval AIFS used in the contention period in other systems. In other systems, a random back-off period is further provided after AIFS. The wireless device of another system cannot access unless it is carrier sense idle during these periods. Therefore, the responder has an equivalent access time to the wireless device of the other system that uses AIFS for the frame interval of the access to the other system, but it is probabilistically advantageous because the random back-off period is not provided. This is the same even if it compares by the operation | movement of a resending process. On the other hand, responders are overwhelmingly disadvantageous for access using preferential PIFS in other systems. Therefore, it is possible to share the medium fairly between the one-to-one proximity communication system and other systems.

  If the initiator and responder are set to match the frame interval to the minimum and default AIFS of the other system, respectively, both the initiator and responder will have a preferential PIFS in the other system. This is overwhelmingly disadvantageous for wireless devices that use. However, it is probabilistically advantageous for a wireless device in which an initiator operates in a competing period in another system, and a responder is relatively advantageous because a random backoff period is not provided.

  According to the fourth embodiment described above, an offset is added only to the frame interval used when accessing the wireless medium when starting frame exchange, and the frame interval during frame exchange is equal to the length of the normal frame interval. This makes it possible to share a fair medium with other systems.

(Fifth embodiment)
In a one-to-one proximity communication system, random backoff is not performed, and therefore a wireless communication apparatus in a one-to-one proximity communication system is stochastically set to a frame interval equal to a fixed-length frame interval used when accessing a medium in another system. This is advantageous in frame transmission. Therefore, in the fifth embodiment, when adjusting the frame interval, in addition to making it equal to any frame interval used in the competing period in the other system, an average random backoff period in the other system is further set. To do. This makes it possible to achieve fairness of access opportunities in consideration of the random backoff period in other systems.

Next, FIG. 10 and FIG. 11 show an example of frame exchange of the wireless communication apparatus according to the fifth embodiment.
FIG. 10 assumes a case where the initiator accesses and transmits DATA1 to the responder. The upper part shows the operation sequence of the initiator, and the lower part shows the operation sequence of the responder.

Assume that the initiator determines that it is better to use a longer frame interval in consideration of interference with other systems. At this time, the normal InitIFS has a 5 μs offset period (also referred to as a first offset period) for the same period as the PIFS of the other system, and a period (second offset period) assuming a random backoff of the other system. InitIFS_C to which is added) is defined. In the example of FIG. 10, the second offset period is a period that is half the default minimum CW (Contention Window) time width in another system. For example, in the case of an IEEE 802.11 wireless LAN system, the default value of CW is the minimum value 3 in CWmin of AC_VO. When transmitting a data frame classified as AC_VO, a wireless communication device of another system waits for a time obtained by multiplying a random number between 0 and 3 by a slot time (SLOT2). Therefore, the average of random numbers in AC_VO is 3/2 = 1.5, and 7.5 μs obtained by multiplying this by the time of SLOT2 (5 μs) is the average random backoff time. That is, the calculated value is a half value of the CW time width (3 × 5 = 15 μs). In the fifth embodiment, the above-described 7.5 μs is the second offset period, and InitIFS_C is 15.5 μs. Defined.
Subsequent communication between the initiator and the responder is the same as in the fourth embodiment, and a description thereof will be omitted.

Next, FIG. 11 shows a case where the responder accesses and transmits DATA1 to the initiator. In FIG. 11, the upper part shows the responder operation sequence, and the lower part shows the initiator operation sequence.
As in the fourth embodiment, the responder adds an offset period (first offset period) of 6 μs to RspIFS (7 μs) so as to be equivalent to the AIFS that is the minimum value by default in other systems. Similarly, a second offset period of 7.5 μs is added. Therefore, RspIFS_C is 20.5 μs. Subsequent communication between the initiator and the responder is the same as in the fourth embodiment, and a description thereof will be omitted.

  As shown in FIG. 10 and FIG. 11, the initiator can be disadvantageous at the time of initial access compared to the priority access at other systems. In addition, for the access in AC_VO and AC_VI during the contention period in the other system, since the AIFS of the other system is 13 μs by default, InitIFS_C (15.5 μs) may be lost probabilistically. . On the other hand, the responder is disadvantageous for preferential access in other systems, and at the default value level, it is also disadvantageous for access in AC_VO and AC_VI during the contention period in other systems. In addition, the responder is at a somewhat advantageous level for AC_BE and AC_BK.

  In addition, although the example which adds the value of the half of CW time width corresponding to default CWmin of AC_VO in another system was demonstrated, it is not restricted to this, You may use CW time width in another frame interval. For example, in the responder, a value 17.5 μs which is a half of the CW time width (7 × 5 = 35 μs) corresponding to the default CWmin of AC_VI may be added to the RspIFS as the second offset period. As described above, an offset time assuming a random backoff may be further different between the initiator and the responder.

  10 and 11 show a method of adding an offset time assuming a random backoff in another system to the fourth embodiment, but the present invention is not limited to this. For example, as in the first embodiment, after adding a fixed-length offset to all frame intervals so as to be equal to the frame interval of the other system, the frame interval used at the time of access is a random back in the other system. An offset time assuming OFF may be further added.

  According to the fifth embodiment described above, by adding an offset period assuming a random back-off to the frame interval of the one-to-one proximity communication system, it is more fair to other systems having a random back-off. Shared media access.

(Sixth embodiment)
By adjusting the frame interval long in the wireless communication device of the one-to-one proximity communication system, it is easy to transfer the access right of the wireless medium to the wireless communication device of another system. However, depending on the wireless device of the other system, specifically the access category of the frame to be transmitted, as long as the frame transmission request continues in any one of the one-to-one proximity communication systems, the wireless device of the other system transmits the frame. There may be situations where it is not possible. Therefore, in the sixth embodiment, when the access right is acquired once and then continuously acquired for a certain period, the access attempt is temporarily suspended. By doing so, wireless communication devices of other communication systems can always obtain transmission opportunities.

