Packet transmission method and wireless communication device

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a wireless communication device capable of transmitting and receiving data in a packet format after setting a link by using a short-range wireless communication means, and a packet transmission method between the wireless communication devices.

【0002】

[Conventional technology]

In recent years, a system has been developed that adopts the Bluetooth standard for transmitting and receiving data between devices using a 2.4 GHz band frequency hopping method. For example, devices such as mobile phones, PHS (Personal Handyphone System), personal computers, and personal digital assistants are equipped with Bluetooth standard wireless modules, and data is transmitted and received using the wireless modules so that data can be transmitted between each device. It is possible to send and receive. In the following, a device equipped with a Bluetooth standard wireless module will be referred to as a BT device.

【0003】

If the BT devices are connected via a wireless link, data can be transmitted and received between these BT devices. At that time, any one BT device operates as a master, and the other BT device operates as a slave.

【0004】

In Bluetooth, channels are divided into time slots of 625 μs in length and slot numbers are assigned according to the Piconet Master's Bluetooth clock. Slot numbers are numbered from 0 to 227-1 and return to 0 when 227-1 is reached. The BT device transmits packets using these time slots for both the master and slave.

【0005】

Bluetooth uses a TDD (Time Division Duplex) scheme in which masters and slaves transmit alternately. The master can only start transmitting packets from even-numbered time slots. Then, the slave can start packet transmission only from the odd-numbered time slot located next to the time slot in which the packet is transmitted, only when the packet is sent from the master to itself. In addition, both master and slave can transmit packets extended to a maximum of 5 time slots.

【0006】

By the way, Bluetooth link types include SCO (Synchronous Connection-Oriented) links and ACL (Asynchronous Connection-Less) links. The SCO link is a circuit-switched connection that reserves time slots at regular time intervals for communication, and is suitable for handling voice traffic. On the other hand, the ACL link is a packet-switched connection that communicates using a time slot that is not reserved for the SCO link, and is suitable for handling data traffic.

【0007】

FIG. 13 shows an example of packet (ACL packet) communication between a master using an ACL link and slave 1 or slave 2. In the example shown in FIG. 13, the master sends an ACL packet having a time slot length of 5 from even-numbered time slots 2n to slave 1. At this time, the slave 1 that has received the ACL packet from the master is given the right to send the ACL packet to the master from the odd-numbered time slots 2n + 5. In the example of FIG. 13, a packet having a time slot length of 3 is sent from the time slot 2n + 5. Even if slave 1 does not have information to be sent to the master, other slaves cannot send ACL packets using time slot 2n + 5. In the example of FIG. 13, the master subsequently sends an ACL packet having a time slot length of 3 from the even-numbered time slot 2n + 8 to the slave 2, and the slave 2 that receives this sends the odd-numbered time slot 2n +. From 11, an ACL packet with a time slot length of 3 is sent to the master.

【0008】

[Problems to be Solved by the Invention]

When a BT device communicates using an ACL link, it is possible to immediately transmit an ACL packet using a time slot that is not reserved by the SCO link. In addition, the packet size that can be used for one ACL packet transmission can span up to five time slots.

【0009】

However, if one BT device determines the packet size and transmits the ACL packet without considering the other BT device, inconvenience may occur from the viewpoint of efficient use of ACL link resources.

【0010】

FIG. 14 shows a request from the master to send data corresponding to the time slot length 15 to the slave and data corresponding to the time slot length 3 from the slave to the master at each time interval corresponding to the time slot length 18. An example of ACL packet communication on an ACL link is shown when a transmission request and a transmission request occur at the same time. In the example of FIG. 14, both the master and the slave can send an ACL packet having a size corresponding to the time slot length 5 as the maximum value of the ACL packet length.

【0011】

As shown in FIG. 14, the time slot positions α, β, and γ are slot positions where the slave can send packets to the master, but at this time, the slave has already transmitted data corresponding to the time slot length 3. Therefore, there is no data to be transmitted in the slave. Therefore, the time slot (α, β, γ) does not transmit data. That is, in the example of FIG. 3 ÷ 36 8.3% ACL link resource was not used for data communication.

