Radio communication system using variable packet length

• US 20010044315A1
• Filed: 04/25/2001
• Published: 11/22/2001
• Est. Priority Date: 05/22/2000
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Okada, Minoru, Aoki, Yutaka
• Granted Patent: US 6,788,951 B2
• Time in Patent Office: Days
• US Class Current: 455/524
• CPC Class Codes: H04L 1/0007 by modifying the frame length
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A radio communication system performs radio communication between a terminal station installed on a vehicle and a plurality of base stations provided along a roadside. The system detects a vehicle traveling speed in each communication area formed by each base station. The vehicle traveling speed is detected by a method which uses radio communication between the terminal station and the base stations. The time of the vehicle stay in the communication area is estimated based on the detected vehicle traveling speed, and the length of a packet is determined based on the estimated time of the vehicle stay in the communication area. In this way, the present system performs data transmission using a packet of an appropriate length according to the detected vehicle traveling speed.

Claims

1. A radio communication system comprising:

a terminal station installed on a mobile object; and

a base station provided along a traveling route of the mobile object,

wherein the base station forms a limited communication area and performs radio communication with the terminal station when the terminal station is in the communication area,

wherein the base station transmits a radio signal of a predetermined reference frequency toward the terminal station, and the terminal station receives the radio signal from the base station, and

wherein the terminal station detects a mobile object traveling speed based on a difference between a frequency of the received radio signal and the predetermined reference frequency, and communicates the detected mobile object traveling speed to the base station.

7. A radio communication system as set forth in

claim 1

,

wherein the terminal station communicates terminal station ID for identifying the terminal station to the base station along with the detected mobile object traveling speed.

13. A radio communication system as set forth in

claim 1

,

wherein a plurality of base stations are provided at predetermined intervals along the traveling route of the mobile object,

wherein the communication area formed by each of the base stations is sized not to include a plurality of terminal stations simultaneously, and

wherein the communication areas formed by the base stations are configured not to overlap each other.

19. A radio communication system as set forth in

claim 13

,

wherein each of the communication areas is a largest size as far as it cannot include a plurality of terminal stations simultaneously.

38. A radio communication system as set forth in

claim 33

,

wherein the base station obtains a mobile object traveling speed by using one of the methods as set forth in

claims 1

to

6

when data is divided and transmitted in a plurality of communication areas corresponding to base stations arranged in the traveling direction of the mobile object.

39. A radio communication system as set forth in

claim 33

,

wherein the terminal station obtains a mobile object traveling speed by using one of the methods as set forth in claims 1, 2, and 6 when data is divided and transmitted in a plurality of communication areas corresponding to base stations arranged in the traveling direction of the mobile object.

2. A radio communication system comprising:

a terminal station installed on a mobile object; and

a base station provided along a traveling route of the mobile object,

wherein the base station forms a limited communication area and performs radio communication with the terminal station when the terminal station is in the communication area,

wherein the base station transmits a radio signal of a predetermined reference bit rate and a predetermined reference frequency toward the terminal station, and the terminal station receives the radio signal from the base station, and

wherein the terminal station detects a mobile object traveling speed based on a difference between a bit rate of the received radio signal and the predetermined reference bit rate, and communicates the detected mobile object traveling speed to the base station.

8. A radio communication system as set forth in

claim 2

,

wherein the terminal station communicates terminal station ID for identifying the terminal station to the base station along with the detected mobile object traveling speed.

14. A radio communication system as set forth in

claim 2

,

wherein a plurality of base stations are provided at predetermined intervals along the traveling route of the mobile object,

wherein the communication area formed by each of the base stations is sized not to include a plurality of terminal stations simultaneously, and

wherein the communication areas formed by the base stations are configured not to overlap each other.

20. A radio communication system as set forth in

claim 14

,

wherein each of the communication areas is a largest size as far as it cannot include a plurality of terminal stations simultaneously.

3. A radio communication system comprising:

a terminal station installed on a mobile object; and

a base station provided along a traveling route of the mobile object,

wherein the base station forms a limited communication area and performs radio communication with the terminal station when the terminal station is in the communication area,

wherein the terminal station transmits a radio signal of a predetermined reference frequency toward the base station, and the base station receives the radio signal from the terminal station, and

wherein the base station detects a mobile object traveling speed based on a difference between a frequency of the received radio signal and the predetermined reference frequency.