The wireless communication apparatus according to the sixth embodiment has the same configuration as the wireless communication apparatus according to FIG. 1, but the operations of the transmission / reception processing unit 206 and the parameter selection unit 205 are different.
The transmission / reception processing unit 206 measures a period (hereinafter referred to as a continuous period) in which the own apparatus has continuously acquired the access right after acquiring the access right. When the continuous period becomes equal to or greater than a threshold value (here, the T_burst period), the parameter selection unit 205 is notified.
The parameter selection unit 205 selects a frame interval (T_pause) for stopping an access attempt for a certain period. Based on the frame interval received from the parameter selection unit 205, the transmission / reception processing unit 206 adds a certain period (T_pause) to the frame interval and stops frame transmission.

Next, an example of frame exchange of the wireless communication apparatus according to the sixth embodiment will be described with reference to FIG.
In FIG. 12, the upper part shows the operation sequence of the initiator, and the lower part shows the operation sequence of the responder. In the case of a responder, InitIFS_C shown in FIG. 12 may be replaced with RspIFS_C, and similar processing may be performed.

  Specifically, the continuous period 1201 detects that the initiator is carrier sense busy while receiving the response frame from the responder and waiting for the period of InitIFS_C from the time when the initiator first acquired the access right with InitIFS_C. This is the period until In other words, it is assumed that the period during which the response frame from the responder is received and the access right is continuously acquired again by InitIFS_C is in a continuous period.

  As shown in FIG. 12, the initiator acquires the access right after InitIFS_C has passed, and transmits DATA1 to the responder. The responder receives DATA1 and returns ACK1 to the initiator. By continuing such processing, the initiator transmits DATAn to the responder after InitIFS_C has elapsed. At this time, if the frame transmission process in the one-to-one proximity communication system continues beyond a certain period (T_burst), the initiator waits until the next access attempt for a certain period (T_pause) after receiving ACKn from the responder.

  In the one-to-one proximity communication system, there is a method of sending a frame for confirming whether a communication partner wireless communication apparatus still exists if there is no frame exchange for a certain period, and disconnecting if there is no response. This period is T_keepalive. If the one-to-one proximity communication system uses this method, it is necessary to make the T_pause period shorter than the period T_keepalive used for existence confirmation.

The timing at which the initiator or responder transitions to the T_pause period after the elapse of the T_burst period is when the frame is transmitted and when the response frame for the transmitted frame is received or within a fixed time for confirming the presence or absence of the response frame. It may be when it is determined that there is no. Thereafter, the timing of the access attempt after the T_burst period at the initiator has elapsed is after the T_pause + InitIFS_C period has elapsed.
The period of T_pause + InitIFS_C may be defined as InitIFS_C_S.

  In the parameter holding unit 204, the frame interval at the time of access at the start of the continuous time and within the continuous time is set to the same value in the first set at normal time, and for example, InitIFS is stored in the initiator and RspIFS is stored in the responder. In the second set compatible with other systems, InitIFS_C_S and InitIFS_C_S may be stored for the initiator, and InitIFS_C and RspIFS_C_S (T_pause + RspIFS) may be stored for the responder, respectively. As a value of T_pause, a value of an average random backoff period in another system may be used.

  In the above example, it is assumed that the T_pause period is also one type of frame interval and carrier sense is performed during the T_pause period. However, T_pause may be a simple access pause period. In this case, carrier sense is not performed during the T_pause period, and carrier sense may be performed from the subsequent access. At this time, the frame interval set stored in the parameter holding unit 204 may not store a value corresponding to the concept of T_pause. For example, when the transmission / reception processing unit 206 receives a notification from the parameter selection unit 205 indicating that the second set is to be used, the continuous period is measured, and when the continuous period becomes equal to or greater than T_burst, until T_pause elapses. A waiting process may be performed.

Here, it is assumed that the continuous period has ended even if an error occurs. However, if it can be determined that the wireless signal is carrier sense busy in the one-to-one proximity communication system, the continuous time may be continued. The case where it can be determined that the carrier sense is busy is specifically the case where, for example, a radio signal is received and the preamble of the PHY packet can be detected correctly.
The example in which the initiator and the responder grasp and manage the continuous time has been described, but the continuous time is continued when it can be determined that the wireless signal is carrier sense busy in the one-to-one proximity communication system. In this way, the continuous time of the entire one-to-one proximity communication system can be managed and controlled, and fairness of medium sharing between systems can be achieved.

  According to the sixth embodiment described above, when the wireless communication device continues to acquire the access right for a certain period of time, the wireless communication device of another communication system is temporarily suspended by temporarily suspending the access attempt. The device can always obtain a transmission opportunity, and can achieve fairness of sharing of medium access.

(Seventh embodiment)
The seventh embodiment is different from the other embodiments in that the frame interval set is switched according to the period.
FIG. 13 shows an example of frame interval set switching in the wireless communication apparatus according to the seventh embodiment.
The initiator and the responder communicate with each other by alternately setting a first set, which is a normal frame interval, and a second set, which is a frame interval when other systems coexist. Here, the first set is used in the normal frame interval use period 1301, and the second set is used in the coexistence frame interval use period 1302.

  The wireless communication apparatus according to the seventh embodiment has the same configuration as that of the wireless communication apparatus according to FIG. 1, but the operations of the transmission / reception processing unit 206, the parameter holding unit 204, and the parameter selection unit 205 are different.

  The parameter holding unit 204 sets a time T_gen to determine the end of the normal frame interval use period 1301, and sets and holds the time T_coex to determine the end of the coexistence frame interval use period 1302.

  When the parameter selection unit 205 determines that coexistence with another system is necessary, the parameter selection unit 205 instructs the transmission / reception processing unit to perform time management of T_gen and T_coex.

The transmission / reception processing unit 206 performs frame transmission processing with reference to the frame interval of the first set or the second set from the parameter holding unit 204 as the time of T_gen or T_coex elapses.
Alternatively, when the parameter selection unit 205 determines that coexistence with another system is necessary, the time management of T_gen and T_coex is performed, and when either time of T_gen or T_coex elapses, the parameter selection unit 205 transmits and receives The processing unit 206 may be instructed to refer from the parameter holding unit 204 to a set of frame intervals to be used in the next frame interval usage period.

