JP3879983B2 - Wireless call system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wireless call system, and in particular, one of a plurality of call units that communicate with each other wirelessly operates in a master mode, the other call unit operates in a slave mode, and each call unit is battery-powered. The present invention relates to a wireless communication system suitable for the system.
[0002]
[Prior art]
In order to enable conversation between passengers on motorcycles, each person's helmet is equipped with a so-called intercom system consisting of speakers, microphones and communication units so that passengers can talk directly to each other. A communication system (wireless) is disclosed, for example, in a microfilm disclosed in Japanese Utility Model Publication No. 62-155535. Japanese Patent Laid-Open No. 2001-155534 discloses a technology that employs Bluetooth as an intercom wireless communication standard.
[0003]
[Problems to be solved by the invention]
When the wireless communication unit is installed in each occupant's helmet, if the power is supplied from the vehicle side, wiring to connect the vehicle and the occupant's helmet is required. Can be considered. In this case, in order to enable long-time driving with a battery, a technique for reducing power consumption is important.
[0004]
In a general wireless communication system, when a period during which communication is not performed exceeds a predetermined time, each communication unit shifts to a power saving mode called a sleep mode or a standby mode.
[0005]
On the other hand, in Bluetooth, which is spreading as a short-range wireless communication system, one of a plurality of communication units functions as a master and the other functions as a slave, and forms a short-distance network called a piconet. Even in this piconet, a power saving mode such as “Park Mode” or “Sniff Mode” is prepared, but only the slave can shift to this power saving mode, and the master cannot shift.
[0006]
For this reason, only the battery of the communication unit that operates as a master tends to be consumed earlier than the batteries of other communication units that operate as a slave. And when the master falls into an inoperable state due to power shortage, there has been a technical problem that other slaves become incapable of communication despite their remaining battery power.
[0007]
The object of the present invention is to solve the above-mentioned problems of the prior art, and the role of the master or slave assigned to each communication unit is automatically set so that the remaining battery power of the plurality of communication units constituting the network is equalized. It is to provide a wireless communication system that switches to
[0008]
[Means for Solving the Problems]
In order to achieve the above-described object, the present invention includes a plurality of communication units constituting a network, and the plurality of communication units operate partly in the master mode and others operate in the slave mode. In the wireless communication system, the communication unit is permitted to enter the power saving mode while operating in the slave mode, and prohibited to enter the power saving mode while operating in the master mode. It is characterized in that such measures are taken.
[0009]
(1) Each of the communication units includes means for measuring the operation continuation time as the current master when the communication unit itself is operating as a master, and when the operation continuation time exceeds a predetermined time, another communication unit And the roles of the master / slave are interchanged.
[0010]
(2) Each of the communication units includes a battery as a driving power source, means for measuring an operation duration prediction time in the current operation mode, and means for exchanging information on the operation duration prediction time with other terminals. And the roles of the master / slave are interchanged so that the terminal with the long predicted operation duration operates in the master mode and the terminal with the small predicted operation duration operates in the slave mode. And
[0011]
(3) Each of the communication units comprises means for counting the accumulated time during which the communication unit is operating in the power saving mode, and means for exchanging information on the accumulated time with another communication unit. The roles of the master / slave are interchanged so that a long terminal operates in a master mode and a terminal with a short cumulative time operates in a slave mode.
[0012]
According to the feature (1) described above, since the operation mode of each communication unit can be changed every predetermined time, the time during which each communication unit operates as a master can be made equal. Therefore, it is possible to prevent an imbalance in which only some of the communication units continue to operate as a master and only the remaining battery level is significantly reduced.
[0013]
According to the above feature (2), the estimated operation maintenance time when the current operation mode (master or slave) is continued for each communication unit is measured, and the communication unit with the longest operation time is operated in the master mode. Even when the power consumption in each operation mode differs for each communication unit, the master mode can be assigned to the optimum communication unit.
