COMMUNICATION DEVICE

• US 20180213497A1
• Filed: 08/22/2016
• Published: 07/26/2018
• Est. Priority Date: 09/17/2015
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: YAMASHIRO, Takahisa, KUMABE, Seigou
• Granted Patent: US 10,448,347 B2
• Time in Patent Office: Days
• CPC Class Codes: H04L 7/0012 by comparing receiver clock with transmitter clock
• CPC Class Codes: H04W 4/40 for vehicles, e.g. vehicle-to-pedestrians [V2P]
• CPC Class Codes: H04W 4/48 for in-vehicle communication
• CPC Class Codes: H04W 56/0005 synchronizing of arrival of multiple uplinks
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 56/006 using known positions of transmitter and receiver

Abstract

A communication device includes: a time zone determiner section that identifies a switching point of time of communication time zones based on a clock time and determines whether the communication time zones are switched based on the clock time and the switching point of time; a channel switch section that designates a communication-target channel by switching the communication time zones at the identified switching point of time; a transmission processor section that performs a data transmission using the communication-target channel designated, and prohibits data transmission from being performed for a predetermined transmission prohibition duration time before and after the switching point of time; an error assessor section that assesses an error amount that is a degree of an error of the clock time against the reference clock time; and a transmission prohibition-time adjuster section that increases the transmission prohibition duration time as the error amount increases.

Claims

1. A communication device that is one of a plurality of communication devices used in a mobile communication system,

the communication devices performing direct wireless communication using a control channel and a service channel among communication channels that are achieved with mutually different frequencies, wherein two communication time zones of a control channel time zone and a service channel time zone are alternately switched, the control channel time zone where communication is performed using the control channel, the service channel time zone where communication is performed using the service channel,

the communication device comprising:

a time holder section configured to hold a clock time at present based on a clock signal outputted successively from a clock generator;

a synchronization information acquirer section configured to acquire synchronization information used to synchronize the clock time held in the time holder with a predetermined reference clock time;

a time amender section configured to perform amendment that amends the clock time held in the time holder section to decrease an error between the clock time held in the time holder section and the reference clock time based on the synchronization information;

a time zone determiner section configured to

identify a switching point of time at which the communication time zones are switched based on the clock time held in the time holder section, and

determine whether the communication time zones are switched based on the switching point of time and the clock time held in the time holder section;

a channel switching section configured to designate a communication-target channel being a channel for a communication target by switching the communication time zones at the switching time identified by the time zone determiner section;

a transmission processor section configured to

perform a data transmission using the communication-target channel designated by the channel switching section, and

prohibit data transmission from being performed for a predetermined transmission prohibition duration time before and after the switching point of time;

an error assessor section configured to assess an error amount being a degree of the error between the clock time held in the time holder section and the reference clock time; and

a transmission prohibition-time adjuster section configured to adjust the transmission prohibition duration time depending on the error amount assessed by the error assessor section,

wherein

the transmission prohibition-time adjuster section increases the transmission prohibition duration time as the error amount assessed by the error assessor section increases.

2. The communication device according to claim 1, wherein:

the synchronization information acquirer section acquires a plurality of kinds of the synchronization information, the kinds being mutually different in accuracy against the reference clock time; and

the error assessor section assesses the error amount depending on the kind of the synchronization information used when the time amender section performs last amendment, which is performed most recently.

3. The communication device according to claim 2, further comprising:

a positioning radio receiver configured to receive radio waves transmitted from a positioning satellite in global navigation satellite system; and

a reception processor section configured to receive a timing advertisement signal that advertises a switching point of time at which seconds are switched in the reference clock time, the timing advertisement signal being transmitted from a different communication device in the mobile communication system,

wherein;

the synchronization information acquirer section acquires, as the synchronization information, the timing advertisement signal and reference timing information that indicates a switching point of time at which seconds are switched in the reference clock time, the reference timing information being acquired as a result of positioning computation using radio waves received by the positioning radio receiver; and

the error assessor section assesses the error amount depending on the synchronization information uses in the last amendment performed by the time amender, such that the error amount when the reference timing information is used as the synchronization information is smaller than the error amount when the timing advertisement signal is used as the synchronization information.

4. The communication device according to claim 1, further comprising:

an importance acquirer section configured to acquire an importance of a data that the transmission processor section is going to transmit,

wherein

the transmission prohibition-time adjuster section increases the transmission prohibition time as the importance becomes higher.

5. The communication device according to claim 1, wherein

the error assessor section assesses the error amount to be greater as an elapsed time since the time amender section performs last amendment that is performed most recently increases.

6. The communication device according to claim 1, wherein:

the synchronization information acquirer section acquires, as the synchronization information, an event of a different communication device starting communication using the service channel among the communication devices; and

the time amender section identifies a switching point of time at which the communication time zone is switched from the control channel time zone into the service channel time zone based on a point of time at which the different communication device starts the communication using the service channel, amending the clock time held by the time holder section.