【0012】

In addition, if a communication error occurs during packet transmission on the ACL link, this packet will be retransmitted. In this case, the larger the packet size, the longer the time required for retransmission, and as a result, the packet transmission quality deteriorates. Will bring.

【0013】

The present invention has been made in consideration of the above circumstances, and it is possible to efficiently use ACL link resources when transmitting and receiving data in ACL packet format after setting an ACL link using the Bluetooth standard. It is an object of the present invention to provide a possible packet transmission method and wireless communication device.

【0014】

Further, the present invention is a packet transmission method and a wireless communication device capable of suppressing deterioration of packet transmission quality to a low level when transmitting / receiving data in the ACL packet format after setting an ACL link using the Bluetooth standard. The purpose is to provide.

【0015】

[Means for solving problems]

According to the present invention, in a packet transmission method between communication devices capable of transmitting and receiving data in packet format after setting a link by using a short-range wireless communication means, the first communication device is a link. The first required value indicating the average value of the data transmission speed to the second communication device requested by the first communication device as the maximum value of the packet size to be transmitted to the second communication device in which is set. It is characterized in that it is determined based on the ratio with the second required value indicating the average value of the data transmission speed to the first communication device required by the second communication device.

【0016】

Further, the wireless communication device according to the present invention includes a short-range wireless communication means for transmitting / receiving data in a packet format after setting a link with another wireless communication device, and the above-mentioned after setting the link. The maximum value of the packet size to be transmitted to another wireless communication device is requested by the own device and the required value indicating the average value of the data transmission speed to the other wireless communication device, and the other wireless communication device. The short-range wireless communication means is provided with a determination means for determining based on a ratio to a required value indicating an average value of data transmission speeds addressed to the own device, and the short-range wireless communication means is used for the other wireless communication device determined by the determination means. It is characterized in that data is transmitted based on the maximum value of the packet size to be transmitted.

【0017】

Further, the present invention is for causing a computer built in a communication device capable of transmitting and receiving data in packet format after setting a link by using a short-range wireless communication means to function as a control unit for packet transmission. In the program, the first communication device is addressed to the second communication device in which the first communication device requests the maximum value of the packet size to be transmitted to the second communication device to which the link is set. Based on the ratio of the first required value indicating the average value of the data transmission speed to the second required value indicating the average value of the data transmission speed destined for the first communication device requested by the second communication device. It is a program for realizing the function of deciding on a computer.

【0018】

The present invention relating to the device is also valid as an invention relating to the method, and the present invention relating to the method is also valid as an invention relating to the device.

【0019】

In addition, the present invention relating to an apparatus or method provides a function for causing a computer to perform a procedure corresponding to the present invention (or for causing the computer to function as a means corresponding to the present invention, or for causing the computer to perform a function corresponding to the present invention. It also holds as a program (for realization), and also as a computer-readable recording medium on which the program is recorded.

【0020】

According to the present invention, when sending and receiving data in ACL packet format after setting an ACL link using the Bluetooth standard, the maximum value of ACL packet length is compared by comparing the required quality with the BT device of the communication partner. By setting, it is possible to provide packet transmission that efficiently uses ACL link resources.

【0021】

In addition, the ACL link resource can be used more efficiently by dynamically changing the maximum value of the ACL packet length based on the presence or absence of transmission information in the BT device of the communication partner.

【0022】

Then, by dynamically changing the maximum value of the ACL packet length based on the knowledge information from the BT device of the communication partner, the packet transmission that can suppress the deterioration of the packet transmission quality due to the ACL packet retransmission is provided. Is possible.

【0023】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the invention will be described with reference to the drawings.

【0024】

In the following, a case where data is transmitted / received in the ACL packet format after the ACL link is set using the Bluetooth standard will be described as an example.

【0025】

FIG. 1 shows an example of the configuration (corresponding to the protocol stack) of the BT device according to the embodiment of the present invention.

