Wireless LAN system

• US 7,561,510 B2
• Filed: 04/28/2005
• Issued: 07/14/2009
• Est. Priority Date: 04/30/2004
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Imamura, Kimihiko, Nakashima, Daiichiro
• Primary Examiner(s): Kincaid; Lester
• Assistant Examiner(s): DOAN, PHUOC HUU
• Application Number:
  US11/116,282
• Publication Number:
  US 20050243843A1
• Time in Patent Office: 1,538 Days
• Field of Search: 370/338, 455/434, 455/422.1, 709/245
• US Class Current: 370/205
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A high-speed wireless LAN system capable of avoiding a collision of packets and maintaining the original transmission speed is provided. A transmitter is applied to an HT terminal using a second frequency band wider than a first frequency band used by a legacy terminal, in which an HT sequence is started after a legacy beacon as an occupation signal and a legacy CTS are transmitted using every frequency in the second frequency band. Due to this, an NAV is set at the legacy terminal and packets are no longer transmitted from the legacy terminal. As a result, a collision of packets is avoided and it becomes possible to perform communication between HT terminals at the original transmission speed.

Claims

1. A communication system including a transmitter and a receiver, where the transmitter is applied to a second radio communication system using a second frequency band wider than a first frequency band used in a first radio communication system and the receiver is applied to the second wireless communication system using a second frequency band wider than a first frequency band used in a first wireless communication system, comprising:

an occupation signal generation section for generating an occupation signal compatible with said first radio communication system and notifying said first radio communication system that said second radio communication system occupies a radio medium;

a transmission section for performing communication in said second radio communication system after transmitting said occupation signal using every frequency in said second frequency band, wherein said transmission section transmits a start signal for notifying that the period during which communication is performed in said second wireless communication system starts; and

a start judgment section for judging the start of the period during which said second wireless communication system occupies the radio medium based on said start signal received from the transmitter.

2. The transmitter according to claim 1, wherein:

said occupation signal generation section adds, information for specifying the period during which said second radio communication system occupies the radio medium perfectly, to said occupation signal; and

said transmission section performs communication in said second radio communication system by occupying the radio medium during said period.

3. The transmitter according to claim 1, wherein:

said occupation signal generation section adds, information that said second radio communication system occupies a part of the period of the radio medium, to said occupation signal; and

said transmission section performs communication in said second radio communication system by occupying the radio medium during said part of the period based on said information.

4. The transmitter according to claim 1, wherein said second frequency band has a band width n times (n is a natural number) that of said first frequency band.

5. The transmitter according to claim 4, wherein said occupation signal generation section comprises a symbol repeating section for repeatedly outputting transmission data corresponding to an occupation signal n times (n is a natural number) in predetermined symbol units.

6. The transmitter according to claim 1, wherein said occupation signal generation section generates said occupation signal intermittently.

7. The transmitter according to claim 1, wherein said transmission section transmits at least, out of a start signal for notifying that a period during which communication is performed in said second radio communication system starts and an end signal for notifying that a period during which communication is performed in said second radio communication system ends, said start signal.

8. The transmitter according to claim 1, wherein said occupation signal generation section adds, identification information by which said second radio communication system recognizes said occupation signal, to said occupation signal.

9. The transmitter according to claim 1, wherein:

said occupation signal generation section comprising;

at least one frequency conversion section for converting the center frequency of an input signal into a predetermined frequency and outputting a frequency-converted signal; and

an addition section for adding up said input signal and the signal outputted from said frequency conversion section.

10. The receiver according to claim 3, further comprising:

a thinning circuit for cutting out and outputting one n-th of an occupation signal received from the transmitter; and

a demodulation section for demodulating a signal inputted from said thinning circuit and outputting the received data.

11. The receiver according to claim 7, further comprising:

a measurement section for measuring an elapsed time from the start of said period;

an end judgment section for judging the end of said period based on the elapsed time from the start of said period and said start signal; and

a control section for outputting a signal for notifying the result of the judgment of the start and end of said period.

12. The receiver according to claim 7, further comprising:

an end judgment section for judging the end of said period based on said end signal received from the transmitter; and

a control section for outputting a signal for notifying the result of the judgment of the start and end of said period.

13. The receiver according to claim 8, further comprising:

a recognition section for recognizing said identification information based on said occupation signal received from the transmitter; and

a reception section for demodulating the received signal and outputting received data when said identification information is recognized, or stopping the receiving operation when said identification information is not recognized.

14. A wireless LAN system, comprising an access point further comprising the transmitter and a station further comprising the receiver according to claim 10.

15. A wireless LAN system, comprising an access point further comprising the transmitter according to claim 1 and a station further comprising the receiver.

16. The receiver according to claim 1, further comprising:

a measurement section for measuring an elapsed time from the start of said period;

an end judgment section for judging an end of said period based on the elapsed time from the start of said period and said start signal; and

a control section for outputting a signal for notifying the result of the judgment of the start and end of said period.

17. The transmitter according to claim 1, wherein said transmission section transmits a start signal for notifying that the period during which communication is performed in said second wireless communication system starts and an end signal for notifying that the period during which communication is performed in said second wireless communication system ends.

18. The receiver according to claim 17, further comprising:

an end judgment section for judging an end of said period based on an end signal received from the transmitter; and

a control section for outputting a signal for notifying the result of the judgment of the start and end of said period.