  In order to recognize T_gen and T_coex as a common value between the initiator and the responder, for example, the T_gen and T_coex may be set as a system in advance, or may be determined when the connection is established. In addition, T_gen and T_coex are time-managed in an independent and distributed manner by the initiator and the responder, respectively, but there is no condition that one access succeeds continuously as in the continuous time in the sixth embodiment. Therefore, what is necessary is just to observe the period using the frame interval of the 1st set or the 2nd set within a wireless communication apparatus.

  In order to achieve fair sharing of media with other systems as a whole system, a frame header is used to notify the set of frame intervals used in the current frame from one to the other. In this way, the timing of T_gen and T_coex can be matched between the initiator and the responder.

  Further, a case is assumed in which the above-described one-to-one proximity communication system uses a method of transmitting a confirmation frame if there is no frame exchange during T_keepalive, and disconnecting if there is no response as a result. In this case, depending on the setting of the second set, it may be difficult to realize communication in the one-to-one proximity communication system in the coexistence frame interval use period 1302, so the coexistence frame interval use period 1302 is shorter than T_keepalive. It is preferable.

  According to the seventh embodiment described above, the wireless communication device of the one-to-one proximity communication system can statistically share the medium with the wireless devices of other systems on the time axis.

(Eighth embodiment)
In the above-described embodiment, a system different from the one-to-one proximity communication system, for example, an IEEE 802.11 wireless LAN using CSMA / CA is assumed as the other system. The eighth embodiment is different in that the same one-to-one proximity communication system is present in the vicinity and interferes. CSMA / CA performs carrier sense to observe whether another wireless device is transmitting on the medium, that is, the frequency channel. As a result, when it recognizes that another wireless device is transmitting, it waits for a random time from the end of the transmission. Transmission (random access). This random access is an operation corresponding to Carrier Aviation (CA).

In this case, when the wireless communication apparatus determines that another system exists in the vicinity and needs an operation for coexistence, as in the seventh embodiment, the normal frame interval use period T_gen and the coexistence frame interval use period An operation for selectively using T_coex is performed.
Here, the other system may be a case where it is understood that it is another one-to-one proximity communication system, or may be a case where it is determined that there is a possibility of another one-to-one proximity communication system. Further, the type of other system is not limited, but in that case, it is the same as in the seventh embodiment.
In the normal frame interval use period, the first set of frame intervals is used as in the first to seventh embodiments. In the coexistence frame interval use period, the second set shown in any of the first to sixth embodiments may be used, but the present invention is not limited to this. That is, it is only necessary that the second set is set so that the frame interval at the time of access is more disadvantageous than when the first set is used, that is, longer.

When the second set described in any of the first to sixth embodiments is used as the second set, the medium is shared with the one-to-one proximity communication system as another system. However, even when sharing media with different systems, fair sharing can be achieved without distinction.
The second set is adjusted so that the frame interval at the time of access is more disadvantageous than that at the time of using the first set, that is, the frame interval becomes longer, and is defined to have a minimum difference in length. For example, since the carrier sense cannot be performed during the transmission / reception switching time, the difference is defined to be larger than the time. By doing so, it is possible to create a situation suitable for coexistence between the one-to-one proximity communication systems while suppressing a useless no-signal period, that is, an efficient coexistence state between the one-to-one proximity communication systems.

Specifically, for example, when two one-to-one proximity communication systems exist in the interference area of each other, the initiator that transmits in T_gen has the highest priority, and the next responder that transmits in T_gen. It is sufficient that there is a difference in the frame interval at the time of access in four stages so that the initiator that transmits in T_coex and the responder that transmits in T_coex have the lowest priority. Alternatively, the initiator transmitting in T_gen has the highest priority, the initiator transmitting next in T_coex, the responder transmitting in T_gen next, and the responder transmitting in T_coex having the lowest priority. As described above, there may be a difference in frame intervals at the time of access in four stages.
According to the eighth embodiment described above, each wireless communication device operates by switching between T_gen and T_coex in an autonomous and distributed manner, so that the wireless device of other systems is statistically shared on the time axis. Can be fair. Also, a set of frame intervals used in the current frame is notified from one wireless communication device in the same system to the other, and the timing of T_gen and T_coex is matched between the initiator and the responder. It is possible to achieve fairness in sharing the medium with the one-to-one proximity communication system.

(Ninth embodiment)
In the above-described embodiment, the one-to-one proximity communication system performs CSMA, but does not perform Carrier Aviation at least after connection establishment. In the ninth embodiment, Carrier Aviation is not performed during a normal operation that does not consider fair sharing of media with other systems, but Carrier Avidance is performed when there is interference from other systems. The Carrier Avoidance may perform the same operation as, for example, random access in an IEEE 802.11 wireless LAN.

The configuration of the wireless communication apparatus according to the ninth embodiment is the same as that in FIG. 1, but the operations of the parameter holding unit 204 and the transmission / reception processing unit 206 are different.
The parameter holding unit 204 holds only the first set.
When there is an instruction from the parameter selection unit 205 that coexistence with another system is required, the transmission / reception processing unit 206 is a value generated by a random function in addition to the frame interval (InitIFS or RspIFS) used during access of the first set during access The carrier sense is performed only for a time obtained by adding a value obtained by multiplying the first set slot time (Slot 1).
For the operation when it is detected that the carrier sense is busy before frame transmission, the operation in the existing system using random access may be referred to. If random access is performed by frame transmission at the time of connection establishment, a random function used at that time may be used, and a detailed operation for random access may be performed by the method at the time of connection. When there is no instruction that coexistence with other systems is necessary, the transmission / reception processing unit 206 uses only the first set as in the first to ninth embodiments.

  Further, by limiting the generation range of random values (the number of random functions to return between 0 and how many), it is possible to optimize the coexistence between the one-to-one proximity communication systems. .