【0026】

In FIG. 1, the L2CAP processing unit 12 that executes the data link layer specification (L2CAP; Logical Link Control and Adaptation Protocol) that uses ACL links is mounted on the baseband processing unit 11 that is the physical layer specification of Bluetooth. As a higher-level protocol that uses the L2CAP processing unit 12, there are protocols (each corresponding processing unit) such as service discovery protocol (SDP) 13, RFCOMM14, and telephony control (TCS) 15. When using the SCO link, the upper layer protocol that uses SCO transfer directly rides on the baseband processing unit 11 without using the L2CAP processing unit 12. In the present embodiment, a case where the L2CAP processing units 12 in the BT device communicate with each other via the ACL link will be described.

【0027】

FIG. 2 shows an example of packet division in the L2CAP processing unit 12. In the figure, 21 is a packet (L2CAP packet) defined by the L2CAP processing unit 12. The L2CAP packet has a Length field (2 octets length) that displays the information payload size in octets, a CID (channel identifier) field (2 octets length) that identifies the destination channel endpoint of the packet, and communication information received from the upper layer protocol. It consists of a Payload field (0 to 65535 octet length) that stores, and the Length field and CID field are collectively called the L2CAP header.

【0028】

The SAR (Segmentation And Reassembly) function implemented in the baseband processing unit 11 divides the L2CAP packet 21 into the payload of the ACL packet handled by the baseband processing unit 12, and also from the payload of the ACL packet. Rebuild the L2CAP packet. The L_CH (logical channel) field defined in the payload header of the ACL packet so that the SAR function (in the baseband processing unit 11) of the BT device that received this ACL packet can reconstruct it into an L2CAP packet. (2 bit length) is used to explicitly indicate whether or not the ACL packet is the start part (continuation part) of the L2CAP packet. More specifically, for ACL packets containing the first segment of an L2CAP packet (see ACL packet 22 in Figure 2), set the L_CH field to the value "10" and for ACL packets containing subsequent segments (Figure). (Refer to ACL packets 23 and 24 in 2), set the value "01" in the L_CH field.

【0029】

FIG. 3 shows an example of the internal configuration of the part related to the SAR function of the baseband processing unit 11. As shown in FIG. 3, the part related to the SAR function of the baseband processing unit 11 is the L2CAP packet division unit 31 that subdivides the L2CAP packet, the ACL packet generation unit that generates the ACL packet by adding a header, etc. 32, TX buffer 33 that controls the transmission of ACL packets or SCO packets onto the time slot, RX buffer 34 that receives ACL packets or SCO packets transmitted on the time slot, and extracts payload information in ACL packets. It includes a payload extraction unit 35, an L2CAP packet reconstruction unit 36 that reconstructs ACL packets to generate L2CAP packets, and an ACL packet length control unit 37.

【0030】

In FIG. 3, the size of the ACL packet transmitted by the BT device is determined by the ACL packet length control unit 37. The ACL packet length control unit 37 dynamically corrects the maximum value of the ACL packet length, depending on the required communication quality between the BT devices that set the ACL link, the actual transmission status of the ACL packet, and the like. Is notified to the L2CAP packet segment 31 (see 42 in the figure). The L2CAP packet division unit 31 divides the L2CAP packet so that an ACL packet that does not exceed the maximum ACL packet length notified from the ACL packet length control unit 37 can be generated.

【0031】

In the embodiment of the present invention shown in FIG. 1, the L2CAP processing unit 12 is directly mounted on the baseband processing unit 11, but as a further embodiment, as shown in FIG. 4, the baseband processing unit 11 and the L2CAP processing are performed. There is also a form in which an HCI processing unit 16 that executes the host controller interface specification (HCI) exists between the unit 12 and the unit 12.

【0032】

As the form of FIG. 4, a BT host (PC, etc.) equipped with upper layer software such as the L2CAP processing unit 12 and a BT device equipped with the baseband processing unit 11 are connected by USB (Universal Serial Bus). ) Etc. may be used for connection. At this time, communication between the BT host and the BT device is performed based on the HCI specifications.