[0014]
According to the feature (3) described above, the accumulated time of operation in the power saving mode is obtained for each communication unit, and the master mode is assigned to the communication unit that is predicted to have the maximum accumulated time, that is, the remaining battery level. Thus, it is possible to prevent an imbalance in which only the remaining battery power of some communication units is significantly reduced.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically showing the minimum configuration of a vehicular wireless communication system to which the present invention is applied. Helmets 1a and 1b worn by a driver and a passenger are microphones 11a and 11b, a speaker 12a, 12b and wireless communication units 13a and 13b are provided.
[0016]
Each of the wireless communication units 13a and 13b conforms to the Bluetooth standard, and performs wireless communication with each other while operating in the master mode and the other in the slave mode on the piconet that uses them as accommodating terminals. Each communication unit 13a, 13b can shift to a power saving mode (park mode or sniff mode) under a predetermined condition only when operating in the slave mode.
[0017]
FIG. 2 is a block diagram showing the configuration of the main part of the communication unit 13a. The same reference numerals as those described above represent the same or equivalent parts.
[0018]
The antenna 314 of the communication unit 13a is connected to the RFIC 316 via the band pass filter 315. The RFIC 316 has a reception side path and a transmission side path, and these are switched by the antenna switch SW316a. The reception side path is composed of a low noise amplifier LNA, a mixer IRM, an IF band pass filter IFBPF, a limit amplifier LIMAMP, a demodulator DEM, and a low pass filter LPF. On the other hand, the transmission side circuit is composed of a Gaussian filter, a switch SW, a PLL circuit, an LPF, voltage controlled oscillators VCO and SW, and a power amplifier PA.
[0019]
A baseband IC 317 that is a baseband signal processing device includes a baseband controller, a ROM, a RAM, a CPU, a PCM / CVSD transcoder, an external bus I / F, a device controller, and a power supply voltage, each connected to a bus. It comprises a voltage regulator that stabilizes the power supply and a power management unit PMU.
[0020]
The sound picked up by the microphone 11 a is amplified by the power amplifier 318 and connected to the input / output I / F 320. On the other hand, the received audio signal sent from the input / output I / F 320 is amplified by the power amplifier 319, reaches the speaker 12a, and is reproduced as audio. A main SW 322 is connected to the switch interface SWI / F 321. Note that the RFIC 316 and the baseband IC 317 are well-known circuits, and thus a detailed description of the operation is omitted.
[0021]
FIG. 3 is a diagram schematically showing another configuration example of the vehicular wireless communication system to which the present invention is applied. The same reference numerals as those described above represent the same or equivalent parts.
[0022]
In the present embodiment, not only the communication units 13a and 13b attached to the helmets 1a and 1b of the driver and the passenger, but also mobile phones (mobile phones or PHS) 13c and 13d carried by the driver and the passenger are Bluetooth. A communication function conforming to the standard is provided. The communication units 13a and 13b and the mobile phones 13c and 13d constitute a piconet, and one performs wireless communication with each other while operating in the master mode and the other in the slave mode. Also in the present embodiment, each communication unit (including a mobile terminal; the same applies hereinafter) can shift to a low power consumption mode (sleep mode) under a predetermined condition only when operating in the slave mode.
[0023]
As in each of the wireless communication systems described above, in a communication system in which one of a plurality of communication units behaves as a master and the others as slaves, and only the slave can enter the power saving mode, the remaining battery level of the communication unit operating in the master mode However, the battery level of the communication unit operating in the slave mode is lowered faster. Therefore, in the present embodiment, the remaining battery level of each communication unit is uniformly reduced by the operation modes of each communication unit changing each other.
[0024]
Next, a procedure for switching the operation mode between the communication unit operating in the master mode and the communication unit operating in the slave mode will be described.
[0025]
FIG. 4 is a flowchart showing the operation of the first embodiment of the operation mode change procedure, which is repeatedly executed at a predetermined cycle in each communication unit. Here, in the communication mode (two communication units) described with reference to FIG. 1, the description starts from a state in which the communication unit 13a operates in the master mode and the communication unit 13b operates in the slave mode.
[0026]
In step S11, it is determined whether its current operation mode is a master or a slave. If it is the master mode (that is, the communication unit 13a), the process proceeds to step S12, and if it is the slave mode (that is, the communication unit 13b), the process ends. In step S12, the communication unit 13a operating in the master mode obtains a duration Tmc_a from when the communication unit 13a starts operating in the current master mode.