  The parameter holding unit 204 also holds the second set, taking into account other assumed systems. For example, as the second set, the frame interval at the time of access is longer than that of the first set (InitIFS_C, RspIFS_C), and the slot time (Slot1_C). In addition, when there is an instruction that coexistence with other systems is required, the second set is used, and the value generated by the random function is multiplied by the second set slot time (Slot1_C) at the time of access. If the carrier sense is performed only for the time when the value is added, it is possible to achieve fairness of the medium with different systems.

  According to the ninth embodiment described above, by performing CSMA / CA, it is possible to achieve fairness in sharing a medium with a wireless device of another system, as in the above-described embodiment.

(Tenth embodiment)
In the tenth embodiment, a buffer is provided in addition to the configuration of the wireless communication apparatus of FIG. As described above, by including the buffer in the wireless communication apparatus, it is possible to hold the transmission / reception frame in the buffer, and it is possible to easily perform the retransmission process and the external output process.

(Eleventh embodiment)
In the eleventh embodiment, in addition to the configuration of the wireless communication apparatus according to the tenth embodiment, a bus, a processor unit, and an external interface unit are provided. The processor unit and the external interface unit are connected to the buffer via the bus. Firmware operates in the processor unit. As described above, by configuring the firmware to be included in the wireless communication device, it is possible to easily change the function of the wireless communication device by rewriting the firmware.

(Twelfth embodiment)
In the twelfth embodiment, a clock generation unit is provided in addition to the configuration of the wireless communication apparatus of FIG. The clock generation unit generates a clock and outputs the clock from the output terminal to the outside of the wireless communication device. Thus, the host side and the wireless communication apparatus side can be operated in synchronization by outputting the clock generated inside the wireless communication apparatus to the outside and operating the host side with the clock output to the outside. It becomes possible.

(13th Embodiment)
The thirteenth embodiment includes a power supply unit, a power supply control unit, and a wireless power supply unit in addition to the configuration of the wireless communication apparatus in FIG. The power supply control unit is connected to the power supply unit and the wireless power supply unit, and performs control to select a power supply to be supplied to the wireless communication device. As described above, by providing the wireless communication apparatus with the power supply, it is possible to perform a low power consumption operation by controlling the power supply.

(Fourteenth embodiment)
In the fourteenth embodiment, in addition to the configuration of the wireless communication apparatus according to the thirteenth embodiment, an NFC (Near Field Communications) transmission / reception unit is added and connected to the power supply control unit and the transmission / reception processing unit 206. As described above, by configuring the NFC transmission / reception unit in the wireless communication device, authentication processing can be easily performed, and power consumption is controlled by using the NFC transmission / reception unit as a trigger, thereby reducing power consumption during standby. Can be achieved.

(Fifteenth embodiment)
The fifteenth embodiment includes a SIM card in addition to the configuration of the wireless communication apparatus according to the thirteenth embodiment. The SIM card is connected to the transmission / reception processing unit 206. As described above, by adopting a configuration in which the SIM card is provided in the wireless communication device, authentication processing can be easily performed.

(Sixteenth embodiment)
In the sixteenth embodiment, in addition to the configuration of the wireless communication apparatus according to the eleventh embodiment, a moving image compression / decompression unit is included. The moving image compression / decompression unit is connected to the bus. As described above, by providing the wireless communication device with the moving image compression / decompression unit, it is possible to easily transmit the compressed moving image and expand the received compressed moving image.

(Seventeenth embodiment)
In the seventeenth embodiment, an LED unit is included in addition to the configuration of the wireless communication apparatus of FIG. The LED unit is connected to the transmission / reception processing unit 206 or the PHY processing unit 203. In this way, by providing the wireless communication device with the LED unit, it is possible to easily notify the user of the operating state of the wireless communication device.

(Eighteenth embodiment)
The eighteenth embodiment includes a vibrator unit in addition to the configuration of the wireless communication apparatus of FIG. The vibrator unit is connected to the transmission / reception processing unit 206 or the PHY processing unit 203. As described above, by providing the radio communication device with the vibrator unit, it is possible to easily notify the user of the operation state of the radio communication device.

(Nineteenth embodiment)
In the nineteenth embodiment, in addition to the configuration of the wireless communication apparatus in FIG. 2, a plurality of different PHY processing units 203 are provided, and a wireless switching unit is included. The radio switching unit is connected to a plurality of different PHY processing units 203 and switches between communication by different PHY processing units 203. As described above, by providing the wireless communication apparatus with a plurality of different PHY processing units 203, it is possible to switch to communication using an appropriate PHY processing unit 203 depending on the situation.

(20th embodiment)
In the twentieth embodiment, in addition to the configuration of the wireless communication apparatus in FIG. 2, a plurality of different PHY processing units 203 are provided, and a transmission / reception processing unit 206 corresponding to each of these PHY processing units 203 is provided, and a wireless switching unit including. The wireless switching unit is connected so that the transmission / reception processing unit 206 can be switched, and switches between a plurality of communication schemes by different transmission / reception processing units 206 and PHY processing units 203. One of the pair of the transmission / reception processing unit 206 and the PHY processing unit 203 corresponds to, for example, a wireless LAN. In this way, by setting the wireless communication apparatus to include a plurality of sets of different transmission / reception processing units 206 and PHY processing units 203, an appropriate set of transmission / reception processing units 206 and PHY processing units 203 was used according to the situation. It is possible to switch to communication. Further, a parameter holding unit 204 and a parameter selection unit 205 may be provided corresponding to each transmission / reception processing unit 206. In this way, by setting the wireless communication device to include a set of a plurality of different transmission / reception processing units 206, parameter holding unit 204, parameter selection unit 205, and PHY processing unit 203, an appropriate transmission / reception processing unit 206 according to the situation, It is possible to switch to communication using a set of the parameter holding unit 204, the parameter selection unit 205, and the PHY processing unit 203.

(21st Embodiment)
The twenty-first embodiment includes a switch (SW) in addition to the configuration of the wireless communication apparatus according to the nineteenth embodiment. The switch is connected to the antenna 201, a plurality of different PHY processing units 203, and a wireless switching unit. As described above, by providing the switch in the wireless communication device, it is possible to switch to communication using the appropriate PHY processing unit 203 according to the situation while sharing the antenna 201.