【0033】

In the case of the form via the HCI processing unit 16 as shown in FIG. 4, the L2CAP packet is divided as shown in FIG. The L2CAP packet sent from the BT host is once divided into packets (HCI packets) defined in the HCI specifications by the HCI processing unit 16 on the BT host side, and then delivered to the BT device.

【0034】

For HCI packets, the Connection Handle field (12-bit length) used to identify the connection, the Packet Boundary flag (PB flag: 2-bit length) indicating whether or not it is the first segment of the L2CAP packet, point-to-point communication or broadcast communication. It consists of a Broadcast flag (BC flag: 2 bit length), a Data Total Length field (2 octet length) that displays the data length in octets, and a Data field that divides and stores L2CAP packets.

【0035】

The maximum length of the HCI packet is set so as not to exceed the maximum value of the buffer size held by the BT device to which the HCI packet is delivered. The SAR function in the baseband processing unit 11 that receives the HCI packet divides the HCI packet into the payload of the ACL packet.

【0036】

In the case of the form via the HCI processing unit 16 as shown in FIG. 4, the internal configuration of the part related to the SAR function of the baseband processing unit 11 is as shown in FIG.

【0037】

FIG. 7 shows an example of a processing procedure when the ACL packet length control unit 37 determines the maximum value of the ACL packet length. The processing procedure shown in FIG. 7 shows the processing procedure for determining the maximum packet length of the ACL packet to be transmitted to the BT device B when the BT device A sets the ACL link with the BT device B. (The processing procedure for BT device B is the same (the processing procedure in Fig. 7 may replace BT device A and BT device B)).

【0038】

The trigger for changing the maximum value of the ACL packet length in the BT device A is, for example, when setting an ACL link with the BT device B, or providing the BT device A or the BT device B using the ACL link. For example, when there is a change in the service content.

【0039】

When notifying BT device A from BT device B due to a change in the QoS parameter in BT device B, the QoS parameter in BT device B should be described as a parameter of the Configuration Request packet. Send to BT device A (The parameter of the configuration request packet is used when negotiating the ACL link agreement between the L2CAP processing unit 12 in one BT device and the L2CAP processing unit 12 in the other BT device. It is). In this case, the BT device A knows the QoS parameters of the BT device B by receiving the notification of the QoS parameters from the BT device B.

【0040】

The BT machine QoS parameters L2CAP processing unit 12 requests the device B is notified to the ACL packet length control unit 37 (see 41 in FIG. 3).

【0041】

On the other hand, the QoS parameters required by the L2CAP processing unit 12 of the BT device A itself are also notified to the ACL packet length control unit 37 (see 41 in FIG. 3).

【0042】

When the QoS parameter in the BT device A is changed, the BT device A similarly notifies the BT device B of the QoS parameter.

【0043】

Now, when the QoS parameter in the BT device A itself and / or the BT device B is changed (step S51), the BT device A compares the token rate, which is one of the QoS parameters (step S52). .. The token rate indicates the speed at which continuous data transmission is possible in bytes. The BT device A compares the token rate of the BT device A with the token rate of the BT device B, and determines which device has the higher token rate.

【0044】

If the token rate required by BT device A and the token rate required by BT device B are equal to each other or the former is larger than the latter, it can be currently occupied as an ACL packet as the maximum value of the ACL packet in BT device A. Set the maximum value N among the candidates for the number of time slots (step S53).

【0045】

When the token rate required by BT device A is smaller than the token rate required by BT device B, the token rate required by BT device A is set to T (A) or BT as the maximum value of the ACL packet in BT device A. When the token rate required by device B is T (B), select from the candidates for the number of time slots that can be currently occupied as ACL packets based on the value U obtained by Eq. (1) (step). S54).

【0046】

U = N × T (A) / T (B) ... (1) As a method of selecting the maximum value of ACL packet length in BT device A based on the value U, for example, the following procedure can be mentioned.

【0047】

From the candidates for the number of time slots that can be currently occupied as an ACL packet, select the minimum value that does not exceed U, and occupy the time slot for this selected (minimum that does not exceed U) value. Set the maximum ACL packet length.