[0027]
In step S13, the operation duration time Tmc_a as the master is compared with a predetermined replacement reference time Tmc_a_ref. If the duration time Tmc_a is shorter than the alternation reference time Tmc_a_ref, the processing is terminated and the operation in the master mode is continued. On the other hand, if the duration time Tmc_a is equal to or longer than the replacement reference time Tmc_a_ref, the process proceeds to step S14. In step S14, a master / slave switching request packet (LMP_switch_req) is transmitted to the communication unit 13b operating in the slave mode.
[0028]
FIG. 5 is a communication sequence showing a procedure in which the master and the slave switch their operation modes in response to the master / slave switching request packet (LMP_switch_req) transmitted from the master as described above.
[0029]
Upon receiving the (LMP_switch_req) master / slave switch request packet, the slave mode communication unit 13b returns an LMP_accepted packet (acknowledgment of acceptance of the switch request) in response to this and further performs intra-piconet synchronization. An LMP_slot_offset (slot offset information) packet and an FHS (synchronization establishment by FHS packet) packet for establishment are transmitted. In response to this, the communication unit 13a in the master mode transmits its own ID packet for confirmation of reception. Thereafter, a POLL (polling) packet is newly transmitted from the communication unit 13b operating in the master mode, and a NULL packet is returned from the communication unit 13a newly operating in the slave mode.
[0030]
In the above-described embodiment, the communication unit 13a operating in the master mode has been described as counting the duration, but conversely, the communication unit 13b operating in the slave mode has the duration. The master / slave switching request packet (LMP_switch_req) may be transmitted to the communication unit operating in the master mode when the time is measured and the duration exceeds a predetermined time.
[0031]
FIG. 6 is a communication sequence showing a procedure in which the master and the slave change their operation modes in response to the master / slave change request (LMP_switch_req) transmitted from the slave.
[0032]
According to this embodiment, since the operation mode of each communication unit can be changed every predetermined time, it is possible to equalize the time during which each communication unit operates as a master. Therefore, it is possible to prevent an imbalance in which only one communication unit continues to operate as a master and only the remaining battery level is significantly reduced.
[0033]
FIG. 7 is a flowchart showing the operation of the second embodiment of the operation mode change procedure, which is repeatedly executed in each communication unit at a predetermined cycle. Here, in the communication mode (four communication units) described with reference to FIG. 3, the communication unit 13a operates in the master mode, and the communication unit 13b and the mobile phones 13c and 13d operate in the slave mode. Begin.
[0034]
In step S21, each of the communication units 13a, 13b and the mobile phones 13c, 13d obtains their battery remaining capacity Q (Qa, Qb, Qc, Qd) based on the terminal voltage and charge / discharge history. If the battery is a lithium ion battery, the remaining battery capacity can be accurately obtained based on information from the power management means built in the lithium ion battery.
[0035]
In step S22, based on its own battery remaining capacity Q and its current operation mode, the time during which the current operation mode (master or slave) can be continued normally when the current operation mode (master or slave) is continued, that is, the operation is maintained. Calculate the estimated time. For example, in the case of the communication unit 13a operating in the master mode, the predicted operation maintenance time can be obtained by dividing its own battery remaining capacity Qa by the average power consumption when operating in the master mode.
[0036]
In step S23, it is determined whether the current operation mode is the master or the slave. If it is the master mode, the process proceeds to step S24, and if it is the slave mode, the process proceeds to step S28. Therefore, if it is the communication unit 13b and the mobile phones 13c and 13d, the process proceeds to step S28, and the predicted operation maintenance time T (Tb, Tc, Td) obtained in step S22 is transmitted to the communication unit 13a operating in the master mode. To do.
[0037]
On the other hand, if the communication unit 13a is in the master mode, the process proceeds to step S24, and the other operation unit (13b, 13c, 13d) operating in the slave mode in the piconet to which it belongs belongs to the predicted operation maintenance time T ( Tb, Tc, Td) are acquired.
