KR20020002792A - Communication method between master and slaves of local wireless communication apparatus - Google Patents

Abstract

PURPOSE: A communication method between a master and a slave in a local radio frequency communication device is provided so that a whole band of a Bluetooth network can be efficiently used by changing an audio data format. CONSTITUTION: A master which is a Bluetooth module and a slave respectively include a Bluetooth host control unit(10) and a Bluetooth radio frequency unit(20). The Bluetooth host control unit(10) performs host interface and link management, and includes an external interface(12), a main control unit(14) and a link baseband controller(16). The link baseband controller(16) processes Bluetooth baseband and performs a physical layer protocol, and the external interface(12) interfaces the main control unit(14) and a host. The main control unit(14) performs various control operations for the host interface and link management. On the other hand, the Bluetooth radio frequency unit(20) includes a radio frequency transmission unit and a radio frequency reception unit, and performs radio frequency transmission and reception of audio and/or data between Bluetooth modules.

Description

COMMUNICATION METHOD BETWEEN MASTER AND SLAVES OF LOCAL WIRELESS COMMUNICATION APPARATUS}

The present invention relates to a wireless communication system, and more particularly, to a communication method between a MR and a slave in a Bluetooth wireless device.

These days, the wireless and computer industries have realized that low cost, power wireless devices or wireless links are practical. Such wireless communication provides a foundation for eliminating complicated connection cables between office devices and communication between devices, which emphasizes small size and portability, in accordance with recent development trends. As a result, various studies have been carried out, and the professional code so-called "bluetooth" has been defined by Sweden's Ericsson. The goal of Bluetooth is to provide mobility and convenience services for business users based on the compact short-range wireless. Bluetooth has defined technical characteristics that optimize the usage model of portable computers and communication devices. It is also specially designed to provide low cost, robustness, efficiency and high capacity, especially voice and data networking.

The short range wireless communication system employing Bluetooth can transmit voice and data in real time through a wireless link between communication devices such as mobile phones, notebook computers, and desktops which are usually located within 10 meters. The short range wireless communication system employing Bluetooth is composed of a master for transmitting voice and / or data and a plurality of slaves for receiving voice and / or data, and the roles of the master and slave are voice and data. The role changes depending on the sender of. The detailed transmission standard of the wireless link method proposed for Bluetooth has the advantage of protecting the information and protecting it from interference. In addition, since the Bluetooth wireless device can be manufactured in the form of a small microchip, it can be easily coupled to communication devices and operates in the 2.4GHz band, which is a globally compatible frequency band. The Bluetooth standard defines two power levels, of which the low voltage level specifies that it can only operate within a distance of the room, and the high voltage level specifies that it can operate throughout the house. Bluetooth wireless technology supports both point-to-point and point-to-multipoint connections, which allow communication between one master and each of up to seven slaves. .

BLUETOOTH SPECIFICATION Version 1.0A stipulates the use of one of three coding methods: Continuous Variable Slope Delta (CVSD), A-Low, and μ-Low for the compression and transmission of voice information over the radio section. . The data rate of the voice information coded and transmitted in one of three coding schemes is all defined as 64 kbps. In addition, the BLUETOOTH SPECIFICATION classifies packet types of SCO (Synchronous Connection-Oriented) packets used to carry and transmit voice information into DV, HV1, HV2, and HV3. The DV and HV1 packet types have 10 bytes of voice information that can be loaded in a payload, the HV2 packet type has 20 bytes of voice information that can be loaded in a payload, and the HV3 packet types have voice information that can be loaded in a payload. 30 bytes. When using the SCO packet of the HV1 packet type, the entire band that can be used between the Bluetooth modules should be used to transmit and receive only SCO packets, that is, the voice information. The% bandwidth should be used for sending and receiving SCO packets. In case of using HV3 packet type SCO packet, 33.3% of all bands should be used for transmitting and receiving SCO packets.

If Bluetooth users can add voice data rate and corresponding SCO packet format to BLUETOOTH SPECIFICATION and reduce the overall bandwidth occupancy rate by voice service between Bluetooth modules, without the problem of receiving voice service, It may be able to allocate more to data services than voice services.

Accordingly, an object of the present invention is to provide a method for efficiently using the entire band of a network in a Bluetooth wireless device.