【0048】

Among the candidates for the number of time slots that can be currently occupied as an ACL packet, the value closest to U can be selected, and the ACL packet can occupy the time slot for the selected (closest to U) value. Set the maximum length.

【0049】

Here, candidates for the number of time slots that can be occupied as ACL packets will be described.

【0050】

In the Bluetooth standard, the number of time slots that one ACL packet can occupy is up to 5 time slots. Since the master always sends packets from even-numbered time slots and the slave always sends packets from odd-numbered time slots, select from (1, 3, 5) as the maximum ACL packet length. Will be set.

【0051】

After all, if the token rate required by BT device A and the token rate required by BT device B are the same according to the procedure of FIG. 7, the maximum in step S53 is obtained in both BT device A and BT device B. If the value N of is selected and the token rate required by BT device A and the token rate required by BT device B are not the same, the maximum value N is selected in step S53 in the larger BT device. Then, in the smaller BT device, the value according to step S54 is selected.

【0052】

By the way, in addition to ACL links, SCO links can also be set between BT devices. Unlike ACL links, SCO links reserve time slots in advance at regular time intervals for communication. Time slots that can be used as ACL links are limited to time slots that are not reserved by SCO links.

【0053】

Figure 8 shows an overview of time slot reservations via SCO Link. In the example of FIG. 8, a time slot is reserved for the SCO link every 6 slots for both the master and the slave. In this case, 5 cannot be set as the maximum ACL packet length. That is, only (1, 3) can be mentioned as a candidate for the number of time slots that can be occupied as an ACL packet. Then, according to the processing procedure shown in FIG. 7, if the time slot length 3 is set as the maximum value of the ACL packet length in the master or slave having the larger request token rate, the maximum value of the other ACL packet length is set. Inevitably has a time slot length of 1. If it is determined from the request token rate ratio that such allocation (maximum time slot length 3: maximum time slot length 1) is not desirable, the maximum ACL packet length is set to 1 for both master and slave. To do.

【0054】

In this way, the candidates for the number of time slots that can be occupied as ACL packets vary depending on the setting status of the SCO link. Therefore, it is necessary to review the number of time slots that can be occupied as ACL packets each time an event such as new setting of SCO link or release of existing SCO link occurs.

【0055】

In the following example, in order to simplify the description of the embodiment, the SCO link will be described in a situation where it is not set. That is, the number of time slots that can be occupied as an ACL packet is always (1, 3, 5).

【0056】

FIG. 9 shows an example of ACL packet communication on the ACL link when the maximum value of the ACL packet length is determined according to the processing procedure shown in FIG. 7 under the same conditions as in FIG. In the example shown in FIG. 17, both the master and the slave were able to transmit ACL packets corresponding to the time slot length of 5. It is assumed that the token rate, which is one of the QoS parameters required by the master side and the slave side, is equal to the data arrival process shown in FIG. In this case, the ratio of the token rates on the master side and the slave side is 5: 1, so the maximum value of the ACL packet length set on the master side is set to be equal to the time slot length 5. On the other hand, the maximum value of the ACL packet length set on the slave side is according to the above equation (1). 5 × 1/5 = 1 And is set equal to the time slot length 1.

【0057】

When the maximum value of the ACL packet length is set according to the processing procedure shown in FIG. 7, as shown in FIG. 9, the time slots (α, β, γ) at which data transmission is not performed as seen in the example of FIG. 17 occur. not exist. This means that ACL link resources are used more efficiently than in the example of FIG.

【0058】

By the way, if the maximum value of the ACL packet length is set based only on the token rate of the request QoS parameter, there is a possibility that a violation of the request QoS parameter other than the token rate may occur. FIG. 10 shows the ACL packet sent from the slave shown in FIG. 17 (time slot length 5 is set as the maximum ACL packet length) and FIG. 9 (time slot length 1 is set as the maximum ACL packet length). The pattern is shown ((a) shows the case of FIG. 17, and (b) shows the case of FIG. 9).