19. A communication system including a transmitter and a receiver, where the transmitter is applied to a second radio communication system using a second frequency band wider than a first frequency band used in a first radio communication system and the receiver is applied to the second wireless communication system using a second frequency band wider than a first frequency band used in a first wireless communication system, comprising:

an occupation signal generation section for generating an occupation signal compatible with said first radio communication system and notifying said first radio communication system that said second radio communication system occupies a radio medium; and

a transmission section for performing communication in said second radio communication system after transmitting said occupation signal using every frequency in said second frequency band, wherein said transmission section transmits at least, out of a start signal for notifying that a period during which communication is performed in said second radio communication system starts and an end signal for notifying that a period during which communication is performed in said second radio communication system ends, said start signal; and

a start judgment section for judging the start of the period during which said second wireless communication system occupies the radio medium based on said start signal received from the transmitter.

20. A communication method comprising:

using a signal to notify a first wireless communication system that a second wireless communication system occupies a radio medium;

wherein the second wireless communication system uses a second frequency band wider than a first frequency band used by the first wireless communication system; and

performing communication in said second wireless communication system after transmitting the signal; and

transmitting a start signal for notifying that the period during which communication is performed in said second wireless communication system starts,

wherein a receiving process applied to the second wireless communication system using a second frequency band wider than a first frequency band used in a first wireless communication system, comprising;

judging the start of the period during which said second wireless communication system occupies the medium based on said start signal received from the transmitting;

measuring the elapsed time from the start of said period;

judging the end of said period based on the elapsed time from the start of said period and said start signal; and

outputting a signal for notifying the result of the judgment of the start and end of said period.

21. A communication method, comprising:

using a signal to notify a first wireless communication system that a second wireless communication system occupies a radio medium;

wherein the second wireless communication system uses a second frequency band wider than a first frequency band used by the first wireless communication system;

performing communication in said second wireless communication system after transmitting the signal; and

transmitting a start signal for notifying that the period during which communication is performed in said second wireless communication system stats and an end signal for notifying that the period during which communication is performed in said second wireless communication system ends,

wherein a receiving process applied to the second wireless communication system using a second frequency band wider than a first frequency band used in a first wireless communication system, comprising;

judging the start of the period during which said second wireless communication system occupies the medium based on said start signal received from the transmitting;

judging the end of said period based on said end signal received from the transmitting; and

outputting a signal for notifying the result of the judgment of the start and end of said period.

22. A receiver applied to a second radio communication system uses a second frequency band wider than a first frequency band used in a first radio communication system, comprising:

a receiving section receiving a start signal for notifying that a period during which communication is started in said second wireless communication system, where the start signal received by the receiving station is subjected to demodulation and/or decoding;

a start judgment section for judging a start of the period during which said second radio communication system occupies the radio medium based on said received start signal;

a measurement section for measuring an elapsed time from the start of said period;

an end judgment section for judging an end of said period based on the elapsed time based on the start of said period and said start signal; and

a control section for outputting a signal for notifying a result of the judgment of the start and end of said period.

23. A receiver applied to a second radio communication system using a second frequency band wider than a first frequency band used in a first radio communication system, comprising:

a receiving section receiving a start signal for notifying that a period during which communication is started in said second wireless communication system and an end signal for notifying that a period during which communication is ended in said second wireless communication system, where the start signal and the end signal received by the receiving station is subjected to demodulation and/or decoding;

a start judgment section for judging a start of the period during which said second radio communication system occupies the radio medium based on said received start signal;

an end judgment section for judging an end of said period based on said end signal received; and

a control section for outputting a signal for notifying a result of the judgment of the start and end of said period.

24. A communication method where a receiving process applied to a second wireless communication system using a second frequency band wider than a first frequency band used in a first wireless communication system, comprising:

receiving a start signal for notifying that a period during which communication is started in said second wireless communication system;

demodulating and/or decoding the start signal;

judging the start of the period during which said second radio communication system occupies the radio medium based on said received start signal;

measuring an elapsed time from the start of said period;

judging an end of said period based on the elapsed time based on the start of said period and said start signal; and

outputting a signal for notifying a result of the judgment of the start and end of said period.

25. A communication method where a receiving process applied to a second wireless communication system using a second frequency band wider than a first frequency band used in a first wireless communication system, comprising:

receiving a start signal for notifying that a period during which communication is started in said second wireless communication system and an end signal for notifying that a period during which communication is ended in said second wireless communication system;

demodulating and/or decoding the start signal and the end signal;

judging the start of the period during which said second radio communication system occupies the radio medium based on said received start signal;

judging the end of said period based on said end signal received; and

outputting a signal for notifying a result of the judgment of the start and end of said period.

26. A transmitter comprising:

an interval start judgment circuit for judging a start of an interval based on a received notification signal which is a start signal for notifying that the period during which communication is performed in said second radio communication system using a second frequency band wider than a first frequency band used in a first radio communication system starts;

a counter circuit which starts a counter based on an output signal of the interval start judgment circuit, the counter counting a time elapsed from the start of the interval;

an interval end judgment circuit for judging an end of the interval in combination with the output of the counter circuit according to information about the interval included in the received notification signal;

a transmission control circuit for controlling a transmitting circuit based on the output signal of the interval start judgment circuit and the output signal of the interval end judgment circuit.

27. A transmission method comprising:

receiving a notification signal which is a start signal for notifying that the period during which communication is performed in said second radio communication system using a second frequency band wider than a first frequency band used in a first radio communication system starts;

judging a start of an interval based on the notification signal and providing an output start signal based on the judging of the start of the interval;

start counting based on the output signal and counting a time elapsed from the start of the interval and outputting a counting output;

judging an end of the interval in combination with the counting output according to information about the interval included in the notification signal and providing an output end signal based on the judging of the end of the interval;

controlling a transmission based on the output start signal and the output end signal.