Another object of the present invention is to provide a method for reducing the total bandwidth occupancy rate by voice service between Bluetooth modules by adding a data rate of voice and a corresponding SCO packet format in a Bluetooth wireless device.

In accordance with the above object, the present invention provides a wireless section voice coding scheme to be used in establishing a link for providing voice and data communication services between a master and a slave in a short range wireless communication device. A first speech coding scheme having a 64 kbps data rate and a second speech coding scheme having a second data rate less than the 64 kbps data rate, wherein the first and second speech coding schemes correspond to the first and second speech coding schemes, respectively. In the process of defining a packet type and establishing a link between the master and the slave, the master and the slave use a specification including the defined first and second voice coding schemes and corresponding first and second packet types. It is characterized by consisting of a protocol negotiation process.

1 is a configuration diagram of a master and slave Bluetooth devices;

2 is a detailed block diagram of a Bluetooth wireless device;

3 is a diagram illustrating a protocol of setting up an SCO link;

4 is a diagram for describing payload information according to an RF packet structure and an SCO packet format;

FIG. 5 is a diagram illustrating a band interval used for voice service by SCO packet type when the Bluetooth wireless device uses one of existing voice coding schemes having a 64kbps data rate.

FIG. 6 is a diagram illustrating a band interval used for voice service for each SCO packet type when the Bluetooth wireless device uses an ADPCM voice coding scheme having a 32kbps data rate.

7 is a table showing a data rate, a wireless section voice coding scheme and an SCO packet type according to an embodiment of the present invention;

FIG. 8 is a table summarizing packets defined for SCO and ACL link types, in particular illustrating a SCO packet type added according to an embodiment of the present invention. FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are represented by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

As in the example shown in FIG. 1, each of the master 2 and the slave 4, which are Bluetooth wireless devices (hereinafter referred to as "Bluetooth module"), has a concrete block configuration as shown in FIG. Referring to FIG. 2, each of the master 2 and the slave 4, which are Bluetooth modules BT, includes a Bluetooth host controller 10 and a Bluetooth RF unit 20. The Bluetooth host controller 10 performs a host interface and a link management function, and includes an external interface 12, a main controller 14, and a link baseband controller (LC) 16. The link baseband controller 16 performs the Bluetooth baseband processing and physical layer protocols, and the external interface 12 performs the interface between the main controller 14 and the host. The main controller 14 performs various controls for host interface and link management. In FIG. 2, the Bluetooth wireless unit 20 is composed of an RF (Radio Frequency) transmitter and an RF receiver to be responsible for wireless transmission and reception of voice or data between Bluetooth modules.

The master module 2 and the slave device 4 shown in FIG. 1 perform an Asynchronous Connection-Less (ACL) connection procedure and a Synchronous Connection-Oriented (SCO) connection procedure in order to transmit and receive voice or / and data. Set up the SCO link. The ACL connection procedure is described in detail in Appendix IV of the BLUETOOTH SPECIFICATION Version 1.0A, MESSAGE SEQUENCE CHARTS Contents 3, with the subtitle of ACL-C0NNECTION ESTABLISHMENT AND DETACHMENT. CHARTS Contents 5 is described in detail under the subheading SCO-CONNECTION ESTABLISHMENT AND DETACHMENT. For better understanding according to an embodiment of the present invention, an operation in which an SCO link is established by performing an asynchronous connection-less (ACL) connection procedure and a synchronous connection-oriented connection (SCO) connection procedure will be described in more detail with reference to FIG. 3. It is as follows. 3 is a diagram illustrating a process of setting up an SCO link as a protocol.