(Twenty-second embodiment)
The twenty-second embodiment includes a switch (SW) in addition to the configuration of the wireless communication apparatus according to the twentieth embodiment. The switch is connected to the antenna 201, the transmission / reception processing unit 206, and the wireless switching unit. As described above, the switch is provided in the wireless communication device, so that an appropriate transmission / reception processing unit 206 (and the parameter holding unit 204 and the parameter selection unit 205 are also included in each transmission / reception processing unit 206 while sharing the antenna according to the situation. It is possible to switch to communication using a set of the PHY processing unit 203.

Here, the communication range in the wireless communication apparatus according to the above-described embodiment will be described.
The communication range is mainly determined by transmission power and antenna gain. When a certain wireless communication device (first wireless communication device) transmits a wireless signal of an arbitrary frequency with a certain transmission power, it is assumed that it has a transmission antenna gain depending on the direction. In addition, it is assumed that the other wireless communication device (second wireless communication device) that receives this wireless signal has a receiving antenna gain that depends on the direction. The reception power of the radio signal at the second radio communication device at a certain distance and in a certain direction from the first radio communication device is statistically the transmission power, frequency, distance between the radio communication devices, and the first radio communication device side in that direction. And the receiving antenna gain on the second wireless communication apparatus side in that direction.

  The statistical power attenuation from the transmission power can be obtained from the distance between the wireless communication devices and the frequency used by the wireless signal. The higher the frequency used, the greater the attenuation. Receiving power can be rephrased in decibel notation as the sum of transmission power and transmission / reception antenna gain minus this attenuation. The error rate at the time of decoding a radio signal, and hence the error rate of a frame extracted from the payload of a physical (PHY) packet reproduced by decoding, depends on the reception power of the radio signal. That is, since the error rate increases as the received power decreases, the range in which wireless communication can be established, that is, the communication range is derived.

In this manner, the communication range of a radio signal using a certain frequency can be limited by the transmission power and the transmission / reception antenna gain. Further, in order to more actively limit the communication range, it is only necessary to perform the decoding process only on a radio signal having a received power of a certain value or more. For example, in FIG. 1, the wireless communication device 101 and the wireless communication device 102 limit transmission power to 0 dBm and perform transmission / reception with an omnidirectional antenna (that is, the antenna gain for transmission / reception is 0 dB each) for convenience of examination. Further, assuming that a 60 GHz millimeter-wave band is used and, as a result, a reception power of −48 dBm is obtained at a distance of about 3 cm, the decoding process can be set only when a radio signal having a reception power of −48 dBm or more is received. .
Of course, it is assumed that there are one or more modulation and coding schemes (MCS) in which the decoding process can be performed above the reference value of the reception power for performing the decoding process. That is, it is assumed that there is one or more MCSs whose minimum reception sensitivity is equal to or less than the reference value of the reception power.

  Since a decoding process is not performed for a radio signal that is lower than the received power reference value for performing this decoding process, the received power reference value is set to the carrier sense level, and a carrier signal is busy for a radio signal that is equal to or higher than the received power reference value. The carrier may be recognized as idle with respect to radio signals less than that. In this way, the communication range of a radio signal when using a certain frequency can be limited by the transmission power, the transmission / reception antenna gain, and the reference value of the reception power decoding process. In other words, if the reference value of the reception power decoding process and the carrier sense level are made the same, the communication range of the radio signal when using a certain frequency may be limited by the transmission power, the antenna gain of transmission and reception, and the carrier sense level. it can.

Next, frame types in a general communication system will be described.
In general, frames handled on a radio access protocol in a communication system are roughly classified into three types: a data frame, a management frame, and a control frame. These types are usually indicated by a header portion provided in common between frames. As a display method of the frame type, three types may be distinguished by one field, or may be distinguished by a combination of two fields.

  The management frame is a frame used for managing a physical communication link with another wireless communication apparatus. For example, there are a frame used for setting communication with another wireless communication device, a frame for releasing a communication link (that is, disconnecting), and a frame related to a power saving operation in the wireless communication device. .

  The data frame is a frame for transmitting data generated inside the wireless communication device to the other wireless communication device after establishing a physical communication link with the other wireless communication device. Data is generated in an upper layer of the present embodiment, for example, generated by a user operation.

  The control frame is a frame used for control when a data frame is transmitted / received (exchanged) to / from another wireless communication apparatus. When the wireless communication apparatus receives a data frame or a management frame, the response frame transmitted for confirmation of delivery belongs to the control frame.

  These three types of frames are sent out via the antenna as physical packets after undergoing processing as required in the physical layer. In the connection establishment procedure, a connection request frame and a connection acceptance frame are management frames, and a response frame of a control frame can be used as a confirmation frame for the connection acceptance frame.

Next, a method for disconnecting connections between wireless communication devices will be described.
There are an explicit method and an implicit method for disconnection. As an explicit method, one of the connected wireless communication apparatuses transmits a frame for disconnection. This frame is classified as a management frame. The frame for disconnection may be called a release frame in the sense that, for example, the connection is released. Usually, the wireless communication device that transmits the release frame determines that the connection is disconnected when the release frame is transmitted and the wireless communication device that receives the release frame receives the release frame. Thereafter, the process returns to the initial state in the communication phase, for example, the state of searching for the wireless communication device of the communication partner. This is because when a frame for disconnection is transmitted, a physical radio link may not be secured such that a radio signal cannot be received or decoded due to a communication distance away from the connection destination radio communication device. Because.

An example of physical radio link disconnection in the one-to-one proximity communication system is shown in FIG.
As illustrated in FIG. 14, the other wireless communication device does not exist in the communication range 1401 of the wireless communication device 101 and the communication range 1402 of the wireless communication device 102. Therefore, even if a frame for disconnection is transmitted to the counterpart wireless communication device, a confirmation response cannot be expected. Therefore, the wireless communication device on the release frame transmission side determines that the connection is disconnected when the release frame is transmitted.