【0059】

Figure 10 is an example of the case where the time slot length 5 is set as the maximum value of the ACL packet length and the case where the time slot length 1 is set to transmit the same data (corresponding to the time slot length 3). Then, there is a time difference corresponding to the time slot length of 10 to finish the transmission of all the data. Since one time slot length is 625 μs, if the maximum value of ACL packet length is set as the time slot length 1, a delay of 6.25 msec occurs. At this time, if a value shorter than 6.25 msec is set as the latency of the QoS parameter requested on the slave side, this is violated.

【0060】

In the procedure processing shown in FIG. 7, since the maximum value of the ACL packet length is determined by paying attention only to the token rate as the QoS parameter, the problem shown in FIG. 10 occurs.

【0061】

FIG. 11 shows an example of the processing procedure when the ACL packet length control unit 37 determines the maximum value of the ACL packet length in consideration of the latency of the QoS parameter.

【0062】

In FIG. 11, steps S51 to S54 are the same as the processing procedure shown in FIG. 7.

【0063】

In the processing procedure shown in FIG. 11, when the maximum value of the ACL packet length selected in step S54 is used, it is examined whether or not the latency of the QoS parameter is also satisfied at the same time (step S55). If it is determined that the latency can be satisfied at the same time by using the maximum value of the ACL packet length selected in step S54, that value is set as the maximum value (step S56). On the other hand, if it is determined that the latency is not satisfactory, the current maximum ACL packet length is increased by one rank (step S57). Specifically, if the time slot length 1 is currently selected as the maximum ACL packet length, this is corrected to 3, and if the time slot length 3 is selected, this is corrected to 5. .. Then, check again whether the latency can be satisfied (step S55).

【0064】

Although not shown in FIG. 11, if the latency cannot be satisfied even if the maximum value of the ACL packet length is set to any value, the L2CAP processing unit 12 should correct the required QoS parameters including the latency. Take control.

【0065】

Here, in the BT device in which the maximum value of the ACL packet length is set to the time slot length 1 or the time slot length 3 by the processing procedure shown in FIGS. 7 and 11, the BT device that is the communication partner using the ACL link By temporarily increasing the maximum value of the ACL packet length when data transmission is interrupted in, more efficient use of the ACL link becomes possible.

【0066】

FIG. 12 shows an example of ACL packet communication when the maximum value of the ACL packet length is temporarily increased due to the temporary suspension of data transmission at the communication partner BT device. In FIG. 12, the white ACL packets (three transmitted by the BT device B) indicate that the communication information is not described in the payload of the packet (only the ACK information related to the ACL packet received immediately before). Is described).

【0067】

In the example shown in FIG. 12, the BT device A sets the maximum ACL packet length to the time slot length 1, and the BT device B sets the maximum ACL packet length to the time slot length 5. Then, the BT device A receives the ACL packet from the BT device B in which the communication information is not described in the payload, and determines that the data to be transmitted by the BT device B does not exist. In the example of FIG. 12, when two ACL packets containing no communication information in the payload are continuously received from the BT device B, the BT device A determines that the data transmission is temporarily interrupted in the BT device B. Then, the BT device A sets the maximum value of the current ACL packet length to the time slot length 5, generates the subsequent ACL packet, and sends it to the BT device B.

【0068】

When the BT device B resumes data transmission again, the BT device A receives the ACL packet in which the communication information is described in the payload. With this as a trigger, BT device A sets the maximum value of the ACL packet length to the initial value again (time slot length 1 in the example of FIG. 12), generates subsequent ACL packets, and sends them to BT device B. ..

【0069】

In order to correct the maximum value of the ACL packet length due to the temporary interruption of data transmission in the BT device of the communication partner as described above, the baseband processing unit 11 of the BT device recycles the L2CAP packet from the received ACL packet. At the stage of construction, the payload extraction unit 35 (Fig. 3) determines whether or not the ACL packet contains payload information, and if the ACL packet does not contain payload information, the ACL packet length control unit 37 determines that fact. Notify (Fig. 3) (see 43 in Fig. 3).