Among the Bluetooth modules, a Bluetooth module to transmit voice or / and data becomes a master, and a Bluetooth module receiving the data becomes a slave. As shown in FIG. 1, in order to transmit voice or / and data from the master 2 to the slave 4, the master 2 and the slave 4 perform page and page scan procedures, as shown in FIG. 3. Set up. The master 2 then sends a link establishment request, i.e., a Link Manager Protocol (LMP) _connection_req message, to the slave 4, and the slave 4 sends an LMP_accepted message to the master 2 in response. The master 2 then sends its LMP features message related to link establishment, that is, the LMP_features_req message, to the slave 4, and in response, the slave 4 also sends its own LMP specification messages related to link establishment, i.e. The LMP_features_req message is sent to the master (2). As the LMP specification information included in the LMP specification message transmitted and received between the master 2 and the slave 4, information about a voice coding method that can be accommodated among the wireless coded voice cording methods and packet types are included. Packet type information that can be accepted. The voice coding method for SCO link setting defined in BLUETOOTH SPECIFICATION Version 1.0A includes CVSD (Continuous Variable Slope Delta), A-Low (law), μ-Low (law), and the packet for SCO link establishment. Types are DV, HV1, HV2, and HV3. When the master 2 and the slave 4 negotiate and confirm the LMP specification with each other for link establishment by the above operation, the master 2 then transmits an LMP setup message, that is, an LMP_setup_complete message to the slave 4. The slave 4 transmits the LMP setup message, that is, the LMP_setup_complete message, to the master 2 in response thereto. The above description is for the ACL connection procedure, and the ACL link is established by the ACL link procedure. ACL links are characterized by packet switching, (a) symmetric and asynchronous services, and polling access schemes.

As described above, after the ACL linking procedure is performed, the master 2 transmits an SCO link request message, that is, an LMP_SCO_link_req message to the slave 4, as shown in FIG. 3, and the slave 4 responds to the SCO. The link accept message, that is, the LMP_accepted message is transmitted to the master 2. The above description is for the SCO connection procedure and the SCO link is established by the SCO connection procedure. SCO links are characterized by circuit switching, symmetric and synchronous services, and slot reservation at fixed intervals.

As described above, when the SCO link is established between the master module 2 and the slave 4, which are the Bluetooth modules, the SCO packets are transmitted and received at the 64kbps data rate between the master 2 and the slave 4 through the SCO link.

In more detail, the packet structure of the Bluetooth wireless device, the RF (Radio Frequency) packet of the SCO packet and ACL packet is composed of an access code (ACCESS CODE), a header (HEADER), payload (PAYLOAD), as shown in FIG. do. The access code (ACCESS CODE) is composed of a preamble (PREAMBLE), a sync word (SYNC WORD), a trailer (TRAILER), the header (HEADER) is an active member address (AM_ADDR), packet type (packet type; TYPE), flow control bit (FLOW), automatic repeat request (ARQN), sequential numbering scheme (header error check (HEC)). AM_ADDR in the header indicates an ID assigned to the slave by the master during the connection interval, TYPE indicates packet type information, and also indicates how many slots the packet occupies. Packet types for SCO link establishment include DV, HV1, HV2, and HV3. Packet types for ACL link establishment include DM1, DH1, AUX, DM3, DH3, DM5, and DH5. Therefore, the packet type information of one of the above packet types is recorded in the TYPE field. FLOW in the header HEADER is information for stopping data transmission when the receiving buffer becomes full. ARQN is recorded as ACK (positive) and NAK (negative) as information for making an automatic repeat request. SEQN is sequential numbering scheme information for ordering a data packet stream. HEC is information for header error check. In addition, FIG. 4 illustrates a payload configuration in a baseband SCO packet according to SCO packet types, that is, DV, HV1, HV2, and HV3. Among them, HV1 packet type has 10 bytes of voice information that can be loaded in payload, HV2 packet type has 20 bytes of voice information that can be loaded in payload, and HV3 packet type has 30 bytes of voice information that can be loaded in payload. to be.

FIG. 5 is a diagram illustrating a band interval used for voice service by SCO packet type when the Bluetooth wireless device uses one of existing coding schemes having a 64kbps data rate. 5, it should be understood that each slot period for transmitting and receiving voice and data in a Bluetooth wireless device is defined as 625 mu s. It is to be understood that FIG. 5 is a diagram for explaining how much bandwidth is occupied for voice service by SCO packet type. In fact, one packet occupies a period of 625 mu s in one slot period of 366 mu s.