[0038]
In step S25, from the predicted operation maintenance time Ta operating in the master mode and the predicted operation maintenance times Tb, Tc, Td acquired from the other communication units 13b, 13c, 13d operating in the slave mode. The longest one is selected and registered as the longest maintenance prediction time Tmax. In the present embodiment, the description is continued assuming that the operation maintenance predicted time Tb of the communication unit 13b is the longest.
[0039]
In step S26, the difference between the longest maintenance predicted time Tmax (= Tb) and its own motion maintenance predicted time Ta is compared with a predetermined alternation determination time Tref.
[0040]
If the difference is smaller than the determination time Tref, the process is terminated as it is. If the difference is larger than the determination time Tref, the process proceeds to step S27. In step S27, in order to shift the communication unit (in this embodiment, the communication terminal 13b) having the longest operation maintenance prediction time T (Tmax) to the master mode, the communication unit itself shifts to the master mode. A master / slave switching request packet (LMP_switch_req) is transmitted to 13b.
[0041]
Thereafter, the communication sequence described with reference to FIG. 5 is executed, and the communication unit 13a that has been operating in the master mode until then shifts to the slave mode, and the communication unit 13b that has been operated in the slave mode shifts to the master mode. To do.
[0042]
According to the present embodiment, the estimated operation maintenance time when the current operation mode is continued for each communication unit is measured, and the communication unit with the longest operation is operated in the master mode. Even when the power consumption of the modes is different, the master mode can be assigned to the optimum communication unit.
[0043]
In the second embodiment described above, the operation maintenance prediction time is obtained based on the remaining battery capacity Q, and the communication unit having the longest operation maintenance prediction time is operated as a master. The communication unit having the largest value may be operated as a master. At this time, if a lithium-ion battery is used as the battery, the remaining battery capacity can be accurately recognized based on information from the power management means built in the lithium-ion battery, so accurate determination can be made with a simple configuration. become.
[0044]
FIG. 8 is a flowchart showing the operation of the third embodiment of the operation mode change procedure, which is repeatedly executed in each communication unit at a predetermined cycle. Here, in the communication mode (four communication units) described with reference to FIG. 3, the communication unit 13a operates in the master mode, and the communication unit 13b and the mobile phones 13c and 13d operate in the slave mode. Begin.
[0045]
In step S31, each of the communication units 13a and 13b and the mobile phones 13c and 13d obtains an accumulated time Ts (Ts_a, Ts_b, Ts_c, Ts_d) in which the communication units 13a and 13b and the mobile phones 13c and 13d operate in the power saving mode. In step S32, it is determined whether the current operation mode is the master or the slave. If it is the master mode, the process proceeds to step S34, and if it is the slave mode, the process proceeds to step S33. Therefore, if the communication unit 13b and the mobile phones 13c and 13d are used, the process proceeds to step S33, and the accumulated time Ts (Ts_b, Ts_c, Ts_d) obtained in step S31 is transmitted to the communication unit 13a operating in the master mode.
[0046]
On the other hand, if the communication unit 13a is in the master mode, the process proceeds to step S34, and the accumulated time Ts (Ts_b, T) from other communication units (13b, 13c, 13d) operating in the slave mode in the piconet to which the master mode belongs. Ts_c, Ts_d) are acquired.
[0047]
In step S35, the communication unit 13a operating in the master mode has its own accumulated time Ts_a and the accumulated time Ts_b, Ts_c, Ts_d acquired from the other communication units 13b, 13c, 13d operating in the slave mode. The longest one is selected and registered as the longest cumulative time Tmax. In the present embodiment, the description will be continued assuming that the accumulated time Ts_b of the communication unit 13b is the longest.
[0048]
In step S36, it is determined whether or not the difference between the longest accumulated time Tmax (= Ts_b) and its own accumulated time Ts_a is equal to or longer than a predetermined alternation reference time Ts_ref.
[0049]
If the difference is smaller than the reference time Ts_ref, the process is terminated as it is. If the difference is equal to or greater than the reference time Tsref, the process proceeds to step S37. In step S37, the communication unit 13a performs communication in order to shift the communication unit (in this embodiment, the communication terminal 13b) having the longest accumulated time Ts (Tmin) to the master mode. A master / slave switch request packet (LMP_switch_req) is transmitted to the unit 13b.