  On the other hand, as an implicit method, a frame transmission (transmission of a data frame and a management frame, or transmission of a response frame to a frame transmitted by the own device) is detected from a wireless communication device of a connection partner that has established a connection for a certain period of time. If not, it is determined whether the connection is disconnected. There is such a method in the situation where it is determined that the connection is disconnected as described above, such that the communication distance is away from the connection-destination wireless communication device, and the wireless signal cannot be received or decoded. This is because a wireless link cannot be secured. That is, it cannot be expected to receive a release frame.

  As a specific example of determining the disconnection by an implicit method, a timer is used. For example, when transmitting a data frame requesting a delivery confirmation response frame, a first timer (for example, a retransmission timer for a data frame) that limits a retransmission period of the frame is started, and until the first timer expires (that is, If a delivery confirmation response frame is not received (until the desired retransmission period elapses), retransmission is performed. The first timer is stopped when a delivery confirmation response frame to the frame is received.

  On the other hand, when the first timer expires without receiving the delivery confirmation response frame, for example, it is confirmed whether the other party's wireless communication device still exists (within the communication range) (in other words, the wireless link can be secured). And a second timer for limiting the retransmission period of the frame (for example, a retransmission timer for the management frame) is started at the same time. Similar to the first timer, the second timer also performs retransmission if it does not receive an acknowledgment frame for the frame until the second timer expires, and determines that the connection has been disconnected when the second timer expires. .

  Alternatively, when a frame is received from the connection partner wireless communication device, the third timer is started. Whenever a new frame is received from the connection partner wireless communication device, the third timer is stopped and restarted from the initial value. When the third timer expires, a management frame is transmitted to confirm whether the other party's wireless communication device still exists (within the communication range) (in other words, whether the wireless link has been secured) as described above. At the same time, a second timer (for example, a retransmission timer for management frames) that limits the retransmission period of the frame is started. Also in this case, if the acknowledgment response frame to the frame is not received until the second timer expires, retransmission is performed, and if the second timer expires, it is determined that the connection has been disconnected. The latter management frame for confirming whether the wireless communication apparatus of the connection partner still exists may be different from the management frame in the former case. In the latter case, the timer for limiting retransmission of the management frame is the same as that in the former case as the second timer, but a different timer may be used.

  Next, an access method in a general one-to-one proximity communication system will be described.

  In the one-to-one proximity communication system, the communication partner is only one wireless communication device after the connection is established, and the wireless communication device other than the communication partner exists in the vicinity on the same channel by restricting the communication range narrowly. The situation, that is, it is rare to interfere or compete with a wireless communication device other than the communication partner on the same wireless medium, so a communication system that is supposed to communicate or compete with multiple wireless communication devices accesses the wireless medium. The conditions when doing are different.

  For example, there is a wireless LAN system as a communication system assuming communication or competition with a plurality of wireless communication apparatuses. In the IEEE802.11 (including extended standards) wireless LAN, CSMA / CA is the basic access method. In a method of grasping transmission of a certain wireless device and performing transmission after a fixed time from the end of the transmission, transmission is performed simultaneously by a plurality of wireless devices grasping the transmission of the wireless device. Collide with each other and frame transmission fails. By grasping the transmission of a certain wireless device and waiting for a random time from the end of the transmission, the transmissions by a plurality of wireless communication devices that grasp the transmission of the wireless device are probabilistically dispersed. Therefore, if there is one wireless device that has subtracted the earliest time among the random times, the frame transmission of the wireless device is successful, and frame collision can be prevented. Since acquisition of a transmission right is fair among a plurality of wireless devices based on a random value, a method employing Carrier Avidance is a method suitable for sharing a wireless medium among a plurality of wireless devices. it can.

  Considering a one-to-one proximity communication system, a plurality of wireless communication devices may be candidates as communication partners before the communication partner wireless communication device is uniquely determined, that is, at the stage of connection establishment. There may be a mechanism for competition on the wireless medium. However, once a connection is established, the communication range is narrowly limited, so it is basically difficult to interfere with other wireless communications, and it is restricted to one-to-one communication. There is no connection or communication with other wireless communication devices. Therefore, a mechanism in which a plurality of wireless communication devices compete on a wireless medium is basically unnecessary. Random access is an overhead on the wireless medium, which is not preferable from the viewpoint of communication efficiency.

  Therefore, it is assumed that the one-to-one proximity communication system according to the present embodiment performs carrier sense and accesses as described above, that is, performs CSMA, but does not perform carrier aviation at least after connection establishment.

  Here, the interference includes both a case of receiving from another wireless communication system and a case of giving.

  When considering one-to-one proximity communication, the communication range is narrowly limited. Therefore, in a wireless communication system having a wider communication range, in many cases, a wireless signal from the one-to-one proximity communication system is detected. You can send without. However, even in such a case, the wireless communication device on the one-to-one proximity communication system side may receive a wireless signal from a wireless communication system with a wide communication range. That is, in this case, the one-to-one proximity communication system receives interference from other wireless communication systems, but is not in a situation of causing interference to other wireless communication systems. In such a situation, in the one-to-one proximity communication system, transmission can be detected by received power even if PHY decoding used in a wireless communication system with a wide communication range cannot be performed based on carrier sense. On the other hand, in a wireless device of a wireless communication system having a wide communication range, a wireless signal from the one-to-one proximity communication system is transmitted without being detected. Therefore, the wireless medium cannot be shared even if the frame interval is adjusted on the one-to-one proximity communication system side. On the other hand, when a one-to-one proximity communication system and a wireless communication system with a wide communication range coexist, it is necessary to share a wireless medium by the wireless communication apparatus according to the above-described embodiment.

Next, an example of general frame exchange in the one-to-one wireless communication system will be described with reference to FIG.
Here, it is assumed that the two wireless communication devices constitute a one-to-one proximity communication system through a connection establishment procedure.