When the Bluetooth wireless device uses an HV1 packet type SCO packet for voice service, as shown in FIG. 5, the period (T) of transmitting the SCO packet is 1.25 ms (= 10 bytes x 8 bit / 64 kbps), so that the entire band is used. All will be used to send and receive SCO packets only. In addition, when the Bluetooth wireless device uses the HV2 packet type SCO packet for voice service, as shown in FIG. 5, the period (T) of transmitting the SCO packet is 2.5ms (= 20 bytes x 8bit / 64kbps). 50% of the band is used to transmit and receive SCO packets. When the SCO packet of the HV3 packet type is used for the voice service, the period (T) of transmitting the SCO packet is 3.75 ms (= 30 bytes x 8 bit / 64 kbps), so that 33.3% of the entire band is shown in FIG. 5. The band section is used to transmit and receive the SCO packet.

In an embodiment of the present invention, in order to reduce the overall bandwidth occupancy rate by the voice service between Bluetooth modules as described above, a voice coding method having a 32 kbps data rate is added to the existing voice coding method. . For example, an embodiment of the present invention adds an adaptive differential pulse code modulation (ADPCM) speech coding scheme having a 32kbps data rate. The inventors have recognized that the 32 kbps ADPCM speech coding scheme is not a problem in providing a voice service to the user. The existing CT2 terminal and DECT also used 32kbps ADPCM speech coding. In addition, in the embodiment of the present invention, if the quality of voice service is somewhat reduced, a voice coding scheme having a 16kbps data rate may be further added.

Therefore, the voice coding scheme for the voice service according to an embodiment of the present invention includes three voice coding schemes of continuous variable slope delta (CVSD), A-row, and μ-law having 32kbps data rate and 32kbps. It consists of 32kbps ADPCM speech coding with data rate. In the speech coding scheme having the 64 kbps data rate, the SCO packet types include DV, HV1, HV2, and HV3. In the 32 kbps ADPCM speech coding scheme added according to an embodiment of the present invention, the SCO packet type is HV1 ', HV2'. , HV3 '. The packet structures of the packet types HV1 ', HV2 and HV3 are the same as those of HV1, HV2 and VV3 described with reference to FIG. In FIG. 7, a data rate, a wireless section voice coding scheme, and an SCO packet type according to the above-described embodiment of the present invention are shown in a table.

FIG. 8 is a table summarizing packets defined for SCO and ACL link types. In particular, FIG. 8 is a diagram illustrating an added SCO packet type according to an embodiment of the present invention. The SCO packet types HV1 ', HV2' and HV3 'defined by the 32 kbps ADPCM speech coding scheme are given undefined type codes (TYPE codes: b3, b2, b1, b0). Referring to FIG. 8, the type codes b3, b2, b1, b0 of HV1 'are set to "1001", and the type codes b3, b2, b1, b0 of HV2' are set to "1010". Type code b3, b2, b1, b0 of " 1011 ".

The negotiation between the master 2 and the slave 4 for the specifications including the data rate, the wireless section voice coding scheme, and the SCO packet type according to the embodiment of the present invention as shown in FIG. Is done on. As shown in FIG. 7, specifications including a data rate, a wireless section voice coding scheme, and an SCO packet type according to an embodiment of the present invention as shown in FIG. 7 are transmitted from the master 2 to the slave 4. Since it is included in the LMP_features_req message and the LMP_features_res message transmitted from the slave 4 to the master 2 in response thereto, the master 2 and the slave 4 negotiate LMP specifications with each other.

FIG. 6 is a diagram illustrating a band interval used for voice service by SCO packet type when a Bluetooth wireless device uses an ADPCM coding method having an added 32kbps data rate according to an embodiment of the present invention. Referring to FIG. 6, as in FIG. 5, it should be understood that each slot period for transmitting and receiving voice and data in a Bluetooth wireless device is defined as 625 mu s. And it is to be understood that FIG. 6 is a diagram for explaining how much bandwidth is occupied for voice service for each SCO packet type. In fact, one packet occupies a period of 625 mu s in one slot period of 366 mu s.