[0050]
Thereafter, the communication sequence described with reference to FIG. 5 is executed, and the communication unit 13a that has been operating in the master mode until then shifts to the slave mode, and the communication unit 13b that has been operated in the slave mode shifts to the master mode. To do.
[0051]
According to the present embodiment, the accumulated time of operation in the power saving mode is obtained for each communication unit, and the master mode is assigned to the communication unit that is predicted to have the longest battery capacity, that is, the remaining battery level is maximum. It is possible to prevent an imbalance in which only the remaining battery power of the unit is significantly reduced.
[0052]
FIG. 9 is a flowchart showing the operation of the fourth embodiment of the operation mode change procedure, which is repeatedly executed at a predetermined cycle in each communication unit. Here, in the communication mode (four communication units) described with reference to FIG. 3, the communication unit 13a operates in the master mode, and the communication unit 13b and the mobile phones 13c and 13d operate in the slave mode. Begin.
[0053]
In step S41, each of the communication units 13a and 13b and the mobile phones 13c and 13d obtains an accumulated time Tm (Tm_a, Tm_b, Tm_c, Tm_d) in which the communication unit 13a and 13b and the mobile phone 13c operate as a master. In step S42, it is determined whether the current operation mode is master or slave. If it is the master mode, the process proceeds to step S44, and if it is the slave mode, the process proceeds to step S43. Therefore, if the communication unit 13b and the mobile phones 13c and 13d are used, the process proceeds to step S43, and the accumulated time Tm (Tm_b, Tm_c, Tm_d) obtained in step S41 is transmitted to the communication unit 13a operating in the master mode.
[0054]
On the other hand, if the communication unit 13a is in the master mode, the process proceeds to step S44, and the accumulated time Tm (Tm_b, Tm_b, from other communication units (13b, 13c, 13d) operating in the slave mode in the piconet to which the master mode belongs. Tm_c, Tm_d) are acquired.
[0055]
In step S45, the communication unit 13a operating in the master mode has the accumulated time Tm_a and the accumulated times Tm_b, Tm_c, and Tm_d acquired from the other communication units 13b, 13c, and 13d operating in the slave mode. The shortest one is selected and registered as the shortest cumulative time Tmin. In the present embodiment, the description will be continued assuming that the accumulated time Tm_c of the communication unit 13c is the shortest.
[0056]
In step S46, it is determined whether or not the difference between the shortest cumulative time Tmin (= Tm_c) and the own cumulative time Tm_a is equal to or longer than a predetermined replacement reference time Tm_ref.
[0057]
If the difference is smaller than the reference time Tm_ref, the process is terminated as it is, and if the difference is equal to or greater than the reference time Tmref, the process proceeds to step S47. In step S47, the communication unit 13a performs communication in order to shift the communication unit (in this embodiment, the communication terminal 13b) having the shortest (Tmin) cumulative time Tm to the master mode. A master / slave switch request packet (LMP_switch_req) is transmitted to the unit 13c.
[0058]
Thereafter, the communication sequence described with reference to FIG. 5 is executed, the communication unit 13a that has been operating in the master mode until then shifts to the slave mode, and the communication unit 13c that has been operated in the slave mode shifts to the master mode. To do.
[0059]
According to the present embodiment, the accumulated time of operation as a master is obtained for each communication unit, and this is assigned the master mode to the communication unit that is predicted to have the shortest, that is, the maximum remaining battery power. An imbalance in which only the remaining battery level is significantly reduced can be prevented.
[0060]
【The invention's effect】
According to the present invention, the following effects are achieved.
(1) Since the operation mode of each communication unit can be changed every predetermined time, the time during which each communication unit operates as a master can be made equal. Therefore, it is possible to prevent an imbalance in which only the remaining battery power of some communication units is significantly reduced.
(2) The estimated operation maintenance time when the current operation mode is continued for each communication unit is measured, and the master mode is assigned to the communication unit with the longest time, so the power consumption of each operation mode for each communication unit Even if they are different, the master mode can be assigned to the optimum communication unit.