【0070】

In the example of FIG. 12, whether or not the BT device of the communication partner temporarily interrupts data transmission is determined based on whether or not an ACL packet with empty payload information is received, but the communication partner is determined. It is also possible to make a similar judgment based on whether or not the BT device of the above has sent an ACL packet. In this case, the RX buffer 34 (Fig. 3) that receives the ACL packet determines whether or not the ACL packet from the BT device of the communication partner has been received in the predetermined time slot, and if the ACL packet is not received, the ACL packet must be received. This is notified to the ACL packet length control unit 37 (Fig. 3) (see 44 in Fig. 3).

【0071】

Next, FIGS. 13 and 14 show how the ACL packet is retransmitted when an error occurs during ACL packet transmission. In both FIGS. 13 and 14, data corresponding to the time slot length 5 is transmitted from the BT device A to the BT device B, and an error occurs in the same time slot. Further, in the example of FIG. 13, the transmission data is transmitted by one ACL packet () corresponding to the time slot length 5, and in the example of FIG. 14, the transmission data is transmitted by five ACL packets corresponding to the time slot length 1 (). Transmit by A, B, C, D, E).

【0072】

Comparing the results of FIGS. 13 and 14, in FIG. 13, the ACL packet is retransmitted twice (',''), and it takes 18 time slots to complete the transmission. On the other hand, in FIG. 14, ACL packets B and D are retransmitted once, and it takes 14 time slots to complete the transmission. That is, when the ACL packet length is large, the retransmission information associated with the occurrence of the error also increases, so that the time required to complete the retransmission increases. In wireless transmission, burst errors that are partially concentrated may occur due to fading or the like, but in this case, the frequency of retransmission of transmitted packets becomes extremely high. Therefore, it is necessary to dynamically change the maximum value of the ACL packet length in consideration of the wireless transmission environment.

【0073】

Next, FIG. 15 shows the concept of changing the maximum ACL packet length based on the deterioration of transmission quality. Whether the transmission quality has deteriorated in the BT device, or whether the transmission quality has not deteriorated and is normalized, and whether the maximum ACL packet length is set as the default value (processing procedure shown in Fig. 7 or Fig. 11). Make changes such as (maximum value determined according to) or decrease the maximum value of ACL packet length (equal to time slot length 1).

【0074】

As a means for determining whether or not the transmission quality has deteriorated, a method of referring to the knowledge information described in the header of the ACL packet sent from the BT device as the communication partner can be considered. 1-bit information (ARQN) indicating acknowledge is prepared in the header of the ACL packet. If ARQN = 1, it means that the reception was successful, and if ARQN = 0, the reception was not successful. By indicating that, the BT device of the sender is notified of this. For example, if the BT device receives an ACL packet with ARQN = 0 a predetermined number of times within a specified time, it is determined that the transmission quality has deteriorated, and the maximum value of the transmission ACL packet length is reduced. Even after reducing the maximum ACL packet length, the BT device checks the ARQN value of the received ACL packet, and if no ACL packet with ARQN = 0 is received within the specified time, the transmission quality. It is judged that the deterioration of is resolved, and the maximum value of the transmission ACL packet length is returned to the set value. If the BT device requests the Acknowledge information but the ACL packet that should include the Acknowledgment information for the transmitted ACL packet is not received, the BT device has received the ACL packet with ARQN = 0. Treat as.

【0075】

Of the components described above, the functions corresponding to the parts that perform processing such as calculation and control can also be realized as software (in this case, a computer (CPU, MPU, etc.) is built into the BT device. Then run the software on the built-in computer).

【0076】

In addition, the functions corresponding to the parts that perform processing such as calculation and control among the components described above are for causing the computer to execute a predetermined means (or for making the computer function as a predetermined means, or for the computer. It can be implemented as a program (to realize a predetermined function), or it can be implemented as a computer-readable recording medium on which the program is recorded.