Referring to FIG. 7, when the Bluetooth wireless device uses the SCO packet of the HV1 'packet type for voice service, the period T for transmitting the SCO packet is 2.5 ms (= 10 bytes x 8 bits / 32 kbps). This means that 50% of all bands will be used to transmit / receive SCO packets, which means that the proportion of SCO packets in all bands is reduced by half compared to the case of using SCO packets of HV1 packet type. In addition, when the Bluetooth wireless device uses the SCO packet of the HV2 'packet type for voice service, the period T to transmit the SCO packet is 5ms (= 20 bytes x 8bit / 32kbps). This means that 25% of all bands are used to transmit / receive SCO packets, which means that the proportion of SCO packets in the entire band is reduced by 1/2 compared to the case of using SCO packets of HV2 packet type. In addition, when the Bluetooth wireless device uses the SCO packet of the HV3 'packet type for voice service, the period T for transmitting the SCO packet is 7.5ms (= 30 bytes x 8bit / 32kbps). This means that 16.65% of the entire band is used to transmit and receive SCO packets, which means that the proportion of SCO packets in the entire band is reduced by 1/2 compared to the case of using the SCO packet of the HV3 packet type.

For example, when one master and one slave establish an ACL link to communicate in DM1 packet type, an ACL packet can be transmitted at 108.8kbps in both directions. However, in this case, when providing a voice service in the HV1 packet type, there is no band available for transmitting the ACL packet among the entire bands, so the ACL packet of the DM1 packet type cannot be transmitted. In this case, when providing a voice service in the HV2 packet type, the available bandwidth for transmitting the ACL packet is 50% of the entire band, so the ACL packet can be transmitted at a data rate of 54.4 kbps (= 108.8 kbps * 1/2). In this case, when providing a voice service in the HV3 packet type, the available bandwidth for transmitting the ACL packet is 66.7% of the entire band, and thus the ACL packet can be transmitted at a data rate of 72.5kbps (= 108.8kbps * 2/3).

As an example, when one master and one slave establish an ACL link to communicate in DM1 packet type, an ACL packet may be transmitted at 108.8kbps in both directions. In this case, an added packet according to an embodiment of the present invention. In case of providing voice service in HV1 'packet type among all types, the available bandwidth for ACL packet transmission is 50%, so ACL packet can be transmitted at 54.4kbps (= 108.8kbps * 1/2) data rate. have. In this case, when the voice service is provided in the HV2 'packet type, the available bandwidth for transmitting the ACL packet is 75% of the entire band, so the ACL packet can be transmitted at a data rate of 81.6kbps (= 108.8kbps * 3/4). . In this case, when providing a voice service in the HV3 'packet type, the bandwidth available for transmitting ACL packets among all bands is 83.35%, so that an ACL packet can be transmitted at a data rate of 90.7kbps (= 108.8kbps * 5/6). .

As described above, in the embodiment of the present invention, since the 32 Kbps ADPCM coding format is added to the Bluetooth wireless device, the interval for sending the current SCO packet is doubled. Accordingly, the remaining bands except for the band used to transmit the SCO packet of all bands can be used to transmit the ACL packet, thereby increasing the data transmission rate for the ACL packet.

In the above description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the equivalent of claims and claims.

As described above, the present invention can efficiently use the entire band of the Bluetooth network by changing the voice data format.

Claims (5)

In the short-range wireless communication device master and slave communication method, A wireless section speech coding scheme to be used in establishing a link for providing a voice and data communication service between the master and the slave may include a first speech coding scheme having a 64kbps data rate and a second data transmission rate less than the 64kbps data rate. Defining a voice coding scheme and defining first and second packet types corresponding to the first and second speech coding schemes, respectively; When establishing a link between the master and the slave, the master and the slave may be configured to negotiate a protocol using a specification including the defined first and second voice coding schemes and corresponding first and second packet types. A communication method characterized by the above. The method of claim 1, wherein the second data rate is 32 kbps. The method of claim 1, wherein the second speech coding scheme having the second data rate is an ADPCM speech coding scheme having a 32kbps data rate. In the short-range wireless communication device master and slave communication method, Perform an ACL connection procedure and an SCO connection procedure for providing voice and data communication services between the master and the slave, and the first voice coding scheme having a 64kbps data rate and the 64kbps data in the wireless section voice coding scheme among the ACL connection procedures Negotiating a link management protocol using a specification including a second speech coding scheme having a second data rate less than the transmission rate and first and second packet types corresponding to the first and second speech coding schemes; And establishing an ACL link and an SCO link by the ACL connection procedure and the SCO connection procedure to provide a voice and data communication service between the master and the slave. 5. The method of claim 4, wherein the second speech coding scheme having the second data rate is an ADPCM speech coding scheme having a 32kbps data rate.