Wireless LAN system

• US 20050243843A1
• Filed: 04/28/2005
• Published: 11/03/2005
• 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: Nakashima, Daiichiro, Imamura, Kimihiko
• Granted Patent: US 7,561,510 B2
• Time in Patent Office: Days
• US Class Current: 370/401
• 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 transmitter 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:

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.

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 any one of 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 any one of claim 1, wherein said transmission section transmits said occupation signal intermittently.

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

8. The transmitter according to any one of 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 any one of 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. 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 thinning circuit for cutting out and outputting one n-th of an occupation signal received from the transmitter according to claim 3;

and

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

11. 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 start judgment section for judging the start of the period during which said second radio communication system occupies the radio medium based on said start signal received from the transmitter according to claim 7;

a measurement section for measuring the 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. 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 start judgment section for judging the start of the period during which said second radio communication system occupies the radio medium based on said start signal received from the transmitter according to claim 7;

an end judgment section for judging the end of said period based on said end signal received from the transmitter according to claim 7;

and

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

13. 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 recognition section for recognizing said identification information based on said occupation signal received from the transmitter according to claim 8;

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. An access point, comprising the transmitter according to any one of claim 1.

15. A station, comprising at least one of the receivers according to claim 10.

16. A wireless LAN system, comprising the access point according to claim 14 and the station according to claim 15.