10. A radio communication system as set forth in

claim 3

,

wherein the terminal station modulates the radio signal of the reference frequency by an information signal representing terminal station ID for identifying the terminal station by using a predetermined modulation technique before the radio signal of the reference frequency is transmitted toward the base station.

15. A radio communication system as set forth in

claim 3

,

wherein a plurality of base stations are provided at predetermined intervals along the traveling route of the mobile object,

wherein the communication area formed by each of the base stations is sized not to include a plurality of terminal stations simultaneously, and

wherein the communication areas formed by the base stations are configured not to overlap each other.

21. A radio communication system as set forth in

claim 15

,

wherein each of the communication areas is a largest size as far as it cannot include a plurality of terminal stations simultaneously.

4. A radio communication system comprising:

a terminal station installed on a mobile object; and

a base station provided along a traveling route of the mobile object,

wherein the base station forms a limited communication area and performs radio communication with the terminal station when the terminal station is in the communication area,

wherein the terminal station transmits a radio signal of a predetermined reference bit rate and a predetermined reference frequency toward the base station, and the base station receives the radio signal from the terminal station, and

wherein the base station detects a mobile object traveling speed based on a difference between a bit rate of the received radio signal and the predetermined reference bit rate.

11. A radio communication system as set forth in

claim 4

,

wherein the terminal station modulates the radio signal of the reference frequency by an information signal representing terminal station ID for identifying the terminal station by using a predetermined modulation technique before the radio signal of the reference frequency is transmitted toward the base station.

16. A radio communication system as set forth in

claim 4

,

wherein a plurality of base stations are provided at predetermined intervals along the traveling route of the mobile object,

wherein the communication area formed by each of the base stations is sized not to include a plurality of terminal stations simultaneously, and

wherein the communication areas formed by the base stations are configured not to overlap each other.

22. A radio communication system as set forth in

claim 16

,

wherein each of the communication areas is a largest size as far as it cannot include a plurality of terminal stations simultaneously.

5. A radio communication system comprising:

a terminal station installed on a mobile object; and

a base station provided along a traveling route of the mobile object,

wherein the base station forms a limited communication area and performs radio communication with the terminal station when the terminal station is in the communication area,

wherein the base station transmits a non-modulated radio signal of a reference frequency toward the terminal station, and the terminal station receives the non-modulated radio signal from the base station,

wherein the terminal station modulates the received non-modulated radio signal by a predetermined modulation technique and transmits the modulated signal toward the base station, and

wherein the base station detects a mobile object traveling speed based on a difference between a frequency of the received modulated radio signal and the reference frequency of transmitted non-modulated radio signal.

12. A radio communication system as set forth in

claim 5

,

wherein the terminal station modulates the received non-modulated radio signal by an information signal representing terminal station ID for identifying the terminal station by using a predetermined modulation technique before the radio signal is transmitted toward the base station, and

wherein the base station obtains the terminal station ID by demodulating the modulated signal received from the terminal station.

17. A radio communication system as set forth in

claim 5

,

wherein a plurality of base stations are provided at predetermined intervals along the traveling route of the mobile object,

wherein the communication area formed by each of the base stations is sized not to include a plurality of terminal stations simultaneously, and

wherein the communication areas formed by the base stations are configured not to overlap each other.

23. A radio communication system as set forth in

claim 17

,

wherein each of the communication areas is a largest size as far as it cannot include a plurality of terminal stations simultaneously.

6. A radio communication system comprising:

a terminal station installed on a mobile object; and

a base station provided along a traveling route of the mobile object,

wherein the base station forms a limited communication area and performs radio communication with the terminal station when the terminal station is in the communication area, and

wherein the terminal station has a speed detection device which detects a mobile object traveling speed by using a speed sensor installed on the mobile object or GPS, and communicates the mobile object traveling speed detected by the speed detection device to the base station so that the base station controls the radio communication with the terminal station based on the received traveling speed.

9. A radio communication system as set forth in

claim 6

,

wherein the terminal station communicates terminal station ID for identifying the terminal station to the base station along with the detected mobile object traveling speed.

18. A radio communication system as set forth in

claim 6

,

wherein a plurality of base stations are provided at predetermined intervals along the traveling route of the mobile object,

wherein the communication area formed by each of the base stations is sized not to include a plurality of terminal stations simultaneously, and

wherein the communication areas formed by the base stations are configured not to overlap each other.

24. A radio communication system as set forth in

claim 18

,

wherein each of the communication areas is a largest size as far as it cannot include a plurality of terminal stations simultaneously.