(3) Since the remaining battery capacity is calculated for each communication unit and the master mode is assigned to the communication unit that has the maximum, it is possible to prevent an imbalance in which only the remaining battery capacity of some communication units is significantly reduced. .
(4) The accumulated time of operation in the power saving mode is obtained for each communication unit, and the master mode is assigned to the communication unit that is predicted to have the longest battery capacity, that is, the maximum remaining battery power. An imbalance in which only the amount is significantly reduced can be prevented.
(5) Since the accumulated time of operation in the master mode is obtained for each communication unit and this is the shortest, that is, the master mode is assigned to the communication unit that is predicted to have the maximum remaining battery power, the remaining battery power of some communication units It is possible to prevent an imbalance that only significantly decreases.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a minimum configuration of a vehicle radio communication system to which the present invention is applied.
FIG. 2 is a block diagram showing a configuration of a main part of a communication unit.
FIG. 3 is a diagram schematically showing another configuration example of a vehicle radio communication system to which the present invention is applied.
FIG. 4 is a flowchart of a first embodiment of an operation mode change procedure.
FIG. 5 is a diagram showing an example of a communication sequence executed between communication units that alternate master / slave.
FIG. 6 is a diagram showing another example of a communication sequence executed between communication units that alternate master / slave.
FIG. 7 is a flowchart of a second embodiment of an operation mode change procedure.
FIG. 8 is a flowchart of a third embodiment of an operation mode change procedure.
FIG. 9 is a flowchart of a fourth embodiment of an operation mode change procedure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1a, 1b ... Helmet, 11a, 11b ... Microphone, 12a, 12b ... Speaker, 13a, 13b ... Wireless communication unit, 13c, 13d ... Mobile phone

Claims (5)

A plurality of communication units comprising a network, part of which operates in the master mode, the other operates in the slave mode, and each communication unit operates in the slave mode. In the wireless communication system in which the transition to the power saving mode is permitted and the transition to the power saving mode is prohibited while operating in the master mode,
Each of the communication units includes a battery as a driving power source, and
Means for timing the accumulated time operating in master mode;
Means for exchanging the accumulated time with another communication unit;
When the communication unit operating in the master mode has its accumulated time longer than the shortest accumulated time by a predetermined replacement reference time, the communication unit having the shortest accumulated time and the master unit. / A wireless communication system characterized by alternating roles of slaves . A plurality of communication units comprising a network, part of which operates in the master mode, the other operates in the slave mode, and each communication unit operates in the slave mode. In the wireless communication system in which the transition to the power saving mode is permitted and the transition to the power saving mode is prohibited while operating in the master mode,
Each of the communication units includes a battery as a driving power source, and
Means for timing the accumulated time operating in power saving mode;
Means for exchanging the accumulated time with another communication unit;
When the communication unit operating in the master mode has the longest cumulative time in the exchanged cumulative time longer than the cumulative time by a predetermined replacement reference time, the communication unit having the longest cumulative time and the master / A wireless communication system characterized by alternating roles of slaves . A plurality of communication units comprising a network, part of which operates in the master mode, the other operates in the slave mode, and each communication unit operates in the slave mode. In the wireless communication system in which the transition to the power saving mode is permitted and the transition to the power saving mode is prohibited while operating in the master mode,
Each communication unit is
Means for timing the cumulative time that it is operating in power saving mode;
Means for exchanging information of the accumulated time with another communication unit;
Means for switching the roles of the master / slave to each other so that the terminal with the long cumulative time operates in the master mode and the terminal with the short cumulative time operates in the slave mode ,
When the communication unit operating in the master mode has the longest cumulative time in the exchanged cumulative time longer than the cumulative time by a predetermined replacement reference time, the communication unit having the longest cumulative time and the master / A wireless communication system characterized by alternating roles of slaves . The wireless communication system according to claim 1 or 2 , wherein the battery is a lithium ion battery. The wireless communication system according to any one of claims 1 to 4 , wherein each of the communication units conforms to a Bluetooth standard.

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