The initiator confirms that the wireless medium is free during InitIFS, and transmits a data frame (DATA1) to the responder.
The responder receives DATA1 from the initiator, and sends a response frame (ACK1) to the initiator after SIFS1 has elapsed.
Here, for example, if a transmission request for a data frame (DATA2) is generated during reception of DATA1 in the responder, the responder then postpones transmission until there is an interval between RspIFS. In the example of FIG. 15, since there is no transmission from the initiator after transmitting ACK1, the responder waits for RspIFS after transmitting ACK1 and then transmits DATA2 to the initiator. The initiator that has received DATA2 transmits a response frame (ACK2) to the responder after SIFS1.

  Unlike the example described above, the minimum value is set with InitIFS and RspIFS while the maximum value is not set. In the case where the carrier is not busy when a transmission request is generated, the value from the previous carrier sense busy state is set. This is because there is no time limit. Since the definition of the frame interval is counted from the previous carrier sense busy state, the InitIFS and RspIFS are 3 μs and 7 μs, respectively, if the carrier sense idle is checked before transmission and changed to a continuous period to be freed. Can be defined.

On the other hand, the maximum value is set in SIFS1 because the side that transmitted the data frame and the management frame waits for reception of the response frame, and there is no response frame transmission, a fixed time after the data frame and management frame transmission This is because after the elapse of time, it is necessary to grasp that no response frame is transmitted.
If it is determined that no response frame is transmitted, the wireless communication device on the data frame and management frame transmission side performs retransmission processing. Although it is conceivable to define SIFS1 as a strict fixed time, in that case, it is necessary to grasp and hold an accurate reception end time of the frame. Furthermore, in practice, there are propagation delays and fluctuations in mounting delays until a response frame is generated by receiving and decoding a radio signal, so it is desirable to allow a certain amount of error.
In these frame intervals, since it is necessary to switch the transceiver from the reception state in which carrier sense is performed to the transmission state in which frames are transmitted in terms of mounting, strictly speaking, only the time obtained by subtracting the transmission / reception switching time is used. The state of sense idle is not observed (for example, the carrier sense state within the transmission / reception switching time immediately before transmission cannot be grasped).

In the example described above, three types of frame intervals are shown, but in addition to these, special frame intervals may be defined when it is determined that frame reception has failed. For example, in the transmission between the initiator and the responder, the minimum value of InitIFS is set smaller than the minimum value of RspIFS in order to give transmission priority to the initiator.
Here, it is assumed that the initiator transmits a data frame or a management frame, but the responder fails to receive the data frame or the management frame, resulting in an error. If the timeout time that the initiator determines that there is no response frame is 4.0 μs or more after the transmission of the data frame or management frame, the minimum time for the initiator to start retransmission is 7 after the transmission of the data frame or management frame. 0.0 μs or more. This is equal to or higher than the timing at which the responder leaves RspIFS after receiving a reception error, and priority cannot be given to retransmission at the initiator.

  Therefore, in the responder, if a reception error occurs, for example, by providing 10.0 μs of ERIFS (Extended RspIFS), it is possible to guarantee the priority of retransmission at the initiator.

Next, the frame interval of the IEEE 802.11 wireless LAN assumed as another communication system will be described.
The frame interval used in the IEEE 802.11 wireless LAN is as follows: distributed coordination function inter frame space (DIFS), arbitration inter frame space (AIFS), point coordination function intra interface space interface (IFS). There are six types, reduced interface space (RIFS). In addition, in order to distinguish from the SIFS in the one-to-one proximity communication system according to the present embodiment, the SIFS is represented as SIFS2 for convenience here.

  Unlike the case of the one-to-one proximity communication system, the frame interval is defined as a continuous period in which the carrier sense idle is confirmed and opened before transmission in the IEEE802.11 wireless LAN. No period will be discussed. Therefore, in the description of the IEEE802.11 wireless LAN system here, the definition follows. In the IEEE802.11 wireless LAN, the time to wait for random access based on CSMA / CA is the sum of a fixed time and a random time, and it can be said that such a definition is used to clarify the fixed time.

  DIFS and AIFS are frame intervals used when attempting to start frame exchange during a contention period competing with other wireless communication devices based on CSMA / CA. The DIFS is used when priority according to the traffic type (Traffic Identifier: TID) is provided when there is no distinction of the priority according to the traffic type.

  Since operations related to DIFS and AIFS are similar, the following description will be mainly given using AIFS. In the IEEE802.11 wireless LAN, access control including the start of frame exchange is performed in the MAC layer. Further, when QoS (Quality of Service) is supported when data is passed from an upper layer, the traffic type is notified together with the data, and the data is classified according to the priority at the time of access based on the traffic type. This class at the time of access is called an access category (AC). Therefore, an AIFS value is provided for each access category.

The PIFS is a frame interval for enabling access with priority over other competing wireless communication apparatuses, and has a shorter period than any value of DIFS and AIFS.
SIFS2 is a frame interval that can be used when transmitting a control frame of a response system or when frame exchange is continued in a burst after an access right is acquired once. The SIFS2 in the IEEE 802.11 wireless LAN includes the concept of the SIFS1 in the one-to-one proximity communication system, and can be said to have a wide range of application because there are many variations between frame types and frame exchanges.
EIFS is a frame interval that is triggered when frame reception fails. EIFS in an IEEE 802.11 wireless LAN and ERIFS in a one-to-one proximity communication system are similar. However, the IEEE802.11 wireless LAN does not have a relationship of an initiator and a responder as in the one-to-one proximity communication in the connection form, and is applied to all wireless communication apparatuses.

  The RIFS is a frame interval that can be used when a plurality of frames are continuously transmitted to the same wireless communication device in bursts after acquiring the access right once. Do not request a response frame.

  In the one-to-one proximity communication system according to the present embodiment, there is no frame interval corresponding to RIFS. In the one-to-one proximity communication system, communication is performed when the wireless communication devices are brought close to each other, so that the data exchange can be reliably completed while the wireless communication device that is the communication partner is in the vicinity, that is, during a limited connection time. There is a demand for it. Therefore, it is conceivable that the layer that performs access control is responsible for error control and frame control without entrusting it to an upper layer, so that high-speed processing within the wireless communication apparatus can be achieved.