25. A terminal station being installed on a mobile object and performing radio communication with a base station provided along a traveling route of the mobile object,

wherein the base station transmits a radio signal of a predetermined reference frequency,

wherein the terminal station receives the radio signal from the base station, and analyzes a frequency of the received radio signal, and

wherein the terminal station detects a mobile object traveling speed based on a difference between the analyzed frequency and the predetermined reference frequency, and communicates the detected mobile object traveling speed to the base station.

29. A terminal station as set forth in

claim 25

,

wherein the terminal station transmits terminal station ID for identifying the terminal station to the base station along with the detected traveling speed of the mobile object.

26. A terminal station being installed on a mobile object and performing radio communication with a base station provided along a traveling route of the mobile object,

wherein the base station transmits a radio signal of a predetermined reference bit rate and a predetermined reference frequency,

wherein the terminal station receives the radio signal from the base station, and analyzes a bit rate of the received radio signal, and

wherein the terminal station detects a mobile object traveling speed based on a difference between the analyzed bit rate and the predetermined reference bit rate, and communicates the detected mobile object traveling speed to the base station.

30. A terminal station as set forth in

claim 26

,

wherein the terminal station transmits terminal station ID for identifying the terminal station to the base station along with the detected traveling speed of the mobile object.

27. A base station being provided along a traveling route of a mobile object on which a terminal station is installed, and performing radio communication with a terminal station which is in a communication area formed by the base station,

wherein the terminal station transmits a radio signal of a predetermined reference frequency,

wherein the base station receives the radio signal and analyzes a frequency of the received radio signal, and

wherein the base station detects a mobile object traveling speed based on a difference between the analyzed frequency and the predetermined frequency.

31. A base station as set forth in

claim 27

,

wherein the terminal station modulates the radio signal of a predetermined frequency by an information signal representing terminal station ID for identifying the terminal station by using a predetermined modulation technique before it transmits the radio signal toward the base station, and

wherein the base station obtains the terminal ID by demodulating the received radio signal.

28. A base station being provided along a traveling route of a mobile object on which a terminal station is installed, and performing radio communication with a terminal station which is in a communication area formed by the base station,

wherein the terminal station transmits a radio signal of a predetermined reference bit rate and a predetermined reference frequency,

wherein the base station receives the radio signal and analyzes a bit rate of the received radio signal, and

wherein the base station detects a mobile object traveling speed based on a difference between the analyzed bit rate and the predetermined bit rate.

32. A base station as set forth in

claim 28

,

wherein the terminal station modulates the radio signal of a predetermined frequency by an information signal representing terminal station ID for identifying the terminal station by using a predetermined modulation technique before it transmits the radio signal toward the base station, and

wherein the base station obtains the terminal ID by demodulating the received radio signal.

33. A radio communication system comprising a terminal station installed on a mobile object and a plurality of base stations provided along a traveling route of the mobile object, each of the base stations forming a limited communication area and performing radio communication with the terminal station which is in the corresponding communication area,

wherein if data transmission between a base station and a terminal station cannot be completed in one communication area corresponding to the base station, data is divided and transmitted in a plurality of communication areas corresponding to base stations arranged in a traveling direction of the mobile object, and

wherein a mobile object traveling speed is detected, and data transmission is performed using a packet of an appropriate length according to the detected mobile object traveling speed.

34. A radio communication system as set forth in

claim 33

,

wherein the packet includes at least one frame, and a length of the packet can be adjusted by varying a number of frames included in the packet.

35. A radio communication system as set forth in

claim 33

,

wherein the packet includes at least one frame, and a length of the packet can be adjusted by varying a length of a frame.

36. A radio communication system as set forth in

claim 33

,

wherein a packet of an appropriate length is formed in real time according to the detected traveling speed of the mobile object, and the packet is transmitted.

37. A radio communication system as set forth in

claim 33

,

wherein a plurality of packets of different lengths are formed beforehand, and

wherein a packet of an appropriate length is selected from the formed packets of different lengths, and the selected packet is transmitted.

40. A radio communication system as set forth in

claim 33

,

wherein the communication area formed by each of the base stations is sized not to include a plurality of terminal stations simultaneously, and

wherein the communication areas formed by the base stations are configured not to overlap each other.

41. A radio communication system as set forth in

claim 40

,

wherein each of the communication areas is a largest size as far as it cannot include a plurality of terminal stations simultaneously.