【0077】

It should be noted that the configuration illustrated in the embodiment of the present invention is an example, and is not intended to exclude other configurations, and a part of the illustrated configuration may be replaced with another or one of the illustrated configurations. It is also possible to obtain another configuration by omitting a part, adding another function or element to the illustrated configuration, or combining them. In addition, another configuration that is logically equivalent to the illustrated configuration, another configuration that includes a part that is logically equivalent to the illustrated configuration, another configuration that is logically equivalent to the main part of the illustrated configuration, and the like are also possible. is there. Further, another configuration that achieves the same or similar purpose as the illustrated configuration, another configuration that has the same or similar effect as the illustrated configuration, and the like are also possible.

【0078】

In addition, various variations of the various constituent parts illustrated in the embodiment of the present invention can be appropriately combined and implemented.

【0079】

Moreover, the embodiment of this invention is an invention as an individual device, an invention about two or more related devices, an invention as a whole system, an invention about a component inside an individual device, or a method corresponding thereto. It includes / inherently inventions related to various viewpoints, stages, concepts or categories such as inventions.

【0080】

Therefore, the invention can be extracted from the contents disclosed in the embodiment of the present invention without being limited to the illustrated configuration.

【0081】

The present invention is not limited to the above-described embodiment, and can be implemented with various modifications within the technical scope thereof.

【0082】

[Effect of the invention]

According to the present invention, the ACL link resource can be efficiently used when sending / receiving data in the ACL packet format after setting the ACL link using the Bluetooth standard.

[Simple explanation of drawings]

[Figure 1]

The figure which shows the structural example of the BT apparatus which concerns on one Embodiment of this invention. [Figure 2]

The figure which shows the packet division example in the L2CAP processing part of the BT apparatus which concerns on the same embodiment. [Fig. 3]

The figure which shows the internal structure example of the part related to the SAR function in the baseband processing part of the BT apparatus which concerns on the same embodiment. [Fig. 4]

The figure which shows the structural example of the BT device which concerns on other embodiment [Fig. 5]

The figure which shows the packet division example in the L2CAP processing part of the BT apparatus which concerns on another embodiment. [Fig. 6]

The figure which shows the internal composition example of the part related to the SAR function in the baseband processing part of the BT apparatus which concerns on another embodiment. [Fig. 7]

A flowchart showing an example of a processing procedure for determining the maximum value of the ACL packet length in the ACL packet length control unit of FIG. [Fig. 8]

Diagram showing an overview of time slot reservations via SCO Link [Fig. 9]

A diagram showing an example of ACL packet communication on an ACL link when the maximum value of ACL packet length is determined according to the processing procedure shown in FIG. 7 under the same conditions as in FIG. [Fig. 10]

The figure which shows the ACL packet pattern sent from the slave shown in FIG. 17 and FIG. [Fig. 11]

A flowchart showing an example of a processing procedure for determining the maximum value of the ACL packet length in consideration of the latency of the QoS parameter of the ACL packet length control unit in FIG. [Fig. 12]

The figure which shows an example of ACL packet communication when the maximum value of ACL packet length is temporarily increased due to the temporary interruption of data transmission in a communication partner BT device. [Fig. 13]

The figure which shows the state of the retransmission of the ACL packet (transmitted by one ACL packet) when an error occurs at the time of ACL packet transmission. [Fig. 14]

The figure which shows the state of the retransmission of the ACL packet (transmitted by dividing into 5 ACL packets) when an error occurs at the time of ACL packet transmission. [Fig. 15]

Diagram showing the concept of changing the maximum ACL packet length based on the deterioration of transmission quality. [Fig. 16]

The figure which shows an example of ACL packet communication between a master and a slave using an ACL link. [Fig. 17]

The figure which shows an example of ACL packet communication on an ACL link when a data transmission request occurs at the same time in a master and a slave. [Explanation of symbols]

11 ... Baseband processing unit 12 ... L2CAP processing unit 21 ... L2CAP packet 22 ... ACL packet (L_CH = 10) 23,24 ... ACL packet (L_CH = 01) 31 ... L2CAP packet divider 32 ... ACL packet generator 33 ... TX buffer 34 ... RX buffer 35 ... Payload extractor 36 ... L2CAP Packet Reconstruction Department 37 ... ACL packet length control unit