  In this case, data is sent from the access control layer of the wireless communication device on the data receiving side to the upper layer in the order of transmission in the access control layer of the wireless communication device on the data transmitting side. It is necessary to send a response frame for delivery confirmation. Therefore, unlike the IEEE 802.11 wireless LAN, the operation of transmitting data frames in bursts is not performed. That is, there is no definition of a frame interval corresponding to RIFS.

Here, FIG. 16 shows an example of a frame exchange in a contention period based on random access in the IEEE 802.11 wireless LAN.
A case is assumed in which when a transmission request for a data frame (W_DATA1) is generated in a certain wireless communication apparatus, the medium is recognized as a busy medium as a result of carrier sense. In this case, a fixed time AIFS is made after the carrier sense becomes idle, and then a data frame W_DATA1 is transmitted to the communication partner when a random time (random backoff) is made.

  The random time is obtained by multiplying a pseudo-random integer derived from a uniform distribution between a contention window (Content Window: CW) given by an integer from 0 to a slot time. Here, CW multiplied by slot time is referred to as CW time width. The initial value of CW is given by CWmin, and every time retransmission is performed, the value of CW is increased until it reaches CWmax. Both CWmin and CWmax have values for each access category, similar to AIFS. When the wireless communication apparatus as the transmission destination of W_DATA1 succeeds in receiving the data frame, it transmits a response frame (W_ACK1) after SIFS2 from the reception end time. The wireless communication apparatus that has transmitted W_DATA1 can transmit the next frame (for example, W_DATA2) after SIFS2 if W_ACK1 is received and within the transmission burst time limit.

  AIFS, DIFS, PIFS, and EIFS are functions of SIFS2 and slot time, and SIFS2 and slot time are defined for each physical layer. Parameters for which values are provided for each access category such as AIFS, CWmin, and CWmax can be set for each communication group (Basic Service Set (BSS) in IEEE802.11 wireless LAN), but default values are set. .

  For example, in the 802.11ad standard formulation using the millimeter wave band, the SIFS is 3 μs and the slot time is 5 μs. Accordingly, the PIFS is 8 μs, the DIFS is 13 μs, and the frame interval of the access category in the AIFS is Bacground (AC_BK). The default value is 38 μs, the frame interval of Best effort (AC_BE) is the default value of 18 μs, the frame interval of Video (AC_VI) and Voice (AC_VO) is the default value of 13 μs, and the default values of CWmin and CWmax are AC_BK and AC_BE, respectively. Are 15 and 1023, AC_VI is 7 and 15, and AC_VO is 3 and 7. Note that EIFS is the sum of the time lengths of response frames when transmitting at SIFS2 and DIFS at the slowest required physical rate. In the present embodiment, a wireless communication system using such a frame interval parameter is assumed as an interference system having a wide communication range.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 100 ... 1-to-1 proximity communication system, 101, 102, 200 ... Wireless communication apparatus, 151, 152, 1401, 1402 ... Communication range, 201 ... Antenna, 202 ... Frequency conversion part, 203 ... PHY processing unit, 204 ... parameter holding unit, 205 ... parameter selection unit, 206 ... transmission / reception processing unit, 207 ... host processing unit, 300 ... sequence, 301 ... InitIFS, 302 ... offset period, 303 ... InitIFS_C, 304 ... data, 305 ... SIFS1, 306 ... SIFS1_C, 307 ... ACK1, 1201 ... continuous period, 1301 ... Normal frame interval usage period, 1302... Coexistence frame interval usage period.

Claims (16)

A transmission / reception processing unit that communicates using the first communication method by using either the first frame interval of the first type or the second frame interval of the first type,
The second frame interval is determined based on a frame interval used in a second communication method, and the second frame interval is longer than the first frame interval.   The wireless communication apparatus according to claim 1, wherein the transmission / reception processing unit selects one of the first and second frame intervals based on information regarding a reception error.   The wireless communication apparatus according to claim 1, wherein the transmission / reception processing unit selects one of the first and second frame intervals based on information related to access.   4. The wireless communication device according to claim 1, wherein the transmission / reception processing unit selects the second frame interval when the number of retransmissions exceeds a threshold value. 5.   The PHY processing unit further performs processing for extracting a frame from a baseband signal and transmitting the frame to the transmission / reception processing unit, or converting the frame from the transmission / reception processing unit into a physical packet. The wireless communication device according to any one of the above.   6. The frequency converter according to claim 5, further comprising: a process of demodulating a radio signal into the baseband signal and sending the demodulated signal to the PHY processing unit, or a process of modulating the physical packet from the PHY processing unit into a radio signal. The wireless communication device described.   The wireless communication apparatus according to claim 6, further comprising an antenna connected to the frequency conversion unit for transmitting and receiving the wireless signal. A processor for controlling to communicate using the first communication method using either the first frame interval of the first type or the second frame interval of the first type;
The second frame interval is determined based on a frame interval used in a second communication method, and the second frame interval is longer than the first frame interval.   The wireless communication apparatus according to claim 8, wherein the processor selects one of the first frame interval and the second frame interval based on information regarding a reception error.   The wireless communication apparatus according to claim 8, wherein the processor selects one of the first and second frame intervals based on information related to access.   The wireless communication device according to any one of claims 8 to 10, wherein the processor selects the second frame interval when the number of retransmissions exceeds a threshold value.   The first frame interval and the second frame interval are times from when it is detected that a carrier has changed from busy to idle in carrier sense on a wireless medium until a frame is transmitted. The wireless communication device according to any one of 11.   The wireless communication apparatus according to any one of claims 1 to 12, wherein the first type is any one of InitIFS, RspIFS, and SIFS.   The wireless communication apparatus according to any one of claims 1 to 13, wherein the first communication method is a proximity communication method, and the second communication method is a communication method using a wireless LAN.   The wireless communication device according to any one of claims 1 to 14, wherein the first communication method is a one-to-one communication method. Using either the first frame interval of the first type and the second frame interval of the first type, communicate with the first communication method,
The second frame interval is determined based on a frame interval used in a second communication method, and the second frame interval is longer than the first frame interval.